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1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016 Facebook
3 *
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.
7 *
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.
12 */
13#include <linux/kernel.h>
14#include <linux/types.h>
15#include <linux/slab.h>
16#include <linux/bpf.h>
17#include <linux/bpf_verifier.h>
18#include <linux/filter.h>
19#include <net/netlink.h>
20#include <linux/file.h>
21#include <linux/vmalloc.h>
22#include <linux/stringify.h>
23
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.
27 *
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 32k 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
39 *
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
43 * copied to R1.
44 *
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
50 *
51 * At the start of BPF program the register R1 contains a pointer to bpf_context
52 * and has type PTR_TO_CTX.
53 *
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.
63 *
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)
67 *
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.
71 *
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.
74 *
75 * registers used to pass values to function calls are checked against
76 * function argument constraints.
77 *
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'
82 *
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,
87 *
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.
92 *
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)
95 * {
96 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
97 * void *key = (void *) (unsigned long) r2;
98 * void *value;
99 *
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.
103 * }
104 *
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
113 *
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.
121 *
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().
126 *
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.
129 */
130
131/* verifier_state + insn_idx are pushed to stack when branch is encountered */
132struct bpf_verifier_stack_elem {
133 /* verifer state is 'st'
134 * before processing instruction 'insn_idx'
135 * and after processing instruction 'prev_insn_idx'
136 */
137 struct bpf_verifier_state st;
138 int insn_idx;
139 int prev_insn_idx;
140 struct bpf_verifier_stack_elem *next;
141};
142
143#define BPF_COMPLEXITY_LIMIT_INSNS 65536
144#define BPF_COMPLEXITY_LIMIT_STACK 1024
145
146struct bpf_call_arg_meta {
147 struct bpf_map *map_ptr;
148 bool raw_mode;
149 bool pkt_access;
150 int regno;
151 int access_size;
152};
153
154/* verbose verifier prints what it's seeing
155 * bpf_check() is called under lock, so no race to access these global vars
156 */
157static u32 log_level, log_size, log_len;
158static char *log_buf;
159
160static DEFINE_MUTEX(bpf_verifier_lock);
161
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
165 */
166static __printf(1, 2) void verbose(const char *fmt, ...)
167{
168 va_list args;
169
170 if (log_level == 0 || log_len >= log_size - 1)
171 return;
172
173 va_start(args, fmt);
174 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
175 va_end(args);
176}
177
178/* string representation of 'enum bpf_reg_type' */
179static const char * const reg_type_str[] = {
180 [NOT_INIT] = "?",
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",
187 [FRAME_PTR] = "fp",
188 [PTR_TO_STACK] = "fp",
189 [CONST_IMM] = "imm",
190 [PTR_TO_PACKET] = "pkt",
191 [PTR_TO_PACKET_END] = "pkt_end",
192};
193
194#define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
195static const char * const func_id_str[] = {
196 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
197};
198#undef __BPF_FUNC_STR_FN
199
200static const char *func_id_name(int id)
201{
202 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
203
204 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
205 return func_id_str[id];
206 else
207 return "unknown";
208}
209
210static void print_verifier_state(struct bpf_verifier_state *state)
211{
212 struct bpf_reg_state *reg;
213 enum bpf_reg_type t;
214 int i;
215
216 for (i = 0; i < MAX_BPF_REG; i++) {
217 reg = &state->regs[i];
218 t = reg->type;
219 if (t == NOT_INIT)
220 continue;
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,
235 reg->id);
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);
242 }
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]);
247 }
248 verbose("\n");
249}
250
251static const char *const bpf_class_string[] = {
252 [BPF_LD] = "ld",
253 [BPF_LDX] = "ldx",
254 [BPF_ST] = "st",
255 [BPF_STX] = "stx",
256 [BPF_ALU] = "alu",
257 [BPF_JMP] = "jmp",
258 [BPF_RET] = "BUG",
259 [BPF_ALU64] = "alu64",
260};
261
262static 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",
277};
278
279static const char *const bpf_ldst_string[] = {
280 [BPF_W >> 3] = "u32",
281 [BPF_H >> 3] = "u16",
282 [BPF_B >> 3] = "u8",
283 [BPF_DW >> 3] = "u64",
284};
285
286static 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",
297};
298
299static void print_bpf_insn(struct bpf_insn *insn)
300{
301 u8 class = BPF_CLASS(insn->code);
302
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) " : "",
307 insn->dst_reg,
308 bpf_alu_string[BPF_OP(insn->code) >> 4],
309 class == BPF_ALU ? "(u32) " : "",
310 insn->src_reg);
311 else
312 verbose("(%02x) %sr%d %s %s%d\n",
313 insn->code, class == BPF_ALU ? "(u32) " : "",
314 insn->dst_reg,
315 bpf_alu_string[BPF_OP(insn->code) >> 4],
316 class == BPF_ALU ? "(u32) " : "",
317 insn->imm);
318 } else if (class == BPF_STX) {
319 if (BPF_MODE(insn->code) == BPF_MEM)
320 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
321 insn->code,
322 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
323 insn->dst_reg,
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",
327 insn->code,
328 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
329 insn->dst_reg, insn->off,
330 insn->src_reg);
331 else
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);
336 return;
337 }
338 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
339 insn->code,
340 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
341 insn->dst_reg,
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);
346 return;
347 }
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",
355 insn->code,
356 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
357 insn->imm);
358 } else if (BPF_MODE(insn->code) == BPF_IND) {
359 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
360 insn->code,
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);
366 } else {
367 verbose("BUG_ld_%02x\n", insn->code);
368 return;
369 }
370 } else if (class == BPF_JMP) {
371 u8 opcode = BPF_OP(insn->code);
372
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);
386 } else {
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);
391 }
392 } else {
393 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
394 }
395}
396
397static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
398{
399 struct bpf_verifier_stack_elem *elem;
400 int insn_idx;
401
402 if (env->head == NULL)
403 return -1;
404
405 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
406 insn_idx = env->head->insn_idx;
407 if (prev_insn_idx)
408 *prev_insn_idx = env->head->prev_insn_idx;
409 elem = env->head->next;
410 kfree(env->head);
411 env->head = elem;
412 env->stack_size--;
413 return insn_idx;
414}
415
416static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
417 int insn_idx, int prev_insn_idx)
418{
419 struct bpf_verifier_stack_elem *elem;
420
421 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
422 if (!elem)
423 goto err;
424
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;
429 env->head = elem;
430 env->stack_size++;
431 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
432 verbose("BPF program is too complex\n");
433 goto err;
434 }
435 return &elem->st;
436err:
437 /* pop all elements and return */
438 while (pop_stack(env, NULL) >= 0);
439 return NULL;
440}
441
442#define CALLER_SAVED_REGS 6
443static 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
445};
446
447static void init_reg_state(struct bpf_reg_state *regs)
448{
449 int i;
450
451 for (i = 0; i < MAX_BPF_REG; i++) {
452 regs[i].type = NOT_INIT;
453 regs[i].imm = 0;
454 regs[i].min_value = BPF_REGISTER_MIN_RANGE;
455 regs[i].max_value = BPF_REGISTER_MAX_RANGE;
456 }
457
458 /* frame pointer */
459 regs[BPF_REG_FP].type = FRAME_PTR;
460
461 /* 1st arg to a function */
462 regs[BPF_REG_1].type = PTR_TO_CTX;
463}
464
465static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
466{
467 regs[regno].type = UNKNOWN_VALUE;
468 regs[regno].id = 0;
469 regs[regno].imm = 0;
470}
471
472static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
473{
474 BUG_ON(regno >= MAX_BPF_REG);
475 __mark_reg_unknown_value(regs, regno);
476}
477
478static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno)
479{
480 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
481 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
482}
483
484enum reg_arg_type {
485 SRC_OP, /* register is used as source operand */
486 DST_OP, /* register is used as destination operand */
487 DST_OP_NO_MARK /* same as above, check only, don't mark */
488};
489
490static int check_reg_arg(struct bpf_reg_state *regs, u32 regno,
491 enum reg_arg_type t)
492{
493 if (regno >= MAX_BPF_REG) {
494 verbose("R%d is invalid\n", regno);
495 return -EINVAL;
496 }
497
498 if (t == SRC_OP) {
499 /* check whether register used as source operand can be read */
500 if (regs[regno].type == NOT_INIT) {
501 verbose("R%d !read_ok\n", regno);
502 return -EACCES;
503 }
504 } else {
505 /* check whether register used as dest operand can be written to */
506 if (regno == BPF_REG_FP) {
507 verbose("frame pointer is read only\n");
508 return -EACCES;
509 }
510 if (t == DST_OP)
511 mark_reg_unknown_value(regs, regno);
512 }
513 return 0;
514}
515
516static int bpf_size_to_bytes(int bpf_size)
517{
518 if (bpf_size == BPF_W)
519 return 4;
520 else if (bpf_size == BPF_H)
521 return 2;
522 else if (bpf_size == BPF_B)
523 return 1;
524 else if (bpf_size == BPF_DW)
525 return 8;
526 else
527 return -EINVAL;
528}
529
530static bool is_spillable_regtype(enum bpf_reg_type type)
531{
532 switch (type) {
533 case PTR_TO_MAP_VALUE:
534 case PTR_TO_MAP_VALUE_OR_NULL:
535 case PTR_TO_STACK:
536 case PTR_TO_CTX:
537 case PTR_TO_PACKET:
538 case PTR_TO_PACKET_END:
539 case FRAME_PTR:
540 case CONST_PTR_TO_MAP:
541 return true;
542 default:
543 return false;
544 }
545}
546
547/* check_stack_read/write functions track spill/fill of registers,
548 * stack boundary and alignment are checked in check_mem_access()
549 */
550static int check_stack_write(struct bpf_verifier_state *state, int off,
551 int size, int value_regno)
552{
553 int i;
554 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
555 * so it's aligned access and [off, off + size) are within stack limits
556 */
557
558 if (value_regno >= 0 &&
559 is_spillable_regtype(state->regs[value_regno].type)) {
560
561 /* register containing pointer is being spilled into stack */
562 if (size != BPF_REG_SIZE) {
563 verbose("invalid size of register spill\n");
564 return -EACCES;
565 }
566
567 /* save register state */
568 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
569 state->regs[value_regno];
570
571 for (i = 0; i < BPF_REG_SIZE; i++)
572 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
573 } else {
574 /* regular write of data into stack */
575 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
576 (struct bpf_reg_state) {};
577
578 for (i = 0; i < size; i++)
579 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
580 }
581 return 0;
582}
583
584static int check_stack_read(struct bpf_verifier_state *state, int off, int size,
585 int value_regno)
586{
587 u8 *slot_type;
588 int i;
589
590 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
591
592 if (slot_type[0] == STACK_SPILL) {
593 if (size != BPF_REG_SIZE) {
594 verbose("invalid size of register spill\n");
595 return -EACCES;
596 }
597 for (i = 1; i < BPF_REG_SIZE; i++) {
598 if (slot_type[i] != STACK_SPILL) {
599 verbose("corrupted spill memory\n");
600 return -EACCES;
601 }
602 }
603
604 if (value_regno >= 0)
605 /* restore register state from stack */
606 state->regs[value_regno] =
607 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
608 return 0;
609 } else {
610 for (i = 0; i < size; i++) {
611 if (slot_type[i] != STACK_MISC) {
612 verbose("invalid read from stack off %d+%d size %d\n",
613 off, i, size);
614 return -EACCES;
615 }
616 }
617 if (value_regno >= 0)
618 /* have read misc data from the stack */
619 mark_reg_unknown_value(state->regs, value_regno);
620 return 0;
621 }
622}
623
624/* check read/write into map element returned by bpf_map_lookup_elem() */
625static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
626 int size)
627{
628 struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
629
630 if (off < 0 || off + size > map->value_size) {
631 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
632 map->value_size, off, size);
633 return -EACCES;
634 }
635 return 0;
636}
637
638#define MAX_PACKET_OFF 0xffff
639
640static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
641 const struct bpf_call_arg_meta *meta,
642 enum bpf_access_type t)
643{
644 switch (env->prog->type) {
645 case BPF_PROG_TYPE_LWT_IN:
646 case BPF_PROG_TYPE_LWT_OUT:
647 /* dst_input() and dst_output() can't write for now */
648 if (t == BPF_WRITE)
649 return false;
650 case BPF_PROG_TYPE_SCHED_CLS:
651 case BPF_PROG_TYPE_SCHED_ACT:
652 case BPF_PROG_TYPE_XDP:
653 case BPF_PROG_TYPE_LWT_XMIT:
654 if (meta)
655 return meta->pkt_access;
656
657 env->seen_direct_write = true;
658 return true;
659 default:
660 return false;
661 }
662}
663
664static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
665 int size)
666{
667 struct bpf_reg_state *regs = env->cur_state.regs;
668 struct bpf_reg_state *reg = ®s[regno];
669
670 off += reg->off;
671 if (off < 0 || size <= 0 || off + size > reg->range) {
672 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
673 off, size, regno, reg->id, reg->off, reg->range);
674 return -EACCES;
675 }
676 return 0;
677}
678
679/* check access to 'struct bpf_context' fields */
680static int check_ctx_access(struct bpf_verifier_env *env, int off, int size,
681 enum bpf_access_type t, enum bpf_reg_type *reg_type)
682{
683 /* for analyzer ctx accesses are already validated and converted */
684 if (env->analyzer_ops)
685 return 0;
686
687 if (env->prog->aux->ops->is_valid_access &&
688 env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) {
689 /* remember the offset of last byte accessed in ctx */
690 if (env->prog->aux->max_ctx_offset < off + size)
691 env->prog->aux->max_ctx_offset = off + size;
692 return 0;
693 }
694
695 verbose("invalid bpf_context access off=%d size=%d\n", off, size);
696 return -EACCES;
697}
698
699static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
700{
701 if (env->allow_ptr_leaks)
702 return false;
703
704 switch (env->cur_state.regs[regno].type) {
705 case UNKNOWN_VALUE:
706 case CONST_IMM:
707 return false;
708 default:
709 return true;
710 }
711}
712
713static int check_ptr_alignment(struct bpf_verifier_env *env,
714 struct bpf_reg_state *reg, int off, int size)
715{
716 if (reg->type != PTR_TO_PACKET && reg->type != PTR_TO_MAP_VALUE_ADJ) {
717 if (off % size != 0) {
718 verbose("misaligned access off %d size %d\n",
719 off, size);
720 return -EACCES;
721 } else {
722 return 0;
723 }
724 }
725
726 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
727 /* misaligned access to packet is ok on x86,arm,arm64 */
728 return 0;
729
730 if (reg->id && size != 1) {
731 verbose("Unknown packet alignment. Only byte-sized access allowed\n");
732 return -EACCES;
733 }
734
735 /* skb->data is NET_IP_ALIGN-ed */
736 if (reg->type == PTR_TO_PACKET &&
737 (NET_IP_ALIGN + reg->off + off) % size != 0) {
738 verbose("misaligned packet access off %d+%d+%d size %d\n",
739 NET_IP_ALIGN, reg->off, off, size);
740 return -EACCES;
741 }
742 return 0;
743}
744
745/* check whether memory at (regno + off) is accessible for t = (read | write)
746 * if t==write, value_regno is a register which value is stored into memory
747 * if t==read, value_regno is a register which will receive the value from memory
748 * if t==write && value_regno==-1, some unknown value is stored into memory
749 * if t==read && value_regno==-1, don't care what we read from memory
750 */
751static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off,
752 int bpf_size, enum bpf_access_type t,
753 int value_regno)
754{
755 struct bpf_verifier_state *state = &env->cur_state;
756 struct bpf_reg_state *reg = &state->regs[regno];
757 int size, err = 0;
758
759 if (reg->type == PTR_TO_STACK)
760 off += reg->imm;
761
762 size = bpf_size_to_bytes(bpf_size);
763 if (size < 0)
764 return size;
765
766 err = check_ptr_alignment(env, reg, off, size);
767 if (err)
768 return err;
769
770 if (reg->type == PTR_TO_MAP_VALUE ||
771 reg->type == PTR_TO_MAP_VALUE_ADJ) {
772 if (t == BPF_WRITE && value_regno >= 0 &&
773 is_pointer_value(env, value_regno)) {
774 verbose("R%d leaks addr into map\n", value_regno);
775 return -EACCES;
776 }
777
778 /* If we adjusted the register to this map value at all then we
779 * need to change off and size to min_value and max_value
780 * respectively to make sure our theoretical access will be
781 * safe.
782 */
783 if (reg->type == PTR_TO_MAP_VALUE_ADJ) {
784 if (log_level)
785 print_verifier_state(state);
786 env->varlen_map_value_access = true;
787 /* The minimum value is only important with signed
788 * comparisons where we can't assume the floor of a
789 * value is 0. If we are using signed variables for our
790 * index'es we need to make sure that whatever we use
791 * will have a set floor within our range.
792 */
793 if (reg->min_value < 0) {
794 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
795 regno);
796 return -EACCES;
797 }
798 err = check_map_access(env, regno, reg->min_value + off,
799 size);
800 if (err) {
801 verbose("R%d min value is outside of the array range\n",
802 regno);
803 return err;
804 }
805
806 /* If we haven't set a max value then we need to bail
807 * since we can't be sure we won't do bad things.
808 */
809 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
810 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
811 regno);
812 return -EACCES;
813 }
814 off += reg->max_value;
815 }
816 err = check_map_access(env, regno, off, size);
817 if (!err && t == BPF_READ && value_regno >= 0)
818 mark_reg_unknown_value(state->regs, value_regno);
819
820 } else if (reg->type == PTR_TO_CTX) {
821 enum bpf_reg_type reg_type = UNKNOWN_VALUE;
822
823 if (t == BPF_WRITE && value_regno >= 0 &&
824 is_pointer_value(env, value_regno)) {
825 verbose("R%d leaks addr into ctx\n", value_regno);
826 return -EACCES;
827 }
828 err = check_ctx_access(env, off, size, t, ®_type);
829 if (!err && t == BPF_READ && value_regno >= 0) {
830 mark_reg_unknown_value(state->regs, value_regno);
831 /* note that reg.[id|off|range] == 0 */
832 state->regs[value_regno].type = reg_type;
833 }
834
835 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) {
836 if (off >= 0 || off < -MAX_BPF_STACK) {
837 verbose("invalid stack off=%d size=%d\n", off, size);
838 return -EACCES;
839 }
840 if (t == BPF_WRITE) {
841 if (!env->allow_ptr_leaks &&
842 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
843 size != BPF_REG_SIZE) {
844 verbose("attempt to corrupt spilled pointer on stack\n");
845 return -EACCES;
846 }
847 err = check_stack_write(state, off, size, value_regno);
848 } else {
849 err = check_stack_read(state, off, size, value_regno);
850 }
851 } else if (state->regs[regno].type == PTR_TO_PACKET) {
852 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
853 verbose("cannot write into packet\n");
854 return -EACCES;
855 }
856 if (t == BPF_WRITE && value_regno >= 0 &&
857 is_pointer_value(env, value_regno)) {
858 verbose("R%d leaks addr into packet\n", value_regno);
859 return -EACCES;
860 }
861 err = check_packet_access(env, regno, off, size);
862 if (!err && t == BPF_READ && value_regno >= 0)
863 mark_reg_unknown_value(state->regs, value_regno);
864 } else {
865 verbose("R%d invalid mem access '%s'\n",
866 regno, reg_type_str[reg->type]);
867 return -EACCES;
868 }
869
870 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks &&
871 state->regs[value_regno].type == UNKNOWN_VALUE) {
872 /* 1 or 2 byte load zero-extends, determine the number of
873 * zero upper bits. Not doing it fo 4 byte load, since
874 * such values cannot be added to ptr_to_packet anyway.
875 */
876 state->regs[value_regno].imm = 64 - size * 8;
877 }
878 return err;
879}
880
881static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn)
882{
883 struct bpf_reg_state *regs = env->cur_state.regs;
884 int err;
885
886 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
887 insn->imm != 0) {
888 verbose("BPF_XADD uses reserved fields\n");
889 return -EINVAL;
890 }
891
892 /* check src1 operand */
893 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
894 if (err)
895 return err;
896
897 /* check src2 operand */
898 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
899 if (err)
900 return err;
901
902 /* check whether atomic_add can read the memory */
903 err = check_mem_access(env, insn->dst_reg, insn->off,
904 BPF_SIZE(insn->code), BPF_READ, -1);
905 if (err)
906 return err;
907
908 /* check whether atomic_add can write into the same memory */
909 return check_mem_access(env, insn->dst_reg, insn->off,
910 BPF_SIZE(insn->code), BPF_WRITE, -1);
911}
912
913/* when register 'regno' is passed into function that will read 'access_size'
914 * bytes from that pointer, make sure that it's within stack boundary
915 * and all elements of stack are initialized
916 */
917static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
918 int access_size, bool zero_size_allowed,
919 struct bpf_call_arg_meta *meta)
920{
921 struct bpf_verifier_state *state = &env->cur_state;
922 struct bpf_reg_state *regs = state->regs;
923 int off, i;
924
925 if (regs[regno].type != PTR_TO_STACK) {
926 if (zero_size_allowed && access_size == 0 &&
927 regs[regno].type == CONST_IMM &&
928 regs[regno].imm == 0)
929 return 0;
930
931 verbose("R%d type=%s expected=%s\n", regno,
932 reg_type_str[regs[regno].type],
933 reg_type_str[PTR_TO_STACK]);
934 return -EACCES;
935 }
936
937 off = regs[regno].imm;
938 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
939 access_size <= 0) {
940 verbose("invalid stack type R%d off=%d access_size=%d\n",
941 regno, off, access_size);
942 return -EACCES;
943 }
944
945 if (meta && meta->raw_mode) {
946 meta->access_size = access_size;
947 meta->regno = regno;
948 return 0;
949 }
950
951 for (i = 0; i < access_size; i++) {
952 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
953 verbose("invalid indirect read from stack off %d+%d size %d\n",
954 off, i, access_size);
955 return -EACCES;
956 }
957 }
958 return 0;
959}
960
961static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
962 enum bpf_arg_type arg_type,
963 struct bpf_call_arg_meta *meta)
964{
965 struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno];
966 enum bpf_reg_type expected_type, type = reg->type;
967 int err = 0;
968
969 if (arg_type == ARG_DONTCARE)
970 return 0;
971
972 if (type == NOT_INIT) {
973 verbose("R%d !read_ok\n", regno);
974 return -EACCES;
975 }
976
977 if (arg_type == ARG_ANYTHING) {
978 if (is_pointer_value(env, regno)) {
979 verbose("R%d leaks addr into helper function\n", regno);
980 return -EACCES;
981 }
982 return 0;
983 }
984
985 if (type == PTR_TO_PACKET &&
986 !may_access_direct_pkt_data(env, meta, BPF_READ)) {
987 verbose("helper access to the packet is not allowed\n");
988 return -EACCES;
989 }
990
991 if (arg_type == ARG_PTR_TO_MAP_KEY ||
992 arg_type == ARG_PTR_TO_MAP_VALUE) {
993 expected_type = PTR_TO_STACK;
994 if (type != PTR_TO_PACKET && type != expected_type)
995 goto err_type;
996 } else if (arg_type == ARG_CONST_STACK_SIZE ||
997 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) {
998 expected_type = CONST_IMM;
999 if (type != expected_type)
1000 goto err_type;
1001 } else if (arg_type == ARG_CONST_MAP_PTR) {
1002 expected_type = CONST_PTR_TO_MAP;
1003 if (type != expected_type)
1004 goto err_type;
1005 } else if (arg_type == ARG_PTR_TO_CTX) {
1006 expected_type = PTR_TO_CTX;
1007 if (type != expected_type)
1008 goto err_type;
1009 } else if (arg_type == ARG_PTR_TO_STACK ||
1010 arg_type == ARG_PTR_TO_RAW_STACK) {
1011 expected_type = PTR_TO_STACK;
1012 /* One exception here. In case function allows for NULL to be
1013 * passed in as argument, it's a CONST_IMM type. Final test
1014 * happens during stack boundary checking.
1015 */
1016 if (type == CONST_IMM && reg->imm == 0)
1017 /* final test in check_stack_boundary() */;
1018 else if (type != PTR_TO_PACKET && type != expected_type)
1019 goto err_type;
1020 meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK;
1021 } else {
1022 verbose("unsupported arg_type %d\n", arg_type);
1023 return -EFAULT;
1024 }
1025
1026 if (arg_type == ARG_CONST_MAP_PTR) {
1027 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1028 meta->map_ptr = reg->map_ptr;
1029 } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
1030 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1031 * check that [key, key + map->key_size) are within
1032 * stack limits and initialized
1033 */
1034 if (!meta->map_ptr) {
1035 /* in function declaration map_ptr must come before
1036 * map_key, so that it's verified and known before
1037 * we have to check map_key here. Otherwise it means
1038 * that kernel subsystem misconfigured verifier
1039 */
1040 verbose("invalid map_ptr to access map->key\n");
1041 return -EACCES;
1042 }
1043 if (type == PTR_TO_PACKET)
1044 err = check_packet_access(env, regno, 0,
1045 meta->map_ptr->key_size);
1046 else
1047 err = check_stack_boundary(env, regno,
1048 meta->map_ptr->key_size,
1049 false, NULL);
1050 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
1051 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1052 * check [value, value + map->value_size) validity
1053 */
1054 if (!meta->map_ptr) {
1055 /* kernel subsystem misconfigured verifier */
1056 verbose("invalid map_ptr to access map->value\n");
1057 return -EACCES;
1058 }
1059 if (type == PTR_TO_PACKET)
1060 err = check_packet_access(env, regno, 0,
1061 meta->map_ptr->value_size);
1062 else
1063 err = check_stack_boundary(env, regno,
1064 meta->map_ptr->value_size,
1065 false, NULL);
1066 } else if (arg_type == ARG_CONST_STACK_SIZE ||
1067 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) {
1068 bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO);
1069
1070 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1071 * from stack pointer 'buf'. Check it
1072 * note: regno == len, regno - 1 == buf
1073 */
1074 if (regno == 0) {
1075 /* kernel subsystem misconfigured verifier */
1076 verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
1077 return -EACCES;
1078 }
1079 if (regs[regno - 1].type == PTR_TO_PACKET)
1080 err = check_packet_access(env, regno - 1, 0, reg->imm);
1081 else
1082 err = check_stack_boundary(env, regno - 1, reg->imm,
1083 zero_size_allowed, meta);
1084 }
1085
1086 return err;
1087err_type:
1088 verbose("R%d type=%s expected=%s\n", regno,
1089 reg_type_str[type], reg_type_str[expected_type]);
1090 return -EACCES;
1091}
1092
1093static int check_map_func_compatibility(struct bpf_map *map, int func_id)
1094{
1095 if (!map)
1096 return 0;
1097
1098 /* We need a two way check, first is from map perspective ... */
1099 switch (map->map_type) {
1100 case BPF_MAP_TYPE_PROG_ARRAY:
1101 if (func_id != BPF_FUNC_tail_call)
1102 goto error;
1103 break;
1104 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
1105 if (func_id != BPF_FUNC_perf_event_read &&
1106 func_id != BPF_FUNC_perf_event_output)
1107 goto error;
1108 break;
1109 case BPF_MAP_TYPE_STACK_TRACE:
1110 if (func_id != BPF_FUNC_get_stackid)
1111 goto error;
1112 break;
1113 case BPF_MAP_TYPE_CGROUP_ARRAY:
1114 if (func_id != BPF_FUNC_skb_under_cgroup &&
1115 func_id != BPF_FUNC_current_task_under_cgroup)
1116 goto error;
1117 break;
1118 default:
1119 break;
1120 }
1121
1122 /* ... and second from the function itself. */
1123 switch (func_id) {
1124 case BPF_FUNC_tail_call:
1125 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
1126 goto error;
1127 break;
1128 case BPF_FUNC_perf_event_read:
1129 case BPF_FUNC_perf_event_output:
1130 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
1131 goto error;
1132 break;
1133 case BPF_FUNC_get_stackid:
1134 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
1135 goto error;
1136 break;
1137 case BPF_FUNC_current_task_under_cgroup:
1138 case BPF_FUNC_skb_under_cgroup:
1139 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
1140 goto error;
1141 break;
1142 default:
1143 break;
1144 }
1145
1146 return 0;
1147error:
1148 verbose("cannot pass map_type %d into func %s#%d\n",
1149 map->map_type, func_id_name(func_id), func_id);
1150 return -EINVAL;
1151}
1152
1153static int check_raw_mode(const struct bpf_func_proto *fn)
1154{
1155 int count = 0;
1156
1157 if (fn->arg1_type == ARG_PTR_TO_RAW_STACK)
1158 count++;
1159 if (fn->arg2_type == ARG_PTR_TO_RAW_STACK)
1160 count++;
1161 if (fn->arg3_type == ARG_PTR_TO_RAW_STACK)
1162 count++;
1163 if (fn->arg4_type == ARG_PTR_TO_RAW_STACK)
1164 count++;
1165 if (fn->arg5_type == ARG_PTR_TO_RAW_STACK)
1166 count++;
1167
1168 return count > 1 ? -EINVAL : 0;
1169}
1170
1171static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
1172{
1173 struct bpf_verifier_state *state = &env->cur_state;
1174 struct bpf_reg_state *regs = state->regs, *reg;
1175 int i;
1176
1177 for (i = 0; i < MAX_BPF_REG; i++)
1178 if (regs[i].type == PTR_TO_PACKET ||
1179 regs[i].type == PTR_TO_PACKET_END)
1180 mark_reg_unknown_value(regs, i);
1181
1182 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1183 if (state->stack_slot_type[i] != STACK_SPILL)
1184 continue;
1185 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1186 if (reg->type != PTR_TO_PACKET &&
1187 reg->type != PTR_TO_PACKET_END)
1188 continue;
1189 reg->type = UNKNOWN_VALUE;
1190 reg->imm = 0;
1191 }
1192}
1193
1194static int check_call(struct bpf_verifier_env *env, int func_id)
1195{
1196 struct bpf_verifier_state *state = &env->cur_state;
1197 const struct bpf_func_proto *fn = NULL;
1198 struct bpf_reg_state *regs = state->regs;
1199 struct bpf_reg_state *reg;
1200 struct bpf_call_arg_meta meta;
1201 bool changes_data;
1202 int i, err;
1203
1204 /* find function prototype */
1205 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
1206 verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
1207 return -EINVAL;
1208 }
1209
1210 if (env->prog->aux->ops->get_func_proto)
1211 fn = env->prog->aux->ops->get_func_proto(func_id);
1212
1213 if (!fn) {
1214 verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
1215 return -EINVAL;
1216 }
1217
1218 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1219 if (!env->prog->gpl_compatible && fn->gpl_only) {
1220 verbose("cannot call GPL only function from proprietary program\n");
1221 return -EINVAL;
1222 }
1223
1224 changes_data = bpf_helper_changes_pkt_data(fn->func);
1225
1226 memset(&meta, 0, sizeof(meta));
1227 meta.pkt_access = fn->pkt_access;
1228
1229 /* We only support one arg being in raw mode at the moment, which
1230 * is sufficient for the helper functions we have right now.
1231 */
1232 err = check_raw_mode(fn);
1233 if (err) {
1234 verbose("kernel subsystem misconfigured func %s#%d\n",
1235 func_id_name(func_id), func_id);
1236 return err;
1237 }
1238
1239 /* check args */
1240 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
1241 if (err)
1242 return err;
1243 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
1244 if (err)
1245 return err;
1246 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
1247 if (err)
1248 return err;
1249 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
1250 if (err)
1251 return err;
1252 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
1253 if (err)
1254 return err;
1255
1256 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1257 * is inferred from register state.
1258 */
1259 for (i = 0; i < meta.access_size; i++) {
1260 err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1);
1261 if (err)
1262 return err;
1263 }
1264
1265 /* reset caller saved regs */
1266 for (i = 0; i < CALLER_SAVED_REGS; i++) {
1267 reg = regs + caller_saved[i];
1268 reg->type = NOT_INIT;
1269 reg->imm = 0;
1270 }
1271
1272 /* update return register */
1273 if (fn->ret_type == RET_INTEGER) {
1274 regs[BPF_REG_0].type = UNKNOWN_VALUE;
1275 } else if (fn->ret_type == RET_VOID) {
1276 regs[BPF_REG_0].type = NOT_INIT;
1277 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
1278 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
1279 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0;
1280 /* remember map_ptr, so that check_map_access()
1281 * can check 'value_size' boundary of memory access
1282 * to map element returned from bpf_map_lookup_elem()
1283 */
1284 if (meta.map_ptr == NULL) {
1285 verbose("kernel subsystem misconfigured verifier\n");
1286 return -EINVAL;
1287 }
1288 regs[BPF_REG_0].map_ptr = meta.map_ptr;
1289 regs[BPF_REG_0].id = ++env->id_gen;
1290 } else {
1291 verbose("unknown return type %d of func %s#%d\n",
1292 fn->ret_type, func_id_name(func_id), func_id);
1293 return -EINVAL;
1294 }
1295
1296 err = check_map_func_compatibility(meta.map_ptr, func_id);
1297 if (err)
1298 return err;
1299
1300 if (changes_data)
1301 clear_all_pkt_pointers(env);
1302 return 0;
1303}
1304
1305static int check_packet_ptr_add(struct bpf_verifier_env *env,
1306 struct bpf_insn *insn)
1307{
1308 struct bpf_reg_state *regs = env->cur_state.regs;
1309 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1310 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1311 struct bpf_reg_state tmp_reg;
1312 s32 imm;
1313
1314 if (BPF_SRC(insn->code) == BPF_K) {
1315 /* pkt_ptr += imm */
1316 imm = insn->imm;
1317
1318add_imm:
1319 if (imm <= 0) {
1320 verbose("addition of negative constant to packet pointer is not allowed\n");
1321 return -EACCES;
1322 }
1323 if (imm >= MAX_PACKET_OFF ||
1324 imm + dst_reg->off >= MAX_PACKET_OFF) {
1325 verbose("constant %d is too large to add to packet pointer\n",
1326 imm);
1327 return -EACCES;
1328 }
1329 /* a constant was added to pkt_ptr.
1330 * Remember it while keeping the same 'id'
1331 */
1332 dst_reg->off += imm;
1333 } else {
1334 if (src_reg->type == PTR_TO_PACKET) {
1335 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1336 tmp_reg = *dst_reg; /* save r7 state */
1337 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
1338 src_reg = &tmp_reg; /* pretend it's src_reg state */
1339 /* if the checks below reject it, the copy won't matter,
1340 * since we're rejecting the whole program. If all ok,
1341 * then imm22 state will be added to r7
1342 * and r7 will be pkt(id=0,off=22,r=62) while
1343 * r6 will stay as pkt(id=0,off=0,r=62)
1344 */
1345 }
1346
1347 if (src_reg->type == CONST_IMM) {
1348 /* pkt_ptr += reg where reg is known constant */
1349 imm = src_reg->imm;
1350 goto add_imm;
1351 }
1352 /* disallow pkt_ptr += reg
1353 * if reg is not uknown_value with guaranteed zero upper bits
1354 * otherwise pkt_ptr may overflow and addition will become
1355 * subtraction which is not allowed
1356 */
1357 if (src_reg->type != UNKNOWN_VALUE) {
1358 verbose("cannot add '%s' to ptr_to_packet\n",
1359 reg_type_str[src_reg->type]);
1360 return -EACCES;
1361 }
1362 if (src_reg->imm < 48) {
1363 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1364 src_reg->imm);
1365 return -EACCES;
1366 }
1367 /* dst_reg stays as pkt_ptr type and since some positive
1368 * integer value was added to the pointer, increment its 'id'
1369 */
1370 dst_reg->id = ++env->id_gen;
1371
1372 /* something was added to pkt_ptr, set range and off to zero */
1373 dst_reg->off = 0;
1374 dst_reg->range = 0;
1375 }
1376 return 0;
1377}
1378
1379static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
1380{
1381 struct bpf_reg_state *regs = env->cur_state.regs;
1382 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1383 u8 opcode = BPF_OP(insn->code);
1384 s64 imm_log2;
1385
1386 /* for type == UNKNOWN_VALUE:
1387 * imm > 0 -> number of zero upper bits
1388 * imm == 0 -> don't track which is the same as all bits can be non-zero
1389 */
1390
1391 if (BPF_SRC(insn->code) == BPF_X) {
1392 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1393
1394 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 &&
1395 dst_reg->imm && opcode == BPF_ADD) {
1396 /* dreg += sreg
1397 * where both have zero upper bits. Adding them
1398 * can only result making one more bit non-zero
1399 * in the larger value.
1400 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1401 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1402 */
1403 dst_reg->imm = min(dst_reg->imm, src_reg->imm);
1404 dst_reg->imm--;
1405 return 0;
1406 }
1407 if (src_reg->type == CONST_IMM && src_reg->imm > 0 &&
1408 dst_reg->imm && opcode == BPF_ADD) {
1409 /* dreg += sreg
1410 * where dreg has zero upper bits and sreg is const.
1411 * Adding them can only result making one more bit
1412 * non-zero in the larger value.
1413 */
1414 imm_log2 = __ilog2_u64((long long)src_reg->imm);
1415 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1416 dst_reg->imm--;
1417 return 0;
1418 }
1419 /* all other cases non supported yet, just mark dst_reg */
1420 dst_reg->imm = 0;
1421 return 0;
1422 }
1423
1424 /* sign extend 32-bit imm into 64-bit to make sure that
1425 * negative values occupy bit 63. Note ilog2() would have
1426 * been incorrect, since sizeof(insn->imm) == 4
1427 */
1428 imm_log2 = __ilog2_u64((long long)insn->imm);
1429
1430 if (dst_reg->imm && opcode == BPF_LSH) {
1431 /* reg <<= imm
1432 * if reg was a result of 2 byte load, then its imm == 48
1433 * which means that upper 48 bits are zero and shifting this reg
1434 * left by 4 would mean that upper 44 bits are still zero
1435 */
1436 dst_reg->imm -= insn->imm;
1437 } else if (dst_reg->imm && opcode == BPF_MUL) {
1438 /* reg *= imm
1439 * if multiplying by 14 subtract 4
1440 * This is conservative calculation of upper zero bits.
1441 * It's not trying to special case insn->imm == 1 or 0 cases
1442 */
1443 dst_reg->imm -= imm_log2 + 1;
1444 } else if (opcode == BPF_AND) {
1445 /* reg &= imm */
1446 dst_reg->imm = 63 - imm_log2;
1447 } else if (dst_reg->imm && opcode == BPF_ADD) {
1448 /* reg += imm */
1449 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1450 dst_reg->imm--;
1451 } else if (opcode == BPF_RSH) {
1452 /* reg >>= imm
1453 * which means that after right shift, upper bits will be zero
1454 * note that verifier already checked that
1455 * 0 <= imm < 64 for shift insn
1456 */
1457 dst_reg->imm += insn->imm;
1458 if (unlikely(dst_reg->imm > 64))
1459 /* some dumb code did:
1460 * r2 = *(u32 *)mem;
1461 * r2 >>= 32;
1462 * and all bits are zero now */
1463 dst_reg->imm = 64;
1464 } else {
1465 /* all other alu ops, means that we don't know what will
1466 * happen to the value, mark it with unknown number of zero bits
1467 */
1468 dst_reg->imm = 0;
1469 }
1470
1471 if (dst_reg->imm < 0) {
1472 /* all 64 bits of the register can contain non-zero bits
1473 * and such value cannot be added to ptr_to_packet, since it
1474 * may overflow, mark it as unknown to avoid further eval
1475 */
1476 dst_reg->imm = 0;
1477 }
1478 return 0;
1479}
1480
1481static int evaluate_reg_imm_alu(struct bpf_verifier_env *env,
1482 struct bpf_insn *insn)
1483{
1484 struct bpf_reg_state *regs = env->cur_state.regs;
1485 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg];
1486 struct bpf_reg_state *src_reg = ®s[insn->src_reg];
1487 u8 opcode = BPF_OP(insn->code);
1488
1489 /* dst_reg->type == CONST_IMM here, simulate execution of 'add'/'or'
1490 * insn. Don't care about overflow or negative values, just add them
1491 */
1492 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K)
1493 dst_reg->imm += insn->imm;
1494 else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X &&
1495 src_reg->type == CONST_IMM)
1496 dst_reg->imm += src_reg->imm;
1497 else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K)
1498 dst_reg->imm |= insn->imm;
1499 else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X &&
1500 src_reg->type == CONST_IMM)
1501 dst_reg->imm |= src_reg->imm;
1502 else
1503 mark_reg_unknown_value(regs, insn->dst_reg);
1504 return 0;
1505}
1506
1507static void check_reg_overflow(struct bpf_reg_state *reg)
1508{
1509 if (reg->max_value > BPF_REGISTER_MAX_RANGE)
1510 reg->max_value = BPF_REGISTER_MAX_RANGE;
1511 if (reg->min_value < BPF_REGISTER_MIN_RANGE ||
1512 reg->min_value > BPF_REGISTER_MAX_RANGE)
1513 reg->min_value = BPF_REGISTER_MIN_RANGE;
1514}
1515
1516static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
1517 struct bpf_insn *insn)
1518{
1519 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1520 s64 min_val = BPF_REGISTER_MIN_RANGE;
1521 u64 max_val = BPF_REGISTER_MAX_RANGE;
1522 u8 opcode = BPF_OP(insn->code);
1523
1524 dst_reg = ®s[insn->dst_reg];
1525 if (BPF_SRC(insn->code) == BPF_X) {
1526 check_reg_overflow(®s[insn->src_reg]);
1527 min_val = regs[insn->src_reg].min_value;
1528 max_val = regs[insn->src_reg].max_value;
1529
1530 /* If the source register is a random pointer then the
1531 * min_value/max_value values represent the range of the known
1532 * accesses into that value, not the actual min/max value of the
1533 * register itself. In this case we have to reset the reg range
1534 * values so we know it is not safe to look at.
1535 */
1536 if (regs[insn->src_reg].type != CONST_IMM &&
1537 regs[insn->src_reg].type != UNKNOWN_VALUE) {
1538 min_val = BPF_REGISTER_MIN_RANGE;
1539 max_val = BPF_REGISTER_MAX_RANGE;
1540 }
1541 } else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
1542 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
1543 min_val = max_val = insn->imm;
1544 }
1545
1546 /* We don't know anything about what was done to this register, mark it
1547 * as unknown.
1548 */
1549 if (min_val == BPF_REGISTER_MIN_RANGE &&
1550 max_val == BPF_REGISTER_MAX_RANGE) {
1551 reset_reg_range_values(regs, insn->dst_reg);
1552 return;
1553 }
1554
1555 /* If one of our values was at the end of our ranges then we can't just
1556 * do our normal operations to the register, we need to set the values
1557 * to the min/max since they are undefined.
1558 */
1559 if (min_val == BPF_REGISTER_MIN_RANGE)
1560 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1561 if (max_val == BPF_REGISTER_MAX_RANGE)
1562 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1563
1564 switch (opcode) {
1565 case BPF_ADD:
1566 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1567 dst_reg->min_value += min_val;
1568 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1569 dst_reg->max_value += max_val;
1570 break;
1571 case BPF_SUB:
1572 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1573 dst_reg->min_value -= min_val;
1574 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1575 dst_reg->max_value -= max_val;
1576 break;
1577 case BPF_MUL:
1578 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1579 dst_reg->min_value *= min_val;
1580 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1581 dst_reg->max_value *= max_val;
1582 break;
1583 case BPF_AND:
1584 /* Disallow AND'ing of negative numbers, ain't nobody got time
1585 * for that. Otherwise the minimum is 0 and the max is the max
1586 * value we could AND against.
1587 */
1588 if (min_val < 0)
1589 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1590 else
1591 dst_reg->min_value = 0;
1592 dst_reg->max_value = max_val;
1593 break;
1594 case BPF_LSH:
1595 /* Gotta have special overflow logic here, if we're shifting
1596 * more than MAX_RANGE then just assume we have an invalid
1597 * range.
1598 */
1599 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE))
1600 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1601 else if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1602 dst_reg->min_value <<= min_val;
1603
1604 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE))
1605 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1606 else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1607 dst_reg->max_value <<= max_val;
1608 break;
1609 case BPF_RSH:
1610 /* RSH by a negative number is undefined, and the BPF_RSH is an
1611 * unsigned shift, so make the appropriate casts.
1612 */
1613 if (min_val < 0 || dst_reg->min_value < 0)
1614 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1615 else
1616 dst_reg->min_value =
1617 (u64)(dst_reg->min_value) >> min_val;
1618 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1619 dst_reg->max_value >>= max_val;
1620 break;
1621 default:
1622 reset_reg_range_values(regs, insn->dst_reg);
1623 break;
1624 }
1625
1626 check_reg_overflow(dst_reg);
1627}
1628
1629/* check validity of 32-bit and 64-bit arithmetic operations */
1630static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
1631{
1632 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1633 u8 opcode = BPF_OP(insn->code);
1634 int err;
1635
1636 if (opcode == BPF_END || opcode == BPF_NEG) {
1637 if (opcode == BPF_NEG) {
1638 if (BPF_SRC(insn->code) != 0 ||
1639 insn->src_reg != BPF_REG_0 ||
1640 insn->off != 0 || insn->imm != 0) {
1641 verbose("BPF_NEG uses reserved fields\n");
1642 return -EINVAL;
1643 }
1644 } else {
1645 if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
1646 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
1647 verbose("BPF_END uses reserved fields\n");
1648 return -EINVAL;
1649 }
1650 }
1651
1652 /* check src operand */
1653 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1654 if (err)
1655 return err;
1656
1657 if (is_pointer_value(env, insn->dst_reg)) {
1658 verbose("R%d pointer arithmetic prohibited\n",
1659 insn->dst_reg);
1660 return -EACCES;
1661 }
1662
1663 /* check dest operand */
1664 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1665 if (err)
1666 return err;
1667
1668 } else if (opcode == BPF_MOV) {
1669
1670 if (BPF_SRC(insn->code) == BPF_X) {
1671 if (insn->imm != 0 || insn->off != 0) {
1672 verbose("BPF_MOV uses reserved fields\n");
1673 return -EINVAL;
1674 }
1675
1676 /* check src operand */
1677 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1678 if (err)
1679 return err;
1680 } else {
1681 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1682 verbose("BPF_MOV uses reserved fields\n");
1683 return -EINVAL;
1684 }
1685 }
1686
1687 /* check dest operand */
1688 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1689 if (err)
1690 return err;
1691
1692 /* we are setting our register to something new, we need to
1693 * reset its range values.
1694 */
1695 reset_reg_range_values(regs, insn->dst_reg);
1696
1697 if (BPF_SRC(insn->code) == BPF_X) {
1698 if (BPF_CLASS(insn->code) == BPF_ALU64) {
1699 /* case: R1 = R2
1700 * copy register state to dest reg
1701 */
1702 regs[insn->dst_reg] = regs[insn->src_reg];
1703 } else {
1704 if (is_pointer_value(env, insn->src_reg)) {
1705 verbose("R%d partial copy of pointer\n",
1706 insn->src_reg);
1707 return -EACCES;
1708 }
1709 mark_reg_unknown_value(regs, insn->dst_reg);
1710 }
1711 } else {
1712 /* case: R = imm
1713 * remember the value we stored into this reg
1714 */
1715 regs[insn->dst_reg].type = CONST_IMM;
1716 regs[insn->dst_reg].imm = insn->imm;
1717 regs[insn->dst_reg].max_value = insn->imm;
1718 regs[insn->dst_reg].min_value = insn->imm;
1719 }
1720
1721 } else if (opcode > BPF_END) {
1722 verbose("invalid BPF_ALU opcode %x\n", opcode);
1723 return -EINVAL;
1724
1725 } else { /* all other ALU ops: and, sub, xor, add, ... */
1726
1727 if (BPF_SRC(insn->code) == BPF_X) {
1728 if (insn->imm != 0 || insn->off != 0) {
1729 verbose("BPF_ALU uses reserved fields\n");
1730 return -EINVAL;
1731 }
1732 /* check src1 operand */
1733 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1734 if (err)
1735 return err;
1736 } else {
1737 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1738 verbose("BPF_ALU uses reserved fields\n");
1739 return -EINVAL;
1740 }
1741 }
1742
1743 /* check src2 operand */
1744 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1745 if (err)
1746 return err;
1747
1748 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
1749 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
1750 verbose("div by zero\n");
1751 return -EINVAL;
1752 }
1753
1754 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
1755 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
1756 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
1757
1758 if (insn->imm < 0 || insn->imm >= size) {
1759 verbose("invalid shift %d\n", insn->imm);
1760 return -EINVAL;
1761 }
1762 }
1763
1764 /* check dest operand */
1765 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
1766 if (err)
1767 return err;
1768
1769 dst_reg = ®s[insn->dst_reg];
1770
1771 /* first we want to adjust our ranges. */
1772 adjust_reg_min_max_vals(env, insn);
1773
1774 /* pattern match 'bpf_add Rx, imm' instruction */
1775 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
1776 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) {
1777 dst_reg->type = PTR_TO_STACK;
1778 dst_reg->imm = insn->imm;
1779 return 0;
1780 } else if (opcode == BPF_ADD &&
1781 BPF_CLASS(insn->code) == BPF_ALU64 &&
1782 (dst_reg->type == PTR_TO_PACKET ||
1783 (BPF_SRC(insn->code) == BPF_X &&
1784 regs[insn->src_reg].type == PTR_TO_PACKET))) {
1785 /* ptr_to_packet += K|X */
1786 return check_packet_ptr_add(env, insn);
1787 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
1788 dst_reg->type == UNKNOWN_VALUE &&
1789 env->allow_ptr_leaks) {
1790 /* unknown += K|X */
1791 return evaluate_reg_alu(env, insn);
1792 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
1793 dst_reg->type == CONST_IMM &&
1794 env->allow_ptr_leaks) {
1795 /* reg_imm += K|X */
1796 return evaluate_reg_imm_alu(env, insn);
1797 } else if (is_pointer_value(env, insn->dst_reg)) {
1798 verbose("R%d pointer arithmetic prohibited\n",
1799 insn->dst_reg);
1800 return -EACCES;
1801 } else if (BPF_SRC(insn->code) == BPF_X &&
1802 is_pointer_value(env, insn->src_reg)) {
1803 verbose("R%d pointer arithmetic prohibited\n",
1804 insn->src_reg);
1805 return -EACCES;
1806 }
1807
1808 /* If we did pointer math on a map value then just set it to our
1809 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
1810 * loads to this register appropriately, otherwise just mark the
1811 * register as unknown.
1812 */
1813 if (env->allow_ptr_leaks &&
1814 (dst_reg->type == PTR_TO_MAP_VALUE ||
1815 dst_reg->type == PTR_TO_MAP_VALUE_ADJ))
1816 dst_reg->type = PTR_TO_MAP_VALUE_ADJ;
1817 else
1818 mark_reg_unknown_value(regs, insn->dst_reg);
1819 }
1820
1821 return 0;
1822}
1823
1824static void find_good_pkt_pointers(struct bpf_verifier_state *state,
1825 struct bpf_reg_state *dst_reg)
1826{
1827 struct bpf_reg_state *regs = state->regs, *reg;
1828 int i;
1829
1830 /* LLVM can generate two kind of checks:
1831 *
1832 * Type 1:
1833 *
1834 * r2 = r3;
1835 * r2 += 8;
1836 * if (r2 > pkt_end) goto <handle exception>
1837 * <access okay>
1838 *
1839 * Where:
1840 * r2 == dst_reg, pkt_end == src_reg
1841 * r2=pkt(id=n,off=8,r=0)
1842 * r3=pkt(id=n,off=0,r=0)
1843 *
1844 * Type 2:
1845 *
1846 * r2 = r3;
1847 * r2 += 8;
1848 * if (pkt_end >= r2) goto <access okay>
1849 * <handle exception>
1850 *
1851 * Where:
1852 * pkt_end == dst_reg, r2 == src_reg
1853 * r2=pkt(id=n,off=8,r=0)
1854 * r3=pkt(id=n,off=0,r=0)
1855 *
1856 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
1857 * so that range of bytes [r3, r3 + 8) is safe to access.
1858 */
1859
1860 for (i = 0; i < MAX_BPF_REG; i++)
1861 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id)
1862 regs[i].range = dst_reg->off;
1863
1864 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1865 if (state->stack_slot_type[i] != STACK_SPILL)
1866 continue;
1867 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1868 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id)
1869 reg->range = dst_reg->off;
1870 }
1871}
1872
1873/* Adjusts the register min/max values in the case that the dst_reg is the
1874 * variable register that we are working on, and src_reg is a constant or we're
1875 * simply doing a BPF_K check.
1876 */
1877static void reg_set_min_max(struct bpf_reg_state *true_reg,
1878 struct bpf_reg_state *false_reg, u64 val,
1879 u8 opcode)
1880{
1881 switch (opcode) {
1882 case BPF_JEQ:
1883 /* If this is false then we know nothing Jon Snow, but if it is
1884 * true then we know for sure.
1885 */
1886 true_reg->max_value = true_reg->min_value = val;
1887 break;
1888 case BPF_JNE:
1889 /* If this is true we know nothing Jon Snow, but if it is false
1890 * we know the value for sure;
1891 */
1892 false_reg->max_value = false_reg->min_value = val;
1893 break;
1894 case BPF_JGT:
1895 /* Unsigned comparison, the minimum value is 0. */
1896 false_reg->min_value = 0;
1897 case BPF_JSGT:
1898 /* If this is false then we know the maximum val is val,
1899 * otherwise we know the min val is val+1.
1900 */
1901 false_reg->max_value = val;
1902 true_reg->min_value = val + 1;
1903 break;
1904 case BPF_JGE:
1905 /* Unsigned comparison, the minimum value is 0. */
1906 false_reg->min_value = 0;
1907 case BPF_JSGE:
1908 /* If this is false then we know the maximum value is val - 1,
1909 * otherwise we know the mimimum value is val.
1910 */
1911 false_reg->max_value = val - 1;
1912 true_reg->min_value = val;
1913 break;
1914 default:
1915 break;
1916 }
1917
1918 check_reg_overflow(false_reg);
1919 check_reg_overflow(true_reg);
1920}
1921
1922/* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
1923 * is the variable reg.
1924 */
1925static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
1926 struct bpf_reg_state *false_reg, u64 val,
1927 u8 opcode)
1928{
1929 switch (opcode) {
1930 case BPF_JEQ:
1931 /* If this is false then we know nothing Jon Snow, but if it is
1932 * true then we know for sure.
1933 */
1934 true_reg->max_value = true_reg->min_value = val;
1935 break;
1936 case BPF_JNE:
1937 /* If this is true we know nothing Jon Snow, but if it is false
1938 * we know the value for sure;
1939 */
1940 false_reg->max_value = false_reg->min_value = val;
1941 break;
1942 case BPF_JGT:
1943 /* Unsigned comparison, the minimum value is 0. */
1944 true_reg->min_value = 0;
1945 case BPF_JSGT:
1946 /*
1947 * If this is false, then the val is <= the register, if it is
1948 * true the register <= to the val.
1949 */
1950 false_reg->min_value = val;
1951 true_reg->max_value = val - 1;
1952 break;
1953 case BPF_JGE:
1954 /* Unsigned comparison, the minimum value is 0. */
1955 true_reg->min_value = 0;
1956 case BPF_JSGE:
1957 /* If this is false then constant < register, if it is true then
1958 * the register < constant.
1959 */
1960 false_reg->min_value = val + 1;
1961 true_reg->max_value = val;
1962 break;
1963 default:
1964 break;
1965 }
1966
1967 check_reg_overflow(false_reg);
1968 check_reg_overflow(true_reg);
1969}
1970
1971static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
1972 enum bpf_reg_type type)
1973{
1974 struct bpf_reg_state *reg = ®s[regno];
1975
1976 if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
1977 reg->type = type;
1978 /* We don't need id from this point onwards anymore, thus we
1979 * should better reset it, so that state pruning has chances
1980 * to take effect.
1981 */
1982 reg->id = 0;
1983 if (type == UNKNOWN_VALUE)
1984 __mark_reg_unknown_value(regs, regno);
1985 }
1986}
1987
1988/* The logic is similar to find_good_pkt_pointers(), both could eventually
1989 * be folded together at some point.
1990 */
1991static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
1992 enum bpf_reg_type type)
1993{
1994 struct bpf_reg_state *regs = state->regs;
1995 u32 id = regs[regno].id;
1996 int i;
1997
1998 for (i = 0; i < MAX_BPF_REG; i++)
1999 mark_map_reg(regs, i, id, type);
2000
2001 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
2002 if (state->stack_slot_type[i] != STACK_SPILL)
2003 continue;
2004 mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type);
2005 }
2006}
2007
2008static int check_cond_jmp_op(struct bpf_verifier_env *env,
2009 struct bpf_insn *insn, int *insn_idx)
2010{
2011 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
2012 struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
2013 u8 opcode = BPF_OP(insn->code);
2014 int err;
2015
2016 if (opcode > BPF_EXIT) {
2017 verbose("invalid BPF_JMP opcode %x\n", opcode);
2018 return -EINVAL;
2019 }
2020
2021 if (BPF_SRC(insn->code) == BPF_X) {
2022 if (insn->imm != 0) {
2023 verbose("BPF_JMP uses reserved fields\n");
2024 return -EINVAL;
2025 }
2026
2027 /* check src1 operand */
2028 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2029 if (err)
2030 return err;
2031
2032 if (is_pointer_value(env, insn->src_reg)) {
2033 verbose("R%d pointer comparison prohibited\n",
2034 insn->src_reg);
2035 return -EACCES;
2036 }
2037 } else {
2038 if (insn->src_reg != BPF_REG_0) {
2039 verbose("BPF_JMP uses reserved fields\n");
2040 return -EINVAL;
2041 }
2042 }
2043
2044 /* check src2 operand */
2045 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2046 if (err)
2047 return err;
2048
2049 dst_reg = ®s[insn->dst_reg];
2050
2051 /* detect if R == 0 where R was initialized to zero earlier */
2052 if (BPF_SRC(insn->code) == BPF_K &&
2053 (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2054 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) {
2055 if (opcode == BPF_JEQ) {
2056 /* if (imm == imm) goto pc+off;
2057 * only follow the goto, ignore fall-through
2058 */
2059 *insn_idx += insn->off;
2060 return 0;
2061 } else {
2062 /* if (imm != imm) goto pc+off;
2063 * only follow fall-through branch, since
2064 * that's where the program will go
2065 */
2066 return 0;
2067 }
2068 }
2069
2070 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
2071 if (!other_branch)
2072 return -EFAULT;
2073
2074 /* detect if we are comparing against a constant value so we can adjust
2075 * our min/max values for our dst register.
2076 */
2077 if (BPF_SRC(insn->code) == BPF_X) {
2078 if (regs[insn->src_reg].type == CONST_IMM)
2079 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2080 dst_reg, regs[insn->src_reg].imm,
2081 opcode);
2082 else if (dst_reg->type == CONST_IMM)
2083 reg_set_min_max_inv(&other_branch->regs[insn->src_reg],
2084 ®s[insn->src_reg], dst_reg->imm,
2085 opcode);
2086 } else {
2087 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2088 dst_reg, insn->imm, opcode);
2089 }
2090
2091 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
2092 if (BPF_SRC(insn->code) == BPF_K &&
2093 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2094 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
2095 /* Mark all identical map registers in each branch as either
2096 * safe or unknown depending R == 0 or R != 0 conditional.
2097 */
2098 mark_map_regs(this_branch, insn->dst_reg,
2099 opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE);
2100 mark_map_regs(other_branch, insn->dst_reg,
2101 opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE);
2102 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
2103 dst_reg->type == PTR_TO_PACKET &&
2104 regs[insn->src_reg].type == PTR_TO_PACKET_END) {
2105 find_good_pkt_pointers(this_branch, dst_reg);
2106 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
2107 dst_reg->type == PTR_TO_PACKET_END &&
2108 regs[insn->src_reg].type == PTR_TO_PACKET) {
2109 find_good_pkt_pointers(other_branch, ®s[insn->src_reg]);
2110 } else if (is_pointer_value(env, insn->dst_reg)) {
2111 verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
2112 return -EACCES;
2113 }
2114 if (log_level)
2115 print_verifier_state(this_branch);
2116 return 0;
2117}
2118
2119/* return the map pointer stored inside BPF_LD_IMM64 instruction */
2120static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
2121{
2122 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
2123
2124 return (struct bpf_map *) (unsigned long) imm64;
2125}
2126
2127/* verify BPF_LD_IMM64 instruction */
2128static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
2129{
2130 struct bpf_reg_state *regs = env->cur_state.regs;
2131 int err;
2132
2133 if (BPF_SIZE(insn->code) != BPF_DW) {
2134 verbose("invalid BPF_LD_IMM insn\n");
2135 return -EINVAL;
2136 }
2137 if (insn->off != 0) {
2138 verbose("BPF_LD_IMM64 uses reserved fields\n");
2139 return -EINVAL;
2140 }
2141
2142 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2143 if (err)
2144 return err;
2145
2146 if (insn->src_reg == 0) {
2147 /* generic move 64-bit immediate into a register,
2148 * only analyzer needs to collect the ld_imm value.
2149 */
2150 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
2151
2152 if (!env->analyzer_ops)
2153 return 0;
2154
2155 regs[insn->dst_reg].type = CONST_IMM;
2156 regs[insn->dst_reg].imm = imm;
2157 return 0;
2158 }
2159
2160 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2161 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
2162
2163 regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
2164 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
2165 return 0;
2166}
2167
2168static bool may_access_skb(enum bpf_prog_type type)
2169{
2170 switch (type) {
2171 case BPF_PROG_TYPE_SOCKET_FILTER:
2172 case BPF_PROG_TYPE_SCHED_CLS:
2173 case BPF_PROG_TYPE_SCHED_ACT:
2174 return true;
2175 default:
2176 return false;
2177 }
2178}
2179
2180/* verify safety of LD_ABS|LD_IND instructions:
2181 * - they can only appear in the programs where ctx == skb
2182 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2183 * preserve R6-R9, and store return value into R0
2184 *
2185 * Implicit input:
2186 * ctx == skb == R6 == CTX
2187 *
2188 * Explicit input:
2189 * SRC == any register
2190 * IMM == 32-bit immediate
2191 *
2192 * Output:
2193 * R0 - 8/16/32-bit skb data converted to cpu endianness
2194 */
2195static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
2196{
2197 struct bpf_reg_state *regs = env->cur_state.regs;
2198 u8 mode = BPF_MODE(insn->code);
2199 struct bpf_reg_state *reg;
2200 int i, err;
2201
2202 if (!may_access_skb(env->prog->type)) {
2203 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
2204 return -EINVAL;
2205 }
2206
2207 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
2208 BPF_SIZE(insn->code) == BPF_DW ||
2209 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
2210 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
2211 return -EINVAL;
2212 }
2213
2214 /* check whether implicit source operand (register R6) is readable */
2215 err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
2216 if (err)
2217 return err;
2218
2219 if (regs[BPF_REG_6].type != PTR_TO_CTX) {
2220 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2221 return -EINVAL;
2222 }
2223
2224 if (mode == BPF_IND) {
2225 /* check explicit source operand */
2226 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2227 if (err)
2228 return err;
2229 }
2230
2231 /* reset caller saved regs to unreadable */
2232 for (i = 0; i < CALLER_SAVED_REGS; i++) {
2233 reg = regs + caller_saved[i];
2234 reg->type = NOT_INIT;
2235 reg->imm = 0;
2236 }
2237
2238 /* mark destination R0 register as readable, since it contains
2239 * the value fetched from the packet
2240 */
2241 regs[BPF_REG_0].type = UNKNOWN_VALUE;
2242 return 0;
2243}
2244
2245/* non-recursive DFS pseudo code
2246 * 1 procedure DFS-iterative(G,v):
2247 * 2 label v as discovered
2248 * 3 let S be a stack
2249 * 4 S.push(v)
2250 * 5 while S is not empty
2251 * 6 t <- S.pop()
2252 * 7 if t is what we're looking for:
2253 * 8 return t
2254 * 9 for all edges e in G.adjacentEdges(t) do
2255 * 10 if edge e is already labelled
2256 * 11 continue with the next edge
2257 * 12 w <- G.adjacentVertex(t,e)
2258 * 13 if vertex w is not discovered and not explored
2259 * 14 label e as tree-edge
2260 * 15 label w as discovered
2261 * 16 S.push(w)
2262 * 17 continue at 5
2263 * 18 else if vertex w is discovered
2264 * 19 label e as back-edge
2265 * 20 else
2266 * 21 // vertex w is explored
2267 * 22 label e as forward- or cross-edge
2268 * 23 label t as explored
2269 * 24 S.pop()
2270 *
2271 * convention:
2272 * 0x10 - discovered
2273 * 0x11 - discovered and fall-through edge labelled
2274 * 0x12 - discovered and fall-through and branch edges labelled
2275 * 0x20 - explored
2276 */
2277
2278enum {
2279 DISCOVERED = 0x10,
2280 EXPLORED = 0x20,
2281 FALLTHROUGH = 1,
2282 BRANCH = 2,
2283};
2284
2285#define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
2286
2287static int *insn_stack; /* stack of insns to process */
2288static int cur_stack; /* current stack index */
2289static int *insn_state;
2290
2291/* t, w, e - match pseudo-code above:
2292 * t - index of current instruction
2293 * w - next instruction
2294 * e - edge
2295 */
2296static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
2297{
2298 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
2299 return 0;
2300
2301 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
2302 return 0;
2303
2304 if (w < 0 || w >= env->prog->len) {
2305 verbose("jump out of range from insn %d to %d\n", t, w);
2306 return -EINVAL;
2307 }
2308
2309 if (e == BRANCH)
2310 /* mark branch target for state pruning */
2311 env->explored_states[w] = STATE_LIST_MARK;
2312
2313 if (insn_state[w] == 0) {
2314 /* tree-edge */
2315 insn_state[t] = DISCOVERED | e;
2316 insn_state[w] = DISCOVERED;
2317 if (cur_stack >= env->prog->len)
2318 return -E2BIG;
2319 insn_stack[cur_stack++] = w;
2320 return 1;
2321 } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
2322 verbose("back-edge from insn %d to %d\n", t, w);
2323 return -EINVAL;
2324 } else if (insn_state[w] == EXPLORED) {
2325 /* forward- or cross-edge */
2326 insn_state[t] = DISCOVERED | e;
2327 } else {
2328 verbose("insn state internal bug\n");
2329 return -EFAULT;
2330 }
2331 return 0;
2332}
2333
2334/* non-recursive depth-first-search to detect loops in BPF program
2335 * loop == back-edge in directed graph
2336 */
2337static int check_cfg(struct bpf_verifier_env *env)
2338{
2339 struct bpf_insn *insns = env->prog->insnsi;
2340 int insn_cnt = env->prog->len;
2341 int ret = 0;
2342 int i, t;
2343
2344 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2345 if (!insn_state)
2346 return -ENOMEM;
2347
2348 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2349 if (!insn_stack) {
2350 kfree(insn_state);
2351 return -ENOMEM;
2352 }
2353
2354 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
2355 insn_stack[0] = 0; /* 0 is the first instruction */
2356 cur_stack = 1;
2357
2358peek_stack:
2359 if (cur_stack == 0)
2360 goto check_state;
2361 t = insn_stack[cur_stack - 1];
2362
2363 if (BPF_CLASS(insns[t].code) == BPF_JMP) {
2364 u8 opcode = BPF_OP(insns[t].code);
2365
2366 if (opcode == BPF_EXIT) {
2367 goto mark_explored;
2368 } else if (opcode == BPF_CALL) {
2369 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2370 if (ret == 1)
2371 goto peek_stack;
2372 else if (ret < 0)
2373 goto err_free;
2374 if (t + 1 < insn_cnt)
2375 env->explored_states[t + 1] = STATE_LIST_MARK;
2376 } else if (opcode == BPF_JA) {
2377 if (BPF_SRC(insns[t].code) != BPF_K) {
2378 ret = -EINVAL;
2379 goto err_free;
2380 }
2381 /* unconditional jump with single edge */
2382 ret = push_insn(t, t + insns[t].off + 1,
2383 FALLTHROUGH, env);
2384 if (ret == 1)
2385 goto peek_stack;
2386 else if (ret < 0)
2387 goto err_free;
2388 /* tell verifier to check for equivalent states
2389 * after every call and jump
2390 */
2391 if (t + 1 < insn_cnt)
2392 env->explored_states[t + 1] = STATE_LIST_MARK;
2393 } else {
2394 /* conditional jump with two edges */
2395 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2396 if (ret == 1)
2397 goto peek_stack;
2398 else if (ret < 0)
2399 goto err_free;
2400
2401 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
2402 if (ret == 1)
2403 goto peek_stack;
2404 else if (ret < 0)
2405 goto err_free;
2406 }
2407 } else {
2408 /* all other non-branch instructions with single
2409 * fall-through edge
2410 */
2411 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2412 if (ret == 1)
2413 goto peek_stack;
2414 else if (ret < 0)
2415 goto err_free;
2416 }
2417
2418mark_explored:
2419 insn_state[t] = EXPLORED;
2420 if (cur_stack-- <= 0) {
2421 verbose("pop stack internal bug\n");
2422 ret = -EFAULT;
2423 goto err_free;
2424 }
2425 goto peek_stack;
2426
2427check_state:
2428 for (i = 0; i < insn_cnt; i++) {
2429 if (insn_state[i] != EXPLORED) {
2430 verbose("unreachable insn %d\n", i);
2431 ret = -EINVAL;
2432 goto err_free;
2433 }
2434 }
2435 ret = 0; /* cfg looks good */
2436
2437err_free:
2438 kfree(insn_state);
2439 kfree(insn_stack);
2440 return ret;
2441}
2442
2443/* the following conditions reduce the number of explored insns
2444 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2445 */
2446static bool compare_ptrs_to_packet(struct bpf_reg_state *old,
2447 struct bpf_reg_state *cur)
2448{
2449 if (old->id != cur->id)
2450 return false;
2451
2452 /* old ptr_to_packet is more conservative, since it allows smaller
2453 * range. Ex:
2454 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2455 * old(off=0,r=10) means that with range=10 the verifier proceeded
2456 * further and found no issues with the program. Now we're in the same
2457 * spot with cur(off=0,r=20), so we're safe too, since anything further
2458 * will only be looking at most 10 bytes after this pointer.
2459 */
2460 if (old->off == cur->off && old->range < cur->range)
2461 return true;
2462
2463 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2464 * since both cannot be used for packet access and safe(old)
2465 * pointer has smaller off that could be used for further
2466 * 'if (ptr > data_end)' check
2467 * Ex:
2468 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2469 * that we cannot access the packet.
2470 * The safe range is:
2471 * [ptr, ptr + range - off)
2472 * so whenever off >=range, it means no safe bytes from this pointer.
2473 * When comparing old->off <= cur->off, it means that older code
2474 * went with smaller offset and that offset was later
2475 * used to figure out the safe range after 'if (ptr > data_end)' check
2476 * Say, 'old' state was explored like:
2477 * ... R3(off=0, r=0)
2478 * R4 = R3 + 20
2479 * ... now R4(off=20,r=0) <-- here
2480 * if (R4 > data_end)
2481 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2482 * ... the code further went all the way to bpf_exit.
2483 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2484 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2485 * goes further, such cur_R4 will give larger safe packet range after
2486 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2487 * so they will be good with r=30 and we can prune the search.
2488 */
2489 if (old->off <= cur->off &&
2490 old->off >= old->range && cur->off >= cur->range)
2491 return true;
2492
2493 return false;
2494}
2495
2496/* compare two verifier states
2497 *
2498 * all states stored in state_list are known to be valid, since
2499 * verifier reached 'bpf_exit' instruction through them
2500 *
2501 * this function is called when verifier exploring different branches of
2502 * execution popped from the state stack. If it sees an old state that has
2503 * more strict register state and more strict stack state then this execution
2504 * branch doesn't need to be explored further, since verifier already
2505 * concluded that more strict state leads to valid finish.
2506 *
2507 * Therefore two states are equivalent if register state is more conservative
2508 * and explored stack state is more conservative than the current one.
2509 * Example:
2510 * explored current
2511 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2512 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2513 *
2514 * In other words if current stack state (one being explored) has more
2515 * valid slots than old one that already passed validation, it means
2516 * the verifier can stop exploring and conclude that current state is valid too
2517 *
2518 * Similarly with registers. If explored state has register type as invalid
2519 * whereas register type in current state is meaningful, it means that
2520 * the current state will reach 'bpf_exit' instruction safely
2521 */
2522static bool states_equal(struct bpf_verifier_env *env,
2523 struct bpf_verifier_state *old,
2524 struct bpf_verifier_state *cur)
2525{
2526 bool varlen_map_access = env->varlen_map_value_access;
2527 struct bpf_reg_state *rold, *rcur;
2528 int i;
2529
2530 for (i = 0; i < MAX_BPF_REG; i++) {
2531 rold = &old->regs[i];
2532 rcur = &cur->regs[i];
2533
2534 if (memcmp(rold, rcur, sizeof(*rold)) == 0)
2535 continue;
2536
2537 /* If the ranges were not the same, but everything else was and
2538 * we didn't do a variable access into a map then we are a-ok.
2539 */
2540 if (!varlen_map_access &&
2541 memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0)
2542 continue;
2543
2544 /* If we didn't map access then again we don't care about the
2545 * mismatched range values and it's ok if our old type was
2546 * UNKNOWN and we didn't go to a NOT_INIT'ed reg.
2547 */
2548 if (rold->type == NOT_INIT ||
2549 (!varlen_map_access && rold->type == UNKNOWN_VALUE &&
2550 rcur->type != NOT_INIT))
2551 continue;
2552
2553 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET &&
2554 compare_ptrs_to_packet(rold, rcur))
2555 continue;
2556
2557 return false;
2558 }
2559
2560 for (i = 0; i < MAX_BPF_STACK; i++) {
2561 if (old->stack_slot_type[i] == STACK_INVALID)
2562 continue;
2563 if (old->stack_slot_type[i] != cur->stack_slot_type[i])
2564 /* Ex: old explored (safe) state has STACK_SPILL in
2565 * this stack slot, but current has has STACK_MISC ->
2566 * this verifier states are not equivalent,
2567 * return false to continue verification of this path
2568 */
2569 return false;
2570 if (i % BPF_REG_SIZE)
2571 continue;
2572 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
2573 &cur->spilled_regs[i / BPF_REG_SIZE],
2574 sizeof(old->spilled_regs[0])))
2575 /* when explored and current stack slot types are
2576 * the same, check that stored pointers types
2577 * are the same as well.
2578 * Ex: explored safe path could have stored
2579 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
2580 * but current path has stored:
2581 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
2582 * such verifier states are not equivalent.
2583 * return false to continue verification of this path
2584 */
2585 return false;
2586 else
2587 continue;
2588 }
2589 return true;
2590}
2591
2592static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
2593{
2594 struct bpf_verifier_state_list *new_sl;
2595 struct bpf_verifier_state_list *sl;
2596
2597 sl = env->explored_states[insn_idx];
2598 if (!sl)
2599 /* this 'insn_idx' instruction wasn't marked, so we will not
2600 * be doing state search here
2601 */
2602 return 0;
2603
2604 while (sl != STATE_LIST_MARK) {
2605 if (states_equal(env, &sl->state, &env->cur_state))
2606 /* reached equivalent register/stack state,
2607 * prune the search
2608 */
2609 return 1;
2610 sl = sl->next;
2611 }
2612
2613 /* there were no equivalent states, remember current one.
2614 * technically the current state is not proven to be safe yet,
2615 * but it will either reach bpf_exit (which means it's safe) or
2616 * it will be rejected. Since there are no loops, we won't be
2617 * seeing this 'insn_idx' instruction again on the way to bpf_exit
2618 */
2619 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
2620 if (!new_sl)
2621 return -ENOMEM;
2622
2623 /* add new state to the head of linked list */
2624 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
2625 new_sl->next = env->explored_states[insn_idx];
2626 env->explored_states[insn_idx] = new_sl;
2627 return 0;
2628}
2629
2630static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
2631 int insn_idx, int prev_insn_idx)
2632{
2633 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
2634 return 0;
2635
2636 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
2637}
2638
2639static int do_check(struct bpf_verifier_env *env)
2640{
2641 struct bpf_verifier_state *state = &env->cur_state;
2642 struct bpf_insn *insns = env->prog->insnsi;
2643 struct bpf_reg_state *regs = state->regs;
2644 int insn_cnt = env->prog->len;
2645 int insn_idx, prev_insn_idx = 0;
2646 int insn_processed = 0;
2647 bool do_print_state = false;
2648
2649 init_reg_state(regs);
2650 insn_idx = 0;
2651 env->varlen_map_value_access = false;
2652 for (;;) {
2653 struct bpf_insn *insn;
2654 u8 class;
2655 int err;
2656
2657 if (insn_idx >= insn_cnt) {
2658 verbose("invalid insn idx %d insn_cnt %d\n",
2659 insn_idx, insn_cnt);
2660 return -EFAULT;
2661 }
2662
2663 insn = &insns[insn_idx];
2664 class = BPF_CLASS(insn->code);
2665
2666 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
2667 verbose("BPF program is too large. Proccessed %d insn\n",
2668 insn_processed);
2669 return -E2BIG;
2670 }
2671
2672 err = is_state_visited(env, insn_idx);
2673 if (err < 0)
2674 return err;
2675 if (err == 1) {
2676 /* found equivalent state, can prune the search */
2677 if (log_level) {
2678 if (do_print_state)
2679 verbose("\nfrom %d to %d: safe\n",
2680 prev_insn_idx, insn_idx);
2681 else
2682 verbose("%d: safe\n", insn_idx);
2683 }
2684 goto process_bpf_exit;
2685 }
2686
2687 if (log_level && do_print_state) {
2688 verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
2689 print_verifier_state(&env->cur_state);
2690 do_print_state = false;
2691 }
2692
2693 if (log_level) {
2694 verbose("%d: ", insn_idx);
2695 print_bpf_insn(insn);
2696 }
2697
2698 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
2699 if (err)
2700 return err;
2701
2702 if (class == BPF_ALU || class == BPF_ALU64) {
2703 err = check_alu_op(env, insn);
2704 if (err)
2705 return err;
2706
2707 } else if (class == BPF_LDX) {
2708 enum bpf_reg_type *prev_src_type, src_reg_type;
2709
2710 /* check for reserved fields is already done */
2711
2712 /* check src operand */
2713 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2714 if (err)
2715 return err;
2716
2717 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
2718 if (err)
2719 return err;
2720
2721 src_reg_type = regs[insn->src_reg].type;
2722
2723 /* check that memory (src_reg + off) is readable,
2724 * the state of dst_reg will be updated by this func
2725 */
2726 err = check_mem_access(env, insn->src_reg, insn->off,
2727 BPF_SIZE(insn->code), BPF_READ,
2728 insn->dst_reg);
2729 if (err)
2730 return err;
2731
2732 reset_reg_range_values(regs, insn->dst_reg);
2733 if (BPF_SIZE(insn->code) != BPF_W &&
2734 BPF_SIZE(insn->code) != BPF_DW) {
2735 insn_idx++;
2736 continue;
2737 }
2738
2739 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
2740
2741 if (*prev_src_type == NOT_INIT) {
2742 /* saw a valid insn
2743 * dst_reg = *(u32 *)(src_reg + off)
2744 * save type to validate intersecting paths
2745 */
2746 *prev_src_type = src_reg_type;
2747
2748 } else if (src_reg_type != *prev_src_type &&
2749 (src_reg_type == PTR_TO_CTX ||
2750 *prev_src_type == PTR_TO_CTX)) {
2751 /* ABuser program is trying to use the same insn
2752 * dst_reg = *(u32*) (src_reg + off)
2753 * with different pointer types:
2754 * src_reg == ctx in one branch and
2755 * src_reg == stack|map in some other branch.
2756 * Reject it.
2757 */
2758 verbose("same insn cannot be used with different pointers\n");
2759 return -EINVAL;
2760 }
2761
2762 } else if (class == BPF_STX) {
2763 enum bpf_reg_type *prev_dst_type, dst_reg_type;
2764
2765 if (BPF_MODE(insn->code) == BPF_XADD) {
2766 err = check_xadd(env, insn);
2767 if (err)
2768 return err;
2769 insn_idx++;
2770 continue;
2771 }
2772
2773 /* check src1 operand */
2774 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2775 if (err)
2776 return err;
2777 /* check src2 operand */
2778 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2779 if (err)
2780 return err;
2781
2782 dst_reg_type = regs[insn->dst_reg].type;
2783
2784 /* check that memory (dst_reg + off) is writeable */
2785 err = check_mem_access(env, insn->dst_reg, insn->off,
2786 BPF_SIZE(insn->code), BPF_WRITE,
2787 insn->src_reg);
2788 if (err)
2789 return err;
2790
2791 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
2792
2793 if (*prev_dst_type == NOT_INIT) {
2794 *prev_dst_type = dst_reg_type;
2795 } else if (dst_reg_type != *prev_dst_type &&
2796 (dst_reg_type == PTR_TO_CTX ||
2797 *prev_dst_type == PTR_TO_CTX)) {
2798 verbose("same insn cannot be used with different pointers\n");
2799 return -EINVAL;
2800 }
2801
2802 } else if (class == BPF_ST) {
2803 if (BPF_MODE(insn->code) != BPF_MEM ||
2804 insn->src_reg != BPF_REG_0) {
2805 verbose("BPF_ST uses reserved fields\n");
2806 return -EINVAL;
2807 }
2808 /* check src operand */
2809 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2810 if (err)
2811 return err;
2812
2813 /* check that memory (dst_reg + off) is writeable */
2814 err = check_mem_access(env, insn->dst_reg, insn->off,
2815 BPF_SIZE(insn->code), BPF_WRITE,
2816 -1);
2817 if (err)
2818 return err;
2819
2820 } else if (class == BPF_JMP) {
2821 u8 opcode = BPF_OP(insn->code);
2822
2823 if (opcode == BPF_CALL) {
2824 if (BPF_SRC(insn->code) != BPF_K ||
2825 insn->off != 0 ||
2826 insn->src_reg != BPF_REG_0 ||
2827 insn->dst_reg != BPF_REG_0) {
2828 verbose("BPF_CALL uses reserved fields\n");
2829 return -EINVAL;
2830 }
2831
2832 err = check_call(env, insn->imm);
2833 if (err)
2834 return err;
2835
2836 } else if (opcode == BPF_JA) {
2837 if (BPF_SRC(insn->code) != BPF_K ||
2838 insn->imm != 0 ||
2839 insn->src_reg != BPF_REG_0 ||
2840 insn->dst_reg != BPF_REG_0) {
2841 verbose("BPF_JA uses reserved fields\n");
2842 return -EINVAL;
2843 }
2844
2845 insn_idx += insn->off + 1;
2846 continue;
2847
2848 } else if (opcode == BPF_EXIT) {
2849 if (BPF_SRC(insn->code) != BPF_K ||
2850 insn->imm != 0 ||
2851 insn->src_reg != BPF_REG_0 ||
2852 insn->dst_reg != BPF_REG_0) {
2853 verbose("BPF_EXIT uses reserved fields\n");
2854 return -EINVAL;
2855 }
2856
2857 /* eBPF calling convetion is such that R0 is used
2858 * to return the value from eBPF program.
2859 * Make sure that it's readable at this time
2860 * of bpf_exit, which means that program wrote
2861 * something into it earlier
2862 */
2863 err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
2864 if (err)
2865 return err;
2866
2867 if (is_pointer_value(env, BPF_REG_0)) {
2868 verbose("R0 leaks addr as return value\n");
2869 return -EACCES;
2870 }
2871
2872process_bpf_exit:
2873 insn_idx = pop_stack(env, &prev_insn_idx);
2874 if (insn_idx < 0) {
2875 break;
2876 } else {
2877 do_print_state = true;
2878 continue;
2879 }
2880 } else {
2881 err = check_cond_jmp_op(env, insn, &insn_idx);
2882 if (err)
2883 return err;
2884 }
2885 } else if (class == BPF_LD) {
2886 u8 mode = BPF_MODE(insn->code);
2887
2888 if (mode == BPF_ABS || mode == BPF_IND) {
2889 err = check_ld_abs(env, insn);
2890 if (err)
2891 return err;
2892
2893 } else if (mode == BPF_IMM) {
2894 err = check_ld_imm(env, insn);
2895 if (err)
2896 return err;
2897
2898 insn_idx++;
2899 } else {
2900 verbose("invalid BPF_LD mode\n");
2901 return -EINVAL;
2902 }
2903 reset_reg_range_values(regs, insn->dst_reg);
2904 } else {
2905 verbose("unknown insn class %d\n", class);
2906 return -EINVAL;
2907 }
2908
2909 insn_idx++;
2910 }
2911
2912 verbose("processed %d insns\n", insn_processed);
2913 return 0;
2914}
2915
2916static int check_map_prog_compatibility(struct bpf_map *map,
2917 struct bpf_prog *prog)
2918
2919{
2920 if (prog->type == BPF_PROG_TYPE_PERF_EVENT &&
2921 (map->map_type == BPF_MAP_TYPE_HASH ||
2922 map->map_type == BPF_MAP_TYPE_PERCPU_HASH) &&
2923 (map->map_flags & BPF_F_NO_PREALLOC)) {
2924 verbose("perf_event programs can only use preallocated hash map\n");
2925 return -EINVAL;
2926 }
2927 return 0;
2928}
2929
2930/* look for pseudo eBPF instructions that access map FDs and
2931 * replace them with actual map pointers
2932 */
2933static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
2934{
2935 struct bpf_insn *insn = env->prog->insnsi;
2936 int insn_cnt = env->prog->len;
2937 int i, j, err;
2938
2939 err = bpf_prog_calc_tag(env->prog);
2940 if (err)
2941 return err;
2942
2943 for (i = 0; i < insn_cnt; i++, insn++) {
2944 if (BPF_CLASS(insn->code) == BPF_LDX &&
2945 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
2946 verbose("BPF_LDX uses reserved fields\n");
2947 return -EINVAL;
2948 }
2949
2950 if (BPF_CLASS(insn->code) == BPF_STX &&
2951 ((BPF_MODE(insn->code) != BPF_MEM &&
2952 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
2953 verbose("BPF_STX uses reserved fields\n");
2954 return -EINVAL;
2955 }
2956
2957 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
2958 struct bpf_map *map;
2959 struct fd f;
2960
2961 if (i == insn_cnt - 1 || insn[1].code != 0 ||
2962 insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
2963 insn[1].off != 0) {
2964 verbose("invalid bpf_ld_imm64 insn\n");
2965 return -EINVAL;
2966 }
2967
2968 if (insn->src_reg == 0)
2969 /* valid generic load 64-bit imm */
2970 goto next_insn;
2971
2972 if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
2973 verbose("unrecognized bpf_ld_imm64 insn\n");
2974 return -EINVAL;
2975 }
2976
2977 f = fdget(insn->imm);
2978 map = __bpf_map_get(f);
2979 if (IS_ERR(map)) {
2980 verbose("fd %d is not pointing to valid bpf_map\n",
2981 insn->imm);
2982 return PTR_ERR(map);
2983 }
2984
2985 err = check_map_prog_compatibility(map, env->prog);
2986 if (err) {
2987 fdput(f);
2988 return err;
2989 }
2990
2991 /* store map pointer inside BPF_LD_IMM64 instruction */
2992 insn[0].imm = (u32) (unsigned long) map;
2993 insn[1].imm = ((u64) (unsigned long) map) >> 32;
2994
2995 /* check whether we recorded this map already */
2996 for (j = 0; j < env->used_map_cnt; j++)
2997 if (env->used_maps[j] == map) {
2998 fdput(f);
2999 goto next_insn;
3000 }
3001
3002 if (env->used_map_cnt >= MAX_USED_MAPS) {
3003 fdput(f);
3004 return -E2BIG;
3005 }
3006
3007 /* hold the map. If the program is rejected by verifier,
3008 * the map will be released by release_maps() or it
3009 * will be used by the valid program until it's unloaded
3010 * and all maps are released in free_bpf_prog_info()
3011 */
3012 map = bpf_map_inc(map, false);
3013 if (IS_ERR(map)) {
3014 fdput(f);
3015 return PTR_ERR(map);
3016 }
3017 env->used_maps[env->used_map_cnt++] = map;
3018
3019 fdput(f);
3020next_insn:
3021 insn++;
3022 i++;
3023 }
3024 }
3025
3026 /* now all pseudo BPF_LD_IMM64 instructions load valid
3027 * 'struct bpf_map *' into a register instead of user map_fd.
3028 * These pointers will be used later by verifier to validate map access.
3029 */
3030 return 0;
3031}
3032
3033/* drop refcnt of maps used by the rejected program */
3034static void release_maps(struct bpf_verifier_env *env)
3035{
3036 int i;
3037
3038 for (i = 0; i < env->used_map_cnt; i++)
3039 bpf_map_put(env->used_maps[i]);
3040}
3041
3042/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
3043static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
3044{
3045 struct bpf_insn *insn = env->prog->insnsi;
3046 int insn_cnt = env->prog->len;
3047 int i;
3048
3049 for (i = 0; i < insn_cnt; i++, insn++)
3050 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
3051 insn->src_reg = 0;
3052}
3053
3054/* convert load instructions that access fields of 'struct __sk_buff'
3055 * into sequence of instructions that access fields of 'struct sk_buff'
3056 */
3057static int convert_ctx_accesses(struct bpf_verifier_env *env)
3058{
3059 const struct bpf_verifier_ops *ops = env->prog->aux->ops;
3060 const int insn_cnt = env->prog->len;
3061 struct bpf_insn insn_buf[16], *insn;
3062 struct bpf_prog *new_prog;
3063 enum bpf_access_type type;
3064 int i, cnt, delta = 0;
3065
3066 if (ops->gen_prologue) {
3067 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
3068 env->prog);
3069 if (cnt >= ARRAY_SIZE(insn_buf)) {
3070 verbose("bpf verifier is misconfigured\n");
3071 return -EINVAL;
3072 } else if (cnt) {
3073 new_prog = bpf_patch_insn_single(env->prog, 0,
3074 insn_buf, cnt);
3075 if (!new_prog)
3076 return -ENOMEM;
3077 env->prog = new_prog;
3078 delta += cnt - 1;
3079 }
3080 }
3081
3082 if (!ops->convert_ctx_access)
3083 return 0;
3084
3085 insn = env->prog->insnsi + delta;
3086
3087 for (i = 0; i < insn_cnt; i++, insn++) {
3088 if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
3089 insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
3090 type = BPF_READ;
3091 else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
3092 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
3093 type = BPF_WRITE;
3094 else
3095 continue;
3096
3097 if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX)
3098 continue;
3099
3100 cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg,
3101 insn->off, insn_buf, env->prog);
3102 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
3103 verbose("bpf verifier is misconfigured\n");
3104 return -EINVAL;
3105 }
3106
3107 new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf,
3108 cnt);
3109 if (!new_prog)
3110 return -ENOMEM;
3111
3112 delta += cnt - 1;
3113
3114 /* keep walking new program and skip insns we just inserted */
3115 env->prog = new_prog;
3116 insn = new_prog->insnsi + i + delta;
3117 }
3118
3119 return 0;
3120}
3121
3122static void free_states(struct bpf_verifier_env *env)
3123{
3124 struct bpf_verifier_state_list *sl, *sln;
3125 int i;
3126
3127 if (!env->explored_states)
3128 return;
3129
3130 for (i = 0; i < env->prog->len; i++) {
3131 sl = env->explored_states[i];
3132
3133 if (sl)
3134 while (sl != STATE_LIST_MARK) {
3135 sln = sl->next;
3136 kfree(sl);
3137 sl = sln;
3138 }
3139 }
3140
3141 kfree(env->explored_states);
3142}
3143
3144int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
3145{
3146 char __user *log_ubuf = NULL;
3147 struct bpf_verifier_env *env;
3148 int ret = -EINVAL;
3149
3150 /* 'struct bpf_verifier_env' can be global, but since it's not small,
3151 * allocate/free it every time bpf_check() is called
3152 */
3153 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3154 if (!env)
3155 return -ENOMEM;
3156
3157 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3158 (*prog)->len);
3159 ret = -ENOMEM;
3160 if (!env->insn_aux_data)
3161 goto err_free_env;
3162 env->prog = *prog;
3163
3164 /* grab the mutex to protect few globals used by verifier */
3165 mutex_lock(&bpf_verifier_lock);
3166
3167 if (attr->log_level || attr->log_buf || attr->log_size) {
3168 /* user requested verbose verifier output
3169 * and supplied buffer to store the verification trace
3170 */
3171 log_level = attr->log_level;
3172 log_ubuf = (char __user *) (unsigned long) attr->log_buf;
3173 log_size = attr->log_size;
3174 log_len = 0;
3175
3176 ret = -EINVAL;
3177 /* log_* values have to be sane */
3178 if (log_size < 128 || log_size > UINT_MAX >> 8 ||
3179 log_level == 0 || log_ubuf == NULL)
3180 goto err_unlock;
3181
3182 ret = -ENOMEM;
3183 log_buf = vmalloc(log_size);
3184 if (!log_buf)
3185 goto err_unlock;
3186 } else {
3187 log_level = 0;
3188 }
3189
3190 ret = replace_map_fd_with_map_ptr(env);
3191 if (ret < 0)
3192 goto skip_full_check;
3193
3194 env->explored_states = kcalloc(env->prog->len,
3195 sizeof(struct bpf_verifier_state_list *),
3196 GFP_USER);
3197 ret = -ENOMEM;
3198 if (!env->explored_states)
3199 goto skip_full_check;
3200
3201 ret = check_cfg(env);
3202 if (ret < 0)
3203 goto skip_full_check;
3204
3205 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3206
3207 ret = do_check(env);
3208
3209skip_full_check:
3210 while (pop_stack(env, NULL) >= 0);
3211 free_states(env);
3212
3213 if (ret == 0)
3214 /* program is valid, convert *(u32*)(ctx + off) accesses */
3215 ret = convert_ctx_accesses(env);
3216
3217 if (log_level && log_len >= log_size - 1) {
3218 BUG_ON(log_len >= log_size);
3219 /* verifier log exceeded user supplied buffer */
3220 ret = -ENOSPC;
3221 /* fall through to return what was recorded */
3222 }
3223
3224 /* copy verifier log back to user space including trailing zero */
3225 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
3226 ret = -EFAULT;
3227 goto free_log_buf;
3228 }
3229
3230 if (ret == 0 && env->used_map_cnt) {
3231 /* if program passed verifier, update used_maps in bpf_prog_info */
3232 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
3233 sizeof(env->used_maps[0]),
3234 GFP_KERNEL);
3235
3236 if (!env->prog->aux->used_maps) {
3237 ret = -ENOMEM;
3238 goto free_log_buf;
3239 }
3240
3241 memcpy(env->prog->aux->used_maps, env->used_maps,
3242 sizeof(env->used_maps[0]) * env->used_map_cnt);
3243 env->prog->aux->used_map_cnt = env->used_map_cnt;
3244
3245 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3246 * bpf_ld_imm64 instructions
3247 */
3248 convert_pseudo_ld_imm64(env);
3249 }
3250
3251free_log_buf:
3252 if (log_level)
3253 vfree(log_buf);
3254 if (!env->prog->aux->used_maps)
3255 /* if we didn't copy map pointers into bpf_prog_info, release
3256 * them now. Otherwise free_bpf_prog_info() will release them.
3257 */
3258 release_maps(env);
3259 *prog = env->prog;
3260err_unlock:
3261 mutex_unlock(&bpf_verifier_lock);
3262 vfree(env->insn_aux_data);
3263err_free_env:
3264 kfree(env);
3265 return ret;
3266}
3267
3268int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
3269 void *priv)
3270{
3271 struct bpf_verifier_env *env;
3272 int ret;
3273
3274 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3275 if (!env)
3276 return -ENOMEM;
3277
3278 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3279 prog->len);
3280 ret = -ENOMEM;
3281 if (!env->insn_aux_data)
3282 goto err_free_env;
3283 env->prog = prog;
3284 env->analyzer_ops = ops;
3285 env->analyzer_priv = priv;
3286
3287 /* grab the mutex to protect few globals used by verifier */
3288 mutex_lock(&bpf_verifier_lock);
3289
3290 log_level = 0;
3291
3292 env->explored_states = kcalloc(env->prog->len,
3293 sizeof(struct bpf_verifier_state_list *),
3294 GFP_KERNEL);
3295 ret = -ENOMEM;
3296 if (!env->explored_states)
3297 goto skip_full_check;
3298
3299 ret = check_cfg(env);
3300 if (ret < 0)
3301 goto skip_full_check;
3302
3303 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3304
3305 ret = do_check(env);
3306
3307skip_full_check:
3308 while (pop_stack(env, NULL) >= 0);
3309 free_states(env);
3310
3311 mutex_unlock(&bpf_verifier_lock);
3312 vfree(env->insn_aux_data);
3313err_free_env:
3314 kfree(env);
3315 return ret;
3316}
3317EXPORT_SYMBOL_GPL(bpf_analyzer);