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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 AS |
23 | |
24 | /* bpf_check() is a static code analyzer that walks eBPF program | |
25 | * instruction by instruction and updates register/stack state. | |
26 | * All paths of conditional branches are analyzed until 'bpf_exit' insn. | |
27 | * | |
28 | * The first pass is depth-first-search to check that the program is a DAG. | |
29 | * It rejects the following programs: | |
30 | * - larger than BPF_MAXINSNS insns | |
31 | * - if loop is present (detected via back-edge) | |
32 | * - unreachable insns exist (shouldn't be a forest. program = one function) | |
33 | * - out of bounds or malformed jumps | |
34 | * The second pass is all possible path descent from the 1st insn. | |
35 | * Since it's analyzing all pathes through the program, the length of the | |
36 | * analysis is limited to 32k insn, which may be hit even if total number of | |
37 | * insn is less then 4K, but there are too many branches that change stack/regs. | |
38 | * Number of 'branches to be analyzed' is limited to 1k | |
39 | * | |
40 | * On entry to each instruction, each register has a type, and the instruction | |
41 | * changes the types of the registers depending on instruction semantics. | |
42 | * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is | |
43 | * copied to R1. | |
44 | * | |
45 | * All registers are 64-bit. | |
46 | * R0 - return register | |
47 | * R1-R5 argument passing registers | |
48 | * R6-R9 callee saved registers | |
49 | * R10 - frame pointer read-only | |
50 | * | |
51 | * At the start of BPF program the register R1 contains a pointer to bpf_context | |
52 | * and has type PTR_TO_CTX. | |
53 | * | |
54 | * Verifier tracks arithmetic operations on pointers in case: | |
55 | * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), | |
56 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), | |
57 | * 1st insn copies R10 (which has FRAME_PTR) type into R1 | |
58 | * and 2nd arithmetic instruction is pattern matched to recognize | |
59 | * that it wants to construct a pointer to some element within stack. | |
60 | * So after 2nd insn, the register R1 has type PTR_TO_STACK | |
61 | * (and -20 constant is saved for further stack bounds checking). | |
62 | * Meaning that this reg is a pointer to stack plus known immediate constant. | |
63 | * | |
64 | * Most of the time the registers have UNKNOWN_VALUE type, which | |
65 | * means the register has some value, but it's not a valid pointer. | |
66 | * (like pointer plus pointer becomes UNKNOWN_VALUE type) | |
67 | * | |
68 | * When verifier sees load or store instructions the type of base register | |
69 | * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer | |
70 | * types recognized by check_mem_access() function. | |
71 | * | |
72 | * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' | |
73 | * and the range of [ptr, ptr + map's value_size) is accessible. | |
74 | * | |
75 | * registers used to pass values to function calls are checked against | |
76 | * function argument constraints. | |
77 | * | |
78 | * ARG_PTR_TO_MAP_KEY is one of such argument constraints. | |
79 | * It means that the register type passed to this function must be | |
80 | * PTR_TO_STACK and it will be used inside the function as | |
81 | * 'pointer to map element key' | |
82 | * | |
83 | * For example the argument constraints for bpf_map_lookup_elem(): | |
84 | * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, | |
85 | * .arg1_type = ARG_CONST_MAP_PTR, | |
86 | * .arg2_type = ARG_PTR_TO_MAP_KEY, | |
87 | * | |
88 | * ret_type says that this function returns 'pointer to map elem value or null' | |
89 | * function expects 1st argument to be a const pointer to 'struct bpf_map' and | |
90 | * 2nd argument should be a pointer to stack, which will be used inside | |
91 | * the helper function as a pointer to map element key. | |
92 | * | |
93 | * On the kernel side the helper function looks like: | |
94 | * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
95 | * { | |
96 | * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
97 | * void *key = (void *) (unsigned long) r2; | |
98 | * void *value; | |
99 | * | |
100 | * here kernel can access 'key' and 'map' pointers safely, knowing that | |
101 | * [key, key + map->key_size) bytes are valid and were initialized on | |
102 | * the stack of eBPF program. | |
103 | * } | |
104 | * | |
105 | * Corresponding eBPF program may look like: | |
106 | * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR | |
107 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK | |
108 | * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP | |
109 | * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
110 | * here verifier looks at prototype of map_lookup_elem() and sees: | |
111 | * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, | |
112 | * Now verifier knows that this map has key of R1->map_ptr->key_size bytes | |
113 | * | |
114 | * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, | |
115 | * Now verifier checks that [R2, R2 + map's key_size) are within stack limits | |
116 | * and were initialized prior to this call. | |
117 | * If it's ok, then verifier allows this BPF_CALL insn and looks at | |
118 | * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets | |
119 | * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function | |
120 | * returns ether pointer to map value or NULL. | |
121 | * | |
122 | * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' | |
123 | * insn, the register holding that pointer in the true branch changes state to | |
124 | * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false | |
125 | * branch. See check_cond_jmp_op(). | |
126 | * | |
127 | * After the call R0 is set to return type of the function and registers R1-R5 | |
128 | * are set to NOT_INIT to indicate that they are no longer readable. | |
129 | */ | |
130 | ||
17a52670 | 131 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ |
58e2af8b | 132 | struct bpf_verifier_stack_elem { |
17a52670 AS |
133 | /* verifer state is 'st' |
134 | * before processing instruction 'insn_idx' | |
135 | * and after processing instruction 'prev_insn_idx' | |
136 | */ | |
58e2af8b | 137 | struct bpf_verifier_state st; |
17a52670 AS |
138 | int insn_idx; |
139 | int prev_insn_idx; | |
58e2af8b | 140 | struct bpf_verifier_stack_elem *next; |
cbd35700 AS |
141 | }; |
142 | ||
07016151 DB |
143 | #define BPF_COMPLEXITY_LIMIT_INSNS 65536 |
144 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 | |
145 | ||
33ff9823 DB |
146 | struct bpf_call_arg_meta { |
147 | struct bpf_map *map_ptr; | |
435faee1 | 148 | bool raw_mode; |
36bbef52 | 149 | bool pkt_access; |
435faee1 DB |
150 | int regno; |
151 | int access_size; | |
33ff9823 DB |
152 | }; |
153 | ||
cbd35700 AS |
154 | /* verbose verifier prints what it's seeing |
155 | * bpf_check() is called under lock, so no race to access these global vars | |
156 | */ | |
157 | static u32 log_level, log_size, log_len; | |
158 | static char *log_buf; | |
159 | ||
160 | static DEFINE_MUTEX(bpf_verifier_lock); | |
161 | ||
162 | /* log_level controls verbosity level of eBPF verifier. | |
163 | * verbose() is used to dump the verification trace to the log, so the user | |
164 | * can figure out what's wrong with the program | |
165 | */ | |
1d056d9c | 166 | static __printf(1, 2) void verbose(const char *fmt, ...) |
cbd35700 AS |
167 | { |
168 | va_list args; | |
169 | ||
170 | if (log_level == 0 || log_len >= log_size - 1) | |
171 | return; | |
172 | ||
173 | va_start(args, fmt); | |
174 | log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); | |
175 | va_end(args); | |
176 | } | |
177 | ||
17a52670 AS |
178 | /* string representation of 'enum bpf_reg_type' */ |
179 | static const char * const reg_type_str[] = { | |
180 | [NOT_INIT] = "?", | |
181 | [UNKNOWN_VALUE] = "inv", | |
182 | [PTR_TO_CTX] = "ctx", | |
183 | [CONST_PTR_TO_MAP] = "map_ptr", | |
184 | [PTR_TO_MAP_VALUE] = "map_value", | |
185 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
48461135 | 186 | [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj", |
17a52670 AS |
187 | [FRAME_PTR] = "fp", |
188 | [PTR_TO_STACK] = "fp", | |
189 | [CONST_IMM] = "imm", | |
969bf05e AS |
190 | [PTR_TO_PACKET] = "pkt", |
191 | [PTR_TO_PACKET_END] = "pkt_end", | |
17a52670 AS |
192 | }; |
193 | ||
ebb676da TG |
194 | #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x) |
195 | static const char * const func_id_str[] = { | |
196 | __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN) | |
197 | }; | |
198 | #undef __BPF_FUNC_STR_FN | |
199 | ||
200 | static const char *func_id_name(int id) | |
201 | { | |
202 | BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID); | |
203 | ||
204 | if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id]) | |
205 | return func_id_str[id]; | |
206 | else | |
207 | return "unknown"; | |
208 | } | |
209 | ||
58e2af8b | 210 | static void print_verifier_state(struct bpf_verifier_state *state) |
17a52670 | 211 | { |
58e2af8b | 212 | struct bpf_reg_state *reg; |
17a52670 AS |
213 | enum bpf_reg_type t; |
214 | int i; | |
215 | ||
216 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
217 | reg = &state->regs[i]; |
218 | t = reg->type; | |
17a52670 AS |
219 | if (t == NOT_INIT) |
220 | continue; | |
221 | verbose(" R%d=%s", i, reg_type_str[t]); | |
222 | if (t == CONST_IMM || t == PTR_TO_STACK) | |
969bf05e AS |
223 | verbose("%lld", reg->imm); |
224 | else if (t == PTR_TO_PACKET) | |
225 | verbose("(id=%d,off=%d,r=%d)", | |
226 | reg->id, reg->off, reg->range); | |
227 | else if (t == UNKNOWN_VALUE && reg->imm) | |
228 | verbose("%lld", reg->imm); | |
17a52670 | 229 | else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || |
48461135 JB |
230 | t == PTR_TO_MAP_VALUE_OR_NULL || |
231 | t == PTR_TO_MAP_VALUE_ADJ) | |
57a09bf0 | 232 | verbose("(ks=%d,vs=%d,id=%u)", |
1a0dc1ac | 233 | reg->map_ptr->key_size, |
57a09bf0 TG |
234 | reg->map_ptr->value_size, |
235 | reg->id); | |
48461135 | 236 | if (reg->min_value != BPF_REGISTER_MIN_RANGE) |
f23cc643 JB |
237 | verbose(",min_value=%lld", |
238 | (long long)reg->min_value); | |
48461135 JB |
239 | if (reg->max_value != BPF_REGISTER_MAX_RANGE) |
240 | verbose(",max_value=%llu", | |
241 | (unsigned long long)reg->max_value); | |
17a52670 | 242 | } |
9c399760 | 243 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 244 | if (state->stack_slot_type[i] == STACK_SPILL) |
17a52670 | 245 | verbose(" fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 246 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 AS |
247 | } |
248 | verbose("\n"); | |
249 | } | |
250 | ||
cbd35700 AS |
251 | static const char *const bpf_class_string[] = { |
252 | [BPF_LD] = "ld", | |
253 | [BPF_LDX] = "ldx", | |
254 | [BPF_ST] = "st", | |
255 | [BPF_STX] = "stx", | |
256 | [BPF_ALU] = "alu", | |
257 | [BPF_JMP] = "jmp", | |
258 | [BPF_RET] = "BUG", | |
259 | [BPF_ALU64] = "alu64", | |
260 | }; | |
261 | ||
687f0715 | 262 | static const char *const bpf_alu_string[16] = { |
cbd35700 AS |
263 | [BPF_ADD >> 4] = "+=", |
264 | [BPF_SUB >> 4] = "-=", | |
265 | [BPF_MUL >> 4] = "*=", | |
266 | [BPF_DIV >> 4] = "/=", | |
267 | [BPF_OR >> 4] = "|=", | |
268 | [BPF_AND >> 4] = "&=", | |
269 | [BPF_LSH >> 4] = "<<=", | |
270 | [BPF_RSH >> 4] = ">>=", | |
271 | [BPF_NEG >> 4] = "neg", | |
272 | [BPF_MOD >> 4] = "%=", | |
273 | [BPF_XOR >> 4] = "^=", | |
274 | [BPF_MOV >> 4] = "=", | |
275 | [BPF_ARSH >> 4] = "s>>=", | |
276 | [BPF_END >> 4] = "endian", | |
277 | }; | |
278 | ||
279 | static const char *const bpf_ldst_string[] = { | |
280 | [BPF_W >> 3] = "u32", | |
281 | [BPF_H >> 3] = "u16", | |
282 | [BPF_B >> 3] = "u8", | |
283 | [BPF_DW >> 3] = "u64", | |
284 | }; | |
285 | ||
687f0715 | 286 | static const char *const bpf_jmp_string[16] = { |
cbd35700 AS |
287 | [BPF_JA >> 4] = "jmp", |
288 | [BPF_JEQ >> 4] = "==", | |
289 | [BPF_JGT >> 4] = ">", | |
290 | [BPF_JGE >> 4] = ">=", | |
291 | [BPF_JSET >> 4] = "&", | |
292 | [BPF_JNE >> 4] = "!=", | |
293 | [BPF_JSGT >> 4] = "s>", | |
294 | [BPF_JSGE >> 4] = "s>=", | |
295 | [BPF_CALL >> 4] = "call", | |
296 | [BPF_EXIT >> 4] = "exit", | |
297 | }; | |
298 | ||
299 | static void print_bpf_insn(struct bpf_insn *insn) | |
300 | { | |
301 | u8 class = BPF_CLASS(insn->code); | |
302 | ||
303 | if (class == BPF_ALU || class == BPF_ALU64) { | |
304 | if (BPF_SRC(insn->code) == BPF_X) | |
305 | verbose("(%02x) %sr%d %s %sr%d\n", | |
306 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
307 | insn->dst_reg, | |
308 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
309 | class == BPF_ALU ? "(u32) " : "", | |
310 | insn->src_reg); | |
311 | else | |
312 | verbose("(%02x) %sr%d %s %s%d\n", | |
313 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
314 | insn->dst_reg, | |
315 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
316 | class == BPF_ALU ? "(u32) " : "", | |
317 | insn->imm); | |
318 | } else if (class == BPF_STX) { | |
319 | if (BPF_MODE(insn->code) == BPF_MEM) | |
320 | verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", | |
321 | insn->code, | |
322 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
323 | insn->dst_reg, | |
324 | insn->off, insn->src_reg); | |
325 | else if (BPF_MODE(insn->code) == BPF_XADD) | |
326 | verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", | |
327 | insn->code, | |
328 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
329 | insn->dst_reg, insn->off, | |
330 | insn->src_reg); | |
331 | else | |
332 | verbose("BUG_%02x\n", insn->code); | |
333 | } else if (class == BPF_ST) { | |
334 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
335 | verbose("BUG_st_%02x\n", insn->code); | |
336 | return; | |
337 | } | |
338 | verbose("(%02x) *(%s *)(r%d %+d) = %d\n", | |
339 | insn->code, | |
340 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
341 | insn->dst_reg, | |
342 | insn->off, insn->imm); | |
343 | } else if (class == BPF_LDX) { | |
344 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
345 | verbose("BUG_ldx_%02x\n", insn->code); | |
346 | return; | |
347 | } | |
348 | verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", | |
349 | insn->code, insn->dst_reg, | |
350 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
351 | insn->src_reg, insn->off); | |
352 | } else if (class == BPF_LD) { | |
353 | if (BPF_MODE(insn->code) == BPF_ABS) { | |
354 | verbose("(%02x) r0 = *(%s *)skb[%d]\n", | |
355 | insn->code, | |
356 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
357 | insn->imm); | |
358 | } else if (BPF_MODE(insn->code) == BPF_IND) { | |
359 | verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", | |
360 | insn->code, | |
361 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
362 | insn->src_reg, insn->imm); | |
363 | } else if (BPF_MODE(insn->code) == BPF_IMM) { | |
364 | verbose("(%02x) r%d = 0x%x\n", | |
365 | insn->code, insn->dst_reg, insn->imm); | |
366 | } else { | |
367 | verbose("BUG_ld_%02x\n", insn->code); | |
368 | return; | |
369 | } | |
370 | } else if (class == BPF_JMP) { | |
371 | u8 opcode = BPF_OP(insn->code); | |
372 | ||
373 | if (opcode == BPF_CALL) { | |
ebb676da TG |
374 | verbose("(%02x) call %s#%d\n", insn->code, |
375 | func_id_name(insn->imm), insn->imm); | |
cbd35700 AS |
376 | } else if (insn->code == (BPF_JMP | BPF_JA)) { |
377 | verbose("(%02x) goto pc%+d\n", | |
378 | insn->code, insn->off); | |
379 | } else if (insn->code == (BPF_JMP | BPF_EXIT)) { | |
380 | verbose("(%02x) exit\n", insn->code); | |
381 | } else if (BPF_SRC(insn->code) == BPF_X) { | |
382 | verbose("(%02x) if r%d %s r%d goto pc%+d\n", | |
383 | insn->code, insn->dst_reg, | |
384 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
385 | insn->src_reg, insn->off); | |
386 | } else { | |
387 | verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", | |
388 | insn->code, insn->dst_reg, | |
389 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
390 | insn->imm, insn->off); | |
391 | } | |
392 | } else { | |
393 | verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); | |
394 | } | |
395 | } | |
396 | ||
58e2af8b | 397 | static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) |
17a52670 | 398 | { |
58e2af8b | 399 | struct bpf_verifier_stack_elem *elem; |
17a52670 AS |
400 | int insn_idx; |
401 | ||
402 | if (env->head == NULL) | |
403 | return -1; | |
404 | ||
405 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
406 | insn_idx = env->head->insn_idx; | |
407 | if (prev_insn_idx) | |
408 | *prev_insn_idx = env->head->prev_insn_idx; | |
409 | elem = env->head->next; | |
410 | kfree(env->head); | |
411 | env->head = elem; | |
412 | env->stack_size--; | |
413 | return insn_idx; | |
414 | } | |
415 | ||
58e2af8b JK |
416 | static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, |
417 | int insn_idx, int prev_insn_idx) | |
17a52670 | 418 | { |
58e2af8b | 419 | struct bpf_verifier_stack_elem *elem; |
17a52670 | 420 | |
58e2af8b | 421 | elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); |
17a52670 AS |
422 | if (!elem) |
423 | goto err; | |
424 | ||
425 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
426 | elem->insn_idx = insn_idx; | |
427 | elem->prev_insn_idx = prev_insn_idx; | |
428 | elem->next = env->head; | |
429 | env->head = elem; | |
430 | env->stack_size++; | |
07016151 | 431 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
17a52670 AS |
432 | verbose("BPF program is too complex\n"); |
433 | goto err; | |
434 | } | |
435 | return &elem->st; | |
436 | err: | |
437 | /* pop all elements and return */ | |
438 | while (pop_stack(env, NULL) >= 0); | |
439 | return NULL; | |
440 | } | |
441 | ||
442 | #define CALLER_SAVED_REGS 6 | |
443 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
444 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
445 | }; | |
446 | ||
58e2af8b | 447 | static void init_reg_state(struct bpf_reg_state *regs) |
17a52670 AS |
448 | { |
449 | int i; | |
450 | ||
451 | for (i = 0; i < MAX_BPF_REG; i++) { | |
452 | regs[i].type = NOT_INIT; | |
453 | regs[i].imm = 0; | |
48461135 JB |
454 | regs[i].min_value = BPF_REGISTER_MIN_RANGE; |
455 | regs[i].max_value = BPF_REGISTER_MAX_RANGE; | |
17a52670 AS |
456 | } |
457 | ||
458 | /* frame pointer */ | |
459 | regs[BPF_REG_FP].type = FRAME_PTR; | |
460 | ||
461 | /* 1st arg to a function */ | |
462 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
463 | } | |
464 | ||
58e2af8b | 465 | static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) |
17a52670 AS |
466 | { |
467 | BUG_ON(regno >= MAX_BPF_REG); | |
468 | regs[regno].type = UNKNOWN_VALUE; | |
57a09bf0 | 469 | regs[regno].id = 0; |
17a52670 | 470 | regs[regno].imm = 0; |
17a52670 AS |
471 | } |
472 | ||
48461135 JB |
473 | static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno) |
474 | { | |
475 | regs[regno].min_value = BPF_REGISTER_MIN_RANGE; | |
476 | regs[regno].max_value = BPF_REGISTER_MAX_RANGE; | |
477 | } | |
478 | ||
17a52670 AS |
479 | enum reg_arg_type { |
480 | SRC_OP, /* register is used as source operand */ | |
481 | DST_OP, /* register is used as destination operand */ | |
482 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
483 | }; | |
484 | ||
58e2af8b | 485 | static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, |
17a52670 AS |
486 | enum reg_arg_type t) |
487 | { | |
488 | if (regno >= MAX_BPF_REG) { | |
489 | verbose("R%d is invalid\n", regno); | |
490 | return -EINVAL; | |
491 | } | |
492 | ||
493 | if (t == SRC_OP) { | |
494 | /* check whether register used as source operand can be read */ | |
495 | if (regs[regno].type == NOT_INIT) { | |
496 | verbose("R%d !read_ok\n", regno); | |
497 | return -EACCES; | |
498 | } | |
499 | } else { | |
500 | /* check whether register used as dest operand can be written to */ | |
501 | if (regno == BPF_REG_FP) { | |
502 | verbose("frame pointer is read only\n"); | |
503 | return -EACCES; | |
504 | } | |
505 | if (t == DST_OP) | |
506 | mark_reg_unknown_value(regs, regno); | |
507 | } | |
508 | return 0; | |
509 | } | |
510 | ||
511 | static int bpf_size_to_bytes(int bpf_size) | |
512 | { | |
513 | if (bpf_size == BPF_W) | |
514 | return 4; | |
515 | else if (bpf_size == BPF_H) | |
516 | return 2; | |
517 | else if (bpf_size == BPF_B) | |
518 | return 1; | |
519 | else if (bpf_size == BPF_DW) | |
520 | return 8; | |
521 | else | |
522 | return -EINVAL; | |
523 | } | |
524 | ||
1be7f75d AS |
525 | static bool is_spillable_regtype(enum bpf_reg_type type) |
526 | { | |
527 | switch (type) { | |
528 | case PTR_TO_MAP_VALUE: | |
529 | case PTR_TO_MAP_VALUE_OR_NULL: | |
530 | case PTR_TO_STACK: | |
531 | case PTR_TO_CTX: | |
969bf05e AS |
532 | case PTR_TO_PACKET: |
533 | case PTR_TO_PACKET_END: | |
1be7f75d AS |
534 | case FRAME_PTR: |
535 | case CONST_PTR_TO_MAP: | |
536 | return true; | |
537 | default: | |
538 | return false; | |
539 | } | |
540 | } | |
541 | ||
17a52670 AS |
542 | /* check_stack_read/write functions track spill/fill of registers, |
543 | * stack boundary and alignment are checked in check_mem_access() | |
544 | */ | |
58e2af8b JK |
545 | static int check_stack_write(struct bpf_verifier_state *state, int off, |
546 | int size, int value_regno) | |
17a52670 | 547 | { |
17a52670 | 548 | int i; |
9c399760 AS |
549 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
550 | * so it's aligned access and [off, off + size) are within stack limits | |
551 | */ | |
17a52670 AS |
552 | |
553 | if (value_regno >= 0 && | |
1be7f75d | 554 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
555 | |
556 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 557 | if (size != BPF_REG_SIZE) { |
17a52670 AS |
558 | verbose("invalid size of register spill\n"); |
559 | return -EACCES; | |
560 | } | |
561 | ||
17a52670 | 562 | /* save register state */ |
9c399760 AS |
563 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
564 | state->regs[value_regno]; | |
17a52670 | 565 | |
9c399760 AS |
566 | for (i = 0; i < BPF_REG_SIZE; i++) |
567 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
568 | } else { | |
17a52670 | 569 | /* regular write of data into stack */ |
9c399760 | 570 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
58e2af8b | 571 | (struct bpf_reg_state) {}; |
9c399760 AS |
572 | |
573 | for (i = 0; i < size; i++) | |
574 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
575 | } |
576 | return 0; | |
577 | } | |
578 | ||
58e2af8b | 579 | static int check_stack_read(struct bpf_verifier_state *state, int off, int size, |
17a52670 AS |
580 | int value_regno) |
581 | { | |
9c399760 | 582 | u8 *slot_type; |
17a52670 | 583 | int i; |
17a52670 | 584 | |
9c399760 | 585 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 586 | |
9c399760 AS |
587 | if (slot_type[0] == STACK_SPILL) { |
588 | if (size != BPF_REG_SIZE) { | |
17a52670 AS |
589 | verbose("invalid size of register spill\n"); |
590 | return -EACCES; | |
591 | } | |
9c399760 AS |
592 | for (i = 1; i < BPF_REG_SIZE; i++) { |
593 | if (slot_type[i] != STACK_SPILL) { | |
17a52670 AS |
594 | verbose("corrupted spill memory\n"); |
595 | return -EACCES; | |
596 | } | |
597 | } | |
598 | ||
599 | if (value_regno >= 0) | |
600 | /* restore register state from stack */ | |
9c399760 AS |
601 | state->regs[value_regno] = |
602 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; | |
17a52670 AS |
603 | return 0; |
604 | } else { | |
605 | for (i = 0; i < size; i++) { | |
9c399760 | 606 | if (slot_type[i] != STACK_MISC) { |
17a52670 AS |
607 | verbose("invalid read from stack off %d+%d size %d\n", |
608 | off, i, size); | |
609 | return -EACCES; | |
610 | } | |
611 | } | |
612 | if (value_regno >= 0) | |
613 | /* have read misc data from the stack */ | |
614 | mark_reg_unknown_value(state->regs, value_regno); | |
615 | return 0; | |
616 | } | |
617 | } | |
618 | ||
619 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
58e2af8b | 620 | static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
621 | int size) |
622 | { | |
623 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
624 | ||
625 | if (off < 0 || off + size > map->value_size) { | |
626 | verbose("invalid access to map value, value_size=%d off=%d size=%d\n", | |
627 | map->value_size, off, size); | |
628 | return -EACCES; | |
629 | } | |
630 | return 0; | |
631 | } | |
632 | ||
969bf05e AS |
633 | #define MAX_PACKET_OFF 0xffff |
634 | ||
58e2af8b | 635 | static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, |
3a0af8fd TG |
636 | const struct bpf_call_arg_meta *meta, |
637 | enum bpf_access_type t) | |
4acf6c0b | 638 | { |
36bbef52 | 639 | switch (env->prog->type) { |
3a0af8fd TG |
640 | case BPF_PROG_TYPE_LWT_IN: |
641 | case BPF_PROG_TYPE_LWT_OUT: | |
642 | /* dst_input() and dst_output() can't write for now */ | |
643 | if (t == BPF_WRITE) | |
644 | return false; | |
36bbef52 DB |
645 | case BPF_PROG_TYPE_SCHED_CLS: |
646 | case BPF_PROG_TYPE_SCHED_ACT: | |
4acf6c0b | 647 | case BPF_PROG_TYPE_XDP: |
3a0af8fd | 648 | case BPF_PROG_TYPE_LWT_XMIT: |
36bbef52 DB |
649 | if (meta) |
650 | return meta->pkt_access; | |
651 | ||
652 | env->seen_direct_write = true; | |
4acf6c0b BB |
653 | return true; |
654 | default: | |
655 | return false; | |
656 | } | |
657 | } | |
658 | ||
58e2af8b | 659 | static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, |
969bf05e AS |
660 | int size) |
661 | { | |
58e2af8b JK |
662 | struct bpf_reg_state *regs = env->cur_state.regs; |
663 | struct bpf_reg_state *reg = ®s[regno]; | |
969bf05e | 664 | |
d91b28ed | 665 | off += reg->off; |
b399cf64 | 666 | if (off < 0 || size <= 0 || off + size > reg->range) { |
d91b28ed AS |
667 | verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", |
668 | off, size, regno, reg->id, reg->off, reg->range); | |
969bf05e AS |
669 | return -EACCES; |
670 | } | |
671 | return 0; | |
672 | } | |
673 | ||
17a52670 | 674 | /* check access to 'struct bpf_context' fields */ |
58e2af8b | 675 | static int check_ctx_access(struct bpf_verifier_env *env, int off, int size, |
19de99f7 | 676 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 | 677 | { |
13a27dfc JK |
678 | /* for analyzer ctx accesses are already validated and converted */ |
679 | if (env->analyzer_ops) | |
680 | return 0; | |
681 | ||
17a52670 | 682 | if (env->prog->aux->ops->is_valid_access && |
19de99f7 | 683 | env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { |
32bbe007 AS |
684 | /* remember the offset of last byte accessed in ctx */ |
685 | if (env->prog->aux->max_ctx_offset < off + size) | |
686 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 687 | return 0; |
32bbe007 | 688 | } |
17a52670 AS |
689 | |
690 | verbose("invalid bpf_context access off=%d size=%d\n", off, size); | |
691 | return -EACCES; | |
692 | } | |
693 | ||
58e2af8b | 694 | static bool is_pointer_value(struct bpf_verifier_env *env, int regno) |
1be7f75d AS |
695 | { |
696 | if (env->allow_ptr_leaks) | |
697 | return false; | |
698 | ||
699 | switch (env->cur_state.regs[regno].type) { | |
700 | case UNKNOWN_VALUE: | |
701 | case CONST_IMM: | |
702 | return false; | |
703 | default: | |
704 | return true; | |
705 | } | |
706 | } | |
707 | ||
58e2af8b JK |
708 | static int check_ptr_alignment(struct bpf_verifier_env *env, |
709 | struct bpf_reg_state *reg, int off, int size) | |
969bf05e | 710 | { |
48461135 | 711 | if (reg->type != PTR_TO_PACKET && reg->type != PTR_TO_MAP_VALUE_ADJ) { |
969bf05e | 712 | if (off % size != 0) { |
58e2af8b JK |
713 | verbose("misaligned access off %d size %d\n", |
714 | off, size); | |
969bf05e AS |
715 | return -EACCES; |
716 | } else { | |
717 | return 0; | |
718 | } | |
719 | } | |
720 | ||
969bf05e AS |
721 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) |
722 | /* misaligned access to packet is ok on x86,arm,arm64 */ | |
723 | return 0; | |
724 | ||
725 | if (reg->id && size != 1) { | |
726 | verbose("Unknown packet alignment. Only byte-sized access allowed\n"); | |
727 | return -EACCES; | |
728 | } | |
729 | ||
730 | /* skb->data is NET_IP_ALIGN-ed */ | |
48461135 JB |
731 | if (reg->type == PTR_TO_PACKET && |
732 | (NET_IP_ALIGN + reg->off + off) % size != 0) { | |
969bf05e AS |
733 | verbose("misaligned packet access off %d+%d+%d size %d\n", |
734 | NET_IP_ALIGN, reg->off, off, size); | |
735 | return -EACCES; | |
736 | } | |
737 | return 0; | |
738 | } | |
739 | ||
17a52670 AS |
740 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
741 | * if t==write, value_regno is a register which value is stored into memory | |
742 | * if t==read, value_regno is a register which will receive the value from memory | |
743 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
744 | * if t==read && value_regno==-1, don't care what we read from memory | |
745 | */ | |
58e2af8b | 746 | static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
747 | int bpf_size, enum bpf_access_type t, |
748 | int value_regno) | |
749 | { | |
58e2af8b JK |
750 | struct bpf_verifier_state *state = &env->cur_state; |
751 | struct bpf_reg_state *reg = &state->regs[regno]; | |
17a52670 AS |
752 | int size, err = 0; |
753 | ||
1a0dc1ac AS |
754 | if (reg->type == PTR_TO_STACK) |
755 | off += reg->imm; | |
24b4d2ab | 756 | |
17a52670 AS |
757 | size = bpf_size_to_bytes(bpf_size); |
758 | if (size < 0) | |
759 | return size; | |
760 | ||
969bf05e AS |
761 | err = check_ptr_alignment(env, reg, off, size); |
762 | if (err) | |
763 | return err; | |
17a52670 | 764 | |
48461135 JB |
765 | if (reg->type == PTR_TO_MAP_VALUE || |
766 | reg->type == PTR_TO_MAP_VALUE_ADJ) { | |
1be7f75d AS |
767 | if (t == BPF_WRITE && value_regno >= 0 && |
768 | is_pointer_value(env, value_regno)) { | |
769 | verbose("R%d leaks addr into map\n", value_regno); | |
770 | return -EACCES; | |
771 | } | |
48461135 JB |
772 | |
773 | /* If we adjusted the register to this map value at all then we | |
774 | * need to change off and size to min_value and max_value | |
775 | * respectively to make sure our theoretical access will be | |
776 | * safe. | |
777 | */ | |
778 | if (reg->type == PTR_TO_MAP_VALUE_ADJ) { | |
779 | if (log_level) | |
780 | print_verifier_state(state); | |
781 | env->varlen_map_value_access = true; | |
782 | /* The minimum value is only important with signed | |
783 | * comparisons where we can't assume the floor of a | |
784 | * value is 0. If we are using signed variables for our | |
785 | * index'es we need to make sure that whatever we use | |
786 | * will have a set floor within our range. | |
787 | */ | |
f23cc643 | 788 | if (reg->min_value < 0) { |
48461135 JB |
789 | verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
790 | regno); | |
791 | return -EACCES; | |
792 | } | |
793 | err = check_map_access(env, regno, reg->min_value + off, | |
794 | size); | |
795 | if (err) { | |
796 | verbose("R%d min value is outside of the array range\n", | |
797 | regno); | |
798 | return err; | |
799 | } | |
800 | ||
801 | /* If we haven't set a max value then we need to bail | |
802 | * since we can't be sure we won't do bad things. | |
803 | */ | |
804 | if (reg->max_value == BPF_REGISTER_MAX_RANGE) { | |
805 | verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", | |
806 | regno); | |
807 | return -EACCES; | |
808 | } | |
809 | off += reg->max_value; | |
810 | } | |
17a52670 AS |
811 | err = check_map_access(env, regno, off, size); |
812 | if (!err && t == BPF_READ && value_regno >= 0) | |
813 | mark_reg_unknown_value(state->regs, value_regno); | |
814 | ||
1a0dc1ac | 815 | } else if (reg->type == PTR_TO_CTX) { |
19de99f7 AS |
816 | enum bpf_reg_type reg_type = UNKNOWN_VALUE; |
817 | ||
1be7f75d AS |
818 | if (t == BPF_WRITE && value_regno >= 0 && |
819 | is_pointer_value(env, value_regno)) { | |
820 | verbose("R%d leaks addr into ctx\n", value_regno); | |
821 | return -EACCES; | |
822 | } | |
19de99f7 | 823 | err = check_ctx_access(env, off, size, t, ®_type); |
969bf05e | 824 | if (!err && t == BPF_READ && value_regno >= 0) { |
17a52670 | 825 | mark_reg_unknown_value(state->regs, value_regno); |
1955351d MS |
826 | /* note that reg.[id|off|range] == 0 */ |
827 | state->regs[value_regno].type = reg_type; | |
969bf05e | 828 | } |
17a52670 | 829 | |
1a0dc1ac | 830 | } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { |
17a52670 AS |
831 | if (off >= 0 || off < -MAX_BPF_STACK) { |
832 | verbose("invalid stack off=%d size=%d\n", off, size); | |
833 | return -EACCES; | |
834 | } | |
1be7f75d AS |
835 | if (t == BPF_WRITE) { |
836 | if (!env->allow_ptr_leaks && | |
837 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
838 | size != BPF_REG_SIZE) { | |
839 | verbose("attempt to corrupt spilled pointer on stack\n"); | |
840 | return -EACCES; | |
841 | } | |
17a52670 | 842 | err = check_stack_write(state, off, size, value_regno); |
1be7f75d | 843 | } else { |
17a52670 | 844 | err = check_stack_read(state, off, size, value_regno); |
1be7f75d | 845 | } |
969bf05e | 846 | } else if (state->regs[regno].type == PTR_TO_PACKET) { |
3a0af8fd | 847 | if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { |
969bf05e AS |
848 | verbose("cannot write into packet\n"); |
849 | return -EACCES; | |
850 | } | |
4acf6c0b BB |
851 | if (t == BPF_WRITE && value_regno >= 0 && |
852 | is_pointer_value(env, value_regno)) { | |
853 | verbose("R%d leaks addr into packet\n", value_regno); | |
854 | return -EACCES; | |
855 | } | |
969bf05e AS |
856 | err = check_packet_access(env, regno, off, size); |
857 | if (!err && t == BPF_READ && value_regno >= 0) | |
858 | mark_reg_unknown_value(state->regs, value_regno); | |
17a52670 AS |
859 | } else { |
860 | verbose("R%d invalid mem access '%s'\n", | |
1a0dc1ac | 861 | regno, reg_type_str[reg->type]); |
17a52670 AS |
862 | return -EACCES; |
863 | } | |
969bf05e AS |
864 | |
865 | if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && | |
866 | state->regs[value_regno].type == UNKNOWN_VALUE) { | |
867 | /* 1 or 2 byte load zero-extends, determine the number of | |
868 | * zero upper bits. Not doing it fo 4 byte load, since | |
869 | * such values cannot be added to ptr_to_packet anyway. | |
870 | */ | |
871 | state->regs[value_regno].imm = 64 - size * 8; | |
872 | } | |
17a52670 AS |
873 | return err; |
874 | } | |
875 | ||
58e2af8b | 876 | static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 877 | { |
58e2af8b | 878 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
879 | int err; |
880 | ||
881 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
882 | insn->imm != 0) { | |
883 | verbose("BPF_XADD uses reserved fields\n"); | |
884 | return -EINVAL; | |
885 | } | |
886 | ||
887 | /* check src1 operand */ | |
888 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
889 | if (err) | |
890 | return err; | |
891 | ||
892 | /* check src2 operand */ | |
893 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
894 | if (err) | |
895 | return err; | |
896 | ||
897 | /* check whether atomic_add can read the memory */ | |
898 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
899 | BPF_SIZE(insn->code), BPF_READ, -1); | |
900 | if (err) | |
901 | return err; | |
902 | ||
903 | /* check whether atomic_add can write into the same memory */ | |
904 | return check_mem_access(env, insn->dst_reg, insn->off, | |
905 | BPF_SIZE(insn->code), BPF_WRITE, -1); | |
906 | } | |
907 | ||
908 | /* when register 'regno' is passed into function that will read 'access_size' | |
909 | * bytes from that pointer, make sure that it's within stack boundary | |
910 | * and all elements of stack are initialized | |
911 | */ | |
58e2af8b | 912 | static int check_stack_boundary(struct bpf_verifier_env *env, int regno, |
435faee1 DB |
913 | int access_size, bool zero_size_allowed, |
914 | struct bpf_call_arg_meta *meta) | |
17a52670 | 915 | { |
58e2af8b JK |
916 | struct bpf_verifier_state *state = &env->cur_state; |
917 | struct bpf_reg_state *regs = state->regs; | |
17a52670 AS |
918 | int off, i; |
919 | ||
8e2fe1d9 DB |
920 | if (regs[regno].type != PTR_TO_STACK) { |
921 | if (zero_size_allowed && access_size == 0 && | |
922 | regs[regno].type == CONST_IMM && | |
923 | regs[regno].imm == 0) | |
924 | return 0; | |
925 | ||
926 | verbose("R%d type=%s expected=%s\n", regno, | |
927 | reg_type_str[regs[regno].type], | |
928 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 929 | return -EACCES; |
8e2fe1d9 | 930 | } |
17a52670 AS |
931 | |
932 | off = regs[regno].imm; | |
933 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || | |
934 | access_size <= 0) { | |
935 | verbose("invalid stack type R%d off=%d access_size=%d\n", | |
936 | regno, off, access_size); | |
937 | return -EACCES; | |
938 | } | |
939 | ||
435faee1 DB |
940 | if (meta && meta->raw_mode) { |
941 | meta->access_size = access_size; | |
942 | meta->regno = regno; | |
943 | return 0; | |
944 | } | |
945 | ||
17a52670 | 946 | for (i = 0; i < access_size; i++) { |
9c399760 | 947 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
17a52670 AS |
948 | verbose("invalid indirect read from stack off %d+%d size %d\n", |
949 | off, i, access_size); | |
950 | return -EACCES; | |
951 | } | |
952 | } | |
953 | return 0; | |
954 | } | |
955 | ||
58e2af8b | 956 | static int check_func_arg(struct bpf_verifier_env *env, u32 regno, |
33ff9823 DB |
957 | enum bpf_arg_type arg_type, |
958 | struct bpf_call_arg_meta *meta) | |
17a52670 | 959 | { |
58e2af8b | 960 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
6841de8b | 961 | enum bpf_reg_type expected_type, type = reg->type; |
17a52670 AS |
962 | int err = 0; |
963 | ||
80f1d68c | 964 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
965 | return 0; |
966 | ||
6841de8b | 967 | if (type == NOT_INIT) { |
17a52670 AS |
968 | verbose("R%d !read_ok\n", regno); |
969 | return -EACCES; | |
970 | } | |
971 | ||
1be7f75d AS |
972 | if (arg_type == ARG_ANYTHING) { |
973 | if (is_pointer_value(env, regno)) { | |
974 | verbose("R%d leaks addr into helper function\n", regno); | |
975 | return -EACCES; | |
976 | } | |
80f1d68c | 977 | return 0; |
1be7f75d | 978 | } |
80f1d68c | 979 | |
3a0af8fd TG |
980 | if (type == PTR_TO_PACKET && |
981 | !may_access_direct_pkt_data(env, meta, BPF_READ)) { | |
36bbef52 | 982 | verbose("helper access to the packet is not allowed\n"); |
6841de8b AS |
983 | return -EACCES; |
984 | } | |
985 | ||
8e2fe1d9 | 986 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
987 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
988 | expected_type = PTR_TO_STACK; | |
6841de8b AS |
989 | if (type != PTR_TO_PACKET && type != expected_type) |
990 | goto err_type; | |
8e2fe1d9 DB |
991 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
992 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
17a52670 | 993 | expected_type = CONST_IMM; |
6841de8b AS |
994 | if (type != expected_type) |
995 | goto err_type; | |
17a52670 AS |
996 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
997 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
998 | if (type != expected_type) |
999 | goto err_type; | |
608cd71a AS |
1000 | } else if (arg_type == ARG_PTR_TO_CTX) { |
1001 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
1002 | if (type != expected_type) |
1003 | goto err_type; | |
435faee1 DB |
1004 | } else if (arg_type == ARG_PTR_TO_STACK || |
1005 | arg_type == ARG_PTR_TO_RAW_STACK) { | |
8e2fe1d9 DB |
1006 | expected_type = PTR_TO_STACK; |
1007 | /* One exception here. In case function allows for NULL to be | |
1008 | * passed in as argument, it's a CONST_IMM type. Final test | |
1009 | * happens during stack boundary checking. | |
1010 | */ | |
6841de8b AS |
1011 | if (type == CONST_IMM && reg->imm == 0) |
1012 | /* final test in check_stack_boundary() */; | |
1013 | else if (type != PTR_TO_PACKET && type != expected_type) | |
1014 | goto err_type; | |
435faee1 | 1015 | meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK; |
17a52670 AS |
1016 | } else { |
1017 | verbose("unsupported arg_type %d\n", arg_type); | |
1018 | return -EFAULT; | |
1019 | } | |
1020 | ||
17a52670 AS |
1021 | if (arg_type == ARG_CONST_MAP_PTR) { |
1022 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 1023 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
1024 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
1025 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
1026 | * check that [key, key + map->key_size) are within | |
1027 | * stack limits and initialized | |
1028 | */ | |
33ff9823 | 1029 | if (!meta->map_ptr) { |
17a52670 AS |
1030 | /* in function declaration map_ptr must come before |
1031 | * map_key, so that it's verified and known before | |
1032 | * we have to check map_key here. Otherwise it means | |
1033 | * that kernel subsystem misconfigured verifier | |
1034 | */ | |
1035 | verbose("invalid map_ptr to access map->key\n"); | |
1036 | return -EACCES; | |
1037 | } | |
6841de8b AS |
1038 | if (type == PTR_TO_PACKET) |
1039 | err = check_packet_access(env, regno, 0, | |
1040 | meta->map_ptr->key_size); | |
1041 | else | |
1042 | err = check_stack_boundary(env, regno, | |
1043 | meta->map_ptr->key_size, | |
1044 | false, NULL); | |
17a52670 AS |
1045 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1046 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1047 | * check [value, value + map->value_size) validity | |
1048 | */ | |
33ff9823 | 1049 | if (!meta->map_ptr) { |
17a52670 AS |
1050 | /* kernel subsystem misconfigured verifier */ |
1051 | verbose("invalid map_ptr to access map->value\n"); | |
1052 | return -EACCES; | |
1053 | } | |
6841de8b AS |
1054 | if (type == PTR_TO_PACKET) |
1055 | err = check_packet_access(env, regno, 0, | |
1056 | meta->map_ptr->value_size); | |
1057 | else | |
1058 | err = check_stack_boundary(env, regno, | |
1059 | meta->map_ptr->value_size, | |
1060 | false, NULL); | |
8e2fe1d9 DB |
1061 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
1062 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
1063 | bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO); | |
17a52670 | 1064 | |
17a52670 AS |
1065 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1066 | * from stack pointer 'buf'. Check it | |
1067 | * note: regno == len, regno - 1 == buf | |
1068 | */ | |
1069 | if (regno == 0) { | |
1070 | /* kernel subsystem misconfigured verifier */ | |
1071 | verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); | |
1072 | return -EACCES; | |
1073 | } | |
6841de8b AS |
1074 | if (regs[regno - 1].type == PTR_TO_PACKET) |
1075 | err = check_packet_access(env, regno - 1, 0, reg->imm); | |
1076 | else | |
1077 | err = check_stack_boundary(env, regno - 1, reg->imm, | |
1078 | zero_size_allowed, meta); | |
17a52670 AS |
1079 | } |
1080 | ||
1081 | return err; | |
6841de8b AS |
1082 | err_type: |
1083 | verbose("R%d type=%s expected=%s\n", regno, | |
1084 | reg_type_str[type], reg_type_str[expected_type]); | |
1085 | return -EACCES; | |
17a52670 AS |
1086 | } |
1087 | ||
35578d79 KX |
1088 | static int check_map_func_compatibility(struct bpf_map *map, int func_id) |
1089 | { | |
35578d79 KX |
1090 | if (!map) |
1091 | return 0; | |
1092 | ||
6aff67c8 AS |
1093 | /* We need a two way check, first is from map perspective ... */ |
1094 | switch (map->map_type) { | |
1095 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1096 | if (func_id != BPF_FUNC_tail_call) | |
1097 | goto error; | |
1098 | break; | |
1099 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1100 | if (func_id != BPF_FUNC_perf_event_read && | |
1101 | func_id != BPF_FUNC_perf_event_output) | |
1102 | goto error; | |
1103 | break; | |
1104 | case BPF_MAP_TYPE_STACK_TRACE: | |
1105 | if (func_id != BPF_FUNC_get_stackid) | |
1106 | goto error; | |
1107 | break; | |
4ed8ec52 | 1108 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1109 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1110 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1111 | goto error; |
1112 | break; | |
6aff67c8 AS |
1113 | default: |
1114 | break; | |
1115 | } | |
1116 | ||
1117 | /* ... and second from the function itself. */ | |
1118 | switch (func_id) { | |
1119 | case BPF_FUNC_tail_call: | |
1120 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1121 | goto error; | |
1122 | break; | |
1123 | case BPF_FUNC_perf_event_read: | |
1124 | case BPF_FUNC_perf_event_output: | |
1125 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) | |
1126 | goto error; | |
1127 | break; | |
1128 | case BPF_FUNC_get_stackid: | |
1129 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1130 | goto error; | |
1131 | break; | |
60d20f91 | 1132 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1133 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1134 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1135 | goto error; | |
1136 | break; | |
6aff67c8 AS |
1137 | default: |
1138 | break; | |
35578d79 KX |
1139 | } |
1140 | ||
1141 | return 0; | |
6aff67c8 | 1142 | error: |
ebb676da TG |
1143 | verbose("cannot pass map_type %d into func %s#%d\n", |
1144 | map->map_type, func_id_name(func_id), func_id); | |
6aff67c8 | 1145 | return -EINVAL; |
35578d79 KX |
1146 | } |
1147 | ||
435faee1 DB |
1148 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1149 | { | |
1150 | int count = 0; | |
1151 | ||
1152 | if (fn->arg1_type == ARG_PTR_TO_RAW_STACK) | |
1153 | count++; | |
1154 | if (fn->arg2_type == ARG_PTR_TO_RAW_STACK) | |
1155 | count++; | |
1156 | if (fn->arg3_type == ARG_PTR_TO_RAW_STACK) | |
1157 | count++; | |
1158 | if (fn->arg4_type == ARG_PTR_TO_RAW_STACK) | |
1159 | count++; | |
1160 | if (fn->arg5_type == ARG_PTR_TO_RAW_STACK) | |
1161 | count++; | |
1162 | ||
1163 | return count > 1 ? -EINVAL : 0; | |
1164 | } | |
1165 | ||
58e2af8b | 1166 | static void clear_all_pkt_pointers(struct bpf_verifier_env *env) |
969bf05e | 1167 | { |
58e2af8b JK |
1168 | struct bpf_verifier_state *state = &env->cur_state; |
1169 | struct bpf_reg_state *regs = state->regs, *reg; | |
969bf05e AS |
1170 | int i; |
1171 | ||
1172 | for (i = 0; i < MAX_BPF_REG; i++) | |
1173 | if (regs[i].type == PTR_TO_PACKET || | |
1174 | regs[i].type == PTR_TO_PACKET_END) | |
1175 | mark_reg_unknown_value(regs, i); | |
1176 | ||
1177 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1178 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1179 | continue; | |
1180 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1181 | if (reg->type != PTR_TO_PACKET && | |
1182 | reg->type != PTR_TO_PACKET_END) | |
1183 | continue; | |
1184 | reg->type = UNKNOWN_VALUE; | |
1185 | reg->imm = 0; | |
1186 | } | |
1187 | } | |
1188 | ||
58e2af8b | 1189 | static int check_call(struct bpf_verifier_env *env, int func_id) |
17a52670 | 1190 | { |
58e2af8b | 1191 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 1192 | const struct bpf_func_proto *fn = NULL; |
58e2af8b JK |
1193 | struct bpf_reg_state *regs = state->regs; |
1194 | struct bpf_reg_state *reg; | |
33ff9823 | 1195 | struct bpf_call_arg_meta meta; |
969bf05e | 1196 | bool changes_data; |
17a52670 AS |
1197 | int i, err; |
1198 | ||
1199 | /* find function prototype */ | |
1200 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
ebb676da | 1201 | verbose("invalid func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1202 | return -EINVAL; |
1203 | } | |
1204 | ||
1205 | if (env->prog->aux->ops->get_func_proto) | |
1206 | fn = env->prog->aux->ops->get_func_proto(func_id); | |
1207 | ||
1208 | if (!fn) { | |
ebb676da | 1209 | verbose("unknown func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1210 | return -EINVAL; |
1211 | } | |
1212 | ||
1213 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1214 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
17a52670 AS |
1215 | verbose("cannot call GPL only function from proprietary program\n"); |
1216 | return -EINVAL; | |
1217 | } | |
1218 | ||
17bedab2 | 1219 | changes_data = bpf_helper_changes_pkt_data(fn->func); |
969bf05e | 1220 | |
33ff9823 | 1221 | memset(&meta, 0, sizeof(meta)); |
36bbef52 | 1222 | meta.pkt_access = fn->pkt_access; |
33ff9823 | 1223 | |
435faee1 DB |
1224 | /* We only support one arg being in raw mode at the moment, which |
1225 | * is sufficient for the helper functions we have right now. | |
1226 | */ | |
1227 | err = check_raw_mode(fn); | |
1228 | if (err) { | |
ebb676da TG |
1229 | verbose("kernel subsystem misconfigured func %s#%d\n", |
1230 | func_id_name(func_id), func_id); | |
435faee1 DB |
1231 | return err; |
1232 | } | |
1233 | ||
17a52670 | 1234 | /* check args */ |
33ff9823 | 1235 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1236 | if (err) |
1237 | return err; | |
33ff9823 | 1238 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1239 | if (err) |
1240 | return err; | |
33ff9823 | 1241 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1242 | if (err) |
1243 | return err; | |
33ff9823 | 1244 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1245 | if (err) |
1246 | return err; | |
33ff9823 | 1247 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1248 | if (err) |
1249 | return err; | |
1250 | ||
435faee1 DB |
1251 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1252 | * is inferred from register state. | |
1253 | */ | |
1254 | for (i = 0; i < meta.access_size; i++) { | |
1255 | err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); | |
1256 | if (err) | |
1257 | return err; | |
1258 | } | |
1259 | ||
17a52670 AS |
1260 | /* reset caller saved regs */ |
1261 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
1262 | reg = regs + caller_saved[i]; | |
1263 | reg->type = NOT_INIT; | |
1264 | reg->imm = 0; | |
1265 | } | |
1266 | ||
1267 | /* update return register */ | |
1268 | if (fn->ret_type == RET_INTEGER) { | |
1269 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1270 | } else if (fn->ret_type == RET_VOID) { | |
1271 | regs[BPF_REG_0].type = NOT_INIT; | |
1272 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
1273 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; | |
48461135 | 1274 | regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0; |
17a52670 AS |
1275 | /* remember map_ptr, so that check_map_access() |
1276 | * can check 'value_size' boundary of memory access | |
1277 | * to map element returned from bpf_map_lookup_elem() | |
1278 | */ | |
33ff9823 | 1279 | if (meta.map_ptr == NULL) { |
17a52670 AS |
1280 | verbose("kernel subsystem misconfigured verifier\n"); |
1281 | return -EINVAL; | |
1282 | } | |
33ff9823 | 1283 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
57a09bf0 | 1284 | regs[BPF_REG_0].id = ++env->id_gen; |
17a52670 | 1285 | } else { |
ebb676da TG |
1286 | verbose("unknown return type %d of func %s#%d\n", |
1287 | fn->ret_type, func_id_name(func_id), func_id); | |
17a52670 AS |
1288 | return -EINVAL; |
1289 | } | |
04fd61ab | 1290 | |
33ff9823 | 1291 | err = check_map_func_compatibility(meta.map_ptr, func_id); |
35578d79 KX |
1292 | if (err) |
1293 | return err; | |
04fd61ab | 1294 | |
969bf05e AS |
1295 | if (changes_data) |
1296 | clear_all_pkt_pointers(env); | |
1297 | return 0; | |
1298 | } | |
1299 | ||
58e2af8b JK |
1300 | static int check_packet_ptr_add(struct bpf_verifier_env *env, |
1301 | struct bpf_insn *insn) | |
969bf05e | 1302 | { |
58e2af8b JK |
1303 | struct bpf_reg_state *regs = env->cur_state.regs; |
1304 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
1305 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; | |
1306 | struct bpf_reg_state tmp_reg; | |
969bf05e AS |
1307 | s32 imm; |
1308 | ||
1309 | if (BPF_SRC(insn->code) == BPF_K) { | |
1310 | /* pkt_ptr += imm */ | |
1311 | imm = insn->imm; | |
1312 | ||
1313 | add_imm: | |
1314 | if (imm <= 0) { | |
1315 | verbose("addition of negative constant to packet pointer is not allowed\n"); | |
1316 | return -EACCES; | |
1317 | } | |
1318 | if (imm >= MAX_PACKET_OFF || | |
1319 | imm + dst_reg->off >= MAX_PACKET_OFF) { | |
1320 | verbose("constant %d is too large to add to packet pointer\n", | |
1321 | imm); | |
1322 | return -EACCES; | |
1323 | } | |
1324 | /* a constant was added to pkt_ptr. | |
1325 | * Remember it while keeping the same 'id' | |
1326 | */ | |
1327 | dst_reg->off += imm; | |
1328 | } else { | |
1b9b69ec AS |
1329 | if (src_reg->type == PTR_TO_PACKET) { |
1330 | /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ | |
1331 | tmp_reg = *dst_reg; /* save r7 state */ | |
1332 | *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ | |
1333 | src_reg = &tmp_reg; /* pretend it's src_reg state */ | |
1334 | /* if the checks below reject it, the copy won't matter, | |
1335 | * since we're rejecting the whole program. If all ok, | |
1336 | * then imm22 state will be added to r7 | |
1337 | * and r7 will be pkt(id=0,off=22,r=62) while | |
1338 | * r6 will stay as pkt(id=0,off=0,r=62) | |
1339 | */ | |
1340 | } | |
1341 | ||
969bf05e AS |
1342 | if (src_reg->type == CONST_IMM) { |
1343 | /* pkt_ptr += reg where reg is known constant */ | |
1344 | imm = src_reg->imm; | |
1345 | goto add_imm; | |
1346 | } | |
1347 | /* disallow pkt_ptr += reg | |
1348 | * if reg is not uknown_value with guaranteed zero upper bits | |
1349 | * otherwise pkt_ptr may overflow and addition will become | |
1350 | * subtraction which is not allowed | |
1351 | */ | |
1352 | if (src_reg->type != UNKNOWN_VALUE) { | |
1353 | verbose("cannot add '%s' to ptr_to_packet\n", | |
1354 | reg_type_str[src_reg->type]); | |
1355 | return -EACCES; | |
1356 | } | |
1357 | if (src_reg->imm < 48) { | |
1358 | verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", | |
1359 | src_reg->imm); | |
1360 | return -EACCES; | |
1361 | } | |
1362 | /* dst_reg stays as pkt_ptr type and since some positive | |
1363 | * integer value was added to the pointer, increment its 'id' | |
1364 | */ | |
1f415a74 | 1365 | dst_reg->id = ++env->id_gen; |
969bf05e AS |
1366 | |
1367 | /* something was added to pkt_ptr, set range and off to zero */ | |
1368 | dst_reg->off = 0; | |
1369 | dst_reg->range = 0; | |
1370 | } | |
1371 | return 0; | |
1372 | } | |
1373 | ||
58e2af8b | 1374 | static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) |
969bf05e | 1375 | { |
58e2af8b JK |
1376 | struct bpf_reg_state *regs = env->cur_state.regs; |
1377 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
969bf05e AS |
1378 | u8 opcode = BPF_OP(insn->code); |
1379 | s64 imm_log2; | |
1380 | ||
1381 | /* for type == UNKNOWN_VALUE: | |
1382 | * imm > 0 -> number of zero upper bits | |
1383 | * imm == 0 -> don't track which is the same as all bits can be non-zero | |
1384 | */ | |
1385 | ||
1386 | if (BPF_SRC(insn->code) == BPF_X) { | |
58e2af8b | 1387 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; |
969bf05e AS |
1388 | |
1389 | if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && | |
1390 | dst_reg->imm && opcode == BPF_ADD) { | |
1391 | /* dreg += sreg | |
1392 | * where both have zero upper bits. Adding them | |
1393 | * can only result making one more bit non-zero | |
1394 | * in the larger value. | |
1395 | * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) | |
1396 | * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) | |
1397 | */ | |
1398 | dst_reg->imm = min(dst_reg->imm, src_reg->imm); | |
1399 | dst_reg->imm--; | |
1400 | return 0; | |
1401 | } | |
1402 | if (src_reg->type == CONST_IMM && src_reg->imm > 0 && | |
1403 | dst_reg->imm && opcode == BPF_ADD) { | |
1404 | /* dreg += sreg | |
1405 | * where dreg has zero upper bits and sreg is const. | |
1406 | * Adding them can only result making one more bit | |
1407 | * non-zero in the larger value. | |
1408 | */ | |
1409 | imm_log2 = __ilog2_u64((long long)src_reg->imm); | |
1410 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1411 | dst_reg->imm--; | |
1412 | return 0; | |
1413 | } | |
1414 | /* all other cases non supported yet, just mark dst_reg */ | |
1415 | dst_reg->imm = 0; | |
1416 | return 0; | |
1417 | } | |
1418 | ||
1419 | /* sign extend 32-bit imm into 64-bit to make sure that | |
1420 | * negative values occupy bit 63. Note ilog2() would have | |
1421 | * been incorrect, since sizeof(insn->imm) == 4 | |
1422 | */ | |
1423 | imm_log2 = __ilog2_u64((long long)insn->imm); | |
1424 | ||
1425 | if (dst_reg->imm && opcode == BPF_LSH) { | |
1426 | /* reg <<= imm | |
1427 | * if reg was a result of 2 byte load, then its imm == 48 | |
1428 | * which means that upper 48 bits are zero and shifting this reg | |
1429 | * left by 4 would mean that upper 44 bits are still zero | |
1430 | */ | |
1431 | dst_reg->imm -= insn->imm; | |
1432 | } else if (dst_reg->imm && opcode == BPF_MUL) { | |
1433 | /* reg *= imm | |
1434 | * if multiplying by 14 subtract 4 | |
1435 | * This is conservative calculation of upper zero bits. | |
1436 | * It's not trying to special case insn->imm == 1 or 0 cases | |
1437 | */ | |
1438 | dst_reg->imm -= imm_log2 + 1; | |
1439 | } else if (opcode == BPF_AND) { | |
1440 | /* reg &= imm */ | |
1441 | dst_reg->imm = 63 - imm_log2; | |
1442 | } else if (dst_reg->imm && opcode == BPF_ADD) { | |
1443 | /* reg += imm */ | |
1444 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1445 | dst_reg->imm--; | |
1446 | } else if (opcode == BPF_RSH) { | |
1447 | /* reg >>= imm | |
1448 | * which means that after right shift, upper bits will be zero | |
1449 | * note that verifier already checked that | |
1450 | * 0 <= imm < 64 for shift insn | |
1451 | */ | |
1452 | dst_reg->imm += insn->imm; | |
1453 | if (unlikely(dst_reg->imm > 64)) | |
1454 | /* some dumb code did: | |
1455 | * r2 = *(u32 *)mem; | |
1456 | * r2 >>= 32; | |
1457 | * and all bits are zero now */ | |
1458 | dst_reg->imm = 64; | |
1459 | } else { | |
1460 | /* all other alu ops, means that we don't know what will | |
1461 | * happen to the value, mark it with unknown number of zero bits | |
1462 | */ | |
1463 | dst_reg->imm = 0; | |
1464 | } | |
1465 | ||
1466 | if (dst_reg->imm < 0) { | |
1467 | /* all 64 bits of the register can contain non-zero bits | |
1468 | * and such value cannot be added to ptr_to_packet, since it | |
1469 | * may overflow, mark it as unknown to avoid further eval | |
1470 | */ | |
1471 | dst_reg->imm = 0; | |
1472 | } | |
1473 | return 0; | |
1474 | } | |
1475 | ||
58e2af8b JK |
1476 | static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, |
1477 | struct bpf_insn *insn) | |
969bf05e | 1478 | { |
58e2af8b JK |
1479 | struct bpf_reg_state *regs = env->cur_state.regs; |
1480 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
1481 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; | |
969bf05e AS |
1482 | u8 opcode = BPF_OP(insn->code); |
1483 | ||
3c839744 GB |
1484 | /* dst_reg->type == CONST_IMM here, simulate execution of 'add'/'or' |
1485 | * insn. Don't care about overflow or negative values, just add them | |
969bf05e AS |
1486 | */ |
1487 | if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) | |
1488 | dst_reg->imm += insn->imm; | |
1489 | else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && | |
1490 | src_reg->type == CONST_IMM) | |
1491 | dst_reg->imm += src_reg->imm; | |
3c839744 GB |
1492 | else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) |
1493 | dst_reg->imm |= insn->imm; | |
1494 | else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X && | |
1495 | src_reg->type == CONST_IMM) | |
1496 | dst_reg->imm |= src_reg->imm; | |
969bf05e AS |
1497 | else |
1498 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1499 | return 0; |
1500 | } | |
1501 | ||
48461135 JB |
1502 | static void check_reg_overflow(struct bpf_reg_state *reg) |
1503 | { | |
1504 | if (reg->max_value > BPF_REGISTER_MAX_RANGE) | |
1505 | reg->max_value = BPF_REGISTER_MAX_RANGE; | |
f23cc643 JB |
1506 | if (reg->min_value < BPF_REGISTER_MIN_RANGE || |
1507 | reg->min_value > BPF_REGISTER_MAX_RANGE) | |
48461135 JB |
1508 | reg->min_value = BPF_REGISTER_MIN_RANGE; |
1509 | } | |
1510 | ||
1511 | static void adjust_reg_min_max_vals(struct bpf_verifier_env *env, | |
1512 | struct bpf_insn *insn) | |
1513 | { | |
1514 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; | |
f23cc643 JB |
1515 | s64 min_val = BPF_REGISTER_MIN_RANGE; |
1516 | u64 max_val = BPF_REGISTER_MAX_RANGE; | |
48461135 JB |
1517 | u8 opcode = BPF_OP(insn->code); |
1518 | ||
1519 | dst_reg = ®s[insn->dst_reg]; | |
1520 | if (BPF_SRC(insn->code) == BPF_X) { | |
1521 | check_reg_overflow(®s[insn->src_reg]); | |
1522 | min_val = regs[insn->src_reg].min_value; | |
1523 | max_val = regs[insn->src_reg].max_value; | |
1524 | ||
1525 | /* If the source register is a random pointer then the | |
1526 | * min_value/max_value values represent the range of the known | |
1527 | * accesses into that value, not the actual min/max value of the | |
1528 | * register itself. In this case we have to reset the reg range | |
1529 | * values so we know it is not safe to look at. | |
1530 | */ | |
1531 | if (regs[insn->src_reg].type != CONST_IMM && | |
1532 | regs[insn->src_reg].type != UNKNOWN_VALUE) { | |
1533 | min_val = BPF_REGISTER_MIN_RANGE; | |
1534 | max_val = BPF_REGISTER_MAX_RANGE; | |
1535 | } | |
1536 | } else if (insn->imm < BPF_REGISTER_MAX_RANGE && | |
1537 | (s64)insn->imm > BPF_REGISTER_MIN_RANGE) { | |
1538 | min_val = max_val = insn->imm; | |
48461135 JB |
1539 | } |
1540 | ||
1541 | /* We don't know anything about what was done to this register, mark it | |
1542 | * as unknown. | |
1543 | */ | |
1544 | if (min_val == BPF_REGISTER_MIN_RANGE && | |
1545 | max_val == BPF_REGISTER_MAX_RANGE) { | |
1546 | reset_reg_range_values(regs, insn->dst_reg); | |
1547 | return; | |
1548 | } | |
1549 | ||
f23cc643 JB |
1550 | /* If one of our values was at the end of our ranges then we can't just |
1551 | * do our normal operations to the register, we need to set the values | |
1552 | * to the min/max since they are undefined. | |
1553 | */ | |
1554 | if (min_val == BPF_REGISTER_MIN_RANGE) | |
1555 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
1556 | if (max_val == BPF_REGISTER_MAX_RANGE) | |
1557 | dst_reg->max_value = BPF_REGISTER_MAX_RANGE; | |
1558 | ||
48461135 JB |
1559 | switch (opcode) { |
1560 | case BPF_ADD: | |
f23cc643 JB |
1561 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1562 | dst_reg->min_value += min_val; | |
1563 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1564 | dst_reg->max_value += max_val; | |
48461135 JB |
1565 | break; |
1566 | case BPF_SUB: | |
f23cc643 JB |
1567 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1568 | dst_reg->min_value -= min_val; | |
1569 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1570 | dst_reg->max_value -= max_val; | |
48461135 JB |
1571 | break; |
1572 | case BPF_MUL: | |
f23cc643 JB |
1573 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1574 | dst_reg->min_value *= min_val; | |
1575 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1576 | dst_reg->max_value *= max_val; | |
48461135 JB |
1577 | break; |
1578 | case BPF_AND: | |
f23cc643 JB |
1579 | /* Disallow AND'ing of negative numbers, ain't nobody got time |
1580 | * for that. Otherwise the minimum is 0 and the max is the max | |
1581 | * value we could AND against. | |
1582 | */ | |
1583 | if (min_val < 0) | |
1584 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
1585 | else | |
1586 | dst_reg->min_value = 0; | |
48461135 JB |
1587 | dst_reg->max_value = max_val; |
1588 | break; | |
1589 | case BPF_LSH: | |
1590 | /* Gotta have special overflow logic here, if we're shifting | |
1591 | * more than MAX_RANGE then just assume we have an invalid | |
1592 | * range. | |
1593 | */ | |
1594 | if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) | |
1595 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
f23cc643 | 1596 | else if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
48461135 JB |
1597 | dst_reg->min_value <<= min_val; |
1598 | ||
1599 | if (max_val > ilog2(BPF_REGISTER_MAX_RANGE)) | |
1600 | dst_reg->max_value = BPF_REGISTER_MAX_RANGE; | |
f23cc643 | 1601 | else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) |
48461135 JB |
1602 | dst_reg->max_value <<= max_val; |
1603 | break; | |
1604 | case BPF_RSH: | |
f23cc643 JB |
1605 | /* RSH by a negative number is undefined, and the BPF_RSH is an |
1606 | * unsigned shift, so make the appropriate casts. | |
48461135 | 1607 | */ |
f23cc643 JB |
1608 | if (min_val < 0 || dst_reg->min_value < 0) |
1609 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
1610 | else | |
1611 | dst_reg->min_value = | |
1612 | (u64)(dst_reg->min_value) >> min_val; | |
1613 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1614 | dst_reg->max_value >>= max_val; | |
48461135 JB |
1615 | break; |
1616 | default: | |
1617 | reset_reg_range_values(regs, insn->dst_reg); | |
1618 | break; | |
1619 | } | |
1620 | ||
1621 | check_reg_overflow(dst_reg); | |
1622 | } | |
1623 | ||
17a52670 | 1624 | /* check validity of 32-bit and 64-bit arithmetic operations */ |
58e2af8b | 1625 | static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 1626 | { |
58e2af8b | 1627 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1628 | u8 opcode = BPF_OP(insn->code); |
1629 | int err; | |
1630 | ||
1631 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
1632 | if (opcode == BPF_NEG) { | |
1633 | if (BPF_SRC(insn->code) != 0 || | |
1634 | insn->src_reg != BPF_REG_0 || | |
1635 | insn->off != 0 || insn->imm != 0) { | |
1636 | verbose("BPF_NEG uses reserved fields\n"); | |
1637 | return -EINVAL; | |
1638 | } | |
1639 | } else { | |
1640 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
1641 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { | |
1642 | verbose("BPF_END uses reserved fields\n"); | |
1643 | return -EINVAL; | |
1644 | } | |
1645 | } | |
1646 | ||
1647 | /* check src operand */ | |
1648 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1649 | if (err) | |
1650 | return err; | |
1651 | ||
1be7f75d AS |
1652 | if (is_pointer_value(env, insn->dst_reg)) { |
1653 | verbose("R%d pointer arithmetic prohibited\n", | |
1654 | insn->dst_reg); | |
1655 | return -EACCES; | |
1656 | } | |
1657 | ||
17a52670 AS |
1658 | /* check dest operand */ |
1659 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1660 | if (err) | |
1661 | return err; | |
1662 | ||
1663 | } else if (opcode == BPF_MOV) { | |
1664 | ||
1665 | if (BPF_SRC(insn->code) == BPF_X) { | |
1666 | if (insn->imm != 0 || insn->off != 0) { | |
1667 | verbose("BPF_MOV uses reserved fields\n"); | |
1668 | return -EINVAL; | |
1669 | } | |
1670 | ||
1671 | /* check src operand */ | |
1672 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1673 | if (err) | |
1674 | return err; | |
1675 | } else { | |
1676 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1677 | verbose("BPF_MOV uses reserved fields\n"); | |
1678 | return -EINVAL; | |
1679 | } | |
1680 | } | |
1681 | ||
1682 | /* check dest operand */ | |
1683 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1684 | if (err) | |
1685 | return err; | |
1686 | ||
48461135 JB |
1687 | /* we are setting our register to something new, we need to |
1688 | * reset its range values. | |
1689 | */ | |
1690 | reset_reg_range_values(regs, insn->dst_reg); | |
1691 | ||
17a52670 AS |
1692 | if (BPF_SRC(insn->code) == BPF_X) { |
1693 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
1694 | /* case: R1 = R2 | |
1695 | * copy register state to dest reg | |
1696 | */ | |
1697 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
1698 | } else { | |
1be7f75d AS |
1699 | if (is_pointer_value(env, insn->src_reg)) { |
1700 | verbose("R%d partial copy of pointer\n", | |
1701 | insn->src_reg); | |
1702 | return -EACCES; | |
1703 | } | |
57a09bf0 | 1704 | mark_reg_unknown_value(regs, insn->dst_reg); |
17a52670 AS |
1705 | } |
1706 | } else { | |
1707 | /* case: R = imm | |
1708 | * remember the value we stored into this reg | |
1709 | */ | |
1710 | regs[insn->dst_reg].type = CONST_IMM; | |
1711 | regs[insn->dst_reg].imm = insn->imm; | |
48461135 JB |
1712 | regs[insn->dst_reg].max_value = insn->imm; |
1713 | regs[insn->dst_reg].min_value = insn->imm; | |
17a52670 AS |
1714 | } |
1715 | ||
1716 | } else if (opcode > BPF_END) { | |
1717 | verbose("invalid BPF_ALU opcode %x\n", opcode); | |
1718 | return -EINVAL; | |
1719 | ||
1720 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
1721 | ||
17a52670 AS |
1722 | if (BPF_SRC(insn->code) == BPF_X) { |
1723 | if (insn->imm != 0 || insn->off != 0) { | |
1724 | verbose("BPF_ALU uses reserved fields\n"); | |
1725 | return -EINVAL; | |
1726 | } | |
1727 | /* check src1 operand */ | |
1728 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1729 | if (err) | |
1730 | return err; | |
1731 | } else { | |
1732 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1733 | verbose("BPF_ALU uses reserved fields\n"); | |
1734 | return -EINVAL; | |
1735 | } | |
1736 | } | |
1737 | ||
1738 | /* check src2 operand */ | |
1739 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1740 | if (err) | |
1741 | return err; | |
1742 | ||
1743 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
1744 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
1745 | verbose("div by zero\n"); | |
1746 | return -EINVAL; | |
1747 | } | |
1748 | ||
229394e8 RV |
1749 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
1750 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
1751 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
1752 | ||
1753 | if (insn->imm < 0 || insn->imm >= size) { | |
1754 | verbose("invalid shift %d\n", insn->imm); | |
1755 | return -EINVAL; | |
1756 | } | |
1757 | } | |
1758 | ||
1a0dc1ac AS |
1759 | /* check dest operand */ |
1760 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
1761 | if (err) | |
1762 | return err; | |
1763 | ||
1764 | dst_reg = ®s[insn->dst_reg]; | |
1765 | ||
48461135 JB |
1766 | /* first we want to adjust our ranges. */ |
1767 | adjust_reg_min_max_vals(env, insn); | |
1768 | ||
17a52670 AS |
1769 | /* pattern match 'bpf_add Rx, imm' instruction */ |
1770 | if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && | |
1a0dc1ac AS |
1771 | dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { |
1772 | dst_reg->type = PTR_TO_STACK; | |
1773 | dst_reg->imm = insn->imm; | |
1774 | return 0; | |
969bf05e AS |
1775 | } else if (opcode == BPF_ADD && |
1776 | BPF_CLASS(insn->code) == BPF_ALU64 && | |
1b9b69ec AS |
1777 | (dst_reg->type == PTR_TO_PACKET || |
1778 | (BPF_SRC(insn->code) == BPF_X && | |
1779 | regs[insn->src_reg].type == PTR_TO_PACKET))) { | |
969bf05e AS |
1780 | /* ptr_to_packet += K|X */ |
1781 | return check_packet_ptr_add(env, insn); | |
1782 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1783 | dst_reg->type == UNKNOWN_VALUE && | |
1784 | env->allow_ptr_leaks) { | |
1785 | /* unknown += K|X */ | |
1786 | return evaluate_reg_alu(env, insn); | |
1787 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1788 | dst_reg->type == CONST_IMM && | |
1789 | env->allow_ptr_leaks) { | |
1790 | /* reg_imm += K|X */ | |
1791 | return evaluate_reg_imm_alu(env, insn); | |
1be7f75d AS |
1792 | } else if (is_pointer_value(env, insn->dst_reg)) { |
1793 | verbose("R%d pointer arithmetic prohibited\n", | |
1794 | insn->dst_reg); | |
1795 | return -EACCES; | |
1796 | } else if (BPF_SRC(insn->code) == BPF_X && | |
1797 | is_pointer_value(env, insn->src_reg)) { | |
1798 | verbose("R%d pointer arithmetic prohibited\n", | |
1799 | insn->src_reg); | |
1800 | return -EACCES; | |
1801 | } | |
17a52670 | 1802 | |
48461135 JB |
1803 | /* If we did pointer math on a map value then just set it to our |
1804 | * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or | |
1805 | * loads to this register appropriately, otherwise just mark the | |
1806 | * register as unknown. | |
1807 | */ | |
1808 | if (env->allow_ptr_leaks && | |
1809 | (dst_reg->type == PTR_TO_MAP_VALUE || | |
1810 | dst_reg->type == PTR_TO_MAP_VALUE_ADJ)) | |
1811 | dst_reg->type = PTR_TO_MAP_VALUE_ADJ; | |
1812 | else | |
1813 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1814 | } |
1815 | ||
1816 | return 0; | |
1817 | } | |
1818 | ||
58e2af8b JK |
1819 | static void find_good_pkt_pointers(struct bpf_verifier_state *state, |
1820 | struct bpf_reg_state *dst_reg) | |
969bf05e | 1821 | { |
58e2af8b | 1822 | struct bpf_reg_state *regs = state->regs, *reg; |
969bf05e | 1823 | int i; |
2d2be8ca DB |
1824 | |
1825 | /* LLVM can generate two kind of checks: | |
1826 | * | |
1827 | * Type 1: | |
1828 | * | |
1829 | * r2 = r3; | |
1830 | * r2 += 8; | |
1831 | * if (r2 > pkt_end) goto <handle exception> | |
1832 | * <access okay> | |
1833 | * | |
1834 | * Where: | |
1835 | * r2 == dst_reg, pkt_end == src_reg | |
1836 | * r2=pkt(id=n,off=8,r=0) | |
1837 | * r3=pkt(id=n,off=0,r=0) | |
1838 | * | |
1839 | * Type 2: | |
1840 | * | |
1841 | * r2 = r3; | |
1842 | * r2 += 8; | |
1843 | * if (pkt_end >= r2) goto <access okay> | |
1844 | * <handle exception> | |
1845 | * | |
1846 | * Where: | |
1847 | * pkt_end == dst_reg, r2 == src_reg | |
1848 | * r2=pkt(id=n,off=8,r=0) | |
1849 | * r3=pkt(id=n,off=0,r=0) | |
1850 | * | |
1851 | * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
1852 | * so that range of bytes [r3, r3 + 8) is safe to access. | |
969bf05e | 1853 | */ |
2d2be8ca | 1854 | |
969bf05e AS |
1855 | for (i = 0; i < MAX_BPF_REG; i++) |
1856 | if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) | |
1857 | regs[i].range = dst_reg->off; | |
1858 | ||
1859 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1860 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1861 | continue; | |
1862 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1863 | if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) | |
1864 | reg->range = dst_reg->off; | |
1865 | } | |
1866 | } | |
1867 | ||
48461135 JB |
1868 | /* Adjusts the register min/max values in the case that the dst_reg is the |
1869 | * variable register that we are working on, and src_reg is a constant or we're | |
1870 | * simply doing a BPF_K check. | |
1871 | */ | |
1872 | static void reg_set_min_max(struct bpf_reg_state *true_reg, | |
1873 | struct bpf_reg_state *false_reg, u64 val, | |
1874 | u8 opcode) | |
1875 | { | |
1876 | switch (opcode) { | |
1877 | case BPF_JEQ: | |
1878 | /* If this is false then we know nothing Jon Snow, but if it is | |
1879 | * true then we know for sure. | |
1880 | */ | |
1881 | true_reg->max_value = true_reg->min_value = val; | |
1882 | break; | |
1883 | case BPF_JNE: | |
1884 | /* If this is true we know nothing Jon Snow, but if it is false | |
1885 | * we know the value for sure; | |
1886 | */ | |
1887 | false_reg->max_value = false_reg->min_value = val; | |
1888 | break; | |
1889 | case BPF_JGT: | |
1890 | /* Unsigned comparison, the minimum value is 0. */ | |
1891 | false_reg->min_value = 0; | |
1892 | case BPF_JSGT: | |
1893 | /* If this is false then we know the maximum val is val, | |
1894 | * otherwise we know the min val is val+1. | |
1895 | */ | |
1896 | false_reg->max_value = val; | |
1897 | true_reg->min_value = val + 1; | |
1898 | break; | |
1899 | case BPF_JGE: | |
1900 | /* Unsigned comparison, the minimum value is 0. */ | |
1901 | false_reg->min_value = 0; | |
1902 | case BPF_JSGE: | |
1903 | /* If this is false then we know the maximum value is val - 1, | |
1904 | * otherwise we know the mimimum value is val. | |
1905 | */ | |
1906 | false_reg->max_value = val - 1; | |
1907 | true_reg->min_value = val; | |
1908 | break; | |
1909 | default: | |
1910 | break; | |
1911 | } | |
1912 | ||
1913 | check_reg_overflow(false_reg); | |
1914 | check_reg_overflow(true_reg); | |
1915 | } | |
1916 | ||
1917 | /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg | |
1918 | * is the variable reg. | |
1919 | */ | |
1920 | static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, | |
1921 | struct bpf_reg_state *false_reg, u64 val, | |
1922 | u8 opcode) | |
1923 | { | |
1924 | switch (opcode) { | |
1925 | case BPF_JEQ: | |
1926 | /* If this is false then we know nothing Jon Snow, but if it is | |
1927 | * true then we know for sure. | |
1928 | */ | |
1929 | true_reg->max_value = true_reg->min_value = val; | |
1930 | break; | |
1931 | case BPF_JNE: | |
1932 | /* If this is true we know nothing Jon Snow, but if it is false | |
1933 | * we know the value for sure; | |
1934 | */ | |
1935 | false_reg->max_value = false_reg->min_value = val; | |
1936 | break; | |
1937 | case BPF_JGT: | |
1938 | /* Unsigned comparison, the minimum value is 0. */ | |
1939 | true_reg->min_value = 0; | |
1940 | case BPF_JSGT: | |
1941 | /* | |
1942 | * If this is false, then the val is <= the register, if it is | |
1943 | * true the register <= to the val. | |
1944 | */ | |
1945 | false_reg->min_value = val; | |
1946 | true_reg->max_value = val - 1; | |
1947 | break; | |
1948 | case BPF_JGE: | |
1949 | /* Unsigned comparison, the minimum value is 0. */ | |
1950 | true_reg->min_value = 0; | |
1951 | case BPF_JSGE: | |
1952 | /* If this is false then constant < register, if it is true then | |
1953 | * the register < constant. | |
1954 | */ | |
1955 | false_reg->min_value = val + 1; | |
1956 | true_reg->max_value = val; | |
1957 | break; | |
1958 | default: | |
1959 | break; | |
1960 | } | |
1961 | ||
1962 | check_reg_overflow(false_reg); | |
1963 | check_reg_overflow(true_reg); | |
1964 | } | |
1965 | ||
57a09bf0 TG |
1966 | static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, |
1967 | enum bpf_reg_type type) | |
1968 | { | |
1969 | struct bpf_reg_state *reg = ®s[regno]; | |
1970 | ||
1971 | if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { | |
1972 | reg->type = type; | |
1973 | if (type == UNKNOWN_VALUE) | |
1974 | mark_reg_unknown_value(regs, regno); | |
1975 | } | |
1976 | } | |
1977 | ||
1978 | /* The logic is similar to find_good_pkt_pointers(), both could eventually | |
1979 | * be folded together at some point. | |
1980 | */ | |
1981 | static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, | |
1982 | enum bpf_reg_type type) | |
1983 | { | |
1984 | struct bpf_reg_state *regs = state->regs; | |
1985 | int i; | |
1986 | ||
1987 | for (i = 0; i < MAX_BPF_REG; i++) | |
1988 | mark_map_reg(regs, i, regs[regno].id, type); | |
1989 | ||
1990 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1991 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1992 | continue; | |
1993 | mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, | |
1994 | regs[regno].id, type); | |
1995 | } | |
1996 | } | |
1997 | ||
58e2af8b | 1998 | static int check_cond_jmp_op(struct bpf_verifier_env *env, |
17a52670 AS |
1999 | struct bpf_insn *insn, int *insn_idx) |
2000 | { | |
58e2af8b JK |
2001 | struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; |
2002 | struct bpf_reg_state *regs = this_branch->regs, *dst_reg; | |
17a52670 AS |
2003 | u8 opcode = BPF_OP(insn->code); |
2004 | int err; | |
2005 | ||
2006 | if (opcode > BPF_EXIT) { | |
2007 | verbose("invalid BPF_JMP opcode %x\n", opcode); | |
2008 | return -EINVAL; | |
2009 | } | |
2010 | ||
2011 | if (BPF_SRC(insn->code) == BPF_X) { | |
2012 | if (insn->imm != 0) { | |
2013 | verbose("BPF_JMP uses reserved fields\n"); | |
2014 | return -EINVAL; | |
2015 | } | |
2016 | ||
2017 | /* check src1 operand */ | |
2018 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2019 | if (err) | |
2020 | return err; | |
1be7f75d AS |
2021 | |
2022 | if (is_pointer_value(env, insn->src_reg)) { | |
2023 | verbose("R%d pointer comparison prohibited\n", | |
2024 | insn->src_reg); | |
2025 | return -EACCES; | |
2026 | } | |
17a52670 AS |
2027 | } else { |
2028 | if (insn->src_reg != BPF_REG_0) { | |
2029 | verbose("BPF_JMP uses reserved fields\n"); | |
2030 | return -EINVAL; | |
2031 | } | |
2032 | } | |
2033 | ||
2034 | /* check src2 operand */ | |
2035 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2036 | if (err) | |
2037 | return err; | |
2038 | ||
1a0dc1ac AS |
2039 | dst_reg = ®s[insn->dst_reg]; |
2040 | ||
17a52670 AS |
2041 | /* detect if R == 0 where R was initialized to zero earlier */ |
2042 | if (BPF_SRC(insn->code) == BPF_K && | |
2043 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
1a0dc1ac | 2044 | dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { |
17a52670 AS |
2045 | if (opcode == BPF_JEQ) { |
2046 | /* if (imm == imm) goto pc+off; | |
2047 | * only follow the goto, ignore fall-through | |
2048 | */ | |
2049 | *insn_idx += insn->off; | |
2050 | return 0; | |
2051 | } else { | |
2052 | /* if (imm != imm) goto pc+off; | |
2053 | * only follow fall-through branch, since | |
2054 | * that's where the program will go | |
2055 | */ | |
2056 | return 0; | |
2057 | } | |
2058 | } | |
2059 | ||
2060 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
2061 | if (!other_branch) | |
2062 | return -EFAULT; | |
2063 | ||
48461135 JB |
2064 | /* detect if we are comparing against a constant value so we can adjust |
2065 | * our min/max values for our dst register. | |
2066 | */ | |
2067 | if (BPF_SRC(insn->code) == BPF_X) { | |
2068 | if (regs[insn->src_reg].type == CONST_IMM) | |
2069 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2070 | dst_reg, regs[insn->src_reg].imm, | |
2071 | opcode); | |
2072 | else if (dst_reg->type == CONST_IMM) | |
2073 | reg_set_min_max_inv(&other_branch->regs[insn->src_reg], | |
2074 | ®s[insn->src_reg], dst_reg->imm, | |
2075 | opcode); | |
2076 | } else { | |
2077 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2078 | dst_reg, insn->imm, opcode); | |
2079 | } | |
2080 | ||
58e2af8b | 2081 | /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ |
17a52670 | 2082 | if (BPF_SRC(insn->code) == BPF_K && |
1a0dc1ac AS |
2083 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
2084 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
57a09bf0 TG |
2085 | /* Mark all identical map registers in each branch as either |
2086 | * safe or unknown depending R == 0 or R != 0 conditional. | |
2087 | */ | |
2088 | mark_map_regs(this_branch, insn->dst_reg, | |
2089 | opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE); | |
2090 | mark_map_regs(other_branch, insn->dst_reg, | |
2091 | opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE); | |
969bf05e AS |
2092 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
2093 | dst_reg->type == PTR_TO_PACKET && | |
2094 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
2d2be8ca DB |
2095 | find_good_pkt_pointers(this_branch, dst_reg); |
2096 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && | |
2097 | dst_reg->type == PTR_TO_PACKET_END && | |
2098 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
2099 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg]); | |
1be7f75d AS |
2100 | } else if (is_pointer_value(env, insn->dst_reg)) { |
2101 | verbose("R%d pointer comparison prohibited\n", insn->dst_reg); | |
2102 | return -EACCES; | |
17a52670 AS |
2103 | } |
2104 | if (log_level) | |
2d2be8ca | 2105 | print_verifier_state(this_branch); |
17a52670 AS |
2106 | return 0; |
2107 | } | |
2108 | ||
0246e64d AS |
2109 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
2110 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
2111 | { | |
2112 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
2113 | ||
2114 | return (struct bpf_map *) (unsigned long) imm64; | |
2115 | } | |
2116 | ||
17a52670 | 2117 | /* verify BPF_LD_IMM64 instruction */ |
58e2af8b | 2118 | static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2119 | { |
58e2af8b | 2120 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2121 | int err; |
2122 | ||
2123 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
2124 | verbose("invalid BPF_LD_IMM insn\n"); | |
2125 | return -EINVAL; | |
2126 | } | |
2127 | if (insn->off != 0) { | |
2128 | verbose("BPF_LD_IMM64 uses reserved fields\n"); | |
2129 | return -EINVAL; | |
2130 | } | |
2131 | ||
2132 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
2133 | if (err) | |
2134 | return err; | |
2135 | ||
6b173873 JK |
2136 | if (insn->src_reg == 0) { |
2137 | /* generic move 64-bit immediate into a register, | |
2138 | * only analyzer needs to collect the ld_imm value. | |
2139 | */ | |
2140 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; | |
2141 | ||
2142 | if (!env->analyzer_ops) | |
2143 | return 0; | |
2144 | ||
2145 | regs[insn->dst_reg].type = CONST_IMM; | |
2146 | regs[insn->dst_reg].imm = imm; | |
17a52670 | 2147 | return 0; |
6b173873 | 2148 | } |
17a52670 AS |
2149 | |
2150 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
2151 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
2152 | ||
2153 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
2154 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
2155 | return 0; | |
2156 | } | |
2157 | ||
96be4325 DB |
2158 | static bool may_access_skb(enum bpf_prog_type type) |
2159 | { | |
2160 | switch (type) { | |
2161 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
2162 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 2163 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
2164 | return true; |
2165 | default: | |
2166 | return false; | |
2167 | } | |
2168 | } | |
2169 | ||
ddd872bc AS |
2170 | /* verify safety of LD_ABS|LD_IND instructions: |
2171 | * - they can only appear in the programs where ctx == skb | |
2172 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
2173 | * preserve R6-R9, and store return value into R0 | |
2174 | * | |
2175 | * Implicit input: | |
2176 | * ctx == skb == R6 == CTX | |
2177 | * | |
2178 | * Explicit input: | |
2179 | * SRC == any register | |
2180 | * IMM == 32-bit immediate | |
2181 | * | |
2182 | * Output: | |
2183 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
2184 | */ | |
58e2af8b | 2185 | static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) |
ddd872bc | 2186 | { |
58e2af8b | 2187 | struct bpf_reg_state *regs = env->cur_state.regs; |
ddd872bc | 2188 | u8 mode = BPF_MODE(insn->code); |
58e2af8b | 2189 | struct bpf_reg_state *reg; |
ddd872bc AS |
2190 | int i, err; |
2191 | ||
24701ece | 2192 | if (!may_access_skb(env->prog->type)) { |
1a0dc1ac | 2193 | verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
2194 | return -EINVAL; |
2195 | } | |
2196 | ||
2197 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 2198 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 2199 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
1a0dc1ac | 2200 | verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
2201 | return -EINVAL; |
2202 | } | |
2203 | ||
2204 | /* check whether implicit source operand (register R6) is readable */ | |
2205 | err = check_reg_arg(regs, BPF_REG_6, SRC_OP); | |
2206 | if (err) | |
2207 | return err; | |
2208 | ||
2209 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
2210 | verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
2211 | return -EINVAL; | |
2212 | } | |
2213 | ||
2214 | if (mode == BPF_IND) { | |
2215 | /* check explicit source operand */ | |
2216 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2217 | if (err) | |
2218 | return err; | |
2219 | } | |
2220 | ||
2221 | /* reset caller saved regs to unreadable */ | |
2222 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
2223 | reg = regs + caller_saved[i]; | |
2224 | reg->type = NOT_INIT; | |
2225 | reg->imm = 0; | |
2226 | } | |
2227 | ||
2228 | /* mark destination R0 register as readable, since it contains | |
2229 | * the value fetched from the packet | |
2230 | */ | |
2231 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
2232 | return 0; | |
2233 | } | |
2234 | ||
475fb78f AS |
2235 | /* non-recursive DFS pseudo code |
2236 | * 1 procedure DFS-iterative(G,v): | |
2237 | * 2 label v as discovered | |
2238 | * 3 let S be a stack | |
2239 | * 4 S.push(v) | |
2240 | * 5 while S is not empty | |
2241 | * 6 t <- S.pop() | |
2242 | * 7 if t is what we're looking for: | |
2243 | * 8 return t | |
2244 | * 9 for all edges e in G.adjacentEdges(t) do | |
2245 | * 10 if edge e is already labelled | |
2246 | * 11 continue with the next edge | |
2247 | * 12 w <- G.adjacentVertex(t,e) | |
2248 | * 13 if vertex w is not discovered and not explored | |
2249 | * 14 label e as tree-edge | |
2250 | * 15 label w as discovered | |
2251 | * 16 S.push(w) | |
2252 | * 17 continue at 5 | |
2253 | * 18 else if vertex w is discovered | |
2254 | * 19 label e as back-edge | |
2255 | * 20 else | |
2256 | * 21 // vertex w is explored | |
2257 | * 22 label e as forward- or cross-edge | |
2258 | * 23 label t as explored | |
2259 | * 24 S.pop() | |
2260 | * | |
2261 | * convention: | |
2262 | * 0x10 - discovered | |
2263 | * 0x11 - discovered and fall-through edge labelled | |
2264 | * 0x12 - discovered and fall-through and branch edges labelled | |
2265 | * 0x20 - explored | |
2266 | */ | |
2267 | ||
2268 | enum { | |
2269 | DISCOVERED = 0x10, | |
2270 | EXPLORED = 0x20, | |
2271 | FALLTHROUGH = 1, | |
2272 | BRANCH = 2, | |
2273 | }; | |
2274 | ||
58e2af8b | 2275 | #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) |
f1bca824 | 2276 | |
475fb78f AS |
2277 | static int *insn_stack; /* stack of insns to process */ |
2278 | static int cur_stack; /* current stack index */ | |
2279 | static int *insn_state; | |
2280 | ||
2281 | /* t, w, e - match pseudo-code above: | |
2282 | * t - index of current instruction | |
2283 | * w - next instruction | |
2284 | * e - edge | |
2285 | */ | |
58e2af8b | 2286 | static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) |
475fb78f AS |
2287 | { |
2288 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
2289 | return 0; | |
2290 | ||
2291 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
2292 | return 0; | |
2293 | ||
2294 | if (w < 0 || w >= env->prog->len) { | |
2295 | verbose("jump out of range from insn %d to %d\n", t, w); | |
2296 | return -EINVAL; | |
2297 | } | |
2298 | ||
f1bca824 AS |
2299 | if (e == BRANCH) |
2300 | /* mark branch target for state pruning */ | |
2301 | env->explored_states[w] = STATE_LIST_MARK; | |
2302 | ||
475fb78f AS |
2303 | if (insn_state[w] == 0) { |
2304 | /* tree-edge */ | |
2305 | insn_state[t] = DISCOVERED | e; | |
2306 | insn_state[w] = DISCOVERED; | |
2307 | if (cur_stack >= env->prog->len) | |
2308 | return -E2BIG; | |
2309 | insn_stack[cur_stack++] = w; | |
2310 | return 1; | |
2311 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
2312 | verbose("back-edge from insn %d to %d\n", t, w); | |
2313 | return -EINVAL; | |
2314 | } else if (insn_state[w] == EXPLORED) { | |
2315 | /* forward- or cross-edge */ | |
2316 | insn_state[t] = DISCOVERED | e; | |
2317 | } else { | |
2318 | verbose("insn state internal bug\n"); | |
2319 | return -EFAULT; | |
2320 | } | |
2321 | return 0; | |
2322 | } | |
2323 | ||
2324 | /* non-recursive depth-first-search to detect loops in BPF program | |
2325 | * loop == back-edge in directed graph | |
2326 | */ | |
58e2af8b | 2327 | static int check_cfg(struct bpf_verifier_env *env) |
475fb78f AS |
2328 | { |
2329 | struct bpf_insn *insns = env->prog->insnsi; | |
2330 | int insn_cnt = env->prog->len; | |
2331 | int ret = 0; | |
2332 | int i, t; | |
2333 | ||
2334 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
2335 | if (!insn_state) | |
2336 | return -ENOMEM; | |
2337 | ||
2338 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
2339 | if (!insn_stack) { | |
2340 | kfree(insn_state); | |
2341 | return -ENOMEM; | |
2342 | } | |
2343 | ||
2344 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
2345 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
2346 | cur_stack = 1; | |
2347 | ||
2348 | peek_stack: | |
2349 | if (cur_stack == 0) | |
2350 | goto check_state; | |
2351 | t = insn_stack[cur_stack - 1]; | |
2352 | ||
2353 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
2354 | u8 opcode = BPF_OP(insns[t].code); | |
2355 | ||
2356 | if (opcode == BPF_EXIT) { | |
2357 | goto mark_explored; | |
2358 | } else if (opcode == BPF_CALL) { | |
2359 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2360 | if (ret == 1) | |
2361 | goto peek_stack; | |
2362 | else if (ret < 0) | |
2363 | goto err_free; | |
07016151 DB |
2364 | if (t + 1 < insn_cnt) |
2365 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2366 | } else if (opcode == BPF_JA) { |
2367 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
2368 | ret = -EINVAL; | |
2369 | goto err_free; | |
2370 | } | |
2371 | /* unconditional jump with single edge */ | |
2372 | ret = push_insn(t, t + insns[t].off + 1, | |
2373 | FALLTHROUGH, env); | |
2374 | if (ret == 1) | |
2375 | goto peek_stack; | |
2376 | else if (ret < 0) | |
2377 | goto err_free; | |
f1bca824 AS |
2378 | /* tell verifier to check for equivalent states |
2379 | * after every call and jump | |
2380 | */ | |
c3de6317 AS |
2381 | if (t + 1 < insn_cnt) |
2382 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2383 | } else { |
2384 | /* conditional jump with two edges */ | |
2385 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2386 | if (ret == 1) | |
2387 | goto peek_stack; | |
2388 | else if (ret < 0) | |
2389 | goto err_free; | |
2390 | ||
2391 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
2392 | if (ret == 1) | |
2393 | goto peek_stack; | |
2394 | else if (ret < 0) | |
2395 | goto err_free; | |
2396 | } | |
2397 | } else { | |
2398 | /* all other non-branch instructions with single | |
2399 | * fall-through edge | |
2400 | */ | |
2401 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2402 | if (ret == 1) | |
2403 | goto peek_stack; | |
2404 | else if (ret < 0) | |
2405 | goto err_free; | |
2406 | } | |
2407 | ||
2408 | mark_explored: | |
2409 | insn_state[t] = EXPLORED; | |
2410 | if (cur_stack-- <= 0) { | |
2411 | verbose("pop stack internal bug\n"); | |
2412 | ret = -EFAULT; | |
2413 | goto err_free; | |
2414 | } | |
2415 | goto peek_stack; | |
2416 | ||
2417 | check_state: | |
2418 | for (i = 0; i < insn_cnt; i++) { | |
2419 | if (insn_state[i] != EXPLORED) { | |
2420 | verbose("unreachable insn %d\n", i); | |
2421 | ret = -EINVAL; | |
2422 | goto err_free; | |
2423 | } | |
2424 | } | |
2425 | ret = 0; /* cfg looks good */ | |
2426 | ||
2427 | err_free: | |
2428 | kfree(insn_state); | |
2429 | kfree(insn_stack); | |
2430 | return ret; | |
2431 | } | |
2432 | ||
969bf05e AS |
2433 | /* the following conditions reduce the number of explored insns |
2434 | * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet | |
2435 | */ | |
58e2af8b JK |
2436 | static bool compare_ptrs_to_packet(struct bpf_reg_state *old, |
2437 | struct bpf_reg_state *cur) | |
969bf05e AS |
2438 | { |
2439 | if (old->id != cur->id) | |
2440 | return false; | |
2441 | ||
2442 | /* old ptr_to_packet is more conservative, since it allows smaller | |
2443 | * range. Ex: | |
2444 | * old(off=0,r=10) is equal to cur(off=0,r=20), because | |
2445 | * old(off=0,r=10) means that with range=10 the verifier proceeded | |
2446 | * further and found no issues with the program. Now we're in the same | |
2447 | * spot with cur(off=0,r=20), so we're safe too, since anything further | |
2448 | * will only be looking at most 10 bytes after this pointer. | |
2449 | */ | |
2450 | if (old->off == cur->off && old->range < cur->range) | |
2451 | return true; | |
2452 | ||
2453 | /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) | |
2454 | * since both cannot be used for packet access and safe(old) | |
2455 | * pointer has smaller off that could be used for further | |
2456 | * 'if (ptr > data_end)' check | |
2457 | * Ex: | |
2458 | * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean | |
2459 | * that we cannot access the packet. | |
2460 | * The safe range is: | |
2461 | * [ptr, ptr + range - off) | |
2462 | * so whenever off >=range, it means no safe bytes from this pointer. | |
2463 | * When comparing old->off <= cur->off, it means that older code | |
2464 | * went with smaller offset and that offset was later | |
2465 | * used to figure out the safe range after 'if (ptr > data_end)' check | |
2466 | * Say, 'old' state was explored like: | |
2467 | * ... R3(off=0, r=0) | |
2468 | * R4 = R3 + 20 | |
2469 | * ... now R4(off=20,r=0) <-- here | |
2470 | * if (R4 > data_end) | |
2471 | * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. | |
2472 | * ... the code further went all the way to bpf_exit. | |
2473 | * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). | |
2474 | * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier | |
2475 | * goes further, such cur_R4 will give larger safe packet range after | |
2476 | * 'if (R4 > data_end)' and all further insn were already good with r=20, | |
2477 | * so they will be good with r=30 and we can prune the search. | |
2478 | */ | |
2479 | if (old->off <= cur->off && | |
2480 | old->off >= old->range && cur->off >= cur->range) | |
2481 | return true; | |
2482 | ||
2483 | return false; | |
2484 | } | |
2485 | ||
f1bca824 AS |
2486 | /* compare two verifier states |
2487 | * | |
2488 | * all states stored in state_list are known to be valid, since | |
2489 | * verifier reached 'bpf_exit' instruction through them | |
2490 | * | |
2491 | * this function is called when verifier exploring different branches of | |
2492 | * execution popped from the state stack. If it sees an old state that has | |
2493 | * more strict register state and more strict stack state then this execution | |
2494 | * branch doesn't need to be explored further, since verifier already | |
2495 | * concluded that more strict state leads to valid finish. | |
2496 | * | |
2497 | * Therefore two states are equivalent if register state is more conservative | |
2498 | * and explored stack state is more conservative than the current one. | |
2499 | * Example: | |
2500 | * explored current | |
2501 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
2502 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
2503 | * | |
2504 | * In other words if current stack state (one being explored) has more | |
2505 | * valid slots than old one that already passed validation, it means | |
2506 | * the verifier can stop exploring and conclude that current state is valid too | |
2507 | * | |
2508 | * Similarly with registers. If explored state has register type as invalid | |
2509 | * whereas register type in current state is meaningful, it means that | |
2510 | * the current state will reach 'bpf_exit' instruction safely | |
2511 | */ | |
48461135 JB |
2512 | static bool states_equal(struct bpf_verifier_env *env, |
2513 | struct bpf_verifier_state *old, | |
58e2af8b | 2514 | struct bpf_verifier_state *cur) |
f1bca824 | 2515 | { |
e2d2afe1 | 2516 | bool varlen_map_access = env->varlen_map_value_access; |
58e2af8b | 2517 | struct bpf_reg_state *rold, *rcur; |
f1bca824 AS |
2518 | int i; |
2519 | ||
2520 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
2521 | rold = &old->regs[i]; |
2522 | rcur = &cur->regs[i]; | |
2523 | ||
2524 | if (memcmp(rold, rcur, sizeof(*rold)) == 0) | |
2525 | continue; | |
2526 | ||
48461135 JB |
2527 | /* If the ranges were not the same, but everything else was and |
2528 | * we didn't do a variable access into a map then we are a-ok. | |
2529 | */ | |
e2d2afe1 | 2530 | if (!varlen_map_access && |
d2a4dd37 | 2531 | memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0) |
48461135 JB |
2532 | continue; |
2533 | ||
e2d2afe1 JB |
2534 | /* If we didn't map access then again we don't care about the |
2535 | * mismatched range values and it's ok if our old type was | |
2536 | * UNKNOWN and we didn't go to a NOT_INIT'ed reg. | |
2537 | */ | |
1a0dc1ac | 2538 | if (rold->type == NOT_INIT || |
e2d2afe1 JB |
2539 | (!varlen_map_access && rold->type == UNKNOWN_VALUE && |
2540 | rcur->type != NOT_INIT)) | |
1a0dc1ac AS |
2541 | continue; |
2542 | ||
969bf05e AS |
2543 | if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && |
2544 | compare_ptrs_to_packet(rold, rcur)) | |
2545 | continue; | |
2546 | ||
1a0dc1ac | 2547 | return false; |
f1bca824 AS |
2548 | } |
2549 | ||
2550 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
2551 | if (old->stack_slot_type[i] == STACK_INVALID) |
2552 | continue; | |
2553 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
2554 | /* Ex: old explored (safe) state has STACK_SPILL in | |
2555 | * this stack slot, but current has has STACK_MISC -> | |
2556 | * this verifier states are not equivalent, | |
2557 | * return false to continue verification of this path | |
2558 | */ | |
f1bca824 | 2559 | return false; |
9c399760 AS |
2560 | if (i % BPF_REG_SIZE) |
2561 | continue; | |
2562 | if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], | |
2563 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
2564 | sizeof(old->spilled_regs[0]))) | |
2565 | /* when explored and current stack slot types are | |
2566 | * the same, check that stored pointers types | |
2567 | * are the same as well. | |
2568 | * Ex: explored safe path could have stored | |
58e2af8b | 2569 | * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8} |
9c399760 | 2570 | * but current path has stored: |
58e2af8b | 2571 | * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16} |
9c399760 AS |
2572 | * such verifier states are not equivalent. |
2573 | * return false to continue verification of this path | |
2574 | */ | |
2575 | return false; | |
2576 | else | |
2577 | continue; | |
f1bca824 AS |
2578 | } |
2579 | return true; | |
2580 | } | |
2581 | ||
58e2af8b | 2582 | static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) |
f1bca824 | 2583 | { |
58e2af8b JK |
2584 | struct bpf_verifier_state_list *new_sl; |
2585 | struct bpf_verifier_state_list *sl; | |
f1bca824 AS |
2586 | |
2587 | sl = env->explored_states[insn_idx]; | |
2588 | if (!sl) | |
2589 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
2590 | * be doing state search here | |
2591 | */ | |
2592 | return 0; | |
2593 | ||
2594 | while (sl != STATE_LIST_MARK) { | |
48461135 | 2595 | if (states_equal(env, &sl->state, &env->cur_state)) |
f1bca824 AS |
2596 | /* reached equivalent register/stack state, |
2597 | * prune the search | |
2598 | */ | |
2599 | return 1; | |
2600 | sl = sl->next; | |
2601 | } | |
2602 | ||
2603 | /* there were no equivalent states, remember current one. | |
2604 | * technically the current state is not proven to be safe yet, | |
2605 | * but it will either reach bpf_exit (which means it's safe) or | |
2606 | * it will be rejected. Since there are no loops, we won't be | |
2607 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
2608 | */ | |
58e2af8b | 2609 | new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); |
f1bca824 AS |
2610 | if (!new_sl) |
2611 | return -ENOMEM; | |
2612 | ||
2613 | /* add new state to the head of linked list */ | |
2614 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
2615 | new_sl->next = env->explored_states[insn_idx]; | |
2616 | env->explored_states[insn_idx] = new_sl; | |
2617 | return 0; | |
2618 | } | |
2619 | ||
13a27dfc JK |
2620 | static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, |
2621 | int insn_idx, int prev_insn_idx) | |
2622 | { | |
2623 | if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) | |
2624 | return 0; | |
2625 | ||
2626 | return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); | |
2627 | } | |
2628 | ||
58e2af8b | 2629 | static int do_check(struct bpf_verifier_env *env) |
17a52670 | 2630 | { |
58e2af8b | 2631 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 2632 | struct bpf_insn *insns = env->prog->insnsi; |
58e2af8b | 2633 | struct bpf_reg_state *regs = state->regs; |
17a52670 AS |
2634 | int insn_cnt = env->prog->len; |
2635 | int insn_idx, prev_insn_idx = 0; | |
2636 | int insn_processed = 0; | |
2637 | bool do_print_state = false; | |
2638 | ||
2639 | init_reg_state(regs); | |
2640 | insn_idx = 0; | |
48461135 | 2641 | env->varlen_map_value_access = false; |
17a52670 AS |
2642 | for (;;) { |
2643 | struct bpf_insn *insn; | |
2644 | u8 class; | |
2645 | int err; | |
2646 | ||
2647 | if (insn_idx >= insn_cnt) { | |
2648 | verbose("invalid insn idx %d insn_cnt %d\n", | |
2649 | insn_idx, insn_cnt); | |
2650 | return -EFAULT; | |
2651 | } | |
2652 | ||
2653 | insn = &insns[insn_idx]; | |
2654 | class = BPF_CLASS(insn->code); | |
2655 | ||
07016151 | 2656 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
17a52670 AS |
2657 | verbose("BPF program is too large. Proccessed %d insn\n", |
2658 | insn_processed); | |
2659 | return -E2BIG; | |
2660 | } | |
2661 | ||
f1bca824 AS |
2662 | err = is_state_visited(env, insn_idx); |
2663 | if (err < 0) | |
2664 | return err; | |
2665 | if (err == 1) { | |
2666 | /* found equivalent state, can prune the search */ | |
2667 | if (log_level) { | |
2668 | if (do_print_state) | |
2669 | verbose("\nfrom %d to %d: safe\n", | |
2670 | prev_insn_idx, insn_idx); | |
2671 | else | |
2672 | verbose("%d: safe\n", insn_idx); | |
2673 | } | |
2674 | goto process_bpf_exit; | |
2675 | } | |
2676 | ||
17a52670 AS |
2677 | if (log_level && do_print_state) { |
2678 | verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx); | |
1a0dc1ac | 2679 | print_verifier_state(&env->cur_state); |
17a52670 AS |
2680 | do_print_state = false; |
2681 | } | |
2682 | ||
2683 | if (log_level) { | |
2684 | verbose("%d: ", insn_idx); | |
2685 | print_bpf_insn(insn); | |
2686 | } | |
2687 | ||
13a27dfc JK |
2688 | err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); |
2689 | if (err) | |
2690 | return err; | |
2691 | ||
17a52670 | 2692 | if (class == BPF_ALU || class == BPF_ALU64) { |
1be7f75d | 2693 | err = check_alu_op(env, insn); |
17a52670 AS |
2694 | if (err) |
2695 | return err; | |
2696 | ||
2697 | } else if (class == BPF_LDX) { | |
3df126f3 | 2698 | enum bpf_reg_type *prev_src_type, src_reg_type; |
9bac3d6d AS |
2699 | |
2700 | /* check for reserved fields is already done */ | |
2701 | ||
17a52670 AS |
2702 | /* check src operand */ |
2703 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2704 | if (err) | |
2705 | return err; | |
2706 | ||
2707 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
2708 | if (err) | |
2709 | return err; | |
2710 | ||
725f9dcd AS |
2711 | src_reg_type = regs[insn->src_reg].type; |
2712 | ||
17a52670 AS |
2713 | /* check that memory (src_reg + off) is readable, |
2714 | * the state of dst_reg will be updated by this func | |
2715 | */ | |
2716 | err = check_mem_access(env, insn->src_reg, insn->off, | |
2717 | BPF_SIZE(insn->code), BPF_READ, | |
2718 | insn->dst_reg); | |
2719 | if (err) | |
2720 | return err; | |
2721 | ||
48461135 | 2722 | reset_reg_range_values(regs, insn->dst_reg); |
ea2e7ce5 AS |
2723 | if (BPF_SIZE(insn->code) != BPF_W && |
2724 | BPF_SIZE(insn->code) != BPF_DW) { | |
725f9dcd AS |
2725 | insn_idx++; |
2726 | continue; | |
2727 | } | |
9bac3d6d | 2728 | |
3df126f3 JK |
2729 | prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; |
2730 | ||
2731 | if (*prev_src_type == NOT_INIT) { | |
9bac3d6d AS |
2732 | /* saw a valid insn |
2733 | * dst_reg = *(u32 *)(src_reg + off) | |
3df126f3 | 2734 | * save type to validate intersecting paths |
9bac3d6d | 2735 | */ |
3df126f3 | 2736 | *prev_src_type = src_reg_type; |
9bac3d6d | 2737 | |
3df126f3 | 2738 | } else if (src_reg_type != *prev_src_type && |
9bac3d6d | 2739 | (src_reg_type == PTR_TO_CTX || |
3df126f3 | 2740 | *prev_src_type == PTR_TO_CTX)) { |
9bac3d6d AS |
2741 | /* ABuser program is trying to use the same insn |
2742 | * dst_reg = *(u32*) (src_reg + off) | |
2743 | * with different pointer types: | |
2744 | * src_reg == ctx in one branch and | |
2745 | * src_reg == stack|map in some other branch. | |
2746 | * Reject it. | |
2747 | */ | |
2748 | verbose("same insn cannot be used with different pointers\n"); | |
2749 | return -EINVAL; | |
2750 | } | |
2751 | ||
17a52670 | 2752 | } else if (class == BPF_STX) { |
3df126f3 | 2753 | enum bpf_reg_type *prev_dst_type, dst_reg_type; |
d691f9e8 | 2754 | |
17a52670 AS |
2755 | if (BPF_MODE(insn->code) == BPF_XADD) { |
2756 | err = check_xadd(env, insn); | |
2757 | if (err) | |
2758 | return err; | |
2759 | insn_idx++; | |
2760 | continue; | |
2761 | } | |
2762 | ||
17a52670 AS |
2763 | /* check src1 operand */ |
2764 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2765 | if (err) | |
2766 | return err; | |
2767 | /* check src2 operand */ | |
2768 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2769 | if (err) | |
2770 | return err; | |
2771 | ||
d691f9e8 AS |
2772 | dst_reg_type = regs[insn->dst_reg].type; |
2773 | ||
17a52670 AS |
2774 | /* check that memory (dst_reg + off) is writeable */ |
2775 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2776 | BPF_SIZE(insn->code), BPF_WRITE, | |
2777 | insn->src_reg); | |
2778 | if (err) | |
2779 | return err; | |
2780 | ||
3df126f3 JK |
2781 | prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; |
2782 | ||
2783 | if (*prev_dst_type == NOT_INIT) { | |
2784 | *prev_dst_type = dst_reg_type; | |
2785 | } else if (dst_reg_type != *prev_dst_type && | |
d691f9e8 | 2786 | (dst_reg_type == PTR_TO_CTX || |
3df126f3 | 2787 | *prev_dst_type == PTR_TO_CTX)) { |
d691f9e8 AS |
2788 | verbose("same insn cannot be used with different pointers\n"); |
2789 | return -EINVAL; | |
2790 | } | |
2791 | ||
17a52670 AS |
2792 | } else if (class == BPF_ST) { |
2793 | if (BPF_MODE(insn->code) != BPF_MEM || | |
2794 | insn->src_reg != BPF_REG_0) { | |
2795 | verbose("BPF_ST uses reserved fields\n"); | |
2796 | return -EINVAL; | |
2797 | } | |
2798 | /* check src operand */ | |
2799 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2800 | if (err) | |
2801 | return err; | |
2802 | ||
2803 | /* check that memory (dst_reg + off) is writeable */ | |
2804 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2805 | BPF_SIZE(insn->code), BPF_WRITE, | |
2806 | -1); | |
2807 | if (err) | |
2808 | return err; | |
2809 | ||
2810 | } else if (class == BPF_JMP) { | |
2811 | u8 opcode = BPF_OP(insn->code); | |
2812 | ||
2813 | if (opcode == BPF_CALL) { | |
2814 | if (BPF_SRC(insn->code) != BPF_K || | |
2815 | insn->off != 0 || | |
2816 | insn->src_reg != BPF_REG_0 || | |
2817 | insn->dst_reg != BPF_REG_0) { | |
2818 | verbose("BPF_CALL uses reserved fields\n"); | |
2819 | return -EINVAL; | |
2820 | } | |
2821 | ||
2822 | err = check_call(env, insn->imm); | |
2823 | if (err) | |
2824 | return err; | |
2825 | ||
2826 | } else if (opcode == BPF_JA) { | |
2827 | if (BPF_SRC(insn->code) != BPF_K || | |
2828 | insn->imm != 0 || | |
2829 | insn->src_reg != BPF_REG_0 || | |
2830 | insn->dst_reg != BPF_REG_0) { | |
2831 | verbose("BPF_JA uses reserved fields\n"); | |
2832 | return -EINVAL; | |
2833 | } | |
2834 | ||
2835 | insn_idx += insn->off + 1; | |
2836 | continue; | |
2837 | ||
2838 | } else if (opcode == BPF_EXIT) { | |
2839 | if (BPF_SRC(insn->code) != BPF_K || | |
2840 | insn->imm != 0 || | |
2841 | insn->src_reg != BPF_REG_0 || | |
2842 | insn->dst_reg != BPF_REG_0) { | |
2843 | verbose("BPF_EXIT uses reserved fields\n"); | |
2844 | return -EINVAL; | |
2845 | } | |
2846 | ||
2847 | /* eBPF calling convetion is such that R0 is used | |
2848 | * to return the value from eBPF program. | |
2849 | * Make sure that it's readable at this time | |
2850 | * of bpf_exit, which means that program wrote | |
2851 | * something into it earlier | |
2852 | */ | |
2853 | err = check_reg_arg(regs, BPF_REG_0, SRC_OP); | |
2854 | if (err) | |
2855 | return err; | |
2856 | ||
1be7f75d AS |
2857 | if (is_pointer_value(env, BPF_REG_0)) { |
2858 | verbose("R0 leaks addr as return value\n"); | |
2859 | return -EACCES; | |
2860 | } | |
2861 | ||
f1bca824 | 2862 | process_bpf_exit: |
17a52670 AS |
2863 | insn_idx = pop_stack(env, &prev_insn_idx); |
2864 | if (insn_idx < 0) { | |
2865 | break; | |
2866 | } else { | |
2867 | do_print_state = true; | |
2868 | continue; | |
2869 | } | |
2870 | } else { | |
2871 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
2872 | if (err) | |
2873 | return err; | |
2874 | } | |
2875 | } else if (class == BPF_LD) { | |
2876 | u8 mode = BPF_MODE(insn->code); | |
2877 | ||
2878 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
2879 | err = check_ld_abs(env, insn); |
2880 | if (err) | |
2881 | return err; | |
2882 | ||
17a52670 AS |
2883 | } else if (mode == BPF_IMM) { |
2884 | err = check_ld_imm(env, insn); | |
2885 | if (err) | |
2886 | return err; | |
2887 | ||
2888 | insn_idx++; | |
2889 | } else { | |
2890 | verbose("invalid BPF_LD mode\n"); | |
2891 | return -EINVAL; | |
2892 | } | |
48461135 | 2893 | reset_reg_range_values(regs, insn->dst_reg); |
17a52670 AS |
2894 | } else { |
2895 | verbose("unknown insn class %d\n", class); | |
2896 | return -EINVAL; | |
2897 | } | |
2898 | ||
2899 | insn_idx++; | |
2900 | } | |
2901 | ||
1a0dc1ac | 2902 | verbose("processed %d insns\n", insn_processed); |
17a52670 AS |
2903 | return 0; |
2904 | } | |
2905 | ||
fdc15d38 AS |
2906 | static int check_map_prog_compatibility(struct bpf_map *map, |
2907 | struct bpf_prog *prog) | |
2908 | ||
2909 | { | |
2910 | if (prog->type == BPF_PROG_TYPE_PERF_EVENT && | |
2911 | (map->map_type == BPF_MAP_TYPE_HASH || | |
2912 | map->map_type == BPF_MAP_TYPE_PERCPU_HASH) && | |
2913 | (map->map_flags & BPF_F_NO_PREALLOC)) { | |
2914 | verbose("perf_event programs can only use preallocated hash map\n"); | |
2915 | return -EINVAL; | |
2916 | } | |
2917 | return 0; | |
2918 | } | |
2919 | ||
0246e64d AS |
2920 | /* look for pseudo eBPF instructions that access map FDs and |
2921 | * replace them with actual map pointers | |
2922 | */ | |
58e2af8b | 2923 | static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) |
0246e64d AS |
2924 | { |
2925 | struct bpf_insn *insn = env->prog->insnsi; | |
2926 | int insn_cnt = env->prog->len; | |
fdc15d38 | 2927 | int i, j, err; |
0246e64d AS |
2928 | |
2929 | for (i = 0; i < insn_cnt; i++, insn++) { | |
9bac3d6d | 2930 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 2931 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
9bac3d6d AS |
2932 | verbose("BPF_LDX uses reserved fields\n"); |
2933 | return -EINVAL; | |
2934 | } | |
2935 | ||
d691f9e8 AS |
2936 | if (BPF_CLASS(insn->code) == BPF_STX && |
2937 | ((BPF_MODE(insn->code) != BPF_MEM && | |
2938 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
2939 | verbose("BPF_STX uses reserved fields\n"); | |
2940 | return -EINVAL; | |
2941 | } | |
2942 | ||
0246e64d AS |
2943 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
2944 | struct bpf_map *map; | |
2945 | struct fd f; | |
2946 | ||
2947 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
2948 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
2949 | insn[1].off != 0) { | |
2950 | verbose("invalid bpf_ld_imm64 insn\n"); | |
2951 | return -EINVAL; | |
2952 | } | |
2953 | ||
2954 | if (insn->src_reg == 0) | |
2955 | /* valid generic load 64-bit imm */ | |
2956 | goto next_insn; | |
2957 | ||
2958 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
2959 | verbose("unrecognized bpf_ld_imm64 insn\n"); | |
2960 | return -EINVAL; | |
2961 | } | |
2962 | ||
2963 | f = fdget(insn->imm); | |
c2101297 | 2964 | map = __bpf_map_get(f); |
0246e64d AS |
2965 | if (IS_ERR(map)) { |
2966 | verbose("fd %d is not pointing to valid bpf_map\n", | |
2967 | insn->imm); | |
0246e64d AS |
2968 | return PTR_ERR(map); |
2969 | } | |
2970 | ||
fdc15d38 AS |
2971 | err = check_map_prog_compatibility(map, env->prog); |
2972 | if (err) { | |
2973 | fdput(f); | |
2974 | return err; | |
2975 | } | |
2976 | ||
0246e64d AS |
2977 | /* store map pointer inside BPF_LD_IMM64 instruction */ |
2978 | insn[0].imm = (u32) (unsigned long) map; | |
2979 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
2980 | ||
2981 | /* check whether we recorded this map already */ | |
2982 | for (j = 0; j < env->used_map_cnt; j++) | |
2983 | if (env->used_maps[j] == map) { | |
2984 | fdput(f); | |
2985 | goto next_insn; | |
2986 | } | |
2987 | ||
2988 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
2989 | fdput(f); | |
2990 | return -E2BIG; | |
2991 | } | |
2992 | ||
0246e64d AS |
2993 | /* hold the map. If the program is rejected by verifier, |
2994 | * the map will be released by release_maps() or it | |
2995 | * will be used by the valid program until it's unloaded | |
2996 | * and all maps are released in free_bpf_prog_info() | |
2997 | */ | |
92117d84 AS |
2998 | map = bpf_map_inc(map, false); |
2999 | if (IS_ERR(map)) { | |
3000 | fdput(f); | |
3001 | return PTR_ERR(map); | |
3002 | } | |
3003 | env->used_maps[env->used_map_cnt++] = map; | |
3004 | ||
0246e64d AS |
3005 | fdput(f); |
3006 | next_insn: | |
3007 | insn++; | |
3008 | i++; | |
3009 | } | |
3010 | } | |
3011 | ||
3012 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
3013 | * 'struct bpf_map *' into a register instead of user map_fd. | |
3014 | * These pointers will be used later by verifier to validate map access. | |
3015 | */ | |
3016 | return 0; | |
3017 | } | |
3018 | ||
3019 | /* drop refcnt of maps used by the rejected program */ | |
58e2af8b | 3020 | static void release_maps(struct bpf_verifier_env *env) |
0246e64d AS |
3021 | { |
3022 | int i; | |
3023 | ||
3024 | for (i = 0; i < env->used_map_cnt; i++) | |
3025 | bpf_map_put(env->used_maps[i]); | |
3026 | } | |
3027 | ||
3028 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
58e2af8b | 3029 | static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) |
0246e64d AS |
3030 | { |
3031 | struct bpf_insn *insn = env->prog->insnsi; | |
3032 | int insn_cnt = env->prog->len; | |
3033 | int i; | |
3034 | ||
3035 | for (i = 0; i < insn_cnt; i++, insn++) | |
3036 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
3037 | insn->src_reg = 0; | |
3038 | } | |
3039 | ||
9bac3d6d AS |
3040 | /* convert load instructions that access fields of 'struct __sk_buff' |
3041 | * into sequence of instructions that access fields of 'struct sk_buff' | |
3042 | */ | |
58e2af8b | 3043 | static int convert_ctx_accesses(struct bpf_verifier_env *env) |
9bac3d6d | 3044 | { |
36bbef52 | 3045 | const struct bpf_verifier_ops *ops = env->prog->aux->ops; |
3df126f3 | 3046 | const int insn_cnt = env->prog->len; |
36bbef52 | 3047 | struct bpf_insn insn_buf[16], *insn; |
9bac3d6d | 3048 | struct bpf_prog *new_prog; |
d691f9e8 | 3049 | enum bpf_access_type type; |
3df126f3 | 3050 | int i, cnt, delta = 0; |
9bac3d6d | 3051 | |
36bbef52 DB |
3052 | if (ops->gen_prologue) { |
3053 | cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, | |
3054 | env->prog); | |
3055 | if (cnt >= ARRAY_SIZE(insn_buf)) { | |
3056 | verbose("bpf verifier is misconfigured\n"); | |
3057 | return -EINVAL; | |
3058 | } else if (cnt) { | |
3059 | new_prog = bpf_patch_insn_single(env->prog, 0, | |
3060 | insn_buf, cnt); | |
3061 | if (!new_prog) | |
3062 | return -ENOMEM; | |
3063 | env->prog = new_prog; | |
3df126f3 | 3064 | delta += cnt - 1; |
36bbef52 DB |
3065 | } |
3066 | } | |
3067 | ||
3068 | if (!ops->convert_ctx_access) | |
9bac3d6d AS |
3069 | return 0; |
3070 | ||
3df126f3 | 3071 | insn = env->prog->insnsi + delta; |
36bbef52 | 3072 | |
9bac3d6d | 3073 | for (i = 0; i < insn_cnt; i++, insn++) { |
ea2e7ce5 AS |
3074 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) || |
3075 | insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) | |
d691f9e8 | 3076 | type = BPF_READ; |
ea2e7ce5 AS |
3077 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) || |
3078 | insn->code == (BPF_STX | BPF_MEM | BPF_DW)) | |
d691f9e8 AS |
3079 | type = BPF_WRITE; |
3080 | else | |
9bac3d6d AS |
3081 | continue; |
3082 | ||
3df126f3 | 3083 | if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX) |
9bac3d6d | 3084 | continue; |
9bac3d6d | 3085 | |
36bbef52 DB |
3086 | cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg, |
3087 | insn->off, insn_buf, env->prog); | |
9bac3d6d AS |
3088 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { |
3089 | verbose("bpf verifier is misconfigured\n"); | |
3090 | return -EINVAL; | |
3091 | } | |
3092 | ||
3df126f3 JK |
3093 | new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf, |
3094 | cnt); | |
9bac3d6d AS |
3095 | if (!new_prog) |
3096 | return -ENOMEM; | |
3097 | ||
3df126f3 | 3098 | delta += cnt - 1; |
9bac3d6d AS |
3099 | |
3100 | /* keep walking new program and skip insns we just inserted */ | |
3101 | env->prog = new_prog; | |
3df126f3 | 3102 | insn = new_prog->insnsi + i + delta; |
9bac3d6d AS |
3103 | } |
3104 | ||
3105 | return 0; | |
3106 | } | |
3107 | ||
58e2af8b | 3108 | static void free_states(struct bpf_verifier_env *env) |
f1bca824 | 3109 | { |
58e2af8b | 3110 | struct bpf_verifier_state_list *sl, *sln; |
f1bca824 AS |
3111 | int i; |
3112 | ||
3113 | if (!env->explored_states) | |
3114 | return; | |
3115 | ||
3116 | for (i = 0; i < env->prog->len; i++) { | |
3117 | sl = env->explored_states[i]; | |
3118 | ||
3119 | if (sl) | |
3120 | while (sl != STATE_LIST_MARK) { | |
3121 | sln = sl->next; | |
3122 | kfree(sl); | |
3123 | sl = sln; | |
3124 | } | |
3125 | } | |
3126 | ||
3127 | kfree(env->explored_states); | |
3128 | } | |
3129 | ||
9bac3d6d | 3130 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 3131 | { |
cbd35700 | 3132 | char __user *log_ubuf = NULL; |
58e2af8b | 3133 | struct bpf_verifier_env *env; |
51580e79 AS |
3134 | int ret = -EINVAL; |
3135 | ||
58e2af8b | 3136 | /* 'struct bpf_verifier_env' can be global, but since it's not small, |
cbd35700 AS |
3137 | * allocate/free it every time bpf_check() is called |
3138 | */ | |
58e2af8b | 3139 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
cbd35700 AS |
3140 | if (!env) |
3141 | return -ENOMEM; | |
3142 | ||
3df126f3 JK |
3143 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * |
3144 | (*prog)->len); | |
3145 | ret = -ENOMEM; | |
3146 | if (!env->insn_aux_data) | |
3147 | goto err_free_env; | |
9bac3d6d | 3148 | env->prog = *prog; |
0246e64d | 3149 | |
cbd35700 AS |
3150 | /* grab the mutex to protect few globals used by verifier */ |
3151 | mutex_lock(&bpf_verifier_lock); | |
3152 | ||
3153 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
3154 | /* user requested verbose verifier output | |
3155 | * and supplied buffer to store the verification trace | |
3156 | */ | |
3157 | log_level = attr->log_level; | |
3158 | log_ubuf = (char __user *) (unsigned long) attr->log_buf; | |
3159 | log_size = attr->log_size; | |
3160 | log_len = 0; | |
3161 | ||
3162 | ret = -EINVAL; | |
3163 | /* log_* values have to be sane */ | |
3164 | if (log_size < 128 || log_size > UINT_MAX >> 8 || | |
3165 | log_level == 0 || log_ubuf == NULL) | |
3df126f3 | 3166 | goto err_unlock; |
cbd35700 AS |
3167 | |
3168 | ret = -ENOMEM; | |
3169 | log_buf = vmalloc(log_size); | |
3170 | if (!log_buf) | |
3df126f3 | 3171 | goto err_unlock; |
cbd35700 AS |
3172 | } else { |
3173 | log_level = 0; | |
3174 | } | |
3175 | ||
7bd509e3 DB |
3176 | bpf_prog_calc_digest(env->prog); |
3177 | ||
0246e64d AS |
3178 | ret = replace_map_fd_with_map_ptr(env); |
3179 | if (ret < 0) | |
3180 | goto skip_full_check; | |
3181 | ||
9bac3d6d | 3182 | env->explored_states = kcalloc(env->prog->len, |
58e2af8b | 3183 | sizeof(struct bpf_verifier_state_list *), |
f1bca824 AS |
3184 | GFP_USER); |
3185 | ret = -ENOMEM; | |
3186 | if (!env->explored_states) | |
3187 | goto skip_full_check; | |
3188 | ||
475fb78f AS |
3189 | ret = check_cfg(env); |
3190 | if (ret < 0) | |
3191 | goto skip_full_check; | |
3192 | ||
1be7f75d AS |
3193 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
3194 | ||
17a52670 | 3195 | ret = do_check(env); |
cbd35700 | 3196 | |
0246e64d | 3197 | skip_full_check: |
17a52670 | 3198 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 3199 | free_states(env); |
0246e64d | 3200 | |
9bac3d6d AS |
3201 | if (ret == 0) |
3202 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
3203 | ret = convert_ctx_accesses(env); | |
3204 | ||
cbd35700 AS |
3205 | if (log_level && log_len >= log_size - 1) { |
3206 | BUG_ON(log_len >= log_size); | |
3207 | /* verifier log exceeded user supplied buffer */ | |
3208 | ret = -ENOSPC; | |
3209 | /* fall through to return what was recorded */ | |
3210 | } | |
3211 | ||
3212 | /* copy verifier log back to user space including trailing zero */ | |
3213 | if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { | |
3214 | ret = -EFAULT; | |
3215 | goto free_log_buf; | |
3216 | } | |
3217 | ||
0246e64d AS |
3218 | if (ret == 0 && env->used_map_cnt) { |
3219 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
3220 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
3221 | sizeof(env->used_maps[0]), | |
3222 | GFP_KERNEL); | |
0246e64d | 3223 | |
9bac3d6d | 3224 | if (!env->prog->aux->used_maps) { |
0246e64d AS |
3225 | ret = -ENOMEM; |
3226 | goto free_log_buf; | |
3227 | } | |
3228 | ||
9bac3d6d | 3229 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 3230 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 3231 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
3232 | |
3233 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
3234 | * bpf_ld_imm64 instructions | |
3235 | */ | |
3236 | convert_pseudo_ld_imm64(env); | |
3237 | } | |
cbd35700 AS |
3238 | |
3239 | free_log_buf: | |
3240 | if (log_level) | |
3241 | vfree(log_buf); | |
9bac3d6d | 3242 | if (!env->prog->aux->used_maps) |
0246e64d AS |
3243 | /* if we didn't copy map pointers into bpf_prog_info, release |
3244 | * them now. Otherwise free_bpf_prog_info() will release them. | |
3245 | */ | |
3246 | release_maps(env); | |
9bac3d6d | 3247 | *prog = env->prog; |
3df126f3 | 3248 | err_unlock: |
cbd35700 | 3249 | mutex_unlock(&bpf_verifier_lock); |
3df126f3 JK |
3250 | vfree(env->insn_aux_data); |
3251 | err_free_env: | |
3252 | kfree(env); | |
51580e79 AS |
3253 | return ret; |
3254 | } | |
13a27dfc JK |
3255 | |
3256 | int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, | |
3257 | void *priv) | |
3258 | { | |
3259 | struct bpf_verifier_env *env; | |
3260 | int ret; | |
3261 | ||
3262 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); | |
3263 | if (!env) | |
3264 | return -ENOMEM; | |
3265 | ||
3266 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * | |
3267 | prog->len); | |
3268 | ret = -ENOMEM; | |
3269 | if (!env->insn_aux_data) | |
3270 | goto err_free_env; | |
3271 | env->prog = prog; | |
3272 | env->analyzer_ops = ops; | |
3273 | env->analyzer_priv = priv; | |
3274 | ||
3275 | /* grab the mutex to protect few globals used by verifier */ | |
3276 | mutex_lock(&bpf_verifier_lock); | |
3277 | ||
3278 | log_level = 0; | |
3279 | ||
3280 | env->explored_states = kcalloc(env->prog->len, | |
3281 | sizeof(struct bpf_verifier_state_list *), | |
3282 | GFP_KERNEL); | |
3283 | ret = -ENOMEM; | |
3284 | if (!env->explored_states) | |
3285 | goto skip_full_check; | |
3286 | ||
3287 | ret = check_cfg(env); | |
3288 | if (ret < 0) | |
3289 | goto skip_full_check; | |
3290 | ||
3291 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); | |
3292 | ||
3293 | ret = do_check(env); | |
3294 | ||
3295 | skip_full_check: | |
3296 | while (pop_stack(env, NULL) >= 0); | |
3297 | free_states(env); | |
3298 | ||
3299 | mutex_unlock(&bpf_verifier_lock); | |
3300 | vfree(env->insn_aux_data); | |
3301 | err_free_env: | |
3302 | kfree(env); | |
3303 | return ret; | |
3304 | } | |
3305 | EXPORT_SYMBOL_GPL(bpf_analyzer); |