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51580e79 | 1 | /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
969bf05e | 2 | * Copyright (c) 2016 Facebook |
51580e79 AS |
3 | * |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | */ | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/bpf.h> | |
58e2af8b | 17 | #include <linux/bpf_verifier.h> |
51580e79 AS |
18 | #include <linux/filter.h> |
19 | #include <net/netlink.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/vmalloc.h> | |
ebb676da | 22 | #include <linux/stringify.h> |
51580e79 | 23 | |
f4ac7e0b JK |
24 | #include "disasm.h" |
25 | ||
00176a34 JK |
26 | static const struct bpf_verifier_ops * const bpf_verifier_ops[] = { |
27 | #define BPF_PROG_TYPE(_id, _name) \ | |
28 | [_id] = & _name ## _verifier_ops, | |
29 | #define BPF_MAP_TYPE(_id, _ops) | |
30 | #include <linux/bpf_types.h> | |
31 | #undef BPF_PROG_TYPE | |
32 | #undef BPF_MAP_TYPE | |
33 | }; | |
34 | ||
51580e79 AS |
35 | /* bpf_check() is a static code analyzer that walks eBPF program |
36 | * instruction by instruction and updates register/stack state. | |
37 | * All paths of conditional branches are analyzed until 'bpf_exit' insn. | |
38 | * | |
39 | * The first pass is depth-first-search to check that the program is a DAG. | |
40 | * It rejects the following programs: | |
41 | * - larger than BPF_MAXINSNS insns | |
42 | * - if loop is present (detected via back-edge) | |
43 | * - unreachable insns exist (shouldn't be a forest. program = one function) | |
44 | * - out of bounds or malformed jumps | |
45 | * The second pass is all possible path descent from the 1st insn. | |
46 | * Since it's analyzing all pathes through the program, the length of the | |
eba38a96 | 47 | * analysis is limited to 64k insn, which may be hit even if total number of |
51580e79 AS |
48 | * insn is less then 4K, but there are too many branches that change stack/regs. |
49 | * Number of 'branches to be analyzed' is limited to 1k | |
50 | * | |
51 | * On entry to each instruction, each register has a type, and the instruction | |
52 | * changes the types of the registers depending on instruction semantics. | |
53 | * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is | |
54 | * copied to R1. | |
55 | * | |
56 | * All registers are 64-bit. | |
57 | * R0 - return register | |
58 | * R1-R5 argument passing registers | |
59 | * R6-R9 callee saved registers | |
60 | * R10 - frame pointer read-only | |
61 | * | |
62 | * At the start of BPF program the register R1 contains a pointer to bpf_context | |
63 | * and has type PTR_TO_CTX. | |
64 | * | |
65 | * Verifier tracks arithmetic operations on pointers in case: | |
66 | * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), | |
67 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), | |
68 | * 1st insn copies R10 (which has FRAME_PTR) type into R1 | |
69 | * and 2nd arithmetic instruction is pattern matched to recognize | |
70 | * that it wants to construct a pointer to some element within stack. | |
71 | * So after 2nd insn, the register R1 has type PTR_TO_STACK | |
72 | * (and -20 constant is saved for further stack bounds checking). | |
73 | * Meaning that this reg is a pointer to stack plus known immediate constant. | |
74 | * | |
f1174f77 | 75 | * Most of the time the registers have SCALAR_VALUE type, which |
51580e79 | 76 | * means the register has some value, but it's not a valid pointer. |
f1174f77 | 77 | * (like pointer plus pointer becomes SCALAR_VALUE type) |
51580e79 AS |
78 | * |
79 | * When verifier sees load or store instructions the type of base register | |
f1174f77 | 80 | * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer |
51580e79 AS |
81 | * types recognized by check_mem_access() function. |
82 | * | |
83 | * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' | |
84 | * and the range of [ptr, ptr + map's value_size) is accessible. | |
85 | * | |
86 | * registers used to pass values to function calls are checked against | |
87 | * function argument constraints. | |
88 | * | |
89 | * ARG_PTR_TO_MAP_KEY is one of such argument constraints. | |
90 | * It means that the register type passed to this function must be | |
91 | * PTR_TO_STACK and it will be used inside the function as | |
92 | * 'pointer to map element key' | |
93 | * | |
94 | * For example the argument constraints for bpf_map_lookup_elem(): | |
95 | * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, | |
96 | * .arg1_type = ARG_CONST_MAP_PTR, | |
97 | * .arg2_type = ARG_PTR_TO_MAP_KEY, | |
98 | * | |
99 | * ret_type says that this function returns 'pointer to map elem value or null' | |
100 | * function expects 1st argument to be a const pointer to 'struct bpf_map' and | |
101 | * 2nd argument should be a pointer to stack, which will be used inside | |
102 | * the helper function as a pointer to map element key. | |
103 | * | |
104 | * On the kernel side the helper function looks like: | |
105 | * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
106 | * { | |
107 | * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
108 | * void *key = (void *) (unsigned long) r2; | |
109 | * void *value; | |
110 | * | |
111 | * here kernel can access 'key' and 'map' pointers safely, knowing that | |
112 | * [key, key + map->key_size) bytes are valid and were initialized on | |
113 | * the stack of eBPF program. | |
114 | * } | |
115 | * | |
116 | * Corresponding eBPF program may look like: | |
117 | * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR | |
118 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK | |
119 | * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP | |
120 | * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
121 | * here verifier looks at prototype of map_lookup_elem() and sees: | |
122 | * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, | |
123 | * Now verifier knows that this map has key of R1->map_ptr->key_size bytes | |
124 | * | |
125 | * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, | |
126 | * Now verifier checks that [R2, R2 + map's key_size) are within stack limits | |
127 | * and were initialized prior to this call. | |
128 | * If it's ok, then verifier allows this BPF_CALL insn and looks at | |
129 | * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets | |
130 | * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function | |
131 | * returns ether pointer to map value or NULL. | |
132 | * | |
133 | * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' | |
134 | * insn, the register holding that pointer in the true branch changes state to | |
135 | * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false | |
136 | * branch. See check_cond_jmp_op(). | |
137 | * | |
138 | * After the call R0 is set to return type of the function and registers R1-R5 | |
139 | * are set to NOT_INIT to indicate that they are no longer readable. | |
140 | */ | |
141 | ||
17a52670 | 142 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ |
58e2af8b | 143 | struct bpf_verifier_stack_elem { |
17a52670 AS |
144 | /* verifer state is 'st' |
145 | * before processing instruction 'insn_idx' | |
146 | * and after processing instruction 'prev_insn_idx' | |
147 | */ | |
58e2af8b | 148 | struct bpf_verifier_state st; |
17a52670 AS |
149 | int insn_idx; |
150 | int prev_insn_idx; | |
58e2af8b | 151 | struct bpf_verifier_stack_elem *next; |
cbd35700 AS |
152 | }; |
153 | ||
8e17c1b1 | 154 | #define BPF_COMPLEXITY_LIMIT_INSNS 131072 |
07016151 DB |
155 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 |
156 | ||
fad73a1a MKL |
157 | #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) |
158 | ||
33ff9823 DB |
159 | struct bpf_call_arg_meta { |
160 | struct bpf_map *map_ptr; | |
435faee1 | 161 | bool raw_mode; |
36bbef52 | 162 | bool pkt_access; |
435faee1 DB |
163 | int regno; |
164 | int access_size; | |
33ff9823 DB |
165 | }; |
166 | ||
cbd35700 AS |
167 | static DEFINE_MUTEX(bpf_verifier_lock); |
168 | ||
169 | /* log_level controls verbosity level of eBPF verifier. | |
170 | * verbose() is used to dump the verification trace to the log, so the user | |
171 | * can figure out what's wrong with the program | |
172 | */ | |
61bd5218 JK |
173 | static __printf(2, 3) void verbose(struct bpf_verifier_env *env, |
174 | const char *fmt, ...) | |
cbd35700 | 175 | { |
61bd5218 | 176 | struct bpf_verifer_log *log = &env->log; |
a2a7d570 | 177 | unsigned int n; |
cbd35700 AS |
178 | va_list args; |
179 | ||
a2a7d570 | 180 | if (!log->level || !log->ubuf || bpf_verifier_log_full(log)) |
cbd35700 AS |
181 | return; |
182 | ||
183 | va_start(args, fmt); | |
a2a7d570 | 184 | n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args); |
cbd35700 | 185 | va_end(args); |
a2a7d570 JK |
186 | |
187 | WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, | |
188 | "verifier log line truncated - local buffer too short\n"); | |
189 | ||
190 | n = min(log->len_total - log->len_used - 1, n); | |
191 | log->kbuf[n] = '\0'; | |
192 | ||
193 | if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1)) | |
194 | log->len_used += n; | |
195 | else | |
196 | log->ubuf = NULL; | |
cbd35700 AS |
197 | } |
198 | ||
de8f3a83 DB |
199 | static bool type_is_pkt_pointer(enum bpf_reg_type type) |
200 | { | |
201 | return type == PTR_TO_PACKET || | |
202 | type == PTR_TO_PACKET_META; | |
203 | } | |
204 | ||
17a52670 AS |
205 | /* string representation of 'enum bpf_reg_type' */ |
206 | static const char * const reg_type_str[] = { | |
207 | [NOT_INIT] = "?", | |
f1174f77 | 208 | [SCALAR_VALUE] = "inv", |
17a52670 AS |
209 | [PTR_TO_CTX] = "ctx", |
210 | [CONST_PTR_TO_MAP] = "map_ptr", | |
211 | [PTR_TO_MAP_VALUE] = "map_value", | |
212 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
17a52670 | 213 | [PTR_TO_STACK] = "fp", |
969bf05e | 214 | [PTR_TO_PACKET] = "pkt", |
de8f3a83 | 215 | [PTR_TO_PACKET_META] = "pkt_meta", |
969bf05e | 216 | [PTR_TO_PACKET_END] = "pkt_end", |
17a52670 AS |
217 | }; |
218 | ||
61bd5218 JK |
219 | static void print_verifier_state(struct bpf_verifier_env *env, |
220 | struct bpf_verifier_state *state) | |
17a52670 | 221 | { |
58e2af8b | 222 | struct bpf_reg_state *reg; |
17a52670 AS |
223 | enum bpf_reg_type t; |
224 | int i; | |
225 | ||
226 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
227 | reg = &state->regs[i]; |
228 | t = reg->type; | |
17a52670 AS |
229 | if (t == NOT_INIT) |
230 | continue; | |
61bd5218 | 231 | verbose(env, " R%d=%s", i, reg_type_str[t]); |
f1174f77 EC |
232 | if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && |
233 | tnum_is_const(reg->var_off)) { | |
234 | /* reg->off should be 0 for SCALAR_VALUE */ | |
61bd5218 | 235 | verbose(env, "%lld", reg->var_off.value + reg->off); |
f1174f77 | 236 | } else { |
61bd5218 | 237 | verbose(env, "(id=%d", reg->id); |
f1174f77 | 238 | if (t != SCALAR_VALUE) |
61bd5218 | 239 | verbose(env, ",off=%d", reg->off); |
de8f3a83 | 240 | if (type_is_pkt_pointer(t)) |
61bd5218 | 241 | verbose(env, ",r=%d", reg->range); |
f1174f77 EC |
242 | else if (t == CONST_PTR_TO_MAP || |
243 | t == PTR_TO_MAP_VALUE || | |
244 | t == PTR_TO_MAP_VALUE_OR_NULL) | |
61bd5218 | 245 | verbose(env, ",ks=%d,vs=%d", |
f1174f77 EC |
246 | reg->map_ptr->key_size, |
247 | reg->map_ptr->value_size); | |
7d1238f2 EC |
248 | if (tnum_is_const(reg->var_off)) { |
249 | /* Typically an immediate SCALAR_VALUE, but | |
250 | * could be a pointer whose offset is too big | |
251 | * for reg->off | |
252 | */ | |
61bd5218 | 253 | verbose(env, ",imm=%llx", reg->var_off.value); |
7d1238f2 EC |
254 | } else { |
255 | if (reg->smin_value != reg->umin_value && | |
256 | reg->smin_value != S64_MIN) | |
61bd5218 | 257 | verbose(env, ",smin_value=%lld", |
7d1238f2 EC |
258 | (long long)reg->smin_value); |
259 | if (reg->smax_value != reg->umax_value && | |
260 | reg->smax_value != S64_MAX) | |
61bd5218 | 261 | verbose(env, ",smax_value=%lld", |
7d1238f2 EC |
262 | (long long)reg->smax_value); |
263 | if (reg->umin_value != 0) | |
61bd5218 | 264 | verbose(env, ",umin_value=%llu", |
7d1238f2 EC |
265 | (unsigned long long)reg->umin_value); |
266 | if (reg->umax_value != U64_MAX) | |
61bd5218 | 267 | verbose(env, ",umax_value=%llu", |
7d1238f2 EC |
268 | (unsigned long long)reg->umax_value); |
269 | if (!tnum_is_unknown(reg->var_off)) { | |
270 | char tn_buf[48]; | |
f1174f77 | 271 | |
7d1238f2 | 272 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); |
61bd5218 | 273 | verbose(env, ",var_off=%s", tn_buf); |
7d1238f2 | 274 | } |
f1174f77 | 275 | } |
61bd5218 | 276 | verbose(env, ")"); |
f1174f77 | 277 | } |
17a52670 | 278 | } |
9c399760 | 279 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 280 | if (state->stack_slot_type[i] == STACK_SPILL) |
61bd5218 | 281 | verbose(env, " fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 282 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 | 283 | } |
61bd5218 | 284 | verbose(env, "\n"); |
17a52670 AS |
285 | } |
286 | ||
58e2af8b | 287 | static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) |
17a52670 | 288 | { |
58e2af8b | 289 | struct bpf_verifier_stack_elem *elem; |
17a52670 AS |
290 | int insn_idx; |
291 | ||
292 | if (env->head == NULL) | |
293 | return -1; | |
294 | ||
295 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
296 | insn_idx = env->head->insn_idx; | |
297 | if (prev_insn_idx) | |
298 | *prev_insn_idx = env->head->prev_insn_idx; | |
299 | elem = env->head->next; | |
300 | kfree(env->head); | |
301 | env->head = elem; | |
302 | env->stack_size--; | |
303 | return insn_idx; | |
304 | } | |
305 | ||
58e2af8b JK |
306 | static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, |
307 | int insn_idx, int prev_insn_idx) | |
17a52670 | 308 | { |
58e2af8b | 309 | struct bpf_verifier_stack_elem *elem; |
17a52670 | 310 | |
58e2af8b | 311 | elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); |
17a52670 AS |
312 | if (!elem) |
313 | goto err; | |
314 | ||
315 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
316 | elem->insn_idx = insn_idx; | |
317 | elem->prev_insn_idx = prev_insn_idx; | |
318 | elem->next = env->head; | |
319 | env->head = elem; | |
320 | env->stack_size++; | |
07016151 | 321 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
61bd5218 | 322 | verbose(env, "BPF program is too complex\n"); |
17a52670 AS |
323 | goto err; |
324 | } | |
325 | return &elem->st; | |
326 | err: | |
327 | /* pop all elements and return */ | |
328 | while (pop_stack(env, NULL) >= 0); | |
329 | return NULL; | |
330 | } | |
331 | ||
332 | #define CALLER_SAVED_REGS 6 | |
333 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
334 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
335 | }; | |
336 | ||
f1174f77 EC |
337 | static void __mark_reg_not_init(struct bpf_reg_state *reg); |
338 | ||
b03c9f9f EC |
339 | /* Mark the unknown part of a register (variable offset or scalar value) as |
340 | * known to have the value @imm. | |
341 | */ | |
342 | static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) | |
343 | { | |
344 | reg->id = 0; | |
345 | reg->var_off = tnum_const(imm); | |
346 | reg->smin_value = (s64)imm; | |
347 | reg->smax_value = (s64)imm; | |
348 | reg->umin_value = imm; | |
349 | reg->umax_value = imm; | |
350 | } | |
351 | ||
f1174f77 EC |
352 | /* Mark the 'variable offset' part of a register as zero. This should be |
353 | * used only on registers holding a pointer type. | |
354 | */ | |
355 | static void __mark_reg_known_zero(struct bpf_reg_state *reg) | |
a9789ef9 | 356 | { |
b03c9f9f | 357 | __mark_reg_known(reg, 0); |
f1174f77 | 358 | } |
a9789ef9 | 359 | |
61bd5218 JK |
360 | static void mark_reg_known_zero(struct bpf_verifier_env *env, |
361 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
362 | { |
363 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 364 | verbose(env, "mark_reg_known_zero(regs, %u)\n", regno); |
f1174f77 EC |
365 | /* Something bad happened, let's kill all regs */ |
366 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
367 | __mark_reg_not_init(regs + regno); | |
368 | return; | |
369 | } | |
370 | __mark_reg_known_zero(regs + regno); | |
371 | } | |
372 | ||
de8f3a83 DB |
373 | static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg) |
374 | { | |
375 | return type_is_pkt_pointer(reg->type); | |
376 | } | |
377 | ||
378 | static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg) | |
379 | { | |
380 | return reg_is_pkt_pointer(reg) || | |
381 | reg->type == PTR_TO_PACKET_END; | |
382 | } | |
383 | ||
384 | /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */ | |
385 | static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, | |
386 | enum bpf_reg_type which) | |
387 | { | |
388 | /* The register can already have a range from prior markings. | |
389 | * This is fine as long as it hasn't been advanced from its | |
390 | * origin. | |
391 | */ | |
392 | return reg->type == which && | |
393 | reg->id == 0 && | |
394 | reg->off == 0 && | |
395 | tnum_equals_const(reg->var_off, 0); | |
396 | } | |
397 | ||
b03c9f9f EC |
398 | /* Attempts to improve min/max values based on var_off information */ |
399 | static void __update_reg_bounds(struct bpf_reg_state *reg) | |
400 | { | |
401 | /* min signed is max(sign bit) | min(other bits) */ | |
402 | reg->smin_value = max_t(s64, reg->smin_value, | |
403 | reg->var_off.value | (reg->var_off.mask & S64_MIN)); | |
404 | /* max signed is min(sign bit) | max(other bits) */ | |
405 | reg->smax_value = min_t(s64, reg->smax_value, | |
406 | reg->var_off.value | (reg->var_off.mask & S64_MAX)); | |
407 | reg->umin_value = max(reg->umin_value, reg->var_off.value); | |
408 | reg->umax_value = min(reg->umax_value, | |
409 | reg->var_off.value | reg->var_off.mask); | |
410 | } | |
411 | ||
412 | /* Uses signed min/max values to inform unsigned, and vice-versa */ | |
413 | static void __reg_deduce_bounds(struct bpf_reg_state *reg) | |
414 | { | |
415 | /* Learn sign from signed bounds. | |
416 | * If we cannot cross the sign boundary, then signed and unsigned bounds | |
417 | * are the same, so combine. This works even in the negative case, e.g. | |
418 | * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff. | |
419 | */ | |
420 | if (reg->smin_value >= 0 || reg->smax_value < 0) { | |
421 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
422 | reg->umin_value); | |
423 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
424 | reg->umax_value); | |
425 | return; | |
426 | } | |
427 | /* Learn sign from unsigned bounds. Signed bounds cross the sign | |
428 | * boundary, so we must be careful. | |
429 | */ | |
430 | if ((s64)reg->umax_value >= 0) { | |
431 | /* Positive. We can't learn anything from the smin, but smax | |
432 | * is positive, hence safe. | |
433 | */ | |
434 | reg->smin_value = reg->umin_value; | |
435 | reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, | |
436 | reg->umax_value); | |
437 | } else if ((s64)reg->umin_value < 0) { | |
438 | /* Negative. We can't learn anything from the smax, but smin | |
439 | * is negative, hence safe. | |
440 | */ | |
441 | reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, | |
442 | reg->umin_value); | |
443 | reg->smax_value = reg->umax_value; | |
444 | } | |
445 | } | |
446 | ||
447 | /* Attempts to improve var_off based on unsigned min/max information */ | |
448 | static void __reg_bound_offset(struct bpf_reg_state *reg) | |
449 | { | |
450 | reg->var_off = tnum_intersect(reg->var_off, | |
451 | tnum_range(reg->umin_value, | |
452 | reg->umax_value)); | |
453 | } | |
454 | ||
455 | /* Reset the min/max bounds of a register */ | |
456 | static void __mark_reg_unbounded(struct bpf_reg_state *reg) | |
457 | { | |
458 | reg->smin_value = S64_MIN; | |
459 | reg->smax_value = S64_MAX; | |
460 | reg->umin_value = 0; | |
461 | reg->umax_value = U64_MAX; | |
462 | } | |
463 | ||
f1174f77 EC |
464 | /* Mark a register as having a completely unknown (scalar) value. */ |
465 | static void __mark_reg_unknown(struct bpf_reg_state *reg) | |
466 | { | |
467 | reg->type = SCALAR_VALUE; | |
468 | reg->id = 0; | |
469 | reg->off = 0; | |
470 | reg->var_off = tnum_unknown; | |
b03c9f9f | 471 | __mark_reg_unbounded(reg); |
f1174f77 EC |
472 | } |
473 | ||
61bd5218 JK |
474 | static void mark_reg_unknown(struct bpf_verifier_env *env, |
475 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
476 | { |
477 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 478 | verbose(env, "mark_reg_unknown(regs, %u)\n", regno); |
f1174f77 EC |
479 | /* Something bad happened, let's kill all regs */ |
480 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
481 | __mark_reg_not_init(regs + regno); | |
482 | return; | |
483 | } | |
484 | __mark_reg_unknown(regs + regno); | |
485 | } | |
486 | ||
487 | static void __mark_reg_not_init(struct bpf_reg_state *reg) | |
488 | { | |
489 | __mark_reg_unknown(reg); | |
490 | reg->type = NOT_INIT; | |
491 | } | |
492 | ||
61bd5218 JK |
493 | static void mark_reg_not_init(struct bpf_verifier_env *env, |
494 | struct bpf_reg_state *regs, u32 regno) | |
f1174f77 EC |
495 | { |
496 | if (WARN_ON(regno >= MAX_BPF_REG)) { | |
61bd5218 | 497 | verbose(env, "mark_reg_not_init(regs, %u)\n", regno); |
f1174f77 EC |
498 | /* Something bad happened, let's kill all regs */ |
499 | for (regno = 0; regno < MAX_BPF_REG; regno++) | |
500 | __mark_reg_not_init(regs + regno); | |
501 | return; | |
502 | } | |
503 | __mark_reg_not_init(regs + regno); | |
a9789ef9 DB |
504 | } |
505 | ||
61bd5218 JK |
506 | static void init_reg_state(struct bpf_verifier_env *env, |
507 | struct bpf_reg_state *regs) | |
17a52670 AS |
508 | { |
509 | int i; | |
510 | ||
dc503a8a | 511 | for (i = 0; i < MAX_BPF_REG; i++) { |
61bd5218 | 512 | mark_reg_not_init(env, regs, i); |
dc503a8a EC |
513 | regs[i].live = REG_LIVE_NONE; |
514 | } | |
17a52670 AS |
515 | |
516 | /* frame pointer */ | |
f1174f77 | 517 | regs[BPF_REG_FP].type = PTR_TO_STACK; |
61bd5218 | 518 | mark_reg_known_zero(env, regs, BPF_REG_FP); |
17a52670 AS |
519 | |
520 | /* 1st arg to a function */ | |
521 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
61bd5218 | 522 | mark_reg_known_zero(env, regs, BPF_REG_1); |
6760bf2d DB |
523 | } |
524 | ||
17a52670 AS |
525 | enum reg_arg_type { |
526 | SRC_OP, /* register is used as source operand */ | |
527 | DST_OP, /* register is used as destination operand */ | |
528 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
529 | }; | |
530 | ||
dc503a8a EC |
531 | static void mark_reg_read(const struct bpf_verifier_state *state, u32 regno) |
532 | { | |
533 | struct bpf_verifier_state *parent = state->parent; | |
534 | ||
8fe2d6cc AS |
535 | if (regno == BPF_REG_FP) |
536 | /* We don't need to worry about FP liveness because it's read-only */ | |
537 | return; | |
538 | ||
dc503a8a EC |
539 | while (parent) { |
540 | /* if read wasn't screened by an earlier write ... */ | |
541 | if (state->regs[regno].live & REG_LIVE_WRITTEN) | |
542 | break; | |
543 | /* ... then we depend on parent's value */ | |
544 | parent->regs[regno].live |= REG_LIVE_READ; | |
545 | state = parent; | |
546 | parent = state->parent; | |
547 | } | |
548 | } | |
549 | ||
550 | static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, | |
17a52670 AS |
551 | enum reg_arg_type t) |
552 | { | |
dc503a8a EC |
553 | struct bpf_reg_state *regs = env->cur_state.regs; |
554 | ||
17a52670 | 555 | if (regno >= MAX_BPF_REG) { |
61bd5218 | 556 | verbose(env, "R%d is invalid\n", regno); |
17a52670 AS |
557 | return -EINVAL; |
558 | } | |
559 | ||
560 | if (t == SRC_OP) { | |
561 | /* check whether register used as source operand can be read */ | |
562 | if (regs[regno].type == NOT_INIT) { | |
61bd5218 | 563 | verbose(env, "R%d !read_ok\n", regno); |
17a52670 AS |
564 | return -EACCES; |
565 | } | |
dc503a8a | 566 | mark_reg_read(&env->cur_state, regno); |
17a52670 AS |
567 | } else { |
568 | /* check whether register used as dest operand can be written to */ | |
569 | if (regno == BPF_REG_FP) { | |
61bd5218 | 570 | verbose(env, "frame pointer is read only\n"); |
17a52670 AS |
571 | return -EACCES; |
572 | } | |
dc503a8a | 573 | regs[regno].live |= REG_LIVE_WRITTEN; |
17a52670 | 574 | if (t == DST_OP) |
61bd5218 | 575 | mark_reg_unknown(env, regs, regno); |
17a52670 AS |
576 | } |
577 | return 0; | |
578 | } | |
579 | ||
1be7f75d AS |
580 | static bool is_spillable_regtype(enum bpf_reg_type type) |
581 | { | |
582 | switch (type) { | |
583 | case PTR_TO_MAP_VALUE: | |
584 | case PTR_TO_MAP_VALUE_OR_NULL: | |
585 | case PTR_TO_STACK: | |
586 | case PTR_TO_CTX: | |
969bf05e | 587 | case PTR_TO_PACKET: |
de8f3a83 | 588 | case PTR_TO_PACKET_META: |
969bf05e | 589 | case PTR_TO_PACKET_END: |
1be7f75d AS |
590 | case CONST_PTR_TO_MAP: |
591 | return true; | |
592 | default: | |
593 | return false; | |
594 | } | |
595 | } | |
596 | ||
17a52670 AS |
597 | /* check_stack_read/write functions track spill/fill of registers, |
598 | * stack boundary and alignment are checked in check_mem_access() | |
599 | */ | |
61bd5218 JK |
600 | static int check_stack_write(struct bpf_verifier_env *env, |
601 | struct bpf_verifier_state *state, int off, | |
58e2af8b | 602 | int size, int value_regno) |
17a52670 | 603 | { |
dc503a8a | 604 | int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE; |
9c399760 AS |
605 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
606 | * so it's aligned access and [off, off + size) are within stack limits | |
607 | */ | |
17a52670 AS |
608 | |
609 | if (value_regno >= 0 && | |
1be7f75d | 610 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
611 | |
612 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 613 | if (size != BPF_REG_SIZE) { |
61bd5218 | 614 | verbose(env, "invalid size of register spill\n"); |
17a52670 AS |
615 | return -EACCES; |
616 | } | |
617 | ||
17a52670 | 618 | /* save register state */ |
dc503a8a EC |
619 | state->spilled_regs[spi] = state->regs[value_regno]; |
620 | state->spilled_regs[spi].live |= REG_LIVE_WRITTEN; | |
17a52670 | 621 | |
9c399760 AS |
622 | for (i = 0; i < BPF_REG_SIZE; i++) |
623 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
624 | } else { | |
17a52670 | 625 | /* regular write of data into stack */ |
dc503a8a | 626 | state->spilled_regs[spi] = (struct bpf_reg_state) {}; |
9c399760 AS |
627 | |
628 | for (i = 0; i < size; i++) | |
629 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
630 | } |
631 | return 0; | |
632 | } | |
633 | ||
dc503a8a EC |
634 | static void mark_stack_slot_read(const struct bpf_verifier_state *state, int slot) |
635 | { | |
636 | struct bpf_verifier_state *parent = state->parent; | |
637 | ||
638 | while (parent) { | |
639 | /* if read wasn't screened by an earlier write ... */ | |
640 | if (state->spilled_regs[slot].live & REG_LIVE_WRITTEN) | |
641 | break; | |
642 | /* ... then we depend on parent's value */ | |
643 | parent->spilled_regs[slot].live |= REG_LIVE_READ; | |
644 | state = parent; | |
645 | parent = state->parent; | |
646 | } | |
647 | } | |
648 | ||
61bd5218 JK |
649 | static int check_stack_read(struct bpf_verifier_env *env, |
650 | struct bpf_verifier_state *state, int off, int size, | |
17a52670 AS |
651 | int value_regno) |
652 | { | |
9c399760 | 653 | u8 *slot_type; |
dc503a8a | 654 | int i, spi; |
17a52670 | 655 | |
9c399760 | 656 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 657 | |
9c399760 AS |
658 | if (slot_type[0] == STACK_SPILL) { |
659 | if (size != BPF_REG_SIZE) { | |
61bd5218 | 660 | verbose(env, "invalid size of register spill\n"); |
17a52670 AS |
661 | return -EACCES; |
662 | } | |
9c399760 AS |
663 | for (i = 1; i < BPF_REG_SIZE; i++) { |
664 | if (slot_type[i] != STACK_SPILL) { | |
61bd5218 | 665 | verbose(env, "corrupted spill memory\n"); |
17a52670 AS |
666 | return -EACCES; |
667 | } | |
668 | } | |
669 | ||
dc503a8a EC |
670 | spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE; |
671 | ||
672 | if (value_regno >= 0) { | |
17a52670 | 673 | /* restore register state from stack */ |
dc503a8a EC |
674 | state->regs[value_regno] = state->spilled_regs[spi]; |
675 | mark_stack_slot_read(state, spi); | |
676 | } | |
17a52670 AS |
677 | return 0; |
678 | } else { | |
679 | for (i = 0; i < size; i++) { | |
9c399760 | 680 | if (slot_type[i] != STACK_MISC) { |
61bd5218 | 681 | verbose(env, "invalid read from stack off %d+%d size %d\n", |
17a52670 AS |
682 | off, i, size); |
683 | return -EACCES; | |
684 | } | |
685 | } | |
686 | if (value_regno >= 0) | |
687 | /* have read misc data from the stack */ | |
61bd5218 | 688 | mark_reg_unknown(env, state->regs, value_regno); |
17a52670 AS |
689 | return 0; |
690 | } | |
691 | } | |
692 | ||
693 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
f1174f77 | 694 | static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off, |
17a52670 AS |
695 | int size) |
696 | { | |
697 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
698 | ||
5722569b | 699 | if (off < 0 || size <= 0 || off + size > map->value_size) { |
61bd5218 | 700 | verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", |
17a52670 AS |
701 | map->value_size, off, size); |
702 | return -EACCES; | |
703 | } | |
704 | return 0; | |
705 | } | |
706 | ||
f1174f77 EC |
707 | /* check read/write into a map element with possible variable offset */ |
708 | static int check_map_access(struct bpf_verifier_env *env, u32 regno, | |
dbcfe5f7 GB |
709 | int off, int size) |
710 | { | |
711 | struct bpf_verifier_state *state = &env->cur_state; | |
712 | struct bpf_reg_state *reg = &state->regs[regno]; | |
713 | int err; | |
714 | ||
f1174f77 EC |
715 | /* We may have adjusted the register to this map value, so we |
716 | * need to try adding each of min_value and max_value to off | |
717 | * to make sure our theoretical access will be safe. | |
dbcfe5f7 | 718 | */ |
61bd5218 JK |
719 | if (env->log.level) |
720 | print_verifier_state(env, state); | |
dbcfe5f7 GB |
721 | /* The minimum value is only important with signed |
722 | * comparisons where we can't assume the floor of a | |
723 | * value is 0. If we are using signed variables for our | |
724 | * index'es we need to make sure that whatever we use | |
725 | * will have a set floor within our range. | |
726 | */ | |
b03c9f9f | 727 | if (reg->smin_value < 0) { |
61bd5218 | 728 | verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
dbcfe5f7 GB |
729 | regno); |
730 | return -EACCES; | |
731 | } | |
b03c9f9f | 732 | err = __check_map_access(env, regno, reg->smin_value + off, size); |
dbcfe5f7 | 733 | if (err) { |
61bd5218 JK |
734 | verbose(env, "R%d min value is outside of the array range\n", |
735 | regno); | |
dbcfe5f7 GB |
736 | return err; |
737 | } | |
738 | ||
b03c9f9f EC |
739 | /* If we haven't set a max value then we need to bail since we can't be |
740 | * sure we won't do bad things. | |
741 | * If reg->umax_value + off could overflow, treat that as unbounded too. | |
dbcfe5f7 | 742 | */ |
b03c9f9f | 743 | if (reg->umax_value >= BPF_MAX_VAR_OFF) { |
61bd5218 | 744 | verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n", |
dbcfe5f7 GB |
745 | regno); |
746 | return -EACCES; | |
747 | } | |
b03c9f9f | 748 | err = __check_map_access(env, regno, reg->umax_value + off, size); |
f1174f77 | 749 | if (err) |
61bd5218 JK |
750 | verbose(env, "R%d max value is outside of the array range\n", |
751 | regno); | |
f1174f77 | 752 | return err; |
dbcfe5f7 GB |
753 | } |
754 | ||
969bf05e AS |
755 | #define MAX_PACKET_OFF 0xffff |
756 | ||
58e2af8b | 757 | static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, |
3a0af8fd TG |
758 | const struct bpf_call_arg_meta *meta, |
759 | enum bpf_access_type t) | |
4acf6c0b | 760 | { |
36bbef52 | 761 | switch (env->prog->type) { |
3a0af8fd TG |
762 | case BPF_PROG_TYPE_LWT_IN: |
763 | case BPF_PROG_TYPE_LWT_OUT: | |
764 | /* dst_input() and dst_output() can't write for now */ | |
765 | if (t == BPF_WRITE) | |
766 | return false; | |
7e57fbb2 | 767 | /* fallthrough */ |
36bbef52 DB |
768 | case BPF_PROG_TYPE_SCHED_CLS: |
769 | case BPF_PROG_TYPE_SCHED_ACT: | |
4acf6c0b | 770 | case BPF_PROG_TYPE_XDP: |
3a0af8fd | 771 | case BPF_PROG_TYPE_LWT_XMIT: |
8a31db56 | 772 | case BPF_PROG_TYPE_SK_SKB: |
36bbef52 DB |
773 | if (meta) |
774 | return meta->pkt_access; | |
775 | ||
776 | env->seen_direct_write = true; | |
4acf6c0b BB |
777 | return true; |
778 | default: | |
779 | return false; | |
780 | } | |
781 | } | |
782 | ||
f1174f77 EC |
783 | static int __check_packet_access(struct bpf_verifier_env *env, u32 regno, |
784 | int off, int size) | |
969bf05e | 785 | { |
58e2af8b JK |
786 | struct bpf_reg_state *regs = env->cur_state.regs; |
787 | struct bpf_reg_state *reg = ®s[regno]; | |
969bf05e | 788 | |
f1174f77 | 789 | if (off < 0 || size <= 0 || (u64)off + size > reg->range) { |
61bd5218 | 790 | verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", |
d91b28ed | 791 | off, size, regno, reg->id, reg->off, reg->range); |
969bf05e AS |
792 | return -EACCES; |
793 | } | |
794 | return 0; | |
795 | } | |
796 | ||
f1174f77 EC |
797 | static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, |
798 | int size) | |
799 | { | |
800 | struct bpf_reg_state *regs = env->cur_state.regs; | |
801 | struct bpf_reg_state *reg = ®s[regno]; | |
802 | int err; | |
803 | ||
804 | /* We may have added a variable offset to the packet pointer; but any | |
805 | * reg->range we have comes after that. We are only checking the fixed | |
806 | * offset. | |
807 | */ | |
808 | ||
809 | /* We don't allow negative numbers, because we aren't tracking enough | |
810 | * detail to prove they're safe. | |
811 | */ | |
b03c9f9f | 812 | if (reg->smin_value < 0) { |
61bd5218 | 813 | verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", |
f1174f77 EC |
814 | regno); |
815 | return -EACCES; | |
816 | } | |
817 | err = __check_packet_access(env, regno, off, size); | |
818 | if (err) { | |
61bd5218 | 819 | verbose(env, "R%d offset is outside of the packet\n", regno); |
f1174f77 EC |
820 | return err; |
821 | } | |
822 | return err; | |
823 | } | |
824 | ||
825 | /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ | |
31fd8581 | 826 | static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, |
19de99f7 | 827 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 | 828 | { |
f96da094 DB |
829 | struct bpf_insn_access_aux info = { |
830 | .reg_type = *reg_type, | |
831 | }; | |
31fd8581 | 832 | |
4f9218aa JK |
833 | if (env->ops->is_valid_access && |
834 | env->ops->is_valid_access(off, size, t, &info)) { | |
f96da094 DB |
835 | /* A non zero info.ctx_field_size indicates that this field is a |
836 | * candidate for later verifier transformation to load the whole | |
837 | * field and then apply a mask when accessed with a narrower | |
838 | * access than actual ctx access size. A zero info.ctx_field_size | |
839 | * will only allow for whole field access and rejects any other | |
840 | * type of narrower access. | |
31fd8581 | 841 | */ |
23994631 | 842 | *reg_type = info.reg_type; |
31fd8581 | 843 | |
4f9218aa JK |
844 | if (env->analyzer_ops) |
845 | return 0; | |
846 | ||
847 | env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; | |
32bbe007 AS |
848 | /* remember the offset of last byte accessed in ctx */ |
849 | if (env->prog->aux->max_ctx_offset < off + size) | |
850 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 851 | return 0; |
32bbe007 | 852 | } |
17a52670 | 853 | |
61bd5218 | 854 | verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size); |
17a52670 AS |
855 | return -EACCES; |
856 | } | |
857 | ||
4cabc5b1 DB |
858 | static bool __is_pointer_value(bool allow_ptr_leaks, |
859 | const struct bpf_reg_state *reg) | |
1be7f75d | 860 | { |
4cabc5b1 | 861 | if (allow_ptr_leaks) |
1be7f75d AS |
862 | return false; |
863 | ||
f1174f77 | 864 | return reg->type != SCALAR_VALUE; |
1be7f75d AS |
865 | } |
866 | ||
4cabc5b1 DB |
867 | static bool is_pointer_value(struct bpf_verifier_env *env, int regno) |
868 | { | |
869 | return __is_pointer_value(env->allow_ptr_leaks, &env->cur_state.regs[regno]); | |
870 | } | |
871 | ||
61bd5218 JK |
872 | static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, |
873 | const struct bpf_reg_state *reg, | |
d1174416 | 874 | int off, int size, bool strict) |
969bf05e | 875 | { |
f1174f77 | 876 | struct tnum reg_off; |
e07b98d9 | 877 | int ip_align; |
d1174416 DM |
878 | |
879 | /* Byte size accesses are always allowed. */ | |
880 | if (!strict || size == 1) | |
881 | return 0; | |
882 | ||
e4eda884 DM |
883 | /* For platforms that do not have a Kconfig enabling |
884 | * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of | |
885 | * NET_IP_ALIGN is universally set to '2'. And on platforms | |
886 | * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get | |
887 | * to this code only in strict mode where we want to emulate | |
888 | * the NET_IP_ALIGN==2 checking. Therefore use an | |
889 | * unconditional IP align value of '2'. | |
e07b98d9 | 890 | */ |
e4eda884 | 891 | ip_align = 2; |
f1174f77 EC |
892 | |
893 | reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off)); | |
894 | if (!tnum_is_aligned(reg_off, size)) { | |
895 | char tn_buf[48]; | |
896 | ||
897 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 JK |
898 | verbose(env, |
899 | "misaligned packet access off %d+%s+%d+%d size %d\n", | |
f1174f77 | 900 | ip_align, tn_buf, reg->off, off, size); |
969bf05e AS |
901 | return -EACCES; |
902 | } | |
79adffcd | 903 | |
969bf05e AS |
904 | return 0; |
905 | } | |
906 | ||
61bd5218 JK |
907 | static int check_generic_ptr_alignment(struct bpf_verifier_env *env, |
908 | const struct bpf_reg_state *reg, | |
f1174f77 EC |
909 | const char *pointer_desc, |
910 | int off, int size, bool strict) | |
79adffcd | 911 | { |
f1174f77 EC |
912 | struct tnum reg_off; |
913 | ||
914 | /* Byte size accesses are always allowed. */ | |
915 | if (!strict || size == 1) | |
916 | return 0; | |
917 | ||
918 | reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off)); | |
919 | if (!tnum_is_aligned(reg_off, size)) { | |
920 | char tn_buf[48]; | |
921 | ||
922 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 923 | verbose(env, "misaligned %saccess off %s+%d+%d size %d\n", |
f1174f77 | 924 | pointer_desc, tn_buf, reg->off, off, size); |
79adffcd DB |
925 | return -EACCES; |
926 | } | |
927 | ||
969bf05e AS |
928 | return 0; |
929 | } | |
930 | ||
e07b98d9 DM |
931 | static int check_ptr_alignment(struct bpf_verifier_env *env, |
932 | const struct bpf_reg_state *reg, | |
79adffcd DB |
933 | int off, int size) |
934 | { | |
e07b98d9 | 935 | bool strict = env->strict_alignment; |
f1174f77 | 936 | const char *pointer_desc = ""; |
d1174416 | 937 | |
79adffcd DB |
938 | switch (reg->type) { |
939 | case PTR_TO_PACKET: | |
de8f3a83 DB |
940 | case PTR_TO_PACKET_META: |
941 | /* Special case, because of NET_IP_ALIGN. Given metadata sits | |
942 | * right in front, treat it the very same way. | |
943 | */ | |
61bd5218 | 944 | return check_pkt_ptr_alignment(env, reg, off, size, strict); |
f1174f77 EC |
945 | case PTR_TO_MAP_VALUE: |
946 | pointer_desc = "value "; | |
947 | break; | |
948 | case PTR_TO_CTX: | |
949 | pointer_desc = "context "; | |
950 | break; | |
951 | case PTR_TO_STACK: | |
952 | pointer_desc = "stack "; | |
953 | break; | |
79adffcd | 954 | default: |
f1174f77 | 955 | break; |
79adffcd | 956 | } |
61bd5218 JK |
957 | return check_generic_ptr_alignment(env, reg, pointer_desc, off, size, |
958 | strict); | |
79adffcd DB |
959 | } |
960 | ||
17a52670 AS |
961 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
962 | * if t==write, value_regno is a register which value is stored into memory | |
963 | * if t==read, value_regno is a register which will receive the value from memory | |
964 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
965 | * if t==read && value_regno==-1, don't care what we read from memory | |
966 | */ | |
31fd8581 | 967 | static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, |
17a52670 AS |
968 | int bpf_size, enum bpf_access_type t, |
969 | int value_regno) | |
970 | { | |
58e2af8b JK |
971 | struct bpf_verifier_state *state = &env->cur_state; |
972 | struct bpf_reg_state *reg = &state->regs[regno]; | |
17a52670 AS |
973 | int size, err = 0; |
974 | ||
975 | size = bpf_size_to_bytes(bpf_size); | |
976 | if (size < 0) | |
977 | return size; | |
978 | ||
f1174f77 | 979 | /* alignment checks will add in reg->off themselves */ |
e07b98d9 | 980 | err = check_ptr_alignment(env, reg, off, size); |
969bf05e AS |
981 | if (err) |
982 | return err; | |
17a52670 | 983 | |
f1174f77 EC |
984 | /* for access checks, reg->off is just part of off */ |
985 | off += reg->off; | |
986 | ||
987 | if (reg->type == PTR_TO_MAP_VALUE) { | |
1be7f75d AS |
988 | if (t == BPF_WRITE && value_regno >= 0 && |
989 | is_pointer_value(env, value_regno)) { | |
61bd5218 | 990 | verbose(env, "R%d leaks addr into map\n", value_regno); |
1be7f75d AS |
991 | return -EACCES; |
992 | } | |
48461135 | 993 | |
f1174f77 | 994 | err = check_map_access(env, regno, off, size); |
17a52670 | 995 | if (!err && t == BPF_READ && value_regno >= 0) |
61bd5218 | 996 | mark_reg_unknown(env, state->regs, value_regno); |
17a52670 | 997 | |
1a0dc1ac | 998 | } else if (reg->type == PTR_TO_CTX) { |
f1174f77 | 999 | enum bpf_reg_type reg_type = SCALAR_VALUE; |
19de99f7 | 1000 | |
1be7f75d AS |
1001 | if (t == BPF_WRITE && value_regno >= 0 && |
1002 | is_pointer_value(env, value_regno)) { | |
61bd5218 | 1003 | verbose(env, "R%d leaks addr into ctx\n", value_regno); |
1be7f75d AS |
1004 | return -EACCES; |
1005 | } | |
f1174f77 EC |
1006 | /* ctx accesses must be at a fixed offset, so that we can |
1007 | * determine what type of data were returned. | |
1008 | */ | |
1009 | if (!tnum_is_const(reg->var_off)) { | |
1010 | char tn_buf[48]; | |
1011 | ||
1012 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 JK |
1013 | verbose(env, |
1014 | "variable ctx access var_off=%s off=%d size=%d", | |
f1174f77 EC |
1015 | tn_buf, off, size); |
1016 | return -EACCES; | |
1017 | } | |
1018 | off += reg->var_off.value; | |
31fd8581 | 1019 | err = check_ctx_access(env, insn_idx, off, size, t, ®_type); |
969bf05e | 1020 | if (!err && t == BPF_READ && value_regno >= 0) { |
f1174f77 | 1021 | /* ctx access returns either a scalar, or a |
de8f3a83 DB |
1022 | * PTR_TO_PACKET[_META,_END]. In the latter |
1023 | * case, we know the offset is zero. | |
f1174f77 EC |
1024 | */ |
1025 | if (reg_type == SCALAR_VALUE) | |
61bd5218 | 1026 | mark_reg_unknown(env, state->regs, value_regno); |
f1174f77 | 1027 | else |
61bd5218 JK |
1028 | mark_reg_known_zero(env, state->regs, |
1029 | value_regno); | |
f1174f77 EC |
1030 | state->regs[value_regno].id = 0; |
1031 | state->regs[value_regno].off = 0; | |
1032 | state->regs[value_regno].range = 0; | |
1955351d | 1033 | state->regs[value_regno].type = reg_type; |
969bf05e | 1034 | } |
17a52670 | 1035 | |
f1174f77 EC |
1036 | } else if (reg->type == PTR_TO_STACK) { |
1037 | /* stack accesses must be at a fixed offset, so that we can | |
1038 | * determine what type of data were returned. | |
1039 | * See check_stack_read(). | |
1040 | */ | |
1041 | if (!tnum_is_const(reg->var_off)) { | |
1042 | char tn_buf[48]; | |
1043 | ||
1044 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 1045 | verbose(env, "variable stack access var_off=%s off=%d size=%d", |
f1174f77 EC |
1046 | tn_buf, off, size); |
1047 | return -EACCES; | |
1048 | } | |
1049 | off += reg->var_off.value; | |
17a52670 | 1050 | if (off >= 0 || off < -MAX_BPF_STACK) { |
61bd5218 JK |
1051 | verbose(env, "invalid stack off=%d size=%d\n", off, |
1052 | size); | |
17a52670 AS |
1053 | return -EACCES; |
1054 | } | |
8726679a AS |
1055 | |
1056 | if (env->prog->aux->stack_depth < -off) | |
1057 | env->prog->aux->stack_depth = -off; | |
1058 | ||
1be7f75d AS |
1059 | if (t == BPF_WRITE) { |
1060 | if (!env->allow_ptr_leaks && | |
1061 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
1062 | size != BPF_REG_SIZE) { | |
61bd5218 | 1063 | verbose(env, "attempt to corrupt spilled pointer on stack\n"); |
1be7f75d AS |
1064 | return -EACCES; |
1065 | } | |
61bd5218 JK |
1066 | err = check_stack_write(env, state, off, size, |
1067 | value_regno); | |
1be7f75d | 1068 | } else { |
61bd5218 JK |
1069 | err = check_stack_read(env, state, off, size, |
1070 | value_regno); | |
1be7f75d | 1071 | } |
de8f3a83 | 1072 | } else if (reg_is_pkt_pointer(reg)) { |
3a0af8fd | 1073 | if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { |
61bd5218 | 1074 | verbose(env, "cannot write into packet\n"); |
969bf05e AS |
1075 | return -EACCES; |
1076 | } | |
4acf6c0b BB |
1077 | if (t == BPF_WRITE && value_regno >= 0 && |
1078 | is_pointer_value(env, value_regno)) { | |
61bd5218 JK |
1079 | verbose(env, "R%d leaks addr into packet\n", |
1080 | value_regno); | |
4acf6c0b BB |
1081 | return -EACCES; |
1082 | } | |
969bf05e AS |
1083 | err = check_packet_access(env, regno, off, size); |
1084 | if (!err && t == BPF_READ && value_regno >= 0) | |
61bd5218 | 1085 | mark_reg_unknown(env, state->regs, value_regno); |
17a52670 | 1086 | } else { |
61bd5218 JK |
1087 | verbose(env, "R%d invalid mem access '%s'\n", regno, |
1088 | reg_type_str[reg->type]); | |
17a52670 AS |
1089 | return -EACCES; |
1090 | } | |
969bf05e | 1091 | |
f1174f77 EC |
1092 | if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && |
1093 | state->regs[value_regno].type == SCALAR_VALUE) { | |
1094 | /* b/h/w load zero-extends, mark upper bits as known 0 */ | |
1095 | state->regs[value_regno].var_off = tnum_cast( | |
1096 | state->regs[value_regno].var_off, size); | |
b03c9f9f | 1097 | __update_reg_bounds(&state->regs[value_regno]); |
969bf05e | 1098 | } |
17a52670 AS |
1099 | return err; |
1100 | } | |
1101 | ||
31fd8581 | 1102 | static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) |
17a52670 | 1103 | { |
17a52670 AS |
1104 | int err; |
1105 | ||
1106 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
1107 | insn->imm != 0) { | |
61bd5218 | 1108 | verbose(env, "BPF_XADD uses reserved fields\n"); |
17a52670 AS |
1109 | return -EINVAL; |
1110 | } | |
1111 | ||
1112 | /* check src1 operand */ | |
dc503a8a | 1113 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
1114 | if (err) |
1115 | return err; | |
1116 | ||
1117 | /* check src2 operand */ | |
dc503a8a | 1118 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
1119 | if (err) |
1120 | return err; | |
1121 | ||
6bdf6abc | 1122 | if (is_pointer_value(env, insn->src_reg)) { |
61bd5218 | 1123 | verbose(env, "R%d leaks addr into mem\n", insn->src_reg); |
6bdf6abc DB |
1124 | return -EACCES; |
1125 | } | |
1126 | ||
17a52670 | 1127 | /* check whether atomic_add can read the memory */ |
31fd8581 | 1128 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1129 | BPF_SIZE(insn->code), BPF_READ, -1); |
1130 | if (err) | |
1131 | return err; | |
1132 | ||
1133 | /* check whether atomic_add can write into the same memory */ | |
31fd8581 | 1134 | return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
1135 | BPF_SIZE(insn->code), BPF_WRITE, -1); |
1136 | } | |
1137 | ||
f1174f77 EC |
1138 | /* Does this register contain a constant zero? */ |
1139 | static bool register_is_null(struct bpf_reg_state reg) | |
1140 | { | |
1141 | return reg.type == SCALAR_VALUE && tnum_equals_const(reg.var_off, 0); | |
1142 | } | |
1143 | ||
17a52670 AS |
1144 | /* when register 'regno' is passed into function that will read 'access_size' |
1145 | * bytes from that pointer, make sure that it's within stack boundary | |
f1174f77 EC |
1146 | * and all elements of stack are initialized. |
1147 | * Unlike most pointer bounds-checking functions, this one doesn't take an | |
1148 | * 'off' argument, so it has to add in reg->off itself. | |
17a52670 | 1149 | */ |
58e2af8b | 1150 | static int check_stack_boundary(struct bpf_verifier_env *env, int regno, |
435faee1 DB |
1151 | int access_size, bool zero_size_allowed, |
1152 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1153 | { |
58e2af8b JK |
1154 | struct bpf_verifier_state *state = &env->cur_state; |
1155 | struct bpf_reg_state *regs = state->regs; | |
17a52670 AS |
1156 | int off, i; |
1157 | ||
8e2fe1d9 | 1158 | if (regs[regno].type != PTR_TO_STACK) { |
f1174f77 | 1159 | /* Allow zero-byte read from NULL, regardless of pointer type */ |
8e2fe1d9 | 1160 | if (zero_size_allowed && access_size == 0 && |
f1174f77 | 1161 | register_is_null(regs[regno])) |
8e2fe1d9 DB |
1162 | return 0; |
1163 | ||
61bd5218 | 1164 | verbose(env, "R%d type=%s expected=%s\n", regno, |
8e2fe1d9 DB |
1165 | reg_type_str[regs[regno].type], |
1166 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 1167 | return -EACCES; |
8e2fe1d9 | 1168 | } |
17a52670 | 1169 | |
f1174f77 EC |
1170 | /* Only allow fixed-offset stack reads */ |
1171 | if (!tnum_is_const(regs[regno].var_off)) { | |
1172 | char tn_buf[48]; | |
1173 | ||
1174 | tnum_strn(tn_buf, sizeof(tn_buf), regs[regno].var_off); | |
61bd5218 | 1175 | verbose(env, "invalid variable stack read R%d var_off=%s\n", |
f1174f77 EC |
1176 | regno, tn_buf); |
1177 | } | |
1178 | off = regs[regno].off + regs[regno].var_off.value; | |
17a52670 AS |
1179 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || |
1180 | access_size <= 0) { | |
61bd5218 | 1181 | verbose(env, "invalid stack type R%d off=%d access_size=%d\n", |
17a52670 AS |
1182 | regno, off, access_size); |
1183 | return -EACCES; | |
1184 | } | |
1185 | ||
8726679a AS |
1186 | if (env->prog->aux->stack_depth < -off) |
1187 | env->prog->aux->stack_depth = -off; | |
1188 | ||
435faee1 DB |
1189 | if (meta && meta->raw_mode) { |
1190 | meta->access_size = access_size; | |
1191 | meta->regno = regno; | |
1192 | return 0; | |
1193 | } | |
1194 | ||
17a52670 | 1195 | for (i = 0; i < access_size; i++) { |
9c399760 | 1196 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
61bd5218 | 1197 | verbose(env, "invalid indirect read from stack off %d+%d size %d\n", |
17a52670 AS |
1198 | off, i, access_size); |
1199 | return -EACCES; | |
1200 | } | |
1201 | } | |
1202 | return 0; | |
1203 | } | |
1204 | ||
06c1c049 GB |
1205 | static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, |
1206 | int access_size, bool zero_size_allowed, | |
1207 | struct bpf_call_arg_meta *meta) | |
1208 | { | |
f1174f77 | 1209 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
06c1c049 | 1210 | |
f1174f77 | 1211 | switch (reg->type) { |
06c1c049 | 1212 | case PTR_TO_PACKET: |
de8f3a83 | 1213 | case PTR_TO_PACKET_META: |
f1174f77 | 1214 | return check_packet_access(env, regno, reg->off, access_size); |
06c1c049 | 1215 | case PTR_TO_MAP_VALUE: |
f1174f77 EC |
1216 | return check_map_access(env, regno, reg->off, access_size); |
1217 | default: /* scalar_value|ptr_to_stack or invalid ptr */ | |
06c1c049 GB |
1218 | return check_stack_boundary(env, regno, access_size, |
1219 | zero_size_allowed, meta); | |
1220 | } | |
1221 | } | |
1222 | ||
58e2af8b | 1223 | static int check_func_arg(struct bpf_verifier_env *env, u32 regno, |
33ff9823 DB |
1224 | enum bpf_arg_type arg_type, |
1225 | struct bpf_call_arg_meta *meta) | |
17a52670 | 1226 | { |
58e2af8b | 1227 | struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
6841de8b | 1228 | enum bpf_reg_type expected_type, type = reg->type; |
17a52670 AS |
1229 | int err = 0; |
1230 | ||
80f1d68c | 1231 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
1232 | return 0; |
1233 | ||
dc503a8a EC |
1234 | err = check_reg_arg(env, regno, SRC_OP); |
1235 | if (err) | |
1236 | return err; | |
17a52670 | 1237 | |
1be7f75d AS |
1238 | if (arg_type == ARG_ANYTHING) { |
1239 | if (is_pointer_value(env, regno)) { | |
61bd5218 JK |
1240 | verbose(env, "R%d leaks addr into helper function\n", |
1241 | regno); | |
1be7f75d AS |
1242 | return -EACCES; |
1243 | } | |
80f1d68c | 1244 | return 0; |
1be7f75d | 1245 | } |
80f1d68c | 1246 | |
de8f3a83 | 1247 | if (type_is_pkt_pointer(type) && |
3a0af8fd | 1248 | !may_access_direct_pkt_data(env, meta, BPF_READ)) { |
61bd5218 | 1249 | verbose(env, "helper access to the packet is not allowed\n"); |
6841de8b AS |
1250 | return -EACCES; |
1251 | } | |
1252 | ||
8e2fe1d9 | 1253 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
1254 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
1255 | expected_type = PTR_TO_STACK; | |
de8f3a83 DB |
1256 | if (!type_is_pkt_pointer(type) && |
1257 | type != expected_type) | |
6841de8b | 1258 | goto err_type; |
39f19ebb AS |
1259 | } else if (arg_type == ARG_CONST_SIZE || |
1260 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
f1174f77 EC |
1261 | expected_type = SCALAR_VALUE; |
1262 | if (type != expected_type) | |
6841de8b | 1263 | goto err_type; |
17a52670 AS |
1264 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
1265 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
1266 | if (type != expected_type) |
1267 | goto err_type; | |
608cd71a AS |
1268 | } else if (arg_type == ARG_PTR_TO_CTX) { |
1269 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
1270 | if (type != expected_type) |
1271 | goto err_type; | |
39f19ebb AS |
1272 | } else if (arg_type == ARG_PTR_TO_MEM || |
1273 | arg_type == ARG_PTR_TO_UNINIT_MEM) { | |
8e2fe1d9 DB |
1274 | expected_type = PTR_TO_STACK; |
1275 | /* One exception here. In case function allows for NULL to be | |
f1174f77 | 1276 | * passed in as argument, it's a SCALAR_VALUE type. Final test |
8e2fe1d9 DB |
1277 | * happens during stack boundary checking. |
1278 | */ | |
f1174f77 | 1279 | if (register_is_null(*reg)) |
6841de8b | 1280 | /* final test in check_stack_boundary() */; |
de8f3a83 DB |
1281 | else if (!type_is_pkt_pointer(type) && |
1282 | type != PTR_TO_MAP_VALUE && | |
f1174f77 | 1283 | type != expected_type) |
6841de8b | 1284 | goto err_type; |
39f19ebb | 1285 | meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; |
17a52670 | 1286 | } else { |
61bd5218 | 1287 | verbose(env, "unsupported arg_type %d\n", arg_type); |
17a52670 AS |
1288 | return -EFAULT; |
1289 | } | |
1290 | ||
17a52670 AS |
1291 | if (arg_type == ARG_CONST_MAP_PTR) { |
1292 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 1293 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
1294 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
1295 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
1296 | * check that [key, key + map->key_size) are within | |
1297 | * stack limits and initialized | |
1298 | */ | |
33ff9823 | 1299 | if (!meta->map_ptr) { |
17a52670 AS |
1300 | /* in function declaration map_ptr must come before |
1301 | * map_key, so that it's verified and known before | |
1302 | * we have to check map_key here. Otherwise it means | |
1303 | * that kernel subsystem misconfigured verifier | |
1304 | */ | |
61bd5218 | 1305 | verbose(env, "invalid map_ptr to access map->key\n"); |
17a52670 AS |
1306 | return -EACCES; |
1307 | } | |
de8f3a83 | 1308 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1309 | err = check_packet_access(env, regno, reg->off, |
6841de8b AS |
1310 | meta->map_ptr->key_size); |
1311 | else | |
1312 | err = check_stack_boundary(env, regno, | |
1313 | meta->map_ptr->key_size, | |
1314 | false, NULL); | |
17a52670 AS |
1315 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1316 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1317 | * check [value, value + map->value_size) validity | |
1318 | */ | |
33ff9823 | 1319 | if (!meta->map_ptr) { |
17a52670 | 1320 | /* kernel subsystem misconfigured verifier */ |
61bd5218 | 1321 | verbose(env, "invalid map_ptr to access map->value\n"); |
17a52670 AS |
1322 | return -EACCES; |
1323 | } | |
de8f3a83 | 1324 | if (type_is_pkt_pointer(type)) |
f1174f77 | 1325 | err = check_packet_access(env, regno, reg->off, |
6841de8b AS |
1326 | meta->map_ptr->value_size); |
1327 | else | |
1328 | err = check_stack_boundary(env, regno, | |
1329 | meta->map_ptr->value_size, | |
1330 | false, NULL); | |
39f19ebb AS |
1331 | } else if (arg_type == ARG_CONST_SIZE || |
1332 | arg_type == ARG_CONST_SIZE_OR_ZERO) { | |
1333 | bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); | |
17a52670 | 1334 | |
17a52670 AS |
1335 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1336 | * from stack pointer 'buf'. Check it | |
1337 | * note: regno == len, regno - 1 == buf | |
1338 | */ | |
1339 | if (regno == 0) { | |
1340 | /* kernel subsystem misconfigured verifier */ | |
61bd5218 JK |
1341 | verbose(env, |
1342 | "ARG_CONST_SIZE cannot be first argument\n"); | |
17a52670 AS |
1343 | return -EACCES; |
1344 | } | |
06c1c049 | 1345 | |
f1174f77 EC |
1346 | /* The register is SCALAR_VALUE; the access check |
1347 | * happens using its boundaries. | |
06c1c049 | 1348 | */ |
f1174f77 EC |
1349 | |
1350 | if (!tnum_is_const(reg->var_off)) | |
06c1c049 GB |
1351 | /* For unprivileged variable accesses, disable raw |
1352 | * mode so that the program is required to | |
1353 | * initialize all the memory that the helper could | |
1354 | * just partially fill up. | |
1355 | */ | |
1356 | meta = NULL; | |
1357 | ||
b03c9f9f | 1358 | if (reg->smin_value < 0) { |
61bd5218 | 1359 | verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", |
f1174f77 EC |
1360 | regno); |
1361 | return -EACCES; | |
1362 | } | |
06c1c049 | 1363 | |
b03c9f9f | 1364 | if (reg->umin_value == 0) { |
f1174f77 EC |
1365 | err = check_helper_mem_access(env, regno - 1, 0, |
1366 | zero_size_allowed, | |
1367 | meta); | |
06c1c049 GB |
1368 | if (err) |
1369 | return err; | |
06c1c049 | 1370 | } |
f1174f77 | 1371 | |
b03c9f9f | 1372 | if (reg->umax_value >= BPF_MAX_VAR_SIZ) { |
61bd5218 | 1373 | verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", |
f1174f77 EC |
1374 | regno); |
1375 | return -EACCES; | |
1376 | } | |
1377 | err = check_helper_mem_access(env, regno - 1, | |
b03c9f9f | 1378 | reg->umax_value, |
f1174f77 | 1379 | zero_size_allowed, meta); |
17a52670 AS |
1380 | } |
1381 | ||
1382 | return err; | |
6841de8b | 1383 | err_type: |
61bd5218 | 1384 | verbose(env, "R%d type=%s expected=%s\n", regno, |
6841de8b AS |
1385 | reg_type_str[type], reg_type_str[expected_type]); |
1386 | return -EACCES; | |
17a52670 AS |
1387 | } |
1388 | ||
61bd5218 JK |
1389 | static int check_map_func_compatibility(struct bpf_verifier_env *env, |
1390 | struct bpf_map *map, int func_id) | |
35578d79 | 1391 | { |
35578d79 KX |
1392 | if (!map) |
1393 | return 0; | |
1394 | ||
6aff67c8 AS |
1395 | /* We need a two way check, first is from map perspective ... */ |
1396 | switch (map->map_type) { | |
1397 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1398 | if (func_id != BPF_FUNC_tail_call) | |
1399 | goto error; | |
1400 | break; | |
1401 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1402 | if (func_id != BPF_FUNC_perf_event_read && | |
908432ca YS |
1403 | func_id != BPF_FUNC_perf_event_output && |
1404 | func_id != BPF_FUNC_perf_event_read_value) | |
6aff67c8 AS |
1405 | goto error; |
1406 | break; | |
1407 | case BPF_MAP_TYPE_STACK_TRACE: | |
1408 | if (func_id != BPF_FUNC_get_stackid) | |
1409 | goto error; | |
1410 | break; | |
4ed8ec52 | 1411 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1412 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1413 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1414 | goto error; |
1415 | break; | |
546ac1ff JF |
1416 | /* devmap returns a pointer to a live net_device ifindex that we cannot |
1417 | * allow to be modified from bpf side. So do not allow lookup elements | |
1418 | * for now. | |
1419 | */ | |
1420 | case BPF_MAP_TYPE_DEVMAP: | |
2ddf71e2 | 1421 | if (func_id != BPF_FUNC_redirect_map) |
546ac1ff JF |
1422 | goto error; |
1423 | break; | |
6710e112 JDB |
1424 | /* Restrict bpf side of cpumap, open when use-cases appear */ |
1425 | case BPF_MAP_TYPE_CPUMAP: | |
1426 | if (func_id != BPF_FUNC_redirect_map) | |
1427 | goto error; | |
1428 | break; | |
56f668df | 1429 | case BPF_MAP_TYPE_ARRAY_OF_MAPS: |
bcc6b1b7 | 1430 | case BPF_MAP_TYPE_HASH_OF_MAPS: |
56f668df MKL |
1431 | if (func_id != BPF_FUNC_map_lookup_elem) |
1432 | goto error; | |
16a43625 | 1433 | break; |
174a79ff JF |
1434 | case BPF_MAP_TYPE_SOCKMAP: |
1435 | if (func_id != BPF_FUNC_sk_redirect_map && | |
1436 | func_id != BPF_FUNC_sock_map_update && | |
1437 | func_id != BPF_FUNC_map_delete_elem) | |
1438 | goto error; | |
1439 | break; | |
6aff67c8 AS |
1440 | default: |
1441 | break; | |
1442 | } | |
1443 | ||
1444 | /* ... and second from the function itself. */ | |
1445 | switch (func_id) { | |
1446 | case BPF_FUNC_tail_call: | |
1447 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1448 | goto error; | |
1449 | break; | |
1450 | case BPF_FUNC_perf_event_read: | |
1451 | case BPF_FUNC_perf_event_output: | |
908432ca | 1452 | case BPF_FUNC_perf_event_read_value: |
6aff67c8 AS |
1453 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) |
1454 | goto error; | |
1455 | break; | |
1456 | case BPF_FUNC_get_stackid: | |
1457 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1458 | goto error; | |
1459 | break; | |
60d20f91 | 1460 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1461 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1462 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1463 | goto error; | |
1464 | break; | |
97f91a7c | 1465 | case BPF_FUNC_redirect_map: |
9c270af3 JDB |
1466 | if (map->map_type != BPF_MAP_TYPE_DEVMAP && |
1467 | map->map_type != BPF_MAP_TYPE_CPUMAP) | |
97f91a7c JF |
1468 | goto error; |
1469 | break; | |
174a79ff JF |
1470 | case BPF_FUNC_sk_redirect_map: |
1471 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1472 | goto error; | |
1473 | break; | |
1474 | case BPF_FUNC_sock_map_update: | |
1475 | if (map->map_type != BPF_MAP_TYPE_SOCKMAP) | |
1476 | goto error; | |
1477 | break; | |
6aff67c8 AS |
1478 | default: |
1479 | break; | |
35578d79 KX |
1480 | } |
1481 | ||
1482 | return 0; | |
6aff67c8 | 1483 | error: |
61bd5218 | 1484 | verbose(env, "cannot pass map_type %d into func %s#%d\n", |
ebb676da | 1485 | map->map_type, func_id_name(func_id), func_id); |
6aff67c8 | 1486 | return -EINVAL; |
35578d79 KX |
1487 | } |
1488 | ||
435faee1 DB |
1489 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1490 | { | |
1491 | int count = 0; | |
1492 | ||
39f19ebb | 1493 | if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1494 | count++; |
39f19ebb | 1495 | if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1496 | count++; |
39f19ebb | 1497 | if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1498 | count++; |
39f19ebb | 1499 | if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 | 1500 | count++; |
39f19ebb | 1501 | if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) |
435faee1 DB |
1502 | count++; |
1503 | ||
1504 | return count > 1 ? -EINVAL : 0; | |
1505 | } | |
1506 | ||
de8f3a83 DB |
1507 | /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END] |
1508 | * are now invalid, so turn them into unknown SCALAR_VALUE. | |
f1174f77 | 1509 | */ |
58e2af8b | 1510 | static void clear_all_pkt_pointers(struct bpf_verifier_env *env) |
969bf05e | 1511 | { |
58e2af8b JK |
1512 | struct bpf_verifier_state *state = &env->cur_state; |
1513 | struct bpf_reg_state *regs = state->regs, *reg; | |
969bf05e AS |
1514 | int i; |
1515 | ||
1516 | for (i = 0; i < MAX_BPF_REG; i++) | |
de8f3a83 | 1517 | if (reg_is_pkt_pointer_any(®s[i])) |
61bd5218 | 1518 | mark_reg_unknown(env, regs, i); |
969bf05e AS |
1519 | |
1520 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1521 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1522 | continue; | |
1523 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
de8f3a83 DB |
1524 | if (reg_is_pkt_pointer_any(reg)) |
1525 | __mark_reg_unknown(reg); | |
969bf05e AS |
1526 | } |
1527 | } | |
1528 | ||
81ed18ab | 1529 | static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) |
17a52670 | 1530 | { |
58e2af8b | 1531 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 1532 | const struct bpf_func_proto *fn = NULL; |
58e2af8b | 1533 | struct bpf_reg_state *regs = state->regs; |
33ff9823 | 1534 | struct bpf_call_arg_meta meta; |
969bf05e | 1535 | bool changes_data; |
17a52670 AS |
1536 | int i, err; |
1537 | ||
1538 | /* find function prototype */ | |
1539 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
61bd5218 JK |
1540 | verbose(env, "invalid func %s#%d\n", func_id_name(func_id), |
1541 | func_id); | |
17a52670 AS |
1542 | return -EINVAL; |
1543 | } | |
1544 | ||
00176a34 JK |
1545 | if (env->ops->get_func_proto) |
1546 | fn = env->ops->get_func_proto(func_id); | |
17a52670 AS |
1547 | |
1548 | if (!fn) { | |
61bd5218 JK |
1549 | verbose(env, "unknown func %s#%d\n", func_id_name(func_id), |
1550 | func_id); | |
17a52670 AS |
1551 | return -EINVAL; |
1552 | } | |
1553 | ||
1554 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1555 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
61bd5218 | 1556 | verbose(env, "cannot call GPL only function from proprietary program\n"); |
17a52670 AS |
1557 | return -EINVAL; |
1558 | } | |
1559 | ||
17bedab2 | 1560 | changes_data = bpf_helper_changes_pkt_data(fn->func); |
969bf05e | 1561 | |
33ff9823 | 1562 | memset(&meta, 0, sizeof(meta)); |
36bbef52 | 1563 | meta.pkt_access = fn->pkt_access; |
33ff9823 | 1564 | |
435faee1 DB |
1565 | /* We only support one arg being in raw mode at the moment, which |
1566 | * is sufficient for the helper functions we have right now. | |
1567 | */ | |
1568 | err = check_raw_mode(fn); | |
1569 | if (err) { | |
61bd5218 | 1570 | verbose(env, "kernel subsystem misconfigured func %s#%d\n", |
ebb676da | 1571 | func_id_name(func_id), func_id); |
435faee1 DB |
1572 | return err; |
1573 | } | |
1574 | ||
17a52670 | 1575 | /* check args */ |
33ff9823 | 1576 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1577 | if (err) |
1578 | return err; | |
33ff9823 | 1579 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1580 | if (err) |
1581 | return err; | |
33ff9823 | 1582 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1583 | if (err) |
1584 | return err; | |
33ff9823 | 1585 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1586 | if (err) |
1587 | return err; | |
33ff9823 | 1588 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1589 | if (err) |
1590 | return err; | |
1591 | ||
435faee1 DB |
1592 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1593 | * is inferred from register state. | |
1594 | */ | |
1595 | for (i = 0; i < meta.access_size; i++) { | |
31fd8581 | 1596 | err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); |
435faee1 DB |
1597 | if (err) |
1598 | return err; | |
1599 | } | |
1600 | ||
17a52670 | 1601 | /* reset caller saved regs */ |
dc503a8a | 1602 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
61bd5218 | 1603 | mark_reg_not_init(env, regs, caller_saved[i]); |
dc503a8a EC |
1604 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
1605 | } | |
17a52670 | 1606 | |
dc503a8a | 1607 | /* update return register (already marked as written above) */ |
17a52670 | 1608 | if (fn->ret_type == RET_INTEGER) { |
f1174f77 | 1609 | /* sets type to SCALAR_VALUE */ |
61bd5218 | 1610 | mark_reg_unknown(env, regs, BPF_REG_0); |
17a52670 AS |
1611 | } else if (fn->ret_type == RET_VOID) { |
1612 | regs[BPF_REG_0].type = NOT_INIT; | |
1613 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
fad73a1a MKL |
1614 | struct bpf_insn_aux_data *insn_aux; |
1615 | ||
17a52670 | 1616 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; |
f1174f77 | 1617 | /* There is no offset yet applied, variable or fixed */ |
61bd5218 | 1618 | mark_reg_known_zero(env, regs, BPF_REG_0); |
f1174f77 | 1619 | regs[BPF_REG_0].off = 0; |
17a52670 AS |
1620 | /* remember map_ptr, so that check_map_access() |
1621 | * can check 'value_size' boundary of memory access | |
1622 | * to map element returned from bpf_map_lookup_elem() | |
1623 | */ | |
33ff9823 | 1624 | if (meta.map_ptr == NULL) { |
61bd5218 JK |
1625 | verbose(env, |
1626 | "kernel subsystem misconfigured verifier\n"); | |
17a52670 AS |
1627 | return -EINVAL; |
1628 | } | |
33ff9823 | 1629 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
57a09bf0 | 1630 | regs[BPF_REG_0].id = ++env->id_gen; |
fad73a1a MKL |
1631 | insn_aux = &env->insn_aux_data[insn_idx]; |
1632 | if (!insn_aux->map_ptr) | |
1633 | insn_aux->map_ptr = meta.map_ptr; | |
1634 | else if (insn_aux->map_ptr != meta.map_ptr) | |
1635 | insn_aux->map_ptr = BPF_MAP_PTR_POISON; | |
17a52670 | 1636 | } else { |
61bd5218 | 1637 | verbose(env, "unknown return type %d of func %s#%d\n", |
ebb676da | 1638 | fn->ret_type, func_id_name(func_id), func_id); |
17a52670 AS |
1639 | return -EINVAL; |
1640 | } | |
04fd61ab | 1641 | |
61bd5218 | 1642 | err = check_map_func_compatibility(env, meta.map_ptr, func_id); |
35578d79 KX |
1643 | if (err) |
1644 | return err; | |
04fd61ab | 1645 | |
969bf05e AS |
1646 | if (changes_data) |
1647 | clear_all_pkt_pointers(env); | |
1648 | return 0; | |
1649 | } | |
1650 | ||
f1174f77 EC |
1651 | static void coerce_reg_to_32(struct bpf_reg_state *reg) |
1652 | { | |
f1174f77 EC |
1653 | /* clear high 32 bits */ |
1654 | reg->var_off = tnum_cast(reg->var_off, 4); | |
b03c9f9f EC |
1655 | /* Update bounds */ |
1656 | __update_reg_bounds(reg); | |
1657 | } | |
1658 | ||
1659 | static bool signed_add_overflows(s64 a, s64 b) | |
1660 | { | |
1661 | /* Do the add in u64, where overflow is well-defined */ | |
1662 | s64 res = (s64)((u64)a + (u64)b); | |
1663 | ||
1664 | if (b < 0) | |
1665 | return res > a; | |
1666 | return res < a; | |
1667 | } | |
1668 | ||
1669 | static bool signed_sub_overflows(s64 a, s64 b) | |
1670 | { | |
1671 | /* Do the sub in u64, where overflow is well-defined */ | |
1672 | s64 res = (s64)((u64)a - (u64)b); | |
1673 | ||
1674 | if (b < 0) | |
1675 | return res < a; | |
1676 | return res > a; | |
969bf05e AS |
1677 | } |
1678 | ||
f1174f77 | 1679 | /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. |
f1174f77 EC |
1680 | * Caller should also handle BPF_MOV case separately. |
1681 | * If we return -EACCES, caller may want to try again treating pointer as a | |
1682 | * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks. | |
1683 | */ | |
1684 | static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, | |
1685 | struct bpf_insn *insn, | |
1686 | const struct bpf_reg_state *ptr_reg, | |
1687 | const struct bpf_reg_state *off_reg) | |
969bf05e | 1688 | { |
f1174f77 EC |
1689 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; |
1690 | bool known = tnum_is_const(off_reg->var_off); | |
b03c9f9f EC |
1691 | s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, |
1692 | smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; | |
1693 | u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, | |
1694 | umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; | |
969bf05e | 1695 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 1696 | u32 dst = insn->dst_reg; |
969bf05e | 1697 | |
f1174f77 | 1698 | dst_reg = ®s[dst]; |
969bf05e | 1699 | |
b03c9f9f | 1700 | if (WARN_ON_ONCE(known && (smin_val != smax_val))) { |
61bd5218 JK |
1701 | print_verifier_state(env, &env->cur_state); |
1702 | verbose(env, | |
1703 | "verifier internal error: known but bad sbounds\n"); | |
b03c9f9f EC |
1704 | return -EINVAL; |
1705 | } | |
1706 | if (WARN_ON_ONCE(known && (umin_val != umax_val))) { | |
61bd5218 JK |
1707 | print_verifier_state(env, &env->cur_state); |
1708 | verbose(env, | |
1709 | "verifier internal error: known but bad ubounds\n"); | |
f1174f77 EC |
1710 | return -EINVAL; |
1711 | } | |
1712 | ||
1713 | if (BPF_CLASS(insn->code) != BPF_ALU64) { | |
1714 | /* 32-bit ALU ops on pointers produce (meaningless) scalars */ | |
1715 | if (!env->allow_ptr_leaks) | |
61bd5218 JK |
1716 | verbose(env, |
1717 | "R%d 32-bit pointer arithmetic prohibited\n", | |
f1174f77 EC |
1718 | dst); |
1719 | return -EACCES; | |
969bf05e AS |
1720 | } |
1721 | ||
f1174f77 EC |
1722 | if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { |
1723 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1724 | verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n", |
f1174f77 EC |
1725 | dst); |
1726 | return -EACCES; | |
1727 | } | |
1728 | if (ptr_reg->type == CONST_PTR_TO_MAP) { | |
1729 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1730 | verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n", |
f1174f77 EC |
1731 | dst); |
1732 | return -EACCES; | |
1733 | } | |
1734 | if (ptr_reg->type == PTR_TO_PACKET_END) { | |
1735 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1736 | verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n", |
f1174f77 EC |
1737 | dst); |
1738 | return -EACCES; | |
1739 | } | |
1740 | ||
1741 | /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. | |
1742 | * The id may be overwritten later if we create a new variable offset. | |
969bf05e | 1743 | */ |
f1174f77 EC |
1744 | dst_reg->type = ptr_reg->type; |
1745 | dst_reg->id = ptr_reg->id; | |
969bf05e | 1746 | |
f1174f77 EC |
1747 | switch (opcode) { |
1748 | case BPF_ADD: | |
1749 | /* We can take a fixed offset as long as it doesn't overflow | |
1750 | * the s32 'off' field | |
969bf05e | 1751 | */ |
b03c9f9f EC |
1752 | if (known && (ptr_reg->off + smin_val == |
1753 | (s64)(s32)(ptr_reg->off + smin_val))) { | |
f1174f77 | 1754 | /* pointer += K. Accumulate it into fixed offset */ |
b03c9f9f EC |
1755 | dst_reg->smin_value = smin_ptr; |
1756 | dst_reg->smax_value = smax_ptr; | |
1757 | dst_reg->umin_value = umin_ptr; | |
1758 | dst_reg->umax_value = umax_ptr; | |
f1174f77 | 1759 | dst_reg->var_off = ptr_reg->var_off; |
b03c9f9f | 1760 | dst_reg->off = ptr_reg->off + smin_val; |
f1174f77 EC |
1761 | dst_reg->range = ptr_reg->range; |
1762 | break; | |
1763 | } | |
f1174f77 EC |
1764 | /* A new variable offset is created. Note that off_reg->off |
1765 | * == 0, since it's a scalar. | |
1766 | * dst_reg gets the pointer type and since some positive | |
1767 | * integer value was added to the pointer, give it a new 'id' | |
1768 | * if it's a PTR_TO_PACKET. | |
1769 | * this creates a new 'base' pointer, off_reg (variable) gets | |
1770 | * added into the variable offset, and we copy the fixed offset | |
1771 | * from ptr_reg. | |
969bf05e | 1772 | */ |
b03c9f9f EC |
1773 | if (signed_add_overflows(smin_ptr, smin_val) || |
1774 | signed_add_overflows(smax_ptr, smax_val)) { | |
1775 | dst_reg->smin_value = S64_MIN; | |
1776 | dst_reg->smax_value = S64_MAX; | |
1777 | } else { | |
1778 | dst_reg->smin_value = smin_ptr + smin_val; | |
1779 | dst_reg->smax_value = smax_ptr + smax_val; | |
1780 | } | |
1781 | if (umin_ptr + umin_val < umin_ptr || | |
1782 | umax_ptr + umax_val < umax_ptr) { | |
1783 | dst_reg->umin_value = 0; | |
1784 | dst_reg->umax_value = U64_MAX; | |
1785 | } else { | |
1786 | dst_reg->umin_value = umin_ptr + umin_val; | |
1787 | dst_reg->umax_value = umax_ptr + umax_val; | |
1788 | } | |
f1174f77 EC |
1789 | dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); |
1790 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 1791 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
1792 | dst_reg->id = ++env->id_gen; |
1793 | /* something was added to pkt_ptr, set range to zero */ | |
1794 | dst_reg->range = 0; | |
1795 | } | |
1796 | break; | |
1797 | case BPF_SUB: | |
1798 | if (dst_reg == off_reg) { | |
1799 | /* scalar -= pointer. Creates an unknown scalar */ | |
1800 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1801 | verbose(env, "R%d tried to subtract pointer from scalar\n", |
f1174f77 EC |
1802 | dst); |
1803 | return -EACCES; | |
1804 | } | |
1805 | /* We don't allow subtraction from FP, because (according to | |
1806 | * test_verifier.c test "invalid fp arithmetic", JITs might not | |
1807 | * be able to deal with it. | |
969bf05e | 1808 | */ |
f1174f77 EC |
1809 | if (ptr_reg->type == PTR_TO_STACK) { |
1810 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1811 | verbose(env, "R%d subtraction from stack pointer prohibited\n", |
f1174f77 EC |
1812 | dst); |
1813 | return -EACCES; | |
1814 | } | |
b03c9f9f EC |
1815 | if (known && (ptr_reg->off - smin_val == |
1816 | (s64)(s32)(ptr_reg->off - smin_val))) { | |
f1174f77 | 1817 | /* pointer -= K. Subtract it from fixed offset */ |
b03c9f9f EC |
1818 | dst_reg->smin_value = smin_ptr; |
1819 | dst_reg->smax_value = smax_ptr; | |
1820 | dst_reg->umin_value = umin_ptr; | |
1821 | dst_reg->umax_value = umax_ptr; | |
f1174f77 EC |
1822 | dst_reg->var_off = ptr_reg->var_off; |
1823 | dst_reg->id = ptr_reg->id; | |
b03c9f9f | 1824 | dst_reg->off = ptr_reg->off - smin_val; |
f1174f77 EC |
1825 | dst_reg->range = ptr_reg->range; |
1826 | break; | |
1827 | } | |
f1174f77 EC |
1828 | /* A new variable offset is created. If the subtrahend is known |
1829 | * nonnegative, then any reg->range we had before is still good. | |
969bf05e | 1830 | */ |
b03c9f9f EC |
1831 | if (signed_sub_overflows(smin_ptr, smax_val) || |
1832 | signed_sub_overflows(smax_ptr, smin_val)) { | |
1833 | /* Overflow possible, we know nothing */ | |
1834 | dst_reg->smin_value = S64_MIN; | |
1835 | dst_reg->smax_value = S64_MAX; | |
1836 | } else { | |
1837 | dst_reg->smin_value = smin_ptr - smax_val; | |
1838 | dst_reg->smax_value = smax_ptr - smin_val; | |
1839 | } | |
1840 | if (umin_ptr < umax_val) { | |
1841 | /* Overflow possible, we know nothing */ | |
1842 | dst_reg->umin_value = 0; | |
1843 | dst_reg->umax_value = U64_MAX; | |
1844 | } else { | |
1845 | /* Cannot overflow (as long as bounds are consistent) */ | |
1846 | dst_reg->umin_value = umin_ptr - umax_val; | |
1847 | dst_reg->umax_value = umax_ptr - umin_val; | |
1848 | } | |
f1174f77 EC |
1849 | dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); |
1850 | dst_reg->off = ptr_reg->off; | |
de8f3a83 | 1851 | if (reg_is_pkt_pointer(ptr_reg)) { |
f1174f77 EC |
1852 | dst_reg->id = ++env->id_gen; |
1853 | /* something was added to pkt_ptr, set range to zero */ | |
b03c9f9f | 1854 | if (smin_val < 0) |
f1174f77 | 1855 | dst_reg->range = 0; |
43188702 | 1856 | } |
f1174f77 EC |
1857 | break; |
1858 | case BPF_AND: | |
1859 | case BPF_OR: | |
1860 | case BPF_XOR: | |
1861 | /* bitwise ops on pointers are troublesome, prohibit for now. | |
1862 | * (However, in principle we could allow some cases, e.g. | |
1863 | * ptr &= ~3 which would reduce min_value by 3.) | |
1864 | */ | |
1865 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1866 | verbose(env, "R%d bitwise operator %s on pointer prohibited\n", |
f1174f77 EC |
1867 | dst, bpf_alu_string[opcode >> 4]); |
1868 | return -EACCES; | |
1869 | default: | |
1870 | /* other operators (e.g. MUL,LSH) produce non-pointer results */ | |
1871 | if (!env->allow_ptr_leaks) | |
61bd5218 | 1872 | verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", |
f1174f77 EC |
1873 | dst, bpf_alu_string[opcode >> 4]); |
1874 | return -EACCES; | |
43188702 JF |
1875 | } |
1876 | ||
b03c9f9f EC |
1877 | __update_reg_bounds(dst_reg); |
1878 | __reg_deduce_bounds(dst_reg); | |
1879 | __reg_bound_offset(dst_reg); | |
43188702 JF |
1880 | return 0; |
1881 | } | |
1882 | ||
f1174f77 EC |
1883 | static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, |
1884 | struct bpf_insn *insn, | |
1885 | struct bpf_reg_state *dst_reg, | |
1886 | struct bpf_reg_state src_reg) | |
969bf05e | 1887 | { |
58e2af8b | 1888 | struct bpf_reg_state *regs = env->cur_state.regs; |
48461135 | 1889 | u8 opcode = BPF_OP(insn->code); |
f1174f77 | 1890 | bool src_known, dst_known; |
b03c9f9f EC |
1891 | s64 smin_val, smax_val; |
1892 | u64 umin_val, umax_val; | |
48461135 | 1893 | |
f1174f77 EC |
1894 | if (BPF_CLASS(insn->code) != BPF_ALU64) { |
1895 | /* 32-bit ALU ops are (32,32)->64 */ | |
1896 | coerce_reg_to_32(dst_reg); | |
1897 | coerce_reg_to_32(&src_reg); | |
9305706c | 1898 | } |
b03c9f9f EC |
1899 | smin_val = src_reg.smin_value; |
1900 | smax_val = src_reg.smax_value; | |
1901 | umin_val = src_reg.umin_value; | |
1902 | umax_val = src_reg.umax_value; | |
f1174f77 EC |
1903 | src_known = tnum_is_const(src_reg.var_off); |
1904 | dst_known = tnum_is_const(dst_reg->var_off); | |
f23cc643 | 1905 | |
48461135 JB |
1906 | switch (opcode) { |
1907 | case BPF_ADD: | |
b03c9f9f EC |
1908 | if (signed_add_overflows(dst_reg->smin_value, smin_val) || |
1909 | signed_add_overflows(dst_reg->smax_value, smax_val)) { | |
1910 | dst_reg->smin_value = S64_MIN; | |
1911 | dst_reg->smax_value = S64_MAX; | |
1912 | } else { | |
1913 | dst_reg->smin_value += smin_val; | |
1914 | dst_reg->smax_value += smax_val; | |
1915 | } | |
1916 | if (dst_reg->umin_value + umin_val < umin_val || | |
1917 | dst_reg->umax_value + umax_val < umax_val) { | |
1918 | dst_reg->umin_value = 0; | |
1919 | dst_reg->umax_value = U64_MAX; | |
1920 | } else { | |
1921 | dst_reg->umin_value += umin_val; | |
1922 | dst_reg->umax_value += umax_val; | |
1923 | } | |
f1174f77 | 1924 | dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
1925 | break; |
1926 | case BPF_SUB: | |
b03c9f9f EC |
1927 | if (signed_sub_overflows(dst_reg->smin_value, smax_val) || |
1928 | signed_sub_overflows(dst_reg->smax_value, smin_val)) { | |
1929 | /* Overflow possible, we know nothing */ | |
1930 | dst_reg->smin_value = S64_MIN; | |
1931 | dst_reg->smax_value = S64_MAX; | |
1932 | } else { | |
1933 | dst_reg->smin_value -= smax_val; | |
1934 | dst_reg->smax_value -= smin_val; | |
1935 | } | |
1936 | if (dst_reg->umin_value < umax_val) { | |
1937 | /* Overflow possible, we know nothing */ | |
1938 | dst_reg->umin_value = 0; | |
1939 | dst_reg->umax_value = U64_MAX; | |
1940 | } else { | |
1941 | /* Cannot overflow (as long as bounds are consistent) */ | |
1942 | dst_reg->umin_value -= umax_val; | |
1943 | dst_reg->umax_value -= umin_val; | |
1944 | } | |
f1174f77 | 1945 | dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off); |
48461135 JB |
1946 | break; |
1947 | case BPF_MUL: | |
b03c9f9f EC |
1948 | dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off); |
1949 | if (smin_val < 0 || dst_reg->smin_value < 0) { | |
f1174f77 | 1950 | /* Ain't nobody got time to multiply that sign */ |
b03c9f9f EC |
1951 | __mark_reg_unbounded(dst_reg); |
1952 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
1953 | break; |
1954 | } | |
b03c9f9f EC |
1955 | /* Both values are positive, so we can work with unsigned and |
1956 | * copy the result to signed (unless it exceeds S64_MAX). | |
f1174f77 | 1957 | */ |
b03c9f9f EC |
1958 | if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) { |
1959 | /* Potential overflow, we know nothing */ | |
1960 | __mark_reg_unbounded(dst_reg); | |
1961 | /* (except what we can learn from the var_off) */ | |
1962 | __update_reg_bounds(dst_reg); | |
1963 | break; | |
1964 | } | |
1965 | dst_reg->umin_value *= umin_val; | |
1966 | dst_reg->umax_value *= umax_val; | |
1967 | if (dst_reg->umax_value > S64_MAX) { | |
1968 | /* Overflow possible, we know nothing */ | |
1969 | dst_reg->smin_value = S64_MIN; | |
1970 | dst_reg->smax_value = S64_MAX; | |
1971 | } else { | |
1972 | dst_reg->smin_value = dst_reg->umin_value; | |
1973 | dst_reg->smax_value = dst_reg->umax_value; | |
1974 | } | |
48461135 JB |
1975 | break; |
1976 | case BPF_AND: | |
f1174f77 | 1977 | if (src_known && dst_known) { |
b03c9f9f EC |
1978 | __mark_reg_known(dst_reg, dst_reg->var_off.value & |
1979 | src_reg.var_off.value); | |
f1174f77 EC |
1980 | break; |
1981 | } | |
b03c9f9f EC |
1982 | /* We get our minimum from the var_off, since that's inherently |
1983 | * bitwise. Our maximum is the minimum of the operands' maxima. | |
f23cc643 | 1984 | */ |
f1174f77 | 1985 | dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); |
b03c9f9f EC |
1986 | dst_reg->umin_value = dst_reg->var_off.value; |
1987 | dst_reg->umax_value = min(dst_reg->umax_value, umax_val); | |
1988 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
1989 | /* Lose signed bounds when ANDing negative numbers, | |
1990 | * ain't nobody got time for that. | |
1991 | */ | |
1992 | dst_reg->smin_value = S64_MIN; | |
1993 | dst_reg->smax_value = S64_MAX; | |
1994 | } else { | |
1995 | /* ANDing two positives gives a positive, so safe to | |
1996 | * cast result into s64. | |
1997 | */ | |
1998 | dst_reg->smin_value = dst_reg->umin_value; | |
1999 | dst_reg->smax_value = dst_reg->umax_value; | |
2000 | } | |
2001 | /* We may learn something more from the var_off */ | |
2002 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2003 | break; |
2004 | case BPF_OR: | |
2005 | if (src_known && dst_known) { | |
b03c9f9f EC |
2006 | __mark_reg_known(dst_reg, dst_reg->var_off.value | |
2007 | src_reg.var_off.value); | |
f1174f77 EC |
2008 | break; |
2009 | } | |
b03c9f9f EC |
2010 | /* We get our maximum from the var_off, and our minimum is the |
2011 | * maximum of the operands' minima | |
f1174f77 EC |
2012 | */ |
2013 | dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); | |
b03c9f9f EC |
2014 | dst_reg->umin_value = max(dst_reg->umin_value, umin_val); |
2015 | dst_reg->umax_value = dst_reg->var_off.value | | |
2016 | dst_reg->var_off.mask; | |
2017 | if (dst_reg->smin_value < 0 || smin_val < 0) { | |
2018 | /* Lose signed bounds when ORing negative numbers, | |
2019 | * ain't nobody got time for that. | |
2020 | */ | |
2021 | dst_reg->smin_value = S64_MIN; | |
2022 | dst_reg->smax_value = S64_MAX; | |
f1174f77 | 2023 | } else { |
b03c9f9f EC |
2024 | /* ORing two positives gives a positive, so safe to |
2025 | * cast result into s64. | |
2026 | */ | |
2027 | dst_reg->smin_value = dst_reg->umin_value; | |
2028 | dst_reg->smax_value = dst_reg->umax_value; | |
f1174f77 | 2029 | } |
b03c9f9f EC |
2030 | /* We may learn something more from the var_off */ |
2031 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2032 | break; |
2033 | case BPF_LSH: | |
b03c9f9f EC |
2034 | if (umax_val > 63) { |
2035 | /* Shifts greater than 63 are undefined. This includes | |
2036 | * shifts by a negative number. | |
2037 | */ | |
61bd5218 | 2038 | mark_reg_unknown(env, regs, insn->dst_reg); |
f1174f77 EC |
2039 | break; |
2040 | } | |
b03c9f9f EC |
2041 | /* We lose all sign bit information (except what we can pick |
2042 | * up from var_off) | |
48461135 | 2043 | */ |
b03c9f9f EC |
2044 | dst_reg->smin_value = S64_MIN; |
2045 | dst_reg->smax_value = S64_MAX; | |
2046 | /* If we might shift our top bit out, then we know nothing */ | |
2047 | if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { | |
2048 | dst_reg->umin_value = 0; | |
2049 | dst_reg->umax_value = U64_MAX; | |
d1174416 | 2050 | } else { |
b03c9f9f EC |
2051 | dst_reg->umin_value <<= umin_val; |
2052 | dst_reg->umax_value <<= umax_val; | |
d1174416 | 2053 | } |
b03c9f9f EC |
2054 | if (src_known) |
2055 | dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); | |
2056 | else | |
2057 | dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val); | |
2058 | /* We may learn something more from the var_off */ | |
2059 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2060 | break; |
2061 | case BPF_RSH: | |
b03c9f9f EC |
2062 | if (umax_val > 63) { |
2063 | /* Shifts greater than 63 are undefined. This includes | |
2064 | * shifts by a negative number. | |
2065 | */ | |
61bd5218 | 2066 | mark_reg_unknown(env, regs, insn->dst_reg); |
f1174f77 EC |
2067 | break; |
2068 | } | |
2069 | /* BPF_RSH is an unsigned shift, so make the appropriate casts */ | |
b03c9f9f EC |
2070 | if (dst_reg->smin_value < 0) { |
2071 | if (umin_val) { | |
f1174f77 | 2072 | /* Sign bit will be cleared */ |
b03c9f9f EC |
2073 | dst_reg->smin_value = 0; |
2074 | } else { | |
2075 | /* Lost sign bit information */ | |
2076 | dst_reg->smin_value = S64_MIN; | |
2077 | dst_reg->smax_value = S64_MAX; | |
2078 | } | |
d1174416 | 2079 | } else { |
b03c9f9f EC |
2080 | dst_reg->smin_value = |
2081 | (u64)(dst_reg->smin_value) >> umax_val; | |
d1174416 | 2082 | } |
f1174f77 | 2083 | if (src_known) |
b03c9f9f EC |
2084 | dst_reg->var_off = tnum_rshift(dst_reg->var_off, |
2085 | umin_val); | |
f1174f77 | 2086 | else |
b03c9f9f EC |
2087 | dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val); |
2088 | dst_reg->umin_value >>= umax_val; | |
2089 | dst_reg->umax_value >>= umin_val; | |
2090 | /* We may learn something more from the var_off */ | |
2091 | __update_reg_bounds(dst_reg); | |
48461135 JB |
2092 | break; |
2093 | default: | |
61bd5218 | 2094 | mark_reg_unknown(env, regs, insn->dst_reg); |
48461135 JB |
2095 | break; |
2096 | } | |
2097 | ||
b03c9f9f EC |
2098 | __reg_deduce_bounds(dst_reg); |
2099 | __reg_bound_offset(dst_reg); | |
f1174f77 EC |
2100 | return 0; |
2101 | } | |
2102 | ||
2103 | /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max | |
2104 | * and var_off. | |
2105 | */ | |
2106 | static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, | |
2107 | struct bpf_insn *insn) | |
2108 | { | |
2109 | struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg, *src_reg; | |
2110 | struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; | |
2111 | u8 opcode = BPF_OP(insn->code); | |
2112 | int rc; | |
2113 | ||
2114 | dst_reg = ®s[insn->dst_reg]; | |
f1174f77 EC |
2115 | src_reg = NULL; |
2116 | if (dst_reg->type != SCALAR_VALUE) | |
2117 | ptr_reg = dst_reg; | |
2118 | if (BPF_SRC(insn->code) == BPF_X) { | |
2119 | src_reg = ®s[insn->src_reg]; | |
f1174f77 EC |
2120 | if (src_reg->type != SCALAR_VALUE) { |
2121 | if (dst_reg->type != SCALAR_VALUE) { | |
2122 | /* Combining two pointers by any ALU op yields | |
2123 | * an arbitrary scalar. | |
2124 | */ | |
2125 | if (!env->allow_ptr_leaks) { | |
61bd5218 | 2126 | verbose(env, "R%d pointer %s pointer prohibited\n", |
f1174f77 EC |
2127 | insn->dst_reg, |
2128 | bpf_alu_string[opcode >> 4]); | |
2129 | return -EACCES; | |
2130 | } | |
61bd5218 | 2131 | mark_reg_unknown(env, regs, insn->dst_reg); |
f1174f77 EC |
2132 | return 0; |
2133 | } else { | |
2134 | /* scalar += pointer | |
2135 | * This is legal, but we have to reverse our | |
2136 | * src/dest handling in computing the range | |
2137 | */ | |
2138 | rc = adjust_ptr_min_max_vals(env, insn, | |
2139 | src_reg, dst_reg); | |
2140 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2141 | /* scalar += unknown scalar */ | |
2142 | __mark_reg_unknown(&off_reg); | |
2143 | return adjust_scalar_min_max_vals( | |
2144 | env, insn, | |
2145 | dst_reg, off_reg); | |
2146 | } | |
2147 | return rc; | |
2148 | } | |
2149 | } else if (ptr_reg) { | |
2150 | /* pointer += scalar */ | |
2151 | rc = adjust_ptr_min_max_vals(env, insn, | |
2152 | dst_reg, src_reg); | |
2153 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2154 | /* unknown scalar += scalar */ | |
2155 | __mark_reg_unknown(dst_reg); | |
2156 | return adjust_scalar_min_max_vals( | |
2157 | env, insn, dst_reg, *src_reg); | |
2158 | } | |
2159 | return rc; | |
2160 | } | |
2161 | } else { | |
2162 | /* Pretend the src is a reg with a known value, since we only | |
2163 | * need to be able to read from this state. | |
2164 | */ | |
2165 | off_reg.type = SCALAR_VALUE; | |
b03c9f9f | 2166 | __mark_reg_known(&off_reg, insn->imm); |
f1174f77 | 2167 | src_reg = &off_reg; |
f1174f77 EC |
2168 | if (ptr_reg) { /* pointer += K */ |
2169 | rc = adjust_ptr_min_max_vals(env, insn, | |
2170 | ptr_reg, src_reg); | |
2171 | if (rc == -EACCES && env->allow_ptr_leaks) { | |
2172 | /* unknown scalar += K */ | |
2173 | __mark_reg_unknown(dst_reg); | |
2174 | return adjust_scalar_min_max_vals( | |
2175 | env, insn, dst_reg, off_reg); | |
2176 | } | |
2177 | return rc; | |
2178 | } | |
2179 | } | |
2180 | ||
2181 | /* Got here implies adding two SCALAR_VALUEs */ | |
2182 | if (WARN_ON_ONCE(ptr_reg)) { | |
61bd5218 JK |
2183 | print_verifier_state(env, &env->cur_state); |
2184 | verbose(env, "verifier internal error: unexpected ptr_reg\n"); | |
f1174f77 EC |
2185 | return -EINVAL; |
2186 | } | |
2187 | if (WARN_ON(!src_reg)) { | |
61bd5218 JK |
2188 | print_verifier_state(env, &env->cur_state); |
2189 | verbose(env, "verifier internal error: no src_reg\n"); | |
f1174f77 EC |
2190 | return -EINVAL; |
2191 | } | |
2192 | return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg); | |
48461135 JB |
2193 | } |
2194 | ||
17a52670 | 2195 | /* check validity of 32-bit and 64-bit arithmetic operations */ |
58e2af8b | 2196 | static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2197 | { |
f1174f77 | 2198 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2199 | u8 opcode = BPF_OP(insn->code); |
2200 | int err; | |
2201 | ||
2202 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
2203 | if (opcode == BPF_NEG) { | |
2204 | if (BPF_SRC(insn->code) != 0 || | |
2205 | insn->src_reg != BPF_REG_0 || | |
2206 | insn->off != 0 || insn->imm != 0) { | |
61bd5218 | 2207 | verbose(env, "BPF_NEG uses reserved fields\n"); |
17a52670 AS |
2208 | return -EINVAL; |
2209 | } | |
2210 | } else { | |
2211 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
e67b8a68 EC |
2212 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || |
2213 | BPF_CLASS(insn->code) == BPF_ALU64) { | |
61bd5218 | 2214 | verbose(env, "BPF_END uses reserved fields\n"); |
17a52670 AS |
2215 | return -EINVAL; |
2216 | } | |
2217 | } | |
2218 | ||
2219 | /* check src operand */ | |
dc503a8a | 2220 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2221 | if (err) |
2222 | return err; | |
2223 | ||
1be7f75d | 2224 | if (is_pointer_value(env, insn->dst_reg)) { |
61bd5218 | 2225 | verbose(env, "R%d pointer arithmetic prohibited\n", |
1be7f75d AS |
2226 | insn->dst_reg); |
2227 | return -EACCES; | |
2228 | } | |
2229 | ||
17a52670 | 2230 | /* check dest operand */ |
dc503a8a | 2231 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2232 | if (err) |
2233 | return err; | |
2234 | ||
2235 | } else if (opcode == BPF_MOV) { | |
2236 | ||
2237 | if (BPF_SRC(insn->code) == BPF_X) { | |
2238 | if (insn->imm != 0 || insn->off != 0) { | |
61bd5218 | 2239 | verbose(env, "BPF_MOV uses reserved fields\n"); |
17a52670 AS |
2240 | return -EINVAL; |
2241 | } | |
2242 | ||
2243 | /* check src operand */ | |
dc503a8a | 2244 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2245 | if (err) |
2246 | return err; | |
2247 | } else { | |
2248 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
61bd5218 | 2249 | verbose(env, "BPF_MOV uses reserved fields\n"); |
17a52670 AS |
2250 | return -EINVAL; |
2251 | } | |
2252 | } | |
2253 | ||
2254 | /* check dest operand */ | |
dc503a8a | 2255 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2256 | if (err) |
2257 | return err; | |
2258 | ||
2259 | if (BPF_SRC(insn->code) == BPF_X) { | |
2260 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
2261 | /* case: R1 = R2 | |
2262 | * copy register state to dest reg | |
2263 | */ | |
2264 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
8fe2d6cc | 2265 | regs[insn->dst_reg].live |= REG_LIVE_WRITTEN; |
17a52670 | 2266 | } else { |
f1174f77 | 2267 | /* R1 = (u32) R2 */ |
1be7f75d | 2268 | if (is_pointer_value(env, insn->src_reg)) { |
61bd5218 JK |
2269 | verbose(env, |
2270 | "R%d partial copy of pointer\n", | |
1be7f75d AS |
2271 | insn->src_reg); |
2272 | return -EACCES; | |
2273 | } | |
61bd5218 | 2274 | mark_reg_unknown(env, regs, insn->dst_reg); |
b03c9f9f | 2275 | /* high 32 bits are known zero. */ |
f1174f77 EC |
2276 | regs[insn->dst_reg].var_off = tnum_cast( |
2277 | regs[insn->dst_reg].var_off, 4); | |
b03c9f9f | 2278 | __update_reg_bounds(®s[insn->dst_reg]); |
17a52670 AS |
2279 | } |
2280 | } else { | |
2281 | /* case: R = imm | |
2282 | * remember the value we stored into this reg | |
2283 | */ | |
f1174f77 | 2284 | regs[insn->dst_reg].type = SCALAR_VALUE; |
b03c9f9f | 2285 | __mark_reg_known(regs + insn->dst_reg, insn->imm); |
17a52670 AS |
2286 | } |
2287 | ||
2288 | } else if (opcode > BPF_END) { | |
61bd5218 | 2289 | verbose(env, "invalid BPF_ALU opcode %x\n", opcode); |
17a52670 AS |
2290 | return -EINVAL; |
2291 | ||
2292 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
2293 | ||
17a52670 AS |
2294 | if (BPF_SRC(insn->code) == BPF_X) { |
2295 | if (insn->imm != 0 || insn->off != 0) { | |
61bd5218 | 2296 | verbose(env, "BPF_ALU uses reserved fields\n"); |
17a52670 AS |
2297 | return -EINVAL; |
2298 | } | |
2299 | /* check src1 operand */ | |
dc503a8a | 2300 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2301 | if (err) |
2302 | return err; | |
2303 | } else { | |
2304 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
61bd5218 | 2305 | verbose(env, "BPF_ALU uses reserved fields\n"); |
17a52670 AS |
2306 | return -EINVAL; |
2307 | } | |
2308 | } | |
2309 | ||
2310 | /* check src2 operand */ | |
dc503a8a | 2311 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2312 | if (err) |
2313 | return err; | |
2314 | ||
2315 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
2316 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
61bd5218 | 2317 | verbose(env, "div by zero\n"); |
17a52670 AS |
2318 | return -EINVAL; |
2319 | } | |
2320 | ||
229394e8 RV |
2321 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
2322 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
2323 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
2324 | ||
2325 | if (insn->imm < 0 || insn->imm >= size) { | |
61bd5218 | 2326 | verbose(env, "invalid shift %d\n", insn->imm); |
229394e8 RV |
2327 | return -EINVAL; |
2328 | } | |
2329 | } | |
2330 | ||
1a0dc1ac | 2331 | /* check dest operand */ |
dc503a8a | 2332 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
1a0dc1ac AS |
2333 | if (err) |
2334 | return err; | |
2335 | ||
f1174f77 | 2336 | return adjust_reg_min_max_vals(env, insn); |
17a52670 AS |
2337 | } |
2338 | ||
2339 | return 0; | |
2340 | } | |
2341 | ||
58e2af8b | 2342 | static void find_good_pkt_pointers(struct bpf_verifier_state *state, |
de8f3a83 DB |
2343 | struct bpf_reg_state *dst_reg, |
2344 | enum bpf_reg_type type) | |
969bf05e | 2345 | { |
58e2af8b | 2346 | struct bpf_reg_state *regs = state->regs, *reg; |
969bf05e | 2347 | int i; |
2d2be8ca | 2348 | |
f1174f77 EC |
2349 | if (dst_reg->off < 0) |
2350 | /* This doesn't give us any range */ | |
2351 | return; | |
2352 | ||
b03c9f9f EC |
2353 | if (dst_reg->umax_value > MAX_PACKET_OFF || |
2354 | dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) | |
f1174f77 EC |
2355 | /* Risk of overflow. For instance, ptr + (1<<63) may be less |
2356 | * than pkt_end, but that's because it's also less than pkt. | |
2357 | */ | |
2358 | return; | |
2359 | ||
b4e432f1 | 2360 | /* LLVM can generate four kind of checks: |
2d2be8ca | 2361 | * |
b4e432f1 | 2362 | * Type 1/2: |
2d2be8ca DB |
2363 | * |
2364 | * r2 = r3; | |
2365 | * r2 += 8; | |
2366 | * if (r2 > pkt_end) goto <handle exception> | |
2367 | * <access okay> | |
2368 | * | |
b4e432f1 DB |
2369 | * r2 = r3; |
2370 | * r2 += 8; | |
2371 | * if (r2 < pkt_end) goto <access okay> | |
2372 | * <handle exception> | |
2373 | * | |
2d2be8ca DB |
2374 | * Where: |
2375 | * r2 == dst_reg, pkt_end == src_reg | |
2376 | * r2=pkt(id=n,off=8,r=0) | |
2377 | * r3=pkt(id=n,off=0,r=0) | |
2378 | * | |
b4e432f1 | 2379 | * Type 3/4: |
2d2be8ca DB |
2380 | * |
2381 | * r2 = r3; | |
2382 | * r2 += 8; | |
2383 | * if (pkt_end >= r2) goto <access okay> | |
2384 | * <handle exception> | |
2385 | * | |
b4e432f1 DB |
2386 | * r2 = r3; |
2387 | * r2 += 8; | |
2388 | * if (pkt_end <= r2) goto <handle exception> | |
2389 | * <access okay> | |
2390 | * | |
2d2be8ca DB |
2391 | * Where: |
2392 | * pkt_end == dst_reg, r2 == src_reg | |
2393 | * r2=pkt(id=n,off=8,r=0) | |
2394 | * r3=pkt(id=n,off=0,r=0) | |
2395 | * | |
2396 | * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
2397 | * so that range of bytes [r3, r3 + 8) is safe to access. | |
969bf05e | 2398 | */ |
2d2be8ca | 2399 | |
f1174f77 EC |
2400 | /* If our ids match, then we must have the same max_value. And we |
2401 | * don't care about the other reg's fixed offset, since if it's too big | |
2402 | * the range won't allow anything. | |
2403 | * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16. | |
2404 | */ | |
969bf05e | 2405 | for (i = 0; i < MAX_BPF_REG; i++) |
de8f3a83 | 2406 | if (regs[i].type == type && regs[i].id == dst_reg->id) |
b1977682 | 2407 | /* keep the maximum range already checked */ |
f1174f77 | 2408 | regs[i].range = max_t(u16, regs[i].range, dst_reg->off); |
969bf05e AS |
2409 | |
2410 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2411 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2412 | continue; | |
2413 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
de8f3a83 | 2414 | if (reg->type == type && reg->id == dst_reg->id) |
f1174f77 | 2415 | reg->range = max_t(u16, reg->range, dst_reg->off); |
969bf05e AS |
2416 | } |
2417 | } | |
2418 | ||
48461135 JB |
2419 | /* Adjusts the register min/max values in the case that the dst_reg is the |
2420 | * variable register that we are working on, and src_reg is a constant or we're | |
2421 | * simply doing a BPF_K check. | |
f1174f77 | 2422 | * In JEQ/JNE cases we also adjust the var_off values. |
48461135 JB |
2423 | */ |
2424 | static void reg_set_min_max(struct bpf_reg_state *true_reg, | |
2425 | struct bpf_reg_state *false_reg, u64 val, | |
2426 | u8 opcode) | |
2427 | { | |
f1174f77 EC |
2428 | /* If the dst_reg is a pointer, we can't learn anything about its |
2429 | * variable offset from the compare (unless src_reg were a pointer into | |
2430 | * the same object, but we don't bother with that. | |
2431 | * Since false_reg and true_reg have the same type by construction, we | |
2432 | * only need to check one of them for pointerness. | |
2433 | */ | |
2434 | if (__is_pointer_value(false, false_reg)) | |
2435 | return; | |
4cabc5b1 | 2436 | |
48461135 JB |
2437 | switch (opcode) { |
2438 | case BPF_JEQ: | |
2439 | /* If this is false then we know nothing Jon Snow, but if it is | |
2440 | * true then we know for sure. | |
2441 | */ | |
b03c9f9f | 2442 | __mark_reg_known(true_reg, val); |
48461135 JB |
2443 | break; |
2444 | case BPF_JNE: | |
2445 | /* If this is true we know nothing Jon Snow, but if it is false | |
2446 | * we know the value for sure; | |
2447 | */ | |
b03c9f9f | 2448 | __mark_reg_known(false_reg, val); |
48461135 JB |
2449 | break; |
2450 | case BPF_JGT: | |
b03c9f9f EC |
2451 | false_reg->umax_value = min(false_reg->umax_value, val); |
2452 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2453 | break; | |
48461135 | 2454 | case BPF_JSGT: |
b03c9f9f EC |
2455 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); |
2456 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
48461135 | 2457 | break; |
b4e432f1 DB |
2458 | case BPF_JLT: |
2459 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2460 | true_reg->umax_value = min(true_reg->umax_value, val - 1); | |
2461 | break; | |
2462 | case BPF_JSLT: | |
2463 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
2464 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); | |
2465 | break; | |
48461135 | 2466 | case BPF_JGE: |
b03c9f9f EC |
2467 | false_reg->umax_value = min(false_reg->umax_value, val - 1); |
2468 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2469 | break; | |
48461135 | 2470 | case BPF_JSGE: |
b03c9f9f EC |
2471 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); |
2472 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
48461135 | 2473 | break; |
b4e432f1 DB |
2474 | case BPF_JLE: |
2475 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2476 | true_reg->umax_value = min(true_reg->umax_value, val); | |
2477 | break; | |
2478 | case BPF_JSLE: | |
2479 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
2480 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); | |
2481 | break; | |
48461135 JB |
2482 | default: |
2483 | break; | |
2484 | } | |
2485 | ||
b03c9f9f EC |
2486 | __reg_deduce_bounds(false_reg); |
2487 | __reg_deduce_bounds(true_reg); | |
2488 | /* We might have learned some bits from the bounds. */ | |
2489 | __reg_bound_offset(false_reg); | |
2490 | __reg_bound_offset(true_reg); | |
2491 | /* Intersecting with the old var_off might have improved our bounds | |
2492 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2493 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2494 | */ | |
2495 | __update_reg_bounds(false_reg); | |
2496 | __update_reg_bounds(true_reg); | |
48461135 JB |
2497 | } |
2498 | ||
f1174f77 EC |
2499 | /* Same as above, but for the case that dst_reg holds a constant and src_reg is |
2500 | * the variable reg. | |
48461135 JB |
2501 | */ |
2502 | static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, | |
2503 | struct bpf_reg_state *false_reg, u64 val, | |
2504 | u8 opcode) | |
2505 | { | |
f1174f77 EC |
2506 | if (__is_pointer_value(false, false_reg)) |
2507 | return; | |
4cabc5b1 | 2508 | |
48461135 JB |
2509 | switch (opcode) { |
2510 | case BPF_JEQ: | |
2511 | /* If this is false then we know nothing Jon Snow, but if it is | |
2512 | * true then we know for sure. | |
2513 | */ | |
b03c9f9f | 2514 | __mark_reg_known(true_reg, val); |
48461135 JB |
2515 | break; |
2516 | case BPF_JNE: | |
2517 | /* If this is true we know nothing Jon Snow, but if it is false | |
2518 | * we know the value for sure; | |
2519 | */ | |
b03c9f9f | 2520 | __mark_reg_known(false_reg, val); |
48461135 JB |
2521 | break; |
2522 | case BPF_JGT: | |
b03c9f9f EC |
2523 | true_reg->umax_value = min(true_reg->umax_value, val - 1); |
2524 | false_reg->umin_value = max(false_reg->umin_value, val); | |
2525 | break; | |
48461135 | 2526 | case BPF_JSGT: |
b03c9f9f EC |
2527 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1); |
2528 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val); | |
48461135 | 2529 | break; |
b4e432f1 DB |
2530 | case BPF_JLT: |
2531 | true_reg->umin_value = max(true_reg->umin_value, val + 1); | |
2532 | false_reg->umax_value = min(false_reg->umax_value, val); | |
2533 | break; | |
2534 | case BPF_JSLT: | |
2535 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1); | |
2536 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val); | |
2537 | break; | |
48461135 | 2538 | case BPF_JGE: |
b03c9f9f EC |
2539 | true_reg->umax_value = min(true_reg->umax_value, val); |
2540 | false_reg->umin_value = max(false_reg->umin_value, val + 1); | |
2541 | break; | |
48461135 | 2542 | case BPF_JSGE: |
b03c9f9f EC |
2543 | true_reg->smax_value = min_t(s64, true_reg->smax_value, val); |
2544 | false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1); | |
48461135 | 2545 | break; |
b4e432f1 DB |
2546 | case BPF_JLE: |
2547 | true_reg->umin_value = max(true_reg->umin_value, val); | |
2548 | false_reg->umax_value = min(false_reg->umax_value, val - 1); | |
2549 | break; | |
2550 | case BPF_JSLE: | |
2551 | true_reg->smin_value = max_t(s64, true_reg->smin_value, val); | |
2552 | false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1); | |
2553 | break; | |
48461135 JB |
2554 | default: |
2555 | break; | |
2556 | } | |
2557 | ||
b03c9f9f EC |
2558 | __reg_deduce_bounds(false_reg); |
2559 | __reg_deduce_bounds(true_reg); | |
2560 | /* We might have learned some bits from the bounds. */ | |
2561 | __reg_bound_offset(false_reg); | |
2562 | __reg_bound_offset(true_reg); | |
2563 | /* Intersecting with the old var_off might have improved our bounds | |
2564 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2565 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2566 | */ | |
2567 | __update_reg_bounds(false_reg); | |
2568 | __update_reg_bounds(true_reg); | |
f1174f77 EC |
2569 | } |
2570 | ||
2571 | /* Regs are known to be equal, so intersect their min/max/var_off */ | |
2572 | static void __reg_combine_min_max(struct bpf_reg_state *src_reg, | |
2573 | struct bpf_reg_state *dst_reg) | |
2574 | { | |
b03c9f9f EC |
2575 | src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, |
2576 | dst_reg->umin_value); | |
2577 | src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, | |
2578 | dst_reg->umax_value); | |
2579 | src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, | |
2580 | dst_reg->smin_value); | |
2581 | src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, | |
2582 | dst_reg->smax_value); | |
f1174f77 EC |
2583 | src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, |
2584 | dst_reg->var_off); | |
b03c9f9f EC |
2585 | /* We might have learned new bounds from the var_off. */ |
2586 | __update_reg_bounds(src_reg); | |
2587 | __update_reg_bounds(dst_reg); | |
2588 | /* We might have learned something about the sign bit. */ | |
2589 | __reg_deduce_bounds(src_reg); | |
2590 | __reg_deduce_bounds(dst_reg); | |
2591 | /* We might have learned some bits from the bounds. */ | |
2592 | __reg_bound_offset(src_reg); | |
2593 | __reg_bound_offset(dst_reg); | |
2594 | /* Intersecting with the old var_off might have improved our bounds | |
2595 | * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc), | |
2596 | * then new var_off is (0; 0x7f...fc) which improves our umax. | |
2597 | */ | |
2598 | __update_reg_bounds(src_reg); | |
2599 | __update_reg_bounds(dst_reg); | |
f1174f77 EC |
2600 | } |
2601 | ||
2602 | static void reg_combine_min_max(struct bpf_reg_state *true_src, | |
2603 | struct bpf_reg_state *true_dst, | |
2604 | struct bpf_reg_state *false_src, | |
2605 | struct bpf_reg_state *false_dst, | |
2606 | u8 opcode) | |
2607 | { | |
2608 | switch (opcode) { | |
2609 | case BPF_JEQ: | |
2610 | __reg_combine_min_max(true_src, true_dst); | |
2611 | break; | |
2612 | case BPF_JNE: | |
2613 | __reg_combine_min_max(false_src, false_dst); | |
b03c9f9f | 2614 | break; |
4cabc5b1 | 2615 | } |
48461135 JB |
2616 | } |
2617 | ||
57a09bf0 | 2618 | static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, |
f1174f77 | 2619 | bool is_null) |
57a09bf0 TG |
2620 | { |
2621 | struct bpf_reg_state *reg = ®s[regno]; | |
2622 | ||
2623 | if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { | |
f1174f77 EC |
2624 | /* Old offset (both fixed and variable parts) should |
2625 | * have been known-zero, because we don't allow pointer | |
2626 | * arithmetic on pointers that might be NULL. | |
2627 | */ | |
b03c9f9f EC |
2628 | if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || |
2629 | !tnum_equals_const(reg->var_off, 0) || | |
f1174f77 | 2630 | reg->off)) { |
b03c9f9f EC |
2631 | __mark_reg_known_zero(reg); |
2632 | reg->off = 0; | |
f1174f77 EC |
2633 | } |
2634 | if (is_null) { | |
2635 | reg->type = SCALAR_VALUE; | |
56f668df MKL |
2636 | } else if (reg->map_ptr->inner_map_meta) { |
2637 | reg->type = CONST_PTR_TO_MAP; | |
2638 | reg->map_ptr = reg->map_ptr->inner_map_meta; | |
2639 | } else { | |
f1174f77 | 2640 | reg->type = PTR_TO_MAP_VALUE; |
56f668df | 2641 | } |
a08dd0da DB |
2642 | /* We don't need id from this point onwards anymore, thus we |
2643 | * should better reset it, so that state pruning has chances | |
2644 | * to take effect. | |
2645 | */ | |
2646 | reg->id = 0; | |
57a09bf0 TG |
2647 | } |
2648 | } | |
2649 | ||
2650 | /* The logic is similar to find_good_pkt_pointers(), both could eventually | |
2651 | * be folded together at some point. | |
2652 | */ | |
2653 | static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, | |
f1174f77 | 2654 | bool is_null) |
57a09bf0 TG |
2655 | { |
2656 | struct bpf_reg_state *regs = state->regs; | |
a08dd0da | 2657 | u32 id = regs[regno].id; |
57a09bf0 TG |
2658 | int i; |
2659 | ||
2660 | for (i = 0; i < MAX_BPF_REG; i++) | |
f1174f77 | 2661 | mark_map_reg(regs, i, id, is_null); |
57a09bf0 TG |
2662 | |
2663 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
2664 | if (state->stack_slot_type[i] != STACK_SPILL) | |
2665 | continue; | |
f1174f77 | 2666 | mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, is_null); |
57a09bf0 TG |
2667 | } |
2668 | } | |
2669 | ||
58e2af8b | 2670 | static int check_cond_jmp_op(struct bpf_verifier_env *env, |
17a52670 AS |
2671 | struct bpf_insn *insn, int *insn_idx) |
2672 | { | |
58e2af8b JK |
2673 | struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; |
2674 | struct bpf_reg_state *regs = this_branch->regs, *dst_reg; | |
17a52670 AS |
2675 | u8 opcode = BPF_OP(insn->code); |
2676 | int err; | |
2677 | ||
b4e432f1 | 2678 | if (opcode > BPF_JSLE) { |
61bd5218 | 2679 | verbose(env, "invalid BPF_JMP opcode %x\n", opcode); |
17a52670 AS |
2680 | return -EINVAL; |
2681 | } | |
2682 | ||
2683 | if (BPF_SRC(insn->code) == BPF_X) { | |
2684 | if (insn->imm != 0) { | |
61bd5218 | 2685 | verbose(env, "BPF_JMP uses reserved fields\n"); |
17a52670 AS |
2686 | return -EINVAL; |
2687 | } | |
2688 | ||
2689 | /* check src1 operand */ | |
dc503a8a | 2690 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
2691 | if (err) |
2692 | return err; | |
1be7f75d AS |
2693 | |
2694 | if (is_pointer_value(env, insn->src_reg)) { | |
61bd5218 | 2695 | verbose(env, "R%d pointer comparison prohibited\n", |
1be7f75d AS |
2696 | insn->src_reg); |
2697 | return -EACCES; | |
2698 | } | |
17a52670 AS |
2699 | } else { |
2700 | if (insn->src_reg != BPF_REG_0) { | |
61bd5218 | 2701 | verbose(env, "BPF_JMP uses reserved fields\n"); |
17a52670 AS |
2702 | return -EINVAL; |
2703 | } | |
2704 | } | |
2705 | ||
2706 | /* check src2 operand */ | |
dc503a8a | 2707 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
2708 | if (err) |
2709 | return err; | |
2710 | ||
1a0dc1ac AS |
2711 | dst_reg = ®s[insn->dst_reg]; |
2712 | ||
17a52670 AS |
2713 | /* detect if R == 0 where R was initialized to zero earlier */ |
2714 | if (BPF_SRC(insn->code) == BPF_K && | |
2715 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
f1174f77 EC |
2716 | dst_reg->type == SCALAR_VALUE && |
2717 | tnum_equals_const(dst_reg->var_off, insn->imm)) { | |
17a52670 AS |
2718 | if (opcode == BPF_JEQ) { |
2719 | /* if (imm == imm) goto pc+off; | |
2720 | * only follow the goto, ignore fall-through | |
2721 | */ | |
2722 | *insn_idx += insn->off; | |
2723 | return 0; | |
2724 | } else { | |
2725 | /* if (imm != imm) goto pc+off; | |
2726 | * only follow fall-through branch, since | |
2727 | * that's where the program will go | |
2728 | */ | |
2729 | return 0; | |
2730 | } | |
2731 | } | |
2732 | ||
2733 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
2734 | if (!other_branch) | |
2735 | return -EFAULT; | |
2736 | ||
48461135 JB |
2737 | /* detect if we are comparing against a constant value so we can adjust |
2738 | * our min/max values for our dst register. | |
f1174f77 EC |
2739 | * this is only legit if both are scalars (or pointers to the same |
2740 | * object, I suppose, but we don't support that right now), because | |
2741 | * otherwise the different base pointers mean the offsets aren't | |
2742 | * comparable. | |
48461135 JB |
2743 | */ |
2744 | if (BPF_SRC(insn->code) == BPF_X) { | |
f1174f77 EC |
2745 | if (dst_reg->type == SCALAR_VALUE && |
2746 | regs[insn->src_reg].type == SCALAR_VALUE) { | |
2747 | if (tnum_is_const(regs[insn->src_reg].var_off)) | |
2748 | reg_set_min_max(&other_branch->regs[insn->dst_reg], | |
2749 | dst_reg, regs[insn->src_reg].var_off.value, | |
2750 | opcode); | |
2751 | else if (tnum_is_const(dst_reg->var_off)) | |
2752 | reg_set_min_max_inv(&other_branch->regs[insn->src_reg], | |
2753 | ®s[insn->src_reg], | |
2754 | dst_reg->var_off.value, opcode); | |
2755 | else if (opcode == BPF_JEQ || opcode == BPF_JNE) | |
2756 | /* Comparing for equality, we can combine knowledge */ | |
2757 | reg_combine_min_max(&other_branch->regs[insn->src_reg], | |
2758 | &other_branch->regs[insn->dst_reg], | |
2759 | ®s[insn->src_reg], | |
2760 | ®s[insn->dst_reg], opcode); | |
2761 | } | |
2762 | } else if (dst_reg->type == SCALAR_VALUE) { | |
48461135 JB |
2763 | reg_set_min_max(&other_branch->regs[insn->dst_reg], |
2764 | dst_reg, insn->imm, opcode); | |
2765 | } | |
2766 | ||
58e2af8b | 2767 | /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ |
17a52670 | 2768 | if (BPF_SRC(insn->code) == BPF_K && |
1a0dc1ac AS |
2769 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
2770 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
57a09bf0 TG |
2771 | /* Mark all identical map registers in each branch as either |
2772 | * safe or unknown depending R == 0 or R != 0 conditional. | |
2773 | */ | |
f1174f77 EC |
2774 | mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE); |
2775 | mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ); | |
969bf05e AS |
2776 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
2777 | dst_reg->type == PTR_TO_PACKET && | |
2778 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
de8f3a83 | 2779 | find_good_pkt_pointers(this_branch, dst_reg, PTR_TO_PACKET); |
b4e432f1 DB |
2780 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT && |
2781 | dst_reg->type == PTR_TO_PACKET && | |
2782 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
de8f3a83 | 2783 | find_good_pkt_pointers(other_branch, dst_reg, PTR_TO_PACKET); |
2d2be8ca DB |
2784 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && |
2785 | dst_reg->type == PTR_TO_PACKET_END && | |
2786 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
de8f3a83 DB |
2787 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg], |
2788 | PTR_TO_PACKET); | |
b4e432f1 DB |
2789 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE && |
2790 | dst_reg->type == PTR_TO_PACKET_END && | |
2791 | regs[insn->src_reg].type == PTR_TO_PACKET) { | |
de8f3a83 DB |
2792 | find_good_pkt_pointers(this_branch, ®s[insn->src_reg], |
2793 | PTR_TO_PACKET); | |
2794 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && | |
2795 | dst_reg->type == PTR_TO_PACKET_META && | |
2796 | reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) { | |
2797 | find_good_pkt_pointers(this_branch, dst_reg, PTR_TO_PACKET_META); | |
2798 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT && | |
2799 | dst_reg->type == PTR_TO_PACKET_META && | |
2800 | reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) { | |
2801 | find_good_pkt_pointers(other_branch, dst_reg, PTR_TO_PACKET_META); | |
2802 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && | |
2803 | reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2804 | regs[insn->src_reg].type == PTR_TO_PACKET_META) { | |
2805 | find_good_pkt_pointers(other_branch, ®s[insn->src_reg], | |
2806 | PTR_TO_PACKET_META); | |
2807 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE && | |
2808 | reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && | |
2809 | regs[insn->src_reg].type == PTR_TO_PACKET_META) { | |
2810 | find_good_pkt_pointers(this_branch, ®s[insn->src_reg], | |
2811 | PTR_TO_PACKET_META); | |
1be7f75d | 2812 | } else if (is_pointer_value(env, insn->dst_reg)) { |
61bd5218 JK |
2813 | verbose(env, "R%d pointer comparison prohibited\n", |
2814 | insn->dst_reg); | |
1be7f75d | 2815 | return -EACCES; |
17a52670 | 2816 | } |
61bd5218 JK |
2817 | if (env->log.level) |
2818 | print_verifier_state(env, this_branch); | |
17a52670 AS |
2819 | return 0; |
2820 | } | |
2821 | ||
0246e64d AS |
2822 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
2823 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
2824 | { | |
2825 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
2826 | ||
2827 | return (struct bpf_map *) (unsigned long) imm64; | |
2828 | } | |
2829 | ||
17a52670 | 2830 | /* verify BPF_LD_IMM64 instruction */ |
58e2af8b | 2831 | static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) |
17a52670 | 2832 | { |
58e2af8b | 2833 | struct bpf_reg_state *regs = env->cur_state.regs; |
17a52670 AS |
2834 | int err; |
2835 | ||
2836 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
61bd5218 | 2837 | verbose(env, "invalid BPF_LD_IMM insn\n"); |
17a52670 AS |
2838 | return -EINVAL; |
2839 | } | |
2840 | if (insn->off != 0) { | |
61bd5218 | 2841 | verbose(env, "BPF_LD_IMM64 uses reserved fields\n"); |
17a52670 AS |
2842 | return -EINVAL; |
2843 | } | |
2844 | ||
dc503a8a | 2845 | err = check_reg_arg(env, insn->dst_reg, DST_OP); |
17a52670 AS |
2846 | if (err) |
2847 | return err; | |
2848 | ||
6b173873 | 2849 | if (insn->src_reg == 0) { |
6b173873 JK |
2850 | u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; |
2851 | ||
f1174f77 | 2852 | regs[insn->dst_reg].type = SCALAR_VALUE; |
b03c9f9f | 2853 | __mark_reg_known(®s[insn->dst_reg], imm); |
17a52670 | 2854 | return 0; |
6b173873 | 2855 | } |
17a52670 AS |
2856 | |
2857 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
2858 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
2859 | ||
2860 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
2861 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
2862 | return 0; | |
2863 | } | |
2864 | ||
96be4325 DB |
2865 | static bool may_access_skb(enum bpf_prog_type type) |
2866 | { | |
2867 | switch (type) { | |
2868 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
2869 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 2870 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
2871 | return true; |
2872 | default: | |
2873 | return false; | |
2874 | } | |
2875 | } | |
2876 | ||
ddd872bc AS |
2877 | /* verify safety of LD_ABS|LD_IND instructions: |
2878 | * - they can only appear in the programs where ctx == skb | |
2879 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
2880 | * preserve R6-R9, and store return value into R0 | |
2881 | * | |
2882 | * Implicit input: | |
2883 | * ctx == skb == R6 == CTX | |
2884 | * | |
2885 | * Explicit input: | |
2886 | * SRC == any register | |
2887 | * IMM == 32-bit immediate | |
2888 | * | |
2889 | * Output: | |
2890 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
2891 | */ | |
58e2af8b | 2892 | static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) |
ddd872bc | 2893 | { |
58e2af8b | 2894 | struct bpf_reg_state *regs = env->cur_state.regs; |
ddd872bc | 2895 | u8 mode = BPF_MODE(insn->code); |
ddd872bc AS |
2896 | int i, err; |
2897 | ||
24701ece | 2898 | if (!may_access_skb(env->prog->type)) { |
61bd5218 | 2899 | verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
2900 | return -EINVAL; |
2901 | } | |
2902 | ||
2903 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 2904 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 2905 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
61bd5218 | 2906 | verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
2907 | return -EINVAL; |
2908 | } | |
2909 | ||
2910 | /* check whether implicit source operand (register R6) is readable */ | |
dc503a8a | 2911 | err = check_reg_arg(env, BPF_REG_6, SRC_OP); |
ddd872bc AS |
2912 | if (err) |
2913 | return err; | |
2914 | ||
2915 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
61bd5218 JK |
2916 | verbose(env, |
2917 | "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
ddd872bc AS |
2918 | return -EINVAL; |
2919 | } | |
2920 | ||
2921 | if (mode == BPF_IND) { | |
2922 | /* check explicit source operand */ | |
dc503a8a | 2923 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
ddd872bc AS |
2924 | if (err) |
2925 | return err; | |
2926 | } | |
2927 | ||
2928 | /* reset caller saved regs to unreadable */ | |
dc503a8a | 2929 | for (i = 0; i < CALLER_SAVED_REGS; i++) { |
61bd5218 | 2930 | mark_reg_not_init(env, regs, caller_saved[i]); |
dc503a8a EC |
2931 | check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); |
2932 | } | |
ddd872bc AS |
2933 | |
2934 | /* mark destination R0 register as readable, since it contains | |
dc503a8a EC |
2935 | * the value fetched from the packet. |
2936 | * Already marked as written above. | |
ddd872bc | 2937 | */ |
61bd5218 | 2938 | mark_reg_unknown(env, regs, BPF_REG_0); |
ddd872bc AS |
2939 | return 0; |
2940 | } | |
2941 | ||
390ee7e2 AS |
2942 | static int check_return_code(struct bpf_verifier_env *env) |
2943 | { | |
2944 | struct bpf_reg_state *reg; | |
2945 | struct tnum range = tnum_range(0, 1); | |
2946 | ||
2947 | switch (env->prog->type) { | |
2948 | case BPF_PROG_TYPE_CGROUP_SKB: | |
2949 | case BPF_PROG_TYPE_CGROUP_SOCK: | |
2950 | case BPF_PROG_TYPE_SOCK_OPS: | |
2951 | break; | |
2952 | default: | |
2953 | return 0; | |
2954 | } | |
2955 | ||
2956 | reg = &env->cur_state.regs[BPF_REG_0]; | |
2957 | if (reg->type != SCALAR_VALUE) { | |
61bd5218 | 2958 | verbose(env, "At program exit the register R0 is not a known value (%s)\n", |
390ee7e2 AS |
2959 | reg_type_str[reg->type]); |
2960 | return -EINVAL; | |
2961 | } | |
2962 | ||
2963 | if (!tnum_in(range, reg->var_off)) { | |
61bd5218 | 2964 | verbose(env, "At program exit the register R0 "); |
390ee7e2 AS |
2965 | if (!tnum_is_unknown(reg->var_off)) { |
2966 | char tn_buf[48]; | |
2967 | ||
2968 | tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off); | |
61bd5218 | 2969 | verbose(env, "has value %s", tn_buf); |
390ee7e2 | 2970 | } else { |
61bd5218 | 2971 | verbose(env, "has unknown scalar value"); |
390ee7e2 | 2972 | } |
61bd5218 | 2973 | verbose(env, " should have been 0 or 1\n"); |
390ee7e2 AS |
2974 | return -EINVAL; |
2975 | } | |
2976 | return 0; | |
2977 | } | |
2978 | ||
475fb78f AS |
2979 | /* non-recursive DFS pseudo code |
2980 | * 1 procedure DFS-iterative(G,v): | |
2981 | * 2 label v as discovered | |
2982 | * 3 let S be a stack | |
2983 | * 4 S.push(v) | |
2984 | * 5 while S is not empty | |
2985 | * 6 t <- S.pop() | |
2986 | * 7 if t is what we're looking for: | |
2987 | * 8 return t | |
2988 | * 9 for all edges e in G.adjacentEdges(t) do | |
2989 | * 10 if edge e is already labelled | |
2990 | * 11 continue with the next edge | |
2991 | * 12 w <- G.adjacentVertex(t,e) | |
2992 | * 13 if vertex w is not discovered and not explored | |
2993 | * 14 label e as tree-edge | |
2994 | * 15 label w as discovered | |
2995 | * 16 S.push(w) | |
2996 | * 17 continue at 5 | |
2997 | * 18 else if vertex w is discovered | |
2998 | * 19 label e as back-edge | |
2999 | * 20 else | |
3000 | * 21 // vertex w is explored | |
3001 | * 22 label e as forward- or cross-edge | |
3002 | * 23 label t as explored | |
3003 | * 24 S.pop() | |
3004 | * | |
3005 | * convention: | |
3006 | * 0x10 - discovered | |
3007 | * 0x11 - discovered and fall-through edge labelled | |
3008 | * 0x12 - discovered and fall-through and branch edges labelled | |
3009 | * 0x20 - explored | |
3010 | */ | |
3011 | ||
3012 | enum { | |
3013 | DISCOVERED = 0x10, | |
3014 | EXPLORED = 0x20, | |
3015 | FALLTHROUGH = 1, | |
3016 | BRANCH = 2, | |
3017 | }; | |
3018 | ||
58e2af8b | 3019 | #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) |
f1bca824 | 3020 | |
475fb78f AS |
3021 | static int *insn_stack; /* stack of insns to process */ |
3022 | static int cur_stack; /* current stack index */ | |
3023 | static int *insn_state; | |
3024 | ||
3025 | /* t, w, e - match pseudo-code above: | |
3026 | * t - index of current instruction | |
3027 | * w - next instruction | |
3028 | * e - edge | |
3029 | */ | |
58e2af8b | 3030 | static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) |
475fb78f AS |
3031 | { |
3032 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
3033 | return 0; | |
3034 | ||
3035 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
3036 | return 0; | |
3037 | ||
3038 | if (w < 0 || w >= env->prog->len) { | |
61bd5218 | 3039 | verbose(env, "jump out of range from insn %d to %d\n", t, w); |
475fb78f AS |
3040 | return -EINVAL; |
3041 | } | |
3042 | ||
f1bca824 AS |
3043 | if (e == BRANCH) |
3044 | /* mark branch target for state pruning */ | |
3045 | env->explored_states[w] = STATE_LIST_MARK; | |
3046 | ||
475fb78f AS |
3047 | if (insn_state[w] == 0) { |
3048 | /* tree-edge */ | |
3049 | insn_state[t] = DISCOVERED | e; | |
3050 | insn_state[w] = DISCOVERED; | |
3051 | if (cur_stack >= env->prog->len) | |
3052 | return -E2BIG; | |
3053 | insn_stack[cur_stack++] = w; | |
3054 | return 1; | |
3055 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
61bd5218 | 3056 | verbose(env, "back-edge from insn %d to %d\n", t, w); |
475fb78f AS |
3057 | return -EINVAL; |
3058 | } else if (insn_state[w] == EXPLORED) { | |
3059 | /* forward- or cross-edge */ | |
3060 | insn_state[t] = DISCOVERED | e; | |
3061 | } else { | |
61bd5218 | 3062 | verbose(env, "insn state internal bug\n"); |
475fb78f AS |
3063 | return -EFAULT; |
3064 | } | |
3065 | return 0; | |
3066 | } | |
3067 | ||
3068 | /* non-recursive depth-first-search to detect loops in BPF program | |
3069 | * loop == back-edge in directed graph | |
3070 | */ | |
58e2af8b | 3071 | static int check_cfg(struct bpf_verifier_env *env) |
475fb78f AS |
3072 | { |
3073 | struct bpf_insn *insns = env->prog->insnsi; | |
3074 | int insn_cnt = env->prog->len; | |
3075 | int ret = 0; | |
3076 | int i, t; | |
3077 | ||
3078 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3079 | if (!insn_state) | |
3080 | return -ENOMEM; | |
3081 | ||
3082 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
3083 | if (!insn_stack) { | |
3084 | kfree(insn_state); | |
3085 | return -ENOMEM; | |
3086 | } | |
3087 | ||
3088 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
3089 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
3090 | cur_stack = 1; | |
3091 | ||
3092 | peek_stack: | |
3093 | if (cur_stack == 0) | |
3094 | goto check_state; | |
3095 | t = insn_stack[cur_stack - 1]; | |
3096 | ||
3097 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
3098 | u8 opcode = BPF_OP(insns[t].code); | |
3099 | ||
3100 | if (opcode == BPF_EXIT) { | |
3101 | goto mark_explored; | |
3102 | } else if (opcode == BPF_CALL) { | |
3103 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3104 | if (ret == 1) | |
3105 | goto peek_stack; | |
3106 | else if (ret < 0) | |
3107 | goto err_free; | |
07016151 DB |
3108 | if (t + 1 < insn_cnt) |
3109 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3110 | } else if (opcode == BPF_JA) { |
3111 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
3112 | ret = -EINVAL; | |
3113 | goto err_free; | |
3114 | } | |
3115 | /* unconditional jump with single edge */ | |
3116 | ret = push_insn(t, t + insns[t].off + 1, | |
3117 | FALLTHROUGH, env); | |
3118 | if (ret == 1) | |
3119 | goto peek_stack; | |
3120 | else if (ret < 0) | |
3121 | goto err_free; | |
f1bca824 AS |
3122 | /* tell verifier to check for equivalent states |
3123 | * after every call and jump | |
3124 | */ | |
c3de6317 AS |
3125 | if (t + 1 < insn_cnt) |
3126 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
3127 | } else { |
3128 | /* conditional jump with two edges */ | |
3c2ce60b | 3129 | env->explored_states[t] = STATE_LIST_MARK; |
475fb78f AS |
3130 | ret = push_insn(t, t + 1, FALLTHROUGH, env); |
3131 | if (ret == 1) | |
3132 | goto peek_stack; | |
3133 | else if (ret < 0) | |
3134 | goto err_free; | |
3135 | ||
3136 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
3137 | if (ret == 1) | |
3138 | goto peek_stack; | |
3139 | else if (ret < 0) | |
3140 | goto err_free; | |
3141 | } | |
3142 | } else { | |
3143 | /* all other non-branch instructions with single | |
3144 | * fall-through edge | |
3145 | */ | |
3146 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
3147 | if (ret == 1) | |
3148 | goto peek_stack; | |
3149 | else if (ret < 0) | |
3150 | goto err_free; | |
3151 | } | |
3152 | ||
3153 | mark_explored: | |
3154 | insn_state[t] = EXPLORED; | |
3155 | if (cur_stack-- <= 0) { | |
61bd5218 | 3156 | verbose(env, "pop stack internal bug\n"); |
475fb78f AS |
3157 | ret = -EFAULT; |
3158 | goto err_free; | |
3159 | } | |
3160 | goto peek_stack; | |
3161 | ||
3162 | check_state: | |
3163 | for (i = 0; i < insn_cnt; i++) { | |
3164 | if (insn_state[i] != EXPLORED) { | |
61bd5218 | 3165 | verbose(env, "unreachable insn %d\n", i); |
475fb78f AS |
3166 | ret = -EINVAL; |
3167 | goto err_free; | |
3168 | } | |
3169 | } | |
3170 | ret = 0; /* cfg looks good */ | |
3171 | ||
3172 | err_free: | |
3173 | kfree(insn_state); | |
3174 | kfree(insn_stack); | |
3175 | return ret; | |
3176 | } | |
3177 | ||
f1174f77 EC |
3178 | /* check %cur's range satisfies %old's */ |
3179 | static bool range_within(struct bpf_reg_state *old, | |
3180 | struct bpf_reg_state *cur) | |
3181 | { | |
b03c9f9f EC |
3182 | return old->umin_value <= cur->umin_value && |
3183 | old->umax_value >= cur->umax_value && | |
3184 | old->smin_value <= cur->smin_value && | |
3185 | old->smax_value >= cur->smax_value; | |
f1174f77 EC |
3186 | } |
3187 | ||
3188 | /* Maximum number of register states that can exist at once */ | |
3189 | #define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE) | |
3190 | struct idpair { | |
3191 | u32 old; | |
3192 | u32 cur; | |
3193 | }; | |
3194 | ||
3195 | /* If in the old state two registers had the same id, then they need to have | |
3196 | * the same id in the new state as well. But that id could be different from | |
3197 | * the old state, so we need to track the mapping from old to new ids. | |
3198 | * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent | |
3199 | * regs with old id 5 must also have new id 9 for the new state to be safe. But | |
3200 | * regs with a different old id could still have new id 9, we don't care about | |
3201 | * that. | |
3202 | * So we look through our idmap to see if this old id has been seen before. If | |
3203 | * so, we require the new id to match; otherwise, we add the id pair to the map. | |
969bf05e | 3204 | */ |
f1174f77 | 3205 | static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap) |
969bf05e | 3206 | { |
f1174f77 | 3207 | unsigned int i; |
969bf05e | 3208 | |
f1174f77 EC |
3209 | for (i = 0; i < ID_MAP_SIZE; i++) { |
3210 | if (!idmap[i].old) { | |
3211 | /* Reached an empty slot; haven't seen this id before */ | |
3212 | idmap[i].old = old_id; | |
3213 | idmap[i].cur = cur_id; | |
3214 | return true; | |
3215 | } | |
3216 | if (idmap[i].old == old_id) | |
3217 | return idmap[i].cur == cur_id; | |
3218 | } | |
3219 | /* We ran out of idmap slots, which should be impossible */ | |
3220 | WARN_ON_ONCE(1); | |
3221 | return false; | |
3222 | } | |
3223 | ||
3224 | /* Returns true if (rold safe implies rcur safe) */ | |
1b688a19 EC |
3225 | static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, |
3226 | struct idpair *idmap) | |
f1174f77 | 3227 | { |
dc503a8a EC |
3228 | if (!(rold->live & REG_LIVE_READ)) |
3229 | /* explored state didn't use this */ | |
3230 | return true; | |
3231 | ||
3232 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, live)) == 0) | |
969bf05e AS |
3233 | return true; |
3234 | ||
f1174f77 EC |
3235 | if (rold->type == NOT_INIT) |
3236 | /* explored state can't have used this */ | |
969bf05e | 3237 | return true; |
f1174f77 EC |
3238 | if (rcur->type == NOT_INIT) |
3239 | return false; | |
3240 | switch (rold->type) { | |
3241 | case SCALAR_VALUE: | |
3242 | if (rcur->type == SCALAR_VALUE) { | |
3243 | /* new val must satisfy old val knowledge */ | |
3244 | return range_within(rold, rcur) && | |
3245 | tnum_in(rold->var_off, rcur->var_off); | |
3246 | } else { | |
3247 | /* if we knew anything about the old value, we're not | |
3248 | * equal, because we can't know anything about the | |
3249 | * scalar value of the pointer in the new value. | |
3250 | */ | |
b03c9f9f EC |
3251 | return rold->umin_value == 0 && |
3252 | rold->umax_value == U64_MAX && | |
3253 | rold->smin_value == S64_MIN && | |
3254 | rold->smax_value == S64_MAX && | |
f1174f77 EC |
3255 | tnum_is_unknown(rold->var_off); |
3256 | } | |
3257 | case PTR_TO_MAP_VALUE: | |
1b688a19 EC |
3258 | /* If the new min/max/var_off satisfy the old ones and |
3259 | * everything else matches, we are OK. | |
3260 | * We don't care about the 'id' value, because nothing | |
3261 | * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL) | |
3262 | */ | |
3263 | return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && | |
3264 | range_within(rold, rcur) && | |
3265 | tnum_in(rold->var_off, rcur->var_off); | |
f1174f77 EC |
3266 | case PTR_TO_MAP_VALUE_OR_NULL: |
3267 | /* a PTR_TO_MAP_VALUE could be safe to use as a | |
3268 | * PTR_TO_MAP_VALUE_OR_NULL into the same map. | |
3269 | * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- | |
3270 | * checked, doing so could have affected others with the same | |
3271 | * id, and we can't check for that because we lost the id when | |
3272 | * we converted to a PTR_TO_MAP_VALUE. | |
3273 | */ | |
3274 | if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL) | |
3275 | return false; | |
3276 | if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) | |
3277 | return false; | |
3278 | /* Check our ids match any regs they're supposed to */ | |
3279 | return check_ids(rold->id, rcur->id, idmap); | |
de8f3a83 | 3280 | case PTR_TO_PACKET_META: |
f1174f77 | 3281 | case PTR_TO_PACKET: |
de8f3a83 | 3282 | if (rcur->type != rold->type) |
f1174f77 EC |
3283 | return false; |
3284 | /* We must have at least as much range as the old ptr | |
3285 | * did, so that any accesses which were safe before are | |
3286 | * still safe. This is true even if old range < old off, | |
3287 | * since someone could have accessed through (ptr - k), or | |
3288 | * even done ptr -= k in a register, to get a safe access. | |
3289 | */ | |
3290 | if (rold->range > rcur->range) | |
3291 | return false; | |
3292 | /* If the offsets don't match, we can't trust our alignment; | |
3293 | * nor can we be sure that we won't fall out of range. | |
3294 | */ | |
3295 | if (rold->off != rcur->off) | |
3296 | return false; | |
3297 | /* id relations must be preserved */ | |
3298 | if (rold->id && !check_ids(rold->id, rcur->id, idmap)) | |
3299 | return false; | |
3300 | /* new val must satisfy old val knowledge */ | |
3301 | return range_within(rold, rcur) && | |
3302 | tnum_in(rold->var_off, rcur->var_off); | |
3303 | case PTR_TO_CTX: | |
3304 | case CONST_PTR_TO_MAP: | |
3305 | case PTR_TO_STACK: | |
3306 | case PTR_TO_PACKET_END: | |
3307 | /* Only valid matches are exact, which memcmp() above | |
3308 | * would have accepted | |
3309 | */ | |
3310 | default: | |
3311 | /* Don't know what's going on, just say it's not safe */ | |
3312 | return false; | |
3313 | } | |
969bf05e | 3314 | |
f1174f77 EC |
3315 | /* Shouldn't get here; if we do, say it's not safe */ |
3316 | WARN_ON_ONCE(1); | |
969bf05e AS |
3317 | return false; |
3318 | } | |
3319 | ||
f1bca824 AS |
3320 | /* compare two verifier states |
3321 | * | |
3322 | * all states stored in state_list are known to be valid, since | |
3323 | * verifier reached 'bpf_exit' instruction through them | |
3324 | * | |
3325 | * this function is called when verifier exploring different branches of | |
3326 | * execution popped from the state stack. If it sees an old state that has | |
3327 | * more strict register state and more strict stack state then this execution | |
3328 | * branch doesn't need to be explored further, since verifier already | |
3329 | * concluded that more strict state leads to valid finish. | |
3330 | * | |
3331 | * Therefore two states are equivalent if register state is more conservative | |
3332 | * and explored stack state is more conservative than the current one. | |
3333 | * Example: | |
3334 | * explored current | |
3335 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
3336 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
3337 | * | |
3338 | * In other words if current stack state (one being explored) has more | |
3339 | * valid slots than old one that already passed validation, it means | |
3340 | * the verifier can stop exploring and conclude that current state is valid too | |
3341 | * | |
3342 | * Similarly with registers. If explored state has register type as invalid | |
3343 | * whereas register type in current state is meaningful, it means that | |
3344 | * the current state will reach 'bpf_exit' instruction safely | |
3345 | */ | |
48461135 JB |
3346 | static bool states_equal(struct bpf_verifier_env *env, |
3347 | struct bpf_verifier_state *old, | |
58e2af8b | 3348 | struct bpf_verifier_state *cur) |
f1bca824 | 3349 | { |
f1174f77 EC |
3350 | struct idpair *idmap; |
3351 | bool ret = false; | |
f1bca824 AS |
3352 | int i; |
3353 | ||
f1174f77 EC |
3354 | idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL); |
3355 | /* If we failed to allocate the idmap, just say it's not safe */ | |
3356 | if (!idmap) | |
1a0dc1ac | 3357 | return false; |
f1174f77 EC |
3358 | |
3359 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1b688a19 | 3360 | if (!regsafe(&old->regs[i], &cur->regs[i], idmap)) |
f1174f77 | 3361 | goto out_free; |
f1bca824 AS |
3362 | } |
3363 | ||
3364 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
3365 | if (old->stack_slot_type[i] == STACK_INVALID) |
3366 | continue; | |
3367 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
3368 | /* Ex: old explored (safe) state has STACK_SPILL in | |
3369 | * this stack slot, but current has has STACK_MISC -> | |
3370 | * this verifier states are not equivalent, | |
3371 | * return false to continue verification of this path | |
3372 | */ | |
f1174f77 | 3373 | goto out_free; |
9c399760 AS |
3374 | if (i % BPF_REG_SIZE) |
3375 | continue; | |
d25da6ca DB |
3376 | if (old->stack_slot_type[i] != STACK_SPILL) |
3377 | continue; | |
f1174f77 EC |
3378 | if (!regsafe(&old->spilled_regs[i / BPF_REG_SIZE], |
3379 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
1b688a19 | 3380 | idmap)) |
f1174f77 EC |
3381 | /* when explored and current stack slot are both storing |
3382 | * spilled registers, check that stored pointers types | |
9c399760 AS |
3383 | * are the same as well. |
3384 | * Ex: explored safe path could have stored | |
f1174f77 | 3385 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8} |
9c399760 | 3386 | * but current path has stored: |
f1174f77 | 3387 | * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16} |
9c399760 AS |
3388 | * such verifier states are not equivalent. |
3389 | * return false to continue verification of this path | |
3390 | */ | |
f1174f77 | 3391 | goto out_free; |
9c399760 AS |
3392 | else |
3393 | continue; | |
f1bca824 | 3394 | } |
f1174f77 EC |
3395 | ret = true; |
3396 | out_free: | |
3397 | kfree(idmap); | |
3398 | return ret; | |
f1bca824 AS |
3399 | } |
3400 | ||
8e9cd9ce EC |
3401 | /* A write screens off any subsequent reads; but write marks come from the |
3402 | * straight-line code between a state and its parent. When we arrive at a | |
3403 | * jump target (in the first iteration of the propagate_liveness() loop), | |
3404 | * we didn't arrive by the straight-line code, so read marks in state must | |
3405 | * propagate to parent regardless of state's write marks. | |
3406 | */ | |
dc503a8a EC |
3407 | static bool do_propagate_liveness(const struct bpf_verifier_state *state, |
3408 | struct bpf_verifier_state *parent) | |
3409 | { | |
63f45f84 | 3410 | bool writes = parent == state->parent; /* Observe write marks */ |
dc503a8a EC |
3411 | bool touched = false; /* any changes made? */ |
3412 | int i; | |
3413 | ||
3414 | if (!parent) | |
3415 | return touched; | |
3416 | /* Propagate read liveness of registers... */ | |
3417 | BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); | |
3418 | /* We don't need to worry about FP liveness because it's read-only */ | |
3419 | for (i = 0; i < BPF_REG_FP; i++) { | |
3420 | if (parent->regs[i].live & REG_LIVE_READ) | |
3421 | continue; | |
63f45f84 EC |
3422 | if (writes && (state->regs[i].live & REG_LIVE_WRITTEN)) |
3423 | continue; | |
3424 | if (state->regs[i].live & REG_LIVE_READ) { | |
dc503a8a EC |
3425 | parent->regs[i].live |= REG_LIVE_READ; |
3426 | touched = true; | |
3427 | } | |
3428 | } | |
3429 | /* ... and stack slots */ | |
3430 | for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++) { | |
3431 | if (parent->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL) | |
3432 | continue; | |
3433 | if (state->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL) | |
3434 | continue; | |
3435 | if (parent->spilled_regs[i].live & REG_LIVE_READ) | |
3436 | continue; | |
63f45f84 EC |
3437 | if (writes && (state->spilled_regs[i].live & REG_LIVE_WRITTEN)) |
3438 | continue; | |
3439 | if (state->spilled_regs[i].live & REG_LIVE_READ) { | |
1ab2de2b | 3440 | parent->spilled_regs[i].live |= REG_LIVE_READ; |
dc503a8a EC |
3441 | touched = true; |
3442 | } | |
3443 | } | |
3444 | return touched; | |
3445 | } | |
3446 | ||
8e9cd9ce EC |
3447 | /* "parent" is "a state from which we reach the current state", but initially |
3448 | * it is not the state->parent (i.e. "the state whose straight-line code leads | |
3449 | * to the current state"), instead it is the state that happened to arrive at | |
3450 | * a (prunable) equivalent of the current state. See comment above | |
3451 | * do_propagate_liveness() for consequences of this. | |
3452 | * This function is just a more efficient way of calling mark_reg_read() or | |
3453 | * mark_stack_slot_read() on each reg in "parent" that is read in "state", | |
3454 | * though it requires that parent != state->parent in the call arguments. | |
3455 | */ | |
dc503a8a EC |
3456 | static void propagate_liveness(const struct bpf_verifier_state *state, |
3457 | struct bpf_verifier_state *parent) | |
3458 | { | |
3459 | while (do_propagate_liveness(state, parent)) { | |
3460 | /* Something changed, so we need to feed those changes onward */ | |
3461 | state = parent; | |
3462 | parent = state->parent; | |
3463 | } | |
3464 | } | |
3465 | ||
58e2af8b | 3466 | static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) |
f1bca824 | 3467 | { |
58e2af8b JK |
3468 | struct bpf_verifier_state_list *new_sl; |
3469 | struct bpf_verifier_state_list *sl; | |
dc503a8a | 3470 | int i; |
f1bca824 AS |
3471 | |
3472 | sl = env->explored_states[insn_idx]; | |
3473 | if (!sl) | |
3474 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
3475 | * be doing state search here | |
3476 | */ | |
3477 | return 0; | |
3478 | ||
3479 | while (sl != STATE_LIST_MARK) { | |
dc503a8a | 3480 | if (states_equal(env, &sl->state, &env->cur_state)) { |
f1bca824 | 3481 | /* reached equivalent register/stack state, |
dc503a8a EC |
3482 | * prune the search. |
3483 | * Registers read by the continuation are read by us. | |
8e9cd9ce EC |
3484 | * If we have any write marks in env->cur_state, they |
3485 | * will prevent corresponding reads in the continuation | |
3486 | * from reaching our parent (an explored_state). Our | |
3487 | * own state will get the read marks recorded, but | |
3488 | * they'll be immediately forgotten as we're pruning | |
3489 | * this state and will pop a new one. | |
f1bca824 | 3490 | */ |
dc503a8a | 3491 | propagate_liveness(&sl->state, &env->cur_state); |
f1bca824 | 3492 | return 1; |
dc503a8a | 3493 | } |
f1bca824 AS |
3494 | sl = sl->next; |
3495 | } | |
3496 | ||
3497 | /* there were no equivalent states, remember current one. | |
3498 | * technically the current state is not proven to be safe yet, | |
3499 | * but it will either reach bpf_exit (which means it's safe) or | |
3500 | * it will be rejected. Since there are no loops, we won't be | |
3501 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
3502 | */ | |
58e2af8b | 3503 | new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); |
f1bca824 AS |
3504 | if (!new_sl) |
3505 | return -ENOMEM; | |
3506 | ||
3507 | /* add new state to the head of linked list */ | |
3508 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
3509 | new_sl->next = env->explored_states[insn_idx]; | |
3510 | env->explored_states[insn_idx] = new_sl; | |
dc503a8a EC |
3511 | /* connect new state to parentage chain */ |
3512 | env->cur_state.parent = &new_sl->state; | |
8e9cd9ce EC |
3513 | /* clear write marks in current state: the writes we did are not writes |
3514 | * our child did, so they don't screen off its reads from us. | |
3515 | * (There are no read marks in current state, because reads always mark | |
3516 | * their parent and current state never has children yet. Only | |
3517 | * explored_states can get read marks.) | |
3518 | */ | |
dc503a8a EC |
3519 | for (i = 0; i < BPF_REG_FP; i++) |
3520 | env->cur_state.regs[i].live = REG_LIVE_NONE; | |
3521 | for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++) | |
3522 | if (env->cur_state.stack_slot_type[i * BPF_REG_SIZE] == STACK_SPILL) | |
3523 | env->cur_state.spilled_regs[i].live = REG_LIVE_NONE; | |
f1bca824 AS |
3524 | return 0; |
3525 | } | |
3526 | ||
13a27dfc JK |
3527 | static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, |
3528 | int insn_idx, int prev_insn_idx) | |
3529 | { | |
3530 | if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) | |
3531 | return 0; | |
3532 | ||
3533 | return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); | |
3534 | } | |
3535 | ||
58e2af8b | 3536 | static int do_check(struct bpf_verifier_env *env) |
17a52670 | 3537 | { |
58e2af8b | 3538 | struct bpf_verifier_state *state = &env->cur_state; |
17a52670 | 3539 | struct bpf_insn *insns = env->prog->insnsi; |
58e2af8b | 3540 | struct bpf_reg_state *regs = state->regs; |
17a52670 AS |
3541 | int insn_cnt = env->prog->len; |
3542 | int insn_idx, prev_insn_idx = 0; | |
3543 | int insn_processed = 0; | |
3544 | bool do_print_state = false; | |
3545 | ||
61bd5218 | 3546 | init_reg_state(env, regs); |
dc503a8a | 3547 | state->parent = NULL; |
17a52670 AS |
3548 | insn_idx = 0; |
3549 | for (;;) { | |
3550 | struct bpf_insn *insn; | |
3551 | u8 class; | |
3552 | int err; | |
3553 | ||
3554 | if (insn_idx >= insn_cnt) { | |
61bd5218 | 3555 | verbose(env, "invalid insn idx %d insn_cnt %d\n", |
17a52670 AS |
3556 | insn_idx, insn_cnt); |
3557 | return -EFAULT; | |
3558 | } | |
3559 | ||
3560 | insn = &insns[insn_idx]; | |
3561 | class = BPF_CLASS(insn->code); | |
3562 | ||
07016151 | 3563 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
61bd5218 JK |
3564 | verbose(env, |
3565 | "BPF program is too large. Processed %d insn\n", | |
17a52670 AS |
3566 | insn_processed); |
3567 | return -E2BIG; | |
3568 | } | |
3569 | ||
f1bca824 AS |
3570 | err = is_state_visited(env, insn_idx); |
3571 | if (err < 0) | |
3572 | return err; | |
3573 | if (err == 1) { | |
3574 | /* found equivalent state, can prune the search */ | |
61bd5218 | 3575 | if (env->log.level) { |
f1bca824 | 3576 | if (do_print_state) |
61bd5218 | 3577 | verbose(env, "\nfrom %d to %d: safe\n", |
f1bca824 AS |
3578 | prev_insn_idx, insn_idx); |
3579 | else | |
61bd5218 | 3580 | verbose(env, "%d: safe\n", insn_idx); |
f1bca824 AS |
3581 | } |
3582 | goto process_bpf_exit; | |
3583 | } | |
3584 | ||
3c2ce60b DB |
3585 | if (need_resched()) |
3586 | cond_resched(); | |
3587 | ||
61bd5218 JK |
3588 | if (env->log.level > 1 || (env->log.level && do_print_state)) { |
3589 | if (env->log.level > 1) | |
3590 | verbose(env, "%d:", insn_idx); | |
c5fc9692 | 3591 | else |
61bd5218 | 3592 | verbose(env, "\nfrom %d to %d:", |
c5fc9692 | 3593 | prev_insn_idx, insn_idx); |
61bd5218 | 3594 | print_verifier_state(env, &env->cur_state); |
17a52670 AS |
3595 | do_print_state = false; |
3596 | } | |
3597 | ||
61bd5218 JK |
3598 | if (env->log.level) { |
3599 | verbose(env, "%d: ", insn_idx); | |
f4ac7e0b JK |
3600 | print_bpf_insn(verbose, env, insn, |
3601 | env->allow_ptr_leaks); | |
17a52670 AS |
3602 | } |
3603 | ||
13a27dfc JK |
3604 | err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); |
3605 | if (err) | |
3606 | return err; | |
3607 | ||
17a52670 | 3608 | if (class == BPF_ALU || class == BPF_ALU64) { |
1be7f75d | 3609 | err = check_alu_op(env, insn); |
17a52670 AS |
3610 | if (err) |
3611 | return err; | |
3612 | ||
3613 | } else if (class == BPF_LDX) { | |
3df126f3 | 3614 | enum bpf_reg_type *prev_src_type, src_reg_type; |
9bac3d6d AS |
3615 | |
3616 | /* check for reserved fields is already done */ | |
3617 | ||
17a52670 | 3618 | /* check src operand */ |
dc503a8a | 3619 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3620 | if (err) |
3621 | return err; | |
3622 | ||
dc503a8a | 3623 | err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); |
17a52670 AS |
3624 | if (err) |
3625 | return err; | |
3626 | ||
725f9dcd AS |
3627 | src_reg_type = regs[insn->src_reg].type; |
3628 | ||
17a52670 AS |
3629 | /* check that memory (src_reg + off) is readable, |
3630 | * the state of dst_reg will be updated by this func | |
3631 | */ | |
31fd8581 | 3632 | err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, |
17a52670 AS |
3633 | BPF_SIZE(insn->code), BPF_READ, |
3634 | insn->dst_reg); | |
3635 | if (err) | |
3636 | return err; | |
3637 | ||
3df126f3 JK |
3638 | prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; |
3639 | ||
3640 | if (*prev_src_type == NOT_INIT) { | |
9bac3d6d AS |
3641 | /* saw a valid insn |
3642 | * dst_reg = *(u32 *)(src_reg + off) | |
3df126f3 | 3643 | * save type to validate intersecting paths |
9bac3d6d | 3644 | */ |
3df126f3 | 3645 | *prev_src_type = src_reg_type; |
9bac3d6d | 3646 | |
3df126f3 | 3647 | } else if (src_reg_type != *prev_src_type && |
9bac3d6d | 3648 | (src_reg_type == PTR_TO_CTX || |
3df126f3 | 3649 | *prev_src_type == PTR_TO_CTX)) { |
9bac3d6d AS |
3650 | /* ABuser program is trying to use the same insn |
3651 | * dst_reg = *(u32*) (src_reg + off) | |
3652 | * with different pointer types: | |
3653 | * src_reg == ctx in one branch and | |
3654 | * src_reg == stack|map in some other branch. | |
3655 | * Reject it. | |
3656 | */ | |
61bd5218 | 3657 | verbose(env, "same insn cannot be used with different pointers\n"); |
9bac3d6d AS |
3658 | return -EINVAL; |
3659 | } | |
3660 | ||
17a52670 | 3661 | } else if (class == BPF_STX) { |
3df126f3 | 3662 | enum bpf_reg_type *prev_dst_type, dst_reg_type; |
d691f9e8 | 3663 | |
17a52670 | 3664 | if (BPF_MODE(insn->code) == BPF_XADD) { |
31fd8581 | 3665 | err = check_xadd(env, insn_idx, insn); |
17a52670 AS |
3666 | if (err) |
3667 | return err; | |
3668 | insn_idx++; | |
3669 | continue; | |
3670 | } | |
3671 | ||
17a52670 | 3672 | /* check src1 operand */ |
dc503a8a | 3673 | err = check_reg_arg(env, insn->src_reg, SRC_OP); |
17a52670 AS |
3674 | if (err) |
3675 | return err; | |
3676 | /* check src2 operand */ | |
dc503a8a | 3677 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3678 | if (err) |
3679 | return err; | |
3680 | ||
d691f9e8 AS |
3681 | dst_reg_type = regs[insn->dst_reg].type; |
3682 | ||
17a52670 | 3683 | /* check that memory (dst_reg + off) is writeable */ |
31fd8581 | 3684 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
3685 | BPF_SIZE(insn->code), BPF_WRITE, |
3686 | insn->src_reg); | |
3687 | if (err) | |
3688 | return err; | |
3689 | ||
3df126f3 JK |
3690 | prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; |
3691 | ||
3692 | if (*prev_dst_type == NOT_INIT) { | |
3693 | *prev_dst_type = dst_reg_type; | |
3694 | } else if (dst_reg_type != *prev_dst_type && | |
d691f9e8 | 3695 | (dst_reg_type == PTR_TO_CTX || |
3df126f3 | 3696 | *prev_dst_type == PTR_TO_CTX)) { |
61bd5218 | 3697 | verbose(env, "same insn cannot be used with different pointers\n"); |
d691f9e8 AS |
3698 | return -EINVAL; |
3699 | } | |
3700 | ||
17a52670 AS |
3701 | } else if (class == BPF_ST) { |
3702 | if (BPF_MODE(insn->code) != BPF_MEM || | |
3703 | insn->src_reg != BPF_REG_0) { | |
61bd5218 | 3704 | verbose(env, "BPF_ST uses reserved fields\n"); |
17a52670 AS |
3705 | return -EINVAL; |
3706 | } | |
3707 | /* check src operand */ | |
dc503a8a | 3708 | err = check_reg_arg(env, insn->dst_reg, SRC_OP); |
17a52670 AS |
3709 | if (err) |
3710 | return err; | |
3711 | ||
3712 | /* check that memory (dst_reg + off) is writeable */ | |
31fd8581 | 3713 | err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, |
17a52670 AS |
3714 | BPF_SIZE(insn->code), BPF_WRITE, |
3715 | -1); | |
3716 | if (err) | |
3717 | return err; | |
3718 | ||
3719 | } else if (class == BPF_JMP) { | |
3720 | u8 opcode = BPF_OP(insn->code); | |
3721 | ||
3722 | if (opcode == BPF_CALL) { | |
3723 | if (BPF_SRC(insn->code) != BPF_K || | |
3724 | insn->off != 0 || | |
3725 | insn->src_reg != BPF_REG_0 || | |
3726 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 3727 | verbose(env, "BPF_CALL uses reserved fields\n"); |
17a52670 AS |
3728 | return -EINVAL; |
3729 | } | |
3730 | ||
81ed18ab | 3731 | err = check_call(env, insn->imm, insn_idx); |
17a52670 AS |
3732 | if (err) |
3733 | return err; | |
3734 | ||
3735 | } else if (opcode == BPF_JA) { | |
3736 | if (BPF_SRC(insn->code) != BPF_K || | |
3737 | insn->imm != 0 || | |
3738 | insn->src_reg != BPF_REG_0 || | |
3739 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 3740 | verbose(env, "BPF_JA uses reserved fields\n"); |
17a52670 AS |
3741 | return -EINVAL; |
3742 | } | |
3743 | ||
3744 | insn_idx += insn->off + 1; | |
3745 | continue; | |
3746 | ||
3747 | } else if (opcode == BPF_EXIT) { | |
3748 | if (BPF_SRC(insn->code) != BPF_K || | |
3749 | insn->imm != 0 || | |
3750 | insn->src_reg != BPF_REG_0 || | |
3751 | insn->dst_reg != BPF_REG_0) { | |
61bd5218 | 3752 | verbose(env, "BPF_EXIT uses reserved fields\n"); |
17a52670 AS |
3753 | return -EINVAL; |
3754 | } | |
3755 | ||
3756 | /* eBPF calling convetion is such that R0 is used | |
3757 | * to return the value from eBPF program. | |
3758 | * Make sure that it's readable at this time | |
3759 | * of bpf_exit, which means that program wrote | |
3760 | * something into it earlier | |
3761 | */ | |
dc503a8a | 3762 | err = check_reg_arg(env, BPF_REG_0, SRC_OP); |
17a52670 AS |
3763 | if (err) |
3764 | return err; | |
3765 | ||
1be7f75d | 3766 | if (is_pointer_value(env, BPF_REG_0)) { |
61bd5218 | 3767 | verbose(env, "R0 leaks addr as return value\n"); |
1be7f75d AS |
3768 | return -EACCES; |
3769 | } | |
3770 | ||
390ee7e2 AS |
3771 | err = check_return_code(env); |
3772 | if (err) | |
3773 | return err; | |
f1bca824 | 3774 | process_bpf_exit: |
17a52670 AS |
3775 | insn_idx = pop_stack(env, &prev_insn_idx); |
3776 | if (insn_idx < 0) { | |
3777 | break; | |
3778 | } else { | |
3779 | do_print_state = true; | |
3780 | continue; | |
3781 | } | |
3782 | } else { | |
3783 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
3784 | if (err) | |
3785 | return err; | |
3786 | } | |
3787 | } else if (class == BPF_LD) { | |
3788 | u8 mode = BPF_MODE(insn->code); | |
3789 | ||
3790 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
3791 | err = check_ld_abs(env, insn); |
3792 | if (err) | |
3793 | return err; | |
3794 | ||
17a52670 AS |
3795 | } else if (mode == BPF_IMM) { |
3796 | err = check_ld_imm(env, insn); | |
3797 | if (err) | |
3798 | return err; | |
3799 | ||
3800 | insn_idx++; | |
3801 | } else { | |
61bd5218 | 3802 | verbose(env, "invalid BPF_LD mode\n"); |
17a52670 AS |
3803 | return -EINVAL; |
3804 | } | |
3805 | } else { | |
61bd5218 | 3806 | verbose(env, "unknown insn class %d\n", class); |
17a52670 AS |
3807 | return -EINVAL; |
3808 | } | |
3809 | ||
3810 | insn_idx++; | |
3811 | } | |
3812 | ||
61bd5218 JK |
3813 | verbose(env, "processed %d insns, stack depth %d\n", insn_processed, |
3814 | env->prog->aux->stack_depth); | |
17a52670 AS |
3815 | return 0; |
3816 | } | |
3817 | ||
56f668df MKL |
3818 | static int check_map_prealloc(struct bpf_map *map) |
3819 | { | |
3820 | return (map->map_type != BPF_MAP_TYPE_HASH && | |
bcc6b1b7 MKL |
3821 | map->map_type != BPF_MAP_TYPE_PERCPU_HASH && |
3822 | map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || | |
56f668df MKL |
3823 | !(map->map_flags & BPF_F_NO_PREALLOC); |
3824 | } | |
3825 | ||
61bd5218 JK |
3826 | static int check_map_prog_compatibility(struct bpf_verifier_env *env, |
3827 | struct bpf_map *map, | |
fdc15d38 AS |
3828 | struct bpf_prog *prog) |
3829 | ||
3830 | { | |
56f668df MKL |
3831 | /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use |
3832 | * preallocated hash maps, since doing memory allocation | |
3833 | * in overflow_handler can crash depending on where nmi got | |
3834 | * triggered. | |
3835 | */ | |
3836 | if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { | |
3837 | if (!check_map_prealloc(map)) { | |
61bd5218 | 3838 | verbose(env, "perf_event programs can only use preallocated hash map\n"); |
56f668df MKL |
3839 | return -EINVAL; |
3840 | } | |
3841 | if (map->inner_map_meta && | |
3842 | !check_map_prealloc(map->inner_map_meta)) { | |
61bd5218 | 3843 | verbose(env, "perf_event programs can only use preallocated inner hash map\n"); |
56f668df MKL |
3844 | return -EINVAL; |
3845 | } | |
fdc15d38 AS |
3846 | } |
3847 | return 0; | |
3848 | } | |
3849 | ||
0246e64d AS |
3850 | /* look for pseudo eBPF instructions that access map FDs and |
3851 | * replace them with actual map pointers | |
3852 | */ | |
58e2af8b | 3853 | static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) |
0246e64d AS |
3854 | { |
3855 | struct bpf_insn *insn = env->prog->insnsi; | |
3856 | int insn_cnt = env->prog->len; | |
fdc15d38 | 3857 | int i, j, err; |
0246e64d | 3858 | |
f1f7714e | 3859 | err = bpf_prog_calc_tag(env->prog); |
aafe6ae9 DB |
3860 | if (err) |
3861 | return err; | |
3862 | ||
0246e64d | 3863 | for (i = 0; i < insn_cnt; i++, insn++) { |
9bac3d6d | 3864 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 3865 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
61bd5218 | 3866 | verbose(env, "BPF_LDX uses reserved fields\n"); |
9bac3d6d AS |
3867 | return -EINVAL; |
3868 | } | |
3869 | ||
d691f9e8 AS |
3870 | if (BPF_CLASS(insn->code) == BPF_STX && |
3871 | ((BPF_MODE(insn->code) != BPF_MEM && | |
3872 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
61bd5218 | 3873 | verbose(env, "BPF_STX uses reserved fields\n"); |
d691f9e8 AS |
3874 | return -EINVAL; |
3875 | } | |
3876 | ||
0246e64d AS |
3877 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
3878 | struct bpf_map *map; | |
3879 | struct fd f; | |
3880 | ||
3881 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
3882 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
3883 | insn[1].off != 0) { | |
61bd5218 | 3884 | verbose(env, "invalid bpf_ld_imm64 insn\n"); |
0246e64d AS |
3885 | return -EINVAL; |
3886 | } | |
3887 | ||
3888 | if (insn->src_reg == 0) | |
3889 | /* valid generic load 64-bit imm */ | |
3890 | goto next_insn; | |
3891 | ||
3892 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
61bd5218 JK |
3893 | verbose(env, |
3894 | "unrecognized bpf_ld_imm64 insn\n"); | |
0246e64d AS |
3895 | return -EINVAL; |
3896 | } | |
3897 | ||
3898 | f = fdget(insn->imm); | |
c2101297 | 3899 | map = __bpf_map_get(f); |
0246e64d | 3900 | if (IS_ERR(map)) { |
61bd5218 | 3901 | verbose(env, "fd %d is not pointing to valid bpf_map\n", |
0246e64d | 3902 | insn->imm); |
0246e64d AS |
3903 | return PTR_ERR(map); |
3904 | } | |
3905 | ||
61bd5218 | 3906 | err = check_map_prog_compatibility(env, map, env->prog); |
fdc15d38 AS |
3907 | if (err) { |
3908 | fdput(f); | |
3909 | return err; | |
3910 | } | |
3911 | ||
0246e64d AS |
3912 | /* store map pointer inside BPF_LD_IMM64 instruction */ |
3913 | insn[0].imm = (u32) (unsigned long) map; | |
3914 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
3915 | ||
3916 | /* check whether we recorded this map already */ | |
3917 | for (j = 0; j < env->used_map_cnt; j++) | |
3918 | if (env->used_maps[j] == map) { | |
3919 | fdput(f); | |
3920 | goto next_insn; | |
3921 | } | |
3922 | ||
3923 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
3924 | fdput(f); | |
3925 | return -E2BIG; | |
3926 | } | |
3927 | ||
0246e64d AS |
3928 | /* hold the map. If the program is rejected by verifier, |
3929 | * the map will be released by release_maps() or it | |
3930 | * will be used by the valid program until it's unloaded | |
3931 | * and all maps are released in free_bpf_prog_info() | |
3932 | */ | |
92117d84 AS |
3933 | map = bpf_map_inc(map, false); |
3934 | if (IS_ERR(map)) { | |
3935 | fdput(f); | |
3936 | return PTR_ERR(map); | |
3937 | } | |
3938 | env->used_maps[env->used_map_cnt++] = map; | |
3939 | ||
0246e64d AS |
3940 | fdput(f); |
3941 | next_insn: | |
3942 | insn++; | |
3943 | i++; | |
3944 | } | |
3945 | } | |
3946 | ||
3947 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
3948 | * 'struct bpf_map *' into a register instead of user map_fd. | |
3949 | * These pointers will be used later by verifier to validate map access. | |
3950 | */ | |
3951 | return 0; | |
3952 | } | |
3953 | ||
3954 | /* drop refcnt of maps used by the rejected program */ | |
58e2af8b | 3955 | static void release_maps(struct bpf_verifier_env *env) |
0246e64d AS |
3956 | { |
3957 | int i; | |
3958 | ||
3959 | for (i = 0; i < env->used_map_cnt; i++) | |
3960 | bpf_map_put(env->used_maps[i]); | |
3961 | } | |
3962 | ||
3963 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
58e2af8b | 3964 | static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) |
0246e64d AS |
3965 | { |
3966 | struct bpf_insn *insn = env->prog->insnsi; | |
3967 | int insn_cnt = env->prog->len; | |
3968 | int i; | |
3969 | ||
3970 | for (i = 0; i < insn_cnt; i++, insn++) | |
3971 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
3972 | insn->src_reg = 0; | |
3973 | } | |
3974 | ||
8041902d AS |
3975 | /* single env->prog->insni[off] instruction was replaced with the range |
3976 | * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying | |
3977 | * [0, off) and [off, end) to new locations, so the patched range stays zero | |
3978 | */ | |
3979 | static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, | |
3980 | u32 off, u32 cnt) | |
3981 | { | |
3982 | struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; | |
3983 | ||
3984 | if (cnt == 1) | |
3985 | return 0; | |
3986 | new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); | |
3987 | if (!new_data) | |
3988 | return -ENOMEM; | |
3989 | memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); | |
3990 | memcpy(new_data + off + cnt - 1, old_data + off, | |
3991 | sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); | |
3992 | env->insn_aux_data = new_data; | |
3993 | vfree(old_data); | |
3994 | return 0; | |
3995 | } | |
3996 | ||
3997 | static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, | |
3998 | const struct bpf_insn *patch, u32 len) | |
3999 | { | |
4000 | struct bpf_prog *new_prog; | |
4001 | ||
4002 | new_prog = bpf_patch_insn_single(env->prog, off, patch, len); | |
4003 | if (!new_prog) | |
4004 | return NULL; | |
4005 | if (adjust_insn_aux_data(env, new_prog->len, off, len)) | |
4006 | return NULL; | |
4007 | return new_prog; | |
4008 | } | |
4009 | ||
9bac3d6d AS |
4010 | /* convert load instructions that access fields of 'struct __sk_buff' |
4011 | * into sequence of instructions that access fields of 'struct sk_buff' | |
4012 | */ | |
58e2af8b | 4013 | static int convert_ctx_accesses(struct bpf_verifier_env *env) |
9bac3d6d | 4014 | { |
00176a34 | 4015 | const struct bpf_verifier_ops *ops = env->ops; |
f96da094 | 4016 | int i, cnt, size, ctx_field_size, delta = 0; |
3df126f3 | 4017 | const int insn_cnt = env->prog->len; |
36bbef52 | 4018 | struct bpf_insn insn_buf[16], *insn; |
9bac3d6d | 4019 | struct bpf_prog *new_prog; |
d691f9e8 | 4020 | enum bpf_access_type type; |
f96da094 DB |
4021 | bool is_narrower_load; |
4022 | u32 target_size; | |
9bac3d6d | 4023 | |
36bbef52 DB |
4024 | if (ops->gen_prologue) { |
4025 | cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, | |
4026 | env->prog); | |
4027 | if (cnt >= ARRAY_SIZE(insn_buf)) { | |
61bd5218 | 4028 | verbose(env, "bpf verifier is misconfigured\n"); |
36bbef52 DB |
4029 | return -EINVAL; |
4030 | } else if (cnt) { | |
8041902d | 4031 | new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); |
36bbef52 DB |
4032 | if (!new_prog) |
4033 | return -ENOMEM; | |
8041902d | 4034 | |
36bbef52 | 4035 | env->prog = new_prog; |
3df126f3 | 4036 | delta += cnt - 1; |
36bbef52 DB |
4037 | } |
4038 | } | |
4039 | ||
4040 | if (!ops->convert_ctx_access) | |
9bac3d6d AS |
4041 | return 0; |
4042 | ||
3df126f3 | 4043 | insn = env->prog->insnsi + delta; |
36bbef52 | 4044 | |
9bac3d6d | 4045 | for (i = 0; i < insn_cnt; i++, insn++) { |
62c7989b DB |
4046 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || |
4047 | insn->code == (BPF_LDX | BPF_MEM | BPF_H) || | |
4048 | insn->code == (BPF_LDX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4049 | insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) |
d691f9e8 | 4050 | type = BPF_READ; |
62c7989b DB |
4051 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || |
4052 | insn->code == (BPF_STX | BPF_MEM | BPF_H) || | |
4053 | insn->code == (BPF_STX | BPF_MEM | BPF_W) || | |
ea2e7ce5 | 4054 | insn->code == (BPF_STX | BPF_MEM | BPF_DW)) |
d691f9e8 AS |
4055 | type = BPF_WRITE; |
4056 | else | |
9bac3d6d AS |
4057 | continue; |
4058 | ||
8041902d | 4059 | if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) |
9bac3d6d | 4060 | continue; |
9bac3d6d | 4061 | |
31fd8581 | 4062 | ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; |
f96da094 | 4063 | size = BPF_LDST_BYTES(insn); |
31fd8581 YS |
4064 | |
4065 | /* If the read access is a narrower load of the field, | |
4066 | * convert to a 4/8-byte load, to minimum program type specific | |
4067 | * convert_ctx_access changes. If conversion is successful, | |
4068 | * we will apply proper mask to the result. | |
4069 | */ | |
f96da094 | 4070 | is_narrower_load = size < ctx_field_size; |
31fd8581 | 4071 | if (is_narrower_load) { |
f96da094 DB |
4072 | u32 off = insn->off; |
4073 | u8 size_code; | |
4074 | ||
4075 | if (type == BPF_WRITE) { | |
61bd5218 | 4076 | verbose(env, "bpf verifier narrow ctx access misconfigured\n"); |
f96da094 DB |
4077 | return -EINVAL; |
4078 | } | |
31fd8581 | 4079 | |
f96da094 | 4080 | size_code = BPF_H; |
31fd8581 YS |
4081 | if (ctx_field_size == 4) |
4082 | size_code = BPF_W; | |
4083 | else if (ctx_field_size == 8) | |
4084 | size_code = BPF_DW; | |
f96da094 | 4085 | |
31fd8581 YS |
4086 | insn->off = off & ~(ctx_field_size - 1); |
4087 | insn->code = BPF_LDX | BPF_MEM | size_code; | |
4088 | } | |
f96da094 DB |
4089 | |
4090 | target_size = 0; | |
4091 | cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog, | |
4092 | &target_size); | |
4093 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || | |
4094 | (ctx_field_size && !target_size)) { | |
61bd5218 | 4095 | verbose(env, "bpf verifier is misconfigured\n"); |
9bac3d6d AS |
4096 | return -EINVAL; |
4097 | } | |
f96da094 DB |
4098 | |
4099 | if (is_narrower_load && size < target_size) { | |
31fd8581 YS |
4100 | if (ctx_field_size <= 4) |
4101 | insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4102 | (1 << size * 8) - 1); |
31fd8581 YS |
4103 | else |
4104 | insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, | |
f96da094 | 4105 | (1 << size * 8) - 1); |
31fd8581 | 4106 | } |
9bac3d6d | 4107 | |
8041902d | 4108 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); |
9bac3d6d AS |
4109 | if (!new_prog) |
4110 | return -ENOMEM; | |
4111 | ||
3df126f3 | 4112 | delta += cnt - 1; |
9bac3d6d AS |
4113 | |
4114 | /* keep walking new program and skip insns we just inserted */ | |
4115 | env->prog = new_prog; | |
3df126f3 | 4116 | insn = new_prog->insnsi + i + delta; |
9bac3d6d AS |
4117 | } |
4118 | ||
4119 | return 0; | |
4120 | } | |
4121 | ||
79741b3b | 4122 | /* fixup insn->imm field of bpf_call instructions |
81ed18ab | 4123 | * and inline eligible helpers as explicit sequence of BPF instructions |
e245c5c6 AS |
4124 | * |
4125 | * this function is called after eBPF program passed verification | |
4126 | */ | |
79741b3b | 4127 | static int fixup_bpf_calls(struct bpf_verifier_env *env) |
e245c5c6 | 4128 | { |
79741b3b AS |
4129 | struct bpf_prog *prog = env->prog; |
4130 | struct bpf_insn *insn = prog->insnsi; | |
e245c5c6 | 4131 | const struct bpf_func_proto *fn; |
79741b3b | 4132 | const int insn_cnt = prog->len; |
81ed18ab AS |
4133 | struct bpf_insn insn_buf[16]; |
4134 | struct bpf_prog *new_prog; | |
4135 | struct bpf_map *map_ptr; | |
4136 | int i, cnt, delta = 0; | |
e245c5c6 | 4137 | |
79741b3b AS |
4138 | for (i = 0; i < insn_cnt; i++, insn++) { |
4139 | if (insn->code != (BPF_JMP | BPF_CALL)) | |
4140 | continue; | |
e245c5c6 | 4141 | |
79741b3b AS |
4142 | if (insn->imm == BPF_FUNC_get_route_realm) |
4143 | prog->dst_needed = 1; | |
4144 | if (insn->imm == BPF_FUNC_get_prandom_u32) | |
4145 | bpf_user_rnd_init_once(); | |
79741b3b | 4146 | if (insn->imm == BPF_FUNC_tail_call) { |
7b9f6da1 DM |
4147 | /* If we tail call into other programs, we |
4148 | * cannot make any assumptions since they can | |
4149 | * be replaced dynamically during runtime in | |
4150 | * the program array. | |
4151 | */ | |
4152 | prog->cb_access = 1; | |
80a58d02 | 4153 | env->prog->aux->stack_depth = MAX_BPF_STACK; |
7b9f6da1 | 4154 | |
79741b3b AS |
4155 | /* mark bpf_tail_call as different opcode to avoid |
4156 | * conditional branch in the interpeter for every normal | |
4157 | * call and to prevent accidental JITing by JIT compiler | |
4158 | * that doesn't support bpf_tail_call yet | |
e245c5c6 | 4159 | */ |
79741b3b | 4160 | insn->imm = 0; |
71189fa9 | 4161 | insn->code = BPF_JMP | BPF_TAIL_CALL; |
79741b3b AS |
4162 | continue; |
4163 | } | |
e245c5c6 | 4164 | |
89c63074 DB |
4165 | /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup |
4166 | * handlers are currently limited to 64 bit only. | |
4167 | */ | |
4168 | if (ebpf_jit_enabled() && BITS_PER_LONG == 64 && | |
4169 | insn->imm == BPF_FUNC_map_lookup_elem) { | |
81ed18ab | 4170 | map_ptr = env->insn_aux_data[i + delta].map_ptr; |
fad73a1a MKL |
4171 | if (map_ptr == BPF_MAP_PTR_POISON || |
4172 | !map_ptr->ops->map_gen_lookup) | |
81ed18ab AS |
4173 | goto patch_call_imm; |
4174 | ||
4175 | cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); | |
4176 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { | |
61bd5218 | 4177 | verbose(env, "bpf verifier is misconfigured\n"); |
81ed18ab AS |
4178 | return -EINVAL; |
4179 | } | |
4180 | ||
4181 | new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, | |
4182 | cnt); | |
4183 | if (!new_prog) | |
4184 | return -ENOMEM; | |
4185 | ||
4186 | delta += cnt - 1; | |
4187 | ||
4188 | /* keep walking new program and skip insns we just inserted */ | |
4189 | env->prog = prog = new_prog; | |
4190 | insn = new_prog->insnsi + i + delta; | |
4191 | continue; | |
4192 | } | |
4193 | ||
109980b8 | 4194 | if (insn->imm == BPF_FUNC_redirect_map) { |
7c300131 DB |
4195 | /* Note, we cannot use prog directly as imm as subsequent |
4196 | * rewrites would still change the prog pointer. The only | |
4197 | * stable address we can use is aux, which also works with | |
4198 | * prog clones during blinding. | |
4199 | */ | |
4200 | u64 addr = (unsigned long)prog->aux; | |
109980b8 DB |
4201 | struct bpf_insn r4_ld[] = { |
4202 | BPF_LD_IMM64(BPF_REG_4, addr), | |
4203 | *insn, | |
4204 | }; | |
4205 | cnt = ARRAY_SIZE(r4_ld); | |
4206 | ||
4207 | new_prog = bpf_patch_insn_data(env, i + delta, r4_ld, cnt); | |
4208 | if (!new_prog) | |
4209 | return -ENOMEM; | |
4210 | ||
4211 | delta += cnt - 1; | |
4212 | env->prog = prog = new_prog; | |
4213 | insn = new_prog->insnsi + i + delta; | |
4214 | } | |
81ed18ab | 4215 | patch_call_imm: |
00176a34 | 4216 | fn = env->ops->get_func_proto(insn->imm); |
79741b3b AS |
4217 | /* all functions that have prototype and verifier allowed |
4218 | * programs to call them, must be real in-kernel functions | |
4219 | */ | |
4220 | if (!fn->func) { | |
61bd5218 JK |
4221 | verbose(env, |
4222 | "kernel subsystem misconfigured func %s#%d\n", | |
79741b3b AS |
4223 | func_id_name(insn->imm), insn->imm); |
4224 | return -EFAULT; | |
e245c5c6 | 4225 | } |
79741b3b | 4226 | insn->imm = fn->func - __bpf_call_base; |
e245c5c6 | 4227 | } |
e245c5c6 | 4228 | |
79741b3b AS |
4229 | return 0; |
4230 | } | |
e245c5c6 | 4231 | |
58e2af8b | 4232 | static void free_states(struct bpf_verifier_env *env) |
f1bca824 | 4233 | { |
58e2af8b | 4234 | struct bpf_verifier_state_list *sl, *sln; |
f1bca824 AS |
4235 | int i; |
4236 | ||
4237 | if (!env->explored_states) | |
4238 | return; | |
4239 | ||
4240 | for (i = 0; i < env->prog->len; i++) { | |
4241 | sl = env->explored_states[i]; | |
4242 | ||
4243 | if (sl) | |
4244 | while (sl != STATE_LIST_MARK) { | |
4245 | sln = sl->next; | |
4246 | kfree(sl); | |
4247 | sl = sln; | |
4248 | } | |
4249 | } | |
4250 | ||
4251 | kfree(env->explored_states); | |
4252 | } | |
4253 | ||
9bac3d6d | 4254 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 4255 | { |
58e2af8b | 4256 | struct bpf_verifier_env *env; |
61bd5218 | 4257 | struct bpf_verifer_log *log; |
51580e79 AS |
4258 | int ret = -EINVAL; |
4259 | ||
58e2af8b | 4260 | /* 'struct bpf_verifier_env' can be global, but since it's not small, |
cbd35700 AS |
4261 | * allocate/free it every time bpf_check() is called |
4262 | */ | |
58e2af8b | 4263 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
cbd35700 AS |
4264 | if (!env) |
4265 | return -ENOMEM; | |
61bd5218 | 4266 | log = &env->log; |
cbd35700 | 4267 | |
3df126f3 JK |
4268 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * |
4269 | (*prog)->len); | |
4270 | ret = -ENOMEM; | |
4271 | if (!env->insn_aux_data) | |
4272 | goto err_free_env; | |
9bac3d6d | 4273 | env->prog = *prog; |
00176a34 | 4274 | env->ops = bpf_verifier_ops[env->prog->type]; |
0246e64d | 4275 | |
cbd35700 AS |
4276 | /* grab the mutex to protect few globals used by verifier */ |
4277 | mutex_lock(&bpf_verifier_lock); | |
4278 | ||
4279 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
4280 | /* user requested verbose verifier output | |
4281 | * and supplied buffer to store the verification trace | |
4282 | */ | |
e7bf8249 JK |
4283 | log->level = attr->log_level; |
4284 | log->ubuf = (char __user *) (unsigned long) attr->log_buf; | |
4285 | log->len_total = attr->log_size; | |
cbd35700 AS |
4286 | |
4287 | ret = -EINVAL; | |
e7bf8249 JK |
4288 | /* log attributes have to be sane */ |
4289 | if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 || | |
4290 | !log->level || !log->ubuf) | |
3df126f3 | 4291 | goto err_unlock; |
cbd35700 | 4292 | } |
1ad2f583 DB |
4293 | |
4294 | env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); | |
4295 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
e07b98d9 | 4296 | env->strict_alignment = true; |
cbd35700 | 4297 | |
0246e64d AS |
4298 | ret = replace_map_fd_with_map_ptr(env); |
4299 | if (ret < 0) | |
4300 | goto skip_full_check; | |
4301 | ||
9bac3d6d | 4302 | env->explored_states = kcalloc(env->prog->len, |
58e2af8b | 4303 | sizeof(struct bpf_verifier_state_list *), |
f1bca824 AS |
4304 | GFP_USER); |
4305 | ret = -ENOMEM; | |
4306 | if (!env->explored_states) | |
4307 | goto skip_full_check; | |
4308 | ||
475fb78f AS |
4309 | ret = check_cfg(env); |
4310 | if (ret < 0) | |
4311 | goto skip_full_check; | |
4312 | ||
1be7f75d AS |
4313 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
4314 | ||
17a52670 | 4315 | ret = do_check(env); |
cbd35700 | 4316 | |
0246e64d | 4317 | skip_full_check: |
17a52670 | 4318 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 4319 | free_states(env); |
0246e64d | 4320 | |
9bac3d6d AS |
4321 | if (ret == 0) |
4322 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
4323 | ret = convert_ctx_accesses(env); | |
4324 | ||
e245c5c6 | 4325 | if (ret == 0) |
79741b3b | 4326 | ret = fixup_bpf_calls(env); |
e245c5c6 | 4327 | |
a2a7d570 | 4328 | if (log->level && bpf_verifier_log_full(log)) |
cbd35700 | 4329 | ret = -ENOSPC; |
a2a7d570 | 4330 | if (log->level && !log->ubuf) { |
cbd35700 | 4331 | ret = -EFAULT; |
a2a7d570 | 4332 | goto err_release_maps; |
cbd35700 AS |
4333 | } |
4334 | ||
0246e64d AS |
4335 | if (ret == 0 && env->used_map_cnt) { |
4336 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
4337 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
4338 | sizeof(env->used_maps[0]), | |
4339 | GFP_KERNEL); | |
0246e64d | 4340 | |
9bac3d6d | 4341 | if (!env->prog->aux->used_maps) { |
0246e64d | 4342 | ret = -ENOMEM; |
a2a7d570 | 4343 | goto err_release_maps; |
0246e64d AS |
4344 | } |
4345 | ||
9bac3d6d | 4346 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 4347 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 4348 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
4349 | |
4350 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
4351 | * bpf_ld_imm64 instructions | |
4352 | */ | |
4353 | convert_pseudo_ld_imm64(env); | |
4354 | } | |
cbd35700 | 4355 | |
a2a7d570 | 4356 | err_release_maps: |
9bac3d6d | 4357 | if (!env->prog->aux->used_maps) |
0246e64d AS |
4358 | /* if we didn't copy map pointers into bpf_prog_info, release |
4359 | * them now. Otherwise free_bpf_prog_info() will release them. | |
4360 | */ | |
4361 | release_maps(env); | |
9bac3d6d | 4362 | *prog = env->prog; |
3df126f3 | 4363 | err_unlock: |
cbd35700 | 4364 | mutex_unlock(&bpf_verifier_lock); |
3df126f3 JK |
4365 | vfree(env->insn_aux_data); |
4366 | err_free_env: | |
4367 | kfree(env); | |
51580e79 AS |
4368 | return ret; |
4369 | } | |
13a27dfc | 4370 | |
4f9218aa JK |
4371 | static const struct bpf_verifier_ops * const bpf_analyzer_ops[] = { |
4372 | [BPF_PROG_TYPE_XDP] = &xdp_analyzer_ops, | |
4373 | [BPF_PROG_TYPE_SCHED_CLS] = &tc_cls_act_analyzer_ops, | |
4374 | }; | |
4375 | ||
13a27dfc JK |
4376 | int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, |
4377 | void *priv) | |
4378 | { | |
4379 | struct bpf_verifier_env *env; | |
4380 | int ret; | |
4381 | ||
4f9218aa JK |
4382 | if (prog->type >= ARRAY_SIZE(bpf_analyzer_ops) || |
4383 | !bpf_analyzer_ops[prog->type]) | |
4384 | return -EOPNOTSUPP; | |
4385 | ||
13a27dfc JK |
4386 | env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); |
4387 | if (!env) | |
4388 | return -ENOMEM; | |
4389 | ||
4390 | env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * | |
4391 | prog->len); | |
4392 | ret = -ENOMEM; | |
4393 | if (!env->insn_aux_data) | |
4394 | goto err_free_env; | |
4395 | env->prog = prog; | |
4f9218aa | 4396 | env->ops = bpf_analyzer_ops[env->prog->type]; |
13a27dfc JK |
4397 | env->analyzer_ops = ops; |
4398 | env->analyzer_priv = priv; | |
4399 | ||
4400 | /* grab the mutex to protect few globals used by verifier */ | |
4401 | mutex_lock(&bpf_verifier_lock); | |
4402 | ||
e07b98d9 | 4403 | env->strict_alignment = false; |
1ad2f583 DB |
4404 | if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) |
4405 | env->strict_alignment = true; | |
13a27dfc JK |
4406 | |
4407 | env->explored_states = kcalloc(env->prog->len, | |
4408 | sizeof(struct bpf_verifier_state_list *), | |
4409 | GFP_KERNEL); | |
4410 | ret = -ENOMEM; | |
4411 | if (!env->explored_states) | |
4412 | goto skip_full_check; | |
4413 | ||
4414 | ret = check_cfg(env); | |
4415 | if (ret < 0) | |
4416 | goto skip_full_check; | |
4417 | ||
4418 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); | |
4419 | ||
4420 | ret = do_check(env); | |
4421 | ||
4422 | skip_full_check: | |
4423 | while (pop_stack(env, NULL) >= 0); | |
4424 | free_states(env); | |
4425 | ||
4426 | mutex_unlock(&bpf_verifier_lock); | |
4427 | vfree(env->insn_aux_data); | |
4428 | err_free_env: | |
4429 | kfree(env); | |
4430 | return ret; | |
4431 | } | |
4432 | EXPORT_SYMBOL_GPL(bpf_analyzer); |