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Merge remote-tracking branch 'regulator/fix/max77802' into regulator-linus
[mirror_ubuntu-artful-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 64k insn, which may be hit even if total number of
37 * insn is less then 4K, but there are too many branches that change stack/regs.
38 * Number of 'branches to be analyzed' is limited to 1k
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 98304
144 #define BPF_COMPLEXITY_LIMIT_STACK 1024
145
146 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
147
148 struct bpf_call_arg_meta {
149 struct bpf_map *map_ptr;
150 bool raw_mode;
151 bool pkt_access;
152 int regno;
153 int access_size;
154 };
155
156 /* verbose verifier prints what it's seeing
157 * bpf_check() is called under lock, so no race to access these global vars
158 */
159 static u32 log_level, log_size, log_len;
160 static char *log_buf;
161
162 static DEFINE_MUTEX(bpf_verifier_lock);
163
164 /* log_level controls verbosity level of eBPF verifier.
165 * verbose() is used to dump the verification trace to the log, so the user
166 * can figure out what's wrong with the program
167 */
168 static __printf(1, 2) void verbose(const char *fmt, ...)
169 {
170 va_list args;
171
172 if (log_level == 0 || log_len >= log_size - 1)
173 return;
174
175 va_start(args, fmt);
176 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
177 va_end(args);
178 }
179
180 /* string representation of 'enum bpf_reg_type' */
181 static const char * const reg_type_str[] = {
182 [NOT_INIT] = "?",
183 [UNKNOWN_VALUE] = "inv",
184 [PTR_TO_CTX] = "ctx",
185 [CONST_PTR_TO_MAP] = "map_ptr",
186 [PTR_TO_MAP_VALUE] = "map_value",
187 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
188 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj",
189 [FRAME_PTR] = "fp",
190 [PTR_TO_STACK] = "fp",
191 [CONST_IMM] = "imm",
192 [PTR_TO_PACKET] = "pkt",
193 [PTR_TO_PACKET_END] = "pkt_end",
194 };
195
196 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x)
197 static const char * const func_id_str[] = {
198 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN)
199 };
200 #undef __BPF_FUNC_STR_FN
201
202 static const char *func_id_name(int id)
203 {
204 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID);
205
206 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id])
207 return func_id_str[id];
208 else
209 return "unknown";
210 }
211
212 static void print_verifier_state(struct bpf_verifier_state *state)
213 {
214 struct bpf_reg_state *reg;
215 enum bpf_reg_type t;
216 int i;
217
218 for (i = 0; i < MAX_BPF_REG; i++) {
219 reg = &state->regs[i];
220 t = reg->type;
221 if (t == NOT_INIT)
222 continue;
223 verbose(" R%d=%s", i, reg_type_str[t]);
224 if (t == CONST_IMM || t == PTR_TO_STACK)
225 verbose("%lld", reg->imm);
226 else if (t == PTR_TO_PACKET)
227 verbose("(id=%d,off=%d,r=%d)",
228 reg->id, reg->off, reg->range);
229 else if (t == UNKNOWN_VALUE && reg->imm)
230 verbose("%lld", reg->imm);
231 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
232 t == PTR_TO_MAP_VALUE_OR_NULL ||
233 t == PTR_TO_MAP_VALUE_ADJ)
234 verbose("(ks=%d,vs=%d,id=%u)",
235 reg->map_ptr->key_size,
236 reg->map_ptr->value_size,
237 reg->id);
238 if (reg->min_value != BPF_REGISTER_MIN_RANGE)
239 verbose(",min_value=%lld",
240 (long long)reg->min_value);
241 if (reg->max_value != BPF_REGISTER_MAX_RANGE)
242 verbose(",max_value=%llu",
243 (unsigned long long)reg->max_value);
244 if (reg->min_align)
245 verbose(",min_align=%u", reg->min_align);
246 if (reg->aux_off)
247 verbose(",aux_off=%u", reg->aux_off);
248 if (reg->aux_off_align)
249 verbose(",aux_off_align=%u", reg->aux_off_align);
250 }
251 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
252 if (state->stack_slot_type[i] == STACK_SPILL)
253 verbose(" fp%d=%s", -MAX_BPF_STACK + i,
254 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]);
255 }
256 verbose("\n");
257 }
258
259 static const char *const bpf_class_string[] = {
260 [BPF_LD] = "ld",
261 [BPF_LDX] = "ldx",
262 [BPF_ST] = "st",
263 [BPF_STX] = "stx",
264 [BPF_ALU] = "alu",
265 [BPF_JMP] = "jmp",
266 [BPF_RET] = "BUG",
267 [BPF_ALU64] = "alu64",
268 };
269
270 static const char *const bpf_alu_string[16] = {
271 [BPF_ADD >> 4] = "+=",
272 [BPF_SUB >> 4] = "-=",
273 [BPF_MUL >> 4] = "*=",
274 [BPF_DIV >> 4] = "/=",
275 [BPF_OR >> 4] = "|=",
276 [BPF_AND >> 4] = "&=",
277 [BPF_LSH >> 4] = "<<=",
278 [BPF_RSH >> 4] = ">>=",
279 [BPF_NEG >> 4] = "neg",
280 [BPF_MOD >> 4] = "%=",
281 [BPF_XOR >> 4] = "^=",
282 [BPF_MOV >> 4] = "=",
283 [BPF_ARSH >> 4] = "s>>=",
284 [BPF_END >> 4] = "endian",
285 };
286
287 static const char *const bpf_ldst_string[] = {
288 [BPF_W >> 3] = "u32",
289 [BPF_H >> 3] = "u16",
290 [BPF_B >> 3] = "u8",
291 [BPF_DW >> 3] = "u64",
292 };
293
294 static const char *const bpf_jmp_string[16] = {
295 [BPF_JA >> 4] = "jmp",
296 [BPF_JEQ >> 4] = "==",
297 [BPF_JGT >> 4] = ">",
298 [BPF_JGE >> 4] = ">=",
299 [BPF_JSET >> 4] = "&",
300 [BPF_JNE >> 4] = "!=",
301 [BPF_JSGT >> 4] = "s>",
302 [BPF_JSGE >> 4] = "s>=",
303 [BPF_CALL >> 4] = "call",
304 [BPF_EXIT >> 4] = "exit",
305 };
306
307 static void print_bpf_insn(const struct bpf_verifier_env *env,
308 const struct bpf_insn *insn)
309 {
310 u8 class = BPF_CLASS(insn->code);
311
312 if (class == BPF_ALU || class == BPF_ALU64) {
313 if (BPF_SRC(insn->code) == BPF_X)
314 verbose("(%02x) %sr%d %s %sr%d\n",
315 insn->code, class == BPF_ALU ? "(u32) " : "",
316 insn->dst_reg,
317 bpf_alu_string[BPF_OP(insn->code) >> 4],
318 class == BPF_ALU ? "(u32) " : "",
319 insn->src_reg);
320 else
321 verbose("(%02x) %sr%d %s %s%d\n",
322 insn->code, class == BPF_ALU ? "(u32) " : "",
323 insn->dst_reg,
324 bpf_alu_string[BPF_OP(insn->code) >> 4],
325 class == BPF_ALU ? "(u32) " : "",
326 insn->imm);
327 } else if (class == BPF_STX) {
328 if (BPF_MODE(insn->code) == BPF_MEM)
329 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
330 insn->code,
331 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
332 insn->dst_reg,
333 insn->off, insn->src_reg);
334 else if (BPF_MODE(insn->code) == BPF_XADD)
335 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
336 insn->code,
337 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
338 insn->dst_reg, insn->off,
339 insn->src_reg);
340 else
341 verbose("BUG_%02x\n", insn->code);
342 } else if (class == BPF_ST) {
343 if (BPF_MODE(insn->code) != BPF_MEM) {
344 verbose("BUG_st_%02x\n", insn->code);
345 return;
346 }
347 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
348 insn->code,
349 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
350 insn->dst_reg,
351 insn->off, insn->imm);
352 } else if (class == BPF_LDX) {
353 if (BPF_MODE(insn->code) != BPF_MEM) {
354 verbose("BUG_ldx_%02x\n", insn->code);
355 return;
356 }
357 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
358 insn->code, insn->dst_reg,
359 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
360 insn->src_reg, insn->off);
361 } else if (class == BPF_LD) {
362 if (BPF_MODE(insn->code) == BPF_ABS) {
363 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
364 insn->code,
365 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
366 insn->imm);
367 } else if (BPF_MODE(insn->code) == BPF_IND) {
368 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
369 insn->code,
370 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
371 insn->src_reg, insn->imm);
372 } else if (BPF_MODE(insn->code) == BPF_IMM &&
373 BPF_SIZE(insn->code) == BPF_DW) {
374 /* At this point, we already made sure that the second
375 * part of the ldimm64 insn is accessible.
376 */
377 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
378 bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD;
379
380 if (map_ptr && !env->allow_ptr_leaks)
381 imm = 0;
382
383 verbose("(%02x) r%d = 0x%llx\n", insn->code,
384 insn->dst_reg, (unsigned long long)imm);
385 } else {
386 verbose("BUG_ld_%02x\n", insn->code);
387 return;
388 }
389 } else if (class == BPF_JMP) {
390 u8 opcode = BPF_OP(insn->code);
391
392 if (opcode == BPF_CALL) {
393 verbose("(%02x) call %s#%d\n", insn->code,
394 func_id_name(insn->imm), insn->imm);
395 } else if (insn->code == (BPF_JMP | BPF_JA)) {
396 verbose("(%02x) goto pc%+d\n",
397 insn->code, insn->off);
398 } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
399 verbose("(%02x) exit\n", insn->code);
400 } else if (BPF_SRC(insn->code) == BPF_X) {
401 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
402 insn->code, insn->dst_reg,
403 bpf_jmp_string[BPF_OP(insn->code) >> 4],
404 insn->src_reg, insn->off);
405 } else {
406 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
407 insn->code, insn->dst_reg,
408 bpf_jmp_string[BPF_OP(insn->code) >> 4],
409 insn->imm, insn->off);
410 }
411 } else {
412 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
413 }
414 }
415
416 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
417 {
418 struct bpf_verifier_stack_elem *elem;
419 int insn_idx;
420
421 if (env->head == NULL)
422 return -1;
423
424 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
425 insn_idx = env->head->insn_idx;
426 if (prev_insn_idx)
427 *prev_insn_idx = env->head->prev_insn_idx;
428 elem = env->head->next;
429 kfree(env->head);
430 env->head = elem;
431 env->stack_size--;
432 return insn_idx;
433 }
434
435 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
436 int insn_idx, int prev_insn_idx)
437 {
438 struct bpf_verifier_stack_elem *elem;
439
440 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
441 if (!elem)
442 goto err;
443
444 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
445 elem->insn_idx = insn_idx;
446 elem->prev_insn_idx = prev_insn_idx;
447 elem->next = env->head;
448 env->head = elem;
449 env->stack_size++;
450 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
451 verbose("BPF program is too complex\n");
452 goto err;
453 }
454 return &elem->st;
455 err:
456 /* pop all elements and return */
457 while (pop_stack(env, NULL) >= 0);
458 return NULL;
459 }
460
461 #define CALLER_SAVED_REGS 6
462 static const int caller_saved[CALLER_SAVED_REGS] = {
463 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
464 };
465
466 static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno)
467 {
468 BUG_ON(regno >= MAX_BPF_REG);
469
470 memset(&regs[regno], 0, sizeof(regs[regno]));
471 regs[regno].type = NOT_INIT;
472 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
473 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
474 }
475
476 static void init_reg_state(struct bpf_reg_state *regs)
477 {
478 int i;
479
480 for (i = 0; i < MAX_BPF_REG; i++)
481 mark_reg_not_init(regs, i);
482
483 /* frame pointer */
484 regs[BPF_REG_FP].type = FRAME_PTR;
485
486 /* 1st arg to a function */
487 regs[BPF_REG_1].type = PTR_TO_CTX;
488 }
489
490 static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
491 {
492 regs[regno].type = UNKNOWN_VALUE;
493 regs[regno].id = 0;
494 regs[regno].imm = 0;
495 }
496
497 static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
498 {
499 BUG_ON(regno >= MAX_BPF_REG);
500 __mark_reg_unknown_value(regs, regno);
501 }
502
503 static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno)
504 {
505 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
506 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
507 regs[regno].min_align = 0;
508 }
509
510 static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs,
511 u32 regno)
512 {
513 mark_reg_unknown_value(regs, regno);
514 reset_reg_range_values(regs, regno);
515 }
516
517 enum reg_arg_type {
518 SRC_OP, /* register is used as source operand */
519 DST_OP, /* register is used as destination operand */
520 DST_OP_NO_MARK /* same as above, check only, don't mark */
521 };
522
523 static int check_reg_arg(struct bpf_reg_state *regs, u32 regno,
524 enum reg_arg_type t)
525 {
526 if (regno >= MAX_BPF_REG) {
527 verbose("R%d is invalid\n", regno);
528 return -EINVAL;
529 }
530
531 if (t == SRC_OP) {
532 /* check whether register used as source operand can be read */
533 if (regs[regno].type == NOT_INIT) {
534 verbose("R%d !read_ok\n", regno);
535 return -EACCES;
536 }
537 } else {
538 /* check whether register used as dest operand can be written to */
539 if (regno == BPF_REG_FP) {
540 verbose("frame pointer is read only\n");
541 return -EACCES;
542 }
543 if (t == DST_OP)
544 mark_reg_unknown_value(regs, regno);
545 }
546 return 0;
547 }
548
549 static int bpf_size_to_bytes(int bpf_size)
550 {
551 if (bpf_size == BPF_W)
552 return 4;
553 else if (bpf_size == BPF_H)
554 return 2;
555 else if (bpf_size == BPF_B)
556 return 1;
557 else if (bpf_size == BPF_DW)
558 return 8;
559 else
560 return -EINVAL;
561 }
562
563 static bool is_spillable_regtype(enum bpf_reg_type type)
564 {
565 switch (type) {
566 case PTR_TO_MAP_VALUE:
567 case PTR_TO_MAP_VALUE_OR_NULL:
568 case PTR_TO_MAP_VALUE_ADJ:
569 case PTR_TO_STACK:
570 case PTR_TO_CTX:
571 case PTR_TO_PACKET:
572 case PTR_TO_PACKET_END:
573 case FRAME_PTR:
574 case CONST_PTR_TO_MAP:
575 return true;
576 default:
577 return false;
578 }
579 }
580
581 /* check_stack_read/write functions track spill/fill of registers,
582 * stack boundary and alignment are checked in check_mem_access()
583 */
584 static int check_stack_write(struct bpf_verifier_state *state, int off,
585 int size, int value_regno)
586 {
587 int i;
588 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
589 * so it's aligned access and [off, off + size) are within stack limits
590 */
591
592 if (value_regno >= 0 &&
593 is_spillable_regtype(state->regs[value_regno].type)) {
594
595 /* register containing pointer is being spilled into stack */
596 if (size != BPF_REG_SIZE) {
597 verbose("invalid size of register spill\n");
598 return -EACCES;
599 }
600
601 /* save register state */
602 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
603 state->regs[value_regno];
604
605 for (i = 0; i < BPF_REG_SIZE; i++)
606 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
607 } else {
608 /* regular write of data into stack */
609 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
610 (struct bpf_reg_state) {};
611
612 for (i = 0; i < size; i++)
613 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
614 }
615 return 0;
616 }
617
618 static int check_stack_read(struct bpf_verifier_state *state, int off, int size,
619 int value_regno)
620 {
621 u8 *slot_type;
622 int i;
623
624 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
625
626 if (slot_type[0] == STACK_SPILL) {
627 if (size != BPF_REG_SIZE) {
628 verbose("invalid size of register spill\n");
629 return -EACCES;
630 }
631 for (i = 1; i < BPF_REG_SIZE; i++) {
632 if (slot_type[i] != STACK_SPILL) {
633 verbose("corrupted spill memory\n");
634 return -EACCES;
635 }
636 }
637
638 if (value_regno >= 0)
639 /* restore register state from stack */
640 state->regs[value_regno] =
641 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
642 return 0;
643 } else {
644 for (i = 0; i < size; i++) {
645 if (slot_type[i] != STACK_MISC) {
646 verbose("invalid read from stack off %d+%d size %d\n",
647 off, i, size);
648 return -EACCES;
649 }
650 }
651 if (value_regno >= 0)
652 /* have read misc data from the stack */
653 mark_reg_unknown_value_and_range(state->regs,
654 value_regno);
655 return 0;
656 }
657 }
658
659 /* check read/write into map element returned by bpf_map_lookup_elem() */
660 static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
661 int size)
662 {
663 struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
664
665 if (off < 0 || size <= 0 || off + size > map->value_size) {
666 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
667 map->value_size, off, size);
668 return -EACCES;
669 }
670 return 0;
671 }
672
673 /* check read/write into an adjusted map element */
674 static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno,
675 int off, int size)
676 {
677 struct bpf_verifier_state *state = &env->cur_state;
678 struct bpf_reg_state *reg = &state->regs[regno];
679 int err;
680
681 /* We adjusted the register to this map value, so we
682 * need to change off and size to min_value and max_value
683 * respectively to make sure our theoretical access will be
684 * safe.
685 */
686 if (log_level)
687 print_verifier_state(state);
688 env->varlen_map_value_access = true;
689 /* The minimum value is only important with signed
690 * comparisons where we can't assume the floor of a
691 * value is 0. If we are using signed variables for our
692 * index'es we need to make sure that whatever we use
693 * will have a set floor within our range.
694 */
695 if (reg->min_value < 0) {
696 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
697 regno);
698 return -EACCES;
699 }
700 err = check_map_access(env, regno, reg->min_value + off, size);
701 if (err) {
702 verbose("R%d min value is outside of the array range\n",
703 regno);
704 return err;
705 }
706
707 /* If we haven't set a max value then we need to bail
708 * since we can't be sure we won't do bad things.
709 */
710 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
711 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
712 regno);
713 return -EACCES;
714 }
715 return check_map_access(env, regno, reg->max_value + off, size);
716 }
717
718 #define MAX_PACKET_OFF 0xffff
719
720 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
721 const struct bpf_call_arg_meta *meta,
722 enum bpf_access_type t)
723 {
724 switch (env->prog->type) {
725 case BPF_PROG_TYPE_LWT_IN:
726 case BPF_PROG_TYPE_LWT_OUT:
727 /* dst_input() and dst_output() can't write for now */
728 if (t == BPF_WRITE)
729 return false;
730 /* fallthrough */
731 case BPF_PROG_TYPE_SCHED_CLS:
732 case BPF_PROG_TYPE_SCHED_ACT:
733 case BPF_PROG_TYPE_XDP:
734 case BPF_PROG_TYPE_LWT_XMIT:
735 if (meta)
736 return meta->pkt_access;
737
738 env->seen_direct_write = true;
739 return true;
740 default:
741 return false;
742 }
743 }
744
745 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
746 int size)
747 {
748 struct bpf_reg_state *regs = env->cur_state.regs;
749 struct bpf_reg_state *reg = &regs[regno];
750
751 off += reg->off;
752 if (off < 0 || size <= 0 || off + size > reg->range) {
753 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
754 off, size, regno, reg->id, reg->off, reg->range);
755 return -EACCES;
756 }
757 return 0;
758 }
759
760 /* check access to 'struct bpf_context' fields */
761 static int check_ctx_access(struct bpf_verifier_env *env, int off, int size,
762 enum bpf_access_type t, enum bpf_reg_type *reg_type)
763 {
764 /* for analyzer ctx accesses are already validated and converted */
765 if (env->analyzer_ops)
766 return 0;
767
768 if (env->prog->aux->ops->is_valid_access &&
769 env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) {
770 /* remember the offset of last byte accessed in ctx */
771 if (env->prog->aux->max_ctx_offset < off + size)
772 env->prog->aux->max_ctx_offset = off + size;
773 return 0;
774 }
775
776 verbose("invalid bpf_context access off=%d size=%d\n", off, size);
777 return -EACCES;
778 }
779
780 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
781 {
782 if (env->allow_ptr_leaks)
783 return false;
784
785 switch (env->cur_state.regs[regno].type) {
786 case UNKNOWN_VALUE:
787 case CONST_IMM:
788 return false;
789 default:
790 return true;
791 }
792 }
793
794 static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg,
795 int off, int size, bool strict)
796 {
797 int ip_align;
798 int reg_off;
799
800 /* Byte size accesses are always allowed. */
801 if (!strict || size == 1)
802 return 0;
803
804 reg_off = reg->off;
805 if (reg->id) {
806 if (reg->aux_off_align % size) {
807 verbose("Packet access is only %u byte aligned, %d byte access not allowed\n",
808 reg->aux_off_align, size);
809 return -EACCES;
810 }
811 reg_off += reg->aux_off;
812 }
813
814 /* For platforms that do not have a Kconfig enabling
815 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
816 * NET_IP_ALIGN is universally set to '2'. And on platforms
817 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
818 * to this code only in strict mode where we want to emulate
819 * the NET_IP_ALIGN==2 checking. Therefore use an
820 * unconditional IP align value of '2'.
821 */
822 ip_align = 2;
823 if ((ip_align + reg_off + off) % size != 0) {
824 verbose("misaligned packet access off %d+%d+%d size %d\n",
825 ip_align, reg_off, off, size);
826 return -EACCES;
827 }
828
829 return 0;
830 }
831
832 static int check_val_ptr_alignment(const struct bpf_reg_state *reg,
833 int size, bool strict)
834 {
835 if (strict && size != 1) {
836 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n");
837 return -EACCES;
838 }
839
840 return 0;
841 }
842
843 static int check_ptr_alignment(struct bpf_verifier_env *env,
844 const struct bpf_reg_state *reg,
845 int off, int size)
846 {
847 bool strict = env->strict_alignment;
848
849 switch (reg->type) {
850 case PTR_TO_PACKET:
851 return check_pkt_ptr_alignment(reg, off, size, strict);
852 case PTR_TO_MAP_VALUE_ADJ:
853 return check_val_ptr_alignment(reg, size, strict);
854 default:
855 if (off % size != 0) {
856 verbose("misaligned access off %d size %d\n",
857 off, size);
858 return -EACCES;
859 }
860
861 return 0;
862 }
863 }
864
865 /* check whether memory at (regno + off) is accessible for t = (read | write)
866 * if t==write, value_regno is a register which value is stored into memory
867 * if t==read, value_regno is a register which will receive the value from memory
868 * if t==write && value_regno==-1, some unknown value is stored into memory
869 * if t==read && value_regno==-1, don't care what we read from memory
870 */
871 static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off,
872 int bpf_size, enum bpf_access_type t,
873 int value_regno)
874 {
875 struct bpf_verifier_state *state = &env->cur_state;
876 struct bpf_reg_state *reg = &state->regs[regno];
877 int size, err = 0;
878
879 if (reg->type == PTR_TO_STACK)
880 off += reg->imm;
881
882 size = bpf_size_to_bytes(bpf_size);
883 if (size < 0)
884 return size;
885
886 err = check_ptr_alignment(env, reg, off, size);
887 if (err)
888 return err;
889
890 if (reg->type == PTR_TO_MAP_VALUE ||
891 reg->type == PTR_TO_MAP_VALUE_ADJ) {
892 if (t == BPF_WRITE && value_regno >= 0 &&
893 is_pointer_value(env, value_regno)) {
894 verbose("R%d leaks addr into map\n", value_regno);
895 return -EACCES;
896 }
897
898 if (reg->type == PTR_TO_MAP_VALUE_ADJ)
899 err = check_map_access_adj(env, regno, off, size);
900 else
901 err = check_map_access(env, regno, off, size);
902 if (!err && t == BPF_READ && value_regno >= 0)
903 mark_reg_unknown_value_and_range(state->regs,
904 value_regno);
905
906 } else if (reg->type == PTR_TO_CTX) {
907 enum bpf_reg_type reg_type = UNKNOWN_VALUE;
908
909 if (t == BPF_WRITE && value_regno >= 0 &&
910 is_pointer_value(env, value_regno)) {
911 verbose("R%d leaks addr into ctx\n", value_regno);
912 return -EACCES;
913 }
914 err = check_ctx_access(env, off, size, t, &reg_type);
915 if (!err && t == BPF_READ && value_regno >= 0) {
916 mark_reg_unknown_value_and_range(state->regs,
917 value_regno);
918 /* note that reg.[id|off|range] == 0 */
919 state->regs[value_regno].type = reg_type;
920 state->regs[value_regno].aux_off = 0;
921 state->regs[value_regno].aux_off_align = 0;
922 }
923
924 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) {
925 if (off >= 0 || off < -MAX_BPF_STACK) {
926 verbose("invalid stack off=%d size=%d\n", off, size);
927 return -EACCES;
928 }
929 if (t == BPF_WRITE) {
930 if (!env->allow_ptr_leaks &&
931 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
932 size != BPF_REG_SIZE) {
933 verbose("attempt to corrupt spilled pointer on stack\n");
934 return -EACCES;
935 }
936 err = check_stack_write(state, off, size, value_regno);
937 } else {
938 err = check_stack_read(state, off, size, value_regno);
939 }
940 } else if (state->regs[regno].type == PTR_TO_PACKET) {
941 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
942 verbose("cannot write into packet\n");
943 return -EACCES;
944 }
945 if (t == BPF_WRITE && value_regno >= 0 &&
946 is_pointer_value(env, value_regno)) {
947 verbose("R%d leaks addr into packet\n", value_regno);
948 return -EACCES;
949 }
950 err = check_packet_access(env, regno, off, size);
951 if (!err && t == BPF_READ && value_regno >= 0)
952 mark_reg_unknown_value_and_range(state->regs,
953 value_regno);
954 } else {
955 verbose("R%d invalid mem access '%s'\n",
956 regno, reg_type_str[reg->type]);
957 return -EACCES;
958 }
959
960 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks &&
961 state->regs[value_regno].type == UNKNOWN_VALUE) {
962 /* 1 or 2 byte load zero-extends, determine the number of
963 * zero upper bits. Not doing it fo 4 byte load, since
964 * such values cannot be added to ptr_to_packet anyway.
965 */
966 state->regs[value_regno].imm = 64 - size * 8;
967 }
968 return err;
969 }
970
971 static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn)
972 {
973 struct bpf_reg_state *regs = env->cur_state.regs;
974 int err;
975
976 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
977 insn->imm != 0) {
978 verbose("BPF_XADD uses reserved fields\n");
979 return -EINVAL;
980 }
981
982 /* check src1 operand */
983 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
984 if (err)
985 return err;
986
987 /* check src2 operand */
988 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
989 if (err)
990 return err;
991
992 if (is_pointer_value(env, insn->src_reg)) {
993 verbose("R%d leaks addr into mem\n", insn->src_reg);
994 return -EACCES;
995 }
996
997 /* check whether atomic_add can read the memory */
998 err = check_mem_access(env, insn->dst_reg, insn->off,
999 BPF_SIZE(insn->code), BPF_READ, -1);
1000 if (err)
1001 return err;
1002
1003 /* check whether atomic_add can write into the same memory */
1004 return check_mem_access(env, insn->dst_reg, insn->off,
1005 BPF_SIZE(insn->code), BPF_WRITE, -1);
1006 }
1007
1008 /* when register 'regno' is passed into function that will read 'access_size'
1009 * bytes from that pointer, make sure that it's within stack boundary
1010 * and all elements of stack are initialized
1011 */
1012 static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
1013 int access_size, bool zero_size_allowed,
1014 struct bpf_call_arg_meta *meta)
1015 {
1016 struct bpf_verifier_state *state = &env->cur_state;
1017 struct bpf_reg_state *regs = state->regs;
1018 int off, i;
1019
1020 if (regs[regno].type != PTR_TO_STACK) {
1021 if (zero_size_allowed && access_size == 0 &&
1022 regs[regno].type == CONST_IMM &&
1023 regs[regno].imm == 0)
1024 return 0;
1025
1026 verbose("R%d type=%s expected=%s\n", regno,
1027 reg_type_str[regs[regno].type],
1028 reg_type_str[PTR_TO_STACK]);
1029 return -EACCES;
1030 }
1031
1032 off = regs[regno].imm;
1033 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
1034 access_size <= 0) {
1035 verbose("invalid stack type R%d off=%d access_size=%d\n",
1036 regno, off, access_size);
1037 return -EACCES;
1038 }
1039
1040 if (meta && meta->raw_mode) {
1041 meta->access_size = access_size;
1042 meta->regno = regno;
1043 return 0;
1044 }
1045
1046 for (i = 0; i < access_size; i++) {
1047 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
1048 verbose("invalid indirect read from stack off %d+%d size %d\n",
1049 off, i, access_size);
1050 return -EACCES;
1051 }
1052 }
1053 return 0;
1054 }
1055
1056 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
1057 int access_size, bool zero_size_allowed,
1058 struct bpf_call_arg_meta *meta)
1059 {
1060 struct bpf_reg_state *regs = env->cur_state.regs;
1061
1062 switch (regs[regno].type) {
1063 case PTR_TO_PACKET:
1064 return check_packet_access(env, regno, 0, access_size);
1065 case PTR_TO_MAP_VALUE:
1066 return check_map_access(env, regno, 0, access_size);
1067 case PTR_TO_MAP_VALUE_ADJ:
1068 return check_map_access_adj(env, regno, 0, access_size);
1069 default: /* const_imm|ptr_to_stack or invalid ptr */
1070 return check_stack_boundary(env, regno, access_size,
1071 zero_size_allowed, meta);
1072 }
1073 }
1074
1075 static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
1076 enum bpf_arg_type arg_type,
1077 struct bpf_call_arg_meta *meta)
1078 {
1079 struct bpf_reg_state *regs = env->cur_state.regs, *reg = &regs[regno];
1080 enum bpf_reg_type expected_type, type = reg->type;
1081 int err = 0;
1082
1083 if (arg_type == ARG_DONTCARE)
1084 return 0;
1085
1086 if (type == NOT_INIT) {
1087 verbose("R%d !read_ok\n", regno);
1088 return -EACCES;
1089 }
1090
1091 if (arg_type == ARG_ANYTHING) {
1092 if (is_pointer_value(env, regno)) {
1093 verbose("R%d leaks addr into helper function\n", regno);
1094 return -EACCES;
1095 }
1096 return 0;
1097 }
1098
1099 if (type == PTR_TO_PACKET &&
1100 !may_access_direct_pkt_data(env, meta, BPF_READ)) {
1101 verbose("helper access to the packet is not allowed\n");
1102 return -EACCES;
1103 }
1104
1105 if (arg_type == ARG_PTR_TO_MAP_KEY ||
1106 arg_type == ARG_PTR_TO_MAP_VALUE) {
1107 expected_type = PTR_TO_STACK;
1108 if (type != PTR_TO_PACKET && type != expected_type)
1109 goto err_type;
1110 } else if (arg_type == ARG_CONST_SIZE ||
1111 arg_type == ARG_CONST_SIZE_OR_ZERO) {
1112 expected_type = CONST_IMM;
1113 /* One exception. Allow UNKNOWN_VALUE registers when the
1114 * boundaries are known and don't cause unsafe memory accesses
1115 */
1116 if (type != UNKNOWN_VALUE && type != expected_type)
1117 goto err_type;
1118 } else if (arg_type == ARG_CONST_MAP_PTR) {
1119 expected_type = CONST_PTR_TO_MAP;
1120 if (type != expected_type)
1121 goto err_type;
1122 } else if (arg_type == ARG_PTR_TO_CTX) {
1123 expected_type = PTR_TO_CTX;
1124 if (type != expected_type)
1125 goto err_type;
1126 } else if (arg_type == ARG_PTR_TO_MEM ||
1127 arg_type == ARG_PTR_TO_UNINIT_MEM) {
1128 expected_type = PTR_TO_STACK;
1129 /* One exception here. In case function allows for NULL to be
1130 * passed in as argument, it's a CONST_IMM type. Final test
1131 * happens during stack boundary checking.
1132 */
1133 if (type == CONST_IMM && reg->imm == 0)
1134 /* final test in check_stack_boundary() */;
1135 else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE &&
1136 type != PTR_TO_MAP_VALUE_ADJ && type != expected_type)
1137 goto err_type;
1138 meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
1139 } else {
1140 verbose("unsupported arg_type %d\n", arg_type);
1141 return -EFAULT;
1142 }
1143
1144 if (arg_type == ARG_CONST_MAP_PTR) {
1145 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
1146 meta->map_ptr = reg->map_ptr;
1147 } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
1148 /* bpf_map_xxx(..., map_ptr, ..., key) call:
1149 * check that [key, key + map->key_size) are within
1150 * stack limits and initialized
1151 */
1152 if (!meta->map_ptr) {
1153 /* in function declaration map_ptr must come before
1154 * map_key, so that it's verified and known before
1155 * we have to check map_key here. Otherwise it means
1156 * that kernel subsystem misconfigured verifier
1157 */
1158 verbose("invalid map_ptr to access map->key\n");
1159 return -EACCES;
1160 }
1161 if (type == PTR_TO_PACKET)
1162 err = check_packet_access(env, regno, 0,
1163 meta->map_ptr->key_size);
1164 else
1165 err = check_stack_boundary(env, regno,
1166 meta->map_ptr->key_size,
1167 false, NULL);
1168 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
1169 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1170 * check [value, value + map->value_size) validity
1171 */
1172 if (!meta->map_ptr) {
1173 /* kernel subsystem misconfigured verifier */
1174 verbose("invalid map_ptr to access map->value\n");
1175 return -EACCES;
1176 }
1177 if (type == PTR_TO_PACKET)
1178 err = check_packet_access(env, regno, 0,
1179 meta->map_ptr->value_size);
1180 else
1181 err = check_stack_boundary(env, regno,
1182 meta->map_ptr->value_size,
1183 false, NULL);
1184 } else if (arg_type == ARG_CONST_SIZE ||
1185 arg_type == ARG_CONST_SIZE_OR_ZERO) {
1186 bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
1187
1188 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1189 * from stack pointer 'buf'. Check it
1190 * note: regno == len, regno - 1 == buf
1191 */
1192 if (regno == 0) {
1193 /* kernel subsystem misconfigured verifier */
1194 verbose("ARG_CONST_SIZE cannot be first argument\n");
1195 return -EACCES;
1196 }
1197
1198 /* If the register is UNKNOWN_VALUE, the access check happens
1199 * using its boundaries. Otherwise, just use its imm
1200 */
1201 if (type == UNKNOWN_VALUE) {
1202 /* For unprivileged variable accesses, disable raw
1203 * mode so that the program is required to
1204 * initialize all the memory that the helper could
1205 * just partially fill up.
1206 */
1207 meta = NULL;
1208
1209 if (reg->min_value < 0) {
1210 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n",
1211 regno);
1212 return -EACCES;
1213 }
1214
1215 if (reg->min_value == 0) {
1216 err = check_helper_mem_access(env, regno - 1, 0,
1217 zero_size_allowed,
1218 meta);
1219 if (err)
1220 return err;
1221 }
1222
1223 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
1224 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
1225 regno);
1226 return -EACCES;
1227 }
1228 err = check_helper_mem_access(env, regno - 1,
1229 reg->max_value,
1230 zero_size_allowed, meta);
1231 if (err)
1232 return err;
1233 } else {
1234 /* register is CONST_IMM */
1235 err = check_helper_mem_access(env, regno - 1, reg->imm,
1236 zero_size_allowed, meta);
1237 }
1238 }
1239
1240 return err;
1241 err_type:
1242 verbose("R%d type=%s expected=%s\n", regno,
1243 reg_type_str[type], reg_type_str[expected_type]);
1244 return -EACCES;
1245 }
1246
1247 static int check_map_func_compatibility(struct bpf_map *map, int func_id)
1248 {
1249 if (!map)
1250 return 0;
1251
1252 /* We need a two way check, first is from map perspective ... */
1253 switch (map->map_type) {
1254 case BPF_MAP_TYPE_PROG_ARRAY:
1255 if (func_id != BPF_FUNC_tail_call)
1256 goto error;
1257 break;
1258 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
1259 if (func_id != BPF_FUNC_perf_event_read &&
1260 func_id != BPF_FUNC_perf_event_output)
1261 goto error;
1262 break;
1263 case BPF_MAP_TYPE_STACK_TRACE:
1264 if (func_id != BPF_FUNC_get_stackid)
1265 goto error;
1266 break;
1267 case BPF_MAP_TYPE_CGROUP_ARRAY:
1268 if (func_id != BPF_FUNC_skb_under_cgroup &&
1269 func_id != BPF_FUNC_current_task_under_cgroup)
1270 goto error;
1271 break;
1272 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
1273 case BPF_MAP_TYPE_HASH_OF_MAPS:
1274 if (func_id != BPF_FUNC_map_lookup_elem)
1275 goto error;
1276 default:
1277 break;
1278 }
1279
1280 /* ... and second from the function itself. */
1281 switch (func_id) {
1282 case BPF_FUNC_tail_call:
1283 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
1284 goto error;
1285 break;
1286 case BPF_FUNC_perf_event_read:
1287 case BPF_FUNC_perf_event_output:
1288 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
1289 goto error;
1290 break;
1291 case BPF_FUNC_get_stackid:
1292 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
1293 goto error;
1294 break;
1295 case BPF_FUNC_current_task_under_cgroup:
1296 case BPF_FUNC_skb_under_cgroup:
1297 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
1298 goto error;
1299 break;
1300 default:
1301 break;
1302 }
1303
1304 return 0;
1305 error:
1306 verbose("cannot pass map_type %d into func %s#%d\n",
1307 map->map_type, func_id_name(func_id), func_id);
1308 return -EINVAL;
1309 }
1310
1311 static int check_raw_mode(const struct bpf_func_proto *fn)
1312 {
1313 int count = 0;
1314
1315 if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
1316 count++;
1317 if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
1318 count++;
1319 if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
1320 count++;
1321 if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
1322 count++;
1323 if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
1324 count++;
1325
1326 return count > 1 ? -EINVAL : 0;
1327 }
1328
1329 static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
1330 {
1331 struct bpf_verifier_state *state = &env->cur_state;
1332 struct bpf_reg_state *regs = state->regs, *reg;
1333 int i;
1334
1335 for (i = 0; i < MAX_BPF_REG; i++)
1336 if (regs[i].type == PTR_TO_PACKET ||
1337 regs[i].type == PTR_TO_PACKET_END)
1338 mark_reg_unknown_value(regs, i);
1339
1340 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1341 if (state->stack_slot_type[i] != STACK_SPILL)
1342 continue;
1343 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1344 if (reg->type != PTR_TO_PACKET &&
1345 reg->type != PTR_TO_PACKET_END)
1346 continue;
1347 reg->type = UNKNOWN_VALUE;
1348 reg->imm = 0;
1349 }
1350 }
1351
1352 static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
1353 {
1354 struct bpf_verifier_state *state = &env->cur_state;
1355 const struct bpf_func_proto *fn = NULL;
1356 struct bpf_reg_state *regs = state->regs;
1357 struct bpf_call_arg_meta meta;
1358 bool changes_data;
1359 int i, err;
1360
1361 /* find function prototype */
1362 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
1363 verbose("invalid func %s#%d\n", func_id_name(func_id), func_id);
1364 return -EINVAL;
1365 }
1366
1367 if (env->prog->aux->ops->get_func_proto)
1368 fn = env->prog->aux->ops->get_func_proto(func_id);
1369
1370 if (!fn) {
1371 verbose("unknown func %s#%d\n", func_id_name(func_id), func_id);
1372 return -EINVAL;
1373 }
1374
1375 /* eBPF programs must be GPL compatible to use GPL-ed functions */
1376 if (!env->prog->gpl_compatible && fn->gpl_only) {
1377 verbose("cannot call GPL only function from proprietary program\n");
1378 return -EINVAL;
1379 }
1380
1381 changes_data = bpf_helper_changes_pkt_data(fn->func);
1382
1383 memset(&meta, 0, sizeof(meta));
1384 meta.pkt_access = fn->pkt_access;
1385
1386 /* We only support one arg being in raw mode at the moment, which
1387 * is sufficient for the helper functions we have right now.
1388 */
1389 err = check_raw_mode(fn);
1390 if (err) {
1391 verbose("kernel subsystem misconfigured func %s#%d\n",
1392 func_id_name(func_id), func_id);
1393 return err;
1394 }
1395
1396 /* check args */
1397 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
1398 if (err)
1399 return err;
1400 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
1401 if (err)
1402 return err;
1403 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
1404 if (err)
1405 return err;
1406 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
1407 if (err)
1408 return err;
1409 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
1410 if (err)
1411 return err;
1412
1413 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1414 * is inferred from register state.
1415 */
1416 for (i = 0; i < meta.access_size; i++) {
1417 err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1);
1418 if (err)
1419 return err;
1420 }
1421
1422 /* reset caller saved regs */
1423 for (i = 0; i < CALLER_SAVED_REGS; i++)
1424 mark_reg_not_init(regs, caller_saved[i]);
1425
1426 /* update return register */
1427 if (fn->ret_type == RET_INTEGER) {
1428 regs[BPF_REG_0].type = UNKNOWN_VALUE;
1429 } else if (fn->ret_type == RET_VOID) {
1430 regs[BPF_REG_0].type = NOT_INIT;
1431 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
1432 struct bpf_insn_aux_data *insn_aux;
1433
1434 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
1435 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0;
1436 /* remember map_ptr, so that check_map_access()
1437 * can check 'value_size' boundary of memory access
1438 * to map element returned from bpf_map_lookup_elem()
1439 */
1440 if (meta.map_ptr == NULL) {
1441 verbose("kernel subsystem misconfigured verifier\n");
1442 return -EINVAL;
1443 }
1444 regs[BPF_REG_0].map_ptr = meta.map_ptr;
1445 regs[BPF_REG_0].id = ++env->id_gen;
1446 insn_aux = &env->insn_aux_data[insn_idx];
1447 if (!insn_aux->map_ptr)
1448 insn_aux->map_ptr = meta.map_ptr;
1449 else if (insn_aux->map_ptr != meta.map_ptr)
1450 insn_aux->map_ptr = BPF_MAP_PTR_POISON;
1451 } else {
1452 verbose("unknown return type %d of func %s#%d\n",
1453 fn->ret_type, func_id_name(func_id), func_id);
1454 return -EINVAL;
1455 }
1456
1457 err = check_map_func_compatibility(meta.map_ptr, func_id);
1458 if (err)
1459 return err;
1460
1461 if (changes_data)
1462 clear_all_pkt_pointers(env);
1463 return 0;
1464 }
1465
1466 static int check_packet_ptr_add(struct bpf_verifier_env *env,
1467 struct bpf_insn *insn)
1468 {
1469 struct bpf_reg_state *regs = env->cur_state.regs;
1470 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
1471 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
1472 struct bpf_reg_state tmp_reg;
1473 s32 imm;
1474
1475 if (BPF_SRC(insn->code) == BPF_K) {
1476 /* pkt_ptr += imm */
1477 imm = insn->imm;
1478
1479 add_imm:
1480 if (imm < 0) {
1481 verbose("addition of negative constant to packet pointer is not allowed\n");
1482 return -EACCES;
1483 }
1484 if (imm >= MAX_PACKET_OFF ||
1485 imm + dst_reg->off >= MAX_PACKET_OFF) {
1486 verbose("constant %d is too large to add to packet pointer\n",
1487 imm);
1488 return -EACCES;
1489 }
1490 /* a constant was added to pkt_ptr.
1491 * Remember it while keeping the same 'id'
1492 */
1493 dst_reg->off += imm;
1494 } else {
1495 bool had_id;
1496
1497 if (src_reg->type == PTR_TO_PACKET) {
1498 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1499 tmp_reg = *dst_reg; /* save r7 state */
1500 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
1501 src_reg = &tmp_reg; /* pretend it's src_reg state */
1502 /* if the checks below reject it, the copy won't matter,
1503 * since we're rejecting the whole program. If all ok,
1504 * then imm22 state will be added to r7
1505 * and r7 will be pkt(id=0,off=22,r=62) while
1506 * r6 will stay as pkt(id=0,off=0,r=62)
1507 */
1508 }
1509
1510 if (src_reg->type == CONST_IMM) {
1511 /* pkt_ptr += reg where reg is known constant */
1512 imm = src_reg->imm;
1513 goto add_imm;
1514 }
1515 /* disallow pkt_ptr += reg
1516 * if reg is not uknown_value with guaranteed zero upper bits
1517 * otherwise pkt_ptr may overflow and addition will become
1518 * subtraction which is not allowed
1519 */
1520 if (src_reg->type != UNKNOWN_VALUE) {
1521 verbose("cannot add '%s' to ptr_to_packet\n",
1522 reg_type_str[src_reg->type]);
1523 return -EACCES;
1524 }
1525 if (src_reg->imm < 48) {
1526 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1527 src_reg->imm);
1528 return -EACCES;
1529 }
1530
1531 had_id = (dst_reg->id != 0);
1532
1533 /* dst_reg stays as pkt_ptr type and since some positive
1534 * integer value was added to the pointer, increment its 'id'
1535 */
1536 dst_reg->id = ++env->id_gen;
1537
1538 /* something was added to pkt_ptr, set range to zero */
1539 dst_reg->aux_off += dst_reg->off;
1540 dst_reg->off = 0;
1541 dst_reg->range = 0;
1542 if (had_id)
1543 dst_reg->aux_off_align = min(dst_reg->aux_off_align,
1544 src_reg->min_align);
1545 else
1546 dst_reg->aux_off_align = src_reg->min_align;
1547 }
1548 return 0;
1549 }
1550
1551 static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
1552 {
1553 struct bpf_reg_state *regs = env->cur_state.regs;
1554 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
1555 u8 opcode = BPF_OP(insn->code);
1556 s64 imm_log2;
1557
1558 /* for type == UNKNOWN_VALUE:
1559 * imm > 0 -> number of zero upper bits
1560 * imm == 0 -> don't track which is the same as all bits can be non-zero
1561 */
1562
1563 if (BPF_SRC(insn->code) == BPF_X) {
1564 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
1565
1566 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 &&
1567 dst_reg->imm && opcode == BPF_ADD) {
1568 /* dreg += sreg
1569 * where both have zero upper bits. Adding them
1570 * can only result making one more bit non-zero
1571 * in the larger value.
1572 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1573 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1574 */
1575 dst_reg->imm = min(dst_reg->imm, src_reg->imm);
1576 dst_reg->imm--;
1577 return 0;
1578 }
1579 if (src_reg->type == CONST_IMM && src_reg->imm > 0 &&
1580 dst_reg->imm && opcode == BPF_ADD) {
1581 /* dreg += sreg
1582 * where dreg has zero upper bits and sreg is const.
1583 * Adding them can only result making one more bit
1584 * non-zero in the larger value.
1585 */
1586 imm_log2 = __ilog2_u64((long long)src_reg->imm);
1587 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1588 dst_reg->imm--;
1589 return 0;
1590 }
1591 /* all other cases non supported yet, just mark dst_reg */
1592 dst_reg->imm = 0;
1593 return 0;
1594 }
1595
1596 /* sign extend 32-bit imm into 64-bit to make sure that
1597 * negative values occupy bit 63. Note ilog2() would have
1598 * been incorrect, since sizeof(insn->imm) == 4
1599 */
1600 imm_log2 = __ilog2_u64((long long)insn->imm);
1601
1602 if (dst_reg->imm && opcode == BPF_LSH) {
1603 /* reg <<= imm
1604 * if reg was a result of 2 byte load, then its imm == 48
1605 * which means that upper 48 bits are zero and shifting this reg
1606 * left by 4 would mean that upper 44 bits are still zero
1607 */
1608 dst_reg->imm -= insn->imm;
1609 } else if (dst_reg->imm && opcode == BPF_MUL) {
1610 /* reg *= imm
1611 * if multiplying by 14 subtract 4
1612 * This is conservative calculation of upper zero bits.
1613 * It's not trying to special case insn->imm == 1 or 0 cases
1614 */
1615 dst_reg->imm -= imm_log2 + 1;
1616 } else if (opcode == BPF_AND) {
1617 /* reg &= imm */
1618 dst_reg->imm = 63 - imm_log2;
1619 } else if (dst_reg->imm && opcode == BPF_ADD) {
1620 /* reg += imm */
1621 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1622 dst_reg->imm--;
1623 } else if (opcode == BPF_RSH) {
1624 /* reg >>= imm
1625 * which means that after right shift, upper bits will be zero
1626 * note that verifier already checked that
1627 * 0 <= imm < 64 for shift insn
1628 */
1629 dst_reg->imm += insn->imm;
1630 if (unlikely(dst_reg->imm > 64))
1631 /* some dumb code did:
1632 * r2 = *(u32 *)mem;
1633 * r2 >>= 32;
1634 * and all bits are zero now */
1635 dst_reg->imm = 64;
1636 } else {
1637 /* all other alu ops, means that we don't know what will
1638 * happen to the value, mark it with unknown number of zero bits
1639 */
1640 dst_reg->imm = 0;
1641 }
1642
1643 if (dst_reg->imm < 0) {
1644 /* all 64 bits of the register can contain non-zero bits
1645 * and such value cannot be added to ptr_to_packet, since it
1646 * may overflow, mark it as unknown to avoid further eval
1647 */
1648 dst_reg->imm = 0;
1649 }
1650 return 0;
1651 }
1652
1653 static int evaluate_reg_imm_alu(struct bpf_verifier_env *env,
1654 struct bpf_insn *insn)
1655 {
1656 struct bpf_reg_state *regs = env->cur_state.regs;
1657 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
1658 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
1659 u8 opcode = BPF_OP(insn->code);
1660 u64 dst_imm = dst_reg->imm;
1661
1662 /* dst_reg->type == CONST_IMM here. Simulate execution of insns
1663 * containing ALU ops. Don't care about overflow or negative
1664 * values, just add/sub/... them; registers are in u64.
1665 */
1666 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) {
1667 dst_imm += insn->imm;
1668 } else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X &&
1669 src_reg->type == CONST_IMM) {
1670 dst_imm += src_reg->imm;
1671 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) {
1672 dst_imm -= insn->imm;
1673 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X &&
1674 src_reg->type == CONST_IMM) {
1675 dst_imm -= src_reg->imm;
1676 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) {
1677 dst_imm *= insn->imm;
1678 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X &&
1679 src_reg->type == CONST_IMM) {
1680 dst_imm *= src_reg->imm;
1681 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) {
1682 dst_imm |= insn->imm;
1683 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X &&
1684 src_reg->type == CONST_IMM) {
1685 dst_imm |= src_reg->imm;
1686 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) {
1687 dst_imm &= insn->imm;
1688 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X &&
1689 src_reg->type == CONST_IMM) {
1690 dst_imm &= src_reg->imm;
1691 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) {
1692 dst_imm >>= insn->imm;
1693 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X &&
1694 src_reg->type == CONST_IMM) {
1695 dst_imm >>= src_reg->imm;
1696 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) {
1697 dst_imm <<= insn->imm;
1698 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X &&
1699 src_reg->type == CONST_IMM) {
1700 dst_imm <<= src_reg->imm;
1701 } else {
1702 mark_reg_unknown_value(regs, insn->dst_reg);
1703 goto out;
1704 }
1705
1706 dst_reg->imm = dst_imm;
1707 out:
1708 return 0;
1709 }
1710
1711 static void check_reg_overflow(struct bpf_reg_state *reg)
1712 {
1713 if (reg->max_value > BPF_REGISTER_MAX_RANGE)
1714 reg->max_value = BPF_REGISTER_MAX_RANGE;
1715 if (reg->min_value < BPF_REGISTER_MIN_RANGE ||
1716 reg->min_value > BPF_REGISTER_MAX_RANGE)
1717 reg->min_value = BPF_REGISTER_MIN_RANGE;
1718 }
1719
1720 static u32 calc_align(u32 imm)
1721 {
1722 if (!imm)
1723 return 1U << 31;
1724 return imm - ((imm - 1) & imm);
1725 }
1726
1727 static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
1728 struct bpf_insn *insn)
1729 {
1730 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1731 s64 min_val = BPF_REGISTER_MIN_RANGE;
1732 u64 max_val = BPF_REGISTER_MAX_RANGE;
1733 u8 opcode = BPF_OP(insn->code);
1734 u32 dst_align, src_align;
1735
1736 dst_reg = &regs[insn->dst_reg];
1737 src_align = 0;
1738 if (BPF_SRC(insn->code) == BPF_X) {
1739 check_reg_overflow(&regs[insn->src_reg]);
1740 min_val = regs[insn->src_reg].min_value;
1741 max_val = regs[insn->src_reg].max_value;
1742
1743 /* If the source register is a random pointer then the
1744 * min_value/max_value values represent the range of the known
1745 * accesses into that value, not the actual min/max value of the
1746 * register itself. In this case we have to reset the reg range
1747 * values so we know it is not safe to look at.
1748 */
1749 if (regs[insn->src_reg].type != CONST_IMM &&
1750 regs[insn->src_reg].type != UNKNOWN_VALUE) {
1751 min_val = BPF_REGISTER_MIN_RANGE;
1752 max_val = BPF_REGISTER_MAX_RANGE;
1753 src_align = 0;
1754 } else {
1755 src_align = regs[insn->src_reg].min_align;
1756 }
1757 } else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
1758 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
1759 min_val = max_val = insn->imm;
1760 src_align = calc_align(insn->imm);
1761 }
1762
1763 dst_align = dst_reg->min_align;
1764
1765 /* We don't know anything about what was done to this register, mark it
1766 * as unknown.
1767 */
1768 if (min_val == BPF_REGISTER_MIN_RANGE &&
1769 max_val == BPF_REGISTER_MAX_RANGE) {
1770 reset_reg_range_values(regs, insn->dst_reg);
1771 return;
1772 }
1773
1774 /* If one of our values was at the end of our ranges then we can't just
1775 * do our normal operations to the register, we need to set the values
1776 * to the min/max since they are undefined.
1777 */
1778 if (min_val == BPF_REGISTER_MIN_RANGE)
1779 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1780 if (max_val == BPF_REGISTER_MAX_RANGE)
1781 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1782
1783 switch (opcode) {
1784 case BPF_ADD:
1785 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1786 dst_reg->min_value += min_val;
1787 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1788 dst_reg->max_value += max_val;
1789 dst_reg->min_align = min(src_align, dst_align);
1790 break;
1791 case BPF_SUB:
1792 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1793 dst_reg->min_value -= min_val;
1794 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1795 dst_reg->max_value -= max_val;
1796 dst_reg->min_align = min(src_align, dst_align);
1797 break;
1798 case BPF_MUL:
1799 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1800 dst_reg->min_value *= min_val;
1801 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1802 dst_reg->max_value *= max_val;
1803 dst_reg->min_align = max(src_align, dst_align);
1804 break;
1805 case BPF_AND:
1806 /* Disallow AND'ing of negative numbers, ain't nobody got time
1807 * for that. Otherwise the minimum is 0 and the max is the max
1808 * value we could AND against.
1809 */
1810 if (min_val < 0)
1811 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1812 else
1813 dst_reg->min_value = 0;
1814 dst_reg->max_value = max_val;
1815 dst_reg->min_align = max(src_align, dst_align);
1816 break;
1817 case BPF_LSH:
1818 /* Gotta have special overflow logic here, if we're shifting
1819 * more than MAX_RANGE then just assume we have an invalid
1820 * range.
1821 */
1822 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) {
1823 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1824 dst_reg->min_align = 1;
1825 } else {
1826 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE)
1827 dst_reg->min_value <<= min_val;
1828 if (!dst_reg->min_align)
1829 dst_reg->min_align = 1;
1830 dst_reg->min_align <<= min_val;
1831 }
1832 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE))
1833 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1834 else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1835 dst_reg->max_value <<= max_val;
1836 break;
1837 case BPF_RSH:
1838 /* RSH by a negative number is undefined, and the BPF_RSH is an
1839 * unsigned shift, so make the appropriate casts.
1840 */
1841 if (min_val < 0 || dst_reg->min_value < 0) {
1842 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1843 } else {
1844 dst_reg->min_value =
1845 (u64)(dst_reg->min_value) >> min_val;
1846 }
1847 if (min_val < 0) {
1848 dst_reg->min_align = 1;
1849 } else {
1850 dst_reg->min_align >>= (u64) min_val;
1851 if (!dst_reg->min_align)
1852 dst_reg->min_align = 1;
1853 }
1854 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE)
1855 dst_reg->max_value >>= max_val;
1856 break;
1857 default:
1858 reset_reg_range_values(regs, insn->dst_reg);
1859 break;
1860 }
1861
1862 check_reg_overflow(dst_reg);
1863 }
1864
1865 /* check validity of 32-bit and 64-bit arithmetic operations */
1866 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
1867 {
1868 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1869 u8 opcode = BPF_OP(insn->code);
1870 int err;
1871
1872 if (opcode == BPF_END || opcode == BPF_NEG) {
1873 if (opcode == BPF_NEG) {
1874 if (BPF_SRC(insn->code) != 0 ||
1875 insn->src_reg != BPF_REG_0 ||
1876 insn->off != 0 || insn->imm != 0) {
1877 verbose("BPF_NEG uses reserved fields\n");
1878 return -EINVAL;
1879 }
1880 } else {
1881 if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
1882 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
1883 verbose("BPF_END uses reserved fields\n");
1884 return -EINVAL;
1885 }
1886 }
1887
1888 /* check src operand */
1889 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1890 if (err)
1891 return err;
1892
1893 if (is_pointer_value(env, insn->dst_reg)) {
1894 verbose("R%d pointer arithmetic prohibited\n",
1895 insn->dst_reg);
1896 return -EACCES;
1897 }
1898
1899 /* check dest operand */
1900 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1901 if (err)
1902 return err;
1903
1904 } else if (opcode == BPF_MOV) {
1905
1906 if (BPF_SRC(insn->code) == BPF_X) {
1907 if (insn->imm != 0 || insn->off != 0) {
1908 verbose("BPF_MOV uses reserved fields\n");
1909 return -EINVAL;
1910 }
1911
1912 /* check src operand */
1913 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1914 if (err)
1915 return err;
1916 } else {
1917 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1918 verbose("BPF_MOV uses reserved fields\n");
1919 return -EINVAL;
1920 }
1921 }
1922
1923 /* check dest operand */
1924 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1925 if (err)
1926 return err;
1927
1928 /* we are setting our register to something new, we need to
1929 * reset its range values.
1930 */
1931 reset_reg_range_values(regs, insn->dst_reg);
1932
1933 if (BPF_SRC(insn->code) == BPF_X) {
1934 if (BPF_CLASS(insn->code) == BPF_ALU64) {
1935 /* case: R1 = R2
1936 * copy register state to dest reg
1937 */
1938 regs[insn->dst_reg] = regs[insn->src_reg];
1939 } else {
1940 if (is_pointer_value(env, insn->src_reg)) {
1941 verbose("R%d partial copy of pointer\n",
1942 insn->src_reg);
1943 return -EACCES;
1944 }
1945 mark_reg_unknown_value(regs, insn->dst_reg);
1946 }
1947 } else {
1948 /* case: R = imm
1949 * remember the value we stored into this reg
1950 */
1951 regs[insn->dst_reg].type = CONST_IMM;
1952 regs[insn->dst_reg].imm = insn->imm;
1953 regs[insn->dst_reg].max_value = insn->imm;
1954 regs[insn->dst_reg].min_value = insn->imm;
1955 regs[insn->dst_reg].min_align = calc_align(insn->imm);
1956 }
1957
1958 } else if (opcode > BPF_END) {
1959 verbose("invalid BPF_ALU opcode %x\n", opcode);
1960 return -EINVAL;
1961
1962 } else { /* all other ALU ops: and, sub, xor, add, ... */
1963
1964 if (BPF_SRC(insn->code) == BPF_X) {
1965 if (insn->imm != 0 || insn->off != 0) {
1966 verbose("BPF_ALU uses reserved fields\n");
1967 return -EINVAL;
1968 }
1969 /* check src1 operand */
1970 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1971 if (err)
1972 return err;
1973 } else {
1974 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1975 verbose("BPF_ALU uses reserved fields\n");
1976 return -EINVAL;
1977 }
1978 }
1979
1980 /* check src2 operand */
1981 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1982 if (err)
1983 return err;
1984
1985 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
1986 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
1987 verbose("div by zero\n");
1988 return -EINVAL;
1989 }
1990
1991 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
1992 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
1993 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
1994
1995 if (insn->imm < 0 || insn->imm >= size) {
1996 verbose("invalid shift %d\n", insn->imm);
1997 return -EINVAL;
1998 }
1999 }
2000
2001 /* check dest operand */
2002 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
2003 if (err)
2004 return err;
2005
2006 dst_reg = &regs[insn->dst_reg];
2007
2008 /* first we want to adjust our ranges. */
2009 adjust_reg_min_max_vals(env, insn);
2010
2011 /* pattern match 'bpf_add Rx, imm' instruction */
2012 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
2013 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) {
2014 dst_reg->type = PTR_TO_STACK;
2015 dst_reg->imm = insn->imm;
2016 return 0;
2017 } else if (opcode == BPF_ADD &&
2018 BPF_CLASS(insn->code) == BPF_ALU64 &&
2019 dst_reg->type == PTR_TO_STACK &&
2020 ((BPF_SRC(insn->code) == BPF_X &&
2021 regs[insn->src_reg].type == CONST_IMM) ||
2022 BPF_SRC(insn->code) == BPF_K)) {
2023 if (BPF_SRC(insn->code) == BPF_X)
2024 dst_reg->imm += regs[insn->src_reg].imm;
2025 else
2026 dst_reg->imm += insn->imm;
2027 return 0;
2028 } else if (opcode == BPF_ADD &&
2029 BPF_CLASS(insn->code) == BPF_ALU64 &&
2030 (dst_reg->type == PTR_TO_PACKET ||
2031 (BPF_SRC(insn->code) == BPF_X &&
2032 regs[insn->src_reg].type == PTR_TO_PACKET))) {
2033 /* ptr_to_packet += K|X */
2034 return check_packet_ptr_add(env, insn);
2035 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
2036 dst_reg->type == UNKNOWN_VALUE &&
2037 env->allow_ptr_leaks) {
2038 /* unknown += K|X */
2039 return evaluate_reg_alu(env, insn);
2040 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
2041 dst_reg->type == CONST_IMM &&
2042 env->allow_ptr_leaks) {
2043 /* reg_imm += K|X */
2044 return evaluate_reg_imm_alu(env, insn);
2045 } else if (is_pointer_value(env, insn->dst_reg)) {
2046 verbose("R%d pointer arithmetic prohibited\n",
2047 insn->dst_reg);
2048 return -EACCES;
2049 } else if (BPF_SRC(insn->code) == BPF_X &&
2050 is_pointer_value(env, insn->src_reg)) {
2051 verbose("R%d pointer arithmetic prohibited\n",
2052 insn->src_reg);
2053 return -EACCES;
2054 }
2055
2056 /* If we did pointer math on a map value then just set it to our
2057 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
2058 * loads to this register appropriately, otherwise just mark the
2059 * register as unknown.
2060 */
2061 if (env->allow_ptr_leaks &&
2062 BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD &&
2063 (dst_reg->type == PTR_TO_MAP_VALUE ||
2064 dst_reg->type == PTR_TO_MAP_VALUE_ADJ))
2065 dst_reg->type = PTR_TO_MAP_VALUE_ADJ;
2066 else
2067 mark_reg_unknown_value(regs, insn->dst_reg);
2068 }
2069
2070 return 0;
2071 }
2072
2073 static void find_good_pkt_pointers(struct bpf_verifier_state *state,
2074 struct bpf_reg_state *dst_reg)
2075 {
2076 struct bpf_reg_state *regs = state->regs, *reg;
2077 int i;
2078
2079 /* LLVM can generate two kind of checks:
2080 *
2081 * Type 1:
2082 *
2083 * r2 = r3;
2084 * r2 += 8;
2085 * if (r2 > pkt_end) goto <handle exception>
2086 * <access okay>
2087 *
2088 * Where:
2089 * r2 == dst_reg, pkt_end == src_reg
2090 * r2=pkt(id=n,off=8,r=0)
2091 * r3=pkt(id=n,off=0,r=0)
2092 *
2093 * Type 2:
2094 *
2095 * r2 = r3;
2096 * r2 += 8;
2097 * if (pkt_end >= r2) goto <access okay>
2098 * <handle exception>
2099 *
2100 * Where:
2101 * pkt_end == dst_reg, r2 == src_reg
2102 * r2=pkt(id=n,off=8,r=0)
2103 * r3=pkt(id=n,off=0,r=0)
2104 *
2105 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
2106 * so that range of bytes [r3, r3 + 8) is safe to access.
2107 */
2108
2109 for (i = 0; i < MAX_BPF_REG; i++)
2110 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id)
2111 /* keep the maximum range already checked */
2112 regs[i].range = max(regs[i].range, dst_reg->off);
2113
2114 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
2115 if (state->stack_slot_type[i] != STACK_SPILL)
2116 continue;
2117 reg = &state->spilled_regs[i / BPF_REG_SIZE];
2118 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id)
2119 reg->range = max(reg->range, dst_reg->off);
2120 }
2121 }
2122
2123 /* Adjusts the register min/max values in the case that the dst_reg is the
2124 * variable register that we are working on, and src_reg is a constant or we're
2125 * simply doing a BPF_K check.
2126 */
2127 static void reg_set_min_max(struct bpf_reg_state *true_reg,
2128 struct bpf_reg_state *false_reg, u64 val,
2129 u8 opcode)
2130 {
2131 switch (opcode) {
2132 case BPF_JEQ:
2133 /* If this is false then we know nothing Jon Snow, but if it is
2134 * true then we know for sure.
2135 */
2136 true_reg->max_value = true_reg->min_value = val;
2137 break;
2138 case BPF_JNE:
2139 /* If this is true we know nothing Jon Snow, but if it is false
2140 * we know the value for sure;
2141 */
2142 false_reg->max_value = false_reg->min_value = val;
2143 break;
2144 case BPF_JGT:
2145 /* Unsigned comparison, the minimum value is 0. */
2146 false_reg->min_value = 0;
2147 /* fallthrough */
2148 case BPF_JSGT:
2149 /* If this is false then we know the maximum val is val,
2150 * otherwise we know the min val is val+1.
2151 */
2152 false_reg->max_value = val;
2153 true_reg->min_value = val + 1;
2154 break;
2155 case BPF_JGE:
2156 /* Unsigned comparison, the minimum value is 0. */
2157 false_reg->min_value = 0;
2158 /* fallthrough */
2159 case BPF_JSGE:
2160 /* If this is false then we know the maximum value is val - 1,
2161 * otherwise we know the mimimum value is val.
2162 */
2163 false_reg->max_value = val - 1;
2164 true_reg->min_value = val;
2165 break;
2166 default:
2167 break;
2168 }
2169
2170 check_reg_overflow(false_reg);
2171 check_reg_overflow(true_reg);
2172 }
2173
2174 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
2175 * is the variable reg.
2176 */
2177 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
2178 struct bpf_reg_state *false_reg, u64 val,
2179 u8 opcode)
2180 {
2181 switch (opcode) {
2182 case BPF_JEQ:
2183 /* If this is false then we know nothing Jon Snow, but if it is
2184 * true then we know for sure.
2185 */
2186 true_reg->max_value = true_reg->min_value = val;
2187 break;
2188 case BPF_JNE:
2189 /* If this is true we know nothing Jon Snow, but if it is false
2190 * we know the value for sure;
2191 */
2192 false_reg->max_value = false_reg->min_value = val;
2193 break;
2194 case BPF_JGT:
2195 /* Unsigned comparison, the minimum value is 0. */
2196 true_reg->min_value = 0;
2197 /* fallthrough */
2198 case BPF_JSGT:
2199 /*
2200 * If this is false, then the val is <= the register, if it is
2201 * true the register <= to the val.
2202 */
2203 false_reg->min_value = val;
2204 true_reg->max_value = val - 1;
2205 break;
2206 case BPF_JGE:
2207 /* Unsigned comparison, the minimum value is 0. */
2208 true_reg->min_value = 0;
2209 /* fallthrough */
2210 case BPF_JSGE:
2211 /* If this is false then constant < register, if it is true then
2212 * the register < constant.
2213 */
2214 false_reg->min_value = val + 1;
2215 true_reg->max_value = val;
2216 break;
2217 default:
2218 break;
2219 }
2220
2221 check_reg_overflow(false_reg);
2222 check_reg_overflow(true_reg);
2223 }
2224
2225 static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
2226 enum bpf_reg_type type)
2227 {
2228 struct bpf_reg_state *reg = &regs[regno];
2229
2230 if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
2231 if (type == UNKNOWN_VALUE) {
2232 __mark_reg_unknown_value(regs, regno);
2233 } else if (reg->map_ptr->inner_map_meta) {
2234 reg->type = CONST_PTR_TO_MAP;
2235 reg->map_ptr = reg->map_ptr->inner_map_meta;
2236 } else {
2237 reg->type = type;
2238 }
2239 /* We don't need id from this point onwards anymore, thus we
2240 * should better reset it, so that state pruning has chances
2241 * to take effect.
2242 */
2243 reg->id = 0;
2244 }
2245 }
2246
2247 /* The logic is similar to find_good_pkt_pointers(), both could eventually
2248 * be folded together at some point.
2249 */
2250 static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
2251 enum bpf_reg_type type)
2252 {
2253 struct bpf_reg_state *regs = state->regs;
2254 u32 id = regs[regno].id;
2255 int i;
2256
2257 for (i = 0; i < MAX_BPF_REG; i++)
2258 mark_map_reg(regs, i, id, type);
2259
2260 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
2261 if (state->stack_slot_type[i] != STACK_SPILL)
2262 continue;
2263 mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type);
2264 }
2265 }
2266
2267 static int check_cond_jmp_op(struct bpf_verifier_env *env,
2268 struct bpf_insn *insn, int *insn_idx)
2269 {
2270 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
2271 struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
2272 u8 opcode = BPF_OP(insn->code);
2273 int err;
2274
2275 if (opcode > BPF_EXIT) {
2276 verbose("invalid BPF_JMP opcode %x\n", opcode);
2277 return -EINVAL;
2278 }
2279
2280 if (BPF_SRC(insn->code) == BPF_X) {
2281 if (insn->imm != 0) {
2282 verbose("BPF_JMP uses reserved fields\n");
2283 return -EINVAL;
2284 }
2285
2286 /* check src1 operand */
2287 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2288 if (err)
2289 return err;
2290
2291 if (is_pointer_value(env, insn->src_reg)) {
2292 verbose("R%d pointer comparison prohibited\n",
2293 insn->src_reg);
2294 return -EACCES;
2295 }
2296 } else {
2297 if (insn->src_reg != BPF_REG_0) {
2298 verbose("BPF_JMP uses reserved fields\n");
2299 return -EINVAL;
2300 }
2301 }
2302
2303 /* check src2 operand */
2304 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2305 if (err)
2306 return err;
2307
2308 dst_reg = &regs[insn->dst_reg];
2309
2310 /* detect if R == 0 where R was initialized to zero earlier */
2311 if (BPF_SRC(insn->code) == BPF_K &&
2312 (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2313 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) {
2314 if (opcode == BPF_JEQ) {
2315 /* if (imm == imm) goto pc+off;
2316 * only follow the goto, ignore fall-through
2317 */
2318 *insn_idx += insn->off;
2319 return 0;
2320 } else {
2321 /* if (imm != imm) goto pc+off;
2322 * only follow fall-through branch, since
2323 * that's where the program will go
2324 */
2325 return 0;
2326 }
2327 }
2328
2329 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
2330 if (!other_branch)
2331 return -EFAULT;
2332
2333 /* detect if we are comparing against a constant value so we can adjust
2334 * our min/max values for our dst register.
2335 */
2336 if (BPF_SRC(insn->code) == BPF_X) {
2337 if (regs[insn->src_reg].type == CONST_IMM)
2338 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2339 dst_reg, regs[insn->src_reg].imm,
2340 opcode);
2341 else if (dst_reg->type == CONST_IMM)
2342 reg_set_min_max_inv(&other_branch->regs[insn->src_reg],
2343 &regs[insn->src_reg], dst_reg->imm,
2344 opcode);
2345 } else {
2346 reg_set_min_max(&other_branch->regs[insn->dst_reg],
2347 dst_reg, insn->imm, opcode);
2348 }
2349
2350 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
2351 if (BPF_SRC(insn->code) == BPF_K &&
2352 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
2353 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
2354 /* Mark all identical map registers in each branch as either
2355 * safe or unknown depending R == 0 or R != 0 conditional.
2356 */
2357 mark_map_regs(this_branch, insn->dst_reg,
2358 opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE);
2359 mark_map_regs(other_branch, insn->dst_reg,
2360 opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE);
2361 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
2362 dst_reg->type == PTR_TO_PACKET &&
2363 regs[insn->src_reg].type == PTR_TO_PACKET_END) {
2364 find_good_pkt_pointers(this_branch, dst_reg);
2365 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
2366 dst_reg->type == PTR_TO_PACKET_END &&
2367 regs[insn->src_reg].type == PTR_TO_PACKET) {
2368 find_good_pkt_pointers(other_branch, &regs[insn->src_reg]);
2369 } else if (is_pointer_value(env, insn->dst_reg)) {
2370 verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
2371 return -EACCES;
2372 }
2373 if (log_level)
2374 print_verifier_state(this_branch);
2375 return 0;
2376 }
2377
2378 /* return the map pointer stored inside BPF_LD_IMM64 instruction */
2379 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
2380 {
2381 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
2382
2383 return (struct bpf_map *) (unsigned long) imm64;
2384 }
2385
2386 /* verify BPF_LD_IMM64 instruction */
2387 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
2388 {
2389 struct bpf_reg_state *regs = env->cur_state.regs;
2390 int err;
2391
2392 if (BPF_SIZE(insn->code) != BPF_DW) {
2393 verbose("invalid BPF_LD_IMM insn\n");
2394 return -EINVAL;
2395 }
2396 if (insn->off != 0) {
2397 verbose("BPF_LD_IMM64 uses reserved fields\n");
2398 return -EINVAL;
2399 }
2400
2401 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2402 if (err)
2403 return err;
2404
2405 if (insn->src_reg == 0) {
2406 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
2407
2408 regs[insn->dst_reg].type = CONST_IMM;
2409 regs[insn->dst_reg].imm = imm;
2410 return 0;
2411 }
2412
2413 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2414 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
2415
2416 regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
2417 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
2418 return 0;
2419 }
2420
2421 static bool may_access_skb(enum bpf_prog_type type)
2422 {
2423 switch (type) {
2424 case BPF_PROG_TYPE_SOCKET_FILTER:
2425 case BPF_PROG_TYPE_SCHED_CLS:
2426 case BPF_PROG_TYPE_SCHED_ACT:
2427 return true;
2428 default:
2429 return false;
2430 }
2431 }
2432
2433 /* verify safety of LD_ABS|LD_IND instructions:
2434 * - they can only appear in the programs where ctx == skb
2435 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2436 * preserve R6-R9, and store return value into R0
2437 *
2438 * Implicit input:
2439 * ctx == skb == R6 == CTX
2440 *
2441 * Explicit input:
2442 * SRC == any register
2443 * IMM == 32-bit immediate
2444 *
2445 * Output:
2446 * R0 - 8/16/32-bit skb data converted to cpu endianness
2447 */
2448 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
2449 {
2450 struct bpf_reg_state *regs = env->cur_state.regs;
2451 u8 mode = BPF_MODE(insn->code);
2452 int i, err;
2453
2454 if (!may_access_skb(env->prog->type)) {
2455 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
2456 return -EINVAL;
2457 }
2458
2459 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
2460 BPF_SIZE(insn->code) == BPF_DW ||
2461 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
2462 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
2463 return -EINVAL;
2464 }
2465
2466 /* check whether implicit source operand (register R6) is readable */
2467 err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
2468 if (err)
2469 return err;
2470
2471 if (regs[BPF_REG_6].type != PTR_TO_CTX) {
2472 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2473 return -EINVAL;
2474 }
2475
2476 if (mode == BPF_IND) {
2477 /* check explicit source operand */
2478 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2479 if (err)
2480 return err;
2481 }
2482
2483 /* reset caller saved regs to unreadable */
2484 for (i = 0; i < CALLER_SAVED_REGS; i++)
2485 mark_reg_not_init(regs, caller_saved[i]);
2486
2487 /* mark destination R0 register as readable, since it contains
2488 * the value fetched from the packet
2489 */
2490 regs[BPF_REG_0].type = UNKNOWN_VALUE;
2491 return 0;
2492 }
2493
2494 /* non-recursive DFS pseudo code
2495 * 1 procedure DFS-iterative(G,v):
2496 * 2 label v as discovered
2497 * 3 let S be a stack
2498 * 4 S.push(v)
2499 * 5 while S is not empty
2500 * 6 t <- S.pop()
2501 * 7 if t is what we're looking for:
2502 * 8 return t
2503 * 9 for all edges e in G.adjacentEdges(t) do
2504 * 10 if edge e is already labelled
2505 * 11 continue with the next edge
2506 * 12 w <- G.adjacentVertex(t,e)
2507 * 13 if vertex w is not discovered and not explored
2508 * 14 label e as tree-edge
2509 * 15 label w as discovered
2510 * 16 S.push(w)
2511 * 17 continue at 5
2512 * 18 else if vertex w is discovered
2513 * 19 label e as back-edge
2514 * 20 else
2515 * 21 // vertex w is explored
2516 * 22 label e as forward- or cross-edge
2517 * 23 label t as explored
2518 * 24 S.pop()
2519 *
2520 * convention:
2521 * 0x10 - discovered
2522 * 0x11 - discovered and fall-through edge labelled
2523 * 0x12 - discovered and fall-through and branch edges labelled
2524 * 0x20 - explored
2525 */
2526
2527 enum {
2528 DISCOVERED = 0x10,
2529 EXPLORED = 0x20,
2530 FALLTHROUGH = 1,
2531 BRANCH = 2,
2532 };
2533
2534 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
2535
2536 static int *insn_stack; /* stack of insns to process */
2537 static int cur_stack; /* current stack index */
2538 static int *insn_state;
2539
2540 /* t, w, e - match pseudo-code above:
2541 * t - index of current instruction
2542 * w - next instruction
2543 * e - edge
2544 */
2545 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
2546 {
2547 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
2548 return 0;
2549
2550 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
2551 return 0;
2552
2553 if (w < 0 || w >= env->prog->len) {
2554 verbose("jump out of range from insn %d to %d\n", t, w);
2555 return -EINVAL;
2556 }
2557
2558 if (e == BRANCH)
2559 /* mark branch target for state pruning */
2560 env->explored_states[w] = STATE_LIST_MARK;
2561
2562 if (insn_state[w] == 0) {
2563 /* tree-edge */
2564 insn_state[t] = DISCOVERED | e;
2565 insn_state[w] = DISCOVERED;
2566 if (cur_stack >= env->prog->len)
2567 return -E2BIG;
2568 insn_stack[cur_stack++] = w;
2569 return 1;
2570 } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
2571 verbose("back-edge from insn %d to %d\n", t, w);
2572 return -EINVAL;
2573 } else if (insn_state[w] == EXPLORED) {
2574 /* forward- or cross-edge */
2575 insn_state[t] = DISCOVERED | e;
2576 } else {
2577 verbose("insn state internal bug\n");
2578 return -EFAULT;
2579 }
2580 return 0;
2581 }
2582
2583 /* non-recursive depth-first-search to detect loops in BPF program
2584 * loop == back-edge in directed graph
2585 */
2586 static int check_cfg(struct bpf_verifier_env *env)
2587 {
2588 struct bpf_insn *insns = env->prog->insnsi;
2589 int insn_cnt = env->prog->len;
2590 int ret = 0;
2591 int i, t;
2592
2593 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2594 if (!insn_state)
2595 return -ENOMEM;
2596
2597 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2598 if (!insn_stack) {
2599 kfree(insn_state);
2600 return -ENOMEM;
2601 }
2602
2603 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
2604 insn_stack[0] = 0; /* 0 is the first instruction */
2605 cur_stack = 1;
2606
2607 peek_stack:
2608 if (cur_stack == 0)
2609 goto check_state;
2610 t = insn_stack[cur_stack - 1];
2611
2612 if (BPF_CLASS(insns[t].code) == BPF_JMP) {
2613 u8 opcode = BPF_OP(insns[t].code);
2614
2615 if (opcode == BPF_EXIT) {
2616 goto mark_explored;
2617 } else if (opcode == BPF_CALL) {
2618 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2619 if (ret == 1)
2620 goto peek_stack;
2621 else if (ret < 0)
2622 goto err_free;
2623 if (t + 1 < insn_cnt)
2624 env->explored_states[t + 1] = STATE_LIST_MARK;
2625 } else if (opcode == BPF_JA) {
2626 if (BPF_SRC(insns[t].code) != BPF_K) {
2627 ret = -EINVAL;
2628 goto err_free;
2629 }
2630 /* unconditional jump with single edge */
2631 ret = push_insn(t, t + insns[t].off + 1,
2632 FALLTHROUGH, env);
2633 if (ret == 1)
2634 goto peek_stack;
2635 else if (ret < 0)
2636 goto err_free;
2637 /* tell verifier to check for equivalent states
2638 * after every call and jump
2639 */
2640 if (t + 1 < insn_cnt)
2641 env->explored_states[t + 1] = STATE_LIST_MARK;
2642 } else {
2643 /* conditional jump with two edges */
2644 env->explored_states[t] = STATE_LIST_MARK;
2645 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2646 if (ret == 1)
2647 goto peek_stack;
2648 else if (ret < 0)
2649 goto err_free;
2650
2651 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
2652 if (ret == 1)
2653 goto peek_stack;
2654 else if (ret < 0)
2655 goto err_free;
2656 }
2657 } else {
2658 /* all other non-branch instructions with single
2659 * fall-through edge
2660 */
2661 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2662 if (ret == 1)
2663 goto peek_stack;
2664 else if (ret < 0)
2665 goto err_free;
2666 }
2667
2668 mark_explored:
2669 insn_state[t] = EXPLORED;
2670 if (cur_stack-- <= 0) {
2671 verbose("pop stack internal bug\n");
2672 ret = -EFAULT;
2673 goto err_free;
2674 }
2675 goto peek_stack;
2676
2677 check_state:
2678 for (i = 0; i < insn_cnt; i++) {
2679 if (insn_state[i] != EXPLORED) {
2680 verbose("unreachable insn %d\n", i);
2681 ret = -EINVAL;
2682 goto err_free;
2683 }
2684 }
2685 ret = 0; /* cfg looks good */
2686
2687 err_free:
2688 kfree(insn_state);
2689 kfree(insn_stack);
2690 return ret;
2691 }
2692
2693 /* the following conditions reduce the number of explored insns
2694 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2695 */
2696 static bool compare_ptrs_to_packet(struct bpf_verifier_env *env,
2697 struct bpf_reg_state *old,
2698 struct bpf_reg_state *cur)
2699 {
2700 if (old->id != cur->id)
2701 return false;
2702
2703 /* old ptr_to_packet is more conservative, since it allows smaller
2704 * range. Ex:
2705 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2706 * old(off=0,r=10) means that with range=10 the verifier proceeded
2707 * further and found no issues with the program. Now we're in the same
2708 * spot with cur(off=0,r=20), so we're safe too, since anything further
2709 * will only be looking at most 10 bytes after this pointer.
2710 */
2711 if (old->off == cur->off && old->range < cur->range)
2712 return true;
2713
2714 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2715 * since both cannot be used for packet access and safe(old)
2716 * pointer has smaller off that could be used for further
2717 * 'if (ptr > data_end)' check
2718 * Ex:
2719 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2720 * that we cannot access the packet.
2721 * The safe range is:
2722 * [ptr, ptr + range - off)
2723 * so whenever off >=range, it means no safe bytes from this pointer.
2724 * When comparing old->off <= cur->off, it means that older code
2725 * went with smaller offset and that offset was later
2726 * used to figure out the safe range after 'if (ptr > data_end)' check
2727 * Say, 'old' state was explored like:
2728 * ... R3(off=0, r=0)
2729 * R4 = R3 + 20
2730 * ... now R4(off=20,r=0) <-- here
2731 * if (R4 > data_end)
2732 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2733 * ... the code further went all the way to bpf_exit.
2734 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2735 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2736 * goes further, such cur_R4 will give larger safe packet range after
2737 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2738 * so they will be good with r=30 and we can prune the search.
2739 */
2740 if (!env->strict_alignment && old->off <= cur->off &&
2741 old->off >= old->range && cur->off >= cur->range)
2742 return true;
2743
2744 return false;
2745 }
2746
2747 /* compare two verifier states
2748 *
2749 * all states stored in state_list are known to be valid, since
2750 * verifier reached 'bpf_exit' instruction through them
2751 *
2752 * this function is called when verifier exploring different branches of
2753 * execution popped from the state stack. If it sees an old state that has
2754 * more strict register state and more strict stack state then this execution
2755 * branch doesn't need to be explored further, since verifier already
2756 * concluded that more strict state leads to valid finish.
2757 *
2758 * Therefore two states are equivalent if register state is more conservative
2759 * and explored stack state is more conservative than the current one.
2760 * Example:
2761 * explored current
2762 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2763 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2764 *
2765 * In other words if current stack state (one being explored) has more
2766 * valid slots than old one that already passed validation, it means
2767 * the verifier can stop exploring and conclude that current state is valid too
2768 *
2769 * Similarly with registers. If explored state has register type as invalid
2770 * whereas register type in current state is meaningful, it means that
2771 * the current state will reach 'bpf_exit' instruction safely
2772 */
2773 static bool states_equal(struct bpf_verifier_env *env,
2774 struct bpf_verifier_state *old,
2775 struct bpf_verifier_state *cur)
2776 {
2777 bool varlen_map_access = env->varlen_map_value_access;
2778 struct bpf_reg_state *rold, *rcur;
2779 int i;
2780
2781 for (i = 0; i < MAX_BPF_REG; i++) {
2782 rold = &old->regs[i];
2783 rcur = &cur->regs[i];
2784
2785 if (memcmp(rold, rcur, sizeof(*rold)) == 0)
2786 continue;
2787
2788 /* If the ranges were not the same, but everything else was and
2789 * we didn't do a variable access into a map then we are a-ok.
2790 */
2791 if (!varlen_map_access &&
2792 memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0)
2793 continue;
2794
2795 /* If we didn't map access then again we don't care about the
2796 * mismatched range values and it's ok if our old type was
2797 * UNKNOWN and we didn't go to a NOT_INIT'ed reg.
2798 */
2799 if (rold->type == NOT_INIT ||
2800 (!varlen_map_access && rold->type == UNKNOWN_VALUE &&
2801 rcur->type != NOT_INIT))
2802 continue;
2803
2804 /* Don't care about the reg->id in this case. */
2805 if (rold->type == PTR_TO_MAP_VALUE_OR_NULL &&
2806 rcur->type == PTR_TO_MAP_VALUE_OR_NULL &&
2807 rold->map_ptr == rcur->map_ptr)
2808 continue;
2809
2810 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET &&
2811 compare_ptrs_to_packet(env, rold, rcur))
2812 continue;
2813
2814 return false;
2815 }
2816
2817 for (i = 0; i < MAX_BPF_STACK; i++) {
2818 if (old->stack_slot_type[i] == STACK_INVALID)
2819 continue;
2820 if (old->stack_slot_type[i] != cur->stack_slot_type[i])
2821 /* Ex: old explored (safe) state has STACK_SPILL in
2822 * this stack slot, but current has has STACK_MISC ->
2823 * this verifier states are not equivalent,
2824 * return false to continue verification of this path
2825 */
2826 return false;
2827 if (i % BPF_REG_SIZE)
2828 continue;
2829 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
2830 &cur->spilled_regs[i / BPF_REG_SIZE],
2831 sizeof(old->spilled_regs[0])))
2832 /* when explored and current stack slot types are
2833 * the same, check that stored pointers types
2834 * are the same as well.
2835 * Ex: explored safe path could have stored
2836 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
2837 * but current path has stored:
2838 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
2839 * such verifier states are not equivalent.
2840 * return false to continue verification of this path
2841 */
2842 return false;
2843 else
2844 continue;
2845 }
2846 return true;
2847 }
2848
2849 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
2850 {
2851 struct bpf_verifier_state_list *new_sl;
2852 struct bpf_verifier_state_list *sl;
2853
2854 sl = env->explored_states[insn_idx];
2855 if (!sl)
2856 /* this 'insn_idx' instruction wasn't marked, so we will not
2857 * be doing state search here
2858 */
2859 return 0;
2860
2861 while (sl != STATE_LIST_MARK) {
2862 if (states_equal(env, &sl->state, &env->cur_state))
2863 /* reached equivalent register/stack state,
2864 * prune the search
2865 */
2866 return 1;
2867 sl = sl->next;
2868 }
2869
2870 /* there were no equivalent states, remember current one.
2871 * technically the current state is not proven to be safe yet,
2872 * but it will either reach bpf_exit (which means it's safe) or
2873 * it will be rejected. Since there are no loops, we won't be
2874 * seeing this 'insn_idx' instruction again on the way to bpf_exit
2875 */
2876 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
2877 if (!new_sl)
2878 return -ENOMEM;
2879
2880 /* add new state to the head of linked list */
2881 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
2882 new_sl->next = env->explored_states[insn_idx];
2883 env->explored_states[insn_idx] = new_sl;
2884 return 0;
2885 }
2886
2887 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
2888 int insn_idx, int prev_insn_idx)
2889 {
2890 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
2891 return 0;
2892
2893 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
2894 }
2895
2896 static int do_check(struct bpf_verifier_env *env)
2897 {
2898 struct bpf_verifier_state *state = &env->cur_state;
2899 struct bpf_insn *insns = env->prog->insnsi;
2900 struct bpf_reg_state *regs = state->regs;
2901 int insn_cnt = env->prog->len;
2902 int insn_idx, prev_insn_idx = 0;
2903 int insn_processed = 0;
2904 bool do_print_state = false;
2905
2906 init_reg_state(regs);
2907 insn_idx = 0;
2908 env->varlen_map_value_access = false;
2909 for (;;) {
2910 struct bpf_insn *insn;
2911 u8 class;
2912 int err;
2913
2914 if (insn_idx >= insn_cnt) {
2915 verbose("invalid insn idx %d insn_cnt %d\n",
2916 insn_idx, insn_cnt);
2917 return -EFAULT;
2918 }
2919
2920 insn = &insns[insn_idx];
2921 class = BPF_CLASS(insn->code);
2922
2923 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
2924 verbose("BPF program is too large. Processed %d insn\n",
2925 insn_processed);
2926 return -E2BIG;
2927 }
2928
2929 err = is_state_visited(env, insn_idx);
2930 if (err < 0)
2931 return err;
2932 if (err == 1) {
2933 /* found equivalent state, can prune the search */
2934 if (log_level) {
2935 if (do_print_state)
2936 verbose("\nfrom %d to %d: safe\n",
2937 prev_insn_idx, insn_idx);
2938 else
2939 verbose("%d: safe\n", insn_idx);
2940 }
2941 goto process_bpf_exit;
2942 }
2943
2944 if (need_resched())
2945 cond_resched();
2946
2947 if (log_level > 1 || (log_level && do_print_state)) {
2948 if (log_level > 1)
2949 verbose("%d:", insn_idx);
2950 else
2951 verbose("\nfrom %d to %d:",
2952 prev_insn_idx, insn_idx);
2953 print_verifier_state(&env->cur_state);
2954 do_print_state = false;
2955 }
2956
2957 if (log_level) {
2958 verbose("%d: ", insn_idx);
2959 print_bpf_insn(env, insn);
2960 }
2961
2962 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
2963 if (err)
2964 return err;
2965
2966 if (class == BPF_ALU || class == BPF_ALU64) {
2967 err = check_alu_op(env, insn);
2968 if (err)
2969 return err;
2970
2971 } else if (class == BPF_LDX) {
2972 enum bpf_reg_type *prev_src_type, src_reg_type;
2973
2974 /* check for reserved fields is already done */
2975
2976 /* check src operand */
2977 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2978 if (err)
2979 return err;
2980
2981 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
2982 if (err)
2983 return err;
2984
2985 src_reg_type = regs[insn->src_reg].type;
2986
2987 /* check that memory (src_reg + off) is readable,
2988 * the state of dst_reg will be updated by this func
2989 */
2990 err = check_mem_access(env, insn->src_reg, insn->off,
2991 BPF_SIZE(insn->code), BPF_READ,
2992 insn->dst_reg);
2993 if (err)
2994 return err;
2995
2996 if (BPF_SIZE(insn->code) != BPF_W &&
2997 BPF_SIZE(insn->code) != BPF_DW) {
2998 insn_idx++;
2999 continue;
3000 }
3001
3002 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
3003
3004 if (*prev_src_type == NOT_INIT) {
3005 /* saw a valid insn
3006 * dst_reg = *(u32 *)(src_reg + off)
3007 * save type to validate intersecting paths
3008 */
3009 *prev_src_type = src_reg_type;
3010
3011 } else if (src_reg_type != *prev_src_type &&
3012 (src_reg_type == PTR_TO_CTX ||
3013 *prev_src_type == PTR_TO_CTX)) {
3014 /* ABuser program is trying to use the same insn
3015 * dst_reg = *(u32*) (src_reg + off)
3016 * with different pointer types:
3017 * src_reg == ctx in one branch and
3018 * src_reg == stack|map in some other branch.
3019 * Reject it.
3020 */
3021 verbose("same insn cannot be used with different pointers\n");
3022 return -EINVAL;
3023 }
3024
3025 } else if (class == BPF_STX) {
3026 enum bpf_reg_type *prev_dst_type, dst_reg_type;
3027
3028 if (BPF_MODE(insn->code) == BPF_XADD) {
3029 err = check_xadd(env, insn);
3030 if (err)
3031 return err;
3032 insn_idx++;
3033 continue;
3034 }
3035
3036 /* check src1 operand */
3037 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
3038 if (err)
3039 return err;
3040 /* check src2 operand */
3041 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
3042 if (err)
3043 return err;
3044
3045 dst_reg_type = regs[insn->dst_reg].type;
3046
3047 /* check that memory (dst_reg + off) is writeable */
3048 err = check_mem_access(env, insn->dst_reg, insn->off,
3049 BPF_SIZE(insn->code), BPF_WRITE,
3050 insn->src_reg);
3051 if (err)
3052 return err;
3053
3054 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
3055
3056 if (*prev_dst_type == NOT_INIT) {
3057 *prev_dst_type = dst_reg_type;
3058 } else if (dst_reg_type != *prev_dst_type &&
3059 (dst_reg_type == PTR_TO_CTX ||
3060 *prev_dst_type == PTR_TO_CTX)) {
3061 verbose("same insn cannot be used with different pointers\n");
3062 return -EINVAL;
3063 }
3064
3065 } else if (class == BPF_ST) {
3066 if (BPF_MODE(insn->code) != BPF_MEM ||
3067 insn->src_reg != BPF_REG_0) {
3068 verbose("BPF_ST uses reserved fields\n");
3069 return -EINVAL;
3070 }
3071 /* check src operand */
3072 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
3073 if (err)
3074 return err;
3075
3076 /* check that memory (dst_reg + off) is writeable */
3077 err = check_mem_access(env, insn->dst_reg, insn->off,
3078 BPF_SIZE(insn->code), BPF_WRITE,
3079 -1);
3080 if (err)
3081 return err;
3082
3083 } else if (class == BPF_JMP) {
3084 u8 opcode = BPF_OP(insn->code);
3085
3086 if (opcode == BPF_CALL) {
3087 if (BPF_SRC(insn->code) != BPF_K ||
3088 insn->off != 0 ||
3089 insn->src_reg != BPF_REG_0 ||
3090 insn->dst_reg != BPF_REG_0) {
3091 verbose("BPF_CALL uses reserved fields\n");
3092 return -EINVAL;
3093 }
3094
3095 err = check_call(env, insn->imm, insn_idx);
3096 if (err)
3097 return err;
3098
3099 } else if (opcode == BPF_JA) {
3100 if (BPF_SRC(insn->code) != BPF_K ||
3101 insn->imm != 0 ||
3102 insn->src_reg != BPF_REG_0 ||
3103 insn->dst_reg != BPF_REG_0) {
3104 verbose("BPF_JA uses reserved fields\n");
3105 return -EINVAL;
3106 }
3107
3108 insn_idx += insn->off + 1;
3109 continue;
3110
3111 } else if (opcode == BPF_EXIT) {
3112 if (BPF_SRC(insn->code) != BPF_K ||
3113 insn->imm != 0 ||
3114 insn->src_reg != BPF_REG_0 ||
3115 insn->dst_reg != BPF_REG_0) {
3116 verbose("BPF_EXIT uses reserved fields\n");
3117 return -EINVAL;
3118 }
3119
3120 /* eBPF calling convetion is such that R0 is used
3121 * to return the value from eBPF program.
3122 * Make sure that it's readable at this time
3123 * of bpf_exit, which means that program wrote
3124 * something into it earlier
3125 */
3126 err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
3127 if (err)
3128 return err;
3129
3130 if (is_pointer_value(env, BPF_REG_0)) {
3131 verbose("R0 leaks addr as return value\n");
3132 return -EACCES;
3133 }
3134
3135 process_bpf_exit:
3136 insn_idx = pop_stack(env, &prev_insn_idx);
3137 if (insn_idx < 0) {
3138 break;
3139 } else {
3140 do_print_state = true;
3141 continue;
3142 }
3143 } else {
3144 err = check_cond_jmp_op(env, insn, &insn_idx);
3145 if (err)
3146 return err;
3147 }
3148 } else if (class == BPF_LD) {
3149 u8 mode = BPF_MODE(insn->code);
3150
3151 if (mode == BPF_ABS || mode == BPF_IND) {
3152 err = check_ld_abs(env, insn);
3153 if (err)
3154 return err;
3155
3156 } else if (mode == BPF_IMM) {
3157 err = check_ld_imm(env, insn);
3158 if (err)
3159 return err;
3160
3161 insn_idx++;
3162 } else {
3163 verbose("invalid BPF_LD mode\n");
3164 return -EINVAL;
3165 }
3166 reset_reg_range_values(regs, insn->dst_reg);
3167 } else {
3168 verbose("unknown insn class %d\n", class);
3169 return -EINVAL;
3170 }
3171
3172 insn_idx++;
3173 }
3174
3175 verbose("processed %d insns\n", insn_processed);
3176 return 0;
3177 }
3178
3179 static int check_map_prealloc(struct bpf_map *map)
3180 {
3181 return (map->map_type != BPF_MAP_TYPE_HASH &&
3182 map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
3183 map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
3184 !(map->map_flags & BPF_F_NO_PREALLOC);
3185 }
3186
3187 static int check_map_prog_compatibility(struct bpf_map *map,
3188 struct bpf_prog *prog)
3189
3190 {
3191 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
3192 * preallocated hash maps, since doing memory allocation
3193 * in overflow_handler can crash depending on where nmi got
3194 * triggered.
3195 */
3196 if (prog->type == BPF_PROG_TYPE_PERF_EVENT) {
3197 if (!check_map_prealloc(map)) {
3198 verbose("perf_event programs can only use preallocated hash map\n");
3199 return -EINVAL;
3200 }
3201 if (map->inner_map_meta &&
3202 !check_map_prealloc(map->inner_map_meta)) {
3203 verbose("perf_event programs can only use preallocated inner hash map\n");
3204 return -EINVAL;
3205 }
3206 }
3207 return 0;
3208 }
3209
3210 /* look for pseudo eBPF instructions that access map FDs and
3211 * replace them with actual map pointers
3212 */
3213 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
3214 {
3215 struct bpf_insn *insn = env->prog->insnsi;
3216 int insn_cnt = env->prog->len;
3217 int i, j, err;
3218
3219 err = bpf_prog_calc_tag(env->prog);
3220 if (err)
3221 return err;
3222
3223 for (i = 0; i < insn_cnt; i++, insn++) {
3224 if (BPF_CLASS(insn->code) == BPF_LDX &&
3225 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
3226 verbose("BPF_LDX uses reserved fields\n");
3227 return -EINVAL;
3228 }
3229
3230 if (BPF_CLASS(insn->code) == BPF_STX &&
3231 ((BPF_MODE(insn->code) != BPF_MEM &&
3232 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
3233 verbose("BPF_STX uses reserved fields\n");
3234 return -EINVAL;
3235 }
3236
3237 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
3238 struct bpf_map *map;
3239 struct fd f;
3240
3241 if (i == insn_cnt - 1 || insn[1].code != 0 ||
3242 insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
3243 insn[1].off != 0) {
3244 verbose("invalid bpf_ld_imm64 insn\n");
3245 return -EINVAL;
3246 }
3247
3248 if (insn->src_reg == 0)
3249 /* valid generic load 64-bit imm */
3250 goto next_insn;
3251
3252 if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
3253 verbose("unrecognized bpf_ld_imm64 insn\n");
3254 return -EINVAL;
3255 }
3256
3257 f = fdget(insn->imm);
3258 map = __bpf_map_get(f);
3259 if (IS_ERR(map)) {
3260 verbose("fd %d is not pointing to valid bpf_map\n",
3261 insn->imm);
3262 return PTR_ERR(map);
3263 }
3264
3265 err = check_map_prog_compatibility(map, env->prog);
3266 if (err) {
3267 fdput(f);
3268 return err;
3269 }
3270
3271 /* store map pointer inside BPF_LD_IMM64 instruction */
3272 insn[0].imm = (u32) (unsigned long) map;
3273 insn[1].imm = ((u64) (unsigned long) map) >> 32;
3274
3275 /* check whether we recorded this map already */
3276 for (j = 0; j < env->used_map_cnt; j++)
3277 if (env->used_maps[j] == map) {
3278 fdput(f);
3279 goto next_insn;
3280 }
3281
3282 if (env->used_map_cnt >= MAX_USED_MAPS) {
3283 fdput(f);
3284 return -E2BIG;
3285 }
3286
3287 /* hold the map. If the program is rejected by verifier,
3288 * the map will be released by release_maps() or it
3289 * will be used by the valid program until it's unloaded
3290 * and all maps are released in free_bpf_prog_info()
3291 */
3292 map = bpf_map_inc(map, false);
3293 if (IS_ERR(map)) {
3294 fdput(f);
3295 return PTR_ERR(map);
3296 }
3297 env->used_maps[env->used_map_cnt++] = map;
3298
3299 fdput(f);
3300 next_insn:
3301 insn++;
3302 i++;
3303 }
3304 }
3305
3306 /* now all pseudo BPF_LD_IMM64 instructions load valid
3307 * 'struct bpf_map *' into a register instead of user map_fd.
3308 * These pointers will be used later by verifier to validate map access.
3309 */
3310 return 0;
3311 }
3312
3313 /* drop refcnt of maps used by the rejected program */
3314 static void release_maps(struct bpf_verifier_env *env)
3315 {
3316 int i;
3317
3318 for (i = 0; i < env->used_map_cnt; i++)
3319 bpf_map_put(env->used_maps[i]);
3320 }
3321
3322 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
3323 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
3324 {
3325 struct bpf_insn *insn = env->prog->insnsi;
3326 int insn_cnt = env->prog->len;
3327 int i;
3328
3329 for (i = 0; i < insn_cnt; i++, insn++)
3330 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
3331 insn->src_reg = 0;
3332 }
3333
3334 /* single env->prog->insni[off] instruction was replaced with the range
3335 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
3336 * [0, off) and [off, end) to new locations, so the patched range stays zero
3337 */
3338 static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
3339 u32 off, u32 cnt)
3340 {
3341 struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
3342
3343 if (cnt == 1)
3344 return 0;
3345 new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len);
3346 if (!new_data)
3347 return -ENOMEM;
3348 memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
3349 memcpy(new_data + off + cnt - 1, old_data + off,
3350 sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
3351 env->insn_aux_data = new_data;
3352 vfree(old_data);
3353 return 0;
3354 }
3355
3356 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
3357 const struct bpf_insn *patch, u32 len)
3358 {
3359 struct bpf_prog *new_prog;
3360
3361 new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
3362 if (!new_prog)
3363 return NULL;
3364 if (adjust_insn_aux_data(env, new_prog->len, off, len))
3365 return NULL;
3366 return new_prog;
3367 }
3368
3369 /* convert load instructions that access fields of 'struct __sk_buff'
3370 * into sequence of instructions that access fields of 'struct sk_buff'
3371 */
3372 static int convert_ctx_accesses(struct bpf_verifier_env *env)
3373 {
3374 const struct bpf_verifier_ops *ops = env->prog->aux->ops;
3375 const int insn_cnt = env->prog->len;
3376 struct bpf_insn insn_buf[16], *insn;
3377 struct bpf_prog *new_prog;
3378 enum bpf_access_type type;
3379 int i, cnt, delta = 0;
3380
3381 if (ops->gen_prologue) {
3382 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
3383 env->prog);
3384 if (cnt >= ARRAY_SIZE(insn_buf)) {
3385 verbose("bpf verifier is misconfigured\n");
3386 return -EINVAL;
3387 } else if (cnt) {
3388 new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
3389 if (!new_prog)
3390 return -ENOMEM;
3391
3392 env->prog = new_prog;
3393 delta += cnt - 1;
3394 }
3395 }
3396
3397 if (!ops->convert_ctx_access)
3398 return 0;
3399
3400 insn = env->prog->insnsi + delta;
3401
3402 for (i = 0; i < insn_cnt; i++, insn++) {
3403 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
3404 insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
3405 insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
3406 insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
3407 type = BPF_READ;
3408 else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
3409 insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
3410 insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
3411 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
3412 type = BPF_WRITE;
3413 else
3414 continue;
3415
3416 if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
3417 continue;
3418
3419 cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog);
3420 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
3421 verbose("bpf verifier is misconfigured\n");
3422 return -EINVAL;
3423 }
3424
3425 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
3426 if (!new_prog)
3427 return -ENOMEM;
3428
3429 delta += cnt - 1;
3430
3431 /* keep walking new program and skip insns we just inserted */
3432 env->prog = new_prog;
3433 insn = new_prog->insnsi + i + delta;
3434 }
3435
3436 return 0;
3437 }
3438
3439 /* fixup insn->imm field of bpf_call instructions
3440 * and inline eligible helpers as explicit sequence of BPF instructions
3441 *
3442 * this function is called after eBPF program passed verification
3443 */
3444 static int fixup_bpf_calls(struct bpf_verifier_env *env)
3445 {
3446 struct bpf_prog *prog = env->prog;
3447 struct bpf_insn *insn = prog->insnsi;
3448 const struct bpf_func_proto *fn;
3449 const int insn_cnt = prog->len;
3450 struct bpf_insn insn_buf[16];
3451 struct bpf_prog *new_prog;
3452 struct bpf_map *map_ptr;
3453 int i, cnt, delta = 0;
3454
3455 for (i = 0; i < insn_cnt; i++, insn++) {
3456 if (insn->code != (BPF_JMP | BPF_CALL))
3457 continue;
3458
3459 if (insn->imm == BPF_FUNC_get_route_realm)
3460 prog->dst_needed = 1;
3461 if (insn->imm == BPF_FUNC_get_prandom_u32)
3462 bpf_user_rnd_init_once();
3463 if (insn->imm == BPF_FUNC_tail_call) {
3464 /* If we tail call into other programs, we
3465 * cannot make any assumptions since they can
3466 * be replaced dynamically during runtime in
3467 * the program array.
3468 */
3469 prog->cb_access = 1;
3470
3471 /* mark bpf_tail_call as different opcode to avoid
3472 * conditional branch in the interpeter for every normal
3473 * call and to prevent accidental JITing by JIT compiler
3474 * that doesn't support bpf_tail_call yet
3475 */
3476 insn->imm = 0;
3477 insn->code |= BPF_X;
3478 continue;
3479 }
3480
3481 if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) {
3482 map_ptr = env->insn_aux_data[i + delta].map_ptr;
3483 if (map_ptr == BPF_MAP_PTR_POISON ||
3484 !map_ptr->ops->map_gen_lookup)
3485 goto patch_call_imm;
3486
3487 cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf);
3488 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
3489 verbose("bpf verifier is misconfigured\n");
3490 return -EINVAL;
3491 }
3492
3493 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
3494 cnt);
3495 if (!new_prog)
3496 return -ENOMEM;
3497
3498 delta += cnt - 1;
3499
3500 /* keep walking new program and skip insns we just inserted */
3501 env->prog = prog = new_prog;
3502 insn = new_prog->insnsi + i + delta;
3503 continue;
3504 }
3505
3506 patch_call_imm:
3507 fn = prog->aux->ops->get_func_proto(insn->imm);
3508 /* all functions that have prototype and verifier allowed
3509 * programs to call them, must be real in-kernel functions
3510 */
3511 if (!fn->func) {
3512 verbose("kernel subsystem misconfigured func %s#%d\n",
3513 func_id_name(insn->imm), insn->imm);
3514 return -EFAULT;
3515 }
3516 insn->imm = fn->func - __bpf_call_base;
3517 }
3518
3519 return 0;
3520 }
3521
3522 static void free_states(struct bpf_verifier_env *env)
3523 {
3524 struct bpf_verifier_state_list *sl, *sln;
3525 int i;
3526
3527 if (!env->explored_states)
3528 return;
3529
3530 for (i = 0; i < env->prog->len; i++) {
3531 sl = env->explored_states[i];
3532
3533 if (sl)
3534 while (sl != STATE_LIST_MARK) {
3535 sln = sl->next;
3536 kfree(sl);
3537 sl = sln;
3538 }
3539 }
3540
3541 kfree(env->explored_states);
3542 }
3543
3544 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
3545 {
3546 char __user *log_ubuf = NULL;
3547 struct bpf_verifier_env *env;
3548 int ret = -EINVAL;
3549
3550 /* 'struct bpf_verifier_env' can be global, but since it's not small,
3551 * allocate/free it every time bpf_check() is called
3552 */
3553 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3554 if (!env)
3555 return -ENOMEM;
3556
3557 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3558 (*prog)->len);
3559 ret = -ENOMEM;
3560 if (!env->insn_aux_data)
3561 goto err_free_env;
3562 env->prog = *prog;
3563
3564 /* grab the mutex to protect few globals used by verifier */
3565 mutex_lock(&bpf_verifier_lock);
3566
3567 if (attr->log_level || attr->log_buf || attr->log_size) {
3568 /* user requested verbose verifier output
3569 * and supplied buffer to store the verification trace
3570 */
3571 log_level = attr->log_level;
3572 log_ubuf = (char __user *) (unsigned long) attr->log_buf;
3573 log_size = attr->log_size;
3574 log_len = 0;
3575
3576 ret = -EINVAL;
3577 /* log_* values have to be sane */
3578 if (log_size < 128 || log_size > UINT_MAX >> 8 ||
3579 log_level == 0 || log_ubuf == NULL)
3580 goto err_unlock;
3581
3582 ret = -ENOMEM;
3583 log_buf = vmalloc(log_size);
3584 if (!log_buf)
3585 goto err_unlock;
3586 } else {
3587 log_level = 0;
3588 }
3589
3590 env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
3591 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
3592 env->strict_alignment = true;
3593
3594 ret = replace_map_fd_with_map_ptr(env);
3595 if (ret < 0)
3596 goto skip_full_check;
3597
3598 env->explored_states = kcalloc(env->prog->len,
3599 sizeof(struct bpf_verifier_state_list *),
3600 GFP_USER);
3601 ret = -ENOMEM;
3602 if (!env->explored_states)
3603 goto skip_full_check;
3604
3605 ret = check_cfg(env);
3606 if (ret < 0)
3607 goto skip_full_check;
3608
3609 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3610
3611 ret = do_check(env);
3612
3613 skip_full_check:
3614 while (pop_stack(env, NULL) >= 0);
3615 free_states(env);
3616
3617 if (ret == 0)
3618 /* program is valid, convert *(u32*)(ctx + off) accesses */
3619 ret = convert_ctx_accesses(env);
3620
3621 if (ret == 0)
3622 ret = fixup_bpf_calls(env);
3623
3624 if (log_level && log_len >= log_size - 1) {
3625 BUG_ON(log_len >= log_size);
3626 /* verifier log exceeded user supplied buffer */
3627 ret = -ENOSPC;
3628 /* fall through to return what was recorded */
3629 }
3630
3631 /* copy verifier log back to user space including trailing zero */
3632 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
3633 ret = -EFAULT;
3634 goto free_log_buf;
3635 }
3636
3637 if (ret == 0 && env->used_map_cnt) {
3638 /* if program passed verifier, update used_maps in bpf_prog_info */
3639 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
3640 sizeof(env->used_maps[0]),
3641 GFP_KERNEL);
3642
3643 if (!env->prog->aux->used_maps) {
3644 ret = -ENOMEM;
3645 goto free_log_buf;
3646 }
3647
3648 memcpy(env->prog->aux->used_maps, env->used_maps,
3649 sizeof(env->used_maps[0]) * env->used_map_cnt);
3650 env->prog->aux->used_map_cnt = env->used_map_cnt;
3651
3652 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3653 * bpf_ld_imm64 instructions
3654 */
3655 convert_pseudo_ld_imm64(env);
3656 }
3657
3658 free_log_buf:
3659 if (log_level)
3660 vfree(log_buf);
3661 if (!env->prog->aux->used_maps)
3662 /* if we didn't copy map pointers into bpf_prog_info, release
3663 * them now. Otherwise free_bpf_prog_info() will release them.
3664 */
3665 release_maps(env);
3666 *prog = env->prog;
3667 err_unlock:
3668 mutex_unlock(&bpf_verifier_lock);
3669 vfree(env->insn_aux_data);
3670 err_free_env:
3671 kfree(env);
3672 return ret;
3673 }
3674
3675 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
3676 void *priv)
3677 {
3678 struct bpf_verifier_env *env;
3679 int ret;
3680
3681 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3682 if (!env)
3683 return -ENOMEM;
3684
3685 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3686 prog->len);
3687 ret = -ENOMEM;
3688 if (!env->insn_aux_data)
3689 goto err_free_env;
3690 env->prog = prog;
3691 env->analyzer_ops = ops;
3692 env->analyzer_priv = priv;
3693
3694 /* grab the mutex to protect few globals used by verifier */
3695 mutex_lock(&bpf_verifier_lock);
3696
3697 log_level = 0;
3698
3699 env->strict_alignment = false;
3700 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
3701 env->strict_alignment = true;
3702
3703 env->explored_states = kcalloc(env->prog->len,
3704 sizeof(struct bpf_verifier_state_list *),
3705 GFP_KERNEL);
3706 ret = -ENOMEM;
3707 if (!env->explored_states)
3708 goto skip_full_check;
3709
3710 ret = check_cfg(env);
3711 if (ret < 0)
3712 goto skip_full_check;
3713
3714 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3715
3716 ret = do_check(env);
3717
3718 skip_full_check:
3719 while (pop_stack(env, NULL) >= 0);
3720 free_states(env);
3721
3722 mutex_unlock(&bpf_verifier_lock);
3723 vfree(env->insn_aux_data);
3724 err_free_env:
3725 kfree(env);
3726 return ret;
3727 }
3728 EXPORT_SYMBOL_GPL(bpf_analyzer);
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