1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
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.
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.
13 #include <linux/kernel.h>
14 #include <linux/types.h>
15 #include <linux/slab.h>
16 #include <linux/bpf.h>
17 #include <linux/bpf_verifier.h>
18 #include <linux/filter.h>
19 #include <net/netlink.h>
20 #include <linux/file.h>
21 #include <linux/vmalloc.h>
22 #include <linux/stringify.h>
24 /* bpf_check() is a static code analyzer that walks eBPF program
25 * instruction by instruction and updates register/stack state.
26 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
28 * The first pass is depth-first-search to check that the program is a DAG.
29 * It rejects the following programs:
30 * - larger than BPF_MAXINSNS insns
31 * - if loop is present (detected via back-edge)
32 * - unreachable insns exist (shouldn't be a forest. program = one function)
33 * - out of bounds or malformed jumps
34 * The second pass is all possible path descent from the 1st insn.
35 * Since it's analyzing all pathes through the program, the length of the
36 * analysis is limited to 64k insn, which may be hit even if total number of
37 * insn is less then 4K, but there are too many branches that change stack/regs.
38 * Number of 'branches to be analyzed' is limited to 1k
40 * On entry to each instruction, each register has a type, and the instruction
41 * changes the types of the registers depending on instruction semantics.
42 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
45 * All registers are 64-bit.
46 * R0 - return register
47 * R1-R5 argument passing registers
48 * R6-R9 callee saved registers
49 * R10 - frame pointer read-only
51 * At the start of BPF program the register R1 contains a pointer to bpf_context
52 * and has type PTR_TO_CTX.
54 * Verifier tracks arithmetic operations on pointers in case:
55 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
56 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
57 * 1st insn copies R10 (which has FRAME_PTR) type into R1
58 * and 2nd arithmetic instruction is pattern matched to recognize
59 * that it wants to construct a pointer to some element within stack.
60 * So after 2nd insn, the register R1 has type PTR_TO_STACK
61 * (and -20 constant is saved for further stack bounds checking).
62 * Meaning that this reg is a pointer to stack plus known immediate constant.
64 * Most of the time the registers have UNKNOWN_VALUE type, which
65 * means the register has some value, but it's not a valid pointer.
66 * (like pointer plus pointer becomes UNKNOWN_VALUE type)
68 * When verifier sees load or store instructions the type of base register
69 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
70 * types recognized by check_mem_access() function.
72 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
73 * and the range of [ptr, ptr + map's value_size) is accessible.
75 * registers used to pass values to function calls are checked against
76 * function argument constraints.
78 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
79 * It means that the register type passed to this function must be
80 * PTR_TO_STACK and it will be used inside the function as
81 * 'pointer to map element key'
83 * For example the argument constraints for bpf_map_lookup_elem():
84 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
85 * .arg1_type = ARG_CONST_MAP_PTR,
86 * .arg2_type = ARG_PTR_TO_MAP_KEY,
88 * ret_type says that this function returns 'pointer to map elem value or null'
89 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
90 * 2nd argument should be a pointer to stack, which will be used inside
91 * the helper function as a pointer to map element key.
93 * On the kernel side the helper function looks like:
94 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
96 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
97 * void *key = (void *) (unsigned long) r2;
100 * here kernel can access 'key' and 'map' pointers safely, knowing that
101 * [key, key + map->key_size) bytes are valid and were initialized on
102 * the stack of eBPF program.
105 * Corresponding eBPF program may look like:
106 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
107 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
108 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
109 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
110 * here verifier looks at prototype of map_lookup_elem() and sees:
111 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
112 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
114 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
115 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
116 * and were initialized prior to this call.
117 * If it's ok, then verifier allows this BPF_CALL insn and looks at
118 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
119 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
120 * returns ether pointer to map value or NULL.
122 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
123 * insn, the register holding that pointer in the true branch changes state to
124 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
125 * branch. See check_cond_jmp_op().
127 * After the call R0 is set to return type of the function and registers R1-R5
128 * are set to NOT_INIT to indicate that they are no longer readable.
131 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
132 struct bpf_verifier_stack_elem {
133 /* verifer state is 'st'
134 * before processing instruction 'insn_idx'
135 * and after processing instruction 'prev_insn_idx'
137 struct bpf_verifier_state st;
140 struct bpf_verifier_stack_elem *next;
143 #define BPF_COMPLEXITY_LIMIT_INSNS 98304
144 #define BPF_COMPLEXITY_LIMIT_STACK 1024
146 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
148 struct bpf_call_arg_meta {
149 struct bpf_map *map_ptr;
156 /* verbose verifier prints what it's seeing
157 * bpf_check() is called under lock, so no race to access these global vars
159 static u32 log_level, log_size, log_len;
160 static char *log_buf;
162 static DEFINE_MUTEX(bpf_verifier_lock);
164 /* log_level controls verbosity level of eBPF verifier.
165 * verbose() is used to dump the verification trace to the log, so the user
166 * can figure out what's wrong with the program
168 static __printf(1, 2) void verbose(const char *fmt, ...)
172 if (log_level == 0 || log_len >= log_size - 1)
176 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
180 /* string representation of 'enum bpf_reg_type' */
181 static const char * const reg_type_str[] = {
183 [UNKNOWN_VALUE] = "inv",
184 [PTR_TO_CTX] = "ctx",
185 [CONST_PTR_TO_MAP] = "map_ptr",
186 [PTR_TO_MAP_VALUE] = "map_value",
187 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
188 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj",
190 [PTR_TO_STACK] = "fp",
192 [PTR_TO_PACKET] = "pkt",
193 [PTR_TO_PACKET_END] = "pkt_end",
196 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
197 static const char * const func_id_str[] = {
198 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
200 #undef __BPF_FUNC_STR_FN
202 static const char *func_id_name(int id)
204 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
206 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
207 return func_id_str[id];
212 static void print_verifier_state(struct bpf_verifier_state *state)
214 struct bpf_reg_state *reg;
218 for (i = 0; i < MAX_BPF_REG; i++) {
219 reg = &state->regs[i];
223 verbose(" R%d=%s", i, reg_type_str[t]);
224 if (t == CONST_IMM || t == PTR_TO_STACK)
225 verbose("%lld", reg->imm);
226 else if (t == PTR_TO_PACKET)
227 verbose("(id=%d,off=%d,r=%d)",
228 reg->id, reg->off, reg->range);
229 else if (t == UNKNOWN_VALUE && reg->imm)
230 verbose("%lld", reg->imm);
231 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
232 t == PTR_TO_MAP_VALUE_OR_NULL ||
233 t == PTR_TO_MAP_VALUE_ADJ)
234 verbose("(ks=%d,vs=%d,id=%u)",
235 reg->map_ptr->key_size,
236 reg->map_ptr->value_size,
238 if (reg->min_value != BPF_REGISTER_MIN_RANGE)
239 verbose(",min_value=%lld",
240 (long long)reg->min_value);
241 if (reg->max_value != BPF_REGISTER_MAX_RANGE)
242 verbose(",max_value=%llu",
243 (unsigned long long)reg->max_value);
245 verbose(",min_align=%u", reg->min_align);
247 verbose(",aux_off=%u", reg->aux_off);
248 if (reg->aux_off_align)
249 verbose(",aux_off_align=%u", reg->aux_off_align);
251 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
252 if (state->stack_slot_type[i] == STACK_SPILL)
253 verbose(" fp%d=%s", -MAX_BPF_STACK + i,
254 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]);
259 static const char *const bpf_class_string[] = {
267 [BPF_ALU64] = "alu64",
270 static const char *const bpf_alu_string[16] = {
271 [BPF_ADD >> 4] = "+=",
272 [BPF_SUB >> 4] = "-=",
273 [BPF_MUL >> 4] = "*=",
274 [BPF_DIV >> 4] = "/=",
275 [BPF_OR >> 4] = "|=",
276 [BPF_AND >> 4] = "&=",
277 [BPF_LSH >> 4] = "<<=",
278 [BPF_RSH >> 4] = ">>=",
279 [BPF_NEG >> 4] = "neg",
280 [BPF_MOD >> 4] = "%=",
281 [BPF_XOR >> 4] = "^=",
282 [BPF_MOV >> 4] = "=",
283 [BPF_ARSH >> 4] = "s>>=",
284 [BPF_END >> 4] = "endian",
287 static const char *const bpf_ldst_string[] = {
288 [BPF_W >> 3] = "u32",
289 [BPF_H >> 3] = "u16",
291 [BPF_DW >> 3] = "u64",
294 static const char *const bpf_jmp_string[16] = {
295 [BPF_JA >> 4] = "jmp",
296 [BPF_JEQ >> 4] = "==",
297 [BPF_JGT >> 4] = ">",
298 [BPF_JGE >> 4] = ">=",
299 [BPF_JSET >> 4] = "&",
300 [BPF_JNE >> 4] = "!=",
301 [BPF_JSGT >> 4] = "s>",
302 [BPF_JSGE >> 4] = "s>=",
303 [BPF_CALL >> 4] = "call",
304 [BPF_EXIT >> 4] = "exit",
307 static void print_bpf_insn(const struct bpf_verifier_env *env,
308 const struct bpf_insn *insn)
310 u8 class = BPF_CLASS(insn->code);
312 if (class == BPF_ALU || class == BPF_ALU64) {
313 if (BPF_SRC(insn->code) == BPF_X)
314 verbose("(%02x) %sr%d %s %sr%d\n",
315 insn->code, class == BPF_ALU ? "(u32) " : "",
317 bpf_alu_string[BPF_OP(insn->code) >> 4],
318 class == BPF_ALU ? "(u32) " : "",
321 verbose("(%02x) %sr%d %s %s%d\n",
322 insn->code, class == BPF_ALU ? "(u32) " : "",
324 bpf_alu_string[BPF_OP(insn->code) >> 4],
325 class == BPF_ALU ? "(u32) " : "",
327 } else if (class == BPF_STX) {
328 if (BPF_MODE(insn->code) == BPF_MEM)
329 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
331 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
333 insn->off, insn->src_reg);
334 else if (BPF_MODE(insn->code) == BPF_XADD)
335 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
337 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
338 insn->dst_reg, insn->off,
341 verbose("BUG_%02x\n", insn->code);
342 } else if (class == BPF_ST) {
343 if (BPF_MODE(insn->code) != BPF_MEM) {
344 verbose("BUG_st_%02x\n", insn->code);
347 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
349 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
351 insn->off, insn->imm);
352 } else if (class == BPF_LDX) {
353 if (BPF_MODE(insn->code) != BPF_MEM) {
354 verbose("BUG_ldx_%02x\n", insn->code);
357 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
358 insn->code, insn->dst_reg,
359 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
360 insn->src_reg, insn->off);
361 } else if (class == BPF_LD) {
362 if (BPF_MODE(insn->code) == BPF_ABS) {
363 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
365 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
367 } else if (BPF_MODE(insn->code) == BPF_IND) {
368 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
370 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
371 insn->src_reg, insn->imm);
372 } else if (BPF_MODE(insn->code) == BPF_IMM &&
373 BPF_SIZE(insn->code) == BPF_DW) {
374 /* At this point, we already made sure that the second
375 * part of the ldimm64 insn is accessible.
377 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
378 bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD;
380 if (map_ptr && !env->allow_ptr_leaks)
383 verbose("(%02x) r%d = 0x%llx\n", insn->code,
384 insn->dst_reg, (unsigned long long)imm);
386 verbose("BUG_ld_%02x\n", insn->code);
389 } else if (class == BPF_JMP) {
390 u8 opcode = BPF_OP(insn->code);
392 if (opcode == BPF_CALL) {
393 verbose("(%02x) call %s#%d\n", insn->code,
394 func_id_name(insn->imm), insn->imm);
395 } else if (insn->code == (BPF_JMP | BPF_JA)) {
396 verbose("(%02x) goto pc%+d\n",
397 insn->code, insn->off);
398 } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
399 verbose("(%02x) exit\n", insn->code);
400 } else if (BPF_SRC(insn->code) == BPF_X) {
401 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
402 insn->code, insn->dst_reg,
403 bpf_jmp_string[BPF_OP(insn->code) >> 4],
404 insn->src_reg, insn->off);
406 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
407 insn->code, insn->dst_reg,
408 bpf_jmp_string[BPF_OP(insn->code) >> 4],
409 insn->imm, insn->off);
412 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
416 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
418 struct bpf_verifier_stack_elem *elem;
421 if (env->head == NULL)
424 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
425 insn_idx = env->head->insn_idx;
427 *prev_insn_idx = env->head->prev_insn_idx;
428 elem = env->head->next;
435 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
436 int insn_idx, int prev_insn_idx)
438 struct bpf_verifier_stack_elem *elem;
440 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
444 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
445 elem->insn_idx = insn_idx;
446 elem->prev_insn_idx = prev_insn_idx;
447 elem->next = env->head;
450 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
451 verbose("BPF program is too complex\n");
456 /* pop all elements and return */
457 while (pop_stack(env, NULL) >= 0);
461 #define CALLER_SAVED_REGS 6
462 static const int caller_saved[CALLER_SAVED_REGS] = {
463 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
466 static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno)
468 BUG_ON(regno >= MAX_BPF_REG);
470 memset(®s[regno], 0, sizeof(regs[regno]));
471 regs[regno].type = NOT_INIT;
472 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
473 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
476 static void init_reg_state(struct bpf_reg_state *regs)
480 for (i = 0; i < MAX_BPF_REG; i++)
481 mark_reg_not_init(regs, i);
484 regs[BPF_REG_FP].type = FRAME_PTR;
486 /* 1st arg to a function */
487 regs[BPF_REG_1].type = PTR_TO_CTX;
490 static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
492 regs[regno].type = UNKNOWN_VALUE;
497 static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
499 BUG_ON(regno >= MAX_BPF_REG);
500 __mark_reg_unknown_value(regs, regno);
503 static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno)
505 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
506 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
507 regs[regno].value_from_signed = false;
508 regs[regno].min_align = 0;
511 static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs,
514 mark_reg_unknown_value(regs, regno);
515 reset_reg_range_values(regs, regno);
519 SRC_OP, /* register is used as source operand */
520 DST_OP, /* register is used as destination operand */
521 DST_OP_NO_MARK /* same as above, check only, don't mark */
524 static int check_reg_arg(struct bpf_reg_state *regs, u32 regno,
527 if (regno >= MAX_BPF_REG) {
528 verbose("R%d is invalid\n", regno);
533 /* check whether register used as source operand can be read */
534 if (regs[regno].type == NOT_INIT) {
535 verbose("R%d !read_ok\n", regno);
539 /* check whether register used as dest operand can be written to */
540 if (regno == BPF_REG_FP) {
541 verbose("frame pointer is read only\n");
545 mark_reg_unknown_value(regs, regno);
550 static bool is_spillable_regtype(enum bpf_reg_type type)
553 case PTR_TO_MAP_VALUE:
554 case PTR_TO_MAP_VALUE_OR_NULL:
555 case PTR_TO_MAP_VALUE_ADJ:
559 case PTR_TO_PACKET_END:
561 case CONST_PTR_TO_MAP:
568 /* check_stack_read/write functions track spill/fill of registers,
569 * stack boundary and alignment are checked in check_mem_access()
571 static int check_stack_write(struct bpf_verifier_state *state, int off,
572 int size, int value_regno)
575 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
576 * so it's aligned access and [off, off + size) are within stack limits
579 if (value_regno >= 0 &&
580 is_spillable_regtype(state->regs[value_regno].type)) {
582 /* register containing pointer is being spilled into stack */
583 if (size != BPF_REG_SIZE) {
584 verbose("invalid size of register spill\n");
588 /* save register state */
589 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
590 state->regs[value_regno];
592 for (i = 0; i < BPF_REG_SIZE; i++)
593 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
595 /* regular write of data into stack */
596 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
597 (struct bpf_reg_state) {};
599 for (i = 0; i < size; i++)
600 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
605 static int check_stack_read(struct bpf_verifier_state *state, int off, int size,
611 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
613 if (slot_type[0] == STACK_SPILL) {
614 if (size != BPF_REG_SIZE) {
615 verbose("invalid size of register spill\n");
618 for (i = 1; i < BPF_REG_SIZE; i++) {
619 if (slot_type[i] != STACK_SPILL) {
620 verbose("corrupted spill memory\n");
625 if (value_regno >= 0)
626 /* restore register state from stack */
627 state->regs[value_regno] =
628 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
631 for (i = 0; i < size; i++) {
632 if (slot_type[i] != STACK_MISC) {
633 verbose("invalid read from stack off %d+%d size %d\n",
638 if (value_regno >= 0)
639 /* have read misc data from the stack */
640 mark_reg_unknown_value_and_range(state->regs,
646 /* check read/write into map element returned by bpf_map_lookup_elem() */
647 static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
650 struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
652 if (off < 0 || size <= 0 || off + size > map->value_size) {
653 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
654 map->value_size, off, size);
660 /* check read/write into an adjusted map element */
661 static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno,
664 struct bpf_verifier_state *state = &env->cur_state;
665 struct bpf_reg_state *reg = &state->regs[regno];
668 /* We adjusted the register to this map value, so we
669 * need to change off and size to min_value and max_value
670 * respectively to make sure our theoretical access will be
674 print_verifier_state(state);
675 env->varlen_map_value_access = true;
676 /* The minimum value is only important with signed
677 * comparisons where we can't assume the floor of a
678 * value is 0. If we are using signed variables for our
679 * index'es we need to make sure that whatever we use
680 * will have a set floor within our range.
682 if (reg->min_value < 0) {
683 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
687 err = check_map_access(env, regno, reg->min_value + off, size);
689 verbose("R%d min value is outside of the array range\n",
694 /* If we haven't set a max value then we need to bail
695 * since we can't be sure we won't do bad things.
697 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
698 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
702 return check_map_access(env, regno, reg->max_value + off, size);
705 #define MAX_PACKET_OFF 0xffff
707 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
708 const struct bpf_call_arg_meta *meta,
709 enum bpf_access_type t)
711 switch (env->prog->type) {
712 case BPF_PROG_TYPE_LWT_IN:
713 case BPF_PROG_TYPE_LWT_OUT:
714 /* dst_input() and dst_output() can't write for now */
718 case BPF_PROG_TYPE_SCHED_CLS:
719 case BPF_PROG_TYPE_SCHED_ACT:
720 case BPF_PROG_TYPE_XDP:
721 case BPF_PROG_TYPE_LWT_XMIT:
723 return meta->pkt_access;
725 env->seen_direct_write = true;
732 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
735 struct bpf_reg_state *regs = env->cur_state.regs;
736 struct bpf_reg_state *reg = ®s[regno];
739 if (off < 0 || size <= 0 || off + size > reg->range) {
740 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
741 off, size, regno, reg->id, reg->off, reg->range);
747 /* check access to 'struct bpf_context' fields */
748 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
749 enum bpf_access_type t, enum bpf_reg_type *reg_type)
751 struct bpf_insn_access_aux info = {
752 .reg_type = *reg_type,
755 /* for analyzer ctx accesses are already validated and converted */
756 if (env->analyzer_ops)
759 if (env->prog->aux->ops->is_valid_access &&
760 env->prog->aux->ops->is_valid_access(off, size, t, &info)) {
761 /* A non zero info.ctx_field_size indicates that this field is a
762 * candidate for later verifier transformation to load the whole
763 * field and then apply a mask when accessed with a narrower
764 * access than actual ctx access size. A zero info.ctx_field_size
765 * will only allow for whole field access and rejects any other
766 * type of narrower access.
768 env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
769 *reg_type = info.reg_type;
771 /* remember the offset of last byte accessed in ctx */
772 if (env->prog->aux->max_ctx_offset < off + size)
773 env->prog->aux->max_ctx_offset = off + size;
777 verbose("invalid bpf_context access off=%d size=%d\n", off, size);
781 static bool __is_pointer_value(bool allow_ptr_leaks,
782 const struct bpf_reg_state *reg)
796 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
798 return __is_pointer_value(env->allow_ptr_leaks, &env->cur_state.regs[regno]);
801 static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg,
802 int off, int size, bool strict)
807 /* Byte size accesses are always allowed. */
808 if (!strict || size == 1)
813 if (reg->aux_off_align % size) {
814 verbose("Packet access is only %u byte aligned, %d byte access not allowed\n",
815 reg->aux_off_align, size);
818 reg_off += reg->aux_off;
821 /* For platforms that do not have a Kconfig enabling
822 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
823 * NET_IP_ALIGN is universally set to '2'. And on platforms
824 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
825 * to this code only in strict mode where we want to emulate
826 * the NET_IP_ALIGN==2 checking. Therefore use an
827 * unconditional IP align value of '2'.
830 if ((ip_align + reg_off + off) % size != 0) {
831 verbose("misaligned packet access off %d+%d+%d size %d\n",
832 ip_align, reg_off, off, size);
839 static int check_val_ptr_alignment(const struct bpf_reg_state *reg,
840 int size, bool strict)
842 if (strict && size != 1) {
843 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n");
850 static int check_ptr_alignment(struct bpf_verifier_env *env,
851 const struct bpf_reg_state *reg,
854 bool strict = env->strict_alignment;
858 return check_pkt_ptr_alignment(reg, off, size, strict);
859 case PTR_TO_MAP_VALUE_ADJ:
860 return check_val_ptr_alignment(reg, size, strict);
862 if (off % size != 0) {
863 verbose("misaligned access off %d size %d\n",
872 /* check whether memory at (regno + off) is accessible for t = (read | write)
873 * if t==write, value_regno is a register which value is stored into memory
874 * if t==read, value_regno is a register which will receive the value from memory
875 * if t==write && value_regno==-1, some unknown value is stored into memory
876 * if t==read && value_regno==-1, don't care what we read from memory
878 static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off,
879 int bpf_size, enum bpf_access_type t,
882 struct bpf_verifier_state *state = &env->cur_state;
883 struct bpf_reg_state *reg = &state->regs[regno];
886 if (reg->type == PTR_TO_STACK)
889 size = bpf_size_to_bytes(bpf_size);
893 err = check_ptr_alignment(env, reg, off, size);
897 if (reg->type == PTR_TO_MAP_VALUE ||
898 reg->type == PTR_TO_MAP_VALUE_ADJ) {
899 if (t == BPF_WRITE && value_regno >= 0 &&
900 is_pointer_value(env, value_regno)) {
901 verbose("R%d leaks addr into map\n", value_regno);
905 if (reg->type == PTR_TO_MAP_VALUE_ADJ)
906 err = check_map_access_adj(env, regno, off, size);
908 err = check_map_access(env, regno, off, size);
909 if (!err && t == BPF_READ && value_regno >= 0)
910 mark_reg_unknown_value_and_range(state->regs,
913 } else if (reg->type == PTR_TO_CTX) {
914 enum bpf_reg_type reg_type = UNKNOWN_VALUE;
916 if (t == BPF_WRITE && value_regno >= 0 &&
917 is_pointer_value(env, value_regno)) {
918 verbose("R%d leaks addr into ctx\n", value_regno);
921 err = check_ctx_access(env, insn_idx, off, size, t, ®_type);
922 if (!err && t == BPF_READ && value_regno >= 0) {
923 mark_reg_unknown_value_and_range(state->regs,
925 /* note that reg.[id|off|range] == 0 */
926 state->regs[value_regno].type = reg_type;
927 state->regs[value_regno].aux_off = 0;
928 state->regs[value_regno].aux_off_align = 0;
931 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) {
932 if (off >= 0 || off < -MAX_BPF_STACK) {
933 verbose("invalid stack off=%d size=%d\n", off, size);
937 if (env->prog->aux->stack_depth < -off)
938 env->prog->aux->stack_depth = -off;
940 if (t == BPF_WRITE) {
941 if (!env->allow_ptr_leaks &&
942 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
943 size != BPF_REG_SIZE) {
944 verbose("attempt to corrupt spilled pointer on stack\n");
947 err = check_stack_write(state, off, size, value_regno);
949 err = check_stack_read(state, off, size, value_regno);
951 } else if (state->regs[regno].type == PTR_TO_PACKET) {
952 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
953 verbose("cannot write into packet\n");
956 if (t == BPF_WRITE && value_regno >= 0 &&
957 is_pointer_value(env, value_regno)) {
958 verbose("R%d leaks addr into packet\n", value_regno);
961 err = check_packet_access(env, regno, off, size);
962 if (!err && t == BPF_READ && value_regno >= 0)
963 mark_reg_unknown_value_and_range(state->regs,
966 verbose("R%d invalid mem access '%s'\n",
967 regno, reg_type_str[reg->type]);
971 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks &&
972 state->regs[value_regno].type == UNKNOWN_VALUE) {
973 /* 1 or 2 byte load zero-extends, determine the number of
974 * zero upper bits. Not doing it fo 4 byte load, since
975 * such values cannot be added to ptr_to_packet anyway.
977 state->regs[value_regno].imm = 64 - size * 8;
982 static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
984 struct bpf_reg_state *regs = env->cur_state.regs;
987 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
989 verbose("BPF_XADD uses reserved fields\n");
993 /* check src1 operand */
994 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
998 /* check src2 operand */
999 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1003 if (is_pointer_value(env, insn->src_reg)) {
1004 verbose("R%d leaks addr into mem\n", insn->src_reg);
1008 /* check whether atomic_add can read the memory */
1009 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
1010 BPF_SIZE(insn->code), BPF_READ, -1);
1014 /* check whether atomic_add can write into the same memory */
1015 return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
1016 BPF_SIZE(insn->code), BPF_WRITE, -1);
1019 /* when register 'regno' is passed into function that will read 'access_size'
1020 * bytes from that pointer, make sure that it's within stack boundary
1021 * and all elements of stack are initialized
1023 static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
1024 int access_size, bool zero_size_allowed,
1025 struct bpf_call_arg_meta *meta)
1027 struct bpf_verifier_state *state = &env->cur_state;
1028 struct bpf_reg_state *regs = state->regs;
1031 if (regs[regno].type != PTR_TO_STACK) {
1032 if (zero_size_allowed && access_size == 0 &&
1033 regs[regno].type == CONST_IMM &&
1034 regs[regno].imm == 0)
1037 verbose("R%d type=%s expected=%s\n", regno,
1038 reg_type_str[regs[regno].type],
1039 reg_type_str[PTR_TO_STACK]);
1043 off = regs[regno].imm;
1044 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
1046 verbose("invalid stack type R%d off=%d access_size=%d\n",
1047 regno, off, access_size);
1051 if (env->prog->aux->stack_depth < -off)
1052 env->prog->aux->stack_depth = -off;
1054 if (meta && meta->raw_mode) {
1055 meta->access_size = access_size;
1056 meta->regno = regno;
1060 for (i = 0; i < access_size; i++) {
1061 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
1062 verbose("invalid indirect read from stack off %d+%d size %d\n",
1063 off, i, access_size);
1070 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
1071 int access_size, bool zero_size_allowed,
1072 struct bpf_call_arg_meta *meta)
1074 struct bpf_reg_state *regs = env->cur_state.regs;
1076 switch (regs[regno].type) {
1078 return check_packet_access(env, regno, 0, access_size);
1079 case PTR_TO_MAP_VALUE:
1080 return check_map_access(env, regno, 0, access_size);
1081 case PTR_TO_MAP_VALUE_ADJ:
1082 return check_map_access_adj(env, regno, 0, access_size);
1083 default: /* const_imm|ptr_to_stack or invalid ptr */
1084 return check_stack_boundary(env, regno, access_size,
1085 zero_size_allowed, meta);
1089 static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
1090 enum bpf_arg_type arg_type,
1091 struct bpf_call_arg_meta *meta)
1093 struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno];
1094 enum bpf_reg_type expected_type, type = reg->type;
1097 if (arg_type == ARG_DONTCARE)
1100 if (type == NOT_INIT) {
1101 verbose("R%d !read_ok\n", regno);
1105 if (arg_type == ARG_ANYTHING) {
1106 if (is_pointer_value(env, regno)) {
1107 verbose("R%d leaks addr into helper function\n", regno);
1113 if (type == PTR_TO_PACKET &&
1114 !may_access_direct_pkt_data(env, meta, BPF_READ)) {
1115 verbose("helper access to the packet is not allowed\n");
1119 if (arg_type == ARG_PTR_TO_MAP_KEY ||
1120 arg_type == ARG_PTR_TO_MAP_VALUE) {
1121 expected_type = PTR_TO_STACK;
1122 if (type != PTR_TO_PACKET && type != expected_type)
1124 } else if (arg_type == ARG_CONST_SIZE ||
1125 arg_type == ARG_CONST_SIZE_OR_ZERO) {
1126 expected_type = CONST_IMM;
1127 /* One exception. Allow UNKNOWN_VALUE registers when the
1128 * boundaries are known and don't cause unsafe memory accesses
1130 if (type != UNKNOWN_VALUE && type != expected_type)
1132 } else if (arg_type == ARG_CONST_MAP_PTR) {
1133 expected_type = CONST_PTR_TO_MAP;
1134 if (type != expected_type)
1136 } else if (arg_type == ARG_PTR_TO_CTX) {
1137 expected_type = PTR_TO_CTX;
1138 if (type != expected_type)
1140 } else if (arg_type == ARG_PTR_TO_MEM ||
1141 arg_type == ARG_PTR_TO_UNINIT_MEM) {
1142 expected_type = PTR_TO_STACK;
1143 /* One exception here. In case function allows for NULL to be
1144 * passed in as argument, it's a CONST_IMM type. Final test
1145 * happens during stack boundary checking.
1147 if (type == CONST_IMM && reg->imm == 0)
1148 /* final test in check_stack_boundary() */;
1149 else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE &&
1150 type != PTR_TO_MAP_VALUE_ADJ && type != expected_type)
1152 meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
1154 verbose("unsupported arg_type %d\n", arg_type);
1158 if (arg_type == ARG_CONST_MAP_PTR) {
1159 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1160 meta->map_ptr = reg->map_ptr;
1161 } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
1162 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1163 * check that [key, key + map->key_size) are within
1164 * stack limits and initialized
1166 if (!meta->map_ptr) {
1167 /* in function declaration map_ptr must come before
1168 * map_key, so that it's verified and known before
1169 * we have to check map_key here. Otherwise it means
1170 * that kernel subsystem misconfigured verifier
1172 verbose("invalid map_ptr to access map->key\n");
1175 if (type == PTR_TO_PACKET)
1176 err = check_packet_access(env, regno, 0,
1177 meta->map_ptr->key_size);
1179 err = check_stack_boundary(env, regno,
1180 meta->map_ptr->key_size,
1182 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
1183 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1184 * check [value, value + map->value_size) validity
1186 if (!meta->map_ptr) {
1187 /* kernel subsystem misconfigured verifier */
1188 verbose("invalid map_ptr to access map->value\n");
1191 if (type == PTR_TO_PACKET)
1192 err = check_packet_access(env, regno, 0,
1193 meta->map_ptr->value_size);
1195 err = check_stack_boundary(env, regno,
1196 meta->map_ptr->value_size,
1198 } else if (arg_type == ARG_CONST_SIZE ||
1199 arg_type == ARG_CONST_SIZE_OR_ZERO) {
1200 bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
1202 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1203 * from stack pointer 'buf'. Check it
1204 * note: regno == len, regno - 1 == buf
1207 /* kernel subsystem misconfigured verifier */
1208 verbose("ARG_CONST_SIZE cannot be first argument\n");
1212 /* If the register is UNKNOWN_VALUE, the access check happens
1213 * using its boundaries. Otherwise, just use its imm
1215 if (type == UNKNOWN_VALUE) {
1216 /* For unprivileged variable accesses, disable raw
1217 * mode so that the program is required to
1218 * initialize all the memory that the helper could
1219 * just partially fill up.
1223 if (reg->min_value < 0) {
1224 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n",
1229 if (reg->min_value == 0) {
1230 err = check_helper_mem_access(env, regno - 1, 0,
1237 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
1238 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
1242 err = check_helper_mem_access(env, regno - 1,
1244 zero_size_allowed, meta);
1248 /* register is CONST_IMM */
1249 err = check_helper_mem_access(env, regno - 1, reg->imm,
1250 zero_size_allowed, meta);
1256 verbose("R%d type=%s expected=%s\n", regno,
1257 reg_type_str[type], reg_type_str[expected_type]);
1261 static int check_map_func_compatibility(struct bpf_map *map, int func_id)
1266 /* We need a two way check, first is from map perspective ... */
1267 switch (map->map_type) {
1268 case BPF_MAP_TYPE_PROG_ARRAY:
1269 if (func_id != BPF_FUNC_tail_call)
1272 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
1273 if (func_id != BPF_FUNC_perf_event_read &&
1274 func_id != BPF_FUNC_perf_event_output)
1277 case BPF_MAP_TYPE_STACK_TRACE:
1278 if (func_id != BPF_FUNC_get_stackid)
1281 case BPF_MAP_TYPE_CGROUP_ARRAY:
1282 if (func_id != BPF_FUNC_skb_under_cgroup &&
1283 func_id != BPF_FUNC_current_task_under_cgroup)
1286 /* devmap returns a pointer to a live net_device ifindex that we cannot
1287 * allow to be modified from bpf side. So do not allow lookup elements
1290 case BPF_MAP_TYPE_DEVMAP:
1291 if (func_id != BPF_FUNC_redirect_map)
1294 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
1295 case BPF_MAP_TYPE_HASH_OF_MAPS:
1296 if (func_id != BPF_FUNC_map_lookup_elem)
1302 /* ... and second from the function itself. */
1304 case BPF_FUNC_tail_call:
1305 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
1308 case BPF_FUNC_perf_event_read:
1309 case BPF_FUNC_perf_event_output:
1310 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
1313 case BPF_FUNC_get_stackid:
1314 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
1317 case BPF_FUNC_current_task_under_cgroup:
1318 case BPF_FUNC_skb_under_cgroup:
1319 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
1322 case BPF_FUNC_redirect_map:
1323 if (map->map_type != BPF_MAP_TYPE_DEVMAP)
1332 verbose("cannot pass map_type %d into func %s#%d\n",
1333 map->map_type, func_id_name(func_id), func_id);
1337 static int check_raw_mode(const struct bpf_func_proto *fn)
1341 if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
1343 if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
1345 if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
1347 if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
1349 if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
1352 return count > 1 ? -EINVAL : 0;
1355 static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
1357 struct bpf_verifier_state *state = &env->cur_state;
1358 struct bpf_reg_state *regs = state->regs, *reg;
1361 for (i = 0; i < MAX_BPF_REG; i++)
1362 if (regs[i].type == PTR_TO_PACKET ||
1363 regs[i].type == PTR_TO_PACKET_END)
1364 mark_reg_unknown_value(regs, i);
1366 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1367 if (state->stack_slot_type[i] != STACK_SPILL)
1369 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1370 if (reg->type != PTR_TO_PACKET &&
1371 reg->type != PTR_TO_PACKET_END)
1373 __mark_reg_unknown_value(state->spilled_regs,
1378 static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
1380 struct bpf_verifier_state *state = &env->cur_state;
1381 const struct bpf_func_proto *fn = NULL;
1382 struct bpf_reg_state *regs = state->regs;
1383 struct bpf_call_arg_meta meta;
1387 /* find function prototype */
1388 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
1389 verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
1393 if (env->prog->aux->ops->get_func_proto)
1394 fn = env->prog->aux->ops->get_func_proto(func_id);
1397 verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
1401 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1402 if (!env->prog->gpl_compatible && fn->gpl_only) {
1403 verbose("cannot call GPL only function from proprietary program\n");
1407 changes_data = bpf_helper_changes_pkt_data(fn->func);
1409 memset(&meta, 0, sizeof(meta));
1410 meta.pkt_access = fn->pkt_access;
1412 /* We only support one arg being in raw mode at the moment, which
1413 * is sufficient for the helper functions we have right now.
1415 err = check_raw_mode(fn);
1417 verbose("kernel subsystem misconfigured func %s#%d\n",
1418 func_id_name(func_id), func_id);
1423 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
1426 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
1429 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
1432 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
1435 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
1439 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1440 * is inferred from register state.
1442 for (i = 0; i < meta.access_size; i++) {
1443 err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1);
1448 /* reset caller saved regs */
1449 for (i = 0; i < CALLER_SAVED_REGS; i++)
1450 mark_reg_not_init(regs, caller_saved[i]);
1452 /* update return register */
1453 if (fn->ret_type == RET_INTEGER) {
1454 regs[BPF_REG_0].type = UNKNOWN_VALUE;
1455 } else if (fn->ret_type == RET_VOID) {
1456 regs[BPF_REG_0].type = NOT_INIT;
1457 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
1458 struct bpf_insn_aux_data *insn_aux;
1460 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
1461 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0;
1462 /* remember map_ptr, so that check_map_access()
1463 * can check 'value_size' boundary of memory access
1464 * to map element returned from bpf_map_lookup_elem()
1466 if (meta.map_ptr == NULL) {
1467 verbose("kernel subsystem misconfigured verifier\n");
1470 regs[BPF_REG_0].map_ptr = meta.map_ptr;
1471 regs[BPF_REG_0].id = ++env->id_gen;
1472 insn_aux = &env->insn_aux_data[insn_idx];
1473 if (!insn_aux->map_ptr)
1474 insn_aux->map_ptr = meta.map_ptr;
1475 else if (insn_aux->map_ptr != meta.map_ptr)
1476 insn_aux->map_ptr = BPF_MAP_PTR_POISON;
1478 verbose("unknown return type %d of func %s#%d\n",
1479 fn->ret_type, func_id_name(func_id), func_id);
1483 err = check_map_func_compatibility(meta.map_ptr, func_id);
1488 clear_all_pkt_pointers(env);
1492 static int check_packet_ptr_add(struct bpf_verifier_env *env,
1493 struct bpf_insn *insn)
1495 struct bpf_reg_state *regs = env->cur_state.regs;
1496 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1497 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1498 struct bpf_reg_state tmp_reg;
1501 if (BPF_SRC(insn->code) == BPF_K) {
1502 /* pkt_ptr += imm */
1507 verbose("addition of negative constant to packet pointer is not allowed\n");
1510 if (imm >= MAX_PACKET_OFF ||
1511 imm + dst_reg->off >= MAX_PACKET_OFF) {
1512 verbose("constant %d is too large to add to packet pointer\n",
1516 /* a constant was added to pkt_ptr.
1517 * Remember it while keeping the same 'id'
1519 dst_reg->off += imm;
1523 if (src_reg->type == PTR_TO_PACKET) {
1524 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1525 tmp_reg = *dst_reg; /* save r7 state */
1526 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
1527 src_reg = &tmp_reg; /* pretend it's src_reg state */
1528 /* if the checks below reject it, the copy won't matter,
1529 * since we're rejecting the whole program. If all ok,
1530 * then imm22 state will be added to r7
1531 * and r7 will be pkt(id=0,off=22,r=62) while
1532 * r6 will stay as pkt(id=0,off=0,r=62)
1536 if (src_reg->type == CONST_IMM) {
1537 /* pkt_ptr += reg where reg is known constant */
1541 /* disallow pkt_ptr += reg
1542 * if reg is not uknown_value with guaranteed zero upper bits
1543 * otherwise pkt_ptr may overflow and addition will become
1544 * subtraction which is not allowed
1546 if (src_reg->type != UNKNOWN_VALUE) {
1547 verbose("cannot add '%s' to ptr_to_packet\n",
1548 reg_type_str[src_reg->type]);
1551 if (src_reg->imm < 48) {
1552 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1557 had_id = (dst_reg->id != 0);
1559 /* dst_reg stays as pkt_ptr type and since some positive
1560 * integer value was added to the pointer, increment its 'id'
1562 dst_reg->id = ++env->id_gen;
1564 /* something was added to pkt_ptr, set range to zero */
1565 dst_reg->aux_off += dst_reg->off;
1569 dst_reg->aux_off_align = min(dst_reg->aux_off_align,
1570 src_reg->min_align);
1572 dst_reg->aux_off_align = src_reg->min_align;
1577 static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
1579 struct bpf_reg_state *regs = env->cur_state.regs;
1580 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1581 u8 opcode = BPF_OP(insn->code);
1584 /* for type == UNKNOWN_VALUE:
1585 * imm > 0 -> number of zero upper bits
1586 * imm == 0 -> don't track which is the same as all bits can be non-zero
1589 if (BPF_SRC(insn->code) == BPF_X) {
1590 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1592 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 &&
1593 dst_reg->imm && opcode == BPF_ADD) {
1595 * where both have zero upper bits. Adding them
1596 * can only result making one more bit non-zero
1597 * in the larger value.
1598 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1599 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1601 dst_reg->imm = min(dst_reg->imm, src_reg->imm);
1605 if (src_reg->type == CONST_IMM && src_reg->imm > 0 &&
1606 dst_reg->imm && opcode == BPF_ADD) {
1608 * where dreg has zero upper bits and sreg is const.
1609 * Adding them can only result making one more bit
1610 * non-zero in the larger value.
1612 imm_log2 = __ilog2_u64((long long)src_reg->imm);
1613 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1617 /* all other cases non supported yet, just mark dst_reg */
1622 /* sign extend 32-bit imm into 64-bit to make sure that
1623 * negative values occupy bit 63. Note ilog2() would have
1624 * been incorrect, since sizeof(insn->imm) == 4
1626 imm_log2 = __ilog2_u64((long long)insn->imm);
1628 if (dst_reg->imm && opcode == BPF_LSH) {
1630 * if reg was a result of 2 byte load, then its imm == 48
1631 * which means that upper 48 bits are zero and shifting this reg
1632 * left by 4 would mean that upper 44 bits are still zero
1634 dst_reg->imm -= insn->imm;
1635 } else if (dst_reg->imm && opcode == BPF_MUL) {
1637 * if multiplying by 14 subtract 4
1638 * This is conservative calculation of upper zero bits.
1639 * It's not trying to special case insn->imm == 1 or 0 cases
1641 dst_reg->imm -= imm_log2 + 1;
1642 } else if (opcode == BPF_AND) {
1644 dst_reg->imm = 63 - imm_log2;
1645 } else if (dst_reg->imm && opcode == BPF_ADD) {
1647 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1649 } else if (opcode == BPF_RSH) {
1651 * which means that after right shift, upper bits will be zero
1652 * note that verifier already checked that
1653 * 0 <= imm < 64 for shift insn
1655 dst_reg->imm += insn->imm;
1656 if (unlikely(dst_reg->imm > 64))
1657 /* some dumb code did:
1660 * and all bits are zero now */
1663 /* all other alu ops, means that we don't know what will
1664 * happen to the value, mark it with unknown number of zero bits
1669 if (dst_reg->imm < 0) {
1670 /* all 64 bits of the register can contain non-zero bits
1671 * and such value cannot be added to ptr_to_packet, since it
1672 * may overflow, mark it as unknown to avoid further eval
1679 static int evaluate_reg_imm_alu_unknown(struct bpf_verifier_env *env,
1680 struct bpf_insn *insn)
1682 struct bpf_reg_state *regs = env->cur_state.regs;
1683 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1684 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1685 u8 opcode = BPF_OP(insn->code);
1686 s64 imm_log2 = __ilog2_u64((long long)dst_reg->imm);
1688 /* BPF_X code with src_reg->type UNKNOWN_VALUE here. */
1689 if (src_reg->imm > 0 && dst_reg->imm) {
1693 * where both have zero upper bits. Adding them
1694 * can only result making one more bit non-zero
1695 * in the larger value.
1696 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1697 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1699 dst_reg->imm = min(src_reg->imm, 63 - imm_log2);
1704 * AND can not extend zero bits only shrink
1705 * Ex. 0x00..00ffffff
1710 dst_reg->imm = max(src_reg->imm, 63 - imm_log2);
1714 * OR can only extend zero bits
1715 * Ex. 0x00..00ffffff
1720 dst_reg->imm = min(src_reg->imm, 63 - imm_log2);
1726 /* These may be flushed out later */
1728 mark_reg_unknown_value(regs, insn->dst_reg);
1731 mark_reg_unknown_value(regs, insn->dst_reg);
1734 dst_reg->type = UNKNOWN_VALUE;
1738 static int evaluate_reg_imm_alu(struct bpf_verifier_env *env,
1739 struct bpf_insn *insn)
1741 struct bpf_reg_state *regs = env->cur_state.regs;
1742 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1743 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1744 u8 opcode = BPF_OP(insn->code);
1745 u64 dst_imm = dst_reg->imm;
1747 if (BPF_SRC(insn->code) == BPF_X && src_reg->type == UNKNOWN_VALUE)
1748 return evaluate_reg_imm_alu_unknown(env, insn);
1750 /* dst_reg->type == CONST_IMM here. Simulate execution of insns
1751 * containing ALU ops. Don't care about overflow or negative
1752 * values, just add/sub/... them; registers are in u64.
1754 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) {
1755 dst_imm += insn->imm;
1756 } else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X &&
1757 src_reg->type == CONST_IMM) {
1758 dst_imm += src_reg->imm;
1759 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) {
1760 dst_imm -= insn->imm;
1761 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X &&
1762 src_reg->type == CONST_IMM) {
1763 dst_imm -= src_reg->imm;
1764 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) {
1765 dst_imm *= insn->imm;
1766 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X &&
1767 src_reg->type == CONST_IMM) {
1768 dst_imm *= src_reg->imm;
1769 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) {
1770 dst_imm |= insn->imm;
1771 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X &&
1772 src_reg->type == CONST_IMM) {
1773 dst_imm |= src_reg->imm;
1774 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) {
1775 dst_imm &= insn->imm;
1776 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X &&
1777 src_reg->type == CONST_IMM) {
1778 dst_imm &= src_reg->imm;
1779 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) {
1780 dst_imm >>= insn->imm;
1781 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X &&
1782 src_reg->type == CONST_IMM) {
1783 dst_imm >>= src_reg->imm;
1784 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) {
1785 dst_imm <<= insn->imm;
1786 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X &&
1787 src_reg->type == CONST_IMM) {
1788 dst_imm <<= src_reg->imm;
1790 mark_reg_unknown_value(regs, insn->dst_reg);
1794 dst_reg->imm = dst_imm;
1799 static void check_reg_overflow(struct bpf_reg_state *reg)
1801 if (reg->max_value > BPF_REGISTER_MAX_RANGE)
1802 reg->max_value = BPF_REGISTER_MAX_RANGE;
1803 if (reg->min_value < BPF_REGISTER_MIN_RANGE ||
1804 reg->min_value > BPF_REGISTER_MAX_RANGE)
1805 reg->min_value = BPF_REGISTER_MIN_RANGE;
1808 static u32 calc_align(u32 imm)
1812 return imm - ((imm - 1) & imm);
1815 static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
1816 struct bpf_insn *insn)
1818 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1819 s64 min_val = BPF_REGISTER_MIN_RANGE;
1820 u64 max_val = BPF_REGISTER_MAX_RANGE;
1821 u8 opcode = BPF_OP(insn->code);
1822 u32 dst_align, src_align;
1824 dst_reg = ®s[insn->dst_reg];
1826 if (BPF_SRC(insn->code) == BPF_X) {
1827 check_reg_overflow(®s[insn->src_reg]);
1828 min_val = regs[insn->src_reg].min_value;
1829 max_val = regs[insn->src_reg].max_value;
1831 /* If the source register is a random pointer then the
1832 * min_value/max_value values represent the range of the known
1833 * accesses into that value, not the actual min/max value of the
1834 * register itself. In this case we have to reset the reg range
1835 * values so we know it is not safe to look at.
1837 if (regs[insn->src_reg].type != CONST_IMM &&
1838 regs[insn->src_reg].type != UNKNOWN_VALUE) {
1839 min_val = BPF_REGISTER_MIN_RANGE;
1840 max_val = BPF_REGISTER_MAX_RANGE;
1843 src_align = regs[insn->src_reg].min_align;
1845 } else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
1846 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
1847 min_val = max_val = insn->imm;
1848 src_align = calc_align(insn->imm);
1851 dst_align = dst_reg->min_align;
1853 /* We don't know anything about what was done to this register, mark it
1854 * as unknown. Also, if both derived bounds came from signed/unsigned
1855 * mixed compares and one side is unbounded, we cannot really do anything
1856 * with them as boundaries cannot be trusted. Thus, arithmetic of two
1857 * regs of such kind will get invalidated bounds on the dst side.
1859 if ((min_val == BPF_REGISTER_MIN_RANGE &&
1860 max_val == BPF_REGISTER_MAX_RANGE) ||
1861 (BPF_SRC(insn->code) == BPF_X &&
1862 ((min_val != BPF_REGISTER_MIN_RANGE &&
1863 max_val == BPF_REGISTER_MAX_RANGE) ||
1864 (min_val == BPF_REGISTER_MIN_RANGE &&
1865 max_val != BPF_REGISTER_MAX_RANGE) ||
1866 (dst_reg->min_value != BPF_REGISTER_MIN_RANGE &&
1867 dst_reg->max_value == BPF_REGISTER_MAX_RANGE) ||
1868 (dst_reg->min_value == BPF_REGISTER_MIN_RANGE &&
1869 dst_reg->max_value != BPF_REGISTER_MAX_RANGE)) &&
1870 regs[insn->dst_reg].value_from_signed !=
1871 regs[insn->src_reg].value_from_signed)) {
1872 reset_reg_range_values(regs, insn->dst_reg);
1876 /* If one of our values was at the end of our ranges then we can't just
1877 * do our normal operations to the register, we need to set the values
1878 * to the min/max since they are undefined.
1880 if (opcode != BPF_SUB) {
1881 if (min_val == BPF_REGISTER_MIN_RANGE)
1882 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1883 if (max_val == BPF_REGISTER_MAX_RANGE)
1884 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1889 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1890 dst_reg->min_value += min_val;
1891 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1892 dst_reg->max_value += max_val;
1893 dst_reg->min_align = min(src_align, dst_align);
1896 /* If one of our values was at the end of our ranges, then the
1897 * _opposite_ value in the dst_reg goes to the end of our range.
1899 if (min_val == BPF_REGISTER_MIN_RANGE)
1900 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1901 if (max_val == BPF_REGISTER_MAX_RANGE)
1902 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1903 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1904 dst_reg->min_value -= max_val;
1905 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1906 dst_reg->max_value -= min_val;
1907 dst_reg->min_align = min(src_align, dst_align);
1910 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1911 dst_reg->min_value *= min_val;
1912 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1913 dst_reg->max_value *= max_val;
1914 dst_reg->min_align = max(src_align, dst_align);
1917 /* Disallow AND'ing of negative numbers, ain't nobody got time
1918 * for that. Otherwise the minimum is 0 and the max is the max
1919 * value we could AND against.
1922 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1924 dst_reg->min_value = 0;
1925 dst_reg->max_value = max_val;
1926 dst_reg->min_align = max(src_align, dst_align);
1929 /* Gotta have special overflow logic here, if we're shifting
1930 * more than MAX_RANGE then just assume we have an invalid
1933 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) {
1934 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1935 dst_reg->min_align = 1;
1937 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1938 dst_reg->min_value <<= min_val;
1939 if (!dst_reg->min_align)
1940 dst_reg->min_align = 1;
1941 dst_reg->min_align <<= min_val;
1943 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE))
1944 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1945 else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1946 dst_reg->max_value <<= max_val;
1949 /* RSH by a negative number is undefined, and the BPF_RSH is an
1950 * unsigned shift, so make the appropriate casts.
1952 if (min_val < 0 || dst_reg->min_value < 0) {
1953 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1955 dst_reg->min_value =
1956 (u64)(dst_reg->min_value) >> min_val;
1959 dst_reg->min_align = 1;
1961 dst_reg->min_align >>= (u64) min_val;
1962 if (!dst_reg->min_align)
1963 dst_reg->min_align = 1;
1965 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1966 dst_reg->max_value >>= max_val;
1969 reset_reg_range_values(regs, insn->dst_reg);
1973 check_reg_overflow(dst_reg);
1976 /* check validity of 32-bit and 64-bit arithmetic operations */
1977 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
1979 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1980 u8 opcode = BPF_OP(insn->code);
1983 if (opcode == BPF_END || opcode == BPF_NEG) {
1984 if (opcode == BPF_NEG) {
1985 if (BPF_SRC(insn->code) != 0 ||
1986 insn->src_reg != BPF_REG_0 ||
1987 insn->off != 0 || insn->imm != 0) {
1988 verbose("BPF_NEG uses reserved fields\n");
1992 if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
1993 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
1994 verbose("BPF_END uses reserved fields\n");
1999 /* check src operand */
2000 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2004 if (is_pointer_value(env, insn->dst_reg)) {
2005 verbose("R%d pointer arithmetic prohibited\n",
2010 /* check dest operand */
2011 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2015 } else if (opcode == BPF_MOV) {
2017 if (BPF_SRC(insn->code) == BPF_X) {
2018 if (insn->imm != 0 || insn->off != 0) {
2019 verbose("BPF_MOV uses reserved fields\n");
2023 /* check src operand */
2024 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2028 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
2029 verbose("BPF_MOV uses reserved fields\n");
2034 /* check dest operand */
2035 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2039 /* we are setting our register to something new, we need to
2040 * reset its range values.
2042 reset_reg_range_values(regs, insn->dst_reg);
2044 if (BPF_SRC(insn->code) == BPF_X) {
2045 if (BPF_CLASS(insn->code) == BPF_ALU64) {
2047 * copy register state to dest reg
2049 regs[insn->dst_reg] = regs[insn->src_reg];
2051 if (is_pointer_value(env, insn->src_reg)) {
2052 verbose("R%d partial copy of pointer\n",
2056 mark_reg_unknown_value(regs, insn->dst_reg);
2060 * remember the value we stored into this reg
2062 regs[insn->dst_reg].type = CONST_IMM;
2063 regs[insn->dst_reg].imm = insn->imm;
2064 regs[insn->dst_reg].id = 0;
2065 regs[insn->dst_reg].max_value = insn->imm;
2066 regs[insn->dst_reg].min_value = insn->imm;
2067 regs[insn->dst_reg].min_align = calc_align(insn->imm);
2068 regs[insn->dst_reg].value_from_signed = false;
2071 } else if (opcode > BPF_END) {
2072 verbose("invalid BPF_ALU opcode %x\n", opcode);
2075 } else { /* all other ALU ops: and, sub, xor, add, ... */
2077 if (BPF_SRC(insn->code) == BPF_X) {
2078 if (insn->imm != 0 || insn->off != 0) {
2079 verbose("BPF_ALU uses reserved fields\n");
2082 /* check src1 operand */
2083 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2087 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
2088 verbose("BPF_ALU uses reserved fields\n");
2093 /* check src2 operand */
2094 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2098 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
2099 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
2100 verbose("div by zero\n");
2104 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
2105 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
2106 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
2108 if (insn->imm < 0 || insn->imm >= size) {
2109 verbose("invalid shift %d\n", insn->imm);
2114 /* check dest operand */
2115 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
2119 dst_reg = ®s[insn->dst_reg];
2121 /* first we want to adjust our ranges. */
2122 adjust_reg_min_max_vals(env, insn);
2124 /* pattern match 'bpf_add Rx, imm' instruction */
2125 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
2126 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) {
2127 dst_reg->type = PTR_TO_STACK;
2128 dst_reg->imm = insn->imm;
2130 } else if (opcode == BPF_ADD &&
2131 BPF_CLASS(insn->code) == BPF_ALU64 &&
2132 dst_reg->type == PTR_TO_STACK &&
2133 ((BPF_SRC(insn->code) == BPF_X &&
2134 regs[insn->src_reg].type == CONST_IMM) ||
2135 BPF_SRC(insn->code) == BPF_K)) {
2136 if (BPF_SRC(insn->code) == BPF_X)
2137 dst_reg->imm += regs[insn->src_reg].imm;
2139 dst_reg->imm += insn->imm;
2141 } else if (opcode == BPF_ADD &&
2142 BPF_CLASS(insn->code) == BPF_ALU64 &&
2143 (dst_reg->type == PTR_TO_PACKET ||
2144 (BPF_SRC(insn->code) == BPF_X &&
2145 regs[insn->src_reg].type == PTR_TO_PACKET))) {
2146 /* ptr_to_packet += K|X */
2147 return check_packet_ptr_add(env, insn);
2148 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
2149 dst_reg->type == UNKNOWN_VALUE &&
2150 env->allow_ptr_leaks) {
2151 /* unknown += K|X */
2152 return evaluate_reg_alu(env, insn);
2153 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
2154 dst_reg->type == CONST_IMM &&
2155 env->allow_ptr_leaks) {
2156 /* reg_imm += K|X */
2157 return evaluate_reg_imm_alu(env, insn);
2158 } else if (is_pointer_value(env, insn->dst_reg)) {
2159 verbose("R%d pointer arithmetic prohibited\n",
2162 } else if (BPF_SRC(insn->code) == BPF_X &&
2163 is_pointer_value(env, insn->src_reg)) {
2164 verbose("R%d pointer arithmetic prohibited\n",
2169 /* If we did pointer math on a map value then just set it to our
2170 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
2171 * loads to this register appropriately, otherwise just mark the
2172 * register as unknown.
2174 if (env->allow_ptr_leaks &&
2175 BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD &&
2176 (dst_reg->type == PTR_TO_MAP_VALUE ||
2177 dst_reg->type == PTR_TO_MAP_VALUE_ADJ))
2178 dst_reg->type = PTR_TO_MAP_VALUE_ADJ;
2180 mark_reg_unknown_value(regs, insn->dst_reg);
2186 static void find_good_pkt_pointers(struct bpf_verifier_state *state,
2187 struct bpf_reg_state *dst_reg)
2189 struct bpf_reg_state *regs = state->regs, *reg;
2192 /* LLVM can generate two kind of checks:
2198 * if (r2 > pkt_end) goto <handle exception>
2202 * r2 == dst_reg, pkt_end == src_reg
2203 * r2=pkt(id=n,off=8,r=0)
2204 * r3=pkt(id=n,off=0,r=0)
2210 * if (pkt_end >= r2) goto <access okay>
2211 * <handle exception>
2214 * pkt_end == dst_reg, r2 == src_reg
2215 * r2=pkt(id=n,off=8,r=0)
2216 * r3=pkt(id=n,off=0,r=0)
2218 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
2219 * so that range of bytes [r3, r3 + 8) is safe to access.
2222 for (i = 0; i < MAX_BPF_REG; i++)
2223 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id)
2224 /* keep the maximum range already checked */
2225 regs[i].range = max(regs[i].range, dst_reg->off);
2227 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
2228 if (state->stack_slot_type[i] != STACK_SPILL)
2230 reg = &state->spilled_regs[i / BPF_REG_SIZE];
2231 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id)
2232 reg->range = max(reg->range, dst_reg->off);
2236 /* Adjusts the register min/max values in the case that the dst_reg is the
2237 * variable register that we are working on, and src_reg is a constant or we're
2238 * simply doing a BPF_K check.
2240 static void reg_set_min_max(struct bpf_reg_state *true_reg,
2241 struct bpf_reg_state *false_reg, u64 val,
2244 bool value_from_signed = true;
2245 bool is_range = true;
2249 /* If this is false then we know nothing Jon Snow, but if it is
2250 * true then we know for sure.
2252 true_reg->max_value = true_reg->min_value = val;
2256 /* If this is true we know nothing Jon Snow, but if it is false
2257 * we know the value for sure;
2259 false_reg->max_value = false_reg->min_value = val;
2263 value_from_signed = false;
2266 if (true_reg->value_from_signed != value_from_signed)
2267 reset_reg_range_values(true_reg, 0);
2268 if (false_reg->value_from_signed != value_from_signed)
2269 reset_reg_range_values(false_reg, 0);
2270 if (opcode == BPF_JGT) {
2271 /* Unsigned comparison, the minimum value is 0. */
2272 false_reg->min_value = 0;
2274 /* If this is false then we know the maximum val is val,
2275 * otherwise we know the min val is val+1.
2277 false_reg->max_value = val;
2278 false_reg->value_from_signed = value_from_signed;
2279 true_reg->min_value = val + 1;
2280 true_reg->value_from_signed = value_from_signed;
2283 value_from_signed = false;
2286 if (true_reg->value_from_signed != value_from_signed)
2287 reset_reg_range_values(true_reg, 0);
2288 if (false_reg->value_from_signed != value_from_signed)
2289 reset_reg_range_values(false_reg, 0);
2290 if (opcode == BPF_JGE) {
2291 /* Unsigned comparison, the minimum value is 0. */
2292 false_reg->min_value = 0;
2294 /* If this is false then we know the maximum value is val - 1,
2295 * otherwise we know the mimimum value is val.
2297 false_reg->max_value = val - 1;
2298 false_reg->value_from_signed = value_from_signed;
2299 true_reg->min_value = val;
2300 true_reg->value_from_signed = value_from_signed;
2306 check_reg_overflow(false_reg);
2307 check_reg_overflow(true_reg);
2309 if (__is_pointer_value(false, false_reg))
2310 reset_reg_range_values(false_reg, 0);
2311 if (__is_pointer_value(false, true_reg))
2312 reset_reg_range_values(true_reg, 0);
2316 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
2317 * is the variable reg.
2319 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
2320 struct bpf_reg_state *false_reg, u64 val,
2323 bool value_from_signed = true;
2324 bool is_range = true;
2328 /* If this is false then we know nothing Jon Snow, but if it is
2329 * true then we know for sure.
2331 true_reg->max_value = true_reg->min_value = val;
2335 /* If this is true we know nothing Jon Snow, but if it is false
2336 * we know the value for sure;
2338 false_reg->max_value = false_reg->min_value = val;
2342 value_from_signed = false;
2345 if (true_reg->value_from_signed != value_from_signed)
2346 reset_reg_range_values(true_reg, 0);
2347 if (false_reg->value_from_signed != value_from_signed)
2348 reset_reg_range_values(false_reg, 0);
2349 if (opcode == BPF_JGT) {
2350 /* Unsigned comparison, the minimum value is 0. */
2351 true_reg->min_value = 0;
2354 * If this is false, then the val is <= the register, if it is
2355 * true the register <= to the val.
2357 false_reg->min_value = val;
2358 false_reg->value_from_signed = value_from_signed;
2359 true_reg->max_value = val - 1;
2360 true_reg->value_from_signed = value_from_signed;
2363 value_from_signed = false;
2366 if (true_reg->value_from_signed != value_from_signed)
2367 reset_reg_range_values(true_reg, 0);
2368 if (false_reg->value_from_signed != value_from_signed)
2369 reset_reg_range_values(false_reg, 0);
2370 if (opcode == BPF_JGE) {
2371 /* Unsigned comparison, the minimum value is 0. */
2372 true_reg->min_value = 0;
2374 /* If this is false then constant < register, if it is true then
2375 * the register < constant.
2377 false_reg->min_value = val + 1;
2378 false_reg->value_from_signed = value_from_signed;
2379 true_reg->max_value = val;
2380 true_reg->value_from_signed = value_from_signed;
2386 check_reg_overflow(false_reg);
2387 check_reg_overflow(true_reg);
2389 if (__is_pointer_value(false, false_reg))
2390 reset_reg_range_values(false_reg, 0);
2391 if (__is_pointer_value(false, true_reg))
2392 reset_reg_range_values(true_reg, 0);
2396 static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
2397 enum bpf_reg_type type)
2399 struct bpf_reg_state *reg = ®s[regno];
2401 if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
2402 if (type == UNKNOWN_VALUE) {
2403 __mark_reg_unknown_value(regs, regno);
2404 } else if (reg->map_ptr->inner_map_meta) {
2405 reg->type = CONST_PTR_TO_MAP;
2406 reg->map_ptr = reg->map_ptr->inner_map_meta;
2410 /* We don't need id from this point onwards anymore, thus we
2411 * should better reset it, so that state pruning has chances
2418 /* The logic is similar to find_good_pkt_pointers(), both could eventually
2419 * be folded together at some point.
2421 static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
2422 enum bpf_reg_type type)
2424 struct bpf_reg_state *regs = state->regs;
2425 u32 id = regs[regno].id;
2428 for (i = 0; i < MAX_BPF_REG; i++)
2429 mark_map_reg(regs, i, id, type);
2431 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
2432 if (state->stack_slot_type[i] != STACK_SPILL)
2434 mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type);
2438 static int check_cond_jmp_op(struct bpf_verifier_env *env,
2439 struct bpf_insn *insn, int *insn_idx)
2441 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
2442 struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
2443 u8 opcode = BPF_OP(insn->code);
2446 if (opcode > BPF_EXIT) {
2447 verbose("invalid BPF_JMP opcode %x\n", opcode);
2451 if (BPF_SRC(insn->code) == BPF_X) {
2452 if (insn->imm != 0) {
2453 verbose("BPF_JMP uses reserved fields\n");
2457 /* check src1 operand */
2458 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2462 if (is_pointer_value(env, insn->src_reg)) {
2463 verbose("R%d pointer comparison prohibited\n",
2468 if (insn->src_reg != BPF_REG_0) {
2469 verbose("BPF_JMP uses reserved fields\n");
2474 /* check src2 operand */
2475 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2479 dst_reg = ®s[insn->dst_reg];
2481 /* detect if R == 0 where R was initialized to zero earlier */
2482 if (BPF_SRC(insn->code) == BPF_K &&
2483 (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2484 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) {
2485 if (opcode == BPF_JEQ) {
2486 /* if (imm == imm) goto pc+off;
2487 * only follow the goto, ignore fall-through
2489 *insn_idx += insn->off;
2492 /* if (imm != imm) goto pc+off;
2493 * only follow fall-through branch, since
2494 * that's where the program will go
2500 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
2504 /* detect if we are comparing against a constant value so we can adjust
2505 * our min/max values for our dst register.
2507 if (BPF_SRC(insn->code) == BPF_X) {
2508 if (regs[insn->src_reg].type == CONST_IMM)
2509 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2510 dst_reg, regs[insn->src_reg].imm,
2512 else if (dst_reg->type == CONST_IMM)
2513 reg_set_min_max_inv(&other_branch->regs[insn->src_reg],
2514 ®s[insn->src_reg], dst_reg->imm,
2517 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2518 dst_reg, insn->imm, opcode);
2521 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
2522 if (BPF_SRC(insn->code) == BPF_K &&
2523 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2524 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
2525 /* Mark all identical map registers in each branch as either
2526 * safe or unknown depending R == 0 or R != 0 conditional.
2528 mark_map_regs(this_branch, insn->dst_reg,
2529 opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE);
2530 mark_map_regs(other_branch, insn->dst_reg,
2531 opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE);
2532 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
2533 dst_reg->type == PTR_TO_PACKET &&
2534 regs[insn->src_reg].type == PTR_TO_PACKET_END) {
2535 find_good_pkt_pointers(this_branch, dst_reg);
2536 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
2537 dst_reg->type == PTR_TO_PACKET_END &&
2538 regs[insn->src_reg].type == PTR_TO_PACKET) {
2539 find_good_pkt_pointers(other_branch, ®s[insn->src_reg]);
2540 } else if (is_pointer_value(env, insn->dst_reg)) {
2541 verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
2545 print_verifier_state(this_branch);
2549 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
2550 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
2552 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
2554 return (struct bpf_map *) (unsigned long) imm64;
2557 /* verify BPF_LD_IMM64 instruction */
2558 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
2560 struct bpf_reg_state *regs = env->cur_state.regs;
2563 if (BPF_SIZE(insn->code) != BPF_DW) {
2564 verbose("invalid BPF_LD_IMM insn\n");
2567 if (insn->off != 0) {
2568 verbose("BPF_LD_IMM64 uses reserved fields\n");
2572 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2576 if (insn->src_reg == 0) {
2577 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
2579 regs[insn->dst_reg].type = CONST_IMM;
2580 regs[insn->dst_reg].imm = imm;
2581 regs[insn->dst_reg].id = 0;
2585 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2586 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
2588 regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
2589 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
2593 static bool may_access_skb(enum bpf_prog_type type)
2596 case BPF_PROG_TYPE_SOCKET_FILTER:
2597 case BPF_PROG_TYPE_SCHED_CLS:
2598 case BPF_PROG_TYPE_SCHED_ACT:
2605 /* verify safety of LD_ABS|LD_IND instructions:
2606 * - they can only appear in the programs where ctx == skb
2607 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2608 * preserve R6-R9, and store return value into R0
2611 * ctx == skb == R6 == CTX
2614 * SRC == any register
2615 * IMM == 32-bit immediate
2618 * R0 - 8/16/32-bit skb data converted to cpu endianness
2620 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
2622 struct bpf_reg_state *regs = env->cur_state.regs;
2623 u8 mode = BPF_MODE(insn->code);
2626 if (!may_access_skb(env->prog->type)) {
2627 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
2631 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
2632 BPF_SIZE(insn->code) == BPF_DW ||
2633 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
2634 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
2638 /* check whether implicit source operand (register R6) is readable */
2639 err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
2643 if (regs[BPF_REG_6].type != PTR_TO_CTX) {
2644 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2648 if (mode == BPF_IND) {
2649 /* check explicit source operand */
2650 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2655 /* reset caller saved regs to unreadable */
2656 for (i = 0; i < CALLER_SAVED_REGS; i++)
2657 mark_reg_not_init(regs, caller_saved[i]);
2659 /* mark destination R0 register as readable, since it contains
2660 * the value fetched from the packet
2662 regs[BPF_REG_0].type = UNKNOWN_VALUE;
2666 /* non-recursive DFS pseudo code
2667 * 1 procedure DFS-iterative(G,v):
2668 * 2 label v as discovered
2669 * 3 let S be a stack
2671 * 5 while S is not empty
2673 * 7 if t is what we're looking for:
2675 * 9 for all edges e in G.adjacentEdges(t) do
2676 * 10 if edge e is already labelled
2677 * 11 continue with the next edge
2678 * 12 w <- G.adjacentVertex(t,e)
2679 * 13 if vertex w is not discovered and not explored
2680 * 14 label e as tree-edge
2681 * 15 label w as discovered
2684 * 18 else if vertex w is discovered
2685 * 19 label e as back-edge
2687 * 21 // vertex w is explored
2688 * 22 label e as forward- or cross-edge
2689 * 23 label t as explored
2694 * 0x11 - discovered and fall-through edge labelled
2695 * 0x12 - discovered and fall-through and branch edges labelled
2706 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
2708 static int *insn_stack; /* stack of insns to process */
2709 static int cur_stack; /* current stack index */
2710 static int *insn_state;
2712 /* t, w, e - match pseudo-code above:
2713 * t - index of current instruction
2714 * w - next instruction
2717 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
2719 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
2722 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
2725 if (w < 0 || w >= env->prog->len) {
2726 verbose("jump out of range from insn %d to %d\n", t, w);
2731 /* mark branch target for state pruning */
2732 env->explored_states[w] = STATE_LIST_MARK;
2734 if (insn_state[w] == 0) {
2736 insn_state[t] = DISCOVERED | e;
2737 insn_state[w] = DISCOVERED;
2738 if (cur_stack >= env->prog->len)
2740 insn_stack[cur_stack++] = w;
2742 } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
2743 verbose("back-edge from insn %d to %d\n", t, w);
2745 } else if (insn_state[w] == EXPLORED) {
2746 /* forward- or cross-edge */
2747 insn_state[t] = DISCOVERED | e;
2749 verbose("insn state internal bug\n");
2755 /* non-recursive depth-first-search to detect loops in BPF program
2756 * loop == back-edge in directed graph
2758 static int check_cfg(struct bpf_verifier_env *env)
2760 struct bpf_insn *insns = env->prog->insnsi;
2761 int insn_cnt = env->prog->len;
2765 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2769 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2775 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
2776 insn_stack[0] = 0; /* 0 is the first instruction */
2782 t = insn_stack[cur_stack - 1];
2784 if (BPF_CLASS(insns[t].code) == BPF_JMP) {
2785 u8 opcode = BPF_OP(insns[t].code);
2787 if (opcode == BPF_EXIT) {
2789 } else if (opcode == BPF_CALL) {
2790 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2795 if (t + 1 < insn_cnt)
2796 env->explored_states[t + 1] = STATE_LIST_MARK;
2797 } else if (opcode == BPF_JA) {
2798 if (BPF_SRC(insns[t].code) != BPF_K) {
2802 /* unconditional jump with single edge */
2803 ret = push_insn(t, t + insns[t].off + 1,
2809 /* tell verifier to check for equivalent states
2810 * after every call and jump
2812 if (t + 1 < insn_cnt)
2813 env->explored_states[t + 1] = STATE_LIST_MARK;
2815 /* conditional jump with two edges */
2816 env->explored_states[t] = STATE_LIST_MARK;
2817 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2823 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
2830 /* all other non-branch instructions with single
2833 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2841 insn_state[t] = EXPLORED;
2842 if (cur_stack-- <= 0) {
2843 verbose("pop stack internal bug\n");
2850 for (i = 0; i < insn_cnt; i++) {
2851 if (insn_state[i] != EXPLORED) {
2852 verbose("unreachable insn %d\n", i);
2857 ret = 0; /* cfg looks good */
2865 /* the following conditions reduce the number of explored insns
2866 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2868 static bool compare_ptrs_to_packet(struct bpf_verifier_env *env,
2869 struct bpf_reg_state *old,
2870 struct bpf_reg_state *cur)
2872 if (old->id != cur->id)
2875 /* old ptr_to_packet is more conservative, since it allows smaller
2877 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2878 * old(off=0,r=10) means that with range=10 the verifier proceeded
2879 * further and found no issues with the program. Now we're in the same
2880 * spot with cur(off=0,r=20), so we're safe too, since anything further
2881 * will only be looking at most 10 bytes after this pointer.
2883 if (old->off == cur->off && old->range < cur->range)
2886 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2887 * since both cannot be used for packet access and safe(old)
2888 * pointer has smaller off that could be used for further
2889 * 'if (ptr > data_end)' check
2891 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2892 * that we cannot access the packet.
2893 * The safe range is:
2894 * [ptr, ptr + range - off)
2895 * so whenever off >=range, it means no safe bytes from this pointer.
2896 * When comparing old->off <= cur->off, it means that older code
2897 * went with smaller offset and that offset was later
2898 * used to figure out the safe range after 'if (ptr > data_end)' check
2899 * Say, 'old' state was explored like:
2900 * ... R3(off=0, r=0)
2902 * ... now R4(off=20,r=0) <-- here
2903 * if (R4 > data_end)
2904 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2905 * ... the code further went all the way to bpf_exit.
2906 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2907 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2908 * goes further, such cur_R4 will give larger safe packet range after
2909 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2910 * so they will be good with r=30 and we can prune the search.
2912 if (!env->strict_alignment && old->off <= cur->off &&
2913 old->off >= old->range && cur->off >= cur->range)
2919 /* compare two verifier states
2921 * all states stored in state_list are known to be valid, since
2922 * verifier reached 'bpf_exit' instruction through them
2924 * this function is called when verifier exploring different branches of
2925 * execution popped from the state stack. If it sees an old state that has
2926 * more strict register state and more strict stack state then this execution
2927 * branch doesn't need to be explored further, since verifier already
2928 * concluded that more strict state leads to valid finish.
2930 * Therefore two states are equivalent if register state is more conservative
2931 * and explored stack state is more conservative than the current one.
2934 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2935 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2937 * In other words if current stack state (one being explored) has more
2938 * valid slots than old one that already passed validation, it means
2939 * the verifier can stop exploring and conclude that current state is valid too
2941 * Similarly with registers. If explored state has register type as invalid
2942 * whereas register type in current state is meaningful, it means that
2943 * the current state will reach 'bpf_exit' instruction safely
2945 static bool states_equal(struct bpf_verifier_env *env,
2946 struct bpf_verifier_state *old,
2947 struct bpf_verifier_state *cur)
2949 bool varlen_map_access = env->varlen_map_value_access;
2950 struct bpf_reg_state *rold, *rcur;
2953 for (i = 0; i < MAX_BPF_REG; i++) {
2954 rold = &old->regs[i];
2955 rcur = &cur->regs[i];
2957 if (memcmp(rold, rcur, sizeof(*rold)) == 0)
2960 /* If the ranges were not the same, but everything else was and
2961 * we didn't do a variable access into a map then we are a-ok.
2963 if (!varlen_map_access &&
2964 memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0)
2967 /* If we didn't map access then again we don't care about the
2968 * mismatched range values and it's ok if our old type was
2969 * UNKNOWN and we didn't go to a NOT_INIT'ed reg.
2971 if (rold->type == NOT_INIT ||
2972 (!varlen_map_access && rold->type == UNKNOWN_VALUE &&
2973 rcur->type != NOT_INIT))
2976 /* Don't care about the reg->id in this case. */
2977 if (rold->type == PTR_TO_MAP_VALUE_OR_NULL &&
2978 rcur->type == PTR_TO_MAP_VALUE_OR_NULL &&
2979 rold->map_ptr == rcur->map_ptr)
2982 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET &&
2983 compare_ptrs_to_packet(env, rold, rcur))
2989 for (i = 0; i < MAX_BPF_STACK; i++) {
2990 if (old->stack_slot_type[i] == STACK_INVALID)
2992 if (old->stack_slot_type[i] != cur->stack_slot_type[i])
2993 /* Ex: old explored (safe) state has STACK_SPILL in
2994 * this stack slot, but current has has STACK_MISC ->
2995 * this verifier states are not equivalent,
2996 * return false to continue verification of this path
2999 if (i % BPF_REG_SIZE)
3001 if (old->stack_slot_type[i] != STACK_SPILL)
3003 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
3004 &cur->spilled_regs[i / BPF_REG_SIZE],
3005 sizeof(old->spilled_regs[0])))
3006 /* when explored and current stack slot types are
3007 * the same, check that stored pointers types
3008 * are the same as well.
3009 * Ex: explored safe path could have stored
3010 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
3011 * but current path has stored:
3012 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
3013 * such verifier states are not equivalent.
3014 * return false to continue verification of this path
3023 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
3025 struct bpf_verifier_state_list *new_sl;
3026 struct bpf_verifier_state_list *sl;
3028 sl = env->explored_states[insn_idx];
3030 /* this 'insn_idx' instruction wasn't marked, so we will not
3031 * be doing state search here
3035 while (sl != STATE_LIST_MARK) {
3036 if (states_equal(env, &sl->state, &env->cur_state))
3037 /* reached equivalent register/stack state,
3044 /* there were no equivalent states, remember current one.
3045 * technically the current state is not proven to be safe yet,
3046 * but it will either reach bpf_exit (which means it's safe) or
3047 * it will be rejected. Since there are no loops, we won't be
3048 * seeing this 'insn_idx' instruction again on the way to bpf_exit
3050 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
3054 /* add new state to the head of linked list */
3055 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
3056 new_sl->next = env->explored_states[insn_idx];
3057 env->explored_states[insn_idx] = new_sl;
3061 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
3062 int insn_idx, int prev_insn_idx)
3064 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
3067 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
3070 static int do_check(struct bpf_verifier_env *env)
3072 struct bpf_verifier_state *state = &env->cur_state;
3073 struct bpf_insn *insns = env->prog->insnsi;
3074 struct bpf_reg_state *regs = state->regs;
3075 int insn_cnt = env->prog->len;
3076 int insn_idx, prev_insn_idx = 0;
3077 int insn_processed = 0;
3078 bool do_print_state = false;
3080 init_reg_state(regs);
3082 env->varlen_map_value_access = false;
3084 struct bpf_insn *insn;
3088 if (insn_idx >= insn_cnt) {
3089 verbose("invalid insn idx %d insn_cnt %d\n",
3090 insn_idx, insn_cnt);
3094 insn = &insns[insn_idx];
3095 class = BPF_CLASS(insn->code);
3097 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
3098 verbose("BPF program is too large. Processed %d insn\n",
3103 err = is_state_visited(env, insn_idx);
3107 /* found equivalent state, can prune the search */
3110 verbose("\nfrom %d to %d: safe\n",
3111 prev_insn_idx, insn_idx);
3113 verbose("%d: safe\n", insn_idx);
3115 goto process_bpf_exit;
3121 if (log_level > 1 || (log_level && do_print_state)) {
3123 verbose("%d:", insn_idx);
3125 verbose("\nfrom %d to %d:",
3126 prev_insn_idx, insn_idx);
3127 print_verifier_state(&env->cur_state);
3128 do_print_state = false;
3132 verbose("%d: ", insn_idx);
3133 print_bpf_insn(env, insn);
3136 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
3140 if (class == BPF_ALU || class == BPF_ALU64) {
3141 err = check_alu_op(env, insn);
3145 } else if (class == BPF_LDX) {
3146 enum bpf_reg_type *prev_src_type, src_reg_type;
3148 /* check for reserved fields is already done */
3150 /* check src operand */
3151 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
3155 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
3159 src_reg_type = regs[insn->src_reg].type;
3161 /* check that memory (src_reg + off) is readable,
3162 * the state of dst_reg will be updated by this func
3164 err = check_mem_access(env, insn_idx, insn->src_reg, insn->off,
3165 BPF_SIZE(insn->code), BPF_READ,
3170 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
3172 if (*prev_src_type == NOT_INIT) {
3174 * dst_reg = *(u32 *)(src_reg + off)
3175 * save type to validate intersecting paths
3177 *prev_src_type = src_reg_type;
3179 } else if (src_reg_type != *prev_src_type &&
3180 (src_reg_type == PTR_TO_CTX ||
3181 *prev_src_type == PTR_TO_CTX)) {
3182 /* ABuser program is trying to use the same insn
3183 * dst_reg = *(u32*) (src_reg + off)
3184 * with different pointer types:
3185 * src_reg == ctx in one branch and
3186 * src_reg == stack|map in some other branch.
3189 verbose("same insn cannot be used with different pointers\n");
3193 } else if (class == BPF_STX) {
3194 enum bpf_reg_type *prev_dst_type, dst_reg_type;
3196 if (BPF_MODE(insn->code) == BPF_XADD) {
3197 err = check_xadd(env, insn_idx, insn);
3204 /* check src1 operand */
3205 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
3208 /* check src2 operand */
3209 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
3213 dst_reg_type = regs[insn->dst_reg].type;
3215 /* check that memory (dst_reg + off) is writeable */
3216 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
3217 BPF_SIZE(insn->code), BPF_WRITE,
3222 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
3224 if (*prev_dst_type == NOT_INIT) {
3225 *prev_dst_type = dst_reg_type;
3226 } else if (dst_reg_type != *prev_dst_type &&
3227 (dst_reg_type == PTR_TO_CTX ||
3228 *prev_dst_type == PTR_TO_CTX)) {
3229 verbose("same insn cannot be used with different pointers\n");
3233 } else if (class == BPF_ST) {
3234 if (BPF_MODE(insn->code) != BPF_MEM ||
3235 insn->src_reg != BPF_REG_0) {
3236 verbose("BPF_ST uses reserved fields\n");
3239 /* check src operand */
3240 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
3244 /* check that memory (dst_reg + off) is writeable */
3245 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
3246 BPF_SIZE(insn->code), BPF_WRITE,
3251 } else if (class == BPF_JMP) {
3252 u8 opcode = BPF_OP(insn->code);
3254 if (opcode == BPF_CALL) {
3255 if (BPF_SRC(insn->code) != BPF_K ||
3257 insn->src_reg != BPF_REG_0 ||
3258 insn->dst_reg != BPF_REG_0) {
3259 verbose("BPF_CALL uses reserved fields\n");
3263 err = check_call(env, insn->imm, insn_idx);
3267 } else if (opcode == BPF_JA) {
3268 if (BPF_SRC(insn->code) != BPF_K ||
3270 insn->src_reg != BPF_REG_0 ||
3271 insn->dst_reg != BPF_REG_0) {
3272 verbose("BPF_JA uses reserved fields\n");
3276 insn_idx += insn->off + 1;
3279 } else if (opcode == BPF_EXIT) {
3280 if (BPF_SRC(insn->code) != BPF_K ||
3282 insn->src_reg != BPF_REG_0 ||
3283 insn->dst_reg != BPF_REG_0) {
3284 verbose("BPF_EXIT uses reserved fields\n");
3288 /* eBPF calling convetion is such that R0 is used
3289 * to return the value from eBPF program.
3290 * Make sure that it's readable at this time
3291 * of bpf_exit, which means that program wrote
3292 * something into it earlier
3294 err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
3298 if (is_pointer_value(env, BPF_REG_0)) {
3299 verbose("R0 leaks addr as return value\n");
3304 insn_idx = pop_stack(env, &prev_insn_idx);
3308 do_print_state = true;
3312 err = check_cond_jmp_op(env, insn, &insn_idx);
3316 } else if (class == BPF_LD) {
3317 u8 mode = BPF_MODE(insn->code);
3319 if (mode == BPF_ABS || mode == BPF_IND) {
3320 err = check_ld_abs(env, insn);
3324 } else if (mode == BPF_IMM) {
3325 err = check_ld_imm(env, insn);
3331 verbose("invalid BPF_LD mode\n");
3334 reset_reg_range_values(regs, insn->dst_reg);
3336 verbose("unknown insn class %d\n", class);
3343 verbose("processed %d insns, stack depth %d\n",
3344 insn_processed, env->prog->aux->stack_depth);
3348 static int check_map_prealloc(struct bpf_map *map)
3350 return (map->map_type != BPF_MAP_TYPE_HASH &&
3351 map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
3352 map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
3353 !(map->map_flags & BPF_F_NO_PREALLOC);
3356 static int check_map_prog_compatibility(struct bpf_map *map,
3357 struct bpf_prog *prog)
3360 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
3361 * preallocated hash maps, since doing memory allocation
3362 * in overflow_handler can crash depending on where nmi got
3365 if (prog->type == BPF_PROG_TYPE_PERF_EVENT) {
3366 if (!check_map_prealloc(map)) {
3367 verbose("perf_event programs can only use preallocated hash map\n");
3370 if (map->inner_map_meta &&
3371 !check_map_prealloc(map->inner_map_meta)) {
3372 verbose("perf_event programs can only use preallocated inner hash map\n");
3379 /* look for pseudo eBPF instructions that access map FDs and
3380 * replace them with actual map pointers
3382 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
3384 struct bpf_insn *insn = env->prog->insnsi;
3385 int insn_cnt = env->prog->len;
3388 err = bpf_prog_calc_tag(env->prog);
3392 for (i = 0; i < insn_cnt; i++, insn++) {
3393 if (BPF_CLASS(insn->code) == BPF_LDX &&
3394 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
3395 verbose("BPF_LDX uses reserved fields\n");
3399 if (BPF_CLASS(insn->code) == BPF_STX &&
3400 ((BPF_MODE(insn->code) != BPF_MEM &&
3401 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
3402 verbose("BPF_STX uses reserved fields\n");
3406 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
3407 struct bpf_map *map;
3410 if (i == insn_cnt - 1 || insn[1].code != 0 ||
3411 insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
3413 verbose("invalid bpf_ld_imm64 insn\n");
3417 if (insn->src_reg == 0)
3418 /* valid generic load 64-bit imm */
3421 if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
3422 verbose("unrecognized bpf_ld_imm64 insn\n");
3426 f = fdget(insn->imm);
3427 map = __bpf_map_get(f);
3429 verbose("fd %d is not pointing to valid bpf_map\n",
3431 return PTR_ERR(map);
3434 err = check_map_prog_compatibility(map, env->prog);
3440 /* store map pointer inside BPF_LD_IMM64 instruction */
3441 insn[0].imm = (u32) (unsigned long) map;
3442 insn[1].imm = ((u64) (unsigned long) map) >> 32;
3444 /* check whether we recorded this map already */
3445 for (j = 0; j < env->used_map_cnt; j++)
3446 if (env->used_maps[j] == map) {
3451 if (env->used_map_cnt >= MAX_USED_MAPS) {
3456 /* hold the map. If the program is rejected by verifier,
3457 * the map will be released by release_maps() or it
3458 * will be used by the valid program until it's unloaded
3459 * and all maps are released in free_bpf_prog_info()
3461 map = bpf_map_inc(map, false);
3464 return PTR_ERR(map);
3466 env->used_maps[env->used_map_cnt++] = map;
3475 /* now all pseudo BPF_LD_IMM64 instructions load valid
3476 * 'struct bpf_map *' into a register instead of user map_fd.
3477 * These pointers will be used later by verifier to validate map access.
3482 /* drop refcnt of maps used by the rejected program */
3483 static void release_maps(struct bpf_verifier_env *env)
3487 for (i = 0; i < env->used_map_cnt; i++)
3488 bpf_map_put(env->used_maps[i]);
3491 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
3492 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
3494 struct bpf_insn *insn = env->prog->insnsi;
3495 int insn_cnt = env->prog->len;
3498 for (i = 0; i < insn_cnt; i++, insn++)
3499 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
3503 /* single env->prog->insni[off] instruction was replaced with the range
3504 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
3505 * [0, off) and [off, end) to new locations, so the patched range stays zero
3507 static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
3510 struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
3514 new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len);
3517 memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
3518 memcpy(new_data + off + cnt - 1, old_data + off,
3519 sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
3520 env->insn_aux_data = new_data;
3525 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
3526 const struct bpf_insn *patch, u32 len)
3528 struct bpf_prog *new_prog;
3530 new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
3533 if (adjust_insn_aux_data(env, new_prog->len, off, len))
3538 /* convert load instructions that access fields of 'struct __sk_buff'
3539 * into sequence of instructions that access fields of 'struct sk_buff'
3541 static int convert_ctx_accesses(struct bpf_verifier_env *env)
3543 const struct bpf_verifier_ops *ops = env->prog->aux->ops;
3544 int i, cnt, size, ctx_field_size, delta = 0;
3545 const int insn_cnt = env->prog->len;
3546 struct bpf_insn insn_buf[16], *insn;
3547 struct bpf_prog *new_prog;
3548 enum bpf_access_type type;
3549 bool is_narrower_load;
3552 if (ops->gen_prologue) {
3553 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
3555 if (cnt >= ARRAY_SIZE(insn_buf)) {
3556 verbose("bpf verifier is misconfigured\n");
3559 new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
3563 env->prog = new_prog;
3568 if (!ops->convert_ctx_access)
3571 insn = env->prog->insnsi + delta;
3573 for (i = 0; i < insn_cnt; i++, insn++) {
3574 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
3575 insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
3576 insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
3577 insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
3579 else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
3580 insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
3581 insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
3582 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
3587 if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
3590 ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
3591 size = BPF_LDST_BYTES(insn);
3593 /* If the read access is a narrower load of the field,
3594 * convert to a 4/8-byte load, to minimum program type specific
3595 * convert_ctx_access changes. If conversion is successful,
3596 * we will apply proper mask to the result.
3598 is_narrower_load = size < ctx_field_size;
3599 if (is_narrower_load) {
3600 u32 off = insn->off;
3603 if (type == BPF_WRITE) {
3604 verbose("bpf verifier narrow ctx access misconfigured\n");
3609 if (ctx_field_size == 4)
3611 else if (ctx_field_size == 8)
3614 insn->off = off & ~(ctx_field_size - 1);
3615 insn->code = BPF_LDX | BPF_MEM | size_code;
3619 cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog,
3621 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
3622 (ctx_field_size && !target_size)) {
3623 verbose("bpf verifier is misconfigured\n");
3627 if (is_narrower_load && size < target_size) {
3628 if (ctx_field_size <= 4)
3629 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
3630 (1 << size * 8) - 1);
3632 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
3633 (1 << size * 8) - 1);
3636 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
3642 /* keep walking new program and skip insns we just inserted */
3643 env->prog = new_prog;
3644 insn = new_prog->insnsi + i + delta;
3650 /* fixup insn->imm field of bpf_call instructions
3651 * and inline eligible helpers as explicit sequence of BPF instructions
3653 * this function is called after eBPF program passed verification
3655 static int fixup_bpf_calls(struct bpf_verifier_env *env)
3657 struct bpf_prog *prog = env->prog;
3658 struct bpf_insn *insn = prog->insnsi;
3659 const struct bpf_func_proto *fn;
3660 const int insn_cnt = prog->len;
3661 struct bpf_insn insn_buf[16];
3662 struct bpf_prog *new_prog;
3663 struct bpf_map *map_ptr;
3664 int i, cnt, delta = 0;
3666 for (i = 0; i < insn_cnt; i++, insn++) {
3667 if (insn->code != (BPF_JMP | BPF_CALL))
3670 if (insn->imm == BPF_FUNC_get_route_realm)
3671 prog->dst_needed = 1;
3672 if (insn->imm == BPF_FUNC_get_prandom_u32)
3673 bpf_user_rnd_init_once();
3674 if (insn->imm == BPF_FUNC_tail_call) {
3675 /* If we tail call into other programs, we
3676 * cannot make any assumptions since they can
3677 * be replaced dynamically during runtime in
3678 * the program array.
3680 prog->cb_access = 1;
3681 env->prog->aux->stack_depth = MAX_BPF_STACK;
3683 /* mark bpf_tail_call as different opcode to avoid
3684 * conditional branch in the interpeter for every normal
3685 * call and to prevent accidental JITing by JIT compiler
3686 * that doesn't support bpf_tail_call yet
3689 insn->code = BPF_JMP | BPF_TAIL_CALL;
3693 if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) {
3694 map_ptr = env->insn_aux_data[i + delta].map_ptr;
3695 if (map_ptr == BPF_MAP_PTR_POISON ||
3696 !map_ptr->ops->map_gen_lookup)
3697 goto patch_call_imm;
3699 cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf);
3700 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
3701 verbose("bpf verifier is misconfigured\n");
3705 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
3712 /* keep walking new program and skip insns we just inserted */
3713 env->prog = prog = new_prog;
3714 insn = new_prog->insnsi + i + delta;
3719 fn = prog->aux->ops->get_func_proto(insn->imm);
3720 /* all functions that have prototype and verifier allowed
3721 * programs to call them, must be real in-kernel functions
3724 verbose("kernel subsystem misconfigured func %s#%d\n",
3725 func_id_name(insn->imm), insn->imm);
3728 insn->imm = fn->func - __bpf_call_base;
3734 static void free_states(struct bpf_verifier_env *env)
3736 struct bpf_verifier_state_list *sl, *sln;
3739 if (!env->explored_states)
3742 for (i = 0; i < env->prog->len; i++) {
3743 sl = env->explored_states[i];
3746 while (sl != STATE_LIST_MARK) {
3753 kfree(env->explored_states);
3756 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
3758 char __user *log_ubuf = NULL;
3759 struct bpf_verifier_env *env;
3762 /* 'struct bpf_verifier_env' can be global, but since it's not small,
3763 * allocate/free it every time bpf_check() is called
3765 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3769 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3772 if (!env->insn_aux_data)
3776 /* grab the mutex to protect few globals used by verifier */
3777 mutex_lock(&bpf_verifier_lock);
3779 if (attr->log_level || attr->log_buf || attr->log_size) {
3780 /* user requested verbose verifier output
3781 * and supplied buffer to store the verification trace
3783 log_level = attr->log_level;
3784 log_ubuf = (char __user *) (unsigned long) attr->log_buf;
3785 log_size = attr->log_size;
3789 /* log_* values have to be sane */
3790 if (log_size < 128 || log_size > UINT_MAX >> 8 ||
3791 log_level == 0 || log_ubuf == NULL)
3795 log_buf = vmalloc(log_size);
3802 env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
3803 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
3804 env->strict_alignment = true;
3806 ret = replace_map_fd_with_map_ptr(env);
3808 goto skip_full_check;
3810 env->explored_states = kcalloc(env->prog->len,
3811 sizeof(struct bpf_verifier_state_list *),
3814 if (!env->explored_states)
3815 goto skip_full_check;
3817 ret = check_cfg(env);
3819 goto skip_full_check;
3821 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3823 ret = do_check(env);
3826 while (pop_stack(env, NULL) >= 0);
3830 /* program is valid, convert *(u32*)(ctx + off) accesses */
3831 ret = convert_ctx_accesses(env);
3834 ret = fixup_bpf_calls(env);
3836 if (log_level && log_len >= log_size - 1) {
3837 BUG_ON(log_len >= log_size);
3838 /* verifier log exceeded user supplied buffer */
3840 /* fall through to return what was recorded */
3843 /* copy verifier log back to user space including trailing zero */
3844 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
3849 if (ret == 0 && env->used_map_cnt) {
3850 /* if program passed verifier, update used_maps in bpf_prog_info */
3851 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
3852 sizeof(env->used_maps[0]),
3855 if (!env->prog->aux->used_maps) {
3860 memcpy(env->prog->aux->used_maps, env->used_maps,
3861 sizeof(env->used_maps[0]) * env->used_map_cnt);
3862 env->prog->aux->used_map_cnt = env->used_map_cnt;
3864 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3865 * bpf_ld_imm64 instructions
3867 convert_pseudo_ld_imm64(env);
3873 if (!env->prog->aux->used_maps)
3874 /* if we didn't copy map pointers into bpf_prog_info, release
3875 * them now. Otherwise free_bpf_prog_info() will release them.
3880 mutex_unlock(&bpf_verifier_lock);
3881 vfree(env->insn_aux_data);
3887 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
3890 struct bpf_verifier_env *env;
3893 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3897 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3900 if (!env->insn_aux_data)
3903 env->analyzer_ops = ops;
3904 env->analyzer_priv = priv;
3906 /* grab the mutex to protect few globals used by verifier */
3907 mutex_lock(&bpf_verifier_lock);
3911 env->strict_alignment = false;
3912 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
3913 env->strict_alignment = true;
3915 env->explored_states = kcalloc(env->prog->len,
3916 sizeof(struct bpf_verifier_state_list *),
3919 if (!env->explored_states)
3920 goto skip_full_check;
3922 ret = check_cfg(env);
3924 goto skip_full_check;
3926 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3928 ret = do_check(env);
3931 while (pop_stack(env, NULL) >= 0);
3934 mutex_unlock(&bpf_verifier_lock);
3935 vfree(env->insn_aux_data);
3940 EXPORT_SYMBOL_GPL(bpf_analyzer);