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>
26 static const struct bpf_verifier_ops
* const bpf_verifier_ops
[] = {
27 #define BPF_PROG_TYPE(_id, _name) \
28 [_id] = & _name ## _verifier_ops,
29 #define BPF_MAP_TYPE(_id, _ops)
30 #include <linux/bpf_types.h>
35 /* bpf_check() is a static code analyzer that walks eBPF program
36 * instruction by instruction and updates register/stack state.
37 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
39 * The first pass is depth-first-search to check that the program is a DAG.
40 * It rejects the following programs:
41 * - larger than BPF_MAXINSNS insns
42 * - if loop is present (detected via back-edge)
43 * - unreachable insns exist (shouldn't be a forest. program = one function)
44 * - out of bounds or malformed jumps
45 * The second pass is all possible path descent from the 1st insn.
46 * Since it's analyzing all pathes through the program, the length of the
47 * analysis is limited to 64k insn, which may be hit even if total number of
48 * insn is less then 4K, but there are too many branches that change stack/regs.
49 * Number of 'branches to be analyzed' is limited to 1k
51 * On entry to each instruction, each register has a type, and the instruction
52 * changes the types of the registers depending on instruction semantics.
53 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
56 * All registers are 64-bit.
57 * R0 - return register
58 * R1-R5 argument passing registers
59 * R6-R9 callee saved registers
60 * R10 - frame pointer read-only
62 * At the start of BPF program the register R1 contains a pointer to bpf_context
63 * and has type PTR_TO_CTX.
65 * Verifier tracks arithmetic operations on pointers in case:
66 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
67 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
68 * 1st insn copies R10 (which has FRAME_PTR) type into R1
69 * and 2nd arithmetic instruction is pattern matched to recognize
70 * that it wants to construct a pointer to some element within stack.
71 * So after 2nd insn, the register R1 has type PTR_TO_STACK
72 * (and -20 constant is saved for further stack bounds checking).
73 * Meaning that this reg is a pointer to stack plus known immediate constant.
75 * Most of the time the registers have SCALAR_VALUE type, which
76 * means the register has some value, but it's not a valid pointer.
77 * (like pointer plus pointer becomes SCALAR_VALUE type)
79 * When verifier sees load or store instructions the type of base register
80 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer
81 * types recognized by check_mem_access() function.
83 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
84 * and the range of [ptr, ptr + map's value_size) is accessible.
86 * registers used to pass values to function calls are checked against
87 * function argument constraints.
89 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
90 * It means that the register type passed to this function must be
91 * PTR_TO_STACK and it will be used inside the function as
92 * 'pointer to map element key'
94 * For example the argument constraints for bpf_map_lookup_elem():
95 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
96 * .arg1_type = ARG_CONST_MAP_PTR,
97 * .arg2_type = ARG_PTR_TO_MAP_KEY,
99 * ret_type says that this function returns 'pointer to map elem value or null'
100 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
101 * 2nd argument should be a pointer to stack, which will be used inside
102 * the helper function as a pointer to map element key.
104 * On the kernel side the helper function looks like:
105 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
107 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
108 * void *key = (void *) (unsigned long) r2;
111 * here kernel can access 'key' and 'map' pointers safely, knowing that
112 * [key, key + map->key_size) bytes are valid and were initialized on
113 * the stack of eBPF program.
116 * Corresponding eBPF program may look like:
117 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
118 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
119 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
120 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
121 * here verifier looks at prototype of map_lookup_elem() and sees:
122 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
123 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
125 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
126 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
127 * and were initialized prior to this call.
128 * If it's ok, then verifier allows this BPF_CALL insn and looks at
129 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
130 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
131 * returns ether pointer to map value or NULL.
133 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
134 * insn, the register holding that pointer in the true branch changes state to
135 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
136 * branch. See check_cond_jmp_op().
138 * After the call R0 is set to return type of the function and registers R1-R5
139 * are set to NOT_INIT to indicate that they are no longer readable.
142 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
143 struct bpf_verifier_stack_elem
{
144 /* verifer state is 'st'
145 * before processing instruction 'insn_idx'
146 * and after processing instruction 'prev_insn_idx'
148 struct bpf_verifier_state st
;
151 struct bpf_verifier_stack_elem
*next
;
154 #define BPF_COMPLEXITY_LIMIT_INSNS 131072
155 #define BPF_COMPLEXITY_LIMIT_STACK 1024
157 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
159 struct bpf_call_arg_meta
{
160 struct bpf_map
*map_ptr
;
167 static DEFINE_MUTEX(bpf_verifier_lock
);
169 /* log_level controls verbosity level of eBPF verifier.
170 * verbose() is used to dump the verification trace to the log, so the user
171 * can figure out what's wrong with the program
173 static __printf(2, 3) void verbose(struct bpf_verifier_env
*env
,
174 const char *fmt
, ...)
176 struct bpf_verifer_log
*log
= &env
->log
;
180 if (!log
->level
|| !log
->ubuf
|| bpf_verifier_log_full(log
))
184 n
= vscnprintf(log
->kbuf
, BPF_VERIFIER_TMP_LOG_SIZE
, fmt
, args
);
187 WARN_ONCE(n
>= BPF_VERIFIER_TMP_LOG_SIZE
- 1,
188 "verifier log line truncated - local buffer too short\n");
190 n
= min(log
->len_total
- log
->len_used
- 1, n
);
193 if (!copy_to_user(log
->ubuf
+ log
->len_used
, log
->kbuf
, n
+ 1))
199 static bool type_is_pkt_pointer(enum bpf_reg_type type
)
201 return type
== PTR_TO_PACKET
||
202 type
== PTR_TO_PACKET_META
;
205 /* string representation of 'enum bpf_reg_type' */
206 static const char * const reg_type_str
[] = {
208 [SCALAR_VALUE
] = "inv",
209 [PTR_TO_CTX
] = "ctx",
210 [CONST_PTR_TO_MAP
] = "map_ptr",
211 [PTR_TO_MAP_VALUE
] = "map_value",
212 [PTR_TO_MAP_VALUE_OR_NULL
] = "map_value_or_null",
213 [PTR_TO_STACK
] = "fp",
214 [PTR_TO_PACKET
] = "pkt",
215 [PTR_TO_PACKET_META
] = "pkt_meta",
216 [PTR_TO_PACKET_END
] = "pkt_end",
219 static void print_verifier_state(struct bpf_verifier_env
*env
,
220 struct bpf_verifier_state
*state
)
222 struct bpf_reg_state
*reg
;
226 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
227 reg
= &state
->regs
[i
];
231 verbose(env
, " R%d=%s", i
, reg_type_str
[t
]);
232 if ((t
== SCALAR_VALUE
|| t
== PTR_TO_STACK
) &&
233 tnum_is_const(reg
->var_off
)) {
234 /* reg->off should be 0 for SCALAR_VALUE */
235 verbose(env
, "%lld", reg
->var_off
.value
+ reg
->off
);
237 verbose(env
, "(id=%d", reg
->id
);
238 if (t
!= SCALAR_VALUE
)
239 verbose(env
, ",off=%d", reg
->off
);
240 if (type_is_pkt_pointer(t
))
241 verbose(env
, ",r=%d", reg
->range
);
242 else if (t
== CONST_PTR_TO_MAP
||
243 t
== PTR_TO_MAP_VALUE
||
244 t
== PTR_TO_MAP_VALUE_OR_NULL
)
245 verbose(env
, ",ks=%d,vs=%d",
246 reg
->map_ptr
->key_size
,
247 reg
->map_ptr
->value_size
);
248 if (tnum_is_const(reg
->var_off
)) {
249 /* Typically an immediate SCALAR_VALUE, but
250 * could be a pointer whose offset is too big
253 verbose(env
, ",imm=%llx", reg
->var_off
.value
);
255 if (reg
->smin_value
!= reg
->umin_value
&&
256 reg
->smin_value
!= S64_MIN
)
257 verbose(env
, ",smin_value=%lld",
258 (long long)reg
->smin_value
);
259 if (reg
->smax_value
!= reg
->umax_value
&&
260 reg
->smax_value
!= S64_MAX
)
261 verbose(env
, ",smax_value=%lld",
262 (long long)reg
->smax_value
);
263 if (reg
->umin_value
!= 0)
264 verbose(env
, ",umin_value=%llu",
265 (unsigned long long)reg
->umin_value
);
266 if (reg
->umax_value
!= U64_MAX
)
267 verbose(env
, ",umax_value=%llu",
268 (unsigned long long)reg
->umax_value
);
269 if (!tnum_is_unknown(reg
->var_off
)) {
272 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
273 verbose(env
, ",var_off=%s", tn_buf
);
279 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
280 if (state
->stack
[i
].slot_type
[0] == STACK_SPILL
)
281 verbose(env
, " fp%d=%s",
282 -MAX_BPF_STACK
+ i
* BPF_REG_SIZE
,
283 reg_type_str
[state
->stack
[i
].spilled_ptr
.type
]);
288 static int copy_stack_state(struct bpf_verifier_state
*dst
,
289 const struct bpf_verifier_state
*src
)
293 if (WARN_ON_ONCE(dst
->allocated_stack
< src
->allocated_stack
)) {
294 /* internal bug, make state invalid to reject the program */
295 memset(dst
, 0, sizeof(*dst
));
298 memcpy(dst
->stack
, src
->stack
,
299 sizeof(*src
->stack
) * (src
->allocated_stack
/ BPF_REG_SIZE
));
303 /* do_check() starts with zero-sized stack in struct bpf_verifier_state to
304 * make it consume minimal amount of memory. check_stack_write() access from
305 * the program calls into realloc_verifier_state() to grow the stack size.
306 * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
307 * which this function copies over. It points to previous bpf_verifier_state
308 * which is never reallocated
310 static int realloc_verifier_state(struct bpf_verifier_state
*state
, int size
,
313 u32 old_size
= state
->allocated_stack
;
314 struct bpf_stack_state
*new_stack
;
315 int slot
= size
/ BPF_REG_SIZE
;
317 if (size
<= old_size
|| !size
) {
320 state
->allocated_stack
= slot
* BPF_REG_SIZE
;
321 if (!size
&& old_size
) {
327 new_stack
= kmalloc_array(slot
, sizeof(struct bpf_stack_state
),
333 memcpy(new_stack
, state
->stack
,
334 sizeof(*new_stack
) * (old_size
/ BPF_REG_SIZE
));
335 memset(new_stack
+ old_size
/ BPF_REG_SIZE
, 0,
336 sizeof(*new_stack
) * (size
- old_size
) / BPF_REG_SIZE
);
338 state
->allocated_stack
= slot
* BPF_REG_SIZE
;
340 state
->stack
= new_stack
;
344 static void free_verifier_state(struct bpf_verifier_state
*state
,
352 /* copy verifier state from src to dst growing dst stack space
353 * when necessary to accommodate larger src stack
355 static int copy_verifier_state(struct bpf_verifier_state
*dst
,
356 const struct bpf_verifier_state
*src
)
360 err
= realloc_verifier_state(dst
, src
->allocated_stack
, false);
363 memcpy(dst
, src
, offsetof(struct bpf_verifier_state
, allocated_stack
));
364 return copy_stack_state(dst
, src
);
367 static int pop_stack(struct bpf_verifier_env
*env
, int *prev_insn_idx
,
370 struct bpf_verifier_state
*cur
= env
->cur_state
;
371 struct bpf_verifier_stack_elem
*elem
, *head
= env
->head
;
374 if (env
->head
== NULL
)
378 err
= copy_verifier_state(cur
, &head
->st
);
383 *insn_idx
= head
->insn_idx
;
385 *prev_insn_idx
= head
->prev_insn_idx
;
387 free_verifier_state(&head
->st
, false);
394 static struct bpf_verifier_state
*push_stack(struct bpf_verifier_env
*env
,
395 int insn_idx
, int prev_insn_idx
)
397 struct bpf_verifier_state
*cur
= env
->cur_state
;
398 struct bpf_verifier_stack_elem
*elem
;
401 elem
= kzalloc(sizeof(struct bpf_verifier_stack_elem
), GFP_KERNEL
);
405 elem
->insn_idx
= insn_idx
;
406 elem
->prev_insn_idx
= prev_insn_idx
;
407 elem
->next
= env
->head
;
410 err
= copy_verifier_state(&elem
->st
, cur
);
413 if (env
->stack_size
> BPF_COMPLEXITY_LIMIT_STACK
) {
414 verbose(env
, "BPF program is too complex\n");
419 /* pop all elements and return */
420 while (!pop_stack(env
, NULL
, NULL
));
424 #define CALLER_SAVED_REGS 6
425 static const int caller_saved
[CALLER_SAVED_REGS
] = {
426 BPF_REG_0
, BPF_REG_1
, BPF_REG_2
, BPF_REG_3
, BPF_REG_4
, BPF_REG_5
429 static void __mark_reg_not_init(struct bpf_reg_state
*reg
);
431 /* Mark the unknown part of a register (variable offset or scalar value) as
432 * known to have the value @imm.
434 static void __mark_reg_known(struct bpf_reg_state
*reg
, u64 imm
)
437 reg
->var_off
= tnum_const(imm
);
438 reg
->smin_value
= (s64
)imm
;
439 reg
->smax_value
= (s64
)imm
;
440 reg
->umin_value
= imm
;
441 reg
->umax_value
= imm
;
444 /* Mark the 'variable offset' part of a register as zero. This should be
445 * used only on registers holding a pointer type.
447 static void __mark_reg_known_zero(struct bpf_reg_state
*reg
)
449 __mark_reg_known(reg
, 0);
452 static void mark_reg_known_zero(struct bpf_verifier_env
*env
,
453 struct bpf_reg_state
*regs
, u32 regno
)
455 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
456 verbose(env
, "mark_reg_known_zero(regs, %u)\n", regno
);
457 /* Something bad happened, let's kill all regs */
458 for (regno
= 0; regno
< MAX_BPF_REG
; regno
++)
459 __mark_reg_not_init(regs
+ regno
);
462 __mark_reg_known_zero(regs
+ regno
);
465 static bool reg_is_pkt_pointer(const struct bpf_reg_state
*reg
)
467 return type_is_pkt_pointer(reg
->type
);
470 static bool reg_is_pkt_pointer_any(const struct bpf_reg_state
*reg
)
472 return reg_is_pkt_pointer(reg
) ||
473 reg
->type
== PTR_TO_PACKET_END
;
476 /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
477 static bool reg_is_init_pkt_pointer(const struct bpf_reg_state
*reg
,
478 enum bpf_reg_type which
)
480 /* The register can already have a range from prior markings.
481 * This is fine as long as it hasn't been advanced from its
484 return reg
->type
== which
&&
487 tnum_equals_const(reg
->var_off
, 0);
490 /* Attempts to improve min/max values based on var_off information */
491 static void __update_reg_bounds(struct bpf_reg_state
*reg
)
493 /* min signed is max(sign bit) | min(other bits) */
494 reg
->smin_value
= max_t(s64
, reg
->smin_value
,
495 reg
->var_off
.value
| (reg
->var_off
.mask
& S64_MIN
));
496 /* max signed is min(sign bit) | max(other bits) */
497 reg
->smax_value
= min_t(s64
, reg
->smax_value
,
498 reg
->var_off
.value
| (reg
->var_off
.mask
& S64_MAX
));
499 reg
->umin_value
= max(reg
->umin_value
, reg
->var_off
.value
);
500 reg
->umax_value
= min(reg
->umax_value
,
501 reg
->var_off
.value
| reg
->var_off
.mask
);
504 /* Uses signed min/max values to inform unsigned, and vice-versa */
505 static void __reg_deduce_bounds(struct bpf_reg_state
*reg
)
507 /* Learn sign from signed bounds.
508 * If we cannot cross the sign boundary, then signed and unsigned bounds
509 * are the same, so combine. This works even in the negative case, e.g.
510 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
512 if (reg
->smin_value
>= 0 || reg
->smax_value
< 0) {
513 reg
->smin_value
= reg
->umin_value
= max_t(u64
, reg
->smin_value
,
515 reg
->smax_value
= reg
->umax_value
= min_t(u64
, reg
->smax_value
,
519 /* Learn sign from unsigned bounds. Signed bounds cross the sign
520 * boundary, so we must be careful.
522 if ((s64
)reg
->umax_value
>= 0) {
523 /* Positive. We can't learn anything from the smin, but smax
524 * is positive, hence safe.
526 reg
->smin_value
= reg
->umin_value
;
527 reg
->smax_value
= reg
->umax_value
= min_t(u64
, reg
->smax_value
,
529 } else if ((s64
)reg
->umin_value
< 0) {
530 /* Negative. We can't learn anything from the smax, but smin
531 * is negative, hence safe.
533 reg
->smin_value
= reg
->umin_value
= max_t(u64
, reg
->smin_value
,
535 reg
->smax_value
= reg
->umax_value
;
539 /* Attempts to improve var_off based on unsigned min/max information */
540 static void __reg_bound_offset(struct bpf_reg_state
*reg
)
542 reg
->var_off
= tnum_intersect(reg
->var_off
,
543 tnum_range(reg
->umin_value
,
547 /* Reset the min/max bounds of a register */
548 static void __mark_reg_unbounded(struct bpf_reg_state
*reg
)
550 reg
->smin_value
= S64_MIN
;
551 reg
->smax_value
= S64_MAX
;
553 reg
->umax_value
= U64_MAX
;
556 /* Mark a register as having a completely unknown (scalar) value. */
557 static void __mark_reg_unknown(struct bpf_reg_state
*reg
)
559 reg
->type
= SCALAR_VALUE
;
562 reg
->var_off
= tnum_unknown
;
563 __mark_reg_unbounded(reg
);
566 static void mark_reg_unknown(struct bpf_verifier_env
*env
,
567 struct bpf_reg_state
*regs
, u32 regno
)
569 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
570 verbose(env
, "mark_reg_unknown(regs, %u)\n", regno
);
571 /* Something bad happened, let's kill all regs */
572 for (regno
= 0; regno
< MAX_BPF_REG
; regno
++)
573 __mark_reg_not_init(regs
+ regno
);
576 __mark_reg_unknown(regs
+ regno
);
579 static void __mark_reg_not_init(struct bpf_reg_state
*reg
)
581 __mark_reg_unknown(reg
);
582 reg
->type
= NOT_INIT
;
585 static void mark_reg_not_init(struct bpf_verifier_env
*env
,
586 struct bpf_reg_state
*regs
, u32 regno
)
588 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
589 verbose(env
, "mark_reg_not_init(regs, %u)\n", regno
);
590 /* Something bad happened, let's kill all regs */
591 for (regno
= 0; regno
< MAX_BPF_REG
; regno
++)
592 __mark_reg_not_init(regs
+ regno
);
595 __mark_reg_not_init(regs
+ regno
);
598 static void init_reg_state(struct bpf_verifier_env
*env
,
599 struct bpf_reg_state
*regs
)
603 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
604 mark_reg_not_init(env
, regs
, i
);
605 regs
[i
].live
= REG_LIVE_NONE
;
609 regs
[BPF_REG_FP
].type
= PTR_TO_STACK
;
610 mark_reg_known_zero(env
, regs
, BPF_REG_FP
);
612 /* 1st arg to a function */
613 regs
[BPF_REG_1
].type
= PTR_TO_CTX
;
614 mark_reg_known_zero(env
, regs
, BPF_REG_1
);
618 SRC_OP
, /* register is used as source operand */
619 DST_OP
, /* register is used as destination operand */
620 DST_OP_NO_MARK
/* same as above, check only, don't mark */
623 static void mark_reg_read(const struct bpf_verifier_state
*state
, u32 regno
)
625 struct bpf_verifier_state
*parent
= state
->parent
;
627 if (regno
== BPF_REG_FP
)
628 /* We don't need to worry about FP liveness because it's read-only */
632 /* if read wasn't screened by an earlier write ... */
633 if (state
->regs
[regno
].live
& REG_LIVE_WRITTEN
)
635 /* ... then we depend on parent's value */
636 parent
->regs
[regno
].live
|= REG_LIVE_READ
;
638 parent
= state
->parent
;
642 static int check_reg_arg(struct bpf_verifier_env
*env
, u32 regno
,
645 struct bpf_reg_state
*regs
= env
->cur_state
->regs
;
647 if (regno
>= MAX_BPF_REG
) {
648 verbose(env
, "R%d is invalid\n", regno
);
653 /* check whether register used as source operand can be read */
654 if (regs
[regno
].type
== NOT_INIT
) {
655 verbose(env
, "R%d !read_ok\n", regno
);
658 mark_reg_read(env
->cur_state
, regno
);
660 /* check whether register used as dest operand can be written to */
661 if (regno
== BPF_REG_FP
) {
662 verbose(env
, "frame pointer is read only\n");
665 regs
[regno
].live
|= REG_LIVE_WRITTEN
;
667 mark_reg_unknown(env
, regs
, regno
);
672 static bool is_spillable_regtype(enum bpf_reg_type type
)
675 case PTR_TO_MAP_VALUE
:
676 case PTR_TO_MAP_VALUE_OR_NULL
:
680 case PTR_TO_PACKET_META
:
681 case PTR_TO_PACKET_END
:
682 case CONST_PTR_TO_MAP
:
689 /* check_stack_read/write functions track spill/fill of registers,
690 * stack boundary and alignment are checked in check_mem_access()
692 static int check_stack_write(struct bpf_verifier_env
*env
,
693 struct bpf_verifier_state
*state
, int off
,
694 int size
, int value_regno
)
696 int i
, slot
= -off
- 1, spi
= slot
/ BPF_REG_SIZE
, err
;
698 err
= realloc_verifier_state(state
, round_up(slot
+ 1, BPF_REG_SIZE
),
702 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
703 * so it's aligned access and [off, off + size) are within stack limits
705 if (!env
->allow_ptr_leaks
&&
706 state
->stack
[spi
].slot_type
[0] == STACK_SPILL
&&
707 size
!= BPF_REG_SIZE
) {
708 verbose(env
, "attempt to corrupt spilled pointer on stack\n");
712 if (value_regno
>= 0 &&
713 is_spillable_regtype(state
->regs
[value_regno
].type
)) {
715 /* register containing pointer is being spilled into stack */
716 if (size
!= BPF_REG_SIZE
) {
717 verbose(env
, "invalid size of register spill\n");
721 /* save register state */
722 state
->stack
[spi
].spilled_ptr
= state
->regs
[value_regno
];
723 state
->stack
[spi
].spilled_ptr
.live
|= REG_LIVE_WRITTEN
;
725 for (i
= 0; i
< BPF_REG_SIZE
; i
++)
726 state
->stack
[spi
].slot_type
[i
] = STACK_SPILL
;
728 /* regular write of data into stack */
729 state
->stack
[spi
].spilled_ptr
= (struct bpf_reg_state
) {};
731 for (i
= 0; i
< size
; i
++)
732 state
->stack
[spi
].slot_type
[(slot
- i
) % BPF_REG_SIZE
] =
738 static void mark_stack_slot_read(const struct bpf_verifier_state
*state
, int slot
)
740 struct bpf_verifier_state
*parent
= state
->parent
;
743 /* if read wasn't screened by an earlier write ... */
744 if (state
->stack
[slot
].spilled_ptr
.live
& REG_LIVE_WRITTEN
)
746 /* ... then we depend on parent's value */
747 parent
->stack
[slot
].spilled_ptr
.live
|= REG_LIVE_READ
;
749 parent
= state
->parent
;
753 static int check_stack_read(struct bpf_verifier_env
*env
,
754 struct bpf_verifier_state
*state
, int off
, int size
,
757 int i
, slot
= -off
- 1, spi
= slot
/ BPF_REG_SIZE
;
760 if (state
->allocated_stack
<= slot
) {
761 verbose(env
, "invalid read from stack off %d+0 size %d\n",
765 stype
= state
->stack
[spi
].slot_type
;
767 if (stype
[0] == STACK_SPILL
) {
768 if (size
!= BPF_REG_SIZE
) {
769 verbose(env
, "invalid size of register spill\n");
772 for (i
= 1; i
< BPF_REG_SIZE
; i
++) {
773 if (stype
[(slot
- i
) % BPF_REG_SIZE
] != STACK_SPILL
) {
774 verbose(env
, "corrupted spill memory\n");
779 if (value_regno
>= 0) {
780 /* restore register state from stack */
781 state
->regs
[value_regno
] = state
->stack
[spi
].spilled_ptr
;
782 mark_stack_slot_read(state
, spi
);
786 for (i
= 0; i
< size
; i
++) {
787 if (stype
[(slot
- i
) % BPF_REG_SIZE
] != STACK_MISC
) {
788 verbose(env
, "invalid read from stack off %d+%d size %d\n",
793 if (value_regno
>= 0)
794 /* have read misc data from the stack */
795 mark_reg_unknown(env
, state
->regs
, value_regno
);
800 /* check read/write into map element returned by bpf_map_lookup_elem() */
801 static int __check_map_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
802 int size
, bool zero_size_allowed
)
804 struct bpf_reg_state
*regs
= cur_regs(env
);
805 struct bpf_map
*map
= regs
[regno
].map_ptr
;
807 if (off
< 0 || size
< 0 || (size
== 0 && !zero_size_allowed
) ||
808 off
+ size
> map
->value_size
) {
809 verbose(env
, "invalid access to map value, value_size=%d off=%d size=%d\n",
810 map
->value_size
, off
, size
);
816 /* check read/write into a map element with possible variable offset */
817 static int check_map_access(struct bpf_verifier_env
*env
, u32 regno
,
818 int off
, int size
, bool zero_size_allowed
)
820 struct bpf_verifier_state
*state
= env
->cur_state
;
821 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
824 /* We may have adjusted the register to this map value, so we
825 * need to try adding each of min_value and max_value to off
826 * to make sure our theoretical access will be safe.
829 print_verifier_state(env
, state
);
830 /* The minimum value is only important with signed
831 * comparisons where we can't assume the floor of a
832 * value is 0. If we are using signed variables for our
833 * index'es we need to make sure that whatever we use
834 * will have a set floor within our range.
836 if (reg
->smin_value
< 0) {
837 verbose(env
, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
841 err
= __check_map_access(env
, regno
, reg
->smin_value
+ off
, size
,
844 verbose(env
, "R%d min value is outside of the array range\n",
849 /* If we haven't set a max value then we need to bail since we can't be
850 * sure we won't do bad things.
851 * If reg->umax_value + off could overflow, treat that as unbounded too.
853 if (reg
->umax_value
>= BPF_MAX_VAR_OFF
) {
854 verbose(env
, "R%d unbounded memory access, make sure to bounds check any array access into a map\n",
858 err
= __check_map_access(env
, regno
, reg
->umax_value
+ off
, size
,
861 verbose(env
, "R%d max value is outside of the array range\n",
866 #define MAX_PACKET_OFF 0xffff
868 static bool may_access_direct_pkt_data(struct bpf_verifier_env
*env
,
869 const struct bpf_call_arg_meta
*meta
,
870 enum bpf_access_type t
)
872 switch (env
->prog
->type
) {
873 case BPF_PROG_TYPE_LWT_IN
:
874 case BPF_PROG_TYPE_LWT_OUT
:
875 /* dst_input() and dst_output() can't write for now */
879 case BPF_PROG_TYPE_SCHED_CLS
:
880 case BPF_PROG_TYPE_SCHED_ACT
:
881 case BPF_PROG_TYPE_XDP
:
882 case BPF_PROG_TYPE_LWT_XMIT
:
883 case BPF_PROG_TYPE_SK_SKB
:
885 return meta
->pkt_access
;
887 env
->seen_direct_write
= true;
894 static int __check_packet_access(struct bpf_verifier_env
*env
, u32 regno
,
895 int off
, int size
, bool zero_size_allowed
)
897 struct bpf_reg_state
*regs
= cur_regs(env
);
898 struct bpf_reg_state
*reg
= ®s
[regno
];
900 if (off
< 0 || size
< 0 || (size
== 0 && !zero_size_allowed
) ||
901 (u64
)off
+ size
> reg
->range
) {
902 verbose(env
, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
903 off
, size
, regno
, reg
->id
, reg
->off
, reg
->range
);
909 static int check_packet_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
910 int size
, bool zero_size_allowed
)
912 struct bpf_reg_state
*regs
= cur_regs(env
);
913 struct bpf_reg_state
*reg
= ®s
[regno
];
916 /* We may have added a variable offset to the packet pointer; but any
917 * reg->range we have comes after that. We are only checking the fixed
921 /* We don't allow negative numbers, because we aren't tracking enough
922 * detail to prove they're safe.
924 if (reg
->smin_value
< 0) {
925 verbose(env
, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
929 err
= __check_packet_access(env
, regno
, off
, size
, zero_size_allowed
);
931 verbose(env
, "R%d offset is outside of the packet\n", regno
);
937 /* check access to 'struct bpf_context' fields. Supports fixed offsets only */
938 static int check_ctx_access(struct bpf_verifier_env
*env
, int insn_idx
, int off
, int size
,
939 enum bpf_access_type t
, enum bpf_reg_type
*reg_type
)
941 struct bpf_insn_access_aux info
= {
942 .reg_type
= *reg_type
,
945 if (env
->ops
->is_valid_access
&&
946 env
->ops
->is_valid_access(off
, size
, t
, &info
)) {
947 /* A non zero info.ctx_field_size indicates that this field is a
948 * candidate for later verifier transformation to load the whole
949 * field and then apply a mask when accessed with a narrower
950 * access than actual ctx access size. A zero info.ctx_field_size
951 * will only allow for whole field access and rejects any other
952 * type of narrower access.
954 *reg_type
= info
.reg_type
;
956 env
->insn_aux_data
[insn_idx
].ctx_field_size
= info
.ctx_field_size
;
957 /* remember the offset of last byte accessed in ctx */
958 if (env
->prog
->aux
->max_ctx_offset
< off
+ size
)
959 env
->prog
->aux
->max_ctx_offset
= off
+ size
;
963 verbose(env
, "invalid bpf_context access off=%d size=%d\n", off
, size
);
967 static bool __is_pointer_value(bool allow_ptr_leaks
,
968 const struct bpf_reg_state
*reg
)
973 return reg
->type
!= SCALAR_VALUE
;
976 static bool is_pointer_value(struct bpf_verifier_env
*env
, int regno
)
978 return __is_pointer_value(env
->allow_ptr_leaks
, cur_regs(env
) + regno
);
981 static int check_pkt_ptr_alignment(struct bpf_verifier_env
*env
,
982 const struct bpf_reg_state
*reg
,
983 int off
, int size
, bool strict
)
988 /* Byte size accesses are always allowed. */
989 if (!strict
|| size
== 1)
992 /* For platforms that do not have a Kconfig enabling
993 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
994 * NET_IP_ALIGN is universally set to '2'. And on platforms
995 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
996 * to this code only in strict mode where we want to emulate
997 * the NET_IP_ALIGN==2 checking. Therefore use an
998 * unconditional IP align value of '2'.
1002 reg_off
= tnum_add(reg
->var_off
, tnum_const(ip_align
+ reg
->off
+ off
));
1003 if (!tnum_is_aligned(reg_off
, size
)) {
1006 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1008 "misaligned packet access off %d+%s+%d+%d size %d\n",
1009 ip_align
, tn_buf
, reg
->off
, off
, size
);
1016 static int check_generic_ptr_alignment(struct bpf_verifier_env
*env
,
1017 const struct bpf_reg_state
*reg
,
1018 const char *pointer_desc
,
1019 int off
, int size
, bool strict
)
1021 struct tnum reg_off
;
1023 /* Byte size accesses are always allowed. */
1024 if (!strict
|| size
== 1)
1027 reg_off
= tnum_add(reg
->var_off
, tnum_const(reg
->off
+ off
));
1028 if (!tnum_is_aligned(reg_off
, size
)) {
1031 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1032 verbose(env
, "misaligned %saccess off %s+%d+%d size %d\n",
1033 pointer_desc
, tn_buf
, reg
->off
, off
, size
);
1040 static int check_ptr_alignment(struct bpf_verifier_env
*env
,
1041 const struct bpf_reg_state
*reg
,
1044 bool strict
= env
->strict_alignment
;
1045 const char *pointer_desc
= "";
1047 switch (reg
->type
) {
1049 case PTR_TO_PACKET_META
:
1050 /* Special case, because of NET_IP_ALIGN. Given metadata sits
1051 * right in front, treat it the very same way.
1053 return check_pkt_ptr_alignment(env
, reg
, off
, size
, strict
);
1054 case PTR_TO_MAP_VALUE
:
1055 pointer_desc
= "value ";
1058 pointer_desc
= "context ";
1061 pointer_desc
= "stack ";
1062 /* The stack spill tracking logic in check_stack_write()
1063 * and check_stack_read() relies on stack accesses being
1071 return check_generic_ptr_alignment(env
, reg
, pointer_desc
, off
, size
,
1075 /* truncate register to smaller size (in bytes)
1076 * must be called with size < BPF_REG_SIZE
1078 static void coerce_reg_to_size(struct bpf_reg_state
*reg
, int size
)
1082 /* clear high bits in bit representation */
1083 reg
->var_off
= tnum_cast(reg
->var_off
, size
);
1085 /* fix arithmetic bounds */
1086 mask
= ((u64
)1 << (size
* 8)) - 1;
1087 if ((reg
->umin_value
& ~mask
) == (reg
->umax_value
& ~mask
)) {
1088 reg
->umin_value
&= mask
;
1089 reg
->umax_value
&= mask
;
1091 reg
->umin_value
= 0;
1092 reg
->umax_value
= mask
;
1094 reg
->smin_value
= reg
->umin_value
;
1095 reg
->smax_value
= reg
->umax_value
;
1098 /* check whether memory at (regno + off) is accessible for t = (read | write)
1099 * if t==write, value_regno is a register which value is stored into memory
1100 * if t==read, value_regno is a register which will receive the value from memory
1101 * if t==write && value_regno==-1, some unknown value is stored into memory
1102 * if t==read && value_regno==-1, don't care what we read from memory
1104 static int check_mem_access(struct bpf_verifier_env
*env
, int insn_idx
, u32 regno
, int off
,
1105 int bpf_size
, enum bpf_access_type t
,
1108 struct bpf_verifier_state
*state
= env
->cur_state
;
1109 struct bpf_reg_state
*regs
= cur_regs(env
);
1110 struct bpf_reg_state
*reg
= regs
+ regno
;
1113 size
= bpf_size_to_bytes(bpf_size
);
1117 /* alignment checks will add in reg->off themselves */
1118 err
= check_ptr_alignment(env
, reg
, off
, size
);
1122 /* for access checks, reg->off is just part of off */
1125 if (reg
->type
== PTR_TO_MAP_VALUE
) {
1126 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1127 is_pointer_value(env
, value_regno
)) {
1128 verbose(env
, "R%d leaks addr into map\n", value_regno
);
1132 err
= check_map_access(env
, regno
, off
, size
, false);
1133 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
1134 mark_reg_unknown(env
, regs
, value_regno
);
1136 } else if (reg
->type
== PTR_TO_CTX
) {
1137 enum bpf_reg_type reg_type
= SCALAR_VALUE
;
1139 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1140 is_pointer_value(env
, value_regno
)) {
1141 verbose(env
, "R%d leaks addr into ctx\n", value_regno
);
1144 /* ctx accesses must be at a fixed offset, so that we can
1145 * determine what type of data were returned.
1149 "dereference of modified ctx ptr R%d off=%d+%d, ctx+const is allowed, ctx+const+const is not\n",
1150 regno
, reg
->off
, off
- reg
->off
);
1153 if (!tnum_is_const(reg
->var_off
) || reg
->var_off
.value
) {
1156 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1158 "variable ctx access var_off=%s off=%d size=%d",
1162 err
= check_ctx_access(env
, insn_idx
, off
, size
, t
, ®_type
);
1163 if (!err
&& t
== BPF_READ
&& value_regno
>= 0) {
1164 /* ctx access returns either a scalar, or a
1165 * PTR_TO_PACKET[_META,_END]. In the latter
1166 * case, we know the offset is zero.
1168 if (reg_type
== SCALAR_VALUE
)
1169 mark_reg_unknown(env
, regs
, value_regno
);
1171 mark_reg_known_zero(env
, regs
,
1173 regs
[value_regno
].id
= 0;
1174 regs
[value_regno
].off
= 0;
1175 regs
[value_regno
].range
= 0;
1176 regs
[value_regno
].type
= reg_type
;
1179 } else if (reg
->type
== PTR_TO_STACK
) {
1180 /* stack accesses must be at a fixed offset, so that we can
1181 * determine what type of data were returned.
1182 * See check_stack_read().
1184 if (!tnum_is_const(reg
->var_off
)) {
1187 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1188 verbose(env
, "variable stack access var_off=%s off=%d size=%d",
1192 off
+= reg
->var_off
.value
;
1193 if (off
>= 0 || off
< -MAX_BPF_STACK
) {
1194 verbose(env
, "invalid stack off=%d size=%d\n", off
,
1199 if (env
->prog
->aux
->stack_depth
< -off
)
1200 env
->prog
->aux
->stack_depth
= -off
;
1203 err
= check_stack_write(env
, state
, off
, size
,
1206 err
= check_stack_read(env
, state
, off
, size
,
1208 } else if (reg_is_pkt_pointer(reg
)) {
1209 if (t
== BPF_WRITE
&& !may_access_direct_pkt_data(env
, NULL
, t
)) {
1210 verbose(env
, "cannot write into packet\n");
1213 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1214 is_pointer_value(env
, value_regno
)) {
1215 verbose(env
, "R%d leaks addr into packet\n",
1219 err
= check_packet_access(env
, regno
, off
, size
, false);
1220 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
1221 mark_reg_unknown(env
, regs
, value_regno
);
1223 verbose(env
, "R%d invalid mem access '%s'\n", regno
,
1224 reg_type_str
[reg
->type
]);
1228 if (!err
&& size
< BPF_REG_SIZE
&& value_regno
>= 0 && t
== BPF_READ
&&
1229 regs
[value_regno
].type
== SCALAR_VALUE
) {
1230 /* b/h/w load zero-extends, mark upper bits as known 0 */
1231 coerce_reg_to_size(®s
[value_regno
], size
);
1236 static int check_xadd(struct bpf_verifier_env
*env
, int insn_idx
, struct bpf_insn
*insn
)
1240 if ((BPF_SIZE(insn
->code
) != BPF_W
&& BPF_SIZE(insn
->code
) != BPF_DW
) ||
1242 verbose(env
, "BPF_XADD uses reserved fields\n");
1246 /* check src1 operand */
1247 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
1251 /* check src2 operand */
1252 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
1256 if (is_pointer_value(env
, insn
->src_reg
)) {
1257 verbose(env
, "R%d leaks addr into mem\n", insn
->src_reg
);
1261 /* check whether atomic_add can read the memory */
1262 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1263 BPF_SIZE(insn
->code
), BPF_READ
, -1);
1267 /* check whether atomic_add can write into the same memory */
1268 return check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1269 BPF_SIZE(insn
->code
), BPF_WRITE
, -1);
1272 /* Does this register contain a constant zero? */
1273 static bool register_is_null(struct bpf_reg_state reg
)
1275 return reg
.type
== SCALAR_VALUE
&& tnum_equals_const(reg
.var_off
, 0);
1278 /* when register 'regno' is passed into function that will read 'access_size'
1279 * bytes from that pointer, make sure that it's within stack boundary
1280 * and all elements of stack are initialized.
1281 * Unlike most pointer bounds-checking functions, this one doesn't take an
1282 * 'off' argument, so it has to add in reg->off itself.
1284 static int check_stack_boundary(struct bpf_verifier_env
*env
, int regno
,
1285 int access_size
, bool zero_size_allowed
,
1286 struct bpf_call_arg_meta
*meta
)
1288 struct bpf_verifier_state
*state
= env
->cur_state
;
1289 struct bpf_reg_state
*regs
= state
->regs
;
1290 int off
, i
, slot
, spi
;
1292 if (regs
[regno
].type
!= PTR_TO_STACK
) {
1293 /* Allow zero-byte read from NULL, regardless of pointer type */
1294 if (zero_size_allowed
&& access_size
== 0 &&
1295 register_is_null(regs
[regno
]))
1298 verbose(env
, "R%d type=%s expected=%s\n", regno
,
1299 reg_type_str
[regs
[regno
].type
],
1300 reg_type_str
[PTR_TO_STACK
]);
1304 /* Only allow fixed-offset stack reads */
1305 if (!tnum_is_const(regs
[regno
].var_off
)) {
1308 tnum_strn(tn_buf
, sizeof(tn_buf
), regs
[regno
].var_off
);
1309 verbose(env
, "invalid variable stack read R%d var_off=%s\n",
1313 off
= regs
[regno
].off
+ regs
[regno
].var_off
.value
;
1314 if (off
>= 0 || off
< -MAX_BPF_STACK
|| off
+ access_size
> 0 ||
1315 access_size
< 0 || (access_size
== 0 && !zero_size_allowed
)) {
1316 verbose(env
, "invalid stack type R%d off=%d access_size=%d\n",
1317 regno
, off
, access_size
);
1321 if (env
->prog
->aux
->stack_depth
< -off
)
1322 env
->prog
->aux
->stack_depth
= -off
;
1324 if (meta
&& meta
->raw_mode
) {
1325 meta
->access_size
= access_size
;
1326 meta
->regno
= regno
;
1330 for (i
= 0; i
< access_size
; i
++) {
1331 slot
= -(off
+ i
) - 1;
1332 spi
= slot
/ BPF_REG_SIZE
;
1333 if (state
->allocated_stack
<= slot
||
1334 state
->stack
[spi
].slot_type
[slot
% BPF_REG_SIZE
] !=
1336 verbose(env
, "invalid indirect read from stack off %d+%d size %d\n",
1337 off
, i
, access_size
);
1344 static int check_helper_mem_access(struct bpf_verifier_env
*env
, int regno
,
1345 int access_size
, bool zero_size_allowed
,
1346 struct bpf_call_arg_meta
*meta
)
1348 struct bpf_reg_state
*regs
= cur_regs(env
), *reg
= ®s
[regno
];
1350 switch (reg
->type
) {
1352 case PTR_TO_PACKET_META
:
1353 return check_packet_access(env
, regno
, reg
->off
, access_size
,
1355 case PTR_TO_MAP_VALUE
:
1356 return check_map_access(env
, regno
, reg
->off
, access_size
,
1358 default: /* scalar_value|ptr_to_stack or invalid ptr */
1359 return check_stack_boundary(env
, regno
, access_size
,
1360 zero_size_allowed
, meta
);
1364 static int check_func_arg(struct bpf_verifier_env
*env
, u32 regno
,
1365 enum bpf_arg_type arg_type
,
1366 struct bpf_call_arg_meta
*meta
)
1368 struct bpf_reg_state
*regs
= cur_regs(env
), *reg
= ®s
[regno
];
1369 enum bpf_reg_type expected_type
, type
= reg
->type
;
1372 if (arg_type
== ARG_DONTCARE
)
1375 err
= check_reg_arg(env
, regno
, SRC_OP
);
1379 if (arg_type
== ARG_ANYTHING
) {
1380 if (is_pointer_value(env
, regno
)) {
1381 verbose(env
, "R%d leaks addr into helper function\n",
1388 if (type_is_pkt_pointer(type
) &&
1389 !may_access_direct_pkt_data(env
, meta
, BPF_READ
)) {
1390 verbose(env
, "helper access to the packet is not allowed\n");
1394 if (arg_type
== ARG_PTR_TO_MAP_KEY
||
1395 arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1396 expected_type
= PTR_TO_STACK
;
1397 if (!type_is_pkt_pointer(type
) &&
1398 type
!= expected_type
)
1400 } else if (arg_type
== ARG_CONST_SIZE
||
1401 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1402 expected_type
= SCALAR_VALUE
;
1403 if (type
!= expected_type
)
1405 } else if (arg_type
== ARG_CONST_MAP_PTR
) {
1406 expected_type
= CONST_PTR_TO_MAP
;
1407 if (type
!= expected_type
)
1409 } else if (arg_type
== ARG_PTR_TO_CTX
) {
1410 expected_type
= PTR_TO_CTX
;
1411 if (type
!= expected_type
)
1413 } else if (arg_type
== ARG_PTR_TO_MEM
||
1414 arg_type
== ARG_PTR_TO_MEM_OR_NULL
||
1415 arg_type
== ARG_PTR_TO_UNINIT_MEM
) {
1416 expected_type
= PTR_TO_STACK
;
1417 /* One exception here. In case function allows for NULL to be
1418 * passed in as argument, it's a SCALAR_VALUE type. Final test
1419 * happens during stack boundary checking.
1421 if (register_is_null(*reg
) &&
1422 arg_type
== ARG_PTR_TO_MEM_OR_NULL
)
1423 /* final test in check_stack_boundary() */;
1424 else if (!type_is_pkt_pointer(type
) &&
1425 type
!= PTR_TO_MAP_VALUE
&&
1426 type
!= expected_type
)
1428 meta
->raw_mode
= arg_type
== ARG_PTR_TO_UNINIT_MEM
;
1430 verbose(env
, "unsupported arg_type %d\n", arg_type
);
1434 if (arg_type
== ARG_CONST_MAP_PTR
) {
1435 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1436 meta
->map_ptr
= reg
->map_ptr
;
1437 } else if (arg_type
== ARG_PTR_TO_MAP_KEY
) {
1438 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1439 * check that [key, key + map->key_size) are within
1440 * stack limits and initialized
1442 if (!meta
->map_ptr
) {
1443 /* in function declaration map_ptr must come before
1444 * map_key, so that it's verified and known before
1445 * we have to check map_key here. Otherwise it means
1446 * that kernel subsystem misconfigured verifier
1448 verbose(env
, "invalid map_ptr to access map->key\n");
1451 if (type_is_pkt_pointer(type
))
1452 err
= check_packet_access(env
, regno
, reg
->off
,
1453 meta
->map_ptr
->key_size
,
1456 err
= check_stack_boundary(env
, regno
,
1457 meta
->map_ptr
->key_size
,
1459 } else if (arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1460 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1461 * check [value, value + map->value_size) validity
1463 if (!meta
->map_ptr
) {
1464 /* kernel subsystem misconfigured verifier */
1465 verbose(env
, "invalid map_ptr to access map->value\n");
1468 if (type_is_pkt_pointer(type
))
1469 err
= check_packet_access(env
, regno
, reg
->off
,
1470 meta
->map_ptr
->value_size
,
1473 err
= check_stack_boundary(env
, regno
,
1474 meta
->map_ptr
->value_size
,
1476 } else if (arg_type
== ARG_CONST_SIZE
||
1477 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1478 bool zero_size_allowed
= (arg_type
== ARG_CONST_SIZE_OR_ZERO
);
1480 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1481 * from stack pointer 'buf'. Check it
1482 * note: regno == len, regno - 1 == buf
1485 /* kernel subsystem misconfigured verifier */
1487 "ARG_CONST_SIZE cannot be first argument\n");
1491 /* The register is SCALAR_VALUE; the access check
1492 * happens using its boundaries.
1495 if (!tnum_is_const(reg
->var_off
))
1496 /* For unprivileged variable accesses, disable raw
1497 * mode so that the program is required to
1498 * initialize all the memory that the helper could
1499 * just partially fill up.
1503 if (reg
->smin_value
< 0) {
1504 verbose(env
, "R%d min value is negative, either use unsigned or 'var &= const'\n",
1509 if (reg
->umin_value
== 0) {
1510 err
= check_helper_mem_access(env
, regno
- 1, 0,
1517 if (reg
->umax_value
>= BPF_MAX_VAR_SIZ
) {
1518 verbose(env
, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
1522 err
= check_helper_mem_access(env
, regno
- 1,
1524 zero_size_allowed
, meta
);
1529 verbose(env
, "R%d type=%s expected=%s\n", regno
,
1530 reg_type_str
[type
], reg_type_str
[expected_type
]);
1534 static int check_map_func_compatibility(struct bpf_verifier_env
*env
,
1535 struct bpf_map
*map
, int func_id
)
1540 /* We need a two way check, first is from map perspective ... */
1541 switch (map
->map_type
) {
1542 case BPF_MAP_TYPE_PROG_ARRAY
:
1543 if (func_id
!= BPF_FUNC_tail_call
)
1546 case BPF_MAP_TYPE_PERF_EVENT_ARRAY
:
1547 if (func_id
!= BPF_FUNC_perf_event_read
&&
1548 func_id
!= BPF_FUNC_perf_event_output
&&
1549 func_id
!= BPF_FUNC_perf_event_read_value
)
1552 case BPF_MAP_TYPE_STACK_TRACE
:
1553 if (func_id
!= BPF_FUNC_get_stackid
)
1556 case BPF_MAP_TYPE_CGROUP_ARRAY
:
1557 if (func_id
!= BPF_FUNC_skb_under_cgroup
&&
1558 func_id
!= BPF_FUNC_current_task_under_cgroup
)
1561 /* devmap returns a pointer to a live net_device ifindex that we cannot
1562 * allow to be modified from bpf side. So do not allow lookup elements
1565 case BPF_MAP_TYPE_DEVMAP
:
1566 if (func_id
!= BPF_FUNC_redirect_map
)
1569 /* Restrict bpf side of cpumap, open when use-cases appear */
1570 case BPF_MAP_TYPE_CPUMAP
:
1571 if (func_id
!= BPF_FUNC_redirect_map
)
1574 case BPF_MAP_TYPE_ARRAY_OF_MAPS
:
1575 case BPF_MAP_TYPE_HASH_OF_MAPS
:
1576 if (func_id
!= BPF_FUNC_map_lookup_elem
)
1579 case BPF_MAP_TYPE_SOCKMAP
:
1580 if (func_id
!= BPF_FUNC_sk_redirect_map
&&
1581 func_id
!= BPF_FUNC_sock_map_update
&&
1582 func_id
!= BPF_FUNC_map_delete_elem
)
1589 /* ... and second from the function itself. */
1591 case BPF_FUNC_tail_call
:
1592 if (map
->map_type
!= BPF_MAP_TYPE_PROG_ARRAY
)
1595 case BPF_FUNC_perf_event_read
:
1596 case BPF_FUNC_perf_event_output
:
1597 case BPF_FUNC_perf_event_read_value
:
1598 if (map
->map_type
!= BPF_MAP_TYPE_PERF_EVENT_ARRAY
)
1601 case BPF_FUNC_get_stackid
:
1602 if (map
->map_type
!= BPF_MAP_TYPE_STACK_TRACE
)
1605 case BPF_FUNC_current_task_under_cgroup
:
1606 case BPF_FUNC_skb_under_cgroup
:
1607 if (map
->map_type
!= BPF_MAP_TYPE_CGROUP_ARRAY
)
1610 case BPF_FUNC_redirect_map
:
1611 if (map
->map_type
!= BPF_MAP_TYPE_DEVMAP
&&
1612 map
->map_type
!= BPF_MAP_TYPE_CPUMAP
)
1615 case BPF_FUNC_sk_redirect_map
:
1616 if (map
->map_type
!= BPF_MAP_TYPE_SOCKMAP
)
1619 case BPF_FUNC_sock_map_update
:
1620 if (map
->map_type
!= BPF_MAP_TYPE_SOCKMAP
)
1629 verbose(env
, "cannot pass map_type %d into func %s#%d\n",
1630 map
->map_type
, func_id_name(func_id
), func_id
);
1634 static int check_raw_mode(const struct bpf_func_proto
*fn
)
1638 if (fn
->arg1_type
== ARG_PTR_TO_UNINIT_MEM
)
1640 if (fn
->arg2_type
== ARG_PTR_TO_UNINIT_MEM
)
1642 if (fn
->arg3_type
== ARG_PTR_TO_UNINIT_MEM
)
1644 if (fn
->arg4_type
== ARG_PTR_TO_UNINIT_MEM
)
1646 if (fn
->arg5_type
== ARG_PTR_TO_UNINIT_MEM
)
1649 return count
> 1 ? -EINVAL
: 0;
1652 /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
1653 * are now invalid, so turn them into unknown SCALAR_VALUE.
1655 static void clear_all_pkt_pointers(struct bpf_verifier_env
*env
)
1657 struct bpf_verifier_state
*state
= env
->cur_state
;
1658 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
1661 for (i
= 0; i
< MAX_BPF_REG
; i
++)
1662 if (reg_is_pkt_pointer_any(®s
[i
]))
1663 mark_reg_unknown(env
, regs
, i
);
1665 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
1666 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
1668 reg
= &state
->stack
[i
].spilled_ptr
;
1669 if (reg_is_pkt_pointer_any(reg
))
1670 __mark_reg_unknown(reg
);
1674 static int check_call(struct bpf_verifier_env
*env
, int func_id
, int insn_idx
)
1676 const struct bpf_func_proto
*fn
= NULL
;
1677 struct bpf_reg_state
*regs
;
1678 struct bpf_call_arg_meta meta
;
1682 /* find function prototype */
1683 if (func_id
< 0 || func_id
>= __BPF_FUNC_MAX_ID
) {
1684 verbose(env
, "invalid func %s#%d\n", func_id_name(func_id
),
1689 if (env
->ops
->get_func_proto
)
1690 fn
= env
->ops
->get_func_proto(func_id
);
1693 verbose(env
, "unknown func %s#%d\n", func_id_name(func_id
),
1698 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1699 if (!env
->prog
->gpl_compatible
&& fn
->gpl_only
) {
1700 verbose(env
, "cannot call GPL only function from proprietary program\n");
1704 /* With LD_ABS/IND some JITs save/restore skb from r1. */
1705 changes_data
= bpf_helper_changes_pkt_data(fn
->func
);
1706 if (changes_data
&& fn
->arg1_type
!= ARG_PTR_TO_CTX
) {
1707 verbose(env
, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
1708 func_id_name(func_id
), func_id
);
1712 memset(&meta
, 0, sizeof(meta
));
1713 meta
.pkt_access
= fn
->pkt_access
;
1715 /* We only support one arg being in raw mode at the moment, which
1716 * is sufficient for the helper functions we have right now.
1718 err
= check_raw_mode(fn
);
1720 verbose(env
, "kernel subsystem misconfigured func %s#%d\n",
1721 func_id_name(func_id
), func_id
);
1726 err
= check_func_arg(env
, BPF_REG_1
, fn
->arg1_type
, &meta
);
1729 err
= check_func_arg(env
, BPF_REG_2
, fn
->arg2_type
, &meta
);
1732 if (func_id
== BPF_FUNC_tail_call
) {
1733 if (meta
.map_ptr
== NULL
) {
1734 verbose(env
, "verifier bug\n");
1737 env
->insn_aux_data
[insn_idx
].map_ptr
= meta
.map_ptr
;
1739 err
= check_func_arg(env
, BPF_REG_3
, fn
->arg3_type
, &meta
);
1742 err
= check_func_arg(env
, BPF_REG_4
, fn
->arg4_type
, &meta
);
1745 err
= check_func_arg(env
, BPF_REG_5
, fn
->arg5_type
, &meta
);
1749 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1750 * is inferred from register state.
1752 for (i
= 0; i
< meta
.access_size
; i
++) {
1753 err
= check_mem_access(env
, insn_idx
, meta
.regno
, i
, BPF_B
, BPF_WRITE
, -1);
1758 regs
= cur_regs(env
);
1759 /* reset caller saved regs */
1760 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
1761 mark_reg_not_init(env
, regs
, caller_saved
[i
]);
1762 check_reg_arg(env
, caller_saved
[i
], DST_OP_NO_MARK
);
1765 /* update return register (already marked as written above) */
1766 if (fn
->ret_type
== RET_INTEGER
) {
1767 /* sets type to SCALAR_VALUE */
1768 mark_reg_unknown(env
, regs
, BPF_REG_0
);
1769 } else if (fn
->ret_type
== RET_VOID
) {
1770 regs
[BPF_REG_0
].type
= NOT_INIT
;
1771 } else if (fn
->ret_type
== RET_PTR_TO_MAP_VALUE_OR_NULL
) {
1772 struct bpf_insn_aux_data
*insn_aux
;
1774 regs
[BPF_REG_0
].type
= PTR_TO_MAP_VALUE_OR_NULL
;
1775 /* There is no offset yet applied, variable or fixed */
1776 mark_reg_known_zero(env
, regs
, BPF_REG_0
);
1777 regs
[BPF_REG_0
].off
= 0;
1778 /* remember map_ptr, so that check_map_access()
1779 * can check 'value_size' boundary of memory access
1780 * to map element returned from bpf_map_lookup_elem()
1782 if (meta
.map_ptr
== NULL
) {
1784 "kernel subsystem misconfigured verifier\n");
1787 regs
[BPF_REG_0
].map_ptr
= meta
.map_ptr
;
1788 regs
[BPF_REG_0
].id
= ++env
->id_gen
;
1789 insn_aux
= &env
->insn_aux_data
[insn_idx
];
1790 if (!insn_aux
->map_ptr
)
1791 insn_aux
->map_ptr
= meta
.map_ptr
;
1792 else if (insn_aux
->map_ptr
!= meta
.map_ptr
)
1793 insn_aux
->map_ptr
= BPF_MAP_PTR_POISON
;
1795 verbose(env
, "unknown return type %d of func %s#%d\n",
1796 fn
->ret_type
, func_id_name(func_id
), func_id
);
1800 err
= check_map_func_compatibility(env
, meta
.map_ptr
, func_id
);
1805 clear_all_pkt_pointers(env
);
1809 static bool signed_add_overflows(s64 a
, s64 b
)
1811 /* Do the add in u64, where overflow is well-defined */
1812 s64 res
= (s64
)((u64
)a
+ (u64
)b
);
1819 static bool signed_sub_overflows(s64 a
, s64 b
)
1821 /* Do the sub in u64, where overflow is well-defined */
1822 s64 res
= (s64
)((u64
)a
- (u64
)b
);
1829 static bool check_reg_sane_offset(struct bpf_verifier_env
*env
,
1830 const struct bpf_reg_state
*reg
,
1831 enum bpf_reg_type type
)
1833 bool known
= tnum_is_const(reg
->var_off
);
1834 s64 val
= reg
->var_off
.value
;
1835 s64 smin
= reg
->smin_value
;
1837 if (known
&& (val
>= BPF_MAX_VAR_OFF
|| val
<= -BPF_MAX_VAR_OFF
)) {
1838 verbose(env
, "math between %s pointer and %lld is not allowed\n",
1839 reg_type_str
[type
], val
);
1843 if (reg
->off
>= BPF_MAX_VAR_OFF
|| reg
->off
<= -BPF_MAX_VAR_OFF
) {
1844 verbose(env
, "%s pointer offset %d is not allowed\n",
1845 reg_type_str
[type
], reg
->off
);
1849 if (smin
== S64_MIN
) {
1850 verbose(env
, "math between %s pointer and register with unbounded min value is not allowed\n",
1851 reg_type_str
[type
]);
1855 if (smin
>= BPF_MAX_VAR_OFF
|| smin
<= -BPF_MAX_VAR_OFF
) {
1856 verbose(env
, "value %lld makes %s pointer be out of bounds\n",
1857 smin
, reg_type_str
[type
]);
1864 /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
1865 * Caller should also handle BPF_MOV case separately.
1866 * If we return -EACCES, caller may want to try again treating pointer as a
1867 * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
1869 static int adjust_ptr_min_max_vals(struct bpf_verifier_env
*env
,
1870 struct bpf_insn
*insn
,
1871 const struct bpf_reg_state
*ptr_reg
,
1872 const struct bpf_reg_state
*off_reg
)
1874 struct bpf_reg_state
*regs
= cur_regs(env
), *dst_reg
;
1875 bool known
= tnum_is_const(off_reg
->var_off
);
1876 s64 smin_val
= off_reg
->smin_value
, smax_val
= off_reg
->smax_value
,
1877 smin_ptr
= ptr_reg
->smin_value
, smax_ptr
= ptr_reg
->smax_value
;
1878 u64 umin_val
= off_reg
->umin_value
, umax_val
= off_reg
->umax_value
,
1879 umin_ptr
= ptr_reg
->umin_value
, umax_ptr
= ptr_reg
->umax_value
;
1880 u8 opcode
= BPF_OP(insn
->code
);
1881 u32 dst
= insn
->dst_reg
;
1883 dst_reg
= ®s
[dst
];
1885 if (WARN_ON_ONCE(known
&& (smin_val
!= smax_val
))) {
1886 print_verifier_state(env
, env
->cur_state
);
1888 "verifier internal error: known but bad sbounds\n");
1891 if (WARN_ON_ONCE(known
&& (umin_val
!= umax_val
))) {
1892 print_verifier_state(env
, env
->cur_state
);
1894 "verifier internal error: known but bad ubounds\n");
1898 if (BPF_CLASS(insn
->code
) != BPF_ALU64
) {
1899 /* 32-bit ALU ops on pointers produce (meaningless) scalars */
1901 "R%d 32-bit pointer arithmetic prohibited\n",
1906 if (ptr_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
1907 verbose(env
, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n",
1911 if (ptr_reg
->type
== CONST_PTR_TO_MAP
) {
1912 verbose(env
, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n",
1916 if (ptr_reg
->type
== PTR_TO_PACKET_END
) {
1917 verbose(env
, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n",
1922 /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
1923 * The id may be overwritten later if we create a new variable offset.
1925 dst_reg
->type
= ptr_reg
->type
;
1926 dst_reg
->id
= ptr_reg
->id
;
1928 if (!check_reg_sane_offset(env
, off_reg
, ptr_reg
->type
) ||
1929 !check_reg_sane_offset(env
, ptr_reg
, ptr_reg
->type
))
1934 /* We can take a fixed offset as long as it doesn't overflow
1935 * the s32 'off' field
1937 if (known
&& (ptr_reg
->off
+ smin_val
==
1938 (s64
)(s32
)(ptr_reg
->off
+ smin_val
))) {
1939 /* pointer += K. Accumulate it into fixed offset */
1940 dst_reg
->smin_value
= smin_ptr
;
1941 dst_reg
->smax_value
= smax_ptr
;
1942 dst_reg
->umin_value
= umin_ptr
;
1943 dst_reg
->umax_value
= umax_ptr
;
1944 dst_reg
->var_off
= ptr_reg
->var_off
;
1945 dst_reg
->off
= ptr_reg
->off
+ smin_val
;
1946 dst_reg
->range
= ptr_reg
->range
;
1949 /* A new variable offset is created. Note that off_reg->off
1950 * == 0, since it's a scalar.
1951 * dst_reg gets the pointer type and since some positive
1952 * integer value was added to the pointer, give it a new 'id'
1953 * if it's a PTR_TO_PACKET.
1954 * this creates a new 'base' pointer, off_reg (variable) gets
1955 * added into the variable offset, and we copy the fixed offset
1958 if (signed_add_overflows(smin_ptr
, smin_val
) ||
1959 signed_add_overflows(smax_ptr
, smax_val
)) {
1960 dst_reg
->smin_value
= S64_MIN
;
1961 dst_reg
->smax_value
= S64_MAX
;
1963 dst_reg
->smin_value
= smin_ptr
+ smin_val
;
1964 dst_reg
->smax_value
= smax_ptr
+ smax_val
;
1966 if (umin_ptr
+ umin_val
< umin_ptr
||
1967 umax_ptr
+ umax_val
< umax_ptr
) {
1968 dst_reg
->umin_value
= 0;
1969 dst_reg
->umax_value
= U64_MAX
;
1971 dst_reg
->umin_value
= umin_ptr
+ umin_val
;
1972 dst_reg
->umax_value
= umax_ptr
+ umax_val
;
1974 dst_reg
->var_off
= tnum_add(ptr_reg
->var_off
, off_reg
->var_off
);
1975 dst_reg
->off
= ptr_reg
->off
;
1976 if (reg_is_pkt_pointer(ptr_reg
)) {
1977 dst_reg
->id
= ++env
->id_gen
;
1978 /* something was added to pkt_ptr, set range to zero */
1983 if (dst_reg
== off_reg
) {
1984 /* scalar -= pointer. Creates an unknown scalar */
1985 verbose(env
, "R%d tried to subtract pointer from scalar\n",
1989 /* We don't allow subtraction from FP, because (according to
1990 * test_verifier.c test "invalid fp arithmetic", JITs might not
1991 * be able to deal with it.
1993 if (ptr_reg
->type
== PTR_TO_STACK
) {
1994 verbose(env
, "R%d subtraction from stack pointer prohibited\n",
1998 if (known
&& (ptr_reg
->off
- smin_val
==
1999 (s64
)(s32
)(ptr_reg
->off
- smin_val
))) {
2000 /* pointer -= K. Subtract it from fixed offset */
2001 dst_reg
->smin_value
= smin_ptr
;
2002 dst_reg
->smax_value
= smax_ptr
;
2003 dst_reg
->umin_value
= umin_ptr
;
2004 dst_reg
->umax_value
= umax_ptr
;
2005 dst_reg
->var_off
= ptr_reg
->var_off
;
2006 dst_reg
->id
= ptr_reg
->id
;
2007 dst_reg
->off
= ptr_reg
->off
- smin_val
;
2008 dst_reg
->range
= ptr_reg
->range
;
2011 /* A new variable offset is created. If the subtrahend is known
2012 * nonnegative, then any reg->range we had before is still good.
2014 if (signed_sub_overflows(smin_ptr
, smax_val
) ||
2015 signed_sub_overflows(smax_ptr
, smin_val
)) {
2016 /* Overflow possible, we know nothing */
2017 dst_reg
->smin_value
= S64_MIN
;
2018 dst_reg
->smax_value
= S64_MAX
;
2020 dst_reg
->smin_value
= smin_ptr
- smax_val
;
2021 dst_reg
->smax_value
= smax_ptr
- smin_val
;
2023 if (umin_ptr
< umax_val
) {
2024 /* Overflow possible, we know nothing */
2025 dst_reg
->umin_value
= 0;
2026 dst_reg
->umax_value
= U64_MAX
;
2028 /* Cannot overflow (as long as bounds are consistent) */
2029 dst_reg
->umin_value
= umin_ptr
- umax_val
;
2030 dst_reg
->umax_value
= umax_ptr
- umin_val
;
2032 dst_reg
->var_off
= tnum_sub(ptr_reg
->var_off
, off_reg
->var_off
);
2033 dst_reg
->off
= ptr_reg
->off
;
2034 if (reg_is_pkt_pointer(ptr_reg
)) {
2035 dst_reg
->id
= ++env
->id_gen
;
2036 /* something was added to pkt_ptr, set range to zero */
2044 /* bitwise ops on pointers are troublesome, prohibit. */
2045 verbose(env
, "R%d bitwise operator %s on pointer prohibited\n",
2046 dst
, bpf_alu_string
[opcode
>> 4]);
2049 /* other operators (e.g. MUL,LSH) produce non-pointer results */
2050 verbose(env
, "R%d pointer arithmetic with %s operator prohibited\n",
2051 dst
, bpf_alu_string
[opcode
>> 4]);
2055 if (!check_reg_sane_offset(env
, dst_reg
, ptr_reg
->type
))
2058 __update_reg_bounds(dst_reg
);
2059 __reg_deduce_bounds(dst_reg
);
2060 __reg_bound_offset(dst_reg
);
2064 /* WARNING: This function does calculations on 64-bit values, but the actual
2065 * execution may occur on 32-bit values. Therefore, things like bitshifts
2066 * need extra checks in the 32-bit case.
2068 static int adjust_scalar_min_max_vals(struct bpf_verifier_env
*env
,
2069 struct bpf_insn
*insn
,
2070 struct bpf_reg_state
*dst_reg
,
2071 struct bpf_reg_state src_reg
)
2073 struct bpf_reg_state
*regs
= cur_regs(env
);
2074 u8 opcode
= BPF_OP(insn
->code
);
2075 bool src_known
, dst_known
;
2076 s64 smin_val
, smax_val
;
2077 u64 umin_val
, umax_val
;
2078 u64 insn_bitness
= (BPF_CLASS(insn
->code
) == BPF_ALU64
) ? 64 : 32;
2080 smin_val
= src_reg
.smin_value
;
2081 smax_val
= src_reg
.smax_value
;
2082 umin_val
= src_reg
.umin_value
;
2083 umax_val
= src_reg
.umax_value
;
2084 src_known
= tnum_is_const(src_reg
.var_off
);
2085 dst_known
= tnum_is_const(dst_reg
->var_off
);
2088 opcode
!= BPF_ADD
&& opcode
!= BPF_SUB
&& opcode
!= BPF_AND
) {
2089 __mark_reg_unknown(dst_reg
);
2095 if (signed_add_overflows(dst_reg
->smin_value
, smin_val
) ||
2096 signed_add_overflows(dst_reg
->smax_value
, smax_val
)) {
2097 dst_reg
->smin_value
= S64_MIN
;
2098 dst_reg
->smax_value
= S64_MAX
;
2100 dst_reg
->smin_value
+= smin_val
;
2101 dst_reg
->smax_value
+= smax_val
;
2103 if (dst_reg
->umin_value
+ umin_val
< umin_val
||
2104 dst_reg
->umax_value
+ umax_val
< umax_val
) {
2105 dst_reg
->umin_value
= 0;
2106 dst_reg
->umax_value
= U64_MAX
;
2108 dst_reg
->umin_value
+= umin_val
;
2109 dst_reg
->umax_value
+= umax_val
;
2111 dst_reg
->var_off
= tnum_add(dst_reg
->var_off
, src_reg
.var_off
);
2114 if (signed_sub_overflows(dst_reg
->smin_value
, smax_val
) ||
2115 signed_sub_overflows(dst_reg
->smax_value
, smin_val
)) {
2116 /* Overflow possible, we know nothing */
2117 dst_reg
->smin_value
= S64_MIN
;
2118 dst_reg
->smax_value
= S64_MAX
;
2120 dst_reg
->smin_value
-= smax_val
;
2121 dst_reg
->smax_value
-= smin_val
;
2123 if (dst_reg
->umin_value
< umax_val
) {
2124 /* Overflow possible, we know nothing */
2125 dst_reg
->umin_value
= 0;
2126 dst_reg
->umax_value
= U64_MAX
;
2128 /* Cannot overflow (as long as bounds are consistent) */
2129 dst_reg
->umin_value
-= umax_val
;
2130 dst_reg
->umax_value
-= umin_val
;
2132 dst_reg
->var_off
= tnum_sub(dst_reg
->var_off
, src_reg
.var_off
);
2135 dst_reg
->var_off
= tnum_mul(dst_reg
->var_off
, src_reg
.var_off
);
2136 if (smin_val
< 0 || dst_reg
->smin_value
< 0) {
2137 /* Ain't nobody got time to multiply that sign */
2138 __mark_reg_unbounded(dst_reg
);
2139 __update_reg_bounds(dst_reg
);
2142 /* Both values are positive, so we can work with unsigned and
2143 * copy the result to signed (unless it exceeds S64_MAX).
2145 if (umax_val
> U32_MAX
|| dst_reg
->umax_value
> U32_MAX
) {
2146 /* Potential overflow, we know nothing */
2147 __mark_reg_unbounded(dst_reg
);
2148 /* (except what we can learn from the var_off) */
2149 __update_reg_bounds(dst_reg
);
2152 dst_reg
->umin_value
*= umin_val
;
2153 dst_reg
->umax_value
*= umax_val
;
2154 if (dst_reg
->umax_value
> S64_MAX
) {
2155 /* Overflow possible, we know nothing */
2156 dst_reg
->smin_value
= S64_MIN
;
2157 dst_reg
->smax_value
= S64_MAX
;
2159 dst_reg
->smin_value
= dst_reg
->umin_value
;
2160 dst_reg
->smax_value
= dst_reg
->umax_value
;
2164 if (src_known
&& dst_known
) {
2165 __mark_reg_known(dst_reg
, dst_reg
->var_off
.value
&
2166 src_reg
.var_off
.value
);
2169 /* We get our minimum from the var_off, since that's inherently
2170 * bitwise. Our maximum is the minimum of the operands' maxima.
2172 dst_reg
->var_off
= tnum_and(dst_reg
->var_off
, src_reg
.var_off
);
2173 dst_reg
->umin_value
= dst_reg
->var_off
.value
;
2174 dst_reg
->umax_value
= min(dst_reg
->umax_value
, umax_val
);
2175 if (dst_reg
->smin_value
< 0 || smin_val
< 0) {
2176 /* Lose signed bounds when ANDing negative numbers,
2177 * ain't nobody got time for that.
2179 dst_reg
->smin_value
= S64_MIN
;
2180 dst_reg
->smax_value
= S64_MAX
;
2182 /* ANDing two positives gives a positive, so safe to
2183 * cast result into s64.
2185 dst_reg
->smin_value
= dst_reg
->umin_value
;
2186 dst_reg
->smax_value
= dst_reg
->umax_value
;
2188 /* We may learn something more from the var_off */
2189 __update_reg_bounds(dst_reg
);
2192 if (src_known
&& dst_known
) {
2193 __mark_reg_known(dst_reg
, dst_reg
->var_off
.value
|
2194 src_reg
.var_off
.value
);
2197 /* We get our maximum from the var_off, and our minimum is the
2198 * maximum of the operands' minima
2200 dst_reg
->var_off
= tnum_or(dst_reg
->var_off
, src_reg
.var_off
);
2201 dst_reg
->umin_value
= max(dst_reg
->umin_value
, umin_val
);
2202 dst_reg
->umax_value
= dst_reg
->var_off
.value
|
2203 dst_reg
->var_off
.mask
;
2204 if (dst_reg
->smin_value
< 0 || smin_val
< 0) {
2205 /* Lose signed bounds when ORing negative numbers,
2206 * ain't nobody got time for that.
2208 dst_reg
->smin_value
= S64_MIN
;
2209 dst_reg
->smax_value
= S64_MAX
;
2211 /* ORing two positives gives a positive, so safe to
2212 * cast result into s64.
2214 dst_reg
->smin_value
= dst_reg
->umin_value
;
2215 dst_reg
->smax_value
= dst_reg
->umax_value
;
2217 /* We may learn something more from the var_off */
2218 __update_reg_bounds(dst_reg
);
2221 if (umax_val
>= insn_bitness
) {
2222 /* Shifts greater than 31 or 63 are undefined.
2223 * This includes shifts by a negative number.
2225 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2228 /* We lose all sign bit information (except what we can pick
2231 dst_reg
->smin_value
= S64_MIN
;
2232 dst_reg
->smax_value
= S64_MAX
;
2233 /* If we might shift our top bit out, then we know nothing */
2234 if (dst_reg
->umax_value
> 1ULL << (63 - umax_val
)) {
2235 dst_reg
->umin_value
= 0;
2236 dst_reg
->umax_value
= U64_MAX
;
2238 dst_reg
->umin_value
<<= umin_val
;
2239 dst_reg
->umax_value
<<= umax_val
;
2242 dst_reg
->var_off
= tnum_lshift(dst_reg
->var_off
, umin_val
);
2244 dst_reg
->var_off
= tnum_lshift(tnum_unknown
, umin_val
);
2245 /* We may learn something more from the var_off */
2246 __update_reg_bounds(dst_reg
);
2249 if (umax_val
>= insn_bitness
) {
2250 /* Shifts greater than 31 or 63 are undefined.
2251 * This includes shifts by a negative number.
2253 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2256 /* BPF_RSH is an unsigned shift. If the value in dst_reg might
2257 * be negative, then either:
2258 * 1) src_reg might be zero, so the sign bit of the result is
2259 * unknown, so we lose our signed bounds
2260 * 2) it's known negative, thus the unsigned bounds capture the
2262 * 3) the signed bounds cross zero, so they tell us nothing
2264 * If the value in dst_reg is known nonnegative, then again the
2265 * unsigned bounts capture the signed bounds.
2266 * Thus, in all cases it suffices to blow away our signed bounds
2267 * and rely on inferring new ones from the unsigned bounds and
2268 * var_off of the result.
2270 dst_reg
->smin_value
= S64_MIN
;
2271 dst_reg
->smax_value
= S64_MAX
;
2273 dst_reg
->var_off
= tnum_rshift(dst_reg
->var_off
,
2276 dst_reg
->var_off
= tnum_rshift(tnum_unknown
, umin_val
);
2277 dst_reg
->umin_value
>>= umax_val
;
2278 dst_reg
->umax_value
>>= umin_val
;
2279 /* We may learn something more from the var_off */
2280 __update_reg_bounds(dst_reg
);
2283 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2287 if (BPF_CLASS(insn
->code
) != BPF_ALU64
) {
2288 /* 32-bit ALU ops are (32,32)->32 */
2289 coerce_reg_to_size(dst_reg
, 4);
2290 coerce_reg_to_size(&src_reg
, 4);
2293 __reg_deduce_bounds(dst_reg
);
2294 __reg_bound_offset(dst_reg
);
2298 /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
2301 static int adjust_reg_min_max_vals(struct bpf_verifier_env
*env
,
2302 struct bpf_insn
*insn
)
2304 struct bpf_reg_state
*regs
= cur_regs(env
), *dst_reg
, *src_reg
;
2305 struct bpf_reg_state
*ptr_reg
= NULL
, off_reg
= {0};
2306 u8 opcode
= BPF_OP(insn
->code
);
2308 dst_reg
= ®s
[insn
->dst_reg
];
2310 if (dst_reg
->type
!= SCALAR_VALUE
)
2312 if (BPF_SRC(insn
->code
) == BPF_X
) {
2313 src_reg
= ®s
[insn
->src_reg
];
2314 if (src_reg
->type
!= SCALAR_VALUE
) {
2315 if (dst_reg
->type
!= SCALAR_VALUE
) {
2316 /* Combining two pointers by any ALU op yields
2317 * an arbitrary scalar. Disallow all math except
2318 * pointer subtraction
2320 if (opcode
== BPF_SUB
){
2321 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2324 verbose(env
, "R%d pointer %s pointer prohibited\n",
2326 bpf_alu_string
[opcode
>> 4]);
2329 /* scalar += pointer
2330 * This is legal, but we have to reverse our
2331 * src/dest handling in computing the range
2333 return adjust_ptr_min_max_vals(env
, insn
,
2336 } else if (ptr_reg
) {
2337 /* pointer += scalar */
2338 return adjust_ptr_min_max_vals(env
, insn
,
2342 /* Pretend the src is a reg with a known value, since we only
2343 * need to be able to read from this state.
2345 off_reg
.type
= SCALAR_VALUE
;
2346 __mark_reg_known(&off_reg
, insn
->imm
);
2348 if (ptr_reg
) /* pointer += K */
2349 return adjust_ptr_min_max_vals(env
, insn
,
2353 /* Got here implies adding two SCALAR_VALUEs */
2354 if (WARN_ON_ONCE(ptr_reg
)) {
2355 print_verifier_state(env
, env
->cur_state
);
2356 verbose(env
, "verifier internal error: unexpected ptr_reg\n");
2359 if (WARN_ON(!src_reg
)) {
2360 print_verifier_state(env
, env
->cur_state
);
2361 verbose(env
, "verifier internal error: no src_reg\n");
2364 return adjust_scalar_min_max_vals(env
, insn
, dst_reg
, *src_reg
);
2367 /* check validity of 32-bit and 64-bit arithmetic operations */
2368 static int check_alu_op(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
2370 struct bpf_reg_state
*regs
= cur_regs(env
);
2371 u8 opcode
= BPF_OP(insn
->code
);
2374 if (opcode
== BPF_END
|| opcode
== BPF_NEG
) {
2375 if (opcode
== BPF_NEG
) {
2376 if (BPF_SRC(insn
->code
) != 0 ||
2377 insn
->src_reg
!= BPF_REG_0
||
2378 insn
->off
!= 0 || insn
->imm
!= 0) {
2379 verbose(env
, "BPF_NEG uses reserved fields\n");
2383 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
2384 (insn
->imm
!= 16 && insn
->imm
!= 32 && insn
->imm
!= 64) ||
2385 BPF_CLASS(insn
->code
) == BPF_ALU64
) {
2386 verbose(env
, "BPF_END uses reserved fields\n");
2391 /* check src operand */
2392 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
2396 if (is_pointer_value(env
, insn
->dst_reg
)) {
2397 verbose(env
, "R%d pointer arithmetic prohibited\n",
2402 /* check dest operand */
2403 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
2407 } else if (opcode
== BPF_MOV
) {
2409 if (BPF_SRC(insn
->code
) == BPF_X
) {
2410 if (insn
->imm
!= 0 || insn
->off
!= 0) {
2411 verbose(env
, "BPF_MOV uses reserved fields\n");
2415 /* check src operand */
2416 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
2420 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
2421 verbose(env
, "BPF_MOV uses reserved fields\n");
2426 /* check dest operand */
2427 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
2431 if (BPF_SRC(insn
->code
) == BPF_X
) {
2432 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
2434 * copy register state to dest reg
2436 regs
[insn
->dst_reg
] = regs
[insn
->src_reg
];
2437 regs
[insn
->dst_reg
].live
|= REG_LIVE_WRITTEN
;
2440 if (is_pointer_value(env
, insn
->src_reg
)) {
2442 "R%d partial copy of pointer\n",
2446 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2447 coerce_reg_to_size(®s
[insn
->dst_reg
], 4);
2451 * remember the value we stored into this reg
2453 regs
[insn
->dst_reg
].type
= SCALAR_VALUE
;
2454 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
2455 __mark_reg_known(regs
+ insn
->dst_reg
,
2458 __mark_reg_known(regs
+ insn
->dst_reg
,
2463 } else if (opcode
> BPF_END
) {
2464 verbose(env
, "invalid BPF_ALU opcode %x\n", opcode
);
2467 } else { /* all other ALU ops: and, sub, xor, add, ... */
2469 if (BPF_SRC(insn
->code
) == BPF_X
) {
2470 if (insn
->imm
!= 0 || insn
->off
!= 0) {
2471 verbose(env
, "BPF_ALU uses reserved fields\n");
2474 /* check src1 operand */
2475 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
2479 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
2480 verbose(env
, "BPF_ALU uses reserved fields\n");
2485 /* check src2 operand */
2486 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
2490 if ((opcode
== BPF_MOD
|| opcode
== BPF_DIV
) &&
2491 BPF_SRC(insn
->code
) == BPF_K
&& insn
->imm
== 0) {
2492 verbose(env
, "div by zero\n");
2496 if (opcode
== BPF_ARSH
&& BPF_CLASS(insn
->code
) != BPF_ALU64
) {
2497 verbose(env
, "BPF_ARSH not supported for 32 bit ALU\n");
2501 if ((opcode
== BPF_LSH
|| opcode
== BPF_RSH
||
2502 opcode
== BPF_ARSH
) && BPF_SRC(insn
->code
) == BPF_K
) {
2503 int size
= BPF_CLASS(insn
->code
) == BPF_ALU64
? 64 : 32;
2505 if (insn
->imm
< 0 || insn
->imm
>= size
) {
2506 verbose(env
, "invalid shift %d\n", insn
->imm
);
2511 /* check dest operand */
2512 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP_NO_MARK
);
2516 return adjust_reg_min_max_vals(env
, insn
);
2522 static void find_good_pkt_pointers(struct bpf_verifier_state
*state
,
2523 struct bpf_reg_state
*dst_reg
,
2524 enum bpf_reg_type type
,
2525 bool range_right_open
)
2527 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
2531 if (dst_reg
->off
< 0 ||
2532 (dst_reg
->off
== 0 && range_right_open
))
2533 /* This doesn't give us any range */
2536 if (dst_reg
->umax_value
> MAX_PACKET_OFF
||
2537 dst_reg
->umax_value
+ dst_reg
->off
> MAX_PACKET_OFF
)
2538 /* Risk of overflow. For instance, ptr + (1<<63) may be less
2539 * than pkt_end, but that's because it's also less than pkt.
2543 new_range
= dst_reg
->off
;
2544 if (range_right_open
)
2547 /* Examples for register markings:
2549 * pkt_data in dst register:
2553 * if (r2 > pkt_end) goto <handle exception>
2558 * if (r2 < pkt_end) goto <access okay>
2559 * <handle exception>
2562 * r2 == dst_reg, pkt_end == src_reg
2563 * r2=pkt(id=n,off=8,r=0)
2564 * r3=pkt(id=n,off=0,r=0)
2566 * pkt_data in src register:
2570 * if (pkt_end >= r2) goto <access okay>
2571 * <handle exception>
2575 * if (pkt_end <= r2) goto <handle exception>
2579 * pkt_end == dst_reg, r2 == src_reg
2580 * r2=pkt(id=n,off=8,r=0)
2581 * r3=pkt(id=n,off=0,r=0)
2583 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
2584 * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
2585 * and [r3, r3 + 8-1) respectively is safe to access depending on
2589 /* If our ids match, then we must have the same max_value. And we
2590 * don't care about the other reg's fixed offset, since if it's too big
2591 * the range won't allow anything.
2592 * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
2594 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2595 if (regs
[i
].type
== type
&& regs
[i
].id
== dst_reg
->id
)
2596 /* keep the maximum range already checked */
2597 regs
[i
].range
= max(regs
[i
].range
, new_range
);
2599 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
2600 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
2602 reg
= &state
->stack
[i
].spilled_ptr
;
2603 if (reg
->type
== type
&& reg
->id
== dst_reg
->id
)
2604 reg
->range
= max(reg
->range
, new_range
);
2608 /* Adjusts the register min/max values in the case that the dst_reg is the
2609 * variable register that we are working on, and src_reg is a constant or we're
2610 * simply doing a BPF_K check.
2611 * In JEQ/JNE cases we also adjust the var_off values.
2613 static void reg_set_min_max(struct bpf_reg_state
*true_reg
,
2614 struct bpf_reg_state
*false_reg
, u64 val
,
2617 /* If the dst_reg is a pointer, we can't learn anything about its
2618 * variable offset from the compare (unless src_reg were a pointer into
2619 * the same object, but we don't bother with that.
2620 * Since false_reg and true_reg have the same type by construction, we
2621 * only need to check one of them for pointerness.
2623 if (__is_pointer_value(false, false_reg
))
2628 /* If this is false then we know nothing Jon Snow, but if it is
2629 * true then we know for sure.
2631 __mark_reg_known(true_reg
, val
);
2634 /* If this is true we know nothing Jon Snow, but if it is false
2635 * we know the value for sure;
2637 __mark_reg_known(false_reg
, val
);
2640 false_reg
->umax_value
= min(false_reg
->umax_value
, val
);
2641 true_reg
->umin_value
= max(true_reg
->umin_value
, val
+ 1);
2644 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
);
2645 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
+ 1);
2648 false_reg
->umin_value
= max(false_reg
->umin_value
, val
);
2649 true_reg
->umax_value
= min(true_reg
->umax_value
, val
- 1);
2652 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
);
2653 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
- 1);
2656 false_reg
->umax_value
= min(false_reg
->umax_value
, val
- 1);
2657 true_reg
->umin_value
= max(true_reg
->umin_value
, val
);
2660 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
- 1);
2661 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
);
2664 false_reg
->umin_value
= max(false_reg
->umin_value
, val
+ 1);
2665 true_reg
->umax_value
= min(true_reg
->umax_value
, val
);
2668 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
+ 1);
2669 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
);
2675 __reg_deduce_bounds(false_reg
);
2676 __reg_deduce_bounds(true_reg
);
2677 /* We might have learned some bits from the bounds. */
2678 __reg_bound_offset(false_reg
);
2679 __reg_bound_offset(true_reg
);
2680 /* Intersecting with the old var_off might have improved our bounds
2681 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
2682 * then new var_off is (0; 0x7f...fc) which improves our umax.
2684 __update_reg_bounds(false_reg
);
2685 __update_reg_bounds(true_reg
);
2688 /* Same as above, but for the case that dst_reg holds a constant and src_reg is
2691 static void reg_set_min_max_inv(struct bpf_reg_state
*true_reg
,
2692 struct bpf_reg_state
*false_reg
, u64 val
,
2695 if (__is_pointer_value(false, false_reg
))
2700 /* If this is false then we know nothing Jon Snow, but if it is
2701 * true then we know for sure.
2703 __mark_reg_known(true_reg
, val
);
2706 /* If this is true we know nothing Jon Snow, but if it is false
2707 * we know the value for sure;
2709 __mark_reg_known(false_reg
, val
);
2712 true_reg
->umax_value
= min(true_reg
->umax_value
, val
- 1);
2713 false_reg
->umin_value
= max(false_reg
->umin_value
, val
);
2716 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
- 1);
2717 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
);
2720 true_reg
->umin_value
= max(true_reg
->umin_value
, val
+ 1);
2721 false_reg
->umax_value
= min(false_reg
->umax_value
, val
);
2724 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
+ 1);
2725 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
);
2728 true_reg
->umax_value
= min(true_reg
->umax_value
, val
);
2729 false_reg
->umin_value
= max(false_reg
->umin_value
, val
+ 1);
2732 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
);
2733 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
+ 1);
2736 true_reg
->umin_value
= max(true_reg
->umin_value
, val
);
2737 false_reg
->umax_value
= min(false_reg
->umax_value
, val
- 1);
2740 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
);
2741 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
- 1);
2747 __reg_deduce_bounds(false_reg
);
2748 __reg_deduce_bounds(true_reg
);
2749 /* We might have learned some bits from the bounds. */
2750 __reg_bound_offset(false_reg
);
2751 __reg_bound_offset(true_reg
);
2752 /* Intersecting with the old var_off might have improved our bounds
2753 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
2754 * then new var_off is (0; 0x7f...fc) which improves our umax.
2756 __update_reg_bounds(false_reg
);
2757 __update_reg_bounds(true_reg
);
2760 /* Regs are known to be equal, so intersect their min/max/var_off */
2761 static void __reg_combine_min_max(struct bpf_reg_state
*src_reg
,
2762 struct bpf_reg_state
*dst_reg
)
2764 src_reg
->umin_value
= dst_reg
->umin_value
= max(src_reg
->umin_value
,
2765 dst_reg
->umin_value
);
2766 src_reg
->umax_value
= dst_reg
->umax_value
= min(src_reg
->umax_value
,
2767 dst_reg
->umax_value
);
2768 src_reg
->smin_value
= dst_reg
->smin_value
= max(src_reg
->smin_value
,
2769 dst_reg
->smin_value
);
2770 src_reg
->smax_value
= dst_reg
->smax_value
= min(src_reg
->smax_value
,
2771 dst_reg
->smax_value
);
2772 src_reg
->var_off
= dst_reg
->var_off
= tnum_intersect(src_reg
->var_off
,
2774 /* We might have learned new bounds from the var_off. */
2775 __update_reg_bounds(src_reg
);
2776 __update_reg_bounds(dst_reg
);
2777 /* We might have learned something about the sign bit. */
2778 __reg_deduce_bounds(src_reg
);
2779 __reg_deduce_bounds(dst_reg
);
2780 /* We might have learned some bits from the bounds. */
2781 __reg_bound_offset(src_reg
);
2782 __reg_bound_offset(dst_reg
);
2783 /* Intersecting with the old var_off might have improved our bounds
2784 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
2785 * then new var_off is (0; 0x7f...fc) which improves our umax.
2787 __update_reg_bounds(src_reg
);
2788 __update_reg_bounds(dst_reg
);
2791 static void reg_combine_min_max(struct bpf_reg_state
*true_src
,
2792 struct bpf_reg_state
*true_dst
,
2793 struct bpf_reg_state
*false_src
,
2794 struct bpf_reg_state
*false_dst
,
2799 __reg_combine_min_max(true_src
, true_dst
);
2802 __reg_combine_min_max(false_src
, false_dst
);
2807 static void mark_map_reg(struct bpf_reg_state
*regs
, u32 regno
, u32 id
,
2810 struct bpf_reg_state
*reg
= ®s
[regno
];
2812 if (reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
&& reg
->id
== id
) {
2813 /* Old offset (both fixed and variable parts) should
2814 * have been known-zero, because we don't allow pointer
2815 * arithmetic on pointers that might be NULL.
2817 if (WARN_ON_ONCE(reg
->smin_value
|| reg
->smax_value
||
2818 !tnum_equals_const(reg
->var_off
, 0) ||
2820 __mark_reg_known_zero(reg
);
2824 reg
->type
= SCALAR_VALUE
;
2825 } else if (reg
->map_ptr
->inner_map_meta
) {
2826 reg
->type
= CONST_PTR_TO_MAP
;
2827 reg
->map_ptr
= reg
->map_ptr
->inner_map_meta
;
2829 reg
->type
= PTR_TO_MAP_VALUE
;
2831 /* We don't need id from this point onwards anymore, thus we
2832 * should better reset it, so that state pruning has chances
2839 /* The logic is similar to find_good_pkt_pointers(), both could eventually
2840 * be folded together at some point.
2842 static void mark_map_regs(struct bpf_verifier_state
*state
, u32 regno
,
2845 struct bpf_reg_state
*regs
= state
->regs
;
2846 u32 id
= regs
[regno
].id
;
2849 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2850 mark_map_reg(regs
, i
, id
, is_null
);
2852 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
2853 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
2855 mark_map_reg(&state
->stack
[i
].spilled_ptr
, 0, id
, is_null
);
2859 static bool try_match_pkt_pointers(const struct bpf_insn
*insn
,
2860 struct bpf_reg_state
*dst_reg
,
2861 struct bpf_reg_state
*src_reg
,
2862 struct bpf_verifier_state
*this_branch
,
2863 struct bpf_verifier_state
*other_branch
)
2865 if (BPF_SRC(insn
->code
) != BPF_X
)
2868 switch (BPF_OP(insn
->code
)) {
2870 if ((dst_reg
->type
== PTR_TO_PACKET
&&
2871 src_reg
->type
== PTR_TO_PACKET_END
) ||
2872 (dst_reg
->type
== PTR_TO_PACKET_META
&&
2873 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
2874 /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
2875 find_good_pkt_pointers(this_branch
, dst_reg
,
2876 dst_reg
->type
, false);
2877 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
2878 src_reg
->type
== PTR_TO_PACKET
) ||
2879 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
2880 src_reg
->type
== PTR_TO_PACKET_META
)) {
2881 /* pkt_end > pkt_data', pkt_data > pkt_meta' */
2882 find_good_pkt_pointers(other_branch
, src_reg
,
2883 src_reg
->type
, true);
2889 if ((dst_reg
->type
== PTR_TO_PACKET
&&
2890 src_reg
->type
== PTR_TO_PACKET_END
) ||
2891 (dst_reg
->type
== PTR_TO_PACKET_META
&&
2892 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
2893 /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
2894 find_good_pkt_pointers(other_branch
, dst_reg
,
2895 dst_reg
->type
, true);
2896 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
2897 src_reg
->type
== PTR_TO_PACKET
) ||
2898 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
2899 src_reg
->type
== PTR_TO_PACKET_META
)) {
2900 /* pkt_end < pkt_data', pkt_data > pkt_meta' */
2901 find_good_pkt_pointers(this_branch
, src_reg
,
2902 src_reg
->type
, false);
2908 if ((dst_reg
->type
== PTR_TO_PACKET
&&
2909 src_reg
->type
== PTR_TO_PACKET_END
) ||
2910 (dst_reg
->type
== PTR_TO_PACKET_META
&&
2911 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
2912 /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
2913 find_good_pkt_pointers(this_branch
, dst_reg
,
2914 dst_reg
->type
, true);
2915 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
2916 src_reg
->type
== PTR_TO_PACKET
) ||
2917 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
2918 src_reg
->type
== PTR_TO_PACKET_META
)) {
2919 /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
2920 find_good_pkt_pointers(other_branch
, src_reg
,
2921 src_reg
->type
, false);
2927 if ((dst_reg
->type
== PTR_TO_PACKET
&&
2928 src_reg
->type
== PTR_TO_PACKET_END
) ||
2929 (dst_reg
->type
== PTR_TO_PACKET_META
&&
2930 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
2931 /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
2932 find_good_pkt_pointers(other_branch
, dst_reg
,
2933 dst_reg
->type
, false);
2934 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
2935 src_reg
->type
== PTR_TO_PACKET
) ||
2936 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
2937 src_reg
->type
== PTR_TO_PACKET_META
)) {
2938 /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
2939 find_good_pkt_pointers(this_branch
, src_reg
,
2940 src_reg
->type
, true);
2952 static int check_cond_jmp_op(struct bpf_verifier_env
*env
,
2953 struct bpf_insn
*insn
, int *insn_idx
)
2955 struct bpf_verifier_state
*other_branch
, *this_branch
= env
->cur_state
;
2956 struct bpf_reg_state
*regs
= this_branch
->regs
, *dst_reg
;
2957 u8 opcode
= BPF_OP(insn
->code
);
2960 if (opcode
> BPF_JSLE
) {
2961 verbose(env
, "invalid BPF_JMP opcode %x\n", opcode
);
2965 if (BPF_SRC(insn
->code
) == BPF_X
) {
2966 if (insn
->imm
!= 0) {
2967 verbose(env
, "BPF_JMP uses reserved fields\n");
2971 /* check src1 operand */
2972 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
2976 if (is_pointer_value(env
, insn
->src_reg
)) {
2977 verbose(env
, "R%d pointer comparison prohibited\n",
2982 if (insn
->src_reg
!= BPF_REG_0
) {
2983 verbose(env
, "BPF_JMP uses reserved fields\n");
2988 /* check src2 operand */
2989 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
2993 dst_reg
= ®s
[insn
->dst_reg
];
2995 /* detect if R == 0 where R was initialized to zero earlier */
2996 if (BPF_SRC(insn
->code
) == BPF_K
&&
2997 (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
2998 dst_reg
->type
== SCALAR_VALUE
&&
2999 tnum_equals_const(dst_reg
->var_off
, insn
->imm
)) {
3000 if (opcode
== BPF_JEQ
) {
3001 /* if (imm == imm) goto pc+off;
3002 * only follow the goto, ignore fall-through
3004 *insn_idx
+= insn
->off
;
3007 /* if (imm != imm) goto pc+off;
3008 * only follow fall-through branch, since
3009 * that's where the program will go
3015 other_branch
= push_stack(env
, *insn_idx
+ insn
->off
+ 1, *insn_idx
);
3019 /* detect if we are comparing against a constant value so we can adjust
3020 * our min/max values for our dst register.
3021 * this is only legit if both are scalars (or pointers to the same
3022 * object, I suppose, but we don't support that right now), because
3023 * otherwise the different base pointers mean the offsets aren't
3026 if (BPF_SRC(insn
->code
) == BPF_X
) {
3027 if (dst_reg
->type
== SCALAR_VALUE
&&
3028 regs
[insn
->src_reg
].type
== SCALAR_VALUE
) {
3029 if (tnum_is_const(regs
[insn
->src_reg
].var_off
))
3030 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
3031 dst_reg
, regs
[insn
->src_reg
].var_off
.value
,
3033 else if (tnum_is_const(dst_reg
->var_off
))
3034 reg_set_min_max_inv(&other_branch
->regs
[insn
->src_reg
],
3035 ®s
[insn
->src_reg
],
3036 dst_reg
->var_off
.value
, opcode
);
3037 else if (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
)
3038 /* Comparing for equality, we can combine knowledge */
3039 reg_combine_min_max(&other_branch
->regs
[insn
->src_reg
],
3040 &other_branch
->regs
[insn
->dst_reg
],
3041 ®s
[insn
->src_reg
],
3042 ®s
[insn
->dst_reg
], opcode
);
3044 } else if (dst_reg
->type
== SCALAR_VALUE
) {
3045 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
3046 dst_reg
, insn
->imm
, opcode
);
3049 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
3050 if (BPF_SRC(insn
->code
) == BPF_K
&&
3051 insn
->imm
== 0 && (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
3052 dst_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
3053 /* Mark all identical map registers in each branch as either
3054 * safe or unknown depending R == 0 or R != 0 conditional.
3056 mark_map_regs(this_branch
, insn
->dst_reg
, opcode
== BPF_JNE
);
3057 mark_map_regs(other_branch
, insn
->dst_reg
, opcode
== BPF_JEQ
);
3058 } else if (!try_match_pkt_pointers(insn
, dst_reg
, ®s
[insn
->src_reg
],
3059 this_branch
, other_branch
) &&
3060 is_pointer_value(env
, insn
->dst_reg
)) {
3061 verbose(env
, "R%d pointer comparison prohibited\n",
3066 print_verifier_state(env
, this_branch
);
3070 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
3071 static struct bpf_map
*ld_imm64_to_map_ptr(struct bpf_insn
*insn
)
3073 u64 imm64
= ((u64
) (u32
) insn
[0].imm
) | ((u64
) (u32
) insn
[1].imm
) << 32;
3075 return (struct bpf_map
*) (unsigned long) imm64
;
3078 /* verify BPF_LD_IMM64 instruction */
3079 static int check_ld_imm(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
3081 struct bpf_reg_state
*regs
= cur_regs(env
);
3084 if (BPF_SIZE(insn
->code
) != BPF_DW
) {
3085 verbose(env
, "invalid BPF_LD_IMM insn\n");
3088 if (insn
->off
!= 0) {
3089 verbose(env
, "BPF_LD_IMM64 uses reserved fields\n");
3093 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
3097 if (insn
->src_reg
== 0) {
3098 u64 imm
= ((u64
)(insn
+ 1)->imm
<< 32) | (u32
)insn
->imm
;
3100 regs
[insn
->dst_reg
].type
= SCALAR_VALUE
;
3101 __mark_reg_known(®s
[insn
->dst_reg
], imm
);
3105 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
3106 BUG_ON(insn
->src_reg
!= BPF_PSEUDO_MAP_FD
);
3108 regs
[insn
->dst_reg
].type
= CONST_PTR_TO_MAP
;
3109 regs
[insn
->dst_reg
].map_ptr
= ld_imm64_to_map_ptr(insn
);
3113 static bool may_access_skb(enum bpf_prog_type type
)
3116 case BPF_PROG_TYPE_SOCKET_FILTER
:
3117 case BPF_PROG_TYPE_SCHED_CLS
:
3118 case BPF_PROG_TYPE_SCHED_ACT
:
3125 /* verify safety of LD_ABS|LD_IND instructions:
3126 * - they can only appear in the programs where ctx == skb
3127 * - since they are wrappers of function calls, they scratch R1-R5 registers,
3128 * preserve R6-R9, and store return value into R0
3131 * ctx == skb == R6 == CTX
3134 * SRC == any register
3135 * IMM == 32-bit immediate
3138 * R0 - 8/16/32-bit skb data converted to cpu endianness
3140 static int check_ld_abs(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
3142 struct bpf_reg_state
*regs
= cur_regs(env
);
3143 u8 mode
= BPF_MODE(insn
->code
);
3146 if (!may_access_skb(env
->prog
->type
)) {
3147 verbose(env
, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
3151 if (insn
->dst_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
3152 BPF_SIZE(insn
->code
) == BPF_DW
||
3153 (mode
== BPF_ABS
&& insn
->src_reg
!= BPF_REG_0
)) {
3154 verbose(env
, "BPF_LD_[ABS|IND] uses reserved fields\n");
3158 /* check whether implicit source operand (register R6) is readable */
3159 err
= check_reg_arg(env
, BPF_REG_6
, SRC_OP
);
3163 if (regs
[BPF_REG_6
].type
!= PTR_TO_CTX
) {
3165 "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
3169 if (mode
== BPF_IND
) {
3170 /* check explicit source operand */
3171 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3176 /* reset caller saved regs to unreadable */
3177 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
3178 mark_reg_not_init(env
, regs
, caller_saved
[i
]);
3179 check_reg_arg(env
, caller_saved
[i
], DST_OP_NO_MARK
);
3182 /* mark destination R0 register as readable, since it contains
3183 * the value fetched from the packet.
3184 * Already marked as written above.
3186 mark_reg_unknown(env
, regs
, BPF_REG_0
);
3190 static int check_return_code(struct bpf_verifier_env
*env
)
3192 struct bpf_reg_state
*reg
;
3193 struct tnum range
= tnum_range(0, 1);
3195 switch (env
->prog
->type
) {
3196 case BPF_PROG_TYPE_CGROUP_SKB
:
3197 case BPF_PROG_TYPE_CGROUP_SOCK
:
3198 case BPF_PROG_TYPE_SOCK_OPS
:
3199 case BPF_PROG_TYPE_CGROUP_DEVICE
:
3205 reg
= cur_regs(env
) + BPF_REG_0
;
3206 if (reg
->type
!= SCALAR_VALUE
) {
3207 verbose(env
, "At program exit the register R0 is not a known value (%s)\n",
3208 reg_type_str
[reg
->type
]);
3212 if (!tnum_in(range
, reg
->var_off
)) {
3213 verbose(env
, "At program exit the register R0 ");
3214 if (!tnum_is_unknown(reg
->var_off
)) {
3217 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
3218 verbose(env
, "has value %s", tn_buf
);
3220 verbose(env
, "has unknown scalar value");
3222 verbose(env
, " should have been 0 or 1\n");
3228 /* non-recursive DFS pseudo code
3229 * 1 procedure DFS-iterative(G,v):
3230 * 2 label v as discovered
3231 * 3 let S be a stack
3233 * 5 while S is not empty
3235 * 7 if t is what we're looking for:
3237 * 9 for all edges e in G.adjacentEdges(t) do
3238 * 10 if edge e is already labelled
3239 * 11 continue with the next edge
3240 * 12 w <- G.adjacentVertex(t,e)
3241 * 13 if vertex w is not discovered and not explored
3242 * 14 label e as tree-edge
3243 * 15 label w as discovered
3246 * 18 else if vertex w is discovered
3247 * 19 label e as back-edge
3249 * 21 // vertex w is explored
3250 * 22 label e as forward- or cross-edge
3251 * 23 label t as explored
3256 * 0x11 - discovered and fall-through edge labelled
3257 * 0x12 - discovered and fall-through and branch edges labelled
3268 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
3270 static int *insn_stack
; /* stack of insns to process */
3271 static int cur_stack
; /* current stack index */
3272 static int *insn_state
;
3274 /* t, w, e - match pseudo-code above:
3275 * t - index of current instruction
3276 * w - next instruction
3279 static int push_insn(int t
, int w
, int e
, struct bpf_verifier_env
*env
)
3281 if (e
== FALLTHROUGH
&& insn_state
[t
] >= (DISCOVERED
| FALLTHROUGH
))
3284 if (e
== BRANCH
&& insn_state
[t
] >= (DISCOVERED
| BRANCH
))
3287 if (w
< 0 || w
>= env
->prog
->len
) {
3288 verbose(env
, "jump out of range from insn %d to %d\n", t
, w
);
3293 /* mark branch target for state pruning */
3294 env
->explored_states
[w
] = STATE_LIST_MARK
;
3296 if (insn_state
[w
] == 0) {
3298 insn_state
[t
] = DISCOVERED
| e
;
3299 insn_state
[w
] = DISCOVERED
;
3300 if (cur_stack
>= env
->prog
->len
)
3302 insn_stack
[cur_stack
++] = w
;
3304 } else if ((insn_state
[w
] & 0xF0) == DISCOVERED
) {
3305 verbose(env
, "back-edge from insn %d to %d\n", t
, w
);
3307 } else if (insn_state
[w
] == EXPLORED
) {
3308 /* forward- or cross-edge */
3309 insn_state
[t
] = DISCOVERED
| e
;
3311 verbose(env
, "insn state internal bug\n");
3317 /* non-recursive depth-first-search to detect loops in BPF program
3318 * loop == back-edge in directed graph
3320 static int check_cfg(struct bpf_verifier_env
*env
)
3322 struct bpf_insn
*insns
= env
->prog
->insnsi
;
3323 int insn_cnt
= env
->prog
->len
;
3327 insn_state
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
3331 insn_stack
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
3337 insn_state
[0] = DISCOVERED
; /* mark 1st insn as discovered */
3338 insn_stack
[0] = 0; /* 0 is the first instruction */
3344 t
= insn_stack
[cur_stack
- 1];
3346 if (BPF_CLASS(insns
[t
].code
) == BPF_JMP
) {
3347 u8 opcode
= BPF_OP(insns
[t
].code
);
3349 if (opcode
== BPF_EXIT
) {
3351 } else if (opcode
== BPF_CALL
) {
3352 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
3357 if (t
+ 1 < insn_cnt
)
3358 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
3359 } else if (opcode
== BPF_JA
) {
3360 if (BPF_SRC(insns
[t
].code
) != BPF_K
) {
3364 /* unconditional jump with single edge */
3365 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1,
3371 /* tell verifier to check for equivalent states
3372 * after every call and jump
3374 if (t
+ 1 < insn_cnt
)
3375 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
3377 /* conditional jump with two edges */
3378 env
->explored_states
[t
] = STATE_LIST_MARK
;
3379 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
3385 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1, BRANCH
, env
);
3392 /* all other non-branch instructions with single
3395 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
3403 insn_state
[t
] = EXPLORED
;
3404 if (cur_stack
-- <= 0) {
3405 verbose(env
, "pop stack internal bug\n");
3412 for (i
= 0; i
< insn_cnt
; i
++) {
3413 if (insn_state
[i
] != EXPLORED
) {
3414 verbose(env
, "unreachable insn %d\n", i
);
3419 ret
= 0; /* cfg looks good */
3427 /* check %cur's range satisfies %old's */
3428 static bool range_within(struct bpf_reg_state
*old
,
3429 struct bpf_reg_state
*cur
)
3431 return old
->umin_value
<= cur
->umin_value
&&
3432 old
->umax_value
>= cur
->umax_value
&&
3433 old
->smin_value
<= cur
->smin_value
&&
3434 old
->smax_value
>= cur
->smax_value
;
3437 /* Maximum number of register states that can exist at once */
3438 #define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE)
3444 /* If in the old state two registers had the same id, then they need to have
3445 * the same id in the new state as well. But that id could be different from
3446 * the old state, so we need to track the mapping from old to new ids.
3447 * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
3448 * regs with old id 5 must also have new id 9 for the new state to be safe. But
3449 * regs with a different old id could still have new id 9, we don't care about
3451 * So we look through our idmap to see if this old id has been seen before. If
3452 * so, we require the new id to match; otherwise, we add the id pair to the map.
3454 static bool check_ids(u32 old_id
, u32 cur_id
, struct idpair
*idmap
)
3458 for (i
= 0; i
< ID_MAP_SIZE
; i
++) {
3459 if (!idmap
[i
].old
) {
3460 /* Reached an empty slot; haven't seen this id before */
3461 idmap
[i
].old
= old_id
;
3462 idmap
[i
].cur
= cur_id
;
3465 if (idmap
[i
].old
== old_id
)
3466 return idmap
[i
].cur
== cur_id
;
3468 /* We ran out of idmap slots, which should be impossible */
3473 /* Returns true if (rold safe implies rcur safe) */
3474 static bool regsafe(struct bpf_reg_state
*rold
, struct bpf_reg_state
*rcur
,
3475 struct idpair
*idmap
)
3477 if (!(rold
->live
& REG_LIVE_READ
))
3478 /* explored state didn't use this */
3481 if (memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, live
)) == 0)
3484 if (rold
->type
== NOT_INIT
)
3485 /* explored state can't have used this */
3487 if (rcur
->type
== NOT_INIT
)
3489 switch (rold
->type
) {
3491 if (rcur
->type
== SCALAR_VALUE
) {
3492 /* new val must satisfy old val knowledge */
3493 return range_within(rold
, rcur
) &&
3494 tnum_in(rold
->var_off
, rcur
->var_off
);
3496 /* We're trying to use a pointer in place of a scalar.
3497 * Even if the scalar was unbounded, this could lead to
3498 * pointer leaks because scalars are allowed to leak
3499 * while pointers are not. We could make this safe in
3500 * special cases if root is calling us, but it's
3501 * probably not worth the hassle.
3505 case PTR_TO_MAP_VALUE
:
3506 /* If the new min/max/var_off satisfy the old ones and
3507 * everything else matches, we are OK.
3508 * We don't care about the 'id' value, because nothing
3509 * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL)
3511 return memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, id
)) == 0 &&
3512 range_within(rold
, rcur
) &&
3513 tnum_in(rold
->var_off
, rcur
->var_off
);
3514 case PTR_TO_MAP_VALUE_OR_NULL
:
3515 /* a PTR_TO_MAP_VALUE could be safe to use as a
3516 * PTR_TO_MAP_VALUE_OR_NULL into the same map.
3517 * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
3518 * checked, doing so could have affected others with the same
3519 * id, and we can't check for that because we lost the id when
3520 * we converted to a PTR_TO_MAP_VALUE.
3522 if (rcur
->type
!= PTR_TO_MAP_VALUE_OR_NULL
)
3524 if (memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, id
)))
3526 /* Check our ids match any regs they're supposed to */
3527 return check_ids(rold
->id
, rcur
->id
, idmap
);
3528 case PTR_TO_PACKET_META
:
3530 if (rcur
->type
!= rold
->type
)
3532 /* We must have at least as much range as the old ptr
3533 * did, so that any accesses which were safe before are
3534 * still safe. This is true even if old range < old off,
3535 * since someone could have accessed through (ptr - k), or
3536 * even done ptr -= k in a register, to get a safe access.
3538 if (rold
->range
> rcur
->range
)
3540 /* If the offsets don't match, we can't trust our alignment;
3541 * nor can we be sure that we won't fall out of range.
3543 if (rold
->off
!= rcur
->off
)
3545 /* id relations must be preserved */
3546 if (rold
->id
&& !check_ids(rold
->id
, rcur
->id
, idmap
))
3548 /* new val must satisfy old val knowledge */
3549 return range_within(rold
, rcur
) &&
3550 tnum_in(rold
->var_off
, rcur
->var_off
);
3552 case CONST_PTR_TO_MAP
:
3554 case PTR_TO_PACKET_END
:
3555 /* Only valid matches are exact, which memcmp() above
3556 * would have accepted
3559 /* Don't know what's going on, just say it's not safe */
3563 /* Shouldn't get here; if we do, say it's not safe */
3568 static bool stacksafe(struct bpf_verifier_state
*old
,
3569 struct bpf_verifier_state
*cur
,
3570 struct idpair
*idmap
)
3574 /* if explored stack has more populated slots than current stack
3575 * such stacks are not equivalent
3577 if (old
->allocated_stack
> cur
->allocated_stack
)
3580 /* walk slots of the explored stack and ignore any additional
3581 * slots in the current stack, since explored(safe) state
3584 for (i
= 0; i
< old
->allocated_stack
; i
++) {
3585 spi
= i
/ BPF_REG_SIZE
;
3587 if (old
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] == STACK_INVALID
)
3589 if (old
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] !=
3590 cur
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
])
3591 /* Ex: old explored (safe) state has STACK_SPILL in
3592 * this stack slot, but current has has STACK_MISC ->
3593 * this verifier states are not equivalent,
3594 * return false to continue verification of this path
3597 if (i
% BPF_REG_SIZE
)
3599 if (old
->stack
[spi
].slot_type
[0] != STACK_SPILL
)
3601 if (!regsafe(&old
->stack
[spi
].spilled_ptr
,
3602 &cur
->stack
[spi
].spilled_ptr
,
3604 /* when explored and current stack slot are both storing
3605 * spilled registers, check that stored pointers types
3606 * are the same as well.
3607 * Ex: explored safe path could have stored
3608 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
3609 * but current path has stored:
3610 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
3611 * such verifier states are not equivalent.
3612 * return false to continue verification of this path
3619 /* compare two verifier states
3621 * all states stored in state_list are known to be valid, since
3622 * verifier reached 'bpf_exit' instruction through them
3624 * this function is called when verifier exploring different branches of
3625 * execution popped from the state stack. If it sees an old state that has
3626 * more strict register state and more strict stack state then this execution
3627 * branch doesn't need to be explored further, since verifier already
3628 * concluded that more strict state leads to valid finish.
3630 * Therefore two states are equivalent if register state is more conservative
3631 * and explored stack state is more conservative than the current one.
3634 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
3635 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
3637 * In other words if current stack state (one being explored) has more
3638 * valid slots than old one that already passed validation, it means
3639 * the verifier can stop exploring and conclude that current state is valid too
3641 * Similarly with registers. If explored state has register type as invalid
3642 * whereas register type in current state is meaningful, it means that
3643 * the current state will reach 'bpf_exit' instruction safely
3645 static bool states_equal(struct bpf_verifier_env
*env
,
3646 struct bpf_verifier_state
*old
,
3647 struct bpf_verifier_state
*cur
)
3649 struct idpair
*idmap
;
3653 idmap
= kcalloc(ID_MAP_SIZE
, sizeof(struct idpair
), GFP_KERNEL
);
3654 /* If we failed to allocate the idmap, just say it's not safe */
3658 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
3659 if (!regsafe(&old
->regs
[i
], &cur
->regs
[i
], idmap
))
3663 if (!stacksafe(old
, cur
, idmap
))
3671 /* A write screens off any subsequent reads; but write marks come from the
3672 * straight-line code between a state and its parent. When we arrive at a
3673 * jump target (in the first iteration of the propagate_liveness() loop),
3674 * we didn't arrive by the straight-line code, so read marks in state must
3675 * propagate to parent regardless of state's write marks.
3677 static bool do_propagate_liveness(const struct bpf_verifier_state
*state
,
3678 struct bpf_verifier_state
*parent
)
3680 bool writes
= parent
== state
->parent
; /* Observe write marks */
3681 bool touched
= false; /* any changes made? */
3686 /* Propagate read liveness of registers... */
3687 BUILD_BUG_ON(BPF_REG_FP
+ 1 != MAX_BPF_REG
);
3688 /* We don't need to worry about FP liveness because it's read-only */
3689 for (i
= 0; i
< BPF_REG_FP
; i
++) {
3690 if (parent
->regs
[i
].live
& REG_LIVE_READ
)
3692 if (writes
&& (state
->regs
[i
].live
& REG_LIVE_WRITTEN
))
3694 if (state
->regs
[i
].live
& REG_LIVE_READ
) {
3695 parent
->regs
[i
].live
|= REG_LIVE_READ
;
3699 /* ... and stack slots */
3700 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
&&
3701 i
< parent
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
3702 if (parent
->stack
[i
].slot_type
[0] != STACK_SPILL
)
3704 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
3706 if (parent
->stack
[i
].spilled_ptr
.live
& REG_LIVE_READ
)
3709 (state
->stack
[i
].spilled_ptr
.live
& REG_LIVE_WRITTEN
))
3711 if (state
->stack
[i
].spilled_ptr
.live
& REG_LIVE_READ
) {
3712 parent
->stack
[i
].spilled_ptr
.live
|= REG_LIVE_READ
;
3719 /* "parent" is "a state from which we reach the current state", but initially
3720 * it is not the state->parent (i.e. "the state whose straight-line code leads
3721 * to the current state"), instead it is the state that happened to arrive at
3722 * a (prunable) equivalent of the current state. See comment above
3723 * do_propagate_liveness() for consequences of this.
3724 * This function is just a more efficient way of calling mark_reg_read() or
3725 * mark_stack_slot_read() on each reg in "parent" that is read in "state",
3726 * though it requires that parent != state->parent in the call arguments.
3728 static void propagate_liveness(const struct bpf_verifier_state
*state
,
3729 struct bpf_verifier_state
*parent
)
3731 while (do_propagate_liveness(state
, parent
)) {
3732 /* Something changed, so we need to feed those changes onward */
3734 parent
= state
->parent
;
3738 static int is_state_visited(struct bpf_verifier_env
*env
, int insn_idx
)
3740 struct bpf_verifier_state_list
*new_sl
;
3741 struct bpf_verifier_state_list
*sl
;
3742 struct bpf_verifier_state
*cur
= env
->cur_state
;
3745 sl
= env
->explored_states
[insn_idx
];
3747 /* this 'insn_idx' instruction wasn't marked, so we will not
3748 * be doing state search here
3752 while (sl
!= STATE_LIST_MARK
) {
3753 if (states_equal(env
, &sl
->state
, cur
)) {
3754 /* reached equivalent register/stack state,
3756 * Registers read by the continuation are read by us.
3757 * If we have any write marks in env->cur_state, they
3758 * will prevent corresponding reads in the continuation
3759 * from reaching our parent (an explored_state). Our
3760 * own state will get the read marks recorded, but
3761 * they'll be immediately forgotten as we're pruning
3762 * this state and will pop a new one.
3764 propagate_liveness(&sl
->state
, cur
);
3770 /* there were no equivalent states, remember current one.
3771 * technically the current state is not proven to be safe yet,
3772 * but it will either reach bpf_exit (which means it's safe) or
3773 * it will be rejected. Since there are no loops, we won't be
3774 * seeing this 'insn_idx' instruction again on the way to bpf_exit
3776 new_sl
= kzalloc(sizeof(struct bpf_verifier_state_list
), GFP_KERNEL
);
3780 /* add new state to the head of linked list */
3781 err
= copy_verifier_state(&new_sl
->state
, cur
);
3783 free_verifier_state(&new_sl
->state
, false);
3787 new_sl
->next
= env
->explored_states
[insn_idx
];
3788 env
->explored_states
[insn_idx
] = new_sl
;
3789 /* connect new state to parentage chain */
3790 cur
->parent
= &new_sl
->state
;
3791 /* clear write marks in current state: the writes we did are not writes
3792 * our child did, so they don't screen off its reads from us.
3793 * (There are no read marks in current state, because reads always mark
3794 * their parent and current state never has children yet. Only
3795 * explored_states can get read marks.)
3797 for (i
= 0; i
< BPF_REG_FP
; i
++)
3798 cur
->regs
[i
].live
= REG_LIVE_NONE
;
3799 for (i
= 0; i
< cur
->allocated_stack
/ BPF_REG_SIZE
; i
++)
3800 if (cur
->stack
[i
].slot_type
[0] == STACK_SPILL
)
3801 cur
->stack
[i
].spilled_ptr
.live
= REG_LIVE_NONE
;
3805 static int ext_analyzer_insn_hook(struct bpf_verifier_env
*env
,
3806 int insn_idx
, int prev_insn_idx
)
3808 if (env
->dev_ops
&& env
->dev_ops
->insn_hook
)
3809 return env
->dev_ops
->insn_hook(env
, insn_idx
, prev_insn_idx
);
3814 static int do_check(struct bpf_verifier_env
*env
)
3816 struct bpf_verifier_state
*state
;
3817 struct bpf_insn
*insns
= env
->prog
->insnsi
;
3818 struct bpf_reg_state
*regs
;
3819 int insn_cnt
= env
->prog
->len
;
3820 int insn_idx
, prev_insn_idx
= 0;
3821 int insn_processed
= 0;
3822 bool do_print_state
= false;
3824 state
= kzalloc(sizeof(struct bpf_verifier_state
), GFP_KERNEL
);
3827 env
->cur_state
= state
;
3828 init_reg_state(env
, state
->regs
);
3829 state
->parent
= NULL
;
3832 struct bpf_insn
*insn
;
3836 if (insn_idx
>= insn_cnt
) {
3837 verbose(env
, "invalid insn idx %d insn_cnt %d\n",
3838 insn_idx
, insn_cnt
);
3842 insn
= &insns
[insn_idx
];
3843 class = BPF_CLASS(insn
->code
);
3845 if (++insn_processed
> BPF_COMPLEXITY_LIMIT_INSNS
) {
3847 "BPF program is too large. Processed %d insn\n",
3852 err
= is_state_visited(env
, insn_idx
);
3856 /* found equivalent state, can prune the search */
3857 if (env
->log
.level
) {
3859 verbose(env
, "\nfrom %d to %d: safe\n",
3860 prev_insn_idx
, insn_idx
);
3862 verbose(env
, "%d: safe\n", insn_idx
);
3864 goto process_bpf_exit
;
3870 if (env
->log
.level
> 1 || (env
->log
.level
&& do_print_state
)) {
3871 if (env
->log
.level
> 1)
3872 verbose(env
, "%d:", insn_idx
);
3874 verbose(env
, "\nfrom %d to %d:",
3875 prev_insn_idx
, insn_idx
);
3876 print_verifier_state(env
, state
);
3877 do_print_state
= false;
3880 if (env
->log
.level
) {
3881 verbose(env
, "%d: ", insn_idx
);
3882 print_bpf_insn(verbose
, env
, insn
,
3883 env
->allow_ptr_leaks
);
3886 err
= ext_analyzer_insn_hook(env
, insn_idx
, prev_insn_idx
);
3890 regs
= cur_regs(env
);
3891 env
->insn_aux_data
[insn_idx
].seen
= true;
3892 if (class == BPF_ALU
|| class == BPF_ALU64
) {
3893 err
= check_alu_op(env
, insn
);
3897 } else if (class == BPF_LDX
) {
3898 enum bpf_reg_type
*prev_src_type
, src_reg_type
;
3900 /* check for reserved fields is already done */
3902 /* check src operand */
3903 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3907 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP_NO_MARK
);
3911 src_reg_type
= regs
[insn
->src_reg
].type
;
3913 /* check that memory (src_reg + off) is readable,
3914 * the state of dst_reg will be updated by this func
3916 err
= check_mem_access(env
, insn_idx
, insn
->src_reg
, insn
->off
,
3917 BPF_SIZE(insn
->code
), BPF_READ
,
3922 prev_src_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
3924 if (*prev_src_type
== NOT_INIT
) {
3926 * dst_reg = *(u32 *)(src_reg + off)
3927 * save type to validate intersecting paths
3929 *prev_src_type
= src_reg_type
;
3931 } else if (src_reg_type
!= *prev_src_type
&&
3932 (src_reg_type
== PTR_TO_CTX
||
3933 *prev_src_type
== PTR_TO_CTX
)) {
3934 /* ABuser program is trying to use the same insn
3935 * dst_reg = *(u32*) (src_reg + off)
3936 * with different pointer types:
3937 * src_reg == ctx in one branch and
3938 * src_reg == stack|map in some other branch.
3941 verbose(env
, "same insn cannot be used with different pointers\n");
3945 } else if (class == BPF_STX
) {
3946 enum bpf_reg_type
*prev_dst_type
, dst_reg_type
;
3948 if (BPF_MODE(insn
->code
) == BPF_XADD
) {
3949 err
= check_xadd(env
, insn_idx
, insn
);
3956 /* check src1 operand */
3957 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3960 /* check src2 operand */
3961 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
3965 dst_reg_type
= regs
[insn
->dst_reg
].type
;
3967 /* check that memory (dst_reg + off) is writeable */
3968 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
3969 BPF_SIZE(insn
->code
), BPF_WRITE
,
3974 prev_dst_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
3976 if (*prev_dst_type
== NOT_INIT
) {
3977 *prev_dst_type
= dst_reg_type
;
3978 } else if (dst_reg_type
!= *prev_dst_type
&&
3979 (dst_reg_type
== PTR_TO_CTX
||
3980 *prev_dst_type
== PTR_TO_CTX
)) {
3981 verbose(env
, "same insn cannot be used with different pointers\n");
3985 } else if (class == BPF_ST
) {
3986 if (BPF_MODE(insn
->code
) != BPF_MEM
||
3987 insn
->src_reg
!= BPF_REG_0
) {
3988 verbose(env
, "BPF_ST uses reserved fields\n");
3991 /* check src operand */
3992 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
3996 /* check that memory (dst_reg + off) is writeable */
3997 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
3998 BPF_SIZE(insn
->code
), BPF_WRITE
,
4003 } else if (class == BPF_JMP
) {
4004 u8 opcode
= BPF_OP(insn
->code
);
4006 if (opcode
== BPF_CALL
) {
4007 if (BPF_SRC(insn
->code
) != BPF_K
||
4009 insn
->src_reg
!= BPF_REG_0
||
4010 insn
->dst_reg
!= BPF_REG_0
) {
4011 verbose(env
, "BPF_CALL uses reserved fields\n");
4015 err
= check_call(env
, insn
->imm
, insn_idx
);
4019 } else if (opcode
== BPF_JA
) {
4020 if (BPF_SRC(insn
->code
) != BPF_K
||
4022 insn
->src_reg
!= BPF_REG_0
||
4023 insn
->dst_reg
!= BPF_REG_0
) {
4024 verbose(env
, "BPF_JA uses reserved fields\n");
4028 insn_idx
+= insn
->off
+ 1;
4031 } else if (opcode
== BPF_EXIT
) {
4032 if (BPF_SRC(insn
->code
) != BPF_K
||
4034 insn
->src_reg
!= BPF_REG_0
||
4035 insn
->dst_reg
!= BPF_REG_0
) {
4036 verbose(env
, "BPF_EXIT uses reserved fields\n");
4040 /* eBPF calling convetion is such that R0 is used
4041 * to return the value from eBPF program.
4042 * Make sure that it's readable at this time
4043 * of bpf_exit, which means that program wrote
4044 * something into it earlier
4046 err
= check_reg_arg(env
, BPF_REG_0
, SRC_OP
);
4050 if (is_pointer_value(env
, BPF_REG_0
)) {
4051 verbose(env
, "R0 leaks addr as return value\n");
4055 err
= check_return_code(env
);
4059 err
= pop_stack(env
, &prev_insn_idx
, &insn_idx
);
4065 do_print_state
= true;
4069 err
= check_cond_jmp_op(env
, insn
, &insn_idx
);
4073 } else if (class == BPF_LD
) {
4074 u8 mode
= BPF_MODE(insn
->code
);
4076 if (mode
== BPF_ABS
|| mode
== BPF_IND
) {
4077 err
= check_ld_abs(env
, insn
);
4081 } else if (mode
== BPF_IMM
) {
4082 err
= check_ld_imm(env
, insn
);
4087 env
->insn_aux_data
[insn_idx
].seen
= true;
4089 verbose(env
, "invalid BPF_LD mode\n");
4093 verbose(env
, "unknown insn class %d\n", class);
4100 verbose(env
, "processed %d insns, stack depth %d\n", insn_processed
,
4101 env
->prog
->aux
->stack_depth
);
4105 static int check_map_prealloc(struct bpf_map
*map
)
4107 return (map
->map_type
!= BPF_MAP_TYPE_HASH
&&
4108 map
->map_type
!= BPF_MAP_TYPE_PERCPU_HASH
&&
4109 map
->map_type
!= BPF_MAP_TYPE_HASH_OF_MAPS
) ||
4110 !(map
->map_flags
& BPF_F_NO_PREALLOC
);
4113 static int check_map_prog_compatibility(struct bpf_verifier_env
*env
,
4114 struct bpf_map
*map
,
4115 struct bpf_prog
*prog
)
4118 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
4119 * preallocated hash maps, since doing memory allocation
4120 * in overflow_handler can crash depending on where nmi got
4123 if (prog
->type
== BPF_PROG_TYPE_PERF_EVENT
) {
4124 if (!check_map_prealloc(map
)) {
4125 verbose(env
, "perf_event programs can only use preallocated hash map\n");
4128 if (map
->inner_map_meta
&&
4129 !check_map_prealloc(map
->inner_map_meta
)) {
4130 verbose(env
, "perf_event programs can only use preallocated inner hash map\n");
4137 /* look for pseudo eBPF instructions that access map FDs and
4138 * replace them with actual map pointers
4140 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env
*env
)
4142 struct bpf_insn
*insn
= env
->prog
->insnsi
;
4143 int insn_cnt
= env
->prog
->len
;
4146 err
= bpf_prog_calc_tag(env
->prog
);
4150 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
4151 if (BPF_CLASS(insn
->code
) == BPF_LDX
&&
4152 (BPF_MODE(insn
->code
) != BPF_MEM
|| insn
->imm
!= 0)) {
4153 verbose(env
, "BPF_LDX uses reserved fields\n");
4157 if (BPF_CLASS(insn
->code
) == BPF_STX
&&
4158 ((BPF_MODE(insn
->code
) != BPF_MEM
&&
4159 BPF_MODE(insn
->code
) != BPF_XADD
) || insn
->imm
!= 0)) {
4160 verbose(env
, "BPF_STX uses reserved fields\n");
4164 if (insn
[0].code
== (BPF_LD
| BPF_IMM
| BPF_DW
)) {
4165 struct bpf_map
*map
;
4168 if (i
== insn_cnt
- 1 || insn
[1].code
!= 0 ||
4169 insn
[1].dst_reg
!= 0 || insn
[1].src_reg
!= 0 ||
4171 verbose(env
, "invalid bpf_ld_imm64 insn\n");
4175 if (insn
->src_reg
== 0)
4176 /* valid generic load 64-bit imm */
4179 if (insn
->src_reg
!= BPF_PSEUDO_MAP_FD
) {
4181 "unrecognized bpf_ld_imm64 insn\n");
4185 f
= fdget(insn
->imm
);
4186 map
= __bpf_map_get(f
);
4188 verbose(env
, "fd %d is not pointing to valid bpf_map\n",
4190 return PTR_ERR(map
);
4193 err
= check_map_prog_compatibility(env
, map
, env
->prog
);
4199 /* store map pointer inside BPF_LD_IMM64 instruction */
4200 insn
[0].imm
= (u32
) (unsigned long) map
;
4201 insn
[1].imm
= ((u64
) (unsigned long) map
) >> 32;
4203 /* check whether we recorded this map already */
4204 for (j
= 0; j
< env
->used_map_cnt
; j
++)
4205 if (env
->used_maps
[j
] == map
) {
4210 if (env
->used_map_cnt
>= MAX_USED_MAPS
) {
4215 /* hold the map. If the program is rejected by verifier,
4216 * the map will be released by release_maps() or it
4217 * will be used by the valid program until it's unloaded
4218 * and all maps are released in free_bpf_prog_info()
4220 map
= bpf_map_inc(map
, false);
4223 return PTR_ERR(map
);
4225 env
->used_maps
[env
->used_map_cnt
++] = map
;
4234 /* now all pseudo BPF_LD_IMM64 instructions load valid
4235 * 'struct bpf_map *' into a register instead of user map_fd.
4236 * These pointers will be used later by verifier to validate map access.
4241 /* drop refcnt of maps used by the rejected program */
4242 static void release_maps(struct bpf_verifier_env
*env
)
4246 for (i
= 0; i
< env
->used_map_cnt
; i
++)
4247 bpf_map_put(env
->used_maps
[i
]);
4250 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
4251 static void convert_pseudo_ld_imm64(struct bpf_verifier_env
*env
)
4253 struct bpf_insn
*insn
= env
->prog
->insnsi
;
4254 int insn_cnt
= env
->prog
->len
;
4257 for (i
= 0; i
< insn_cnt
; i
++, insn
++)
4258 if (insn
->code
== (BPF_LD
| BPF_IMM
| BPF_DW
))
4262 /* single env->prog->insni[off] instruction was replaced with the range
4263 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
4264 * [0, off) and [off, end) to new locations, so the patched range stays zero
4266 static int adjust_insn_aux_data(struct bpf_verifier_env
*env
, u32 prog_len
,
4269 struct bpf_insn_aux_data
*new_data
, *old_data
= env
->insn_aux_data
;
4274 new_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) * prog_len
);
4277 memcpy(new_data
, old_data
, sizeof(struct bpf_insn_aux_data
) * off
);
4278 memcpy(new_data
+ off
+ cnt
- 1, old_data
+ off
,
4279 sizeof(struct bpf_insn_aux_data
) * (prog_len
- off
- cnt
+ 1));
4280 for (i
= off
; i
< off
+ cnt
- 1; i
++)
4281 new_data
[i
].seen
= true;
4282 env
->insn_aux_data
= new_data
;
4287 static struct bpf_prog
*bpf_patch_insn_data(struct bpf_verifier_env
*env
, u32 off
,
4288 const struct bpf_insn
*patch
, u32 len
)
4290 struct bpf_prog
*new_prog
;
4292 new_prog
= bpf_patch_insn_single(env
->prog
, off
, patch
, len
);
4295 if (adjust_insn_aux_data(env
, new_prog
->len
, off
, len
))
4300 /* The verifier does more data flow analysis than llvm and will not explore
4301 * branches that are dead at run time. Malicious programs can have dead code
4302 * too. Therefore replace all dead at-run-time code with nops.
4304 static void sanitize_dead_code(struct bpf_verifier_env
*env
)
4306 struct bpf_insn_aux_data
*aux_data
= env
->insn_aux_data
;
4307 struct bpf_insn nop
= BPF_MOV64_REG(BPF_REG_0
, BPF_REG_0
);
4308 struct bpf_insn
*insn
= env
->prog
->insnsi
;
4309 const int insn_cnt
= env
->prog
->len
;
4312 for (i
= 0; i
< insn_cnt
; i
++) {
4313 if (aux_data
[i
].seen
)
4315 memcpy(insn
+ i
, &nop
, sizeof(nop
));
4319 /* convert load instructions that access fields of 'struct __sk_buff'
4320 * into sequence of instructions that access fields of 'struct sk_buff'
4322 static int convert_ctx_accesses(struct bpf_verifier_env
*env
)
4324 const struct bpf_verifier_ops
*ops
= env
->ops
;
4325 int i
, cnt
, size
, ctx_field_size
, delta
= 0;
4326 const int insn_cnt
= env
->prog
->len
;
4327 struct bpf_insn insn_buf
[16], *insn
;
4328 struct bpf_prog
*new_prog
;
4329 enum bpf_access_type type
;
4330 bool is_narrower_load
;
4333 if (ops
->gen_prologue
) {
4334 cnt
= ops
->gen_prologue(insn_buf
, env
->seen_direct_write
,
4336 if (cnt
>= ARRAY_SIZE(insn_buf
)) {
4337 verbose(env
, "bpf verifier is misconfigured\n");
4340 new_prog
= bpf_patch_insn_data(env
, 0, insn_buf
, cnt
);
4344 env
->prog
= new_prog
;
4349 if (!ops
->convert_ctx_access
)
4352 insn
= env
->prog
->insnsi
+ delta
;
4354 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
4355 if (insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_B
) ||
4356 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_H
) ||
4357 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_W
) ||
4358 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_DW
))
4360 else if (insn
->code
== (BPF_STX
| BPF_MEM
| BPF_B
) ||
4361 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_H
) ||
4362 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_W
) ||
4363 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_DW
))
4368 if (env
->insn_aux_data
[i
+ delta
].ptr_type
!= PTR_TO_CTX
)
4371 ctx_field_size
= env
->insn_aux_data
[i
+ delta
].ctx_field_size
;
4372 size
= BPF_LDST_BYTES(insn
);
4374 /* If the read access is a narrower load of the field,
4375 * convert to a 4/8-byte load, to minimum program type specific
4376 * convert_ctx_access changes. If conversion is successful,
4377 * we will apply proper mask to the result.
4379 is_narrower_load
= size
< ctx_field_size
;
4380 if (is_narrower_load
) {
4381 u32 off
= insn
->off
;
4384 if (type
== BPF_WRITE
) {
4385 verbose(env
, "bpf verifier narrow ctx access misconfigured\n");
4390 if (ctx_field_size
== 4)
4392 else if (ctx_field_size
== 8)
4395 insn
->off
= off
& ~(ctx_field_size
- 1);
4396 insn
->code
= BPF_LDX
| BPF_MEM
| size_code
;
4400 cnt
= ops
->convert_ctx_access(type
, insn
, insn_buf
, env
->prog
,
4402 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
) ||
4403 (ctx_field_size
&& !target_size
)) {
4404 verbose(env
, "bpf verifier is misconfigured\n");
4408 if (is_narrower_load
&& size
< target_size
) {
4409 if (ctx_field_size
<= 4)
4410 insn_buf
[cnt
++] = BPF_ALU32_IMM(BPF_AND
, insn
->dst_reg
,
4411 (1 << size
* 8) - 1);
4413 insn_buf
[cnt
++] = BPF_ALU64_IMM(BPF_AND
, insn
->dst_reg
,
4414 (1 << size
* 8) - 1);
4417 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
, cnt
);
4423 /* keep walking new program and skip insns we just inserted */
4424 env
->prog
= new_prog
;
4425 insn
= new_prog
->insnsi
+ i
+ delta
;
4431 /* fixup insn->imm field of bpf_call instructions
4432 * and inline eligible helpers as explicit sequence of BPF instructions
4434 * this function is called after eBPF program passed verification
4436 static int fixup_bpf_calls(struct bpf_verifier_env
*env
)
4438 struct bpf_prog
*prog
= env
->prog
;
4439 struct bpf_insn
*insn
= prog
->insnsi
;
4440 const struct bpf_func_proto
*fn
;
4441 const int insn_cnt
= prog
->len
;
4442 struct bpf_insn insn_buf
[16];
4443 struct bpf_prog
*new_prog
;
4444 struct bpf_map
*map_ptr
;
4445 int i
, cnt
, delta
= 0;
4447 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
4448 if (insn
->code
!= (BPF_JMP
| BPF_CALL
))
4451 if (insn
->imm
== BPF_FUNC_get_route_realm
)
4452 prog
->dst_needed
= 1;
4453 if (insn
->imm
== BPF_FUNC_get_prandom_u32
)
4454 bpf_user_rnd_init_once();
4455 if (insn
->imm
== BPF_FUNC_tail_call
) {
4456 /* If we tail call into other programs, we
4457 * cannot make any assumptions since they can
4458 * be replaced dynamically during runtime in
4459 * the program array.
4461 prog
->cb_access
= 1;
4462 env
->prog
->aux
->stack_depth
= MAX_BPF_STACK
;
4464 /* mark bpf_tail_call as different opcode to avoid
4465 * conditional branch in the interpeter for every normal
4466 * call and to prevent accidental JITing by JIT compiler
4467 * that doesn't support bpf_tail_call yet
4470 insn
->code
= BPF_JMP
| BPF_TAIL_CALL
;
4472 /* instead of changing every JIT dealing with tail_call
4473 * emit two extra insns:
4474 * if (index >= max_entries) goto out;
4475 * index &= array->index_mask;
4476 * to avoid out-of-bounds cpu speculation
4478 map_ptr
= env
->insn_aux_data
[i
+ delta
].map_ptr
;
4479 if (map_ptr
== BPF_MAP_PTR_POISON
) {
4480 verbose(env
, "tail_call abusing map_ptr\n");
4483 if (!map_ptr
->unpriv_array
)
4485 insn_buf
[0] = BPF_JMP_IMM(BPF_JGE
, BPF_REG_3
,
4486 map_ptr
->max_entries
, 2);
4487 insn_buf
[1] = BPF_ALU32_IMM(BPF_AND
, BPF_REG_3
,
4488 container_of(map_ptr
,
4491 insn_buf
[2] = *insn
;
4493 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
, cnt
);
4498 env
->prog
= prog
= new_prog
;
4499 insn
= new_prog
->insnsi
+ i
+ delta
;
4503 /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
4504 * handlers are currently limited to 64 bit only.
4506 if (ebpf_jit_enabled() && BITS_PER_LONG
== 64 &&
4507 insn
->imm
== BPF_FUNC_map_lookup_elem
) {
4508 map_ptr
= env
->insn_aux_data
[i
+ delta
].map_ptr
;
4509 if (map_ptr
== BPF_MAP_PTR_POISON
||
4510 !map_ptr
->ops
->map_gen_lookup
)
4511 goto patch_call_imm
;
4513 cnt
= map_ptr
->ops
->map_gen_lookup(map_ptr
, insn_buf
);
4514 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
)) {
4515 verbose(env
, "bpf verifier is misconfigured\n");
4519 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
,
4526 /* keep walking new program and skip insns we just inserted */
4527 env
->prog
= prog
= new_prog
;
4528 insn
= new_prog
->insnsi
+ i
+ delta
;
4532 if (insn
->imm
== BPF_FUNC_redirect_map
) {
4533 /* Note, we cannot use prog directly as imm as subsequent
4534 * rewrites would still change the prog pointer. The only
4535 * stable address we can use is aux, which also works with
4536 * prog clones during blinding.
4538 u64 addr
= (unsigned long)prog
->aux
;
4539 struct bpf_insn r4_ld
[] = {
4540 BPF_LD_IMM64(BPF_REG_4
, addr
),
4543 cnt
= ARRAY_SIZE(r4_ld
);
4545 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, r4_ld
, cnt
);
4550 env
->prog
= prog
= new_prog
;
4551 insn
= new_prog
->insnsi
+ i
+ delta
;
4554 fn
= env
->ops
->get_func_proto(insn
->imm
);
4555 /* all functions that have prototype and verifier allowed
4556 * programs to call them, must be real in-kernel functions
4560 "kernel subsystem misconfigured func %s#%d\n",
4561 func_id_name(insn
->imm
), insn
->imm
);
4564 insn
->imm
= fn
->func
- __bpf_call_base
;
4570 static void free_states(struct bpf_verifier_env
*env
)
4572 struct bpf_verifier_state_list
*sl
, *sln
;
4575 if (!env
->explored_states
)
4578 for (i
= 0; i
< env
->prog
->len
; i
++) {
4579 sl
= env
->explored_states
[i
];
4582 while (sl
!= STATE_LIST_MARK
) {
4584 free_verifier_state(&sl
->state
, false);
4590 kfree(env
->explored_states
);
4593 int bpf_check(struct bpf_prog
**prog
, union bpf_attr
*attr
)
4595 struct bpf_verifier_env
*env
;
4596 struct bpf_verifer_log
*log
;
4599 /* no program is valid */
4600 if (ARRAY_SIZE(bpf_verifier_ops
) == 0)
4603 /* 'struct bpf_verifier_env' can be global, but since it's not small,
4604 * allocate/free it every time bpf_check() is called
4606 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
4611 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
4614 if (!env
->insn_aux_data
)
4617 env
->ops
= bpf_verifier_ops
[env
->prog
->type
];
4619 /* grab the mutex to protect few globals used by verifier */
4620 mutex_lock(&bpf_verifier_lock
);
4622 if (attr
->log_level
|| attr
->log_buf
|| attr
->log_size
) {
4623 /* user requested verbose verifier output
4624 * and supplied buffer to store the verification trace
4626 log
->level
= attr
->log_level
;
4627 log
->ubuf
= (char __user
*) (unsigned long) attr
->log_buf
;
4628 log
->len_total
= attr
->log_size
;
4631 /* log attributes have to be sane */
4632 if (log
->len_total
< 128 || log
->len_total
> UINT_MAX
>> 8 ||
4633 !log
->level
|| !log
->ubuf
)
4637 env
->strict_alignment
= !!(attr
->prog_flags
& BPF_F_STRICT_ALIGNMENT
);
4638 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
))
4639 env
->strict_alignment
= true;
4641 if (env
->prog
->aux
->offload
) {
4642 ret
= bpf_prog_offload_verifier_prep(env
);
4647 ret
= replace_map_fd_with_map_ptr(env
);
4649 goto skip_full_check
;
4651 env
->explored_states
= kcalloc(env
->prog
->len
,
4652 sizeof(struct bpf_verifier_state_list
*),
4655 if (!env
->explored_states
)
4656 goto skip_full_check
;
4658 ret
= check_cfg(env
);
4660 goto skip_full_check
;
4662 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
4664 ret
= do_check(env
);
4665 if (env
->cur_state
) {
4666 free_verifier_state(env
->cur_state
, true);
4667 env
->cur_state
= NULL
;
4671 while (!pop_stack(env
, NULL
, NULL
));
4675 sanitize_dead_code(env
);
4678 /* program is valid, convert *(u32*)(ctx + off) accesses */
4679 ret
= convert_ctx_accesses(env
);
4682 ret
= fixup_bpf_calls(env
);
4684 if (log
->level
&& bpf_verifier_log_full(log
))
4686 if (log
->level
&& !log
->ubuf
) {
4688 goto err_release_maps
;
4691 if (ret
== 0 && env
->used_map_cnt
) {
4692 /* if program passed verifier, update used_maps in bpf_prog_info */
4693 env
->prog
->aux
->used_maps
= kmalloc_array(env
->used_map_cnt
,
4694 sizeof(env
->used_maps
[0]),
4697 if (!env
->prog
->aux
->used_maps
) {
4699 goto err_release_maps
;
4702 memcpy(env
->prog
->aux
->used_maps
, env
->used_maps
,
4703 sizeof(env
->used_maps
[0]) * env
->used_map_cnt
);
4704 env
->prog
->aux
->used_map_cnt
= env
->used_map_cnt
;
4706 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
4707 * bpf_ld_imm64 instructions
4709 convert_pseudo_ld_imm64(env
);
4713 if (!env
->prog
->aux
->used_maps
)
4714 /* if we didn't copy map pointers into bpf_prog_info, release
4715 * them now. Otherwise free_bpf_prog_info() will release them.
4720 mutex_unlock(&bpf_verifier_lock
);
4721 vfree(env
->insn_aux_data
);