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 65536
144 #define BPF_COMPLEXITY_LIMIT_STACK 1024
146 struct bpf_call_arg_meta
{
147 struct bpf_map
*map_ptr
;
154 /* verbose verifier prints what it's seeing
155 * bpf_check() is called under lock, so no race to access these global vars
157 static u32 log_level
, log_size
, log_len
;
158 static char *log_buf
;
160 static DEFINE_MUTEX(bpf_verifier_lock
);
162 /* log_level controls verbosity level of eBPF verifier.
163 * verbose() is used to dump the verification trace to the log, so the user
164 * can figure out what's wrong with the program
166 static __printf(1, 2) void verbose(const char *fmt
, ...)
170 if (log_level
== 0 || log_len
>= log_size
- 1)
174 log_len
+= vscnprintf(log_buf
+ log_len
, log_size
- log_len
, fmt
, args
);
178 /* string representation of 'enum bpf_reg_type' */
179 static const char * const reg_type_str
[] = {
181 [UNKNOWN_VALUE
] = "inv",
182 [PTR_TO_CTX
] = "ctx",
183 [CONST_PTR_TO_MAP
] = "map_ptr",
184 [PTR_TO_MAP_VALUE
] = "map_value",
185 [PTR_TO_MAP_VALUE_OR_NULL
] = "map_value_or_null",
186 [PTR_TO_MAP_VALUE_ADJ
] = "map_value_adj",
188 [PTR_TO_STACK
] = "fp",
190 [PTR_TO_PACKET
] = "pkt",
191 [PTR_TO_PACKET_END
] = "pkt_end",
194 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
195 static const char * const func_id_str
[] = {
196 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN
)
198 #undef __BPF_FUNC_STR_FN
200 static const char *func_id_name(int id
)
202 BUILD_BUG_ON(ARRAY_SIZE(func_id_str
) != __BPF_FUNC_MAX_ID
);
204 if (id
>= 0 && id
< __BPF_FUNC_MAX_ID
&& func_id_str
[id
])
205 return func_id_str
[id
];
210 static void print_verifier_state(struct bpf_verifier_state
*state
)
212 struct bpf_reg_state
*reg
;
216 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
217 reg
= &state
->regs
[i
];
221 verbose(" R%d=%s", i
, reg_type_str
[t
]);
222 if (t
== CONST_IMM
|| t
== PTR_TO_STACK
)
223 verbose("%lld", reg
->imm
);
224 else if (t
== PTR_TO_PACKET
)
225 verbose("(id=%d,off=%d,r=%d)",
226 reg
->id
, reg
->off
, reg
->range
);
227 else if (t
== UNKNOWN_VALUE
&& reg
->imm
)
228 verbose("%lld", reg
->imm
);
229 else if (t
== CONST_PTR_TO_MAP
|| t
== PTR_TO_MAP_VALUE
||
230 t
== PTR_TO_MAP_VALUE_OR_NULL
||
231 t
== PTR_TO_MAP_VALUE_ADJ
)
232 verbose("(ks=%d,vs=%d,id=%u)",
233 reg
->map_ptr
->key_size
,
234 reg
->map_ptr
->value_size
,
236 if (reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
237 verbose(",min_value=%lld",
238 (long long)reg
->min_value
);
239 if (reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
240 verbose(",max_value=%llu",
241 (unsigned long long)reg
->max_value
);
243 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
244 if (state
->stack_slot_type
[i
] == STACK_SPILL
)
245 verbose(" fp%d=%s", -MAX_BPF_STACK
+ i
,
246 reg_type_str
[state
->spilled_regs
[i
/ BPF_REG_SIZE
].type
]);
251 static const char *const bpf_class_string
[] = {
259 [BPF_ALU64
] = "alu64",
262 static const char *const bpf_alu_string
[16] = {
263 [BPF_ADD
>> 4] = "+=",
264 [BPF_SUB
>> 4] = "-=",
265 [BPF_MUL
>> 4] = "*=",
266 [BPF_DIV
>> 4] = "/=",
267 [BPF_OR
>> 4] = "|=",
268 [BPF_AND
>> 4] = "&=",
269 [BPF_LSH
>> 4] = "<<=",
270 [BPF_RSH
>> 4] = ">>=",
271 [BPF_NEG
>> 4] = "neg",
272 [BPF_MOD
>> 4] = "%=",
273 [BPF_XOR
>> 4] = "^=",
274 [BPF_MOV
>> 4] = "=",
275 [BPF_ARSH
>> 4] = "s>>=",
276 [BPF_END
>> 4] = "endian",
279 static const char *const bpf_ldst_string
[] = {
280 [BPF_W
>> 3] = "u32",
281 [BPF_H
>> 3] = "u16",
283 [BPF_DW
>> 3] = "u64",
286 static const char *const bpf_jmp_string
[16] = {
287 [BPF_JA
>> 4] = "jmp",
288 [BPF_JEQ
>> 4] = "==",
289 [BPF_JGT
>> 4] = ">",
290 [BPF_JGE
>> 4] = ">=",
291 [BPF_JSET
>> 4] = "&",
292 [BPF_JNE
>> 4] = "!=",
293 [BPF_JSGT
>> 4] = "s>",
294 [BPF_JSGE
>> 4] = "s>=",
295 [BPF_CALL
>> 4] = "call",
296 [BPF_EXIT
>> 4] = "exit",
299 static void print_bpf_insn(struct bpf_insn
*insn
)
301 u8
class = BPF_CLASS(insn
->code
);
303 if (class == BPF_ALU
|| class == BPF_ALU64
) {
304 if (BPF_SRC(insn
->code
) == BPF_X
)
305 verbose("(%02x) %sr%d %s %sr%d\n",
306 insn
->code
, class == BPF_ALU
? "(u32) " : "",
308 bpf_alu_string
[BPF_OP(insn
->code
) >> 4],
309 class == BPF_ALU
? "(u32) " : "",
312 verbose("(%02x) %sr%d %s %s%d\n",
313 insn
->code
, class == BPF_ALU
? "(u32) " : "",
315 bpf_alu_string
[BPF_OP(insn
->code
) >> 4],
316 class == BPF_ALU
? "(u32) " : "",
318 } else if (class == BPF_STX
) {
319 if (BPF_MODE(insn
->code
) == BPF_MEM
)
320 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
322 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
324 insn
->off
, insn
->src_reg
);
325 else if (BPF_MODE(insn
->code
) == BPF_XADD
)
326 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
328 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
329 insn
->dst_reg
, insn
->off
,
332 verbose("BUG_%02x\n", insn
->code
);
333 } else if (class == BPF_ST
) {
334 if (BPF_MODE(insn
->code
) != BPF_MEM
) {
335 verbose("BUG_st_%02x\n", insn
->code
);
338 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
340 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
342 insn
->off
, insn
->imm
);
343 } else if (class == BPF_LDX
) {
344 if (BPF_MODE(insn
->code
) != BPF_MEM
) {
345 verbose("BUG_ldx_%02x\n", insn
->code
);
348 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
349 insn
->code
, insn
->dst_reg
,
350 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
351 insn
->src_reg
, insn
->off
);
352 } else if (class == BPF_LD
) {
353 if (BPF_MODE(insn
->code
) == BPF_ABS
) {
354 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
356 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
358 } else if (BPF_MODE(insn
->code
) == BPF_IND
) {
359 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
361 bpf_ldst_string
[BPF_SIZE(insn
->code
) >> 3],
362 insn
->src_reg
, insn
->imm
);
363 } else if (BPF_MODE(insn
->code
) == BPF_IMM
) {
364 verbose("(%02x) r%d = 0x%x\n",
365 insn
->code
, insn
->dst_reg
, insn
->imm
);
367 verbose("BUG_ld_%02x\n", insn
->code
);
370 } else if (class == BPF_JMP
) {
371 u8 opcode
= BPF_OP(insn
->code
);
373 if (opcode
== BPF_CALL
) {
374 verbose("(%02x) call %s#%d\n", insn
->code
,
375 func_id_name(insn
->imm
), insn
->imm
);
376 } else if (insn
->code
== (BPF_JMP
| BPF_JA
)) {
377 verbose("(%02x) goto pc%+d\n",
378 insn
->code
, insn
->off
);
379 } else if (insn
->code
== (BPF_JMP
| BPF_EXIT
)) {
380 verbose("(%02x) exit\n", insn
->code
);
381 } else if (BPF_SRC(insn
->code
) == BPF_X
) {
382 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
383 insn
->code
, insn
->dst_reg
,
384 bpf_jmp_string
[BPF_OP(insn
->code
) >> 4],
385 insn
->src_reg
, insn
->off
);
387 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
388 insn
->code
, insn
->dst_reg
,
389 bpf_jmp_string
[BPF_OP(insn
->code
) >> 4],
390 insn
->imm
, insn
->off
);
393 verbose("(%02x) %s\n", insn
->code
, bpf_class_string
[class]);
397 static int pop_stack(struct bpf_verifier_env
*env
, int *prev_insn_idx
)
399 struct bpf_verifier_stack_elem
*elem
;
402 if (env
->head
== NULL
)
405 memcpy(&env
->cur_state
, &env
->head
->st
, sizeof(env
->cur_state
));
406 insn_idx
= env
->head
->insn_idx
;
408 *prev_insn_idx
= env
->head
->prev_insn_idx
;
409 elem
= env
->head
->next
;
416 static struct bpf_verifier_state
*push_stack(struct bpf_verifier_env
*env
,
417 int insn_idx
, int prev_insn_idx
)
419 struct bpf_verifier_stack_elem
*elem
;
421 elem
= kmalloc(sizeof(struct bpf_verifier_stack_elem
), GFP_KERNEL
);
425 memcpy(&elem
->st
, &env
->cur_state
, sizeof(env
->cur_state
));
426 elem
->insn_idx
= insn_idx
;
427 elem
->prev_insn_idx
= prev_insn_idx
;
428 elem
->next
= env
->head
;
431 if (env
->stack_size
> BPF_COMPLEXITY_LIMIT_STACK
) {
432 verbose("BPF program is too complex\n");
437 /* pop all elements and return */
438 while (pop_stack(env
, NULL
) >= 0);
442 #define CALLER_SAVED_REGS 6
443 static const int caller_saved
[CALLER_SAVED_REGS
] = {
444 BPF_REG_0
, BPF_REG_1
, BPF_REG_2
, BPF_REG_3
, BPF_REG_4
, BPF_REG_5
447 static void init_reg_state(struct bpf_reg_state
*regs
)
451 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
452 regs
[i
].type
= NOT_INIT
;
454 regs
[i
].min_value
= BPF_REGISTER_MIN_RANGE
;
455 regs
[i
].max_value
= BPF_REGISTER_MAX_RANGE
;
459 regs
[BPF_REG_FP
].type
= FRAME_PTR
;
461 /* 1st arg to a function */
462 regs
[BPF_REG_1
].type
= PTR_TO_CTX
;
465 static void __mark_reg_unknown_value(struct bpf_reg_state
*regs
, u32 regno
)
467 regs
[regno
].type
= UNKNOWN_VALUE
;
472 static void mark_reg_unknown_value(struct bpf_reg_state
*regs
, u32 regno
)
474 BUG_ON(regno
>= MAX_BPF_REG
);
475 __mark_reg_unknown_value(regs
, regno
);
478 static void reset_reg_range_values(struct bpf_reg_state
*regs
, u32 regno
)
480 regs
[regno
].min_value
= BPF_REGISTER_MIN_RANGE
;
481 regs
[regno
].max_value
= BPF_REGISTER_MAX_RANGE
;
484 static void mark_reg_unknown_value_and_range(struct bpf_reg_state
*regs
,
487 mark_reg_unknown_value(regs
, regno
);
488 reset_reg_range_values(regs
, regno
);
492 SRC_OP
, /* register is used as source operand */
493 DST_OP
, /* register is used as destination operand */
494 DST_OP_NO_MARK
/* same as above, check only, don't mark */
497 static int check_reg_arg(struct bpf_reg_state
*regs
, u32 regno
,
500 if (regno
>= MAX_BPF_REG
) {
501 verbose("R%d is invalid\n", regno
);
506 /* check whether register used as source operand can be read */
507 if (regs
[regno
].type
== NOT_INIT
) {
508 verbose("R%d !read_ok\n", regno
);
512 /* check whether register used as dest operand can be written to */
513 if (regno
== BPF_REG_FP
) {
514 verbose("frame pointer is read only\n");
518 mark_reg_unknown_value(regs
, regno
);
523 static int bpf_size_to_bytes(int bpf_size
)
525 if (bpf_size
== BPF_W
)
527 else if (bpf_size
== BPF_H
)
529 else if (bpf_size
== BPF_B
)
531 else if (bpf_size
== BPF_DW
)
537 static bool is_spillable_regtype(enum bpf_reg_type type
)
540 case PTR_TO_MAP_VALUE
:
541 case PTR_TO_MAP_VALUE_OR_NULL
:
542 case PTR_TO_MAP_VALUE_ADJ
:
546 case PTR_TO_PACKET_END
:
548 case CONST_PTR_TO_MAP
:
555 /* check_stack_read/write functions track spill/fill of registers,
556 * stack boundary and alignment are checked in check_mem_access()
558 static int check_stack_write(struct bpf_verifier_state
*state
, int off
,
559 int size
, int value_regno
)
562 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
563 * so it's aligned access and [off, off + size) are within stack limits
566 if (value_regno
>= 0 &&
567 is_spillable_regtype(state
->regs
[value_regno
].type
)) {
569 /* register containing pointer is being spilled into stack */
570 if (size
!= BPF_REG_SIZE
) {
571 verbose("invalid size of register spill\n");
575 /* save register state */
576 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
] =
577 state
->regs
[value_regno
];
579 for (i
= 0; i
< BPF_REG_SIZE
; i
++)
580 state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] = STACK_SPILL
;
582 /* regular write of data into stack */
583 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
] =
584 (struct bpf_reg_state
) {};
586 for (i
= 0; i
< size
; i
++)
587 state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] = STACK_MISC
;
592 static int check_stack_read(struct bpf_verifier_state
*state
, int off
, int size
,
598 slot_type
= &state
->stack_slot_type
[MAX_BPF_STACK
+ off
];
600 if (slot_type
[0] == STACK_SPILL
) {
601 if (size
!= BPF_REG_SIZE
) {
602 verbose("invalid size of register spill\n");
605 for (i
= 1; i
< BPF_REG_SIZE
; i
++) {
606 if (slot_type
[i
] != STACK_SPILL
) {
607 verbose("corrupted spill memory\n");
612 if (value_regno
>= 0)
613 /* restore register state from stack */
614 state
->regs
[value_regno
] =
615 state
->spilled_regs
[(MAX_BPF_STACK
+ off
) / BPF_REG_SIZE
];
618 for (i
= 0; i
< size
; i
++) {
619 if (slot_type
[i
] != STACK_MISC
) {
620 verbose("invalid read from stack off %d+%d size %d\n",
625 if (value_regno
>= 0)
626 /* have read misc data from the stack */
627 mark_reg_unknown_value_and_range(state
->regs
,
633 /* check read/write into map element returned by bpf_map_lookup_elem() */
634 static int check_map_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
637 struct bpf_map
*map
= env
->cur_state
.regs
[regno
].map_ptr
;
639 if (off
< 0 || size
<= 0 || off
+ size
> map
->value_size
) {
640 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
641 map
->value_size
, off
, size
);
647 /* check read/write into an adjusted map element */
648 static int check_map_access_adj(struct bpf_verifier_env
*env
, u32 regno
,
651 struct bpf_verifier_state
*state
= &env
->cur_state
;
652 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
655 /* We adjusted the register to this map value, so we
656 * need to change off and size to min_value and max_value
657 * respectively to make sure our theoretical access will be
661 print_verifier_state(state
);
662 env
->varlen_map_value_access
= true;
663 /* The minimum value is only important with signed
664 * comparisons where we can't assume the floor of a
665 * value is 0. If we are using signed variables for our
666 * index'es we need to make sure that whatever we use
667 * will have a set floor within our range.
669 if (reg
->min_value
< 0) {
670 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
674 err
= check_map_access(env
, regno
, reg
->min_value
+ off
, size
);
676 verbose("R%d min value is outside of the array range\n",
681 /* If we haven't set a max value then we need to bail
682 * since we can't be sure we won't do bad things.
684 if (reg
->max_value
== BPF_REGISTER_MAX_RANGE
) {
685 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
689 return check_map_access(env
, regno
, reg
->max_value
+ off
, size
);
692 #define MAX_PACKET_OFF 0xffff
694 static bool may_access_direct_pkt_data(struct bpf_verifier_env
*env
,
695 const struct bpf_call_arg_meta
*meta
,
696 enum bpf_access_type t
)
698 switch (env
->prog
->type
) {
699 case BPF_PROG_TYPE_LWT_IN
:
700 case BPF_PROG_TYPE_LWT_OUT
:
701 /* dst_input() and dst_output() can't write for now */
705 case BPF_PROG_TYPE_SCHED_CLS
:
706 case BPF_PROG_TYPE_SCHED_ACT
:
707 case BPF_PROG_TYPE_XDP
:
708 case BPF_PROG_TYPE_LWT_XMIT
:
710 return meta
->pkt_access
;
712 env
->seen_direct_write
= true;
719 static int check_packet_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
722 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
723 struct bpf_reg_state
*reg
= ®s
[regno
];
726 if (off
< 0 || size
<= 0 || off
+ size
> reg
->range
) {
727 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
728 off
, size
, regno
, reg
->id
, reg
->off
, reg
->range
);
734 /* check access to 'struct bpf_context' fields */
735 static int check_ctx_access(struct bpf_verifier_env
*env
, int off
, int size
,
736 enum bpf_access_type t
, enum bpf_reg_type
*reg_type
)
738 /* for analyzer ctx accesses are already validated and converted */
739 if (env
->analyzer_ops
)
742 if (env
->prog
->aux
->ops
->is_valid_access
&&
743 env
->prog
->aux
->ops
->is_valid_access(off
, size
, t
, reg_type
)) {
744 /* remember the offset of last byte accessed in ctx */
745 if (env
->prog
->aux
->max_ctx_offset
< off
+ size
)
746 env
->prog
->aux
->max_ctx_offset
= off
+ size
;
750 verbose("invalid bpf_context access off=%d size=%d\n", off
, size
);
754 static bool is_pointer_value(struct bpf_verifier_env
*env
, int regno
)
756 if (env
->allow_ptr_leaks
)
759 switch (env
->cur_state
.regs
[regno
].type
) {
768 static int check_pkt_ptr_alignment(const struct bpf_reg_state
*reg
,
771 if (reg
->id
&& size
!= 1) {
772 verbose("Unknown alignment. Only byte-sized access allowed in packet access.\n");
776 /* skb->data is NET_IP_ALIGN-ed */
777 if ((NET_IP_ALIGN
+ reg
->off
+ off
) % size
!= 0) {
778 verbose("misaligned packet access off %d+%d+%d size %d\n",
779 NET_IP_ALIGN
, reg
->off
, off
, size
);
786 static int check_val_ptr_alignment(const struct bpf_reg_state
*reg
,
790 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n");
797 static int check_ptr_alignment(const struct bpf_reg_state
*reg
,
802 return IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
) ? 0 :
803 check_pkt_ptr_alignment(reg
, off
, size
);
804 case PTR_TO_MAP_VALUE_ADJ
:
805 return IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
) ? 0 :
806 check_val_ptr_alignment(reg
, size
);
808 if (off
% size
!= 0) {
809 verbose("misaligned access off %d size %d\n",
818 /* check whether memory at (regno + off) is accessible for t = (read | write)
819 * if t==write, value_regno is a register which value is stored into memory
820 * if t==read, value_regno is a register which will receive the value from memory
821 * if t==write && value_regno==-1, some unknown value is stored into memory
822 * if t==read && value_regno==-1, don't care what we read from memory
824 static int check_mem_access(struct bpf_verifier_env
*env
, u32 regno
, int off
,
825 int bpf_size
, enum bpf_access_type t
,
828 struct bpf_verifier_state
*state
= &env
->cur_state
;
829 struct bpf_reg_state
*reg
= &state
->regs
[regno
];
832 if (reg
->type
== PTR_TO_STACK
)
835 size
= bpf_size_to_bytes(bpf_size
);
839 err
= check_ptr_alignment(reg
, off
, size
);
843 if (reg
->type
== PTR_TO_MAP_VALUE
||
844 reg
->type
== PTR_TO_MAP_VALUE_ADJ
) {
845 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
846 is_pointer_value(env
, value_regno
)) {
847 verbose("R%d leaks addr into map\n", value_regno
);
851 if (reg
->type
== PTR_TO_MAP_VALUE_ADJ
)
852 err
= check_map_access_adj(env
, regno
, off
, size
);
854 err
= check_map_access(env
, regno
, off
, size
);
855 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
856 mark_reg_unknown_value_and_range(state
->regs
,
859 } else if (reg
->type
== PTR_TO_CTX
) {
860 enum bpf_reg_type reg_type
= UNKNOWN_VALUE
;
862 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
863 is_pointer_value(env
, value_regno
)) {
864 verbose("R%d leaks addr into ctx\n", value_regno
);
867 err
= check_ctx_access(env
, off
, size
, t
, ®_type
);
868 if (!err
&& t
== BPF_READ
&& value_regno
>= 0) {
869 mark_reg_unknown_value_and_range(state
->regs
,
871 /* note that reg.[id|off|range] == 0 */
872 state
->regs
[value_regno
].type
= reg_type
;
875 } else if (reg
->type
== FRAME_PTR
|| reg
->type
== PTR_TO_STACK
) {
876 if (off
>= 0 || off
< -MAX_BPF_STACK
) {
877 verbose("invalid stack off=%d size=%d\n", off
, size
);
880 if (t
== BPF_WRITE
) {
881 if (!env
->allow_ptr_leaks
&&
882 state
->stack_slot_type
[MAX_BPF_STACK
+ off
] == STACK_SPILL
&&
883 size
!= BPF_REG_SIZE
) {
884 verbose("attempt to corrupt spilled pointer on stack\n");
887 err
= check_stack_write(state
, off
, size
, value_regno
);
889 err
= check_stack_read(state
, off
, size
, value_regno
);
891 } else if (state
->regs
[regno
].type
== PTR_TO_PACKET
) {
892 if (t
== BPF_WRITE
&& !may_access_direct_pkt_data(env
, NULL
, t
)) {
893 verbose("cannot write into packet\n");
896 if (t
== BPF_WRITE
&& value_regno
>= 0 &&
897 is_pointer_value(env
, value_regno
)) {
898 verbose("R%d leaks addr into packet\n", value_regno
);
901 err
= check_packet_access(env
, regno
, off
, size
);
902 if (!err
&& t
== BPF_READ
&& value_regno
>= 0)
903 mark_reg_unknown_value_and_range(state
->regs
,
906 verbose("R%d invalid mem access '%s'\n",
907 regno
, reg_type_str
[reg
->type
]);
911 if (!err
&& size
<= 2 && value_regno
>= 0 && env
->allow_ptr_leaks
&&
912 state
->regs
[value_regno
].type
== UNKNOWN_VALUE
) {
913 /* 1 or 2 byte load zero-extends, determine the number of
914 * zero upper bits. Not doing it fo 4 byte load, since
915 * such values cannot be added to ptr_to_packet anyway.
917 state
->regs
[value_regno
].imm
= 64 - size
* 8;
922 static int check_xadd(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
924 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
927 if ((BPF_SIZE(insn
->code
) != BPF_W
&& BPF_SIZE(insn
->code
) != BPF_DW
) ||
929 verbose("BPF_XADD uses reserved fields\n");
933 /* check src1 operand */
934 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
938 /* check src2 operand */
939 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
943 /* check whether atomic_add can read the memory */
944 err
= check_mem_access(env
, insn
->dst_reg
, insn
->off
,
945 BPF_SIZE(insn
->code
), BPF_READ
, -1);
949 /* check whether atomic_add can write into the same memory */
950 return check_mem_access(env
, insn
->dst_reg
, insn
->off
,
951 BPF_SIZE(insn
->code
), BPF_WRITE
, -1);
954 /* when register 'regno' is passed into function that will read 'access_size'
955 * bytes from that pointer, make sure that it's within stack boundary
956 * and all elements of stack are initialized
958 static int check_stack_boundary(struct bpf_verifier_env
*env
, int regno
,
959 int access_size
, bool zero_size_allowed
,
960 struct bpf_call_arg_meta
*meta
)
962 struct bpf_verifier_state
*state
= &env
->cur_state
;
963 struct bpf_reg_state
*regs
= state
->regs
;
966 if (regs
[regno
].type
!= PTR_TO_STACK
) {
967 if (zero_size_allowed
&& access_size
== 0 &&
968 regs
[regno
].type
== CONST_IMM
&&
969 regs
[regno
].imm
== 0)
972 verbose("R%d type=%s expected=%s\n", regno
,
973 reg_type_str
[regs
[regno
].type
],
974 reg_type_str
[PTR_TO_STACK
]);
978 off
= regs
[regno
].imm
;
979 if (off
>= 0 || off
< -MAX_BPF_STACK
|| off
+ access_size
> 0 ||
981 verbose("invalid stack type R%d off=%d access_size=%d\n",
982 regno
, off
, access_size
);
986 if (meta
&& meta
->raw_mode
) {
987 meta
->access_size
= access_size
;
992 for (i
= 0; i
< access_size
; i
++) {
993 if (state
->stack_slot_type
[MAX_BPF_STACK
+ off
+ i
] != STACK_MISC
) {
994 verbose("invalid indirect read from stack off %d+%d size %d\n",
995 off
, i
, access_size
);
1002 static int check_helper_mem_access(struct bpf_verifier_env
*env
, int regno
,
1003 int access_size
, bool zero_size_allowed
,
1004 struct bpf_call_arg_meta
*meta
)
1006 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1008 switch (regs
[regno
].type
) {
1010 return check_packet_access(env
, regno
, 0, access_size
);
1011 case PTR_TO_MAP_VALUE
:
1012 return check_map_access(env
, regno
, 0, access_size
);
1013 case PTR_TO_MAP_VALUE_ADJ
:
1014 return check_map_access_adj(env
, regno
, 0, access_size
);
1015 default: /* const_imm|ptr_to_stack or invalid ptr */
1016 return check_stack_boundary(env
, regno
, access_size
,
1017 zero_size_allowed
, meta
);
1021 static int check_func_arg(struct bpf_verifier_env
*env
, u32 regno
,
1022 enum bpf_arg_type arg_type
,
1023 struct bpf_call_arg_meta
*meta
)
1025 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *reg
= ®s
[regno
];
1026 enum bpf_reg_type expected_type
, type
= reg
->type
;
1029 if (arg_type
== ARG_DONTCARE
)
1032 if (type
== NOT_INIT
) {
1033 verbose("R%d !read_ok\n", regno
);
1037 if (arg_type
== ARG_ANYTHING
) {
1038 if (is_pointer_value(env
, regno
)) {
1039 verbose("R%d leaks addr into helper function\n", regno
);
1045 if (type
== PTR_TO_PACKET
&&
1046 !may_access_direct_pkt_data(env
, meta
, BPF_READ
)) {
1047 verbose("helper access to the packet is not allowed\n");
1051 if (arg_type
== ARG_PTR_TO_MAP_KEY
||
1052 arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1053 expected_type
= PTR_TO_STACK
;
1054 if (type
!= PTR_TO_PACKET
&& type
!= expected_type
)
1056 } else if (arg_type
== ARG_CONST_SIZE
||
1057 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1058 expected_type
= CONST_IMM
;
1059 /* One exception. Allow UNKNOWN_VALUE registers when the
1060 * boundaries are known and don't cause unsafe memory accesses
1062 if (type
!= UNKNOWN_VALUE
&& type
!= expected_type
)
1064 } else if (arg_type
== ARG_CONST_MAP_PTR
) {
1065 expected_type
= CONST_PTR_TO_MAP
;
1066 if (type
!= expected_type
)
1068 } else if (arg_type
== ARG_PTR_TO_CTX
) {
1069 expected_type
= PTR_TO_CTX
;
1070 if (type
!= expected_type
)
1072 } else if (arg_type
== ARG_PTR_TO_MEM
||
1073 arg_type
== ARG_PTR_TO_UNINIT_MEM
) {
1074 expected_type
= PTR_TO_STACK
;
1075 /* One exception here. In case function allows for NULL to be
1076 * passed in as argument, it's a CONST_IMM type. Final test
1077 * happens during stack boundary checking.
1079 if (type
== CONST_IMM
&& reg
->imm
== 0)
1080 /* final test in check_stack_boundary() */;
1081 else if (type
!= PTR_TO_PACKET
&& type
!= PTR_TO_MAP_VALUE
&&
1082 type
!= PTR_TO_MAP_VALUE_ADJ
&& type
!= expected_type
)
1084 meta
->raw_mode
= arg_type
== ARG_PTR_TO_UNINIT_MEM
;
1086 verbose("unsupported arg_type %d\n", arg_type
);
1090 if (arg_type
== ARG_CONST_MAP_PTR
) {
1091 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1092 meta
->map_ptr
= reg
->map_ptr
;
1093 } else if (arg_type
== ARG_PTR_TO_MAP_KEY
) {
1094 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1095 * check that [key, key + map->key_size) are within
1096 * stack limits and initialized
1098 if (!meta
->map_ptr
) {
1099 /* in function declaration map_ptr must come before
1100 * map_key, so that it's verified and known before
1101 * we have to check map_key here. Otherwise it means
1102 * that kernel subsystem misconfigured verifier
1104 verbose("invalid map_ptr to access map->key\n");
1107 if (type
== PTR_TO_PACKET
)
1108 err
= check_packet_access(env
, regno
, 0,
1109 meta
->map_ptr
->key_size
);
1111 err
= check_stack_boundary(env
, regno
,
1112 meta
->map_ptr
->key_size
,
1114 } else if (arg_type
== ARG_PTR_TO_MAP_VALUE
) {
1115 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1116 * check [value, value + map->value_size) validity
1118 if (!meta
->map_ptr
) {
1119 /* kernel subsystem misconfigured verifier */
1120 verbose("invalid map_ptr to access map->value\n");
1123 if (type
== PTR_TO_PACKET
)
1124 err
= check_packet_access(env
, regno
, 0,
1125 meta
->map_ptr
->value_size
);
1127 err
= check_stack_boundary(env
, regno
,
1128 meta
->map_ptr
->value_size
,
1130 } else if (arg_type
== ARG_CONST_SIZE
||
1131 arg_type
== ARG_CONST_SIZE_OR_ZERO
) {
1132 bool zero_size_allowed
= (arg_type
== ARG_CONST_SIZE_OR_ZERO
);
1134 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1135 * from stack pointer 'buf'. Check it
1136 * note: regno == len, regno - 1 == buf
1139 /* kernel subsystem misconfigured verifier */
1140 verbose("ARG_CONST_SIZE cannot be first argument\n");
1144 /* If the register is UNKNOWN_VALUE, the access check happens
1145 * using its boundaries. Otherwise, just use its imm
1147 if (type
== UNKNOWN_VALUE
) {
1148 /* For unprivileged variable accesses, disable raw
1149 * mode so that the program is required to
1150 * initialize all the memory that the helper could
1151 * just partially fill up.
1155 if (reg
->min_value
< 0) {
1156 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n",
1161 if (reg
->min_value
== 0) {
1162 err
= check_helper_mem_access(env
, regno
- 1, 0,
1169 if (reg
->max_value
== BPF_REGISTER_MAX_RANGE
) {
1170 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
1174 err
= check_helper_mem_access(env
, regno
- 1,
1176 zero_size_allowed
, meta
);
1180 /* register is CONST_IMM */
1181 err
= check_helper_mem_access(env
, regno
- 1, reg
->imm
,
1182 zero_size_allowed
, meta
);
1188 verbose("R%d type=%s expected=%s\n", regno
,
1189 reg_type_str
[type
], reg_type_str
[expected_type
]);
1193 static int check_map_func_compatibility(struct bpf_map
*map
, int func_id
)
1198 /* We need a two way check, first is from map perspective ... */
1199 switch (map
->map_type
) {
1200 case BPF_MAP_TYPE_PROG_ARRAY
:
1201 if (func_id
!= BPF_FUNC_tail_call
)
1204 case BPF_MAP_TYPE_PERF_EVENT_ARRAY
:
1205 if (func_id
!= BPF_FUNC_perf_event_read
&&
1206 func_id
!= BPF_FUNC_perf_event_output
)
1209 case BPF_MAP_TYPE_STACK_TRACE
:
1210 if (func_id
!= BPF_FUNC_get_stackid
)
1213 case BPF_MAP_TYPE_CGROUP_ARRAY
:
1214 if (func_id
!= BPF_FUNC_skb_under_cgroup
&&
1215 func_id
!= BPF_FUNC_current_task_under_cgroup
)
1222 /* ... and second from the function itself. */
1224 case BPF_FUNC_tail_call
:
1225 if (map
->map_type
!= BPF_MAP_TYPE_PROG_ARRAY
)
1228 case BPF_FUNC_perf_event_read
:
1229 case BPF_FUNC_perf_event_output
:
1230 if (map
->map_type
!= BPF_MAP_TYPE_PERF_EVENT_ARRAY
)
1233 case BPF_FUNC_get_stackid
:
1234 if (map
->map_type
!= BPF_MAP_TYPE_STACK_TRACE
)
1237 case BPF_FUNC_current_task_under_cgroup
:
1238 case BPF_FUNC_skb_under_cgroup
:
1239 if (map
->map_type
!= BPF_MAP_TYPE_CGROUP_ARRAY
)
1248 verbose("cannot pass map_type %d into func %s#%d\n",
1249 map
->map_type
, func_id_name(func_id
), func_id
);
1253 static int check_raw_mode(const struct bpf_func_proto
*fn
)
1257 if (fn
->arg1_type
== ARG_PTR_TO_UNINIT_MEM
)
1259 if (fn
->arg2_type
== ARG_PTR_TO_UNINIT_MEM
)
1261 if (fn
->arg3_type
== ARG_PTR_TO_UNINIT_MEM
)
1263 if (fn
->arg4_type
== ARG_PTR_TO_UNINIT_MEM
)
1265 if (fn
->arg5_type
== ARG_PTR_TO_UNINIT_MEM
)
1268 return count
> 1 ? -EINVAL
: 0;
1271 static void clear_all_pkt_pointers(struct bpf_verifier_env
*env
)
1273 struct bpf_verifier_state
*state
= &env
->cur_state
;
1274 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
1277 for (i
= 0; i
< MAX_BPF_REG
; i
++)
1278 if (regs
[i
].type
== PTR_TO_PACKET
||
1279 regs
[i
].type
== PTR_TO_PACKET_END
)
1280 mark_reg_unknown_value(regs
, i
);
1282 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
1283 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
1285 reg
= &state
->spilled_regs
[i
/ BPF_REG_SIZE
];
1286 if (reg
->type
!= PTR_TO_PACKET
&&
1287 reg
->type
!= PTR_TO_PACKET_END
)
1289 reg
->type
= UNKNOWN_VALUE
;
1294 static int check_call(struct bpf_verifier_env
*env
, int func_id
)
1296 struct bpf_verifier_state
*state
= &env
->cur_state
;
1297 const struct bpf_func_proto
*fn
= NULL
;
1298 struct bpf_reg_state
*regs
= state
->regs
;
1299 struct bpf_reg_state
*reg
;
1300 struct bpf_call_arg_meta meta
;
1304 /* find function prototype */
1305 if (func_id
< 0 || func_id
>= __BPF_FUNC_MAX_ID
) {
1306 verbose("invalid func %s#%d\n", func_id_name(func_id
), func_id
);
1310 if (env
->prog
->aux
->ops
->get_func_proto
)
1311 fn
= env
->prog
->aux
->ops
->get_func_proto(func_id
);
1314 verbose("unknown func %s#%d\n", func_id_name(func_id
), func_id
);
1318 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1319 if (!env
->prog
->gpl_compatible
&& fn
->gpl_only
) {
1320 verbose("cannot call GPL only function from proprietary program\n");
1324 changes_data
= bpf_helper_changes_pkt_data(fn
->func
);
1326 memset(&meta
, 0, sizeof(meta
));
1327 meta
.pkt_access
= fn
->pkt_access
;
1329 /* We only support one arg being in raw mode at the moment, which
1330 * is sufficient for the helper functions we have right now.
1332 err
= check_raw_mode(fn
);
1334 verbose("kernel subsystem misconfigured func %s#%d\n",
1335 func_id_name(func_id
), func_id
);
1340 err
= check_func_arg(env
, BPF_REG_1
, fn
->arg1_type
, &meta
);
1343 err
= check_func_arg(env
, BPF_REG_2
, fn
->arg2_type
, &meta
);
1346 err
= check_func_arg(env
, BPF_REG_3
, fn
->arg3_type
, &meta
);
1349 err
= check_func_arg(env
, BPF_REG_4
, fn
->arg4_type
, &meta
);
1352 err
= check_func_arg(env
, BPF_REG_5
, fn
->arg5_type
, &meta
);
1356 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1357 * is inferred from register state.
1359 for (i
= 0; i
< meta
.access_size
; i
++) {
1360 err
= check_mem_access(env
, meta
.regno
, i
, BPF_B
, BPF_WRITE
, -1);
1365 /* reset caller saved regs */
1366 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
1367 reg
= regs
+ caller_saved
[i
];
1368 reg
->type
= NOT_INIT
;
1372 /* update return register */
1373 if (fn
->ret_type
== RET_INTEGER
) {
1374 regs
[BPF_REG_0
].type
= UNKNOWN_VALUE
;
1375 } else if (fn
->ret_type
== RET_VOID
) {
1376 regs
[BPF_REG_0
].type
= NOT_INIT
;
1377 } else if (fn
->ret_type
== RET_PTR_TO_MAP_VALUE_OR_NULL
) {
1378 regs
[BPF_REG_0
].type
= PTR_TO_MAP_VALUE_OR_NULL
;
1379 regs
[BPF_REG_0
].max_value
= regs
[BPF_REG_0
].min_value
= 0;
1380 /* remember map_ptr, so that check_map_access()
1381 * can check 'value_size' boundary of memory access
1382 * to map element returned from bpf_map_lookup_elem()
1384 if (meta
.map_ptr
== NULL
) {
1385 verbose("kernel subsystem misconfigured verifier\n");
1388 regs
[BPF_REG_0
].map_ptr
= meta
.map_ptr
;
1389 regs
[BPF_REG_0
].id
= ++env
->id_gen
;
1391 verbose("unknown return type %d of func %s#%d\n",
1392 fn
->ret_type
, func_id_name(func_id
), func_id
);
1396 err
= check_map_func_compatibility(meta
.map_ptr
, func_id
);
1401 clear_all_pkt_pointers(env
);
1405 static int check_packet_ptr_add(struct bpf_verifier_env
*env
,
1406 struct bpf_insn
*insn
)
1408 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1409 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1410 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1411 struct bpf_reg_state tmp_reg
;
1414 if (BPF_SRC(insn
->code
) == BPF_K
) {
1415 /* pkt_ptr += imm */
1420 verbose("addition of negative constant to packet pointer is not allowed\n");
1423 if (imm
>= MAX_PACKET_OFF
||
1424 imm
+ dst_reg
->off
>= MAX_PACKET_OFF
) {
1425 verbose("constant %d is too large to add to packet pointer\n",
1429 /* a constant was added to pkt_ptr.
1430 * Remember it while keeping the same 'id'
1432 dst_reg
->off
+= imm
;
1434 if (src_reg
->type
== PTR_TO_PACKET
) {
1435 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1436 tmp_reg
= *dst_reg
; /* save r7 state */
1437 *dst_reg
= *src_reg
; /* copy pkt_ptr state r6 into r7 */
1438 src_reg
= &tmp_reg
; /* pretend it's src_reg state */
1439 /* if the checks below reject it, the copy won't matter,
1440 * since we're rejecting the whole program. If all ok,
1441 * then imm22 state will be added to r7
1442 * and r7 will be pkt(id=0,off=22,r=62) while
1443 * r6 will stay as pkt(id=0,off=0,r=62)
1447 if (src_reg
->type
== CONST_IMM
) {
1448 /* pkt_ptr += reg where reg is known constant */
1452 /* disallow pkt_ptr += reg
1453 * if reg is not uknown_value with guaranteed zero upper bits
1454 * otherwise pkt_ptr may overflow and addition will become
1455 * subtraction which is not allowed
1457 if (src_reg
->type
!= UNKNOWN_VALUE
) {
1458 verbose("cannot add '%s' to ptr_to_packet\n",
1459 reg_type_str
[src_reg
->type
]);
1462 if (src_reg
->imm
< 48) {
1463 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1467 /* dst_reg stays as pkt_ptr type and since some positive
1468 * integer value was added to the pointer, increment its 'id'
1470 dst_reg
->id
= ++env
->id_gen
;
1472 /* something was added to pkt_ptr, set range and off to zero */
1479 static int evaluate_reg_alu(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
1481 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1482 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1483 u8 opcode
= BPF_OP(insn
->code
);
1486 /* for type == UNKNOWN_VALUE:
1487 * imm > 0 -> number of zero upper bits
1488 * imm == 0 -> don't track which is the same as all bits can be non-zero
1491 if (BPF_SRC(insn
->code
) == BPF_X
) {
1492 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1494 if (src_reg
->type
== UNKNOWN_VALUE
&& src_reg
->imm
> 0 &&
1495 dst_reg
->imm
&& opcode
== BPF_ADD
) {
1497 * where both have zero upper bits. Adding them
1498 * can only result making one more bit non-zero
1499 * in the larger value.
1500 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1501 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1503 dst_reg
->imm
= min(dst_reg
->imm
, src_reg
->imm
);
1507 if (src_reg
->type
== CONST_IMM
&& src_reg
->imm
> 0 &&
1508 dst_reg
->imm
&& opcode
== BPF_ADD
) {
1510 * where dreg has zero upper bits and sreg is const.
1511 * Adding them can only result making one more bit
1512 * non-zero in the larger value.
1514 imm_log2
= __ilog2_u64((long long)src_reg
->imm
);
1515 dst_reg
->imm
= min(dst_reg
->imm
, 63 - imm_log2
);
1519 /* all other cases non supported yet, just mark dst_reg */
1524 /* sign extend 32-bit imm into 64-bit to make sure that
1525 * negative values occupy bit 63. Note ilog2() would have
1526 * been incorrect, since sizeof(insn->imm) == 4
1528 imm_log2
= __ilog2_u64((long long)insn
->imm
);
1530 if (dst_reg
->imm
&& opcode
== BPF_LSH
) {
1532 * if reg was a result of 2 byte load, then its imm == 48
1533 * which means that upper 48 bits are zero and shifting this reg
1534 * left by 4 would mean that upper 44 bits are still zero
1536 dst_reg
->imm
-= insn
->imm
;
1537 } else if (dst_reg
->imm
&& opcode
== BPF_MUL
) {
1539 * if multiplying by 14 subtract 4
1540 * This is conservative calculation of upper zero bits.
1541 * It's not trying to special case insn->imm == 1 or 0 cases
1543 dst_reg
->imm
-= imm_log2
+ 1;
1544 } else if (opcode
== BPF_AND
) {
1546 dst_reg
->imm
= 63 - imm_log2
;
1547 } else if (dst_reg
->imm
&& opcode
== BPF_ADD
) {
1549 dst_reg
->imm
= min(dst_reg
->imm
, 63 - imm_log2
);
1551 } else if (opcode
== BPF_RSH
) {
1553 * which means that after right shift, upper bits will be zero
1554 * note that verifier already checked that
1555 * 0 <= imm < 64 for shift insn
1557 dst_reg
->imm
+= insn
->imm
;
1558 if (unlikely(dst_reg
->imm
> 64))
1559 /* some dumb code did:
1562 * and all bits are zero now */
1565 /* all other alu ops, means that we don't know what will
1566 * happen to the value, mark it with unknown number of zero bits
1571 if (dst_reg
->imm
< 0) {
1572 /* all 64 bits of the register can contain non-zero bits
1573 * and such value cannot be added to ptr_to_packet, since it
1574 * may overflow, mark it as unknown to avoid further eval
1581 static int evaluate_reg_imm_alu(struct bpf_verifier_env
*env
,
1582 struct bpf_insn
*insn
)
1584 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
1585 struct bpf_reg_state
*dst_reg
= ®s
[insn
->dst_reg
];
1586 struct bpf_reg_state
*src_reg
= ®s
[insn
->src_reg
];
1587 u8 opcode
= BPF_OP(insn
->code
);
1588 u64 dst_imm
= dst_reg
->imm
;
1590 /* dst_reg->type == CONST_IMM here. Simulate execution of insns
1591 * containing ALU ops. Don't care about overflow or negative
1592 * values, just add/sub/... them; registers are in u64.
1594 if (opcode
== BPF_ADD
&& BPF_SRC(insn
->code
) == BPF_K
) {
1595 dst_imm
+= insn
->imm
;
1596 } else if (opcode
== BPF_ADD
&& BPF_SRC(insn
->code
) == BPF_X
&&
1597 src_reg
->type
== CONST_IMM
) {
1598 dst_imm
+= src_reg
->imm
;
1599 } else if (opcode
== BPF_SUB
&& BPF_SRC(insn
->code
) == BPF_K
) {
1600 dst_imm
-= insn
->imm
;
1601 } else if (opcode
== BPF_SUB
&& BPF_SRC(insn
->code
) == BPF_X
&&
1602 src_reg
->type
== CONST_IMM
) {
1603 dst_imm
-= src_reg
->imm
;
1604 } else if (opcode
== BPF_MUL
&& BPF_SRC(insn
->code
) == BPF_K
) {
1605 dst_imm
*= insn
->imm
;
1606 } else if (opcode
== BPF_MUL
&& BPF_SRC(insn
->code
) == BPF_X
&&
1607 src_reg
->type
== CONST_IMM
) {
1608 dst_imm
*= src_reg
->imm
;
1609 } else if (opcode
== BPF_OR
&& BPF_SRC(insn
->code
) == BPF_K
) {
1610 dst_imm
|= insn
->imm
;
1611 } else if (opcode
== BPF_OR
&& BPF_SRC(insn
->code
) == BPF_X
&&
1612 src_reg
->type
== CONST_IMM
) {
1613 dst_imm
|= src_reg
->imm
;
1614 } else if (opcode
== BPF_AND
&& BPF_SRC(insn
->code
) == BPF_K
) {
1615 dst_imm
&= insn
->imm
;
1616 } else if (opcode
== BPF_AND
&& BPF_SRC(insn
->code
) == BPF_X
&&
1617 src_reg
->type
== CONST_IMM
) {
1618 dst_imm
&= src_reg
->imm
;
1619 } else if (opcode
== BPF_RSH
&& BPF_SRC(insn
->code
) == BPF_K
) {
1620 dst_imm
>>= insn
->imm
;
1621 } else if (opcode
== BPF_RSH
&& BPF_SRC(insn
->code
) == BPF_X
&&
1622 src_reg
->type
== CONST_IMM
) {
1623 dst_imm
>>= src_reg
->imm
;
1624 } else if (opcode
== BPF_LSH
&& BPF_SRC(insn
->code
) == BPF_K
) {
1625 dst_imm
<<= insn
->imm
;
1626 } else if (opcode
== BPF_LSH
&& BPF_SRC(insn
->code
) == BPF_X
&&
1627 src_reg
->type
== CONST_IMM
) {
1628 dst_imm
<<= src_reg
->imm
;
1630 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1634 dst_reg
->imm
= dst_imm
;
1639 static void check_reg_overflow(struct bpf_reg_state
*reg
)
1641 if (reg
->max_value
> BPF_REGISTER_MAX_RANGE
)
1642 reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1643 if (reg
->min_value
< BPF_REGISTER_MIN_RANGE
||
1644 reg
->min_value
> BPF_REGISTER_MAX_RANGE
)
1645 reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1648 static void adjust_reg_min_max_vals(struct bpf_verifier_env
*env
,
1649 struct bpf_insn
*insn
)
1651 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *dst_reg
;
1652 s64 min_val
= BPF_REGISTER_MIN_RANGE
;
1653 u64 max_val
= BPF_REGISTER_MAX_RANGE
;
1654 u8 opcode
= BPF_OP(insn
->code
);
1656 dst_reg
= ®s
[insn
->dst_reg
];
1657 if (BPF_SRC(insn
->code
) == BPF_X
) {
1658 check_reg_overflow(®s
[insn
->src_reg
]);
1659 min_val
= regs
[insn
->src_reg
].min_value
;
1660 max_val
= regs
[insn
->src_reg
].max_value
;
1662 /* If the source register is a random pointer then the
1663 * min_value/max_value values represent the range of the known
1664 * accesses into that value, not the actual min/max value of the
1665 * register itself. In this case we have to reset the reg range
1666 * values so we know it is not safe to look at.
1668 if (regs
[insn
->src_reg
].type
!= CONST_IMM
&&
1669 regs
[insn
->src_reg
].type
!= UNKNOWN_VALUE
) {
1670 min_val
= BPF_REGISTER_MIN_RANGE
;
1671 max_val
= BPF_REGISTER_MAX_RANGE
;
1673 } else if (insn
->imm
< BPF_REGISTER_MAX_RANGE
&&
1674 (s64
)insn
->imm
> BPF_REGISTER_MIN_RANGE
) {
1675 min_val
= max_val
= insn
->imm
;
1678 /* We don't know anything about what was done to this register, mark it
1681 if (min_val
== BPF_REGISTER_MIN_RANGE
&&
1682 max_val
== BPF_REGISTER_MAX_RANGE
) {
1683 reset_reg_range_values(regs
, insn
->dst_reg
);
1687 /* If one of our values was at the end of our ranges then we can't just
1688 * do our normal operations to the register, we need to set the values
1689 * to the min/max since they are undefined.
1691 if (min_val
== BPF_REGISTER_MIN_RANGE
)
1692 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1693 if (max_val
== BPF_REGISTER_MAX_RANGE
)
1694 dst_reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1698 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1699 dst_reg
->min_value
+= min_val
;
1700 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1701 dst_reg
->max_value
+= max_val
;
1704 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1705 dst_reg
->min_value
-= min_val
;
1706 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1707 dst_reg
->max_value
-= max_val
;
1710 if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1711 dst_reg
->min_value
*= min_val
;
1712 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1713 dst_reg
->max_value
*= max_val
;
1716 /* Disallow AND'ing of negative numbers, ain't nobody got time
1717 * for that. Otherwise the minimum is 0 and the max is the max
1718 * value we could AND against.
1721 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1723 dst_reg
->min_value
= 0;
1724 dst_reg
->max_value
= max_val
;
1727 /* Gotta have special overflow logic here, if we're shifting
1728 * more than MAX_RANGE then just assume we have an invalid
1731 if (min_val
> ilog2(BPF_REGISTER_MAX_RANGE
))
1732 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1733 else if (dst_reg
->min_value
!= BPF_REGISTER_MIN_RANGE
)
1734 dst_reg
->min_value
<<= min_val
;
1736 if (max_val
> ilog2(BPF_REGISTER_MAX_RANGE
))
1737 dst_reg
->max_value
= BPF_REGISTER_MAX_RANGE
;
1738 else if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1739 dst_reg
->max_value
<<= max_val
;
1742 /* RSH by a negative number is undefined, and the BPF_RSH is an
1743 * unsigned shift, so make the appropriate casts.
1745 if (min_val
< 0 || dst_reg
->min_value
< 0)
1746 dst_reg
->min_value
= BPF_REGISTER_MIN_RANGE
;
1748 dst_reg
->min_value
=
1749 (u64
)(dst_reg
->min_value
) >> min_val
;
1750 if (dst_reg
->max_value
!= BPF_REGISTER_MAX_RANGE
)
1751 dst_reg
->max_value
>>= max_val
;
1754 reset_reg_range_values(regs
, insn
->dst_reg
);
1758 check_reg_overflow(dst_reg
);
1761 /* check validity of 32-bit and 64-bit arithmetic operations */
1762 static int check_alu_op(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
1764 struct bpf_reg_state
*regs
= env
->cur_state
.regs
, *dst_reg
;
1765 u8 opcode
= BPF_OP(insn
->code
);
1768 if (opcode
== BPF_END
|| opcode
== BPF_NEG
) {
1769 if (opcode
== BPF_NEG
) {
1770 if (BPF_SRC(insn
->code
) != 0 ||
1771 insn
->src_reg
!= BPF_REG_0
||
1772 insn
->off
!= 0 || insn
->imm
!= 0) {
1773 verbose("BPF_NEG uses reserved fields\n");
1777 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
1778 (insn
->imm
!= 16 && insn
->imm
!= 32 && insn
->imm
!= 64)) {
1779 verbose("BPF_END uses reserved fields\n");
1784 /* check src operand */
1785 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
1789 if (is_pointer_value(env
, insn
->dst_reg
)) {
1790 verbose("R%d pointer arithmetic prohibited\n",
1795 /* check dest operand */
1796 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
1800 } else if (opcode
== BPF_MOV
) {
1802 if (BPF_SRC(insn
->code
) == BPF_X
) {
1803 if (insn
->imm
!= 0 || insn
->off
!= 0) {
1804 verbose("BPF_MOV uses reserved fields\n");
1808 /* check src operand */
1809 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
1813 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
1814 verbose("BPF_MOV uses reserved fields\n");
1819 /* check dest operand */
1820 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
1824 /* we are setting our register to something new, we need to
1825 * reset its range values.
1827 reset_reg_range_values(regs
, insn
->dst_reg
);
1829 if (BPF_SRC(insn
->code
) == BPF_X
) {
1830 if (BPF_CLASS(insn
->code
) == BPF_ALU64
) {
1832 * copy register state to dest reg
1834 regs
[insn
->dst_reg
] = regs
[insn
->src_reg
];
1836 if (is_pointer_value(env
, insn
->src_reg
)) {
1837 verbose("R%d partial copy of pointer\n",
1841 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1845 * remember the value we stored into this reg
1847 regs
[insn
->dst_reg
].type
= CONST_IMM
;
1848 regs
[insn
->dst_reg
].imm
= insn
->imm
;
1849 regs
[insn
->dst_reg
].max_value
= insn
->imm
;
1850 regs
[insn
->dst_reg
].min_value
= insn
->imm
;
1853 } else if (opcode
> BPF_END
) {
1854 verbose("invalid BPF_ALU opcode %x\n", opcode
);
1857 } else { /* all other ALU ops: and, sub, xor, add, ... */
1859 if (BPF_SRC(insn
->code
) == BPF_X
) {
1860 if (insn
->imm
!= 0 || insn
->off
!= 0) {
1861 verbose("BPF_ALU uses reserved fields\n");
1864 /* check src1 operand */
1865 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
1869 if (insn
->src_reg
!= BPF_REG_0
|| insn
->off
!= 0) {
1870 verbose("BPF_ALU uses reserved fields\n");
1875 /* check src2 operand */
1876 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
1880 if ((opcode
== BPF_MOD
|| opcode
== BPF_DIV
) &&
1881 BPF_SRC(insn
->code
) == BPF_K
&& insn
->imm
== 0) {
1882 verbose("div by zero\n");
1886 if ((opcode
== BPF_LSH
|| opcode
== BPF_RSH
||
1887 opcode
== BPF_ARSH
) && BPF_SRC(insn
->code
) == BPF_K
) {
1888 int size
= BPF_CLASS(insn
->code
) == BPF_ALU64
? 64 : 32;
1890 if (insn
->imm
< 0 || insn
->imm
>= size
) {
1891 verbose("invalid shift %d\n", insn
->imm
);
1896 /* check dest operand */
1897 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP_NO_MARK
);
1901 dst_reg
= ®s
[insn
->dst_reg
];
1903 /* first we want to adjust our ranges. */
1904 adjust_reg_min_max_vals(env
, insn
);
1906 /* pattern match 'bpf_add Rx, imm' instruction */
1907 if (opcode
== BPF_ADD
&& BPF_CLASS(insn
->code
) == BPF_ALU64
&&
1908 dst_reg
->type
== FRAME_PTR
&& BPF_SRC(insn
->code
) == BPF_K
) {
1909 dst_reg
->type
= PTR_TO_STACK
;
1910 dst_reg
->imm
= insn
->imm
;
1912 } else if (opcode
== BPF_ADD
&&
1913 BPF_CLASS(insn
->code
) == BPF_ALU64
&&
1914 (dst_reg
->type
== PTR_TO_PACKET
||
1915 (BPF_SRC(insn
->code
) == BPF_X
&&
1916 regs
[insn
->src_reg
].type
== PTR_TO_PACKET
))) {
1917 /* ptr_to_packet += K|X */
1918 return check_packet_ptr_add(env
, insn
);
1919 } else if (BPF_CLASS(insn
->code
) == BPF_ALU64
&&
1920 dst_reg
->type
== UNKNOWN_VALUE
&&
1921 env
->allow_ptr_leaks
) {
1922 /* unknown += K|X */
1923 return evaluate_reg_alu(env
, insn
);
1924 } else if (BPF_CLASS(insn
->code
) == BPF_ALU64
&&
1925 dst_reg
->type
== CONST_IMM
&&
1926 env
->allow_ptr_leaks
) {
1927 /* reg_imm += K|X */
1928 return evaluate_reg_imm_alu(env
, insn
);
1929 } else if (is_pointer_value(env
, insn
->dst_reg
)) {
1930 verbose("R%d pointer arithmetic prohibited\n",
1933 } else if (BPF_SRC(insn
->code
) == BPF_X
&&
1934 is_pointer_value(env
, insn
->src_reg
)) {
1935 verbose("R%d pointer arithmetic prohibited\n",
1940 /* If we did pointer math on a map value then just set it to our
1941 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
1942 * loads to this register appropriately, otherwise just mark the
1943 * register as unknown.
1945 if (env
->allow_ptr_leaks
&&
1946 BPF_CLASS(insn
->code
) == BPF_ALU64
&& opcode
== BPF_ADD
&&
1947 (dst_reg
->type
== PTR_TO_MAP_VALUE
||
1948 dst_reg
->type
== PTR_TO_MAP_VALUE_ADJ
))
1949 dst_reg
->type
= PTR_TO_MAP_VALUE_ADJ
;
1951 mark_reg_unknown_value(regs
, insn
->dst_reg
);
1957 static void find_good_pkt_pointers(struct bpf_verifier_state
*state
,
1958 struct bpf_reg_state
*dst_reg
)
1960 struct bpf_reg_state
*regs
= state
->regs
, *reg
;
1963 /* LLVM can generate two kind of checks:
1969 * if (r2 > pkt_end) goto <handle exception>
1973 * r2 == dst_reg, pkt_end == src_reg
1974 * r2=pkt(id=n,off=8,r=0)
1975 * r3=pkt(id=n,off=0,r=0)
1981 * if (pkt_end >= r2) goto <access okay>
1982 * <handle exception>
1985 * pkt_end == dst_reg, r2 == src_reg
1986 * r2=pkt(id=n,off=8,r=0)
1987 * r3=pkt(id=n,off=0,r=0)
1989 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
1990 * so that range of bytes [r3, r3 + 8) is safe to access.
1993 for (i
= 0; i
< MAX_BPF_REG
; i
++)
1994 if (regs
[i
].type
== PTR_TO_PACKET
&& regs
[i
].id
== dst_reg
->id
)
1995 /* keep the maximum range already checked */
1996 regs
[i
].range
= max(regs
[i
].range
, dst_reg
->off
);
1998 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
1999 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
2001 reg
= &state
->spilled_regs
[i
/ BPF_REG_SIZE
];
2002 if (reg
->type
== PTR_TO_PACKET
&& reg
->id
== dst_reg
->id
)
2003 reg
->range
= max(reg
->range
, dst_reg
->off
);
2007 /* Adjusts the register min/max values in the case that the dst_reg is the
2008 * variable register that we are working on, and src_reg is a constant or we're
2009 * simply doing a BPF_K check.
2011 static void reg_set_min_max(struct bpf_reg_state
*true_reg
,
2012 struct bpf_reg_state
*false_reg
, u64 val
,
2017 /* If this is false then we know nothing Jon Snow, but if it is
2018 * true then we know for sure.
2020 true_reg
->max_value
= true_reg
->min_value
= val
;
2023 /* If this is true we know nothing Jon Snow, but if it is false
2024 * we know the value for sure;
2026 false_reg
->max_value
= false_reg
->min_value
= val
;
2029 /* Unsigned comparison, the minimum value is 0. */
2030 false_reg
->min_value
= 0;
2033 /* If this is false then we know the maximum val is val,
2034 * otherwise we know the min val is val+1.
2036 false_reg
->max_value
= val
;
2037 true_reg
->min_value
= val
+ 1;
2040 /* Unsigned comparison, the minimum value is 0. */
2041 false_reg
->min_value
= 0;
2044 /* If this is false then we know the maximum value is val - 1,
2045 * otherwise we know the mimimum value is val.
2047 false_reg
->max_value
= val
- 1;
2048 true_reg
->min_value
= val
;
2054 check_reg_overflow(false_reg
);
2055 check_reg_overflow(true_reg
);
2058 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
2059 * is the variable reg.
2061 static void reg_set_min_max_inv(struct bpf_reg_state
*true_reg
,
2062 struct bpf_reg_state
*false_reg
, u64 val
,
2067 /* If this is false then we know nothing Jon Snow, but if it is
2068 * true then we know for sure.
2070 true_reg
->max_value
= true_reg
->min_value
= val
;
2073 /* If this is true we know nothing Jon Snow, but if it is false
2074 * we know the value for sure;
2076 false_reg
->max_value
= false_reg
->min_value
= val
;
2079 /* Unsigned comparison, the minimum value is 0. */
2080 true_reg
->min_value
= 0;
2084 * If this is false, then the val is <= the register, if it is
2085 * true the register <= to the val.
2087 false_reg
->min_value
= val
;
2088 true_reg
->max_value
= val
- 1;
2091 /* Unsigned comparison, the minimum value is 0. */
2092 true_reg
->min_value
= 0;
2095 /* If this is false then constant < register, if it is true then
2096 * the register < constant.
2098 false_reg
->min_value
= val
+ 1;
2099 true_reg
->max_value
= val
;
2105 check_reg_overflow(false_reg
);
2106 check_reg_overflow(true_reg
);
2109 static void mark_map_reg(struct bpf_reg_state
*regs
, u32 regno
, u32 id
,
2110 enum bpf_reg_type type
)
2112 struct bpf_reg_state
*reg
= ®s
[regno
];
2114 if (reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
&& reg
->id
== id
) {
2116 /* We don't need id from this point onwards anymore, thus we
2117 * should better reset it, so that state pruning has chances
2121 if (type
== UNKNOWN_VALUE
)
2122 __mark_reg_unknown_value(regs
, regno
);
2126 /* The logic is similar to find_good_pkt_pointers(), both could eventually
2127 * be folded together at some point.
2129 static void mark_map_regs(struct bpf_verifier_state
*state
, u32 regno
,
2130 enum bpf_reg_type type
)
2132 struct bpf_reg_state
*regs
= state
->regs
;
2133 u32 id
= regs
[regno
].id
;
2136 for (i
= 0; i
< MAX_BPF_REG
; i
++)
2137 mark_map_reg(regs
, i
, id
, type
);
2139 for (i
= 0; i
< MAX_BPF_STACK
; i
+= BPF_REG_SIZE
) {
2140 if (state
->stack_slot_type
[i
] != STACK_SPILL
)
2142 mark_map_reg(state
->spilled_regs
, i
/ BPF_REG_SIZE
, id
, type
);
2146 static int check_cond_jmp_op(struct bpf_verifier_env
*env
,
2147 struct bpf_insn
*insn
, int *insn_idx
)
2149 struct bpf_verifier_state
*other_branch
, *this_branch
= &env
->cur_state
;
2150 struct bpf_reg_state
*regs
= this_branch
->regs
, *dst_reg
;
2151 u8 opcode
= BPF_OP(insn
->code
);
2154 if (opcode
> BPF_EXIT
) {
2155 verbose("invalid BPF_JMP opcode %x\n", opcode
);
2159 if (BPF_SRC(insn
->code
) == BPF_X
) {
2160 if (insn
->imm
!= 0) {
2161 verbose("BPF_JMP uses reserved fields\n");
2165 /* check src1 operand */
2166 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2170 if (is_pointer_value(env
, insn
->src_reg
)) {
2171 verbose("R%d pointer comparison prohibited\n",
2176 if (insn
->src_reg
!= BPF_REG_0
) {
2177 verbose("BPF_JMP uses reserved fields\n");
2182 /* check src2 operand */
2183 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
2187 dst_reg
= ®s
[insn
->dst_reg
];
2189 /* detect if R == 0 where R was initialized to zero earlier */
2190 if (BPF_SRC(insn
->code
) == BPF_K
&&
2191 (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
2192 dst_reg
->type
== CONST_IMM
&& dst_reg
->imm
== insn
->imm
) {
2193 if (opcode
== BPF_JEQ
) {
2194 /* if (imm == imm) goto pc+off;
2195 * only follow the goto, ignore fall-through
2197 *insn_idx
+= insn
->off
;
2200 /* if (imm != imm) goto pc+off;
2201 * only follow fall-through branch, since
2202 * that's where the program will go
2208 other_branch
= push_stack(env
, *insn_idx
+ insn
->off
+ 1, *insn_idx
);
2212 /* detect if we are comparing against a constant value so we can adjust
2213 * our min/max values for our dst register.
2215 if (BPF_SRC(insn
->code
) == BPF_X
) {
2216 if (regs
[insn
->src_reg
].type
== CONST_IMM
)
2217 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
2218 dst_reg
, regs
[insn
->src_reg
].imm
,
2220 else if (dst_reg
->type
== CONST_IMM
)
2221 reg_set_min_max_inv(&other_branch
->regs
[insn
->src_reg
],
2222 ®s
[insn
->src_reg
], dst_reg
->imm
,
2225 reg_set_min_max(&other_branch
->regs
[insn
->dst_reg
],
2226 dst_reg
, insn
->imm
, opcode
);
2229 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
2230 if (BPF_SRC(insn
->code
) == BPF_K
&&
2231 insn
->imm
== 0 && (opcode
== BPF_JEQ
|| opcode
== BPF_JNE
) &&
2232 dst_reg
->type
== PTR_TO_MAP_VALUE_OR_NULL
) {
2233 /* Mark all identical map registers in each branch as either
2234 * safe or unknown depending R == 0 or R != 0 conditional.
2236 mark_map_regs(this_branch
, insn
->dst_reg
,
2237 opcode
== BPF_JEQ
? PTR_TO_MAP_VALUE
: UNKNOWN_VALUE
);
2238 mark_map_regs(other_branch
, insn
->dst_reg
,
2239 opcode
== BPF_JEQ
? UNKNOWN_VALUE
: PTR_TO_MAP_VALUE
);
2240 } else if (BPF_SRC(insn
->code
) == BPF_X
&& opcode
== BPF_JGT
&&
2241 dst_reg
->type
== PTR_TO_PACKET
&&
2242 regs
[insn
->src_reg
].type
== PTR_TO_PACKET_END
) {
2243 find_good_pkt_pointers(this_branch
, dst_reg
);
2244 } else if (BPF_SRC(insn
->code
) == BPF_X
&& opcode
== BPF_JGE
&&
2245 dst_reg
->type
== PTR_TO_PACKET_END
&&
2246 regs
[insn
->src_reg
].type
== PTR_TO_PACKET
) {
2247 find_good_pkt_pointers(other_branch
, ®s
[insn
->src_reg
]);
2248 } else if (is_pointer_value(env
, insn
->dst_reg
)) {
2249 verbose("R%d pointer comparison prohibited\n", insn
->dst_reg
);
2253 print_verifier_state(this_branch
);
2257 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
2258 static struct bpf_map
*ld_imm64_to_map_ptr(struct bpf_insn
*insn
)
2260 u64 imm64
= ((u64
) (u32
) insn
[0].imm
) | ((u64
) (u32
) insn
[1].imm
) << 32;
2262 return (struct bpf_map
*) (unsigned long) imm64
;
2265 /* verify BPF_LD_IMM64 instruction */
2266 static int check_ld_imm(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
2268 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
2271 if (BPF_SIZE(insn
->code
) != BPF_DW
) {
2272 verbose("invalid BPF_LD_IMM insn\n");
2275 if (insn
->off
!= 0) {
2276 verbose("BPF_LD_IMM64 uses reserved fields\n");
2280 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP
);
2284 if (insn
->src_reg
== 0) {
2285 u64 imm
= ((u64
)(insn
+ 1)->imm
<< 32) | (u32
)insn
->imm
;
2287 regs
[insn
->dst_reg
].type
= CONST_IMM
;
2288 regs
[insn
->dst_reg
].imm
= imm
;
2292 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2293 BUG_ON(insn
->src_reg
!= BPF_PSEUDO_MAP_FD
);
2295 regs
[insn
->dst_reg
].type
= CONST_PTR_TO_MAP
;
2296 regs
[insn
->dst_reg
].map_ptr
= ld_imm64_to_map_ptr(insn
);
2300 static bool may_access_skb(enum bpf_prog_type type
)
2303 case BPF_PROG_TYPE_SOCKET_FILTER
:
2304 case BPF_PROG_TYPE_SCHED_CLS
:
2305 case BPF_PROG_TYPE_SCHED_ACT
:
2312 /* verify safety of LD_ABS|LD_IND instructions:
2313 * - they can only appear in the programs where ctx == skb
2314 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2315 * preserve R6-R9, and store return value into R0
2318 * ctx == skb == R6 == CTX
2321 * SRC == any register
2322 * IMM == 32-bit immediate
2325 * R0 - 8/16/32-bit skb data converted to cpu endianness
2327 static int check_ld_abs(struct bpf_verifier_env
*env
, struct bpf_insn
*insn
)
2329 struct bpf_reg_state
*regs
= env
->cur_state
.regs
;
2330 u8 mode
= BPF_MODE(insn
->code
);
2331 struct bpf_reg_state
*reg
;
2334 if (!may_access_skb(env
->prog
->type
)) {
2335 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
2339 if (insn
->dst_reg
!= BPF_REG_0
|| insn
->off
!= 0 ||
2340 BPF_SIZE(insn
->code
) == BPF_DW
||
2341 (mode
== BPF_ABS
&& insn
->src_reg
!= BPF_REG_0
)) {
2342 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
2346 /* check whether implicit source operand (register R6) is readable */
2347 err
= check_reg_arg(regs
, BPF_REG_6
, SRC_OP
);
2351 if (regs
[BPF_REG_6
].type
!= PTR_TO_CTX
) {
2352 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2356 if (mode
== BPF_IND
) {
2357 /* check explicit source operand */
2358 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2363 /* reset caller saved regs to unreadable */
2364 for (i
= 0; i
< CALLER_SAVED_REGS
; i
++) {
2365 reg
= regs
+ caller_saved
[i
];
2366 reg
->type
= NOT_INIT
;
2370 /* mark destination R0 register as readable, since it contains
2371 * the value fetched from the packet
2373 regs
[BPF_REG_0
].type
= UNKNOWN_VALUE
;
2377 /* non-recursive DFS pseudo code
2378 * 1 procedure DFS-iterative(G,v):
2379 * 2 label v as discovered
2380 * 3 let S be a stack
2382 * 5 while S is not empty
2384 * 7 if t is what we're looking for:
2386 * 9 for all edges e in G.adjacentEdges(t) do
2387 * 10 if edge e is already labelled
2388 * 11 continue with the next edge
2389 * 12 w <- G.adjacentVertex(t,e)
2390 * 13 if vertex w is not discovered and not explored
2391 * 14 label e as tree-edge
2392 * 15 label w as discovered
2395 * 18 else if vertex w is discovered
2396 * 19 label e as back-edge
2398 * 21 // vertex w is explored
2399 * 22 label e as forward- or cross-edge
2400 * 23 label t as explored
2405 * 0x11 - discovered and fall-through edge labelled
2406 * 0x12 - discovered and fall-through and branch edges labelled
2417 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
2419 static int *insn_stack
; /* stack of insns to process */
2420 static int cur_stack
; /* current stack index */
2421 static int *insn_state
;
2423 /* t, w, e - match pseudo-code above:
2424 * t - index of current instruction
2425 * w - next instruction
2428 static int push_insn(int t
, int w
, int e
, struct bpf_verifier_env
*env
)
2430 if (e
== FALLTHROUGH
&& insn_state
[t
] >= (DISCOVERED
| FALLTHROUGH
))
2433 if (e
== BRANCH
&& insn_state
[t
] >= (DISCOVERED
| BRANCH
))
2436 if (w
< 0 || w
>= env
->prog
->len
) {
2437 verbose("jump out of range from insn %d to %d\n", t
, w
);
2442 /* mark branch target for state pruning */
2443 env
->explored_states
[w
] = STATE_LIST_MARK
;
2445 if (insn_state
[w
] == 0) {
2447 insn_state
[t
] = DISCOVERED
| e
;
2448 insn_state
[w
] = DISCOVERED
;
2449 if (cur_stack
>= env
->prog
->len
)
2451 insn_stack
[cur_stack
++] = w
;
2453 } else if ((insn_state
[w
] & 0xF0) == DISCOVERED
) {
2454 verbose("back-edge from insn %d to %d\n", t
, w
);
2456 } else if (insn_state
[w
] == EXPLORED
) {
2457 /* forward- or cross-edge */
2458 insn_state
[t
] = DISCOVERED
| e
;
2460 verbose("insn state internal bug\n");
2466 /* non-recursive depth-first-search to detect loops in BPF program
2467 * loop == back-edge in directed graph
2469 static int check_cfg(struct bpf_verifier_env
*env
)
2471 struct bpf_insn
*insns
= env
->prog
->insnsi
;
2472 int insn_cnt
= env
->prog
->len
;
2476 insn_state
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
2480 insn_stack
= kcalloc(insn_cnt
, sizeof(int), GFP_KERNEL
);
2486 insn_state
[0] = DISCOVERED
; /* mark 1st insn as discovered */
2487 insn_stack
[0] = 0; /* 0 is the first instruction */
2493 t
= insn_stack
[cur_stack
- 1];
2495 if (BPF_CLASS(insns
[t
].code
) == BPF_JMP
) {
2496 u8 opcode
= BPF_OP(insns
[t
].code
);
2498 if (opcode
== BPF_EXIT
) {
2500 } else if (opcode
== BPF_CALL
) {
2501 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2506 if (t
+ 1 < insn_cnt
)
2507 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
2508 } else if (opcode
== BPF_JA
) {
2509 if (BPF_SRC(insns
[t
].code
) != BPF_K
) {
2513 /* unconditional jump with single edge */
2514 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1,
2520 /* tell verifier to check for equivalent states
2521 * after every call and jump
2523 if (t
+ 1 < insn_cnt
)
2524 env
->explored_states
[t
+ 1] = STATE_LIST_MARK
;
2526 /* conditional jump with two edges */
2527 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2533 ret
= push_insn(t
, t
+ insns
[t
].off
+ 1, BRANCH
, env
);
2540 /* all other non-branch instructions with single
2543 ret
= push_insn(t
, t
+ 1, FALLTHROUGH
, env
);
2551 insn_state
[t
] = EXPLORED
;
2552 if (cur_stack
-- <= 0) {
2553 verbose("pop stack internal bug\n");
2560 for (i
= 0; i
< insn_cnt
; i
++) {
2561 if (insn_state
[i
] != EXPLORED
) {
2562 verbose("unreachable insn %d\n", i
);
2567 ret
= 0; /* cfg looks good */
2575 /* the following conditions reduce the number of explored insns
2576 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2578 static bool compare_ptrs_to_packet(struct bpf_reg_state
*old
,
2579 struct bpf_reg_state
*cur
)
2581 if (old
->id
!= cur
->id
)
2584 /* old ptr_to_packet is more conservative, since it allows smaller
2586 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2587 * old(off=0,r=10) means that with range=10 the verifier proceeded
2588 * further and found no issues with the program. Now we're in the same
2589 * spot with cur(off=0,r=20), so we're safe too, since anything further
2590 * will only be looking at most 10 bytes after this pointer.
2592 if (old
->off
== cur
->off
&& old
->range
< cur
->range
)
2595 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2596 * since both cannot be used for packet access and safe(old)
2597 * pointer has smaller off that could be used for further
2598 * 'if (ptr > data_end)' check
2600 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2601 * that we cannot access the packet.
2602 * The safe range is:
2603 * [ptr, ptr + range - off)
2604 * so whenever off >=range, it means no safe bytes from this pointer.
2605 * When comparing old->off <= cur->off, it means that older code
2606 * went with smaller offset and that offset was later
2607 * used to figure out the safe range after 'if (ptr > data_end)' check
2608 * Say, 'old' state was explored like:
2609 * ... R3(off=0, r=0)
2611 * ... now R4(off=20,r=0) <-- here
2612 * if (R4 > data_end)
2613 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2614 * ... the code further went all the way to bpf_exit.
2615 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2616 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2617 * goes further, such cur_R4 will give larger safe packet range after
2618 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2619 * so they will be good with r=30 and we can prune the search.
2621 if (old
->off
<= cur
->off
&&
2622 old
->off
>= old
->range
&& cur
->off
>= cur
->range
)
2628 /* compare two verifier states
2630 * all states stored in state_list are known to be valid, since
2631 * verifier reached 'bpf_exit' instruction through them
2633 * this function is called when verifier exploring different branches of
2634 * execution popped from the state stack. If it sees an old state that has
2635 * more strict register state and more strict stack state then this execution
2636 * branch doesn't need to be explored further, since verifier already
2637 * concluded that more strict state leads to valid finish.
2639 * Therefore two states are equivalent if register state is more conservative
2640 * and explored stack state is more conservative than the current one.
2643 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2644 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2646 * In other words if current stack state (one being explored) has more
2647 * valid slots than old one that already passed validation, it means
2648 * the verifier can stop exploring and conclude that current state is valid too
2650 * Similarly with registers. If explored state has register type as invalid
2651 * whereas register type in current state is meaningful, it means that
2652 * the current state will reach 'bpf_exit' instruction safely
2654 static bool states_equal(struct bpf_verifier_env
*env
,
2655 struct bpf_verifier_state
*old
,
2656 struct bpf_verifier_state
*cur
)
2658 bool varlen_map_access
= env
->varlen_map_value_access
;
2659 struct bpf_reg_state
*rold
, *rcur
;
2662 for (i
= 0; i
< MAX_BPF_REG
; i
++) {
2663 rold
= &old
->regs
[i
];
2664 rcur
= &cur
->regs
[i
];
2666 if (memcmp(rold
, rcur
, sizeof(*rold
)) == 0)
2669 /* If the ranges were not the same, but everything else was and
2670 * we didn't do a variable access into a map then we are a-ok.
2672 if (!varlen_map_access
&&
2673 memcmp(rold
, rcur
, offsetofend(struct bpf_reg_state
, id
)) == 0)
2676 /* If we didn't map access then again we don't care about the
2677 * mismatched range values and it's ok if our old type was
2678 * UNKNOWN and we didn't go to a NOT_INIT'ed reg.
2680 if (rold
->type
== NOT_INIT
||
2681 (!varlen_map_access
&& rold
->type
== UNKNOWN_VALUE
&&
2682 rcur
->type
!= NOT_INIT
))
2685 if (rold
->type
== PTR_TO_PACKET
&& rcur
->type
== PTR_TO_PACKET
&&
2686 compare_ptrs_to_packet(rold
, rcur
))
2692 for (i
= 0; i
< MAX_BPF_STACK
; i
++) {
2693 if (old
->stack_slot_type
[i
] == STACK_INVALID
)
2695 if (old
->stack_slot_type
[i
] != cur
->stack_slot_type
[i
])
2696 /* Ex: old explored (safe) state has STACK_SPILL in
2697 * this stack slot, but current has has STACK_MISC ->
2698 * this verifier states are not equivalent,
2699 * return false to continue verification of this path
2702 if (i
% BPF_REG_SIZE
)
2704 if (memcmp(&old
->spilled_regs
[i
/ BPF_REG_SIZE
],
2705 &cur
->spilled_regs
[i
/ BPF_REG_SIZE
],
2706 sizeof(old
->spilled_regs
[0])))
2707 /* when explored and current stack slot types are
2708 * the same, check that stored pointers types
2709 * are the same as well.
2710 * Ex: explored safe path could have stored
2711 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
2712 * but current path has stored:
2713 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
2714 * such verifier states are not equivalent.
2715 * return false to continue verification of this path
2724 static int is_state_visited(struct bpf_verifier_env
*env
, int insn_idx
)
2726 struct bpf_verifier_state_list
*new_sl
;
2727 struct bpf_verifier_state_list
*sl
;
2729 sl
= env
->explored_states
[insn_idx
];
2731 /* this 'insn_idx' instruction wasn't marked, so we will not
2732 * be doing state search here
2736 while (sl
!= STATE_LIST_MARK
) {
2737 if (states_equal(env
, &sl
->state
, &env
->cur_state
))
2738 /* reached equivalent register/stack state,
2745 /* there were no equivalent states, remember current one.
2746 * technically the current state is not proven to be safe yet,
2747 * but it will either reach bpf_exit (which means it's safe) or
2748 * it will be rejected. Since there are no loops, we won't be
2749 * seeing this 'insn_idx' instruction again on the way to bpf_exit
2751 new_sl
= kmalloc(sizeof(struct bpf_verifier_state_list
), GFP_USER
);
2755 /* add new state to the head of linked list */
2756 memcpy(&new_sl
->state
, &env
->cur_state
, sizeof(env
->cur_state
));
2757 new_sl
->next
= env
->explored_states
[insn_idx
];
2758 env
->explored_states
[insn_idx
] = new_sl
;
2762 static int ext_analyzer_insn_hook(struct bpf_verifier_env
*env
,
2763 int insn_idx
, int prev_insn_idx
)
2765 if (!env
->analyzer_ops
|| !env
->analyzer_ops
->insn_hook
)
2768 return env
->analyzer_ops
->insn_hook(env
, insn_idx
, prev_insn_idx
);
2771 static int do_check(struct bpf_verifier_env
*env
)
2773 struct bpf_verifier_state
*state
= &env
->cur_state
;
2774 struct bpf_insn
*insns
= env
->prog
->insnsi
;
2775 struct bpf_reg_state
*regs
= state
->regs
;
2776 int insn_cnt
= env
->prog
->len
;
2777 int insn_idx
, prev_insn_idx
= 0;
2778 int insn_processed
= 0;
2779 bool do_print_state
= false;
2781 init_reg_state(regs
);
2783 env
->varlen_map_value_access
= false;
2785 struct bpf_insn
*insn
;
2789 if (insn_idx
>= insn_cnt
) {
2790 verbose("invalid insn idx %d insn_cnt %d\n",
2791 insn_idx
, insn_cnt
);
2795 insn
= &insns
[insn_idx
];
2796 class = BPF_CLASS(insn
->code
);
2798 if (++insn_processed
> BPF_COMPLEXITY_LIMIT_INSNS
) {
2799 verbose("BPF program is too large. Processed %d insn\n",
2804 err
= is_state_visited(env
, insn_idx
);
2808 /* found equivalent state, can prune the search */
2811 verbose("\nfrom %d to %d: safe\n",
2812 prev_insn_idx
, insn_idx
);
2814 verbose("%d: safe\n", insn_idx
);
2816 goto process_bpf_exit
;
2819 if (log_level
&& do_print_state
) {
2820 verbose("\nfrom %d to %d:", prev_insn_idx
, insn_idx
);
2821 print_verifier_state(&env
->cur_state
);
2822 do_print_state
= false;
2826 verbose("%d: ", insn_idx
);
2827 print_bpf_insn(insn
);
2830 err
= ext_analyzer_insn_hook(env
, insn_idx
, prev_insn_idx
);
2834 if (class == BPF_ALU
|| class == BPF_ALU64
) {
2835 err
= check_alu_op(env
, insn
);
2839 } else if (class == BPF_LDX
) {
2840 enum bpf_reg_type
*prev_src_type
, src_reg_type
;
2842 /* check for reserved fields is already done */
2844 /* check src operand */
2845 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2849 err
= check_reg_arg(regs
, insn
->dst_reg
, DST_OP_NO_MARK
);
2853 src_reg_type
= regs
[insn
->src_reg
].type
;
2855 /* check that memory (src_reg + off) is readable,
2856 * the state of dst_reg will be updated by this func
2858 err
= check_mem_access(env
, insn
->src_reg
, insn
->off
,
2859 BPF_SIZE(insn
->code
), BPF_READ
,
2864 if (BPF_SIZE(insn
->code
) != BPF_W
&&
2865 BPF_SIZE(insn
->code
) != BPF_DW
) {
2870 prev_src_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
2872 if (*prev_src_type
== NOT_INIT
) {
2874 * dst_reg = *(u32 *)(src_reg + off)
2875 * save type to validate intersecting paths
2877 *prev_src_type
= src_reg_type
;
2879 } else if (src_reg_type
!= *prev_src_type
&&
2880 (src_reg_type
== PTR_TO_CTX
||
2881 *prev_src_type
== PTR_TO_CTX
)) {
2882 /* ABuser program is trying to use the same insn
2883 * dst_reg = *(u32*) (src_reg + off)
2884 * with different pointer types:
2885 * src_reg == ctx in one branch and
2886 * src_reg == stack|map in some other branch.
2889 verbose("same insn cannot be used with different pointers\n");
2893 } else if (class == BPF_STX
) {
2894 enum bpf_reg_type
*prev_dst_type
, dst_reg_type
;
2896 if (BPF_MODE(insn
->code
) == BPF_XADD
) {
2897 err
= check_xadd(env
, insn
);
2904 /* check src1 operand */
2905 err
= check_reg_arg(regs
, insn
->src_reg
, SRC_OP
);
2908 /* check src2 operand */
2909 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
2913 dst_reg_type
= regs
[insn
->dst_reg
].type
;
2915 /* check that memory (dst_reg + off) is writeable */
2916 err
= check_mem_access(env
, insn
->dst_reg
, insn
->off
,
2917 BPF_SIZE(insn
->code
), BPF_WRITE
,
2922 prev_dst_type
= &env
->insn_aux_data
[insn_idx
].ptr_type
;
2924 if (*prev_dst_type
== NOT_INIT
) {
2925 *prev_dst_type
= dst_reg_type
;
2926 } else if (dst_reg_type
!= *prev_dst_type
&&
2927 (dst_reg_type
== PTR_TO_CTX
||
2928 *prev_dst_type
== PTR_TO_CTX
)) {
2929 verbose("same insn cannot be used with different pointers\n");
2933 } else if (class == BPF_ST
) {
2934 if (BPF_MODE(insn
->code
) != BPF_MEM
||
2935 insn
->src_reg
!= BPF_REG_0
) {
2936 verbose("BPF_ST uses reserved fields\n");
2939 /* check src operand */
2940 err
= check_reg_arg(regs
, insn
->dst_reg
, SRC_OP
);
2944 /* check that memory (dst_reg + off) is writeable */
2945 err
= check_mem_access(env
, insn
->dst_reg
, insn
->off
,
2946 BPF_SIZE(insn
->code
), BPF_WRITE
,
2951 } else if (class == BPF_JMP
) {
2952 u8 opcode
= BPF_OP(insn
->code
);
2954 if (opcode
== BPF_CALL
) {
2955 if (BPF_SRC(insn
->code
) != BPF_K
||
2957 insn
->src_reg
!= BPF_REG_0
||
2958 insn
->dst_reg
!= BPF_REG_0
) {
2959 verbose("BPF_CALL uses reserved fields\n");
2963 err
= check_call(env
, insn
->imm
);
2967 } else if (opcode
== BPF_JA
) {
2968 if (BPF_SRC(insn
->code
) != BPF_K
||
2970 insn
->src_reg
!= BPF_REG_0
||
2971 insn
->dst_reg
!= BPF_REG_0
) {
2972 verbose("BPF_JA uses reserved fields\n");
2976 insn_idx
+= insn
->off
+ 1;
2979 } else if (opcode
== BPF_EXIT
) {
2980 if (BPF_SRC(insn
->code
) != BPF_K
||
2982 insn
->src_reg
!= BPF_REG_0
||
2983 insn
->dst_reg
!= BPF_REG_0
) {
2984 verbose("BPF_EXIT uses reserved fields\n");
2988 /* eBPF calling convetion is such that R0 is used
2989 * to return the value from eBPF program.
2990 * Make sure that it's readable at this time
2991 * of bpf_exit, which means that program wrote
2992 * something into it earlier
2994 err
= check_reg_arg(regs
, BPF_REG_0
, SRC_OP
);
2998 if (is_pointer_value(env
, BPF_REG_0
)) {
2999 verbose("R0 leaks addr as return value\n");
3004 insn_idx
= pop_stack(env
, &prev_insn_idx
);
3008 do_print_state
= true;
3012 err
= check_cond_jmp_op(env
, insn
, &insn_idx
);
3016 } else if (class == BPF_LD
) {
3017 u8 mode
= BPF_MODE(insn
->code
);
3019 if (mode
== BPF_ABS
|| mode
== BPF_IND
) {
3020 err
= check_ld_abs(env
, insn
);
3024 } else if (mode
== BPF_IMM
) {
3025 err
= check_ld_imm(env
, insn
);
3031 verbose("invalid BPF_LD mode\n");
3034 reset_reg_range_values(regs
, insn
->dst_reg
);
3036 verbose("unknown insn class %d\n", class);
3043 verbose("processed %d insns\n", insn_processed
);
3047 static int check_map_prog_compatibility(struct bpf_map
*map
,
3048 struct bpf_prog
*prog
)
3051 if (prog
->type
== BPF_PROG_TYPE_PERF_EVENT
&&
3052 (map
->map_type
== BPF_MAP_TYPE_HASH
||
3053 map
->map_type
== BPF_MAP_TYPE_PERCPU_HASH
) &&
3054 (map
->map_flags
& BPF_F_NO_PREALLOC
)) {
3055 verbose("perf_event programs can only use preallocated hash map\n");
3061 /* look for pseudo eBPF instructions that access map FDs and
3062 * replace them with actual map pointers
3064 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env
*env
)
3066 struct bpf_insn
*insn
= env
->prog
->insnsi
;
3067 int insn_cnt
= env
->prog
->len
;
3070 err
= bpf_prog_calc_tag(env
->prog
);
3074 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
3075 if (BPF_CLASS(insn
->code
) == BPF_LDX
&&
3076 (BPF_MODE(insn
->code
) != BPF_MEM
|| insn
->imm
!= 0)) {
3077 verbose("BPF_LDX uses reserved fields\n");
3081 if (BPF_CLASS(insn
->code
) == BPF_STX
&&
3082 ((BPF_MODE(insn
->code
) != BPF_MEM
&&
3083 BPF_MODE(insn
->code
) != BPF_XADD
) || insn
->imm
!= 0)) {
3084 verbose("BPF_STX uses reserved fields\n");
3088 if (insn
[0].code
== (BPF_LD
| BPF_IMM
| BPF_DW
)) {
3089 struct bpf_map
*map
;
3092 if (i
== insn_cnt
- 1 || insn
[1].code
!= 0 ||
3093 insn
[1].dst_reg
!= 0 || insn
[1].src_reg
!= 0 ||
3095 verbose("invalid bpf_ld_imm64 insn\n");
3099 if (insn
->src_reg
== 0)
3100 /* valid generic load 64-bit imm */
3103 if (insn
->src_reg
!= BPF_PSEUDO_MAP_FD
) {
3104 verbose("unrecognized bpf_ld_imm64 insn\n");
3108 f
= fdget(insn
->imm
);
3109 map
= __bpf_map_get(f
);
3111 verbose("fd %d is not pointing to valid bpf_map\n",
3113 return PTR_ERR(map
);
3116 err
= check_map_prog_compatibility(map
, env
->prog
);
3122 /* store map pointer inside BPF_LD_IMM64 instruction */
3123 insn
[0].imm
= (u32
) (unsigned long) map
;
3124 insn
[1].imm
= ((u64
) (unsigned long) map
) >> 32;
3126 /* check whether we recorded this map already */
3127 for (j
= 0; j
< env
->used_map_cnt
; j
++)
3128 if (env
->used_maps
[j
] == map
) {
3133 if (env
->used_map_cnt
>= MAX_USED_MAPS
) {
3138 /* hold the map. If the program is rejected by verifier,
3139 * the map will be released by release_maps() or it
3140 * will be used by the valid program until it's unloaded
3141 * and all maps are released in free_bpf_prog_info()
3143 map
= bpf_map_inc(map
, false);
3146 return PTR_ERR(map
);
3148 env
->used_maps
[env
->used_map_cnt
++] = map
;
3157 /* now all pseudo BPF_LD_IMM64 instructions load valid
3158 * 'struct bpf_map *' into a register instead of user map_fd.
3159 * These pointers will be used later by verifier to validate map access.
3164 /* drop refcnt of maps used by the rejected program */
3165 static void release_maps(struct bpf_verifier_env
*env
)
3169 for (i
= 0; i
< env
->used_map_cnt
; i
++)
3170 bpf_map_put(env
->used_maps
[i
]);
3173 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
3174 static void convert_pseudo_ld_imm64(struct bpf_verifier_env
*env
)
3176 struct bpf_insn
*insn
= env
->prog
->insnsi
;
3177 int insn_cnt
= env
->prog
->len
;
3180 for (i
= 0; i
< insn_cnt
; i
++, insn
++)
3181 if (insn
->code
== (BPF_LD
| BPF_IMM
| BPF_DW
))
3185 /* convert load instructions that access fields of 'struct __sk_buff'
3186 * into sequence of instructions that access fields of 'struct sk_buff'
3188 static int convert_ctx_accesses(struct bpf_verifier_env
*env
)
3190 const struct bpf_verifier_ops
*ops
= env
->prog
->aux
->ops
;
3191 const int insn_cnt
= env
->prog
->len
;
3192 struct bpf_insn insn_buf
[16], *insn
;
3193 struct bpf_prog
*new_prog
;
3194 enum bpf_access_type type
;
3195 int i
, cnt
, delta
= 0;
3197 if (ops
->gen_prologue
) {
3198 cnt
= ops
->gen_prologue(insn_buf
, env
->seen_direct_write
,
3200 if (cnt
>= ARRAY_SIZE(insn_buf
)) {
3201 verbose("bpf verifier is misconfigured\n");
3204 new_prog
= bpf_patch_insn_single(env
->prog
, 0,
3208 env
->prog
= new_prog
;
3213 if (!ops
->convert_ctx_access
)
3216 insn
= env
->prog
->insnsi
+ delta
;
3218 for (i
= 0; i
< insn_cnt
; i
++, insn
++) {
3219 if (insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_B
) ||
3220 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_H
) ||
3221 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_W
) ||
3222 insn
->code
== (BPF_LDX
| BPF_MEM
| BPF_DW
))
3224 else if (insn
->code
== (BPF_STX
| BPF_MEM
| BPF_B
) ||
3225 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_H
) ||
3226 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_W
) ||
3227 insn
->code
== (BPF_STX
| BPF_MEM
| BPF_DW
))
3232 if (env
->insn_aux_data
[i
].ptr_type
!= PTR_TO_CTX
)
3235 cnt
= ops
->convert_ctx_access(type
, insn
, insn_buf
, env
->prog
);
3236 if (cnt
== 0 || cnt
>= ARRAY_SIZE(insn_buf
)) {
3237 verbose("bpf verifier is misconfigured\n");
3241 new_prog
= bpf_patch_insn_single(env
->prog
, i
+ delta
, insn_buf
,
3248 /* keep walking new program and skip insns we just inserted */
3249 env
->prog
= new_prog
;
3250 insn
= new_prog
->insnsi
+ i
+ delta
;
3256 static void free_states(struct bpf_verifier_env
*env
)
3258 struct bpf_verifier_state_list
*sl
, *sln
;
3261 if (!env
->explored_states
)
3264 for (i
= 0; i
< env
->prog
->len
; i
++) {
3265 sl
= env
->explored_states
[i
];
3268 while (sl
!= STATE_LIST_MARK
) {
3275 kfree(env
->explored_states
);
3278 int bpf_check(struct bpf_prog
**prog
, union bpf_attr
*attr
)
3280 char __user
*log_ubuf
= NULL
;
3281 struct bpf_verifier_env
*env
;
3284 /* 'struct bpf_verifier_env' can be global, but since it's not small,
3285 * allocate/free it every time bpf_check() is called
3287 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
3291 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
3294 if (!env
->insn_aux_data
)
3298 /* grab the mutex to protect few globals used by verifier */
3299 mutex_lock(&bpf_verifier_lock
);
3301 if (attr
->log_level
|| attr
->log_buf
|| attr
->log_size
) {
3302 /* user requested verbose verifier output
3303 * and supplied buffer to store the verification trace
3305 log_level
= attr
->log_level
;
3306 log_ubuf
= (char __user
*) (unsigned long) attr
->log_buf
;
3307 log_size
= attr
->log_size
;
3311 /* log_* values have to be sane */
3312 if (log_size
< 128 || log_size
> UINT_MAX
>> 8 ||
3313 log_level
== 0 || log_ubuf
== NULL
)
3317 log_buf
= vmalloc(log_size
);
3324 ret
= replace_map_fd_with_map_ptr(env
);
3326 goto skip_full_check
;
3328 env
->explored_states
= kcalloc(env
->prog
->len
,
3329 sizeof(struct bpf_verifier_state_list
*),
3332 if (!env
->explored_states
)
3333 goto skip_full_check
;
3335 ret
= check_cfg(env
);
3337 goto skip_full_check
;
3339 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
3341 ret
= do_check(env
);
3344 while (pop_stack(env
, NULL
) >= 0);
3348 /* program is valid, convert *(u32*)(ctx + off) accesses */
3349 ret
= convert_ctx_accesses(env
);
3351 if (log_level
&& log_len
>= log_size
- 1) {
3352 BUG_ON(log_len
>= log_size
);
3353 /* verifier log exceeded user supplied buffer */
3355 /* fall through to return what was recorded */
3358 /* copy verifier log back to user space including trailing zero */
3359 if (log_level
&& copy_to_user(log_ubuf
, log_buf
, log_len
+ 1) != 0) {
3364 if (ret
== 0 && env
->used_map_cnt
) {
3365 /* if program passed verifier, update used_maps in bpf_prog_info */
3366 env
->prog
->aux
->used_maps
= kmalloc_array(env
->used_map_cnt
,
3367 sizeof(env
->used_maps
[0]),
3370 if (!env
->prog
->aux
->used_maps
) {
3375 memcpy(env
->prog
->aux
->used_maps
, env
->used_maps
,
3376 sizeof(env
->used_maps
[0]) * env
->used_map_cnt
);
3377 env
->prog
->aux
->used_map_cnt
= env
->used_map_cnt
;
3379 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3380 * bpf_ld_imm64 instructions
3382 convert_pseudo_ld_imm64(env
);
3388 if (!env
->prog
->aux
->used_maps
)
3389 /* if we didn't copy map pointers into bpf_prog_info, release
3390 * them now. Otherwise free_bpf_prog_info() will release them.
3395 mutex_unlock(&bpf_verifier_lock
);
3396 vfree(env
->insn_aux_data
);
3402 int bpf_analyzer(struct bpf_prog
*prog
, const struct bpf_ext_analyzer_ops
*ops
,
3405 struct bpf_verifier_env
*env
;
3408 env
= kzalloc(sizeof(struct bpf_verifier_env
), GFP_KERNEL
);
3412 env
->insn_aux_data
= vzalloc(sizeof(struct bpf_insn_aux_data
) *
3415 if (!env
->insn_aux_data
)
3418 env
->analyzer_ops
= ops
;
3419 env
->analyzer_priv
= priv
;
3421 /* grab the mutex to protect few globals used by verifier */
3422 mutex_lock(&bpf_verifier_lock
);
3426 env
->explored_states
= kcalloc(env
->prog
->len
,
3427 sizeof(struct bpf_verifier_state_list
*),
3430 if (!env
->explored_states
)
3431 goto skip_full_check
;
3433 ret
= check_cfg(env
);
3435 goto skip_full_check
;
3437 env
->allow_ptr_leaks
= capable(CAP_SYS_ADMIN
);
3439 ret
= do_check(env
);
3442 while (pop_stack(env
, NULL
) >= 0);
3445 mutex_unlock(&bpf_verifier_lock
);
3446 vfree(env
->insn_aux_data
);
3451 EXPORT_SYMBOL_GPL(bpf_analyzer
);