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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 | |
eba38a96 | 36 | * analysis is limited to 64k insn, which may be hit even if total number of |
51580e79 AS |
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 | ||
3c2ce60b | 143 | #define BPF_COMPLEXITY_LIMIT_INSNS 98304 |
07016151 DB |
144 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 |
145 | ||
fad73a1a MKL |
146 | #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) |
147 | ||
33ff9823 DB |
148 | struct bpf_call_arg_meta { |
149 | struct bpf_map *map_ptr; | |
435faee1 | 150 | bool raw_mode; |
36bbef52 | 151 | bool pkt_access; |
435faee1 DB |
152 | int regno; |
153 | int access_size; | |
33ff9823 DB |
154 | }; |
155 | ||
cbd35700 AS |
156 | /* verbose verifier prints what it's seeing |
157 | * bpf_check() is called under lock, so no race to access these global vars | |
158 | */ | |
159 | static u32 log_level, log_size, log_len; | |
160 | static char *log_buf; | |
161 | ||
162 | static DEFINE_MUTEX(bpf_verifier_lock); | |
163 | ||
164 | /* log_level controls verbosity level of eBPF verifier. | |
165 | * verbose() is used to dump the verification trace to the log, so the user | |
166 | * can figure out what's wrong with the program | |
167 | */ | |
1d056d9c | 168 | static __printf(1, 2) void verbose(const char *fmt, ...) |
cbd35700 AS |
169 | { |
170 | va_list args; | |
171 | ||
172 | if (log_level == 0 || log_len >= log_size - 1) | |
173 | return; | |
174 | ||
175 | va_start(args, fmt); | |
176 | log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); | |
177 | va_end(args); | |
178 | } | |
179 | ||
17a52670 AS |
180 | /* string representation of 'enum bpf_reg_type' */ |
181 | static const char * const reg_type_str[] = { | |
182 | [NOT_INIT] = "?", | |
183 | [UNKNOWN_VALUE] = "inv", | |
184 | [PTR_TO_CTX] = "ctx", | |
185 | [CONST_PTR_TO_MAP] = "map_ptr", | |
186 | [PTR_TO_MAP_VALUE] = "map_value", | |
187 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
48461135 | 188 | [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj", |
17a52670 AS |
189 | [FRAME_PTR] = "fp", |
190 | [PTR_TO_STACK] = "fp", | |
191 | [CONST_IMM] = "imm", | |
969bf05e AS |
192 | [PTR_TO_PACKET] = "pkt", |
193 | [PTR_TO_PACKET_END] = "pkt_end", | |
17a52670 AS |
194 | }; |
195 | ||
ebb676da TG |
196 | #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x) |
197 | static const char * const func_id_str[] = { | |
198 | __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN) | |
199 | }; | |
200 | #undef __BPF_FUNC_STR_FN | |
201 | ||
202 | static const char *func_id_name(int id) | |
203 | { | |
204 | BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID); | |
205 | ||
206 | if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id]) | |
207 | return func_id_str[id]; | |
208 | else | |
209 | return "unknown"; | |
210 | } | |
211 | ||
58e2af8b | 212 | static void print_verifier_state(struct bpf_verifier_state *state) |
17a52670 | 213 | { |
58e2af8b | 214 | struct bpf_reg_state *reg; |
17a52670 AS |
215 | enum bpf_reg_type t; |
216 | int i; | |
217 | ||
218 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
219 | reg = &state->regs[i]; |
220 | t = reg->type; | |
17a52670 AS |
221 | if (t == NOT_INIT) |
222 | continue; | |
223 | verbose(" R%d=%s", i, reg_type_str[t]); | |
224 | if (t == CONST_IMM || t == PTR_TO_STACK) | |
969bf05e AS |
225 | verbose("%lld", reg->imm); |
226 | else if (t == PTR_TO_PACKET) | |
227 | verbose("(id=%d,off=%d,r=%d)", | |
228 | reg->id, reg->off, reg->range); | |
229 | else if (t == UNKNOWN_VALUE && reg->imm) | |
230 | verbose("%lld", reg->imm); | |
17a52670 | 231 | else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || |
48461135 JB |
232 | t == PTR_TO_MAP_VALUE_OR_NULL || |
233 | t == PTR_TO_MAP_VALUE_ADJ) | |
57a09bf0 | 234 | verbose("(ks=%d,vs=%d,id=%u)", |
1a0dc1ac | 235 | reg->map_ptr->key_size, |
57a09bf0 TG |
236 | reg->map_ptr->value_size, |
237 | reg->id); | |
48461135 | 238 | if (reg->min_value != BPF_REGISTER_MIN_RANGE) |
f23cc643 JB |
239 | verbose(",min_value=%lld", |
240 | (long long)reg->min_value); | |
48461135 JB |
241 | if (reg->max_value != BPF_REGISTER_MAX_RANGE) |
242 | verbose(",max_value=%llu", | |
243 | (unsigned long long)reg->max_value); | |
d1174416 DM |
244 | if (reg->min_align) |
245 | verbose(",min_align=%u", reg->min_align); | |
246 | if (reg->aux_off) | |
247 | verbose(",aux_off=%u", reg->aux_off); | |
248 | if (reg->aux_off_align) | |
249 | verbose(",aux_off_align=%u", reg->aux_off_align); | |
17a52670 | 250 | } |
9c399760 | 251 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 252 | if (state->stack_slot_type[i] == STACK_SPILL) |
17a52670 | 253 | verbose(" fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 254 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 AS |
255 | } |
256 | verbose("\n"); | |
257 | } | |
258 | ||
cbd35700 AS |
259 | static const char *const bpf_class_string[] = { |
260 | [BPF_LD] = "ld", | |
261 | [BPF_LDX] = "ldx", | |
262 | [BPF_ST] = "st", | |
263 | [BPF_STX] = "stx", | |
264 | [BPF_ALU] = "alu", | |
265 | [BPF_JMP] = "jmp", | |
266 | [BPF_RET] = "BUG", | |
267 | [BPF_ALU64] = "alu64", | |
268 | }; | |
269 | ||
687f0715 | 270 | static const char *const bpf_alu_string[16] = { |
cbd35700 AS |
271 | [BPF_ADD >> 4] = "+=", |
272 | [BPF_SUB >> 4] = "-=", | |
273 | [BPF_MUL >> 4] = "*=", | |
274 | [BPF_DIV >> 4] = "/=", | |
275 | [BPF_OR >> 4] = "|=", | |
276 | [BPF_AND >> 4] = "&=", | |
277 | [BPF_LSH >> 4] = "<<=", | |
278 | [BPF_RSH >> 4] = ">>=", | |
279 | [BPF_NEG >> 4] = "neg", | |
280 | [BPF_MOD >> 4] = "%=", | |
281 | [BPF_XOR >> 4] = "^=", | |
282 | [BPF_MOV >> 4] = "=", | |
283 | [BPF_ARSH >> 4] = "s>>=", | |
284 | [BPF_END >> 4] = "endian", | |
285 | }; | |
286 | ||
287 | static const char *const bpf_ldst_string[] = { | |
288 | [BPF_W >> 3] = "u32", | |
289 | [BPF_H >> 3] = "u16", | |
290 | [BPF_B >> 3] = "u8", | |
291 | [BPF_DW >> 3] = "u64", | |
292 | }; | |
293 | ||
687f0715 | 294 | static const char *const bpf_jmp_string[16] = { |
cbd35700 AS |
295 | [BPF_JA >> 4] = "jmp", |
296 | [BPF_JEQ >> 4] = "==", | |
297 | [BPF_JGT >> 4] = ">", | |
298 | [BPF_JGE >> 4] = ">=", | |
299 | [BPF_JSET >> 4] = "&", | |
300 | [BPF_JNE >> 4] = "!=", | |
301 | [BPF_JSGT >> 4] = "s>", | |
302 | [BPF_JSGE >> 4] = "s>=", | |
303 | [BPF_CALL >> 4] = "call", | |
304 | [BPF_EXIT >> 4] = "exit", | |
305 | }; | |
306 | ||
0d0e5769 DB |
307 | static void print_bpf_insn(const struct bpf_verifier_env *env, |
308 | const struct bpf_insn *insn) | |
cbd35700 AS |
309 | { |
310 | u8 class = BPF_CLASS(insn->code); | |
311 | ||
312 | if (class == BPF_ALU || class == BPF_ALU64) { | |
313 | if (BPF_SRC(insn->code) == BPF_X) | |
314 | verbose("(%02x) %sr%d %s %sr%d\n", | |
315 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
316 | insn->dst_reg, | |
317 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
318 | class == BPF_ALU ? "(u32) " : "", | |
319 | insn->src_reg); | |
320 | else | |
321 | verbose("(%02x) %sr%d %s %s%d\n", | |
322 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
323 | insn->dst_reg, | |
324 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
325 | class == BPF_ALU ? "(u32) " : "", | |
326 | insn->imm); | |
327 | } else if (class == BPF_STX) { | |
328 | if (BPF_MODE(insn->code) == BPF_MEM) | |
329 | verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", | |
330 | insn->code, | |
331 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
332 | insn->dst_reg, | |
333 | insn->off, insn->src_reg); | |
334 | else if (BPF_MODE(insn->code) == BPF_XADD) | |
335 | verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", | |
336 | insn->code, | |
337 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
338 | insn->dst_reg, insn->off, | |
339 | insn->src_reg); | |
340 | else | |
341 | verbose("BUG_%02x\n", insn->code); | |
342 | } else if (class == BPF_ST) { | |
343 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
344 | verbose("BUG_st_%02x\n", insn->code); | |
345 | return; | |
346 | } | |
347 | verbose("(%02x) *(%s *)(r%d %+d) = %d\n", | |
348 | insn->code, | |
349 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
350 | insn->dst_reg, | |
351 | insn->off, insn->imm); | |
352 | } else if (class == BPF_LDX) { | |
353 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
354 | verbose("BUG_ldx_%02x\n", insn->code); | |
355 | return; | |
356 | } | |
357 | verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", | |
358 | insn->code, insn->dst_reg, | |
359 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
360 | insn->src_reg, insn->off); | |
361 | } else if (class == BPF_LD) { | |
362 | if (BPF_MODE(insn->code) == BPF_ABS) { | |
363 | verbose("(%02x) r0 = *(%s *)skb[%d]\n", | |
364 | insn->code, | |
365 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
366 | insn->imm); | |
367 | } else if (BPF_MODE(insn->code) == BPF_IND) { | |
368 | verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", | |
369 | insn->code, | |
370 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
371 | insn->src_reg, insn->imm); | |
0d0e5769 DB |
372 | } else if (BPF_MODE(insn->code) == BPF_IMM && |
373 | BPF_SIZE(insn->code) == BPF_DW) { | |
374 | /* At this point, we already made sure that the second | |
375 | * part of the ldimm64 insn is accessible. | |
376 | */ | |
377 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; | |
378 | bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD; | |
379 | ||
380 | if (map_ptr && !env->allow_ptr_leaks) | |
381 | imm = 0; | |
382 | ||
383 | verbose("(%02x) r%d = 0x%llx\n", insn->code, | |
384 | insn->dst_reg, (unsigned long long)imm); | |
cbd35700 AS |
385 | } else { |
386 | verbose("BUG_ld_%02x\n", insn->code); | |
387 | return; | |
388 | } | |
389 | } else if (class == BPF_JMP) { | |
390 | u8 opcode = BPF_OP(insn->code); | |
391 | ||
392 | if (opcode == BPF_CALL) { | |
ebb676da TG |
393 | verbose("(%02x) call %s#%d\n", insn->code, |
394 | func_id_name(insn->imm), insn->imm); | |
cbd35700 AS |
395 | } else if (insn->code == (BPF_JMP | BPF_JA)) { |
396 | verbose("(%02x) goto pc%+d\n", | |
397 | insn->code, insn->off); | |
398 | } else if (insn->code == (BPF_JMP | BPF_EXIT)) { | |
399 | verbose("(%02x) exit\n", insn->code); | |
400 | } else if (BPF_SRC(insn->code) == BPF_X) { | |
401 | verbose("(%02x) if r%d %s r%d goto pc%+d\n", | |
402 | insn->code, insn->dst_reg, | |
403 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
404 | insn->src_reg, insn->off); | |
405 | } else { | |
406 | verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", | |
407 | insn->code, insn->dst_reg, | |
408 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
409 | insn->imm, insn->off); | |
410 | } | |
411 | } else { | |
412 | verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); | |
413 | } | |
414 | } | |
415 | ||
58e2af8b | 416 | static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) |
17a52670 | 417 | { |
58e2af8b | 418 | struct bpf_verifier_stack_elem *elem; |
17a52670 AS |
419 | int insn_idx; |
420 | ||
421 | if (env->head == NULL) | |
422 | return -1; | |
423 | ||
424 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
425 | insn_idx = env->head->insn_idx; | |
426 | if (prev_insn_idx) | |
427 | *prev_insn_idx = env->head->prev_insn_idx; | |
428 | elem = env->head->next; | |
429 | kfree(env->head); | |
430 | env->head = elem; | |
431 | env->stack_size--; | |
432 | return insn_idx; | |
433 | } | |
434 | ||
58e2af8b JK |
435 | static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, |
436 | int insn_idx, int prev_insn_idx) | |
17a52670 | 437 | { |
58e2af8b | 438 | struct bpf_verifier_stack_elem *elem; |
17a52670 | 439 | |
58e2af8b | 440 | elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); |
17a52670 AS |
441 | if (!elem) |
442 | goto err; | |
443 | ||
444 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
445 | elem->insn_idx = insn_idx; | |
446 | elem->prev_insn_idx = prev_insn_idx; | |
447 | elem->next = env->head; | |
448 | env->head = elem; | |
449 | env->stack_size++; | |
07016151 | 450 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
17a52670 AS |
451 | verbose("BPF program is too complex\n"); |
452 | goto err; | |
453 | } | |
454 | return &elem->st; | |
455 | err: | |
456 | /* pop all elements and return */ | |
457 | while (pop_stack(env, NULL) >= 0); | |
458 | return NULL; | |
459 | } | |
460 | ||
461 | #define CALLER_SAVED_REGS 6 | |
462 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
463 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
464 | }; | |
465 | ||
a9789ef9 DB |
466 | static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno) |
467 | { | |
468 | BUG_ON(regno >= MAX_BPF_REG); | |
469 | ||
470 | memset(®s[regno], 0, sizeof(regs[regno])); | |
471 | regs[regno].type = NOT_INIT; | |
472 | regs[regno].min_value = BPF_REGISTER_MIN_RANGE; | |
473 | regs[regno].max_value = BPF_REGISTER_MAX_RANGE; | |
474 | } | |
475 | ||
58e2af8b | 476 | static void init_reg_state(struct bpf_reg_state *regs) |
17a52670 AS |
477 | { |
478 | int i; | |
479 | ||
a9789ef9 DB |
480 | for (i = 0; i < MAX_BPF_REG; i++) |
481 | mark_reg_not_init(regs, i); | |
17a52670 AS |
482 | |
483 | /* frame pointer */ | |
484 | regs[BPF_REG_FP].type = FRAME_PTR; | |
485 | ||
486 | /* 1st arg to a function */ | |
487 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
488 | } | |
489 | ||
6760bf2d | 490 | static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) |
17a52670 | 491 | { |
17a52670 | 492 | regs[regno].type = UNKNOWN_VALUE; |
57a09bf0 | 493 | regs[regno].id = 0; |
17a52670 | 494 | regs[regno].imm = 0; |
17a52670 AS |
495 | } |
496 | ||
6760bf2d DB |
497 | static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) |
498 | { | |
499 | BUG_ON(regno >= MAX_BPF_REG); | |
500 | __mark_reg_unknown_value(regs, regno); | |
501 | } | |
502 | ||
48461135 JB |
503 | static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno) |
504 | { | |
505 | regs[regno].min_value = BPF_REGISTER_MIN_RANGE; | |
506 | regs[regno].max_value = BPF_REGISTER_MAX_RANGE; | |
d1174416 | 507 | regs[regno].min_align = 0; |
48461135 JB |
508 | } |
509 | ||
f0318d01 GB |
510 | static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs, |
511 | u32 regno) | |
512 | { | |
513 | mark_reg_unknown_value(regs, regno); | |
514 | reset_reg_range_values(regs, regno); | |
515 | } | |
516 | ||
17a52670 AS |
517 | enum reg_arg_type { |
518 | SRC_OP, /* register is used as source operand */ | |
519 | DST_OP, /* register is used as destination operand */ | |
520 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
521 | }; | |
522 | ||
58e2af8b | 523 | static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, |
17a52670 AS |
524 | enum reg_arg_type t) |
525 | { | |
526 | if (regno >= MAX_BPF_REG) { | |
527 | verbose("R%d is invalid\n", regno); | |
528 | return -EINVAL; | |
529 | } | |
530 | ||
531 | if (t == SRC_OP) { | |
532 | /* check whether register used as source operand can be read */ | |
533 | if (regs[regno].type == NOT_INIT) { | |
534 | verbose("R%d !read_ok\n", regno); | |
535 | return -EACCES; | |
536 | } | |
537 | } else { | |
538 | /* check whether register used as dest operand can be written to */ | |
539 | if (regno == BPF_REG_FP) { | |
540 | verbose("frame pointer is read only\n"); | |
541 | return -EACCES; | |
542 | } | |
543 | if (t == DST_OP) | |
544 | mark_reg_unknown_value(regs, regno); | |
545 | } | |
546 | return 0; | |
547 | } | |
548 | ||
549 | static int bpf_size_to_bytes(int bpf_size) | |
550 | { | |
551 | if (bpf_size == BPF_W) | |
552 | return 4; | |
553 | else if (bpf_size == BPF_H) | |
554 | return 2; | |
555 | else if (bpf_size == BPF_B) | |
556 | return 1; | |
557 | else if (bpf_size == BPF_DW) | |
558 | return 8; | |
559 | else | |
560 | return -EINVAL; | |
561 | } | |
562 | ||
1be7f75d AS |
563 | static bool is_spillable_regtype(enum bpf_reg_type type) |
564 | { | |
565 | switch (type) { | |
566 | case PTR_TO_MAP_VALUE: | |
567 | case PTR_TO_MAP_VALUE_OR_NULL: | |
f0318d01 | 568 | case PTR_TO_MAP_VALUE_ADJ: |
1be7f75d AS |
569 | case PTR_TO_STACK: |
570 | case PTR_TO_CTX: | |
969bf05e AS |
571 | case PTR_TO_PACKET: |
572 | case PTR_TO_PACKET_END: | |
1be7f75d AS |
573 | case FRAME_PTR: |
574 | case CONST_PTR_TO_MAP: | |
575 | return true; | |
576 | default: | |
577 | return false; | |
578 | } | |
579 | } | |
580 | ||
17a52670 AS |
581 | /* check_stack_read/write functions track spill/fill of registers, |
582 | * stack boundary and alignment are checked in check_mem_access() | |
583 | */ | |
58e2af8b JK |
584 | static int check_stack_write(struct bpf_verifier_state *state, int off, |
585 | int size, int value_regno) | |
17a52670 | 586 | { |
17a52670 | 587 | int i; |
9c399760 AS |
588 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
589 | * so it's aligned access and [off, off + size) are within stack limits | |
590 | */ | |
17a52670 AS |
591 | |
592 | if (value_regno >= 0 && | |
1be7f75d | 593 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
594 | |
595 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 596 | if (size != BPF_REG_SIZE) { |
17a52670 AS |
597 | verbose("invalid size of register spill\n"); |
598 | return -EACCES; | |
599 | } | |
600 | ||
17a52670 | 601 | /* save register state */ |
9c399760 AS |
602 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
603 | state->regs[value_regno]; | |
17a52670 | 604 | |
9c399760 AS |
605 | for (i = 0; i < BPF_REG_SIZE; i++) |
606 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
607 | } else { | |
17a52670 | 608 | /* regular write of data into stack */ |
9c399760 | 609 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
58e2af8b | 610 | (struct bpf_reg_state) {}; |
9c399760 AS |
611 | |
612 | for (i = 0; i < size; i++) | |
613 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
614 | } |
615 | return 0; | |
616 | } | |
617 | ||
58e2af8b | 618 | static int check_stack_read(struct bpf_verifier_state *state, int off, int size, |
17a52670 AS |
619 | int value_regno) |
620 | { | |
9c399760 | 621 | u8 *slot_type; |
17a52670 | 622 | int i; |
17a52670 | 623 | |
9c399760 | 624 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 625 | |
9c399760 AS |
626 | if (slot_type[0] == STACK_SPILL) { |
627 | if (size != BPF_REG_SIZE) { | |
17a52670 AS |
628 | verbose("invalid size of register spill\n"); |
629 | return -EACCES; | |
630 | } | |
9c399760 AS |
631 | for (i = 1; i < BPF_REG_SIZE; i++) { |
632 | if (slot_type[i] != STACK_SPILL) { | |
17a52670 AS |
633 | verbose("corrupted spill memory\n"); |
634 | return -EACCES; | |
635 | } | |
636 | } | |
637 | ||
638 | if (value_regno >= 0) | |
639 | /* restore register state from stack */ | |
9c399760 AS |
640 | state->regs[value_regno] = |
641 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; | |
17a52670 AS |
642 | return 0; |
643 | } else { | |
644 | for (i = 0; i < size; i++) { | |
9c399760 | 645 | if (slot_type[i] != STACK_MISC) { |
17a52670 AS |
646 | verbose("invalid read from stack off %d+%d size %d\n", |
647 | off, i, size); | |
648 | return -EACCES; | |
649 | } | |
650 | } | |
651 | if (value_regno >= 0) | |
652 | /* have read misc data from the stack */ | |
f0318d01 GB |
653 | mark_reg_unknown_value_and_range(state->regs, |
654 | value_regno); | |
17a52670 AS |
655 | return 0; |
656 | } | |
657 | } | |
658 | ||
659 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
58e2af8b | 660 | static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
661 | int size) |
662 | { | |
663 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
664 | ||
5722569b | 665 | if (off < 0 || size <= 0 || off + size > map->value_size) { |
17a52670 AS |
666 | verbose("invalid access to map value, value_size=%d off=%d size=%d\n", |
667 | map->value_size, off, size); | |
668 | return -EACCES; | |
669 | } | |
670 | return 0; | |
671 | } | |
672 | ||
dbcfe5f7 GB |
673 | /* check read/write into an adjusted map element */ |
674 | static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno, | |
675 | int off, int size) | |
676 | { | |
677 | struct bpf_verifier_state *state = &env->cur_state; | |
678 | struct bpf_reg_state *reg = &state->regs[regno]; | |
679 | int err; | |
680 | ||
681 | /* We adjusted the register to this map value, so we | |
682 | * need to change off and size to min_value and max_value | |
683 | * respectively to make sure our theoretical access will be | |
684 | * safe. | |
685 | */ | |
686 | if (log_level) | |
687 | print_verifier_state(state); | |
688 | env->varlen_map_value_access = true; | |
689 | /* The minimum value is only important with signed | |
690 | * comparisons where we can't assume the floor of a | |
691 | * value is 0. If we are using signed variables for our | |
692 | * index'es we need to make sure that whatever we use | |
693 | * will have a set floor within our range. | |
694 | */ | |
695 | if (reg->min_value < 0) { | |
696 | verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", | |
697 | regno); | |
698 | return -EACCES; | |
699 | } | |
700 | err = check_map_access(env, regno, reg->min_value + off, size); | |
701 | if (err) { | |
702 | verbose("R%d min value is outside of the array range\n", | |
703 | regno); | |
704 | return err; | |
705 | } | |
706 | ||
707 | /* If we haven't set a max value then we need to bail | |
708 | * since we can't be sure we won't do bad things. | |
709 | */ | |
710 | if (reg->max_value == BPF_REGISTER_MAX_RANGE) { | |
711 | verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", | |
712 | regno); | |
713 | return -EACCES; | |
714 | } | |
715 | return check_map_access(env, regno, reg->max_value + off, size); | |
716 | } | |
717 | ||
969bf05e AS |
718 | #define MAX_PACKET_OFF 0xffff |
719 | ||
58e2af8b | 720 | static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, |
3a0af8fd TG |
721 | const struct bpf_call_arg_meta *meta, |
722 | enum bpf_access_type t) | |
4acf6c0b | 723 | { |
36bbef52 | 724 | switch (env->prog->type) { |
3a0af8fd TG |
725 | case BPF_PROG_TYPE_LWT_IN: |
726 | case BPF_PROG_TYPE_LWT_OUT: | |
727 | /* dst_input() and dst_output() can't write for now */ | |
728 | if (t == BPF_WRITE) | |
729 | return false; | |
7e57fbb2 | 730 | /* fallthrough */ |
36bbef52 DB |
731 | case BPF_PROG_TYPE_SCHED_CLS: |
732 | case BPF_PROG_TYPE_SCHED_ACT: | |
4acf6c0b | 733 | case BPF_PROG_TYPE_XDP: |
3a0af8fd | 734 | case BPF_PROG_TYPE_LWT_XMIT: |
36bbef52 DB |
735 | if (meta) |
736 | return meta->pkt_access; | |
737 | ||
738 | env->seen_direct_write = true; | |
4acf6c0b BB |
739 | return true; |
740 | default: | |
741 | return false; | |
742 | } | |
743 | } | |
744 | ||
58e2af8b | 745 | static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, |
969bf05e AS |
746 | int size) |
747 | { | |
58e2af8b JK |
748 | struct bpf_reg_state *regs = env->cur_state.regs; |
749 | struct bpf_reg_state *reg = ®s[regno]; | |
969bf05e | 750 | |
d91b28ed | 751 | off += reg->off; |
b399cf64 | 752 | if (off < 0 || size <= 0 || off + size > reg->range) { |
d91b28ed AS |
753 | verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", |
754 | off, size, regno, reg->id, reg->off, reg->range); | |
969bf05e AS |
755 | return -EACCES; |
756 | } | |
757 | return 0; | |
758 | } | |
759 | ||
17a52670 | 760 | /* check access to 'struct bpf_context' fields */ |
58e2af8b | 761 | static int check_ctx_access(struct bpf_verifier_env *env, int off, int size, |
19de99f7 | 762 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 | 763 | { |
13a27dfc JK |
764 | /* for analyzer ctx accesses are already validated and converted */ |
765 | if (env->analyzer_ops) | |
766 | return 0; | |
767 | ||
17a52670 | 768 | if (env->prog->aux->ops->is_valid_access && |
19de99f7 | 769 | env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { |
32bbe007 AS |
770 | /* remember the offset of last byte accessed in ctx */ |
771 | if (env->prog->aux->max_ctx_offset < off + size) | |
772 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 773 | return 0; |
32bbe007 | 774 | } |
17a52670 AS |
775 | |
776 | verbose("invalid bpf_context access off=%d size=%d\n", off, size); | |
777 | return -EACCES; | |
778 | } | |
779 | ||
58e2af8b | 780 | static bool is_pointer_value(struct bpf_verifier_env *env, int regno) |
1be7f75d AS |
781 | { |
782 | if (env->allow_ptr_leaks) | |
783 | return false; | |
784 | ||
785 | switch (env->cur_state.regs[regno].type) { | |
786 | case UNKNOWN_VALUE: | |
787 | case CONST_IMM: | |
788 | return false; | |
789 | default: | |
790 | return true; | |
791 | } | |
792 | } | |
793 | ||
79adffcd | 794 | static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg, |
d1174416 | 795 | int off, int size, bool strict) |
969bf05e | 796 | { |
e07b98d9 | 797 | int ip_align; |
d1174416 DM |
798 | int reg_off; |
799 | ||
800 | /* Byte size accesses are always allowed. */ | |
801 | if (!strict || size == 1) | |
802 | return 0; | |
803 | ||
804 | reg_off = reg->off; | |
805 | if (reg->id) { | |
806 | if (reg->aux_off_align % size) { | |
807 | verbose("Packet access is only %u byte aligned, %d byte access not allowed\n", | |
808 | reg->aux_off_align, size); | |
809 | return -EACCES; | |
810 | } | |
811 | reg_off += reg->aux_off; | |
969bf05e AS |
812 | } |
813 | ||
e4eda884 DM |
814 | /* For platforms that do not have a Kconfig enabling |
815 | * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of | |
816 | * NET_IP_ALIGN is universally set to '2'. And on platforms | |
817 | * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get | |
818 | * to this code only in strict mode where we want to emulate | |
819 | * the NET_IP_ALIGN==2 checking. Therefore use an | |
820 | * unconditional IP align value of '2'. | |
e07b98d9 | 821 | */ |
e4eda884 | 822 | ip_align = 2; |
e07b98d9 | 823 | if ((ip_align + reg_off + off) % size != 0) { |
969bf05e | 824 | verbose("misaligned packet access off %d+%d+%d size %d\n", |
e07b98d9 | 825 | ip_align, reg_off, off, size); |
969bf05e AS |
826 | return -EACCES; |
827 | } | |
79adffcd | 828 | |
969bf05e AS |
829 | return 0; |
830 | } | |
831 | ||
79adffcd | 832 | static int check_val_ptr_alignment(const struct bpf_reg_state *reg, |
d1174416 | 833 | int size, bool strict) |
79adffcd | 834 | { |
d1174416 | 835 | if (strict && size != 1) { |
79adffcd DB |
836 | verbose("Unknown alignment. Only byte-sized access allowed in value access.\n"); |
837 | return -EACCES; | |
838 | } | |
839 | ||
969bf05e AS |
840 | return 0; |
841 | } | |
842 | ||
e07b98d9 DM |
843 | static int check_ptr_alignment(struct bpf_verifier_env *env, |
844 | const struct bpf_reg_state *reg, | |
79adffcd DB |
845 | int off, int size) |
846 | { | |
e07b98d9 | 847 | bool strict = env->strict_alignment; |
d1174416 | 848 | |
79adffcd DB |
849 | switch (reg->type) { |
850 | case PTR_TO_PACKET: | |
d1174416 | 851 | return check_pkt_ptr_alignment(reg, off, size, strict); |
79adffcd | 852 | case PTR_TO_MAP_VALUE_ADJ: |
d1174416 | 853 | return check_val_ptr_alignment(reg, size, strict); |
79adffcd DB |
854 | default: |
855 | if (off % size != 0) { | |
856 | verbose("misaligned access off %d size %d\n", | |
857 | off, size); | |
858 | return -EACCES; | |
859 | } | |
860 | ||
861 | return 0; | |
862 | } | |
863 | } | |
864 | ||
17a52670 AS |
865 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
866 | * if t==write, value_regno is a register which value is stored into memory | |
867 | * if t==read, value_regno is a register which will receive the value from memory | |
868 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
869 | * if t==read && value_regno==-1, don't care what we read from memory | |
870 | */ | |
58e2af8b | 871 | static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
872 | int bpf_size, enum bpf_access_type t, |
873 | int value_regno) | |
874 | { | |
58e2af8b JK |
875 | struct bpf_verifier_state *state = &env->cur_state; |
876 | struct bpf_reg_state *reg = &state->regs[regno]; | |
17a52670 AS |
877 | int size, err = 0; |
878 | ||
1a0dc1ac AS |
879 | if (reg->type == PTR_TO_STACK) |
880 | off += reg->imm; | |
24b4d2ab | 881 | |
17a52670 AS |
882 | size = bpf_size_to_bytes(bpf_size); |
883 | if (size < 0) | |
884 | return size; | |
885 | ||
e07b98d9 | 886 | err = check_ptr_alignment(env, reg, off, size); |
969bf05e AS |
887 | if (err) |
888 | return err; | |
17a52670 | 889 | |
48461135 JB |
890 | if (reg->type == PTR_TO_MAP_VALUE || |
891 | reg->type == PTR_TO_MAP_VALUE_ADJ) { | |
1be7f75d AS |
892 | if (t == BPF_WRITE && value_regno >= 0 && |
893 | is_pointer_value(env, value_regno)) { | |
894 | verbose("R%d leaks addr into map\n", value_regno); | |
895 | return -EACCES; | |
896 | } | |
48461135 | 897 | |
dbcfe5f7 GB |
898 | if (reg->type == PTR_TO_MAP_VALUE_ADJ) |
899 | err = check_map_access_adj(env, regno, off, size); | |
900 | else | |
901 | err = check_map_access(env, regno, off, size); | |
17a52670 | 902 | if (!err && t == BPF_READ && value_regno >= 0) |
f0318d01 GB |
903 | mark_reg_unknown_value_and_range(state->regs, |
904 | value_regno); | |
17a52670 | 905 | |
1a0dc1ac | 906 | } else if (reg->type == PTR_TO_CTX) { |
19de99f7 AS |
907 | enum bpf_reg_type reg_type = UNKNOWN_VALUE; |
908 | ||
1be7f75d AS |
909 | if (t == BPF_WRITE && value_regno >= 0 && |
910 | is_pointer_value(env, value_regno)) { | |
911 | verbose("R%d leaks addr into ctx\n", value_regno); | |
912 | return -EACCES; | |
913 | } | |
19de99f7 | 914 | err = check_ctx_access(env, off, size, t, ®_type); |
969bf05e | 915 | if (!err && t == BPF_READ && value_regno >= 0) { |
f0318d01 GB |
916 | mark_reg_unknown_value_and_range(state->regs, |
917 | value_regno); | |
1955351d MS |
918 | /* note that reg.[id|off|range] == 0 */ |
919 | state->regs[value_regno].type = reg_type; | |
d1174416 DM |
920 | state->regs[value_regno].aux_off = 0; |
921 | state->regs[value_regno].aux_off_align = 0; | |
969bf05e | 922 | } |
17a52670 | 923 | |
1a0dc1ac | 924 | } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { |
17a52670 AS |
925 | if (off >= 0 || off < -MAX_BPF_STACK) { |
926 | verbose("invalid stack off=%d size=%d\n", off, size); | |
927 | return -EACCES; | |
928 | } | |
1be7f75d AS |
929 | if (t == BPF_WRITE) { |
930 | if (!env->allow_ptr_leaks && | |
931 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
932 | size != BPF_REG_SIZE) { | |
933 | verbose("attempt to corrupt spilled pointer on stack\n"); | |
934 | return -EACCES; | |
935 | } | |
17a52670 | 936 | err = check_stack_write(state, off, size, value_regno); |
1be7f75d | 937 | } else { |
17a52670 | 938 | err = check_stack_read(state, off, size, value_regno); |
1be7f75d | 939 | } |
969bf05e | 940 | } else if (state->regs[regno].type == PTR_TO_PACKET) { |
3a0af8fd | 941 | if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { |
969bf05e AS |
942 | verbose("cannot write into packet\n"); |
943 | return -EACCES; | |
944 | } | |
4acf6c0b BB |
945 | if (t == BPF_WRITE && value_regno >= 0 && |
946 | is_pointer_value(env, value_regno)) { | |
947 | verbose("R%d leaks addr into packet\n", value_regno); | |
948 | return -EACCES; | |
949 | } | |
969bf05e AS |
950 | err = check_packet_access(env, regno, off, size); |
951 | if (!err && t == BPF_READ && value_regno >= 0) | |
f0318d01 GB |
952 | mark_reg_unknown_value_and_range(state->regs, |
953 | value_regno); | |
17a52670 AS |
954 | } else { |
955 | verbose("R%d invalid mem access '%s'\n", | |
1a0dc1ac | 956 | regno, reg_type_str[reg->type]); |
17a52670 AS |
957 | return -EACCES; |
958 | } | |
969bf05e AS |
959 | |
960 | if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && | |
961 | state->regs[value_regno].type == UNKNOWN_VALUE) { | |
962 | /* 1 or 2 byte load zero-extends, determine the number of | |
963 | * zero upper bits. Not doing it fo 4 byte load, since | |
964 | * such values cannot be added to ptr_to_packet anyway. | |
965 | */ | |
966 | state->regs[value_regno].imm = 64 - size * 8; | |
967 | } | |
17a52670 AS |
968 | return err; |
969 | } | |
970 | ||
58e2af8b | 971 | static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 972 | { |
58e2af8b | 973 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
974 | int err; |
975 | ||
976 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
977 | insn->imm != 0) { | |
978 | verbose("BPF_XADD uses reserved fields\n"); | |
979 | return -EINVAL; | |
980 | } | |
981 | ||
982 | /* check src1 operand */ | |
983 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
984 | if (err) | |
985 | return err; | |
986 | ||
987 | /* check src2 operand */ | |
988 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
989 | if (err) | |
990 | return err; | |
991 | ||
992 | /* check whether atomic_add can read the memory */ | |
993 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
994 | BPF_SIZE(insn->code), BPF_READ, -1); | |
995 | if (err) | |
996 | return err; | |
997 | ||
998 | /* check whether atomic_add can write into the same memory */ | |
999 | return check_mem_access(env, insn->dst_reg, insn->off, | |
1000 | BPF_SIZE(insn->code), BPF_WRITE, -1); | |
1001 | } | |
1002 | ||
1003 | /* when register 'regno' is passed into function that will read 'access_size' | |
1004 | * bytes from that pointer, make sure that it's within stack boundary | |
1005 | * and all elements of stack are initialized | |
1006 | */ | |
58e2af8b | 1007 | static int check_stack_boundary(struct bpf_verifier_env *env, int regno, |
435faee1 DB |
1008 | int access_size, bool zero_size_allowed, |
1009 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1010 | { |
58e2af8b JK |
1011 | struct bpf_verifier_state *state = &env->cur_state; |
1012 | struct bpf_reg_state *regs = state->regs; | |
17a52670 AS |
1013 | int off, i; |
1014 | ||
8e2fe1d9 DB |
1015 | if (regs[regno].type != PTR_TO_STACK) { |
1016 | if (zero_size_allowed && access_size == 0 && | |
1017 | regs[regno].type == CONST_IMM && | |
1018 | regs[regno].imm == 0) | |
1019 | return 0; | |
1020 | ||
1021 | verbose("R%d type=%s expected=%s\n", regno, | |
1022 | reg_type_str[regs[regno].type], | |
1023 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 1024 | return -EACCES; |
8e2fe1d9 | 1025 | } |
17a52670 AS |
1026 | |
1027 | off = regs[regno].imm; | |
1028 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || | |
1029 | access_size <= 0) { | |
1030 | verbose("invalid stack type R%d off=%d access_size=%d\n", | |
1031 | regno, off, access_size); | |
1032 | return -EACCES; | |
1033 | } | |
1034 | ||
435faee1 DB |
1035 | if (meta && meta->raw_mode) { |
1036 | meta->access_size = access_size; | |
1037 | meta->regno = regno; | |
1038 | return 0; | |
1039 | } | |
1040 | ||
17a52670 | 1041 | for (i = 0; i < access_size; i++) { |
9c399760 | 1042 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
17a52670 AS |
1043 | verbose("invalid indirect read from stack off %d+%d size %d\n", |
1044 | off, i, access_size); | |
1045 | return -EACCES; | |
1046 | } | |
1047 | } | |
1048 | return 0; | |
1049 | } | |
1050 | ||
06c1c049 GB |
1051 | static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, |
1052 | int access_size, bool zero_size_allowed, | |
1053 | struct bpf_call_arg_meta *meta) | |
1054 | { | |
1055 | struct bpf_reg_state *regs = env->cur_state.regs; | |
1056 | ||
1057 | switch (regs[regno].type) { | |
1058 | case PTR_TO_PACKET: | |
1059 | return check_packet_access(env, regno, 0, access_size); | |
1060 | case PTR_TO_MAP_VALUE: | |
1061 | return check_map_access(env, regno, 0, access_size); | |
1062 | case PTR_TO_MAP_VALUE_ADJ: | |
1063 | return check_map_access_adj(env, regno, 0, access_size); | |
1064 | default: /* const_imm|ptr_to_stack or invalid ptr */ | |
1065 | return check_stack_boundary(env, regno, access_size, | |
1066 | zero_size_allowed, meta); | |
1067 | } | |
1068 | } | |
1069 | ||
58e2af8b | 1070 | static int check_func_arg(struct bpf_verifier_env *env, u32 regno, |
33ff9823 DB |
1071 | enum bpf_arg_type arg_type, |
1072 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1073 | { |
58e2af8b | 1074 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
6841de8b | 1075 | enum bpf_reg_type expected_type, type = reg->type; |
17a52670 AS |
1076 | int err = 0; |
1077 | ||
80f1d68c | 1078 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
1079 | return 0; |
1080 | ||
6841de8b | 1081 | if (type == NOT_INIT) { |
17a52670 AS |
1082 | verbose("R%d !read_ok\n", regno); |
1083 | return -EACCES; | |
1084 | } | |
1085 | ||
1be7f75d AS |
1086 | if (arg_type == ARG_ANYTHING) { |
1087 | if (is_pointer_value(env, regno)) { | |
1088 | verbose("R%d leaks addr into helper function\n", regno); | |
1089 | return -EACCES; | |
1090 | } | |
80f1d68c | 1091 | return 0; |
1be7f75d | 1092 | } |
80f1d68c | 1093 | |
3a0af8fd TG |
1094 | if (type == PTR_TO_PACKET && |
1095 | !may_access_direct_pkt_data(env, meta, BPF_READ)) { | |
36bbef52 | 1096 | verbose("helper access to the packet is not allowed\n"); |
6841de8b AS |
1097 | return -EACCES; |
1098 | } | |
1099 | ||
8e2fe1d9 | 1100 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
1101 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
1102 | expected_type = PTR_TO_STACK; | |
6841de8b AS |
1103 | if (type != PTR_TO_PACKET && type != expected_type) |
1104 | goto err_type; | |
39f19ebb AS |
1105 | } else if (arg_type == ARG_CONST_SIZE || |
1106 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
17a52670 | 1107 | expected_type = CONST_IMM; |
06c1c049 GB |
1108 | /* One exception. Allow UNKNOWN_VALUE registers when the |
1109 | * boundaries are known and don't cause unsafe memory accesses | |
1110 | */ | |
1111 | if (type != UNKNOWN_VALUE && type != expected_type) | |
6841de8b | 1112 | goto err_type; |
17a52670 AS |
1113 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
1114 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
1115 | if (type != expected_type) |
1116 | goto err_type; | |
608cd71a AS |
1117 | } else if (arg_type == ARG_PTR_TO_CTX) { |
1118 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
1119 | if (type != expected_type) |
1120 | goto err_type; | |
39f19ebb AS |
1121 | } else if (arg_type == ARG_PTR_TO_MEM || |
1122 | arg_type == ARG_PTR_TO_UNINIT_MEM) { | |
8e2fe1d9 DB |
1123 | expected_type = PTR_TO_STACK; |
1124 | /* One exception here. In case function allows for NULL to be | |
1125 | * passed in as argument, it's a CONST_IMM type. Final test | |
1126 | * happens during stack boundary checking. | |
1127 | */ | |
6841de8b AS |
1128 | if (type == CONST_IMM && reg->imm == 0) |
1129 | /* final test in check_stack_boundary() */; | |
5722569b GB |
1130 | else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE && |
1131 | type != PTR_TO_MAP_VALUE_ADJ && type != expected_type) | |
6841de8b | 1132 | goto err_type; |
39f19ebb | 1133 | meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; |
17a52670 AS |
1134 | } else { |
1135 | verbose("unsupported arg_type %d\n", arg_type); | |
1136 | return -EFAULT; | |
1137 | } | |
1138 | ||
17a52670 AS |
1139 | if (arg_type == ARG_CONST_MAP_PTR) { |
1140 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 1141 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
1142 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
1143 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
1144 | * check that [key, key + map->key_size) are within | |
1145 | * stack limits and initialized | |
1146 | */ | |
33ff9823 | 1147 | if (!meta->map_ptr) { |
17a52670 AS |
1148 | /* in function declaration map_ptr must come before |
1149 | * map_key, so that it's verified and known before | |
1150 | * we have to check map_key here. Otherwise it means | |
1151 | * that kernel subsystem misconfigured verifier | |
1152 | */ | |
1153 | verbose("invalid map_ptr to access map->key\n"); | |
1154 | return -EACCES; | |
1155 | } | |
6841de8b AS |
1156 | if (type == PTR_TO_PACKET) |
1157 | err = check_packet_access(env, regno, 0, | |
1158 | meta->map_ptr->key_size); | |
1159 | else | |
1160 | err = check_stack_boundary(env, regno, | |
1161 | meta->map_ptr->key_size, | |
1162 | false, NULL); | |
17a52670 AS |
1163 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1164 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1165 | * check [value, value + map->value_size) validity | |
1166 | */ | |
33ff9823 | 1167 | if (!meta->map_ptr) { |
17a52670 AS |
1168 | /* kernel subsystem misconfigured verifier */ |
1169 | verbose("invalid map_ptr to access map->value\n"); | |
1170 | return -EACCES; | |
1171 | } | |
6841de8b AS |
1172 | if (type == PTR_TO_PACKET) |
1173 | err = check_packet_access(env, regno, 0, | |
1174 | meta->map_ptr->value_size); | |
1175 | else | |
1176 | err = check_stack_boundary(env, regno, | |
1177 | meta->map_ptr->value_size, | |
1178 | false, NULL); | |
39f19ebb AS |
1179 | } else if (arg_type == ARG_CONST_SIZE || |
1180 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
1181 | bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); | |
17a52670 | 1182 | |
17a52670 AS |
1183 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1184 | * from stack pointer 'buf'. Check it | |
1185 | * note: regno == len, regno - 1 == buf | |
1186 | */ | |
1187 | if (regno == 0) { | |
1188 | /* kernel subsystem misconfigured verifier */ | |
39f19ebb | 1189 | verbose("ARG_CONST_SIZE cannot be first argument\n"); |
17a52670 AS |
1190 | return -EACCES; |
1191 | } | |
06c1c049 GB |
1192 | |
1193 | /* If the register is UNKNOWN_VALUE, the access check happens | |
1194 | * using its boundaries. Otherwise, just use its imm | |
1195 | */ | |
1196 | if (type == UNKNOWN_VALUE) { | |
1197 | /* For unprivileged variable accesses, disable raw | |
1198 | * mode so that the program is required to | |
1199 | * initialize all the memory that the helper could | |
1200 | * just partially fill up. | |
1201 | */ | |
1202 | meta = NULL; | |
1203 | ||
1204 | if (reg->min_value < 0) { | |
1205 | verbose("R%d min value is negative, either use unsigned or 'var &= const'\n", | |
1206 | regno); | |
1207 | return -EACCES; | |
1208 | } | |
1209 | ||
1210 | if (reg->min_value == 0) { | |
1211 | err = check_helper_mem_access(env, regno - 1, 0, | |
1212 | zero_size_allowed, | |
1213 | meta); | |
1214 | if (err) | |
1215 | return err; | |
1216 | } | |
1217 | ||
1218 | if (reg->max_value == BPF_REGISTER_MAX_RANGE) { | |
1219 | verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", | |
1220 | regno); | |
1221 | return -EACCES; | |
1222 | } | |
1223 | err = check_helper_mem_access(env, regno - 1, | |
1224 | reg->max_value, | |
1225 | zero_size_allowed, meta); | |
1226 | if (err) | |
1227 | return err; | |
1228 | } else { | |
1229 | /* register is CONST_IMM */ | |
1230 | err = check_helper_mem_access(env, regno - 1, reg->imm, | |
1231 | zero_size_allowed, meta); | |
1232 | } | |
17a52670 AS |
1233 | } |
1234 | ||
1235 | return err; | |
6841de8b AS |
1236 | err_type: |
1237 | verbose("R%d type=%s expected=%s\n", regno, | |
1238 | reg_type_str[type], reg_type_str[expected_type]); | |
1239 | return -EACCES; | |
17a52670 AS |
1240 | } |
1241 | ||
35578d79 KX |
1242 | static int check_map_func_compatibility(struct bpf_map *map, int func_id) |
1243 | { | |
35578d79 KX |
1244 | if (!map) |
1245 | return 0; | |
1246 | ||
6aff67c8 AS |
1247 | /* We need a two way check, first is from map perspective ... */ |
1248 | switch (map->map_type) { | |
1249 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1250 | if (func_id != BPF_FUNC_tail_call) | |
1251 | goto error; | |
1252 | break; | |
1253 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1254 | if (func_id != BPF_FUNC_perf_event_read && | |
1255 | func_id != BPF_FUNC_perf_event_output) | |
1256 | goto error; | |
1257 | break; | |
1258 | case BPF_MAP_TYPE_STACK_TRACE: | |
1259 | if (func_id != BPF_FUNC_get_stackid) | |
1260 | goto error; | |
1261 | break; | |
4ed8ec52 | 1262 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1263 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1264 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1265 | goto error; |
1266 | break; | |
56f668df | 1267 | case BPF_MAP_TYPE_ARRAY_OF_MAPS: |
bcc6b1b7 | 1268 | case BPF_MAP_TYPE_HASH_OF_MAPS: |
56f668df MKL |
1269 | if (func_id != BPF_FUNC_map_lookup_elem) |
1270 | goto error; | |
6aff67c8 AS |
1271 | default: |
1272 | break; | |
1273 | } | |
1274 | ||
1275 | /* ... and second from the function itself. */ | |
1276 | switch (func_id) { | |
1277 | case BPF_FUNC_tail_call: | |
1278 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1279 | goto error; | |
1280 | break; | |
1281 | case BPF_FUNC_perf_event_read: | |
1282 | case BPF_FUNC_perf_event_output: | |
1283 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) | |
1284 | goto error; | |
1285 | break; | |
1286 | case BPF_FUNC_get_stackid: | |
1287 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1288 | goto error; | |
1289 | break; | |
60d20f91 | 1290 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1291 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1292 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1293 | goto error; | |
1294 | break; | |
6aff67c8 AS |
1295 | default: |
1296 | break; | |
35578d79 KX |
1297 | } |
1298 | ||
1299 | return 0; | |
6aff67c8 | 1300 | error: |
ebb676da TG |
1301 | verbose("cannot pass map_type %d into func %s#%d\n", |
1302 | map->map_type, func_id_name(func_id), func_id); | |
6aff67c8 | 1303 | return -EINVAL; |
35578d79 KX |
1304 | } |
1305 | ||
435faee1 DB |
1306 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1307 | { | |
1308 | int count = 0; | |
1309 | ||
39f19ebb | 1310 | if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1311 | count++; |
39f19ebb | 1312 | if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1313 | count++; |
39f19ebb | 1314 | if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1315 | count++; |
39f19ebb | 1316 | if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1317 | count++; |
39f19ebb | 1318 | if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 DB |
1319 | count++; |
1320 | ||
1321 | return count > 1 ? -EINVAL : 0; | |
1322 | } | |
1323 | ||
58e2af8b | 1324 | static void clear_all_pkt_pointers(struct bpf_verifier_env *env) |
969bf05e | 1325 | { |
58e2af8b JK |
1326 | struct bpf_verifier_state *state = &env->cur_state; |
1327 | struct bpf_reg_state *regs = state->regs, *reg; | |
969bf05e AS |
1328 | int i; |
1329 | ||
1330 | for (i = 0; i < MAX_BPF_REG; i++) | |
1331 | if (regs[i].type == PTR_TO_PACKET || | |
1332 | regs[i].type == PTR_TO_PACKET_END) | |
1333 | mark_reg_unknown_value(regs, i); | |
1334 | ||
1335 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1336 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1337 | continue; | |
1338 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1339 | if (reg->type != PTR_TO_PACKET && | |
1340 | reg->type != PTR_TO_PACKET_END) | |
1341 | continue; | |
1342 | reg->type = UNKNOWN_VALUE; | |
1343 | reg->imm = 0; | |
1344 | } | |
1345 | } | |
1346 | ||
81ed18ab | 1347 | static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) |
17a52670 | 1348 | { |
58e2af8b | 1349 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 1350 | const struct bpf_func_proto *fn = NULL; |
58e2af8b | 1351 | struct bpf_reg_state *regs = state->regs; |
33ff9823 | 1352 | struct bpf_call_arg_meta meta; |
969bf05e | 1353 | bool changes_data; |
17a52670 AS |
1354 | int i, err; |
1355 | ||
1356 | /* find function prototype */ | |
1357 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
ebb676da | 1358 | verbose("invalid func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1359 | return -EINVAL; |
1360 | } | |
1361 | ||
1362 | if (env->prog->aux->ops->get_func_proto) | |
1363 | fn = env->prog->aux->ops->get_func_proto(func_id); | |
1364 | ||
1365 | if (!fn) { | |
ebb676da | 1366 | verbose("unknown func %s#%d\n", func_id_name(func_id), func_id); |
17a52670 AS |
1367 | return -EINVAL; |
1368 | } | |
1369 | ||
1370 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1371 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
17a52670 AS |
1372 | verbose("cannot call GPL only function from proprietary program\n"); |
1373 | return -EINVAL; | |
1374 | } | |
1375 | ||
17bedab2 | 1376 | changes_data = bpf_helper_changes_pkt_data(fn->func); |
969bf05e | 1377 | |
33ff9823 | 1378 | memset(&meta, 0, sizeof(meta)); |
36bbef52 | 1379 | meta.pkt_access = fn->pkt_access; |
33ff9823 | 1380 | |
435faee1 DB |
1381 | /* We only support one arg being in raw mode at the moment, which |
1382 | * is sufficient for the helper functions we have right now. | |
1383 | */ | |
1384 | err = check_raw_mode(fn); | |
1385 | if (err) { | |
ebb676da TG |
1386 | verbose("kernel subsystem misconfigured func %s#%d\n", |
1387 | func_id_name(func_id), func_id); | |
435faee1 DB |
1388 | return err; |
1389 | } | |
1390 | ||
17a52670 | 1391 | /* check args */ |
33ff9823 | 1392 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1393 | if (err) |
1394 | return err; | |
33ff9823 | 1395 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1396 | if (err) |
1397 | return err; | |
33ff9823 | 1398 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1399 | if (err) |
1400 | return err; | |
33ff9823 | 1401 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1402 | if (err) |
1403 | return err; | |
33ff9823 | 1404 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1405 | if (err) |
1406 | return err; | |
1407 | ||
435faee1 DB |
1408 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1409 | * is inferred from register state. | |
1410 | */ | |
1411 | for (i = 0; i < meta.access_size; i++) { | |
1412 | err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); | |
1413 | if (err) | |
1414 | return err; | |
1415 | } | |
1416 | ||
17a52670 | 1417 | /* reset caller saved regs */ |
a9789ef9 DB |
1418 | for (i = 0; i < CALLER_SAVED_REGS; i++) |
1419 | mark_reg_not_init(regs, caller_saved[i]); | |
17a52670 AS |
1420 | |
1421 | /* update return register */ | |
1422 | if (fn->ret_type == RET_INTEGER) { | |
1423 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1424 | } else if (fn->ret_type == RET_VOID) { | |
1425 | regs[BPF_REG_0].type = NOT_INIT; | |
1426 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
fad73a1a MKL |
1427 | struct bpf_insn_aux_data *insn_aux; |
1428 | ||
17a52670 | 1429 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; |
48461135 | 1430 | regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0; |
17a52670 AS |
1431 | /* remember map_ptr, so that check_map_access() |
1432 | * can check 'value_size' boundary of memory access | |
1433 | * to map element returned from bpf_map_lookup_elem() | |
1434 | */ | |
33ff9823 | 1435 | if (meta.map_ptr == NULL) { |
17a52670 AS |
1436 | verbose("kernel subsystem misconfigured verifier\n"); |
1437 | return -EINVAL; | |
1438 | } | |
33ff9823 | 1439 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
57a09bf0 | 1440 | regs[BPF_REG_0].id = ++env->id_gen; |
fad73a1a MKL |
1441 | insn_aux = &env->insn_aux_data[insn_idx]; |
1442 | if (!insn_aux->map_ptr) | |
1443 | insn_aux->map_ptr = meta.map_ptr; | |
1444 | else if (insn_aux->map_ptr != meta.map_ptr) | |
1445 | insn_aux->map_ptr = BPF_MAP_PTR_POISON; | |
17a52670 | 1446 | } else { |
ebb676da TG |
1447 | verbose("unknown return type %d of func %s#%d\n", |
1448 | fn->ret_type, func_id_name(func_id), func_id); | |
17a52670 AS |
1449 | return -EINVAL; |
1450 | } | |
04fd61ab | 1451 | |
33ff9823 | 1452 | err = check_map_func_compatibility(meta.map_ptr, func_id); |
35578d79 KX |
1453 | if (err) |
1454 | return err; | |
04fd61ab | 1455 | |
969bf05e AS |
1456 | if (changes_data) |
1457 | clear_all_pkt_pointers(env); | |
1458 | return 0; | |
1459 | } | |
1460 | ||
58e2af8b JK |
1461 | static int check_packet_ptr_add(struct bpf_verifier_env *env, |
1462 | struct bpf_insn *insn) | |
969bf05e | 1463 | { |
58e2af8b JK |
1464 | struct bpf_reg_state *regs = env->cur_state.regs; |
1465 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
1466 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; | |
1467 | struct bpf_reg_state tmp_reg; | |
969bf05e AS |
1468 | s32 imm; |
1469 | ||
1470 | if (BPF_SRC(insn->code) == BPF_K) { | |
1471 | /* pkt_ptr += imm */ | |
1472 | imm = insn->imm; | |
1473 | ||
1474 | add_imm: | |
63dfef75 | 1475 | if (imm < 0) { |
969bf05e AS |
1476 | verbose("addition of negative constant to packet pointer is not allowed\n"); |
1477 | return -EACCES; | |
1478 | } | |
1479 | if (imm >= MAX_PACKET_OFF || | |
1480 | imm + dst_reg->off >= MAX_PACKET_OFF) { | |
1481 | verbose("constant %d is too large to add to packet pointer\n", | |
1482 | imm); | |
1483 | return -EACCES; | |
1484 | } | |
1485 | /* a constant was added to pkt_ptr. | |
1486 | * Remember it while keeping the same 'id' | |
1487 | */ | |
1488 | dst_reg->off += imm; | |
1489 | } else { | |
d1174416 DM |
1490 | bool had_id; |
1491 | ||
1b9b69ec AS |
1492 | if (src_reg->type == PTR_TO_PACKET) { |
1493 | /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ | |
1494 | tmp_reg = *dst_reg; /* save r7 state */ | |
1495 | *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ | |
1496 | src_reg = &tmp_reg; /* pretend it's src_reg state */ | |
1497 | /* if the checks below reject it, the copy won't matter, | |
1498 | * since we're rejecting the whole program. If all ok, | |
1499 | * then imm22 state will be added to r7 | |
1500 | * and r7 will be pkt(id=0,off=22,r=62) while | |
1501 | * r6 will stay as pkt(id=0,off=0,r=62) | |
1502 | */ | |
1503 | } | |
1504 | ||
969bf05e AS |
1505 | if (src_reg->type == CONST_IMM) { |
1506 | /* pkt_ptr += reg where reg is known constant */ | |
1507 | imm = src_reg->imm; | |
1508 | goto add_imm; | |
1509 | } | |
1510 | /* disallow pkt_ptr += reg | |
1511 | * if reg is not uknown_value with guaranteed zero upper bits | |
1512 | * otherwise pkt_ptr may overflow and addition will become | |
1513 | * subtraction which is not allowed | |
1514 | */ | |
1515 | if (src_reg->type != UNKNOWN_VALUE) { | |
1516 | verbose("cannot add '%s' to ptr_to_packet\n", | |
1517 | reg_type_str[src_reg->type]); | |
1518 | return -EACCES; | |
1519 | } | |
1520 | if (src_reg->imm < 48) { | |
1521 | verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", | |
1522 | src_reg->imm); | |
1523 | return -EACCES; | |
1524 | } | |
d1174416 DM |
1525 | |
1526 | had_id = (dst_reg->id != 0); | |
1527 | ||
969bf05e AS |
1528 | /* dst_reg stays as pkt_ptr type and since some positive |
1529 | * integer value was added to the pointer, increment its 'id' | |
1530 | */ | |
1f415a74 | 1531 | dst_reg->id = ++env->id_gen; |
969bf05e | 1532 | |
d1174416 | 1533 | /* something was added to pkt_ptr, set range to zero */ |
6832a333 | 1534 | dst_reg->aux_off += dst_reg->off; |
969bf05e AS |
1535 | dst_reg->off = 0; |
1536 | dst_reg->range = 0; | |
d1174416 DM |
1537 | if (had_id) |
1538 | dst_reg->aux_off_align = min(dst_reg->aux_off_align, | |
1539 | src_reg->min_align); | |
1540 | else | |
1541 | dst_reg->aux_off_align = src_reg->min_align; | |
969bf05e AS |
1542 | } |
1543 | return 0; | |
1544 | } | |
1545 | ||
58e2af8b | 1546 | static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) |
969bf05e | 1547 | { |
58e2af8b JK |
1548 | struct bpf_reg_state *regs = env->cur_state.regs; |
1549 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
969bf05e AS |
1550 | u8 opcode = BPF_OP(insn->code); |
1551 | s64 imm_log2; | |
1552 | ||
1553 | /* for type == UNKNOWN_VALUE: | |
1554 | * imm > 0 -> number of zero upper bits | |
1555 | * imm == 0 -> don't track which is the same as all bits can be non-zero | |
1556 | */ | |
1557 | ||
1558 | if (BPF_SRC(insn->code) == BPF_X) { | |
58e2af8b | 1559 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; |
969bf05e AS |
1560 | |
1561 | if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && | |
1562 | dst_reg->imm && opcode == BPF_ADD) { | |
1563 | /* dreg += sreg | |
1564 | * where both have zero upper bits. Adding them | |
1565 | * can only result making one more bit non-zero | |
1566 | * in the larger value. | |
1567 | * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) | |
1568 | * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) | |
1569 | */ | |
1570 | dst_reg->imm = min(dst_reg->imm, src_reg->imm); | |
1571 | dst_reg->imm--; | |
1572 | return 0; | |
1573 | } | |
1574 | if (src_reg->type == CONST_IMM && src_reg->imm > 0 && | |
1575 | dst_reg->imm && opcode == BPF_ADD) { | |
1576 | /* dreg += sreg | |
1577 | * where dreg has zero upper bits and sreg is const. | |
1578 | * Adding them can only result making one more bit | |
1579 | * non-zero in the larger value. | |
1580 | */ | |
1581 | imm_log2 = __ilog2_u64((long long)src_reg->imm); | |
1582 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1583 | dst_reg->imm--; | |
1584 | return 0; | |
1585 | } | |
1586 | /* all other cases non supported yet, just mark dst_reg */ | |
1587 | dst_reg->imm = 0; | |
1588 | return 0; | |
1589 | } | |
1590 | ||
1591 | /* sign extend 32-bit imm into 64-bit to make sure that | |
1592 | * negative values occupy bit 63. Note ilog2() would have | |
1593 | * been incorrect, since sizeof(insn->imm) == 4 | |
1594 | */ | |
1595 | imm_log2 = __ilog2_u64((long long)insn->imm); | |
1596 | ||
1597 | if (dst_reg->imm && opcode == BPF_LSH) { | |
1598 | /* reg <<= imm | |
1599 | * if reg was a result of 2 byte load, then its imm == 48 | |
1600 | * which means that upper 48 bits are zero and shifting this reg | |
1601 | * left by 4 would mean that upper 44 bits are still zero | |
1602 | */ | |
1603 | dst_reg->imm -= insn->imm; | |
1604 | } else if (dst_reg->imm && opcode == BPF_MUL) { | |
1605 | /* reg *= imm | |
1606 | * if multiplying by 14 subtract 4 | |
1607 | * This is conservative calculation of upper zero bits. | |
1608 | * It's not trying to special case insn->imm == 1 or 0 cases | |
1609 | */ | |
1610 | dst_reg->imm -= imm_log2 + 1; | |
1611 | } else if (opcode == BPF_AND) { | |
1612 | /* reg &= imm */ | |
1613 | dst_reg->imm = 63 - imm_log2; | |
1614 | } else if (dst_reg->imm && opcode == BPF_ADD) { | |
1615 | /* reg += imm */ | |
1616 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1617 | dst_reg->imm--; | |
1618 | } else if (opcode == BPF_RSH) { | |
1619 | /* reg >>= imm | |
1620 | * which means that after right shift, upper bits will be zero | |
1621 | * note that verifier already checked that | |
1622 | * 0 <= imm < 64 for shift insn | |
1623 | */ | |
1624 | dst_reg->imm += insn->imm; | |
1625 | if (unlikely(dst_reg->imm > 64)) | |
1626 | /* some dumb code did: | |
1627 | * r2 = *(u32 *)mem; | |
1628 | * r2 >>= 32; | |
1629 | * and all bits are zero now */ | |
1630 | dst_reg->imm = 64; | |
1631 | } else { | |
1632 | /* all other alu ops, means that we don't know what will | |
1633 | * happen to the value, mark it with unknown number of zero bits | |
1634 | */ | |
1635 | dst_reg->imm = 0; | |
1636 | } | |
1637 | ||
1638 | if (dst_reg->imm < 0) { | |
1639 | /* all 64 bits of the register can contain non-zero bits | |
1640 | * and such value cannot be added to ptr_to_packet, since it | |
1641 | * may overflow, mark it as unknown to avoid further eval | |
1642 | */ | |
1643 | dst_reg->imm = 0; | |
1644 | } | |
1645 | return 0; | |
1646 | } | |
1647 | ||
58e2af8b JK |
1648 | static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, |
1649 | struct bpf_insn *insn) | |
969bf05e | 1650 | { |
58e2af8b JK |
1651 | struct bpf_reg_state *regs = env->cur_state.regs; |
1652 | struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; | |
1653 | struct bpf_reg_state *src_reg = ®s[insn->src_reg]; | |
969bf05e | 1654 | u8 opcode = BPF_OP(insn->code); |
3fadc801 | 1655 | u64 dst_imm = dst_reg->imm; |
969bf05e | 1656 | |
3fadc801 DB |
1657 | /* dst_reg->type == CONST_IMM here. Simulate execution of insns |
1658 | * containing ALU ops. Don't care about overflow or negative | |
1659 | * values, just add/sub/... them; registers are in u64. | |
969bf05e | 1660 | */ |
3fadc801 DB |
1661 | if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) { |
1662 | dst_imm += insn->imm; | |
1663 | } else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && | |
1664 | src_reg->type == CONST_IMM) { | |
1665 | dst_imm += src_reg->imm; | |
1666 | } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) { | |
1667 | dst_imm -= insn->imm; | |
1668 | } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X && | |
1669 | src_reg->type == CONST_IMM) { | |
1670 | dst_imm -= src_reg->imm; | |
1671 | } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) { | |
1672 | dst_imm *= insn->imm; | |
1673 | } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X && | |
1674 | src_reg->type == CONST_IMM) { | |
1675 | dst_imm *= src_reg->imm; | |
1676 | } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) { | |
1677 | dst_imm |= insn->imm; | |
1678 | } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X && | |
1679 | src_reg->type == CONST_IMM) { | |
1680 | dst_imm |= src_reg->imm; | |
1681 | } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) { | |
1682 | dst_imm &= insn->imm; | |
1683 | } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X && | |
1684 | src_reg->type == CONST_IMM) { | |
1685 | dst_imm &= src_reg->imm; | |
1686 | } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) { | |
1687 | dst_imm >>= insn->imm; | |
1688 | } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X && | |
1689 | src_reg->type == CONST_IMM) { | |
1690 | dst_imm >>= src_reg->imm; | |
1691 | } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) { | |
1692 | dst_imm <<= insn->imm; | |
1693 | } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X && | |
1694 | src_reg->type == CONST_IMM) { | |
1695 | dst_imm <<= src_reg->imm; | |
1696 | } else { | |
969bf05e | 1697 | mark_reg_unknown_value(regs, insn->dst_reg); |
3fadc801 DB |
1698 | goto out; |
1699 | } | |
1700 | ||
1701 | dst_reg->imm = dst_imm; | |
1702 | out: | |
17a52670 AS |
1703 | return 0; |
1704 | } | |
1705 | ||
48461135 JB |
1706 | static void check_reg_overflow(struct bpf_reg_state *reg) |
1707 | { | |
1708 | if (reg->max_value > BPF_REGISTER_MAX_RANGE) | |
1709 | reg->max_value = BPF_REGISTER_MAX_RANGE; | |
f23cc643 JB |
1710 | if (reg->min_value < BPF_REGISTER_MIN_RANGE || |
1711 | reg->min_value > BPF_REGISTER_MAX_RANGE) | |
48461135 JB |
1712 | reg->min_value = BPF_REGISTER_MIN_RANGE; |
1713 | } | |
1714 | ||
d1174416 DM |
1715 | static u32 calc_align(u32 imm) |
1716 | { | |
1717 | if (!imm) | |
1718 | return 1U << 31; | |
1719 | return imm - ((imm - 1) & imm); | |
1720 | } | |
1721 | ||
48461135 JB |
1722 | static void adjust_reg_min_max_vals(struct bpf_verifier_env *env, |
1723 | struct bpf_insn *insn) | |
1724 | { | |
1725 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; | |
f23cc643 JB |
1726 | s64 min_val = BPF_REGISTER_MIN_RANGE; |
1727 | u64 max_val = BPF_REGISTER_MAX_RANGE; | |
48461135 | 1728 | u8 opcode = BPF_OP(insn->code); |
d1174416 | 1729 | u32 dst_align, src_align; |
48461135 JB |
1730 | |
1731 | dst_reg = ®s[insn->dst_reg]; | |
d1174416 | 1732 | src_align = 0; |
48461135 JB |
1733 | if (BPF_SRC(insn->code) == BPF_X) { |
1734 | check_reg_overflow(®s[insn->src_reg]); | |
1735 | min_val = regs[insn->src_reg].min_value; | |
1736 | max_val = regs[insn->src_reg].max_value; | |
1737 | ||
1738 | /* If the source register is a random pointer then the | |
1739 | * min_value/max_value values represent the range of the known | |
1740 | * accesses into that value, not the actual min/max value of the | |
1741 | * register itself. In this case we have to reset the reg range | |
1742 | * values so we know it is not safe to look at. | |
1743 | */ | |
1744 | if (regs[insn->src_reg].type != CONST_IMM && | |
1745 | regs[insn->src_reg].type != UNKNOWN_VALUE) { | |
1746 | min_val = BPF_REGISTER_MIN_RANGE; | |
1747 | max_val = BPF_REGISTER_MAX_RANGE; | |
d1174416 DM |
1748 | src_align = 0; |
1749 | } else { | |
1750 | src_align = regs[insn->src_reg].min_align; | |
48461135 JB |
1751 | } |
1752 | } else if (insn->imm < BPF_REGISTER_MAX_RANGE && | |
1753 | (s64)insn->imm > BPF_REGISTER_MIN_RANGE) { | |
1754 | min_val = max_val = insn->imm; | |
d1174416 | 1755 | src_align = calc_align(insn->imm); |
48461135 JB |
1756 | } |
1757 | ||
d1174416 DM |
1758 | dst_align = dst_reg->min_align; |
1759 | ||
48461135 JB |
1760 | /* We don't know anything about what was done to this register, mark it |
1761 | * as unknown. | |
1762 | */ | |
1763 | if (min_val == BPF_REGISTER_MIN_RANGE && | |
1764 | max_val == BPF_REGISTER_MAX_RANGE) { | |
1765 | reset_reg_range_values(regs, insn->dst_reg); | |
1766 | return; | |
1767 | } | |
1768 | ||
f23cc643 JB |
1769 | /* If one of our values was at the end of our ranges then we can't just |
1770 | * do our normal operations to the register, we need to set the values | |
1771 | * to the min/max since they are undefined. | |
1772 | */ | |
1773 | if (min_val == BPF_REGISTER_MIN_RANGE) | |
1774 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
1775 | if (max_val == BPF_REGISTER_MAX_RANGE) | |
1776 | dst_reg->max_value = BPF_REGISTER_MAX_RANGE; | |
1777 | ||
48461135 JB |
1778 | switch (opcode) { |
1779 | case BPF_ADD: | |
f23cc643 JB |
1780 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1781 | dst_reg->min_value += min_val; | |
1782 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1783 | dst_reg->max_value += max_val; | |
d1174416 | 1784 | dst_reg->min_align = min(src_align, dst_align); |
48461135 JB |
1785 | break; |
1786 | case BPF_SUB: | |
f23cc643 JB |
1787 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1788 | dst_reg->min_value -= min_val; | |
1789 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1790 | dst_reg->max_value -= max_val; | |
d1174416 | 1791 | dst_reg->min_align = min(src_align, dst_align); |
48461135 JB |
1792 | break; |
1793 | case BPF_MUL: | |
f23cc643 JB |
1794 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) |
1795 | dst_reg->min_value *= min_val; | |
1796 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) | |
1797 | dst_reg->max_value *= max_val; | |
d1174416 | 1798 | dst_reg->min_align = max(src_align, dst_align); |
48461135 JB |
1799 | break; |
1800 | case BPF_AND: | |
f23cc643 JB |
1801 | /* Disallow AND'ing of negative numbers, ain't nobody got time |
1802 | * for that. Otherwise the minimum is 0 and the max is the max | |
1803 | * value we could AND against. | |
1804 | */ | |
1805 | if (min_val < 0) | |
1806 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; | |
1807 | else | |
1808 | dst_reg->min_value = 0; | |
48461135 | 1809 | dst_reg->max_value = max_val; |
d1174416 | 1810 | dst_reg->min_align = max(src_align, dst_align); |
48461135 JB |
1811 | break; |
1812 | case BPF_LSH: | |
1813 | /* Gotta have special overflow logic here, if we're shifting | |
1814 | * more than MAX_RANGE then just assume we have an invalid | |
1815 | * range. | |
1816 | */ | |
d1174416 | 1817 | if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) { |
48461135 | 1818 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; |
d1174416 DM |
1819 | dst_reg->min_align = 1; |
1820 | } else { | |
1821 | if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) | |
1822 | dst_reg->min_value <<= min_val; | |
1823 | if (!dst_reg->min_align) | |
1824 | dst_reg->min_align = 1; | |
1825 | dst_reg->min_align <<= min_val; | |
1826 | } | |
48461135 JB |
1827 | if (max_val > ilog2(BPF_REGISTER_MAX_RANGE)) |
1828 | dst_reg->max_value = BPF_REGISTER_MAX_RANGE; | |
f23cc643 | 1829 | else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) |
48461135 JB |
1830 | dst_reg->max_value <<= max_val; |
1831 | break; | |
1832 | case BPF_RSH: | |
f23cc643 JB |
1833 | /* RSH by a negative number is undefined, and the BPF_RSH is an |
1834 | * unsigned shift, so make the appropriate casts. | |
48461135 | 1835 | */ |
d1174416 | 1836 | if (min_val < 0 || dst_reg->min_value < 0) { |
f23cc643 | 1837 | dst_reg->min_value = BPF_REGISTER_MIN_RANGE; |
d1174416 | 1838 | } else { |
f23cc643 JB |
1839 | dst_reg->min_value = |
1840 | (u64)(dst_reg->min_value) >> min_val; | |
d1174416 DM |
1841 | } |
1842 | if (min_val < 0) { | |
1843 | dst_reg->min_align = 1; | |
1844 | } else { | |
1845 | dst_reg->min_align >>= (u64) min_val; | |
1846 | if (!dst_reg->min_align) | |
1847 | dst_reg->min_align = 1; | |
1848 | } | |
f23cc643 JB |
1849 | if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) |
1850 | dst_reg->max_value >>= max_val; | |
48461135 JB |
1851 | break; |
1852 | default: | |
1853 | reset_reg_range_values(regs, insn->dst_reg); | |
1854 | break; | |
1855 | } | |
1856 | ||
1857 | check_reg_overflow(dst_reg); | |
1858 | } | |
1859 | ||
17a52670 | 1860 | /* check validity of 32-bit and 64-bit arithmetic operations */ |
58e2af8b | 1861 | static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 1862 | { |
58e2af8b | 1863 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1864 | u8 opcode = BPF_OP(insn->code); |
1865 | int err; | |
1866 | ||
1867 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
1868 | if (opcode == BPF_NEG) { | |
1869 | if (BPF_SRC(insn->code) != 0 || | |
1870 | insn->src_reg != BPF_REG_0 || | |
1871 | insn->off != 0 || insn->imm != 0) { | |
1872 | verbose("BPF_NEG uses reserved fields\n"); | |
1873 | return -EINVAL; | |
1874 | } | |
1875 | } else { | |
1876 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
1877 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { | |
1878 | verbose("BPF_END uses reserved fields\n"); | |
1879 | return -EINVAL; | |
1880 | } | |
1881 | } | |
1882 | ||
1883 | /* check src operand */ | |
1884 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1885 | if (err) | |
1886 | return err; | |
1887 | ||
1be7f75d AS |
1888 | if (is_pointer_value(env, insn->dst_reg)) { |
1889 | verbose("R%d pointer arithmetic prohibited\n", | |
1890 | insn->dst_reg); | |
1891 | return -EACCES; | |
1892 | } | |
1893 | ||
17a52670 AS |
1894 | /* check dest operand */ |
1895 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1896 | if (err) | |
1897 | return err; | |
1898 | ||
1899 | } else if (opcode == BPF_MOV) { | |
1900 | ||
1901 | if (BPF_SRC(insn->code) == BPF_X) { | |
1902 | if (insn->imm != 0 || insn->off != 0) { | |
1903 | verbose("BPF_MOV uses reserved fields\n"); | |
1904 | return -EINVAL; | |
1905 | } | |
1906 | ||
1907 | /* check src operand */ | |
1908 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1909 | if (err) | |
1910 | return err; | |
1911 | } else { | |
1912 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1913 | verbose("BPF_MOV uses reserved fields\n"); | |
1914 | return -EINVAL; | |
1915 | } | |
1916 | } | |
1917 | ||
1918 | /* check dest operand */ | |
1919 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1920 | if (err) | |
1921 | return err; | |
1922 | ||
48461135 JB |
1923 | /* we are setting our register to something new, we need to |
1924 | * reset its range values. | |
1925 | */ | |
1926 | reset_reg_range_values(regs, insn->dst_reg); | |
1927 | ||
17a52670 AS |
1928 | if (BPF_SRC(insn->code) == BPF_X) { |
1929 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
1930 | /* case: R1 = R2 | |
1931 | * copy register state to dest reg | |
1932 | */ | |
1933 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
1934 | } else { | |
1be7f75d AS |
1935 | if (is_pointer_value(env, insn->src_reg)) { |
1936 | verbose("R%d partial copy of pointer\n", | |
1937 | insn->src_reg); | |
1938 | return -EACCES; | |
1939 | } | |
57a09bf0 | 1940 | mark_reg_unknown_value(regs, insn->dst_reg); |
17a52670 AS |
1941 | } |
1942 | } else { | |
1943 | /* case: R = imm | |
1944 | * remember the value we stored into this reg | |
1945 | */ | |
1946 | regs[insn->dst_reg].type = CONST_IMM; | |
1947 | regs[insn->dst_reg].imm = insn->imm; | |
48461135 JB |
1948 | regs[insn->dst_reg].max_value = insn->imm; |
1949 | regs[insn->dst_reg].min_value = insn->imm; | |
d1174416 | 1950 | regs[insn->dst_reg].min_align = calc_align(insn->imm); |
17a52670 AS |
1951 | } |
1952 | ||
1953 | } else if (opcode > BPF_END) { | |
1954 | verbose("invalid BPF_ALU opcode %x\n", opcode); | |
1955 | return -EINVAL; | |
1956 | ||
1957 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
1958 | ||
17a52670 AS |
1959 | if (BPF_SRC(insn->code) == BPF_X) { |
1960 | if (insn->imm != 0 || insn->off != 0) { | |
1961 | verbose("BPF_ALU uses reserved fields\n"); | |
1962 | return -EINVAL; | |
1963 | } | |
1964 | /* check src1 operand */ | |
1965 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1966 | if (err) | |
1967 | return err; | |
1968 | } else { | |
1969 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1970 | verbose("BPF_ALU uses reserved fields\n"); | |
1971 | return -EINVAL; | |
1972 | } | |
1973 | } | |
1974 | ||
1975 | /* check src2 operand */ | |
1976 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1977 | if (err) | |
1978 | return err; | |
1979 | ||
1980 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
1981 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
1982 | verbose("div by zero\n"); | |
1983 | return -EINVAL; | |
1984 | } | |
1985 | ||
229394e8 RV |
1986 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
1987 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
1988 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
1989 | ||
1990 | if (insn->imm < 0 || insn->imm >= size) { | |
1991 | verbose("invalid shift %d\n", insn->imm); | |
1992 | return -EINVAL; | |
1993 | } | |
1994 | } | |
1995 | ||
1a0dc1ac AS |
1996 | /* check dest operand */ |
1997 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
1998 | if (err) | |
1999 | return err; | |
2000 | ||
2001 | dst_reg = ®s[insn->dst_reg]; | |
2002 | ||
48461135 JB |
2003 | /* first we want to adjust our ranges. */ |
2004 | adjust_reg_min_max_vals(env, insn); | |
2005 | ||
17a52670 AS |
2006 | /* pattern match 'bpf_add Rx, imm' instruction */ |
2007 | if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && | |
1a0dc1ac AS |
2008 | dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { |
2009 | dst_reg->type = PTR_TO_STACK; | |
2010 | dst_reg->imm = insn->imm; | |
2011 | return 0; | |
332270fd YS |
2012 | } else if (opcode == BPF_ADD && |
2013 | BPF_CLASS(insn->code) == BPF_ALU64 && | |
2014 | dst_reg->type == PTR_TO_STACK && | |
2015 | ((BPF_SRC(insn->code) == BPF_X && | |
2016 | regs[insn->src_reg].type == CONST_IMM) || | |
2017 | BPF_SRC(insn->code) == BPF_K)) { | |
2018 | if (BPF_SRC(insn->code) == BPF_X) | |
2019 | dst_reg->imm += regs[insn->src_reg].imm; | |
2020 | else | |
2021 | dst_reg->imm += insn->imm; | |
2022 | return 0; | |
969bf05e AS |
2023 | } else if (opcode == BPF_ADD && |
2024 | BPF_CLASS(insn->code) == BPF_ALU64 && | |
1b9b69ec AS |
2025 | (dst_reg->type == PTR_TO_PACKET || |
2026 | (BPF_SRC(insn->code) == BPF_X && | |
2027 | regs[insn->src_reg].type == PTR_TO_PACKET))) { | |
969bf05e AS |
2028 | /* ptr_to_packet += K|X */ |
2029 | return check_packet_ptr_add(env, insn); | |
2030 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
2031 | dst_reg->type == UNKNOWN_VALUE && | |
2032 | env->allow_ptr_leaks) { | |
2033 | /* unknown += K|X */ | |
2034 | return evaluate_reg_alu(env, insn); | |
2035 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
2036 | dst_reg->type == CONST_IMM && | |
2037 | env->allow_ptr_leaks) { | |
2038 | /* reg_imm += K|X */ | |
2039 | return evaluate_reg_imm_alu(env, insn); | |
1be7f75d AS |
2040 | } else if (is_pointer_value(env, insn->dst_reg)) { |
2041 | verbose("R%d pointer arithmetic prohibited\n", | |
2042 | insn->dst_reg); | |
2043 | return -EACCES; | |
2044 | } else if (BPF_SRC(insn->code) == BPF_X && | |
2045 | is_pointer_value(env, insn->src_reg)) { | |
2046 | verbose("R%d pointer arithmetic prohibited\n", | |
2047 | insn->src_reg); | |
2048 | return -EACCES; | |
2049 | } | |
17a52670 | 2050 | |
48461135 JB |
2051 | /* If we did pointer math on a map value then just set it to our |
2052 | * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or | |
2053 | * loads to this register appropriately, otherwise just mark the | |
2054 | * register as unknown. | |
2055 | */ | |
2056 | if (env->allow_ptr_leaks && | |
fce366a9 | 2057 | BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD && |
48461135 JB |
2058 | (dst_reg->type == PTR_TO_MAP_VALUE || |
2059 | dst_reg->type == PTR_TO_MAP_VALUE_ADJ)) | |
2060 | dst_reg->type = PTR_TO_MAP_VALUE_ADJ; | |
2061 | else | |
2062 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
2063 | } |
2064 | ||
2065 | return 0; | |
2066 | } | |
2067 | ||
58e2af8b JK |
2068 | static void find_good_pkt_pointers(struct bpf_verifier_state *state, |
2069 | struct bpf_reg_state *dst_reg) | |
969bf05e | 2070 | { |
58e2af8b | 2071 | struct bpf_reg_state *regs = state->regs, *reg; |
969bf05e | 2072 | int i; |
2d2be8ca DB |
2073 | |
2074 | /* LLVM can generate two kind of checks: | |
2075 | * | |
2076 | * Type 1: | |
2077 | * | |
2078 | * r2 = r3; | |
2079 | * r2 += 8; | |
2080 | * if (r2 > pkt_end) goto <handle exception> | |
2081 | * <access okay> | |
2082 | * | |
2083 | * Where: | |
2084 | * r2 == dst_reg, pkt_end == src_reg | |
2085 | * r2=pkt(id=n,off=8,r=0) | |
2086 | * r3=pkt(id=n,off=0,r=0) | |
2087 | * | |
2088 | * Type 2: | |
2089 | * | |
2090 | * r2 = r3; | |
2091 | * r2 += 8; | |
2092 | * if (pkt_end >= r2) goto <access okay> | |
2093 | * <handle exception> | |
2094 | * | |
2095 | * Where: | |
2096 | * pkt_end == dst_reg, r2 == src_reg | |
2097 | * r2=pkt(id=n,off=8,r=0) | |
2098 | * r3=pkt(id=n,off=0,r=0) | |
2099 | * | |
2100 | * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
2101 | * so that range of bytes [r3, r3 + 8) is safe to access. | |
969bf05e | 2102 | */ |
2d2be8ca | 2103 | |
969bf05e AS |
2104 | for (i = 0; i < MAX_BPF_REG; i++) |
2105 | if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) | |
b1977682 AS |
2106 | /* keep the maximum range already checked */ |
2107 | regs[i].range = max(regs[i].range, dst_reg->off); | |
969bf05e AS |
2108 | |
2109 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2110 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2111 | continue; | |
2112 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
2113 | if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) | |
b1977682 | 2114 | reg->range = max(reg->range, dst_reg->off); |
969bf05e AS |
2115 | } |
2116 | } | |
2117 | ||
48461135 JB |
2118 | /* Adjusts the register min/max values in the case that the dst_reg is the |
2119 | * variable register that we are working on, and src_reg is a constant or we're | |
2120 | * simply doing a BPF_K check. | |
2121 | */ | |
2122 | static void reg_set_min_max(struct bpf_reg_state *true_reg, | |
2123 | struct bpf_reg_state *false_reg, u64 val, | |
2124 | u8 opcode) | |
2125 | { | |
2126 | switch (opcode) { | |
2127 | case BPF_JEQ: | |
2128 | /* If this is false then we know nothing Jon Snow, but if it is | |
2129 | * true then we know for sure. | |
2130 | */ | |
2131 | true_reg->max_value = true_reg->min_value = val; | |
2132 | break; | |
2133 | case BPF_JNE: | |
2134 | /* If this is true we know nothing Jon Snow, but if it is false | |
2135 | * we know the value for sure; | |
2136 | */ | |
2137 | false_reg->max_value = false_reg->min_value = val; | |
2138 | break; | |
2139 | case BPF_JGT: | |
2140 | /* Unsigned comparison, the minimum value is 0. */ | |
2141 | false_reg->min_value = 0; | |
7e57fbb2 | 2142 | /* fallthrough */ |
48461135 JB |
2143 | case BPF_JSGT: |
2144 | /* If this is false then we know the maximum val is val, | |
2145 | * otherwise we know the min val is val+1. | |
2146 | */ | |
2147 | false_reg->max_value = val; | |
2148 | true_reg->min_value = val + 1; | |
2149 | break; | |
2150 | case BPF_JGE: | |
2151 | /* Unsigned comparison, the minimum value is 0. */ | |
2152 | false_reg->min_value = 0; | |
7e57fbb2 | 2153 | /* fallthrough */ |
48461135 JB |
2154 | case BPF_JSGE: |
2155 | /* If this is false then we know the maximum value is val - 1, | |
2156 | * otherwise we know the mimimum value is val. | |
2157 | */ | |
2158 | false_reg->max_value = val - 1; | |
2159 | true_reg->min_value = val; | |
2160 | break; | |
2161 | default: | |
2162 | break; | |
2163 | } | |
2164 | ||
2165 | check_reg_overflow(false_reg); | |
2166 | check_reg_overflow(true_reg); | |
2167 | } | |
2168 | ||
2169 | /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg | |
2170 | * is the variable reg. | |
2171 | */ | |
2172 | static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, | |
2173 | struct bpf_reg_state *false_reg, u64 val, | |
2174 | u8 opcode) | |
2175 | { | |
2176 | switch (opcode) { | |
2177 | case BPF_JEQ: | |
2178 | /* If this is false then we know nothing Jon Snow, but if it is | |
2179 | * true then we know for sure. | |
2180 | */ | |
2181 | true_reg->max_value = true_reg->min_value = val; | |
2182 | break; | |
2183 | case BPF_JNE: | |
2184 | /* If this is true we know nothing Jon Snow, but if it is false | |
2185 | * we know the value for sure; | |
2186 | */ | |
2187 | false_reg->max_value = false_reg->min_value = val; | |
2188 | break; | |
2189 | case BPF_JGT: | |
2190 | /* Unsigned comparison, the minimum value is 0. */ | |
2191 | true_reg->min_value = 0; | |
7e57fbb2 | 2192 | /* fallthrough */ |
48461135 JB |
2193 | case BPF_JSGT: |
2194 | /* | |
2195 | * If this is false, then the val is <= the register, if it is | |
2196 | * true the register <= to the val. | |
2197 | */ | |
2198 | false_reg->min_value = val; | |
2199 | true_reg->max_value = val - 1; | |
2200 | break; | |
2201 | case BPF_JGE: | |
2202 | /* Unsigned comparison, the minimum value is 0. */ | |
2203 | true_reg->min_value = 0; | |
7e57fbb2 | 2204 | /* fallthrough */ |
48461135 JB |
2205 | case BPF_JSGE: |
2206 | /* If this is false then constant < register, if it is true then | |
2207 | * the register < constant. | |
2208 | */ | |
2209 | false_reg->min_value = val + 1; | |
2210 | true_reg->max_value = val; | |
2211 | break; | |
2212 | default: | |
2213 | break; | |
2214 | } | |
2215 | ||
2216 | check_reg_overflow(false_reg); | |
2217 | check_reg_overflow(true_reg); | |
2218 | } | |
2219 | ||
57a09bf0 TG |
2220 | static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, |
2221 | enum bpf_reg_type type) | |
2222 | { | |
2223 | struct bpf_reg_state *reg = ®s[regno]; | |
2224 | ||
2225 | if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { | |
56f668df MKL |
2226 | if (type == UNKNOWN_VALUE) { |
2227 | __mark_reg_unknown_value(regs, regno); | |
2228 | } else if (reg->map_ptr->inner_map_meta) { | |
2229 | reg->type = CONST_PTR_TO_MAP; | |
2230 | reg->map_ptr = reg->map_ptr->inner_map_meta; | |
2231 | } else { | |
2232 | reg->type = type; | |
2233 | } | |
a08dd0da DB |
2234 | /* We don't need id from this point onwards anymore, thus we |
2235 | * should better reset it, so that state pruning has chances | |
2236 | * to take effect. | |
2237 | */ | |
2238 | reg->id = 0; | |
57a09bf0 TG |
2239 | } |
2240 | } | |
2241 | ||
2242 | /* The logic is similar to find_good_pkt_pointers(), both could eventually | |
2243 | * be folded together at some point. | |
2244 | */ | |
2245 | static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, | |
2246 | enum bpf_reg_type type) | |
2247 | { | |
2248 | struct bpf_reg_state *regs = state->regs; | |
a08dd0da | 2249 | u32 id = regs[regno].id; |
57a09bf0 TG |
2250 | int i; |
2251 | ||
2252 | for (i = 0; i < MAX_BPF_REG; i++) | |
a08dd0da | 2253 | mark_map_reg(regs, i, id, type); |
57a09bf0 TG |
2254 | |
2255 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2256 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2257 | continue; | |
a08dd0da | 2258 | mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type); |
57a09bf0 TG |
2259 | } |
2260 | } | |
2261 | ||
58e2af8b | 2262 | static int check_cond_jmp_op(struct bpf_verifier_env *env, |
17a52670 AS |
2263 | struct bpf_insn *insn, int *insn_idx) |
2264 | { | |
58e2af8b JK |
2265 | struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; |
2266 | struct bpf_reg_state *regs = this_branch->regs, *dst_reg; | |
17a52670 AS |
2267 | u8 opcode = BPF_OP(insn->code); |
2268 | int err; | |
2269 | ||
2270 | if (opcode > BPF_EXIT) { | |
2271 | verbose("invalid BPF_JMP opcode %x\n", opcode); | |
2272 | return -EINVAL; | |
2273 | } | |
2274 | ||
2275 | if (BPF_SRC(insn->code) == BPF_X) { | |
2276 | if (insn->imm != 0) { | |
2277 | verbose("BPF_JMP uses reserved fields\n"); | |
2278 | return -EINVAL; | |
2279 | } | |
2280 | ||
2281 | /* check src1 operand */ | |
2282 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2283 | if (err) | |
2284 | return err; | |
1be7f75d AS |
2285 | |
2286 | if (is_pointer_value(env, insn->src_reg)) { | |
2287 | verbose("R%d pointer comparison prohibited\n", | |
2288 | insn->src_reg); | |
2289 | return -EACCES; | |
2290 | } | |
17a52670 AS |
2291 | } else { |
2292 | if (insn->src_reg != BPF_REG_0) { | |
2293 | verbose("BPF_JMP uses reserved fields\n"); | |
2294 | return -EINVAL; | |
2295 | } | |
2296 | } | |
2297 | ||
2298 | /* check src2 operand */ | |
2299 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2300 | if (err) | |
2301 | return err; | |
2302 | ||
1a0dc1ac AS |
2303 | dst_reg = ®s[insn->dst_reg]; |
2304 | ||
17a52670 AS |
2305 | /* detect if R == 0 where R was initialized to zero earlier */ |
2306 | if (BPF_SRC(insn->code) == BPF_K && | |
2307 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
1a0dc1ac | 2308 | dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { |
17a52670 AS |
2309 | if (opcode == BPF_JEQ) { |
2310 | /* if (imm == imm) goto pc+off; | |
2311 | * only follow the goto, ignore fall-through | |
2312 | */ | |
2313 | *insn_idx += insn->off; | |
2314 | return 0; | |
2315 | } else { | |
2316 | /* if (imm != imm) goto pc+off; | |
2317 | * only follow fall-through branch, since | |
2318 | * that's where the program will go | |
2319 | */ | |
2320 | return 0; | |
2321 | } | |
2322 | } | |
2323 | ||
2324 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
2325 | if (!other_branch) | |
2326 | return -EFAULT; | |
2327 | ||
48461135 JB |
2328 | /* detect if we are comparing against a constant value so we can adjust |
2329 | * our min/max values for our dst register. | |
2330 | */ | |
2331 | if (BPF_SRC(insn->code) == BPF_X) { | |
2332 | if (regs[insn->src_reg].type == CONST_IMM) | |
2333 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2334 | dst_reg, regs[insn->src_reg].imm, | |
2335 | opcode); | |
2336 | else if (dst_reg->type == CONST_IMM) | |
2337 | reg_set_min_max_inv(&other_branch->regs[insn->src_reg], | |
2338 | ®s[insn->src_reg], dst_reg->imm, | |
2339 | opcode); | |
2340 | } else { | |
2341 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2342 | dst_reg, insn->imm, opcode); | |
2343 | } | |
2344 | ||
58e2af8b | 2345 | /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ |
17a52670 | 2346 | if (BPF_SRC(insn->code) == BPF_K && |
1a0dc1ac AS |
2347 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
2348 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
57a09bf0 TG |
2349 | /* Mark all identical map registers in each branch as either |
2350 | * safe or unknown depending R == 0 or R != 0 conditional. | |
2351 | */ | |
2352 | mark_map_regs(this_branch, insn->dst_reg, | |
2353 | opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE); | |
2354 | mark_map_regs(other_branch, insn->dst_reg, | |
2355 | opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE); | |
969bf05e AS |
2356 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
2357 | dst_reg->type == PTR_TO_PACKET && | |
2358 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
2d2be8ca DB |
2359 | find_good_pkt_pointers(this_branch, dst_reg); |
2360 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && | |
2361 | dst_reg->type == PTR_TO_PACKET_END && | |
2362 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
2363 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg]); | |
1be7f75d AS |
2364 | } else if (is_pointer_value(env, insn->dst_reg)) { |
2365 | verbose("R%d pointer comparison prohibited\n", insn->dst_reg); | |
2366 | return -EACCES; | |
17a52670 AS |
2367 | } |
2368 | if (log_level) | |
2d2be8ca | 2369 | print_verifier_state(this_branch); |
17a52670 AS |
2370 | return 0; |
2371 | } | |
2372 | ||
0246e64d AS |
2373 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
2374 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
2375 | { | |
2376 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
2377 | ||
2378 | return (struct bpf_map *) (unsigned long) imm64; | |
2379 | } | |
2380 | ||
17a52670 | 2381 | /* verify BPF_LD_IMM64 instruction */ |
58e2af8b | 2382 | static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2383 | { |
58e2af8b | 2384 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2385 | int err; |
2386 | ||
2387 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
2388 | verbose("invalid BPF_LD_IMM insn\n"); | |
2389 | return -EINVAL; | |
2390 | } | |
2391 | if (insn->off != 0) { | |
2392 | verbose("BPF_LD_IMM64 uses reserved fields\n"); | |
2393 | return -EINVAL; | |
2394 | } | |
2395 | ||
2396 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
2397 | if (err) | |
2398 | return err; | |
2399 | ||
6b173873 | 2400 | if (insn->src_reg == 0) { |
6b173873 JK |
2401 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; |
2402 | ||
6b173873 JK |
2403 | regs[insn->dst_reg].type = CONST_IMM; |
2404 | regs[insn->dst_reg].imm = imm; | |
17a52670 | 2405 | return 0; |
6b173873 | 2406 | } |
17a52670 AS |
2407 | |
2408 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
2409 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
2410 | ||
2411 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
2412 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
2413 | return 0; | |
2414 | } | |
2415 | ||
96be4325 DB |
2416 | static bool may_access_skb(enum bpf_prog_type type) |
2417 | { | |
2418 | switch (type) { | |
2419 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
2420 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 2421 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
2422 | return true; |
2423 | default: | |
2424 | return false; | |
2425 | } | |
2426 | } | |
2427 | ||
ddd872bc AS |
2428 | /* verify safety of LD_ABS|LD_IND instructions: |
2429 | * - they can only appear in the programs where ctx == skb | |
2430 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
2431 | * preserve R6-R9, and store return value into R0 | |
2432 | * | |
2433 | * Implicit input: | |
2434 | * ctx == skb == R6 == CTX | |
2435 | * | |
2436 | * Explicit input: | |
2437 | * SRC == any register | |
2438 | * IMM == 32-bit immediate | |
2439 | * | |
2440 | * Output: | |
2441 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
2442 | */ | |
58e2af8b | 2443 | static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) |
ddd872bc | 2444 | { |
58e2af8b | 2445 | struct bpf_reg_state *regs = env->cur_state.regs; |
ddd872bc | 2446 | u8 mode = BPF_MODE(insn->code); |
ddd872bc AS |
2447 | int i, err; |
2448 | ||
24701ece | 2449 | if (!may_access_skb(env->prog->type)) { |
1a0dc1ac | 2450 | verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
2451 | return -EINVAL; |
2452 | } | |
2453 | ||
2454 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 2455 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 2456 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
1a0dc1ac | 2457 | verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
2458 | return -EINVAL; |
2459 | } | |
2460 | ||
2461 | /* check whether implicit source operand (register R6) is readable */ | |
2462 | err = check_reg_arg(regs, BPF_REG_6, SRC_OP); | |
2463 | if (err) | |
2464 | return err; | |
2465 | ||
2466 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
2467 | verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
2468 | return -EINVAL; | |
2469 | } | |
2470 | ||
2471 | if (mode == BPF_IND) { | |
2472 | /* check explicit source operand */ | |
2473 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2474 | if (err) | |
2475 | return err; | |
2476 | } | |
2477 | ||
2478 | /* reset caller saved regs to unreadable */ | |
a9789ef9 DB |
2479 | for (i = 0; i < CALLER_SAVED_REGS; i++) |
2480 | mark_reg_not_init(regs, caller_saved[i]); | |
ddd872bc AS |
2481 | |
2482 | /* mark destination R0 register as readable, since it contains | |
2483 | * the value fetched from the packet | |
2484 | */ | |
2485 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
2486 | return 0; | |
2487 | } | |
2488 | ||
475fb78f AS |
2489 | /* non-recursive DFS pseudo code |
2490 | * 1 procedure DFS-iterative(G,v): | |
2491 | * 2 label v as discovered | |
2492 | * 3 let S be a stack | |
2493 | * 4 S.push(v) | |
2494 | * 5 while S is not empty | |
2495 | * 6 t <- S.pop() | |
2496 | * 7 if t is what we're looking for: | |
2497 | * 8 return t | |
2498 | * 9 for all edges e in G.adjacentEdges(t) do | |
2499 | * 10 if edge e is already labelled | |
2500 | * 11 continue with the next edge | |
2501 | * 12 w <- G.adjacentVertex(t,e) | |
2502 | * 13 if vertex w is not discovered and not explored | |
2503 | * 14 label e as tree-edge | |
2504 | * 15 label w as discovered | |
2505 | * 16 S.push(w) | |
2506 | * 17 continue at 5 | |
2507 | * 18 else if vertex w is discovered | |
2508 | * 19 label e as back-edge | |
2509 | * 20 else | |
2510 | * 21 // vertex w is explored | |
2511 | * 22 label e as forward- or cross-edge | |
2512 | * 23 label t as explored | |
2513 | * 24 S.pop() | |
2514 | * | |
2515 | * convention: | |
2516 | * 0x10 - discovered | |
2517 | * 0x11 - discovered and fall-through edge labelled | |
2518 | * 0x12 - discovered and fall-through and branch edges labelled | |
2519 | * 0x20 - explored | |
2520 | */ | |
2521 | ||
2522 | enum { | |
2523 | DISCOVERED = 0x10, | |
2524 | EXPLORED = 0x20, | |
2525 | FALLTHROUGH = 1, | |
2526 | BRANCH = 2, | |
2527 | }; | |
2528 | ||
58e2af8b | 2529 | #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) |
f1bca824 | 2530 | |
475fb78f AS |
2531 | static int *insn_stack; /* stack of insns to process */ |
2532 | static int cur_stack; /* current stack index */ | |
2533 | static int *insn_state; | |
2534 | ||
2535 | /* t, w, e - match pseudo-code above: | |
2536 | * t - index of current instruction | |
2537 | * w - next instruction | |
2538 | * e - edge | |
2539 | */ | |
58e2af8b | 2540 | static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) |
475fb78f AS |
2541 | { |
2542 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
2543 | return 0; | |
2544 | ||
2545 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
2546 | return 0; | |
2547 | ||
2548 | if (w < 0 || w >= env->prog->len) { | |
2549 | verbose("jump out of range from insn %d to %d\n", t, w); | |
2550 | return -EINVAL; | |
2551 | } | |
2552 | ||
f1bca824 AS |
2553 | if (e == BRANCH) |
2554 | /* mark branch target for state pruning */ | |
2555 | env->explored_states[w] = STATE_LIST_MARK; | |
2556 | ||
475fb78f AS |
2557 | if (insn_state[w] == 0) { |
2558 | /* tree-edge */ | |
2559 | insn_state[t] = DISCOVERED | e; | |
2560 | insn_state[w] = DISCOVERED; | |
2561 | if (cur_stack >= env->prog->len) | |
2562 | return -E2BIG; | |
2563 | insn_stack[cur_stack++] = w; | |
2564 | return 1; | |
2565 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
2566 | verbose("back-edge from insn %d to %d\n", t, w); | |
2567 | return -EINVAL; | |
2568 | } else if (insn_state[w] == EXPLORED) { | |
2569 | /* forward- or cross-edge */ | |
2570 | insn_state[t] = DISCOVERED | e; | |
2571 | } else { | |
2572 | verbose("insn state internal bug\n"); | |
2573 | return -EFAULT; | |
2574 | } | |
2575 | return 0; | |
2576 | } | |
2577 | ||
2578 | /* non-recursive depth-first-search to detect loops in BPF program | |
2579 | * loop == back-edge in directed graph | |
2580 | */ | |
58e2af8b | 2581 | static int check_cfg(struct bpf_verifier_env *env) |
475fb78f AS |
2582 | { |
2583 | struct bpf_insn *insns = env->prog->insnsi; | |
2584 | int insn_cnt = env->prog->len; | |
2585 | int ret = 0; | |
2586 | int i, t; | |
2587 | ||
2588 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
2589 | if (!insn_state) | |
2590 | return -ENOMEM; | |
2591 | ||
2592 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
2593 | if (!insn_stack) { | |
2594 | kfree(insn_state); | |
2595 | return -ENOMEM; | |
2596 | } | |
2597 | ||
2598 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
2599 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
2600 | cur_stack = 1; | |
2601 | ||
2602 | peek_stack: | |
2603 | if (cur_stack == 0) | |
2604 | goto check_state; | |
2605 | t = insn_stack[cur_stack - 1]; | |
2606 | ||
2607 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
2608 | u8 opcode = BPF_OP(insns[t].code); | |
2609 | ||
2610 | if (opcode == BPF_EXIT) { | |
2611 | goto mark_explored; | |
2612 | } else if (opcode == BPF_CALL) { | |
2613 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2614 | if (ret == 1) | |
2615 | goto peek_stack; | |
2616 | else if (ret < 0) | |
2617 | goto err_free; | |
07016151 DB |
2618 | if (t + 1 < insn_cnt) |
2619 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2620 | } else if (opcode == BPF_JA) { |
2621 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
2622 | ret = -EINVAL; | |
2623 | goto err_free; | |
2624 | } | |
2625 | /* unconditional jump with single edge */ | |
2626 | ret = push_insn(t, t + insns[t].off + 1, | |
2627 | FALLTHROUGH, env); | |
2628 | if (ret == 1) | |
2629 | goto peek_stack; | |
2630 | else if (ret < 0) | |
2631 | goto err_free; | |
f1bca824 AS |
2632 | /* tell verifier to check for equivalent states |
2633 | * after every call and jump | |
2634 | */ | |
c3de6317 AS |
2635 | if (t + 1 < insn_cnt) |
2636 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2637 | } else { |
2638 | /* conditional jump with two edges */ | |
3c2ce60b | 2639 | env->explored_states[t] = STATE_LIST_MARK; |
475fb78f AS |
2640 | ret = push_insn(t, t + 1, FALLTHROUGH, env); |
2641 | if (ret == 1) | |
2642 | goto peek_stack; | |
2643 | else if (ret < 0) | |
2644 | goto err_free; | |
2645 | ||
2646 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
2647 | if (ret == 1) | |
2648 | goto peek_stack; | |
2649 | else if (ret < 0) | |
2650 | goto err_free; | |
2651 | } | |
2652 | } else { | |
2653 | /* all other non-branch instructions with single | |
2654 | * fall-through edge | |
2655 | */ | |
2656 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2657 | if (ret == 1) | |
2658 | goto peek_stack; | |
2659 | else if (ret < 0) | |
2660 | goto err_free; | |
2661 | } | |
2662 | ||
2663 | mark_explored: | |
2664 | insn_state[t] = EXPLORED; | |
2665 | if (cur_stack-- <= 0) { | |
2666 | verbose("pop stack internal bug\n"); | |
2667 | ret = -EFAULT; | |
2668 | goto err_free; | |
2669 | } | |
2670 | goto peek_stack; | |
2671 | ||
2672 | check_state: | |
2673 | for (i = 0; i < insn_cnt; i++) { | |
2674 | if (insn_state[i] != EXPLORED) { | |
2675 | verbose("unreachable insn %d\n", i); | |
2676 | ret = -EINVAL; | |
2677 | goto err_free; | |
2678 | } | |
2679 | } | |
2680 | ret = 0; /* cfg looks good */ | |
2681 | ||
2682 | err_free: | |
2683 | kfree(insn_state); | |
2684 | kfree(insn_stack); | |
2685 | return ret; | |
2686 | } | |
2687 | ||
969bf05e AS |
2688 | /* the following conditions reduce the number of explored insns |
2689 | * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet | |
2690 | */ | |
1ad2f583 DB |
2691 | static bool compare_ptrs_to_packet(struct bpf_verifier_env *env, |
2692 | struct bpf_reg_state *old, | |
58e2af8b | 2693 | struct bpf_reg_state *cur) |
969bf05e AS |
2694 | { |
2695 | if (old->id != cur->id) | |
2696 | return false; | |
2697 | ||
2698 | /* old ptr_to_packet is more conservative, since it allows smaller | |
2699 | * range. Ex: | |
2700 | * old(off=0,r=10) is equal to cur(off=0,r=20), because | |
2701 | * old(off=0,r=10) means that with range=10 the verifier proceeded | |
2702 | * further and found no issues with the program. Now we're in the same | |
2703 | * spot with cur(off=0,r=20), so we're safe too, since anything further | |
2704 | * will only be looking at most 10 bytes after this pointer. | |
2705 | */ | |
2706 | if (old->off == cur->off && old->range < cur->range) | |
2707 | return true; | |
2708 | ||
2709 | /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) | |
2710 | * since both cannot be used for packet access and safe(old) | |
2711 | * pointer has smaller off that could be used for further | |
2712 | * 'if (ptr > data_end)' check | |
2713 | * Ex: | |
2714 | * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean | |
2715 | * that we cannot access the packet. | |
2716 | * The safe range is: | |
2717 | * [ptr, ptr + range - off) | |
2718 | * so whenever off >=range, it means no safe bytes from this pointer. | |
2719 | * When comparing old->off <= cur->off, it means that older code | |
2720 | * went with smaller offset and that offset was later | |
2721 | * used to figure out the safe range after 'if (ptr > data_end)' check | |
2722 | * Say, 'old' state was explored like: | |
2723 | * ... R3(off=0, r=0) | |
2724 | * R4 = R3 + 20 | |
2725 | * ... now R4(off=20,r=0) <-- here | |
2726 | * if (R4 > data_end) | |
2727 | * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. | |
2728 | * ... the code further went all the way to bpf_exit. | |
2729 | * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). | |
2730 | * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier | |
2731 | * goes further, such cur_R4 will give larger safe packet range after | |
2732 | * 'if (R4 > data_end)' and all further insn were already good with r=20, | |
2733 | * so they will be good with r=30 and we can prune the search. | |
2734 | */ | |
1ad2f583 | 2735 | if (!env->strict_alignment && old->off <= cur->off && |
969bf05e AS |
2736 | old->off >= old->range && cur->off >= cur->range) |
2737 | return true; | |
2738 | ||
2739 | return false; | |
2740 | } | |
2741 | ||
f1bca824 AS |
2742 | /* compare two verifier states |
2743 | * | |
2744 | * all states stored in state_list are known to be valid, since | |
2745 | * verifier reached 'bpf_exit' instruction through them | |
2746 | * | |
2747 | * this function is called when verifier exploring different branches of | |
2748 | * execution popped from the state stack. If it sees an old state that has | |
2749 | * more strict register state and more strict stack state then this execution | |
2750 | * branch doesn't need to be explored further, since verifier already | |
2751 | * concluded that more strict state leads to valid finish. | |
2752 | * | |
2753 | * Therefore two states are equivalent if register state is more conservative | |
2754 | * and explored stack state is more conservative than the current one. | |
2755 | * Example: | |
2756 | * explored current | |
2757 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
2758 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
2759 | * | |
2760 | * In other words if current stack state (one being explored) has more | |
2761 | * valid slots than old one that already passed validation, it means | |
2762 | * the verifier can stop exploring and conclude that current state is valid too | |
2763 | * | |
2764 | * Similarly with registers. If explored state has register type as invalid | |
2765 | * whereas register type in current state is meaningful, it means that | |
2766 | * the current state will reach 'bpf_exit' instruction safely | |
2767 | */ | |
48461135 JB |
2768 | static bool states_equal(struct bpf_verifier_env *env, |
2769 | struct bpf_verifier_state *old, | |
58e2af8b | 2770 | struct bpf_verifier_state *cur) |
f1bca824 | 2771 | { |
e2d2afe1 | 2772 | bool varlen_map_access = env->varlen_map_value_access; |
58e2af8b | 2773 | struct bpf_reg_state *rold, *rcur; |
f1bca824 AS |
2774 | int i; |
2775 | ||
2776 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
2777 | rold = &old->regs[i]; |
2778 | rcur = &cur->regs[i]; | |
2779 | ||
2780 | if (memcmp(rold, rcur, sizeof(*rold)) == 0) | |
2781 | continue; | |
2782 | ||
48461135 JB |
2783 | /* If the ranges were not the same, but everything else was and |
2784 | * we didn't do a variable access into a map then we are a-ok. | |
2785 | */ | |
e2d2afe1 | 2786 | if (!varlen_map_access && |
d2a4dd37 | 2787 | memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0) |
48461135 JB |
2788 | continue; |
2789 | ||
e2d2afe1 JB |
2790 | /* If we didn't map access then again we don't care about the |
2791 | * mismatched range values and it's ok if our old type was | |
2792 | * UNKNOWN and we didn't go to a NOT_INIT'ed reg. | |
2793 | */ | |
1a0dc1ac | 2794 | if (rold->type == NOT_INIT || |
e2d2afe1 JB |
2795 | (!varlen_map_access && rold->type == UNKNOWN_VALUE && |
2796 | rcur->type != NOT_INIT)) | |
1a0dc1ac AS |
2797 | continue; |
2798 | ||
3c2ce60b DB |
2799 | /* Don't care about the reg->id in this case. */ |
2800 | if (rold->type == PTR_TO_MAP_VALUE_OR_NULL && | |
2801 | rcur->type == PTR_TO_MAP_VALUE_OR_NULL && | |
2802 | rold->map_ptr == rcur->map_ptr) | |
2803 | continue; | |
2804 | ||
969bf05e | 2805 | if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && |
1ad2f583 | 2806 | compare_ptrs_to_packet(env, rold, rcur)) |
969bf05e AS |
2807 | continue; |
2808 | ||
1a0dc1ac | 2809 | return false; |
f1bca824 AS |
2810 | } |
2811 | ||
2812 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
2813 | if (old->stack_slot_type[i] == STACK_INVALID) |
2814 | continue; | |
2815 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
2816 | /* Ex: old explored (safe) state has STACK_SPILL in | |
2817 | * this stack slot, but current has has STACK_MISC -> | |
2818 | * this verifier states are not equivalent, | |
2819 | * return false to continue verification of this path | |
2820 | */ | |
f1bca824 | 2821 | return false; |
9c399760 AS |
2822 | if (i % BPF_REG_SIZE) |
2823 | continue; | |
2824 | if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], | |
2825 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
2826 | sizeof(old->spilled_regs[0]))) | |
2827 | /* when explored and current stack slot types are | |
2828 | * the same, check that stored pointers types | |
2829 | * are the same as well. | |
2830 | * Ex: explored safe path could have stored | |
58e2af8b | 2831 | * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8} |
9c399760 | 2832 | * but current path has stored: |
58e2af8b | 2833 | * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16} |
9c399760 AS |
2834 | * such verifier states are not equivalent. |
2835 | * return false to continue verification of this path | |
2836 | */ | |
2837 | return false; | |
2838 | else | |
2839 | continue; | |
f1bca824 AS |
2840 | } |
2841 | return true; | |
2842 | } | |
2843 | ||
58e2af8b | 2844 | static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) |
f1bca824 | 2845 | { |
58e2af8b JK |
2846 | struct bpf_verifier_state_list *new_sl; |
2847 | struct bpf_verifier_state_list *sl; | |
f1bca824 AS |
2848 | |
2849 | sl = env->explored_states[insn_idx]; | |
2850 | if (!sl) | |
2851 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
2852 | * be doing state search here | |
2853 | */ | |
2854 | return 0; | |
2855 | ||
2856 | while (sl != STATE_LIST_MARK) { | |
48461135 | 2857 | if (states_equal(env, &sl->state, &env->cur_state)) |
f1bca824 AS |
2858 | /* reached equivalent register/stack state, |
2859 | * prune the search | |
2860 | */ | |
2861 | return 1; | |
2862 | sl = sl->next; | |
2863 | } | |
2864 | ||
2865 | /* there were no equivalent states, remember current one. | |
2866 | * technically the current state is not proven to be safe yet, | |
2867 | * but it will either reach bpf_exit (which means it's safe) or | |
2868 | * it will be rejected. Since there are no loops, we won't be | |
2869 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
2870 | */ | |
58e2af8b | 2871 | new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); |
f1bca824 AS |
2872 | if (!new_sl) |
2873 | return -ENOMEM; | |
2874 | ||
2875 | /* add new state to the head of linked list */ | |
2876 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
2877 | new_sl->next = env->explored_states[insn_idx]; | |
2878 | env->explored_states[insn_idx] = new_sl; | |
2879 | return 0; | |
2880 | } | |
2881 | ||
13a27dfc JK |
2882 | static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, |
2883 | int insn_idx, int prev_insn_idx) | |
2884 | { | |
2885 | if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) | |
2886 | return 0; | |
2887 | ||
2888 | return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); | |
2889 | } | |
2890 | ||
58e2af8b | 2891 | static int do_check(struct bpf_verifier_env *env) |
17a52670 | 2892 | { |
58e2af8b | 2893 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 2894 | struct bpf_insn *insns = env->prog->insnsi; |
58e2af8b | 2895 | struct bpf_reg_state *regs = state->regs; |
17a52670 AS |
2896 | int insn_cnt = env->prog->len; |
2897 | int insn_idx, prev_insn_idx = 0; | |
2898 | int insn_processed = 0; | |
2899 | bool do_print_state = false; | |
2900 | ||
2901 | init_reg_state(regs); | |
2902 | insn_idx = 0; | |
48461135 | 2903 | env->varlen_map_value_access = false; |
17a52670 AS |
2904 | for (;;) { |
2905 | struct bpf_insn *insn; | |
2906 | u8 class; | |
2907 | int err; | |
2908 | ||
2909 | if (insn_idx >= insn_cnt) { | |
2910 | verbose("invalid insn idx %d insn_cnt %d\n", | |
2911 | insn_idx, insn_cnt); | |
2912 | return -EFAULT; | |
2913 | } | |
2914 | ||
2915 | insn = &insns[insn_idx]; | |
2916 | class = BPF_CLASS(insn->code); | |
2917 | ||
07016151 | 2918 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
bc1750f3 | 2919 | verbose("BPF program is too large. Processed %d insn\n", |
17a52670 AS |
2920 | insn_processed); |
2921 | return -E2BIG; | |
2922 | } | |
2923 | ||
f1bca824 AS |
2924 | err = is_state_visited(env, insn_idx); |
2925 | if (err < 0) | |
2926 | return err; | |
2927 | if (err == 1) { | |
2928 | /* found equivalent state, can prune the search */ | |
2929 | if (log_level) { | |
2930 | if (do_print_state) | |
2931 | verbose("\nfrom %d to %d: safe\n", | |
2932 | prev_insn_idx, insn_idx); | |
2933 | else | |
2934 | verbose("%d: safe\n", insn_idx); | |
2935 | } | |
2936 | goto process_bpf_exit; | |
2937 | } | |
2938 | ||
3c2ce60b DB |
2939 | if (need_resched()) |
2940 | cond_resched(); | |
2941 | ||
c5fc9692 DM |
2942 | if (log_level > 1 || (log_level && do_print_state)) { |
2943 | if (log_level > 1) | |
2944 | verbose("%d:", insn_idx); | |
2945 | else | |
2946 | verbose("\nfrom %d to %d:", | |
2947 | prev_insn_idx, insn_idx); | |
1a0dc1ac | 2948 | print_verifier_state(&env->cur_state); |
17a52670 AS |
2949 | do_print_state = false; |
2950 | } | |
2951 | ||
2952 | if (log_level) { | |
2953 | verbose("%d: ", insn_idx); | |
0d0e5769 | 2954 | print_bpf_insn(env, insn); |
17a52670 AS |
2955 | } |
2956 | ||
13a27dfc JK |
2957 | err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); |
2958 | if (err) | |
2959 | return err; | |
2960 | ||
17a52670 | 2961 | if (class == BPF_ALU || class == BPF_ALU64) { |
1be7f75d | 2962 | err = check_alu_op(env, insn); |
17a52670 AS |
2963 | if (err) |
2964 | return err; | |
2965 | ||
2966 | } else if (class == BPF_LDX) { | |
3df126f3 | 2967 | enum bpf_reg_type *prev_src_type, src_reg_type; |
9bac3d6d AS |
2968 | |
2969 | /* check for reserved fields is already done */ | |
2970 | ||
17a52670 AS |
2971 | /* check src operand */ |
2972 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2973 | if (err) | |
2974 | return err; | |
2975 | ||
2976 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
2977 | if (err) | |
2978 | return err; | |
2979 | ||
725f9dcd AS |
2980 | src_reg_type = regs[insn->src_reg].type; |
2981 | ||
17a52670 AS |
2982 | /* check that memory (src_reg + off) is readable, |
2983 | * the state of dst_reg will be updated by this func | |
2984 | */ | |
2985 | err = check_mem_access(env, insn->src_reg, insn->off, | |
2986 | BPF_SIZE(insn->code), BPF_READ, | |
2987 | insn->dst_reg); | |
2988 | if (err) | |
2989 | return err; | |
2990 | ||
ea2e7ce5 AS |
2991 | if (BPF_SIZE(insn->code) != BPF_W && |
2992 | BPF_SIZE(insn->code) != BPF_DW) { | |
725f9dcd AS |
2993 | insn_idx++; |
2994 | continue; | |
2995 | } | |
9bac3d6d | 2996 | |
3df126f3 JK |
2997 | prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; |
2998 | ||
2999 | if (*prev_src_type == NOT_INIT) { | |
9bac3d6d AS |
3000 | /* saw a valid insn |
3001 | * dst_reg = *(u32 *)(src_reg + off) | |
3df126f3 | 3002 | * save type to validate intersecting paths |
9bac3d6d | 3003 | */ |
3df126f3 | 3004 | *prev_src_type = src_reg_type; |
9bac3d6d | 3005 | |
3df126f3 | 3006 | } else if (src_reg_type != *prev_src_type && |
9bac3d6d | 3007 | (src_reg_type == PTR_TO_CTX || |
3df126f3 | 3008 | *prev_src_type == PTR_TO_CTX)) { |
9bac3d6d AS |
3009 | /* ABuser program is trying to use the same insn |
3010 | * dst_reg = *(u32*) (src_reg + off) | |
3011 | * with different pointer types: | |
3012 | * src_reg == ctx in one branch and | |
3013 | * src_reg == stack|map in some other branch. | |
3014 | * Reject it. | |
3015 | */ | |
3016 | verbose("same insn cannot be used with different pointers\n"); | |
3017 | return -EINVAL; | |
3018 | } | |
3019 | ||
17a52670 | 3020 | } else if (class == BPF_STX) { |
3df126f3 | 3021 | enum bpf_reg_type *prev_dst_type, dst_reg_type; |
d691f9e8 | 3022 | |
17a52670 AS |
3023 | if (BPF_MODE(insn->code) == BPF_XADD) { |
3024 | err = check_xadd(env, insn); | |
3025 | if (err) | |
3026 | return err; | |
3027 | insn_idx++; | |
3028 | continue; | |
3029 | } | |
3030 | ||
17a52670 AS |
3031 | /* check src1 operand */ |
3032 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
3033 | if (err) | |
3034 | return err; | |
3035 | /* check src2 operand */ | |
3036 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
3037 | if (err) | |
3038 | return err; | |
3039 | ||
d691f9e8 AS |
3040 | dst_reg_type = regs[insn->dst_reg].type; |
3041 | ||
17a52670 AS |
3042 | /* check that memory (dst_reg + off) is writeable */ |
3043 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
3044 | BPF_SIZE(insn->code), BPF_WRITE, | |
3045 | insn->src_reg); | |
3046 | if (err) | |
3047 | return err; | |
3048 | ||
3df126f3 JK |
3049 | prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; |
3050 | ||
3051 | if (*prev_dst_type == NOT_INIT) { | |
3052 | *prev_dst_type = dst_reg_type; | |
3053 | } else if (dst_reg_type != *prev_dst_type && | |
d691f9e8 | 3054 | (dst_reg_type == PTR_TO_CTX || |
3df126f3 | 3055 | *prev_dst_type == PTR_TO_CTX)) { |
d691f9e8 AS |
3056 | verbose("same insn cannot be used with different pointers\n"); |
3057 | return -EINVAL; | |
3058 | } | |
3059 | ||
17a52670 AS |
3060 | } else if (class == BPF_ST) { |
3061 | if (BPF_MODE(insn->code) != BPF_MEM || | |
3062 | insn->src_reg != BPF_REG_0) { | |
3063 | verbose("BPF_ST uses reserved fields\n"); | |
3064 | return -EINVAL; | |
3065 | } | |
3066 | /* check src operand */ | |
3067 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
3068 | if (err) | |
3069 | return err; | |
3070 | ||
3071 | /* check that memory (dst_reg + off) is writeable */ | |
3072 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
3073 | BPF_SIZE(insn->code), BPF_WRITE, | |
3074 | -1); | |
3075 | if (err) | |
3076 | return err; | |
3077 | ||
3078 | } else if (class == BPF_JMP) { | |
3079 | u8 opcode = BPF_OP(insn->code); | |
3080 | ||
3081 | if (opcode == BPF_CALL) { | |
3082 | if (BPF_SRC(insn->code) != BPF_K || | |
3083 | insn->off != 0 || | |
3084 | insn->src_reg != BPF_REG_0 || | |
3085 | insn->dst_reg != BPF_REG_0) { | |
3086 | verbose("BPF_CALL uses reserved fields\n"); | |
3087 | return -EINVAL; | |
3088 | } | |
3089 | ||
81ed18ab | 3090 | err = check_call(env, insn->imm, insn_idx); |
17a52670 AS |
3091 | if (err) |
3092 | return err; | |
3093 | ||
3094 | } else if (opcode == BPF_JA) { | |
3095 | if (BPF_SRC(insn->code) != BPF_K || | |
3096 | insn->imm != 0 || | |
3097 | insn->src_reg != BPF_REG_0 || | |
3098 | insn->dst_reg != BPF_REG_0) { | |
3099 | verbose("BPF_JA uses reserved fields\n"); | |
3100 | return -EINVAL; | |
3101 | } | |
3102 | ||
3103 | insn_idx += insn->off + 1; | |
3104 | continue; | |
3105 | ||
3106 | } else if (opcode == BPF_EXIT) { | |
3107 | if (BPF_SRC(insn->code) != BPF_K || | |
3108 | insn->imm != 0 || | |
3109 | insn->src_reg != BPF_REG_0 || | |
3110 | insn->dst_reg != BPF_REG_0) { | |
3111 | verbose("BPF_EXIT uses reserved fields\n"); | |
3112 | return -EINVAL; | |
3113 | } | |
3114 | ||
3115 | /* eBPF calling convetion is such that R0 is used | |
3116 | * to return the value from eBPF program. | |
3117 | * Make sure that it's readable at this time | |
3118 | * of bpf_exit, which means that program wrote | |
3119 | * something into it earlier | |
3120 | */ | |
3121 | err = check_reg_arg(regs, BPF_REG_0, SRC_OP); | |
3122 | if (err) | |
3123 | return err; | |
3124 | ||
1be7f75d AS |
3125 | if (is_pointer_value(env, BPF_REG_0)) { |
3126 | verbose("R0 leaks addr as return value\n"); | |
3127 | return -EACCES; | |
3128 | } | |
3129 | ||
f1bca824 | 3130 | process_bpf_exit: |
17a52670 AS |
3131 | insn_idx = pop_stack(env, &prev_insn_idx); |
3132 | if (insn_idx < 0) { | |
3133 | break; | |
3134 | } else { | |
3135 | do_print_state = true; | |
3136 | continue; | |
3137 | } | |
3138 | } else { | |
3139 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
3140 | if (err) | |
3141 | return err; | |
3142 | } | |
3143 | } else if (class == BPF_LD) { | |
3144 | u8 mode = BPF_MODE(insn->code); | |
3145 | ||
3146 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
3147 | err = check_ld_abs(env, insn); |
3148 | if (err) | |
3149 | return err; | |
3150 | ||
17a52670 AS |
3151 | } else if (mode == BPF_IMM) { |
3152 | err = check_ld_imm(env, insn); | |
3153 | if (err) | |
3154 | return err; | |
3155 | ||
3156 | insn_idx++; | |
3157 | } else { | |
3158 | verbose("invalid BPF_LD mode\n"); | |
3159 | return -EINVAL; | |
3160 | } | |
48461135 | 3161 | reset_reg_range_values(regs, insn->dst_reg); |
17a52670 AS |
3162 | } else { |
3163 | verbose("unknown insn class %d\n", class); | |
3164 | return -EINVAL; | |
3165 | } | |
3166 | ||
3167 | insn_idx++; | |
3168 | } | |
3169 | ||
1a0dc1ac | 3170 | verbose("processed %d insns\n", insn_processed); |
17a52670 AS |
3171 | return 0; |
3172 | } | |
3173 | ||
56f668df MKL |
3174 | static int check_map_prealloc(struct bpf_map *map) |
3175 | { | |
3176 | return (map->map_type != BPF_MAP_TYPE_HASH && | |
bcc6b1b7 MKL |
3177 | map->map_type != BPF_MAP_TYPE_PERCPU_HASH && |
3178 | map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || | |
56f668df MKL |
3179 | !(map->map_flags & BPF_F_NO_PREALLOC); |
3180 | } | |
3181 | ||
fdc15d38 AS |
3182 | static int check_map_prog_compatibility(struct bpf_map *map, |
3183 | struct bpf_prog *prog) | |
3184 | ||
3185 | { | |
56f668df MKL |
3186 | /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use |
3187 | * preallocated hash maps, since doing memory allocation | |
3188 | * in overflow_handler can crash depending on where nmi got | |
3189 | * triggered. | |
3190 | */ | |
3191 | if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { | |
3192 | if (!check_map_prealloc(map)) { | |
3193 | verbose("perf_event programs can only use preallocated hash map\n"); | |
3194 | return -EINVAL; | |
3195 | } | |
3196 | if (map->inner_map_meta && | |
3197 | !check_map_prealloc(map->inner_map_meta)) { | |
3198 | verbose("perf_event programs can only use preallocated inner hash map\n"); | |
3199 | return -EINVAL; | |
3200 | } | |
fdc15d38 AS |
3201 | } |
3202 | return 0; | |
3203 | } | |
3204 | ||
0246e64d AS |
3205 | /* look for pseudo eBPF instructions that access map FDs and |
3206 | * replace them with actual map pointers | |
3207 | */ | |
58e2af8b | 3208 | static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) |
0246e64d AS |
3209 | { |
3210 | struct bpf_insn *insn = env->prog->insnsi; | |
3211 | int insn_cnt = env->prog->len; | |
fdc15d38 | 3212 | int i, j, err; |
0246e64d | 3213 | |
f1f7714e | 3214 | err = bpf_prog_calc_tag(env->prog); |
aafe6ae9 DB |
3215 | if (err) |
3216 | return err; | |
3217 | ||
0246e64d | 3218 | for (i = 0; i < insn_cnt; i++, insn++) { |
9bac3d6d | 3219 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 3220 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
9bac3d6d AS |
3221 | verbose("BPF_LDX uses reserved fields\n"); |
3222 | return -EINVAL; | |
3223 | } | |
3224 | ||
d691f9e8 AS |
3225 | if (BPF_CLASS(insn->code) == BPF_STX && |
3226 | ((BPF_MODE(insn->code) != BPF_MEM && | |
3227 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
3228 | verbose("BPF_STX uses reserved fields\n"); | |
3229 | return -EINVAL; | |
3230 | } | |
3231 | ||
0246e64d AS |
3232 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
3233 | struct bpf_map *map; | |
3234 | struct fd f; | |
3235 | ||
3236 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
3237 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
3238 | insn[1].off != 0) { | |
3239 | verbose("invalid bpf_ld_imm64 insn\n"); | |
3240 | return -EINVAL; | |
3241 | } | |
3242 | ||
3243 | if (insn->src_reg == 0) | |
3244 | /* valid generic load 64-bit imm */ | |
3245 | goto next_insn; | |
3246 | ||
3247 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
3248 | verbose("unrecognized bpf_ld_imm64 insn\n"); | |
3249 | return -EINVAL; | |
3250 | } | |
3251 | ||
3252 | f = fdget(insn->imm); | |
c2101297 | 3253 | map = __bpf_map_get(f); |
0246e64d AS |
3254 | if (IS_ERR(map)) { |
3255 | verbose("fd %d is not pointing to valid bpf_map\n", | |
3256 | insn->imm); | |
0246e64d AS |
3257 | return PTR_ERR(map); |
3258 | } | |
3259 | ||
fdc15d38 AS |
3260 | err = check_map_prog_compatibility(map, env->prog); |
3261 | if (err) { | |
3262 | fdput(f); | |
3263 | return err; | |
3264 | } | |
3265 | ||
0246e64d AS |
3266 | /* store map pointer inside BPF_LD_IMM64 instruction */ |
3267 | insn[0].imm = (u32) (unsigned long) map; | |
3268 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
3269 | ||
3270 | /* check whether we recorded this map already */ | |
3271 | for (j = 0; j < env->used_map_cnt; j++) | |
3272 | if (env->used_maps[j] == map) { | |
3273 | fdput(f); | |
3274 | goto next_insn; | |
3275 | } | |
3276 | ||
3277 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
3278 | fdput(f); | |
3279 | return -E2BIG; | |
3280 | } | |
3281 | ||
0246e64d AS |
3282 | /* hold the map. If the program is rejected by verifier, |
3283 | * the map will be released by release_maps() or it | |
3284 | * will be used by the valid program until it's unloaded | |
3285 | * and all maps are released in free_bpf_prog_info() | |
3286 | */ | |
92117d84 AS |
3287 | map = bpf_map_inc(map, false); |
3288 | if (IS_ERR(map)) { | |
3289 | fdput(f); | |
3290 | return PTR_ERR(map); | |
3291 | } | |
3292 | env->used_maps[env->used_map_cnt++] = map; | |
3293 | ||
0246e64d AS |
3294 | fdput(f); |
3295 | next_insn: | |
3296 | insn++; | |
3297 | i++; | |
3298 | } | |
3299 | } | |
3300 | ||
3301 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
3302 | * 'struct bpf_map *' into a register instead of user map_fd. | |
3303 | * These pointers will be used later by verifier to validate map access. | |
3304 | */ | |
3305 | return 0; | |
3306 | } | |
3307 | ||
3308 | /* drop refcnt of maps used by the rejected program */ | |
58e2af8b | 3309 | static void release_maps(struct bpf_verifier_env *env) |
0246e64d AS |
3310 | { |
3311 | int i; | |
3312 | ||
3313 | for (i = 0; i < env->used_map_cnt; i++) | |
3314 | bpf_map_put(env->used_maps[i]); | |
3315 | } | |
3316 | ||
3317 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
58e2af8b | 3318 | static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) |
0246e64d AS |
3319 | { |
3320 | struct bpf_insn *insn = env->prog->insnsi; | |
3321 | int insn_cnt = env->prog->len; | |
3322 | int i; | |
3323 | ||
3324 | for (i = 0; i < insn_cnt; i++, insn++) | |
3325 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
3326 | insn->src_reg = 0; | |
3327 | } | |
3328 | ||
8041902d AS |
3329 | /* single env->prog->insni[off] instruction was replaced with the range |
3330 | * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying | |
3331 | * [0, off) and [off, end) to new locations, so the patched range stays zero | |
3332 | */ | |
3333 | static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, | |
3334 | u32 off, u32 cnt) | |
3335 | { | |
3336 | struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; | |
3337 | ||
3338 | if (cnt == 1) | |
3339 | return 0; | |
3340 | new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); | |
3341 | if (!new_data) | |
3342 | return -ENOMEM; | |
3343 | memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); | |
3344 | memcpy(new_data + off + cnt - 1, old_data + off, | |
3345 | sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); | |
3346 | env->insn_aux_data = new_data; | |
3347 | vfree(old_data); | |
3348 | return 0; | |
3349 | } | |
3350 | ||
3351 | static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, | |
3352 | const struct bpf_insn *patch, u32 len) | |
3353 | { | |
3354 | struct bpf_prog *new_prog; | |
3355 | ||
3356 | new_prog = bpf_patch_insn_single(env->prog, off, patch, len); | |
3357 | if (!new_prog) | |
3358 | return NULL; | |
3359 | if (adjust_insn_aux_data(env, new_prog->len, off, len)) | |
3360 | return NULL; | |
3361 | return new_prog; | |
3362 | } | |
3363 | ||
9bac3d6d AS |
3364 | /* convert load instructions that access fields of 'struct __sk_buff' |
3365 | * into sequence of instructions that access fields of 'struct sk_buff' | |
3366 | */ | |
58e2af8b | 3367 | static int convert_ctx_accesses(struct bpf_verifier_env *env) |
9bac3d6d | 3368 | { |
36bbef52 | 3369 | const struct bpf_verifier_ops *ops = env->prog->aux->ops; |
3df126f3 | 3370 | const int insn_cnt = env->prog->len; |
36bbef52 | 3371 | struct bpf_insn insn_buf[16], *insn; |
9bac3d6d | 3372 | struct bpf_prog *new_prog; |
d691f9e8 | 3373 | enum bpf_access_type type; |
3df126f3 | 3374 | int i, cnt, delta = 0; |
9bac3d6d | 3375 | |
36bbef52 DB |
3376 | if (ops->gen_prologue) { |
3377 | cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, | |
3378 | env->prog); | |
3379 | if (cnt >= ARRAY_SIZE(insn_buf)) { | |
3380 | verbose("bpf verifier is misconfigured\n"); | |
3381 | return -EINVAL; | |
3382 | } else if (cnt) { | |
8041902d | 3383 | new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); |
36bbef52 DB |
3384 | if (!new_prog) |
3385 | return -ENOMEM; | |
8041902d | 3386 | |
36bbef52 | 3387 | env->prog = new_prog; |
3df126f3 | 3388 | delta += cnt - 1; |
36bbef52 DB |
3389 | } |
3390 | } | |
3391 | ||
3392 | if (!ops->convert_ctx_access) | |
9bac3d6d AS |
3393 | return 0; |
3394 | ||
3df126f3 | 3395 | insn = env->prog->insnsi + delta; |
36bbef52 | 3396 | |
9bac3d6d | 3397 | for (i = 0; i < insn_cnt; i++, insn++) { |
62c7989b DB |
3398 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || |
3399 | insn->code == (BPF_LDX | BPF_MEM | BPF_H) || | |
3400 | insn->code == (BPF_LDX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 3401 | insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) |
d691f9e8 | 3402 | type = BPF_READ; |
62c7989b DB |
3403 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || |
3404 | insn->code == (BPF_STX | BPF_MEM | BPF_H) || | |
3405 | insn->code == (BPF_STX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 3406 | insn->code == (BPF_STX | BPF_MEM | BPF_DW)) |
d691f9e8 AS |
3407 | type = BPF_WRITE; |
3408 | else | |
9bac3d6d AS |
3409 | continue; |
3410 | ||
8041902d | 3411 | if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) |
9bac3d6d | 3412 | continue; |
9bac3d6d | 3413 | |
6b8cc1d1 | 3414 | cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog); |
9bac3d6d AS |
3415 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { |
3416 | verbose("bpf verifier is misconfigured\n"); | |
3417 | return -EINVAL; | |
3418 | } | |
3419 | ||
8041902d | 3420 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); |
9bac3d6d AS |
3421 | if (!new_prog) |
3422 | return -ENOMEM; | |
3423 | ||
3df126f3 | 3424 | delta += cnt - 1; |
9bac3d6d AS |
3425 | |
3426 | /* keep walking new program and skip insns we just inserted */ | |
3427 | env->prog = new_prog; | |
3df126f3 | 3428 | insn = new_prog->insnsi + i + delta; |
9bac3d6d AS |
3429 | } |
3430 | ||
3431 | return 0; | |
3432 | } | |
3433 | ||
79741b3b | 3434 | /* fixup insn->imm field of bpf_call instructions |
81ed18ab | 3435 | * and inline eligible helpers as explicit sequence of BPF instructions |
e245c5c6 AS |
3436 | * |
3437 | * this function is called after eBPF program passed verification | |
3438 | */ | |
79741b3b | 3439 | static int fixup_bpf_calls(struct bpf_verifier_env *env) |
e245c5c6 | 3440 | { |
79741b3b AS |
3441 | struct bpf_prog *prog = env->prog; |
3442 | struct bpf_insn *insn = prog->insnsi; | |
e245c5c6 | 3443 | const struct bpf_func_proto *fn; |
79741b3b | 3444 | const int insn_cnt = prog->len; |
81ed18ab AS |
3445 | struct bpf_insn insn_buf[16]; |
3446 | struct bpf_prog *new_prog; | |
3447 | struct bpf_map *map_ptr; | |
3448 | int i, cnt, delta = 0; | |
e245c5c6 | 3449 | |
79741b3b AS |
3450 | for (i = 0; i < insn_cnt; i++, insn++) { |
3451 | if (insn->code != (BPF_JMP | BPF_CALL)) | |
3452 | continue; | |
e245c5c6 | 3453 | |
79741b3b AS |
3454 | if (insn->imm == BPF_FUNC_get_route_realm) |
3455 | prog->dst_needed = 1; | |
3456 | if (insn->imm == BPF_FUNC_get_prandom_u32) | |
3457 | bpf_user_rnd_init_once(); | |
79741b3b | 3458 | if (insn->imm == BPF_FUNC_tail_call) { |
7b9f6da1 DM |
3459 | /* If we tail call into other programs, we |
3460 | * cannot make any assumptions since they can | |
3461 | * be replaced dynamically during runtime in | |
3462 | * the program array. | |
3463 | */ | |
3464 | prog->cb_access = 1; | |
7b9f6da1 | 3465 | |
79741b3b AS |
3466 | /* mark bpf_tail_call as different opcode to avoid |
3467 | * conditional branch in the interpeter for every normal | |
3468 | * call and to prevent accidental JITing by JIT compiler | |
3469 | * that doesn't support bpf_tail_call yet | |
e245c5c6 | 3470 | */ |
79741b3b AS |
3471 | insn->imm = 0; |
3472 | insn->code |= BPF_X; | |
3473 | continue; | |
3474 | } | |
e245c5c6 | 3475 | |
81ed18ab AS |
3476 | if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) { |
3477 | map_ptr = env->insn_aux_data[i + delta].map_ptr; | |
fad73a1a MKL |
3478 | if (map_ptr == BPF_MAP_PTR_POISON || |
3479 | !map_ptr->ops->map_gen_lookup) | |
81ed18ab AS |
3480 | goto patch_call_imm; |
3481 | ||
3482 | cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); | |
3483 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { | |
3484 | verbose("bpf verifier is misconfigured\n"); | |
3485 | return -EINVAL; | |
3486 | } | |
3487 | ||
3488 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, | |
3489 | cnt); | |
3490 | if (!new_prog) | |
3491 | return -ENOMEM; | |
3492 | ||
3493 | delta += cnt - 1; | |
3494 | ||
3495 | /* keep walking new program and skip insns we just inserted */ | |
3496 | env->prog = prog = new_prog; | |
3497 | insn = new_prog->insnsi + i + delta; | |
3498 | continue; | |
3499 | } | |
3500 | ||
3501 | patch_call_imm: | |
79741b3b AS |
3502 | fn = prog->aux->ops->get_func_proto(insn->imm); |
3503 | /* all functions that have prototype and verifier allowed | |
3504 | * programs to call them, must be real in-kernel functions | |
3505 | */ | |
3506 | if (!fn->func) { | |
3507 | verbose("kernel subsystem misconfigured func %s#%d\n", | |
3508 | func_id_name(insn->imm), insn->imm); | |
3509 | return -EFAULT; | |
e245c5c6 | 3510 | } |
79741b3b | 3511 | insn->imm = fn->func - __bpf_call_base; |
e245c5c6 | 3512 | } |
e245c5c6 | 3513 | |
79741b3b AS |
3514 | return 0; |
3515 | } | |
e245c5c6 | 3516 | |
58e2af8b | 3517 | static void free_states(struct bpf_verifier_env *env) |
f1bca824 | 3518 | { |
58e2af8b | 3519 | struct bpf_verifier_state_list *sl, *sln; |
f1bca824 AS |
3520 | int i; |
3521 | ||
3522 | if (!env->explored_states) | |
3523 | return; | |
3524 | ||
3525 | for (i = 0; i < env->prog->len; i++) { | |
3526 | sl = env->explored_states[i]; | |
3527 | ||
3528 | if (sl) | |
3529 | while (sl != STATE_LIST_MARK) { | |
3530 | sln = sl->next; | |
3531 | kfree(sl); | |
3532 | sl = sln; | |
3533 | } | |
3534 | } | |
3535 | ||
3536 | kfree(env->explored_states); | |
3537 | } | |
3538 | ||
9bac3d6d | 3539 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 3540 | { |
cbd35700 | 3541 | char __user *log_ubuf = NULL; |
58e2af8b | 3542 | struct bpf_verifier_env *env; |
51580e79 AS |
3543 | int ret = -EINVAL; |
3544 | ||
58e2af8b | 3545 | /* 'struct bpf_verifier_env' can be global, but since it's not small, |
cbd35700 AS |
3546 | * allocate/free it every time bpf_check() is called |
3547 | */ | |
58e2af8b | 3548 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
cbd35700 AS |
3549 | if (!env) |
3550 | return -ENOMEM; | |
3551 | ||
3df126f3 JK |
3552 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * |
3553 | (*prog)->len); | |
3554 | ret = -ENOMEM; | |
3555 | if (!env->insn_aux_data) | |
3556 | goto err_free_env; | |
9bac3d6d | 3557 | env->prog = *prog; |
0246e64d | 3558 | |
cbd35700 AS |
3559 | /* grab the mutex to protect few globals used by verifier */ |
3560 | mutex_lock(&bpf_verifier_lock); | |
3561 | ||
3562 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
3563 | /* user requested verbose verifier output | |
3564 | * and supplied buffer to store the verification trace | |
3565 | */ | |
3566 | log_level = attr->log_level; | |
3567 | log_ubuf = (char __user *) (unsigned long) attr->log_buf; | |
3568 | log_size = attr->log_size; | |
3569 | log_len = 0; | |
3570 | ||
3571 | ret = -EINVAL; | |
3572 | /* log_* values have to be sane */ | |
3573 | if (log_size < 128 || log_size > UINT_MAX >> 8 || | |
3574 | log_level == 0 || log_ubuf == NULL) | |
3df126f3 | 3575 | goto err_unlock; |
cbd35700 AS |
3576 | |
3577 | ret = -ENOMEM; | |
3578 | log_buf = vmalloc(log_size); | |
3579 | if (!log_buf) | |
3df126f3 | 3580 | goto err_unlock; |
cbd35700 AS |
3581 | } else { |
3582 | log_level = 0; | |
3583 | } | |
1ad2f583 DB |
3584 | |
3585 | env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); | |
3586 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
e07b98d9 | 3587 | env->strict_alignment = true; |
cbd35700 | 3588 | |
0246e64d AS |
3589 | ret = replace_map_fd_with_map_ptr(env); |
3590 | if (ret < 0) | |
3591 | goto skip_full_check; | |
3592 | ||
9bac3d6d | 3593 | env->explored_states = kcalloc(env->prog->len, |
58e2af8b | 3594 | sizeof(struct bpf_verifier_state_list *), |
f1bca824 AS |
3595 | GFP_USER); |
3596 | ret = -ENOMEM; | |
3597 | if (!env->explored_states) | |
3598 | goto skip_full_check; | |
3599 | ||
475fb78f AS |
3600 | ret = check_cfg(env); |
3601 | if (ret < 0) | |
3602 | goto skip_full_check; | |
3603 | ||
1be7f75d AS |
3604 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
3605 | ||
17a52670 | 3606 | ret = do_check(env); |
cbd35700 | 3607 | |
0246e64d | 3608 | skip_full_check: |
17a52670 | 3609 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 3610 | free_states(env); |
0246e64d | 3611 | |
9bac3d6d AS |
3612 | if (ret == 0) |
3613 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
3614 | ret = convert_ctx_accesses(env); | |
3615 | ||
e245c5c6 | 3616 | if (ret == 0) |
79741b3b | 3617 | ret = fixup_bpf_calls(env); |
e245c5c6 | 3618 | |
cbd35700 AS |
3619 | if (log_level && log_len >= log_size - 1) { |
3620 | BUG_ON(log_len >= log_size); | |
3621 | /* verifier log exceeded user supplied buffer */ | |
3622 | ret = -ENOSPC; | |
3623 | /* fall through to return what was recorded */ | |
3624 | } | |
3625 | ||
3626 | /* copy verifier log back to user space including trailing zero */ | |
3627 | if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { | |
3628 | ret = -EFAULT; | |
3629 | goto free_log_buf; | |
3630 | } | |
3631 | ||
0246e64d AS |
3632 | if (ret == 0 && env->used_map_cnt) { |
3633 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
3634 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
3635 | sizeof(env->used_maps[0]), | |
3636 | GFP_KERNEL); | |
0246e64d | 3637 | |
9bac3d6d | 3638 | if (!env->prog->aux->used_maps) { |
0246e64d AS |
3639 | ret = -ENOMEM; |
3640 | goto free_log_buf; | |
3641 | } | |
3642 | ||
9bac3d6d | 3643 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 3644 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 3645 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
3646 | |
3647 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
3648 | * bpf_ld_imm64 instructions | |
3649 | */ | |
3650 | convert_pseudo_ld_imm64(env); | |
3651 | } | |
cbd35700 AS |
3652 | |
3653 | free_log_buf: | |
3654 | if (log_level) | |
3655 | vfree(log_buf); | |
9bac3d6d | 3656 | if (!env->prog->aux->used_maps) |
0246e64d AS |
3657 | /* if we didn't copy map pointers into bpf_prog_info, release |
3658 | * them now. Otherwise free_bpf_prog_info() will release them. | |
3659 | */ | |
3660 | release_maps(env); | |
9bac3d6d | 3661 | *prog = env->prog; |
3df126f3 | 3662 | err_unlock: |
cbd35700 | 3663 | mutex_unlock(&bpf_verifier_lock); |
3df126f3 JK |
3664 | vfree(env->insn_aux_data); |
3665 | err_free_env: | |
3666 | kfree(env); | |
51580e79 AS |
3667 | return ret; |
3668 | } | |
13a27dfc JK |
3669 | |
3670 | int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, | |
3671 | void *priv) | |
3672 | { | |
3673 | struct bpf_verifier_env *env; | |
3674 | int ret; | |
3675 | ||
3676 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); | |
3677 | if (!env) | |
3678 | return -ENOMEM; | |
3679 | ||
3680 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * | |
3681 | prog->len); | |
3682 | ret = -ENOMEM; | |
3683 | if (!env->insn_aux_data) | |
3684 | goto err_free_env; | |
3685 | env->prog = prog; | |
3686 | env->analyzer_ops = ops; | |
3687 | env->analyzer_priv = priv; | |
3688 | ||
3689 | /* grab the mutex to protect few globals used by verifier */ | |
3690 | mutex_lock(&bpf_verifier_lock); | |
3691 | ||
3692 | log_level = 0; | |
1ad2f583 | 3693 | |
e07b98d9 | 3694 | env->strict_alignment = false; |
1ad2f583 DB |
3695 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) |
3696 | env->strict_alignment = true; | |
13a27dfc JK |
3697 | |
3698 | env->explored_states = kcalloc(env->prog->len, | |
3699 | sizeof(struct bpf_verifier_state_list *), | |
3700 | GFP_KERNEL); | |
3701 | ret = -ENOMEM; | |
3702 | if (!env->explored_states) | |
3703 | goto skip_full_check; | |
3704 | ||
3705 | ret = check_cfg(env); | |
3706 | if (ret < 0) | |
3707 | goto skip_full_check; | |
3708 | ||
3709 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); | |
3710 | ||
3711 | ret = do_check(env); | |
3712 | ||
3713 | skip_full_check: | |
3714 | while (pop_stack(env, NULL) >= 0); | |
3715 | free_states(env); | |
3716 | ||
3717 | mutex_unlock(&bpf_verifier_lock); | |
3718 | vfree(env->insn_aux_data); | |
3719 | err_free_env: | |
3720 | kfree(env); | |
3721 | return ret; | |
3722 | } | |
3723 | EXPORT_SYMBOL_GPL(bpf_analyzer); |