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51580e79 | 1 | /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
969bf05e | 2 | * Copyright (c) 2016 Facebook |
51580e79 AS |
3 | * |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | */ | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/bpf.h> | |
58e2af8b | 17 | #include <linux/bpf_verifier.h> |
51580e79 AS |
18 | #include <linux/filter.h> |
19 | #include <net/netlink.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/vmalloc.h> | |
ebb676da | 22 | #include <linux/stringify.h> |
51580e79 | 23 | |
f4ac7e0b JK |
24 | #include "disasm.h" |
25 | ||
00176a34 JK |
26 | static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { |
27 | #define BPF_PROG_TYPE(_id, _name) \ | |
28 | [_id] = & _name ## _verifier_ops, | |
29 | #define BPF_MAP_TYPE(_id, _ops) | |
30 | #include <linux/bpf_types.h> | |
31 | #undef BPF_PROG_TYPE | |
32 | #undef BPF_MAP_TYPE | |
33 | }; | |
34 | ||
51580e79 AS |
35 | /* bpf_check() is a static code analyzer that walks eBPF program |
36 | * instruction by instruction and updates register/stack state. | |
37 | * All paths of conditional branches are analyzed until 'bpf_exit' insn. | |
38 | * | |
39 | * The first pass is depth-first-search to check that the program is a DAG. | |
40 | * It rejects the following programs: | |
41 | * - larger than BPF_MAXINSNS insns | |
42 | * - if loop is present (detected via back-edge) | |
43 | * - unreachable insns exist (shouldn't be a forest. program = one function) | |
44 | * - out of bounds or malformed jumps | |
45 | * The second pass is all possible path descent from the 1st insn. | |
46 | * Since it's analyzing all pathes through the program, the length of the | |
eba38a96 | 47 | * analysis is limited to 64k insn, which may be hit even if total number of |
51580e79 AS |
48 | * insn is less then 4K, but there are too many branches that change stack/regs. |
49 | * Number of 'branches to be analyzed' is limited to 1k | |
50 | * | |
51 | * On entry to each instruction, each register has a type, and the instruction | |
52 | * changes the types of the registers depending on instruction semantics. | |
53 | * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is | |
54 | * copied to R1. | |
55 | * | |
56 | * All registers are 64-bit. | |
57 | * R0 - return register | |
58 | * R1-R5 argument passing registers | |
59 | * R6-R9 callee saved registers | |
60 | * R10 - frame pointer read-only | |
61 | * | |
62 | * At the start of BPF program the register R1 contains a pointer to bpf_context | |
63 | * and has type PTR_TO_CTX. | |
64 | * | |
65 | * Verifier tracks arithmetic operations on pointers in case: | |
66 | * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), | |
67 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), | |
68 | * 1st insn copies R10 (which has FRAME_PTR) type into R1 | |
69 | * and 2nd arithmetic instruction is pattern matched to recognize | |
70 | * that it wants to construct a pointer to some element within stack. | |
71 | * So after 2nd insn, the register R1 has type PTR_TO_STACK | |
72 | * (and -20 constant is saved for further stack bounds checking). | |
73 | * Meaning that this reg is a pointer to stack plus known immediate constant. | |
74 | * | |
f1174f77 | 75 | * Most of the time the registers have SCALAR_VALUE type, which |
51580e79 | 76 | * means the register has some value, but it's not a valid pointer. |
f1174f77 | 77 | * (like pointer plus pointer becomes SCALAR_VALUE type) |
51580e79 AS |
78 | * |
79 | * When verifier sees load or store instructions the type of base register | |
f1174f77 | 80 | * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer |
51580e79 AS |
81 | * types recognized by check_mem_access() function. |
82 | * | |
83 | * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' | |
84 | * and the range of [ptr, ptr + map's value_size) is accessible. | |
85 | * | |
86 | * registers used to pass values to function calls are checked against | |
87 | * function argument constraints. | |
88 | * | |
89 | * ARG_PTR_TO_MAP_KEY is one of such argument constraints. | |
90 | * It means that the register type passed to this function must be | |
91 | * PTR_TO_STACK and it will be used inside the function as | |
92 | * 'pointer to map element key' | |
93 | * | |
94 | * For example the argument constraints for bpf_map_lookup_elem(): | |
95 | * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, | |
96 | * .arg1_type = ARG_CONST_MAP_PTR, | |
97 | * .arg2_type = ARG_PTR_TO_MAP_KEY, | |
98 | * | |
99 | * ret_type says that this function returns 'pointer to map elem value or null' | |
100 | * function expects 1st argument to be a const pointer to 'struct bpf_map' and | |
101 | * 2nd argument should be a pointer to stack, which will be used inside | |
102 | * the helper function as a pointer to map element key. | |
103 | * | |
104 | * On the kernel side the helper function looks like: | |
105 | * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
106 | * { | |
107 | * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
108 | * void *key = (void *) (unsigned long) r2; | |
109 | * void *value; | |
110 | * | |
111 | * here kernel can access 'key' and 'map' pointers safely, knowing that | |
112 | * [key, key + map->key_size) bytes are valid and were initialized on | |
113 | * the stack of eBPF program. | |
114 | * } | |
115 | * | |
116 | * Corresponding eBPF program may look like: | |
117 | * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR | |
118 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK | |
119 | * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP | |
120 | * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
121 | * here verifier looks at prototype of map_lookup_elem() and sees: | |
122 | * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, | |
123 | * Now verifier knows that this map has key of R1->map_ptr->key_size bytes | |
124 | * | |
125 | * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, | |
126 | * Now verifier checks that [R2, R2 + map's key_size) are within stack limits | |
127 | * and were initialized prior to this call. | |
128 | * If it's ok, then verifier allows this BPF_CALL insn and looks at | |
129 | * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets | |
130 | * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function | |
131 | * returns ether pointer to map value or NULL. | |
132 | * | |
133 | * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' | |
134 | * insn, the register holding that pointer in the true branch changes state to | |
135 | * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false | |
136 | * branch. See check_cond_jmp_op(). | |
137 | * | |
138 | * After the call R0 is set to return type of the function and registers R1-R5 | |
139 | * are set to NOT_INIT to indicate that they are no longer readable. | |
140 | */ | |
141 | ||
17a52670 | 142 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ |
58e2af8b | 143 | struct bpf_verifier_stack_elem { |
17a52670 AS |
144 | /* verifer state is 'st' |
145 | * before processing instruction 'insn_idx' | |
146 | * and after processing instruction 'prev_insn_idx' | |
147 | */ | |
58e2af8b | 148 | struct bpf_verifier_state st; |
17a52670 AS |
149 | int insn_idx; |
150 | int prev_insn_idx; | |
58e2af8b | 151 | struct bpf_verifier_stack_elem *next; |
cbd35700 AS |
152 | }; |
153 | ||
8e17c1b1 | 154 | #define BPF_COMPLEXITY_LIMIT_INSNS 131072 |
07016151 DB |
155 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 |
156 | ||
fad73a1a MKL |
157 | #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) |
158 | ||
33ff9823 DB |
159 | struct bpf_call_arg_meta { |
160 | struct bpf_map *map_ptr; | |
435faee1 | 161 | bool raw_mode; |
36bbef52 | 162 | bool pkt_access; |
435faee1 DB |
163 | int regno; |
164 | int access_size; | |
33ff9823 DB |
165 | }; |
166 | ||
cbd35700 AS |
167 | static DEFINE_MUTEX(bpf_verifier_lock); |
168 | ||
169 | /* log_level controls verbosity level of eBPF verifier. | |
170 | * verbose() is used to dump the verification trace to the log, so the user | |
171 | * can figure out what's wrong with the program | |
172 | */ | |
61bd5218 JK |
173 | static __printf(2, 3) void verbose(struct bpf_verifier_env *env, |
174 | const char *fmt, ...) | |
cbd35700 | 175 | { |
61bd5218 | 176 | struct bpf_verifer_log *log = &env->log; |
a2a7d570 | 177 | unsigned int n; |
cbd35700 AS |
178 | va_list args; |
179 | ||
a2a7d570 | 180 | if (!log->level || !log->ubuf || bpf_verifier_log_full(log)) |
cbd35700 AS |
181 | return; |
182 | ||
183 | va_start(args, fmt); | |
a2a7d570 | 184 | n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args); |
cbd35700 | 185 | va_end(args); |
a2a7d570 JK |
186 | |
187 | WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, | |
188 | "verifier log line truncated - local buffer too short\n"); | |
189 | ||
190 | n = min(log->len_total - log->len_used - 1, n); | |
191 | log->kbuf[n] = '\0'; | |
192 | ||
193 | if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1)) | |
194 | log->len_used += n; | |
195 | else | |
196 | log->ubuf = NULL; | |
cbd35700 AS |
197 | } |
198 | ||
de8f3a83 DB |
199 | static bool type_is_pkt_pointer(enum bpf_reg_type type) |
200 | { | |
201 | return type == PTR_TO_PACKET || | |
202 | type == PTR_TO_PACKET_META; | |
203 | } | |
204 | ||
17a52670 AS |
205 | /* string representation of 'enum bpf_reg_type' */ |
206 | static const char * const reg_type_str[] = { | |
207 | [NOT_INIT] = "?", | |
f1174f77 | 208 | [SCALAR_VALUE] = "inv", |
17a52670 AS |
209 | [PTR_TO_CTX] = "ctx", |
210 | [CONST_PTR_TO_MAP] = "map_ptr", | |
211 | [PTR_TO_MAP_VALUE] = "map_value", | |
212 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
17a52670 | 213 | [PTR_TO_STACK] = "fp", |
969bf05e | 214 | [PTR_TO_PACKET] = "pkt", |
de8f3a83 | 215 | [PTR_TO_PACKET_META] = "pkt_meta", |
969bf05e | 216 | [PTR_TO_PACKET_END] = "pkt_end", |
17a52670 AS |
217 | }; |
218 | ||
61bd5218 JK |
219 | static void print_verifier_state(struct bpf_verifier_env *env, |
220 | struct bpf_verifier_state *state) | |
17a52670 | 221 | { |
58e2af8b | 222 | struct bpf_reg_state *reg; |
17a52670 AS |
223 | enum bpf_reg_type t; |
224 | int i; | |
225 | ||
226 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
227 | reg = &state->regs[i]; |
228 | t = reg->type; | |
17a52670 AS |
229 | if (t == NOT_INIT) |
230 | continue; | |
61bd5218 | 231 | verbose(env, " R%d=%s", i, reg_type_str[t]); |
f1174f77 EC |
232 | if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && |
233 | tnum_is_const(reg->var_off)) { | |
234 | /* reg->off should be 0 for SCALAR_VALUE */ | |
61bd5218 | 235 | verbose(env, "%lld", reg->var_off.value + reg->off); |
f1174f77 | 236 | } else { |
61bd5218 | 237 | verbose(env, "(id=%d", reg->id); |
f1174f77 | 238 | if (t != SCALAR_VALUE) |
61bd5218 | 239 | verbose(env, ",off=%d", reg->off); |
de8f3a83 | 240 | if (type_is_pkt_pointer(t)) |
61bd5218 | 241 | verbose(env, ",r=%d", reg->range); |
f1174f77 EC |
242 | else if (t == CONST_PTR_TO_MAP || |
243 | t == PTR_TO_MAP_VALUE || | |
244 | t == PTR_TO_MAP_VALUE_OR_NULL) | |
61bd5218 | 245 | verbose(env, ",ks=%d,vs=%d", |
f1174f77 EC |
246 | reg->map_ptr->key_size, |
247 | reg->map_ptr->value_size); | |
7d1238f2 EC |
248 | if (tnum_is_const(reg->var_off)) { |
249 | /* Typically an immediate SCALAR_VALUE, but | |
250 | * could be a pointer whose offset is too big | |
251 | * for reg->off | |
252 | */ | |
61bd5218 | 253 | verbose(env, ",imm=%llx", reg->var_off.value); |
7d1238f2 EC |
254 | } else { |
255 | if (reg->smin_value != reg->umin_value && | |
256 | reg->smin_value != S64_MIN) | |
61bd5218 | 257 | verbose(env, ",smin_value=%lld", |
7d1238f2 EC |
258 | (long long)reg->smin_value); |
259 | if (reg->smax_value != reg->umax_value && | |
260 | reg->smax_value != S64_MAX) | |
61bd5218 | 261 | verbose(env, ",smax_value=%lld", |
7d1238f2 EC |
262 | (long long)reg->smax_value); |
263 | if (reg->umin_value != 0) | |
61bd5218 | 264 | verbose(env, ",umin_value=%llu", |
7d1238f2 EC |
265 | (unsigned long long)reg->umin_value); |
266 | if (reg->umax_value != U64_MAX) | |
61bd5218 | 267 | verbose(env, ",umax_value=%llu", |
7d1238f2 EC |
268 | (unsigned long long)reg->umax_value); |
269 | if (!tnum_is_unknown(reg->var_off)) { | |
270 | char tn_buf[48]; | |
f1174f77 | 271 | |
7d1238f2 | 272 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); |
61bd5218 | 273 | verbose(env, ",var_off=%s", tn_buf); |
7d1238f2 | 274 | } |
f1174f77 | 275 | } |
61bd5218 | 276 | verbose(env, ")"); |
f1174f77 | 277 | } |
17a52670 | 278 | } |
638f5b90 AS |
279 | for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { |
280 | if (state->stack[i].slot_type[0] == STACK_SPILL) | |
281 | verbose(env, " fp%d=%s", | |
282 | -MAX_BPF_STACK + i * BPF_REG_SIZE, | |
283 | reg_type_str[state->stack[i].spilled_ptr.type]); | |
17a52670 | 284 | } |
61bd5218 | 285 | verbose(env, "\n"); |
17a52670 AS |
286 | } |
287 | ||
638f5b90 AS |
288 | static int copy_stack_state(struct bpf_verifier_state *dst, |
289 | const struct bpf_verifier_state *src) | |
17a52670 | 290 | { |
638f5b90 AS |
291 | if (!src->stack) |
292 | return 0; | |
293 | if (WARN_ON_ONCE(dst->allocated_stack < src->allocated_stack)) { | |
294 | /* internal bug, make state invalid to reject the program */ | |
295 | memset(dst, 0, sizeof(*dst)); | |
296 | return -EFAULT; | |
297 | } | |
298 | memcpy(dst->stack, src->stack, | |
299 | sizeof(*src->stack) * (src->allocated_stack / BPF_REG_SIZE)); | |
300 | return 0; | |
301 | } | |
302 | ||
303 | /* do_check() starts with zero-sized stack in struct bpf_verifier_state to | |
304 | * make it consume minimal amount of memory. check_stack_write() access from | |
305 | * the program calls into realloc_verifier_state() to grow the stack size. | |
306 | * Note there is a non-zero 'parent' pointer inside bpf_verifier_state | |
307 | * which this function copies over. It points to previous bpf_verifier_state | |
308 | * which is never reallocated | |
309 | */ | |
310 | static int realloc_verifier_state(struct bpf_verifier_state *state, int size, | |
311 | bool copy_old) | |
312 | { | |
313 | u32 old_size = state->allocated_stack; | |
314 | struct bpf_stack_state *new_stack; | |
315 | int slot = size / BPF_REG_SIZE; | |
316 | ||
317 | if (size <= old_size || !size) { | |
318 | if (copy_old) | |
319 | return 0; | |
320 | state->allocated_stack = slot * BPF_REG_SIZE; | |
321 | if (!size && old_size) { | |
322 | kfree(state->stack); | |
323 | state->stack = NULL; | |
324 | } | |
325 | return 0; | |
326 | } | |
327 | new_stack = kmalloc_array(slot, sizeof(struct bpf_stack_state), | |
328 | GFP_KERNEL); | |
329 | if (!new_stack) | |
330 | return -ENOMEM; | |
331 | if (copy_old) { | |
332 | if (state->stack) | |
333 | memcpy(new_stack, state->stack, | |
334 | sizeof(*new_stack) * (old_size / BPF_REG_SIZE)); | |
335 | memset(new_stack + old_size / BPF_REG_SIZE, 0, | |
336 | sizeof(*new_stack) * (size - old_size) / BPF_REG_SIZE); | |
337 | } | |
338 | state->allocated_stack = slot * BPF_REG_SIZE; | |
339 | kfree(state->stack); | |
340 | state->stack = new_stack; | |
341 | return 0; | |
342 | } | |
343 | ||
1969db47 AS |
344 | static void free_verifier_state(struct bpf_verifier_state *state, |
345 | bool free_self) | |
638f5b90 AS |
346 | { |
347 | kfree(state->stack); | |
1969db47 AS |
348 | if (free_self) |
349 | kfree(state); | |
638f5b90 AS |
350 | } |
351 | ||
352 | /* copy verifier state from src to dst growing dst stack space | |
353 | * when necessary to accommodate larger src stack | |
354 | */ | |
355 | static int copy_verifier_state(struct bpf_verifier_state *dst, | |
356 | const struct bpf_verifier_state *src) | |
357 | { | |
358 | int err; | |
359 | ||
360 | err = realloc_verifier_state(dst, src->allocated_stack, false); | |
361 | if (err) | |
362 | return err; | |
363 | memcpy(dst, src, offsetof(struct bpf_verifier_state, allocated_stack)); | |
364 | return copy_stack_state(dst, src); | |
365 | } | |
366 | ||
367 | static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, | |
368 | int *insn_idx) | |
369 | { | |
370 | struct bpf_verifier_state *cur = env->cur_state; | |
371 | struct bpf_verifier_stack_elem *elem, *head = env->head; | |
372 | int err; | |
17a52670 AS |
373 | |
374 | if (env->head == NULL) | |
638f5b90 | 375 | return -ENOENT; |
17a52670 | 376 | |
638f5b90 AS |
377 | if (cur) { |
378 | err = copy_verifier_state(cur, &head->st); | |
379 | if (err) | |
380 | return err; | |
381 | } | |
382 | if (insn_idx) | |
383 | *insn_idx = head->insn_idx; | |
17a52670 | 384 | if (prev_insn_idx) |
638f5b90 AS |
385 | *prev_insn_idx = head->prev_insn_idx; |
386 | elem = head->next; | |
1969db47 | 387 | free_verifier_state(&head->st, false); |
638f5b90 | 388 | kfree(head); |
17a52670 AS |
389 | env->head = elem; |
390 | env->stack_size--; | |
638f5b90 | 391 | return 0; |
17a52670 AS |
392 | } |
393 | ||
58e2af8b JK |
394 | static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, |
395 | int insn_idx, int prev_insn_idx) | |
17a52670 | 396 | { |
638f5b90 | 397 | struct bpf_verifier_state *cur = env->cur_state; |
58e2af8b | 398 | struct bpf_verifier_stack_elem *elem; |
638f5b90 | 399 | int err; |
17a52670 | 400 | |
638f5b90 | 401 | elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); |
17a52670 AS |
402 | if (!elem) |
403 | goto err; | |
404 | ||
17a52670 AS |
405 | elem->insn_idx = insn_idx; |
406 | elem->prev_insn_idx = prev_insn_idx; | |
407 | elem->next = env->head; | |
408 | env->head = elem; | |
409 | env->stack_size++; | |
1969db47 AS |
410 | err = copy_verifier_state(&elem->st, cur); |
411 | if (err) | |
412 | goto err; | |
07016151 | 413 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
61bd5218 | 414 | verbose(env, "BPF program is too complex\n"); |
17a52670 AS |
415 | goto err; |
416 | } | |
417 | return &elem->st; | |
418 | err: | |
419 | /* pop all elements and return */ | |
638f5b90 | 420 | while (!pop_stack(env, NULL, NULL)); |
17a52670 AS |
421 | return NULL; |
422 | } | |
423 | ||
424 | #define CALLER_SAVED_REGS 6 | |
425 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
426 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
427 | }; | |
428 | ||
f1174f77 EC |
429 | static void __mark_reg_not_init(struct bpf_reg_state *reg); |
430 | ||
b03c9f9f EC |
431 | /* Mark the unknown part of a register (variable offset or scalar value) as |
432 | * known to have the value @imm. | |
433 | */ | |
434 | static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) | |
435 | { | |
436 | reg->id = 0; | |
437 | reg->var_off = tnum_const(imm); | |
438 | reg->smin_value = (s64)imm; | |
439 | reg->smax_value = (s64)imm; | |
440 | reg->umin_value = imm; | |
441 | reg->umax_value = imm; | |
442 | } | |
443 | ||
f1174f77 EC |
444 | /* Mark the 'variable offset' part of a register as zero. This should be |
445 | * used only on registers holding a pointer type. | |
446 | */ | |
447 | static void __mark_reg_known_zero(struct bpf_reg_state *reg) | |
a9789ef9 | 448 | { |
b03c9f9f | 449 | __mark_reg_known(reg, 0); |
f1174f77 | 450 | } |
a9789ef9 | 451 | |
61bd5218 JK |
452 | static void mark_reg_known_zero(struct bpf_verifier_env *env, |
453 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
454 | { |
455 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 456 | verbose(env, "mark_reg_known_zero(regs, %u)\n", regno); |
f1174f77 EC |
457 | /* Something bad happened, let's kill all regs */ |
458 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
459 | __mark_reg_not_init(regs + regno); | |
460 | return; | |
461 | } | |
462 | __mark_reg_known_zero(regs + regno); | |
463 | } | |
464 | ||
de8f3a83 DB |
465 | static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) |
466 | { | |
467 | return type_is_pkt_pointer(reg->type); | |
468 | } | |
469 | ||
470 | static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg) | |
471 | { | |
472 | return reg_is_pkt_pointer(reg) || | |
473 | reg->type == PTR_TO_PACKET_END; | |
474 | } | |
475 | ||
476 | /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */ | |
477 | static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, | |
478 | enum bpf_reg_type which) | |
479 | { | |
480 | /* The register can already have a range from prior markings. | |
481 | * This is fine as long as it hasn't been advanced from its | |
482 | * origin. | |
483 | */ | |
484 | return reg->type == which && | |
485 | reg->id == 0 && | |
486 | reg->off == 0 && | |
487 | tnum_equals_const(reg->var_off, 0); | |
488 | } | |
489 | ||
b03c9f9f EC |
490 | /* Attempts to improve min/max values based on var_off information */ |
491 | static void __update_reg_bounds(struct bpf_reg_state *reg) | |
492 | { | |
493 | /* min signed is max(sign bit) | min(other bits) */ | |
494 | reg->smin_value = max_t(s64, reg->smin_value, | |
495 | reg->var_off.value | (reg->var_off.mask & S64_MIN)); | |
496 | /* max signed is min(sign bit) | max(other bits) */ | |
497 | reg->smax_value = min_t(s64, reg->smax_value, | |
498 | reg->var_off.value | (reg->var_off.mask & S64_MAX)); | |
499 | reg->umin_value = max(reg->umin_value, reg->var_off.value); | |
500 | reg->umax_value = min(reg->umax_value, | |
501 | reg->var_off.value | reg->var_off.mask); | |
502 | } | |
503 | ||
504 | /* Uses signed min/max values to inform unsigned, and vice-versa */ | |
505 | static void __reg_deduce_bounds(struct bpf_reg_state *reg) | |
506 | { | |
507 | /* Learn sign from signed bounds. | |
508 | * If we cannot cross the sign boundary, then signed and unsigned bounds | |
509 | * are the same, so combine. This works even in the negative case, e.g. | |
510 | * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. | |
511 | */ | |
512 | if (reg->smin_value >= 0 || reg->smax_value < 0) { | |
513 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
514 | reg->umin_value); | |
515 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
516 | reg->umax_value); | |
517 | return; | |
518 | } | |
519 | /* Learn sign from unsigned bounds. Signed bounds cross the sign | |
520 | * boundary, so we must be careful. | |
521 | */ | |
522 | if ((s64)reg->umax_value >= 0) { | |
523 | /* Positive. We can't learn anything from the smin, but smax | |
524 | * is positive, hence safe. | |
525 | */ | |
526 | reg->smin_value = reg->umin_value; | |
527 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
528 | reg->umax_value); | |
529 | } else if ((s64)reg->umin_value < 0) { | |
530 | /* Negative. We can't learn anything from the smax, but smin | |
531 | * is negative, hence safe. | |
532 | */ | |
533 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
534 | reg->umin_value); | |
535 | reg->smax_value = reg->umax_value; | |
536 | } | |
537 | } | |
538 | ||
539 | /* Attempts to improve var_off based on unsigned min/max information */ | |
540 | static void __reg_bound_offset(struct bpf_reg_state *reg) | |
541 | { | |
542 | reg->var_off = tnum_intersect(reg->var_off, | |
543 | tnum_range(reg->umin_value, | |
544 | reg->umax_value)); | |
545 | } | |
546 | ||
547 | /* Reset the min/max bounds of a register */ | |
548 | static void __mark_reg_unbounded(struct bpf_reg_state *reg) | |
549 | { | |
550 | reg->smin_value = S64_MIN; | |
551 | reg->smax_value = S64_MAX; | |
552 | reg->umin_value = 0; | |
553 | reg->umax_value = U64_MAX; | |
554 | } | |
555 | ||
f1174f77 EC |
556 | /* Mark a register as having a completely unknown (scalar) value. */ |
557 | static void __mark_reg_unknown(struct bpf_reg_state *reg) | |
558 | { | |
559 | reg->type = SCALAR_VALUE; | |
560 | reg->id = 0; | |
561 | reg->off = 0; | |
562 | reg->var_off = tnum_unknown; | |
b03c9f9f | 563 | __mark_reg_unbounded(reg); |
f1174f77 EC |
564 | } |
565 | ||
61bd5218 JK |
566 | static void mark_reg_unknown(struct bpf_verifier_env *env, |
567 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
568 | { |
569 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 570 | verbose(env, "mark_reg_unknown(regs, %u)\n", regno); |
f1174f77 EC |
571 | /* Something bad happened, let's kill all regs */ |
572 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
573 | __mark_reg_not_init(regs + regno); | |
574 | return; | |
575 | } | |
576 | __mark_reg_unknown(regs + regno); | |
577 | } | |
578 | ||
579 | static void __mark_reg_not_init(struct bpf_reg_state *reg) | |
580 | { | |
581 | __mark_reg_unknown(reg); | |
582 | reg->type = NOT_INIT; | |
583 | } | |
584 | ||
61bd5218 JK |
585 | static void mark_reg_not_init(struct bpf_verifier_env *env, |
586 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
587 | { |
588 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 589 | verbose(env, "mark_reg_not_init(regs, %u)\n", regno); |
f1174f77 EC |
590 | /* Something bad happened, let's kill all regs */ |
591 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
592 | __mark_reg_not_init(regs + regno); | |
593 | return; | |
594 | } | |
595 | __mark_reg_not_init(regs + regno); | |
a9789ef9 DB |
596 | } |
597 | ||
61bd5218 JK |
598 | static void init_reg_state(struct bpf_verifier_env *env, |
599 | struct bpf_reg_state *regs) | |
17a52670 AS |
600 | { |
601 | int i; | |
602 | ||
dc503a8a | 603 | for (i = 0; i < MAX_BPF_REG; i++) { |
61bd5218 | 604 | mark_reg_not_init(env, regs, i); |
dc503a8a EC |
605 | regs[i].live = REG_LIVE_NONE; |
606 | } | |
17a52670 AS |
607 | |
608 | /* frame pointer */ | |
f1174f77 | 609 | regs[BPF_REG_FP].type = PTR_TO_STACK; |
61bd5218 | 610 | mark_reg_known_zero(env, regs, BPF_REG_FP); |
17a52670 AS |
611 | |
612 | /* 1st arg to a function */ | |
613 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
61bd5218 | 614 | mark_reg_known_zero(env, regs, BPF_REG_1); |
6760bf2d DB |
615 | } |
616 | ||
17a52670 AS |
617 | enum reg_arg_type { |
618 | SRC_OP, /* register is used as source operand */ | |
619 | DST_OP, /* register is used as destination operand */ | |
620 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
621 | }; | |
622 | ||
dc503a8a EC |
623 | static void mark_reg_read(const struct bpf_verifier_state *state, u32 regno) |
624 | { | |
625 | struct bpf_verifier_state *parent = state->parent; | |
626 | ||
8fe2d6cc AS |
627 | if (regno == BPF_REG_FP) |
628 | /* We don't need to worry about FP liveness because it's read-only */ | |
629 | return; | |
630 | ||
dc503a8a EC |
631 | while (parent) { |
632 | /* if read wasn't screened by an earlier write ... */ | |
633 | if (state->regs[regno].live & REG_LIVE_WRITTEN) | |
634 | break; | |
635 | /* ... then we depend on parent's value */ | |
636 | parent->regs[regno].live |= REG_LIVE_READ; | |
637 | state = parent; | |
638 | parent = state->parent; | |
639 | } | |
640 | } | |
641 | ||
642 | static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, | |
17a52670 AS |
643 | enum reg_arg_type t) |
644 | { | |
638f5b90 | 645 | struct bpf_reg_state *regs = env->cur_state->regs; |
dc503a8a | 646 | |
17a52670 | 647 | if (regno >= MAX_BPF_REG) { |
61bd5218 | 648 | verbose(env, "R%d is invalid\n", regno); |
17a52670 AS |
649 | return -EINVAL; |
650 | } | |
651 | ||
652 | if (t == SRC_OP) { | |
653 | /* check whether register used as source operand can be read */ | |
654 | if (regs[regno].type == NOT_INIT) { | |
61bd5218 | 655 | verbose(env, "R%d !read_ok\n", regno); |
17a52670 AS |
656 | return -EACCES; |
657 | } | |
638f5b90 | 658 | mark_reg_read(env->cur_state, regno); |
17a52670 AS |
659 | } else { |
660 | /* check whether register used as dest operand can be written to */ | |
661 | if (regno == BPF_REG_FP) { | |
61bd5218 | 662 | verbose(env, "frame pointer is read only\n"); |
17a52670 AS |
663 | return -EACCES; |
664 | } | |
dc503a8a | 665 | regs[regno].live |= REG_LIVE_WRITTEN; |
17a52670 | 666 | if (t == DST_OP) |
61bd5218 | 667 | mark_reg_unknown(env, regs, regno); |
17a52670 AS |
668 | } |
669 | return 0; | |
670 | } | |
671 | ||
1be7f75d AS |
672 | static bool is_spillable_regtype(enum bpf_reg_type type) |
673 | { | |
674 | switch (type) { | |
675 | case PTR_TO_MAP_VALUE: | |
676 | case PTR_TO_MAP_VALUE_OR_NULL: | |
677 | case PTR_TO_STACK: | |
678 | case PTR_TO_CTX: | |
969bf05e | 679 | case PTR_TO_PACKET: |
de8f3a83 | 680 | case PTR_TO_PACKET_META: |
969bf05e | 681 | case PTR_TO_PACKET_END: |
1be7f75d AS |
682 | case CONST_PTR_TO_MAP: |
683 | return true; | |
684 | default: | |
685 | return false; | |
686 | } | |
687 | } | |
688 | ||
17a52670 AS |
689 | /* check_stack_read/write functions track spill/fill of registers, |
690 | * stack boundary and alignment are checked in check_mem_access() | |
691 | */ | |
61bd5218 JK |
692 | static int check_stack_write(struct bpf_verifier_env *env, |
693 | struct bpf_verifier_state *state, int off, | |
58e2af8b | 694 | int size, int value_regno) |
17a52670 | 695 | { |
638f5b90 AS |
696 | int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err; |
697 | ||
698 | err = realloc_verifier_state(state, round_up(slot + 1, BPF_REG_SIZE), | |
699 | true); | |
700 | if (err) | |
701 | return err; | |
9c399760 AS |
702 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
703 | * so it's aligned access and [off, off + size) are within stack limits | |
704 | */ | |
638f5b90 AS |
705 | if (!env->allow_ptr_leaks && |
706 | state->stack[spi].slot_type[0] == STACK_SPILL && | |
707 | size != BPF_REG_SIZE) { | |
708 | verbose(env, "attempt to corrupt spilled pointer on stack\n"); | |
709 | return -EACCES; | |
710 | } | |
17a52670 AS |
711 | |
712 | if (value_regno >= 0 && | |
1be7f75d | 713 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
714 | |
715 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 716 | if (size != BPF_REG_SIZE) { |
61bd5218 | 717 | verbose(env, "invalid size of register spill\n"); |
17a52670 AS |
718 | return -EACCES; |
719 | } | |
720 | ||
17a52670 | 721 | /* save register state */ |
638f5b90 AS |
722 | state->stack[spi].spilled_ptr = state->regs[value_regno]; |
723 | state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN; | |
17a52670 | 724 | |
9c399760 | 725 | for (i = 0; i < BPF_REG_SIZE; i++) |
638f5b90 | 726 | state->stack[spi].slot_type[i] = STACK_SPILL; |
9c399760 | 727 | } else { |
17a52670 | 728 | /* regular write of data into stack */ |
638f5b90 | 729 | state->stack[spi].spilled_ptr = (struct bpf_reg_state) {}; |
9c399760 AS |
730 | |
731 | for (i = 0; i < size; i++) | |
638f5b90 AS |
732 | state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = |
733 | STACK_MISC; | |
17a52670 AS |
734 | } |
735 | return 0; | |
736 | } | |
737 | ||
dc503a8a EC |
738 | static void mark_stack_slot_read(const struct bpf_verifier_state *state, int slot) |
739 | { | |
740 | struct bpf_verifier_state *parent = state->parent; | |
741 | ||
742 | while (parent) { | |
743 | /* if read wasn't screened by an earlier write ... */ | |
638f5b90 | 744 | if (state->stack[slot].spilled_ptr.live & REG_LIVE_WRITTEN) |
dc503a8a EC |
745 | break; |
746 | /* ... then we depend on parent's value */ | |
638f5b90 | 747 | parent->stack[slot].spilled_ptr.live |= REG_LIVE_READ; |
dc503a8a EC |
748 | state = parent; |
749 | parent = state->parent; | |
750 | } | |
751 | } | |
752 | ||
61bd5218 JK |
753 | static int check_stack_read(struct bpf_verifier_env *env, |
754 | struct bpf_verifier_state *state, int off, int size, | |
17a52670 AS |
755 | int value_regno) |
756 | { | |
638f5b90 AS |
757 | int i, slot = -off - 1, spi = slot / BPF_REG_SIZE; |
758 | u8 *stype; | |
17a52670 | 759 | |
638f5b90 AS |
760 | if (state->allocated_stack <= slot) { |
761 | verbose(env, "invalid read from stack off %d+0 size %d\n", | |
762 | off, size); | |
763 | return -EACCES; | |
764 | } | |
765 | stype = state->stack[spi].slot_type; | |
17a52670 | 766 | |
638f5b90 | 767 | if (stype[0] == STACK_SPILL) { |
9c399760 | 768 | if (size != BPF_REG_SIZE) { |
61bd5218 | 769 | verbose(env, "invalid size of register spill\n"); |
17a52670 AS |
770 | return -EACCES; |
771 | } | |
9c399760 | 772 | for (i = 1; i < BPF_REG_SIZE; i++) { |
638f5b90 | 773 | if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) { |
61bd5218 | 774 | verbose(env, "corrupted spill memory\n"); |
17a52670 AS |
775 | return -EACCES; |
776 | } | |
777 | } | |
778 | ||
dc503a8a | 779 | if (value_regno >= 0) { |
17a52670 | 780 | /* restore register state from stack */ |
638f5b90 | 781 | state->regs[value_regno] = state->stack[spi].spilled_ptr; |
dc503a8a EC |
782 | mark_stack_slot_read(state, spi); |
783 | } | |
17a52670 AS |
784 | return 0; |
785 | } else { | |
786 | for (i = 0; i < size; i++) { | |
638f5b90 | 787 | if (stype[(slot - i) % BPF_REG_SIZE] != STACK_MISC) { |
61bd5218 | 788 | verbose(env, "invalid read from stack off %d+%d size %d\n", |
17a52670 AS |
789 | off, i, size); |
790 | return -EACCES; | |
791 | } | |
792 | } | |
793 | if (value_regno >= 0) | |
794 | /* have read misc data from the stack */ | |
61bd5218 | 795 | mark_reg_unknown(env, state->regs, value_regno); |
17a52670 AS |
796 | return 0; |
797 | } | |
798 | } | |
799 | ||
800 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
f1174f77 | 801 | static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off, |
9fd29c08 | 802 | int size, bool zero_size_allowed) |
17a52670 | 803 | { |
638f5b90 AS |
804 | struct bpf_reg_state *regs = cur_regs(env); |
805 | struct bpf_map *map = regs[regno].map_ptr; | |
17a52670 | 806 | |
9fd29c08 YS |
807 | if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) || |
808 | off + size > map->value_size) { | |
61bd5218 | 809 | verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", |
17a52670 AS |
810 | map->value_size, off, size); |
811 | return -EACCES; | |
812 | } | |
813 | return 0; | |
814 | } | |
815 | ||
f1174f77 EC |
816 | /* check read/write into a map element with possible variable offset */ |
817 | static int check_map_access(struct bpf_verifier_env *env, u32 regno, | |
9fd29c08 | 818 | int off, int size, bool zero_size_allowed) |
dbcfe5f7 | 819 | { |
638f5b90 | 820 | struct bpf_verifier_state *state = env->cur_state; |
dbcfe5f7 GB |
821 | struct bpf_reg_state *reg = &state->regs[regno]; |
822 | int err; | |
823 | ||
f1174f77 EC |
824 | /* We may have adjusted the register to this map value, so we |
825 | * need to try adding each of min_value and max_value to off | |
826 | * to make sure our theoretical access will be safe. | |
dbcfe5f7 | 827 | */ |
61bd5218 JK |
828 | if (env->log.level) |
829 | print_verifier_state(env, state); | |
dbcfe5f7 GB |
830 | /* The minimum value is only important with signed |
831 | * comparisons where we can't assume the floor of a | |
832 | * value is 0. If we are using signed variables for our | |
833 | * index'es we need to make sure that whatever we use | |
834 | * will have a set floor within our range. | |
835 | */ | |
b03c9f9f | 836 | if (reg->smin_value < 0) { |
61bd5218 | 837 | verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
dbcfe5f7 GB |
838 | regno); |
839 | return -EACCES; | |
840 | } | |
9fd29c08 YS |
841 | err = __check_map_access(env, regno, reg->smin_value + off, size, |
842 | zero_size_allowed); | |
dbcfe5f7 | 843 | if (err) { |
61bd5218 JK |
844 | verbose(env, "R%d min value is outside of the array range\n", |
845 | regno); | |
dbcfe5f7 GB |
846 | return err; |
847 | } | |
848 | ||
b03c9f9f EC |
849 | /* If we haven't set a max value then we need to bail since we can't be |
850 | * sure we won't do bad things. | |
851 | * If reg->umax_value + off could overflow, treat that as unbounded too. | |
dbcfe5f7 | 852 | */ |
b03c9f9f | 853 | if (reg->umax_value >= BPF_MAX_VAR_OFF) { |
61bd5218 | 854 | verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n", |
dbcfe5f7 GB |
855 | regno); |
856 | return -EACCES; | |
857 | } | |
9fd29c08 YS |
858 | err = __check_map_access(env, regno, reg->umax_value + off, size, |
859 | zero_size_allowed); | |
f1174f77 | 860 | if (err) |
61bd5218 JK |
861 | verbose(env, "R%d max value is outside of the array range\n", |
862 | regno); | |
f1174f77 | 863 | return err; |
dbcfe5f7 GB |
864 | } |
865 | ||
969bf05e AS |
866 | #define MAX_PACKET_OFF 0xffff |
867 | ||
58e2af8b | 868 | static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, |
3a0af8fd TG |
869 | const struct bpf_call_arg_meta *meta, |
870 | enum bpf_access_type t) | |
4acf6c0b | 871 | { |
36bbef52 | 872 | switch (env->prog->type) { |
3a0af8fd TG |
873 | case BPF_PROG_TYPE_LWT_IN: |
874 | case BPF_PROG_TYPE_LWT_OUT: | |
875 | /* dst_input() and dst_output() can't write for now */ | |
876 | if (t == BPF_WRITE) | |
877 | return false; | |
7e57fbb2 | 878 | /* fallthrough */ |
36bbef52 DB |
879 | case BPF_PROG_TYPE_SCHED_CLS: |
880 | case BPF_PROG_TYPE_SCHED_ACT: | |
4acf6c0b | 881 | case BPF_PROG_TYPE_XDP: |
3a0af8fd | 882 | case BPF_PROG_TYPE_LWT_XMIT: |
8a31db56 | 883 | case BPF_PROG_TYPE_SK_SKB: |
36bbef52 DB |
884 | if (meta) |
885 | return meta->pkt_access; | |
886 | ||
887 | env->seen_direct_write = true; | |
4acf6c0b BB |
888 | return true; |
889 | default: | |
890 | return false; | |
891 | } | |
892 | } | |
893 | ||
f1174f77 | 894 | static int __check_packet_access(struct bpf_verifier_env *env, u32 regno, |
9fd29c08 | 895 | int off, int size, bool zero_size_allowed) |
969bf05e | 896 | { |
638f5b90 | 897 | struct bpf_reg_state *regs = cur_regs(env); |
58e2af8b | 898 | struct bpf_reg_state *reg = ®s[regno]; |
969bf05e | 899 | |
9fd29c08 YS |
900 | if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) || |
901 | (u64)off + size > reg->range) { | |
61bd5218 | 902 | verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", |
d91b28ed | 903 | off, size, regno, reg->id, reg->off, reg->range); |
969bf05e AS |
904 | return -EACCES; |
905 | } | |
906 | return 0; | |
907 | } | |
908 | ||
f1174f77 | 909 | static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, |
9fd29c08 | 910 | int size, bool zero_size_allowed) |
f1174f77 | 911 | { |
638f5b90 | 912 | struct bpf_reg_state *regs = cur_regs(env); |
f1174f77 EC |
913 | struct bpf_reg_state *reg = ®s[regno]; |
914 | int err; | |
915 | ||
916 | /* We may have added a variable offset to the packet pointer; but any | |
917 | * reg->range we have comes after that. We are only checking the fixed | |
918 | * offset. | |
919 | */ | |
920 | ||
921 | /* We don't allow negative numbers, because we aren't tracking enough | |
922 | * detail to prove they're safe. | |
923 | */ | |
b03c9f9f | 924 | if (reg->smin_value < 0) { |
61bd5218 | 925 | verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
f1174f77 EC |
926 | regno); |
927 | return -EACCES; | |
928 | } | |
9fd29c08 | 929 | err = __check_packet_access(env, regno, off, size, zero_size_allowed); |
f1174f77 | 930 | if (err) { |
61bd5218 | 931 | verbose(env, "R%d offset is outside of the packet\n", regno); |
f1174f77 EC |
932 | return err; |
933 | } | |
934 | return err; | |
935 | } | |
936 | ||
937 | /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ | |
31fd8581 | 938 | static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, |
19de99f7 | 939 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 | 940 | { |
f96da094 DB |
941 | struct bpf_insn_access_aux info = { |
942 | .reg_type = *reg_type, | |
943 | }; | |
31fd8581 | 944 | |
4f9218aa JK |
945 | if (env->ops->is_valid_access && |
946 | env->ops->is_valid_access(off, size, t, &info)) { | |
f96da094 DB |
947 | /* A non zero info.ctx_field_size indicates that this field is a |
948 | * candidate for later verifier transformation to load the whole | |
949 | * field and then apply a mask when accessed with a narrower | |
950 | * access than actual ctx access size. A zero info.ctx_field_size | |
951 | * will only allow for whole field access and rejects any other | |
952 | * type of narrower access. | |
31fd8581 | 953 | */ |
23994631 | 954 | *reg_type = info.reg_type; |
31fd8581 | 955 | |
4f9218aa | 956 | env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; |
32bbe007 AS |
957 | /* remember the offset of last byte accessed in ctx */ |
958 | if (env->prog->aux->max_ctx_offset < off + size) | |
959 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 960 | return 0; |
32bbe007 | 961 | } |
17a52670 | 962 | |
61bd5218 | 963 | verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size); |
17a52670 AS |
964 | return -EACCES; |
965 | } | |
966 | ||
4cabc5b1 DB |
967 | static bool __is_pointer_value(bool allow_ptr_leaks, |
968 | const struct bpf_reg_state *reg) | |
1be7f75d | 969 | { |
4cabc5b1 | 970 | if (allow_ptr_leaks) |
1be7f75d AS |
971 | return false; |
972 | ||
f1174f77 | 973 | return reg->type != SCALAR_VALUE; |
1be7f75d AS |
974 | } |
975 | ||
4cabc5b1 DB |
976 | static bool is_pointer_value(struct bpf_verifier_env *env, int regno) |
977 | { | |
638f5b90 | 978 | return __is_pointer_value(env->allow_ptr_leaks, cur_regs(env) + regno); |
4cabc5b1 DB |
979 | } |
980 | ||
f37a8cb8 DB |
981 | static bool is_ctx_reg(struct bpf_verifier_env *env, int regno) |
982 | { | |
983 | const struct bpf_reg_state *reg = cur_regs(env) + regno; | |
984 | ||
985 | return reg->type == PTR_TO_CTX; | |
986 | } | |
987 | ||
61bd5218 JK |
988 | static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, |
989 | const struct bpf_reg_state *reg, | |
d1174416 | 990 | int off, int size, bool strict) |
969bf05e | 991 | { |
f1174f77 | 992 | struct tnum reg_off; |
e07b98d9 | 993 | int ip_align; |
d1174416 DM |
994 | |
995 | /* Byte size accesses are always allowed. */ | |
996 | if (!strict || size == 1) | |
997 | return 0; | |
998 | ||
e4eda884 DM |
999 | /* For platforms that do not have a Kconfig enabling |
1000 | * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of | |
1001 | * NET_IP_ALIGN is universally set to '2'. And on platforms | |
1002 | * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get | |
1003 | * to this code only in strict mode where we want to emulate | |
1004 | * the NET_IP_ALIGN==2 checking. Therefore use an | |
1005 | * unconditional IP align value of '2'. | |
e07b98d9 | 1006 | */ |
e4eda884 | 1007 | ip_align = 2; |
f1174f77 EC |
1008 | |
1009 | reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off)); | |
1010 | if (!tnum_is_aligned(reg_off, size)) { | |
1011 | char tn_buf[48]; | |
1012 | ||
1013 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 JK |
1014 | verbose(env, |
1015 | "misaligned packet access off %d+%s+%d+%d size %d\n", | |
f1174f77 | 1016 | ip_align, tn_buf, reg->off, off, size); |
969bf05e AS |
1017 | return -EACCES; |
1018 | } | |
79adffcd | 1019 | |
969bf05e AS |
1020 | return 0; |
1021 | } | |
1022 | ||
61bd5218 JK |
1023 | static int check_generic_ptr_alignment(struct bpf_verifier_env *env, |
1024 | const struct bpf_reg_state *reg, | |
f1174f77 EC |
1025 | const char *pointer_desc, |
1026 | int off, int size, bool strict) | |
79adffcd | 1027 | { |
f1174f77 EC |
1028 | struct tnum reg_off; |
1029 | ||
1030 | /* Byte size accesses are always allowed. */ | |
1031 | if (!strict || size == 1) | |
1032 | return 0; | |
1033 | ||
1034 | reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off)); | |
1035 | if (!tnum_is_aligned(reg_off, size)) { | |
1036 | char tn_buf[48]; | |
1037 | ||
1038 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 1039 | verbose(env, "misaligned %saccess off %s+%d+%d size %d\n", |
f1174f77 | 1040 | pointer_desc, tn_buf, reg->off, off, size); |
79adffcd DB |
1041 | return -EACCES; |
1042 | } | |
1043 | ||
969bf05e AS |
1044 | return 0; |
1045 | } | |
1046 | ||
e07b98d9 DM |
1047 | static int check_ptr_alignment(struct bpf_verifier_env *env, |
1048 | const struct bpf_reg_state *reg, | |
79adffcd DB |
1049 | int off, int size) |
1050 | { | |
e07b98d9 | 1051 | bool strict = env->strict_alignment; |
f1174f77 | 1052 | const char *pointer_desc = ""; |
d1174416 | 1053 | |
79adffcd DB |
1054 | switch (reg->type) { |
1055 | case PTR_TO_PACKET: | |
de8f3a83 DB |
1056 | case PTR_TO_PACKET_META: |
1057 | /* Special case, because of NET_IP_ALIGN. Given metadata sits | |
1058 | * right in front, treat it the very same way. | |
1059 | */ | |
61bd5218 | 1060 | return check_pkt_ptr_alignment(env, reg, off, size, strict); |
f1174f77 EC |
1061 | case PTR_TO_MAP_VALUE: |
1062 | pointer_desc = "value "; | |
1063 | break; | |
1064 | case PTR_TO_CTX: | |
1065 | pointer_desc = "context "; | |
1066 | break; | |
1067 | case PTR_TO_STACK: | |
1068 | pointer_desc = "stack "; | |
a5ec6ae1 JH |
1069 | /* The stack spill tracking logic in check_stack_write() |
1070 | * and check_stack_read() relies on stack accesses being | |
1071 | * aligned. | |
1072 | */ | |
1073 | strict = true; | |
f1174f77 | 1074 | break; |
79adffcd | 1075 | default: |
f1174f77 | 1076 | break; |
79adffcd | 1077 | } |
61bd5218 JK |
1078 | return check_generic_ptr_alignment(env, reg, pointer_desc, off, size, |
1079 | strict); | |
79adffcd DB |
1080 | } |
1081 | ||
0c17d1d2 JH |
1082 | /* truncate register to smaller size (in bytes) |
1083 | * must be called with size < BPF_REG_SIZE | |
1084 | */ | |
1085 | static void coerce_reg_to_size(struct bpf_reg_state *reg, int size) | |
1086 | { | |
1087 | u64 mask; | |
1088 | ||
1089 | /* clear high bits in bit representation */ | |
1090 | reg->var_off = tnum_cast(reg->var_off, size); | |
1091 | ||
1092 | /* fix arithmetic bounds */ | |
1093 | mask = ((u64)1 << (size * 8)) - 1; | |
1094 | if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) { | |
1095 | reg->umin_value &= mask; | |
1096 | reg->umax_value &= mask; | |
1097 | } else { | |
1098 | reg->umin_value = 0; | |
1099 | reg->umax_value = mask; | |
1100 | } | |
1101 | reg->smin_value = reg->umin_value; | |
1102 | reg->smax_value = reg->umax_value; | |
1103 | } | |
1104 | ||
17a52670 AS |
1105 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
1106 | * if t==write, value_regno is a register which value is stored into memory | |
1107 | * if t==read, value_regno is a register which will receive the value from memory | |
1108 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
1109 | * if t==read && value_regno==-1, don't care what we read from memory | |
1110 | */ | |
31fd8581 | 1111 | static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, |
17a52670 AS |
1112 | int bpf_size, enum bpf_access_type t, |
1113 | int value_regno) | |
1114 | { | |
638f5b90 AS |
1115 | struct bpf_verifier_state *state = env->cur_state; |
1116 | struct bpf_reg_state *regs = cur_regs(env); | |
1117 | struct bpf_reg_state *reg = regs + regno; | |
17a52670 AS |
1118 | int size, err = 0; |
1119 | ||
1120 | size = bpf_size_to_bytes(bpf_size); | |
1121 | if (size < 0) | |
1122 | return size; | |
1123 | ||
f1174f77 | 1124 | /* alignment checks will add in reg->off themselves */ |
e07b98d9 | 1125 | err = check_ptr_alignment(env, reg, off, size); |
969bf05e AS |
1126 | if (err) |
1127 | return err; | |
17a52670 | 1128 | |
f1174f77 EC |
1129 | /* for access checks, reg->off is just part of off */ |
1130 | off += reg->off; | |
1131 | ||
1132 | if (reg->type == PTR_TO_MAP_VALUE) { | |
1be7f75d AS |
1133 | if (t == BPF_WRITE && value_regno >= 0 && |
1134 | is_pointer_value(env, value_regno)) { | |
61bd5218 | 1135 | verbose(env, "R%d leaks addr into map\n", value_regno); |
1be7f75d AS |
1136 | return -EACCES; |
1137 | } | |
48461135 | 1138 | |
9fd29c08 | 1139 | err = check_map_access(env, regno, off, size, false); |
17a52670 | 1140 | if (!err && t == BPF_READ && value_regno >= 0) |
638f5b90 | 1141 | mark_reg_unknown(env, regs, value_regno); |
17a52670 | 1142 | |
1a0dc1ac | 1143 | } else if (reg->type == PTR_TO_CTX) { |
f1174f77 | 1144 | enum bpf_reg_type reg_type = SCALAR_VALUE; |
19de99f7 | 1145 | |
1be7f75d AS |
1146 | if (t == BPF_WRITE && value_regno >= 0 && |
1147 | is_pointer_value(env, value_regno)) { | |
61bd5218 | 1148 | verbose(env, "R%d leaks addr into ctx\n", value_regno); |
1be7f75d AS |
1149 | return -EACCES; |
1150 | } | |
f1174f77 EC |
1151 | /* ctx accesses must be at a fixed offset, so that we can |
1152 | * determine what type of data were returned. | |
1153 | */ | |
28e33f9d | 1154 | if (reg->off) { |
f8ddadc4 DM |
1155 | verbose(env, |
1156 | "dereference of modified ctx ptr R%d off=%d+%d, ctx+const is allowed, ctx+const+const is not\n", | |
28e33f9d JK |
1157 | regno, reg->off, off - reg->off); |
1158 | return -EACCES; | |
1159 | } | |
1160 | if (!tnum_is_const(reg->var_off) || reg->var_off.value) { | |
f1174f77 EC |
1161 | char tn_buf[48]; |
1162 | ||
1163 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 JK |
1164 | verbose(env, |
1165 | "variable ctx access var_off=%s off=%d size=%d", | |
f1174f77 EC |
1166 | tn_buf, off, size); |
1167 | return -EACCES; | |
1168 | } | |
31fd8581 | 1169 | err = check_ctx_access(env, insn_idx, off, size, t, ®_type); |
969bf05e | 1170 | if (!err && t == BPF_READ && value_regno >= 0) { |
f1174f77 | 1171 | /* ctx access returns either a scalar, or a |
de8f3a83 DB |
1172 | * PTR_TO_PACKET[_META,_END]. In the latter |
1173 | * case, we know the offset is zero. | |
f1174f77 EC |
1174 | */ |
1175 | if (reg_type == SCALAR_VALUE) | |
638f5b90 | 1176 | mark_reg_unknown(env, regs, value_regno); |
f1174f77 | 1177 | else |
638f5b90 | 1178 | mark_reg_known_zero(env, regs, |
61bd5218 | 1179 | value_regno); |
638f5b90 AS |
1180 | regs[value_regno].id = 0; |
1181 | regs[value_regno].off = 0; | |
1182 | regs[value_regno].range = 0; | |
1183 | regs[value_regno].type = reg_type; | |
969bf05e | 1184 | } |
17a52670 | 1185 | |
f1174f77 EC |
1186 | } else if (reg->type == PTR_TO_STACK) { |
1187 | /* stack accesses must be at a fixed offset, so that we can | |
1188 | * determine what type of data were returned. | |
1189 | * See check_stack_read(). | |
1190 | */ | |
1191 | if (!tnum_is_const(reg->var_off)) { | |
1192 | char tn_buf[48]; | |
1193 | ||
1194 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 1195 | verbose(env, "variable stack access var_off=%s off=%d size=%d", |
f1174f77 EC |
1196 | tn_buf, off, size); |
1197 | return -EACCES; | |
1198 | } | |
1199 | off += reg->var_off.value; | |
17a52670 | 1200 | if (off >= 0 || off < -MAX_BPF_STACK) { |
61bd5218 JK |
1201 | verbose(env, "invalid stack off=%d size=%d\n", off, |
1202 | size); | |
17a52670 AS |
1203 | return -EACCES; |
1204 | } | |
8726679a AS |
1205 | |
1206 | if (env->prog->aux->stack_depth < -off) | |
1207 | env->prog->aux->stack_depth = -off; | |
1208 | ||
638f5b90 | 1209 | if (t == BPF_WRITE) |
61bd5218 JK |
1210 | err = check_stack_write(env, state, off, size, |
1211 | value_regno); | |
638f5b90 | 1212 | else |
61bd5218 JK |
1213 | err = check_stack_read(env, state, off, size, |
1214 | value_regno); | |
de8f3a83 | 1215 | } else if (reg_is_pkt_pointer(reg)) { |
3a0af8fd | 1216 | if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { |
61bd5218 | 1217 | verbose(env, "cannot write into packet\n"); |
969bf05e AS |
1218 | return -EACCES; |
1219 | } | |
4acf6c0b BB |
1220 | if (t == BPF_WRITE && value_regno >= 0 && |
1221 | is_pointer_value(env, value_regno)) { | |
61bd5218 JK |
1222 | verbose(env, "R%d leaks addr into packet\n", |
1223 | value_regno); | |
4acf6c0b BB |
1224 | return -EACCES; |
1225 | } | |
9fd29c08 | 1226 | err = check_packet_access(env, regno, off, size, false); |
969bf05e | 1227 | if (!err && t == BPF_READ && value_regno >= 0) |
638f5b90 | 1228 | mark_reg_unknown(env, regs, value_regno); |
17a52670 | 1229 | } else { |
61bd5218 JK |
1230 | verbose(env, "R%d invalid mem access '%s'\n", regno, |
1231 | reg_type_str[reg->type]); | |
17a52670 AS |
1232 | return -EACCES; |
1233 | } | |
969bf05e | 1234 | |
f1174f77 | 1235 | if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && |
638f5b90 | 1236 | regs[value_regno].type == SCALAR_VALUE) { |
f1174f77 | 1237 | /* b/h/w load zero-extends, mark upper bits as known 0 */ |
0c17d1d2 | 1238 | coerce_reg_to_size(®s[value_regno], size); |
969bf05e | 1239 | } |
17a52670 AS |
1240 | return err; |
1241 | } | |
1242 | ||
31fd8581 | 1243 | static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) |
17a52670 | 1244 | { |
17a52670 AS |
1245 | int err; |
1246 | ||
1247 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
1248 | insn->imm != 0) { | |
61bd5218 | 1249 | verbose(env, "BPF_XADD uses reserved fields\n"); |
17a52670 AS |
1250 | return -EINVAL; |
1251 | } | |
1252 | ||
1253 | /* check src1 operand */ | |
dc503a8a | 1254 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
1255 | if (err) |
1256 | return err; | |
1257 | ||
1258 | /* check src2 operand */ | |
dc503a8a | 1259 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
1260 | if (err) |
1261 | return err; | |
1262 | ||
6bdf6abc | 1263 | if (is_pointer_value(env, insn->src_reg)) { |
61bd5218 | 1264 | verbose(env, "R%d leaks addr into mem\n", insn->src_reg); |
6bdf6abc DB |
1265 | return -EACCES; |
1266 | } | |
1267 | ||
f37a8cb8 DB |
1268 | if (is_ctx_reg(env, insn->dst_reg)) { |
1269 | verbose(env, "BPF_XADD stores into R%d context is not allowed\n", | |
1270 | insn->dst_reg); | |
1271 | return -EACCES; | |
1272 | } | |
1273 | ||
17a52670 | 1274 | /* check whether atomic_add can read the memory */ |
31fd8581 | 1275 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1276 | BPF_SIZE(insn->code), BPF_READ, -1); |
1277 | if (err) | |
1278 | return err; | |
1279 | ||
1280 | /* check whether atomic_add can write into the same memory */ | |
31fd8581 | 1281 | return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1282 | BPF_SIZE(insn->code), BPF_WRITE, -1); |
1283 | } | |
1284 | ||
f1174f77 EC |
1285 | /* Does this register contain a constant zero? */ |
1286 | static bool register_is_null(struct bpf_reg_state reg) | |
1287 | { | |
1288 | return reg.type == SCALAR_VALUE && tnum_equals_const(reg.var_off, 0); | |
1289 | } | |
1290 | ||
17a52670 AS |
1291 | /* when register 'regno' is passed into function that will read 'access_size' |
1292 | * bytes from that pointer, make sure that it's within stack boundary | |
f1174f77 EC |
1293 | * and all elements of stack are initialized. |
1294 | * Unlike most pointer bounds-checking functions, this one doesn't take an | |
1295 | * 'off' argument, so it has to add in reg->off itself. | |
17a52670 | 1296 | */ |
58e2af8b | 1297 | static int check_stack_boundary(struct bpf_verifier_env *env, int regno, |
435faee1 DB |
1298 | int access_size, bool zero_size_allowed, |
1299 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1300 | { |
638f5b90 | 1301 | struct bpf_verifier_state *state = env->cur_state; |
58e2af8b | 1302 | struct bpf_reg_state *regs = state->regs; |
638f5b90 | 1303 | int off, i, slot, spi; |
17a52670 | 1304 | |
8e2fe1d9 | 1305 | if (regs[regno].type != PTR_TO_STACK) { |
f1174f77 | 1306 | /* Allow zero-byte read from NULL, regardless of pointer type */ |
8e2fe1d9 | 1307 | if (zero_size_allowed && access_size == 0 && |
f1174f77 | 1308 | register_is_null(regs[regno])) |
8e2fe1d9 DB |
1309 | return 0; |
1310 | ||
61bd5218 | 1311 | verbose(env, "R%d type=%s expected=%s\n", regno, |
8e2fe1d9 DB |
1312 | reg_type_str[regs[regno].type], |
1313 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 1314 | return -EACCES; |
8e2fe1d9 | 1315 | } |
17a52670 | 1316 | |
f1174f77 EC |
1317 | /* Only allow fixed-offset stack reads */ |
1318 | if (!tnum_is_const(regs[regno].var_off)) { | |
1319 | char tn_buf[48]; | |
1320 | ||
1321 | tnum_strn(tn_buf, sizeof(tn_buf), regs[regno].var_off); | |
61bd5218 | 1322 | verbose(env, "invalid variable stack read R%d var_off=%s\n", |
f1174f77 | 1323 | regno, tn_buf); |
ea25f914 | 1324 | return -EACCES; |
f1174f77 EC |
1325 | } |
1326 | off = regs[regno].off + regs[regno].var_off.value; | |
17a52670 | 1327 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || |
9fd29c08 | 1328 | access_size < 0 || (access_size == 0 && !zero_size_allowed)) { |
61bd5218 | 1329 | verbose(env, "invalid stack type R%d off=%d access_size=%d\n", |
17a52670 AS |
1330 | regno, off, access_size); |
1331 | return -EACCES; | |
1332 | } | |
1333 | ||
8726679a AS |
1334 | if (env->prog->aux->stack_depth < -off) |
1335 | env->prog->aux->stack_depth = -off; | |
1336 | ||
435faee1 DB |
1337 | if (meta && meta->raw_mode) { |
1338 | meta->access_size = access_size; | |
1339 | meta->regno = regno; | |
1340 | return 0; | |
1341 | } | |
1342 | ||
17a52670 | 1343 | for (i = 0; i < access_size; i++) { |
638f5b90 AS |
1344 | slot = -(off + i) - 1; |
1345 | spi = slot / BPF_REG_SIZE; | |
1346 | if (state->allocated_stack <= slot || | |
1347 | state->stack[spi].slot_type[slot % BPF_REG_SIZE] != | |
1348 | STACK_MISC) { | |
61bd5218 | 1349 | verbose(env, "invalid indirect read from stack off %d+%d size %d\n", |
17a52670 AS |
1350 | off, i, access_size); |
1351 | return -EACCES; | |
1352 | } | |
1353 | } | |
1354 | return 0; | |
1355 | } | |
1356 | ||
06c1c049 GB |
1357 | static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, |
1358 | int access_size, bool zero_size_allowed, | |
1359 | struct bpf_call_arg_meta *meta) | |
1360 | { | |
638f5b90 | 1361 | struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; |
06c1c049 | 1362 | |
f1174f77 | 1363 | switch (reg->type) { |
06c1c049 | 1364 | case PTR_TO_PACKET: |
de8f3a83 | 1365 | case PTR_TO_PACKET_META: |
9fd29c08 YS |
1366 | return check_packet_access(env, regno, reg->off, access_size, |
1367 | zero_size_allowed); | |
06c1c049 | 1368 | case PTR_TO_MAP_VALUE: |
9fd29c08 YS |
1369 | return check_map_access(env, regno, reg->off, access_size, |
1370 | zero_size_allowed); | |
f1174f77 | 1371 | default: /* scalar_value|ptr_to_stack or invalid ptr */ |
06c1c049 GB |
1372 | return check_stack_boundary(env, regno, access_size, |
1373 | zero_size_allowed, meta); | |
1374 | } | |
1375 | } | |
1376 | ||
58e2af8b | 1377 | static int check_func_arg(struct bpf_verifier_env *env, u32 regno, |
33ff9823 DB |
1378 | enum bpf_arg_type arg_type, |
1379 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1380 | { |
638f5b90 | 1381 | struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; |
6841de8b | 1382 | enum bpf_reg_type expected_type, type = reg->type; |
17a52670 AS |
1383 | int err = 0; |
1384 | ||
80f1d68c | 1385 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
1386 | return 0; |
1387 | ||
dc503a8a EC |
1388 | err = check_reg_arg(env, regno, SRC_OP); |
1389 | if (err) | |
1390 | return err; | |
17a52670 | 1391 | |
1be7f75d AS |
1392 | if (arg_type == ARG_ANYTHING) { |
1393 | if (is_pointer_value(env, regno)) { | |
61bd5218 JK |
1394 | verbose(env, "R%d leaks addr into helper function\n", |
1395 | regno); | |
1be7f75d AS |
1396 | return -EACCES; |
1397 | } | |
80f1d68c | 1398 | return 0; |
1be7f75d | 1399 | } |
80f1d68c | 1400 | |
de8f3a83 | 1401 | if (type_is_pkt_pointer(type) && |
3a0af8fd | 1402 | !may_access_direct_pkt_data(env, meta, BPF_READ)) { |
61bd5218 | 1403 | verbose(env, "helper access to the packet is not allowed\n"); |
6841de8b AS |
1404 | return -EACCES; |
1405 | } | |
1406 | ||
8e2fe1d9 | 1407 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
1408 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
1409 | expected_type = PTR_TO_STACK; | |
de8f3a83 DB |
1410 | if (!type_is_pkt_pointer(type) && |
1411 | type != expected_type) | |
6841de8b | 1412 | goto err_type; |
39f19ebb AS |
1413 | } else if (arg_type == ARG_CONST_SIZE || |
1414 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
f1174f77 EC |
1415 | expected_type = SCALAR_VALUE; |
1416 | if (type != expected_type) | |
6841de8b | 1417 | goto err_type; |
17a52670 AS |
1418 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
1419 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
1420 | if (type != expected_type) |
1421 | goto err_type; | |
608cd71a AS |
1422 | } else if (arg_type == ARG_PTR_TO_CTX) { |
1423 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
1424 | if (type != expected_type) |
1425 | goto err_type; | |
39f19ebb | 1426 | } else if (arg_type == ARG_PTR_TO_MEM || |
db1ac496 | 1427 | arg_type == ARG_PTR_TO_MEM_OR_NULL || |
39f19ebb | 1428 | arg_type == ARG_PTR_TO_UNINIT_MEM) { |
8e2fe1d9 DB |
1429 | expected_type = PTR_TO_STACK; |
1430 | /* One exception here. In case function allows for NULL to be | |
f1174f77 | 1431 | * passed in as argument, it's a SCALAR_VALUE type. Final test |
8e2fe1d9 DB |
1432 | * happens during stack boundary checking. |
1433 | */ | |
db1ac496 GB |
1434 | if (register_is_null(*reg) && |
1435 | arg_type == ARG_PTR_TO_MEM_OR_NULL) | |
6841de8b | 1436 | /* final test in check_stack_boundary() */; |
de8f3a83 DB |
1437 | else if (!type_is_pkt_pointer(type) && |
1438 | type != PTR_TO_MAP_VALUE && | |
f1174f77 | 1439 | type != expected_type) |
6841de8b | 1440 | goto err_type; |
39f19ebb | 1441 | meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; |
17a52670 | 1442 | } else { |
61bd5218 | 1443 | verbose(env, "unsupported arg_type %d\n", arg_type); |
17a52670 AS |
1444 | return -EFAULT; |
1445 | } | |
1446 | ||
17a52670 AS |
1447 | if (arg_type == ARG_CONST_MAP_PTR) { |
1448 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 1449 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
1450 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
1451 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
1452 | * check that [key, key + map->key_size) are within | |
1453 | * stack limits and initialized | |
1454 | */ | |
33ff9823 | 1455 | if (!meta->map_ptr) { |
17a52670 AS |
1456 | /* in function declaration map_ptr must come before |
1457 | * map_key, so that it's verified and known before | |
1458 | * we have to check map_key here. Otherwise it means | |
1459 | * that kernel subsystem misconfigured verifier | |
1460 | */ | |
61bd5218 | 1461 | verbose(env, "invalid map_ptr to access map->key\n"); |
17a52670 AS |
1462 | return -EACCES; |
1463 | } | |
de8f3a83 | 1464 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1465 | err = check_packet_access(env, regno, reg->off, |
9fd29c08 YS |
1466 | meta->map_ptr->key_size, |
1467 | false); | |
6841de8b AS |
1468 | else |
1469 | err = check_stack_boundary(env, regno, | |
1470 | meta->map_ptr->key_size, | |
1471 | false, NULL); | |
17a52670 AS |
1472 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1473 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1474 | * check [value, value + map->value_size) validity | |
1475 | */ | |
33ff9823 | 1476 | if (!meta->map_ptr) { |
17a52670 | 1477 | /* kernel subsystem misconfigured verifier */ |
61bd5218 | 1478 | verbose(env, "invalid map_ptr to access map->value\n"); |
17a52670 AS |
1479 | return -EACCES; |
1480 | } | |
de8f3a83 | 1481 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1482 | err = check_packet_access(env, regno, reg->off, |
9fd29c08 YS |
1483 | meta->map_ptr->value_size, |
1484 | false); | |
6841de8b AS |
1485 | else |
1486 | err = check_stack_boundary(env, regno, | |
1487 | meta->map_ptr->value_size, | |
1488 | false, NULL); | |
39f19ebb AS |
1489 | } else if (arg_type == ARG_CONST_SIZE || |
1490 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
1491 | bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); | |
17a52670 | 1492 | |
17a52670 AS |
1493 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1494 | * from stack pointer 'buf'. Check it | |
1495 | * note: regno == len, regno - 1 == buf | |
1496 | */ | |
1497 | if (regno == 0) { | |
1498 | /* kernel subsystem misconfigured verifier */ | |
61bd5218 JK |
1499 | verbose(env, |
1500 | "ARG_CONST_SIZE cannot be first argument\n"); | |
17a52670 AS |
1501 | return -EACCES; |
1502 | } | |
06c1c049 | 1503 | |
f1174f77 EC |
1504 | /* The register is SCALAR_VALUE; the access check |
1505 | * happens using its boundaries. | |
06c1c049 | 1506 | */ |
f1174f77 EC |
1507 | |
1508 | if (!tnum_is_const(reg->var_off)) | |
06c1c049 GB |
1509 | /* For unprivileged variable accesses, disable raw |
1510 | * mode so that the program is required to | |
1511 | * initialize all the memory that the helper could | |
1512 | * just partially fill up. | |
1513 | */ | |
1514 | meta = NULL; | |
1515 | ||
b03c9f9f | 1516 | if (reg->smin_value < 0) { |
61bd5218 | 1517 | verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", |
f1174f77 EC |
1518 | regno); |
1519 | return -EACCES; | |
1520 | } | |
06c1c049 | 1521 | |
b03c9f9f | 1522 | if (reg->umin_value == 0) { |
f1174f77 EC |
1523 | err = check_helper_mem_access(env, regno - 1, 0, |
1524 | zero_size_allowed, | |
1525 | meta); | |
06c1c049 GB |
1526 | if (err) |
1527 | return err; | |
06c1c049 | 1528 | } |
f1174f77 | 1529 | |
b03c9f9f | 1530 | if (reg->umax_value >= BPF_MAX_VAR_SIZ) { |
61bd5218 | 1531 | verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", |
f1174f77 EC |
1532 | regno); |
1533 | return -EACCES; | |
1534 | } | |
1535 | err = check_helper_mem_access(env, regno - 1, | |
b03c9f9f | 1536 | reg->umax_value, |
f1174f77 | 1537 | zero_size_allowed, meta); |
17a52670 AS |
1538 | } |
1539 | ||
1540 | return err; | |
6841de8b | 1541 | err_type: |
61bd5218 | 1542 | verbose(env, "R%d type=%s expected=%s\n", regno, |
6841de8b AS |
1543 | reg_type_str[type], reg_type_str[expected_type]); |
1544 | return -EACCES; | |
17a52670 AS |
1545 | } |
1546 | ||
61bd5218 JK |
1547 | static int check_map_func_compatibility(struct bpf_verifier_env *env, |
1548 | struct bpf_map *map, int func_id) | |
35578d79 | 1549 | { |
35578d79 KX |
1550 | if (!map) |
1551 | return 0; | |
1552 | ||
6aff67c8 AS |
1553 | /* We need a two way check, first is from map perspective ... */ |
1554 | switch (map->map_type) { | |
1555 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1556 | if (func_id != BPF_FUNC_tail_call) | |
1557 | goto error; | |
1558 | break; | |
1559 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1560 | if (func_id != BPF_FUNC_perf_event_read && | |
908432ca YS |
1561 | func_id != BPF_FUNC_perf_event_output && |
1562 | func_id != BPF_FUNC_perf_event_read_value) | |
6aff67c8 AS |
1563 | goto error; |
1564 | break; | |
1565 | case BPF_MAP_TYPE_STACK_TRACE: | |
1566 | if (func_id != BPF_FUNC_get_stackid) | |
1567 | goto error; | |
1568 | break; | |
4ed8ec52 | 1569 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1570 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1571 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1572 | goto error; |
1573 | break; | |
546ac1ff JF |
1574 | /* devmap returns a pointer to a live net_device ifindex that we cannot |
1575 | * allow to be modified from bpf side. So do not allow lookup elements | |
1576 | * for now. | |
1577 | */ | |
1578 | case BPF_MAP_TYPE_DEVMAP: | |
2ddf71e2 | 1579 | if (func_id != BPF_FUNC_redirect_map) |
546ac1ff JF |
1580 | goto error; |
1581 | break; | |
6710e112 JDB |
1582 | /* Restrict bpf side of cpumap, open when use-cases appear */ |
1583 | case BPF_MAP_TYPE_CPUMAP: | |
1584 | if (func_id != BPF_FUNC_redirect_map) | |
1585 | goto error; | |
1586 | break; | |
56f668df | 1587 | case BPF_MAP_TYPE_ARRAY_OF_MAPS: |
bcc6b1b7 | 1588 | case BPF_MAP_TYPE_HASH_OF_MAPS: |
56f668df MKL |
1589 | if (func_id != BPF_FUNC_map_lookup_elem) |
1590 | goto error; | |
16a43625 | 1591 | break; |
174a79ff JF |
1592 | case BPF_MAP_TYPE_SOCKMAP: |
1593 | if (func_id != BPF_FUNC_sk_redirect_map && | |
1594 | func_id != BPF_FUNC_sock_map_update && | |
1595 | func_id != BPF_FUNC_map_delete_elem) | |
1596 | goto error; | |
1597 | break; | |
6aff67c8 AS |
1598 | default: |
1599 | break; | |
1600 | } | |
1601 | ||
1602 | /* ... and second from the function itself. */ | |
1603 | switch (func_id) { | |
1604 | case BPF_FUNC_tail_call: | |
1605 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1606 | goto error; | |
1607 | break; | |
1608 | case BPF_FUNC_perf_event_read: | |
1609 | case BPF_FUNC_perf_event_output: | |
908432ca | 1610 | case BPF_FUNC_perf_event_read_value: |
6aff67c8 AS |
1611 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) |
1612 | goto error; | |
1613 | break; | |
1614 | case BPF_FUNC_get_stackid: | |
1615 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1616 | goto error; | |
1617 | break; | |
60d20f91 | 1618 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1619 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1620 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1621 | goto error; | |
1622 | break; | |
97f91a7c | 1623 | case BPF_FUNC_redirect_map: |
9c270af3 JDB |
1624 | if (map->map_type != BPF_MAP_TYPE_DEVMAP && |
1625 | map->map_type != BPF_MAP_TYPE_CPUMAP) | |
97f91a7c JF |
1626 | goto error; |
1627 | break; | |
174a79ff JF |
1628 | case BPF_FUNC_sk_redirect_map: |
1629 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1630 | goto error; | |
1631 | break; | |
1632 | case BPF_FUNC_sock_map_update: | |
1633 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1634 | goto error; | |
1635 | break; | |
6aff67c8 AS |
1636 | default: |
1637 | break; | |
35578d79 KX |
1638 | } |
1639 | ||
1640 | return 0; | |
6aff67c8 | 1641 | error: |
61bd5218 | 1642 | verbose(env, "cannot pass map_type %d into func %s#%d\n", |
ebb676da | 1643 | map->map_type, func_id_name(func_id), func_id); |
6aff67c8 | 1644 | return -EINVAL; |
35578d79 KX |
1645 | } |
1646 | ||
435faee1 DB |
1647 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1648 | { | |
1649 | int count = 0; | |
1650 | ||
39f19ebb | 1651 | if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1652 | count++; |
39f19ebb | 1653 | if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1654 | count++; |
39f19ebb | 1655 | if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1656 | count++; |
39f19ebb | 1657 | if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1658 | count++; |
39f19ebb | 1659 | if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 DB |
1660 | count++; |
1661 | ||
1662 | return count > 1 ? -EINVAL : 0; | |
1663 | } | |
1664 | ||
de8f3a83 DB |
1665 | /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] |
1666 | * are now invalid, so turn them into unknown SCALAR_VALUE. | |
f1174f77 | 1667 | */ |
58e2af8b | 1668 | static void clear_all_pkt_pointers(struct bpf_verifier_env *env) |
969bf05e | 1669 | { |
638f5b90 | 1670 | struct bpf_verifier_state *state = env->cur_state; |
58e2af8b | 1671 | struct bpf_reg_state *regs = state->regs, *reg; |
969bf05e AS |
1672 | int i; |
1673 | ||
1674 | for (i = 0; i < MAX_BPF_REG; i++) | |
de8f3a83 | 1675 | if (reg_is_pkt_pointer_any(®s[i])) |
61bd5218 | 1676 | mark_reg_unknown(env, regs, i); |
969bf05e | 1677 | |
638f5b90 AS |
1678 | for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { |
1679 | if (state->stack[i].slot_type[0] != STACK_SPILL) | |
969bf05e | 1680 | continue; |
638f5b90 | 1681 | reg = &state->stack[i].spilled_ptr; |
de8f3a83 DB |
1682 | if (reg_is_pkt_pointer_any(reg)) |
1683 | __mark_reg_unknown(reg); | |
969bf05e AS |
1684 | } |
1685 | } | |
1686 | ||
81ed18ab | 1687 | static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) |
17a52670 | 1688 | { |
17a52670 | 1689 | const struct bpf_func_proto *fn = NULL; |
638f5b90 | 1690 | struct bpf_reg_state *regs; |
33ff9823 | 1691 | struct bpf_call_arg_meta meta; |
969bf05e | 1692 | bool changes_data; |
17a52670 AS |
1693 | int i, err; |
1694 | ||
1695 | /* find function prototype */ | |
1696 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
61bd5218 JK |
1697 | verbose(env, "invalid func %s#%d\n", func_id_name(func_id), |
1698 | func_id); | |
17a52670 AS |
1699 | return -EINVAL; |
1700 | } | |
1701 | ||
00176a34 JK |
1702 | if (env->ops->get_func_proto) |
1703 | fn = env->ops->get_func_proto(func_id); | |
17a52670 AS |
1704 | |
1705 | if (!fn) { | |
61bd5218 JK |
1706 | verbose(env, "unknown func %s#%d\n", func_id_name(func_id), |
1707 | func_id); | |
17a52670 AS |
1708 | return -EINVAL; |
1709 | } | |
1710 | ||
1711 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1712 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
61bd5218 | 1713 | verbose(env, "cannot call GPL only function from proprietary program\n"); |
17a52670 AS |
1714 | return -EINVAL; |
1715 | } | |
1716 | ||
04514d13 | 1717 | /* With LD_ABS/IND some JITs save/restore skb from r1. */ |
17bedab2 | 1718 | changes_data = bpf_helper_changes_pkt_data(fn->func); |
04514d13 DB |
1719 | if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { |
1720 | verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", | |
1721 | func_id_name(func_id), func_id); | |
1722 | return -EINVAL; | |
1723 | } | |
969bf05e | 1724 | |
33ff9823 | 1725 | memset(&meta, 0, sizeof(meta)); |
36bbef52 | 1726 | meta.pkt_access = fn->pkt_access; |
33ff9823 | 1727 | |
435faee1 DB |
1728 | /* We only support one arg being in raw mode at the moment, which |
1729 | * is sufficient for the helper functions we have right now. | |
1730 | */ | |
1731 | err = check_raw_mode(fn); | |
1732 | if (err) { | |
61bd5218 | 1733 | verbose(env, "kernel subsystem misconfigured func %s#%d\n", |
ebb676da | 1734 | func_id_name(func_id), func_id); |
435faee1 DB |
1735 | return err; |
1736 | } | |
1737 | ||
17a52670 | 1738 | /* check args */ |
33ff9823 | 1739 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1740 | if (err) |
1741 | return err; | |
33ff9823 | 1742 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1743 | if (err) |
1744 | return err; | |
b2157399 AS |
1745 | if (func_id == BPF_FUNC_tail_call) { |
1746 | if (meta.map_ptr == NULL) { | |
1747 | verbose(env, "verifier bug\n"); | |
1748 | return -EINVAL; | |
1749 | } | |
1750 | env->insn_aux_data[insn_idx].map_ptr = meta.map_ptr; | |
1751 | } | |
33ff9823 | 1752 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1753 | if (err) |
1754 | return err; | |
33ff9823 | 1755 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1756 | if (err) |
1757 | return err; | |
33ff9823 | 1758 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1759 | if (err) |
1760 | return err; | |
1761 | ||
435faee1 DB |
1762 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1763 | * is inferred from register state. | |
1764 | */ | |
1765 | for (i = 0; i < meta.access_size; i++) { | |
31fd8581 | 1766 | err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); |
435faee1 DB |
1767 | if (err) |
1768 | return err; | |
1769 | } | |
1770 | ||
638f5b90 | 1771 | regs = cur_regs(env); |
17a52670 | 1772 | /* reset caller saved regs */ |
dc503a8a | 1773 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
61bd5218 | 1774 | mark_reg_not_init(env, regs, caller_saved[i]); |
dc503a8a EC |
1775 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
1776 | } | |
17a52670 | 1777 | |
dc503a8a | 1778 | /* update return register (already marked as written above) */ |
17a52670 | 1779 | if (fn->ret_type == RET_INTEGER) { |
f1174f77 | 1780 | /* sets type to SCALAR_VALUE */ |
61bd5218 | 1781 | mark_reg_unknown(env, regs, BPF_REG_0); |
17a52670 AS |
1782 | } else if (fn->ret_type == RET_VOID) { |
1783 | regs[BPF_REG_0].type = NOT_INIT; | |
1784 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
fad73a1a MKL |
1785 | struct bpf_insn_aux_data *insn_aux; |
1786 | ||
17a52670 | 1787 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; |
f1174f77 | 1788 | /* There is no offset yet applied, variable or fixed */ |
61bd5218 | 1789 | mark_reg_known_zero(env, regs, BPF_REG_0); |
f1174f77 | 1790 | regs[BPF_REG_0].off = 0; |
17a52670 AS |
1791 | /* remember map_ptr, so that check_map_access() |
1792 | * can check 'value_size' boundary of memory access | |
1793 | * to map element returned from bpf_map_lookup_elem() | |
1794 | */ | |
33ff9823 | 1795 | if (meta.map_ptr == NULL) { |
61bd5218 JK |
1796 | verbose(env, |
1797 | "kernel subsystem misconfigured verifier\n"); | |
17a52670 AS |
1798 | return -EINVAL; |
1799 | } | |
33ff9823 | 1800 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
57a09bf0 | 1801 | regs[BPF_REG_0].id = ++env->id_gen; |
fad73a1a MKL |
1802 | insn_aux = &env->insn_aux_data[insn_idx]; |
1803 | if (!insn_aux->map_ptr) | |
1804 | insn_aux->map_ptr = meta.map_ptr; | |
1805 | else if (insn_aux->map_ptr != meta.map_ptr) | |
1806 | insn_aux->map_ptr = BPF_MAP_PTR_POISON; | |
17a52670 | 1807 | } else { |
61bd5218 | 1808 | verbose(env, "unknown return type %d of func %s#%d\n", |
ebb676da | 1809 | fn->ret_type, func_id_name(func_id), func_id); |
17a52670 AS |
1810 | return -EINVAL; |
1811 | } | |
04fd61ab | 1812 | |
61bd5218 | 1813 | err = check_map_func_compatibility(env, meta.map_ptr, func_id); |
35578d79 KX |
1814 | if (err) |
1815 | return err; | |
04fd61ab | 1816 | |
969bf05e AS |
1817 | if (changes_data) |
1818 | clear_all_pkt_pointers(env); | |
1819 | return 0; | |
1820 | } | |
1821 | ||
b03c9f9f EC |
1822 | static bool signed_add_overflows(s64 a, s64 b) |
1823 | { | |
1824 | /* Do the add in u64, where overflow is well-defined */ | |
1825 | s64 res = (s64)((u64)a + (u64)b); | |
1826 | ||
1827 | if (b < 0) | |
1828 | return res > a; | |
1829 | return res < a; | |
1830 | } | |
1831 | ||
1832 | static bool signed_sub_overflows(s64 a, s64 b) | |
1833 | { | |
1834 | /* Do the sub in u64, where overflow is well-defined */ | |
1835 | s64 res = (s64)((u64)a - (u64)b); | |
1836 | ||
1837 | if (b < 0) | |
1838 | return res < a; | |
1839 | return res > a; | |
969bf05e AS |
1840 | } |
1841 | ||
bb7f0f98 AS |
1842 | static bool check_reg_sane_offset(struct bpf_verifier_env *env, |
1843 | const struct bpf_reg_state *reg, | |
1844 | enum bpf_reg_type type) | |
1845 | { | |
1846 | bool known = tnum_is_const(reg->var_off); | |
1847 | s64 val = reg->var_off.value; | |
1848 | s64 smin = reg->smin_value; | |
1849 | ||
1850 | if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) { | |
1851 | verbose(env, "math between %s pointer and %lld is not allowed\n", | |
1852 | reg_type_str[type], val); | |
1853 | return false; | |
1854 | } | |
1855 | ||
1856 | if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) { | |
1857 | verbose(env, "%s pointer offset %d is not allowed\n", | |
1858 | reg_type_str[type], reg->off); | |
1859 | return false; | |
1860 | } | |
1861 | ||
1862 | if (smin == S64_MIN) { | |
1863 | verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n", | |
1864 | reg_type_str[type]); | |
1865 | return false; | |
1866 | } | |
1867 | ||
1868 | if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) { | |
1869 | verbose(env, "value %lld makes %s pointer be out of bounds\n", | |
1870 | smin, reg_type_str[type]); | |
1871 | return false; | |
1872 | } | |
1873 | ||
1874 | return true; | |
1875 | } | |
1876 | ||
f1174f77 | 1877 | /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. |
f1174f77 EC |
1878 | * Caller should also handle BPF_MOV case separately. |
1879 | * If we return -EACCES, caller may want to try again treating pointer as a | |
1880 | * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks. | |
1881 | */ | |
1882 | static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, | |
1883 | struct bpf_insn *insn, | |
1884 | const struct bpf_reg_state *ptr_reg, | |
1885 | const struct bpf_reg_state *off_reg) | |
969bf05e | 1886 | { |
638f5b90 | 1887 | struct bpf_reg_state *regs = cur_regs(env), *dst_reg; |
f1174f77 | 1888 | bool known = tnum_is_const(off_reg->var_off); |
b03c9f9f EC |
1889 | s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, |
1890 | smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; | |
1891 | u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, | |
1892 | umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; | |
969bf05e | 1893 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 1894 | u32 dst = insn->dst_reg; |
969bf05e | 1895 | |
f1174f77 | 1896 | dst_reg = ®s[dst]; |
969bf05e | 1897 | |
6f16101e DB |
1898 | if ((known && (smin_val != smax_val || umin_val != umax_val)) || |
1899 | smin_val > smax_val || umin_val > umax_val) { | |
1900 | /* Taint dst register if offset had invalid bounds derived from | |
1901 | * e.g. dead branches. | |
1902 | */ | |
1903 | __mark_reg_unknown(dst_reg); | |
1904 | return 0; | |
f1174f77 EC |
1905 | } |
1906 | ||
1907 | if (BPF_CLASS(insn->code) != BPF_ALU64) { | |
1908 | /* 32-bit ALU ops on pointers produce (meaningless) scalars */ | |
82abbf8d AS |
1909 | verbose(env, |
1910 | "R%d 32-bit pointer arithmetic prohibited\n", | |
1911 | dst); | |
f1174f77 | 1912 | return -EACCES; |
969bf05e AS |
1913 | } |
1914 | ||
f1174f77 | 1915 | if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { |
82abbf8d AS |
1916 | verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n", |
1917 | dst); | |
f1174f77 EC |
1918 | return -EACCES; |
1919 | } | |
1920 | if (ptr_reg->type == CONST_PTR_TO_MAP) { | |
82abbf8d AS |
1921 | verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n", |
1922 | dst); | |
f1174f77 EC |
1923 | return -EACCES; |
1924 | } | |
1925 | if (ptr_reg->type == PTR_TO_PACKET_END) { | |
82abbf8d AS |
1926 | verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n", |
1927 | dst); | |
f1174f77 EC |
1928 | return -EACCES; |
1929 | } | |
1930 | ||
1931 | /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. | |
1932 | * The id may be overwritten later if we create a new variable offset. | |
969bf05e | 1933 | */ |
f1174f77 EC |
1934 | dst_reg->type = ptr_reg->type; |
1935 | dst_reg->id = ptr_reg->id; | |
969bf05e | 1936 | |
bb7f0f98 AS |
1937 | if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || |
1938 | !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) | |
1939 | return -EINVAL; | |
1940 | ||
f1174f77 EC |
1941 | switch (opcode) { |
1942 | case BPF_ADD: | |
1943 | /* We can take a fixed offset as long as it doesn't overflow | |
1944 | * the s32 'off' field | |
969bf05e | 1945 | */ |
b03c9f9f EC |
1946 | if (known && (ptr_reg->off + smin_val == |
1947 | (s64)(s32)(ptr_reg->off + smin_val))) { | |
f1174f77 | 1948 | /* pointer += K. Accumulate it into fixed offset */ |
b03c9f9f EC |
1949 | dst_reg->smin_value = smin_ptr; |
1950 | dst_reg->smax_value = smax_ptr; | |
1951 | dst_reg->umin_value = umin_ptr; | |
1952 | dst_reg->umax_value = umax_ptr; | |
f1174f77 | 1953 | dst_reg->var_off = ptr_reg->var_off; |
b03c9f9f | 1954 | dst_reg->off = ptr_reg->off + smin_val; |
f1174f77 EC |
1955 | dst_reg->range = ptr_reg->range; |
1956 | break; | |
1957 | } | |
f1174f77 EC |
1958 | /* A new variable offset is created. Note that off_reg->off |
1959 | * == 0, since it's a scalar. | |
1960 | * dst_reg gets the pointer type and since some positive | |
1961 | * integer value was added to the pointer, give it a new 'id' | |
1962 | * if it's a PTR_TO_PACKET. | |
1963 | * this creates a new 'base' pointer, off_reg (variable) gets | |
1964 | * added into the variable offset, and we copy the fixed offset | |
1965 | * from ptr_reg. | |
969bf05e | 1966 | */ |
b03c9f9f EC |
1967 | if (signed_add_overflows(smin_ptr, smin_val) || |
1968 | signed_add_overflows(smax_ptr, smax_val)) { | |
1969 | dst_reg->smin_value = S64_MIN; | |
1970 | dst_reg->smax_value = S64_MAX; | |
1971 | } else { | |
1972 | dst_reg->smin_value = smin_ptr + smin_val; | |
1973 | dst_reg->smax_value = smax_ptr + smax_val; | |
1974 | } | |
1975 | if (umin_ptr + umin_val < umin_ptr || | |
1976 | umax_ptr + umax_val < umax_ptr) { | |
1977 | dst_reg->umin_value = 0; | |
1978 | dst_reg->umax_value = U64_MAX; | |
1979 | } else { | |
1980 | dst_reg->umin_value = umin_ptr + umin_val; | |
1981 | dst_reg->umax_value = umax_ptr + umax_val; | |
1982 | } | |
f1174f77 EC |
1983 | dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); |
1984 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 1985 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
1986 | dst_reg->id = ++env->id_gen; |
1987 | /* something was added to pkt_ptr, set range to zero */ | |
1988 | dst_reg->range = 0; | |
1989 | } | |
1990 | break; | |
1991 | case BPF_SUB: | |
1992 | if (dst_reg == off_reg) { | |
1993 | /* scalar -= pointer. Creates an unknown scalar */ | |
82abbf8d AS |
1994 | verbose(env, "R%d tried to subtract pointer from scalar\n", |
1995 | dst); | |
f1174f77 EC |
1996 | return -EACCES; |
1997 | } | |
1998 | /* We don't allow subtraction from FP, because (according to | |
1999 | * test_verifier.c test "invalid fp arithmetic", JITs might not | |
2000 | * be able to deal with it. | |
969bf05e | 2001 | */ |
f1174f77 | 2002 | if (ptr_reg->type == PTR_TO_STACK) { |
82abbf8d AS |
2003 | verbose(env, "R%d subtraction from stack pointer prohibited\n", |
2004 | dst); | |
f1174f77 EC |
2005 | return -EACCES; |
2006 | } | |
b03c9f9f EC |
2007 | if (known && (ptr_reg->off - smin_val == |
2008 | (s64)(s32)(ptr_reg->off - smin_val))) { | |
f1174f77 | 2009 | /* pointer -= K. Subtract it from fixed offset */ |
b03c9f9f EC |
2010 | dst_reg->smin_value = smin_ptr; |
2011 | dst_reg->smax_value = smax_ptr; | |
2012 | dst_reg->umin_value = umin_ptr; | |
2013 | dst_reg->umax_value = umax_ptr; | |
f1174f77 EC |
2014 | dst_reg->var_off = ptr_reg->var_off; |
2015 | dst_reg->id = ptr_reg->id; | |
b03c9f9f | 2016 | dst_reg->off = ptr_reg->off - smin_val; |
f1174f77 EC |
2017 | dst_reg->range = ptr_reg->range; |
2018 | break; | |
2019 | } | |
f1174f77 EC |
2020 | /* A new variable offset is created. If the subtrahend is known |
2021 | * nonnegative, then any reg->range we had before is still good. | |
969bf05e | 2022 | */ |
b03c9f9f EC |
2023 | if (signed_sub_overflows(smin_ptr, smax_val) || |
2024 | signed_sub_overflows(smax_ptr, smin_val)) { | |
2025 | /* Overflow possible, we know nothing */ | |
2026 | dst_reg->smin_value = S64_MIN; | |
2027 | dst_reg->smax_value = S64_MAX; | |
2028 | } else { | |
2029 | dst_reg->smin_value = smin_ptr - smax_val; | |
2030 | dst_reg->smax_value = smax_ptr - smin_val; | |
2031 | } | |
2032 | if (umin_ptr < umax_val) { | |
2033 | /* Overflow possible, we know nothing */ | |
2034 | dst_reg->umin_value = 0; | |
2035 | dst_reg->umax_value = U64_MAX; | |
2036 | } else { | |
2037 | /* Cannot overflow (as long as bounds are consistent) */ | |
2038 | dst_reg->umin_value = umin_ptr - umax_val; | |
2039 | dst_reg->umax_value = umax_ptr - umin_val; | |
2040 | } | |
f1174f77 EC |
2041 | dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); |
2042 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 2043 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
2044 | dst_reg->id = ++env->id_gen; |
2045 | /* something was added to pkt_ptr, set range to zero */ | |
b03c9f9f | 2046 | if (smin_val < 0) |
f1174f77 | 2047 | dst_reg->range = 0; |
43188702 | 2048 | } |
f1174f77 EC |
2049 | break; |
2050 | case BPF_AND: | |
2051 | case BPF_OR: | |
2052 | case BPF_XOR: | |
82abbf8d AS |
2053 | /* bitwise ops on pointers are troublesome, prohibit. */ |
2054 | verbose(env, "R%d bitwise operator %s on pointer prohibited\n", | |
2055 | dst, bpf_alu_string[opcode >> 4]); | |
f1174f77 EC |
2056 | return -EACCES; |
2057 | default: | |
2058 | /* other operators (e.g. MUL,LSH) produce non-pointer results */ | |
82abbf8d AS |
2059 | verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", |
2060 | dst, bpf_alu_string[opcode >> 4]); | |
f1174f77 | 2061 | return -EACCES; |
43188702 JF |
2062 | } |
2063 | ||
bb7f0f98 AS |
2064 | if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) |
2065 | return -EINVAL; | |
2066 | ||
b03c9f9f EC |
2067 | __update_reg_bounds(dst_reg); |
2068 | __reg_deduce_bounds(dst_reg); | |
2069 | __reg_bound_offset(dst_reg); | |
43188702 JF |
2070 | return 0; |
2071 | } | |
2072 | ||
468f6eaf JH |
2073 | /* WARNING: This function does calculations on 64-bit values, but the actual |
2074 | * execution may occur on 32-bit values. Therefore, things like bitshifts | |
2075 | * need extra checks in the 32-bit case. | |
2076 | */ | |
f1174f77 EC |
2077 | static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, |
2078 | struct bpf_insn *insn, | |
2079 | struct bpf_reg_state *dst_reg, | |
2080 | struct bpf_reg_state src_reg) | |
969bf05e | 2081 | { |
638f5b90 | 2082 | struct bpf_reg_state *regs = cur_regs(env); |
48461135 | 2083 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 2084 | bool src_known, dst_known; |
b03c9f9f EC |
2085 | s64 smin_val, smax_val; |
2086 | u64 umin_val, umax_val; | |
468f6eaf | 2087 | u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; |
48461135 | 2088 | |
b03c9f9f EC |
2089 | smin_val = src_reg.smin_value; |
2090 | smax_val = src_reg.smax_value; | |
2091 | umin_val = src_reg.umin_value; | |
2092 | umax_val = src_reg.umax_value; | |
f1174f77 EC |
2093 | src_known = tnum_is_const(src_reg.var_off); |
2094 | dst_known = tnum_is_const(dst_reg->var_off); | |
f23cc643 | 2095 | |
6f16101e DB |
2096 | if ((src_known && (smin_val != smax_val || umin_val != umax_val)) || |
2097 | smin_val > smax_val || umin_val > umax_val) { | |
2098 | /* Taint dst register if offset had invalid bounds derived from | |
2099 | * e.g. dead branches. | |
2100 | */ | |
2101 | __mark_reg_unknown(dst_reg); | |
2102 | return 0; | |
2103 | } | |
2104 | ||
bb7f0f98 AS |
2105 | if (!src_known && |
2106 | opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) { | |
2107 | __mark_reg_unknown(dst_reg); | |
2108 | return 0; | |
2109 | } | |
2110 | ||
48461135 JB |
2111 | switch (opcode) { |
2112 | case BPF_ADD: | |
b03c9f9f EC |
2113 | if (signed_add_overflows(dst_reg->smin_value, smin_val) || |
2114 | signed_add_overflows(dst_reg->smax_value, smax_val)) { | |
2115 | dst_reg->smin_value = S64_MIN; | |
2116 | dst_reg->smax_value = S64_MAX; | |
2117 | } else { | |
2118 | dst_reg->smin_value += smin_val; | |
2119 | dst_reg->smax_value += smax_val; | |
2120 | } | |
2121 | if (dst_reg->umin_value + umin_val < umin_val || | |
2122 | dst_reg->umax_value + umax_val < umax_val) { | |
2123 | dst_reg->umin_value = 0; | |
2124 | dst_reg->umax_value = U64_MAX; | |
2125 | } else { | |
2126 | dst_reg->umin_value += umin_val; | |
2127 | dst_reg->umax_value += umax_val; | |
2128 | } | |
f1174f77 | 2129 | dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
2130 | break; |
2131 | case BPF_SUB: | |
b03c9f9f EC |
2132 | if (signed_sub_overflows(dst_reg->smin_value, smax_val) || |
2133 | signed_sub_overflows(dst_reg->smax_value, smin_val)) { | |
2134 | /* Overflow possible, we know nothing */ | |
2135 | dst_reg->smin_value = S64_MIN; | |
2136 | dst_reg->smax_value = S64_MAX; | |
2137 | } else { | |
2138 | dst_reg->smin_value -= smax_val; | |
2139 | dst_reg->smax_value -= smin_val; | |
2140 | } | |
2141 | if (dst_reg->umin_value < umax_val) { | |
2142 | /* Overflow possible, we know nothing */ | |
2143 | dst_reg->umin_value = 0; | |
2144 | dst_reg->umax_value = U64_MAX; | |
2145 | } else { | |
2146 | /* Cannot overflow (as long as bounds are consistent) */ | |
2147 | dst_reg->umin_value -= umax_val; | |
2148 | dst_reg->umax_value -= umin_val; | |
2149 | } | |
f1174f77 | 2150 | dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
2151 | break; |
2152 | case BPF_MUL: | |
b03c9f9f EC |
2153 | dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); |
2154 | if (smin_val < 0 || dst_reg->smin_value < 0) { | |
f1174f77 | 2155 | /* Ain't nobody got time to multiply that sign */ |
b03c9f9f EC |
2156 | __mark_reg_unbounded(dst_reg); |
2157 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2158 | break; |
2159 | } | |
b03c9f9f EC |
2160 | /* Both values are positive, so we can work with unsigned and |
2161 | * copy the result to signed (unless it exceeds S64_MAX). | |
f1174f77 | 2162 | */ |
b03c9f9f EC |
2163 | if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { |
2164 | /* Potential overflow, we know nothing */ | |
2165 | __mark_reg_unbounded(dst_reg); | |
2166 | /* (except what we can learn from the var_off) */ | |
2167 | __update_reg_bounds(dst_reg); | |
2168 | break; | |
2169 | } | |
2170 | dst_reg->umin_value *= umin_val; | |
2171 | dst_reg->umax_value *= umax_val; | |
2172 | if (dst_reg->umax_value > S64_MAX) { | |
2173 | /* Overflow possible, we know nothing */ | |
2174 | dst_reg->smin_value = S64_MIN; | |
2175 | dst_reg->smax_value = S64_MAX; | |
2176 | } else { | |
2177 | dst_reg->smin_value = dst_reg->umin_value; | |
2178 | dst_reg->smax_value = dst_reg->umax_value; | |
2179 | } | |
48461135 JB |
2180 | break; |
2181 | case BPF_AND: | |
f1174f77 | 2182 | if (src_known && dst_known) { |
b03c9f9f EC |
2183 | __mark_reg_known(dst_reg, dst_reg->var_off.value & |
2184 | src_reg.var_off.value); | |
f1174f77 EC |
2185 | break; |
2186 | } | |
b03c9f9f EC |
2187 | /* We get our minimum from the var_off, since that's inherently |
2188 | * bitwise. Our maximum is the minimum of the operands' maxima. | |
f23cc643 | 2189 | */ |
f1174f77 | 2190 | dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); |
b03c9f9f EC |
2191 | dst_reg->umin_value = dst_reg->var_off.value; |
2192 | dst_reg->umax_value = min(dst_reg->umax_value, umax_val); | |
2193 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
2194 | /* Lose signed bounds when ANDing negative numbers, | |
2195 | * ain't nobody got time for that. | |
2196 | */ | |
2197 | dst_reg->smin_value = S64_MIN; | |
2198 | dst_reg->smax_value = S64_MAX; | |
2199 | } else { | |
2200 | /* ANDing two positives gives a positive, so safe to | |
2201 | * cast result into s64. | |
2202 | */ | |
2203 | dst_reg->smin_value = dst_reg->umin_value; | |
2204 | dst_reg->smax_value = dst_reg->umax_value; | |
2205 | } | |
2206 | /* We may learn something more from the var_off */ | |
2207 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2208 | break; |
2209 | case BPF_OR: | |
2210 | if (src_known && dst_known) { | |
b03c9f9f EC |
2211 | __mark_reg_known(dst_reg, dst_reg->var_off.value | |
2212 | src_reg.var_off.value); | |
f1174f77 EC |
2213 | break; |
2214 | } | |
b03c9f9f EC |
2215 | /* We get our maximum from the var_off, and our minimum is the |
2216 | * maximum of the operands' minima | |
f1174f77 EC |
2217 | */ |
2218 | dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); | |
b03c9f9f EC |
2219 | dst_reg->umin_value = max(dst_reg->umin_value, umin_val); |
2220 | dst_reg->umax_value = dst_reg->var_off.value | | |
2221 | dst_reg->var_off.mask; | |
2222 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
2223 | /* Lose signed bounds when ORing negative numbers, | |
2224 | * ain't nobody got time for that. | |
2225 | */ | |
2226 | dst_reg->smin_value = S64_MIN; | |
2227 | dst_reg->smax_value = S64_MAX; | |
f1174f77 | 2228 | } else { |
b03c9f9f EC |
2229 | /* ORing two positives gives a positive, so safe to |
2230 | * cast result into s64. | |
2231 | */ | |
2232 | dst_reg->smin_value = dst_reg->umin_value; | |
2233 | dst_reg->smax_value = dst_reg->umax_value; | |
f1174f77 | 2234 | } |
b03c9f9f EC |
2235 | /* We may learn something more from the var_off */ |
2236 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2237 | break; |
2238 | case BPF_LSH: | |
468f6eaf JH |
2239 | if (umax_val >= insn_bitness) { |
2240 | /* Shifts greater than 31 or 63 are undefined. | |
2241 | * This includes shifts by a negative number. | |
b03c9f9f | 2242 | */ |
61bd5218 | 2243 | mark_reg_unknown(env, regs, insn->dst_reg); |
f1174f77 EC |
2244 | break; |
2245 | } | |
b03c9f9f EC |
2246 | /* We lose all sign bit information (except what we can pick |
2247 | * up from var_off) | |
48461135 | 2248 | */ |
b03c9f9f EC |
2249 | dst_reg->smin_value = S64_MIN; |
2250 | dst_reg->smax_value = S64_MAX; | |
2251 | /* If we might shift our top bit out, then we know nothing */ | |
2252 | if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { | |
2253 | dst_reg->umin_value = 0; | |
2254 | dst_reg->umax_value = U64_MAX; | |
d1174416 | 2255 | } else { |
b03c9f9f EC |
2256 | dst_reg->umin_value <<= umin_val; |
2257 | dst_reg->umax_value <<= umax_val; | |
d1174416 | 2258 | } |
b03c9f9f EC |
2259 | if (src_known) |
2260 | dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); | |
2261 | else | |
2262 | dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val); | |
2263 | /* We may learn something more from the var_off */ | |
2264 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2265 | break; |
2266 | case BPF_RSH: | |
468f6eaf JH |
2267 | if (umax_val >= insn_bitness) { |
2268 | /* Shifts greater than 31 or 63 are undefined. | |
2269 | * This includes shifts by a negative number. | |
b03c9f9f | 2270 | */ |
61bd5218 | 2271 | mark_reg_unknown(env, regs, insn->dst_reg); |
f1174f77 EC |
2272 | break; |
2273 | } | |
4374f256 EC |
2274 | /* BPF_RSH is an unsigned shift. If the value in dst_reg might |
2275 | * be negative, then either: | |
2276 | * 1) src_reg might be zero, so the sign bit of the result is | |
2277 | * unknown, so we lose our signed bounds | |
2278 | * 2) it's known negative, thus the unsigned bounds capture the | |
2279 | * signed bounds | |
2280 | * 3) the signed bounds cross zero, so they tell us nothing | |
2281 | * about the result | |
2282 | * If the value in dst_reg is known nonnegative, then again the | |
2283 | * unsigned bounts capture the signed bounds. | |
2284 | * Thus, in all cases it suffices to blow away our signed bounds | |
2285 | * and rely on inferring new ones from the unsigned bounds and | |
2286 | * var_off of the result. | |
2287 | */ | |
2288 | dst_reg->smin_value = S64_MIN; | |
2289 | dst_reg->smax_value = S64_MAX; | |
f1174f77 | 2290 | if (src_known) |
b03c9f9f EC |
2291 | dst_reg->var_off = tnum_rshift(dst_reg->var_off, |
2292 | umin_val); | |
f1174f77 | 2293 | else |
b03c9f9f EC |
2294 | dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val); |
2295 | dst_reg->umin_value >>= umax_val; | |
2296 | dst_reg->umax_value >>= umin_val; | |
2297 | /* We may learn something more from the var_off */ | |
2298 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2299 | break; |
2300 | default: | |
61bd5218 | 2301 | mark_reg_unknown(env, regs, insn->dst_reg); |
48461135 JB |
2302 | break; |
2303 | } | |
2304 | ||
468f6eaf JH |
2305 | if (BPF_CLASS(insn->code) != BPF_ALU64) { |
2306 | /* 32-bit ALU ops are (32,32)->32 */ | |
2307 | coerce_reg_to_size(dst_reg, 4); | |
2308 | coerce_reg_to_size(&src_reg, 4); | |
2309 | } | |
2310 | ||
b03c9f9f EC |
2311 | __reg_deduce_bounds(dst_reg); |
2312 | __reg_bound_offset(dst_reg); | |
f1174f77 EC |
2313 | return 0; |
2314 | } | |
2315 | ||
2316 | /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max | |
2317 | * and var_off. | |
2318 | */ | |
2319 | static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, | |
2320 | struct bpf_insn *insn) | |
2321 | { | |
638f5b90 | 2322 | struct bpf_reg_state *regs = cur_regs(env), *dst_reg, *src_reg; |
f1174f77 EC |
2323 | struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; |
2324 | u8 opcode = BPF_OP(insn->code); | |
f1174f77 EC |
2325 | |
2326 | dst_reg = ®s[insn->dst_reg]; | |
f1174f77 EC |
2327 | src_reg = NULL; |
2328 | if (dst_reg->type != SCALAR_VALUE) | |
2329 | ptr_reg = dst_reg; | |
2330 | if (BPF_SRC(insn->code) == BPF_X) { | |
2331 | src_reg = ®s[insn->src_reg]; | |
f1174f77 EC |
2332 | if (src_reg->type != SCALAR_VALUE) { |
2333 | if (dst_reg->type != SCALAR_VALUE) { | |
2334 | /* Combining two pointers by any ALU op yields | |
82abbf8d AS |
2335 | * an arbitrary scalar. Disallow all math except |
2336 | * pointer subtraction | |
f1174f77 | 2337 | */ |
82abbf8d AS |
2338 | if (opcode == BPF_SUB){ |
2339 | mark_reg_unknown(env, regs, insn->dst_reg); | |
2340 | return 0; | |
f1174f77 | 2341 | } |
82abbf8d AS |
2342 | verbose(env, "R%d pointer %s pointer prohibited\n", |
2343 | insn->dst_reg, | |
2344 | bpf_alu_string[opcode >> 4]); | |
2345 | return -EACCES; | |
f1174f77 EC |
2346 | } else { |
2347 | /* scalar += pointer | |
2348 | * This is legal, but we have to reverse our | |
2349 | * src/dest handling in computing the range | |
2350 | */ | |
82abbf8d AS |
2351 | return adjust_ptr_min_max_vals(env, insn, |
2352 | src_reg, dst_reg); | |
f1174f77 EC |
2353 | } |
2354 | } else if (ptr_reg) { | |
2355 | /* pointer += scalar */ | |
82abbf8d AS |
2356 | return adjust_ptr_min_max_vals(env, insn, |
2357 | dst_reg, src_reg); | |
f1174f77 EC |
2358 | } |
2359 | } else { | |
2360 | /* Pretend the src is a reg with a known value, since we only | |
2361 | * need to be able to read from this state. | |
2362 | */ | |
2363 | off_reg.type = SCALAR_VALUE; | |
b03c9f9f | 2364 | __mark_reg_known(&off_reg, insn->imm); |
f1174f77 | 2365 | src_reg = &off_reg; |
82abbf8d AS |
2366 | if (ptr_reg) /* pointer += K */ |
2367 | return adjust_ptr_min_max_vals(env, insn, | |
2368 | ptr_reg, src_reg); | |
f1174f77 EC |
2369 | } |
2370 | ||
2371 | /* Got here implies adding two SCALAR_VALUEs */ | |
2372 | if (WARN_ON_ONCE(ptr_reg)) { | |
638f5b90 | 2373 | print_verifier_state(env, env->cur_state); |
61bd5218 | 2374 | verbose(env, "verifier internal error: unexpected ptr_reg\n"); |
f1174f77 EC |
2375 | return -EINVAL; |
2376 | } | |
2377 | if (WARN_ON(!src_reg)) { | |
638f5b90 | 2378 | print_verifier_state(env, env->cur_state); |
61bd5218 | 2379 | verbose(env, "verifier internal error: no src_reg\n"); |
f1174f77 EC |
2380 | return -EINVAL; |
2381 | } | |
2382 | return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg); | |
48461135 JB |
2383 | } |
2384 | ||
17a52670 | 2385 | /* check validity of 32-bit and 64-bit arithmetic operations */ |
58e2af8b | 2386 | static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2387 | { |
638f5b90 | 2388 | struct bpf_reg_state *regs = cur_regs(env); |
17a52670 AS |
2389 | u8 opcode = BPF_OP(insn->code); |
2390 | int err; | |
2391 | ||
2392 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
2393 | if (opcode == BPF_NEG) { | |
2394 | if (BPF_SRC(insn->code) != 0 || | |
2395 | insn->src_reg != BPF_REG_0 || | |
2396 | insn->off != 0 || insn->imm != 0) { | |
61bd5218 | 2397 | verbose(env, "BPF_NEG uses reserved fields\n"); |
17a52670 AS |
2398 | return -EINVAL; |
2399 | } | |
2400 | } else { | |
2401 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
e67b8a68 EC |
2402 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || |
2403 | BPF_CLASS(insn->code) == BPF_ALU64) { | |
61bd5218 | 2404 | verbose(env, "BPF_END uses reserved fields\n"); |
17a52670 AS |
2405 | return -EINVAL; |
2406 | } | |
2407 | } | |
2408 | ||
2409 | /* check src operand */ | |
dc503a8a | 2410 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2411 | if (err) |
2412 | return err; | |
2413 | ||
1be7f75d | 2414 | if (is_pointer_value(env, insn->dst_reg)) { |
61bd5218 | 2415 | verbose(env, "R%d pointer arithmetic prohibited\n", |
1be7f75d AS |
2416 | insn->dst_reg); |
2417 | return -EACCES; | |
2418 | } | |
2419 | ||
17a52670 | 2420 | /* check dest operand */ |
dc503a8a | 2421 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2422 | if (err) |
2423 | return err; | |
2424 | ||
2425 | } else if (opcode == BPF_MOV) { | |
2426 | ||
2427 | if (BPF_SRC(insn->code) == BPF_X) { | |
2428 | if (insn->imm != 0 || insn->off != 0) { | |
61bd5218 | 2429 | verbose(env, "BPF_MOV uses reserved fields\n"); |
17a52670 AS |
2430 | return -EINVAL; |
2431 | } | |
2432 | ||
2433 | /* check src operand */ | |
dc503a8a | 2434 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2435 | if (err) |
2436 | return err; | |
2437 | } else { | |
2438 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
61bd5218 | 2439 | verbose(env, "BPF_MOV uses reserved fields\n"); |
17a52670 AS |
2440 | return -EINVAL; |
2441 | } | |
2442 | } | |
2443 | ||
2444 | /* check dest operand */ | |
dc503a8a | 2445 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2446 | if (err) |
2447 | return err; | |
2448 | ||
2449 | if (BPF_SRC(insn->code) == BPF_X) { | |
2450 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
2451 | /* case: R1 = R2 | |
2452 | * copy register state to dest reg | |
2453 | */ | |
2454 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
8fe2d6cc | 2455 | regs[insn->dst_reg].live |= REG_LIVE_WRITTEN; |
17a52670 | 2456 | } else { |
f1174f77 | 2457 | /* R1 = (u32) R2 */ |
1be7f75d | 2458 | if (is_pointer_value(env, insn->src_reg)) { |
61bd5218 JK |
2459 | verbose(env, |
2460 | "R%d partial copy of pointer\n", | |
1be7f75d AS |
2461 | insn->src_reg); |
2462 | return -EACCES; | |
2463 | } | |
61bd5218 | 2464 | mark_reg_unknown(env, regs, insn->dst_reg); |
0c17d1d2 | 2465 | coerce_reg_to_size(®s[insn->dst_reg], 4); |
17a52670 AS |
2466 | } |
2467 | } else { | |
2468 | /* case: R = imm | |
2469 | * remember the value we stored into this reg | |
2470 | */ | |
f1174f77 | 2471 | regs[insn->dst_reg].type = SCALAR_VALUE; |
95a762e2 JH |
2472 | if (BPF_CLASS(insn->code) == BPF_ALU64) { |
2473 | __mark_reg_known(regs + insn->dst_reg, | |
2474 | insn->imm); | |
2475 | } else { | |
2476 | __mark_reg_known(regs + insn->dst_reg, | |
2477 | (u32)insn->imm); | |
2478 | } | |
17a52670 AS |
2479 | } |
2480 | ||
2481 | } else if (opcode > BPF_END) { | |
61bd5218 | 2482 | verbose(env, "invalid BPF_ALU opcode %x\n", opcode); |
17a52670 AS |
2483 | return -EINVAL; |
2484 | ||
2485 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
2486 | ||
17a52670 AS |
2487 | if (BPF_SRC(insn->code) == BPF_X) { |
2488 | if (insn->imm != 0 || insn->off != 0) { | |
61bd5218 | 2489 | verbose(env, "BPF_ALU uses reserved fields\n"); |
17a52670 AS |
2490 | return -EINVAL; |
2491 | } | |
2492 | /* check src1 operand */ | |
dc503a8a | 2493 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2494 | if (err) |
2495 | return err; | |
2496 | } else { | |
2497 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
61bd5218 | 2498 | verbose(env, "BPF_ALU uses reserved fields\n"); |
17a52670 AS |
2499 | return -EINVAL; |
2500 | } | |
2501 | } | |
2502 | ||
2503 | /* check src2 operand */ | |
dc503a8a | 2504 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2505 | if (err) |
2506 | return err; | |
2507 | ||
2508 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
2509 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
61bd5218 | 2510 | verbose(env, "div by zero\n"); |
17a52670 AS |
2511 | return -EINVAL; |
2512 | } | |
2513 | ||
7891a87e DB |
2514 | if (opcode == BPF_ARSH && BPF_CLASS(insn->code) != BPF_ALU64) { |
2515 | verbose(env, "BPF_ARSH not supported for 32 bit ALU\n"); | |
2516 | return -EINVAL; | |
2517 | } | |
2518 | ||
229394e8 RV |
2519 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
2520 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
2521 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
2522 | ||
2523 | if (insn->imm < 0 || insn->imm >= size) { | |
61bd5218 | 2524 | verbose(env, "invalid shift %d\n", insn->imm); |
229394e8 RV |
2525 | return -EINVAL; |
2526 | } | |
2527 | } | |
2528 | ||
1a0dc1ac | 2529 | /* check dest operand */ |
dc503a8a | 2530 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
1a0dc1ac AS |
2531 | if (err) |
2532 | return err; | |
2533 | ||
f1174f77 | 2534 | return adjust_reg_min_max_vals(env, insn); |
17a52670 AS |
2535 | } |
2536 | ||
2537 | return 0; | |
2538 | } | |
2539 | ||
58e2af8b | 2540 | static void find_good_pkt_pointers(struct bpf_verifier_state *state, |
de8f3a83 | 2541 | struct bpf_reg_state *dst_reg, |
f8ddadc4 | 2542 | enum bpf_reg_type type, |
fb2a311a | 2543 | bool range_right_open) |
969bf05e | 2544 | { |
58e2af8b | 2545 | struct bpf_reg_state *regs = state->regs, *reg; |
fb2a311a | 2546 | u16 new_range; |
969bf05e | 2547 | int i; |
2d2be8ca | 2548 | |
fb2a311a DB |
2549 | if (dst_reg->off < 0 || |
2550 | (dst_reg->off == 0 && range_right_open)) | |
f1174f77 EC |
2551 | /* This doesn't give us any range */ |
2552 | return; | |
2553 | ||
b03c9f9f EC |
2554 | if (dst_reg->umax_value > MAX_PACKET_OFF || |
2555 | dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) | |
f1174f77 EC |
2556 | /* Risk of overflow. For instance, ptr + (1<<63) may be less |
2557 | * than pkt_end, but that's because it's also less than pkt. | |
2558 | */ | |
2559 | return; | |
2560 | ||
fb2a311a DB |
2561 | new_range = dst_reg->off; |
2562 | if (range_right_open) | |
2563 | new_range--; | |
2564 | ||
2565 | /* Examples for register markings: | |
2d2be8ca | 2566 | * |
fb2a311a | 2567 | * pkt_data in dst register: |
2d2be8ca DB |
2568 | * |
2569 | * r2 = r3; | |
2570 | * r2 += 8; | |
2571 | * if (r2 > pkt_end) goto <handle exception> | |
2572 | * <access okay> | |
2573 | * | |
b4e432f1 DB |
2574 | * r2 = r3; |
2575 | * r2 += 8; | |
2576 | * if (r2 < pkt_end) goto <access okay> | |
2577 | * <handle exception> | |
2578 | * | |
2d2be8ca DB |
2579 | * Where: |
2580 | * r2 == dst_reg, pkt_end == src_reg | |
2581 | * r2=pkt(id=n,off=8,r=0) | |
2582 | * r3=pkt(id=n,off=0,r=0) | |
2583 | * | |
fb2a311a | 2584 | * pkt_data in src register: |
2d2be8ca DB |
2585 | * |
2586 | * r2 = r3; | |
2587 | * r2 += 8; | |
2588 | * if (pkt_end >= r2) goto <access okay> | |
2589 | * <handle exception> | |
2590 | * | |
b4e432f1 DB |
2591 | * r2 = r3; |
2592 | * r2 += 8; | |
2593 | * if (pkt_end <= r2) goto <handle exception> | |
2594 | * <access okay> | |
2595 | * | |
2d2be8ca DB |
2596 | * Where: |
2597 | * pkt_end == dst_reg, r2 == src_reg | |
2598 | * r2=pkt(id=n,off=8,r=0) | |
2599 | * r3=pkt(id=n,off=0,r=0) | |
2600 | * | |
2601 | * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
fb2a311a DB |
2602 | * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8) |
2603 | * and [r3, r3 + 8-1) respectively is safe to access depending on | |
2604 | * the check. | |
969bf05e | 2605 | */ |
2d2be8ca | 2606 | |
f1174f77 EC |
2607 | /* If our ids match, then we must have the same max_value. And we |
2608 | * don't care about the other reg's fixed offset, since if it's too big | |
2609 | * the range won't allow anything. | |
2610 | * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. | |
2611 | */ | |
969bf05e | 2612 | for (i = 0; i < MAX_BPF_REG; i++) |
de8f3a83 | 2613 | if (regs[i].type == type && regs[i].id == dst_reg->id) |
b1977682 | 2614 | /* keep the maximum range already checked */ |
fb2a311a | 2615 | regs[i].range = max(regs[i].range, new_range); |
969bf05e | 2616 | |
638f5b90 AS |
2617 | for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { |
2618 | if (state->stack[i].slot_type[0] != STACK_SPILL) | |
969bf05e | 2619 | continue; |
638f5b90 | 2620 | reg = &state->stack[i].spilled_ptr; |
de8f3a83 | 2621 | if (reg->type == type && reg->id == dst_reg->id) |
b06723da | 2622 | reg->range = max(reg->range, new_range); |
969bf05e AS |
2623 | } |
2624 | } | |
2625 | ||
48461135 JB |
2626 | /* Adjusts the register min/max values in the case that the dst_reg is the |
2627 | * variable register that we are working on, and src_reg is a constant or we're | |
2628 | * simply doing a BPF_K check. | |
f1174f77 | 2629 | * In JEQ/JNE cases we also adjust the var_off values. |
48461135 JB |
2630 | */ |
2631 | static void reg_set_min_max(struct bpf_reg_state *true_reg, | |
2632 | struct bpf_reg_state *false_reg, u64 val, | |
2633 | u8 opcode) | |
2634 | { | |
f1174f77 EC |
2635 | /* If the dst_reg is a pointer, we can't learn anything about its |
2636 | * variable offset from the compare (unless src_reg were a pointer into | |
2637 | * the same object, but we don't bother with that. | |
2638 | * Since false_reg and true_reg have the same type by construction, we | |
2639 | * only need to check one of them for pointerness. | |
2640 | */ | |
2641 | if (__is_pointer_value(false, false_reg)) | |
2642 | return; | |
4cabc5b1 | 2643 | |
48461135 JB |
2644 | switch (opcode) { |
2645 | case BPF_JEQ: | |
2646 | /* If this is false then we know nothing Jon Snow, but if it is | |
2647 | * true then we know for sure. | |
2648 | */ | |
b03c9f9f | 2649 | __mark_reg_known(true_reg, val); |
48461135 JB |
2650 | break; |
2651 | case BPF_JNE: | |
2652 | /* If this is true we know nothing Jon Snow, but if it is false | |
2653 | * we know the value for sure; | |
2654 | */ | |
b03c9f9f | 2655 | __mark_reg_known(false_reg, val); |
48461135 JB |
2656 | break; |
2657 | case BPF_JGT: | |
b03c9f9f EC |
2658 | false_reg->umax_value = min(false_reg->umax_value, val); |
2659 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2660 | break; | |
48461135 | 2661 | case BPF_JSGT: |
b03c9f9f EC |
2662 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); |
2663 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
48461135 | 2664 | break; |
b4e432f1 DB |
2665 | case BPF_JLT: |
2666 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2667 | true_reg->umax_value = min(true_reg->umax_value, val - 1); | |
2668 | break; | |
2669 | case BPF_JSLT: | |
2670 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
2671 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); | |
2672 | break; | |
48461135 | 2673 | case BPF_JGE: |
b03c9f9f EC |
2674 | false_reg->umax_value = min(false_reg->umax_value, val - 1); |
2675 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2676 | break; | |
48461135 | 2677 | case BPF_JSGE: |
b03c9f9f EC |
2678 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); |
2679 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
48461135 | 2680 | break; |
b4e432f1 DB |
2681 | case BPF_JLE: |
2682 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2683 | true_reg->umax_value = min(true_reg->umax_value, val); | |
2684 | break; | |
2685 | case BPF_JSLE: | |
2686 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
2687 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); | |
2688 | break; | |
48461135 JB |
2689 | default: |
2690 | break; | |
2691 | } | |
2692 | ||
b03c9f9f EC |
2693 | __reg_deduce_bounds(false_reg); |
2694 | __reg_deduce_bounds(true_reg); | |
2695 | /* We might have learned some bits from the bounds. */ | |
2696 | __reg_bound_offset(false_reg); | |
2697 | __reg_bound_offset(true_reg); | |
2698 | /* Intersecting with the old var_off might have improved our bounds | |
2699 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2700 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2701 | */ | |
2702 | __update_reg_bounds(false_reg); | |
2703 | __update_reg_bounds(true_reg); | |
48461135 JB |
2704 | } |
2705 | ||
f1174f77 EC |
2706 | /* Same as above, but for the case that dst_reg holds a constant and src_reg is |
2707 | * the variable reg. | |
48461135 JB |
2708 | */ |
2709 | static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, | |
2710 | struct bpf_reg_state *false_reg, u64 val, | |
2711 | u8 opcode) | |
2712 | { | |
f1174f77 EC |
2713 | if (__is_pointer_value(false, false_reg)) |
2714 | return; | |
4cabc5b1 | 2715 | |
48461135 JB |
2716 | switch (opcode) { |
2717 | case BPF_JEQ: | |
2718 | /* If this is false then we know nothing Jon Snow, but if it is | |
2719 | * true then we know for sure. | |
2720 | */ | |
b03c9f9f | 2721 | __mark_reg_known(true_reg, val); |
48461135 JB |
2722 | break; |
2723 | case BPF_JNE: | |
2724 | /* If this is true we know nothing Jon Snow, but if it is false | |
2725 | * we know the value for sure; | |
2726 | */ | |
b03c9f9f | 2727 | __mark_reg_known(false_reg, val); |
48461135 JB |
2728 | break; |
2729 | case BPF_JGT: | |
b03c9f9f EC |
2730 | true_reg->umax_value = min(true_reg->umax_value, val - 1); |
2731 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2732 | break; | |
48461135 | 2733 | case BPF_JSGT: |
b03c9f9f EC |
2734 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); |
2735 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
48461135 | 2736 | break; |
b4e432f1 DB |
2737 | case BPF_JLT: |
2738 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2739 | false_reg->umax_value = min(false_reg->umax_value, val); | |
2740 | break; | |
2741 | case BPF_JSLT: | |
2742 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
2743 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); | |
2744 | break; | |
48461135 | 2745 | case BPF_JGE: |
b03c9f9f EC |
2746 | true_reg->umax_value = min(true_reg->umax_value, val); |
2747 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2748 | break; | |
48461135 | 2749 | case BPF_JSGE: |
b03c9f9f EC |
2750 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); |
2751 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
48461135 | 2752 | break; |
b4e432f1 DB |
2753 | case BPF_JLE: |
2754 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2755 | false_reg->umax_value = min(false_reg->umax_value, val - 1); | |
2756 | break; | |
2757 | case BPF_JSLE: | |
2758 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
2759 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); | |
2760 | break; | |
48461135 JB |
2761 | default: |
2762 | break; | |
2763 | } | |
2764 | ||
b03c9f9f EC |
2765 | __reg_deduce_bounds(false_reg); |
2766 | __reg_deduce_bounds(true_reg); | |
2767 | /* We might have learned some bits from the bounds. */ | |
2768 | __reg_bound_offset(false_reg); | |
2769 | __reg_bound_offset(true_reg); | |
2770 | /* Intersecting with the old var_off might have improved our bounds | |
2771 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2772 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2773 | */ | |
2774 | __update_reg_bounds(false_reg); | |
2775 | __update_reg_bounds(true_reg); | |
f1174f77 EC |
2776 | } |
2777 | ||
2778 | /* Regs are known to be equal, so intersect their min/max/var_off */ | |
2779 | static void __reg_combine_min_max(struct bpf_reg_state *src_reg, | |
2780 | struct bpf_reg_state *dst_reg) | |
2781 | { | |
b03c9f9f EC |
2782 | src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, |
2783 | dst_reg->umin_value); | |
2784 | src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, | |
2785 | dst_reg->umax_value); | |
2786 | src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, | |
2787 | dst_reg->smin_value); | |
2788 | src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, | |
2789 | dst_reg->smax_value); | |
f1174f77 EC |
2790 | src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, |
2791 | dst_reg->var_off); | |
b03c9f9f EC |
2792 | /* We might have learned new bounds from the var_off. */ |
2793 | __update_reg_bounds(src_reg); | |
2794 | __update_reg_bounds(dst_reg); | |
2795 | /* We might have learned something about the sign bit. */ | |
2796 | __reg_deduce_bounds(src_reg); | |
2797 | __reg_deduce_bounds(dst_reg); | |
2798 | /* We might have learned some bits from the bounds. */ | |
2799 | __reg_bound_offset(src_reg); | |
2800 | __reg_bound_offset(dst_reg); | |
2801 | /* Intersecting with the old var_off might have improved our bounds | |
2802 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2803 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2804 | */ | |
2805 | __update_reg_bounds(src_reg); | |
2806 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2807 | } |
2808 | ||
2809 | static void reg_combine_min_max(struct bpf_reg_state *true_src, | |
2810 | struct bpf_reg_state *true_dst, | |
2811 | struct bpf_reg_state *false_src, | |
2812 | struct bpf_reg_state *false_dst, | |
2813 | u8 opcode) | |
2814 | { | |
2815 | switch (opcode) { | |
2816 | case BPF_JEQ: | |
2817 | __reg_combine_min_max(true_src, true_dst); | |
2818 | break; | |
2819 | case BPF_JNE: | |
2820 | __reg_combine_min_max(false_src, false_dst); | |
b03c9f9f | 2821 | break; |
4cabc5b1 | 2822 | } |
48461135 JB |
2823 | } |
2824 | ||
57a09bf0 | 2825 | static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, |
f1174f77 | 2826 | bool is_null) |
57a09bf0 TG |
2827 | { |
2828 | struct bpf_reg_state *reg = ®s[regno]; | |
2829 | ||
2830 | if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { | |
f1174f77 EC |
2831 | /* Old offset (both fixed and variable parts) should |
2832 | * have been known-zero, because we don't allow pointer | |
2833 | * arithmetic on pointers that might be NULL. | |
2834 | */ | |
b03c9f9f EC |
2835 | if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || |
2836 | !tnum_equals_const(reg->var_off, 0) || | |
f1174f77 | 2837 | reg->off)) { |
b03c9f9f EC |
2838 | __mark_reg_known_zero(reg); |
2839 | reg->off = 0; | |
f1174f77 EC |
2840 | } |
2841 | if (is_null) { | |
2842 | reg->type = SCALAR_VALUE; | |
56f668df MKL |
2843 | } else if (reg->map_ptr->inner_map_meta) { |
2844 | reg->type = CONST_PTR_TO_MAP; | |
2845 | reg->map_ptr = reg->map_ptr->inner_map_meta; | |
2846 | } else { | |
f1174f77 | 2847 | reg->type = PTR_TO_MAP_VALUE; |
56f668df | 2848 | } |
a08dd0da DB |
2849 | /* We don't need id from this point onwards anymore, thus we |
2850 | * should better reset it, so that state pruning has chances | |
2851 | * to take effect. | |
2852 | */ | |
2853 | reg->id = 0; | |
57a09bf0 TG |
2854 | } |
2855 | } | |
2856 | ||
2857 | /* The logic is similar to find_good_pkt_pointers(), both could eventually | |
2858 | * be folded together at some point. | |
2859 | */ | |
2860 | static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, | |
f1174f77 | 2861 | bool is_null) |
57a09bf0 TG |
2862 | { |
2863 | struct bpf_reg_state *regs = state->regs; | |
a08dd0da | 2864 | u32 id = regs[regno].id; |
57a09bf0 TG |
2865 | int i; |
2866 | ||
2867 | for (i = 0; i < MAX_BPF_REG; i++) | |
f1174f77 | 2868 | mark_map_reg(regs, i, id, is_null); |
57a09bf0 | 2869 | |
638f5b90 AS |
2870 | for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) { |
2871 | if (state->stack[i].slot_type[0] != STACK_SPILL) | |
57a09bf0 | 2872 | continue; |
638f5b90 | 2873 | mark_map_reg(&state->stack[i].spilled_ptr, 0, id, is_null); |
57a09bf0 TG |
2874 | } |
2875 | } | |
2876 | ||
5beca081 DB |
2877 | static bool try_match_pkt_pointers(const struct bpf_insn *insn, |
2878 | struct bpf_reg_state *dst_reg, | |
2879 | struct bpf_reg_state *src_reg, | |
2880 | struct bpf_verifier_state *this_branch, | |
2881 | struct bpf_verifier_state *other_branch) | |
2882 | { | |
2883 | if (BPF_SRC(insn->code) != BPF_X) | |
2884 | return false; | |
2885 | ||
2886 | switch (BPF_OP(insn->code)) { | |
2887 | case BPF_JGT: | |
2888 | if ((dst_reg->type == PTR_TO_PACKET && | |
2889 | src_reg->type == PTR_TO_PACKET_END) || | |
2890 | (dst_reg->type == PTR_TO_PACKET_META && | |
2891 | reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { | |
2892 | /* pkt_data' > pkt_end, pkt_meta' > pkt_data */ | |
2893 | find_good_pkt_pointers(this_branch, dst_reg, | |
2894 | dst_reg->type, false); | |
2895 | } else if ((dst_reg->type == PTR_TO_PACKET_END && | |
2896 | src_reg->type == PTR_TO_PACKET) || | |
2897 | (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2898 | src_reg->type == PTR_TO_PACKET_META)) { | |
2899 | /* pkt_end > pkt_data', pkt_data > pkt_meta' */ | |
2900 | find_good_pkt_pointers(other_branch, src_reg, | |
2901 | src_reg->type, true); | |
2902 | } else { | |
2903 | return false; | |
2904 | } | |
2905 | break; | |
2906 | case BPF_JLT: | |
2907 | if ((dst_reg->type == PTR_TO_PACKET && | |
2908 | src_reg->type == PTR_TO_PACKET_END) || | |
2909 | (dst_reg->type == PTR_TO_PACKET_META && | |
2910 | reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { | |
2911 | /* pkt_data' < pkt_end, pkt_meta' < pkt_data */ | |
2912 | find_good_pkt_pointers(other_branch, dst_reg, | |
2913 | dst_reg->type, true); | |
2914 | } else if ((dst_reg->type == PTR_TO_PACKET_END && | |
2915 | src_reg->type == PTR_TO_PACKET) || | |
2916 | (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2917 | src_reg->type == PTR_TO_PACKET_META)) { | |
2918 | /* pkt_end < pkt_data', pkt_data > pkt_meta' */ | |
2919 | find_good_pkt_pointers(this_branch, src_reg, | |
2920 | src_reg->type, false); | |
2921 | } else { | |
2922 | return false; | |
2923 | } | |
2924 | break; | |
2925 | case BPF_JGE: | |
2926 | if ((dst_reg->type == PTR_TO_PACKET && | |
2927 | src_reg->type == PTR_TO_PACKET_END) || | |
2928 | (dst_reg->type == PTR_TO_PACKET_META && | |
2929 | reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { | |
2930 | /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */ | |
2931 | find_good_pkt_pointers(this_branch, dst_reg, | |
2932 | dst_reg->type, true); | |
2933 | } else if ((dst_reg->type == PTR_TO_PACKET_END && | |
2934 | src_reg->type == PTR_TO_PACKET) || | |
2935 | (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2936 | src_reg->type == PTR_TO_PACKET_META)) { | |
2937 | /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */ | |
2938 | find_good_pkt_pointers(other_branch, src_reg, | |
2939 | src_reg->type, false); | |
2940 | } else { | |
2941 | return false; | |
2942 | } | |
2943 | break; | |
2944 | case BPF_JLE: | |
2945 | if ((dst_reg->type == PTR_TO_PACKET && | |
2946 | src_reg->type == PTR_TO_PACKET_END) || | |
2947 | (dst_reg->type == PTR_TO_PACKET_META && | |
2948 | reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) { | |
2949 | /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */ | |
2950 | find_good_pkt_pointers(other_branch, dst_reg, | |
2951 | dst_reg->type, false); | |
2952 | } else if ((dst_reg->type == PTR_TO_PACKET_END && | |
2953 | src_reg->type == PTR_TO_PACKET) || | |
2954 | (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2955 | src_reg->type == PTR_TO_PACKET_META)) { | |
2956 | /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */ | |
2957 | find_good_pkt_pointers(this_branch, src_reg, | |
2958 | src_reg->type, true); | |
2959 | } else { | |
2960 | return false; | |
2961 | } | |
2962 | break; | |
2963 | default: | |
2964 | return false; | |
2965 | } | |
2966 | ||
2967 | return true; | |
2968 | } | |
2969 | ||
58e2af8b | 2970 | static int check_cond_jmp_op(struct bpf_verifier_env *env, |
17a52670 AS |
2971 | struct bpf_insn *insn, int *insn_idx) |
2972 | { | |
638f5b90 | 2973 | struct bpf_verifier_state *other_branch, *this_branch = env->cur_state; |
58e2af8b | 2974 | struct bpf_reg_state *regs = this_branch->regs, *dst_reg; |
17a52670 AS |
2975 | u8 opcode = BPF_OP(insn->code); |
2976 | int err; | |
2977 | ||
b4e432f1 | 2978 | if (opcode > BPF_JSLE) { |
61bd5218 | 2979 | verbose(env, "invalid BPF_JMP opcode %x\n", opcode); |
17a52670 AS |
2980 | return -EINVAL; |
2981 | } | |
2982 | ||
2983 | if (BPF_SRC(insn->code) == BPF_X) { | |
2984 | if (insn->imm != 0) { | |
61bd5218 | 2985 | verbose(env, "BPF_JMP uses reserved fields\n"); |
17a52670 AS |
2986 | return -EINVAL; |
2987 | } | |
2988 | ||
2989 | /* check src1 operand */ | |
dc503a8a | 2990 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2991 | if (err) |
2992 | return err; | |
1be7f75d AS |
2993 | |
2994 | if (is_pointer_value(env, insn->src_reg)) { | |
61bd5218 | 2995 | verbose(env, "R%d pointer comparison prohibited\n", |
1be7f75d AS |
2996 | insn->src_reg); |
2997 | return -EACCES; | |
2998 | } | |
17a52670 AS |
2999 | } else { |
3000 | if (insn->src_reg != BPF_REG_0) { | |
61bd5218 | 3001 | verbose(env, "BPF_JMP uses reserved fields\n"); |
17a52670 AS |
3002 | return -EINVAL; |
3003 | } | |
3004 | } | |
3005 | ||
3006 | /* check src2 operand */ | |
dc503a8a | 3007 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3008 | if (err) |
3009 | return err; | |
3010 | ||
1a0dc1ac AS |
3011 | dst_reg = ®s[insn->dst_reg]; |
3012 | ||
17a52670 AS |
3013 | /* detect if R == 0 where R was initialized to zero earlier */ |
3014 | if (BPF_SRC(insn->code) == BPF_K && | |
3015 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
f1174f77 EC |
3016 | dst_reg->type == SCALAR_VALUE && |
3017 | tnum_equals_const(dst_reg->var_off, insn->imm)) { | |
17a52670 AS |
3018 | if (opcode == BPF_JEQ) { |
3019 | /* if (imm == imm) goto pc+off; | |
3020 | * only follow the goto, ignore fall-through | |
3021 | */ | |
3022 | *insn_idx += insn->off; | |
3023 | return 0; | |
3024 | } else { | |
3025 | /* if (imm != imm) goto pc+off; | |
3026 | * only follow fall-through branch, since | |
3027 | * that's where the program will go | |
3028 | */ | |
3029 | return 0; | |
3030 | } | |
3031 | } | |
3032 | ||
3033 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
3034 | if (!other_branch) | |
3035 | return -EFAULT; | |
3036 | ||
48461135 JB |
3037 | /* detect if we are comparing against a constant value so we can adjust |
3038 | * our min/max values for our dst register. | |
f1174f77 EC |
3039 | * this is only legit if both are scalars (or pointers to the same |
3040 | * object, I suppose, but we don't support that right now), because | |
3041 | * otherwise the different base pointers mean the offsets aren't | |
3042 | * comparable. | |
48461135 JB |
3043 | */ |
3044 | if (BPF_SRC(insn->code) == BPF_X) { | |
f1174f77 EC |
3045 | if (dst_reg->type == SCALAR_VALUE && |
3046 | regs[insn->src_reg].type == SCALAR_VALUE) { | |
3047 | if (tnum_is_const(regs[insn->src_reg].var_off)) | |
3048 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
3049 | dst_reg, regs[insn->src_reg].var_off.value, | |
3050 | opcode); | |
3051 | else if (tnum_is_const(dst_reg->var_off)) | |
3052 | reg_set_min_max_inv(&other_branch->regs[insn->src_reg], | |
3053 | ®s[insn->src_reg], | |
3054 | dst_reg->var_off.value, opcode); | |
3055 | else if (opcode == BPF_JEQ || opcode == BPF_JNE) | |
3056 | /* Comparing for equality, we can combine knowledge */ | |
3057 | reg_combine_min_max(&other_branch->regs[insn->src_reg], | |
3058 | &other_branch->regs[insn->dst_reg], | |
3059 | ®s[insn->src_reg], | |
3060 | ®s[insn->dst_reg], opcode); | |
3061 | } | |
3062 | } else if (dst_reg->type == SCALAR_VALUE) { | |
48461135 JB |
3063 | reg_set_min_max(&other_branch->regs[insn->dst_reg], |
3064 | dst_reg, insn->imm, opcode); | |
3065 | } | |
3066 | ||
58e2af8b | 3067 | /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ |
17a52670 | 3068 | if (BPF_SRC(insn->code) == BPF_K && |
1a0dc1ac AS |
3069 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
3070 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
57a09bf0 TG |
3071 | /* Mark all identical map registers in each branch as either |
3072 | * safe or unknown depending R == 0 or R != 0 conditional. | |
3073 | */ | |
f1174f77 EC |
3074 | mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE); |
3075 | mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ); | |
5beca081 DB |
3076 | } else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg], |
3077 | this_branch, other_branch) && | |
3078 | is_pointer_value(env, insn->dst_reg)) { | |
61bd5218 JK |
3079 | verbose(env, "R%d pointer comparison prohibited\n", |
3080 | insn->dst_reg); | |
1be7f75d | 3081 | return -EACCES; |
17a52670 | 3082 | } |
61bd5218 JK |
3083 | if (env->log.level) |
3084 | print_verifier_state(env, this_branch); | |
17a52670 AS |
3085 | return 0; |
3086 | } | |
3087 | ||
0246e64d AS |
3088 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
3089 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
3090 | { | |
3091 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
3092 | ||
3093 | return (struct bpf_map *) (unsigned long) imm64; | |
3094 | } | |
3095 | ||
17a52670 | 3096 | /* verify BPF_LD_IMM64 instruction */ |
58e2af8b | 3097 | static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 3098 | { |
638f5b90 | 3099 | struct bpf_reg_state *regs = cur_regs(env); |
17a52670 AS |
3100 | int err; |
3101 | ||
3102 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
61bd5218 | 3103 | verbose(env, "invalid BPF_LD_IMM insn\n"); |
17a52670 AS |
3104 | return -EINVAL; |
3105 | } | |
3106 | if (insn->off != 0) { | |
61bd5218 | 3107 | verbose(env, "BPF_LD_IMM64 uses reserved fields\n"); |
17a52670 AS |
3108 | return -EINVAL; |
3109 | } | |
3110 | ||
dc503a8a | 3111 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
3112 | if (err) |
3113 | return err; | |
3114 | ||
6b173873 | 3115 | if (insn->src_reg == 0) { |
6b173873 JK |
3116 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; |
3117 | ||
f1174f77 | 3118 | regs[insn->dst_reg].type = SCALAR_VALUE; |
b03c9f9f | 3119 | __mark_reg_known(®s[insn->dst_reg], imm); |
17a52670 | 3120 | return 0; |
6b173873 | 3121 | } |
17a52670 AS |
3122 | |
3123 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
3124 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
3125 | ||
3126 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
3127 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
3128 | return 0; | |
3129 | } | |
3130 | ||
96be4325 DB |
3131 | static bool may_access_skb(enum bpf_prog_type type) |
3132 | { | |
3133 | switch (type) { | |
3134 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
3135 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 3136 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
3137 | return true; |
3138 | default: | |
3139 | return false; | |
3140 | } | |
3141 | } | |
3142 | ||
ddd872bc AS |
3143 | /* verify safety of LD_ABS|LD_IND instructions: |
3144 | * - they can only appear in the programs where ctx == skb | |
3145 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
3146 | * preserve R6-R9, and store return value into R0 | |
3147 | * | |
3148 | * Implicit input: | |
3149 | * ctx == skb == R6 == CTX | |
3150 | * | |
3151 | * Explicit input: | |
3152 | * SRC == any register | |
3153 | * IMM == 32-bit immediate | |
3154 | * | |
3155 | * Output: | |
3156 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
3157 | */ | |
58e2af8b | 3158 | static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) |
ddd872bc | 3159 | { |
638f5b90 | 3160 | struct bpf_reg_state *regs = cur_regs(env); |
ddd872bc | 3161 | u8 mode = BPF_MODE(insn->code); |
ddd872bc AS |
3162 | int i, err; |
3163 | ||
24701ece | 3164 | if (!may_access_skb(env->prog->type)) { |
61bd5218 | 3165 | verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
3166 | return -EINVAL; |
3167 | } | |
3168 | ||
3169 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 3170 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 3171 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
61bd5218 | 3172 | verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
3173 | return -EINVAL; |
3174 | } | |
3175 | ||
3176 | /* check whether implicit source operand (register R6) is readable */ | |
dc503a8a | 3177 | err = check_reg_arg(env, BPF_REG_6, SRC_OP); |
ddd872bc AS |
3178 | if (err) |
3179 | return err; | |
3180 | ||
3181 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
61bd5218 JK |
3182 | verbose(env, |
3183 | "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
ddd872bc AS |
3184 | return -EINVAL; |
3185 | } | |
3186 | ||
3187 | if (mode == BPF_IND) { | |
3188 | /* check explicit source operand */ | |
dc503a8a | 3189 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
ddd872bc AS |
3190 | if (err) |
3191 | return err; | |
3192 | } | |
3193 | ||
3194 | /* reset caller saved regs to unreadable */ | |
dc503a8a | 3195 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
61bd5218 | 3196 | mark_reg_not_init(env, regs, caller_saved[i]); |
dc503a8a EC |
3197 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
3198 | } | |
ddd872bc AS |
3199 | |
3200 | /* mark destination R0 register as readable, since it contains | |
dc503a8a EC |
3201 | * the value fetched from the packet. |
3202 | * Already marked as written above. | |
ddd872bc | 3203 | */ |
61bd5218 | 3204 | mark_reg_unknown(env, regs, BPF_REG_0); |
ddd872bc AS |
3205 | return 0; |
3206 | } | |
3207 | ||
390ee7e2 AS |
3208 | static int check_return_code(struct bpf_verifier_env *env) |
3209 | { | |
3210 | struct bpf_reg_state *reg; | |
3211 | struct tnum range = tnum_range(0, 1); | |
3212 | ||
3213 | switch (env->prog->type) { | |
3214 | case BPF_PROG_TYPE_CGROUP_SKB: | |
3215 | case BPF_PROG_TYPE_CGROUP_SOCK: | |
3216 | case BPF_PROG_TYPE_SOCK_OPS: | |
ebc614f6 | 3217 | case BPF_PROG_TYPE_CGROUP_DEVICE: |
390ee7e2 AS |
3218 | break; |
3219 | default: | |
3220 | return 0; | |
3221 | } | |
3222 | ||
638f5b90 | 3223 | reg = cur_regs(env) + BPF_REG_0; |
390ee7e2 | 3224 | if (reg->type != SCALAR_VALUE) { |
61bd5218 | 3225 | verbose(env, "At program exit the register R0 is not a known value (%s)\n", |
390ee7e2 AS |
3226 | reg_type_str[reg->type]); |
3227 | return -EINVAL; | |
3228 | } | |
3229 | ||
3230 | if (!tnum_in(range, reg->var_off)) { | |
61bd5218 | 3231 | verbose(env, "At program exit the register R0 "); |
390ee7e2 AS |
3232 | if (!tnum_is_unknown(reg->var_off)) { |
3233 | char tn_buf[48]; | |
3234 | ||
3235 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 3236 | verbose(env, "has value %s", tn_buf); |
390ee7e2 | 3237 | } else { |
61bd5218 | 3238 | verbose(env, "has unknown scalar value"); |
390ee7e2 | 3239 | } |
61bd5218 | 3240 | verbose(env, " should have been 0 or 1\n"); |
390ee7e2 AS |
3241 | return -EINVAL; |
3242 | } | |
3243 | return 0; | |
3244 | } | |
3245 | ||
475fb78f AS |
3246 | /* non-recursive DFS pseudo code |
3247 | * 1 procedure DFS-iterative(G,v): | |
3248 | * 2 label v as discovered | |
3249 | * 3 let S be a stack | |
3250 | * 4 S.push(v) | |
3251 | * 5 while S is not empty | |
3252 | * 6 t <- S.pop() | |
3253 | * 7 if t is what we're looking for: | |
3254 | * 8 return t | |
3255 | * 9 for all edges e in G.adjacentEdges(t) do | |
3256 | * 10 if edge e is already labelled | |
3257 | * 11 continue with the next edge | |
3258 | * 12 w <- G.adjacentVertex(t,e) | |
3259 | * 13 if vertex w is not discovered and not explored | |
3260 | * 14 label e as tree-edge | |
3261 | * 15 label w as discovered | |
3262 | * 16 S.push(w) | |
3263 | * 17 continue at 5 | |
3264 | * 18 else if vertex w is discovered | |
3265 | * 19 label e as back-edge | |
3266 | * 20 else | |
3267 | * 21 // vertex w is explored | |
3268 | * 22 label e as forward- or cross-edge | |
3269 | * 23 label t as explored | |
3270 | * 24 S.pop() | |
3271 | * | |
3272 | * convention: | |
3273 | * 0x10 - discovered | |
3274 | * 0x11 - discovered and fall-through edge labelled | |
3275 | * 0x12 - discovered and fall-through and branch edges labelled | |
3276 | * 0x20 - explored | |
3277 | */ | |
3278 | ||
3279 | enum { | |
3280 | DISCOVERED = 0x10, | |
3281 | EXPLORED = 0x20, | |
3282 | FALLTHROUGH = 1, | |
3283 | BRANCH = 2, | |
3284 | }; | |
3285 | ||
58e2af8b | 3286 | #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) |
f1bca824 | 3287 | |
475fb78f AS |
3288 | static int *insn_stack; /* stack of insns to process */ |
3289 | static int cur_stack; /* current stack index */ | |
3290 | static int *insn_state; | |
3291 | ||
3292 | /* t, w, e - match pseudo-code above: | |
3293 | * t - index of current instruction | |
3294 | * w - next instruction | |
3295 | * e - edge | |
3296 | */ | |
58e2af8b | 3297 | static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) |
475fb78f AS |
3298 | { |
3299 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
3300 | return 0; | |
3301 | ||
3302 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
3303 | return 0; | |
3304 | ||
3305 | if (w < 0 || w >= env->prog->len) { | |
61bd5218 | 3306 | verbose(env, "jump out of range from insn %d to %d\n", t, w); |
475fb78f AS |
3307 | return -EINVAL; |
3308 | } | |
3309 | ||
f1bca824 AS |
3310 | if (e == BRANCH) |
3311 | /* mark branch target for state pruning */ | |
3312 | env->explored_states[w] = STATE_LIST_MARK; | |
3313 | ||
475fb78f AS |
3314 | if (insn_state[w] == 0) { |
3315 | /* tree-edge */ | |
3316 | insn_state[t] = DISCOVERED | e; | |
3317 | insn_state[w] = DISCOVERED; | |
3318 | if (cur_stack >= env->prog->len) | |
3319 | return -E2BIG; | |
3320 | insn_stack[cur_stack++] = w; | |
3321 | return 1; | |
3322 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
61bd5218 | 3323 | verbose(env, "back-edge from insn %d to %d\n", t, w); |
475fb78f AS |
3324 | return -EINVAL; |
3325 | } else if (insn_state[w] == EXPLORED) { | |
3326 | /* forward- or cross-edge */ | |
3327 | insn_state[t] = DISCOVERED | e; | |
3328 | } else { | |
61bd5218 | 3329 | verbose(env, "insn state internal bug\n"); |
475fb78f AS |
3330 | return -EFAULT; |
3331 | } | |
3332 | return 0; | |
3333 | } | |
3334 | ||
3335 | /* non-recursive depth-first-search to detect loops in BPF program | |
3336 | * loop == back-edge in directed graph | |
3337 | */ | |
58e2af8b | 3338 | static int check_cfg(struct bpf_verifier_env *env) |
475fb78f AS |
3339 | { |
3340 | struct bpf_insn *insns = env->prog->insnsi; | |
3341 | int insn_cnt = env->prog->len; | |
3342 | int ret = 0; | |
3343 | int i, t; | |
3344 | ||
3345 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3346 | if (!insn_state) | |
3347 | return -ENOMEM; | |
3348 | ||
3349 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3350 | if (!insn_stack) { | |
3351 | kfree(insn_state); | |
3352 | return -ENOMEM; | |
3353 | } | |
3354 | ||
3355 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
3356 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
3357 | cur_stack = 1; | |
3358 | ||
3359 | peek_stack: | |
3360 | if (cur_stack == 0) | |
3361 | goto check_state; | |
3362 | t = insn_stack[cur_stack - 1]; | |
3363 | ||
3364 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
3365 | u8 opcode = BPF_OP(insns[t].code); | |
3366 | ||
3367 | if (opcode == BPF_EXIT) { | |
3368 | goto mark_explored; | |
3369 | } else if (opcode == BPF_CALL) { | |
3370 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3371 | if (ret == 1) | |
3372 | goto peek_stack; | |
3373 | else if (ret < 0) | |
3374 | goto err_free; | |
07016151 DB |
3375 | if (t + 1 < insn_cnt) |
3376 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3377 | } else if (opcode == BPF_JA) { |
3378 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
3379 | ret = -EINVAL; | |
3380 | goto err_free; | |
3381 | } | |
3382 | /* unconditional jump with single edge */ | |
3383 | ret = push_insn(t, t + insns[t].off + 1, | |
3384 | FALLTHROUGH, env); | |
3385 | if (ret == 1) | |
3386 | goto peek_stack; | |
3387 | else if (ret < 0) | |
3388 | goto err_free; | |
f1bca824 AS |
3389 | /* tell verifier to check for equivalent states |
3390 | * after every call and jump | |
3391 | */ | |
c3de6317 AS |
3392 | if (t + 1 < insn_cnt) |
3393 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3394 | } else { |
3395 | /* conditional jump with two edges */ | |
3c2ce60b | 3396 | env->explored_states[t] = STATE_LIST_MARK; |
475fb78f AS |
3397 | ret = push_insn(t, t + 1, FALLTHROUGH, env); |
3398 | if (ret == 1) | |
3399 | goto peek_stack; | |
3400 | else if (ret < 0) | |
3401 | goto err_free; | |
3402 | ||
3403 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
3404 | if (ret == 1) | |
3405 | goto peek_stack; | |
3406 | else if (ret < 0) | |
3407 | goto err_free; | |
3408 | } | |
3409 | } else { | |
3410 | /* all other non-branch instructions with single | |
3411 | * fall-through edge | |
3412 | */ | |
3413 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3414 | if (ret == 1) | |
3415 | goto peek_stack; | |
3416 | else if (ret < 0) | |
3417 | goto err_free; | |
3418 | } | |
3419 | ||
3420 | mark_explored: | |
3421 | insn_state[t] = EXPLORED; | |
3422 | if (cur_stack-- <= 0) { | |
61bd5218 | 3423 | verbose(env, "pop stack internal bug\n"); |
475fb78f AS |
3424 | ret = -EFAULT; |
3425 | goto err_free; | |
3426 | } | |
3427 | goto peek_stack; | |
3428 | ||
3429 | check_state: | |
3430 | for (i = 0; i < insn_cnt; i++) { | |
3431 | if (insn_state[i] != EXPLORED) { | |
61bd5218 | 3432 | verbose(env, "unreachable insn %d\n", i); |
475fb78f AS |
3433 | ret = -EINVAL; |
3434 | goto err_free; | |
3435 | } | |
3436 | } | |
3437 | ret = 0; /* cfg looks good */ | |
3438 | ||
3439 | err_free: | |
3440 | kfree(insn_state); | |
3441 | kfree(insn_stack); | |
3442 | return ret; | |
3443 | } | |
3444 | ||
f1174f77 EC |
3445 | /* check %cur's range satisfies %old's */ |
3446 | static bool range_within(struct bpf_reg_state *old, | |
3447 | struct bpf_reg_state *cur) | |
3448 | { | |
b03c9f9f EC |
3449 | return old->umin_value <= cur->umin_value && |
3450 | old->umax_value >= cur->umax_value && | |
3451 | old->smin_value <= cur->smin_value && | |
3452 | old->smax_value >= cur->smax_value; | |
f1174f77 EC |
3453 | } |
3454 | ||
3455 | /* Maximum number of register states that can exist at once */ | |
3456 | #define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) | |
3457 | struct idpair { | |
3458 | u32 old; | |
3459 | u32 cur; | |
3460 | }; | |
3461 | ||
3462 | /* If in the old state two registers had the same id, then they need to have | |
3463 | * the same id in the new state as well. But that id could be different from | |
3464 | * the old state, so we need to track the mapping from old to new ids. | |
3465 | * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent | |
3466 | * regs with old id 5 must also have new id 9 for the new state to be safe. But | |
3467 | * regs with a different old id could still have new id 9, we don't care about | |
3468 | * that. | |
3469 | * So we look through our idmap to see if this old id has been seen before. If | |
3470 | * so, we require the new id to match; otherwise, we add the id pair to the map. | |
969bf05e | 3471 | */ |
f1174f77 | 3472 | static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap) |
969bf05e | 3473 | { |
f1174f77 | 3474 | unsigned int i; |
969bf05e | 3475 | |
f1174f77 EC |
3476 | for (i = 0; i < ID_MAP_SIZE; i++) { |
3477 | if (!idmap[i].old) { | |
3478 | /* Reached an empty slot; haven't seen this id before */ | |
3479 | idmap[i].old = old_id; | |
3480 | idmap[i].cur = cur_id; | |
3481 | return true; | |
3482 | } | |
3483 | if (idmap[i].old == old_id) | |
3484 | return idmap[i].cur == cur_id; | |
3485 | } | |
3486 | /* We ran out of idmap slots, which should be impossible */ | |
3487 | WARN_ON_ONCE(1); | |
3488 | return false; | |
3489 | } | |
3490 | ||
3491 | /* Returns true if (rold safe implies rcur safe) */ | |
1b688a19 EC |
3492 | static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, |
3493 | struct idpair *idmap) | |
f1174f77 | 3494 | { |
dc503a8a EC |
3495 | if (!(rold->live & REG_LIVE_READ)) |
3496 | /* explored state didn't use this */ | |
3497 | return true; | |
3498 | ||
3499 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, live)) == 0) | |
969bf05e AS |
3500 | return true; |
3501 | ||
f1174f77 EC |
3502 | if (rold->type == NOT_INIT) |
3503 | /* explored state can't have used this */ | |
969bf05e | 3504 | return true; |
f1174f77 EC |
3505 | if (rcur->type == NOT_INIT) |
3506 | return false; | |
3507 | switch (rold->type) { | |
3508 | case SCALAR_VALUE: | |
3509 | if (rcur->type == SCALAR_VALUE) { | |
3510 | /* new val must satisfy old val knowledge */ | |
3511 | return range_within(rold, rcur) && | |
3512 | tnum_in(rold->var_off, rcur->var_off); | |
3513 | } else { | |
179d1c56 JH |
3514 | /* We're trying to use a pointer in place of a scalar. |
3515 | * Even if the scalar was unbounded, this could lead to | |
3516 | * pointer leaks because scalars are allowed to leak | |
3517 | * while pointers are not. We could make this safe in | |
3518 | * special cases if root is calling us, but it's | |
3519 | * probably not worth the hassle. | |
f1174f77 | 3520 | */ |
179d1c56 | 3521 | return false; |
f1174f77 EC |
3522 | } |
3523 | case PTR_TO_MAP_VALUE: | |
1b688a19 EC |
3524 | /* If the new min/max/var_off satisfy the old ones and |
3525 | * everything else matches, we are OK. | |
3526 | * We don't care about the 'id' value, because nothing | |
3527 | * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL) | |
3528 | */ | |
3529 | return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && | |
3530 | range_within(rold, rcur) && | |
3531 | tnum_in(rold->var_off, rcur->var_off); | |
f1174f77 EC |
3532 | case PTR_TO_MAP_VALUE_OR_NULL: |
3533 | /* a PTR_TO_MAP_VALUE could be safe to use as a | |
3534 | * PTR_TO_MAP_VALUE_OR_NULL into the same map. | |
3535 | * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- | |
3536 | * checked, doing so could have affected others with the same | |
3537 | * id, and we can't check for that because we lost the id when | |
3538 | * we converted to a PTR_TO_MAP_VALUE. | |
3539 | */ | |
3540 | if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL) | |
3541 | return false; | |
3542 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) | |
3543 | return false; | |
3544 | /* Check our ids match any regs they're supposed to */ | |
3545 | return check_ids(rold->id, rcur->id, idmap); | |
de8f3a83 | 3546 | case PTR_TO_PACKET_META: |
f1174f77 | 3547 | case PTR_TO_PACKET: |
de8f3a83 | 3548 | if (rcur->type != rold->type) |
f1174f77 EC |
3549 | return false; |
3550 | /* We must have at least as much range as the old ptr | |
3551 | * did, so that any accesses which were safe before are | |
3552 | * still safe. This is true even if old range < old off, | |
3553 | * since someone could have accessed through (ptr - k), or | |
3554 | * even done ptr -= k in a register, to get a safe access. | |
3555 | */ | |
3556 | if (rold->range > rcur->range) | |
3557 | return false; | |
3558 | /* If the offsets don't match, we can't trust our alignment; | |
3559 | * nor can we be sure that we won't fall out of range. | |
3560 | */ | |
3561 | if (rold->off != rcur->off) | |
3562 | return false; | |
3563 | /* id relations must be preserved */ | |
3564 | if (rold->id && !check_ids(rold->id, rcur->id, idmap)) | |
3565 | return false; | |
3566 | /* new val must satisfy old val knowledge */ | |
3567 | return range_within(rold, rcur) && | |
3568 | tnum_in(rold->var_off, rcur->var_off); | |
3569 | case PTR_TO_CTX: | |
3570 | case CONST_PTR_TO_MAP: | |
3571 | case PTR_TO_STACK: | |
3572 | case PTR_TO_PACKET_END: | |
3573 | /* Only valid matches are exact, which memcmp() above | |
3574 | * would have accepted | |
3575 | */ | |
3576 | default: | |
3577 | /* Don't know what's going on, just say it's not safe */ | |
3578 | return false; | |
3579 | } | |
969bf05e | 3580 | |
f1174f77 EC |
3581 | /* Shouldn't get here; if we do, say it's not safe */ |
3582 | WARN_ON_ONCE(1); | |
969bf05e AS |
3583 | return false; |
3584 | } | |
3585 | ||
638f5b90 AS |
3586 | static bool stacksafe(struct bpf_verifier_state *old, |
3587 | struct bpf_verifier_state *cur, | |
3588 | struct idpair *idmap) | |
3589 | { | |
3590 | int i, spi; | |
3591 | ||
3592 | /* if explored stack has more populated slots than current stack | |
3593 | * such stacks are not equivalent | |
3594 | */ | |
3595 | if (old->allocated_stack > cur->allocated_stack) | |
3596 | return false; | |
3597 | ||
3598 | /* walk slots of the explored stack and ignore any additional | |
3599 | * slots in the current stack, since explored(safe) state | |
3600 | * didn't use them | |
3601 | */ | |
3602 | for (i = 0; i < old->allocated_stack; i++) { | |
3603 | spi = i / BPF_REG_SIZE; | |
3604 | ||
3605 | if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID) | |
3606 | continue; | |
3607 | if (old->stack[spi].slot_type[i % BPF_REG_SIZE] != | |
3608 | cur->stack[spi].slot_type[i % BPF_REG_SIZE]) | |
3609 | /* Ex: old explored (safe) state has STACK_SPILL in | |
3610 | * this stack slot, but current has has STACK_MISC -> | |
3611 | * this verifier states are not equivalent, | |
3612 | * return false to continue verification of this path | |
3613 | */ | |
3614 | return false; | |
3615 | if (i % BPF_REG_SIZE) | |
3616 | continue; | |
3617 | if (old->stack[spi].slot_type[0] != STACK_SPILL) | |
3618 | continue; | |
3619 | if (!regsafe(&old->stack[spi].spilled_ptr, | |
3620 | &cur->stack[spi].spilled_ptr, | |
3621 | idmap)) | |
3622 | /* when explored and current stack slot are both storing | |
3623 | * spilled registers, check that stored pointers types | |
3624 | * are the same as well. | |
3625 | * Ex: explored safe path could have stored | |
3626 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8} | |
3627 | * but current path has stored: | |
3628 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16} | |
3629 | * such verifier states are not equivalent. | |
3630 | * return false to continue verification of this path | |
3631 | */ | |
3632 | return false; | |
3633 | } | |
3634 | return true; | |
3635 | } | |
3636 | ||
f1bca824 AS |
3637 | /* compare two verifier states |
3638 | * | |
3639 | * all states stored in state_list are known to be valid, since | |
3640 | * verifier reached 'bpf_exit' instruction through them | |
3641 | * | |
3642 | * this function is called when verifier exploring different branches of | |
3643 | * execution popped from the state stack. If it sees an old state that has | |
3644 | * more strict register state and more strict stack state then this execution | |
3645 | * branch doesn't need to be explored further, since verifier already | |
3646 | * concluded that more strict state leads to valid finish. | |
3647 | * | |
3648 | * Therefore two states are equivalent if register state is more conservative | |
3649 | * and explored stack state is more conservative than the current one. | |
3650 | * Example: | |
3651 | * explored current | |
3652 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
3653 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
3654 | * | |
3655 | * In other words if current stack state (one being explored) has more | |
3656 | * valid slots than old one that already passed validation, it means | |
3657 | * the verifier can stop exploring and conclude that current state is valid too | |
3658 | * | |
3659 | * Similarly with registers. If explored state has register type as invalid | |
3660 | * whereas register type in current state is meaningful, it means that | |
3661 | * the current state will reach 'bpf_exit' instruction safely | |
3662 | */ | |
48461135 JB |
3663 | static bool states_equal(struct bpf_verifier_env *env, |
3664 | struct bpf_verifier_state *old, | |
58e2af8b | 3665 | struct bpf_verifier_state *cur) |
f1bca824 | 3666 | { |
f1174f77 EC |
3667 | struct idpair *idmap; |
3668 | bool ret = false; | |
f1bca824 AS |
3669 | int i; |
3670 | ||
f1174f77 EC |
3671 | idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL); |
3672 | /* If we failed to allocate the idmap, just say it's not safe */ | |
3673 | if (!idmap) | |
1a0dc1ac | 3674 | return false; |
f1174f77 EC |
3675 | |
3676 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1b688a19 | 3677 | if (!regsafe(&old->regs[i], &cur->regs[i], idmap)) |
f1174f77 | 3678 | goto out_free; |
f1bca824 AS |
3679 | } |
3680 | ||
638f5b90 AS |
3681 | if (!stacksafe(old, cur, idmap)) |
3682 | goto out_free; | |
f1174f77 EC |
3683 | ret = true; |
3684 | out_free: | |
3685 | kfree(idmap); | |
3686 | return ret; | |
f1bca824 AS |
3687 | } |
3688 | ||
8e9cd9ce EC |
3689 | /* A write screens off any subsequent reads; but write marks come from the |
3690 | * straight-line code between a state and its parent. When we arrive at a | |
3691 | * jump target (in the first iteration of the propagate_liveness() loop), | |
3692 | * we didn't arrive by the straight-line code, so read marks in state must | |
3693 | * propagate to parent regardless of state's write marks. | |
3694 | */ | |
dc503a8a EC |
3695 | static bool do_propagate_liveness(const struct bpf_verifier_state *state, |
3696 | struct bpf_verifier_state *parent) | |
3697 | { | |
63f45f84 | 3698 | bool writes = parent == state->parent; /* Observe write marks */ |
dc503a8a EC |
3699 | bool touched = false; /* any changes made? */ |
3700 | int i; | |
3701 | ||
3702 | if (!parent) | |
3703 | return touched; | |
3704 | /* Propagate read liveness of registers... */ | |
3705 | BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); | |
3706 | /* We don't need to worry about FP liveness because it's read-only */ | |
3707 | for (i = 0; i < BPF_REG_FP; i++) { | |
3708 | if (parent->regs[i].live & REG_LIVE_READ) | |
3709 | continue; | |
63f45f84 EC |
3710 | if (writes && (state->regs[i].live & REG_LIVE_WRITTEN)) |
3711 | continue; | |
3712 | if (state->regs[i].live & REG_LIVE_READ) { | |
dc503a8a EC |
3713 | parent->regs[i].live |= REG_LIVE_READ; |
3714 | touched = true; | |
3715 | } | |
3716 | } | |
3717 | /* ... and stack slots */ | |
638f5b90 AS |
3718 | for (i = 0; i < state->allocated_stack / BPF_REG_SIZE && |
3719 | i < parent->allocated_stack / BPF_REG_SIZE; i++) { | |
3720 | if (parent->stack[i].slot_type[0] != STACK_SPILL) | |
dc503a8a | 3721 | continue; |
638f5b90 | 3722 | if (state->stack[i].slot_type[0] != STACK_SPILL) |
dc503a8a | 3723 | continue; |
638f5b90 | 3724 | if (parent->stack[i].spilled_ptr.live & REG_LIVE_READ) |
dc503a8a | 3725 | continue; |
638f5b90 AS |
3726 | if (writes && |
3727 | (state->stack[i].spilled_ptr.live & REG_LIVE_WRITTEN)) | |
63f45f84 | 3728 | continue; |
638f5b90 AS |
3729 | if (state->stack[i].spilled_ptr.live & REG_LIVE_READ) { |
3730 | parent->stack[i].spilled_ptr.live |= REG_LIVE_READ; | |
dc503a8a EC |
3731 | touched = true; |
3732 | } | |
3733 | } | |
3734 | return touched; | |
3735 | } | |
3736 | ||
8e9cd9ce EC |
3737 | /* "parent" is "a state from which we reach the current state", but initially |
3738 | * it is not the state->parent (i.e. "the state whose straight-line code leads | |
3739 | * to the current state"), instead it is the state that happened to arrive at | |
3740 | * a (prunable) equivalent of the current state. See comment above | |
3741 | * do_propagate_liveness() for consequences of this. | |
3742 | * This function is just a more efficient way of calling mark_reg_read() or | |
3743 | * mark_stack_slot_read() on each reg in "parent" that is read in "state", | |
3744 | * though it requires that parent != state->parent in the call arguments. | |
3745 | */ | |
dc503a8a EC |
3746 | static void propagate_liveness(const struct bpf_verifier_state *state, |
3747 | struct bpf_verifier_state *parent) | |
3748 | { | |
3749 | while (do_propagate_liveness(state, parent)) { | |
3750 | /* Something changed, so we need to feed those changes onward */ | |
3751 | state = parent; | |
3752 | parent = state->parent; | |
3753 | } | |
3754 | } | |
3755 | ||
58e2af8b | 3756 | static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) |
f1bca824 | 3757 | { |
58e2af8b JK |
3758 | struct bpf_verifier_state_list *new_sl; |
3759 | struct bpf_verifier_state_list *sl; | |
638f5b90 | 3760 | struct bpf_verifier_state *cur = env->cur_state; |
1969db47 | 3761 | int i, err; |
f1bca824 AS |
3762 | |
3763 | sl = env->explored_states[insn_idx]; | |
3764 | if (!sl) | |
3765 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
3766 | * be doing state search here | |
3767 | */ | |
3768 | return 0; | |
3769 | ||
3770 | while (sl != STATE_LIST_MARK) { | |
638f5b90 | 3771 | if (states_equal(env, &sl->state, cur)) { |
f1bca824 | 3772 | /* reached equivalent register/stack state, |
dc503a8a EC |
3773 | * prune the search. |
3774 | * Registers read by the continuation are read by us. | |
8e9cd9ce EC |
3775 | * If we have any write marks in env->cur_state, they |
3776 | * will prevent corresponding reads in the continuation | |
3777 | * from reaching our parent (an explored_state). Our | |
3778 | * own state will get the read marks recorded, but | |
3779 | * they'll be immediately forgotten as we're pruning | |
3780 | * this state and will pop a new one. | |
f1bca824 | 3781 | */ |
638f5b90 | 3782 | propagate_liveness(&sl->state, cur); |
f1bca824 | 3783 | return 1; |
dc503a8a | 3784 | } |
f1bca824 AS |
3785 | sl = sl->next; |
3786 | } | |
3787 | ||
3788 | /* there were no equivalent states, remember current one. | |
3789 | * technically the current state is not proven to be safe yet, | |
3790 | * but it will either reach bpf_exit (which means it's safe) or | |
3791 | * it will be rejected. Since there are no loops, we won't be | |
3792 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
3793 | */ | |
638f5b90 | 3794 | new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL); |
f1bca824 AS |
3795 | if (!new_sl) |
3796 | return -ENOMEM; | |
3797 | ||
3798 | /* add new state to the head of linked list */ | |
1969db47 AS |
3799 | err = copy_verifier_state(&new_sl->state, cur); |
3800 | if (err) { | |
3801 | free_verifier_state(&new_sl->state, false); | |
3802 | kfree(new_sl); | |
3803 | return err; | |
3804 | } | |
f1bca824 AS |
3805 | new_sl->next = env->explored_states[insn_idx]; |
3806 | env->explored_states[insn_idx] = new_sl; | |
dc503a8a | 3807 | /* connect new state to parentage chain */ |
638f5b90 | 3808 | cur->parent = &new_sl->state; |
8e9cd9ce EC |
3809 | /* clear write marks in current state: the writes we did are not writes |
3810 | * our child did, so they don't screen off its reads from us. | |
3811 | * (There are no read marks in current state, because reads always mark | |
3812 | * their parent and current state never has children yet. Only | |
3813 | * explored_states can get read marks.) | |
3814 | */ | |
dc503a8a | 3815 | for (i = 0; i < BPF_REG_FP; i++) |
638f5b90 AS |
3816 | cur->regs[i].live = REG_LIVE_NONE; |
3817 | for (i = 0; i < cur->allocated_stack / BPF_REG_SIZE; i++) | |
3818 | if (cur->stack[i].slot_type[0] == STACK_SPILL) | |
3819 | cur->stack[i].spilled_ptr.live = REG_LIVE_NONE; | |
f1bca824 AS |
3820 | return 0; |
3821 | } | |
3822 | ||
13a27dfc JK |
3823 | static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, |
3824 | int insn_idx, int prev_insn_idx) | |
3825 | { | |
ab3f0063 JK |
3826 | if (env->dev_ops && env->dev_ops->insn_hook) |
3827 | return env->dev_ops->insn_hook(env, insn_idx, prev_insn_idx); | |
13a27dfc | 3828 | |
ab3f0063 | 3829 | return 0; |
13a27dfc JK |
3830 | } |
3831 | ||
58e2af8b | 3832 | static int do_check(struct bpf_verifier_env *env) |
17a52670 | 3833 | { |
638f5b90 | 3834 | struct bpf_verifier_state *state; |
17a52670 | 3835 | struct bpf_insn *insns = env->prog->insnsi; |
638f5b90 | 3836 | struct bpf_reg_state *regs; |
17a52670 AS |
3837 | int insn_cnt = env->prog->len; |
3838 | int insn_idx, prev_insn_idx = 0; | |
3839 | int insn_processed = 0; | |
3840 | bool do_print_state = false; | |
3841 | ||
638f5b90 AS |
3842 | state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL); |
3843 | if (!state) | |
3844 | return -ENOMEM; | |
3845 | env->cur_state = state; | |
3846 | init_reg_state(env, state->regs); | |
dc503a8a | 3847 | state->parent = NULL; |
17a52670 AS |
3848 | insn_idx = 0; |
3849 | for (;;) { | |
3850 | struct bpf_insn *insn; | |
3851 | u8 class; | |
3852 | int err; | |
3853 | ||
3854 | if (insn_idx >= insn_cnt) { | |
61bd5218 | 3855 | verbose(env, "invalid insn idx %d insn_cnt %d\n", |
17a52670 AS |
3856 | insn_idx, insn_cnt); |
3857 | return -EFAULT; | |
3858 | } | |
3859 | ||
3860 | insn = &insns[insn_idx]; | |
3861 | class = BPF_CLASS(insn->code); | |
3862 | ||
07016151 | 3863 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
61bd5218 JK |
3864 | verbose(env, |
3865 | "BPF program is too large. Processed %d insn\n", | |
17a52670 AS |
3866 | insn_processed); |
3867 | return -E2BIG; | |
3868 | } | |
3869 | ||
f1bca824 AS |
3870 | err = is_state_visited(env, insn_idx); |
3871 | if (err < 0) | |
3872 | return err; | |
3873 | if (err == 1) { | |
3874 | /* found equivalent state, can prune the search */ | |
61bd5218 | 3875 | if (env->log.level) { |
f1bca824 | 3876 | if (do_print_state) |
61bd5218 | 3877 | verbose(env, "\nfrom %d to %d: safe\n", |
f1bca824 AS |
3878 | prev_insn_idx, insn_idx); |
3879 | else | |
61bd5218 | 3880 | verbose(env, "%d: safe\n", insn_idx); |
f1bca824 AS |
3881 | } |
3882 | goto process_bpf_exit; | |
3883 | } | |
3884 | ||
3c2ce60b DB |
3885 | if (need_resched()) |
3886 | cond_resched(); | |
3887 | ||
61bd5218 JK |
3888 | if (env->log.level > 1 || (env->log.level && do_print_state)) { |
3889 | if (env->log.level > 1) | |
3890 | verbose(env, "%d:", insn_idx); | |
c5fc9692 | 3891 | else |
61bd5218 | 3892 | verbose(env, "\nfrom %d to %d:", |
c5fc9692 | 3893 | prev_insn_idx, insn_idx); |
638f5b90 | 3894 | print_verifier_state(env, state); |
17a52670 AS |
3895 | do_print_state = false; |
3896 | } | |
3897 | ||
61bd5218 JK |
3898 | if (env->log.level) { |
3899 | verbose(env, "%d: ", insn_idx); | |
f4ac7e0b JK |
3900 | print_bpf_insn(verbose, env, insn, |
3901 | env->allow_ptr_leaks); | |
17a52670 AS |
3902 | } |
3903 | ||
13a27dfc JK |
3904 | err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); |
3905 | if (err) | |
3906 | return err; | |
3907 | ||
638f5b90 | 3908 | regs = cur_regs(env); |
c131187d | 3909 | env->insn_aux_data[insn_idx].seen = true; |
17a52670 | 3910 | if (class == BPF_ALU || class == BPF_ALU64) { |
1be7f75d | 3911 | err = check_alu_op(env, insn); |
17a52670 AS |
3912 | if (err) |
3913 | return err; | |
3914 | ||
3915 | } else if (class == BPF_LDX) { | |
3df126f3 | 3916 | enum bpf_reg_type *prev_src_type, src_reg_type; |
9bac3d6d AS |
3917 | |
3918 | /* check for reserved fields is already done */ | |
3919 | ||
17a52670 | 3920 | /* check src operand */ |
dc503a8a | 3921 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3922 | if (err) |
3923 | return err; | |
3924 | ||
dc503a8a | 3925 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
17a52670 AS |
3926 | if (err) |
3927 | return err; | |
3928 | ||
725f9dcd AS |
3929 | src_reg_type = regs[insn->src_reg].type; |
3930 | ||
17a52670 AS |
3931 | /* check that memory (src_reg + off) is readable, |
3932 | * the state of dst_reg will be updated by this func | |
3933 | */ | |
31fd8581 | 3934 | err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, |
17a52670 AS |
3935 | BPF_SIZE(insn->code), BPF_READ, |
3936 | insn->dst_reg); | |
3937 | if (err) | |
3938 | return err; | |
3939 | ||
3df126f3 JK |
3940 | prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; |
3941 | ||
3942 | if (*prev_src_type == NOT_INIT) { | |
9bac3d6d AS |
3943 | /* saw a valid insn |
3944 | * dst_reg = *(u32 *)(src_reg + off) | |
3df126f3 | 3945 | * save type to validate intersecting paths |
9bac3d6d | 3946 | */ |
3df126f3 | 3947 | *prev_src_type = src_reg_type; |
9bac3d6d | 3948 | |
3df126f3 | 3949 | } else if (src_reg_type != *prev_src_type && |
9bac3d6d | 3950 | (src_reg_type == PTR_TO_CTX || |
3df126f3 | 3951 | *prev_src_type == PTR_TO_CTX)) { |
9bac3d6d AS |
3952 | /* ABuser program is trying to use the same insn |
3953 | * dst_reg = *(u32*) (src_reg + off) | |
3954 | * with different pointer types: | |
3955 | * src_reg == ctx in one branch and | |
3956 | * src_reg == stack|map in some other branch. | |
3957 | * Reject it. | |
3958 | */ | |
61bd5218 | 3959 | verbose(env, "same insn cannot be used with different pointers\n"); |
9bac3d6d AS |
3960 | return -EINVAL; |
3961 | } | |
3962 | ||
17a52670 | 3963 | } else if (class == BPF_STX) { |
3df126f3 | 3964 | enum bpf_reg_type *prev_dst_type, dst_reg_type; |
d691f9e8 | 3965 | |
17a52670 | 3966 | if (BPF_MODE(insn->code) == BPF_XADD) { |
31fd8581 | 3967 | err = check_xadd(env, insn_idx, insn); |
17a52670 AS |
3968 | if (err) |
3969 | return err; | |
3970 | insn_idx++; | |
3971 | continue; | |
3972 | } | |
3973 | ||
17a52670 | 3974 | /* check src1 operand */ |
dc503a8a | 3975 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3976 | if (err) |
3977 | return err; | |
3978 | /* check src2 operand */ | |
dc503a8a | 3979 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3980 | if (err) |
3981 | return err; | |
3982 | ||
d691f9e8 AS |
3983 | dst_reg_type = regs[insn->dst_reg].type; |
3984 | ||
17a52670 | 3985 | /* check that memory (dst_reg + off) is writeable */ |
31fd8581 | 3986 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
3987 | BPF_SIZE(insn->code), BPF_WRITE, |
3988 | insn->src_reg); | |
3989 | if (err) | |
3990 | return err; | |
3991 | ||
3df126f3 JK |
3992 | prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; |
3993 | ||
3994 | if (*prev_dst_type == NOT_INIT) { | |
3995 | *prev_dst_type = dst_reg_type; | |
3996 | } else if (dst_reg_type != *prev_dst_type && | |
d691f9e8 | 3997 | (dst_reg_type == PTR_TO_CTX || |
3df126f3 | 3998 | *prev_dst_type == PTR_TO_CTX)) { |
61bd5218 | 3999 | verbose(env, "same insn cannot be used with different pointers\n"); |
d691f9e8 AS |
4000 | return -EINVAL; |
4001 | } | |
4002 | ||
17a52670 AS |
4003 | } else if (class == BPF_ST) { |
4004 | if (BPF_MODE(insn->code) != BPF_MEM || | |
4005 | insn->src_reg != BPF_REG_0) { | |
61bd5218 | 4006 | verbose(env, "BPF_ST uses reserved fields\n"); |
17a52670 AS |
4007 | return -EINVAL; |
4008 | } | |
4009 | /* check src operand */ | |
dc503a8a | 4010 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
4011 | if (err) |
4012 | return err; | |
4013 | ||
f37a8cb8 DB |
4014 | if (is_ctx_reg(env, insn->dst_reg)) { |
4015 | verbose(env, "BPF_ST stores into R%d context is not allowed\n", | |
4016 | insn->dst_reg); | |
4017 | return -EACCES; | |
4018 | } | |
4019 | ||
17a52670 | 4020 | /* check that memory (dst_reg + off) is writeable */ |
31fd8581 | 4021 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
4022 | BPF_SIZE(insn->code), BPF_WRITE, |
4023 | -1); | |
4024 | if (err) | |
4025 | return err; | |
4026 | ||
4027 | } else if (class == BPF_JMP) { | |
4028 | u8 opcode = BPF_OP(insn->code); | |
4029 | ||
4030 | if (opcode == BPF_CALL) { | |
4031 | if (BPF_SRC(insn->code) != BPF_K || | |
4032 | insn->off != 0 || | |
4033 | insn->src_reg != BPF_REG_0 || | |
4034 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 4035 | verbose(env, "BPF_CALL uses reserved fields\n"); |
17a52670 AS |
4036 | return -EINVAL; |
4037 | } | |
4038 | ||
81ed18ab | 4039 | err = check_call(env, insn->imm, insn_idx); |
17a52670 AS |
4040 | if (err) |
4041 | return err; | |
4042 | ||
4043 | } else if (opcode == BPF_JA) { | |
4044 | if (BPF_SRC(insn->code) != BPF_K || | |
4045 | insn->imm != 0 || | |
4046 | insn->src_reg != BPF_REG_0 || | |
4047 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 4048 | verbose(env, "BPF_JA uses reserved fields\n"); |
17a52670 AS |
4049 | return -EINVAL; |
4050 | } | |
4051 | ||
4052 | insn_idx += insn->off + 1; | |
4053 | continue; | |
4054 | ||
4055 | } else if (opcode == BPF_EXIT) { | |
4056 | if (BPF_SRC(insn->code) != BPF_K || | |
4057 | insn->imm != 0 || | |
4058 | insn->src_reg != BPF_REG_0 || | |
4059 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 4060 | verbose(env, "BPF_EXIT uses reserved fields\n"); |
17a52670 AS |
4061 | return -EINVAL; |
4062 | } | |
4063 | ||
4064 | /* eBPF calling convetion is such that R0 is used | |
4065 | * to return the value from eBPF program. | |
4066 | * Make sure that it's readable at this time | |
4067 | * of bpf_exit, which means that program wrote | |
4068 | * something into it earlier | |
4069 | */ | |
dc503a8a | 4070 | err = check_reg_arg(env, BPF_REG_0, SRC_OP); |
17a52670 AS |
4071 | if (err) |
4072 | return err; | |
4073 | ||
1be7f75d | 4074 | if (is_pointer_value(env, BPF_REG_0)) { |
61bd5218 | 4075 | verbose(env, "R0 leaks addr as return value\n"); |
1be7f75d AS |
4076 | return -EACCES; |
4077 | } | |
4078 | ||
390ee7e2 AS |
4079 | err = check_return_code(env); |
4080 | if (err) | |
4081 | return err; | |
f1bca824 | 4082 | process_bpf_exit: |
638f5b90 AS |
4083 | err = pop_stack(env, &prev_insn_idx, &insn_idx); |
4084 | if (err < 0) { | |
4085 | if (err != -ENOENT) | |
4086 | return err; | |
17a52670 AS |
4087 | break; |
4088 | } else { | |
4089 | do_print_state = true; | |
4090 | continue; | |
4091 | } | |
4092 | } else { | |
4093 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
4094 | if (err) | |
4095 | return err; | |
4096 | } | |
4097 | } else if (class == BPF_LD) { | |
4098 | u8 mode = BPF_MODE(insn->code); | |
4099 | ||
4100 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
4101 | err = check_ld_abs(env, insn); |
4102 | if (err) | |
4103 | return err; | |
4104 | ||
17a52670 AS |
4105 | } else if (mode == BPF_IMM) { |
4106 | err = check_ld_imm(env, insn); | |
4107 | if (err) | |
4108 | return err; | |
4109 | ||
4110 | insn_idx++; | |
c131187d | 4111 | env->insn_aux_data[insn_idx].seen = true; |
17a52670 | 4112 | } else { |
61bd5218 | 4113 | verbose(env, "invalid BPF_LD mode\n"); |
17a52670 AS |
4114 | return -EINVAL; |
4115 | } | |
4116 | } else { | |
61bd5218 | 4117 | verbose(env, "unknown insn class %d\n", class); |
17a52670 AS |
4118 | return -EINVAL; |
4119 | } | |
4120 | ||
4121 | insn_idx++; | |
4122 | } | |
4123 | ||
61bd5218 JK |
4124 | verbose(env, "processed %d insns, stack depth %d\n", insn_processed, |
4125 | env->prog->aux->stack_depth); | |
17a52670 AS |
4126 | return 0; |
4127 | } | |
4128 | ||
56f668df MKL |
4129 | static int check_map_prealloc(struct bpf_map *map) |
4130 | { | |
4131 | return (map->map_type != BPF_MAP_TYPE_HASH && | |
bcc6b1b7 MKL |
4132 | map->map_type != BPF_MAP_TYPE_PERCPU_HASH && |
4133 | map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || | |
56f668df MKL |
4134 | !(map->map_flags & BPF_F_NO_PREALLOC); |
4135 | } | |
4136 | ||
61bd5218 JK |
4137 | static int check_map_prog_compatibility(struct bpf_verifier_env *env, |
4138 | struct bpf_map *map, | |
fdc15d38 AS |
4139 | struct bpf_prog *prog) |
4140 | ||
4141 | { | |
56f668df MKL |
4142 | /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use |
4143 | * preallocated hash maps, since doing memory allocation | |
4144 | * in overflow_handler can crash depending on where nmi got | |
4145 | * triggered. | |
4146 | */ | |
4147 | if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { | |
4148 | if (!check_map_prealloc(map)) { | |
61bd5218 | 4149 | verbose(env, "perf_event programs can only use preallocated hash map\n"); |
56f668df MKL |
4150 | return -EINVAL; |
4151 | } | |
4152 | if (map->inner_map_meta && | |
4153 | !check_map_prealloc(map->inner_map_meta)) { | |
61bd5218 | 4154 | verbose(env, "perf_event programs can only use preallocated inner hash map\n"); |
56f668df MKL |
4155 | return -EINVAL; |
4156 | } | |
fdc15d38 AS |
4157 | } |
4158 | return 0; | |
4159 | } | |
4160 | ||
0246e64d AS |
4161 | /* look for pseudo eBPF instructions that access map FDs and |
4162 | * replace them with actual map pointers | |
4163 | */ | |
58e2af8b | 4164 | static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) |
0246e64d AS |
4165 | { |
4166 | struct bpf_insn *insn = env->prog->insnsi; | |
4167 | int insn_cnt = env->prog->len; | |
fdc15d38 | 4168 | int i, j, err; |
0246e64d | 4169 | |
f1f7714e | 4170 | err = bpf_prog_calc_tag(env->prog); |
aafe6ae9 DB |
4171 | if (err) |
4172 | return err; | |
4173 | ||
0246e64d | 4174 | for (i = 0; i < insn_cnt; i++, insn++) { |
9bac3d6d | 4175 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 4176 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
61bd5218 | 4177 | verbose(env, "BPF_LDX uses reserved fields\n"); |
9bac3d6d AS |
4178 | return -EINVAL; |
4179 | } | |
4180 | ||
d691f9e8 AS |
4181 | if (BPF_CLASS(insn->code) == BPF_STX && |
4182 | ((BPF_MODE(insn->code) != BPF_MEM && | |
4183 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
61bd5218 | 4184 | verbose(env, "BPF_STX uses reserved fields\n"); |
d691f9e8 AS |
4185 | return -EINVAL; |
4186 | } | |
4187 | ||
0246e64d AS |
4188 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
4189 | struct bpf_map *map; | |
4190 | struct fd f; | |
4191 | ||
4192 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
4193 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
4194 | insn[1].off != 0) { | |
61bd5218 | 4195 | verbose(env, "invalid bpf_ld_imm64 insn\n"); |
0246e64d AS |
4196 | return -EINVAL; |
4197 | } | |
4198 | ||
4199 | if (insn->src_reg == 0) | |
4200 | /* valid generic load 64-bit imm */ | |
4201 | goto next_insn; | |
4202 | ||
4203 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
61bd5218 JK |
4204 | verbose(env, |
4205 | "unrecognized bpf_ld_imm64 insn\n"); | |
0246e64d AS |
4206 | return -EINVAL; |
4207 | } | |
4208 | ||
4209 | f = fdget(insn->imm); | |
c2101297 | 4210 | map = __bpf_map_get(f); |
0246e64d | 4211 | if (IS_ERR(map)) { |
61bd5218 | 4212 | verbose(env, "fd %d is not pointing to valid bpf_map\n", |
0246e64d | 4213 | insn->imm); |
0246e64d AS |
4214 | return PTR_ERR(map); |
4215 | } | |
4216 | ||
61bd5218 | 4217 | err = check_map_prog_compatibility(env, map, env->prog); |
fdc15d38 AS |
4218 | if (err) { |
4219 | fdput(f); | |
4220 | return err; | |
4221 | } | |
4222 | ||
0246e64d AS |
4223 | /* store map pointer inside BPF_LD_IMM64 instruction */ |
4224 | insn[0].imm = (u32) (unsigned long) map; | |
4225 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
4226 | ||
4227 | /* check whether we recorded this map already */ | |
4228 | for (j = 0; j < env->used_map_cnt; j++) | |
4229 | if (env->used_maps[j] == map) { | |
4230 | fdput(f); | |
4231 | goto next_insn; | |
4232 | } | |
4233 | ||
4234 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
4235 | fdput(f); | |
4236 | return -E2BIG; | |
4237 | } | |
4238 | ||
0246e64d AS |
4239 | /* hold the map. If the program is rejected by verifier, |
4240 | * the map will be released by release_maps() or it | |
4241 | * will be used by the valid program until it's unloaded | |
4242 | * and all maps are released in free_bpf_prog_info() | |
4243 | */ | |
92117d84 AS |
4244 | map = bpf_map_inc(map, false); |
4245 | if (IS_ERR(map)) { | |
4246 | fdput(f); | |
4247 | return PTR_ERR(map); | |
4248 | } | |
4249 | env->used_maps[env->used_map_cnt++] = map; | |
4250 | ||
0246e64d AS |
4251 | fdput(f); |
4252 | next_insn: | |
4253 | insn++; | |
4254 | i++; | |
4255 | } | |
4256 | } | |
4257 | ||
4258 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
4259 | * 'struct bpf_map *' into a register instead of user map_fd. | |
4260 | * These pointers will be used later by verifier to validate map access. | |
4261 | */ | |
4262 | return 0; | |
4263 | } | |
4264 | ||
4265 | /* drop refcnt of maps used by the rejected program */ | |
58e2af8b | 4266 | static void release_maps(struct bpf_verifier_env *env) |
0246e64d AS |
4267 | { |
4268 | int i; | |
4269 | ||
4270 | for (i = 0; i < env->used_map_cnt; i++) | |
4271 | bpf_map_put(env->used_maps[i]); | |
4272 | } | |
4273 | ||
4274 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
58e2af8b | 4275 | static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) |
0246e64d AS |
4276 | { |
4277 | struct bpf_insn *insn = env->prog->insnsi; | |
4278 | int insn_cnt = env->prog->len; | |
4279 | int i; | |
4280 | ||
4281 | for (i = 0; i < insn_cnt; i++, insn++) | |
4282 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
4283 | insn->src_reg = 0; | |
4284 | } | |
4285 | ||
8041902d AS |
4286 | /* single env->prog->insni[off] instruction was replaced with the range |
4287 | * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying | |
4288 | * [0, off) and [off, end) to new locations, so the patched range stays zero | |
4289 | */ | |
4290 | static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, | |
4291 | u32 off, u32 cnt) | |
4292 | { | |
4293 | struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; | |
c131187d | 4294 | int i; |
8041902d AS |
4295 | |
4296 | if (cnt == 1) | |
4297 | return 0; | |
4298 | new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); | |
4299 | if (!new_data) | |
4300 | return -ENOMEM; | |
4301 | memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); | |
4302 | memcpy(new_data + off + cnt - 1, old_data + off, | |
4303 | sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); | |
c131187d AS |
4304 | for (i = off; i < off + cnt - 1; i++) |
4305 | new_data[i].seen = true; | |
8041902d AS |
4306 | env->insn_aux_data = new_data; |
4307 | vfree(old_data); | |
4308 | return 0; | |
4309 | } | |
4310 | ||
4311 | static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, | |
4312 | const struct bpf_insn *patch, u32 len) | |
4313 | { | |
4314 | struct bpf_prog *new_prog; | |
4315 | ||
4316 | new_prog = bpf_patch_insn_single(env->prog, off, patch, len); | |
4317 | if (!new_prog) | |
4318 | return NULL; | |
4319 | if (adjust_insn_aux_data(env, new_prog->len, off, len)) | |
4320 | return NULL; | |
4321 | return new_prog; | |
4322 | } | |
4323 | ||
c131187d AS |
4324 | /* The verifier does more data flow analysis than llvm and will not explore |
4325 | * branches that are dead at run time. Malicious programs can have dead code | |
4326 | * too. Therefore replace all dead at-run-time code with nops. | |
4327 | */ | |
4328 | static void sanitize_dead_code(struct bpf_verifier_env *env) | |
4329 | { | |
4330 | struct bpf_insn_aux_data *aux_data = env->insn_aux_data; | |
4331 | struct bpf_insn nop = BPF_MOV64_REG(BPF_REG_0, BPF_REG_0); | |
4332 | struct bpf_insn *insn = env->prog->insnsi; | |
4333 | const int insn_cnt = env->prog->len; | |
4334 | int i; | |
4335 | ||
4336 | for (i = 0; i < insn_cnt; i++) { | |
4337 | if (aux_data[i].seen) | |
4338 | continue; | |
4339 | memcpy(insn + i, &nop, sizeof(nop)); | |
4340 | } | |
4341 | } | |
4342 | ||
9bac3d6d AS |
4343 | /* convert load instructions that access fields of 'struct __sk_buff' |
4344 | * into sequence of instructions that access fields of 'struct sk_buff' | |
4345 | */ | |
58e2af8b | 4346 | static int convert_ctx_accesses(struct bpf_verifier_env *env) |
9bac3d6d | 4347 | { |
00176a34 | 4348 | const struct bpf_verifier_ops *ops = env->ops; |
f96da094 | 4349 | int i, cnt, size, ctx_field_size, delta = 0; |
3df126f3 | 4350 | const int insn_cnt = env->prog->len; |
36bbef52 | 4351 | struct bpf_insn insn_buf[16], *insn; |
9bac3d6d | 4352 | struct bpf_prog *new_prog; |
d691f9e8 | 4353 | enum bpf_access_type type; |
f96da094 DB |
4354 | bool is_narrower_load; |
4355 | u32 target_size; | |
9bac3d6d | 4356 | |
36bbef52 DB |
4357 | if (ops->gen_prologue) { |
4358 | cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, | |
4359 | env->prog); | |
4360 | if (cnt >= ARRAY_SIZE(insn_buf)) { | |
61bd5218 | 4361 | verbose(env, "bpf verifier is misconfigured\n"); |
36bbef52 DB |
4362 | return -EINVAL; |
4363 | } else if (cnt) { | |
8041902d | 4364 | new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); |
36bbef52 DB |
4365 | if (!new_prog) |
4366 | return -ENOMEM; | |
8041902d | 4367 | |
36bbef52 | 4368 | env->prog = new_prog; |
3df126f3 | 4369 | delta += cnt - 1; |
36bbef52 DB |
4370 | } |
4371 | } | |
4372 | ||
4373 | if (!ops->convert_ctx_access) | |
9bac3d6d AS |
4374 | return 0; |
4375 | ||
3df126f3 | 4376 | insn = env->prog->insnsi + delta; |
36bbef52 | 4377 | |
9bac3d6d | 4378 | for (i = 0; i < insn_cnt; i++, insn++) { |
62c7989b DB |
4379 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || |
4380 | insn->code == (BPF_LDX | BPF_MEM | BPF_H) || | |
4381 | insn->code == (BPF_LDX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4382 | insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) |
d691f9e8 | 4383 | type = BPF_READ; |
62c7989b DB |
4384 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || |
4385 | insn->code == (BPF_STX | BPF_MEM | BPF_H) || | |
4386 | insn->code == (BPF_STX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4387 | insn->code == (BPF_STX | BPF_MEM | BPF_DW)) |
d691f9e8 AS |
4388 | type = BPF_WRITE; |
4389 | else | |
9bac3d6d AS |
4390 | continue; |
4391 | ||
8041902d | 4392 | if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) |
9bac3d6d | 4393 | continue; |
9bac3d6d | 4394 | |
31fd8581 | 4395 | ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; |
f96da094 | 4396 | size = BPF_LDST_BYTES(insn); |
31fd8581 YS |
4397 | |
4398 | /* If the read access is a narrower load of the field, | |
4399 | * convert to a 4/8-byte load, to minimum program type specific | |
4400 | * convert_ctx_access changes. If conversion is successful, | |
4401 | * we will apply proper mask to the result. | |
4402 | */ | |
f96da094 | 4403 | is_narrower_load = size < ctx_field_size; |
31fd8581 | 4404 | if (is_narrower_load) { |
f96da094 DB |
4405 | u32 off = insn->off; |
4406 | u8 size_code; | |
4407 | ||
4408 | if (type == BPF_WRITE) { | |
61bd5218 | 4409 | verbose(env, "bpf verifier narrow ctx access misconfigured\n"); |
f96da094 DB |
4410 | return -EINVAL; |
4411 | } | |
31fd8581 | 4412 | |
f96da094 | 4413 | size_code = BPF_H; |
31fd8581 YS |
4414 | if (ctx_field_size == 4) |
4415 | size_code = BPF_W; | |
4416 | else if (ctx_field_size == 8) | |
4417 | size_code = BPF_DW; | |
f96da094 | 4418 | |
31fd8581 YS |
4419 | insn->off = off & ~(ctx_field_size - 1); |
4420 | insn->code = BPF_LDX | BPF_MEM | size_code; | |
4421 | } | |
f96da094 DB |
4422 | |
4423 | target_size = 0; | |
4424 | cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog, | |
4425 | &target_size); | |
4426 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || | |
4427 | (ctx_field_size && !target_size)) { | |
61bd5218 | 4428 | verbose(env, "bpf verifier is misconfigured\n"); |
9bac3d6d AS |
4429 | return -EINVAL; |
4430 | } | |
f96da094 DB |
4431 | |
4432 | if (is_narrower_load && size < target_size) { | |
31fd8581 YS |
4433 | if (ctx_field_size <= 4) |
4434 | insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4435 | (1 << size * 8) - 1); |
31fd8581 YS |
4436 | else |
4437 | insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4438 | (1 << size * 8) - 1); |
31fd8581 | 4439 | } |
9bac3d6d | 4440 | |
8041902d | 4441 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); |
9bac3d6d AS |
4442 | if (!new_prog) |
4443 | return -ENOMEM; | |
4444 | ||
3df126f3 | 4445 | delta += cnt - 1; |
9bac3d6d AS |
4446 | |
4447 | /* keep walking new program and skip insns we just inserted */ | |
4448 | env->prog = new_prog; | |
3df126f3 | 4449 | insn = new_prog->insnsi + i + delta; |
9bac3d6d AS |
4450 | } |
4451 | ||
4452 | return 0; | |
4453 | } | |
4454 | ||
79741b3b | 4455 | /* fixup insn->imm field of bpf_call instructions |
81ed18ab | 4456 | * and inline eligible helpers as explicit sequence of BPF instructions |
e245c5c6 AS |
4457 | * |
4458 | * this function is called after eBPF program passed verification | |
4459 | */ | |
79741b3b | 4460 | static int fixup_bpf_calls(struct bpf_verifier_env *env) |
e245c5c6 | 4461 | { |
79741b3b AS |
4462 | struct bpf_prog *prog = env->prog; |
4463 | struct bpf_insn *insn = prog->insnsi; | |
e245c5c6 | 4464 | const struct bpf_func_proto *fn; |
79741b3b | 4465 | const int insn_cnt = prog->len; |
81ed18ab AS |
4466 | struct bpf_insn insn_buf[16]; |
4467 | struct bpf_prog *new_prog; | |
4468 | struct bpf_map *map_ptr; | |
4469 | int i, cnt, delta = 0; | |
e245c5c6 | 4470 | |
79741b3b | 4471 | for (i = 0; i < insn_cnt; i++, insn++) { |
68fda450 AS |
4472 | if (insn->code == (BPF_ALU | BPF_MOD | BPF_X) || |
4473 | insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { | |
4474 | /* due to JIT bugs clear upper 32-bits of src register | |
4475 | * before div/mod operation | |
4476 | */ | |
4477 | insn_buf[0] = BPF_MOV32_REG(insn->src_reg, insn->src_reg); | |
4478 | insn_buf[1] = *insn; | |
4479 | cnt = 2; | |
4480 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); | |
4481 | if (!new_prog) | |
4482 | return -ENOMEM; | |
4483 | ||
4484 | delta += cnt - 1; | |
4485 | env->prog = prog = new_prog; | |
4486 | insn = new_prog->insnsi + i + delta; | |
4487 | continue; | |
4488 | } | |
4489 | ||
79741b3b AS |
4490 | if (insn->code != (BPF_JMP | BPF_CALL)) |
4491 | continue; | |
e245c5c6 | 4492 | |
79741b3b AS |
4493 | if (insn->imm == BPF_FUNC_get_route_realm) |
4494 | prog->dst_needed = 1; | |
4495 | if (insn->imm == BPF_FUNC_get_prandom_u32) | |
4496 | bpf_user_rnd_init_once(); | |
79741b3b | 4497 | if (insn->imm == BPF_FUNC_tail_call) { |
7b9f6da1 DM |
4498 | /* If we tail call into other programs, we |
4499 | * cannot make any assumptions since they can | |
4500 | * be replaced dynamically during runtime in | |
4501 | * the program array. | |
4502 | */ | |
4503 | prog->cb_access = 1; | |
80a58d02 | 4504 | env->prog->aux->stack_depth = MAX_BPF_STACK; |
7b9f6da1 | 4505 | |
79741b3b AS |
4506 | /* mark bpf_tail_call as different opcode to avoid |
4507 | * conditional branch in the interpeter for every normal | |
4508 | * call and to prevent accidental JITing by JIT compiler | |
4509 | * that doesn't support bpf_tail_call yet | |
e245c5c6 | 4510 | */ |
79741b3b | 4511 | insn->imm = 0; |
71189fa9 | 4512 | insn->code = BPF_JMP | BPF_TAIL_CALL; |
b2157399 AS |
4513 | |
4514 | /* instead of changing every JIT dealing with tail_call | |
4515 | * emit two extra insns: | |
4516 | * if (index >= max_entries) goto out; | |
4517 | * index &= array->index_mask; | |
4518 | * to avoid out-of-bounds cpu speculation | |
4519 | */ | |
4520 | map_ptr = env->insn_aux_data[i + delta].map_ptr; | |
4521 | if (map_ptr == BPF_MAP_PTR_POISON) { | |
40950343 | 4522 | verbose(env, "tail_call abusing map_ptr\n"); |
b2157399 AS |
4523 | return -EINVAL; |
4524 | } | |
4525 | if (!map_ptr->unpriv_array) | |
4526 | continue; | |
4527 | insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3, | |
4528 | map_ptr->max_entries, 2); | |
4529 | insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3, | |
4530 | container_of(map_ptr, | |
4531 | struct bpf_array, | |
4532 | map)->index_mask); | |
4533 | insn_buf[2] = *insn; | |
4534 | cnt = 3; | |
4535 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); | |
4536 | if (!new_prog) | |
4537 | return -ENOMEM; | |
4538 | ||
4539 | delta += cnt - 1; | |
4540 | env->prog = prog = new_prog; | |
4541 | insn = new_prog->insnsi + i + delta; | |
79741b3b AS |
4542 | continue; |
4543 | } | |
e245c5c6 | 4544 | |
89c63074 DB |
4545 | /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup |
4546 | * handlers are currently limited to 64 bit only. | |
4547 | */ | |
4548 | if (ebpf_jit_enabled() && BITS_PER_LONG == 64 && | |
4549 | insn->imm == BPF_FUNC_map_lookup_elem) { | |
81ed18ab | 4550 | map_ptr = env->insn_aux_data[i + delta].map_ptr; |
fad73a1a MKL |
4551 | if (map_ptr == BPF_MAP_PTR_POISON || |
4552 | !map_ptr->ops->map_gen_lookup) | |
81ed18ab AS |
4553 | goto patch_call_imm; |
4554 | ||
4555 | cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); | |
4556 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { | |
61bd5218 | 4557 | verbose(env, "bpf verifier is misconfigured\n"); |
81ed18ab AS |
4558 | return -EINVAL; |
4559 | } | |
4560 | ||
4561 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, | |
4562 | cnt); | |
4563 | if (!new_prog) | |
4564 | return -ENOMEM; | |
4565 | ||
4566 | delta += cnt - 1; | |
4567 | ||
4568 | /* keep walking new program and skip insns we just inserted */ | |
4569 | env->prog = prog = new_prog; | |
4570 | insn = new_prog->insnsi + i + delta; | |
4571 | continue; | |
4572 | } | |
4573 | ||
109980b8 | 4574 | if (insn->imm == BPF_FUNC_redirect_map) { |
7c300131 DB |
4575 | /* Note, we cannot use prog directly as imm as subsequent |
4576 | * rewrites would still change the prog pointer. The only | |
4577 | * stable address we can use is aux, which also works with | |
4578 | * prog clones during blinding. | |
4579 | */ | |
4580 | u64 addr = (unsigned long)prog->aux; | |
109980b8 DB |
4581 | struct bpf_insn r4_ld[] = { |
4582 | BPF_LD_IMM64(BPF_REG_4, addr), | |
4583 | *insn, | |
4584 | }; | |
4585 | cnt = ARRAY_SIZE(r4_ld); | |
4586 | ||
4587 | new_prog = bpf_patch_insn_data(env, i + delta, r4_ld, cnt); | |
4588 | if (!new_prog) | |
4589 | return -ENOMEM; | |
4590 | ||
4591 | delta += cnt - 1; | |
4592 | env->prog = prog = new_prog; | |
4593 | insn = new_prog->insnsi + i + delta; | |
4594 | } | |
81ed18ab | 4595 | patch_call_imm: |
00176a34 | 4596 | fn = env->ops->get_func_proto(insn->imm); |
79741b3b AS |
4597 | /* all functions that have prototype and verifier allowed |
4598 | * programs to call them, must be real in-kernel functions | |
4599 | */ | |
4600 | if (!fn->func) { | |
61bd5218 JK |
4601 | verbose(env, |
4602 | "kernel subsystem misconfigured func %s#%d\n", | |
79741b3b AS |
4603 | func_id_name(insn->imm), insn->imm); |
4604 | return -EFAULT; | |
e245c5c6 | 4605 | } |
79741b3b | 4606 | insn->imm = fn->func - __bpf_call_base; |
e245c5c6 | 4607 | } |
e245c5c6 | 4608 | |
79741b3b AS |
4609 | return 0; |
4610 | } | |
e245c5c6 | 4611 | |
58e2af8b | 4612 | static void free_states(struct bpf_verifier_env *env) |
f1bca824 | 4613 | { |
58e2af8b | 4614 | struct bpf_verifier_state_list *sl, *sln; |
f1bca824 AS |
4615 | int i; |
4616 | ||
4617 | if (!env->explored_states) | |
4618 | return; | |
4619 | ||
4620 | for (i = 0; i < env->prog->len; i++) { | |
4621 | sl = env->explored_states[i]; | |
4622 | ||
4623 | if (sl) | |
4624 | while (sl != STATE_LIST_MARK) { | |
4625 | sln = sl->next; | |
1969db47 | 4626 | free_verifier_state(&sl->state, false); |
f1bca824 AS |
4627 | kfree(sl); |
4628 | sl = sln; | |
4629 | } | |
4630 | } | |
4631 | ||
4632 | kfree(env->explored_states); | |
4633 | } | |
4634 | ||
9bac3d6d | 4635 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 4636 | { |
58e2af8b | 4637 | struct bpf_verifier_env *env; |
61bd5218 | 4638 | struct bpf_verifer_log *log; |
51580e79 AS |
4639 | int ret = -EINVAL; |
4640 | ||
eba0c929 AB |
4641 | /* no program is valid */ |
4642 | if (ARRAY_SIZE(bpf_verifier_ops) == 0) | |
4643 | return -EINVAL; | |
4644 | ||
58e2af8b | 4645 | /* 'struct bpf_verifier_env' can be global, but since it's not small, |
cbd35700 AS |
4646 | * allocate/free it every time bpf_check() is called |
4647 | */ | |
58e2af8b | 4648 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
cbd35700 AS |
4649 | if (!env) |
4650 | return -ENOMEM; | |
61bd5218 | 4651 | log = &env->log; |
cbd35700 | 4652 | |
3df126f3 JK |
4653 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * |
4654 | (*prog)->len); | |
4655 | ret = -ENOMEM; | |
4656 | if (!env->insn_aux_data) | |
4657 | goto err_free_env; | |
9bac3d6d | 4658 | env->prog = *prog; |
00176a34 | 4659 | env->ops = bpf_verifier_ops[env->prog->type]; |
0246e64d | 4660 | |
cbd35700 AS |
4661 | /* grab the mutex to protect few globals used by verifier */ |
4662 | mutex_lock(&bpf_verifier_lock); | |
4663 | ||
4664 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
4665 | /* user requested verbose verifier output | |
4666 | * and supplied buffer to store the verification trace | |
4667 | */ | |
e7bf8249 JK |
4668 | log->level = attr->log_level; |
4669 | log->ubuf = (char __user *) (unsigned long) attr->log_buf; | |
4670 | log->len_total = attr->log_size; | |
cbd35700 AS |
4671 | |
4672 | ret = -EINVAL; | |
e7bf8249 JK |
4673 | /* log attributes have to be sane */ |
4674 | if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 || | |
4675 | !log->level || !log->ubuf) | |
3df126f3 | 4676 | goto err_unlock; |
cbd35700 | 4677 | } |
1ad2f583 DB |
4678 | |
4679 | env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); | |
4680 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
e07b98d9 | 4681 | env->strict_alignment = true; |
cbd35700 | 4682 | |
ab3f0063 JK |
4683 | if (env->prog->aux->offload) { |
4684 | ret = bpf_prog_offload_verifier_prep(env); | |
4685 | if (ret) | |
4686 | goto err_unlock; | |
4687 | } | |
4688 | ||
0246e64d AS |
4689 | ret = replace_map_fd_with_map_ptr(env); |
4690 | if (ret < 0) | |
4691 | goto skip_full_check; | |
4692 | ||
9bac3d6d | 4693 | env->explored_states = kcalloc(env->prog->len, |
58e2af8b | 4694 | sizeof(struct bpf_verifier_state_list *), |
f1bca824 AS |
4695 | GFP_USER); |
4696 | ret = -ENOMEM; | |
4697 | if (!env->explored_states) | |
4698 | goto skip_full_check; | |
4699 | ||
475fb78f AS |
4700 | ret = check_cfg(env); |
4701 | if (ret < 0) | |
4702 | goto skip_full_check; | |
4703 | ||
1be7f75d AS |
4704 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
4705 | ||
17a52670 | 4706 | ret = do_check(env); |
8c01c4f8 CG |
4707 | if (env->cur_state) { |
4708 | free_verifier_state(env->cur_state, true); | |
4709 | env->cur_state = NULL; | |
4710 | } | |
cbd35700 | 4711 | |
0246e64d | 4712 | skip_full_check: |
638f5b90 | 4713 | while (!pop_stack(env, NULL, NULL)); |
f1bca824 | 4714 | free_states(env); |
0246e64d | 4715 | |
c131187d AS |
4716 | if (ret == 0) |
4717 | sanitize_dead_code(env); | |
4718 | ||
9bac3d6d AS |
4719 | if (ret == 0) |
4720 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
4721 | ret = convert_ctx_accesses(env); | |
4722 | ||
e245c5c6 | 4723 | if (ret == 0) |
79741b3b | 4724 | ret = fixup_bpf_calls(env); |
e245c5c6 | 4725 | |
a2a7d570 | 4726 | if (log->level && bpf_verifier_log_full(log)) |
cbd35700 | 4727 | ret = -ENOSPC; |
a2a7d570 | 4728 | if (log->level && !log->ubuf) { |
cbd35700 | 4729 | ret = -EFAULT; |
a2a7d570 | 4730 | goto err_release_maps; |
cbd35700 AS |
4731 | } |
4732 | ||
0246e64d AS |
4733 | if (ret == 0 && env->used_map_cnt) { |
4734 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
4735 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
4736 | sizeof(env->used_maps[0]), | |
4737 | GFP_KERNEL); | |
0246e64d | 4738 | |
9bac3d6d | 4739 | if (!env->prog->aux->used_maps) { |
0246e64d | 4740 | ret = -ENOMEM; |
a2a7d570 | 4741 | goto err_release_maps; |
0246e64d AS |
4742 | } |
4743 | ||
9bac3d6d | 4744 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 4745 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 4746 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
4747 | |
4748 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
4749 | * bpf_ld_imm64 instructions | |
4750 | */ | |
4751 | convert_pseudo_ld_imm64(env); | |
4752 | } | |
cbd35700 | 4753 | |
a2a7d570 | 4754 | err_release_maps: |
9bac3d6d | 4755 | if (!env->prog->aux->used_maps) |
0246e64d AS |
4756 | /* if we didn't copy map pointers into bpf_prog_info, release |
4757 | * them now. Otherwise free_bpf_prog_info() will release them. | |
4758 | */ | |
4759 | release_maps(env); | |
9bac3d6d | 4760 | *prog = env->prog; |
3df126f3 | 4761 | err_unlock: |
cbd35700 | 4762 | mutex_unlock(&bpf_verifier_lock); |
3df126f3 JK |
4763 | vfree(env->insn_aux_data); |
4764 | err_free_env: | |
4765 | kfree(env); | |
51580e79 AS |
4766 | return ret; |
4767 | } |