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51580e79
AS		 1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 *
7 * This program is distributed in the hope that it will be useful, but
8 * WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
10 * General Public License for more details.
11 */
12#include <linux/kernel.h>
13#include <linux/types.h>
14#include <linux/slab.h>
15#include <linux/bpf.h>
16#include <linux/filter.h>
17#include <net/netlink.h>
18#include <linux/file.h>
19#include <linux/vmalloc.h>
20
21/* bpf_check() is a static code analyzer that walks eBPF program
22 * instruction by instruction and updates register/stack state.
23 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
24 *
25 * The first pass is depth-first-search to check that the program is a DAG.
26 * It rejects the following programs:
27 * - larger than BPF_MAXINSNS insns
28 * - if loop is present (detected via back-edge)
29 * - unreachable insns exist (shouldn't be a forest. program = one function)
30 * - out of bounds or malformed jumps
31 * The second pass is all possible path descent from the 1st insn.
32 * Since it's analyzing all pathes through the program, the length of the
33 * analysis is limited to 32k insn, which may be hit even if total number of
34 * insn is less then 4K, but there are too many branches that change stack/regs.
35 * Number of 'branches to be analyzed' is limited to 1k
36 *
37 * On entry to each instruction, each register has a type, and the instruction
38 * changes the types of the registers depending on instruction semantics.
39 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
40 * copied to R1.
41 *
42 * All registers are 64-bit.
43 * R0 - return register
44 * R1-R5 argument passing registers
45 * R6-R9 callee saved registers
46 * R10 - frame pointer read-only
47 *
48 * At the start of BPF program the register R1 contains a pointer to bpf_context
49 * and has type PTR_TO_CTX.
50 *
51 * Verifier tracks arithmetic operations on pointers in case:
52 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
53 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
54 * 1st insn copies R10 (which has FRAME_PTR) type into R1
55 * and 2nd arithmetic instruction is pattern matched to recognize
56 * that it wants to construct a pointer to some element within stack.
57 * So after 2nd insn, the register R1 has type PTR_TO_STACK
58 * (and -20 constant is saved for further stack bounds checking).
59 * Meaning that this reg is a pointer to stack plus known immediate constant.
60 *
61 * Most of the time the registers have UNKNOWN_VALUE type, which
62 * means the register has some value, but it's not a valid pointer.
63 * (like pointer plus pointer becomes UNKNOWN_VALUE type)
64 *
65 * When verifier sees load or store instructions the type of base register
66 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
67 * types recognized by check_mem_access() function.
68 *
69 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
70 * and the range of [ptr, ptr + map's value_size) is accessible.
71 *
72 * registers used to pass values to function calls are checked against
73 * function argument constraints.
74 *
75 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
76 * It means that the register type passed to this function must be
77 * PTR_TO_STACK and it will be used inside the function as
78 * 'pointer to map element key'
79 *
80 * For example the argument constraints for bpf_map_lookup_elem():
81 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
82 * .arg1_type = ARG_CONST_MAP_PTR,
83 * .arg2_type = ARG_PTR_TO_MAP_KEY,
84 *
85 * ret_type says that this function returns 'pointer to map elem value or null'
86 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
87 * 2nd argument should be a pointer to stack, which will be used inside
88 * the helper function as a pointer to map element key.
89 *
90 * On the kernel side the helper function looks like:
91 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
92 * {
93 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
94 * void *key = (void *) (unsigned long) r2;
95 * void *value;
96 *
97 * here kernel can access 'key' and 'map' pointers safely, knowing that
98 * [key, key + map->key_size) bytes are valid and were initialized on
99 * the stack of eBPF program.
100 * }
101 *
102 * Corresponding eBPF program may look like:
103 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
104 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
105 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
106 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
107 * here verifier looks at prototype of map_lookup_elem() and sees:
108 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
109 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
110 *
111 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
112 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
113 * and were initialized prior to this call.
114 * If it's ok, then verifier allows this BPF_CALL insn and looks at
115 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
116 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
117 * returns ether pointer to map value or NULL.
118 *
119 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
120 * insn, the register holding that pointer in the true branch changes state to
121 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
122 * branch. See check_cond_jmp_op().
123 *
124 * After the call R0 is set to return type of the function and registers R1-R5
125 * are set to NOT_INIT to indicate that they are no longer readable.
126 */
127
17a52670
AS		 128/* types of values stored in eBPF registers */
129enum bpf_reg_type {
130 NOT_INIT = 0, /* nothing was written into register */
131 UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */
132 PTR_TO_CTX, /* reg points to bpf_context */
133 CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
134 PTR_TO_MAP_VALUE, /* reg points to map element value */
135 PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
136 FRAME_PTR, /* reg == frame_pointer */
137 PTR_TO_STACK, /* reg == frame_pointer + imm */
138 CONST_IMM, /* constant integer value */
139};
140
141struct reg_state {
142 enum bpf_reg_type type;
143 union {
144 /* valid when type == CONST_IMM | PTR_TO_STACK */
145 int imm;
146
147 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
148 * PTR_TO_MAP_VALUE_OR_NULL
149 */
150 struct bpf_map *map_ptr;
151 };
152};
153
154enum bpf_stack_slot_type {
155 STACK_INVALID, /* nothing was stored in this stack slot */
9c399760 156 STACK_SPILL, /* register spilled into stack */
17a52670
AS		 157 STACK_MISC /* BPF program wrote some data into this slot */
158};
159
9c399760 160#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */
17a52670
AS		 161
162/* state of the program:
163 * type of all registers and stack info
164 */
165struct verifier_state {
166 struct reg_state regs[MAX_BPF_REG];
9c399760
AS		 167 u8 stack_slot_type[MAX_BPF_STACK];
168 struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];
17a52670
AS		 169};
170
171/* linked list of verifier states used to prune search */
172struct verifier_state_list {
173 struct verifier_state state;
174 struct verifier_state_list *next;
175};
176
177/* verifier_state + insn_idx are pushed to stack when branch is encountered */
178struct verifier_stack_elem {
179 /* verifer state is 'st'
180 * before processing instruction 'insn_idx'
181 * and after processing instruction 'prev_insn_idx'
182 */
183 struct verifier_state st;
184 int insn_idx;
185 int prev_insn_idx;
186 struct verifier_stack_elem *next;
187};
188
0246e64d
AS		 189#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
190
cbd35700
AS		 191/* single container for all structs
192 * one verifier_env per bpf_check() call
193 */
194struct verifier_env {
0246e64d 195 struct bpf_prog *prog; /* eBPF program being verified */
17a52670
AS		 196 struct verifier_stack_elem *head; /* stack of verifier states to be processed */
197 int stack_size; /* number of states to be processed */
198 struct verifier_state cur_state; /* current verifier state */
f1bca824 199 struct verifier_state_list **explored_states; /* search pruning optimization */
0246e64d
AS		 200 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
201 u32 used_map_cnt; /* number of used maps */
cbd35700
AS		 202};
203
204/* verbose verifier prints what it's seeing
205 * bpf_check() is called under lock, so no race to access these global vars
206 */
207static u32 log_level, log_size, log_len;
208static char *log_buf;
209
210static DEFINE_MUTEX(bpf_verifier_lock);
211
212/* log_level controls verbosity level of eBPF verifier.
213 * verbose() is used to dump the verification trace to the log, so the user
214 * can figure out what's wrong with the program
215 */
216static void verbose(const char *fmt, ...)
217{
218 va_list args;
219
220 if (log_level == 0 || log_len >= log_size - 1)
221 return;
222
223 va_start(args, fmt);
224 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
225 va_end(args);
226}
227
17a52670
AS		 228/* string representation of 'enum bpf_reg_type' */
229static const char * const reg_type_str[] = {
230 [NOT_INIT] = "?",
231 [UNKNOWN_VALUE] = "inv",
232 [PTR_TO_CTX] = "ctx",
233 [CONST_PTR_TO_MAP] = "map_ptr",
234 [PTR_TO_MAP_VALUE] = "map_value",
235 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
236 [FRAME_PTR] = "fp",
237 [PTR_TO_STACK] = "fp",
238 [CONST_IMM] = "imm",
239};
240
241static void print_verifier_state(struct verifier_env *env)
242{
243 enum bpf_reg_type t;
244 int i;
245
246 for (i = 0; i < MAX_BPF_REG; i++) {
247 t = env->cur_state.regs[i].type;
248 if (t == NOT_INIT)
249 continue;
250 verbose(" R%d=%s", i, reg_type_str[t]);
251 if (t == CONST_IMM || t == PTR_TO_STACK)
252 verbose("%d", env->cur_state.regs[i].imm);
253 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
254 t == PTR_TO_MAP_VALUE_OR_NULL)
255 verbose("(ks=%d,vs=%d)",
256 env->cur_state.regs[i].map_ptr->key_size,
257 env->cur_state.regs[i].map_ptr->value_size);
258 }
9c399760
AS		 259 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
260 if (env->cur_state.stack_slot_type[i] == STACK_SPILL)
17a52670 261 verbose(" fp%d=%s", -MAX_BPF_STACK + i,
9c399760 262 reg_type_str[env->cur_state.spilled_regs[i / BPF_REG_SIZE].type]);
17a52670
AS		 263 }
264 verbose("\n");
265}
266
cbd35700
AS		 267static const char *const bpf_class_string[] = {
268 [BPF_LD] = "ld",
269 [BPF_LDX] = "ldx",
270 [BPF_ST] = "st",
271 [BPF_STX] = "stx",
272 [BPF_ALU] = "alu",
273 [BPF_JMP] = "jmp",
274 [BPF_RET] = "BUG",
275 [BPF_ALU64] = "alu64",
276};
277
278static const char *const bpf_alu_string[] = {
279 [BPF_ADD >> 4] = "+=",
280 [BPF_SUB >> 4] = "-=",
281 [BPF_MUL >> 4] = "*=",
282 [BPF_DIV >> 4] = "/=",
283 [BPF_OR >> 4] = "|=",
284 [BPF_AND >> 4] = "&=",
285 [BPF_LSH >> 4] = "<<=",
286 [BPF_RSH >> 4] = ">>=",
287 [BPF_NEG >> 4] = "neg",
288 [BPF_MOD >> 4] = "%=",
289 [BPF_XOR >> 4] = "^=",
290 [BPF_MOV >> 4] = "=",
291 [BPF_ARSH >> 4] = "s>>=",
292 [BPF_END >> 4] = "endian",
293};
294
295static const char *const bpf_ldst_string[] = {
296 [BPF_W >> 3] = "u32",
297 [BPF_H >> 3] = "u16",
298 [BPF_B >> 3] = "u8",
299 [BPF_DW >> 3] = "u64",
300};
301
302static const char *const bpf_jmp_string[] = {
303 [BPF_JA >> 4] = "jmp",
304 [BPF_JEQ >> 4] = "==",
305 [BPF_JGT >> 4] = ">",
306 [BPF_JGE >> 4] = ">=",
307 [BPF_JSET >> 4] = "&",
308 [BPF_JNE >> 4] = "!=",
309 [BPF_JSGT >> 4] = "s>",
310 [BPF_JSGE >> 4] = "s>=",
311 [BPF_CALL >> 4] = "call",
312 [BPF_EXIT >> 4] = "exit",
313};
314
315static void print_bpf_insn(struct bpf_insn *insn)
316{
317 u8 class = BPF_CLASS(insn->code);
318
319 if (class == BPF_ALU || class == BPF_ALU64) {
320 if (BPF_SRC(insn->code) == BPF_X)
321 verbose("(%02x) %sr%d %s %sr%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->src_reg);
327 else
328 verbose("(%02x) %sr%d %s %s%d\n",
329 insn->code, class == BPF_ALU ? "(u32) " : "",
330 insn->dst_reg,
331 bpf_alu_string[BPF_OP(insn->code) >> 4],
332 class == BPF_ALU ? "(u32) " : "",
333 insn->imm);
334 } else if (class == BPF_STX) {
335 if (BPF_MODE(insn->code) == BPF_MEM)
336 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
337 insn->code,
338 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
339 insn->dst_reg,
340 insn->off, insn->src_reg);
341 else if (BPF_MODE(insn->code) == BPF_XADD)
342 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
343 insn->code,
344 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
345 insn->dst_reg, insn->off,
346 insn->src_reg);
347 else
348 verbose("BUG_%02x\n", insn->code);
349 } else if (class == BPF_ST) {
350 if (BPF_MODE(insn->code) != BPF_MEM) {
351 verbose("BUG_st_%02x\n", insn->code);
352 return;
353 }
354 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
355 insn->code,
356 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
357 insn->dst_reg,
358 insn->off, insn->imm);
359 } else if (class == BPF_LDX) {
360 if (BPF_MODE(insn->code) != BPF_MEM) {
361 verbose("BUG_ldx_%02x\n", insn->code);
362 return;
363 }
364 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
365 insn->code, insn->dst_reg,
366 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
367 insn->src_reg, insn->off);
368 } else if (class == BPF_LD) {
369 if (BPF_MODE(insn->code) == BPF_ABS) {
370 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
371 insn->code,
372 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
373 insn->imm);
374 } else if (BPF_MODE(insn->code) == BPF_IND) {
375 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
376 insn->code,
377 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
378 insn->src_reg, insn->imm);
379 } else if (BPF_MODE(insn->code) == BPF_IMM) {
380 verbose("(%02x) r%d = 0x%x\n",
381 insn->code, insn->dst_reg, insn->imm);
382 } else {
383 verbose("BUG_ld_%02x\n", insn->code);
384 return;
385 }
386 } else if (class == BPF_JMP) {
387 u8 opcode = BPF_OP(insn->code);
388
389 if (opcode == BPF_CALL) {
390 verbose("(%02x) call %d\n", insn->code, insn->imm);
391 } else if (insn->code == (BPF_JMP | BPF_JA)) {
392 verbose("(%02x) goto pc%+d\n",
393 insn->code, insn->off);
394 } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
395 verbose("(%02x) exit\n", insn->code);
396 } else if (BPF_SRC(insn->code) == BPF_X) {
397 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
398 insn->code, insn->dst_reg,
399 bpf_jmp_string[BPF_OP(insn->code) >> 4],
400 insn->src_reg, insn->off);
401 } else {
402 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
403 insn->code, insn->dst_reg,
404 bpf_jmp_string[BPF_OP(insn->code) >> 4],
405 insn->imm, insn->off);
406 }
407 } else {
408 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
409 }
410}
411
17a52670
AS		 412static int pop_stack(struct verifier_env *env, int *prev_insn_idx)
413{
414 struct verifier_stack_elem *elem;
415 int insn_idx;
416
417 if (env->head == NULL)
418 return -1;
419
420 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
421 insn_idx = env->head->insn_idx;
422 if (prev_insn_idx)
423 *prev_insn_idx = env->head->prev_insn_idx;
424 elem = env->head->next;
425 kfree(env->head);
426 env->head = elem;
427 env->stack_size--;
428 return insn_idx;
429}
430
431static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx,
432 int prev_insn_idx)
433{
434 struct verifier_stack_elem *elem;
435
436 elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL);
437 if (!elem)
438 goto err;
439
440 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
441 elem->insn_idx = insn_idx;
442 elem->prev_insn_idx = prev_insn_idx;
443 elem->next = env->head;
444 env->head = elem;
445 env->stack_size++;
446 if (env->stack_size > 1024) {
447 verbose("BPF program is too complex\n");
448 goto err;
449 }
450 return &elem->st;
451err:
452 /* pop all elements and return */
453 while (pop_stack(env, NULL) >= 0);
454 return NULL;
455}
456
457#define CALLER_SAVED_REGS 6
458static const int caller_saved[CALLER_SAVED_REGS] = {
459 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
460};
461
462static void init_reg_state(struct reg_state *regs)
463{
464 int i;
465
466 for (i = 0; i < MAX_BPF_REG; i++) {
467 regs[i].type = NOT_INIT;
468 regs[i].imm = 0;
469 regs[i].map_ptr = NULL;
470 }
471
472 /* frame pointer */
473 regs[BPF_REG_FP].type = FRAME_PTR;
474
475 /* 1st arg to a function */
476 regs[BPF_REG_1].type = PTR_TO_CTX;
477}
478
479static void mark_reg_unknown_value(struct reg_state *regs, u32 regno)
480{
481 BUG_ON(regno >= MAX_BPF_REG);
482 regs[regno].type = UNKNOWN_VALUE;
483 regs[regno].imm = 0;
484 regs[regno].map_ptr = NULL;
485}
486
487enum reg_arg_type {
488 SRC_OP, /* register is used as source operand */
489 DST_OP, /* register is used as destination operand */
490 DST_OP_NO_MARK /* same as above, check only, don't mark */
491};
492
493static int check_reg_arg(struct reg_state *regs, u32 regno,
494 enum reg_arg_type t)
495{
496 if (regno >= MAX_BPF_REG) {
497 verbose("R%d is invalid\n", regno);
498 return -EINVAL;
499 }
500
501 if (t == SRC_OP) {
502 /* check whether register used as source operand can be read */
503 if (regs[regno].type == NOT_INIT) {
504 verbose("R%d !read_ok\n", regno);
505 return -EACCES;
506 }
507 } else {
508 /* check whether register used as dest operand can be written to */
509 if (regno == BPF_REG_FP) {
510 verbose("frame pointer is read only\n");
511 return -EACCES;
512 }
513 if (t == DST_OP)
514 mark_reg_unknown_value(regs, regno);
515 }
516 return 0;
517}
518
519static int bpf_size_to_bytes(int bpf_size)
520{
521 if (bpf_size == BPF_W)
522 return 4;
523 else if (bpf_size == BPF_H)
524 return 2;
525 else if (bpf_size == BPF_B)
526 return 1;
527 else if (bpf_size == BPF_DW)
528 return 8;
529 else
530 return -EINVAL;
531}
532
533/* check_stack_read/write functions track spill/fill of registers,
534 * stack boundary and alignment are checked in check_mem_access()
535 */
536static int check_stack_write(struct verifier_state *state, int off, int size,
537 int value_regno)
538{
17a52670 539 int i;
9c399760
AS		 540 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
541 * so it's aligned access and [off, off + size) are within stack limits
542 */
17a52670
AS		 543
544 if (value_regno >= 0 &&
545 (state->regs[value_regno].type == PTR_TO_MAP_VALUE ||
546 state->regs[value_regno].type == PTR_TO_STACK ||
547 state->regs[value_regno].type == PTR_TO_CTX)) {
548
549 /* register containing pointer is being spilled into stack */
9c399760 550 if (size != BPF_REG_SIZE) {
17a52670
AS		 551 verbose("invalid size of register spill\n");
552 return -EACCES;
553 }
554
17a52670 555 /* save register state */
9c399760
AS		 556 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
557 state->regs[value_regno];
17a52670 558
9c399760
AS		 559 for (i = 0; i < BPF_REG_SIZE; i++)
560 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
561 } else {
17a52670 562 /* regular write of data into stack */
9c399760
AS		 563 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
564 (struct reg_state) {};
565
566 for (i = 0; i < size; i++)
567 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
17a52670
AS		 568 }
569 return 0;
570}
571
572static int check_stack_read(struct verifier_state *state, int off, int size,
573 int value_regno)
574{
9c399760 575 u8 *slot_type;
17a52670 576 int i;
17a52670 577
9c399760 578 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
17a52670 579
9c399760
AS		 580 if (slot_type[0] == STACK_SPILL) {
581 if (size != BPF_REG_SIZE) {
17a52670
AS		 582 verbose("invalid size of register spill\n");
583 return -EACCES;
584 }
9c399760
AS		 585 for (i = 1; i < BPF_REG_SIZE; i++) {
586 if (slot_type[i] != STACK_SPILL) {
17a52670
AS		 587 verbose("corrupted spill memory\n");
588 return -EACCES;
589 }
590 }
591
592 if (value_regno >= 0)
593 /* restore register state from stack */
9c399760
AS		 594 state->regs[value_regno] =
595 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
17a52670
AS		 596 return 0;
597 } else {
598 for (i = 0; i < size; i++) {
9c399760 599 if (slot_type[i] != STACK_MISC) {
17a52670
AS		 600 verbose("invalid read from stack off %d+%d size %d\n",
601 off, i, size);
602 return -EACCES;
603 }
604 }
605 if (value_regno >= 0)
606 /* have read misc data from the stack */
607 mark_reg_unknown_value(state->regs, value_regno);
608 return 0;
609 }
610}
611
612/* check read/write into map element returned by bpf_map_lookup_elem() */
613static int check_map_access(struct verifier_env *env, u32 regno, int off,
614 int size)
615{
616 struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
617
618 if (off < 0 || off + size > map->value_size) {
619 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
620 map->value_size, off, size);
621 return -EACCES;
622 }
623 return 0;
624}
625
626/* check access to 'struct bpf_context' fields */
627static int check_ctx_access(struct verifier_env *env, int off, int size,
628 enum bpf_access_type t)
629{
630 if (env->prog->aux->ops->is_valid_access &&
631 env->prog->aux->ops->is_valid_access(off, size, t))
632 return 0;
633
634 verbose("invalid bpf_context access off=%d size=%d\n", off, size);
635 return -EACCES;
636}
637
638/* check whether memory at (regno + off) is accessible for t = (read | write)
639 * if t==write, value_regno is a register which value is stored into memory
640 * if t==read, value_regno is a register which will receive the value from memory
641 * if t==write && value_regno==-1, some unknown value is stored into memory
642 * if t==read && value_regno==-1, don't care what we read from memory
643 */
644static int check_mem_access(struct verifier_env *env, u32 regno, int off,
645 int bpf_size, enum bpf_access_type t,
646 int value_regno)
647{
648 struct verifier_state *state = &env->cur_state;
649 int size, err = 0;
650
651 size = bpf_size_to_bytes(bpf_size);
652 if (size < 0)
653 return size;
654
655 if (off % size != 0) {
656 verbose("misaligned access off %d size %d\n", off, size);
657 return -EACCES;
658 }
659
660 if (state->regs[regno].type == PTR_TO_MAP_VALUE) {
661 err = check_map_access(env, regno, off, size);
662 if (!err && t == BPF_READ && value_regno >= 0)
663 mark_reg_unknown_value(state->regs, value_regno);
664
665 } else if (state->regs[regno].type == PTR_TO_CTX) {
666 err = check_ctx_access(env, off, size, t);
667 if (!err && t == BPF_READ && value_regno >= 0)
668 mark_reg_unknown_value(state->regs, value_regno);
669
670 } else if (state->regs[regno].type == FRAME_PTR) {
671 if (off >= 0 || off < -MAX_BPF_STACK) {
672 verbose("invalid stack off=%d size=%d\n", off, size);
673 return -EACCES;
674 }
675 if (t == BPF_WRITE)
676 err = check_stack_write(state, off, size, value_regno);
677 else
678 err = check_stack_read(state, off, size, value_regno);
679 } else {
680 verbose("R%d invalid mem access '%s'\n",
681 regno, reg_type_str[state->regs[regno].type]);
682 return -EACCES;
683 }
684 return err;
685}
686
687static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
688{
689 struct reg_state *regs = env->cur_state.regs;
690 int err;
691
692 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
693 insn->imm != 0) {
694 verbose("BPF_XADD uses reserved fields\n");
695 return -EINVAL;
696 }
697
698 /* check src1 operand */
699 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
700 if (err)
701 return err;
702
703 /* check src2 operand */
704 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
705 if (err)
706 return err;
707
708 /* check whether atomic_add can read the memory */
709 err = check_mem_access(env, insn->dst_reg, insn->off,
710 BPF_SIZE(insn->code), BPF_READ, -1);
711 if (err)
712 return err;
713
714 /* check whether atomic_add can write into the same memory */
715 return check_mem_access(env, insn->dst_reg, insn->off,
716 BPF_SIZE(insn->code), BPF_WRITE, -1);
717}
718
719/* when register 'regno' is passed into function that will read 'access_size'
720 * bytes from that pointer, make sure that it's within stack boundary
721 * and all elements of stack are initialized
722 */
723static int check_stack_boundary(struct verifier_env *env,
724 int regno, int access_size)
725{
726 struct verifier_state *state = &env->cur_state;
727 struct reg_state *regs = state->regs;
728 int off, i;
729
730 if (regs[regno].type != PTR_TO_STACK)
731 return -EACCES;
732
733 off = regs[regno].imm;
734 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
735 access_size <= 0) {
736 verbose("invalid stack type R%d off=%d access_size=%d\n",
737 regno, off, access_size);
738 return -EACCES;
739 }
740
741 for (i = 0; i < access_size; i++) {
9c399760 742 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
17a52670
AS		 743 verbose("invalid indirect read from stack off %d+%d size %d\n",
744 off, i, access_size);
745 return -EACCES;
746 }
747 }
748 return 0;
749}
750
751static int check_func_arg(struct verifier_env *env, u32 regno,
752 enum bpf_arg_type arg_type, struct bpf_map **mapp)
753{
754 struct reg_state *reg = env->cur_state.regs + regno;
755 enum bpf_reg_type expected_type;
756 int err = 0;
757
758 if (arg_type == ARG_ANYTHING)
759 return 0;
760
761 if (reg->type == NOT_INIT) {
762 verbose("R%d !read_ok\n", regno);
763 return -EACCES;
764 }
765
766 if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
767 arg_type == ARG_PTR_TO_MAP_VALUE) {
768 expected_type = PTR_TO_STACK;
769 } else if (arg_type == ARG_CONST_STACK_SIZE) {
770 expected_type = CONST_IMM;
771 } else if (arg_type == ARG_CONST_MAP_PTR) {
772 expected_type = CONST_PTR_TO_MAP;
773 } else {
774 verbose("unsupported arg_type %d\n", arg_type);
775 return -EFAULT;
776 }
777
778 if (reg->type != expected_type) {
779 verbose("R%d type=%s expected=%s\n", regno,
780 reg_type_str[reg->type], reg_type_str[expected_type]);
781 return -EACCES;
782 }
783
784 if (arg_type == ARG_CONST_MAP_PTR) {
785 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
786 *mapp = reg->map_ptr;
787
788 } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
789 /* bpf_map_xxx(..., map_ptr, ..., key) call:
790 * check that [key, key + map->key_size) are within
791 * stack limits and initialized
792 */
793 if (!*mapp) {
794 /* in function declaration map_ptr must come before
795 * map_key, so that it's verified and known before
796 * we have to check map_key here. Otherwise it means
797 * that kernel subsystem misconfigured verifier
798 */
799 verbose("invalid map_ptr to access map->key\n");
800 return -EACCES;
801 }
802 err = check_stack_boundary(env, regno, (*mapp)->key_size);
803
804 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
805 /* bpf_map_xxx(..., map_ptr, ..., value) call:
806 * check [value, value + map->value_size) validity
807 */
808 if (!*mapp) {
809 /* kernel subsystem misconfigured verifier */
810 verbose("invalid map_ptr to access map->value\n");
811 return -EACCES;
812 }
813 err = check_stack_boundary(env, regno, (*mapp)->value_size);
814
815 } else if (arg_type == ARG_CONST_STACK_SIZE) {
816 /* bpf_xxx(..., buf, len) call will access 'len' bytes
817 * from stack pointer 'buf'. Check it
818 * note: regno == len, regno - 1 == buf
819 */
820 if (regno == 0) {
821 /* kernel subsystem misconfigured verifier */
822 verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
823 return -EACCES;
824 }
825 err = check_stack_boundary(env, regno - 1, reg->imm);
826 }
827
828 return err;
829}
830
831static int check_call(struct verifier_env *env, int func_id)
832{
833 struct verifier_state *state = &env->cur_state;
834 const struct bpf_func_proto *fn = NULL;
835 struct reg_state *regs = state->regs;
836 struct bpf_map *map = NULL;
837 struct reg_state *reg;
838 int i, err;
839
840 /* find function prototype */
841 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
842 verbose("invalid func %d\n", func_id);
843 return -EINVAL;
844 }
845
846 if (env->prog->aux->ops->get_func_proto)
847 fn = env->prog->aux->ops->get_func_proto(func_id);
848
849 if (!fn) {
850 verbose("unknown func %d\n", func_id);
851 return -EINVAL;
852 }
853
854 /* eBPF programs must be GPL compatible to use GPL-ed functions */
855 if (!env->prog->aux->is_gpl_compatible && fn->gpl_only) {
856 verbose("cannot call GPL only function from proprietary program\n");
857 return -EINVAL;
858 }
859
860 /* check args */
861 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &map);
862 if (err)
863 return err;
864 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &map);
865 if (err)
866 return err;
867 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &map);
868 if (err)
869 return err;
870 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &map);
871 if (err)
872 return err;
873 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &map);
874 if (err)
875 return err;
876
877 /* reset caller saved regs */
878 for (i = 0; i < CALLER_SAVED_REGS; i++) {
879 reg = regs + caller_saved[i];
880 reg->type = NOT_INIT;
881 reg->imm = 0;
882 }
883
884 /* update return register */
885 if (fn->ret_type == RET_INTEGER) {
886 regs[BPF_REG_0].type = UNKNOWN_VALUE;
887 } else if (fn->ret_type == RET_VOID) {
888 regs[BPF_REG_0].type = NOT_INIT;
889 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
890 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
891 /* remember map_ptr, so that check_map_access()
892 * can check 'value_size' boundary of memory access
893 * to map element returned from bpf_map_lookup_elem()
894 */
895 if (map == NULL) {
896 verbose("kernel subsystem misconfigured verifier\n");
897 return -EINVAL;
898 }
899 regs[BPF_REG_0].map_ptr = map;
900 } else {
901 verbose("unknown return type %d of func %d\n",
902 fn->ret_type, func_id);
903 return -EINVAL;
904 }
905 return 0;
906}
907
908/* check validity of 32-bit and 64-bit arithmetic operations */
909static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn)
910{
911 u8 opcode = BPF_OP(insn->code);
912 int err;
913
914 if (opcode == BPF_END || opcode == BPF_NEG) {
915 if (opcode == BPF_NEG) {
916 if (BPF_SRC(insn->code) != 0 ||
917 insn->src_reg != BPF_REG_0 ||
918 insn->off != 0 || insn->imm != 0) {
919 verbose("BPF_NEG uses reserved fields\n");
920 return -EINVAL;
921 }
922 } else {
923 if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
924 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
925 verbose("BPF_END uses reserved fields\n");
926 return -EINVAL;
927 }
928 }
929
930 /* check src operand */
931 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
932 if (err)
933 return err;
934
935 /* check dest operand */
936 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
937 if (err)
938 return err;
939
940 } else if (opcode == BPF_MOV) {
941
942 if (BPF_SRC(insn->code) == BPF_X) {
943 if (insn->imm != 0 || insn->off != 0) {
944 verbose("BPF_MOV uses reserved fields\n");
945 return -EINVAL;
946 }
947
948 /* check src operand */
949 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
950 if (err)
951 return err;
952 } else {
953 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
954 verbose("BPF_MOV uses reserved fields\n");
955 return -EINVAL;
956 }
957 }
958
959 /* check dest operand */
960 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
961 if (err)
962 return err;
963
964 if (BPF_SRC(insn->code) == BPF_X) {
965 if (BPF_CLASS(insn->code) == BPF_ALU64) {
966 /* case: R1 = R2
967 * copy register state to dest reg
968 */
969 regs[insn->dst_reg] = regs[insn->src_reg];
970 } else {
971 regs[insn->dst_reg].type = UNKNOWN_VALUE;
972 regs[insn->dst_reg].map_ptr = NULL;
973 }
974 } else {
975 /* case: R = imm
976 * remember the value we stored into this reg
977 */
978 regs[insn->dst_reg].type = CONST_IMM;
979 regs[insn->dst_reg].imm = insn->imm;
980 }
981
982 } else if (opcode > BPF_END) {
983 verbose("invalid BPF_ALU opcode %x\n", opcode);
984 return -EINVAL;
985
986 } else { /* all other ALU ops: and, sub, xor, add, ... */
987
988 bool stack_relative = false;
989
990 if (BPF_SRC(insn->code) == BPF_X) {
991 if (insn->imm != 0 || insn->off != 0) {
992 verbose("BPF_ALU uses reserved fields\n");
993 return -EINVAL;
994 }
995 /* check src1 operand */
996 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
997 if (err)
998 return err;
999 } else {
1000 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1001 verbose("BPF_ALU uses reserved fields\n");
1002 return -EINVAL;
1003 }
1004 }
1005
1006 /* check src2 operand */
1007 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1008 if (err)
1009 return err;
1010
1011 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
1012 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
1013 verbose("div by zero\n");
1014 return -EINVAL;
1015 }
1016
1017 /* pattern match 'bpf_add Rx, imm' instruction */
1018 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
1019 regs[insn->dst_reg].type == FRAME_PTR &&
1020 BPF_SRC(insn->code) == BPF_K)
1021 stack_relative = true;
1022
1023 /* check dest operand */
1024 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1025 if (err)
1026 return err;
1027
1028 if (stack_relative) {
1029 regs[insn->dst_reg].type = PTR_TO_STACK;
1030 regs[insn->dst_reg].imm = insn->imm;
1031 }
1032 }
1033
1034 return 0;
1035}
1036
1037static int check_cond_jmp_op(struct verifier_env *env,
1038 struct bpf_insn *insn, int *insn_idx)
1039{
1040 struct reg_state *regs = env->cur_state.regs;
1041 struct verifier_state *other_branch;
1042 u8 opcode = BPF_OP(insn->code);
1043 int err;
1044
1045 if (opcode > BPF_EXIT) {
1046 verbose("invalid BPF_JMP opcode %x\n", opcode);
1047 return -EINVAL;
1048 }
1049
1050 if (BPF_SRC(insn->code) == BPF_X) {
1051 if (insn->imm != 0) {
1052 verbose("BPF_JMP uses reserved fields\n");
1053 return -EINVAL;
1054 }
1055
1056 /* check src1 operand */
1057 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1058 if (err)
1059 return err;
1060 } else {
1061 if (insn->src_reg != BPF_REG_0) {
1062 verbose("BPF_JMP uses reserved fields\n");
1063 return -EINVAL;
1064 }
1065 }
1066
1067 /* check src2 operand */
1068 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1069 if (err)
1070 return err;
1071
1072 /* detect if R == 0 where R was initialized to zero earlier */
1073 if (BPF_SRC(insn->code) == BPF_K &&
1074 (opcode == BPF_JEQ || opcode == BPF_JNE) &&
1075 regs[insn->dst_reg].type == CONST_IMM &&
1076 regs[insn->dst_reg].imm == insn->imm) {
1077 if (opcode == BPF_JEQ) {
1078 /* if (imm == imm) goto pc+off;
1079 * only follow the goto, ignore fall-through
1080 */
1081 *insn_idx += insn->off;
1082 return 0;
1083 } else {
1084 /* if (imm != imm) goto pc+off;
1085 * only follow fall-through branch, since
1086 * that's where the program will go
1087 */
1088 return 0;
1089 }
1090 }
1091
1092 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
1093 if (!other_branch)
1094 return -EFAULT;
1095
1096 /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */
1097 if (BPF_SRC(insn->code) == BPF_K &&
1098 insn->imm == 0 && (opcode == BPF_JEQ ||
1099 opcode == BPF_JNE) &&
1100 regs[insn->dst_reg].type == PTR_TO_MAP_VALUE_OR_NULL) {
1101 if (opcode == BPF_JEQ) {
1102 /* next fallthrough insn can access memory via
1103 * this register
1104 */
1105 regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
1106 /* branch targer cannot access it, since reg == 0 */
1107 other_branch->regs[insn->dst_reg].type = CONST_IMM;
1108 other_branch->regs[insn->dst_reg].imm = 0;
1109 } else {
1110 other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
1111 regs[insn->dst_reg].type = CONST_IMM;
1112 regs[insn->dst_reg].imm = 0;
1113 }
1114 } else if (BPF_SRC(insn->code) == BPF_K &&
1115 (opcode == BPF_JEQ || opcode == BPF_JNE)) {
1116
1117 if (opcode == BPF_JEQ) {
1118 /* detect if (R == imm) goto
1119 * and in the target state recognize that R = imm
1120 */
1121 other_branch->regs[insn->dst_reg].type = CONST_IMM;
1122 other_branch->regs[insn->dst_reg].imm = insn->imm;
1123 } else {
1124 /* detect if (R != imm) goto
1125 * and in the fall-through state recognize that R = imm
1126 */
1127 regs[insn->dst_reg].type = CONST_IMM;
1128 regs[insn->dst_reg].imm = insn->imm;
1129 }
1130 }
1131 if (log_level)
1132 print_verifier_state(env);
1133 return 0;
1134}
1135
0246e64d
AS		 1136/* return the map pointer stored inside BPF_LD_IMM64 instruction */
1137static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
1138{
1139 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
1140
1141 return (struct bpf_map *) (unsigned long) imm64;
1142}
1143
17a52670
AS		 1144/* verify BPF_LD_IMM64 instruction */
1145static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn)
1146{
1147 struct reg_state *regs = env->cur_state.regs;
1148 int err;
1149
1150 if (BPF_SIZE(insn->code) != BPF_DW) {
1151 verbose("invalid BPF_LD_IMM insn\n");
1152 return -EINVAL;
1153 }
1154 if (insn->off != 0) {
1155 verbose("BPF_LD_IMM64 uses reserved fields\n");
1156 return -EINVAL;
1157 }
1158
1159 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1160 if (err)
1161 return err;
1162
1163 if (insn->src_reg == 0)
1164 /* generic move 64-bit immediate into a register */
1165 return 0;
1166
1167 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
1168 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
1169
1170 regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
1171 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
1172 return 0;
1173}
1174
ddd872bc
AS		 1175/* verify safety of LD_ABS|LD_IND instructions:
1176 * - they can only appear in the programs where ctx == skb
1177 * - since they are wrappers of function calls, they scratch R1-R5 registers,
1178 * preserve R6-R9, and store return value into R0
1179 *
1180 * Implicit input:
1181 * ctx == skb == R6 == CTX
1182 *
1183 * Explicit input:
1184 * SRC == any register
1185 * IMM == 32-bit immediate
1186 *
1187 * Output:
1188 * R0 - 8/16/32-bit skb data converted to cpu endianness
1189 */
1190static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn)
1191{
1192 struct reg_state *regs = env->cur_state.regs;
1193 u8 mode = BPF_MODE(insn->code);
1194 struct reg_state *reg;
1195 int i, err;
1196
1197 if (env->prog->aux->prog_type != BPF_PROG_TYPE_SOCKET_FILTER) {
1198 verbose("BPF_LD_ABS|IND instructions are only allowed in socket filters\n");
1199 return -EINVAL;
1200 }
1201
1202 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
1203 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
1204 verbose("BPF_LD_ABS uses reserved fields\n");
1205 return -EINVAL;
1206 }
1207
1208 /* check whether implicit source operand (register R6) is readable */
1209 err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
1210 if (err)
1211 return err;
1212
1213 if (regs[BPF_REG_6].type != PTR_TO_CTX) {
1214 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
1215 return -EINVAL;
1216 }
1217
1218 if (mode == BPF_IND) {
1219 /* check explicit source operand */
1220 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1221 if (err)
1222 return err;
1223 }
1224
1225 /* reset caller saved regs to unreadable */
1226 for (i = 0; i < CALLER_SAVED_REGS; i++) {
1227 reg = regs + caller_saved[i];
1228 reg->type = NOT_INIT;
1229 reg->imm = 0;
1230 }
1231
1232 /* mark destination R0 register as readable, since it contains
1233 * the value fetched from the packet
1234 */
1235 regs[BPF_REG_0].type = UNKNOWN_VALUE;
1236 return 0;
1237}
1238
475fb78f
AS		 1239/* non-recursive DFS pseudo code
1240 * 1 procedure DFS-iterative(G,v):
1241 * 2 label v as discovered
1242 * 3 let S be a stack
1243 * 4 S.push(v)
1244 * 5 while S is not empty
1245 * 6 t <- S.pop()
1246 * 7 if t is what we're looking for:
1247 * 8 return t
1248 * 9 for all edges e in G.adjacentEdges(t) do
1249 * 10 if edge e is already labelled
1250 * 11 continue with the next edge
1251 * 12 w <- G.adjacentVertex(t,e)
1252 * 13 if vertex w is not discovered and not explored
1253 * 14 label e as tree-edge
1254 * 15 label w as discovered
1255 * 16 S.push(w)
1256 * 17 continue at 5
1257 * 18 else if vertex w is discovered
1258 * 19 label e as back-edge
1259 * 20 else
1260 * 21 // vertex w is explored
1261 * 22 label e as forward- or cross-edge
1262 * 23 label t as explored
1263 * 24 S.pop()
1264 *
1265 * convention:
1266 * 0x10 - discovered
1267 * 0x11 - discovered and fall-through edge labelled
1268 * 0x12 - discovered and fall-through and branch edges labelled
1269 * 0x20 - explored
1270 */
1271
1272enum {
1273 DISCOVERED = 0x10,
1274 EXPLORED = 0x20,
1275 FALLTHROUGH = 1,
1276 BRANCH = 2,
1277};
1278
f1bca824
AS		 1279#define STATE_LIST_MARK ((struct verifier_state_list *) -1L)
1280
475fb78f
AS		 1281static int *insn_stack; /* stack of insns to process */
1282static int cur_stack; /* current stack index */
1283static int *insn_state;
1284
1285/* t, w, e - match pseudo-code above:
1286 * t - index of current instruction
1287 * w - next instruction
1288 * e - edge
1289 */
1290static int push_insn(int t, int w, int e, struct verifier_env *env)
1291{
1292 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
1293 return 0;
1294
1295 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
1296 return 0;
1297
1298 if (w < 0 || w >= env->prog->len) {
1299 verbose("jump out of range from insn %d to %d\n", t, w);
1300 return -EINVAL;
1301 }
1302
f1bca824
AS		 1303 if (e == BRANCH)
1304 /* mark branch target for state pruning */
1305 env->explored_states[w] = STATE_LIST_MARK;
1306
475fb78f
AS		 1307 if (insn_state[w] == 0) {
1308 /* tree-edge */
1309 insn_state[t] = DISCOVERED | e;
1310 insn_state[w] = DISCOVERED;
1311 if (cur_stack >= env->prog->len)
1312 return -E2BIG;
1313 insn_stack[cur_stack++] = w;
1314 return 1;
1315 } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
1316 verbose("back-edge from insn %d to %d\n", t, w);
1317 return -EINVAL;
1318 } else if (insn_state[w] == EXPLORED) {
1319 /* forward- or cross-edge */
1320 insn_state[t] = DISCOVERED | e;
1321 } else {
1322 verbose("insn state internal bug\n");
1323 return -EFAULT;
1324 }
1325 return 0;
1326}
1327
1328/* non-recursive depth-first-search to detect loops in BPF program
1329 * loop == back-edge in directed graph
1330 */
1331static int check_cfg(struct verifier_env *env)
1332{
1333 struct bpf_insn *insns = env->prog->insnsi;
1334 int insn_cnt = env->prog->len;
1335 int ret = 0;
1336 int i, t;
1337
1338 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
1339 if (!insn_state)
1340 return -ENOMEM;
1341
1342 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
1343 if (!insn_stack) {
1344 kfree(insn_state);
1345 return -ENOMEM;
1346 }
1347
1348 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
1349 insn_stack[0] = 0; /* 0 is the first instruction */
1350 cur_stack = 1;
1351
1352peek_stack:
1353 if (cur_stack == 0)
1354 goto check_state;
1355 t = insn_stack[cur_stack - 1];
1356
1357 if (BPF_CLASS(insns[t].code) == BPF_JMP) {
1358 u8 opcode = BPF_OP(insns[t].code);
1359
1360 if (opcode == BPF_EXIT) {
1361 goto mark_explored;
1362 } else if (opcode == BPF_CALL) {
1363 ret = push_insn(t, t + 1, FALLTHROUGH, env);
1364 if (ret == 1)
1365 goto peek_stack;
1366 else if (ret < 0)
1367 goto err_free;
1368 } else if (opcode == BPF_JA) {
1369 if (BPF_SRC(insns[t].code) != BPF_K) {
1370 ret = -EINVAL;
1371 goto err_free;
1372 }
1373 /* unconditional jump with single edge */
1374 ret = push_insn(t, t + insns[t].off + 1,
1375 FALLTHROUGH, env);
1376 if (ret == 1)
1377 goto peek_stack;
1378 else if (ret < 0)
1379 goto err_free;
f1bca824
AS		 1380 /* tell verifier to check for equivalent states
1381 * after every call and jump
1382 */
1383 env->explored_states[t + 1] = STATE_LIST_MARK;
475fb78f
AS		 1384 } else {
1385 /* conditional jump with two edges */
1386 ret = push_insn(t, t + 1, FALLTHROUGH, env);
1387 if (ret == 1)
1388 goto peek_stack;
1389 else if (ret < 0)
1390 goto err_free;
1391
1392 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
1393 if (ret == 1)
1394 goto peek_stack;
1395 else if (ret < 0)
1396 goto err_free;
1397 }
1398 } else {
1399 /* all other non-branch instructions with single
1400 * fall-through edge
1401 */
1402 ret = push_insn(t, t + 1, FALLTHROUGH, env);
1403 if (ret == 1)
1404 goto peek_stack;
1405 else if (ret < 0)
1406 goto err_free;
1407 }
1408
1409mark_explored:
1410 insn_state[t] = EXPLORED;
1411 if (cur_stack-- <= 0) {
1412 verbose("pop stack internal bug\n");
1413 ret = -EFAULT;
1414 goto err_free;
1415 }
1416 goto peek_stack;
1417
1418check_state:
1419 for (i = 0; i < insn_cnt; i++) {
1420 if (insn_state[i] != EXPLORED) {
1421 verbose("unreachable insn %d\n", i);
1422 ret = -EINVAL;
1423 goto err_free;
1424 }
1425 }
1426 ret = 0; /* cfg looks good */
1427
1428err_free:
1429 kfree(insn_state);
1430 kfree(insn_stack);
1431 return ret;
1432}
1433
f1bca824
AS		 1434/* compare two verifier states
1435 *
1436 * all states stored in state_list are known to be valid, since
1437 * verifier reached 'bpf_exit' instruction through them
1438 *
1439 * this function is called when verifier exploring different branches of
1440 * execution popped from the state stack. If it sees an old state that has
1441 * more strict register state and more strict stack state then this execution
1442 * branch doesn't need to be explored further, since verifier already
1443 * concluded that more strict state leads to valid finish.
1444 *
1445 * Therefore two states are equivalent if register state is more conservative
1446 * and explored stack state is more conservative than the current one.
1447 * Example:
1448 * explored current
1449 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
1450 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
1451 *
1452 * In other words if current stack state (one being explored) has more
1453 * valid slots than old one that already passed validation, it means
1454 * the verifier can stop exploring and conclude that current state is valid too
1455 *
1456 * Similarly with registers. If explored state has register type as invalid
1457 * whereas register type in current state is meaningful, it means that
1458 * the current state will reach 'bpf_exit' instruction safely
1459 */
1460static bool states_equal(struct verifier_state *old, struct verifier_state *cur)
1461{
1462 int i;
1463
1464 for (i = 0; i < MAX_BPF_REG; i++) {
1465 if (memcmp(&old->regs[i], &cur->regs[i],
1466 sizeof(old->regs[0])) != 0) {
1467 if (old->regs[i].type == NOT_INIT ||
32bf08a6
AS		 1468 (old->regs[i].type == UNKNOWN_VALUE &&
1469 cur->regs[i].type != NOT_INIT))
f1bca824
AS		 1470 continue;
1471 return false;
1472 }
1473 }
1474
1475 for (i = 0; i < MAX_BPF_STACK; i++) {
9c399760
AS		 1476 if (old->stack_slot_type[i] == STACK_INVALID)
1477 continue;
1478 if (old->stack_slot_type[i] != cur->stack_slot_type[i])
1479 /* Ex: old explored (safe) state has STACK_SPILL in
1480 * this stack slot, but current has has STACK_MISC ->
1481 * this verifier states are not equivalent,
1482 * return false to continue verification of this path
1483 */
f1bca824 1484 return false;
9c399760
AS		 1485 if (i % BPF_REG_SIZE)
1486 continue;
1487 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
1488 &cur->spilled_regs[i / BPF_REG_SIZE],
1489 sizeof(old->spilled_regs[0])))
1490 /* when explored and current stack slot types are
1491 * the same, check that stored pointers types
1492 * are the same as well.
1493 * Ex: explored safe path could have stored
1494 * (struct reg_state) {.type = PTR_TO_STACK, .imm = -8}
1495 * but current path has stored:
1496 * (struct reg_state) {.type = PTR_TO_STACK, .imm = -16}
1497 * such verifier states are not equivalent.
1498 * return false to continue verification of this path
1499 */
1500 return false;
1501 else
1502 continue;
f1bca824
AS		 1503 }
1504 return true;
1505}
1506
1507static int is_state_visited(struct verifier_env *env, int insn_idx)
1508{
1509 struct verifier_state_list *new_sl;
1510 struct verifier_state_list *sl;
1511
1512 sl = env->explored_states[insn_idx];
1513 if (!sl)
1514 /* this 'insn_idx' instruction wasn't marked, so we will not
1515 * be doing state search here
1516 */
1517 return 0;
1518
1519 while (sl != STATE_LIST_MARK) {
1520 if (states_equal(&sl->state, &env->cur_state))
1521 /* reached equivalent register/stack state,
1522 * prune the search
1523 */
1524 return 1;
1525 sl = sl->next;
1526 }
1527
1528 /* there were no equivalent states, remember current one.
1529 * technically the current state is not proven to be safe yet,
1530 * but it will either reach bpf_exit (which means it's safe) or
1531 * it will be rejected. Since there are no loops, we won't be
1532 * seeing this 'insn_idx' instruction again on the way to bpf_exit
1533 */
1534 new_sl = kmalloc(sizeof(struct verifier_state_list), GFP_USER);
1535 if (!new_sl)
1536 return -ENOMEM;
1537
1538 /* add new state to the head of linked list */
1539 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
1540 new_sl->next = env->explored_states[insn_idx];
1541 env->explored_states[insn_idx] = new_sl;
1542 return 0;
1543}
1544
17a52670
AS		 1545static int do_check(struct verifier_env *env)
1546{
1547 struct verifier_state *state = &env->cur_state;
1548 struct bpf_insn *insns = env->prog->insnsi;
1549 struct reg_state *regs = state->regs;
1550 int insn_cnt = env->prog->len;
1551 int insn_idx, prev_insn_idx = 0;
1552 int insn_processed = 0;
1553 bool do_print_state = false;
1554
1555 init_reg_state(regs);
1556 insn_idx = 0;
1557 for (;;) {
1558 struct bpf_insn *insn;
1559 u8 class;
1560 int err;
1561
1562 if (insn_idx >= insn_cnt) {
1563 verbose("invalid insn idx %d insn_cnt %d\n",
1564 insn_idx, insn_cnt);
1565 return -EFAULT;
1566 }
1567
1568 insn = &insns[insn_idx];
1569 class = BPF_CLASS(insn->code);
1570
1571 if (++insn_processed > 32768) {
1572 verbose("BPF program is too large. Proccessed %d insn\n",
1573 insn_processed);
1574 return -E2BIG;
1575 }
1576
f1bca824
AS		 1577 err = is_state_visited(env, insn_idx);
1578 if (err < 0)
1579 return err;
1580 if (err == 1) {
1581 /* found equivalent state, can prune the search */
1582 if (log_level) {
1583 if (do_print_state)
1584 verbose("\nfrom %d to %d: safe\n",
1585 prev_insn_idx, insn_idx);
1586 else
1587 verbose("%d: safe\n", insn_idx);
1588 }
1589 goto process_bpf_exit;
1590 }
1591
17a52670
AS		 1592 if (log_level && do_print_state) {
1593 verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
1594 print_verifier_state(env);
1595 do_print_state = false;
1596 }
1597
1598 if (log_level) {
1599 verbose("%d: ", insn_idx);
1600 print_bpf_insn(insn);
1601 }
1602
1603 if (class == BPF_ALU || class == BPF_ALU64) {
1604 err = check_alu_op(regs, insn);
1605 if (err)
1606 return err;
1607
1608 } else if (class == BPF_LDX) {
1609 if (BPF_MODE(insn->code) != BPF_MEM ||
1610 insn->imm != 0) {
1611 verbose("BPF_LDX uses reserved fields\n");
1612 return -EINVAL;
1613 }
1614 /* check src operand */
1615 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1616 if (err)
1617 return err;
1618
1619 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
1620 if (err)
1621 return err;
1622
1623 /* check that memory (src_reg + off) is readable,
1624 * the state of dst_reg will be updated by this func
1625 */
1626 err = check_mem_access(env, insn->src_reg, insn->off,
1627 BPF_SIZE(insn->code), BPF_READ,
1628 insn->dst_reg);
1629 if (err)
1630 return err;
1631
1632 } else if (class == BPF_STX) {
1633 if (BPF_MODE(insn->code) == BPF_XADD) {
1634 err = check_xadd(env, insn);
1635 if (err)
1636 return err;
1637 insn_idx++;
1638 continue;
1639 }
1640
1641 if (BPF_MODE(insn->code) != BPF_MEM ||
1642 insn->imm != 0) {
1643 verbose("BPF_STX uses reserved fields\n");
1644 return -EINVAL;
1645 }
1646 /* check src1 operand */
1647 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1648 if (err)
1649 return err;
1650 /* check src2 operand */
1651 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1652 if (err)
1653 return err;
1654
1655 /* check that memory (dst_reg + off) is writeable */
1656 err = check_mem_access(env, insn->dst_reg, insn->off,
1657 BPF_SIZE(insn->code), BPF_WRITE,
1658 insn->src_reg);
1659 if (err)
1660 return err;
1661
1662 } else if (class == BPF_ST) {
1663 if (BPF_MODE(insn->code) != BPF_MEM ||
1664 insn->src_reg != BPF_REG_0) {
1665 verbose("BPF_ST uses reserved fields\n");
1666 return -EINVAL;
1667 }
1668 /* check src operand */
1669 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1670 if (err)
1671 return err;
1672
1673 /* check that memory (dst_reg + off) is writeable */
1674 err = check_mem_access(env, insn->dst_reg, insn->off,
1675 BPF_SIZE(insn->code), BPF_WRITE,
1676 -1);
1677 if (err)
1678 return err;
1679
1680 } else if (class == BPF_JMP) {
1681 u8 opcode = BPF_OP(insn->code);
1682
1683 if (opcode == BPF_CALL) {
1684 if (BPF_SRC(insn->code) != BPF_K ||
1685 insn->off != 0 ||
1686 insn->src_reg != BPF_REG_0 ||
1687 insn->dst_reg != BPF_REG_0) {
1688 verbose("BPF_CALL uses reserved fields\n");
1689 return -EINVAL;
1690 }
1691
1692 err = check_call(env, insn->imm);
1693 if (err)
1694 return err;
1695
1696 } else if (opcode == BPF_JA) {
1697 if (BPF_SRC(insn->code) != BPF_K ||
1698 insn->imm != 0 ||
1699 insn->src_reg != BPF_REG_0 ||
1700 insn->dst_reg != BPF_REG_0) {
1701 verbose("BPF_JA uses reserved fields\n");
1702 return -EINVAL;
1703 }
1704
1705 insn_idx += insn->off + 1;
1706 continue;
1707
1708 } else if (opcode == BPF_EXIT) {
1709 if (BPF_SRC(insn->code) != BPF_K ||
1710 insn->imm != 0 ||
1711 insn->src_reg != BPF_REG_0 ||
1712 insn->dst_reg != BPF_REG_0) {
1713 verbose("BPF_EXIT uses reserved fields\n");
1714 return -EINVAL;
1715 }
1716
1717 /* eBPF calling convetion is such that R0 is used
1718 * to return the value from eBPF program.
1719 * Make sure that it's readable at this time
1720 * of bpf_exit, which means that program wrote
1721 * something into it earlier
1722 */
1723 err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
1724 if (err)
1725 return err;
1726
f1bca824 1727process_bpf_exit:
17a52670
AS		 1728 insn_idx = pop_stack(env, &prev_insn_idx);
1729 if (insn_idx < 0) {
1730 break;
1731 } else {
1732 do_print_state = true;
1733 continue;
1734 }
1735 } else {
1736 err = check_cond_jmp_op(env, insn, &insn_idx);
1737 if (err)
1738 return err;
1739 }
1740 } else if (class == BPF_LD) {
1741 u8 mode = BPF_MODE(insn->code);
1742
1743 if (mode == BPF_ABS || mode == BPF_IND) {
ddd872bc
AS		 1744 err = check_ld_abs(env, insn);
1745 if (err)
1746 return err;
1747
17a52670
AS		 1748 } else if (mode == BPF_IMM) {
1749 err = check_ld_imm(env, insn);
1750 if (err)
1751 return err;
1752
1753 insn_idx++;
1754 } else {
1755 verbose("invalid BPF_LD mode\n");
1756 return -EINVAL;
1757 }
1758 } else {
1759 verbose("unknown insn class %d\n", class);
1760 return -EINVAL;
1761 }
1762
1763 insn_idx++;
1764 }
1765
1766 return 0;
1767}
1768
0246e64d
AS		 1769/* look for pseudo eBPF instructions that access map FDs and
1770 * replace them with actual map pointers
1771 */
1772static int replace_map_fd_with_map_ptr(struct verifier_env *env)
1773{
1774 struct bpf_insn *insn = env->prog->insnsi;
1775 int insn_cnt = env->prog->len;
1776 int i, j;
1777
1778 for (i = 0; i < insn_cnt; i++, insn++) {
1779 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
1780 struct bpf_map *map;
1781 struct fd f;
1782
1783 if (i == insn_cnt - 1 || insn[1].code != 0 ||
1784 insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
1785 insn[1].off != 0) {
1786 verbose("invalid bpf_ld_imm64 insn\n");
1787 return -EINVAL;
1788 }
1789
1790 if (insn->src_reg == 0)
1791 /* valid generic load 64-bit imm */
1792 goto next_insn;
1793
1794 if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
1795 verbose("unrecognized bpf_ld_imm64 insn\n");
1796 return -EINVAL;
1797 }
1798
1799 f = fdget(insn->imm);
1800
1801 map = bpf_map_get(f);
1802 if (IS_ERR(map)) {
1803 verbose("fd %d is not pointing to valid bpf_map\n",
1804 insn->imm);
1805 fdput(f);
1806 return PTR_ERR(map);
1807 }
1808
1809 /* store map pointer inside BPF_LD_IMM64 instruction */
1810 insn[0].imm = (u32) (unsigned long) map;
1811 insn[1].imm = ((u64) (unsigned long) map) >> 32;
1812
1813 /* check whether we recorded this map already */
1814 for (j = 0; j < env->used_map_cnt; j++)
1815 if (env->used_maps[j] == map) {
1816 fdput(f);
1817 goto next_insn;
1818 }
1819
1820 if (env->used_map_cnt >= MAX_USED_MAPS) {
1821 fdput(f);
1822 return -E2BIG;
1823 }
1824
1825 /* remember this map */
1826 env->used_maps[env->used_map_cnt++] = map;
1827
1828 /* hold the map. If the program is rejected by verifier,
1829 * the map will be released by release_maps() or it
1830 * will be used by the valid program until it's unloaded
1831 * and all maps are released in free_bpf_prog_info()
1832 */
1833 atomic_inc(&map->refcnt);
1834
1835 fdput(f);
1836next_insn:
1837 insn++;
1838 i++;
1839 }
1840 }
1841
1842 /* now all pseudo BPF_LD_IMM64 instructions load valid
1843 * 'struct bpf_map *' into a register instead of user map_fd.
1844 * These pointers will be used later by verifier to validate map access.
1845 */
1846 return 0;
1847}
1848
1849/* drop refcnt of maps used by the rejected program */
1850static void release_maps(struct verifier_env *env)
1851{
1852 int i;
1853
1854 for (i = 0; i < env->used_map_cnt; i++)
1855 bpf_map_put(env->used_maps[i]);
1856}
1857
1858/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
1859static void convert_pseudo_ld_imm64(struct verifier_env *env)
1860{
1861 struct bpf_insn *insn = env->prog->insnsi;
1862 int insn_cnt = env->prog->len;
1863 int i;
1864
1865 for (i = 0; i < insn_cnt; i++, insn++)
1866 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
1867 insn->src_reg = 0;
1868}
1869
f1bca824
AS		 1870static void free_states(struct verifier_env *env)
1871{
1872 struct verifier_state_list *sl, *sln;
1873 int i;
1874
1875 if (!env->explored_states)
1876 return;
1877
1878 for (i = 0; i < env->prog->len; i++) {
1879 sl = env->explored_states[i];
1880
1881 if (sl)
1882 while (sl != STATE_LIST_MARK) {
1883 sln = sl->next;
1884 kfree(sl);
1885 sl = sln;
1886 }
1887 }
1888
1889 kfree(env->explored_states);
1890}
1891
51580e79
AS		 1892int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
1893{
cbd35700
AS		 1894 char __user *log_ubuf = NULL;
1895 struct verifier_env *env;
51580e79
AS		 1896 int ret = -EINVAL;
1897
cbd35700
AS		 1898 if (prog->len <= 0 || prog->len > BPF_MAXINSNS)
1899 return -E2BIG;
1900
1901 /* 'struct verifier_env' can be global, but since it's not small,
1902 * allocate/free it every time bpf_check() is called
1903 */
1904 env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL);
1905 if (!env)
1906 return -ENOMEM;
1907
0246e64d
AS		 1908 env->prog = prog;
1909
cbd35700
AS		 1910 /* grab the mutex to protect few globals used by verifier */
1911 mutex_lock(&bpf_verifier_lock);
1912
1913 if (attr->log_level || attr->log_buf || attr->log_size) {
1914 /* user requested verbose verifier output
1915 * and supplied buffer to store the verification trace
1916 */
1917 log_level = attr->log_level;
1918 log_ubuf = (char __user *) (unsigned long) attr->log_buf;
1919 log_size = attr->log_size;
1920 log_len = 0;
1921
1922 ret = -EINVAL;
1923 /* log_* values have to be sane */
1924 if (log_size < 128 || log_size > UINT_MAX >> 8 ||
1925 log_level == 0 || log_ubuf == NULL)
1926 goto free_env;
1927
1928 ret = -ENOMEM;
1929 log_buf = vmalloc(log_size);
1930 if (!log_buf)
1931 goto free_env;
1932 } else {
1933 log_level = 0;
1934 }
1935
0246e64d
AS		 1936 ret = replace_map_fd_with_map_ptr(env);
1937 if (ret < 0)
1938 goto skip_full_check;
1939
f1bca824
AS		 1940 env->explored_states = kcalloc(prog->len,
1941 sizeof(struct verifier_state_list *),
1942 GFP_USER);
1943 ret = -ENOMEM;
1944 if (!env->explored_states)
1945 goto skip_full_check;
1946
475fb78f
AS		 1947 ret = check_cfg(env);
1948 if (ret < 0)
1949 goto skip_full_check;
1950
17a52670 1951 ret = do_check(env);
cbd35700 1952
0246e64d 1953skip_full_check:
17a52670 1954 while (pop_stack(env, NULL) >= 0);
f1bca824 1955 free_states(env);
0246e64d 1956
cbd35700
AS		 1957 if (log_level && log_len >= log_size - 1) {
1958 BUG_ON(log_len >= log_size);
1959 /* verifier log exceeded user supplied buffer */
1960 ret = -ENOSPC;
1961 /* fall through to return what was recorded */
1962 }
1963
1964 /* copy verifier log back to user space including trailing zero */
1965 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
1966 ret = -EFAULT;
1967 goto free_log_buf;
1968 }
1969
0246e64d
AS		 1970 if (ret == 0 && env->used_map_cnt) {
1971 /* if program passed verifier, update used_maps in bpf_prog_info */
1972 prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
1973 sizeof(env->used_maps[0]),
1974 GFP_KERNEL);
1975
1976 if (!prog->aux->used_maps) {
1977 ret = -ENOMEM;
1978 goto free_log_buf;
1979 }
1980
1981 memcpy(prog->aux->used_maps, env->used_maps,
1982 sizeof(env->used_maps[0]) * env->used_map_cnt);
1983 prog->aux->used_map_cnt = env->used_map_cnt;
1984
1985 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
1986 * bpf_ld_imm64 instructions
1987 */
1988 convert_pseudo_ld_imm64(env);
1989 }
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AS		 1990
1991free_log_buf:
1992 if (log_level)
1993 vfree(log_buf);
1994free_env:
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AS		 1995 if (!prog->aux->used_maps)
1996 /* if we didn't copy map pointers into bpf_prog_info, release
1997 * them now. Otherwise free_bpf_prog_info() will release them.
1998 */
1999 release_maps(env);
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AS		 2000 kfree(env);
2001 mutex_unlock(&bpf_verifier_lock);
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AS		 2002 return ret;
2003}
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