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