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>
23 #include <linux/bsearch.h>
24 #include <linux/sort.h>
28 static const struct bpf_verifier_ops
* const bpf_verifier_ops
[] = {
29 #define BPF_PROG_TYPE(_id, _name) \
30 [_id] = & _name ## _verifier_ops,
31 #define BPF_MAP_TYPE(_id, _ops)
32 #include <linux/bpf_types.h>
37 /* bpf_check() is a static code analyzer that walks eBPF program
38 * instruction by instruction and updates register/stack state.
39 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
41 * The first pass is depth-first-search to check that the program is a DAG.
42 * It rejects the following programs:
43 * - larger than BPF_MAXINSNS insns
44 * - if loop is present (detected via back-edge)
45 * - unreachable insns exist (shouldn't be a forest. program = one function)
46 * - out of bounds or malformed jumps
47 * The second pass is all possible path descent from the 1st insn.
48 * Since it's analyzing all pathes through the program, the length of the
49 * analysis is limited to 64k insn, which may be hit even if total number of
50 * insn is less then 4K, but there are too many branches that change stack/regs.
51 * Number of 'branches to be analyzed' is limited to 1k
53 * On entry to each instruction, each register has a type, and the instruction
54 * changes the types of the registers depending on instruction semantics.
55 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
58 * All registers are 64-bit.
59 * R0 - return register
60 * R1-R5 argument passing registers
61 * R6-R9 callee saved registers
62 * R10 - frame pointer read-only
64 * At the start of BPF program the register R1 contains a pointer to bpf_context
65 * and has type PTR_TO_CTX.
67 * Verifier tracks arithmetic operations on pointers in case:
68 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
69 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
70 * 1st insn copies R10 (which has FRAME_PTR) type into R1
71 * and 2nd arithmetic instruction is pattern matched to recognize
72 * that it wants to construct a pointer to some element within stack.
73 * So after 2nd insn, the register R1 has type PTR_TO_STACK
74 * (and -20 constant is saved for further stack bounds checking).
75 * Meaning that this reg is a pointer to stack plus known immediate constant.
77 * Most of the time the registers have SCALAR_VALUE type, which
78 * means the register has some value, but it's not a valid pointer.
79 * (like pointer plus pointer becomes SCALAR_VALUE type)
81 * When verifier sees load or store instructions the type of base register
82 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer
83 * types recognized by check_mem_access() function.
85 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
86 * and the range of [ptr, ptr + map's value_size) is accessible.
88 * registers used to pass values to function calls are checked against
89 * function argument constraints.
91 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
92 * It means that the register type passed to this function must be
93 * PTR_TO_STACK and it will be used inside the function as
94 * 'pointer to map element key'
96 * For example the argument constraints for bpf_map_lookup_elem():
97 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
98 * .arg1_type = ARG_CONST_MAP_PTR,
99 * .arg2_type = ARG_PTR_TO_MAP_KEY,
101 * ret_type says that this function returns 'pointer to map elem value or null'
102 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
103 * 2nd argument should be a pointer to stack, which will be used inside
104 * the helper function as a pointer to map element key.
106 * On the kernel side the helper function looks like:
107 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
109 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
110 * void *key = (void *) (unsigned long) r2;
113 * here kernel can access 'key' and 'map' pointers safely, knowing that
114 * [key, key + map->key_size) bytes are valid and were initialized on
115 * the stack of eBPF program.
118 * Corresponding eBPF program may look like:
119 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
120 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
121 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
122 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
123 * here verifier looks at prototype of map_lookup_elem() and sees:
124 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
125 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
127 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
128 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
129 * and were initialized prior to this call.
130 * If it's ok, then verifier allows this BPF_CALL insn and looks at
131 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
132 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
133 * returns ether pointer to map value or NULL.
135 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
136 * insn, the register holding that pointer in the true branch changes state to
137 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
138 * branch. See check_cond_jmp_op().
140 * After the call R0 is set to return type of the function and registers R1-R5
141 * are set to NOT_INIT to indicate that they are no longer readable.
144 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
145 struct bpf_verifier_stack_elem
{
146 /* verifer state is 'st'
147 * before processing instruction 'insn_idx'
148 * and after processing instruction 'prev_insn_idx'
150 struct bpf_verifier_state st
;
153 struct bpf_verifier_stack_elem
*next
;
156 #define BPF_COMPLEXITY_LIMIT_INSNS 131072
157 #define BPF_COMPLEXITY_LIMIT_STACK 1024
159 #define BPF_MAP_PTR_UNPRIV 1UL
160 #define BPF_MAP_PTR_POISON ((void *)((0xeB9FUL << 1) + \
161 POISON_POINTER_DELTA))
162 #define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
164 static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data
*aux
)
166 return BPF_MAP_PTR(aux
->map_state
) == BPF_MAP_PTR_POISON
;
169 static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data
*aux
)
171 return aux
->map_state
& BPF_MAP_PTR_UNPRIV
;
174 static void bpf_map_ptr_store(struct bpf_insn_aux_data
*aux
,
175 const struct bpf_map
*map
, bool unpriv
)
177 BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON
& BPF_MAP_PTR_UNPRIV
);
178 unpriv
|= bpf_map_ptr_unpriv(aux
);
179 aux
->map_state
= (unsigned long)map
|
180 (unpriv
? BPF_MAP_PTR_UNPRIV
: 0UL);
183 struct bpf_call_arg_meta
{
184 struct bpf_map
*map_ptr
;
191 static DEFINE_MUTEX(bpf_verifier_lock
);
193 void bpf_verifier_vlog(struct bpf_verifier_log
*log
, const char *fmt
,
198 n
= vscnprintf(log
->kbuf
, BPF_VERIFIER_TMP_LOG_SIZE
, fmt
, args
);
200 WARN_ONCE(n
>= BPF_VERIFIER_TMP_LOG_SIZE
- 1,
201 "verifier log line truncated - local buffer too short\n");
203 n
= min(log
->len_total
- log
->len_used
- 1, n
);
206 if (!copy_to_user(log
->ubuf
+ log
->len_used
, log
->kbuf
, n
+ 1))
212 /* log_level controls verbosity level of eBPF verifier.
213 * bpf_verifier_log_write() is used to dump the verification trace to the log,
214 * so the user can figure out what's wrong with the program
216 __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env
*env
,
217 const char *fmt
, ...)
221 if (!bpf_verifier_log_needed(&env
->log
))
225 bpf_verifier_vlog(&env
->log
, fmt
, args
);
228 EXPORT_SYMBOL_GPL(bpf_verifier_log_write
);
230 __printf(2, 3) static void verbose(void *private_data
, const char *fmt
, ...)
232 struct bpf_verifier_env
*env
= private_data
;
235 if (!bpf_verifier_log_needed(&env
->log
))
239 bpf_verifier_vlog(&env
->log
, fmt
, args
);
243 static bool type_is_pkt_pointer(enum bpf_reg_type type
)
245 return type
== PTR_TO_PACKET
||
246 type
== PTR_TO_PACKET_META
;
249 /* string representation of 'enum bpf_reg_type' */
250 static const char * const reg_type_str
[] = {
252 [SCALAR_VALUE
] = "inv",
253 [PTR_TO_CTX
] = "ctx",
254 [CONST_PTR_TO_MAP
] = "map_ptr",
255 [PTR_TO_MAP_VALUE
] = "map_value",
256 [PTR_TO_MAP_VALUE_OR_NULL
] = "map_value_or_null",
257 [PTR_TO_STACK
] = "fp",
258 [PTR_TO_PACKET
] = "pkt",
259 [PTR_TO_PACKET_META
] = "pkt_meta",
260 [PTR_TO_PACKET_END
] = "pkt_end",
263 static void print_liveness(struct bpf_verifier_env
*env
,
264 enum bpf_reg_liveness live
)
266 if (live
& (REG_LIVE_READ
| REG_LIVE_WRITTEN
))
268 if (live
& REG_LIVE_READ
)
270 if (live
& REG_LIVE_WRITTEN
)
274 static struct bpf_func_state
*func(struct bpf_verifier_env
*env
,
275 const struct bpf_reg_state
*reg
)
277 struct bpf_verifier_state
*cur
= env
->cur_state
;
279 return cur
->frame
[reg
->frameno
];
282 static void print_verifier_state(struct bpf_verifier_env
*env
,
283 const struct bpf_func_state
*state
)
285 const struct bpf_reg_state
*reg
;
290 verbose(env
, " frame%d:", state
->frameno
);
291 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
292 reg
= &state
->regs
[i
];
296 verbose(env
, " R%d", i
);
297 print_liveness(env
, reg
->live
);
298 verbose(env
, "=%s", reg_type_str
[t
]);
299 if ((t
== SCALAR_VALUE
|| t
== PTR_TO_STACK
) &&
300 tnum_is_const(reg
->var_off
)) {
301 /* reg->off should be 0 for SCALAR_VALUE */
302 verbose(env
, "%lld", reg
->var_off
.value
+ reg
->off
);
303 if (t
== PTR_TO_STACK
)
304 verbose(env
, ",call_%d", func(env
, reg
)->callsite
);
306 verbose(env
, "(id=%d", reg
->id
);
307 if (t
!= SCALAR_VALUE
)
308 verbose(env
, ",off=%d", reg
->off
);
309 if (type_is_pkt_pointer(t
))
310 verbose(env
, ",r=%d", reg
->range
);
311 else if (t
== CONST_PTR_TO_MAP
||
312 t
== PTR_TO_MAP_VALUE
||
313 t
== PTR_TO_MAP_VALUE_OR_NULL
)
314 verbose(env
, ",ks=%d,vs=%d",
315 reg
->map_ptr
->key_size
,
316 reg
->map_ptr
->value_size
);
317 if (tnum_is_const(reg
->var_off
)) {
318 /* Typically an immediate SCALAR_VALUE, but
319 * could be a pointer whose offset is too big
322 verbose(env
, ",imm=%llx", reg
->var_off
.value
);
324 if (reg
->smin_value
!= reg
->umin_value
&&
325 reg
->smin_value
!= S64_MIN
)
326 verbose(env
, ",smin_value=%lld",
327 (long long)reg
->smin_value
);
328 if (reg
->smax_value
!= reg
->umax_value
&&
329 reg
->smax_value
!= S64_MAX
)
330 verbose(env
, ",smax_value=%lld",
331 (long long)reg
->smax_value
);
332 if (reg
->umin_value
!= 0)
333 verbose(env
, ",umin_value=%llu",
334 (unsigned long long)reg
->umin_value
);
335 if (reg
->umax_value
!= U64_MAX
)
336 verbose(env
, ",umax_value=%llu",
337 (unsigned long long)reg
->umax_value
);
338 if (!tnum_is_unknown(reg
->var_off
)) {
341 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
342 verbose(env
, ",var_off=%s", tn_buf
);
348 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
349 if (state
->stack
[i
].slot_type
[0] == STACK_SPILL
) {
350 verbose(env
, " fp%d",
351 (-i
- 1) * BPF_REG_SIZE
);
352 print_liveness(env
, state
->stack
[i
].spilled_ptr
.live
);
354 reg_type_str
[state
->stack
[i
].spilled_ptr
.type
]);
356 if (state
->stack
[i
].slot_type
[0] == STACK_ZERO
)
357 verbose(env
, " fp%d=0", (-i
- 1) * BPF_REG_SIZE
);
362 static int copy_stack_state(struct bpf_func_state
*dst
,
363 const struct bpf_func_state
*src
)
367 if (WARN_ON_ONCE(dst
->allocated_stack
< src
->allocated_stack
)) {
368 /* internal bug, make state invalid to reject the program */
369 memset(dst
, 0, sizeof(*dst
));
372 memcpy(dst
->stack
, src
->stack
,
373 sizeof(*src
->stack
) * (src
->allocated_stack
/ BPF_REG_SIZE
));
377 /* do_check() starts with zero-sized stack in struct bpf_verifier_state to
378 * make it consume minimal amount of memory. check_stack_write() access from
379 * the program calls into realloc_func_state() to grow the stack size.
380 * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
381 * which this function copies over. It points to previous bpf_verifier_state
382 * which is never reallocated
384 static int realloc_func_state(struct bpf_func_state
*state
, int size
,
387 u32 old_size
= state
->allocated_stack
;
388 struct bpf_stack_state
*new_stack
;
389 int slot
= size
/ BPF_REG_SIZE
;
391 if (size
<= old_size
|| !size
) {
394 state
->allocated_stack
= slot
* BPF_REG_SIZE
;
395 if (!size
&& old_size
) {
401 new_stack
= kmalloc_array(slot
, sizeof(struct bpf_stack_state
),
407 memcpy(new_stack
, state
->stack
,
408 sizeof(*new_stack
) * (old_size
/ BPF_REG_SIZE
));
409 memset(new_stack
+ old_size
/ BPF_REG_SIZE
, 0,
410 sizeof(*new_stack
) * (size
- old_size
) / BPF_REG_SIZE
);
412 state
->allocated_stack
= slot
* BPF_REG_SIZE
;
414 state
->stack
= new_stack
;
418 static void free_func_state(struct bpf_func_state
*state
)
426 static void free_verifier_state(struct bpf_verifier_state
*state
,
431 for (i
= 0; i
<= state
->curframe
; i
++) {
432 free_func_state(state
->frame
[i
]);
433 state
->frame
[i
] = NULL
;
439 /* copy verifier state from src to dst growing dst stack space
440 * when necessary to accommodate larger src stack
442 static int copy_func_state(struct bpf_func_state
*dst
,
443 const struct bpf_func_state
*src
)
447 err
= realloc_func_state(dst
, src
->allocated_stack
, false);
450 memcpy(dst
, src
, offsetof(struct bpf_func_state
, allocated_stack
));
451 return copy_stack_state(dst
, src
);
454 static int copy_verifier_state(struct bpf_verifier_state
*dst_state
,
455 const struct bpf_verifier_state
*src
)
457 struct bpf_func_state
*dst
;
460 /* if dst has more stack frames then src frame, free them */
461 for (i
= src
->curframe
+ 1; i
<= dst_state
->curframe
; i
++) {
462 free_func_state(dst_state
->frame
[i
]);
463 dst_state
->frame
[i
] = NULL
;
465 dst_state
->curframe
= src
->curframe
;
466 dst_state
->parent
= src
->parent
;
467 for (i
= 0; i
<= src
->curframe
; i
++) {
468 dst
= dst_state
->frame
[i
];
470 dst
= kzalloc(sizeof(*dst
), GFP_KERNEL
);
473 dst_state
->frame
[i
] = dst
;
475 err
= copy_func_state(dst
, src
->frame
[i
]);
482 static int pop_stack(struct bpf_verifier_env
*env
, int *prev_insn_idx
,
485 struct bpf_verifier_state
*cur
= env
->cur_state
;
486 struct bpf_verifier_stack_elem
*elem
, *head
= env
->head
;
489 if (env
->head
== NULL
)
493 err
= copy_verifier_state(cur
, &head
->st
);
498 *insn_idx
= head
->insn_idx
;
500 *prev_insn_idx
= head
->prev_insn_idx
;
502 free_verifier_state(&head
->st
, false);
509 static struct bpf_verifier_state
*push_stack(struct bpf_verifier_env
*env
,
510 int insn_idx
, int prev_insn_idx
)
512 struct bpf_verifier_state
*cur
= env
->cur_state
;
513 struct bpf_verifier_stack_elem
*elem
;
516 elem
= kzalloc(sizeof(struct bpf_verifier_stack_elem
), GFP_KERNEL
);
520 elem
->insn_idx
= insn_idx
;
521 elem
->prev_insn_idx
= prev_insn_idx
;
522 elem
->next
= env
->head
;
525 err
= copy_verifier_state(&elem
->st
, cur
);
528 if (env
->stack_size
> BPF_COMPLEXITY_LIMIT_STACK
) {
529 verbose(env
, "BPF program is too complex\n");
534 free_verifier_state(env
->cur_state
, true);
535 env
->cur_state
= NULL
;
536 /* pop all elements and return */
537 while (!pop_stack(env
, NULL
, NULL
));
541 #define CALLER_SAVED_REGS 6
542 static const int caller_saved
[CALLER_SAVED_REGS
] = {
543 BPF_REG_0
, BPF_REG_1
, BPF_REG_2
, BPF_REG_3
, BPF_REG_4
, BPF_REG_5
546 static void __mark_reg_not_init(struct bpf_reg_state
*reg
);
548 /* Mark the unknown part of a register (variable offset or scalar value) as
549 * known to have the value @imm.
551 static void __mark_reg_known(struct bpf_reg_state
*reg
, u64 imm
)
554 reg
->var_off
= tnum_const(imm
);
555 reg
->smin_value
= (s64
)imm
;
556 reg
->smax_value
= (s64
)imm
;
557 reg
->umin_value
= imm
;
558 reg
->umax_value
= imm
;
561 /* Mark the 'variable offset' part of a register as zero. This should be
562 * used only on registers holding a pointer type.
564 static void __mark_reg_known_zero(struct bpf_reg_state
*reg
)
566 __mark_reg_known(reg
, 0);
569 static void __mark_reg_const_zero(struct bpf_reg_state
*reg
)
571 __mark_reg_known(reg
, 0);
573 reg
->type
= SCALAR_VALUE
;
576 static void mark_reg_known_zero(struct bpf_verifier_env
*env
,
577 struct bpf_reg_state
*regs
, u32 regno
)
579 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
580 verbose(env
, "mark_reg_known_zero(regs, %u)\n", regno
);
581 /* Something bad happened, let's kill all regs */
582 for (regno
= 0; regno
< MAX_BPF_REG
; regno
++)
583 __mark_reg_not_init(regs
+ regno
);
586 __mark_reg_known_zero(regs
+ regno
);
589 static bool reg_is_pkt_pointer(const struct bpf_reg_state
*reg
)
591 return type_is_pkt_pointer(reg
->type
);
594 static bool reg_is_pkt_pointer_any(const struct bpf_reg_state
*reg
)
596 return reg_is_pkt_pointer(reg
) ||
597 reg
->type
== PTR_TO_PACKET_END
;
600 /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
601 static bool reg_is_init_pkt_pointer(const struct bpf_reg_state
*reg
,
602 enum bpf_reg_type which
)
604 /* The register can already have a range from prior markings.
605 * This is fine as long as it hasn't been advanced from its
608 return reg
->type
== which
&&
611 tnum_equals_const(reg
->var_off
, 0);
614 /* Attempts to improve min/max values based on var_off information */
615 static void __update_reg_bounds(struct bpf_reg_state
*reg
)
617 /* min signed is max(sign bit) | min(other bits) */
618 reg
->smin_value
= max_t(s64
, reg
->smin_value
,
619 reg
->var_off
.value
| (reg
->var_off
.mask
& S64_MIN
));
620 /* max signed is min(sign bit) | max(other bits) */
621 reg
->smax_value
= min_t(s64
, reg
->smax_value
,
622 reg
->var_off
.value
| (reg
->var_off
.mask
& S64_MAX
));
623 reg
->umin_value
= max(reg
->umin_value
, reg
->var_off
.value
);
624 reg
->umax_value
= min(reg
->umax_value
,
625 reg
->var_off
.value
| reg
->var_off
.mask
);
628 /* Uses signed min/max values to inform unsigned, and vice-versa */
629 static void __reg_deduce_bounds(struct bpf_reg_state
*reg
)
631 /* Learn sign from signed bounds.
632 * If we cannot cross the sign boundary, then signed and unsigned bounds
633 * are the same, so combine. This works even in the negative case, e.g.
634 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
636 if (reg
->smin_value
>= 0 || reg
->smax_value
< 0) {
637 reg
->smin_value
= reg
->umin_value
= max_t(u64
, reg
->smin_value
,
639 reg
->smax_value
= reg
->umax_value
= min_t(u64
, reg
->smax_value
,
643 /* Learn sign from unsigned bounds. Signed bounds cross the sign
644 * boundary, so we must be careful.
646 if ((s64
)reg
->umax_value
>= 0) {
647 /* Positive. We can't learn anything from the smin, but smax
648 * is positive, hence safe.
650 reg
->smin_value
= reg
->umin_value
;
651 reg
->smax_value
= reg
->umax_value
= min_t(u64
, reg
->smax_value
,
653 } else if ((s64
)reg
->umin_value
< 0) {
654 /* Negative. We can't learn anything from the smax, but smin
655 * is negative, hence safe.
657 reg
->smin_value
= reg
->umin_value
= max_t(u64
, reg
->smin_value
,
659 reg
->smax_value
= reg
->umax_value
;
663 /* Attempts to improve var_off based on unsigned min/max information */
664 static void __reg_bound_offset(struct bpf_reg_state
*reg
)
666 reg
->var_off
= tnum_intersect(reg
->var_off
,
667 tnum_range(reg
->umin_value
,
671 /* Reset the min/max bounds of a register */
672 static void __mark_reg_unbounded(struct bpf_reg_state
*reg
)
674 reg
->smin_value
= S64_MIN
;
675 reg
->smax_value
= S64_MAX
;
677 reg
->umax_value
= U64_MAX
;
680 /* Mark a register as having a completely unknown (scalar) value. */
681 static void __mark_reg_unknown(struct bpf_reg_state
*reg
)
683 reg
->type
= SCALAR_VALUE
;
686 reg
->var_off
= tnum_unknown
;
688 __mark_reg_unbounded(reg
);
691 static void mark_reg_unknown(struct bpf_verifier_env
*env
,
692 struct bpf_reg_state
*regs
, u32 regno
)
694 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
695 verbose(env
, "mark_reg_unknown(regs, %u)\n", regno
);
696 /* Something bad happened, let's kill all regs except FP */
697 for (regno
= 0; regno
< BPF_REG_FP
; regno
++)
698 __mark_reg_not_init(regs
+ regno
);
701 __mark_reg_unknown(regs
+ regno
);
704 static void __mark_reg_not_init(struct bpf_reg_state
*reg
)
706 __mark_reg_unknown(reg
);
707 reg
->type
= NOT_INIT
;
710 static void mark_reg_not_init(struct bpf_verifier_env
*env
,
711 struct bpf_reg_state
*regs
, u32 regno
)
713 if (WARN_ON(regno
>= MAX_BPF_REG
)) {
714 verbose(env
, "mark_reg_not_init(regs, %u)\n", regno
);
715 /* Something bad happened, let's kill all regs except FP */
716 for (regno
= 0; regno
< BPF_REG_FP
; regno
++)
717 __mark_reg_not_init(regs
+ regno
);
720 __mark_reg_not_init(regs
+ regno
);
723 static void init_reg_state(struct bpf_verifier_env
*env
,
724 struct bpf_func_state
*state
)
726 struct bpf_reg_state
*regs
= state
->regs
;
729 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
730 mark_reg_not_init(env
, regs
, i
);
731 regs
[i
].live
= REG_LIVE_NONE
;
735 regs
[BPF_REG_FP
].type
= PTR_TO_STACK
;
736 mark_reg_known_zero(env
, regs
, BPF_REG_FP
);
737 regs
[BPF_REG_FP
].frameno
= state
->frameno
;
739 /* 1st arg to a function */
740 regs
[BPF_REG_1
].type
= PTR_TO_CTX
;
741 mark_reg_known_zero(env
, regs
, BPF_REG_1
);
744 #define BPF_MAIN_FUNC (-1)
745 static void init_func_state(struct bpf_verifier_env
*env
,
746 struct bpf_func_state
*state
,
747 int callsite
, int frameno
, int subprogno
)
749 state
->callsite
= callsite
;
750 state
->frameno
= frameno
;
751 state
->subprogno
= subprogno
;
752 init_reg_state(env
, state
);
756 SRC_OP
, /* register is used as source operand */
757 DST_OP
, /* register is used as destination operand */
758 DST_OP_NO_MARK
/* same as above, check only, don't mark */
761 static int cmp_subprogs(const void *a
, const void *b
)
763 return *(int *)a
- *(int *)b
;
766 static int find_subprog(struct bpf_verifier_env
*env
, int off
)
770 p
= bsearch(&off
, env
->subprog_starts
, env
->subprog_cnt
,
771 sizeof(env
->subprog_starts
[0]), cmp_subprogs
);
774 return p
- env
->subprog_starts
;
778 static int add_subprog(struct bpf_verifier_env
*env
, int off
)
780 int insn_cnt
= env
->prog
->len
;
783 if (off
>= insn_cnt
|| off
< 0) {
784 verbose(env
, "call to invalid destination\n");
787 ret
= find_subprog(env
, off
);
790 if (env
->subprog_cnt
>= BPF_MAX_SUBPROGS
) {
791 verbose(env
, "too many subprograms\n");
794 env
->subprog_starts
[env
->subprog_cnt
++] = off
;
795 sort(env
->subprog_starts
, env
->subprog_cnt
,
796 sizeof(env
->subprog_starts
[0]), cmp_subprogs
, NULL
);
800 static int check_subprogs(struct bpf_verifier_env
*env
)
802 int i
, ret
, subprog_start
, subprog_end
, off
, cur_subprog
= 0;
803 struct bpf_insn
*insn
= env
->prog
->insnsi
;
804 int insn_cnt
= env
->prog
->len
;
806 /* determine subprog starts. The end is one before the next starts */
807 for (i
= 0; i
< insn_cnt
; i
++) {
808 if (insn
[i
].code
!= (BPF_JMP
| BPF_CALL
))
810 if (insn
[i
].src_reg
!= BPF_PSEUDO_CALL
)
812 if (!env
->allow_ptr_leaks
) {
813 verbose(env
, "function calls to other bpf functions are allowed for root only\n");
816 if (bpf_prog_is_dev_bound(env
->prog
->aux
)) {
817 verbose(env
, "function calls in offloaded programs are not supported yet\n");
820 ret
= add_subprog(env
, i
+ insn
[i
].imm
+ 1);
825 if (env
->log
.level
> 1)
826 for (i
= 0; i
< env
->subprog_cnt
; i
++)
827 verbose(env
, "func#%d @%d\n", i
, env
->subprog_starts
[i
]);
829 /* now check that all jumps are within the same subprog */
831 if (env
->subprog_cnt
== cur_subprog
)
832 subprog_end
= insn_cnt
;
834 subprog_end
= env
->subprog_starts
[cur_subprog
++];
835 for (i
= 0; i
< insn_cnt
; i
++) {
836 u8 code
= insn
[i
].code
;
838 if (BPF_CLASS(code
) != BPF_JMP
)
840 if (BPF_OP(code
) == BPF_EXIT
|| BPF_OP(code
) == BPF_CALL
)
842 off
= i
+ insn
[i
].off
+ 1;
843 if (off
< subprog_start
|| off
>= subprog_end
) {
844 verbose(env
, "jump out of range from insn %d to %d\n", i
, off
);
848 if (i
== subprog_end
- 1) {
849 /* to avoid fall-through from one subprog into another
850 * the last insn of the subprog should be either exit
851 * or unconditional jump back
853 if (code
!= (BPF_JMP
| BPF_EXIT
) &&
854 code
!= (BPF_JMP
| BPF_JA
)) {
855 verbose(env
, "last insn is not an exit or jmp\n");
858 subprog_start
= subprog_end
;
859 if (env
->subprog_cnt
== cur_subprog
)
860 subprog_end
= insn_cnt
;
862 subprog_end
= env
->subprog_starts
[cur_subprog
++];
869 struct bpf_verifier_state
*skip_callee(struct bpf_verifier_env
*env
,
870 const struct bpf_verifier_state
*state
,
871 struct bpf_verifier_state
*parent
,
874 struct bpf_verifier_state
*tmp
= NULL
;
876 /* 'parent' could be a state of caller and
877 * 'state' could be a state of callee. In such case
878 * parent->curframe < state->curframe
879 * and it's ok for r1 - r5 registers
881 * 'parent' could be a callee's state after it bpf_exit-ed.
882 * In such case parent->curframe > state->curframe
883 * and it's ok for r0 only
885 if (parent
->curframe
== state
->curframe
||
886 (parent
->curframe
< state
->curframe
&&
887 regno
>= BPF_REG_1
&& regno
<= BPF_REG_5
) ||
888 (parent
->curframe
> state
->curframe
&&
892 if (parent
->curframe
> state
->curframe
&&
893 regno
>= BPF_REG_6
) {
894 /* for callee saved regs we have to skip the whole chain
895 * of states that belong to callee and mark as LIVE_READ
896 * the registers before the call
899 while (tmp
&& tmp
->curframe
!= state
->curframe
) {
910 verbose(env
, "verifier bug regno %d tmp %p\n", regno
, tmp
);
911 verbose(env
, "regno %d parent frame %d current frame %d\n",
912 regno
, parent
->curframe
, state
->curframe
);
916 static int mark_reg_read(struct bpf_verifier_env
*env
,
917 const struct bpf_verifier_state
*state
,
918 struct bpf_verifier_state
*parent
,
921 bool writes
= parent
== state
->parent
; /* Observe write marks */
923 if (regno
== BPF_REG_FP
)
924 /* We don't need to worry about FP liveness because it's read-only */
928 /* if read wasn't screened by an earlier write ... */
929 if (writes
&& state
->frame
[state
->curframe
]->regs
[regno
].live
& REG_LIVE_WRITTEN
)
931 parent
= skip_callee(env
, state
, parent
, regno
);
934 /* ... then we depend on parent's value */
935 parent
->frame
[parent
->curframe
]->regs
[regno
].live
|= REG_LIVE_READ
;
937 parent
= state
->parent
;
943 static int check_reg_arg(struct bpf_verifier_env
*env
, u32 regno
,
946 struct bpf_verifier_state
*vstate
= env
->cur_state
;
947 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
948 struct bpf_reg_state
*regs
= state
->regs
;
950 if (regno
>= MAX_BPF_REG
) {
951 verbose(env
, "R%d is invalid\n", regno
);
956 /* check whether register used as source operand can be read */
957 if (regs
[regno
].type
== NOT_INIT
) {
958 verbose(env
, "R%d !read_ok\n", regno
);
961 return mark_reg_read(env
, vstate
, vstate
->parent
, regno
);
963 /* check whether register used as dest operand can be written to */
964 if (regno
== BPF_REG_FP
) {
965 verbose(env
, "frame pointer is read only\n");
968 regs
[regno
].live
|= REG_LIVE_WRITTEN
;
970 mark_reg_unknown(env
, regs
, regno
);
975 static bool is_spillable_regtype(enum bpf_reg_type type
)
978 case PTR_TO_MAP_VALUE
:
979 case PTR_TO_MAP_VALUE_OR_NULL
:
983 case PTR_TO_PACKET_META
:
984 case PTR_TO_PACKET_END
:
985 case CONST_PTR_TO_MAP
:
992 /* Does this register contain a constant zero? */
993 static bool register_is_null(struct bpf_reg_state
*reg
)
995 return reg
->type
== SCALAR_VALUE
&& tnum_equals_const(reg
->var_off
, 0);
998 /* check_stack_read/write functions track spill/fill of registers,
999 * stack boundary and alignment are checked in check_mem_access()
1001 static int check_stack_write(struct bpf_verifier_env
*env
,
1002 struct bpf_func_state
*state
, /* func where register points to */
1003 int off
, int size
, int value_regno
, int insn_idx
)
1005 struct bpf_func_state
*cur
; /* state of the current function */
1006 int i
, slot
= -off
- 1, spi
= slot
/ BPF_REG_SIZE
, err
;
1007 enum bpf_reg_type type
;
1009 err
= realloc_func_state(state
, round_up(slot
+ 1, BPF_REG_SIZE
),
1013 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
1014 * so it's aligned access and [off, off + size) are within stack limits
1016 if (!env
->allow_ptr_leaks
&&
1017 state
->stack
[spi
].slot_type
[0] == STACK_SPILL
&&
1018 size
!= BPF_REG_SIZE
) {
1019 verbose(env
, "attempt to corrupt spilled pointer on stack\n");
1023 cur
= env
->cur_state
->frame
[env
->cur_state
->curframe
];
1024 if (value_regno
>= 0 &&
1025 is_spillable_regtype((type
= cur
->regs
[value_regno
].type
))) {
1027 /* register containing pointer is being spilled into stack */
1028 if (size
!= BPF_REG_SIZE
) {
1029 verbose(env
, "invalid size of register spill\n");
1033 if (state
!= cur
&& type
== PTR_TO_STACK
) {
1034 verbose(env
, "cannot spill pointers to stack into stack frame of the caller\n");
1038 /* save register state */
1039 state
->stack
[spi
].spilled_ptr
= cur
->regs
[value_regno
];
1040 state
->stack
[spi
].spilled_ptr
.live
|= REG_LIVE_WRITTEN
;
1042 for (i
= 0; i
< BPF_REG_SIZE
; i
++) {
1043 if (state
->stack
[spi
].slot_type
[i
] == STACK_MISC
&&
1044 !env
->allow_ptr_leaks
) {
1045 int *poff
= &env
->insn_aux_data
[insn_idx
].sanitize_stack_off
;
1046 int soff
= (-spi
- 1) * BPF_REG_SIZE
;
1048 /* detected reuse of integer stack slot with a pointer
1049 * which means either llvm is reusing stack slot or
1050 * an attacker is trying to exploit CVE-2018-3639
1051 * (speculative store bypass)
1052 * Have to sanitize that slot with preemptive
1055 if (*poff
&& *poff
!= soff
) {
1056 /* disallow programs where single insn stores
1057 * into two different stack slots, since verifier
1058 * cannot sanitize them
1061 "insn %d cannot access two stack slots fp%d and fp%d",
1062 insn_idx
, *poff
, soff
);
1067 state
->stack
[spi
].slot_type
[i
] = STACK_SPILL
;
1070 u8 type
= STACK_MISC
;
1072 /* regular write of data into stack */
1073 state
->stack
[spi
].spilled_ptr
= (struct bpf_reg_state
) {};
1075 /* only mark the slot as written if all 8 bytes were written
1076 * otherwise read propagation may incorrectly stop too soon
1077 * when stack slots are partially written.
1078 * This heuristic means that read propagation will be
1079 * conservative, since it will add reg_live_read marks
1080 * to stack slots all the way to first state when programs
1081 * writes+reads less than 8 bytes
1083 if (size
== BPF_REG_SIZE
)
1084 state
->stack
[spi
].spilled_ptr
.live
|= REG_LIVE_WRITTEN
;
1086 /* when we zero initialize stack slots mark them as such */
1087 if (value_regno
>= 0 &&
1088 register_is_null(&cur
->regs
[value_regno
]))
1091 for (i
= 0; i
< size
; i
++)
1092 state
->stack
[spi
].slot_type
[(slot
- i
) % BPF_REG_SIZE
] =
1098 /* registers of every function are unique and mark_reg_read() propagates
1099 * the liveness in the following cases:
1100 * - from callee into caller for R1 - R5 that were used as arguments
1101 * - from caller into callee for R0 that used as result of the call
1102 * - from caller to the same caller skipping states of the callee for R6 - R9,
1103 * since R6 - R9 are callee saved by implicit function prologue and
1104 * caller's R6 != callee's R6, so when we propagate liveness up to
1105 * parent states we need to skip callee states for R6 - R9.
1107 * stack slot marking is different, since stacks of caller and callee are
1108 * accessible in both (since caller can pass a pointer to caller's stack to
1109 * callee which can pass it to another function), hence mark_stack_slot_read()
1110 * has to propagate the stack liveness to all parent states at given frame number.
1120 * First *ptr is reading from f1's stack and mark_stack_slot_read() has
1121 * to mark liveness at the f1's frame and not f2's frame.
1122 * Second *ptr is also reading from f1's stack and mark_stack_slot_read() has
1123 * to propagate liveness to f2 states at f1's frame level and further into
1124 * f1 states at f1's frame level until write into that stack slot
1126 static void mark_stack_slot_read(struct bpf_verifier_env
*env
,
1127 const struct bpf_verifier_state
*state
,
1128 struct bpf_verifier_state
*parent
,
1129 int slot
, int frameno
)
1131 bool writes
= parent
== state
->parent
; /* Observe write marks */
1134 if (parent
->frame
[frameno
]->allocated_stack
<= slot
* BPF_REG_SIZE
)
1135 /* since LIVE_WRITTEN mark is only done for full 8-byte
1136 * write the read marks are conservative and parent
1137 * state may not even have the stack allocated. In such case
1138 * end the propagation, since the loop reached beginning
1142 /* if read wasn't screened by an earlier write ... */
1143 if (writes
&& state
->frame
[frameno
]->stack
[slot
].spilled_ptr
.live
& REG_LIVE_WRITTEN
)
1145 /* ... then we depend on parent's value */
1146 parent
->frame
[frameno
]->stack
[slot
].spilled_ptr
.live
|= REG_LIVE_READ
;
1148 parent
= state
->parent
;
1153 static int check_stack_read(struct bpf_verifier_env
*env
,
1154 struct bpf_func_state
*reg_state
/* func where register points to */,
1155 int off
, int size
, int value_regno
)
1157 struct bpf_verifier_state
*vstate
= env
->cur_state
;
1158 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
1159 int i
, slot
= -off
- 1, spi
= slot
/ BPF_REG_SIZE
;
1162 if (reg_state
->allocated_stack
<= slot
) {
1163 verbose(env
, "invalid read from stack off %d+0 size %d\n",
1167 stype
= reg_state
->stack
[spi
].slot_type
;
1169 if (stype
[0] == STACK_SPILL
) {
1170 if (size
!= BPF_REG_SIZE
) {
1171 verbose(env
, "invalid size of register spill\n");
1174 for (i
= 1; i
< BPF_REG_SIZE
; i
++) {
1175 if (stype
[(slot
- i
) % BPF_REG_SIZE
] != STACK_SPILL
) {
1176 verbose(env
, "corrupted spill memory\n");
1181 if (value_regno
>= 0) {
1182 /* restore register state from stack */
1183 state
->regs
[value_regno
] = reg_state
->stack
[spi
].spilled_ptr
;
1184 /* mark reg as written since spilled pointer state likely
1185 * has its liveness marks cleared by is_state_visited()
1186 * which resets stack/reg liveness for state transitions
1188 state
->regs
[value_regno
].live
|= REG_LIVE_WRITTEN
;
1190 mark_stack_slot_read(env
, vstate
, vstate
->parent
, spi
,
1191 reg_state
->frameno
);
1196 for (i
= 0; i
< size
; i
++) {
1197 if (stype
[(slot
- i
) % BPF_REG_SIZE
] == STACK_MISC
)
1199 if (stype
[(slot
- i
) % BPF_REG_SIZE
] == STACK_ZERO
) {
1203 verbose(env
, "invalid read from stack off %d+%d size %d\n",
1207 mark_stack_slot_read(env
, vstate
, vstate
->parent
, spi
,
1208 reg_state
->frameno
);
1209 if (value_regno
>= 0) {
1210 if (zeros
== size
) {
1211 /* any size read into register is zero extended,
1212 * so the whole register == const_zero
1214 __mark_reg_const_zero(&state
->regs
[value_regno
]);
1216 /* have read misc data from the stack */
1217 mark_reg_unknown(env
, state
->regs
, value_regno
);
1219 state
->regs
[value_regno
].live
|= REG_LIVE_WRITTEN
;
1225 /* check read/write into map element returned by bpf_map_lookup_elem() */
1226 static int __check_map_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
1227 int size
, bool zero_size_allowed
)
1229 struct bpf_reg_state
*regs
= cur_regs(env
);
1230 struct bpf_map
*map
= regs
[regno
].map_ptr
;
1232 if (off
< 0 || size
< 0 || (size
== 0 && !zero_size_allowed
) ||
1233 off
+ size
> map
->value_size
) {
1234 verbose(env
, "invalid access to map value, value_size=%d off=%d size=%d\n",
1235 map
->value_size
, off
, size
);
1241 /* check read/write into a map element with possible variable offset */
1242 static int check_map_access(struct bpf_verifier_env
*env
, u32 regno
,
1243 int off
, int size
, bool zero_size_allowed
)
1245 struct bpf_verifier_state
*vstate
= env
->cur_state
;
1246 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
1247 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
1250 /* We may have adjusted the register to this map value, so we
1251 * need to try adding each of min_value and max_value to off
1252 * to make sure our theoretical access will be safe.
1255 print_verifier_state(env
, state
);
1256 /* The minimum value is only important with signed
1257 * comparisons where we can't assume the floor of a
1258 * value is 0. If we are using signed variables for our
1259 * index'es we need to make sure that whatever we use
1260 * will have a set floor within our range.
1262 if (reg
->smin_value
< 0) {
1263 verbose(env
, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
1267 err
= __check_map_access(env
, regno
, reg
->smin_value
+ off
, size
,
1270 verbose(env
, "R%d min value is outside of the array range\n",
1275 /* If we haven't set a max value then we need to bail since we can't be
1276 * sure we won't do bad things.
1277 * If reg->umax_value + off could overflow, treat that as unbounded too.
1279 if (reg
->umax_value
>= BPF_MAX_VAR_OFF
) {
1280 verbose(env
, "R%d unbounded memory access, make sure to bounds check any array access into a map\n",
1284 err
= __check_map_access(env
, regno
, reg
->umax_value
+ off
, size
,
1287 verbose(env
, "R%d max value is outside of the array range\n",
1292 #define MAX_PACKET_OFF 0xffff
1294 static bool may_access_direct_pkt_data(struct bpf_verifier_env
*env
,
1295 const struct bpf_call_arg_meta
*meta
,
1296 enum bpf_access_type t
)
1298 switch (env
->prog
->type
) {
1299 case BPF_PROG_TYPE_LWT_IN
:
1300 case BPF_PROG_TYPE_LWT_OUT
:
1301 /* dst_input() and dst_output() can't write for now */
1305 case BPF_PROG_TYPE_SCHED_CLS
:
1306 case BPF_PROG_TYPE_SCHED_ACT
:
1307 case BPF_PROG_TYPE_XDP
:
1308 case BPF_PROG_TYPE_LWT_XMIT
:
1309 case BPF_PROG_TYPE_SK_SKB
:
1310 case BPF_PROG_TYPE_SK_MSG
:
1312 return meta
->pkt_access
;
1314 env
->seen_direct_write
= true;
1321 static int __check_packet_access(struct bpf_verifier_env
*env
, u32 regno
,
1322 int off
, int size
, bool zero_size_allowed
)
1324 struct bpf_reg_state
*regs
= cur_regs(env
);
1325 struct bpf_reg_state
*reg
= ®s
[regno
];
1327 if (off
< 0 || size
< 0 || (size
== 0 && !zero_size_allowed
) ||
1328 (u64
)off
+ size
> reg
->range
) {
1329 verbose(env
, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
1330 off
, size
, regno
, reg
->id
, reg
->off
, reg
->range
);
1336 static int check_packet_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
1337 int size
, bool zero_size_allowed
)
1339 struct bpf_reg_state
*regs
= cur_regs(env
);
1340 struct bpf_reg_state
*reg
= ®s
[regno
];
1343 /* We may have added a variable offset to the packet pointer; but any
1344 * reg->range we have comes after that. We are only checking the fixed
1348 /* We don't allow negative numbers, because we aren't tracking enough
1349 * detail to prove they're safe.
1351 if (reg
->smin_value
< 0) {
1352 verbose(env
, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
1356 err
= __check_packet_access(env
, regno
, off
, size
, zero_size_allowed
);
1358 verbose(env
, "R%d offset is outside of the packet\n", regno
);
1364 /* check access to 'struct bpf_context' fields. Supports fixed offsets only */
1365 static int check_ctx_access(struct bpf_verifier_env
*env
, int insn_idx
, int off
, int size
,
1366 enum bpf_access_type t
, enum bpf_reg_type
*reg_type
)
1368 struct bpf_insn_access_aux info
= {
1369 .reg_type
= *reg_type
,
1372 if (env
->ops
->is_valid_access
&&
1373 env
->ops
->is_valid_access(off
, size
, t
, env
->prog
, &info
)) {
1374 /* A non zero info.ctx_field_size indicates that this field is a
1375 * candidate for later verifier transformation to load the whole
1376 * field and then apply a mask when accessed with a narrower
1377 * access than actual ctx access size. A zero info.ctx_field_size
1378 * will only allow for whole field access and rejects any other
1379 * type of narrower access.
1381 *reg_type
= info
.reg_type
;
1383 env
->insn_aux_data
[insn_idx
].ctx_field_size
= info
.ctx_field_size
;
1384 /* remember the offset of last byte accessed in ctx */
1385 if (env
->prog
->aux
->max_ctx_offset
< off
+ size
)
1386 env
->prog
->aux
->max_ctx_offset
= off
+ size
;
1390 verbose(env
, "invalid bpf_context access off=%d size=%d\n", off
, size
);
1394 static bool __is_pointer_value(bool allow_ptr_leaks
,
1395 const struct bpf_reg_state
*reg
)
1397 if (allow_ptr_leaks
)
1400 return reg
->type
!= SCALAR_VALUE
;
1403 static bool is_pointer_value(struct bpf_verifier_env
*env
, int regno
)
1405 return __is_pointer_value(env
->allow_ptr_leaks
, cur_regs(env
) + regno
);
1408 static bool is_ctx_reg(struct bpf_verifier_env
*env
, int regno
)
1410 const struct bpf_reg_state
*reg
= cur_regs(env
) + regno
;
1412 return reg
->type
== PTR_TO_CTX
;
1415 static bool is_pkt_reg(struct bpf_verifier_env
*env
, int regno
)
1417 const struct bpf_reg_state
*reg
= cur_regs(env
) + regno
;
1419 return type_is_pkt_pointer(reg
->type
);
1422 static int check_pkt_ptr_alignment(struct bpf_verifier_env
*env
,
1423 const struct bpf_reg_state
*reg
,
1424 int off
, int size
, bool strict
)
1426 struct tnum reg_off
;
1429 /* Byte size accesses are always allowed. */
1430 if (!strict
|| size
== 1)
1433 /* For platforms that do not have a Kconfig enabling
1434 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
1435 * NET_IP_ALIGN is universally set to '2'. And on platforms
1436 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
1437 * to this code only in strict mode where we want to emulate
1438 * the NET_IP_ALIGN==2 checking. Therefore use an
1439 * unconditional IP align value of '2'.
1443 reg_off
= tnum_add(reg
->var_off
, tnum_const(ip_align
+ reg
->off
+ off
));
1444 if (!tnum_is_aligned(reg_off
, size
)) {
1447 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1449 "misaligned packet access off %d+%s+%d+%d size %d\n",
1450 ip_align
, tn_buf
, reg
->off
, off
, size
);
1457 static int check_generic_ptr_alignment(struct bpf_verifier_env
*env
,
1458 const struct bpf_reg_state
*reg
,
1459 const char *pointer_desc
,
1460 int off
, int size
, bool strict
)
1462 struct tnum reg_off
;
1464 /* Byte size accesses are always allowed. */
1465 if (!strict
|| size
== 1)
1468 reg_off
= tnum_add(reg
->var_off
, tnum_const(reg
->off
+ off
));
1469 if (!tnum_is_aligned(reg_off
, size
)) {
1472 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1473 verbose(env
, "misaligned %saccess off %s+%d+%d size %d\n",
1474 pointer_desc
, tn_buf
, reg
->off
, off
, size
);
1481 static int check_ptr_alignment(struct bpf_verifier_env
*env
,
1482 const struct bpf_reg_state
*reg
, int off
,
1483 int size
, bool strict_alignment_once
)
1485 bool strict
= env
->strict_alignment
|| strict_alignment_once
;
1486 const char *pointer_desc
= "";
1488 switch (reg
->type
) {
1490 case PTR_TO_PACKET_META
:
1491 /* Special case, because of NET_IP_ALIGN. Given metadata sits
1492 * right in front, treat it the very same way.
1494 return check_pkt_ptr_alignment(env
, reg
, off
, size
, strict
);
1495 case PTR_TO_MAP_VALUE
:
1496 pointer_desc
= "value ";
1499 pointer_desc
= "context ";
1502 pointer_desc
= "stack ";
1503 /* The stack spill tracking logic in check_stack_write()
1504 * and check_stack_read() relies on stack accesses being
1512 return check_generic_ptr_alignment(env
, reg
, pointer_desc
, off
, size
,
1516 static int update_stack_depth(struct bpf_verifier_env
*env
,
1517 const struct bpf_func_state
*func
,
1520 u16 stack
= env
->subprog_stack_depth
[func
->subprogno
];
1525 /* update known max for given subprogram */
1526 env
->subprog_stack_depth
[func
->subprogno
] = -off
;
1530 /* starting from main bpf function walk all instructions of the function
1531 * and recursively walk all callees that given function can call.
1532 * Ignore jump and exit insns.
1533 * Since recursion is prevented by check_cfg() this algorithm
1534 * only needs a local stack of MAX_CALL_FRAMES to remember callsites
1536 static int check_max_stack_depth(struct bpf_verifier_env
*env
)
1538 int depth
= 0, frame
= 0, subprog
= 0, i
= 0, subprog_end
;
1539 struct bpf_insn
*insn
= env
->prog
->insnsi
;
1540 int insn_cnt
= env
->prog
->len
;
1541 int ret_insn
[MAX_CALL_FRAMES
];
1542 int ret_prog
[MAX_CALL_FRAMES
];
1545 /* round up to 32-bytes, since this is granularity
1546 * of interpreter stack size
1548 depth
+= round_up(max_t(u32
, env
->subprog_stack_depth
[subprog
], 1), 32);
1549 if (depth
> MAX_BPF_STACK
) {
1550 verbose(env
, "combined stack size of %d calls is %d. Too large\n",
1555 if (env
->subprog_cnt
== subprog
)
1556 subprog_end
= insn_cnt
;
1558 subprog_end
= env
->subprog_starts
[subprog
];
1559 for (; i
< subprog_end
; i
++) {
1560 if (insn
[i
].code
!= (BPF_JMP
| BPF_CALL
))
1562 if (insn
[i
].src_reg
!= BPF_PSEUDO_CALL
)
1564 /* remember insn and function to return to */
1565 ret_insn
[frame
] = i
+ 1;
1566 ret_prog
[frame
] = subprog
;
1568 /* find the callee */
1569 i
= i
+ insn
[i
].imm
+ 1;
1570 subprog
= find_subprog(env
, i
);
1572 WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
1578 if (frame
>= MAX_CALL_FRAMES
) {
1579 WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
1584 /* end of for() loop means the last insn of the 'subprog'
1585 * was reached. Doesn't matter whether it was JA or EXIT
1589 depth
-= round_up(max_t(u32
, env
->subprog_stack_depth
[subprog
], 1), 32);
1591 i
= ret_insn
[frame
];
1592 subprog
= ret_prog
[frame
];
1596 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
1597 static int get_callee_stack_depth(struct bpf_verifier_env
*env
,
1598 const struct bpf_insn
*insn
, int idx
)
1600 int start
= idx
+ insn
->imm
+ 1, subprog
;
1602 subprog
= find_subprog(env
, start
);
1604 WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
1609 return env
->subprog_stack_depth
[subprog
];
1613 /* truncate register to smaller size (in bytes)
1614 * must be called with size < BPF_REG_SIZE
1616 static void coerce_reg_to_size(struct bpf_reg_state
*reg
, int size
)
1620 /* clear high bits in bit representation */
1621 reg
->var_off
= tnum_cast(reg
->var_off
, size
);
1623 /* fix arithmetic bounds */
1624 mask
= ((u64
)1 << (size
* 8)) - 1;
1625 if ((reg
->umin_value
& ~mask
) == (reg
->umax_value
& ~mask
)) {
1626 reg
->umin_value
&= mask
;
1627 reg
->umax_value
&= mask
;
1629 reg
->umin_value
= 0;
1630 reg
->umax_value
= mask
;
1632 reg
->smin_value
= reg
->umin_value
;
1633 reg
->smax_value
= reg
->umax_value
;
1636 /* check whether memory at (regno + off) is accessible for t = (read | write)
1637 * if t==write, value_regno is a register which value is stored into memory
1638 * if t==read, value_regno is a register which will receive the value from memory
1639 * if t==write && value_regno==-1, some unknown value is stored into memory
1640 * if t==read && value_regno==-1, don't care what we read from memory
1642 static int check_mem_access(struct bpf_verifier_env
*env
, int insn_idx
, u32 regno
,
1643 int off
, int bpf_size
, enum bpf_access_type t
,
1644 int value_regno
, bool strict_alignment_once
)
1646 struct bpf_reg_state
*regs
= cur_regs(env
);
1647 struct bpf_reg_state
*reg
= regs
+ regno
;
1648 struct bpf_func_state
*state
;
1651 size
= bpf_size_to_bytes(bpf_size
);
1655 /* alignment checks will add in reg->off themselves */
1656 err
= check_ptr_alignment(env
, reg
, off
, size
, strict_alignment_once
);
1660 /* for access checks, reg->off is just part of off */
1663 if (reg
->type
== PTR_TO_MAP_VALUE
) {
1664 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1665 is_pointer_value(env
, value_regno
)) {
1666 verbose(env
, "R%d leaks addr into map\n", value_regno
);
1670 err
= check_map_access(env
, regno
, off
, size
, false);
1671 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
1672 mark_reg_unknown(env
, regs
, value_regno
);
1674 } else if (reg
->type
== PTR_TO_CTX
) {
1675 enum bpf_reg_type reg_type
= SCALAR_VALUE
;
1677 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1678 is_pointer_value(env
, value_regno
)) {
1679 verbose(env
, "R%d leaks addr into ctx\n", value_regno
);
1682 /* ctx accesses must be at a fixed offset, so that we can
1683 * determine what type of data were returned.
1687 "dereference of modified ctx ptr R%d off=%d+%d, ctx+const is allowed, ctx+const+const is not\n",
1688 regno
, reg
->off
, off
- reg
->off
);
1691 if (!tnum_is_const(reg
->var_off
) || reg
->var_off
.value
) {
1694 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1696 "variable ctx access var_off=%s off=%d size=%d",
1700 err
= check_ctx_access(env
, insn_idx
, off
, size
, t
, ®_type
);
1701 if (!err
&& t
== BPF_READ
&& value_regno
>= 0) {
1702 /* ctx access returns either a scalar, or a
1703 * PTR_TO_PACKET[_META,_END]. In the latter
1704 * case, we know the offset is zero.
1706 if (reg_type
== SCALAR_VALUE
)
1707 mark_reg_unknown(env
, regs
, value_regno
);
1709 mark_reg_known_zero(env
, regs
,
1711 regs
[value_regno
].id
= 0;
1712 regs
[value_regno
].off
= 0;
1713 regs
[value_regno
].range
= 0;
1714 regs
[value_regno
].type
= reg_type
;
1717 } else if (reg
->type
== PTR_TO_STACK
) {
1718 /* stack accesses must be at a fixed offset, so that we can
1719 * determine what type of data were returned.
1720 * See check_stack_read().
1722 if (!tnum_is_const(reg
->var_off
)) {
1725 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1726 verbose(env
, "variable stack access var_off=%s off=%d size=%d",
1730 off
+= reg
->var_off
.value
;
1731 if (off
>= 0 || off
< -MAX_BPF_STACK
) {
1732 verbose(env
, "invalid stack off=%d size=%d\n", off
,
1737 state
= func(env
, reg
);
1738 err
= update_stack_depth(env
, state
, off
);
1743 err
= check_stack_write(env
, state
, off
, size
,
1744 value_regno
, insn_idx
);
1746 err
= check_stack_read(env
, state
, off
, size
,
1748 } else if (reg_is_pkt_pointer(reg
)) {
1749 if (t
== BPF_WRITE
&& !may_access_direct_pkt_data(env
, NULL
, t
)) {
1750 verbose(env
, "cannot write into packet\n");
1753 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
1754 is_pointer_value(env
, value_regno
)) {
1755 verbose(env
, "R%d leaks addr into packet\n",
1759 err
= check_packet_access(env
, regno
, off
, size
, false);
1760 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
1761 mark_reg_unknown(env
, regs
, value_regno
);
1763 verbose(env
, "R%d invalid mem access '%s'\n", regno
,
1764 reg_type_str
[reg
->type
]);
1768 if (!err
&& size
< BPF_REG_SIZE
&& value_regno
>= 0 && t
== BPF_READ
&&
1769 regs
[value_regno
].type
== SCALAR_VALUE
) {
1770 /* b/h/w load zero-extends, mark upper bits as known 0 */
1771 coerce_reg_to_size(®s
[value_regno
], size
);
1776 static int check_xadd(struct bpf_verifier_env
*env
, int insn_idx
, struct bpf_insn
*insn
)
1780 if ((BPF_SIZE(insn
->code
) != BPF_W
&& BPF_SIZE(insn
->code
) != BPF_DW
) ||
1782 verbose(env
, "BPF_XADD uses reserved fields\n");
1786 /* check src1 operand */
1787 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
1791 /* check src2 operand */
1792 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
1796 if (is_pointer_value(env
, insn
->src_reg
)) {
1797 verbose(env
, "R%d leaks addr into mem\n", insn
->src_reg
);
1801 if (is_ctx_reg(env
, insn
->dst_reg
) ||
1802 is_pkt_reg(env
, insn
->dst_reg
)) {
1803 verbose(env
, "BPF_XADD stores into R%d %s is not allowed\n",
1804 insn
->dst_reg
, is_ctx_reg(env
, insn
->dst_reg
) ?
1805 "context" : "packet");
1809 /* check whether atomic_add can read the memory */
1810 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1811 BPF_SIZE(insn
->code
), BPF_READ
, -1, true);
1815 /* check whether atomic_add can write into the same memory */
1816 return check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1817 BPF_SIZE(insn
->code
), BPF_WRITE
, -1, true);
1820 /* when register 'regno' is passed into function that will read 'access_size'
1821 * bytes from that pointer, make sure that it's within stack boundary
1822 * and all elements of stack are initialized.
1823 * Unlike most pointer bounds-checking functions, this one doesn't take an
1824 * 'off' argument, so it has to add in reg->off itself.
1826 static int check_stack_boundary(struct bpf_verifier_env
*env
, int regno
,
1827 int access_size
, bool zero_size_allowed
,
1828 struct bpf_call_arg_meta
*meta
)
1830 struct bpf_reg_state
*reg
= cur_regs(env
) + regno
;
1831 struct bpf_func_state
*state
= func(env
, reg
);
1832 int off
, i
, slot
, spi
;
1834 if (reg
->type
!= PTR_TO_STACK
) {
1835 /* Allow zero-byte read from NULL, regardless of pointer type */
1836 if (zero_size_allowed
&& access_size
== 0 &&
1837 register_is_null(reg
))
1840 verbose(env
, "R%d type=%s expected=%s\n", regno
,
1841 reg_type_str
[reg
->type
],
1842 reg_type_str
[PTR_TO_STACK
]);
1846 /* Only allow fixed-offset stack reads */
1847 if (!tnum_is_const(reg
->var_off
)) {
1850 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
1851 verbose(env
, "invalid variable stack read R%d var_off=%s\n",
1855 off
= reg
->off
+ reg
->var_off
.value
;
1856 if (off
>= 0 || off
< -MAX_BPF_STACK
|| off
+ access_size
> 0 ||
1857 access_size
< 0 || (access_size
== 0 && !zero_size_allowed
)) {
1858 verbose(env
, "invalid stack type R%d off=%d access_size=%d\n",
1859 regno
, off
, access_size
);
1863 if (meta
&& meta
->raw_mode
) {
1864 meta
->access_size
= access_size
;
1865 meta
->regno
= regno
;
1869 for (i
= 0; i
< access_size
; i
++) {
1872 slot
= -(off
+ i
) - 1;
1873 spi
= slot
/ BPF_REG_SIZE
;
1874 if (state
->allocated_stack
<= slot
)
1876 stype
= &state
->stack
[spi
].slot_type
[slot
% BPF_REG_SIZE
];
1877 if (*stype
== STACK_MISC
)
1879 if (*stype
== STACK_ZERO
) {
1880 /* helper can write anything into the stack */
1881 *stype
= STACK_MISC
;
1885 verbose(env
, "invalid indirect read from stack off %d+%d size %d\n",
1886 off
, i
, access_size
);
1889 /* reading any byte out of 8-byte 'spill_slot' will cause
1890 * the whole slot to be marked as 'read'
1892 mark_stack_slot_read(env
, env
->cur_state
, env
->cur_state
->parent
,
1893 spi
, state
->frameno
);
1895 return update_stack_depth(env
, state
, off
);
1898 static int check_helper_mem_access(struct bpf_verifier_env
*env
, int regno
,
1899 int access_size
, bool zero_size_allowed
,
1900 struct bpf_call_arg_meta
*meta
)
1902 struct bpf_reg_state
*regs
= cur_regs(env
), *reg
= ®s
[regno
];
1904 switch (reg
->type
) {
1906 case PTR_TO_PACKET_META
:
1907 return check_packet_access(env
, regno
, reg
->off
, access_size
,
1909 case PTR_TO_MAP_VALUE
:
1910 return check_map_access(env
, regno
, reg
->off
, access_size
,
1912 default: /* scalar_value|ptr_to_stack or invalid ptr */
1913 return check_stack_boundary(env
, regno
, access_size
,
1914 zero_size_allowed
, meta
);
1918 static bool arg_type_is_mem_ptr(enum bpf_arg_type type
)
1920 return type
== ARG_PTR_TO_MEM
||
1921 type
== ARG_PTR_TO_MEM_OR_NULL
||
1922 type
== ARG_PTR_TO_UNINIT_MEM
;
1925 static bool arg_type_is_mem_size(enum bpf_arg_type type
)
1927 return type
== ARG_CONST_SIZE
||
1928 type
== ARG_CONST_SIZE_OR_ZERO
;
1931 static int check_func_arg(struct bpf_verifier_env
*env
, u32 regno
,
1932 enum bpf_arg_type arg_type
,
1933 struct bpf_call_arg_meta
*meta
)
1935 struct bpf_reg_state
*regs
= cur_regs(env
), *reg
= ®s
[regno
];
1936 enum bpf_reg_type expected_type
, type
= reg
->type
;
1939 if (arg_type
== ARG_DONTCARE
)
1942 err
= check_reg_arg(env
, regno
, SRC_OP
);
1946 if (arg_type
== ARG_ANYTHING
) {
1947 if (is_pointer_value(env
, regno
)) {
1948 verbose(env
, "R%d leaks addr into helper function\n",
1955 if (type_is_pkt_pointer(type
) &&
1956 !may_access_direct_pkt_data(env
, meta
, BPF_READ
)) {
1957 verbose(env
, "helper access to the packet is not allowed\n");
1961 if (arg_type
== ARG_PTR_TO_MAP_KEY
||
1962 arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1963 expected_type
= PTR_TO_STACK
;
1964 if (!type_is_pkt_pointer(type
) &&
1965 type
!= expected_type
)
1967 } else if (arg_type
== ARG_CONST_SIZE
||
1968 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1969 expected_type
= SCALAR_VALUE
;
1970 if (type
!= expected_type
)
1972 } else if (arg_type
== ARG_CONST_MAP_PTR
) {
1973 expected_type
= CONST_PTR_TO_MAP
;
1974 if (type
!= expected_type
)
1976 } else if (arg_type
== ARG_PTR_TO_CTX
) {
1977 expected_type
= PTR_TO_CTX
;
1978 if (type
!= expected_type
)
1980 } else if (arg_type_is_mem_ptr(arg_type
)) {
1981 expected_type
= PTR_TO_STACK
;
1982 /* One exception here. In case function allows for NULL to be
1983 * passed in as argument, it's a SCALAR_VALUE type. Final test
1984 * happens during stack boundary checking.
1986 if (register_is_null(reg
) &&
1987 arg_type
== ARG_PTR_TO_MEM_OR_NULL
)
1988 /* final test in check_stack_boundary() */;
1989 else if (!type_is_pkt_pointer(type
) &&
1990 type
!= PTR_TO_MAP_VALUE
&&
1991 type
!= expected_type
)
1993 meta
->raw_mode
= arg_type
== ARG_PTR_TO_UNINIT_MEM
;
1995 verbose(env
, "unsupported arg_type %d\n", arg_type
);
1999 if (arg_type
== ARG_CONST_MAP_PTR
) {
2000 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
2001 meta
->map_ptr
= reg
->map_ptr
;
2002 } else if (arg_type
== ARG_PTR_TO_MAP_KEY
) {
2003 /* bpf_map_xxx(..., map_ptr, ..., key) call:
2004 * check that [key, key + map->key_size) are within
2005 * stack limits and initialized
2007 if (!meta
->map_ptr
) {
2008 /* in function declaration map_ptr must come before
2009 * map_key, so that it's verified and known before
2010 * we have to check map_key here. Otherwise it means
2011 * that kernel subsystem misconfigured verifier
2013 verbose(env
, "invalid map_ptr to access map->key\n");
2016 if (type_is_pkt_pointer(type
))
2017 err
= check_packet_access(env
, regno
, reg
->off
,
2018 meta
->map_ptr
->key_size
,
2021 err
= check_stack_boundary(env
, regno
,
2022 meta
->map_ptr
->key_size
,
2024 } else if (arg_type
== ARG_PTR_TO_MAP_VALUE
) {
2025 /* bpf_map_xxx(..., map_ptr, ..., value) call:
2026 * check [value, value + map->value_size) validity
2028 if (!meta
->map_ptr
) {
2029 /* kernel subsystem misconfigured verifier */
2030 verbose(env
, "invalid map_ptr to access map->value\n");
2033 if (type_is_pkt_pointer(type
))
2034 err
= check_packet_access(env
, regno
, reg
->off
,
2035 meta
->map_ptr
->value_size
,
2038 err
= check_stack_boundary(env
, regno
,
2039 meta
->map_ptr
->value_size
,
2041 } else if (arg_type_is_mem_size(arg_type
)) {
2042 bool zero_size_allowed
= (arg_type
== ARG_CONST_SIZE_OR_ZERO
);
2044 /* The register is SCALAR_VALUE; the access check
2045 * happens using its boundaries.
2047 if (!tnum_is_const(reg
->var_off
))
2048 /* For unprivileged variable accesses, disable raw
2049 * mode so that the program is required to
2050 * initialize all the memory that the helper could
2051 * just partially fill up.
2055 if (reg
->smin_value
< 0) {
2056 verbose(env
, "R%d min value is negative, either use unsigned or 'var &= const'\n",
2061 if (reg
->umin_value
== 0) {
2062 err
= check_helper_mem_access(env
, regno
- 1, 0,
2069 if (reg
->umax_value
>= BPF_MAX_VAR_SIZ
) {
2070 verbose(env
, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
2074 err
= check_helper_mem_access(env
, regno
- 1,
2076 zero_size_allowed
, meta
);
2081 verbose(env
, "R%d type=%s expected=%s\n", regno
,
2082 reg_type_str
[type
], reg_type_str
[expected_type
]);
2086 static int check_map_func_compatibility(struct bpf_verifier_env
*env
,
2087 struct bpf_map
*map
, int func_id
)
2092 /* We need a two way check, first is from map perspective ... */
2093 switch (map
->map_type
) {
2094 case BPF_MAP_TYPE_PROG_ARRAY
:
2095 if (func_id
!= BPF_FUNC_tail_call
)
2098 case BPF_MAP_TYPE_PERF_EVENT_ARRAY
:
2099 if (func_id
!= BPF_FUNC_perf_event_read
&&
2100 func_id
!= BPF_FUNC_perf_event_output
&&
2101 func_id
!= BPF_FUNC_perf_event_read_value
)
2104 case BPF_MAP_TYPE_STACK_TRACE
:
2105 if (func_id
!= BPF_FUNC_get_stackid
)
2108 case BPF_MAP_TYPE_CGROUP_ARRAY
:
2109 if (func_id
!= BPF_FUNC_skb_under_cgroup
&&
2110 func_id
!= BPF_FUNC_current_task_under_cgroup
)
2113 /* devmap returns a pointer to a live net_device ifindex that we cannot
2114 * allow to be modified from bpf side. So do not allow lookup elements
2117 case BPF_MAP_TYPE_DEVMAP
:
2118 if (func_id
!= BPF_FUNC_redirect_map
)
2121 /* Restrict bpf side of cpumap, open when use-cases appear */
2122 case BPF_MAP_TYPE_CPUMAP
:
2123 if (func_id
!= BPF_FUNC_redirect_map
)
2126 case BPF_MAP_TYPE_ARRAY_OF_MAPS
:
2127 case BPF_MAP_TYPE_HASH_OF_MAPS
:
2128 if (func_id
!= BPF_FUNC_map_lookup_elem
)
2131 case BPF_MAP_TYPE_SOCKMAP
:
2132 if (func_id
!= BPF_FUNC_sk_redirect_map
&&
2133 func_id
!= BPF_FUNC_sock_map_update
&&
2134 func_id
!= BPF_FUNC_map_delete_elem
&&
2135 func_id
!= BPF_FUNC_msg_redirect_map
)
2142 /* ... and second from the function itself. */
2144 case BPF_FUNC_tail_call
:
2145 if (map
->map_type
!= BPF_MAP_TYPE_PROG_ARRAY
)
2147 if (env
->subprog_cnt
) {
2148 verbose(env
, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
2152 case BPF_FUNC_perf_event_read
:
2153 case BPF_FUNC_perf_event_output
:
2154 case BPF_FUNC_perf_event_read_value
:
2155 if (map
->map_type
!= BPF_MAP_TYPE_PERF_EVENT_ARRAY
)
2158 case BPF_FUNC_get_stackid
:
2159 if (map
->map_type
!= BPF_MAP_TYPE_STACK_TRACE
)
2162 case BPF_FUNC_current_task_under_cgroup
:
2163 case BPF_FUNC_skb_under_cgroup
:
2164 if (map
->map_type
!= BPF_MAP_TYPE_CGROUP_ARRAY
)
2167 case BPF_FUNC_redirect_map
:
2168 if (map
->map_type
!= BPF_MAP_TYPE_DEVMAP
&&
2169 map
->map_type
!= BPF_MAP_TYPE_CPUMAP
)
2172 case BPF_FUNC_sk_redirect_map
:
2173 case BPF_FUNC_msg_redirect_map
:
2174 if (map
->map_type
!= BPF_MAP_TYPE_SOCKMAP
)
2177 case BPF_FUNC_sock_map_update
:
2178 if (map
->map_type
!= BPF_MAP_TYPE_SOCKMAP
)
2187 verbose(env
, "cannot pass map_type %d into func %s#%d\n",
2188 map
->map_type
, func_id_name(func_id
), func_id
);
2192 static bool check_raw_mode_ok(const struct bpf_func_proto
*fn
)
2196 if (fn
->arg1_type
== ARG_PTR_TO_UNINIT_MEM
)
2198 if (fn
->arg2_type
== ARG_PTR_TO_UNINIT_MEM
)
2200 if (fn
->arg3_type
== ARG_PTR_TO_UNINIT_MEM
)
2202 if (fn
->arg4_type
== ARG_PTR_TO_UNINIT_MEM
)
2204 if (fn
->arg5_type
== ARG_PTR_TO_UNINIT_MEM
)
2207 /* We only support one arg being in raw mode at the moment,
2208 * which is sufficient for the helper functions we have
2214 static bool check_args_pair_invalid(enum bpf_arg_type arg_curr
,
2215 enum bpf_arg_type arg_next
)
2217 return (arg_type_is_mem_ptr(arg_curr
) &&
2218 !arg_type_is_mem_size(arg_next
)) ||
2219 (!arg_type_is_mem_ptr(arg_curr
) &&
2220 arg_type_is_mem_size(arg_next
));
2223 static bool check_arg_pair_ok(const struct bpf_func_proto
*fn
)
2225 /* bpf_xxx(..., buf, len) call will access 'len'
2226 * bytes from memory 'buf'. Both arg types need
2227 * to be paired, so make sure there's no buggy
2228 * helper function specification.
2230 if (arg_type_is_mem_size(fn
->arg1_type
) ||
2231 arg_type_is_mem_ptr(fn
->arg5_type
) ||
2232 check_args_pair_invalid(fn
->arg1_type
, fn
->arg2_type
) ||
2233 check_args_pair_invalid(fn
->arg2_type
, fn
->arg3_type
) ||
2234 check_args_pair_invalid(fn
->arg3_type
, fn
->arg4_type
) ||
2235 check_args_pair_invalid(fn
->arg4_type
, fn
->arg5_type
))
2241 static int check_func_proto(const struct bpf_func_proto
*fn
)
2243 return check_raw_mode_ok(fn
) &&
2244 check_arg_pair_ok(fn
) ? 0 : -EINVAL
;
2247 /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
2248 * are now invalid, so turn them into unknown SCALAR_VALUE.
2250 static void __clear_all_pkt_pointers(struct bpf_verifier_env
*env
,
2251 struct bpf_func_state
*state
)
2253 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
2256 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2257 if (reg_is_pkt_pointer_any(®s
[i
]))
2258 mark_reg_unknown(env
, regs
, i
);
2260 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
2261 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
2263 reg
= &state
->stack
[i
].spilled_ptr
;
2264 if (reg_is_pkt_pointer_any(reg
))
2265 __mark_reg_unknown(reg
);
2269 static void clear_all_pkt_pointers(struct bpf_verifier_env
*env
)
2271 struct bpf_verifier_state
*vstate
= env
->cur_state
;
2274 for (i
= 0; i
<= vstate
->curframe
; i
++)
2275 __clear_all_pkt_pointers(env
, vstate
->frame
[i
]);
2278 static int check_func_call(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
,
2281 struct bpf_verifier_state
*state
= env
->cur_state
;
2282 struct bpf_func_state
*caller
, *callee
;
2283 int i
, subprog
, target_insn
;
2285 if (state
->curframe
+ 1 >= MAX_CALL_FRAMES
) {
2286 verbose(env
, "the call stack of %d frames is too deep\n",
2287 state
->curframe
+ 2);
2291 target_insn
= *insn_idx
+ insn
->imm
;
2292 subprog
= find_subprog(env
, target_insn
+ 1);
2294 verbose(env
, "verifier bug. No program starts at insn %d\n",
2299 caller
= state
->frame
[state
->curframe
];
2300 if (state
->frame
[state
->curframe
+ 1]) {
2301 verbose(env
, "verifier bug. Frame %d already allocated\n",
2302 state
->curframe
+ 1);
2306 callee
= kzalloc(sizeof(*callee
), GFP_KERNEL
);
2309 state
->frame
[state
->curframe
+ 1] = callee
;
2311 /* callee cannot access r0, r6 - r9 for reading and has to write
2312 * into its own stack before reading from it.
2313 * callee can read/write into caller's stack
2315 init_func_state(env
, callee
,
2316 /* remember the callsite, it will be used by bpf_exit */
2317 *insn_idx
/* callsite */,
2318 state
->curframe
+ 1 /* frameno within this callchain */,
2319 subprog
+ 1 /* subprog number within this prog */);
2321 /* copy r1 - r5 args that callee can access */
2322 for (i
= BPF_REG_1
; i
<= BPF_REG_5
; i
++)
2323 callee
->regs
[i
] = caller
->regs
[i
];
2325 /* after the call regsiters r0 - r5 were scratched */
2326 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
2327 mark_reg_not_init(env
, caller
->regs
, caller_saved
[i
]);
2328 check_reg_arg(env
, caller_saved
[i
], DST_OP_NO_MARK
);
2331 /* only increment it after check_reg_arg() finished */
2334 /* and go analyze first insn of the callee */
2335 *insn_idx
= target_insn
;
2337 if (env
->log
.level
) {
2338 verbose(env
, "caller:\n");
2339 print_verifier_state(env
, caller
);
2340 verbose(env
, "callee:\n");
2341 print_verifier_state(env
, callee
);
2346 static int prepare_func_exit(struct bpf_verifier_env
*env
, int *insn_idx
)
2348 struct bpf_verifier_state
*state
= env
->cur_state
;
2349 struct bpf_func_state
*caller
, *callee
;
2350 struct bpf_reg_state
*r0
;
2352 callee
= state
->frame
[state
->curframe
];
2353 r0
= &callee
->regs
[BPF_REG_0
];
2354 if (r0
->type
== PTR_TO_STACK
) {
2355 /* technically it's ok to return caller's stack pointer
2356 * (or caller's caller's pointer) back to the caller,
2357 * since these pointers are valid. Only current stack
2358 * pointer will be invalid as soon as function exits,
2359 * but let's be conservative
2361 verbose(env
, "cannot return stack pointer to the caller\n");
2366 caller
= state
->frame
[state
->curframe
];
2367 /* return to the caller whatever r0 had in the callee */
2368 caller
->regs
[BPF_REG_0
] = *r0
;
2370 *insn_idx
= callee
->callsite
+ 1;
2371 if (env
->log
.level
) {
2372 verbose(env
, "returning from callee:\n");
2373 print_verifier_state(env
, callee
);
2374 verbose(env
, "to caller at %d:\n", *insn_idx
);
2375 print_verifier_state(env
, caller
);
2377 /* clear everything in the callee */
2378 free_func_state(callee
);
2379 state
->frame
[state
->curframe
+ 1] = NULL
;
2384 record_func_map(struct bpf_verifier_env
*env
, struct bpf_call_arg_meta
*meta
,
2385 int func_id
, int insn_idx
)
2387 struct bpf_insn_aux_data
*aux
= &env
->insn_aux_data
[insn_idx
];
2389 if (func_id
!= BPF_FUNC_tail_call
&&
2390 func_id
!= BPF_FUNC_map_lookup_elem
)
2392 if (meta
->map_ptr
== NULL
) {
2393 verbose(env
, "kernel subsystem misconfigured verifier\n");
2397 if (!BPF_MAP_PTR(aux
->map_state
))
2398 bpf_map_ptr_store(aux
, meta
->map_ptr
,
2399 meta
->map_ptr
->unpriv_array
);
2400 else if (BPF_MAP_PTR(aux
->map_state
) != meta
->map_ptr
)
2401 bpf_map_ptr_store(aux
, BPF_MAP_PTR_POISON
,
2402 meta
->map_ptr
->unpriv_array
);
2406 static int check_helper_call(struct bpf_verifier_env
*env
, int func_id
, int insn_idx
)
2408 const struct bpf_func_proto
*fn
= NULL
;
2409 struct bpf_reg_state
*regs
;
2410 struct bpf_call_arg_meta meta
;
2414 /* find function prototype */
2415 if (func_id
< 0 || func_id
>= __BPF_FUNC_MAX_ID
) {
2416 verbose(env
, "invalid func %s#%d\n", func_id_name(func_id
),
2421 if (env
->ops
->get_func_proto
)
2422 fn
= env
->ops
->get_func_proto(func_id
, env
->prog
);
2424 verbose(env
, "unknown func %s#%d\n", func_id_name(func_id
),
2429 /* eBPF programs must be GPL compatible to use GPL-ed functions */
2430 if (!env
->prog
->gpl_compatible
&& fn
->gpl_only
) {
2431 verbose(env
, "cannot call GPL only function from proprietary program\n");
2435 /* With LD_ABS/IND some JITs save/restore skb from r1. */
2436 changes_data
= bpf_helper_changes_pkt_data(fn
->func
);
2437 if (changes_data
&& fn
->arg1_type
!= ARG_PTR_TO_CTX
) {
2438 verbose(env
, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
2439 func_id_name(func_id
), func_id
);
2443 memset(&meta
, 0, sizeof(meta
));
2444 meta
.pkt_access
= fn
->pkt_access
;
2446 err
= check_func_proto(fn
);
2448 verbose(env
, "kernel subsystem misconfigured func %s#%d\n",
2449 func_id_name(func_id
), func_id
);
2454 err
= check_func_arg(env
, BPF_REG_1
, fn
->arg1_type
, &meta
);
2457 err
= check_func_arg(env
, BPF_REG_2
, fn
->arg2_type
, &meta
);
2460 err
= check_func_arg(env
, BPF_REG_3
, fn
->arg3_type
, &meta
);
2463 err
= check_func_arg(env
, BPF_REG_4
, fn
->arg4_type
, &meta
);
2466 err
= check_func_arg(env
, BPF_REG_5
, fn
->arg5_type
, &meta
);
2470 err
= record_func_map(env
, &meta
, func_id
, insn_idx
);
2474 /* Mark slots with STACK_MISC in case of raw mode, stack offset
2475 * is inferred from register state.
2477 for (i
= 0; i
< meta
.access_size
; i
++) {
2478 err
= check_mem_access(env
, insn_idx
, meta
.regno
, i
, BPF_B
,
2479 BPF_WRITE
, -1, false);
2484 regs
= cur_regs(env
);
2485 /* reset caller saved regs */
2486 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
2487 mark_reg_not_init(env
, regs
, caller_saved
[i
]);
2488 check_reg_arg(env
, caller_saved
[i
], DST_OP_NO_MARK
);
2491 /* update return register (already marked as written above) */
2492 if (fn
->ret_type
== RET_INTEGER
) {
2493 /* sets type to SCALAR_VALUE */
2494 mark_reg_unknown(env
, regs
, BPF_REG_0
);
2495 } else if (fn
->ret_type
== RET_VOID
) {
2496 regs
[BPF_REG_0
].type
= NOT_INIT
;
2497 } else if (fn
->ret_type
== RET_PTR_TO_MAP_VALUE_OR_NULL
) {
2498 regs
[BPF_REG_0
].type
= PTR_TO_MAP_VALUE_OR_NULL
;
2499 /* There is no offset yet applied, variable or fixed */
2500 mark_reg_known_zero(env
, regs
, BPF_REG_0
);
2501 regs
[BPF_REG_0
].off
= 0;
2502 /* remember map_ptr, so that check_map_access()
2503 * can check 'value_size' boundary of memory access
2504 * to map element returned from bpf_map_lookup_elem()
2506 if (meta
.map_ptr
== NULL
) {
2508 "kernel subsystem misconfigured verifier\n");
2511 regs
[BPF_REG_0
].map_ptr
= meta
.map_ptr
;
2512 regs
[BPF_REG_0
].id
= ++env
->id_gen
;
2514 verbose(env
, "unknown return type %d of func %s#%d\n",
2515 fn
->ret_type
, func_id_name(func_id
), func_id
);
2519 err
= check_map_func_compatibility(env
, meta
.map_ptr
, func_id
);
2524 clear_all_pkt_pointers(env
);
2528 static bool signed_add_overflows(s64 a
, s64 b
)
2530 /* Do the add in u64, where overflow is well-defined */
2531 s64 res
= (s64
)((u64
)a
+ (u64
)b
);
2538 static bool signed_sub_overflows(s64 a
, s64 b
)
2540 /* Do the sub in u64, where overflow is well-defined */
2541 s64 res
= (s64
)((u64
)a
- (u64
)b
);
2548 static bool check_reg_sane_offset(struct bpf_verifier_env
*env
,
2549 const struct bpf_reg_state
*reg
,
2550 enum bpf_reg_type type
)
2552 bool known
= tnum_is_const(reg
->var_off
);
2553 s64 val
= reg
->var_off
.value
;
2554 s64 smin
= reg
->smin_value
;
2556 if (known
&& (val
>= BPF_MAX_VAR_OFF
|| val
<= -BPF_MAX_VAR_OFF
)) {
2557 verbose(env
, "math between %s pointer and %lld is not allowed\n",
2558 reg_type_str
[type
], val
);
2562 if (reg
->off
>= BPF_MAX_VAR_OFF
|| reg
->off
<= -BPF_MAX_VAR_OFF
) {
2563 verbose(env
, "%s pointer offset %d is not allowed\n",
2564 reg_type_str
[type
], reg
->off
);
2568 if (smin
== S64_MIN
) {
2569 verbose(env
, "math between %s pointer and register with unbounded min value is not allowed\n",
2570 reg_type_str
[type
]);
2574 if (smin
>= BPF_MAX_VAR_OFF
|| smin
<= -BPF_MAX_VAR_OFF
) {
2575 verbose(env
, "value %lld makes %s pointer be out of bounds\n",
2576 smin
, reg_type_str
[type
]);
2583 /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
2584 * Caller should also handle BPF_MOV case separately.
2585 * If we return -EACCES, caller may want to try again treating pointer as a
2586 * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
2588 static int adjust_ptr_min_max_vals(struct bpf_verifier_env
*env
,
2589 struct bpf_insn
*insn
,
2590 const struct bpf_reg_state
*ptr_reg
,
2591 const struct bpf_reg_state
*off_reg
)
2593 struct bpf_verifier_state
*vstate
= env
->cur_state
;
2594 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
2595 struct bpf_reg_state
*regs
= state
->regs
, *dst_reg
;
2596 bool known
= tnum_is_const(off_reg
->var_off
);
2597 s64 smin_val
= off_reg
->smin_value
, smax_val
= off_reg
->smax_value
,
2598 smin_ptr
= ptr_reg
->smin_value
, smax_ptr
= ptr_reg
->smax_value
;
2599 u64 umin_val
= off_reg
->umin_value
, umax_val
= off_reg
->umax_value
,
2600 umin_ptr
= ptr_reg
->umin_value
, umax_ptr
= ptr_reg
->umax_value
;
2601 u8 opcode
= BPF_OP(insn
->code
);
2602 u32 dst
= insn
->dst_reg
;
2604 dst_reg
= ®s
[dst
];
2606 if ((known
&& (smin_val
!= smax_val
|| umin_val
!= umax_val
)) ||
2607 smin_val
> smax_val
|| umin_val
> umax_val
) {
2608 /* Taint dst register if offset had invalid bounds derived from
2609 * e.g. dead branches.
2611 __mark_reg_unknown(dst_reg
);
2615 if (BPF_CLASS(insn
->code
) != BPF_ALU64
) {
2616 /* 32-bit ALU ops on pointers produce (meaningless) scalars */
2618 "R%d 32-bit pointer arithmetic prohibited\n",
2623 if (ptr_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
2624 verbose(env
, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n",
2628 if (ptr_reg
->type
== CONST_PTR_TO_MAP
) {
2629 verbose(env
, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n",
2633 if (ptr_reg
->type
== PTR_TO_PACKET_END
) {
2634 verbose(env
, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n",
2639 /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
2640 * The id may be overwritten later if we create a new variable offset.
2642 dst_reg
->type
= ptr_reg
->type
;
2643 dst_reg
->id
= ptr_reg
->id
;
2645 if (!check_reg_sane_offset(env
, off_reg
, ptr_reg
->type
) ||
2646 !check_reg_sane_offset(env
, ptr_reg
, ptr_reg
->type
))
2651 /* We can take a fixed offset as long as it doesn't overflow
2652 * the s32 'off' field
2654 if (known
&& (ptr_reg
->off
+ smin_val
==
2655 (s64
)(s32
)(ptr_reg
->off
+ smin_val
))) {
2656 /* pointer += K. Accumulate it into fixed offset */
2657 dst_reg
->smin_value
= smin_ptr
;
2658 dst_reg
->smax_value
= smax_ptr
;
2659 dst_reg
->umin_value
= umin_ptr
;
2660 dst_reg
->umax_value
= umax_ptr
;
2661 dst_reg
->var_off
= ptr_reg
->var_off
;
2662 dst_reg
->off
= ptr_reg
->off
+ smin_val
;
2663 dst_reg
->range
= ptr_reg
->range
;
2666 /* A new variable offset is created. Note that off_reg->off
2667 * == 0, since it's a scalar.
2668 * dst_reg gets the pointer type and since some positive
2669 * integer value was added to the pointer, give it a new 'id'
2670 * if it's a PTR_TO_PACKET.
2671 * this creates a new 'base' pointer, off_reg (variable) gets
2672 * added into the variable offset, and we copy the fixed offset
2675 if (signed_add_overflows(smin_ptr
, smin_val
) ||
2676 signed_add_overflows(smax_ptr
, smax_val
)) {
2677 dst_reg
->smin_value
= S64_MIN
;
2678 dst_reg
->smax_value
= S64_MAX
;
2680 dst_reg
->smin_value
= smin_ptr
+ smin_val
;
2681 dst_reg
->smax_value
= smax_ptr
+ smax_val
;
2683 if (umin_ptr
+ umin_val
< umin_ptr
||
2684 umax_ptr
+ umax_val
< umax_ptr
) {
2685 dst_reg
->umin_value
= 0;
2686 dst_reg
->umax_value
= U64_MAX
;
2688 dst_reg
->umin_value
= umin_ptr
+ umin_val
;
2689 dst_reg
->umax_value
= umax_ptr
+ umax_val
;
2691 dst_reg
->var_off
= tnum_add(ptr_reg
->var_off
, off_reg
->var_off
);
2692 dst_reg
->off
= ptr_reg
->off
;
2693 if (reg_is_pkt_pointer(ptr_reg
)) {
2694 dst_reg
->id
= ++env
->id_gen
;
2695 /* something was added to pkt_ptr, set range to zero */
2700 if (dst_reg
== off_reg
) {
2701 /* scalar -= pointer. Creates an unknown scalar */
2702 verbose(env
, "R%d tried to subtract pointer from scalar\n",
2706 /* We don't allow subtraction from FP, because (according to
2707 * test_verifier.c test "invalid fp arithmetic", JITs might not
2708 * be able to deal with it.
2710 if (ptr_reg
->type
== PTR_TO_STACK
) {
2711 verbose(env
, "R%d subtraction from stack pointer prohibited\n",
2715 if (known
&& (ptr_reg
->off
- smin_val
==
2716 (s64
)(s32
)(ptr_reg
->off
- smin_val
))) {
2717 /* pointer -= K. Subtract it from fixed offset */
2718 dst_reg
->smin_value
= smin_ptr
;
2719 dst_reg
->smax_value
= smax_ptr
;
2720 dst_reg
->umin_value
= umin_ptr
;
2721 dst_reg
->umax_value
= umax_ptr
;
2722 dst_reg
->var_off
= ptr_reg
->var_off
;
2723 dst_reg
->id
= ptr_reg
->id
;
2724 dst_reg
->off
= ptr_reg
->off
- smin_val
;
2725 dst_reg
->range
= ptr_reg
->range
;
2728 /* A new variable offset is created. If the subtrahend is known
2729 * nonnegative, then any reg->range we had before is still good.
2731 if (signed_sub_overflows(smin_ptr
, smax_val
) ||
2732 signed_sub_overflows(smax_ptr
, smin_val
)) {
2733 /* Overflow possible, we know nothing */
2734 dst_reg
->smin_value
= S64_MIN
;
2735 dst_reg
->smax_value
= S64_MAX
;
2737 dst_reg
->smin_value
= smin_ptr
- smax_val
;
2738 dst_reg
->smax_value
= smax_ptr
- smin_val
;
2740 if (umin_ptr
< umax_val
) {
2741 /* Overflow possible, we know nothing */
2742 dst_reg
->umin_value
= 0;
2743 dst_reg
->umax_value
= U64_MAX
;
2745 /* Cannot overflow (as long as bounds are consistent) */
2746 dst_reg
->umin_value
= umin_ptr
- umax_val
;
2747 dst_reg
->umax_value
= umax_ptr
- umin_val
;
2749 dst_reg
->var_off
= tnum_sub(ptr_reg
->var_off
, off_reg
->var_off
);
2750 dst_reg
->off
= ptr_reg
->off
;
2751 if (reg_is_pkt_pointer(ptr_reg
)) {
2752 dst_reg
->id
= ++env
->id_gen
;
2753 /* something was added to pkt_ptr, set range to zero */
2761 /* bitwise ops on pointers are troublesome, prohibit. */
2762 verbose(env
, "R%d bitwise operator %s on pointer prohibited\n",
2763 dst
, bpf_alu_string
[opcode
>> 4]);
2766 /* other operators (e.g. MUL,LSH) produce non-pointer results */
2767 verbose(env
, "R%d pointer arithmetic with %s operator prohibited\n",
2768 dst
, bpf_alu_string
[opcode
>> 4]);
2772 if (!check_reg_sane_offset(env
, dst_reg
, ptr_reg
->type
))
2775 __update_reg_bounds(dst_reg
);
2776 __reg_deduce_bounds(dst_reg
);
2777 __reg_bound_offset(dst_reg
);
2781 /* WARNING: This function does calculations on 64-bit values, but the actual
2782 * execution may occur on 32-bit values. Therefore, things like bitshifts
2783 * need extra checks in the 32-bit case.
2785 static int adjust_scalar_min_max_vals(struct bpf_verifier_env
*env
,
2786 struct bpf_insn
*insn
,
2787 struct bpf_reg_state
*dst_reg
,
2788 struct bpf_reg_state src_reg
)
2790 struct bpf_reg_state
*regs
= cur_regs(env
);
2791 u8 opcode
= BPF_OP(insn
->code
);
2792 bool src_known
, dst_known
;
2793 s64 smin_val
, smax_val
;
2794 u64 umin_val
, umax_val
;
2795 u64 insn_bitness
= (BPF_CLASS(insn
->code
) == BPF_ALU64
) ? 64 : 32;
2797 smin_val
= src_reg
.smin_value
;
2798 smax_val
= src_reg
.smax_value
;
2799 umin_val
= src_reg
.umin_value
;
2800 umax_val
= src_reg
.umax_value
;
2801 src_known
= tnum_is_const(src_reg
.var_off
);
2802 dst_known
= tnum_is_const(dst_reg
->var_off
);
2804 if ((src_known
&& (smin_val
!= smax_val
|| umin_val
!= umax_val
)) ||
2805 smin_val
> smax_val
|| umin_val
> umax_val
) {
2806 /* Taint dst register if offset had invalid bounds derived from
2807 * e.g. dead branches.
2809 __mark_reg_unknown(dst_reg
);
2814 opcode
!= BPF_ADD
&& opcode
!= BPF_SUB
&& opcode
!= BPF_AND
) {
2815 __mark_reg_unknown(dst_reg
);
2821 if (signed_add_overflows(dst_reg
->smin_value
, smin_val
) ||
2822 signed_add_overflows(dst_reg
->smax_value
, smax_val
)) {
2823 dst_reg
->smin_value
= S64_MIN
;
2824 dst_reg
->smax_value
= S64_MAX
;
2826 dst_reg
->smin_value
+= smin_val
;
2827 dst_reg
->smax_value
+= smax_val
;
2829 if (dst_reg
->umin_value
+ umin_val
< umin_val
||
2830 dst_reg
->umax_value
+ umax_val
< umax_val
) {
2831 dst_reg
->umin_value
= 0;
2832 dst_reg
->umax_value
= U64_MAX
;
2834 dst_reg
->umin_value
+= umin_val
;
2835 dst_reg
->umax_value
+= umax_val
;
2837 dst_reg
->var_off
= tnum_add(dst_reg
->var_off
, src_reg
.var_off
);
2840 if (signed_sub_overflows(dst_reg
->smin_value
, smax_val
) ||
2841 signed_sub_overflows(dst_reg
->smax_value
, smin_val
)) {
2842 /* Overflow possible, we know nothing */
2843 dst_reg
->smin_value
= S64_MIN
;
2844 dst_reg
->smax_value
= S64_MAX
;
2846 dst_reg
->smin_value
-= smax_val
;
2847 dst_reg
->smax_value
-= smin_val
;
2849 if (dst_reg
->umin_value
< umax_val
) {
2850 /* Overflow possible, we know nothing */
2851 dst_reg
->umin_value
= 0;
2852 dst_reg
->umax_value
= U64_MAX
;
2854 /* Cannot overflow (as long as bounds are consistent) */
2855 dst_reg
->umin_value
-= umax_val
;
2856 dst_reg
->umax_value
-= umin_val
;
2858 dst_reg
->var_off
= tnum_sub(dst_reg
->var_off
, src_reg
.var_off
);
2861 dst_reg
->var_off
= tnum_mul(dst_reg
->var_off
, src_reg
.var_off
);
2862 if (smin_val
< 0 || dst_reg
->smin_value
< 0) {
2863 /* Ain't nobody got time to multiply that sign */
2864 __mark_reg_unbounded(dst_reg
);
2865 __update_reg_bounds(dst_reg
);
2868 /* Both values are positive, so we can work with unsigned and
2869 * copy the result to signed (unless it exceeds S64_MAX).
2871 if (umax_val
> U32_MAX
|| dst_reg
->umax_value
> U32_MAX
) {
2872 /* Potential overflow, we know nothing */
2873 __mark_reg_unbounded(dst_reg
);
2874 /* (except what we can learn from the var_off) */
2875 __update_reg_bounds(dst_reg
);
2878 dst_reg
->umin_value
*= umin_val
;
2879 dst_reg
->umax_value
*= umax_val
;
2880 if (dst_reg
->umax_value
> S64_MAX
) {
2881 /* Overflow possible, we know nothing */
2882 dst_reg
->smin_value
= S64_MIN
;
2883 dst_reg
->smax_value
= S64_MAX
;
2885 dst_reg
->smin_value
= dst_reg
->umin_value
;
2886 dst_reg
->smax_value
= dst_reg
->umax_value
;
2890 if (src_known
&& dst_known
) {
2891 __mark_reg_known(dst_reg
, dst_reg
->var_off
.value
&
2892 src_reg
.var_off
.value
);
2895 /* We get our minimum from the var_off, since that's inherently
2896 * bitwise. Our maximum is the minimum of the operands' maxima.
2898 dst_reg
->var_off
= tnum_and(dst_reg
->var_off
, src_reg
.var_off
);
2899 dst_reg
->umin_value
= dst_reg
->var_off
.value
;
2900 dst_reg
->umax_value
= min(dst_reg
->umax_value
, umax_val
);
2901 if (dst_reg
->smin_value
< 0 || smin_val
< 0) {
2902 /* Lose signed bounds when ANDing negative numbers,
2903 * ain't nobody got time for that.
2905 dst_reg
->smin_value
= S64_MIN
;
2906 dst_reg
->smax_value
= S64_MAX
;
2908 /* ANDing two positives gives a positive, so safe to
2909 * cast result into s64.
2911 dst_reg
->smin_value
= dst_reg
->umin_value
;
2912 dst_reg
->smax_value
= dst_reg
->umax_value
;
2914 /* We may learn something more from the var_off */
2915 __update_reg_bounds(dst_reg
);
2918 if (src_known
&& dst_known
) {
2919 __mark_reg_known(dst_reg
, dst_reg
->var_off
.value
|
2920 src_reg
.var_off
.value
);
2923 /* We get our maximum from the var_off, and our minimum is the
2924 * maximum of the operands' minima
2926 dst_reg
->var_off
= tnum_or(dst_reg
->var_off
, src_reg
.var_off
);
2927 dst_reg
->umin_value
= max(dst_reg
->umin_value
, umin_val
);
2928 dst_reg
->umax_value
= dst_reg
->var_off
.value
|
2929 dst_reg
->var_off
.mask
;
2930 if (dst_reg
->smin_value
< 0 || smin_val
< 0) {
2931 /* Lose signed bounds when ORing negative numbers,
2932 * ain't nobody got time for that.
2934 dst_reg
->smin_value
= S64_MIN
;
2935 dst_reg
->smax_value
= S64_MAX
;
2937 /* ORing two positives gives a positive, so safe to
2938 * cast result into s64.
2940 dst_reg
->smin_value
= dst_reg
->umin_value
;
2941 dst_reg
->smax_value
= dst_reg
->umax_value
;
2943 /* We may learn something more from the var_off */
2944 __update_reg_bounds(dst_reg
);
2947 if (umax_val
>= insn_bitness
) {
2948 /* Shifts greater than 31 or 63 are undefined.
2949 * This includes shifts by a negative number.
2951 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2954 /* We lose all sign bit information (except what we can pick
2957 dst_reg
->smin_value
= S64_MIN
;
2958 dst_reg
->smax_value
= S64_MAX
;
2959 /* If we might shift our top bit out, then we know nothing */
2960 if (dst_reg
->umax_value
> 1ULL << (63 - umax_val
)) {
2961 dst_reg
->umin_value
= 0;
2962 dst_reg
->umax_value
= U64_MAX
;
2964 dst_reg
->umin_value
<<= umin_val
;
2965 dst_reg
->umax_value
<<= umax_val
;
2968 dst_reg
->var_off
= tnum_lshift(dst_reg
->var_off
, umin_val
);
2970 dst_reg
->var_off
= tnum_lshift(tnum_unknown
, umin_val
);
2971 /* We may learn something more from the var_off */
2972 __update_reg_bounds(dst_reg
);
2975 if (umax_val
>= insn_bitness
) {
2976 /* Shifts greater than 31 or 63 are undefined.
2977 * This includes shifts by a negative number.
2979 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
2982 /* BPF_RSH is an unsigned shift. If the value in dst_reg might
2983 * be negative, then either:
2984 * 1) src_reg might be zero, so the sign bit of the result is
2985 * unknown, so we lose our signed bounds
2986 * 2) it's known negative, thus the unsigned bounds capture the
2988 * 3) the signed bounds cross zero, so they tell us nothing
2990 * If the value in dst_reg is known nonnegative, then again the
2991 * unsigned bounts capture the signed bounds.
2992 * Thus, in all cases it suffices to blow away our signed bounds
2993 * and rely on inferring new ones from the unsigned bounds and
2994 * var_off of the result.
2996 dst_reg
->smin_value
= S64_MIN
;
2997 dst_reg
->smax_value
= S64_MAX
;
2999 dst_reg
->var_off
= tnum_rshift(dst_reg
->var_off
,
3002 dst_reg
->var_off
= tnum_rshift(tnum_unknown
, umin_val
);
3003 dst_reg
->umin_value
>>= umax_val
;
3004 dst_reg
->umax_value
>>= umin_val
;
3005 /* We may learn something more from the var_off */
3006 __update_reg_bounds(dst_reg
);
3009 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
3013 if (BPF_CLASS(insn
->code
) != BPF_ALU64
) {
3014 /* 32-bit ALU ops are (32,32)->32 */
3015 coerce_reg_to_size(dst_reg
, 4);
3016 coerce_reg_to_size(&src_reg
, 4);
3019 __reg_deduce_bounds(dst_reg
);
3020 __reg_bound_offset(dst_reg
);
3024 /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
3027 static int adjust_reg_min_max_vals(struct bpf_verifier_env
*env
,
3028 struct bpf_insn
*insn
)
3030 struct bpf_verifier_state
*vstate
= env
->cur_state
;
3031 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
3032 struct bpf_reg_state
*regs
= state
->regs
, *dst_reg
, *src_reg
;
3033 struct bpf_reg_state
*ptr_reg
= NULL
, off_reg
= {0};
3034 u8 opcode
= BPF_OP(insn
->code
);
3036 dst_reg
= ®s
[insn
->dst_reg
];
3038 if (dst_reg
->type
!= SCALAR_VALUE
)
3040 if (BPF_SRC(insn
->code
) == BPF_X
) {
3041 src_reg
= ®s
[insn
->src_reg
];
3042 if (src_reg
->type
!= SCALAR_VALUE
) {
3043 if (dst_reg
->type
!= SCALAR_VALUE
) {
3044 /* Combining two pointers by any ALU op yields
3045 * an arbitrary scalar. Disallow all math except
3046 * pointer subtraction
3048 if (opcode
== BPF_SUB
){
3049 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
3052 verbose(env
, "R%d pointer %s pointer prohibited\n",
3054 bpf_alu_string
[opcode
>> 4]);
3057 /* scalar += pointer
3058 * This is legal, but we have to reverse our
3059 * src/dest handling in computing the range
3061 return adjust_ptr_min_max_vals(env
, insn
,
3064 } else if (ptr_reg
) {
3065 /* pointer += scalar */
3066 return adjust_ptr_min_max_vals(env
, insn
,
3070 /* Pretend the src is a reg with a known value, since we only
3071 * need to be able to read from this state.
3073 off_reg
.type
= SCALAR_VALUE
;
3074 __mark_reg_known(&off_reg
, insn
->imm
);
3076 if (ptr_reg
) /* pointer += K */
3077 return adjust_ptr_min_max_vals(env
, insn
,
3081 /* Got here implies adding two SCALAR_VALUEs */
3082 if (WARN_ON_ONCE(ptr_reg
)) {
3083 print_verifier_state(env
, state
);
3084 verbose(env
, "verifier internal error: unexpected ptr_reg\n");
3087 if (WARN_ON(!src_reg
)) {
3088 print_verifier_state(env
, state
);
3089 verbose(env
, "verifier internal error: no src_reg\n");
3092 return adjust_scalar_min_max_vals(env
, insn
, dst_reg
, *src_reg
);
3095 /* check validity of 32-bit and 64-bit arithmetic operations */
3096 static int check_alu_op(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
3098 struct bpf_reg_state
*regs
= cur_regs(env
);
3099 u8 opcode
= BPF_OP(insn
->code
);
3102 if (opcode
== BPF_END
|| opcode
== BPF_NEG
) {
3103 if (opcode
== BPF_NEG
) {
3104 if (BPF_SRC(insn
->code
) != 0 ||
3105 insn
->src_reg
!= BPF_REG_0
||
3106 insn
->off
!= 0 || insn
->imm
!= 0) {
3107 verbose(env
, "BPF_NEG uses reserved fields\n");
3111 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
3112 (insn
->imm
!= 16 && insn
->imm
!= 32 && insn
->imm
!= 64) ||
3113 BPF_CLASS(insn
->code
) == BPF_ALU64
) {
3114 verbose(env
, "BPF_END uses reserved fields\n");
3119 /* check src operand */
3120 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
3124 if (is_pointer_value(env
, insn
->dst_reg
)) {
3125 verbose(env
, "R%d pointer arithmetic prohibited\n",
3130 /* check dest operand */
3131 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
3135 } else if (opcode
== BPF_MOV
) {
3137 if (BPF_SRC(insn
->code
) == BPF_X
) {
3138 if (insn
->imm
!= 0 || insn
->off
!= 0) {
3139 verbose(env
, "BPF_MOV uses reserved fields\n");
3143 /* check src operand */
3144 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3148 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
3149 verbose(env
, "BPF_MOV uses reserved fields\n");
3154 /* check dest operand */
3155 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
3159 if (BPF_SRC(insn
->code
) == BPF_X
) {
3160 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
3162 * copy register state to dest reg
3164 regs
[insn
->dst_reg
] = regs
[insn
->src_reg
];
3165 regs
[insn
->dst_reg
].live
|= REG_LIVE_WRITTEN
;
3168 if (is_pointer_value(env
, insn
->src_reg
)) {
3170 "R%d partial copy of pointer\n",
3174 mark_reg_unknown(env
, regs
, insn
->dst_reg
);
3175 coerce_reg_to_size(®s
[insn
->dst_reg
], 4);
3179 * remember the value we stored into this reg
3181 regs
[insn
->dst_reg
].type
= SCALAR_VALUE
;
3182 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
3183 __mark_reg_known(regs
+ insn
->dst_reg
,
3186 __mark_reg_known(regs
+ insn
->dst_reg
,
3191 } else if (opcode
> BPF_END
) {
3192 verbose(env
, "invalid BPF_ALU opcode %x\n", opcode
);
3195 } else { /* all other ALU ops: and, sub, xor, add, ... */
3197 if (BPF_SRC(insn
->code
) == BPF_X
) {
3198 if (insn
->imm
!= 0 || insn
->off
!= 0) {
3199 verbose(env
, "BPF_ALU uses reserved fields\n");
3202 /* check src1 operand */
3203 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3207 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
3208 verbose(env
, "BPF_ALU uses reserved fields\n");
3213 /* check src2 operand */
3214 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
3218 if ((opcode
== BPF_MOD
|| opcode
== BPF_DIV
) &&
3219 BPF_SRC(insn
->code
) == BPF_K
&& insn
->imm
== 0) {
3220 verbose(env
, "div by zero\n");
3224 if (opcode
== BPF_ARSH
&& BPF_CLASS(insn
->code
) != BPF_ALU64
) {
3225 verbose(env
, "BPF_ARSH not supported for 32 bit ALU\n");
3229 if ((opcode
== BPF_LSH
|| opcode
== BPF_RSH
||
3230 opcode
== BPF_ARSH
) && BPF_SRC(insn
->code
) == BPF_K
) {
3231 int size
= BPF_CLASS(insn
->code
) == BPF_ALU64
? 64 : 32;
3233 if (insn
->imm
< 0 || insn
->imm
>= size
) {
3234 verbose(env
, "invalid shift %d\n", insn
->imm
);
3239 /* check dest operand */
3240 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP_NO_MARK
);
3244 return adjust_reg_min_max_vals(env
, insn
);
3250 static void find_good_pkt_pointers(struct bpf_verifier_state
*vstate
,
3251 struct bpf_reg_state
*dst_reg
,
3252 enum bpf_reg_type type
,
3253 bool range_right_open
)
3255 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
3256 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
3260 if (dst_reg
->off
< 0 ||
3261 (dst_reg
->off
== 0 && range_right_open
))
3262 /* This doesn't give us any range */
3265 if (dst_reg
->umax_value
> MAX_PACKET_OFF
||
3266 dst_reg
->umax_value
+ dst_reg
->off
> MAX_PACKET_OFF
)
3267 /* Risk of overflow. For instance, ptr + (1<<63) may be less
3268 * than pkt_end, but that's because it's also less than pkt.
3272 new_range
= dst_reg
->off
;
3273 if (range_right_open
)
3276 /* Examples for register markings:
3278 * pkt_data in dst register:
3282 * if (r2 > pkt_end) goto <handle exception>
3287 * if (r2 < pkt_end) goto <access okay>
3288 * <handle exception>
3291 * r2 == dst_reg, pkt_end == src_reg
3292 * r2=pkt(id=n,off=8,r=0)
3293 * r3=pkt(id=n,off=0,r=0)
3295 * pkt_data in src register:
3299 * if (pkt_end >= r2) goto <access okay>
3300 * <handle exception>
3304 * if (pkt_end <= r2) goto <handle exception>
3308 * pkt_end == dst_reg, r2 == src_reg
3309 * r2=pkt(id=n,off=8,r=0)
3310 * r3=pkt(id=n,off=0,r=0)
3312 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
3313 * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
3314 * and [r3, r3 + 8-1) respectively is safe to access depending on
3318 /* If our ids match, then we must have the same max_value. And we
3319 * don't care about the other reg's fixed offset, since if it's too big
3320 * the range won't allow anything.
3321 * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
3323 for (i
= 0; i
< MAX_BPF_REG
; i
++)
3324 if (regs
[i
].type
== type
&& regs
[i
].id
== dst_reg
->id
)
3325 /* keep the maximum range already checked */
3326 regs
[i
].range
= max(regs
[i
].range
, new_range
);
3328 for (j
= 0; j
<= vstate
->curframe
; j
++) {
3329 state
= vstate
->frame
[j
];
3330 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
3331 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
3333 reg
= &state
->stack
[i
].spilled_ptr
;
3334 if (reg
->type
== type
&& reg
->id
== dst_reg
->id
)
3335 reg
->range
= max(reg
->range
, new_range
);
3340 /* Adjusts the register min/max values in the case that the dst_reg is the
3341 * variable register that we are working on, and src_reg is a constant or we're
3342 * simply doing a BPF_K check.
3343 * In JEQ/JNE cases we also adjust the var_off values.
3345 static void reg_set_min_max(struct bpf_reg_state
*true_reg
,
3346 struct bpf_reg_state
*false_reg
, u64 val
,
3349 /* If the dst_reg is a pointer, we can't learn anything about its
3350 * variable offset from the compare (unless src_reg were a pointer into
3351 * the same object, but we don't bother with that.
3352 * Since false_reg and true_reg have the same type by construction, we
3353 * only need to check one of them for pointerness.
3355 if (__is_pointer_value(false, false_reg
))
3360 /* If this is false then we know nothing Jon Snow, but if it is
3361 * true then we know for sure.
3363 __mark_reg_known(true_reg
, val
);
3366 /* If this is true we know nothing Jon Snow, but if it is false
3367 * we know the value for sure;
3369 __mark_reg_known(false_reg
, val
);
3372 false_reg
->umax_value
= min(false_reg
->umax_value
, val
);
3373 true_reg
->umin_value
= max(true_reg
->umin_value
, val
+ 1);
3376 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
);
3377 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
+ 1);
3380 false_reg
->umin_value
= max(false_reg
->umin_value
, val
);
3381 true_reg
->umax_value
= min(true_reg
->umax_value
, val
- 1);
3384 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
);
3385 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
- 1);
3388 false_reg
->umax_value
= min(false_reg
->umax_value
, val
- 1);
3389 true_reg
->umin_value
= max(true_reg
->umin_value
, val
);
3392 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
- 1);
3393 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
);
3396 false_reg
->umin_value
= max(false_reg
->umin_value
, val
+ 1);
3397 true_reg
->umax_value
= min(true_reg
->umax_value
, val
);
3400 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
+ 1);
3401 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
);
3407 __reg_deduce_bounds(false_reg
);
3408 __reg_deduce_bounds(true_reg
);
3409 /* We might have learned some bits from the bounds. */
3410 __reg_bound_offset(false_reg
);
3411 __reg_bound_offset(true_reg
);
3412 /* Intersecting with the old var_off might have improved our bounds
3413 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
3414 * then new var_off is (0; 0x7f...fc) which improves our umax.
3416 __update_reg_bounds(false_reg
);
3417 __update_reg_bounds(true_reg
);
3420 /* Same as above, but for the case that dst_reg holds a constant and src_reg is
3423 static void reg_set_min_max_inv(struct bpf_reg_state
*true_reg
,
3424 struct bpf_reg_state
*false_reg
, u64 val
,
3427 if (__is_pointer_value(false, false_reg
))
3432 /* If this is false then we know nothing Jon Snow, but if it is
3433 * true then we know for sure.
3435 __mark_reg_known(true_reg
, val
);
3438 /* If this is true we know nothing Jon Snow, but if it is false
3439 * we know the value for sure;
3441 __mark_reg_known(false_reg
, val
);
3444 true_reg
->umax_value
= min(true_reg
->umax_value
, val
- 1);
3445 false_reg
->umin_value
= max(false_reg
->umin_value
, val
);
3448 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
- 1);
3449 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
);
3452 true_reg
->umin_value
= max(true_reg
->umin_value
, val
+ 1);
3453 false_reg
->umax_value
= min(false_reg
->umax_value
, val
);
3456 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
+ 1);
3457 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
);
3460 true_reg
->umax_value
= min(true_reg
->umax_value
, val
);
3461 false_reg
->umin_value
= max(false_reg
->umin_value
, val
+ 1);
3464 true_reg
->smax_value
= min_t(s64
, true_reg
->smax_value
, val
);
3465 false_reg
->smin_value
= max_t(s64
, false_reg
->smin_value
, val
+ 1);
3468 true_reg
->umin_value
= max(true_reg
->umin_value
, val
);
3469 false_reg
->umax_value
= min(false_reg
->umax_value
, val
- 1);
3472 true_reg
->smin_value
= max_t(s64
, true_reg
->smin_value
, val
);
3473 false_reg
->smax_value
= min_t(s64
, false_reg
->smax_value
, val
- 1);
3479 __reg_deduce_bounds(false_reg
);
3480 __reg_deduce_bounds(true_reg
);
3481 /* We might have learned some bits from the bounds. */
3482 __reg_bound_offset(false_reg
);
3483 __reg_bound_offset(true_reg
);
3484 /* Intersecting with the old var_off might have improved our bounds
3485 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
3486 * then new var_off is (0; 0x7f...fc) which improves our umax.
3488 __update_reg_bounds(false_reg
);
3489 __update_reg_bounds(true_reg
);
3492 /* Regs are known to be equal, so intersect their min/max/var_off */
3493 static void __reg_combine_min_max(struct bpf_reg_state
*src_reg
,
3494 struct bpf_reg_state
*dst_reg
)
3496 src_reg
->umin_value
= dst_reg
->umin_value
= max(src_reg
->umin_value
,
3497 dst_reg
->umin_value
);
3498 src_reg
->umax_value
= dst_reg
->umax_value
= min(src_reg
->umax_value
,
3499 dst_reg
->umax_value
);
3500 src_reg
->smin_value
= dst_reg
->smin_value
= max(src_reg
->smin_value
,
3501 dst_reg
->smin_value
);
3502 src_reg
->smax_value
= dst_reg
->smax_value
= min(src_reg
->smax_value
,
3503 dst_reg
->smax_value
);
3504 src_reg
->var_off
= dst_reg
->var_off
= tnum_intersect(src_reg
->var_off
,
3506 /* We might have learned new bounds from the var_off. */
3507 __update_reg_bounds(src_reg
);
3508 __update_reg_bounds(dst_reg
);
3509 /* We might have learned something about the sign bit. */
3510 __reg_deduce_bounds(src_reg
);
3511 __reg_deduce_bounds(dst_reg
);
3512 /* We might have learned some bits from the bounds. */
3513 __reg_bound_offset(src_reg
);
3514 __reg_bound_offset(dst_reg
);
3515 /* Intersecting with the old var_off might have improved our bounds
3516 * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
3517 * then new var_off is (0; 0x7f...fc) which improves our umax.
3519 __update_reg_bounds(src_reg
);
3520 __update_reg_bounds(dst_reg
);
3523 static void reg_combine_min_max(struct bpf_reg_state
*true_src
,
3524 struct bpf_reg_state
*true_dst
,
3525 struct bpf_reg_state
*false_src
,
3526 struct bpf_reg_state
*false_dst
,
3531 __reg_combine_min_max(true_src
, true_dst
);
3534 __reg_combine_min_max(false_src
, false_dst
);
3539 static void mark_map_reg(struct bpf_reg_state
*regs
, u32 regno
, u32 id
,
3542 struct bpf_reg_state
*reg
= ®s
[regno
];
3544 if (reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
&& reg
->id
== id
) {
3545 /* Old offset (both fixed and variable parts) should
3546 * have been known-zero, because we don't allow pointer
3547 * arithmetic on pointers that might be NULL.
3549 if (WARN_ON_ONCE(reg
->smin_value
|| reg
->smax_value
||
3550 !tnum_equals_const(reg
->var_off
, 0) ||
3552 __mark_reg_known_zero(reg
);
3556 reg
->type
= SCALAR_VALUE
;
3557 } else if (reg
->map_ptr
->inner_map_meta
) {
3558 reg
->type
= CONST_PTR_TO_MAP
;
3559 reg
->map_ptr
= reg
->map_ptr
->inner_map_meta
;
3561 reg
->type
= PTR_TO_MAP_VALUE
;
3563 /* We don't need id from this point onwards anymore, thus we
3564 * should better reset it, so that state pruning has chances
3571 /* The logic is similar to find_good_pkt_pointers(), both could eventually
3572 * be folded together at some point.
3574 static void mark_map_regs(struct bpf_verifier_state
*vstate
, u32 regno
,
3577 struct bpf_func_state
*state
= vstate
->frame
[vstate
->curframe
];
3578 struct bpf_reg_state
*regs
= state
->regs
;
3579 u32 id
= regs
[regno
].id
;
3582 for (i
= 0; i
< MAX_BPF_REG
; i
++)
3583 mark_map_reg(regs
, i
, id
, is_null
);
3585 for (j
= 0; j
<= vstate
->curframe
; j
++) {
3586 state
= vstate
->frame
[j
];
3587 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
3588 if (state
->stack
[i
].slot_type
[0] != STACK_SPILL
)
3590 mark_map_reg(&state
->stack
[i
].spilled_ptr
, 0, id
, is_null
);
3595 static bool try_match_pkt_pointers(const struct bpf_insn
*insn
,
3596 struct bpf_reg_state
*dst_reg
,
3597 struct bpf_reg_state
*src_reg
,
3598 struct bpf_verifier_state
*this_branch
,
3599 struct bpf_verifier_state
*other_branch
)
3601 if (BPF_SRC(insn
->code
) != BPF_X
)
3604 switch (BPF_OP(insn
->code
)) {
3606 if ((dst_reg
->type
== PTR_TO_PACKET
&&
3607 src_reg
->type
== PTR_TO_PACKET_END
) ||
3608 (dst_reg
->type
== PTR_TO_PACKET_META
&&
3609 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
3610 /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
3611 find_good_pkt_pointers(this_branch
, dst_reg
,
3612 dst_reg
->type
, false);
3613 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
3614 src_reg
->type
== PTR_TO_PACKET
) ||
3615 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
3616 src_reg
->type
== PTR_TO_PACKET_META
)) {
3617 /* pkt_end > pkt_data', pkt_data > pkt_meta' */
3618 find_good_pkt_pointers(other_branch
, src_reg
,
3619 src_reg
->type
, true);
3625 if ((dst_reg
->type
== PTR_TO_PACKET
&&
3626 src_reg
->type
== PTR_TO_PACKET_END
) ||
3627 (dst_reg
->type
== PTR_TO_PACKET_META
&&
3628 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
3629 /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
3630 find_good_pkt_pointers(other_branch
, dst_reg
,
3631 dst_reg
->type
, true);
3632 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
3633 src_reg
->type
== PTR_TO_PACKET
) ||
3634 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
3635 src_reg
->type
== PTR_TO_PACKET_META
)) {
3636 /* pkt_end < pkt_data', pkt_data > pkt_meta' */
3637 find_good_pkt_pointers(this_branch
, src_reg
,
3638 src_reg
->type
, false);
3644 if ((dst_reg
->type
== PTR_TO_PACKET
&&
3645 src_reg
->type
== PTR_TO_PACKET_END
) ||
3646 (dst_reg
->type
== PTR_TO_PACKET_META
&&
3647 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
3648 /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
3649 find_good_pkt_pointers(this_branch
, dst_reg
,
3650 dst_reg
->type
, true);
3651 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
3652 src_reg
->type
== PTR_TO_PACKET
) ||
3653 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
3654 src_reg
->type
== PTR_TO_PACKET_META
)) {
3655 /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
3656 find_good_pkt_pointers(other_branch
, src_reg
,
3657 src_reg
->type
, false);
3663 if ((dst_reg
->type
== PTR_TO_PACKET
&&
3664 src_reg
->type
== PTR_TO_PACKET_END
) ||
3665 (dst_reg
->type
== PTR_TO_PACKET_META
&&
3666 reg_is_init_pkt_pointer(src_reg
, PTR_TO_PACKET
))) {
3667 /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
3668 find_good_pkt_pointers(other_branch
, dst_reg
,
3669 dst_reg
->type
, false);
3670 } else if ((dst_reg
->type
== PTR_TO_PACKET_END
&&
3671 src_reg
->type
== PTR_TO_PACKET
) ||
3672 (reg_is_init_pkt_pointer(dst_reg
, PTR_TO_PACKET
) &&
3673 src_reg
->type
== PTR_TO_PACKET_META
)) {
3674 /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
3675 find_good_pkt_pointers(this_branch
, src_reg
,
3676 src_reg
->type
, true);
3688 static int check_cond_jmp_op(struct bpf_verifier_env
*env
,
3689 struct bpf_insn
*insn
, int *insn_idx
)
3691 struct bpf_verifier_state
*this_branch
= env
->cur_state
;
3692 struct bpf_verifier_state
*other_branch
;
3693 struct bpf_reg_state
*regs
= this_branch
->frame
[this_branch
->curframe
]->regs
;
3694 struct bpf_reg_state
*dst_reg
, *other_branch_regs
;
3695 u8 opcode
= BPF_OP(insn
->code
);
3698 if (opcode
> BPF_JSLE
) {
3699 verbose(env
, "invalid BPF_JMP opcode %x\n", opcode
);
3703 if (BPF_SRC(insn
->code
) == BPF_X
) {
3704 if (insn
->imm
!= 0) {
3705 verbose(env
, "BPF_JMP uses reserved fields\n");
3709 /* check src1 operand */
3710 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3714 if (is_pointer_value(env
, insn
->src_reg
)) {
3715 verbose(env
, "R%d pointer comparison prohibited\n",
3720 if (insn
->src_reg
!= BPF_REG_0
) {
3721 verbose(env
, "BPF_JMP uses reserved fields\n");
3726 /* check src2 operand */
3727 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
3731 dst_reg
= ®s
[insn
->dst_reg
];
3733 /* detect if R == 0 where R was initialized to zero earlier */
3734 if (BPF_SRC(insn
->code
) == BPF_K
&&
3735 (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
3736 dst_reg
->type
== SCALAR_VALUE
&&
3737 tnum_is_const(dst_reg
->var_off
)) {
3738 if ((opcode
== BPF_JEQ
&& dst_reg
->var_off
.value
== insn
->imm
) ||
3739 (opcode
== BPF_JNE
&& dst_reg
->var_off
.value
!= insn
->imm
)) {
3740 /* if (imm == imm) goto pc+off;
3741 * only follow the goto, ignore fall-through
3743 *insn_idx
+= insn
->off
;
3746 /* if (imm != imm) goto pc+off;
3747 * only follow fall-through branch, since
3748 * that's where the program will go
3754 other_branch
= push_stack(env
, *insn_idx
+ insn
->off
+ 1, *insn_idx
);
3757 other_branch_regs
= other_branch
->frame
[other_branch
->curframe
]->regs
;
3759 /* detect if we are comparing against a constant value so we can adjust
3760 * our min/max values for our dst register.
3761 * this is only legit if both are scalars (or pointers to the same
3762 * object, I suppose, but we don't support that right now), because
3763 * otherwise the different base pointers mean the offsets aren't
3766 if (BPF_SRC(insn
->code
) == BPF_X
) {
3767 if (dst_reg
->type
== SCALAR_VALUE
&&
3768 regs
[insn
->src_reg
].type
== SCALAR_VALUE
) {
3769 if (tnum_is_const(regs
[insn
->src_reg
].var_off
))
3770 reg_set_min_max(&other_branch_regs
[insn
->dst_reg
],
3771 dst_reg
, regs
[insn
->src_reg
].var_off
.value
,
3773 else if (tnum_is_const(dst_reg
->var_off
))
3774 reg_set_min_max_inv(&other_branch_regs
[insn
->src_reg
],
3775 ®s
[insn
->src_reg
],
3776 dst_reg
->var_off
.value
, opcode
);
3777 else if (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
)
3778 /* Comparing for equality, we can combine knowledge */
3779 reg_combine_min_max(&other_branch_regs
[insn
->src_reg
],
3780 &other_branch_regs
[insn
->dst_reg
],
3781 ®s
[insn
->src_reg
],
3782 ®s
[insn
->dst_reg
], opcode
);
3784 } else if (dst_reg
->type
== SCALAR_VALUE
) {
3785 reg_set_min_max(&other_branch_regs
[insn
->dst_reg
],
3786 dst_reg
, insn
->imm
, opcode
);
3789 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
3790 if (BPF_SRC(insn
->code
) == BPF_K
&&
3791 insn
->imm
== 0 && (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
3792 dst_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
3793 /* Mark all identical map registers in each branch as either
3794 * safe or unknown depending R == 0 or R != 0 conditional.
3796 mark_map_regs(this_branch
, insn
->dst_reg
, opcode
== BPF_JNE
);
3797 mark_map_regs(other_branch
, insn
->dst_reg
, opcode
== BPF_JEQ
);
3798 } else if (!try_match_pkt_pointers(insn
, dst_reg
, ®s
[insn
->src_reg
],
3799 this_branch
, other_branch
) &&
3800 is_pointer_value(env
, insn
->dst_reg
)) {
3801 verbose(env
, "R%d pointer comparison prohibited\n",
3806 print_verifier_state(env
, this_branch
->frame
[this_branch
->curframe
]);
3810 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
3811 static struct bpf_map
*ld_imm64_to_map_ptr(struct bpf_insn
*insn
)
3813 u64 imm64
= ((u64
) (u32
) insn
[0].imm
) | ((u64
) (u32
) insn
[1].imm
) << 32;
3815 return (struct bpf_map
*) (unsigned long) imm64
;
3818 /* verify BPF_LD_IMM64 instruction */
3819 static int check_ld_imm(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
3821 struct bpf_reg_state
*regs
= cur_regs(env
);
3824 if (BPF_SIZE(insn
->code
) != BPF_DW
) {
3825 verbose(env
, "invalid BPF_LD_IMM insn\n");
3828 if (insn
->off
!= 0) {
3829 verbose(env
, "BPF_LD_IMM64 uses reserved fields\n");
3833 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP
);
3837 if (insn
->src_reg
== 0) {
3838 u64 imm
= ((u64
)(insn
+ 1)->imm
<< 32) | (u32
)insn
->imm
;
3840 regs
[insn
->dst_reg
].type
= SCALAR_VALUE
;
3841 __mark_reg_known(®s
[insn
->dst_reg
], imm
);
3845 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
3846 BUG_ON(insn
->src_reg
!= BPF_PSEUDO_MAP_FD
);
3848 regs
[insn
->dst_reg
].type
= CONST_PTR_TO_MAP
;
3849 regs
[insn
->dst_reg
].map_ptr
= ld_imm64_to_map_ptr(insn
);
3853 static bool may_access_skb(enum bpf_prog_type type
)
3856 case BPF_PROG_TYPE_SOCKET_FILTER
:
3857 case BPF_PROG_TYPE_SCHED_CLS
:
3858 case BPF_PROG_TYPE_SCHED_ACT
:
3865 /* verify safety of LD_ABS|LD_IND instructions:
3866 * - they can only appear in the programs where ctx == skb
3867 * - since they are wrappers of function calls, they scratch R1-R5 registers,
3868 * preserve R6-R9, and store return value into R0
3871 * ctx == skb == R6 == CTX
3874 * SRC == any register
3875 * IMM == 32-bit immediate
3878 * R0 - 8/16/32-bit skb data converted to cpu endianness
3880 static int check_ld_abs(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
3882 struct bpf_reg_state
*regs
= cur_regs(env
);
3883 u8 mode
= BPF_MODE(insn
->code
);
3886 if (!may_access_skb(env
->prog
->type
)) {
3887 verbose(env
, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
3891 if (env
->subprog_cnt
) {
3892 /* when program has LD_ABS insn JITs and interpreter assume
3893 * that r1 == ctx == skb which is not the case for callees
3894 * that can have arbitrary arguments. It's problematic
3895 * for main prog as well since JITs would need to analyze
3896 * all functions in order to make proper register save/restore
3897 * decisions in the main prog. Hence disallow LD_ABS with calls
3899 verbose(env
, "BPF_LD_[ABS|IND] instructions cannot be mixed with bpf-to-bpf calls\n");
3903 if (insn
->dst_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
3904 BPF_SIZE(insn
->code
) == BPF_DW
||
3905 (mode
== BPF_ABS
&& insn
->src_reg
!= BPF_REG_0
)) {
3906 verbose(env
, "BPF_LD_[ABS|IND] uses reserved fields\n");
3910 /* check whether implicit source operand (register R6) is readable */
3911 err
= check_reg_arg(env
, BPF_REG_6
, SRC_OP
);
3915 if (regs
[BPF_REG_6
].type
!= PTR_TO_CTX
) {
3917 "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
3921 if (mode
== BPF_IND
) {
3922 /* check explicit source operand */
3923 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
3928 /* reset caller saved regs to unreadable */
3929 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
3930 mark_reg_not_init(env
, regs
, caller_saved
[i
]);
3931 check_reg_arg(env
, caller_saved
[i
], DST_OP_NO_MARK
);
3934 /* mark destination R0 register as readable, since it contains
3935 * the value fetched from the packet.
3936 * Already marked as written above.
3938 mark_reg_unknown(env
, regs
, BPF_REG_0
);
3942 static int check_return_code(struct bpf_verifier_env
*env
)
3944 struct bpf_reg_state
*reg
;
3945 struct tnum range
= tnum_range(0, 1);
3947 switch (env
->prog
->type
) {
3948 case BPF_PROG_TYPE_CGROUP_SKB
:
3949 case BPF_PROG_TYPE_CGROUP_SOCK
:
3950 case BPF_PROG_TYPE_CGROUP_SOCK_ADDR
:
3951 case BPF_PROG_TYPE_SOCK_OPS
:
3952 case BPF_PROG_TYPE_CGROUP_DEVICE
:
3958 reg
= cur_regs(env
) + BPF_REG_0
;
3959 if (reg
->type
!= SCALAR_VALUE
) {
3960 verbose(env
, "At program exit the register R0 is not a known value (%s)\n",
3961 reg_type_str
[reg
->type
]);
3965 if (!tnum_in(range
, reg
->var_off
)) {
3966 verbose(env
, "At program exit the register R0 ");
3967 if (!tnum_is_unknown(reg
->var_off
)) {
3970 tnum_strn(tn_buf
, sizeof(tn_buf
), reg
->var_off
);
3971 verbose(env
, "has value %s", tn_buf
);
3973 verbose(env
, "has unknown scalar value");
3975 verbose(env
, " should have been 0 or 1\n");
3981 /* non-recursive DFS pseudo code
3982 * 1 procedure DFS-iterative(G,v):
3983 * 2 label v as discovered
3984 * 3 let S be a stack
3986 * 5 while S is not empty
3988 * 7 if t is what we're looking for:
3990 * 9 for all edges e in G.adjacentEdges(t) do
3991 * 10 if edge e is already labelled
3992 * 11 continue with the next edge
3993 * 12 w <- G.adjacentVertex(t,e)
3994 * 13 if vertex w is not discovered and not explored
3995 * 14 label e as tree-edge
3996 * 15 label w as discovered
3999 * 18 else if vertex w is discovered
4000 * 19 label e as back-edge
4002 * 21 // vertex w is explored
4003 * 22 label e as forward- or cross-edge
4004 * 23 label t as explored
4009 * 0x11 - discovered and fall-through edge labelled
4010 * 0x12 - discovered and fall-through and branch edges labelled
4021 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
4023 static int *insn_stack
; /* stack of insns to process */
4024 static int cur_stack
; /* current stack index */
4025 static int *insn_state
;
4027 /* t, w, e - match pseudo-code above:
4028 * t - index of current instruction
4029 * w - next instruction
4032 static int push_insn(int t
, int w
, int e
, struct bpf_verifier_env
*env
)
4034 if (e
== FALLTHROUGH
&& insn_state
[t
] >= (DISCOVERED
| FALLTHROUGH
))
4037 if (e
== BRANCH
&& insn_state
[t
] >= (DISCOVERED
| BRANCH
))
4040 if (w
< 0 || w
>= env
->prog
->len
) {
4041 verbose(env
, "jump out of range from insn %d to %d\n", t
, w
);
4046 /* mark branch target for state pruning */
4047 env
->explored_states
[w
] = STATE_LIST_MARK
;
4049 if (insn_state
[w
] == 0) {
4051 insn_state
[t
] = DISCOVERED
| e
;
4052 insn_state
[w
] = DISCOVERED
;
4053 if (cur_stack
>= env
->prog
->len
)
4055 insn_stack
[cur_stack
++] = w
;
4057 } else if ((insn_state
[w
] & 0xF0) == DISCOVERED
) {
4058 verbose(env
, "back-edge from insn %d to %d\n", t
, w
);
4060 } else if (insn_state
[w
] == EXPLORED
) {
4061 /* forward- or cross-edge */
4062 insn_state
[t
] = DISCOVERED
| e
;
4064 verbose(env
, "insn state internal bug\n");
4070 /* non-recursive depth-first-search to detect loops in BPF program
4071 * loop == back-edge in directed graph
4073 static int check_cfg(struct bpf_verifier_env
*env
)
4075 struct bpf_insn
*insns
= env
->prog
->insnsi
;
4076 int insn_cnt
= env
->prog
->len
;
4080 ret
= check_subprogs(env
);
4084 insn_state
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
4088 insn_stack
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
4094 insn_state
[0] = DISCOVERED
; /* mark 1st insn as discovered */
4095 insn_stack
[0] = 0; /* 0 is the first instruction */
4101 t
= insn_stack
[cur_stack
- 1];
4103 if (BPF_CLASS(insns
[t
].code
) == BPF_JMP
) {
4104 u8 opcode
= BPF_OP(insns
[t
].code
);
4106 if (opcode
== BPF_EXIT
) {
4108 } else if (opcode
== BPF_CALL
) {
4109 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
4114 if (t
+ 1 < insn_cnt
)
4115 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
4116 if (insns
[t
].src_reg
== BPF_PSEUDO_CALL
) {
4117 env
->explored_states
[t
] = STATE_LIST_MARK
;
4118 ret
= push_insn(t
, t
+ insns
[t
].imm
+ 1, BRANCH
, env
);
4124 } else if (opcode
== BPF_JA
) {
4125 if (BPF_SRC(insns
[t
].code
) != BPF_K
) {
4129 /* unconditional jump with single edge */
4130 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1,
4136 /* tell verifier to check for equivalent states
4137 * after every call and jump
4139 if (t
+ 1 < insn_cnt
)
4140 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
4142 /* conditional jump with two edges */
4143 env
->explored_states
[t
] = STATE_LIST_MARK
;
4144 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
4150 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1, BRANCH
, env
);
4157 /* all other non-branch instructions with single
4160 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
4168 insn_state
[t
] = EXPLORED
;
4169 if (cur_stack
-- <= 0) {
4170 verbose(env
, "pop stack internal bug\n");
4177 for (i
= 0; i
< insn_cnt
; i
++) {
4178 if (insn_state
[i
] != EXPLORED
) {
4179 verbose(env
, "unreachable insn %d\n", i
);
4184 ret
= 0; /* cfg looks good */
4192 /* check %cur's range satisfies %old's */
4193 static bool range_within(struct bpf_reg_state
*old
,
4194 struct bpf_reg_state
*cur
)
4196 return old
->umin_value
<= cur
->umin_value
&&
4197 old
->umax_value
>= cur
->umax_value
&&
4198 old
->smin_value
<= cur
->smin_value
&&
4199 old
->smax_value
>= cur
->smax_value
;
4202 /* Maximum number of register states that can exist at once */
4203 #define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE)
4209 /* If in the old state two registers had the same id, then they need to have
4210 * the same id in the new state as well. But that id could be different from
4211 * the old state, so we need to track the mapping from old to new ids.
4212 * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
4213 * regs with old id 5 must also have new id 9 for the new state to be safe. But
4214 * regs with a different old id could still have new id 9, we don't care about
4216 * So we look through our idmap to see if this old id has been seen before. If
4217 * so, we require the new id to match; otherwise, we add the id pair to the map.
4219 static bool check_ids(u32 old_id
, u32 cur_id
, struct idpair
*idmap
)
4223 for (i
= 0; i
< ID_MAP_SIZE
; i
++) {
4224 if (!idmap
[i
].old
) {
4225 /* Reached an empty slot; haven't seen this id before */
4226 idmap
[i
].old
= old_id
;
4227 idmap
[i
].cur
= cur_id
;
4230 if (idmap
[i
].old
== old_id
)
4231 return idmap
[i
].cur
== cur_id
;
4233 /* We ran out of idmap slots, which should be impossible */
4238 /* Returns true if (rold safe implies rcur safe) */
4239 static bool regsafe(struct bpf_reg_state
*rold
, struct bpf_reg_state
*rcur
,
4240 struct idpair
*idmap
)
4244 if (!(rold
->live
& REG_LIVE_READ
))
4245 /* explored state didn't use this */
4248 equal
= memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, frameno
)) == 0;
4250 if (rold
->type
== PTR_TO_STACK
)
4251 /* two stack pointers are equal only if they're pointing to
4252 * the same stack frame, since fp-8 in foo != fp-8 in bar
4254 return equal
&& rold
->frameno
== rcur
->frameno
;
4259 if (rold
->type
== NOT_INIT
)
4260 /* explored state can't have used this */
4262 if (rcur
->type
== NOT_INIT
)
4264 switch (rold
->type
) {
4266 if (rcur
->type
== SCALAR_VALUE
) {
4267 /* new val must satisfy old val knowledge */
4268 return range_within(rold
, rcur
) &&
4269 tnum_in(rold
->var_off
, rcur
->var_off
);
4271 /* We're trying to use a pointer in place of a scalar.
4272 * Even if the scalar was unbounded, this could lead to
4273 * pointer leaks because scalars are allowed to leak
4274 * while pointers are not. We could make this safe in
4275 * special cases if root is calling us, but it's
4276 * probably not worth the hassle.
4280 case PTR_TO_MAP_VALUE
:
4281 /* If the new min/max/var_off satisfy the old ones and
4282 * everything else matches, we are OK.
4283 * We don't care about the 'id' value, because nothing
4284 * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL)
4286 return memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, id
)) == 0 &&
4287 range_within(rold
, rcur
) &&
4288 tnum_in(rold
->var_off
, rcur
->var_off
);
4289 case PTR_TO_MAP_VALUE_OR_NULL
:
4290 /* a PTR_TO_MAP_VALUE could be safe to use as a
4291 * PTR_TO_MAP_VALUE_OR_NULL into the same map.
4292 * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
4293 * checked, doing so could have affected others with the same
4294 * id, and we can't check for that because we lost the id when
4295 * we converted to a PTR_TO_MAP_VALUE.
4297 if (rcur
->type
!= PTR_TO_MAP_VALUE_OR_NULL
)
4299 if (memcmp(rold
, rcur
, offsetof(struct bpf_reg_state
, id
)))
4301 /* Check our ids match any regs they're supposed to */
4302 return check_ids(rold
->id
, rcur
->id
, idmap
);
4303 case PTR_TO_PACKET_META
:
4305 if (rcur
->type
!= rold
->type
)
4307 /* We must have at least as much range as the old ptr
4308 * did, so that any accesses which were safe before are
4309 * still safe. This is true even if old range < old off,
4310 * since someone could have accessed through (ptr - k), or
4311 * even done ptr -= k in a register, to get a safe access.
4313 if (rold
->range
> rcur
->range
)
4315 /* If the offsets don't match, we can't trust our alignment;
4316 * nor can we be sure that we won't fall out of range.
4318 if (rold
->off
!= rcur
->off
)
4320 /* id relations must be preserved */
4321 if (rold
->id
&& !check_ids(rold
->id
, rcur
->id
, idmap
))
4323 /* new val must satisfy old val knowledge */
4324 return range_within(rold
, rcur
) &&
4325 tnum_in(rold
->var_off
, rcur
->var_off
);
4327 case CONST_PTR_TO_MAP
:
4328 case PTR_TO_PACKET_END
:
4329 /* Only valid matches are exact, which memcmp() above
4330 * would have accepted
4333 /* Don't know what's going on, just say it's not safe */
4337 /* Shouldn't get here; if we do, say it's not safe */
4342 static bool stacksafe(struct bpf_func_state
*old
,
4343 struct bpf_func_state
*cur
,
4344 struct idpair
*idmap
)
4348 /* if explored stack has more populated slots than current stack
4349 * such stacks are not equivalent
4351 if (old
->allocated_stack
> cur
->allocated_stack
)
4354 /* walk slots of the explored stack and ignore any additional
4355 * slots in the current stack, since explored(safe) state
4358 for (i
= 0; i
< old
->allocated_stack
; i
++) {
4359 spi
= i
/ BPF_REG_SIZE
;
4361 if (!(old
->stack
[spi
].spilled_ptr
.live
& REG_LIVE_READ
))
4362 /* explored state didn't use this */
4365 if (old
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] == STACK_INVALID
)
4367 /* if old state was safe with misc data in the stack
4368 * it will be safe with zero-initialized stack.
4369 * The opposite is not true
4371 if (old
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] == STACK_MISC
&&
4372 cur
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] == STACK_ZERO
)
4374 if (old
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
] !=
4375 cur
->stack
[spi
].slot_type
[i
% BPF_REG_SIZE
])
4376 /* Ex: old explored (safe) state has STACK_SPILL in
4377 * this stack slot, but current has has STACK_MISC ->
4378 * this verifier states are not equivalent,
4379 * return false to continue verification of this path
4382 if (i
% BPF_REG_SIZE
)
4384 if (old
->stack
[spi
].slot_type
[0] != STACK_SPILL
)
4386 if (!regsafe(&old
->stack
[spi
].spilled_ptr
,
4387 &cur
->stack
[spi
].spilled_ptr
,
4389 /* when explored and current stack slot are both storing
4390 * spilled registers, check that stored pointers types
4391 * are the same as well.
4392 * Ex: explored safe path could have stored
4393 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
4394 * but current path has stored:
4395 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
4396 * such verifier states are not equivalent.
4397 * return false to continue verification of this path
4404 /* compare two verifier states
4406 * all states stored in state_list are known to be valid, since
4407 * verifier reached 'bpf_exit' instruction through them
4409 * this function is called when verifier exploring different branches of
4410 * execution popped from the state stack. If it sees an old state that has
4411 * more strict register state and more strict stack state then this execution
4412 * branch doesn't need to be explored further, since verifier already
4413 * concluded that more strict state leads to valid finish.
4415 * Therefore two states are equivalent if register state is more conservative
4416 * and explored stack state is more conservative than the current one.
4419 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
4420 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
4422 * In other words if current stack state (one being explored) has more
4423 * valid slots than old one that already passed validation, it means
4424 * the verifier can stop exploring and conclude that current state is valid too
4426 * Similarly with registers. If explored state has register type as invalid
4427 * whereas register type in current state is meaningful, it means that
4428 * the current state will reach 'bpf_exit' instruction safely
4430 static bool func_states_equal(struct bpf_func_state
*old
,
4431 struct bpf_func_state
*cur
)
4433 struct idpair
*idmap
;
4437 idmap
= kcalloc(ID_MAP_SIZE
, sizeof(struct idpair
), GFP_KERNEL
);
4438 /* If we failed to allocate the idmap, just say it's not safe */
4442 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
4443 if (!regsafe(&old
->regs
[i
], &cur
->regs
[i
], idmap
))
4447 if (!stacksafe(old
, cur
, idmap
))
4455 static bool states_equal(struct bpf_verifier_env
*env
,
4456 struct bpf_verifier_state
*old
,
4457 struct bpf_verifier_state
*cur
)
4461 if (old
->curframe
!= cur
->curframe
)
4464 /* for states to be equal callsites have to be the same
4465 * and all frame states need to be equivalent
4467 for (i
= 0; i
<= old
->curframe
; i
++) {
4468 if (old
->frame
[i
]->callsite
!= cur
->frame
[i
]->callsite
)
4470 if (!func_states_equal(old
->frame
[i
], cur
->frame
[i
]))
4476 /* A write screens off any subsequent reads; but write marks come from the
4477 * straight-line code between a state and its parent. When we arrive at an
4478 * equivalent state (jump target or such) we didn't arrive by the straight-line
4479 * code, so read marks in the state must propagate to the parent regardless
4480 * of the state's write marks. That's what 'parent == state->parent' comparison
4481 * in mark_reg_read() and mark_stack_slot_read() is for.
4483 static int propagate_liveness(struct bpf_verifier_env
*env
,
4484 const struct bpf_verifier_state
*vstate
,
4485 struct bpf_verifier_state
*vparent
)
4487 int i
, frame
, err
= 0;
4488 struct bpf_func_state
*state
, *parent
;
4490 if (vparent
->curframe
!= vstate
->curframe
) {
4491 WARN(1, "propagate_live: parent frame %d current frame %d\n",
4492 vparent
->curframe
, vstate
->curframe
);
4495 /* Propagate read liveness of registers... */
4496 BUILD_BUG_ON(BPF_REG_FP
+ 1 != MAX_BPF_REG
);
4497 /* We don't need to worry about FP liveness because it's read-only */
4498 for (i
= 0; i
< BPF_REG_FP
; i
++) {
4499 if (vparent
->frame
[vparent
->curframe
]->regs
[i
].live
& REG_LIVE_READ
)
4501 if (vstate
->frame
[vstate
->curframe
]->regs
[i
].live
& REG_LIVE_READ
) {
4502 err
= mark_reg_read(env
, vstate
, vparent
, i
);
4508 /* ... and stack slots */
4509 for (frame
= 0; frame
<= vstate
->curframe
; frame
++) {
4510 state
= vstate
->frame
[frame
];
4511 parent
= vparent
->frame
[frame
];
4512 for (i
= 0; i
< state
->allocated_stack
/ BPF_REG_SIZE
&&
4513 i
< parent
->allocated_stack
/ BPF_REG_SIZE
; i
++) {
4514 if (parent
->stack
[i
].spilled_ptr
.live
& REG_LIVE_READ
)
4516 if (state
->stack
[i
].spilled_ptr
.live
& REG_LIVE_READ
)
4517 mark_stack_slot_read(env
, vstate
, vparent
, i
, frame
);
4523 static int is_state_visited(struct bpf_verifier_env
*env
, int insn_idx
)
4525 struct bpf_verifier_state_list
*new_sl
;
4526 struct bpf_verifier_state_list
*sl
;
4527 struct bpf_verifier_state
*cur
= env
->cur_state
;
4530 sl
= env
->explored_states
[insn_idx
];
4532 /* this 'insn_idx' instruction wasn't marked, so we will not
4533 * be doing state search here
4537 while (sl
!= STATE_LIST_MARK
) {
4538 if (states_equal(env
, &sl
->state
, cur
)) {
4539 /* reached equivalent register/stack state,
4541 * Registers read by the continuation are read by us.
4542 * If we have any write marks in env->cur_state, they
4543 * will prevent corresponding reads in the continuation
4544 * from reaching our parent (an explored_state). Our
4545 * own state will get the read marks recorded, but
4546 * they'll be immediately forgotten as we're pruning
4547 * this state and will pop a new one.
4549 err
= propagate_liveness(env
, &sl
->state
, cur
);
4557 /* there were no equivalent states, remember current one.
4558 * technically the current state is not proven to be safe yet,
4559 * but it will either reach outer most bpf_exit (which means it's safe)
4560 * or it will be rejected. Since there are no loops, we won't be
4561 * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
4562 * again on the way to bpf_exit
4564 new_sl
= kzalloc(sizeof(struct bpf_verifier_state_list
), GFP_KERNEL
);
4568 /* add new state to the head of linked list */
4569 err
= copy_verifier_state(&new_sl
->state
, cur
);
4571 free_verifier_state(&new_sl
->state
, false);
4575 new_sl
->next
= env
->explored_states
[insn_idx
];
4576 env
->explored_states
[insn_idx
] = new_sl
;
4577 /* connect new state to parentage chain */
4578 cur
->parent
= &new_sl
->state
;
4579 /* clear write marks in current state: the writes we did are not writes
4580 * our child did, so they don't screen off its reads from us.
4581 * (There are no read marks in current state, because reads always mark
4582 * their parent and current state never has children yet. Only
4583 * explored_states can get read marks.)
4585 for (i
= 0; i
< BPF_REG_FP
; i
++)
4586 cur
->frame
[cur
->curframe
]->regs
[i
].live
= REG_LIVE_NONE
;
4588 /* all stack frames are accessible from callee, clear them all */
4589 for (j
= 0; j
<= cur
->curframe
; j
++) {
4590 struct bpf_func_state
*frame
= cur
->frame
[j
];
4592 for (i
= 0; i
< frame
->allocated_stack
/ BPF_REG_SIZE
; i
++)
4593 frame
->stack
[i
].spilled_ptr
.live
= REG_LIVE_NONE
;
4598 static int do_check(struct bpf_verifier_env
*env
)
4600 struct bpf_verifier_state
*state
;
4601 struct bpf_insn
*insns
= env
->prog
->insnsi
;
4602 struct bpf_reg_state
*regs
;
4603 int insn_cnt
= env
->prog
->len
, i
;
4604 int insn_idx
, prev_insn_idx
= 0;
4605 int insn_processed
= 0;
4606 bool do_print_state
= false;
4608 state
= kzalloc(sizeof(struct bpf_verifier_state
), GFP_KERNEL
);
4611 state
->curframe
= 0;
4612 state
->parent
= NULL
;
4613 state
->frame
[0] = kzalloc(sizeof(struct bpf_func_state
), GFP_KERNEL
);
4614 if (!state
->frame
[0]) {
4618 env
->cur_state
= state
;
4619 init_func_state(env
, state
->frame
[0],
4620 BPF_MAIN_FUNC
/* callsite */,
4622 0 /* subprogno, zero == main subprog */);
4625 struct bpf_insn
*insn
;
4629 if (insn_idx
>= insn_cnt
) {
4630 verbose(env
, "invalid insn idx %d insn_cnt %d\n",
4631 insn_idx
, insn_cnt
);
4635 insn
= &insns
[insn_idx
];
4636 class = BPF_CLASS(insn
->code
);
4638 if (++insn_processed
> BPF_COMPLEXITY_LIMIT_INSNS
) {
4640 "BPF program is too large. Processed %d insn\n",
4645 err
= is_state_visited(env
, insn_idx
);
4649 /* found equivalent state, can prune the search */
4650 if (env
->log
.level
) {
4652 verbose(env
, "\nfrom %d to %d: safe\n",
4653 prev_insn_idx
, insn_idx
);
4655 verbose(env
, "%d: safe\n", insn_idx
);
4657 goto process_bpf_exit
;
4663 if (env
->log
.level
> 1 || (env
->log
.level
&& do_print_state
)) {
4664 if (env
->log
.level
> 1)
4665 verbose(env
, "%d:", insn_idx
);
4667 verbose(env
, "\nfrom %d to %d:",
4668 prev_insn_idx
, insn_idx
);
4669 print_verifier_state(env
, state
->frame
[state
->curframe
]);
4670 do_print_state
= false;
4673 if (env
->log
.level
) {
4674 const struct bpf_insn_cbs cbs
= {
4675 .cb_print
= verbose
,
4676 .private_data
= env
,
4679 verbose(env
, "%d: ", insn_idx
);
4680 print_bpf_insn(&cbs
, insn
, env
->allow_ptr_leaks
);
4683 if (bpf_prog_is_dev_bound(env
->prog
->aux
)) {
4684 err
= bpf_prog_offload_verify_insn(env
, insn_idx
,
4690 regs
= cur_regs(env
);
4691 env
->insn_aux_data
[insn_idx
].seen
= true;
4692 if (class == BPF_ALU
|| class == BPF_ALU64
) {
4693 err
= check_alu_op(env
, insn
);
4697 } else if (class == BPF_LDX
) {
4698 enum bpf_reg_type
*prev_src_type
, src_reg_type
;
4700 /* check for reserved fields is already done */
4702 /* check src operand */
4703 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
4707 err
= check_reg_arg(env
, insn
->dst_reg
, DST_OP_NO_MARK
);
4711 src_reg_type
= regs
[insn
->src_reg
].type
;
4713 /* check that memory (src_reg + off) is readable,
4714 * the state of dst_reg will be updated by this func
4716 err
= check_mem_access(env
, insn_idx
, insn
->src_reg
, insn
->off
,
4717 BPF_SIZE(insn
->code
), BPF_READ
,
4718 insn
->dst_reg
, false);
4722 prev_src_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
4724 if (*prev_src_type
== NOT_INIT
) {
4726 * dst_reg = *(u32 *)(src_reg + off)
4727 * save type to validate intersecting paths
4729 *prev_src_type
= src_reg_type
;
4731 } else if (src_reg_type
!= *prev_src_type
&&
4732 (src_reg_type
== PTR_TO_CTX
||
4733 *prev_src_type
== PTR_TO_CTX
)) {
4734 /* ABuser program is trying to use the same insn
4735 * dst_reg = *(u32*) (src_reg + off)
4736 * with different pointer types:
4737 * src_reg == ctx in one branch and
4738 * src_reg == stack|map in some other branch.
4741 verbose(env
, "same insn cannot be used with different pointers\n");
4745 } else if (class == BPF_STX
) {
4746 enum bpf_reg_type
*prev_dst_type
, dst_reg_type
;
4748 if (BPF_MODE(insn
->code
) == BPF_XADD
) {
4749 err
= check_xadd(env
, insn_idx
, insn
);
4756 /* check src1 operand */
4757 err
= check_reg_arg(env
, insn
->src_reg
, SRC_OP
);
4760 /* check src2 operand */
4761 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
4765 dst_reg_type
= regs
[insn
->dst_reg
].type
;
4767 /* check that memory (dst_reg + off) is writeable */
4768 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
4769 BPF_SIZE(insn
->code
), BPF_WRITE
,
4770 insn
->src_reg
, false);
4774 prev_dst_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
4776 if (*prev_dst_type
== NOT_INIT
) {
4777 *prev_dst_type
= dst_reg_type
;
4778 } else if (dst_reg_type
!= *prev_dst_type
&&
4779 (dst_reg_type
== PTR_TO_CTX
||
4780 *prev_dst_type
== PTR_TO_CTX
)) {
4781 verbose(env
, "same insn cannot be used with different pointers\n");
4785 } else if (class == BPF_ST
) {
4786 if (BPF_MODE(insn
->code
) != BPF_MEM
||
4787 insn
->src_reg
!= BPF_REG_0
) {
4788 verbose(env
, "BPF_ST uses reserved fields\n");
4791 /* check src operand */
4792 err
= check_reg_arg(env
, insn
->dst_reg
, SRC_OP
);
4796 if (is_ctx_reg(env
, insn
->dst_reg
)) {
4797 verbose(env
, "BPF_ST stores into R%d context is not allowed\n",
4802 /* check that memory (dst_reg + off) is writeable */
4803 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
4804 BPF_SIZE(insn
->code
), BPF_WRITE
,
4809 } else if (class == BPF_JMP
) {
4810 u8 opcode
= BPF_OP(insn
->code
);
4812 if (opcode
== BPF_CALL
) {
4813 if (BPF_SRC(insn
->code
) != BPF_K
||
4815 (insn
->src_reg
!= BPF_REG_0
&&
4816 insn
->src_reg
!= BPF_PSEUDO_CALL
) ||
4817 insn
->dst_reg
!= BPF_REG_0
) {
4818 verbose(env
, "BPF_CALL uses reserved fields\n");
4822 if (insn
->src_reg
== BPF_PSEUDO_CALL
)
4823 err
= check_func_call(env
, insn
, &insn_idx
);
4825 err
= check_helper_call(env
, insn
->imm
, insn_idx
);
4829 } else if (opcode
== BPF_JA
) {
4830 if (BPF_SRC(insn
->code
) != BPF_K
||
4832 insn
->src_reg
!= BPF_REG_0
||
4833 insn
->dst_reg
!= BPF_REG_0
) {
4834 verbose(env
, "BPF_JA uses reserved fields\n");
4838 insn_idx
+= insn
->off
+ 1;
4841 } else if (opcode
== BPF_EXIT
) {
4842 if (BPF_SRC(insn
->code
) != BPF_K
||
4844 insn
->src_reg
!= BPF_REG_0
||
4845 insn
->dst_reg
!= BPF_REG_0
) {
4846 verbose(env
, "BPF_EXIT uses reserved fields\n");
4850 if (state
->curframe
) {
4851 /* exit from nested function */
4852 prev_insn_idx
= insn_idx
;
4853 err
= prepare_func_exit(env
, &insn_idx
);
4856 do_print_state
= true;
4860 /* eBPF calling convetion is such that R0 is used
4861 * to return the value from eBPF program.
4862 * Make sure that it's readable at this time
4863 * of bpf_exit, which means that program wrote
4864 * something into it earlier
4866 err
= check_reg_arg(env
, BPF_REG_0
, SRC_OP
);
4870 if (is_pointer_value(env
, BPF_REG_0
)) {
4871 verbose(env
, "R0 leaks addr as return value\n");
4875 err
= check_return_code(env
);
4879 err
= pop_stack(env
, &prev_insn_idx
, &insn_idx
);
4885 do_print_state
= true;
4889 err
= check_cond_jmp_op(env
, insn
, &insn_idx
);
4893 } else if (class == BPF_LD
) {
4894 u8 mode
= BPF_MODE(insn
->code
);
4896 if (mode
== BPF_ABS
|| mode
== BPF_IND
) {
4897 err
= check_ld_abs(env
, insn
);
4901 } else if (mode
== BPF_IMM
) {
4902 err
= check_ld_imm(env
, insn
);
4907 env
->insn_aux_data
[insn_idx
].seen
= true;
4909 verbose(env
, "invalid BPF_LD mode\n");
4913 verbose(env
, "unknown insn class %d\n", class);
4920 verbose(env
, "processed %d insns (limit %d), stack depth ",
4921 insn_processed
, BPF_COMPLEXITY_LIMIT_INSNS
);
4922 for (i
= 0; i
< env
->subprog_cnt
+ 1; i
++) {
4923 u32 depth
= env
->subprog_stack_depth
[i
];
4925 verbose(env
, "%d", depth
);
4926 if (i
+ 1 < env
->subprog_cnt
+ 1)
4930 env
->prog
->aux
->stack_depth
= env
->subprog_stack_depth
[0];
4934 static int check_map_prealloc(struct bpf_map
*map
)
4936 return (map
->map_type
!= BPF_MAP_TYPE_HASH
&&
4937 map
->map_type
!= BPF_MAP_TYPE_PERCPU_HASH
&&
4938 map
->map_type
!= BPF_MAP_TYPE_HASH_OF_MAPS
) ||
4939 !(map
->map_flags
& BPF_F_NO_PREALLOC
);
4942 static int check_map_prog_compatibility(struct bpf_verifier_env
*env
,
4943 struct bpf_map
*map
,
4944 struct bpf_prog
*prog
)
4947 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
4948 * preallocated hash maps, since doing memory allocation
4949 * in overflow_handler can crash depending on where nmi got
4952 if (prog
->type
== BPF_PROG_TYPE_PERF_EVENT
) {
4953 if (!check_map_prealloc(map
)) {
4954 verbose(env
, "perf_event programs can only use preallocated hash map\n");
4957 if (map
->inner_map_meta
&&
4958 !check_map_prealloc(map
->inner_map_meta
)) {
4959 verbose(env
, "perf_event programs can only use preallocated inner hash map\n");
4964 if ((bpf_prog_is_dev_bound(prog
->aux
) || bpf_map_is_dev_bound(map
)) &&
4965 !bpf_offload_dev_match(prog
, map
)) {
4966 verbose(env
, "offload device mismatch between prog and map\n");
4973 /* look for pseudo eBPF instructions that access map FDs and
4974 * replace them with actual map pointers
4976 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env
*env
)
4978 struct bpf_insn
*insn
= env
->prog
->insnsi
;
4979 int insn_cnt
= env
->prog
->len
;
4982 err
= bpf_prog_calc_tag(env
->prog
);
4986 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
4987 if (BPF_CLASS(insn
->code
) == BPF_LDX
&&
4988 (BPF_MODE(insn
->code
) != BPF_MEM
|| insn
->imm
!= 0)) {
4989 verbose(env
, "BPF_LDX uses reserved fields\n");
4993 if (BPF_CLASS(insn
->code
) == BPF_STX
&&
4994 ((BPF_MODE(insn
->code
) != BPF_MEM
&&
4995 BPF_MODE(insn
->code
) != BPF_XADD
) || insn
->imm
!= 0)) {
4996 verbose(env
, "BPF_STX uses reserved fields\n");
5000 if (insn
[0].code
== (BPF_LD
| BPF_IMM
| BPF_DW
)) {
5001 struct bpf_map
*map
;
5004 if (i
== insn_cnt
- 1 || insn
[1].code
!= 0 ||
5005 insn
[1].dst_reg
!= 0 || insn
[1].src_reg
!= 0 ||
5007 verbose(env
, "invalid bpf_ld_imm64 insn\n");
5011 if (insn
->src_reg
== 0)
5012 /* valid generic load 64-bit imm */
5015 if (insn
->src_reg
!= BPF_PSEUDO_MAP_FD
) {
5017 "unrecognized bpf_ld_imm64 insn\n");
5021 f
= fdget(insn
->imm
);
5022 map
= __bpf_map_get(f
);
5024 verbose(env
, "fd %d is not pointing to valid bpf_map\n",
5026 return PTR_ERR(map
);
5029 err
= check_map_prog_compatibility(env
, map
, env
->prog
);
5035 /* store map pointer inside BPF_LD_IMM64 instruction */
5036 insn
[0].imm
= (u32
) (unsigned long) map
;
5037 insn
[1].imm
= ((u64
) (unsigned long) map
) >> 32;
5039 /* check whether we recorded this map already */
5040 for (j
= 0; j
< env
->used_map_cnt
; j
++)
5041 if (env
->used_maps
[j
] == map
) {
5046 if (env
->used_map_cnt
>= MAX_USED_MAPS
) {
5051 /* hold the map. If the program is rejected by verifier,
5052 * the map will be released by release_maps() or it
5053 * will be used by the valid program until it's unloaded
5054 * and all maps are released in free_bpf_prog_info()
5056 map
= bpf_map_inc(map
, false);
5059 return PTR_ERR(map
);
5061 env
->used_maps
[env
->used_map_cnt
++] = map
;
5070 /* Basic sanity check before we invest more work here. */
5071 if (!bpf_opcode_in_insntable(insn
->code
)) {
5072 verbose(env
, "unknown opcode %02x\n", insn
->code
);
5077 /* now all pseudo BPF_LD_IMM64 instructions load valid
5078 * 'struct bpf_map *' into a register instead of user map_fd.
5079 * These pointers will be used later by verifier to validate map access.
5084 /* drop refcnt of maps used by the rejected program */
5085 static void release_maps(struct bpf_verifier_env
*env
)
5089 for (i
= 0; i
< env
->used_map_cnt
; i
++)
5090 bpf_map_put(env
->used_maps
[i
]);
5093 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
5094 static void convert_pseudo_ld_imm64(struct bpf_verifier_env
*env
)
5096 struct bpf_insn
*insn
= env
->prog
->insnsi
;
5097 int insn_cnt
= env
->prog
->len
;
5100 for (i
= 0; i
< insn_cnt
; i
++, insn
++)
5101 if (insn
->code
== (BPF_LD
| BPF_IMM
| BPF_DW
))
5105 /* single env->prog->insni[off] instruction was replaced with the range
5106 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
5107 * [0, off) and [off, end) to new locations, so the patched range stays zero
5109 static int adjust_insn_aux_data(struct bpf_verifier_env
*env
, u32 prog_len
,
5112 struct bpf_insn_aux_data
*new_data
, *old_data
= env
->insn_aux_data
;
5117 new_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) * prog_len
);
5120 memcpy(new_data
, old_data
, sizeof(struct bpf_insn_aux_data
) * off
);
5121 memcpy(new_data
+ off
+ cnt
- 1, old_data
+ off
,
5122 sizeof(struct bpf_insn_aux_data
) * (prog_len
- off
- cnt
+ 1));
5123 for (i
= off
; i
< off
+ cnt
- 1; i
++)
5124 new_data
[i
].seen
= true;
5125 env
->insn_aux_data
= new_data
;
5130 static void adjust_subprog_starts(struct bpf_verifier_env
*env
, u32 off
, u32 len
)
5136 for (i
= 0; i
< env
->subprog_cnt
; i
++) {
5137 if (env
->subprog_starts
[i
] < off
)
5139 env
->subprog_starts
[i
] += len
- 1;
5143 static struct bpf_prog
*bpf_patch_insn_data(struct bpf_verifier_env
*env
, u32 off
,
5144 const struct bpf_insn
*patch
, u32 len
)
5146 struct bpf_prog
*new_prog
;
5148 new_prog
= bpf_patch_insn_single(env
->prog
, off
, patch
, len
);
5151 if (adjust_insn_aux_data(env
, new_prog
->len
, off
, len
))
5153 adjust_subprog_starts(env
, off
, len
);
5157 /* The verifier does more data flow analysis than llvm and will not
5158 * explore branches that are dead at run time. Malicious programs can
5159 * have dead code too. Therefore replace all dead at-run-time code
5162 * Just nops are not optimal, e.g. if they would sit at the end of the
5163 * program and through another bug we would manage to jump there, then
5164 * we'd execute beyond program memory otherwise. Returning exception
5165 * code also wouldn't work since we can have subprogs where the dead
5166 * code could be located.
5168 static void sanitize_dead_code(struct bpf_verifier_env
*env
)
5170 struct bpf_insn_aux_data
*aux_data
= env
->insn_aux_data
;
5171 struct bpf_insn trap
= BPF_JMP_IMM(BPF_JA
, 0, 0, -1);
5172 struct bpf_insn
*insn
= env
->prog
->insnsi
;
5173 const int insn_cnt
= env
->prog
->len
;
5176 for (i
= 0; i
< insn_cnt
; i
++) {
5177 if (aux_data
[i
].seen
)
5179 memcpy(insn
+ i
, &trap
, sizeof(trap
));
5183 /* convert load instructions that access fields of 'struct __sk_buff'
5184 * into sequence of instructions that access fields of 'struct sk_buff'
5186 static int convert_ctx_accesses(struct bpf_verifier_env
*env
)
5188 const struct bpf_verifier_ops
*ops
= env
->ops
;
5189 int i
, cnt
, size
, ctx_field_size
, delta
= 0;
5190 const int insn_cnt
= env
->prog
->len
;
5191 struct bpf_insn insn_buf
[16], *insn
;
5192 struct bpf_prog
*new_prog
;
5193 enum bpf_access_type type
;
5194 bool is_narrower_load
;
5197 if (ops
->gen_prologue
) {
5198 cnt
= ops
->gen_prologue(insn_buf
, env
->seen_direct_write
,
5200 if (cnt
>= ARRAY_SIZE(insn_buf
)) {
5201 verbose(env
, "bpf verifier is misconfigured\n");
5204 new_prog
= bpf_patch_insn_data(env
, 0, insn_buf
, cnt
);
5208 env
->prog
= new_prog
;
5213 if (!ops
->convert_ctx_access
)
5216 insn
= env
->prog
->insnsi
+ delta
;
5218 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
5219 if (insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_B
) ||
5220 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_H
) ||
5221 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_W
) ||
5222 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_DW
))
5224 else if (insn
->code
== (BPF_STX
| BPF_MEM
| BPF_B
) ||
5225 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_H
) ||
5226 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_W
) ||
5227 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_DW
))
5232 if (type
== BPF_WRITE
&&
5233 env
->insn_aux_data
[i
+ delta
].sanitize_stack_off
) {
5234 struct bpf_insn patch
[] = {
5235 /* Sanitize suspicious stack slot with zero.
5236 * There are no memory dependencies for this store,
5237 * since it's only using frame pointer and immediate
5240 BPF_ST_MEM(BPF_DW
, BPF_REG_FP
,
5241 env
->insn_aux_data
[i
+ delta
].sanitize_stack_off
,
5243 /* the original STX instruction will immediately
5244 * overwrite the same stack slot with appropriate value
5249 cnt
= ARRAY_SIZE(patch
);
5250 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, patch
, cnt
);
5255 env
->prog
= new_prog
;
5256 insn
= new_prog
->insnsi
+ i
+ delta
;
5260 if (env
->insn_aux_data
[i
+ delta
].ptr_type
!= PTR_TO_CTX
)
5263 ctx_field_size
= env
->insn_aux_data
[i
+ delta
].ctx_field_size
;
5264 size
= BPF_LDST_BYTES(insn
);
5266 /* If the read access is a narrower load of the field,
5267 * convert to a 4/8-byte load, to minimum program type specific
5268 * convert_ctx_access changes. If conversion is successful,
5269 * we will apply proper mask to the result.
5271 is_narrower_load
= size
< ctx_field_size
;
5272 if (is_narrower_load
) {
5273 u32 off
= insn
->off
;
5276 if (type
== BPF_WRITE
) {
5277 verbose(env
, "bpf verifier narrow ctx access misconfigured\n");
5282 if (ctx_field_size
== 4)
5284 else if (ctx_field_size
== 8)
5287 insn
->off
= off
& ~(ctx_field_size
- 1);
5288 insn
->code
= BPF_LDX
| BPF_MEM
| size_code
;
5292 cnt
= ops
->convert_ctx_access(type
, insn
, insn_buf
, env
->prog
,
5294 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
) ||
5295 (ctx_field_size
&& !target_size
)) {
5296 verbose(env
, "bpf verifier is misconfigured\n");
5300 if (is_narrower_load
&& size
< target_size
) {
5301 if (ctx_field_size
<= 4)
5302 insn_buf
[cnt
++] = BPF_ALU32_IMM(BPF_AND
, insn
->dst_reg
,
5303 (1 << size
* 8) - 1);
5305 insn_buf
[cnt
++] = BPF_ALU64_IMM(BPF_AND
, insn
->dst_reg
,
5306 (1 << size
* 8) - 1);
5309 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
, cnt
);
5315 /* keep walking new program and skip insns we just inserted */
5316 env
->prog
= new_prog
;
5317 insn
= new_prog
->insnsi
+ i
+ delta
;
5323 static int jit_subprogs(struct bpf_verifier_env
*env
)
5325 struct bpf_prog
*prog
= env
->prog
, **func
, *tmp
;
5326 int i
, j
, subprog_start
, subprog_end
= 0, len
, subprog
;
5327 struct bpf_insn
*insn
;
5331 if (env
->subprog_cnt
== 0)
5334 for (i
= 0, insn
= prog
->insnsi
; i
< prog
->len
; i
++, insn
++) {
5335 if (insn
->code
!= (BPF_JMP
| BPF_CALL
) ||
5336 insn
->src_reg
!= BPF_PSEUDO_CALL
)
5338 subprog
= find_subprog(env
, i
+ insn
->imm
+ 1);
5340 WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
5344 /* temporarily remember subprog id inside insn instead of
5345 * aux_data, since next loop will split up all insns into funcs
5347 insn
->off
= subprog
+ 1;
5348 /* remember original imm in case JIT fails and fallback
5349 * to interpreter will be needed
5351 env
->insn_aux_data
[i
].call_imm
= insn
->imm
;
5352 /* point imm to __bpf_call_base+1 from JITs point of view */
5356 func
= kzalloc(sizeof(prog
) * (env
->subprog_cnt
+ 1), GFP_KERNEL
);
5360 for (i
= 0; i
<= env
->subprog_cnt
; i
++) {
5361 subprog_start
= subprog_end
;
5362 if (env
->subprog_cnt
== i
)
5363 subprog_end
= prog
->len
;
5365 subprog_end
= env
->subprog_starts
[i
];
5367 len
= subprog_end
- subprog_start
;
5368 func
[i
] = bpf_prog_alloc(bpf_prog_size(len
), GFP_USER
);
5371 memcpy(func
[i
]->insnsi
, &prog
->insnsi
[subprog_start
],
5372 len
* sizeof(struct bpf_insn
));
5373 func
[i
]->type
= prog
->type
;
5375 if (bpf_prog_calc_tag(func
[i
]))
5377 func
[i
]->is_func
= 1;
5378 /* Use bpf_prog_F_tag to indicate functions in stack traces.
5379 * Long term would need debug info to populate names
5381 func
[i
]->aux
->name
[0] = 'F';
5382 func
[i
]->aux
->stack_depth
= env
->subprog_stack_depth
[i
];
5383 func
[i
]->jit_requested
= 1;
5384 func
[i
] = bpf_int_jit_compile(func
[i
]);
5385 if (!func
[i
]->jited
) {
5391 /* at this point all bpf functions were successfully JITed
5392 * now populate all bpf_calls with correct addresses and
5393 * run last pass of JIT
5395 for (i
= 0; i
<= env
->subprog_cnt
; i
++) {
5396 insn
= func
[i
]->insnsi
;
5397 for (j
= 0; j
< func
[i
]->len
; j
++, insn
++) {
5398 if (insn
->code
!= (BPF_JMP
| BPF_CALL
) ||
5399 insn
->src_reg
!= BPF_PSEUDO_CALL
)
5401 subprog
= insn
->off
;
5403 insn
->imm
= (u64 (*)(u64
, u64
, u64
, u64
, u64
))
5404 func
[subprog
]->bpf_func
-
5408 for (i
= 0; i
<= env
->subprog_cnt
; i
++) {
5409 old_bpf_func
= func
[i
]->bpf_func
;
5410 tmp
= bpf_int_jit_compile(func
[i
]);
5411 if (tmp
!= func
[i
] || func
[i
]->bpf_func
!= old_bpf_func
) {
5412 verbose(env
, "JIT doesn't support bpf-to-bpf calls\n");
5419 /* finally lock prog and jit images for all functions and
5422 for (i
= 0; i
<= env
->subprog_cnt
; i
++) {
5423 bpf_prog_lock_ro(func
[i
]);
5424 bpf_prog_kallsyms_add(func
[i
]);
5427 /* Last step: make now unused interpreter insns from main
5428 * prog consistent for later dump requests, so they can
5429 * later look the same as if they were interpreted only.
5431 for (i
= 0, insn
= prog
->insnsi
; i
< prog
->len
; i
++, insn
++) {
5434 if (insn
->code
!= (BPF_JMP
| BPF_CALL
) ||
5435 insn
->src_reg
!= BPF_PSEUDO_CALL
)
5437 insn
->off
= env
->insn_aux_data
[i
].call_imm
;
5438 subprog
= find_subprog(env
, i
+ insn
->off
+ 1);
5439 addr
= (unsigned long)func
[subprog
+ 1]->bpf_func
;
5441 insn
->imm
= (u64 (*)(u64
, u64
, u64
, u64
, u64
))
5442 addr
- __bpf_call_base
;
5446 prog
->bpf_func
= func
[0]->bpf_func
;
5447 prog
->aux
->func
= func
;
5448 prog
->aux
->func_cnt
= env
->subprog_cnt
+ 1;
5451 for (i
= 0; i
<= env
->subprog_cnt
; i
++)
5453 bpf_jit_free(func
[i
]);
5455 /* cleanup main prog to be interpreted */
5456 prog
->jit_requested
= 0;
5457 for (i
= 0, insn
= prog
->insnsi
; i
< prog
->len
; i
++, insn
++) {
5458 if (insn
->code
!= (BPF_JMP
| BPF_CALL
) ||
5459 insn
->src_reg
!= BPF_PSEUDO_CALL
)
5462 insn
->imm
= env
->insn_aux_data
[i
].call_imm
;
5467 static int fixup_call_args(struct bpf_verifier_env
*env
)
5469 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
5470 struct bpf_prog
*prog
= env
->prog
;
5471 struct bpf_insn
*insn
= prog
->insnsi
;
5477 if (env
->prog
->jit_requested
) {
5478 err
= jit_subprogs(env
);
5482 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
5483 for (i
= 0; i
< prog
->len
; i
++, insn
++) {
5484 if (insn
->code
!= (BPF_JMP
| BPF_CALL
) ||
5485 insn
->src_reg
!= BPF_PSEUDO_CALL
)
5487 depth
= get_callee_stack_depth(env
, insn
, i
);
5490 bpf_patch_call_args(insn
, depth
);
5497 /* fixup insn->imm field of bpf_call instructions
5498 * and inline eligible helpers as explicit sequence of BPF instructions
5500 * this function is called after eBPF program passed verification
5502 static int fixup_bpf_calls(struct bpf_verifier_env
*env
)
5504 struct bpf_prog
*prog
= env
->prog
;
5505 struct bpf_insn
*insn
= prog
->insnsi
;
5506 const struct bpf_func_proto
*fn
;
5507 const int insn_cnt
= prog
->len
;
5508 struct bpf_insn_aux_data
*aux
;
5509 struct bpf_insn insn_buf
[16];
5510 struct bpf_prog
*new_prog
;
5511 struct bpf_map
*map_ptr
;
5512 int i
, cnt
, delta
= 0;
5514 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
5515 if (insn
->code
== (BPF_ALU64
| BPF_MOD
| BPF_X
) ||
5516 insn
->code
== (BPF_ALU64
| BPF_DIV
| BPF_X
) ||
5517 insn
->code
== (BPF_ALU
| BPF_MOD
| BPF_X
) ||
5518 insn
->code
== (BPF_ALU
| BPF_DIV
| BPF_X
)) {
5519 bool is64
= BPF_CLASS(insn
->code
) == BPF_ALU64
;
5520 struct bpf_insn mask_and_div
[] = {
5521 BPF_MOV32_REG(insn
->src_reg
, insn
->src_reg
),
5523 BPF_JMP_IMM(BPF_JNE
, insn
->src_reg
, 0, 2),
5524 BPF_ALU32_REG(BPF_XOR
, insn
->dst_reg
, insn
->dst_reg
),
5525 BPF_JMP_IMM(BPF_JA
, 0, 0, 1),
5528 struct bpf_insn mask_and_mod
[] = {
5529 BPF_MOV32_REG(insn
->src_reg
, insn
->src_reg
),
5530 /* Rx mod 0 -> Rx */
5531 BPF_JMP_IMM(BPF_JEQ
, insn
->src_reg
, 0, 1),
5534 struct bpf_insn
*patchlet
;
5536 if (insn
->code
== (BPF_ALU64
| BPF_DIV
| BPF_X
) ||
5537 insn
->code
== (BPF_ALU
| BPF_DIV
| BPF_X
)) {
5538 patchlet
= mask_and_div
+ (is64
? 1 : 0);
5539 cnt
= ARRAY_SIZE(mask_and_div
) - (is64
? 1 : 0);
5541 patchlet
= mask_and_mod
+ (is64
? 1 : 0);
5542 cnt
= ARRAY_SIZE(mask_and_mod
) - (is64
? 1 : 0);
5545 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, patchlet
, cnt
);
5550 env
->prog
= prog
= new_prog
;
5551 insn
= new_prog
->insnsi
+ i
+ delta
;
5555 if (insn
->code
!= (BPF_JMP
| BPF_CALL
))
5557 if (insn
->src_reg
== BPF_PSEUDO_CALL
)
5560 if (insn
->imm
== BPF_FUNC_get_route_realm
)
5561 prog
->dst_needed
= 1;
5562 if (insn
->imm
== BPF_FUNC_get_prandom_u32
)
5563 bpf_user_rnd_init_once();
5564 if (insn
->imm
== BPF_FUNC_override_return
)
5565 prog
->kprobe_override
= 1;
5566 if (insn
->imm
== BPF_FUNC_tail_call
) {
5567 /* If we tail call into other programs, we
5568 * cannot make any assumptions since they can
5569 * be replaced dynamically during runtime in
5570 * the program array.
5572 prog
->cb_access
= 1;
5573 env
->prog
->aux
->stack_depth
= MAX_BPF_STACK
;
5575 /* mark bpf_tail_call as different opcode to avoid
5576 * conditional branch in the interpeter for every normal
5577 * call and to prevent accidental JITing by JIT compiler
5578 * that doesn't support bpf_tail_call yet
5581 insn
->code
= BPF_JMP
| BPF_TAIL_CALL
;
5583 aux
= &env
->insn_aux_data
[i
+ delta
];
5584 if (!bpf_map_ptr_unpriv(aux
))
5587 /* instead of changing every JIT dealing with tail_call
5588 * emit two extra insns:
5589 * if (index >= max_entries) goto out;
5590 * index &= array->index_mask;
5591 * to avoid out-of-bounds cpu speculation
5593 if (bpf_map_ptr_poisoned(aux
)) {
5594 verbose(env
, "tail_call abusing map_ptr\n");
5598 map_ptr
= BPF_MAP_PTR(aux
->map_state
);
5599 insn_buf
[0] = BPF_JMP_IMM(BPF_JGE
, BPF_REG_3
,
5600 map_ptr
->max_entries
, 2);
5601 insn_buf
[1] = BPF_ALU32_IMM(BPF_AND
, BPF_REG_3
,
5602 container_of(map_ptr
,
5605 insn_buf
[2] = *insn
;
5607 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
, cnt
);
5612 env
->prog
= prog
= new_prog
;
5613 insn
= new_prog
->insnsi
+ i
+ delta
;
5617 /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
5618 * handlers are currently limited to 64 bit only.
5620 if (prog
->jit_requested
&& BITS_PER_LONG
== 64 &&
5621 insn
->imm
== BPF_FUNC_map_lookup_elem
) {
5622 aux
= &env
->insn_aux_data
[i
+ delta
];
5623 if (bpf_map_ptr_poisoned(aux
))
5624 goto patch_call_imm
;
5626 map_ptr
= BPF_MAP_PTR(aux
->map_state
);
5627 if (!map_ptr
->ops
->map_gen_lookup
)
5628 goto patch_call_imm
;
5630 cnt
= map_ptr
->ops
->map_gen_lookup(map_ptr
, insn_buf
);
5631 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
)) {
5632 verbose(env
, "bpf verifier is misconfigured\n");
5636 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
,
5643 /* keep walking new program and skip insns we just inserted */
5644 env
->prog
= prog
= new_prog
;
5645 insn
= new_prog
->insnsi
+ i
+ delta
;
5649 if (insn
->imm
== BPF_FUNC_redirect_map
) {
5650 /* Note, we cannot use prog directly as imm as subsequent
5651 * rewrites would still change the prog pointer. The only
5652 * stable address we can use is aux, which also works with
5653 * prog clones during blinding.
5655 u64 addr
= (unsigned long)prog
->aux
;
5656 struct bpf_insn r4_ld
[] = {
5657 BPF_LD_IMM64(BPF_REG_4
, addr
),
5660 cnt
= ARRAY_SIZE(r4_ld
);
5662 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, r4_ld
, cnt
);
5667 env
->prog
= prog
= new_prog
;
5668 insn
= new_prog
->insnsi
+ i
+ delta
;
5671 fn
= env
->ops
->get_func_proto(insn
->imm
, env
->prog
);
5672 /* all functions that have prototype and verifier allowed
5673 * programs to call them, must be real in-kernel functions
5677 "kernel subsystem misconfigured func %s#%d\n",
5678 func_id_name(insn
->imm
), insn
->imm
);
5681 insn
->imm
= fn
->func
- __bpf_call_base
;
5687 static void free_states(struct bpf_verifier_env
*env
)
5689 struct bpf_verifier_state_list
*sl
, *sln
;
5692 if (!env
->explored_states
)
5695 for (i
= 0; i
< env
->prog
->len
; i
++) {
5696 sl
= env
->explored_states
[i
];
5699 while (sl
!= STATE_LIST_MARK
) {
5701 free_verifier_state(&sl
->state
, false);
5707 kfree(env
->explored_states
);
5710 int bpf_check(struct bpf_prog
**prog
, union bpf_attr
*attr
)
5712 struct bpf_verifier_env
*env
;
5713 struct bpf_verifier_log
*log
;
5716 /* no program is valid */
5717 if (ARRAY_SIZE(bpf_verifier_ops
) == 0)
5720 /* 'struct bpf_verifier_env' can be global, but since it's not small,
5721 * allocate/free it every time bpf_check() is called
5723 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
5728 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
5731 if (!env
->insn_aux_data
)
5734 env
->ops
= bpf_verifier_ops
[env
->prog
->type
];
5736 /* grab the mutex to protect few globals used by verifier */
5737 mutex_lock(&bpf_verifier_lock
);
5739 if (attr
->log_level
|| attr
->log_buf
|| attr
->log_size
) {
5740 /* user requested verbose verifier output
5741 * and supplied buffer to store the verification trace
5743 log
->level
= attr
->log_level
;
5744 log
->ubuf
= (char __user
*) (unsigned long) attr
->log_buf
;
5745 log
->len_total
= attr
->log_size
;
5748 /* log attributes have to be sane */
5749 if (log
->len_total
< 128 || log
->len_total
> UINT_MAX
>> 8 ||
5750 !log
->level
|| !log
->ubuf
)
5754 env
->strict_alignment
= !!(attr
->prog_flags
& BPF_F_STRICT_ALIGNMENT
);
5755 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
))
5756 env
->strict_alignment
= true;
5758 if (bpf_prog_is_dev_bound(env
->prog
->aux
)) {
5759 ret
= bpf_prog_offload_verifier_prep(env
);
5764 ret
= replace_map_fd_with_map_ptr(env
);
5766 goto skip_full_check
;
5768 env
->explored_states
= kcalloc(env
->prog
->len
,
5769 sizeof(struct bpf_verifier_state_list
*),
5772 if (!env
->explored_states
)
5773 goto skip_full_check
;
5775 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
5777 ret
= check_cfg(env
);
5779 goto skip_full_check
;
5781 ret
= do_check(env
);
5782 if (env
->cur_state
) {
5783 free_verifier_state(env
->cur_state
, true);
5784 env
->cur_state
= NULL
;
5788 while (!pop_stack(env
, NULL
, NULL
));
5792 sanitize_dead_code(env
);
5795 ret
= check_max_stack_depth(env
);
5798 /* program is valid, convert *(u32*)(ctx + off) accesses */
5799 ret
= convert_ctx_accesses(env
);
5802 ret
= fixup_bpf_calls(env
);
5805 ret
= fixup_call_args(env
);
5807 if (log
->level
&& bpf_verifier_log_full(log
))
5809 if (log
->level
&& !log
->ubuf
) {
5811 goto err_release_maps
;
5814 if (ret
== 0 && env
->used_map_cnt
) {
5815 /* if program passed verifier, update used_maps in bpf_prog_info */
5816 env
->prog
->aux
->used_maps
= kmalloc_array(env
->used_map_cnt
,
5817 sizeof(env
->used_maps
[0]),
5820 if (!env
->prog
->aux
->used_maps
) {
5822 goto err_release_maps
;
5825 memcpy(env
->prog
->aux
->used_maps
, env
->used_maps
,
5826 sizeof(env
->used_maps
[0]) * env
->used_map_cnt
);
5827 env
->prog
->aux
->used_map_cnt
= env
->used_map_cnt
;
5829 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
5830 * bpf_ld_imm64 instructions
5832 convert_pseudo_ld_imm64(env
);
5836 if (!env
->prog
->aux
->used_maps
)
5837 /* if we didn't copy map pointers into bpf_prog_info, release
5838 * them now. Otherwise free_bpf_prog_info() will release them.
5843 mutex_unlock(&bpf_verifier_lock
);
5844 vfree(env
->insn_aux_data
);