1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 #include <linux/kernel.h>
14 #include <linux/types.h>
15 #include <linux/slab.h>
16 #include <linux/bpf.h>
17 #include <linux/bpf_verifier.h>
18 #include <linux/filter.h>
19 #include <net/netlink.h>
20 #include <linux/file.h>
21 #include <linux/vmalloc.h>
22 #include <linux/stringify.h>
24 /* bpf_check() is a static code analyzer that walks eBPF program
25 * instruction by instruction and updates register/stack state.
26 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
28 * The first pass is depth-first-search to check that the program is a DAG.
29 * It rejects the following programs:
30 * - larger than BPF_MAXINSNS insns
31 * - if loop is present (detected via back-edge)
32 * - unreachable insns exist (shouldn't be a forest. program = one function)
33 * - out of bounds or malformed jumps
34 * The second pass is all possible path descent from the 1st insn.
35 * Since it's analyzing all pathes through the program, the length of the
36 * analysis is limited to 64k insn, which may be hit even if total number of
37 * insn is less then 4K, but there are too many branches that change stack/regs.
38 * Number of 'branches to be analyzed' is limited to 1k
40 * On entry to each instruction, each register has a type, and the instruction
41 * changes the types of the registers depending on instruction semantics.
42 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
45 * All registers are 64-bit.
46 * R0 - return register
47 * R1-R5 argument passing registers
48 * R6-R9 callee saved registers
49 * R10 - frame pointer read-only
51 * At the start of BPF program the register R1 contains a pointer to bpf_context
52 * and has type PTR_TO_CTX.
54 * Verifier tracks arithmetic operations on pointers in case:
55 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
56 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
57 * 1st insn copies R10 (which has FRAME_PTR) type into R1
58 * and 2nd arithmetic instruction is pattern matched to recognize
59 * that it wants to construct a pointer to some element within stack.
60 * So after 2nd insn, the register R1 has type PTR_TO_STACK
61 * (and -20 constant is saved for further stack bounds checking).
62 * Meaning that this reg is a pointer to stack plus known immediate constant.
64 * Most of the time the registers have UNKNOWN_VALUE type, which
65 * means the register has some value, but it's not a valid pointer.
66 * (like pointer plus pointer becomes UNKNOWN_VALUE type)
68 * When verifier sees load or store instructions the type of base register
69 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
70 * types recognized by check_mem_access() function.
72 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
73 * and the range of [ptr, ptr + map's value_size) is accessible.
75 * registers used to pass values to function calls are checked against
76 * function argument constraints.
78 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
79 * It means that the register type passed to this function must be
80 * PTR_TO_STACK and it will be used inside the function as
81 * 'pointer to map element key'
83 * For example the argument constraints for bpf_map_lookup_elem():
84 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
85 * .arg1_type = ARG_CONST_MAP_PTR,
86 * .arg2_type = ARG_PTR_TO_MAP_KEY,
88 * ret_type says that this function returns 'pointer to map elem value or null'
89 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
90 * 2nd argument should be a pointer to stack, which will be used inside
91 * the helper function as a pointer to map element key.
93 * On the kernel side the helper function looks like:
94 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
96 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
97 * void *key = (void *) (unsigned long) r2;
100 * here kernel can access 'key' and 'map' pointers safely, knowing that
101 * [key, key + map->key_size) bytes are valid and were initialized on
102 * the stack of eBPF program.
105 * Corresponding eBPF program may look like:
106 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
107 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
108 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
109 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
110 * here verifier looks at prototype of map_lookup_elem() and sees:
111 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
112 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
114 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
115 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
116 * and were initialized prior to this call.
117 * If it's ok, then verifier allows this BPF_CALL insn and looks at
118 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
119 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
120 * returns ether pointer to map value or NULL.
122 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
123 * insn, the register holding that pointer in the true branch changes state to
124 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
125 * branch. See check_cond_jmp_op().
127 * After the call R0 is set to return type of the function and registers R1-R5
128 * are set to NOT_INIT to indicate that they are no longer readable.
131 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
132 struct bpf_verifier_stack_elem
{
133 /* verifer state is 'st'
134 * before processing instruction 'insn_idx'
135 * and after processing instruction 'prev_insn_idx'
137 struct bpf_verifier_state st
;
140 struct bpf_verifier_stack_elem
*next
;
143 #define BPF_COMPLEXITY_LIMIT_INSNS 98304
144 #define BPF_COMPLEXITY_LIMIT_STACK 1024
146 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
148 struct bpf_call_arg_meta
{
149 struct bpf_map
*map_ptr
;
156 /* verbose verifier prints what it's seeing
157 * bpf_check() is called under lock, so no race to access these global vars
159 static u32 log_level
, log_size
, log_len
;
160 static char *log_buf
;
162 static DEFINE_MUTEX(bpf_verifier_lock
);
164 /* log_level controls verbosity level of eBPF verifier.
165 * verbose() is used to dump the verification trace to the log, so the user
166 * can figure out what's wrong with the program
168 static __printf(1, 2) void verbose(const char *fmt
, ...)
172 if (log_level
== 0 || log_len
>= log_size
- 1)
176 log_len
+= vscnprintf(log_buf
+ log_len
, log_size
- log_len
, fmt
, args
);
180 /* string representation of 'enum bpf_reg_type' */
181 static const char * const reg_type_str
[] = {
183 [UNKNOWN_VALUE
] = "inv",
184 [PTR_TO_CTX
] = "ctx",
185 [CONST_PTR_TO_MAP
] = "map_ptr",
186 [PTR_TO_MAP_VALUE
] = "map_value",
187 [PTR_TO_MAP_VALUE_OR_NULL
] = "map_value_or_null",
188 [PTR_TO_MAP_VALUE_ADJ
] = "map_value_adj",
190 [PTR_TO_STACK
] = "fp",
192 [PTR_TO_PACKET
] = "pkt",
193 [PTR_TO_PACKET_END
] = "pkt_end",
196 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
197 static const char * const func_id_str
[] = {
198 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN
)
200 #undef __BPF_FUNC_STR_FN
202 static const char *func_id_name(int id
)
204 BUILD_BUG_ON(ARRAY_SIZE(func_id_str
) != __BPF_FUNC_MAX_ID
);
206 if (id
>= 0 && id
< __BPF_FUNC_MAX_ID
&& func_id_str
[id
])
207 return func_id_str
[id
];
212 static void print_verifier_state(struct bpf_verifier_state
*state
)
214 struct bpf_reg_state
*reg
;
218 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
219 reg
= &state
->regs
[i
];
223 verbose(" R%d=%s", i
, reg_type_str
[t
]);
224 if (t
== CONST_IMM
|| t
== PTR_TO_STACK
)
225 verbose("%lld", reg
->imm
);
226 else if (t
== PTR_TO_PACKET
)
227 verbose("(id=%d,off=%d,r=%d)",
228 reg
->id
, reg
->off
, reg
->range
);
229 else if (t
== UNKNOWN_VALUE
&& reg
->imm
)
230 verbose("%lld", reg
->imm
);
231 else if (t
== CONST_PTR_TO_MAP
|| t
== PTR_TO_MAP_VALUE
||
232 t
== PTR_TO_MAP_VALUE_OR_NULL
||
233 t
== PTR_TO_MAP_VALUE_ADJ
)
234 verbose("(ks=%d,vs=%d,id=%u)",
235 reg
->map_ptr
->key_size
,
236 reg
->map_ptr
->value_size
,
238 if (reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
239 verbose(",min_value=%lld",
240 (long long)reg
->min_value
);
241 if (reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
242 verbose(",max_value=%llu",
243 (unsigned long long)reg
->max_value
);
245 verbose(",min_align=%u", reg
->min_align
);
247 verbose(",aux_off=%u", reg
->aux_off
);
248 if (reg
->aux_off_align
)
249 verbose(",aux_off_align=%u", reg
->aux_off_align
);
251 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
252 if (state
->stack_slot_type
[i
] == STACK_SPILL
)
253 verbose(" fp%d=%s", -MAX_BPF_STACK
+ i
,
254 reg_type_str
[state
->spilled_regs
[i
/ BPF_REG_SIZE
].type
]);
259 static const char *const bpf_class_string
[] = {
267 [BPF_ALU64
] = "alu64",
270 static const char *const bpf_alu_string
[16] = {
271 [BPF_ADD
>> 4] = "+=",
272 [BPF_SUB
>> 4] = "-=",
273 [BPF_MUL
>> 4] = "*=",
274 [BPF_DIV
>> 4] = "/=",
275 [BPF_OR
>> 4] = "|=",
276 [BPF_AND
>> 4] = "&=",
277 [BPF_LSH
>> 4] = "<<=",
278 [BPF_RSH
>> 4] = ">>=",
279 [BPF_NEG
>> 4] = "neg",
280 [BPF_MOD
>> 4] = "%=",
281 [BPF_XOR
>> 4] = "^=",
282 [BPF_MOV
>> 4] = "=",
283 [BPF_ARSH
>> 4] = "s>>=",
284 [BPF_END
>> 4] = "endian",
287 static const char *const bpf_ldst_string
[] = {
288 [BPF_W
>> 3] = "u32",
289 [BPF_H
>> 3] = "u16",
291 [BPF_DW
>> 3] = "u64",
294 static const char *const bpf_jmp_string
[16] = {
295 [BPF_JA
>> 4] = "jmp",
296 [BPF_JEQ
>> 4] = "==",
297 [BPF_JGT
>> 4] = ">",
298 [BPF_JGE
>> 4] = ">=",
299 [BPF_JSET
>> 4] = "&",
300 [BPF_JNE
>> 4] = "!=",
301 [BPF_JSGT
>> 4] = "s>",
302 [BPF_JSGE
>> 4] = "s>=",
303 [BPF_CALL
>> 4] = "call",
304 [BPF_EXIT
>> 4] = "exit",
307 static void print_bpf_insn(const struct bpf_verifier_env
*env
,
308 const struct bpf_insn
*insn
)
310 u8
class = BPF_CLASS(insn
->code
);
312 if (class == BPF_ALU
|| class == BPF_ALU64
) {
313 if (BPF_SRC(insn
->code
) == BPF_X
)
314 verbose("(%02x) %sr%d %s %sr%d\n",
315 insn
->code
, class == BPF_ALU
? "(u32) " : "",
317 bpf_alu_string
[BPF_OP(insn
->code
) >> 4],
318 class == BPF_ALU
? "(u32) " : "",
321 verbose("(%02x) %sr%d %s %s%d\n",
322 insn
->code
, class == BPF_ALU
? "(u32) " : "",
324 bpf_alu_string
[BPF_OP(insn
->code
) >> 4],
325 class == BPF_ALU
? "(u32) " : "",
327 } else if (class == BPF_STX
) {
328 if (BPF_MODE(insn
->code
) == BPF_MEM
)
329 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
331 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
333 insn
->off
, insn
->src_reg
);
334 else if (BPF_MODE(insn
->code
) == BPF_XADD
)
335 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
337 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
338 insn
->dst_reg
, insn
->off
,
341 verbose("BUG_%02x\n", insn
->code
);
342 } else if (class == BPF_ST
) {
343 if (BPF_MODE(insn
->code
) != BPF_MEM
) {
344 verbose("BUG_st_%02x\n", insn
->code
);
347 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
349 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
351 insn
->off
, insn
->imm
);
352 } else if (class == BPF_LDX
) {
353 if (BPF_MODE(insn
->code
) != BPF_MEM
) {
354 verbose("BUG_ldx_%02x\n", insn
->code
);
357 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
358 insn
->code
, insn
->dst_reg
,
359 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
360 insn
->src_reg
, insn
->off
);
361 } else if (class == BPF_LD
) {
362 if (BPF_MODE(insn
->code
) == BPF_ABS
) {
363 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
365 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
367 } else if (BPF_MODE(insn
->code
) == BPF_IND
) {
368 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
370 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
371 insn
->src_reg
, insn
->imm
);
372 } else if (BPF_MODE(insn
->code
) == BPF_IMM
&&
373 BPF_SIZE(insn
->code
) == BPF_DW
) {
374 /* At this point, we already made sure that the second
375 * part of the ldimm64 insn is accessible.
377 u64 imm
= ((u64
)(insn
+ 1)->imm
<< 32) | (u32
)insn
->imm
;
378 bool map_ptr
= insn
->src_reg
== BPF_PSEUDO_MAP_FD
;
380 if (map_ptr
&& !env
->allow_ptr_leaks
)
383 verbose("(%02x) r%d = 0x%llx\n", insn
->code
,
384 insn
->dst_reg
, (unsigned long long)imm
);
386 verbose("BUG_ld_%02x\n", insn
->code
);
389 } else if (class == BPF_JMP
) {
390 u8 opcode
= BPF_OP(insn
->code
);
392 if (opcode
== BPF_CALL
) {
393 verbose("(%02x) call %s#%d\n", insn
->code
,
394 func_id_name(insn
->imm
), insn
->imm
);
395 } else if (insn
->code
== (BPF_JMP
| BPF_JA
)) {
396 verbose("(%02x) goto pc%+d\n",
397 insn
->code
, insn
->off
);
398 } else if (insn
->code
== (BPF_JMP
| BPF_EXIT
)) {
399 verbose("(%02x) exit\n", insn
->code
);
400 } else if (BPF_SRC(insn
->code
) == BPF_X
) {
401 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
402 insn
->code
, insn
->dst_reg
,
403 bpf_jmp_string
[BPF_OP(insn
->code
) >> 4],
404 insn
->src_reg
, insn
->off
);
406 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
407 insn
->code
, insn
->dst_reg
,
408 bpf_jmp_string
[BPF_OP(insn
->code
) >> 4],
409 insn
->imm
, insn
->off
);
412 verbose("(%02x) %s\n", insn
->code
, bpf_class_string
[class]);
416 static int pop_stack(struct bpf_verifier_env
*env
, int *prev_insn_idx
)
418 struct bpf_verifier_stack_elem
*elem
;
421 if (env
->head
== NULL
)
424 memcpy(&env
->cur_state
, &env
->head
->st
, sizeof(env
->cur_state
));
425 insn_idx
= env
->head
->insn_idx
;
427 *prev_insn_idx
= env
->head
->prev_insn_idx
;
428 elem
= env
->head
->next
;
435 static struct bpf_verifier_state
*push_stack(struct bpf_verifier_env
*env
,
436 int insn_idx
, int prev_insn_idx
)
438 struct bpf_verifier_stack_elem
*elem
;
440 elem
= kmalloc(sizeof(struct bpf_verifier_stack_elem
), GFP_KERNEL
);
444 memcpy(&elem
->st
, &env
->cur_state
, sizeof(env
->cur_state
));
445 elem
->insn_idx
= insn_idx
;
446 elem
->prev_insn_idx
= prev_insn_idx
;
447 elem
->next
= env
->head
;
450 if (env
->stack_size
> BPF_COMPLEXITY_LIMIT_STACK
) {
451 verbose("BPF program is too complex\n");
456 /* pop all elements and return */
457 while (pop_stack(env
, NULL
) >= 0);
461 #define CALLER_SAVED_REGS 6
462 static const int caller_saved
[CALLER_SAVED_REGS
] = {
463 BPF_REG_0
, BPF_REG_1
, BPF_REG_2
, BPF_REG_3
, BPF_REG_4
, BPF_REG_5
466 static void mark_reg_not_init(struct bpf_reg_state
*regs
, u32 regno
)
468 BUG_ON(regno
>= MAX_BPF_REG
);
470 memset(®s
[regno
], 0, sizeof(regs
[regno
]));
471 regs
[regno
].type
= NOT_INIT
;
472 regs
[regno
].min_value
= BPF_REGISTER_MIN_RANGE
;
473 regs
[regno
].max_value
= BPF_REGISTER_MAX_RANGE
;
476 static void init_reg_state(struct bpf_reg_state
*regs
)
480 for (i
= 0; i
< MAX_BPF_REG
; i
++)
481 mark_reg_not_init(regs
, i
);
484 regs
[BPF_REG_FP
].type
= FRAME_PTR
;
486 /* 1st arg to a function */
487 regs
[BPF_REG_1
].type
= PTR_TO_CTX
;
490 static void __mark_reg_unknown_value(struct bpf_reg_state
*regs
, u32 regno
)
492 regs
[regno
].type
= UNKNOWN_VALUE
;
497 static void mark_reg_unknown_value(struct bpf_reg_state
*regs
, u32 regno
)
499 BUG_ON(regno
>= MAX_BPF_REG
);
500 __mark_reg_unknown_value(regs
, regno
);
503 static void reset_reg_range_values(struct bpf_reg_state
*regs
, u32 regno
)
505 regs
[regno
].min_value
= BPF_REGISTER_MIN_RANGE
;
506 regs
[regno
].max_value
= BPF_REGISTER_MAX_RANGE
;
507 regs
[regno
].value_from_signed
= false;
508 regs
[regno
].min_align
= 0;
511 static void mark_reg_unknown_value_and_range(struct bpf_reg_state
*regs
,
514 mark_reg_unknown_value(regs
, regno
);
515 reset_reg_range_values(regs
, regno
);
519 SRC_OP
, /* register is used as source operand */
520 DST_OP
, /* register is used as destination operand */
521 DST_OP_NO_MARK
/* same as above, check only, don't mark */
524 static int check_reg_arg(struct bpf_reg_state
*regs
, u32 regno
,
527 if (regno
>= MAX_BPF_REG
) {
528 verbose("R%d is invalid\n", regno
);
533 /* check whether register used as source operand can be read */
534 if (regs
[regno
].type
== NOT_INIT
) {
535 verbose("R%d !read_ok\n", regno
);
539 /* check whether register used as dest operand can be written to */
540 if (regno
== BPF_REG_FP
) {
541 verbose("frame pointer is read only\n");
545 mark_reg_unknown_value(regs
, regno
);
550 static bool is_spillable_regtype(enum bpf_reg_type type
)
553 case PTR_TO_MAP_VALUE
:
554 case PTR_TO_MAP_VALUE_OR_NULL
:
555 case PTR_TO_MAP_VALUE_ADJ
:
559 case PTR_TO_PACKET_END
:
561 case CONST_PTR_TO_MAP
:
568 /* check_stack_read/write functions track spill/fill of registers,
569 * stack boundary and alignment are checked in check_mem_access()
571 static int check_stack_write(struct bpf_verifier_state
*state
, int off
,
572 int size
, int value_regno
)
575 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
576 * so it's aligned access and [off, off + size) are within stack limits
579 if (value_regno
>= 0 &&
580 is_spillable_regtype(state
->regs
[value_regno
].type
)) {
582 /* register containing pointer is being spilled into stack */
583 if (size
!= BPF_REG_SIZE
) {
584 verbose("invalid size of register spill\n");
588 /* save register state */
589 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
] =
590 state
->regs
[value_regno
];
592 for (i
= 0; i
< BPF_REG_SIZE
; i
++)
593 state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] = STACK_SPILL
;
595 /* regular write of data into stack */
596 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
] =
597 (struct bpf_reg_state
) {};
599 for (i
= 0; i
< size
; i
++)
600 state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] = STACK_MISC
;
605 static int check_stack_read(struct bpf_verifier_state
*state
, int off
, int size
,
611 slot_type
= &state
->stack_slot_type
[MAX_BPF_STACK
+ off
];
613 if (slot_type
[0] == STACK_SPILL
) {
614 if (size
!= BPF_REG_SIZE
) {
615 verbose("invalid size of register spill\n");
618 for (i
= 1; i
< BPF_REG_SIZE
; i
++) {
619 if (slot_type
[i
] != STACK_SPILL
) {
620 verbose("corrupted spill memory\n");
625 if (value_regno
>= 0)
626 /* restore register state from stack */
627 state
->regs
[value_regno
] =
628 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
];
631 for (i
= 0; i
< size
; i
++) {
632 if (slot_type
[i
] != STACK_MISC
) {
633 verbose("invalid read from stack off %d+%d size %d\n",
638 if (value_regno
>= 0)
639 /* have read misc data from the stack */
640 mark_reg_unknown_value_and_range(state
->regs
,
646 /* check read/write into map element returned by bpf_map_lookup_elem() */
647 static int check_map_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
650 struct bpf_map
*map
= env
->cur_state
.regs
[regno
].map_ptr
;
652 if (off
< 0 || size
<= 0 || off
+ size
> map
->value_size
) {
653 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
654 map
->value_size
, off
, size
);
660 /* check read/write into an adjusted map element */
661 static int check_map_access_adj(struct bpf_verifier_env
*env
, u32 regno
,
664 struct bpf_verifier_state
*state
= &env
->cur_state
;
665 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
668 /* We adjusted the register to this map value, so we
669 * need to change off and size to min_value and max_value
670 * respectively to make sure our theoretical access will be
674 print_verifier_state(state
);
675 env
->varlen_map_value_access
= true;
676 /* The minimum value is only important with signed
677 * comparisons where we can't assume the floor of a
678 * value is 0. If we are using signed variables for our
679 * index'es we need to make sure that whatever we use
680 * will have a set floor within our range.
682 if (reg
->min_value
< 0) {
683 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
687 err
= check_map_access(env
, regno
, reg
->min_value
+ off
, size
);
689 verbose("R%d min value is outside of the array range\n",
694 /* If we haven't set a max value then we need to bail
695 * since we can't be sure we won't do bad things.
697 if (reg
->max_value
== BPF_REGISTER_MAX_RANGE
) {
698 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
702 return check_map_access(env
, regno
, reg
->max_value
+ off
, size
);
705 #define MAX_PACKET_OFF 0xffff
707 static bool may_access_direct_pkt_data(struct bpf_verifier_env
*env
,
708 const struct bpf_call_arg_meta
*meta
,
709 enum bpf_access_type t
)
711 switch (env
->prog
->type
) {
712 case BPF_PROG_TYPE_LWT_IN
:
713 case BPF_PROG_TYPE_LWT_OUT
:
714 /* dst_input() and dst_output() can't write for now */
718 case BPF_PROG_TYPE_SCHED_CLS
:
719 case BPF_PROG_TYPE_SCHED_ACT
:
720 case BPF_PROG_TYPE_XDP
:
721 case BPF_PROG_TYPE_LWT_XMIT
:
723 return meta
->pkt_access
;
725 env
->seen_direct_write
= true;
732 static int check_packet_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
735 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
736 struct bpf_reg_state
*reg
= ®s
[regno
];
739 if (off
< 0 || size
<= 0 || off
+ size
> reg
->range
) {
740 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
741 off
, size
, regno
, reg
->id
, reg
->off
, reg
->range
);
747 /* check access to 'struct bpf_context' fields */
748 static int check_ctx_access(struct bpf_verifier_env
*env
, int insn_idx
, int off
, int size
,
749 enum bpf_access_type t
, enum bpf_reg_type
*reg_type
)
751 struct bpf_insn_access_aux info
= {
752 .reg_type
= *reg_type
,
755 /* for analyzer ctx accesses are already validated and converted */
756 if (env
->analyzer_ops
)
759 if (env
->prog
->aux
->ops
->is_valid_access
&&
760 env
->prog
->aux
->ops
->is_valid_access(off
, size
, t
, &info
)) {
761 /* A non zero info.ctx_field_size indicates that this field is a
762 * candidate for later verifier transformation to load the whole
763 * field and then apply a mask when accessed with a narrower
764 * access than actual ctx access size. A zero info.ctx_field_size
765 * will only allow for whole field access and rejects any other
766 * type of narrower access.
768 env
->insn_aux_data
[insn_idx
].ctx_field_size
= info
.ctx_field_size
;
769 *reg_type
= info
.reg_type
;
771 /* remember the offset of last byte accessed in ctx */
772 if (env
->prog
->aux
->max_ctx_offset
< off
+ size
)
773 env
->prog
->aux
->max_ctx_offset
= off
+ size
;
777 verbose("invalid bpf_context access off=%d size=%d\n", off
, size
);
781 static bool __is_pointer_value(bool allow_ptr_leaks
,
782 const struct bpf_reg_state
*reg
)
796 static bool is_pointer_value(struct bpf_verifier_env
*env
, int regno
)
798 return __is_pointer_value(env
->allow_ptr_leaks
, &env
->cur_state
.regs
[regno
]);
801 static int check_pkt_ptr_alignment(const struct bpf_reg_state
*reg
,
802 int off
, int size
, bool strict
)
807 /* Byte size accesses are always allowed. */
808 if (!strict
|| size
== 1)
813 if (reg
->aux_off_align
% size
) {
814 verbose("Packet access is only %u byte aligned, %d byte access not allowed\n",
815 reg
->aux_off_align
, size
);
818 reg_off
+= reg
->aux_off
;
821 /* For platforms that do not have a Kconfig enabling
822 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
823 * NET_IP_ALIGN is universally set to '2'. And on platforms
824 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
825 * to this code only in strict mode where we want to emulate
826 * the NET_IP_ALIGN==2 checking. Therefore use an
827 * unconditional IP align value of '2'.
830 if ((ip_align
+ reg_off
+ off
) % size
!= 0) {
831 verbose("misaligned packet access off %d+%d+%d size %d\n",
832 ip_align
, reg_off
, off
, size
);
839 static int check_val_ptr_alignment(const struct bpf_reg_state
*reg
,
840 int size
, bool strict
)
842 if (strict
&& size
!= 1) {
843 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n");
850 static int check_ptr_alignment(struct bpf_verifier_env
*env
,
851 const struct bpf_reg_state
*reg
,
854 bool strict
= env
->strict_alignment
;
858 return check_pkt_ptr_alignment(reg
, off
, size
, strict
);
859 case PTR_TO_MAP_VALUE_ADJ
:
860 return check_val_ptr_alignment(reg
, size
, strict
);
862 if (off
% size
!= 0) {
863 verbose("misaligned access off %d size %d\n",
872 /* check whether memory at (regno + off) is accessible for t = (read | write)
873 * if t==write, value_regno is a register which value is stored into memory
874 * if t==read, value_regno is a register which will receive the value from memory
875 * if t==write && value_regno==-1, some unknown value is stored into memory
876 * if t==read && value_regno==-1, don't care what we read from memory
878 static int check_mem_access(struct bpf_verifier_env
*env
, int insn_idx
, u32 regno
, int off
,
879 int bpf_size
, enum bpf_access_type t
,
882 struct bpf_verifier_state
*state
= &env
->cur_state
;
883 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
886 if (reg
->type
== PTR_TO_STACK
)
889 size
= bpf_size_to_bytes(bpf_size
);
893 err
= check_ptr_alignment(env
, reg
, off
, size
);
897 if (reg
->type
== PTR_TO_MAP_VALUE
||
898 reg
->type
== PTR_TO_MAP_VALUE_ADJ
) {
899 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
900 is_pointer_value(env
, value_regno
)) {
901 verbose("R%d leaks addr into map\n", value_regno
);
905 if (reg
->type
== PTR_TO_MAP_VALUE_ADJ
)
906 err
= check_map_access_adj(env
, regno
, off
, size
);
908 err
= check_map_access(env
, regno
, off
, size
);
909 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
910 mark_reg_unknown_value_and_range(state
->regs
,
913 } else if (reg
->type
== PTR_TO_CTX
) {
914 enum bpf_reg_type reg_type
= UNKNOWN_VALUE
;
916 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
917 is_pointer_value(env
, value_regno
)) {
918 verbose("R%d leaks addr into ctx\n", value_regno
);
921 err
= check_ctx_access(env
, insn_idx
, off
, size
, t
, ®_type
);
922 if (!err
&& t
== BPF_READ
&& value_regno
>= 0) {
923 mark_reg_unknown_value_and_range(state
->regs
,
925 /* note that reg.[id|off|range] == 0 */
926 state
->regs
[value_regno
].type
= reg_type
;
927 state
->regs
[value_regno
].aux_off
= 0;
928 state
->regs
[value_regno
].aux_off_align
= 0;
931 } else if (reg
->type
== FRAME_PTR
|| reg
->type
== PTR_TO_STACK
) {
932 if (off
>= 0 || off
< -MAX_BPF_STACK
) {
933 verbose("invalid stack off=%d size=%d\n", off
, size
);
937 if (env
->prog
->aux
->stack_depth
< -off
)
938 env
->prog
->aux
->stack_depth
= -off
;
940 if (t
== BPF_WRITE
) {
941 if (!env
->allow_ptr_leaks
&&
942 state
->stack_slot_type
[MAX_BPF_STACK
+ off
] == STACK_SPILL
&&
943 size
!= BPF_REG_SIZE
) {
944 verbose("attempt to corrupt spilled pointer on stack\n");
947 err
= check_stack_write(state
, off
, size
, value_regno
);
949 err
= check_stack_read(state
, off
, size
, value_regno
);
951 } else if (state
->regs
[regno
].type
== PTR_TO_PACKET
) {
952 if (t
== BPF_WRITE
&& !may_access_direct_pkt_data(env
, NULL
, t
)) {
953 verbose("cannot write into packet\n");
956 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
957 is_pointer_value(env
, value_regno
)) {
958 verbose("R%d leaks addr into packet\n", value_regno
);
961 err
= check_packet_access(env
, regno
, off
, size
);
962 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
963 mark_reg_unknown_value_and_range(state
->regs
,
966 verbose("R%d invalid mem access '%s'\n",
967 regno
, reg_type_str
[reg
->type
]);
971 if (!err
&& size
<= 2 && value_regno
>= 0 && env
->allow_ptr_leaks
&&
972 state
->regs
[value_regno
].type
== UNKNOWN_VALUE
) {
973 /* 1 or 2 byte load zero-extends, determine the number of
974 * zero upper bits. Not doing it fo 4 byte load, since
975 * such values cannot be added to ptr_to_packet anyway.
977 state
->regs
[value_regno
].imm
= 64 - size
* 8;
982 static int check_xadd(struct bpf_verifier_env
*env
, int insn_idx
, struct bpf_insn
*insn
)
984 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
987 if ((BPF_SIZE(insn
->code
) != BPF_W
&& BPF_SIZE(insn
->code
) != BPF_DW
) ||
989 verbose("BPF_XADD uses reserved fields\n");
993 /* check src1 operand */
994 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
998 /* check src2 operand */
999 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
1003 if (is_pointer_value(env
, insn
->src_reg
)) {
1004 verbose("R%d leaks addr into mem\n", insn
->src_reg
);
1008 /* check whether atomic_add can read the memory */
1009 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1010 BPF_SIZE(insn
->code
), BPF_READ
, -1);
1014 /* check whether atomic_add can write into the same memory */
1015 return check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
1016 BPF_SIZE(insn
->code
), BPF_WRITE
, -1);
1019 /* when register 'regno' is passed into function that will read 'access_size'
1020 * bytes from that pointer, make sure that it's within stack boundary
1021 * and all elements of stack are initialized
1023 static int check_stack_boundary(struct bpf_verifier_env
*env
, int regno
,
1024 int access_size
, bool zero_size_allowed
,
1025 struct bpf_call_arg_meta
*meta
)
1027 struct bpf_verifier_state
*state
= &env
->cur_state
;
1028 struct bpf_reg_state
*regs
= state
->regs
;
1031 if (regs
[regno
].type
!= PTR_TO_STACK
) {
1032 if (zero_size_allowed
&& access_size
== 0 &&
1033 regs
[regno
].type
== CONST_IMM
&&
1034 regs
[regno
].imm
== 0)
1037 verbose("R%d type=%s expected=%s\n", regno
,
1038 reg_type_str
[regs
[regno
].type
],
1039 reg_type_str
[PTR_TO_STACK
]);
1043 off
= regs
[regno
].imm
;
1044 if (off
>= 0 || off
< -MAX_BPF_STACK
|| off
+ access_size
> 0 ||
1046 verbose("invalid stack type R%d off=%d access_size=%d\n",
1047 regno
, off
, access_size
);
1051 if (env
->prog
->aux
->stack_depth
< -off
)
1052 env
->prog
->aux
->stack_depth
= -off
;
1054 if (meta
&& meta
->raw_mode
) {
1055 meta
->access_size
= access_size
;
1056 meta
->regno
= regno
;
1060 for (i
= 0; i
< access_size
; i
++) {
1061 if (state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] != STACK_MISC
) {
1062 verbose("invalid indirect read from stack off %d+%d size %d\n",
1063 off
, i
, access_size
);
1070 static int check_helper_mem_access(struct bpf_verifier_env
*env
, int regno
,
1071 int access_size
, bool zero_size_allowed
,
1072 struct bpf_call_arg_meta
*meta
)
1074 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1076 switch (regs
[regno
].type
) {
1078 return check_packet_access(env
, regno
, 0, access_size
);
1079 case PTR_TO_MAP_VALUE
:
1080 return check_map_access(env
, regno
, 0, access_size
);
1081 case PTR_TO_MAP_VALUE_ADJ
:
1082 return check_map_access_adj(env
, regno
, 0, access_size
);
1083 default: /* const_imm|ptr_to_stack or invalid ptr */
1084 return check_stack_boundary(env
, regno
, access_size
,
1085 zero_size_allowed
, meta
);
1089 static int check_func_arg(struct bpf_verifier_env
*env
, u32 regno
,
1090 enum bpf_arg_type arg_type
,
1091 struct bpf_call_arg_meta
*meta
)
1093 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *reg
= ®s
[regno
];
1094 enum bpf_reg_type expected_type
, type
= reg
->type
;
1097 if (arg_type
== ARG_DONTCARE
)
1100 if (type
== NOT_INIT
) {
1101 verbose("R%d !read_ok\n", regno
);
1105 if (arg_type
== ARG_ANYTHING
) {
1106 if (is_pointer_value(env
, regno
)) {
1107 verbose("R%d leaks addr into helper function\n", regno
);
1113 if (type
== PTR_TO_PACKET
&&
1114 !may_access_direct_pkt_data(env
, meta
, BPF_READ
)) {
1115 verbose("helper access to the packet is not allowed\n");
1119 if (arg_type
== ARG_PTR_TO_MAP_KEY
||
1120 arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1121 expected_type
= PTR_TO_STACK
;
1122 if (type
!= PTR_TO_PACKET
&& type
!= expected_type
)
1124 } else if (arg_type
== ARG_CONST_SIZE
||
1125 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1126 expected_type
= CONST_IMM
;
1127 /* One exception. Allow UNKNOWN_VALUE registers when the
1128 * boundaries are known and don't cause unsafe memory accesses
1130 if (type
!= UNKNOWN_VALUE
&& type
!= expected_type
)
1132 } else if (arg_type
== ARG_CONST_MAP_PTR
) {
1133 expected_type
= CONST_PTR_TO_MAP
;
1134 if (type
!= expected_type
)
1136 } else if (arg_type
== ARG_PTR_TO_CTX
) {
1137 expected_type
= PTR_TO_CTX
;
1138 if (type
!= expected_type
)
1140 } else if (arg_type
== ARG_PTR_TO_MEM
||
1141 arg_type
== ARG_PTR_TO_UNINIT_MEM
) {
1142 expected_type
= PTR_TO_STACK
;
1143 /* One exception here. In case function allows for NULL to be
1144 * passed in as argument, it's a CONST_IMM type. Final test
1145 * happens during stack boundary checking.
1147 if (type
== CONST_IMM
&& reg
->imm
== 0)
1148 /* final test in check_stack_boundary() */;
1149 else if (type
!= PTR_TO_PACKET
&& type
!= PTR_TO_MAP_VALUE
&&
1150 type
!= PTR_TO_MAP_VALUE_ADJ
&& type
!= expected_type
)
1152 meta
->raw_mode
= arg_type
== ARG_PTR_TO_UNINIT_MEM
;
1154 verbose("unsupported arg_type %d\n", arg_type
);
1158 if (arg_type
== ARG_CONST_MAP_PTR
) {
1159 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1160 meta
->map_ptr
= reg
->map_ptr
;
1161 } else if (arg_type
== ARG_PTR_TO_MAP_KEY
) {
1162 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1163 * check that [key, key + map->key_size) are within
1164 * stack limits and initialized
1166 if (!meta
->map_ptr
) {
1167 /* in function declaration map_ptr must come before
1168 * map_key, so that it's verified and known before
1169 * we have to check map_key here. Otherwise it means
1170 * that kernel subsystem misconfigured verifier
1172 verbose("invalid map_ptr to access map->key\n");
1175 if (type
== PTR_TO_PACKET
)
1176 err
= check_packet_access(env
, regno
, 0,
1177 meta
->map_ptr
->key_size
);
1179 err
= check_stack_boundary(env
, regno
,
1180 meta
->map_ptr
->key_size
,
1182 } else if (arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1183 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1184 * check [value, value + map->value_size) validity
1186 if (!meta
->map_ptr
) {
1187 /* kernel subsystem misconfigured verifier */
1188 verbose("invalid map_ptr to access map->value\n");
1191 if (type
== PTR_TO_PACKET
)
1192 err
= check_packet_access(env
, regno
, 0,
1193 meta
->map_ptr
->value_size
);
1195 err
= check_stack_boundary(env
, regno
,
1196 meta
->map_ptr
->value_size
,
1198 } else if (arg_type
== ARG_CONST_SIZE
||
1199 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1200 bool zero_size_allowed
= (arg_type
== ARG_CONST_SIZE_OR_ZERO
);
1202 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1203 * from stack pointer 'buf'. Check it
1204 * note: regno == len, regno - 1 == buf
1207 /* kernel subsystem misconfigured verifier */
1208 verbose("ARG_CONST_SIZE cannot be first argument\n");
1212 /* If the register is UNKNOWN_VALUE, the access check happens
1213 * using its boundaries. Otherwise, just use its imm
1215 if (type
== UNKNOWN_VALUE
) {
1216 /* For unprivileged variable accesses, disable raw
1217 * mode so that the program is required to
1218 * initialize all the memory that the helper could
1219 * just partially fill up.
1223 if (reg
->min_value
< 0) {
1224 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n",
1229 if (reg
->min_value
== 0) {
1230 err
= check_helper_mem_access(env
, regno
- 1, 0,
1237 if (reg
->max_value
== BPF_REGISTER_MAX_RANGE
) {
1238 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
1242 err
= check_helper_mem_access(env
, regno
- 1,
1244 zero_size_allowed
, meta
);
1248 /* register is CONST_IMM */
1249 err
= check_helper_mem_access(env
, regno
- 1, reg
->imm
,
1250 zero_size_allowed
, meta
);
1256 verbose("R%d type=%s expected=%s\n", regno
,
1257 reg_type_str
[type
], reg_type_str
[expected_type
]);
1261 static int check_map_func_compatibility(struct bpf_map
*map
, int func_id
)
1266 /* We need a two way check, first is from map perspective ... */
1267 switch (map
->map_type
) {
1268 case BPF_MAP_TYPE_PROG_ARRAY
:
1269 if (func_id
!= BPF_FUNC_tail_call
)
1272 case BPF_MAP_TYPE_PERF_EVENT_ARRAY
:
1273 if (func_id
!= BPF_FUNC_perf_event_read
&&
1274 func_id
!= BPF_FUNC_perf_event_output
)
1277 case BPF_MAP_TYPE_STACK_TRACE
:
1278 if (func_id
!= BPF_FUNC_get_stackid
)
1281 case BPF_MAP_TYPE_CGROUP_ARRAY
:
1282 if (func_id
!= BPF_FUNC_skb_under_cgroup
&&
1283 func_id
!= BPF_FUNC_current_task_under_cgroup
)
1286 case BPF_MAP_TYPE_ARRAY_OF_MAPS
:
1287 case BPF_MAP_TYPE_HASH_OF_MAPS
:
1288 if (func_id
!= BPF_FUNC_map_lookup_elem
)
1294 /* ... and second from the function itself. */
1296 case BPF_FUNC_tail_call
:
1297 if (map
->map_type
!= BPF_MAP_TYPE_PROG_ARRAY
)
1300 case BPF_FUNC_perf_event_read
:
1301 case BPF_FUNC_perf_event_output
:
1302 if (map
->map_type
!= BPF_MAP_TYPE_PERF_EVENT_ARRAY
)
1305 case BPF_FUNC_get_stackid
:
1306 if (map
->map_type
!= BPF_MAP_TYPE_STACK_TRACE
)
1309 case BPF_FUNC_current_task_under_cgroup
:
1310 case BPF_FUNC_skb_under_cgroup
:
1311 if (map
->map_type
!= BPF_MAP_TYPE_CGROUP_ARRAY
)
1320 verbose("cannot pass map_type %d into func %s#%d\n",
1321 map
->map_type
, func_id_name(func_id
), func_id
);
1325 static int check_raw_mode(const struct bpf_func_proto
*fn
)
1329 if (fn
->arg1_type
== ARG_PTR_TO_UNINIT_MEM
)
1331 if (fn
->arg2_type
== ARG_PTR_TO_UNINIT_MEM
)
1333 if (fn
->arg3_type
== ARG_PTR_TO_UNINIT_MEM
)
1335 if (fn
->arg4_type
== ARG_PTR_TO_UNINIT_MEM
)
1337 if (fn
->arg5_type
== ARG_PTR_TO_UNINIT_MEM
)
1340 return count
> 1 ? -EINVAL
: 0;
1343 static void clear_all_pkt_pointers(struct bpf_verifier_env
*env
)
1345 struct bpf_verifier_state
*state
= &env
->cur_state
;
1346 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
1349 for (i
= 0; i
< MAX_BPF_REG
; i
++)
1350 if (regs
[i
].type
== PTR_TO_PACKET
||
1351 regs
[i
].type
== PTR_TO_PACKET_END
)
1352 mark_reg_unknown_value(regs
, i
);
1354 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
1355 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
1357 reg
= &state
->spilled_regs
[i
/ BPF_REG_SIZE
];
1358 if (reg
->type
!= PTR_TO_PACKET
&&
1359 reg
->type
!= PTR_TO_PACKET_END
)
1361 __mark_reg_unknown_value(state
->spilled_regs
,
1366 static int check_call(struct bpf_verifier_env
*env
, int func_id
, int insn_idx
)
1368 struct bpf_verifier_state
*state
= &env
->cur_state
;
1369 const struct bpf_func_proto
*fn
= NULL
;
1370 struct bpf_reg_state
*regs
= state
->regs
;
1371 struct bpf_call_arg_meta meta
;
1375 /* find function prototype */
1376 if (func_id
< 0 || func_id
>= __BPF_FUNC_MAX_ID
) {
1377 verbose("invalid func %s#%d\n", func_id_name(func_id
), func_id
);
1381 if (env
->prog
->aux
->ops
->get_func_proto
)
1382 fn
= env
->prog
->aux
->ops
->get_func_proto(func_id
);
1385 verbose("unknown func %s#%d\n", func_id_name(func_id
), func_id
);
1389 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1390 if (!env
->prog
->gpl_compatible
&& fn
->gpl_only
) {
1391 verbose("cannot call GPL only function from proprietary program\n");
1395 changes_data
= bpf_helper_changes_pkt_data(fn
->func
);
1397 memset(&meta
, 0, sizeof(meta
));
1398 meta
.pkt_access
= fn
->pkt_access
;
1400 /* We only support one arg being in raw mode at the moment, which
1401 * is sufficient for the helper functions we have right now.
1403 err
= check_raw_mode(fn
);
1405 verbose("kernel subsystem misconfigured func %s#%d\n",
1406 func_id_name(func_id
), func_id
);
1411 err
= check_func_arg(env
, BPF_REG_1
, fn
->arg1_type
, &meta
);
1414 err
= check_func_arg(env
, BPF_REG_2
, fn
->arg2_type
, &meta
);
1417 err
= check_func_arg(env
, BPF_REG_3
, fn
->arg3_type
, &meta
);
1420 err
= check_func_arg(env
, BPF_REG_4
, fn
->arg4_type
, &meta
);
1423 err
= check_func_arg(env
, BPF_REG_5
, fn
->arg5_type
, &meta
);
1427 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1428 * is inferred from register state.
1430 for (i
= 0; i
< meta
.access_size
; i
++) {
1431 err
= check_mem_access(env
, insn_idx
, meta
.regno
, i
, BPF_B
, BPF_WRITE
, -1);
1436 /* reset caller saved regs */
1437 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++)
1438 mark_reg_not_init(regs
, caller_saved
[i
]);
1440 /* update return register */
1441 if (fn
->ret_type
== RET_INTEGER
) {
1442 regs
[BPF_REG_0
].type
= UNKNOWN_VALUE
;
1443 } else if (fn
->ret_type
== RET_VOID
) {
1444 regs
[BPF_REG_0
].type
= NOT_INIT
;
1445 } else if (fn
->ret_type
== RET_PTR_TO_MAP_VALUE_OR_NULL
) {
1446 struct bpf_insn_aux_data
*insn_aux
;
1448 regs
[BPF_REG_0
].type
= PTR_TO_MAP_VALUE_OR_NULL
;
1449 regs
[BPF_REG_0
].max_value
= regs
[BPF_REG_0
].min_value
= 0;
1450 /* remember map_ptr, so that check_map_access()
1451 * can check 'value_size' boundary of memory access
1452 * to map element returned from bpf_map_lookup_elem()
1454 if (meta
.map_ptr
== NULL
) {
1455 verbose("kernel subsystem misconfigured verifier\n");
1458 regs
[BPF_REG_0
].map_ptr
= meta
.map_ptr
;
1459 regs
[BPF_REG_0
].id
= ++env
->id_gen
;
1460 insn_aux
= &env
->insn_aux_data
[insn_idx
];
1461 if (!insn_aux
->map_ptr
)
1462 insn_aux
->map_ptr
= meta
.map_ptr
;
1463 else if (insn_aux
->map_ptr
!= meta
.map_ptr
)
1464 insn_aux
->map_ptr
= BPF_MAP_PTR_POISON
;
1466 verbose("unknown return type %d of func %s#%d\n",
1467 fn
->ret_type
, func_id_name(func_id
), func_id
);
1471 err
= check_map_func_compatibility(meta
.map_ptr
, func_id
);
1476 clear_all_pkt_pointers(env
);
1480 static int check_packet_ptr_add(struct bpf_verifier_env
*env
,
1481 struct bpf_insn
*insn
)
1483 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1484 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1485 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1486 struct bpf_reg_state tmp_reg
;
1489 if (BPF_SRC(insn
->code
) == BPF_K
) {
1490 /* pkt_ptr += imm */
1495 verbose("addition of negative constant to packet pointer is not allowed\n");
1498 if (imm
>= MAX_PACKET_OFF
||
1499 imm
+ dst_reg
->off
>= MAX_PACKET_OFF
) {
1500 verbose("constant %d is too large to add to packet pointer\n",
1504 /* a constant was added to pkt_ptr.
1505 * Remember it while keeping the same 'id'
1507 dst_reg
->off
+= imm
;
1511 if (src_reg
->type
== PTR_TO_PACKET
) {
1512 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1513 tmp_reg
= *dst_reg
; /* save r7 state */
1514 *dst_reg
= *src_reg
; /* copy pkt_ptr state r6 into r7 */
1515 src_reg
= &tmp_reg
; /* pretend it's src_reg state */
1516 /* if the checks below reject it, the copy won't matter,
1517 * since we're rejecting the whole program. If all ok,
1518 * then imm22 state will be added to r7
1519 * and r7 will be pkt(id=0,off=22,r=62) while
1520 * r6 will stay as pkt(id=0,off=0,r=62)
1524 if (src_reg
->type
== CONST_IMM
) {
1525 /* pkt_ptr += reg where reg is known constant */
1529 /* disallow pkt_ptr += reg
1530 * if reg is not uknown_value with guaranteed zero upper bits
1531 * otherwise pkt_ptr may overflow and addition will become
1532 * subtraction which is not allowed
1534 if (src_reg
->type
!= UNKNOWN_VALUE
) {
1535 verbose("cannot add '%s' to ptr_to_packet\n",
1536 reg_type_str
[src_reg
->type
]);
1539 if (src_reg
->imm
< 48) {
1540 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1545 had_id
= (dst_reg
->id
!= 0);
1547 /* dst_reg stays as pkt_ptr type and since some positive
1548 * integer value was added to the pointer, increment its 'id'
1550 dst_reg
->id
= ++env
->id_gen
;
1552 /* something was added to pkt_ptr, set range to zero */
1553 dst_reg
->aux_off
+= dst_reg
->off
;
1557 dst_reg
->aux_off_align
= min(dst_reg
->aux_off_align
,
1558 src_reg
->min_align
);
1560 dst_reg
->aux_off_align
= src_reg
->min_align
;
1565 static int evaluate_reg_alu(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
1567 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1568 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1569 u8 opcode
= BPF_OP(insn
->code
);
1572 /* for type == UNKNOWN_VALUE:
1573 * imm > 0 -> number of zero upper bits
1574 * imm == 0 -> don't track which is the same as all bits can be non-zero
1577 if (BPF_SRC(insn
->code
) == BPF_X
) {
1578 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1580 if (src_reg
->type
== UNKNOWN_VALUE
&& src_reg
->imm
> 0 &&
1581 dst_reg
->imm
&& opcode
== BPF_ADD
) {
1583 * where both have zero upper bits. Adding them
1584 * can only result making one more bit non-zero
1585 * in the larger value.
1586 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1587 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1589 dst_reg
->imm
= min(dst_reg
->imm
, src_reg
->imm
);
1593 if (src_reg
->type
== CONST_IMM
&& src_reg
->imm
> 0 &&
1594 dst_reg
->imm
&& opcode
== BPF_ADD
) {
1596 * where dreg has zero upper bits and sreg is const.
1597 * Adding them can only result making one more bit
1598 * non-zero in the larger value.
1600 imm_log2
= __ilog2_u64((long long)src_reg
->imm
);
1601 dst_reg
->imm
= min(dst_reg
->imm
, 63 - imm_log2
);
1605 /* all other cases non supported yet, just mark dst_reg */
1610 /* sign extend 32-bit imm into 64-bit to make sure that
1611 * negative values occupy bit 63. Note ilog2() would have
1612 * been incorrect, since sizeof(insn->imm) == 4
1614 imm_log2
= __ilog2_u64((long long)insn
->imm
);
1616 if (dst_reg
->imm
&& opcode
== BPF_LSH
) {
1618 * if reg was a result of 2 byte load, then its imm == 48
1619 * which means that upper 48 bits are zero and shifting this reg
1620 * left by 4 would mean that upper 44 bits are still zero
1622 dst_reg
->imm
-= insn
->imm
;
1623 } else if (dst_reg
->imm
&& opcode
== BPF_MUL
) {
1625 * if multiplying by 14 subtract 4
1626 * This is conservative calculation of upper zero bits.
1627 * It's not trying to special case insn->imm == 1 or 0 cases
1629 dst_reg
->imm
-= imm_log2
+ 1;
1630 } else if (opcode
== BPF_AND
) {
1632 dst_reg
->imm
= 63 - imm_log2
;
1633 } else if (dst_reg
->imm
&& opcode
== BPF_ADD
) {
1635 dst_reg
->imm
= min(dst_reg
->imm
, 63 - imm_log2
);
1637 } else if (opcode
== BPF_RSH
) {
1639 * which means that after right shift, upper bits will be zero
1640 * note that verifier already checked that
1641 * 0 <= imm < 64 for shift insn
1643 dst_reg
->imm
+= insn
->imm
;
1644 if (unlikely(dst_reg
->imm
> 64))
1645 /* some dumb code did:
1648 * and all bits are zero now */
1651 /* all other alu ops, means that we don't know what will
1652 * happen to the value, mark it with unknown number of zero bits
1657 if (dst_reg
->imm
< 0) {
1658 /* all 64 bits of the register can contain non-zero bits
1659 * and such value cannot be added to ptr_to_packet, since it
1660 * may overflow, mark it as unknown to avoid further eval
1667 static int evaluate_reg_imm_alu_unknown(struct bpf_verifier_env
*env
,
1668 struct bpf_insn
*insn
)
1670 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1671 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1672 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1673 u8 opcode
= BPF_OP(insn
->code
);
1674 s64 imm_log2
= __ilog2_u64((long long)dst_reg
->imm
);
1676 /* BPF_X code with src_reg->type UNKNOWN_VALUE here. */
1677 if (src_reg
->imm
> 0 && dst_reg
->imm
) {
1681 * where both have zero upper bits. Adding them
1682 * can only result making one more bit non-zero
1683 * in the larger value.
1684 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1685 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1687 dst_reg
->imm
= min(src_reg
->imm
, 63 - imm_log2
);
1692 * AND can not extend zero bits only shrink
1693 * Ex. 0x00..00ffffff
1698 dst_reg
->imm
= max(src_reg
->imm
, 63 - imm_log2
);
1702 * OR can only extend zero bits
1703 * Ex. 0x00..00ffffff
1708 dst_reg
->imm
= min(src_reg
->imm
, 63 - imm_log2
);
1714 /* These may be flushed out later */
1716 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1719 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1722 dst_reg
->type
= UNKNOWN_VALUE
;
1726 static int evaluate_reg_imm_alu(struct bpf_verifier_env
*env
,
1727 struct bpf_insn
*insn
)
1729 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1730 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1731 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1732 u8 opcode
= BPF_OP(insn
->code
);
1733 u64 dst_imm
= dst_reg
->imm
;
1735 if (BPF_SRC(insn
->code
) == BPF_X
&& src_reg
->type
== UNKNOWN_VALUE
)
1736 return evaluate_reg_imm_alu_unknown(env
, insn
);
1738 /* dst_reg->type == CONST_IMM here. Simulate execution of insns
1739 * containing ALU ops. Don't care about overflow or negative
1740 * values, just add/sub/... them; registers are in u64.
1742 if (opcode
== BPF_ADD
&& BPF_SRC(insn
->code
) == BPF_K
) {
1743 dst_imm
+= insn
->imm
;
1744 } else if (opcode
== BPF_ADD
&& BPF_SRC(insn
->code
) == BPF_X
&&
1745 src_reg
->type
== CONST_IMM
) {
1746 dst_imm
+= src_reg
->imm
;
1747 } else if (opcode
== BPF_SUB
&& BPF_SRC(insn
->code
) == BPF_K
) {
1748 dst_imm
-= insn
->imm
;
1749 } else if (opcode
== BPF_SUB
&& BPF_SRC(insn
->code
) == BPF_X
&&
1750 src_reg
->type
== CONST_IMM
) {
1751 dst_imm
-= src_reg
->imm
;
1752 } else if (opcode
== BPF_MUL
&& BPF_SRC(insn
->code
) == BPF_K
) {
1753 dst_imm
*= insn
->imm
;
1754 } else if (opcode
== BPF_MUL
&& BPF_SRC(insn
->code
) == BPF_X
&&
1755 src_reg
->type
== CONST_IMM
) {
1756 dst_imm
*= src_reg
->imm
;
1757 } else if (opcode
== BPF_OR
&& BPF_SRC(insn
->code
) == BPF_K
) {
1758 dst_imm
|= insn
->imm
;
1759 } else if (opcode
== BPF_OR
&& BPF_SRC(insn
->code
) == BPF_X
&&
1760 src_reg
->type
== CONST_IMM
) {
1761 dst_imm
|= src_reg
->imm
;
1762 } else if (opcode
== BPF_AND
&& BPF_SRC(insn
->code
) == BPF_K
) {
1763 dst_imm
&= insn
->imm
;
1764 } else if (opcode
== BPF_AND
&& BPF_SRC(insn
->code
) == BPF_X
&&
1765 src_reg
->type
== CONST_IMM
) {
1766 dst_imm
&= src_reg
->imm
;
1767 } else if (opcode
== BPF_RSH
&& BPF_SRC(insn
->code
) == BPF_K
) {
1768 dst_imm
>>= insn
->imm
;
1769 } else if (opcode
== BPF_RSH
&& BPF_SRC(insn
->code
) == BPF_X
&&
1770 src_reg
->type
== CONST_IMM
) {
1771 dst_imm
>>= src_reg
->imm
;
1772 } else if (opcode
== BPF_LSH
&& BPF_SRC(insn
->code
) == BPF_K
) {
1773 dst_imm
<<= insn
->imm
;
1774 } else if (opcode
== BPF_LSH
&& BPF_SRC(insn
->code
) == BPF_X
&&
1775 src_reg
->type
== CONST_IMM
) {
1776 dst_imm
<<= src_reg
->imm
;
1778 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1782 dst_reg
->imm
= dst_imm
;
1787 static void check_reg_overflow(struct bpf_reg_state
*reg
)
1789 if (reg
->max_value
> BPF_REGISTER_MAX_RANGE
)
1790 reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1791 if (reg
->min_value
< BPF_REGISTER_MIN_RANGE
||
1792 reg
->min_value
> BPF_REGISTER_MAX_RANGE
)
1793 reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1796 static u32
calc_align(u32 imm
)
1800 return imm
- ((imm
- 1) & imm
);
1803 static void adjust_reg_min_max_vals(struct bpf_verifier_env
*env
,
1804 struct bpf_insn
*insn
)
1806 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *dst_reg
;
1807 s64 min_val
= BPF_REGISTER_MIN_RANGE
;
1808 u64 max_val
= BPF_REGISTER_MAX_RANGE
;
1809 u8 opcode
= BPF_OP(insn
->code
);
1810 u32 dst_align
, src_align
;
1812 dst_reg
= ®s
[insn
->dst_reg
];
1814 if (BPF_SRC(insn
->code
) == BPF_X
) {
1815 check_reg_overflow(®s
[insn
->src_reg
]);
1816 min_val
= regs
[insn
->src_reg
].min_value
;
1817 max_val
= regs
[insn
->src_reg
].max_value
;
1819 /* If the source register is a random pointer then the
1820 * min_value/max_value values represent the range of the known
1821 * accesses into that value, not the actual min/max value of the
1822 * register itself. In this case we have to reset the reg range
1823 * values so we know it is not safe to look at.
1825 if (regs
[insn
->src_reg
].type
!= CONST_IMM
&&
1826 regs
[insn
->src_reg
].type
!= UNKNOWN_VALUE
) {
1827 min_val
= BPF_REGISTER_MIN_RANGE
;
1828 max_val
= BPF_REGISTER_MAX_RANGE
;
1831 src_align
= regs
[insn
->src_reg
].min_align
;
1833 } else if (insn
->imm
< BPF_REGISTER_MAX_RANGE
&&
1834 (s64
)insn
->imm
> BPF_REGISTER_MIN_RANGE
) {
1835 min_val
= max_val
= insn
->imm
;
1836 src_align
= calc_align(insn
->imm
);
1839 dst_align
= dst_reg
->min_align
;
1841 /* We don't know anything about what was done to this register, mark it
1842 * as unknown. Also, if both derived bounds came from signed/unsigned
1843 * mixed compares and one side is unbounded, we cannot really do anything
1844 * with them as boundaries cannot be trusted. Thus, arithmetic of two
1845 * regs of such kind will get invalidated bounds on the dst side.
1847 if ((min_val
== BPF_REGISTER_MIN_RANGE
&&
1848 max_val
== BPF_REGISTER_MAX_RANGE
) ||
1849 (BPF_SRC(insn
->code
) == BPF_X
&&
1850 ((min_val
!= BPF_REGISTER_MIN_RANGE
&&
1851 max_val
== BPF_REGISTER_MAX_RANGE
) ||
1852 (min_val
== BPF_REGISTER_MIN_RANGE
&&
1853 max_val
!= BPF_REGISTER_MAX_RANGE
) ||
1854 (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
&&
1855 dst_reg
->max_value
== BPF_REGISTER_MAX_RANGE
) ||
1856 (dst_reg
->min_value
== BPF_REGISTER_MIN_RANGE
&&
1857 dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)) &&
1858 regs
[insn
->dst_reg
].value_from_signed
!=
1859 regs
[insn
->src_reg
].value_from_signed
)) {
1860 reset_reg_range_values(regs
, insn
->dst_reg
);
1864 /* If one of our values was at the end of our ranges then we can't just
1865 * do our normal operations to the register, we need to set the values
1866 * to the min/max since they are undefined.
1868 if (min_val
== BPF_REGISTER_MIN_RANGE
)
1869 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1870 if (max_val
== BPF_REGISTER_MAX_RANGE
)
1871 dst_reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1875 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1876 dst_reg
->min_value
+= min_val
;
1877 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1878 dst_reg
->max_value
+= max_val
;
1879 dst_reg
->min_align
= min(src_align
, dst_align
);
1882 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1883 dst_reg
->min_value
-= min_val
;
1884 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1885 dst_reg
->max_value
-= max_val
;
1886 dst_reg
->min_align
= min(src_align
, dst_align
);
1889 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1890 dst_reg
->min_value
*= min_val
;
1891 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1892 dst_reg
->max_value
*= max_val
;
1893 dst_reg
->min_align
= max(src_align
, dst_align
);
1896 /* Disallow AND'ing of negative numbers, ain't nobody got time
1897 * for that. Otherwise the minimum is 0 and the max is the max
1898 * value we could AND against.
1901 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1903 dst_reg
->min_value
= 0;
1904 dst_reg
->max_value
= max_val
;
1905 dst_reg
->min_align
= max(src_align
, dst_align
);
1908 /* Gotta have special overflow logic here, if we're shifting
1909 * more than MAX_RANGE then just assume we have an invalid
1912 if (min_val
> ilog2(BPF_REGISTER_MAX_RANGE
)) {
1913 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1914 dst_reg
->min_align
= 1;
1916 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1917 dst_reg
->min_value
<<= min_val
;
1918 if (!dst_reg
->min_align
)
1919 dst_reg
->min_align
= 1;
1920 dst_reg
->min_align
<<= min_val
;
1922 if (max_val
> ilog2(BPF_REGISTER_MAX_RANGE
))
1923 dst_reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1924 else if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1925 dst_reg
->max_value
<<= max_val
;
1928 /* RSH by a negative number is undefined, and the BPF_RSH is an
1929 * unsigned shift, so make the appropriate casts.
1931 if (min_val
< 0 || dst_reg
->min_value
< 0) {
1932 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1934 dst_reg
->min_value
=
1935 (u64
)(dst_reg
->min_value
) >> min_val
;
1938 dst_reg
->min_align
= 1;
1940 dst_reg
->min_align
>>= (u64
) min_val
;
1941 if (!dst_reg
->min_align
)
1942 dst_reg
->min_align
= 1;
1944 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1945 dst_reg
->max_value
>>= max_val
;
1948 reset_reg_range_values(regs
, insn
->dst_reg
);
1952 check_reg_overflow(dst_reg
);
1955 /* check validity of 32-bit and 64-bit arithmetic operations */
1956 static int check_alu_op(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
1958 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *dst_reg
;
1959 u8 opcode
= BPF_OP(insn
->code
);
1962 if (opcode
== BPF_END
|| opcode
== BPF_NEG
) {
1963 if (opcode
== BPF_NEG
) {
1964 if (BPF_SRC(insn
->code
) != 0 ||
1965 insn
->src_reg
!= BPF_REG_0
||
1966 insn
->off
!= 0 || insn
->imm
!= 0) {
1967 verbose("BPF_NEG uses reserved fields\n");
1971 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
1972 (insn
->imm
!= 16 && insn
->imm
!= 32 && insn
->imm
!= 64)) {
1973 verbose("BPF_END uses reserved fields\n");
1978 /* check src operand */
1979 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
1983 if (is_pointer_value(env
, insn
->dst_reg
)) {
1984 verbose("R%d pointer arithmetic prohibited\n",
1989 /* check dest operand */
1990 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
1994 } else if (opcode
== BPF_MOV
) {
1996 if (BPF_SRC(insn
->code
) == BPF_X
) {
1997 if (insn
->imm
!= 0 || insn
->off
!= 0) {
1998 verbose("BPF_MOV uses reserved fields\n");
2002 /* check src operand */
2003 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2007 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
2008 verbose("BPF_MOV uses reserved fields\n");
2013 /* check dest operand */
2014 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
2018 /* we are setting our register to something new, we need to
2019 * reset its range values.
2021 reset_reg_range_values(regs
, insn
->dst_reg
);
2023 if (BPF_SRC(insn
->code
) == BPF_X
) {
2024 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
2026 * copy register state to dest reg
2028 regs
[insn
->dst_reg
] = regs
[insn
->src_reg
];
2030 if (is_pointer_value(env
, insn
->src_reg
)) {
2031 verbose("R%d partial copy of pointer\n",
2035 mark_reg_unknown_value(regs
, insn
->dst_reg
);
2039 * remember the value we stored into this reg
2041 regs
[insn
->dst_reg
].type
= CONST_IMM
;
2042 regs
[insn
->dst_reg
].imm
= insn
->imm
;
2043 regs
[insn
->dst_reg
].id
= 0;
2044 regs
[insn
->dst_reg
].max_value
= insn
->imm
;
2045 regs
[insn
->dst_reg
].min_value
= insn
->imm
;
2046 regs
[insn
->dst_reg
].min_align
= calc_align(insn
->imm
);
2047 regs
[insn
->dst_reg
].value_from_signed
= false;
2050 } else if (opcode
> BPF_END
) {
2051 verbose("invalid BPF_ALU opcode %x\n", opcode
);
2054 } else { /* all other ALU ops: and, sub, xor, add, ... */
2056 if (BPF_SRC(insn
->code
) == BPF_X
) {
2057 if (insn
->imm
!= 0 || insn
->off
!= 0) {
2058 verbose("BPF_ALU uses reserved fields\n");
2061 /* check src1 operand */
2062 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2066 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
2067 verbose("BPF_ALU uses reserved fields\n");
2072 /* check src2 operand */
2073 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
2077 if ((opcode
== BPF_MOD
|| opcode
== BPF_DIV
) &&
2078 BPF_SRC(insn
->code
) == BPF_K
&& insn
->imm
== 0) {
2079 verbose("div by zero\n");
2083 if ((opcode
== BPF_LSH
|| opcode
== BPF_RSH
||
2084 opcode
== BPF_ARSH
) && BPF_SRC(insn
->code
) == BPF_K
) {
2085 int size
= BPF_CLASS(insn
->code
) == BPF_ALU64
? 64 : 32;
2087 if (insn
->imm
< 0 || insn
->imm
>= size
) {
2088 verbose("invalid shift %d\n", insn
->imm
);
2093 /* check dest operand */
2094 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP_NO_MARK
);
2098 dst_reg
= ®s
[insn
->dst_reg
];
2100 /* first we want to adjust our ranges. */
2101 adjust_reg_min_max_vals(env
, insn
);
2103 /* pattern match 'bpf_add Rx, imm' instruction */
2104 if (opcode
== BPF_ADD
&& BPF_CLASS(insn
->code
) == BPF_ALU64
&&
2105 dst_reg
->type
== FRAME_PTR
&& BPF_SRC(insn
->code
) == BPF_K
) {
2106 dst_reg
->type
= PTR_TO_STACK
;
2107 dst_reg
->imm
= insn
->imm
;
2109 } else if (opcode
== BPF_ADD
&&
2110 BPF_CLASS(insn
->code
) == BPF_ALU64
&&
2111 dst_reg
->type
== PTR_TO_STACK
&&
2112 ((BPF_SRC(insn
->code
) == BPF_X
&&
2113 regs
[insn
->src_reg
].type
== CONST_IMM
) ||
2114 BPF_SRC(insn
->code
) == BPF_K
)) {
2115 if (BPF_SRC(insn
->code
) == BPF_X
)
2116 dst_reg
->imm
+= regs
[insn
->src_reg
].imm
;
2118 dst_reg
->imm
+= insn
->imm
;
2120 } else if (opcode
== BPF_ADD
&&
2121 BPF_CLASS(insn
->code
) == BPF_ALU64
&&
2122 (dst_reg
->type
== PTR_TO_PACKET
||
2123 (BPF_SRC(insn
->code
) == BPF_X
&&
2124 regs
[insn
->src_reg
].type
== PTR_TO_PACKET
))) {
2125 /* ptr_to_packet += K|X */
2126 return check_packet_ptr_add(env
, insn
);
2127 } else if (BPF_CLASS(insn
->code
) == BPF_ALU64
&&
2128 dst_reg
->type
== UNKNOWN_VALUE
&&
2129 env
->allow_ptr_leaks
) {
2130 /* unknown += K|X */
2131 return evaluate_reg_alu(env
, insn
);
2132 } else if (BPF_CLASS(insn
->code
) == BPF_ALU64
&&
2133 dst_reg
->type
== CONST_IMM
&&
2134 env
->allow_ptr_leaks
) {
2135 /* reg_imm += K|X */
2136 return evaluate_reg_imm_alu(env
, insn
);
2137 } else if (is_pointer_value(env
, insn
->dst_reg
)) {
2138 verbose("R%d pointer arithmetic prohibited\n",
2141 } else if (BPF_SRC(insn
->code
) == BPF_X
&&
2142 is_pointer_value(env
, insn
->src_reg
)) {
2143 verbose("R%d pointer arithmetic prohibited\n",
2148 /* If we did pointer math on a map value then just set it to our
2149 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
2150 * loads to this register appropriately, otherwise just mark the
2151 * register as unknown.
2153 if (env
->allow_ptr_leaks
&&
2154 BPF_CLASS(insn
->code
) == BPF_ALU64
&& opcode
== BPF_ADD
&&
2155 (dst_reg
->type
== PTR_TO_MAP_VALUE
||
2156 dst_reg
->type
== PTR_TO_MAP_VALUE_ADJ
))
2157 dst_reg
->type
= PTR_TO_MAP_VALUE_ADJ
;
2159 mark_reg_unknown_value(regs
, insn
->dst_reg
);
2165 static void find_good_pkt_pointers(struct bpf_verifier_state
*state
,
2166 struct bpf_reg_state
*dst_reg
)
2168 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
2171 /* LLVM can generate two kind of checks:
2177 * if (r2 > pkt_end) goto <handle exception>
2181 * r2 == dst_reg, pkt_end == src_reg
2182 * r2=pkt(id=n,off=8,r=0)
2183 * r3=pkt(id=n,off=0,r=0)
2189 * if (pkt_end >= r2) goto <access okay>
2190 * <handle exception>
2193 * pkt_end == dst_reg, r2 == src_reg
2194 * r2=pkt(id=n,off=8,r=0)
2195 * r3=pkt(id=n,off=0,r=0)
2197 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
2198 * so that range of bytes [r3, r3 + 8) is safe to access.
2201 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2202 if (regs
[i
].type
== PTR_TO_PACKET
&& regs
[i
].id
== dst_reg
->id
)
2203 /* keep the maximum range already checked */
2204 regs
[i
].range
= max(regs
[i
].range
, dst_reg
->off
);
2206 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
2207 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
2209 reg
= &state
->spilled_regs
[i
/ BPF_REG_SIZE
];
2210 if (reg
->type
== PTR_TO_PACKET
&& reg
->id
== dst_reg
->id
)
2211 reg
->range
= max(reg
->range
, dst_reg
->off
);
2215 /* Adjusts the register min/max values in the case that the dst_reg is the
2216 * variable register that we are working on, and src_reg is a constant or we're
2217 * simply doing a BPF_K check.
2219 static void reg_set_min_max(struct bpf_reg_state
*true_reg
,
2220 struct bpf_reg_state
*false_reg
, u64 val
,
2223 bool value_from_signed
= true;
2224 bool is_range
= true;
2228 /* If this is false then we know nothing Jon Snow, but if it is
2229 * true then we know for sure.
2231 true_reg
->max_value
= true_reg
->min_value
= val
;
2235 /* If this is true we know nothing Jon Snow, but if it is false
2236 * we know the value for sure;
2238 false_reg
->max_value
= false_reg
->min_value
= val
;
2242 value_from_signed
= false;
2245 if (true_reg
->value_from_signed
!= value_from_signed
)
2246 reset_reg_range_values(true_reg
, 0);
2247 if (false_reg
->value_from_signed
!= value_from_signed
)
2248 reset_reg_range_values(false_reg
, 0);
2249 if (opcode
== BPF_JGT
) {
2250 /* Unsigned comparison, the minimum value is 0. */
2251 false_reg
->min_value
= 0;
2253 /* If this is false then we know the maximum val is val,
2254 * otherwise we know the min val is val+1.
2256 false_reg
->max_value
= val
;
2257 false_reg
->value_from_signed
= value_from_signed
;
2258 true_reg
->min_value
= val
+ 1;
2259 true_reg
->value_from_signed
= value_from_signed
;
2262 value_from_signed
= false;
2265 if (true_reg
->value_from_signed
!= value_from_signed
)
2266 reset_reg_range_values(true_reg
, 0);
2267 if (false_reg
->value_from_signed
!= value_from_signed
)
2268 reset_reg_range_values(false_reg
, 0);
2269 if (opcode
== BPF_JGE
) {
2270 /* Unsigned comparison, the minimum value is 0. */
2271 false_reg
->min_value
= 0;
2273 /* If this is false then we know the maximum value is val - 1,
2274 * otherwise we know the mimimum value is val.
2276 false_reg
->max_value
= val
- 1;
2277 false_reg
->value_from_signed
= value_from_signed
;
2278 true_reg
->min_value
= val
;
2279 true_reg
->value_from_signed
= value_from_signed
;
2285 check_reg_overflow(false_reg
);
2286 check_reg_overflow(true_reg
);
2288 if (__is_pointer_value(false, false_reg
))
2289 reset_reg_range_values(false_reg
, 0);
2290 if (__is_pointer_value(false, true_reg
))
2291 reset_reg_range_values(true_reg
, 0);
2295 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
2296 * is the variable reg.
2298 static void reg_set_min_max_inv(struct bpf_reg_state
*true_reg
,
2299 struct bpf_reg_state
*false_reg
, u64 val
,
2302 bool value_from_signed
= true;
2303 bool is_range
= true;
2307 /* If this is false then we know nothing Jon Snow, but if it is
2308 * true then we know for sure.
2310 true_reg
->max_value
= true_reg
->min_value
= val
;
2314 /* If this is true we know nothing Jon Snow, but if it is false
2315 * we know the value for sure;
2317 false_reg
->max_value
= false_reg
->min_value
= val
;
2321 value_from_signed
= false;
2324 if (true_reg
->value_from_signed
!= value_from_signed
)
2325 reset_reg_range_values(true_reg
, 0);
2326 if (false_reg
->value_from_signed
!= value_from_signed
)
2327 reset_reg_range_values(false_reg
, 0);
2328 if (opcode
== BPF_JGT
) {
2329 /* Unsigned comparison, the minimum value is 0. */
2330 true_reg
->min_value
= 0;
2333 * If this is false, then the val is <= the register, if it is
2334 * true the register <= to the val.
2336 false_reg
->min_value
= val
;
2337 false_reg
->value_from_signed
= value_from_signed
;
2338 true_reg
->max_value
= val
- 1;
2339 true_reg
->value_from_signed
= value_from_signed
;
2342 value_from_signed
= false;
2345 if (true_reg
->value_from_signed
!= value_from_signed
)
2346 reset_reg_range_values(true_reg
, 0);
2347 if (false_reg
->value_from_signed
!= value_from_signed
)
2348 reset_reg_range_values(false_reg
, 0);
2349 if (opcode
== BPF_JGE
) {
2350 /* Unsigned comparison, the minimum value is 0. */
2351 true_reg
->min_value
= 0;
2353 /* If this is false then constant < register, if it is true then
2354 * the register < constant.
2356 false_reg
->min_value
= val
+ 1;
2357 false_reg
->value_from_signed
= value_from_signed
;
2358 true_reg
->max_value
= val
;
2359 true_reg
->value_from_signed
= value_from_signed
;
2365 check_reg_overflow(false_reg
);
2366 check_reg_overflow(true_reg
);
2368 if (__is_pointer_value(false, false_reg
))
2369 reset_reg_range_values(false_reg
, 0);
2370 if (__is_pointer_value(false, true_reg
))
2371 reset_reg_range_values(true_reg
, 0);
2375 static void mark_map_reg(struct bpf_reg_state
*regs
, u32 regno
, u32 id
,
2376 enum bpf_reg_type type
)
2378 struct bpf_reg_state
*reg
= ®s
[regno
];
2380 if (reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
&& reg
->id
== id
) {
2381 if (type
== UNKNOWN_VALUE
) {
2382 __mark_reg_unknown_value(regs
, regno
);
2383 } else if (reg
->map_ptr
->inner_map_meta
) {
2384 reg
->type
= CONST_PTR_TO_MAP
;
2385 reg
->map_ptr
= reg
->map_ptr
->inner_map_meta
;
2389 /* We don't need id from this point onwards anymore, thus we
2390 * should better reset it, so that state pruning has chances
2397 /* The logic is similar to find_good_pkt_pointers(), both could eventually
2398 * be folded together at some point.
2400 static void mark_map_regs(struct bpf_verifier_state
*state
, u32 regno
,
2401 enum bpf_reg_type type
)
2403 struct bpf_reg_state
*regs
= state
->regs
;
2404 u32 id
= regs
[regno
].id
;
2407 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2408 mark_map_reg(regs
, i
, id
, type
);
2410 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
2411 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
2413 mark_map_reg(state
->spilled_regs
, i
/ BPF_REG_SIZE
, id
, type
);
2417 static int check_cond_jmp_op(struct bpf_verifier_env
*env
,
2418 struct bpf_insn
*insn
, int *insn_idx
)
2420 struct bpf_verifier_state
*other_branch
, *this_branch
= &env
->cur_state
;
2421 struct bpf_reg_state
*regs
= this_branch
->regs
, *dst_reg
;
2422 u8 opcode
= BPF_OP(insn
->code
);
2425 if (opcode
> BPF_EXIT
) {
2426 verbose("invalid BPF_JMP opcode %x\n", opcode
);
2430 if (BPF_SRC(insn
->code
) == BPF_X
) {
2431 if (insn
->imm
!= 0) {
2432 verbose("BPF_JMP uses reserved fields\n");
2436 /* check src1 operand */
2437 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2441 if (is_pointer_value(env
, insn
->src_reg
)) {
2442 verbose("R%d pointer comparison prohibited\n",
2447 if (insn
->src_reg
!= BPF_REG_0
) {
2448 verbose("BPF_JMP uses reserved fields\n");
2453 /* check src2 operand */
2454 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
2458 dst_reg
= ®s
[insn
->dst_reg
];
2460 /* detect if R == 0 where R was initialized to zero earlier */
2461 if (BPF_SRC(insn
->code
) == BPF_K
&&
2462 (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
2463 dst_reg
->type
== CONST_IMM
&& dst_reg
->imm
== insn
->imm
) {
2464 if (opcode
== BPF_JEQ
) {
2465 /* if (imm == imm) goto pc+off;
2466 * only follow the goto, ignore fall-through
2468 *insn_idx
+= insn
->off
;
2471 /* if (imm != imm) goto pc+off;
2472 * only follow fall-through branch, since
2473 * that's where the program will go
2479 other_branch
= push_stack(env
, *insn_idx
+ insn
->off
+ 1, *insn_idx
);
2483 /* detect if we are comparing against a constant value so we can adjust
2484 * our min/max values for our dst register.
2486 if (BPF_SRC(insn
->code
) == BPF_X
) {
2487 if (regs
[insn
->src_reg
].type
== CONST_IMM
)
2488 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
2489 dst_reg
, regs
[insn
->src_reg
].imm
,
2491 else if (dst_reg
->type
== CONST_IMM
)
2492 reg_set_min_max_inv(&other_branch
->regs
[insn
->src_reg
],
2493 ®s
[insn
->src_reg
], dst_reg
->imm
,
2496 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
2497 dst_reg
, insn
->imm
, opcode
);
2500 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
2501 if (BPF_SRC(insn
->code
) == BPF_K
&&
2502 insn
->imm
== 0 && (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
2503 dst_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
2504 /* Mark all identical map registers in each branch as either
2505 * safe or unknown depending R == 0 or R != 0 conditional.
2507 mark_map_regs(this_branch
, insn
->dst_reg
,
2508 opcode
== BPF_JEQ
? PTR_TO_MAP_VALUE
: UNKNOWN_VALUE
);
2509 mark_map_regs(other_branch
, insn
->dst_reg
,
2510 opcode
== BPF_JEQ
? UNKNOWN_VALUE
: PTR_TO_MAP_VALUE
);
2511 } else if (BPF_SRC(insn
->code
) == BPF_X
&& opcode
== BPF_JGT
&&
2512 dst_reg
->type
== PTR_TO_PACKET
&&
2513 regs
[insn
->src_reg
].type
== PTR_TO_PACKET_END
) {
2514 find_good_pkt_pointers(this_branch
, dst_reg
);
2515 } else if (BPF_SRC(insn
->code
) == BPF_X
&& opcode
== BPF_JGE
&&
2516 dst_reg
->type
== PTR_TO_PACKET_END
&&
2517 regs
[insn
->src_reg
].type
== PTR_TO_PACKET
) {
2518 find_good_pkt_pointers(other_branch
, ®s
[insn
->src_reg
]);
2519 } else if (is_pointer_value(env
, insn
->dst_reg
)) {
2520 verbose("R%d pointer comparison prohibited\n", insn
->dst_reg
);
2524 print_verifier_state(this_branch
);
2528 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
2529 static struct bpf_map
*ld_imm64_to_map_ptr(struct bpf_insn
*insn
)
2531 u64 imm64
= ((u64
) (u32
) insn
[0].imm
) | ((u64
) (u32
) insn
[1].imm
) << 32;
2533 return (struct bpf_map
*) (unsigned long) imm64
;
2536 /* verify BPF_LD_IMM64 instruction */
2537 static int check_ld_imm(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
2539 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
2542 if (BPF_SIZE(insn
->code
) != BPF_DW
) {
2543 verbose("invalid BPF_LD_IMM insn\n");
2546 if (insn
->off
!= 0) {
2547 verbose("BPF_LD_IMM64 uses reserved fields\n");
2551 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
2555 if (insn
->src_reg
== 0) {
2556 u64 imm
= ((u64
)(insn
+ 1)->imm
<< 32) | (u32
)insn
->imm
;
2558 regs
[insn
->dst_reg
].type
= CONST_IMM
;
2559 regs
[insn
->dst_reg
].imm
= imm
;
2560 regs
[insn
->dst_reg
].id
= 0;
2564 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2565 BUG_ON(insn
->src_reg
!= BPF_PSEUDO_MAP_FD
);
2567 regs
[insn
->dst_reg
].type
= CONST_PTR_TO_MAP
;
2568 regs
[insn
->dst_reg
].map_ptr
= ld_imm64_to_map_ptr(insn
);
2572 static bool may_access_skb(enum bpf_prog_type type
)
2575 case BPF_PROG_TYPE_SOCKET_FILTER
:
2576 case BPF_PROG_TYPE_SCHED_CLS
:
2577 case BPF_PROG_TYPE_SCHED_ACT
:
2584 /* verify safety of LD_ABS|LD_IND instructions:
2585 * - they can only appear in the programs where ctx == skb
2586 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2587 * preserve R6-R9, and store return value into R0
2590 * ctx == skb == R6 == CTX
2593 * SRC == any register
2594 * IMM == 32-bit immediate
2597 * R0 - 8/16/32-bit skb data converted to cpu endianness
2599 static int check_ld_abs(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
2601 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
2602 u8 mode
= BPF_MODE(insn
->code
);
2605 if (!may_access_skb(env
->prog
->type
)) {
2606 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
2610 if (insn
->dst_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
2611 BPF_SIZE(insn
->code
) == BPF_DW
||
2612 (mode
== BPF_ABS
&& insn
->src_reg
!= BPF_REG_0
)) {
2613 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
2617 /* check whether implicit source operand (register R6) is readable */
2618 err
= check_reg_arg(regs
, BPF_REG_6
, SRC_OP
);
2622 if (regs
[BPF_REG_6
].type
!= PTR_TO_CTX
) {
2623 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2627 if (mode
== BPF_IND
) {
2628 /* check explicit source operand */
2629 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2634 /* reset caller saved regs to unreadable */
2635 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++)
2636 mark_reg_not_init(regs
, caller_saved
[i
]);
2638 /* mark destination R0 register as readable, since it contains
2639 * the value fetched from the packet
2641 regs
[BPF_REG_0
].type
= UNKNOWN_VALUE
;
2645 /* non-recursive DFS pseudo code
2646 * 1 procedure DFS-iterative(G,v):
2647 * 2 label v as discovered
2648 * 3 let S be a stack
2650 * 5 while S is not empty
2652 * 7 if t is what we're looking for:
2654 * 9 for all edges e in G.adjacentEdges(t) do
2655 * 10 if edge e is already labelled
2656 * 11 continue with the next edge
2657 * 12 w <- G.adjacentVertex(t,e)
2658 * 13 if vertex w is not discovered and not explored
2659 * 14 label e as tree-edge
2660 * 15 label w as discovered
2663 * 18 else if vertex w is discovered
2664 * 19 label e as back-edge
2666 * 21 // vertex w is explored
2667 * 22 label e as forward- or cross-edge
2668 * 23 label t as explored
2673 * 0x11 - discovered and fall-through edge labelled
2674 * 0x12 - discovered and fall-through and branch edges labelled
2685 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
2687 static int *insn_stack
; /* stack of insns to process */
2688 static int cur_stack
; /* current stack index */
2689 static int *insn_state
;
2691 /* t, w, e - match pseudo-code above:
2692 * t - index of current instruction
2693 * w - next instruction
2696 static int push_insn(int t
, int w
, int e
, struct bpf_verifier_env
*env
)
2698 if (e
== FALLTHROUGH
&& insn_state
[t
] >= (DISCOVERED
| FALLTHROUGH
))
2701 if (e
== BRANCH
&& insn_state
[t
] >= (DISCOVERED
| BRANCH
))
2704 if (w
< 0 || w
>= env
->prog
->len
) {
2705 verbose("jump out of range from insn %d to %d\n", t
, w
);
2710 /* mark branch target for state pruning */
2711 env
->explored_states
[w
] = STATE_LIST_MARK
;
2713 if (insn_state
[w
] == 0) {
2715 insn_state
[t
] = DISCOVERED
| e
;
2716 insn_state
[w
] = DISCOVERED
;
2717 if (cur_stack
>= env
->prog
->len
)
2719 insn_stack
[cur_stack
++] = w
;
2721 } else if ((insn_state
[w
] & 0xF0) == DISCOVERED
) {
2722 verbose("back-edge from insn %d to %d\n", t
, w
);
2724 } else if (insn_state
[w
] == EXPLORED
) {
2725 /* forward- or cross-edge */
2726 insn_state
[t
] = DISCOVERED
| e
;
2728 verbose("insn state internal bug\n");
2734 /* non-recursive depth-first-search to detect loops in BPF program
2735 * loop == back-edge in directed graph
2737 static int check_cfg(struct bpf_verifier_env
*env
)
2739 struct bpf_insn
*insns
= env
->prog
->insnsi
;
2740 int insn_cnt
= env
->prog
->len
;
2744 insn_state
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
2748 insn_stack
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
2754 insn_state
[0] = DISCOVERED
; /* mark 1st insn as discovered */
2755 insn_stack
[0] = 0; /* 0 is the first instruction */
2761 t
= insn_stack
[cur_stack
- 1];
2763 if (BPF_CLASS(insns
[t
].code
) == BPF_JMP
) {
2764 u8 opcode
= BPF_OP(insns
[t
].code
);
2766 if (opcode
== BPF_EXIT
) {
2768 } else if (opcode
== BPF_CALL
) {
2769 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2774 if (t
+ 1 < insn_cnt
)
2775 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
2776 } else if (opcode
== BPF_JA
) {
2777 if (BPF_SRC(insns
[t
].code
) != BPF_K
) {
2781 /* unconditional jump with single edge */
2782 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1,
2788 /* tell verifier to check for equivalent states
2789 * after every call and jump
2791 if (t
+ 1 < insn_cnt
)
2792 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
2794 /* conditional jump with two edges */
2795 env
->explored_states
[t
] = STATE_LIST_MARK
;
2796 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2802 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1, BRANCH
, env
);
2809 /* all other non-branch instructions with single
2812 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2820 insn_state
[t
] = EXPLORED
;
2821 if (cur_stack
-- <= 0) {
2822 verbose("pop stack internal bug\n");
2829 for (i
= 0; i
< insn_cnt
; i
++) {
2830 if (insn_state
[i
] != EXPLORED
) {
2831 verbose("unreachable insn %d\n", i
);
2836 ret
= 0; /* cfg looks good */
2844 /* the following conditions reduce the number of explored insns
2845 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2847 static bool compare_ptrs_to_packet(struct bpf_verifier_env
*env
,
2848 struct bpf_reg_state
*old
,
2849 struct bpf_reg_state
*cur
)
2851 if (old
->id
!= cur
->id
)
2854 /* old ptr_to_packet is more conservative, since it allows smaller
2856 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2857 * old(off=0,r=10) means that with range=10 the verifier proceeded
2858 * further and found no issues with the program. Now we're in the same
2859 * spot with cur(off=0,r=20), so we're safe too, since anything further
2860 * will only be looking at most 10 bytes after this pointer.
2862 if (old
->off
== cur
->off
&& old
->range
< cur
->range
)
2865 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2866 * since both cannot be used for packet access and safe(old)
2867 * pointer has smaller off that could be used for further
2868 * 'if (ptr > data_end)' check
2870 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2871 * that we cannot access the packet.
2872 * The safe range is:
2873 * [ptr, ptr + range - off)
2874 * so whenever off >=range, it means no safe bytes from this pointer.
2875 * When comparing old->off <= cur->off, it means that older code
2876 * went with smaller offset and that offset was later
2877 * used to figure out the safe range after 'if (ptr > data_end)' check
2878 * Say, 'old' state was explored like:
2879 * ... R3(off=0, r=0)
2881 * ... now R4(off=20,r=0) <-- here
2882 * if (R4 > data_end)
2883 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2884 * ... the code further went all the way to bpf_exit.
2885 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2886 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2887 * goes further, such cur_R4 will give larger safe packet range after
2888 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2889 * so they will be good with r=30 and we can prune the search.
2891 if (!env
->strict_alignment
&& old
->off
<= cur
->off
&&
2892 old
->off
>= old
->range
&& cur
->off
>= cur
->range
)
2898 /* compare two verifier states
2900 * all states stored in state_list are known to be valid, since
2901 * verifier reached 'bpf_exit' instruction through them
2903 * this function is called when verifier exploring different branches of
2904 * execution popped from the state stack. If it sees an old state that has
2905 * more strict register state and more strict stack state then this execution
2906 * branch doesn't need to be explored further, since verifier already
2907 * concluded that more strict state leads to valid finish.
2909 * Therefore two states are equivalent if register state is more conservative
2910 * and explored stack state is more conservative than the current one.
2913 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2914 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2916 * In other words if current stack state (one being explored) has more
2917 * valid slots than old one that already passed validation, it means
2918 * the verifier can stop exploring and conclude that current state is valid too
2920 * Similarly with registers. If explored state has register type as invalid
2921 * whereas register type in current state is meaningful, it means that
2922 * the current state will reach 'bpf_exit' instruction safely
2924 static bool states_equal(struct bpf_verifier_env
*env
,
2925 struct bpf_verifier_state
*old
,
2926 struct bpf_verifier_state
*cur
)
2928 bool varlen_map_access
= env
->varlen_map_value_access
;
2929 struct bpf_reg_state
*rold
, *rcur
;
2932 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
2933 rold
= &old
->regs
[i
];
2934 rcur
= &cur
->regs
[i
];
2936 if (memcmp(rold
, rcur
, sizeof(*rold
)) == 0)
2939 /* If the ranges were not the same, but everything else was and
2940 * we didn't do a variable access into a map then we are a-ok.
2942 if (!varlen_map_access
&&
2943 memcmp(rold
, rcur
, offsetofend(struct bpf_reg_state
, id
)) == 0)
2946 /* If we didn't map access then again we don't care about the
2947 * mismatched range values and it's ok if our old type was
2948 * UNKNOWN and we didn't go to a NOT_INIT'ed reg.
2950 if (rold
->type
== NOT_INIT
||
2951 (!varlen_map_access
&& rold
->type
== UNKNOWN_VALUE
&&
2952 rcur
->type
!= NOT_INIT
))
2955 /* Don't care about the reg->id in this case. */
2956 if (rold
->type
== PTR_TO_MAP_VALUE_OR_NULL
&&
2957 rcur
->type
== PTR_TO_MAP_VALUE_OR_NULL
&&
2958 rold
->map_ptr
== rcur
->map_ptr
)
2961 if (rold
->type
== PTR_TO_PACKET
&& rcur
->type
== PTR_TO_PACKET
&&
2962 compare_ptrs_to_packet(env
, rold
, rcur
))
2968 for (i
= 0; i
< MAX_BPF_STACK
; i
++) {
2969 if (old
->stack_slot_type
[i
] == STACK_INVALID
)
2971 if (old
->stack_slot_type
[i
] != cur
->stack_slot_type
[i
])
2972 /* Ex: old explored (safe) state has STACK_SPILL in
2973 * this stack slot, but current has has STACK_MISC ->
2974 * this verifier states are not equivalent,
2975 * return false to continue verification of this path
2978 if (i
% BPF_REG_SIZE
)
2980 if (old
->stack_slot_type
[i
] != STACK_SPILL
)
2982 if (memcmp(&old
->spilled_regs
[i
/ BPF_REG_SIZE
],
2983 &cur
->spilled_regs
[i
/ BPF_REG_SIZE
],
2984 sizeof(old
->spilled_regs
[0])))
2985 /* when explored and current stack slot types are
2986 * the same, check that stored pointers types
2987 * are the same as well.
2988 * Ex: explored safe path could have stored
2989 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
2990 * but current path has stored:
2991 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
2992 * such verifier states are not equivalent.
2993 * return false to continue verification of this path
3002 static int is_state_visited(struct bpf_verifier_env
*env
, int insn_idx
)
3004 struct bpf_verifier_state_list
*new_sl
;
3005 struct bpf_verifier_state_list
*sl
;
3007 sl
= env
->explored_states
[insn_idx
];
3009 /* this 'insn_idx' instruction wasn't marked, so we will not
3010 * be doing state search here
3014 while (sl
!= STATE_LIST_MARK
) {
3015 if (states_equal(env
, &sl
->state
, &env
->cur_state
))
3016 /* reached equivalent register/stack state,
3023 /* there were no equivalent states, remember current one.
3024 * technically the current state is not proven to be safe yet,
3025 * but it will either reach bpf_exit (which means it's safe) or
3026 * it will be rejected. Since there are no loops, we won't be
3027 * seeing this 'insn_idx' instruction again on the way to bpf_exit
3029 new_sl
= kmalloc(sizeof(struct bpf_verifier_state_list
), GFP_USER
);
3033 /* add new state to the head of linked list */
3034 memcpy(&new_sl
->state
, &env
->cur_state
, sizeof(env
->cur_state
));
3035 new_sl
->next
= env
->explored_states
[insn_idx
];
3036 env
->explored_states
[insn_idx
] = new_sl
;
3040 static int ext_analyzer_insn_hook(struct bpf_verifier_env
*env
,
3041 int insn_idx
, int prev_insn_idx
)
3043 if (!env
->analyzer_ops
|| !env
->analyzer_ops
->insn_hook
)
3046 return env
->analyzer_ops
->insn_hook(env
, insn_idx
, prev_insn_idx
);
3049 static int do_check(struct bpf_verifier_env
*env
)
3051 struct bpf_verifier_state
*state
= &env
->cur_state
;
3052 struct bpf_insn
*insns
= env
->prog
->insnsi
;
3053 struct bpf_reg_state
*regs
= state
->regs
;
3054 int insn_cnt
= env
->prog
->len
;
3055 int insn_idx
, prev_insn_idx
= 0;
3056 int insn_processed
= 0;
3057 bool do_print_state
= false;
3059 init_reg_state(regs
);
3061 env
->varlen_map_value_access
= false;
3063 struct bpf_insn
*insn
;
3067 if (insn_idx
>= insn_cnt
) {
3068 verbose("invalid insn idx %d insn_cnt %d\n",
3069 insn_idx
, insn_cnt
);
3073 insn
= &insns
[insn_idx
];
3074 class = BPF_CLASS(insn
->code
);
3076 if (++insn_processed
> BPF_COMPLEXITY_LIMIT_INSNS
) {
3077 verbose("BPF program is too large. Processed %d insn\n",
3082 err
= is_state_visited(env
, insn_idx
);
3086 /* found equivalent state, can prune the search */
3089 verbose("\nfrom %d to %d: safe\n",
3090 prev_insn_idx
, insn_idx
);
3092 verbose("%d: safe\n", insn_idx
);
3094 goto process_bpf_exit
;
3100 if (log_level
> 1 || (log_level
&& do_print_state
)) {
3102 verbose("%d:", insn_idx
);
3104 verbose("\nfrom %d to %d:",
3105 prev_insn_idx
, insn_idx
);
3106 print_verifier_state(&env
->cur_state
);
3107 do_print_state
= false;
3111 verbose("%d: ", insn_idx
);
3112 print_bpf_insn(env
, insn
);
3115 err
= ext_analyzer_insn_hook(env
, insn_idx
, prev_insn_idx
);
3119 if (class == BPF_ALU
|| class == BPF_ALU64
) {
3120 err
= check_alu_op(env
, insn
);
3124 } else if (class == BPF_LDX
) {
3125 enum bpf_reg_type
*prev_src_type
, src_reg_type
;
3127 /* check for reserved fields is already done */
3129 /* check src operand */
3130 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
3134 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP_NO_MARK
);
3138 src_reg_type
= regs
[insn
->src_reg
].type
;
3140 /* check that memory (src_reg + off) is readable,
3141 * the state of dst_reg will be updated by this func
3143 err
= check_mem_access(env
, insn_idx
, insn
->src_reg
, insn
->off
,
3144 BPF_SIZE(insn
->code
), BPF_READ
,
3149 prev_src_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
3151 if (*prev_src_type
== NOT_INIT
) {
3153 * dst_reg = *(u32 *)(src_reg + off)
3154 * save type to validate intersecting paths
3156 *prev_src_type
= src_reg_type
;
3158 } else if (src_reg_type
!= *prev_src_type
&&
3159 (src_reg_type
== PTR_TO_CTX
||
3160 *prev_src_type
== PTR_TO_CTX
)) {
3161 /* ABuser program is trying to use the same insn
3162 * dst_reg = *(u32*) (src_reg + off)
3163 * with different pointer types:
3164 * src_reg == ctx in one branch and
3165 * src_reg == stack|map in some other branch.
3168 verbose("same insn cannot be used with different pointers\n");
3172 } else if (class == BPF_STX
) {
3173 enum bpf_reg_type
*prev_dst_type
, dst_reg_type
;
3175 if (BPF_MODE(insn
->code
) == BPF_XADD
) {
3176 err
= check_xadd(env
, insn_idx
, insn
);
3183 /* check src1 operand */
3184 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
3187 /* check src2 operand */
3188 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
3192 dst_reg_type
= regs
[insn
->dst_reg
].type
;
3194 /* check that memory (dst_reg + off) is writeable */
3195 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
3196 BPF_SIZE(insn
->code
), BPF_WRITE
,
3201 prev_dst_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
3203 if (*prev_dst_type
== NOT_INIT
) {
3204 *prev_dst_type
= dst_reg_type
;
3205 } else if (dst_reg_type
!= *prev_dst_type
&&
3206 (dst_reg_type
== PTR_TO_CTX
||
3207 *prev_dst_type
== PTR_TO_CTX
)) {
3208 verbose("same insn cannot be used with different pointers\n");
3212 } else if (class == BPF_ST
) {
3213 if (BPF_MODE(insn
->code
) != BPF_MEM
||
3214 insn
->src_reg
!= BPF_REG_0
) {
3215 verbose("BPF_ST uses reserved fields\n");
3218 /* check src operand */
3219 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
3223 /* check that memory (dst_reg + off) is writeable */
3224 err
= check_mem_access(env
, insn_idx
, insn
->dst_reg
, insn
->off
,
3225 BPF_SIZE(insn
->code
), BPF_WRITE
,
3230 } else if (class == BPF_JMP
) {
3231 u8 opcode
= BPF_OP(insn
->code
);
3233 if (opcode
== BPF_CALL
) {
3234 if (BPF_SRC(insn
->code
) != BPF_K
||
3236 insn
->src_reg
!= BPF_REG_0
||
3237 insn
->dst_reg
!= BPF_REG_0
) {
3238 verbose("BPF_CALL uses reserved fields\n");
3242 err
= check_call(env
, insn
->imm
, insn_idx
);
3246 } else if (opcode
== BPF_JA
) {
3247 if (BPF_SRC(insn
->code
) != BPF_K
||
3249 insn
->src_reg
!= BPF_REG_0
||
3250 insn
->dst_reg
!= BPF_REG_0
) {
3251 verbose("BPF_JA uses reserved fields\n");
3255 insn_idx
+= insn
->off
+ 1;
3258 } else if (opcode
== BPF_EXIT
) {
3259 if (BPF_SRC(insn
->code
) != BPF_K
||
3261 insn
->src_reg
!= BPF_REG_0
||
3262 insn
->dst_reg
!= BPF_REG_0
) {
3263 verbose("BPF_EXIT uses reserved fields\n");
3267 /* eBPF calling convetion is such that R0 is used
3268 * to return the value from eBPF program.
3269 * Make sure that it's readable at this time
3270 * of bpf_exit, which means that program wrote
3271 * something into it earlier
3273 err
= check_reg_arg(regs
, BPF_REG_0
, SRC_OP
);
3277 if (is_pointer_value(env
, BPF_REG_0
)) {
3278 verbose("R0 leaks addr as return value\n");
3283 insn_idx
= pop_stack(env
, &prev_insn_idx
);
3287 do_print_state
= true;
3291 err
= check_cond_jmp_op(env
, insn
, &insn_idx
);
3295 } else if (class == BPF_LD
) {
3296 u8 mode
= BPF_MODE(insn
->code
);
3298 if (mode
== BPF_ABS
|| mode
== BPF_IND
) {
3299 err
= check_ld_abs(env
, insn
);
3303 } else if (mode
== BPF_IMM
) {
3304 err
= check_ld_imm(env
, insn
);
3310 verbose("invalid BPF_LD mode\n");
3313 reset_reg_range_values(regs
, insn
->dst_reg
);
3315 verbose("unknown insn class %d\n", class);
3322 verbose("processed %d insns, stack depth %d\n",
3323 insn_processed
, env
->prog
->aux
->stack_depth
);
3327 static int check_map_prealloc(struct bpf_map
*map
)
3329 return (map
->map_type
!= BPF_MAP_TYPE_HASH
&&
3330 map
->map_type
!= BPF_MAP_TYPE_PERCPU_HASH
&&
3331 map
->map_type
!= BPF_MAP_TYPE_HASH_OF_MAPS
) ||
3332 !(map
->map_flags
& BPF_F_NO_PREALLOC
);
3335 static int check_map_prog_compatibility(struct bpf_map
*map
,
3336 struct bpf_prog
*prog
)
3339 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
3340 * preallocated hash maps, since doing memory allocation
3341 * in overflow_handler can crash depending on where nmi got
3344 if (prog
->type
== BPF_PROG_TYPE_PERF_EVENT
) {
3345 if (!check_map_prealloc(map
)) {
3346 verbose("perf_event programs can only use preallocated hash map\n");
3349 if (map
->inner_map_meta
&&
3350 !check_map_prealloc(map
->inner_map_meta
)) {
3351 verbose("perf_event programs can only use preallocated inner hash map\n");
3358 /* look for pseudo eBPF instructions that access map FDs and
3359 * replace them with actual map pointers
3361 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env
*env
)
3363 struct bpf_insn
*insn
= env
->prog
->insnsi
;
3364 int insn_cnt
= env
->prog
->len
;
3367 err
= bpf_prog_calc_tag(env
->prog
);
3371 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
3372 if (BPF_CLASS(insn
->code
) == BPF_LDX
&&
3373 (BPF_MODE(insn
->code
) != BPF_MEM
|| insn
->imm
!= 0)) {
3374 verbose("BPF_LDX uses reserved fields\n");
3378 if (BPF_CLASS(insn
->code
) == BPF_STX
&&
3379 ((BPF_MODE(insn
->code
) != BPF_MEM
&&
3380 BPF_MODE(insn
->code
) != BPF_XADD
) || insn
->imm
!= 0)) {
3381 verbose("BPF_STX uses reserved fields\n");
3385 if (insn
[0].code
== (BPF_LD
| BPF_IMM
| BPF_DW
)) {
3386 struct bpf_map
*map
;
3389 if (i
== insn_cnt
- 1 || insn
[1].code
!= 0 ||
3390 insn
[1].dst_reg
!= 0 || insn
[1].src_reg
!= 0 ||
3392 verbose("invalid bpf_ld_imm64 insn\n");
3396 if (insn
->src_reg
== 0)
3397 /* valid generic load 64-bit imm */
3400 if (insn
->src_reg
!= BPF_PSEUDO_MAP_FD
) {
3401 verbose("unrecognized bpf_ld_imm64 insn\n");
3405 f
= fdget(insn
->imm
);
3406 map
= __bpf_map_get(f
);
3408 verbose("fd %d is not pointing to valid bpf_map\n",
3410 return PTR_ERR(map
);
3413 err
= check_map_prog_compatibility(map
, env
->prog
);
3419 /* store map pointer inside BPF_LD_IMM64 instruction */
3420 insn
[0].imm
= (u32
) (unsigned long) map
;
3421 insn
[1].imm
= ((u64
) (unsigned long) map
) >> 32;
3423 /* check whether we recorded this map already */
3424 for (j
= 0; j
< env
->used_map_cnt
; j
++)
3425 if (env
->used_maps
[j
] == map
) {
3430 if (env
->used_map_cnt
>= MAX_USED_MAPS
) {
3435 /* hold the map. If the program is rejected by verifier,
3436 * the map will be released by release_maps() or it
3437 * will be used by the valid program until it's unloaded
3438 * and all maps are released in free_bpf_prog_info()
3440 map
= bpf_map_inc(map
, false);
3443 return PTR_ERR(map
);
3445 env
->used_maps
[env
->used_map_cnt
++] = map
;
3454 /* now all pseudo BPF_LD_IMM64 instructions load valid
3455 * 'struct bpf_map *' into a register instead of user map_fd.
3456 * These pointers will be used later by verifier to validate map access.
3461 /* drop refcnt of maps used by the rejected program */
3462 static void release_maps(struct bpf_verifier_env
*env
)
3466 for (i
= 0; i
< env
->used_map_cnt
; i
++)
3467 bpf_map_put(env
->used_maps
[i
]);
3470 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
3471 static void convert_pseudo_ld_imm64(struct bpf_verifier_env
*env
)
3473 struct bpf_insn
*insn
= env
->prog
->insnsi
;
3474 int insn_cnt
= env
->prog
->len
;
3477 for (i
= 0; i
< insn_cnt
; i
++, insn
++)
3478 if (insn
->code
== (BPF_LD
| BPF_IMM
| BPF_DW
))
3482 /* single env->prog->insni[off] instruction was replaced with the range
3483 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
3484 * [0, off) and [off, end) to new locations, so the patched range stays zero
3486 static int adjust_insn_aux_data(struct bpf_verifier_env
*env
, u32 prog_len
,
3489 struct bpf_insn_aux_data
*new_data
, *old_data
= env
->insn_aux_data
;
3493 new_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) * prog_len
);
3496 memcpy(new_data
, old_data
, sizeof(struct bpf_insn_aux_data
) * off
);
3497 memcpy(new_data
+ off
+ cnt
- 1, old_data
+ off
,
3498 sizeof(struct bpf_insn_aux_data
) * (prog_len
- off
- cnt
+ 1));
3499 env
->insn_aux_data
= new_data
;
3504 static struct bpf_prog
*bpf_patch_insn_data(struct bpf_verifier_env
*env
, u32 off
,
3505 const struct bpf_insn
*patch
, u32 len
)
3507 struct bpf_prog
*new_prog
;
3509 new_prog
= bpf_patch_insn_single(env
->prog
, off
, patch
, len
);
3512 if (adjust_insn_aux_data(env
, new_prog
->len
, off
, len
))
3517 /* convert load instructions that access fields of 'struct __sk_buff'
3518 * into sequence of instructions that access fields of 'struct sk_buff'
3520 static int convert_ctx_accesses(struct bpf_verifier_env
*env
)
3522 const struct bpf_verifier_ops
*ops
= env
->prog
->aux
->ops
;
3523 int i
, cnt
, size
, ctx_field_size
, delta
= 0;
3524 const int insn_cnt
= env
->prog
->len
;
3525 struct bpf_insn insn_buf
[16], *insn
;
3526 struct bpf_prog
*new_prog
;
3527 enum bpf_access_type type
;
3528 bool is_narrower_load
;
3531 if (ops
->gen_prologue
) {
3532 cnt
= ops
->gen_prologue(insn_buf
, env
->seen_direct_write
,
3534 if (cnt
>= ARRAY_SIZE(insn_buf
)) {
3535 verbose("bpf verifier is misconfigured\n");
3538 new_prog
= bpf_patch_insn_data(env
, 0, insn_buf
, cnt
);
3542 env
->prog
= new_prog
;
3547 if (!ops
->convert_ctx_access
)
3550 insn
= env
->prog
->insnsi
+ delta
;
3552 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
3553 if (insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_B
) ||
3554 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_H
) ||
3555 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_W
) ||
3556 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_DW
))
3558 else if (insn
->code
== (BPF_STX
| BPF_MEM
| BPF_B
) ||
3559 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_H
) ||
3560 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_W
) ||
3561 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_DW
))
3566 if (env
->insn_aux_data
[i
+ delta
].ptr_type
!= PTR_TO_CTX
)
3569 ctx_field_size
= env
->insn_aux_data
[i
+ delta
].ctx_field_size
;
3570 size
= BPF_LDST_BYTES(insn
);
3572 /* If the read access is a narrower load of the field,
3573 * convert to a 4/8-byte load, to minimum program type specific
3574 * convert_ctx_access changes. If conversion is successful,
3575 * we will apply proper mask to the result.
3577 is_narrower_load
= size
< ctx_field_size
;
3578 if (is_narrower_load
) {
3579 u32 off
= insn
->off
;
3582 if (type
== BPF_WRITE
) {
3583 verbose("bpf verifier narrow ctx access misconfigured\n");
3588 if (ctx_field_size
== 4)
3590 else if (ctx_field_size
== 8)
3593 insn
->off
= off
& ~(ctx_field_size
- 1);
3594 insn
->code
= BPF_LDX
| BPF_MEM
| size_code
;
3598 cnt
= ops
->convert_ctx_access(type
, insn
, insn_buf
, env
->prog
,
3600 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
) ||
3601 (ctx_field_size
&& !target_size
)) {
3602 verbose("bpf verifier is misconfigured\n");
3606 if (is_narrower_load
&& size
< target_size
) {
3607 if (ctx_field_size
<= 4)
3608 insn_buf
[cnt
++] = BPF_ALU32_IMM(BPF_AND
, insn
->dst_reg
,
3609 (1 << size
* 8) - 1);
3611 insn_buf
[cnt
++] = BPF_ALU64_IMM(BPF_AND
, insn
->dst_reg
,
3612 (1 << size
* 8) - 1);
3615 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
, cnt
);
3621 /* keep walking new program and skip insns we just inserted */
3622 env
->prog
= new_prog
;
3623 insn
= new_prog
->insnsi
+ i
+ delta
;
3629 /* fixup insn->imm field of bpf_call instructions
3630 * and inline eligible helpers as explicit sequence of BPF instructions
3632 * this function is called after eBPF program passed verification
3634 static int fixup_bpf_calls(struct bpf_verifier_env
*env
)
3636 struct bpf_prog
*prog
= env
->prog
;
3637 struct bpf_insn
*insn
= prog
->insnsi
;
3638 const struct bpf_func_proto
*fn
;
3639 const int insn_cnt
= prog
->len
;
3640 struct bpf_insn insn_buf
[16];
3641 struct bpf_prog
*new_prog
;
3642 struct bpf_map
*map_ptr
;
3643 int i
, cnt
, delta
= 0;
3645 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
3646 if (insn
->code
!= (BPF_JMP
| BPF_CALL
))
3649 if (insn
->imm
== BPF_FUNC_get_route_realm
)
3650 prog
->dst_needed
= 1;
3651 if (insn
->imm
== BPF_FUNC_get_prandom_u32
)
3652 bpf_user_rnd_init_once();
3653 if (insn
->imm
== BPF_FUNC_tail_call
) {
3654 /* If we tail call into other programs, we
3655 * cannot make any assumptions since they can
3656 * be replaced dynamically during runtime in
3657 * the program array.
3659 prog
->cb_access
= 1;
3660 env
->prog
->aux
->stack_depth
= MAX_BPF_STACK
;
3662 /* mark bpf_tail_call as different opcode to avoid
3663 * conditional branch in the interpeter for every normal
3664 * call and to prevent accidental JITing by JIT compiler
3665 * that doesn't support bpf_tail_call yet
3668 insn
->code
= BPF_JMP
| BPF_TAIL_CALL
;
3672 if (ebpf_jit_enabled() && insn
->imm
== BPF_FUNC_map_lookup_elem
) {
3673 map_ptr
= env
->insn_aux_data
[i
+ delta
].map_ptr
;
3674 if (map_ptr
== BPF_MAP_PTR_POISON
||
3675 !map_ptr
->ops
->map_gen_lookup
)
3676 goto patch_call_imm
;
3678 cnt
= map_ptr
->ops
->map_gen_lookup(map_ptr
, insn_buf
);
3679 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
)) {
3680 verbose("bpf verifier is misconfigured\n");
3684 new_prog
= bpf_patch_insn_data(env
, i
+ delta
, insn_buf
,
3691 /* keep walking new program and skip insns we just inserted */
3692 env
->prog
= prog
= new_prog
;
3693 insn
= new_prog
->insnsi
+ i
+ delta
;
3698 fn
= prog
->aux
->ops
->get_func_proto(insn
->imm
);
3699 /* all functions that have prototype and verifier allowed
3700 * programs to call them, must be real in-kernel functions
3703 verbose("kernel subsystem misconfigured func %s#%d\n",
3704 func_id_name(insn
->imm
), insn
->imm
);
3707 insn
->imm
= fn
->func
- __bpf_call_base
;
3713 static void free_states(struct bpf_verifier_env
*env
)
3715 struct bpf_verifier_state_list
*sl
, *sln
;
3718 if (!env
->explored_states
)
3721 for (i
= 0; i
< env
->prog
->len
; i
++) {
3722 sl
= env
->explored_states
[i
];
3725 while (sl
!= STATE_LIST_MARK
) {
3732 kfree(env
->explored_states
);
3735 int bpf_check(struct bpf_prog
**prog
, union bpf_attr
*attr
)
3737 char __user
*log_ubuf
= NULL
;
3738 struct bpf_verifier_env
*env
;
3741 /* 'struct bpf_verifier_env' can be global, but since it's not small,
3742 * allocate/free it every time bpf_check() is called
3744 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
3748 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
3751 if (!env
->insn_aux_data
)
3755 /* grab the mutex to protect few globals used by verifier */
3756 mutex_lock(&bpf_verifier_lock
);
3758 if (attr
->log_level
|| attr
->log_buf
|| attr
->log_size
) {
3759 /* user requested verbose verifier output
3760 * and supplied buffer to store the verification trace
3762 log_level
= attr
->log_level
;
3763 log_ubuf
= (char __user
*) (unsigned long) attr
->log_buf
;
3764 log_size
= attr
->log_size
;
3768 /* log_* values have to be sane */
3769 if (log_size
< 128 || log_size
> UINT_MAX
>> 8 ||
3770 log_level
== 0 || log_ubuf
== NULL
)
3774 log_buf
= vmalloc(log_size
);
3781 env
->strict_alignment
= !!(attr
->prog_flags
& BPF_F_STRICT_ALIGNMENT
);
3782 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
))
3783 env
->strict_alignment
= true;
3785 ret
= replace_map_fd_with_map_ptr(env
);
3787 goto skip_full_check
;
3789 env
->explored_states
= kcalloc(env
->prog
->len
,
3790 sizeof(struct bpf_verifier_state_list
*),
3793 if (!env
->explored_states
)
3794 goto skip_full_check
;
3796 ret
= check_cfg(env
);
3798 goto skip_full_check
;
3800 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
3802 ret
= do_check(env
);
3805 while (pop_stack(env
, NULL
) >= 0);
3809 /* program is valid, convert *(u32*)(ctx + off) accesses */
3810 ret
= convert_ctx_accesses(env
);
3813 ret
= fixup_bpf_calls(env
);
3815 if (log_level
&& log_len
>= log_size
- 1) {
3816 BUG_ON(log_len
>= log_size
);
3817 /* verifier log exceeded user supplied buffer */
3819 /* fall through to return what was recorded */
3822 /* copy verifier log back to user space including trailing zero */
3823 if (log_level
&& copy_to_user(log_ubuf
, log_buf
, log_len
+ 1) != 0) {
3828 if (ret
== 0 && env
->used_map_cnt
) {
3829 /* if program passed verifier, update used_maps in bpf_prog_info */
3830 env
->prog
->aux
->used_maps
= kmalloc_array(env
->used_map_cnt
,
3831 sizeof(env
->used_maps
[0]),
3834 if (!env
->prog
->aux
->used_maps
) {
3839 memcpy(env
->prog
->aux
->used_maps
, env
->used_maps
,
3840 sizeof(env
->used_maps
[0]) * env
->used_map_cnt
);
3841 env
->prog
->aux
->used_map_cnt
= env
->used_map_cnt
;
3843 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3844 * bpf_ld_imm64 instructions
3846 convert_pseudo_ld_imm64(env
);
3852 if (!env
->prog
->aux
->used_maps
)
3853 /* if we didn't copy map pointers into bpf_prog_info, release
3854 * them now. Otherwise free_bpf_prog_info() will release them.
3859 mutex_unlock(&bpf_verifier_lock
);
3860 vfree(env
->insn_aux_data
);
3866 int bpf_analyzer(struct bpf_prog
*prog
, const struct bpf_ext_analyzer_ops
*ops
,
3869 struct bpf_verifier_env
*env
;
3872 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
3876 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
3879 if (!env
->insn_aux_data
)
3882 env
->analyzer_ops
= ops
;
3883 env
->analyzer_priv
= priv
;
3885 /* grab the mutex to protect few globals used by verifier */
3886 mutex_lock(&bpf_verifier_lock
);
3890 env
->strict_alignment
= false;
3891 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
))
3892 env
->strict_alignment
= true;
3894 env
->explored_states
= kcalloc(env
->prog
->len
,
3895 sizeof(struct bpf_verifier_state_list
*),
3898 if (!env
->explored_states
)
3899 goto skip_full_check
;
3901 ret
= check_cfg(env
);
3903 goto skip_full_check
;
3905 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
3907 ret
= do_check(env
);
3910 while (pop_stack(env
, NULL
) >= 0);
3913 mutex_unlock(&bpf_verifier_lock
);
3914 vfree(env
->insn_aux_data
);
3919 EXPORT_SYMBOL_GPL(bpf_analyzer
);