blob: 99a7e5b388f236ea62f23afefac5c252416d2b60 [file] [log] [blame]
Alexei Starovoitov51580e72014-09-26 00:17:02 -07001/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
Alexei Starovoitov969bf052016-05-05 19:49:10 -07002 * Copyright (c) 2016 Facebook
Alexei Starovoitov51580e72014-09-26 00:17:02 -07003 *
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>
Jakub Kicinski58e2af82016-09-21 11:43:57 +010017#include <linux/bpf_verifier.h>
Alexei Starovoitov51580e72014-09-26 00:17:02 -070018#include <linux/filter.h>
19#include <net/netlink.h>
20#include <linux/file.h>
21#include <linux/vmalloc.h>
22
23/* bpf_check() is a static code analyzer that walks eBPF program
24 * instruction by instruction and updates register/stack state.
25 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
26 *
27 * The first pass is depth-first-search to check that the program is a DAG.
28 * It rejects the following programs:
29 * - larger than BPF_MAXINSNS insns
30 * - if loop is present (detected via back-edge)
31 * - unreachable insns exist (shouldn't be a forest. program = one function)
32 * - out of bounds or malformed jumps
33 * The second pass is all possible path descent from the 1st insn.
34 * Since it's analyzing all pathes through the program, the length of the
35 * analysis is limited to 32k insn, which may be hit even if total number of
36 * insn is less then 4K, but there are too many branches that change stack/regs.
37 * Number of 'branches to be analyzed' is limited to 1k
38 *
39 * On entry to each instruction, each register has a type, and the instruction
40 * changes the types of the registers depending on instruction semantics.
41 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
42 * copied to R1.
43 *
44 * All registers are 64-bit.
45 * R0 - return register
46 * R1-R5 argument passing registers
47 * R6-R9 callee saved registers
48 * R10 - frame pointer read-only
49 *
50 * At the start of BPF program the register R1 contains a pointer to bpf_context
51 * and has type PTR_TO_CTX.
52 *
53 * Verifier tracks arithmetic operations on pointers in case:
54 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
55 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
56 * 1st insn copies R10 (which has FRAME_PTR) type into R1
57 * and 2nd arithmetic instruction is pattern matched to recognize
58 * that it wants to construct a pointer to some element within stack.
59 * So after 2nd insn, the register R1 has type PTR_TO_STACK
60 * (and -20 constant is saved for further stack bounds checking).
61 * Meaning that this reg is a pointer to stack plus known immediate constant.
62 *
63 * Most of the time the registers have UNKNOWN_VALUE type, which
64 * means the register has some value, but it's not a valid pointer.
65 * (like pointer plus pointer becomes UNKNOWN_VALUE type)
66 *
67 * When verifier sees load or store instructions the type of base register
68 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
69 * types recognized by check_mem_access() function.
70 *
71 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
72 * and the range of [ptr, ptr + map's value_size) is accessible.
73 *
74 * registers used to pass values to function calls are checked against
75 * function argument constraints.
76 *
77 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
78 * It means that the register type passed to this function must be
79 * PTR_TO_STACK and it will be used inside the function as
80 * 'pointer to map element key'
81 *
82 * For example the argument constraints for bpf_map_lookup_elem():
83 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
84 * .arg1_type = ARG_CONST_MAP_PTR,
85 * .arg2_type = ARG_PTR_TO_MAP_KEY,
86 *
87 * ret_type says that this function returns 'pointer to map elem value or null'
88 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
89 * 2nd argument should be a pointer to stack, which will be used inside
90 * the helper function as a pointer to map element key.
91 *
92 * On the kernel side the helper function looks like:
93 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
94 * {
95 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
96 * void *key = (void *) (unsigned long) r2;
97 * void *value;
98 *
99 * here kernel can access 'key' and 'map' pointers safely, knowing that
100 * [key, key + map->key_size) bytes are valid and were initialized on
101 * the stack of eBPF program.
102 * }
103 *
104 * Corresponding eBPF program may look like:
105 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
106 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
107 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
108 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
109 * here verifier looks at prototype of map_lookup_elem() and sees:
110 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
111 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
112 *
113 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
114 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
115 * and were initialized prior to this call.
116 * If it's ok, then verifier allows this BPF_CALL insn and looks at
117 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
118 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
119 * returns ether pointer to map value or NULL.
120 *
121 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
122 * insn, the register holding that pointer in the true branch changes state to
123 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
124 * branch. See check_cond_jmp_op().
125 *
126 * After the call R0 is set to return type of the function and registers R1-R5
127 * are set to NOT_INIT to indicate that they are no longer readable.
128 */
129
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700130/* verifier_state + insn_idx are pushed to stack when branch is encountered */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100131struct bpf_verifier_stack_elem {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700132 /* verifer state is 'st'
133 * before processing instruction 'insn_idx'
134 * and after processing instruction 'prev_insn_idx'
135 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100136 struct bpf_verifier_state st;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700137 int insn_idx;
138 int prev_insn_idx;
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100139 struct bpf_verifier_stack_elem *next;
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700140};
141
Daniel Borkmann07016152016-04-05 22:33:17 +0200142#define BPF_COMPLEXITY_LIMIT_INSNS 65536
143#define BPF_COMPLEXITY_LIMIT_STACK 1024
144
Daniel Borkmann33ff9822016-04-13 00:10:50 +0200145struct bpf_call_arg_meta {
146 struct bpf_map *map_ptr;
Daniel Borkmann435faee12016-04-13 00:10:51 +0200147 bool raw_mode;
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200148 bool pkt_access;
Daniel Borkmann435faee12016-04-13 00:10:51 +0200149 int regno;
150 int access_size;
Daniel Borkmann33ff9822016-04-13 00:10:50 +0200151};
152
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700153/* verbose verifier prints what it's seeing
154 * bpf_check() is called under lock, so no race to access these global vars
155 */
156static u32 log_level, log_size, log_len;
157static char *log_buf;
158
159static DEFINE_MUTEX(bpf_verifier_lock);
160
161/* log_level controls verbosity level of eBPF verifier.
162 * verbose() is used to dump the verification trace to the log, so the user
163 * can figure out what's wrong with the program
164 */
Daniel Borkmann1d056d92015-11-03 11:39:20 +0100165static __printf(1, 2) void verbose(const char *fmt, ...)
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700166{
167 va_list args;
168
169 if (log_level == 0 || log_len >= log_size - 1)
170 return;
171
172 va_start(args, fmt);
173 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
174 va_end(args);
175}
176
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700177/* string representation of 'enum bpf_reg_type' */
178static const char * const reg_type_str[] = {
179 [NOT_INIT] = "?",
180 [UNKNOWN_VALUE] = "inv",
181 [PTR_TO_CTX] = "ctx",
182 [CONST_PTR_TO_MAP] = "map_ptr",
183 [PTR_TO_MAP_VALUE] = "map_value",
184 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
Josef Bacik48461132016-09-28 10:54:32 -0400185 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj",
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700186 [FRAME_PTR] = "fp",
187 [PTR_TO_STACK] = "fp",
188 [CONST_IMM] = "imm",
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700189 [PTR_TO_PACKET] = "pkt",
190 [PTR_TO_PACKET_END] = "pkt_end",
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700191};
192
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100193static void print_verifier_state(struct bpf_verifier_state *state)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700194{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100195 struct bpf_reg_state *reg;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700196 enum bpf_reg_type t;
197 int i;
198
199 for (i = 0; i < MAX_BPF_REG; i++) {
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700200 reg = &state->regs[i];
201 t = reg->type;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700202 if (t == NOT_INIT)
203 continue;
204 verbose(" R%d=%s", i, reg_type_str[t]);
205 if (t == CONST_IMM || t == PTR_TO_STACK)
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700206 verbose("%lld", reg->imm);
207 else if (t == PTR_TO_PACKET)
208 verbose("(id=%d,off=%d,r=%d)",
209 reg->id, reg->off, reg->range);
210 else if (t == UNKNOWN_VALUE && reg->imm)
211 verbose("%lld", reg->imm);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700212 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
Josef Bacik48461132016-09-28 10:54:32 -0400213 t == PTR_TO_MAP_VALUE_OR_NULL ||
214 t == PTR_TO_MAP_VALUE_ADJ)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700215 verbose("(ks=%d,vs=%d)",
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700216 reg->map_ptr->key_size,
217 reg->map_ptr->value_size);
Josef Bacik48461132016-09-28 10:54:32 -0400218 if (reg->min_value != BPF_REGISTER_MIN_RANGE)
219 verbose(",min_value=%llu",
220 (unsigned long long)reg->min_value);
221 if (reg->max_value != BPF_REGISTER_MAX_RANGE)
222 verbose(",max_value=%llu",
223 (unsigned long long)reg->max_value);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700224 }
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700225 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700226 if (state->stack_slot_type[i] == STACK_SPILL)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700227 verbose(" fp%d=%s", -MAX_BPF_STACK + i,
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700228 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700229 }
230 verbose("\n");
231}
232
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700233static const char *const bpf_class_string[] = {
234 [BPF_LD] = "ld",
235 [BPF_LDX] = "ldx",
236 [BPF_ST] = "st",
237 [BPF_STX] = "stx",
238 [BPF_ALU] = "alu",
239 [BPF_JMP] = "jmp",
240 [BPF_RET] = "BUG",
241 [BPF_ALU64] = "alu64",
242};
243
Alexei Starovoitov687f0712015-09-08 13:40:01 -0700244static const char *const bpf_alu_string[16] = {
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700245 [BPF_ADD >> 4] = "+=",
246 [BPF_SUB >> 4] = "-=",
247 [BPF_MUL >> 4] = "*=",
248 [BPF_DIV >> 4] = "/=",
249 [BPF_OR >> 4] = "|=",
250 [BPF_AND >> 4] = "&=",
251 [BPF_LSH >> 4] = "<<=",
252 [BPF_RSH >> 4] = ">>=",
253 [BPF_NEG >> 4] = "neg",
254 [BPF_MOD >> 4] = "%=",
255 [BPF_XOR >> 4] = "^=",
256 [BPF_MOV >> 4] = "=",
257 [BPF_ARSH >> 4] = "s>>=",
258 [BPF_END >> 4] = "endian",
259};
260
261static const char *const bpf_ldst_string[] = {
262 [BPF_W >> 3] = "u32",
263 [BPF_H >> 3] = "u16",
264 [BPF_B >> 3] = "u8",
265 [BPF_DW >> 3] = "u64",
266};
267
Alexei Starovoitov687f0712015-09-08 13:40:01 -0700268static const char *const bpf_jmp_string[16] = {
Alexei Starovoitovcbd35702014-09-26 00:17:03 -0700269 [BPF_JA >> 4] = "jmp",
270 [BPF_JEQ >> 4] = "==",
271 [BPF_JGT >> 4] = ">",
272 [BPF_JGE >> 4] = ">=",
273 [BPF_JSET >> 4] = "&",
274 [BPF_JNE >> 4] = "!=",
275 [BPF_JSGT >> 4] = "s>",
276 [BPF_JSGE >> 4] = "s>=",
277 [BPF_CALL >> 4] = "call",
278 [BPF_EXIT >> 4] = "exit",
279};
280
281static void print_bpf_insn(struct bpf_insn *insn)
282{
283 u8 class = BPF_CLASS(insn->code);
284
285 if (class == BPF_ALU || class == BPF_ALU64) {
286 if (BPF_SRC(insn->code) == BPF_X)
287 verbose("(%02x) %sr%d %s %sr%d\n",
288 insn->code, class == BPF_ALU ? "(u32) " : "",
289 insn->dst_reg,
290 bpf_alu_string[BPF_OP(insn->code) >> 4],
291 class == BPF_ALU ? "(u32) " : "",
292 insn->src_reg);
293 else
294 verbose("(%02x) %sr%d %s %s%d\n",
295 insn->code, class == BPF_ALU ? "(u32) " : "",
296 insn->dst_reg,
297 bpf_alu_string[BPF_OP(insn->code) >> 4],
298 class == BPF_ALU ? "(u32) " : "",
299 insn->imm);
300 } else if (class == BPF_STX) {
301 if (BPF_MODE(insn->code) == BPF_MEM)
302 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
303 insn->code,
304 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
305 insn->dst_reg,
306 insn->off, insn->src_reg);
307 else if (BPF_MODE(insn->code) == BPF_XADD)
308 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
309 insn->code,
310 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
311 insn->dst_reg, insn->off,
312 insn->src_reg);
313 else
314 verbose("BUG_%02x\n", insn->code);
315 } else if (class == BPF_ST) {
316 if (BPF_MODE(insn->code) != BPF_MEM) {
317 verbose("BUG_st_%02x\n", insn->code);
318 return;
319 }
320 verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
321 insn->code,
322 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
323 insn->dst_reg,
324 insn->off, insn->imm);
325 } else if (class == BPF_LDX) {
326 if (BPF_MODE(insn->code) != BPF_MEM) {
327 verbose("BUG_ldx_%02x\n", insn->code);
328 return;
329 }
330 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
331 insn->code, insn->dst_reg,
332 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
333 insn->src_reg, insn->off);
334 } else if (class == BPF_LD) {
335 if (BPF_MODE(insn->code) == BPF_ABS) {
336 verbose("(%02x) r0 = *(%s *)skb[%d]\n",
337 insn->code,
338 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
339 insn->imm);
340 } else if (BPF_MODE(insn->code) == BPF_IND) {
341 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
342 insn->code,
343 bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
344 insn->src_reg, insn->imm);
345 } else if (BPF_MODE(insn->code) == BPF_IMM) {
346 verbose("(%02x) r%d = 0x%x\n",
347 insn->code, insn->dst_reg, insn->imm);
348 } else {
349 verbose("BUG_ld_%02x\n", insn->code);
350 return;
351 }
352 } else if (class == BPF_JMP) {
353 u8 opcode = BPF_OP(insn->code);
354
355 if (opcode == BPF_CALL) {
356 verbose("(%02x) call %d\n", insn->code, insn->imm);
357 } else if (insn->code == (BPF_JMP | BPF_JA)) {
358 verbose("(%02x) goto pc%+d\n",
359 insn->code, insn->off);
360 } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
361 verbose("(%02x) exit\n", insn->code);
362 } else if (BPF_SRC(insn->code) == BPF_X) {
363 verbose("(%02x) if r%d %s r%d goto pc%+d\n",
364 insn->code, insn->dst_reg,
365 bpf_jmp_string[BPF_OP(insn->code) >> 4],
366 insn->src_reg, insn->off);
367 } else {
368 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
369 insn->code, insn->dst_reg,
370 bpf_jmp_string[BPF_OP(insn->code) >> 4],
371 insn->imm, insn->off);
372 }
373 } else {
374 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
375 }
376}
377
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100378static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700379{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100380 struct bpf_verifier_stack_elem *elem;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700381 int insn_idx;
382
383 if (env->head == NULL)
384 return -1;
385
386 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
387 insn_idx = env->head->insn_idx;
388 if (prev_insn_idx)
389 *prev_insn_idx = env->head->prev_insn_idx;
390 elem = env->head->next;
391 kfree(env->head);
392 env->head = elem;
393 env->stack_size--;
394 return insn_idx;
395}
396
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100397static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
398 int insn_idx, int prev_insn_idx)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700399{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100400 struct bpf_verifier_stack_elem *elem;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700401
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100402 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700403 if (!elem)
404 goto err;
405
406 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
407 elem->insn_idx = insn_idx;
408 elem->prev_insn_idx = prev_insn_idx;
409 elem->next = env->head;
410 env->head = elem;
411 env->stack_size++;
Daniel Borkmann07016152016-04-05 22:33:17 +0200412 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700413 verbose("BPF program is too complex\n");
414 goto err;
415 }
416 return &elem->st;
417err:
418 /* pop all elements and return */
419 while (pop_stack(env, NULL) >= 0);
420 return NULL;
421}
422
423#define CALLER_SAVED_REGS 6
424static const int caller_saved[CALLER_SAVED_REGS] = {
425 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
426};
427
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100428static void init_reg_state(struct bpf_reg_state *regs)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700429{
430 int i;
431
432 for (i = 0; i < MAX_BPF_REG; i++) {
433 regs[i].type = NOT_INIT;
434 regs[i].imm = 0;
Josef Bacik48461132016-09-28 10:54:32 -0400435 regs[i].min_value = BPF_REGISTER_MIN_RANGE;
436 regs[i].max_value = BPF_REGISTER_MAX_RANGE;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700437 }
438
439 /* frame pointer */
440 regs[BPF_REG_FP].type = FRAME_PTR;
441
442 /* 1st arg to a function */
443 regs[BPF_REG_1].type = PTR_TO_CTX;
444}
445
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100446static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700447{
448 BUG_ON(regno >= MAX_BPF_REG);
449 regs[regno].type = UNKNOWN_VALUE;
450 regs[regno].imm = 0;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700451}
452
Josef Bacik48461132016-09-28 10:54:32 -0400453static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno)
454{
455 regs[regno].min_value = BPF_REGISTER_MIN_RANGE;
456 regs[regno].max_value = BPF_REGISTER_MAX_RANGE;
457}
458
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700459enum reg_arg_type {
460 SRC_OP, /* register is used as source operand */
461 DST_OP, /* register is used as destination operand */
462 DST_OP_NO_MARK /* same as above, check only, don't mark */
463};
464
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100465static int check_reg_arg(struct bpf_reg_state *regs, u32 regno,
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700466 enum reg_arg_type t)
467{
468 if (regno >= MAX_BPF_REG) {
469 verbose("R%d is invalid\n", regno);
470 return -EINVAL;
471 }
472
473 if (t == SRC_OP) {
474 /* check whether register used as source operand can be read */
475 if (regs[regno].type == NOT_INIT) {
476 verbose("R%d !read_ok\n", regno);
477 return -EACCES;
478 }
479 } else {
480 /* check whether register used as dest operand can be written to */
481 if (regno == BPF_REG_FP) {
482 verbose("frame pointer is read only\n");
483 return -EACCES;
484 }
485 if (t == DST_OP)
486 mark_reg_unknown_value(regs, regno);
487 }
488 return 0;
489}
490
491static int bpf_size_to_bytes(int bpf_size)
492{
493 if (bpf_size == BPF_W)
494 return 4;
495 else if (bpf_size == BPF_H)
496 return 2;
497 else if (bpf_size == BPF_B)
498 return 1;
499 else if (bpf_size == BPF_DW)
500 return 8;
501 else
502 return -EINVAL;
503}
504
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700505static bool is_spillable_regtype(enum bpf_reg_type type)
506{
507 switch (type) {
508 case PTR_TO_MAP_VALUE:
509 case PTR_TO_MAP_VALUE_OR_NULL:
510 case PTR_TO_STACK:
511 case PTR_TO_CTX:
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700512 case PTR_TO_PACKET:
513 case PTR_TO_PACKET_END:
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700514 case FRAME_PTR:
515 case CONST_PTR_TO_MAP:
516 return true;
517 default:
518 return false;
519 }
520}
521
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700522/* check_stack_read/write functions track spill/fill of registers,
523 * stack boundary and alignment are checked in check_mem_access()
524 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100525static int check_stack_write(struct bpf_verifier_state *state, int off,
526 int size, int value_regno)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700527{
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700528 int i;
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700529 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
530 * so it's aligned access and [off, off + size) are within stack limits
531 */
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700532
533 if (value_regno >= 0 &&
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700534 is_spillable_regtype(state->regs[value_regno].type)) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700535
536 /* register containing pointer is being spilled into stack */
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700537 if (size != BPF_REG_SIZE) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700538 verbose("invalid size of register spill\n");
539 return -EACCES;
540 }
541
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700542 /* save register state */
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700543 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
544 state->regs[value_regno];
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700545
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700546 for (i = 0; i < BPF_REG_SIZE; i++)
547 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
548 } else {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700549 /* regular write of data into stack */
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700550 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100551 (struct bpf_reg_state) {};
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700552
553 for (i = 0; i < size; i++)
554 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700555 }
556 return 0;
557}
558
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100559static int check_stack_read(struct bpf_verifier_state *state, int off, int size,
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700560 int value_regno)
561{
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700562 u8 *slot_type;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700563 int i;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700564
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700565 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700566
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700567 if (slot_type[0] == STACK_SPILL) {
568 if (size != BPF_REG_SIZE) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700569 verbose("invalid size of register spill\n");
570 return -EACCES;
571 }
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700572 for (i = 1; i < BPF_REG_SIZE; i++) {
573 if (slot_type[i] != STACK_SPILL) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700574 verbose("corrupted spill memory\n");
575 return -EACCES;
576 }
577 }
578
579 if (value_regno >= 0)
580 /* restore register state from stack */
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700581 state->regs[value_regno] =
582 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700583 return 0;
584 } else {
585 for (i = 0; i < size; i++) {
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700586 if (slot_type[i] != STACK_MISC) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700587 verbose("invalid read from stack off %d+%d size %d\n",
588 off, i, size);
589 return -EACCES;
590 }
591 }
592 if (value_regno >= 0)
593 /* have read misc data from the stack */
594 mark_reg_unknown_value(state->regs, value_regno);
595 return 0;
596 }
597}
598
599/* check read/write into map element returned by bpf_map_lookup_elem() */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100600static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700601 int size)
602{
603 struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
604
605 if (off < 0 || off + size > map->value_size) {
606 verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
607 map->value_size, off, size);
608 return -EACCES;
609 }
610 return 0;
611}
612
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700613#define MAX_PACKET_OFF 0xffff
614
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100615static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200616 const struct bpf_call_arg_meta *meta)
Brenden Blanco4acf6c02016-07-19 12:16:56 -0700617{
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200618 switch (env->prog->type) {
619 case BPF_PROG_TYPE_SCHED_CLS:
620 case BPF_PROG_TYPE_SCHED_ACT:
Brenden Blanco4acf6c02016-07-19 12:16:56 -0700621 case BPF_PROG_TYPE_XDP:
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200622 if (meta)
623 return meta->pkt_access;
624
625 env->seen_direct_write = true;
Brenden Blanco4acf6c02016-07-19 12:16:56 -0700626 return true;
627 default:
628 return false;
629 }
630}
631
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100632static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700633 int size)
634{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100635 struct bpf_reg_state *regs = env->cur_state.regs;
636 struct bpf_reg_state *reg = &regs[regno];
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700637
Alexei Starovoitovd91b28e2016-05-19 18:17:13 -0700638 off += reg->off;
Daniel Borkmannb399cf62016-09-20 00:26:12 +0200639 if (off < 0 || size <= 0 || off + size > reg->range) {
Alexei Starovoitovd91b28e2016-05-19 18:17:13 -0700640 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
641 off, size, regno, reg->id, reg->off, reg->range);
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700642 return -EACCES;
643 }
644 return 0;
645}
646
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700647/* check access to 'struct bpf_context' fields */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100648static int check_ctx_access(struct bpf_verifier_env *env, int off, int size,
Alexei Starovoitov19de99f2016-06-15 18:25:38 -0700649 enum bpf_access_type t, enum bpf_reg_type *reg_type)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700650{
Jakub Kicinski13a27df2016-09-21 11:43:58 +0100651 /* for analyzer ctx accesses are already validated and converted */
652 if (env->analyzer_ops)
653 return 0;
654
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700655 if (env->prog->aux->ops->is_valid_access &&
Alexei Starovoitov19de99f2016-06-15 18:25:38 -0700656 env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) {
Alexei Starovoitov32bbe002016-04-06 18:43:28 -0700657 /* remember the offset of last byte accessed in ctx */
658 if (env->prog->aux->max_ctx_offset < off + size)
659 env->prog->aux->max_ctx_offset = off + size;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700660 return 0;
Alexei Starovoitov32bbe002016-04-06 18:43:28 -0700661 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700662
663 verbose("invalid bpf_context access off=%d size=%d\n", off, size);
664 return -EACCES;
665}
666
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100667static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700668{
669 if (env->allow_ptr_leaks)
670 return false;
671
672 switch (env->cur_state.regs[regno].type) {
673 case UNKNOWN_VALUE:
674 case CONST_IMM:
675 return false;
676 default:
677 return true;
678 }
679}
680
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100681static int check_ptr_alignment(struct bpf_verifier_env *env,
682 struct bpf_reg_state *reg, int off, int size)
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700683{
Josef Bacik48461132016-09-28 10:54:32 -0400684 if (reg->type != PTR_TO_PACKET && reg->type != PTR_TO_MAP_VALUE_ADJ) {
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700685 if (off % size != 0) {
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100686 verbose("misaligned access off %d size %d\n",
687 off, size);
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700688 return -EACCES;
689 } else {
690 return 0;
691 }
692 }
693
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700694 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
695 /* misaligned access to packet is ok on x86,arm,arm64 */
696 return 0;
697
698 if (reg->id && size != 1) {
699 verbose("Unknown packet alignment. Only byte-sized access allowed\n");
700 return -EACCES;
701 }
702
703 /* skb->data is NET_IP_ALIGN-ed */
Josef Bacik48461132016-09-28 10:54:32 -0400704 if (reg->type == PTR_TO_PACKET &&
705 (NET_IP_ALIGN + reg->off + off) % size != 0) {
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700706 verbose("misaligned packet access off %d+%d+%d size %d\n",
707 NET_IP_ALIGN, reg->off, off, size);
708 return -EACCES;
709 }
710 return 0;
711}
712
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700713/* check whether memory at (regno + off) is accessible for t = (read | write)
714 * if t==write, value_regno is a register which value is stored into memory
715 * if t==read, value_regno is a register which will receive the value from memory
716 * if t==write && value_regno==-1, some unknown value is stored into memory
717 * if t==read && value_regno==-1, don't care what we read from memory
718 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100719static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off,
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700720 int bpf_size, enum bpf_access_type t,
721 int value_regno)
722{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100723 struct bpf_verifier_state *state = &env->cur_state;
724 struct bpf_reg_state *reg = &state->regs[regno];
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700725 int size, err = 0;
726
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700727 if (reg->type == PTR_TO_STACK)
728 off += reg->imm;
Alex Gartrell24b4d2a2015-07-23 14:24:40 -0700729
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700730 size = bpf_size_to_bytes(bpf_size);
731 if (size < 0)
732 return size;
733
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700734 err = check_ptr_alignment(env, reg, off, size);
735 if (err)
736 return err;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700737
Josef Bacik48461132016-09-28 10:54:32 -0400738 if (reg->type == PTR_TO_MAP_VALUE ||
739 reg->type == PTR_TO_MAP_VALUE_ADJ) {
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700740 if (t == BPF_WRITE && value_regno >= 0 &&
741 is_pointer_value(env, value_regno)) {
742 verbose("R%d leaks addr into map\n", value_regno);
743 return -EACCES;
744 }
Josef Bacik48461132016-09-28 10:54:32 -0400745
746 /* If we adjusted the register to this map value at all then we
747 * need to change off and size to min_value and max_value
748 * respectively to make sure our theoretical access will be
749 * safe.
750 */
751 if (reg->type == PTR_TO_MAP_VALUE_ADJ) {
752 if (log_level)
753 print_verifier_state(state);
754 env->varlen_map_value_access = true;
755 /* The minimum value is only important with signed
756 * comparisons where we can't assume the floor of a
757 * value is 0. If we are using signed variables for our
758 * index'es we need to make sure that whatever we use
759 * will have a set floor within our range.
760 */
761 if ((s64)reg->min_value < 0) {
762 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
763 regno);
764 return -EACCES;
765 }
766 err = check_map_access(env, regno, reg->min_value + off,
767 size);
768 if (err) {
769 verbose("R%d min value is outside of the array range\n",
770 regno);
771 return err;
772 }
773
774 /* If we haven't set a max value then we need to bail
775 * since we can't be sure we won't do bad things.
776 */
777 if (reg->max_value == BPF_REGISTER_MAX_RANGE) {
778 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n",
779 regno);
780 return -EACCES;
781 }
782 off += reg->max_value;
783 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700784 err = check_map_access(env, regno, off, size);
785 if (!err && t == BPF_READ && value_regno >= 0)
786 mark_reg_unknown_value(state->regs, value_regno);
787
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700788 } else if (reg->type == PTR_TO_CTX) {
Alexei Starovoitov19de99f2016-06-15 18:25:38 -0700789 enum bpf_reg_type reg_type = UNKNOWN_VALUE;
790
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700791 if (t == BPF_WRITE && value_regno >= 0 &&
792 is_pointer_value(env, value_regno)) {
793 verbose("R%d leaks addr into ctx\n", value_regno);
794 return -EACCES;
795 }
Alexei Starovoitov19de99f2016-06-15 18:25:38 -0700796 err = check_ctx_access(env, off, size, t, &reg_type);
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700797 if (!err && t == BPF_READ && value_regno >= 0) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700798 mark_reg_unknown_value(state->regs, value_regno);
Mickaël Salaün19553512016-09-24 20:01:50 +0200799 /* note that reg.[id|off|range] == 0 */
800 state->regs[value_regno].type = reg_type;
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700801 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700802
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700803 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700804 if (off >= 0 || off < -MAX_BPF_STACK) {
805 verbose("invalid stack off=%d size=%d\n", off, size);
806 return -EACCES;
807 }
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700808 if (t == BPF_WRITE) {
809 if (!env->allow_ptr_leaks &&
810 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
811 size != BPF_REG_SIZE) {
812 verbose("attempt to corrupt spilled pointer on stack\n");
813 return -EACCES;
814 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700815 err = check_stack_write(state, off, size, value_regno);
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700816 } else {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700817 err = check_stack_read(state, off, size, value_regno);
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700818 }
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700819 } else if (state->regs[regno].type == PTR_TO_PACKET) {
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200820 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL)) {
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700821 verbose("cannot write into packet\n");
822 return -EACCES;
823 }
Brenden Blanco4acf6c02016-07-19 12:16:56 -0700824 if (t == BPF_WRITE && value_regno >= 0 &&
825 is_pointer_value(env, value_regno)) {
826 verbose("R%d leaks addr into packet\n", value_regno);
827 return -EACCES;
828 }
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700829 err = check_packet_access(env, regno, off, size);
830 if (!err && t == BPF_READ && value_regno >= 0)
831 mark_reg_unknown_value(state->regs, value_regno);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700832 } else {
833 verbose("R%d invalid mem access '%s'\n",
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -0700834 regno, reg_type_str[reg->type]);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700835 return -EACCES;
836 }
Alexei Starovoitov969bf052016-05-05 19:49:10 -0700837
838 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks &&
839 state->regs[value_regno].type == UNKNOWN_VALUE) {
840 /* 1 or 2 byte load zero-extends, determine the number of
841 * zero upper bits. Not doing it fo 4 byte load, since
842 * such values cannot be added to ptr_to_packet anyway.
843 */
844 state->regs[value_regno].imm = 64 - size * 8;
845 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700846 return err;
847}
848
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100849static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700850{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100851 struct bpf_reg_state *regs = env->cur_state.regs;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700852 int err;
853
854 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
855 insn->imm != 0) {
856 verbose("BPF_XADD uses reserved fields\n");
857 return -EINVAL;
858 }
859
860 /* check src1 operand */
861 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
862 if (err)
863 return err;
864
865 /* check src2 operand */
866 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
867 if (err)
868 return err;
869
870 /* check whether atomic_add can read the memory */
871 err = check_mem_access(env, insn->dst_reg, insn->off,
872 BPF_SIZE(insn->code), BPF_READ, -1);
873 if (err)
874 return err;
875
876 /* check whether atomic_add can write into the same memory */
877 return check_mem_access(env, insn->dst_reg, insn->off,
878 BPF_SIZE(insn->code), BPF_WRITE, -1);
879}
880
881/* when register 'regno' is passed into function that will read 'access_size'
882 * bytes from that pointer, make sure that it's within stack boundary
883 * and all elements of stack are initialized
884 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100885static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
Daniel Borkmann435faee12016-04-13 00:10:51 +0200886 int access_size, bool zero_size_allowed,
887 struct bpf_call_arg_meta *meta)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700888{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100889 struct bpf_verifier_state *state = &env->cur_state;
890 struct bpf_reg_state *regs = state->regs;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700891 int off, i;
892
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +0100893 if (regs[regno].type != PTR_TO_STACK) {
894 if (zero_size_allowed && access_size == 0 &&
895 regs[regno].type == CONST_IMM &&
896 regs[regno].imm == 0)
897 return 0;
898
899 verbose("R%d type=%s expected=%s\n", regno,
900 reg_type_str[regs[regno].type],
901 reg_type_str[PTR_TO_STACK]);
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700902 return -EACCES;
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +0100903 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700904
905 off = regs[regno].imm;
906 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
907 access_size <= 0) {
908 verbose("invalid stack type R%d off=%d access_size=%d\n",
909 regno, off, access_size);
910 return -EACCES;
911 }
912
Daniel Borkmann435faee12016-04-13 00:10:51 +0200913 if (meta && meta->raw_mode) {
914 meta->access_size = access_size;
915 meta->regno = regno;
916 return 0;
917 }
918
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700919 for (i = 0; i < access_size; i++) {
Alexei Starovoitov9c3997602014-10-28 15:11:41 -0700920 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700921 verbose("invalid indirect read from stack off %d+%d size %d\n",
922 off, i, access_size);
923 return -EACCES;
924 }
925 }
926 return 0;
927}
928
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100929static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
Daniel Borkmann33ff9822016-04-13 00:10:50 +0200930 enum bpf_arg_type arg_type,
931 struct bpf_call_arg_meta *meta)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700932{
Jakub Kicinski58e2af82016-09-21 11:43:57 +0100933 struct bpf_reg_state *regs = env->cur_state.regs, *reg = &regs[regno];
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700934 enum bpf_reg_type expected_type, type = reg->type;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700935 int err = 0;
936
Daniel Borkmann80f1d682015-03-12 17:21:42 +0100937 if (arg_type == ARG_DONTCARE)
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700938 return 0;
939
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700940 if (type == NOT_INIT) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700941 verbose("R%d !read_ok\n", regno);
942 return -EACCES;
943 }
944
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700945 if (arg_type == ARG_ANYTHING) {
946 if (is_pointer_value(env, regno)) {
947 verbose("R%d leaks addr into helper function\n", regno);
948 return -EACCES;
949 }
Daniel Borkmann80f1d682015-03-12 17:21:42 +0100950 return 0;
Alexei Starovoitov1be7f752015-10-07 22:23:21 -0700951 }
Daniel Borkmann80f1d682015-03-12 17:21:42 +0100952
Daniel Borkmann36bbef52016-09-20 00:26:13 +0200953 if (type == PTR_TO_PACKET && !may_access_direct_pkt_data(env, meta)) {
954 verbose("helper access to the packet is not allowed\n");
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700955 return -EACCES;
956 }
957
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +0100958 if (arg_type == ARG_PTR_TO_MAP_KEY ||
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700959 arg_type == ARG_PTR_TO_MAP_VALUE) {
960 expected_type = PTR_TO_STACK;
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700961 if (type != PTR_TO_PACKET && type != expected_type)
962 goto err_type;
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +0100963 } else if (arg_type == ARG_CONST_STACK_SIZE ||
964 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700965 expected_type = CONST_IMM;
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700966 if (type != expected_type)
967 goto err_type;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700968 } else if (arg_type == ARG_CONST_MAP_PTR) {
969 expected_type = CONST_PTR_TO_MAP;
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700970 if (type != expected_type)
971 goto err_type;
Alexei Starovoitov608cd712015-03-26 19:53:57 -0700972 } else if (arg_type == ARG_PTR_TO_CTX) {
973 expected_type = PTR_TO_CTX;
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700974 if (type != expected_type)
975 goto err_type;
Daniel Borkmann435faee12016-04-13 00:10:51 +0200976 } else if (arg_type == ARG_PTR_TO_STACK ||
977 arg_type == ARG_PTR_TO_RAW_STACK) {
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +0100978 expected_type = PTR_TO_STACK;
979 /* One exception here. In case function allows for NULL to be
980 * passed in as argument, it's a CONST_IMM type. Final test
981 * happens during stack boundary checking.
982 */
Alexei Starovoitov6841de82016-08-11 18:17:16 -0700983 if (type == CONST_IMM && reg->imm == 0)
984 /* final test in check_stack_boundary() */;
985 else if (type != PTR_TO_PACKET && type != expected_type)
986 goto err_type;
Daniel Borkmann435faee12016-04-13 00:10:51 +0200987 meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700988 } else {
989 verbose("unsupported arg_type %d\n", arg_type);
990 return -EFAULT;
991 }
992
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700993 if (arg_type == ARG_CONST_MAP_PTR) {
994 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
Daniel Borkmann33ff9822016-04-13 00:10:50 +0200995 meta->map_ptr = reg->map_ptr;
Alexei Starovoitov17a52672014-09-26 00:17:06 -0700996 } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
997 /* bpf_map_xxx(..., map_ptr, ..., key) call:
998 * check that [key, key + map->key_size) are within
999 * stack limits and initialized
1000 */
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001001 if (!meta->map_ptr) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001002 /* in function declaration map_ptr must come before
1003 * map_key, so that it's verified and known before
1004 * we have to check map_key here. Otherwise it means
1005 * that kernel subsystem misconfigured verifier
1006 */
1007 verbose("invalid map_ptr to access map->key\n");
1008 return -EACCES;
1009 }
Alexei Starovoitov6841de82016-08-11 18:17:16 -07001010 if (type == PTR_TO_PACKET)
1011 err = check_packet_access(env, regno, 0,
1012 meta->map_ptr->key_size);
1013 else
1014 err = check_stack_boundary(env, regno,
1015 meta->map_ptr->key_size,
1016 false, NULL);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001017 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
1018 /* bpf_map_xxx(..., map_ptr, ..., value) call:
1019 * check [value, value + map->value_size) validity
1020 */
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001021 if (!meta->map_ptr) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001022 /* kernel subsystem misconfigured verifier */
1023 verbose("invalid map_ptr to access map->value\n");
1024 return -EACCES;
1025 }
Alexei Starovoitov6841de82016-08-11 18:17:16 -07001026 if (type == PTR_TO_PACKET)
1027 err = check_packet_access(env, regno, 0,
1028 meta->map_ptr->value_size);
1029 else
1030 err = check_stack_boundary(env, regno,
1031 meta->map_ptr->value_size,
1032 false, NULL);
Daniel Borkmann8e2fe1d92016-02-19 23:05:22 +01001033 } else if (arg_type == ARG_CONST_STACK_SIZE ||
1034 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) {
1035 bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001036
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001037 /* bpf_xxx(..., buf, len) call will access 'len' bytes
1038 * from stack pointer 'buf'. Check it
1039 * note: regno == len, regno - 1 == buf
1040 */
1041 if (regno == 0) {
1042 /* kernel subsystem misconfigured verifier */
1043 verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
1044 return -EACCES;
1045 }
Alexei Starovoitov6841de82016-08-11 18:17:16 -07001046 if (regs[regno - 1].type == PTR_TO_PACKET)
1047 err = check_packet_access(env, regno - 1, 0, reg->imm);
1048 else
1049 err = check_stack_boundary(env, regno - 1, reg->imm,
1050 zero_size_allowed, meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001051 }
1052
1053 return err;
Alexei Starovoitov6841de82016-08-11 18:17:16 -07001054err_type:
1055 verbose("R%d type=%s expected=%s\n", regno,
1056 reg_type_str[type], reg_type_str[expected_type]);
1057 return -EACCES;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001058}
1059
Kaixu Xia35578d72015-08-06 07:02:35 +00001060static int check_map_func_compatibility(struct bpf_map *map, int func_id)
1061{
Kaixu Xia35578d72015-08-06 07:02:35 +00001062 if (!map)
1063 return 0;
1064
Alexei Starovoitov6aff67c2016-04-27 18:56:21 -07001065 /* We need a two way check, first is from map perspective ... */
1066 switch (map->map_type) {
1067 case BPF_MAP_TYPE_PROG_ARRAY:
1068 if (func_id != BPF_FUNC_tail_call)
1069 goto error;
1070 break;
1071 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
1072 if (func_id != BPF_FUNC_perf_event_read &&
1073 func_id != BPF_FUNC_perf_event_output)
1074 goto error;
1075 break;
1076 case BPF_MAP_TYPE_STACK_TRACE:
1077 if (func_id != BPF_FUNC_get_stackid)
1078 goto error;
1079 break;
Martin KaFai Lau4ed8ec52016-06-30 10:28:43 -07001080 case BPF_MAP_TYPE_CGROUP_ARRAY:
David S. Miller60747ef2016-08-18 01:17:32 -04001081 if (func_id != BPF_FUNC_skb_under_cgroup &&
Sargun Dhillon60d20f92016-08-12 08:56:52 -07001082 func_id != BPF_FUNC_current_task_under_cgroup)
Martin KaFai Lau4a482f32016-06-30 10:28:44 -07001083 goto error;
1084 break;
Alexei Starovoitov6aff67c2016-04-27 18:56:21 -07001085 default:
1086 break;
1087 }
1088
1089 /* ... and second from the function itself. */
1090 switch (func_id) {
1091 case BPF_FUNC_tail_call:
1092 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
1093 goto error;
1094 break;
1095 case BPF_FUNC_perf_event_read:
1096 case BPF_FUNC_perf_event_output:
1097 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
1098 goto error;
1099 break;
1100 case BPF_FUNC_get_stackid:
1101 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
1102 goto error;
1103 break;
Sargun Dhillon60d20f92016-08-12 08:56:52 -07001104 case BPF_FUNC_current_task_under_cgroup:
Daniel Borkmann747ea552016-08-12 22:17:17 +02001105 case BPF_FUNC_skb_under_cgroup:
Martin KaFai Lau4a482f32016-06-30 10:28:44 -07001106 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
1107 goto error;
1108 break;
Alexei Starovoitov6aff67c2016-04-27 18:56:21 -07001109 default:
1110 break;
Kaixu Xia35578d72015-08-06 07:02:35 +00001111 }
1112
1113 return 0;
Alexei Starovoitov6aff67c2016-04-27 18:56:21 -07001114error:
1115 verbose("cannot pass map_type %d into func %d\n",
1116 map->map_type, func_id);
1117 return -EINVAL;
Kaixu Xia35578d72015-08-06 07:02:35 +00001118}
1119
Daniel Borkmann435faee12016-04-13 00:10:51 +02001120static int check_raw_mode(const struct bpf_func_proto *fn)
1121{
1122 int count = 0;
1123
1124 if (fn->arg1_type == ARG_PTR_TO_RAW_STACK)
1125 count++;
1126 if (fn->arg2_type == ARG_PTR_TO_RAW_STACK)
1127 count++;
1128 if (fn->arg3_type == ARG_PTR_TO_RAW_STACK)
1129 count++;
1130 if (fn->arg4_type == ARG_PTR_TO_RAW_STACK)
1131 count++;
1132 if (fn->arg5_type == ARG_PTR_TO_RAW_STACK)
1133 count++;
1134
1135 return count > 1 ? -EINVAL : 0;
1136}
1137
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001138static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001139{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001140 struct bpf_verifier_state *state = &env->cur_state;
1141 struct bpf_reg_state *regs = state->regs, *reg;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001142 int i;
1143
1144 for (i = 0; i < MAX_BPF_REG; i++)
1145 if (regs[i].type == PTR_TO_PACKET ||
1146 regs[i].type == PTR_TO_PACKET_END)
1147 mark_reg_unknown_value(regs, i);
1148
1149 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1150 if (state->stack_slot_type[i] != STACK_SPILL)
1151 continue;
1152 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1153 if (reg->type != PTR_TO_PACKET &&
1154 reg->type != PTR_TO_PACKET_END)
1155 continue;
1156 reg->type = UNKNOWN_VALUE;
1157 reg->imm = 0;
1158 }
1159}
1160
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001161static int check_call(struct bpf_verifier_env *env, int func_id)
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001162{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001163 struct bpf_verifier_state *state = &env->cur_state;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001164 const struct bpf_func_proto *fn = NULL;
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001165 struct bpf_reg_state *regs = state->regs;
1166 struct bpf_reg_state *reg;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001167 struct bpf_call_arg_meta meta;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001168 bool changes_data;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001169 int i, err;
1170
1171 /* find function prototype */
1172 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
1173 verbose("invalid func %d\n", func_id);
1174 return -EINVAL;
1175 }
1176
1177 if (env->prog->aux->ops->get_func_proto)
1178 fn = env->prog->aux->ops->get_func_proto(func_id);
1179
1180 if (!fn) {
1181 verbose("unknown func %d\n", func_id);
1182 return -EINVAL;
1183 }
1184
1185 /* eBPF programs must be GPL compatible to use GPL-ed functions */
Daniel Borkmann24701ec2015-03-01 12:31:47 +01001186 if (!env->prog->gpl_compatible && fn->gpl_only) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001187 verbose("cannot call GPL only function from proprietary program\n");
1188 return -EINVAL;
1189 }
1190
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001191 changes_data = bpf_helper_changes_skb_data(fn->func);
1192
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001193 memset(&meta, 0, sizeof(meta));
Daniel Borkmann36bbef52016-09-20 00:26:13 +02001194 meta.pkt_access = fn->pkt_access;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001195
Daniel Borkmann435faee12016-04-13 00:10:51 +02001196 /* We only support one arg being in raw mode at the moment, which
1197 * is sufficient for the helper functions we have right now.
1198 */
1199 err = check_raw_mode(fn);
1200 if (err) {
1201 verbose("kernel subsystem misconfigured func %d\n", func_id);
1202 return err;
1203 }
1204
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001205 /* check args */
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001206 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001207 if (err)
1208 return err;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001209 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001210 if (err)
1211 return err;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001212 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001213 if (err)
1214 return err;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001215 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001216 if (err)
1217 return err;
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001218 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001219 if (err)
1220 return err;
1221
Daniel Borkmann435faee12016-04-13 00:10:51 +02001222 /* Mark slots with STACK_MISC in case of raw mode, stack offset
1223 * is inferred from register state.
1224 */
1225 for (i = 0; i < meta.access_size; i++) {
1226 err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1);
1227 if (err)
1228 return err;
1229 }
1230
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001231 /* reset caller saved regs */
1232 for (i = 0; i < CALLER_SAVED_REGS; i++) {
1233 reg = regs + caller_saved[i];
1234 reg->type = NOT_INIT;
1235 reg->imm = 0;
1236 }
1237
1238 /* update return register */
1239 if (fn->ret_type == RET_INTEGER) {
1240 regs[BPF_REG_0].type = UNKNOWN_VALUE;
1241 } else if (fn->ret_type == RET_VOID) {
1242 regs[BPF_REG_0].type = NOT_INIT;
1243 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
1244 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
Josef Bacik48461132016-09-28 10:54:32 -04001245 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001246 /* remember map_ptr, so that check_map_access()
1247 * can check 'value_size' boundary of memory access
1248 * to map element returned from bpf_map_lookup_elem()
1249 */
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001250 if (meta.map_ptr == NULL) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001251 verbose("kernel subsystem misconfigured verifier\n");
1252 return -EINVAL;
1253 }
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001254 regs[BPF_REG_0].map_ptr = meta.map_ptr;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001255 } else {
1256 verbose("unknown return type %d of func %d\n",
1257 fn->ret_type, func_id);
1258 return -EINVAL;
1259 }
Alexei Starovoitov04fd61a2015-05-19 16:59:03 -07001260
Daniel Borkmann33ff9822016-04-13 00:10:50 +02001261 err = check_map_func_compatibility(meta.map_ptr, func_id);
Kaixu Xia35578d72015-08-06 07:02:35 +00001262 if (err)
1263 return err;
Alexei Starovoitov04fd61a2015-05-19 16:59:03 -07001264
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001265 if (changes_data)
1266 clear_all_pkt_pointers(env);
1267 return 0;
1268}
1269
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001270static int check_packet_ptr_add(struct bpf_verifier_env *env,
1271 struct bpf_insn *insn)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001272{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001273 struct bpf_reg_state *regs = env->cur_state.regs;
1274 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
1275 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
1276 struct bpf_reg_state tmp_reg;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001277 s32 imm;
1278
1279 if (BPF_SRC(insn->code) == BPF_K) {
1280 /* pkt_ptr += imm */
1281 imm = insn->imm;
1282
1283add_imm:
1284 if (imm <= 0) {
1285 verbose("addition of negative constant to packet pointer is not allowed\n");
1286 return -EACCES;
1287 }
1288 if (imm >= MAX_PACKET_OFF ||
1289 imm + dst_reg->off >= MAX_PACKET_OFF) {
1290 verbose("constant %d is too large to add to packet pointer\n",
1291 imm);
1292 return -EACCES;
1293 }
1294 /* a constant was added to pkt_ptr.
1295 * Remember it while keeping the same 'id'
1296 */
1297 dst_reg->off += imm;
1298 } else {
Alexei Starovoitov1b9b69e2016-05-19 18:17:14 -07001299 if (src_reg->type == PTR_TO_PACKET) {
1300 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
1301 tmp_reg = *dst_reg; /* save r7 state */
1302 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
1303 src_reg = &tmp_reg; /* pretend it's src_reg state */
1304 /* if the checks below reject it, the copy won't matter,
1305 * since we're rejecting the whole program. If all ok,
1306 * then imm22 state will be added to r7
1307 * and r7 will be pkt(id=0,off=22,r=62) while
1308 * r6 will stay as pkt(id=0,off=0,r=62)
1309 */
1310 }
1311
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001312 if (src_reg->type == CONST_IMM) {
1313 /* pkt_ptr += reg where reg is known constant */
1314 imm = src_reg->imm;
1315 goto add_imm;
1316 }
1317 /* disallow pkt_ptr += reg
1318 * if reg is not uknown_value with guaranteed zero upper bits
1319 * otherwise pkt_ptr may overflow and addition will become
1320 * subtraction which is not allowed
1321 */
1322 if (src_reg->type != UNKNOWN_VALUE) {
1323 verbose("cannot add '%s' to ptr_to_packet\n",
1324 reg_type_str[src_reg->type]);
1325 return -EACCES;
1326 }
1327 if (src_reg->imm < 48) {
1328 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n",
1329 src_reg->imm);
1330 return -EACCES;
1331 }
1332 /* dst_reg stays as pkt_ptr type and since some positive
1333 * integer value was added to the pointer, increment its 'id'
1334 */
Jakub Kicinski1f415a72016-08-02 16:12:14 +01001335 dst_reg->id = ++env->id_gen;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001336
1337 /* something was added to pkt_ptr, set range and off to zero */
1338 dst_reg->off = 0;
1339 dst_reg->range = 0;
1340 }
1341 return 0;
1342}
1343
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001344static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001345{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001346 struct bpf_reg_state *regs = env->cur_state.regs;
1347 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001348 u8 opcode = BPF_OP(insn->code);
1349 s64 imm_log2;
1350
1351 /* for type == UNKNOWN_VALUE:
1352 * imm > 0 -> number of zero upper bits
1353 * imm == 0 -> don't track which is the same as all bits can be non-zero
1354 */
1355
1356 if (BPF_SRC(insn->code) == BPF_X) {
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001357 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001358
1359 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 &&
1360 dst_reg->imm && opcode == BPF_ADD) {
1361 /* dreg += sreg
1362 * where both have zero upper bits. Adding them
1363 * can only result making one more bit non-zero
1364 * in the larger value.
1365 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47)
1366 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47)
1367 */
1368 dst_reg->imm = min(dst_reg->imm, src_reg->imm);
1369 dst_reg->imm--;
1370 return 0;
1371 }
1372 if (src_reg->type == CONST_IMM && src_reg->imm > 0 &&
1373 dst_reg->imm && opcode == BPF_ADD) {
1374 /* dreg += sreg
1375 * where dreg has zero upper bits and sreg is const.
1376 * Adding them can only result making one more bit
1377 * non-zero in the larger value.
1378 */
1379 imm_log2 = __ilog2_u64((long long)src_reg->imm);
1380 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1381 dst_reg->imm--;
1382 return 0;
1383 }
1384 /* all other cases non supported yet, just mark dst_reg */
1385 dst_reg->imm = 0;
1386 return 0;
1387 }
1388
1389 /* sign extend 32-bit imm into 64-bit to make sure that
1390 * negative values occupy bit 63. Note ilog2() would have
1391 * been incorrect, since sizeof(insn->imm) == 4
1392 */
1393 imm_log2 = __ilog2_u64((long long)insn->imm);
1394
1395 if (dst_reg->imm && opcode == BPF_LSH) {
1396 /* reg <<= imm
1397 * if reg was a result of 2 byte load, then its imm == 48
1398 * which means that upper 48 bits are zero and shifting this reg
1399 * left by 4 would mean that upper 44 bits are still zero
1400 */
1401 dst_reg->imm -= insn->imm;
1402 } else if (dst_reg->imm && opcode == BPF_MUL) {
1403 /* reg *= imm
1404 * if multiplying by 14 subtract 4
1405 * This is conservative calculation of upper zero bits.
1406 * It's not trying to special case insn->imm == 1 or 0 cases
1407 */
1408 dst_reg->imm -= imm_log2 + 1;
1409 } else if (opcode == BPF_AND) {
1410 /* reg &= imm */
1411 dst_reg->imm = 63 - imm_log2;
1412 } else if (dst_reg->imm && opcode == BPF_ADD) {
1413 /* reg += imm */
1414 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2);
1415 dst_reg->imm--;
1416 } else if (opcode == BPF_RSH) {
1417 /* reg >>= imm
1418 * which means that after right shift, upper bits will be zero
1419 * note that verifier already checked that
1420 * 0 <= imm < 64 for shift insn
1421 */
1422 dst_reg->imm += insn->imm;
1423 if (unlikely(dst_reg->imm > 64))
1424 /* some dumb code did:
1425 * r2 = *(u32 *)mem;
1426 * r2 >>= 32;
1427 * and all bits are zero now */
1428 dst_reg->imm = 64;
1429 } else {
1430 /* all other alu ops, means that we don't know what will
1431 * happen to the value, mark it with unknown number of zero bits
1432 */
1433 dst_reg->imm = 0;
1434 }
1435
1436 if (dst_reg->imm < 0) {
1437 /* all 64 bits of the register can contain non-zero bits
1438 * and such value cannot be added to ptr_to_packet, since it
1439 * may overflow, mark it as unknown to avoid further eval
1440 */
1441 dst_reg->imm = 0;
1442 }
1443 return 0;
1444}
1445
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001446static int evaluate_reg_imm_alu(struct bpf_verifier_env *env,
1447 struct bpf_insn *insn)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001448{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001449 struct bpf_reg_state *regs = env->cur_state.regs;
1450 struct bpf_reg_state *dst_reg = &regs[insn->dst_reg];
1451 struct bpf_reg_state *src_reg = &regs[insn->src_reg];
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001452 u8 opcode = BPF_OP(insn->code);
1453
1454 /* dst_reg->type == CONST_IMM here, simulate execution of 'add' insn.
1455 * Don't care about overflow or negative values, just add them
1456 */
1457 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K)
1458 dst_reg->imm += insn->imm;
1459 else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X &&
1460 src_reg->type == CONST_IMM)
1461 dst_reg->imm += src_reg->imm;
1462 else
1463 mark_reg_unknown_value(regs, insn->dst_reg);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001464 return 0;
1465}
1466
Josef Bacik48461132016-09-28 10:54:32 -04001467static void check_reg_overflow(struct bpf_reg_state *reg)
1468{
1469 if (reg->max_value > BPF_REGISTER_MAX_RANGE)
1470 reg->max_value = BPF_REGISTER_MAX_RANGE;
1471 if ((s64)reg->min_value < BPF_REGISTER_MIN_RANGE)
1472 reg->min_value = BPF_REGISTER_MIN_RANGE;
1473}
1474
1475static void adjust_reg_min_max_vals(struct bpf_verifier_env *env,
1476 struct bpf_insn *insn)
1477{
1478 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
1479 u64 min_val = BPF_REGISTER_MIN_RANGE, max_val = BPF_REGISTER_MAX_RANGE;
1480 bool min_set = false, max_set = false;
1481 u8 opcode = BPF_OP(insn->code);
1482
1483 dst_reg = &regs[insn->dst_reg];
1484 if (BPF_SRC(insn->code) == BPF_X) {
1485 check_reg_overflow(&regs[insn->src_reg]);
1486 min_val = regs[insn->src_reg].min_value;
1487 max_val = regs[insn->src_reg].max_value;
1488
1489 /* If the source register is a random pointer then the
1490 * min_value/max_value values represent the range of the known
1491 * accesses into that value, not the actual min/max value of the
1492 * register itself. In this case we have to reset the reg range
1493 * values so we know it is not safe to look at.
1494 */
1495 if (regs[insn->src_reg].type != CONST_IMM &&
1496 regs[insn->src_reg].type != UNKNOWN_VALUE) {
1497 min_val = BPF_REGISTER_MIN_RANGE;
1498 max_val = BPF_REGISTER_MAX_RANGE;
1499 }
1500 } else if (insn->imm < BPF_REGISTER_MAX_RANGE &&
1501 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) {
1502 min_val = max_val = insn->imm;
1503 min_set = max_set = true;
1504 }
1505
1506 /* We don't know anything about what was done to this register, mark it
1507 * as unknown.
1508 */
1509 if (min_val == BPF_REGISTER_MIN_RANGE &&
1510 max_val == BPF_REGISTER_MAX_RANGE) {
1511 reset_reg_range_values(regs, insn->dst_reg);
1512 return;
1513 }
1514
1515 switch (opcode) {
1516 case BPF_ADD:
1517 dst_reg->min_value += min_val;
1518 dst_reg->max_value += max_val;
1519 break;
1520 case BPF_SUB:
1521 dst_reg->min_value -= min_val;
1522 dst_reg->max_value -= max_val;
1523 break;
1524 case BPF_MUL:
1525 dst_reg->min_value *= min_val;
1526 dst_reg->max_value *= max_val;
1527 break;
1528 case BPF_AND:
1529 /* & is special since it could end up with 0 bits set. */
1530 dst_reg->min_value &= min_val;
1531 dst_reg->max_value = max_val;
1532 break;
1533 case BPF_LSH:
1534 /* Gotta have special overflow logic here, if we're shifting
1535 * more than MAX_RANGE then just assume we have an invalid
1536 * range.
1537 */
1538 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE))
1539 dst_reg->min_value = BPF_REGISTER_MIN_RANGE;
1540 else
1541 dst_reg->min_value <<= min_val;
1542
1543 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE))
1544 dst_reg->max_value = BPF_REGISTER_MAX_RANGE;
1545 else
1546 dst_reg->max_value <<= max_val;
1547 break;
1548 case BPF_RSH:
1549 dst_reg->min_value >>= min_val;
1550 dst_reg->max_value >>= max_val;
1551 break;
1552 case BPF_MOD:
1553 /* % is special since it is an unsigned modulus, so the floor
1554 * will always be 0.
1555 */
1556 dst_reg->min_value = 0;
1557 dst_reg->max_value = max_val - 1;
1558 break;
1559 default:
1560 reset_reg_range_values(regs, insn->dst_reg);
1561 break;
1562 }
1563
1564 check_reg_overflow(dst_reg);
1565}
1566
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001567/* check validity of 32-bit and 64-bit arithmetic operations */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001568static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001569{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001570 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001571 u8 opcode = BPF_OP(insn->code);
1572 int err;
1573
1574 if (opcode == BPF_END || opcode == BPF_NEG) {
1575 if (opcode == BPF_NEG) {
1576 if (BPF_SRC(insn->code) != 0 ||
1577 insn->src_reg != BPF_REG_0 ||
1578 insn->off != 0 || insn->imm != 0) {
1579 verbose("BPF_NEG uses reserved fields\n");
1580 return -EINVAL;
1581 }
1582 } else {
1583 if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
1584 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
1585 verbose("BPF_END uses reserved fields\n");
1586 return -EINVAL;
1587 }
1588 }
1589
1590 /* check src operand */
1591 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1592 if (err)
1593 return err;
1594
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07001595 if (is_pointer_value(env, insn->dst_reg)) {
1596 verbose("R%d pointer arithmetic prohibited\n",
1597 insn->dst_reg);
1598 return -EACCES;
1599 }
1600
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001601 /* check dest operand */
1602 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1603 if (err)
1604 return err;
1605
1606 } else if (opcode == BPF_MOV) {
1607
1608 if (BPF_SRC(insn->code) == BPF_X) {
1609 if (insn->imm != 0 || insn->off != 0) {
1610 verbose("BPF_MOV uses reserved fields\n");
1611 return -EINVAL;
1612 }
1613
1614 /* check src operand */
1615 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1616 if (err)
1617 return err;
1618 } else {
1619 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1620 verbose("BPF_MOV uses reserved fields\n");
1621 return -EINVAL;
1622 }
1623 }
1624
1625 /* check dest operand */
1626 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
1627 if (err)
1628 return err;
1629
Josef Bacik48461132016-09-28 10:54:32 -04001630 /* we are setting our register to something new, we need to
1631 * reset its range values.
1632 */
1633 reset_reg_range_values(regs, insn->dst_reg);
1634
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001635 if (BPF_SRC(insn->code) == BPF_X) {
1636 if (BPF_CLASS(insn->code) == BPF_ALU64) {
1637 /* case: R1 = R2
1638 * copy register state to dest reg
1639 */
1640 regs[insn->dst_reg] = regs[insn->src_reg];
1641 } else {
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07001642 if (is_pointer_value(env, insn->src_reg)) {
1643 verbose("R%d partial copy of pointer\n",
1644 insn->src_reg);
1645 return -EACCES;
1646 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001647 regs[insn->dst_reg].type = UNKNOWN_VALUE;
1648 regs[insn->dst_reg].map_ptr = NULL;
1649 }
1650 } else {
1651 /* case: R = imm
1652 * remember the value we stored into this reg
1653 */
1654 regs[insn->dst_reg].type = CONST_IMM;
1655 regs[insn->dst_reg].imm = insn->imm;
Josef Bacik48461132016-09-28 10:54:32 -04001656 regs[insn->dst_reg].max_value = insn->imm;
1657 regs[insn->dst_reg].min_value = insn->imm;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001658 }
1659
1660 } else if (opcode > BPF_END) {
1661 verbose("invalid BPF_ALU opcode %x\n", opcode);
1662 return -EINVAL;
1663
1664 } else { /* all other ALU ops: and, sub, xor, add, ... */
1665
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001666 if (BPF_SRC(insn->code) == BPF_X) {
1667 if (insn->imm != 0 || insn->off != 0) {
1668 verbose("BPF_ALU uses reserved fields\n");
1669 return -EINVAL;
1670 }
1671 /* check src1 operand */
1672 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1673 if (err)
1674 return err;
1675 } else {
1676 if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
1677 verbose("BPF_ALU uses reserved fields\n");
1678 return -EINVAL;
1679 }
1680 }
1681
1682 /* check src2 operand */
1683 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1684 if (err)
1685 return err;
1686
1687 if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
1688 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
1689 verbose("div by zero\n");
1690 return -EINVAL;
1691 }
1692
Rabin Vincent229394e2016-01-12 20:17:08 +01001693 if ((opcode == BPF_LSH || opcode == BPF_RSH ||
1694 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
1695 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
1696
1697 if (insn->imm < 0 || insn->imm >= size) {
1698 verbose("invalid shift %d\n", insn->imm);
1699 return -EINVAL;
1700 }
1701 }
1702
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07001703 /* check dest operand */
1704 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
1705 if (err)
1706 return err;
1707
1708 dst_reg = &regs[insn->dst_reg];
1709
Josef Bacik48461132016-09-28 10:54:32 -04001710 /* first we want to adjust our ranges. */
1711 adjust_reg_min_max_vals(env, insn);
1712
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001713 /* pattern match 'bpf_add Rx, imm' instruction */
1714 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07001715 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) {
1716 dst_reg->type = PTR_TO_STACK;
1717 dst_reg->imm = insn->imm;
1718 return 0;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001719 } else if (opcode == BPF_ADD &&
1720 BPF_CLASS(insn->code) == BPF_ALU64 &&
Alexei Starovoitov1b9b69e2016-05-19 18:17:14 -07001721 (dst_reg->type == PTR_TO_PACKET ||
1722 (BPF_SRC(insn->code) == BPF_X &&
1723 regs[insn->src_reg].type == PTR_TO_PACKET))) {
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001724 /* ptr_to_packet += K|X */
1725 return check_packet_ptr_add(env, insn);
1726 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
1727 dst_reg->type == UNKNOWN_VALUE &&
1728 env->allow_ptr_leaks) {
1729 /* unknown += K|X */
1730 return evaluate_reg_alu(env, insn);
1731 } else if (BPF_CLASS(insn->code) == BPF_ALU64 &&
1732 dst_reg->type == CONST_IMM &&
1733 env->allow_ptr_leaks) {
1734 /* reg_imm += K|X */
1735 return evaluate_reg_imm_alu(env, insn);
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07001736 } else if (is_pointer_value(env, insn->dst_reg)) {
1737 verbose("R%d pointer arithmetic prohibited\n",
1738 insn->dst_reg);
1739 return -EACCES;
1740 } else if (BPF_SRC(insn->code) == BPF_X &&
1741 is_pointer_value(env, insn->src_reg)) {
1742 verbose("R%d pointer arithmetic prohibited\n",
1743 insn->src_reg);
1744 return -EACCES;
1745 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001746
Josef Bacik48461132016-09-28 10:54:32 -04001747 /* If we did pointer math on a map value then just set it to our
1748 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or
1749 * loads to this register appropriately, otherwise just mark the
1750 * register as unknown.
1751 */
1752 if (env->allow_ptr_leaks &&
1753 (dst_reg->type == PTR_TO_MAP_VALUE ||
1754 dst_reg->type == PTR_TO_MAP_VALUE_ADJ))
1755 dst_reg->type = PTR_TO_MAP_VALUE_ADJ;
1756 else
1757 mark_reg_unknown_value(regs, insn->dst_reg);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001758 }
1759
1760 return 0;
1761}
1762
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001763static void find_good_pkt_pointers(struct bpf_verifier_state *state,
1764 struct bpf_reg_state *dst_reg)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001765{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001766 struct bpf_reg_state *regs = state->regs, *reg;
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001767 int i;
Daniel Borkmann2d2be8c2016-09-08 01:03:42 +02001768
1769 /* LLVM can generate two kind of checks:
1770 *
1771 * Type 1:
1772 *
1773 * r2 = r3;
1774 * r2 += 8;
1775 * if (r2 > pkt_end) goto <handle exception>
1776 * <access okay>
1777 *
1778 * Where:
1779 * r2 == dst_reg, pkt_end == src_reg
1780 * r2=pkt(id=n,off=8,r=0)
1781 * r3=pkt(id=n,off=0,r=0)
1782 *
1783 * Type 2:
1784 *
1785 * r2 = r3;
1786 * r2 += 8;
1787 * if (pkt_end >= r2) goto <access okay>
1788 * <handle exception>
1789 *
1790 * Where:
1791 * pkt_end == dst_reg, r2 == src_reg
1792 * r2=pkt(id=n,off=8,r=0)
1793 * r3=pkt(id=n,off=0,r=0)
1794 *
1795 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
1796 * so that range of bytes [r3, r3 + 8) is safe to access.
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001797 */
Daniel Borkmann2d2be8c2016-09-08 01:03:42 +02001798
Alexei Starovoitov969bf052016-05-05 19:49:10 -07001799 for (i = 0; i < MAX_BPF_REG; i++)
1800 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id)
1801 regs[i].range = dst_reg->off;
1802
1803 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
1804 if (state->stack_slot_type[i] != STACK_SPILL)
1805 continue;
1806 reg = &state->spilled_regs[i / BPF_REG_SIZE];
1807 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id)
1808 reg->range = dst_reg->off;
1809 }
1810}
1811
Josef Bacik48461132016-09-28 10:54:32 -04001812/* Adjusts the register min/max values in the case that the dst_reg is the
1813 * variable register that we are working on, and src_reg is a constant or we're
1814 * simply doing a BPF_K check.
1815 */
1816static void reg_set_min_max(struct bpf_reg_state *true_reg,
1817 struct bpf_reg_state *false_reg, u64 val,
1818 u8 opcode)
1819{
1820 switch (opcode) {
1821 case BPF_JEQ:
1822 /* If this is false then we know nothing Jon Snow, but if it is
1823 * true then we know for sure.
1824 */
1825 true_reg->max_value = true_reg->min_value = val;
1826 break;
1827 case BPF_JNE:
1828 /* If this is true we know nothing Jon Snow, but if it is false
1829 * we know the value for sure;
1830 */
1831 false_reg->max_value = false_reg->min_value = val;
1832 break;
1833 case BPF_JGT:
1834 /* Unsigned comparison, the minimum value is 0. */
1835 false_reg->min_value = 0;
1836 case BPF_JSGT:
1837 /* If this is false then we know the maximum val is val,
1838 * otherwise we know the min val is val+1.
1839 */
1840 false_reg->max_value = val;
1841 true_reg->min_value = val + 1;
1842 break;
1843 case BPF_JGE:
1844 /* Unsigned comparison, the minimum value is 0. */
1845 false_reg->min_value = 0;
1846 case BPF_JSGE:
1847 /* If this is false then we know the maximum value is val - 1,
1848 * otherwise we know the mimimum value is val.
1849 */
1850 false_reg->max_value = val - 1;
1851 true_reg->min_value = val;
1852 break;
1853 default:
1854 break;
1855 }
1856
1857 check_reg_overflow(false_reg);
1858 check_reg_overflow(true_reg);
1859}
1860
1861/* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg
1862 * is the variable reg.
1863 */
1864static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
1865 struct bpf_reg_state *false_reg, u64 val,
1866 u8 opcode)
1867{
1868 switch (opcode) {
1869 case BPF_JEQ:
1870 /* If this is false then we know nothing Jon Snow, but if it is
1871 * true then we know for sure.
1872 */
1873 true_reg->max_value = true_reg->min_value = val;
1874 break;
1875 case BPF_JNE:
1876 /* If this is true we know nothing Jon Snow, but if it is false
1877 * we know the value for sure;
1878 */
1879 false_reg->max_value = false_reg->min_value = val;
1880 break;
1881 case BPF_JGT:
1882 /* Unsigned comparison, the minimum value is 0. */
1883 true_reg->min_value = 0;
1884 case BPF_JSGT:
1885 /*
1886 * If this is false, then the val is <= the register, if it is
1887 * true the register <= to the val.
1888 */
1889 false_reg->min_value = val;
1890 true_reg->max_value = val - 1;
1891 break;
1892 case BPF_JGE:
1893 /* Unsigned comparison, the minimum value is 0. */
1894 true_reg->min_value = 0;
1895 case BPF_JSGE:
1896 /* If this is false then constant < register, if it is true then
1897 * the register < constant.
1898 */
1899 false_reg->min_value = val + 1;
1900 true_reg->max_value = val;
1901 break;
1902 default:
1903 break;
1904 }
1905
1906 check_reg_overflow(false_reg);
1907 check_reg_overflow(true_reg);
1908}
1909
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001910static int check_cond_jmp_op(struct bpf_verifier_env *env,
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001911 struct bpf_insn *insn, int *insn_idx)
1912{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001913 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
1914 struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001915 u8 opcode = BPF_OP(insn->code);
1916 int err;
1917
1918 if (opcode > BPF_EXIT) {
1919 verbose("invalid BPF_JMP opcode %x\n", opcode);
1920 return -EINVAL;
1921 }
1922
1923 if (BPF_SRC(insn->code) == BPF_X) {
1924 if (insn->imm != 0) {
1925 verbose("BPF_JMP uses reserved fields\n");
1926 return -EINVAL;
1927 }
1928
1929 /* check src1 operand */
1930 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
1931 if (err)
1932 return err;
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07001933
1934 if (is_pointer_value(env, insn->src_reg)) {
1935 verbose("R%d pointer comparison prohibited\n",
1936 insn->src_reg);
1937 return -EACCES;
1938 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001939 } else {
1940 if (insn->src_reg != BPF_REG_0) {
1941 verbose("BPF_JMP uses reserved fields\n");
1942 return -EINVAL;
1943 }
1944 }
1945
1946 /* check src2 operand */
1947 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
1948 if (err)
1949 return err;
1950
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07001951 dst_reg = &regs[insn->dst_reg];
1952
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001953 /* detect if R == 0 where R was initialized to zero earlier */
1954 if (BPF_SRC(insn->code) == BPF_K &&
1955 (opcode == BPF_JEQ || opcode == BPF_JNE) &&
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07001956 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001957 if (opcode == BPF_JEQ) {
1958 /* if (imm == imm) goto pc+off;
1959 * only follow the goto, ignore fall-through
1960 */
1961 *insn_idx += insn->off;
1962 return 0;
1963 } else {
1964 /* if (imm != imm) goto pc+off;
1965 * only follow fall-through branch, since
1966 * that's where the program will go
1967 */
1968 return 0;
1969 }
1970 }
1971
1972 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
1973 if (!other_branch)
1974 return -EFAULT;
1975
Josef Bacik48461132016-09-28 10:54:32 -04001976 /* detect if we are comparing against a constant value so we can adjust
1977 * our min/max values for our dst register.
1978 */
1979 if (BPF_SRC(insn->code) == BPF_X) {
1980 if (regs[insn->src_reg].type == CONST_IMM)
1981 reg_set_min_max(&other_branch->regs[insn->dst_reg],
1982 dst_reg, regs[insn->src_reg].imm,
1983 opcode);
1984 else if (dst_reg->type == CONST_IMM)
1985 reg_set_min_max_inv(&other_branch->regs[insn->src_reg],
1986 &regs[insn->src_reg], dst_reg->imm,
1987 opcode);
1988 } else {
1989 reg_set_min_max(&other_branch->regs[insn->dst_reg],
1990 dst_reg, insn->imm, opcode);
1991 }
1992
Jakub Kicinski58e2af82016-09-21 11:43:57 +01001993 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001994 if (BPF_SRC(insn->code) == BPF_K &&
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07001995 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
1996 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07001997 if (opcode == BPF_JEQ) {
1998 /* next fallthrough insn can access memory via
1999 * this register
2000 */
2001 regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
2002 /* branch targer cannot access it, since reg == 0 */
Alexei Starovoitov735b4332016-05-05 19:49:11 -07002003 mark_reg_unknown_value(other_branch->regs,
2004 insn->dst_reg);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002005 } else {
2006 other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
Alexei Starovoitov735b4332016-05-05 19:49:11 -07002007 mark_reg_unknown_value(regs, insn->dst_reg);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002008 }
Alexei Starovoitov969bf052016-05-05 19:49:10 -07002009 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
2010 dst_reg->type == PTR_TO_PACKET &&
2011 regs[insn->src_reg].type == PTR_TO_PACKET_END) {
Daniel Borkmann2d2be8c2016-09-08 01:03:42 +02002012 find_good_pkt_pointers(this_branch, dst_reg);
2013 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
2014 dst_reg->type == PTR_TO_PACKET_END &&
2015 regs[insn->src_reg].type == PTR_TO_PACKET) {
2016 find_good_pkt_pointers(other_branch, &regs[insn->src_reg]);
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07002017 } else if (is_pointer_value(env, insn->dst_reg)) {
2018 verbose("R%d pointer comparison prohibited\n", insn->dst_reg);
2019 return -EACCES;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002020 }
2021 if (log_level)
Daniel Borkmann2d2be8c2016-09-08 01:03:42 +02002022 print_verifier_state(this_branch);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002023 return 0;
2024}
2025
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002026/* return the map pointer stored inside BPF_LD_IMM64 instruction */
2027static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
2028{
2029 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
2030
2031 return (struct bpf_map *) (unsigned long) imm64;
2032}
2033
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002034/* verify BPF_LD_IMM64 instruction */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002035static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002036{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002037 struct bpf_reg_state *regs = env->cur_state.regs;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002038 int err;
2039
2040 if (BPF_SIZE(insn->code) != BPF_DW) {
2041 verbose("invalid BPF_LD_IMM insn\n");
2042 return -EINVAL;
2043 }
2044 if (insn->off != 0) {
2045 verbose("BPF_LD_IMM64 uses reserved fields\n");
2046 return -EINVAL;
2047 }
2048
2049 err = check_reg_arg(regs, insn->dst_reg, DST_OP);
2050 if (err)
2051 return err;
2052
Jakub Kicinski6b173872016-09-21 11:43:59 +01002053 if (insn->src_reg == 0) {
2054 /* generic move 64-bit immediate into a register,
2055 * only analyzer needs to collect the ld_imm value.
2056 */
2057 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
2058
2059 if (!env->analyzer_ops)
2060 return 0;
2061
2062 regs[insn->dst_reg].type = CONST_IMM;
2063 regs[insn->dst_reg].imm = imm;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002064 return 0;
Jakub Kicinski6b173872016-09-21 11:43:59 +01002065 }
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002066
2067 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
2068 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
2069
2070 regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
2071 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
2072 return 0;
2073}
2074
Daniel Borkmann96be4322015-03-01 12:31:46 +01002075static bool may_access_skb(enum bpf_prog_type type)
2076{
2077 switch (type) {
2078 case BPF_PROG_TYPE_SOCKET_FILTER:
2079 case BPF_PROG_TYPE_SCHED_CLS:
Daniel Borkmann94caee82015-03-20 15:11:11 +01002080 case BPF_PROG_TYPE_SCHED_ACT:
Daniel Borkmann96be4322015-03-01 12:31:46 +01002081 return true;
2082 default:
2083 return false;
2084 }
2085}
2086
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002087/* verify safety of LD_ABS|LD_IND instructions:
2088 * - they can only appear in the programs where ctx == skb
2089 * - since they are wrappers of function calls, they scratch R1-R5 registers,
2090 * preserve R6-R9, and store return value into R0
2091 *
2092 * Implicit input:
2093 * ctx == skb == R6 == CTX
2094 *
2095 * Explicit input:
2096 * SRC == any register
2097 * IMM == 32-bit immediate
2098 *
2099 * Output:
2100 * R0 - 8/16/32-bit skb data converted to cpu endianness
2101 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002102static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002103{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002104 struct bpf_reg_state *regs = env->cur_state.regs;
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002105 u8 mode = BPF_MODE(insn->code);
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002106 struct bpf_reg_state *reg;
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002107 int i, err;
2108
Daniel Borkmann24701ec2015-03-01 12:31:47 +01002109 if (!may_access_skb(env->prog->type)) {
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002110 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002111 return -EINVAL;
2112 }
2113
2114 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
Alexei Starovoitovd82bccc2016-04-12 10:26:19 -07002115 BPF_SIZE(insn->code) == BPF_DW ||
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002116 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002117 verbose("BPF_LD_[ABS|IND] uses reserved fields\n");
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002118 return -EINVAL;
2119 }
2120
2121 /* check whether implicit source operand (register R6) is readable */
2122 err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
2123 if (err)
2124 return err;
2125
2126 if (regs[BPF_REG_6].type != PTR_TO_CTX) {
2127 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
2128 return -EINVAL;
2129 }
2130
2131 if (mode == BPF_IND) {
2132 /* check explicit source operand */
2133 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2134 if (err)
2135 return err;
2136 }
2137
2138 /* reset caller saved regs to unreadable */
2139 for (i = 0; i < CALLER_SAVED_REGS; i++) {
2140 reg = regs + caller_saved[i];
2141 reg->type = NOT_INIT;
2142 reg->imm = 0;
2143 }
2144
2145 /* mark destination R0 register as readable, since it contains
2146 * the value fetched from the packet
2147 */
2148 regs[BPF_REG_0].type = UNKNOWN_VALUE;
2149 return 0;
2150}
2151
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002152/* non-recursive DFS pseudo code
2153 * 1 procedure DFS-iterative(G,v):
2154 * 2 label v as discovered
2155 * 3 let S be a stack
2156 * 4 S.push(v)
2157 * 5 while S is not empty
2158 * 6 t <- S.pop()
2159 * 7 if t is what we're looking for:
2160 * 8 return t
2161 * 9 for all edges e in G.adjacentEdges(t) do
2162 * 10 if edge e is already labelled
2163 * 11 continue with the next edge
2164 * 12 w <- G.adjacentVertex(t,e)
2165 * 13 if vertex w is not discovered and not explored
2166 * 14 label e as tree-edge
2167 * 15 label w as discovered
2168 * 16 S.push(w)
2169 * 17 continue at 5
2170 * 18 else if vertex w is discovered
2171 * 19 label e as back-edge
2172 * 20 else
2173 * 21 // vertex w is explored
2174 * 22 label e as forward- or cross-edge
2175 * 23 label t as explored
2176 * 24 S.pop()
2177 *
2178 * convention:
2179 * 0x10 - discovered
2180 * 0x11 - discovered and fall-through edge labelled
2181 * 0x12 - discovered and fall-through and branch edges labelled
2182 * 0x20 - explored
2183 */
2184
2185enum {
2186 DISCOVERED = 0x10,
2187 EXPLORED = 0x20,
2188 FALLTHROUGH = 1,
2189 BRANCH = 2,
2190};
2191
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002192#define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002193
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002194static int *insn_stack; /* stack of insns to process */
2195static int cur_stack; /* current stack index */
2196static int *insn_state;
2197
2198/* t, w, e - match pseudo-code above:
2199 * t - index of current instruction
2200 * w - next instruction
2201 * e - edge
2202 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002203static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002204{
2205 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
2206 return 0;
2207
2208 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
2209 return 0;
2210
2211 if (w < 0 || w >= env->prog->len) {
2212 verbose("jump out of range from insn %d to %d\n", t, w);
2213 return -EINVAL;
2214 }
2215
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002216 if (e == BRANCH)
2217 /* mark branch target for state pruning */
2218 env->explored_states[w] = STATE_LIST_MARK;
2219
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002220 if (insn_state[w] == 0) {
2221 /* tree-edge */
2222 insn_state[t] = DISCOVERED | e;
2223 insn_state[w] = DISCOVERED;
2224 if (cur_stack >= env->prog->len)
2225 return -E2BIG;
2226 insn_stack[cur_stack++] = w;
2227 return 1;
2228 } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
2229 verbose("back-edge from insn %d to %d\n", t, w);
2230 return -EINVAL;
2231 } else if (insn_state[w] == EXPLORED) {
2232 /* forward- or cross-edge */
2233 insn_state[t] = DISCOVERED | e;
2234 } else {
2235 verbose("insn state internal bug\n");
2236 return -EFAULT;
2237 }
2238 return 0;
2239}
2240
2241/* non-recursive depth-first-search to detect loops in BPF program
2242 * loop == back-edge in directed graph
2243 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002244static int check_cfg(struct bpf_verifier_env *env)
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002245{
2246 struct bpf_insn *insns = env->prog->insnsi;
2247 int insn_cnt = env->prog->len;
2248 int ret = 0;
2249 int i, t;
2250
2251 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2252 if (!insn_state)
2253 return -ENOMEM;
2254
2255 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
2256 if (!insn_stack) {
2257 kfree(insn_state);
2258 return -ENOMEM;
2259 }
2260
2261 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
2262 insn_stack[0] = 0; /* 0 is the first instruction */
2263 cur_stack = 1;
2264
2265peek_stack:
2266 if (cur_stack == 0)
2267 goto check_state;
2268 t = insn_stack[cur_stack - 1];
2269
2270 if (BPF_CLASS(insns[t].code) == BPF_JMP) {
2271 u8 opcode = BPF_OP(insns[t].code);
2272
2273 if (opcode == BPF_EXIT) {
2274 goto mark_explored;
2275 } else if (opcode == BPF_CALL) {
2276 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2277 if (ret == 1)
2278 goto peek_stack;
2279 else if (ret < 0)
2280 goto err_free;
Daniel Borkmann07016152016-04-05 22:33:17 +02002281 if (t + 1 < insn_cnt)
2282 env->explored_states[t + 1] = STATE_LIST_MARK;
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002283 } else if (opcode == BPF_JA) {
2284 if (BPF_SRC(insns[t].code) != BPF_K) {
2285 ret = -EINVAL;
2286 goto err_free;
2287 }
2288 /* unconditional jump with single edge */
2289 ret = push_insn(t, t + insns[t].off + 1,
2290 FALLTHROUGH, env);
2291 if (ret == 1)
2292 goto peek_stack;
2293 else if (ret < 0)
2294 goto err_free;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002295 /* tell verifier to check for equivalent states
2296 * after every call and jump
2297 */
Alexei Starovoitovc3de6312015-04-14 15:57:13 -07002298 if (t + 1 < insn_cnt)
2299 env->explored_states[t + 1] = STATE_LIST_MARK;
Alexei Starovoitov475fb782014-09-26 00:17:05 -07002300 } else {
2301 /* conditional jump with two edges */
2302 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2303 if (ret == 1)
2304 goto peek_stack;
2305 else if (ret < 0)
2306 goto err_free;
2307
2308 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
2309 if (ret == 1)
2310 goto peek_stack;
2311 else if (ret < 0)
2312 goto err_free;
2313 }
2314 } else {
2315 /* all other non-branch instructions with single
2316 * fall-through edge
2317 */
2318 ret = push_insn(t, t + 1, FALLTHROUGH, env);
2319 if (ret == 1)
2320 goto peek_stack;
2321 else if (ret < 0)
2322 goto err_free;
2323 }
2324
2325mark_explored:
2326 insn_state[t] = EXPLORED;
2327 if (cur_stack-- <= 0) {
2328 verbose("pop stack internal bug\n");
2329 ret = -EFAULT;
2330 goto err_free;
2331 }
2332 goto peek_stack;
2333
2334check_state:
2335 for (i = 0; i < insn_cnt; i++) {
2336 if (insn_state[i] != EXPLORED) {
2337 verbose("unreachable insn %d\n", i);
2338 ret = -EINVAL;
2339 goto err_free;
2340 }
2341 }
2342 ret = 0; /* cfg looks good */
2343
2344err_free:
2345 kfree(insn_state);
2346 kfree(insn_stack);
2347 return ret;
2348}
2349
Alexei Starovoitov969bf052016-05-05 19:49:10 -07002350/* the following conditions reduce the number of explored insns
2351 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet
2352 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002353static bool compare_ptrs_to_packet(struct bpf_reg_state *old,
2354 struct bpf_reg_state *cur)
Alexei Starovoitov969bf052016-05-05 19:49:10 -07002355{
2356 if (old->id != cur->id)
2357 return false;
2358
2359 /* old ptr_to_packet is more conservative, since it allows smaller
2360 * range. Ex:
2361 * old(off=0,r=10) is equal to cur(off=0,r=20), because
2362 * old(off=0,r=10) means that with range=10 the verifier proceeded
2363 * further and found no issues with the program. Now we're in the same
2364 * spot with cur(off=0,r=20), so we're safe too, since anything further
2365 * will only be looking at most 10 bytes after this pointer.
2366 */
2367 if (old->off == cur->off && old->range < cur->range)
2368 return true;
2369
2370 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0)
2371 * since both cannot be used for packet access and safe(old)
2372 * pointer has smaller off that could be used for further
2373 * 'if (ptr > data_end)' check
2374 * Ex:
2375 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean
2376 * that we cannot access the packet.
2377 * The safe range is:
2378 * [ptr, ptr + range - off)
2379 * so whenever off >=range, it means no safe bytes from this pointer.
2380 * When comparing old->off <= cur->off, it means that older code
2381 * went with smaller offset and that offset was later
2382 * used to figure out the safe range after 'if (ptr > data_end)' check
2383 * Say, 'old' state was explored like:
2384 * ... R3(off=0, r=0)
2385 * R4 = R3 + 20
2386 * ... now R4(off=20,r=0) <-- here
2387 * if (R4 > data_end)
2388 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access.
2389 * ... the code further went all the way to bpf_exit.
2390 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0).
2391 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier
2392 * goes further, such cur_R4 will give larger safe packet range after
2393 * 'if (R4 > data_end)' and all further insn were already good with r=20,
2394 * so they will be good with r=30 and we can prune the search.
2395 */
2396 if (old->off <= cur->off &&
2397 old->off >= old->range && cur->off >= cur->range)
2398 return true;
2399
2400 return false;
2401}
2402
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002403/* compare two verifier states
2404 *
2405 * all states stored in state_list are known to be valid, since
2406 * verifier reached 'bpf_exit' instruction through them
2407 *
2408 * this function is called when verifier exploring different branches of
2409 * execution popped from the state stack. If it sees an old state that has
2410 * more strict register state and more strict stack state then this execution
2411 * branch doesn't need to be explored further, since verifier already
2412 * concluded that more strict state leads to valid finish.
2413 *
2414 * Therefore two states are equivalent if register state is more conservative
2415 * and explored stack state is more conservative than the current one.
2416 * Example:
2417 * explored current
2418 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
2419 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
2420 *
2421 * In other words if current stack state (one being explored) has more
2422 * valid slots than old one that already passed validation, it means
2423 * the verifier can stop exploring and conclude that current state is valid too
2424 *
2425 * Similarly with registers. If explored state has register type as invalid
2426 * whereas register type in current state is meaningful, it means that
2427 * the current state will reach 'bpf_exit' instruction safely
2428 */
Josef Bacik48461132016-09-28 10:54:32 -04002429static bool states_equal(struct bpf_verifier_env *env,
2430 struct bpf_verifier_state *old,
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002431 struct bpf_verifier_state *cur)
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002432{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002433 struct bpf_reg_state *rold, *rcur;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002434 int i;
2435
2436 for (i = 0; i < MAX_BPF_REG; i++) {
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002437 rold = &old->regs[i];
2438 rcur = &cur->regs[i];
2439
2440 if (memcmp(rold, rcur, sizeof(*rold)) == 0)
2441 continue;
2442
Josef Bacik48461132016-09-28 10:54:32 -04002443 /* If the ranges were not the same, but everything else was and
2444 * we didn't do a variable access into a map then we are a-ok.
2445 */
2446 if (!env->varlen_map_value_access &&
2447 rold->type == rcur->type && rold->imm == rcur->imm)
2448 continue;
2449
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002450 if (rold->type == NOT_INIT ||
2451 (rold->type == UNKNOWN_VALUE && rcur->type != NOT_INIT))
2452 continue;
2453
Alexei Starovoitov969bf052016-05-05 19:49:10 -07002454 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET &&
2455 compare_ptrs_to_packet(rold, rcur))
2456 continue;
2457
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002458 return false;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002459 }
2460
2461 for (i = 0; i < MAX_BPF_STACK; i++) {
Alexei Starovoitov9c3997602014-10-28 15:11:41 -07002462 if (old->stack_slot_type[i] == STACK_INVALID)
2463 continue;
2464 if (old->stack_slot_type[i] != cur->stack_slot_type[i])
2465 /* Ex: old explored (safe) state has STACK_SPILL in
2466 * this stack slot, but current has has STACK_MISC ->
2467 * this verifier states are not equivalent,
2468 * return false to continue verification of this path
2469 */
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002470 return false;
Alexei Starovoitov9c3997602014-10-28 15:11:41 -07002471 if (i % BPF_REG_SIZE)
2472 continue;
2473 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
2474 &cur->spilled_regs[i / BPF_REG_SIZE],
2475 sizeof(old->spilled_regs[0])))
2476 /* when explored and current stack slot types are
2477 * the same, check that stored pointers types
2478 * are the same as well.
2479 * Ex: explored safe path could have stored
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002480 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8}
Alexei Starovoitov9c3997602014-10-28 15:11:41 -07002481 * but current path has stored:
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002482 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16}
Alexei Starovoitov9c3997602014-10-28 15:11:41 -07002483 * such verifier states are not equivalent.
2484 * return false to continue verification of this path
2485 */
2486 return false;
2487 else
2488 continue;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002489 }
2490 return true;
2491}
2492
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002493static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002494{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002495 struct bpf_verifier_state_list *new_sl;
2496 struct bpf_verifier_state_list *sl;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002497
2498 sl = env->explored_states[insn_idx];
2499 if (!sl)
2500 /* this 'insn_idx' instruction wasn't marked, so we will not
2501 * be doing state search here
2502 */
2503 return 0;
2504
2505 while (sl != STATE_LIST_MARK) {
Josef Bacik48461132016-09-28 10:54:32 -04002506 if (states_equal(env, &sl->state, &env->cur_state))
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002507 /* reached equivalent register/stack state,
2508 * prune the search
2509 */
2510 return 1;
2511 sl = sl->next;
2512 }
2513
2514 /* there were no equivalent states, remember current one.
2515 * technically the current state is not proven to be safe yet,
2516 * but it will either reach bpf_exit (which means it's safe) or
2517 * it will be rejected. Since there are no loops, we won't be
2518 * seeing this 'insn_idx' instruction again on the way to bpf_exit
2519 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002520 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002521 if (!new_sl)
2522 return -ENOMEM;
2523
2524 /* add new state to the head of linked list */
2525 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
2526 new_sl->next = env->explored_states[insn_idx];
2527 env->explored_states[insn_idx] = new_sl;
2528 return 0;
2529}
2530
Jakub Kicinski13a27df2016-09-21 11:43:58 +01002531static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
2532 int insn_idx, int prev_insn_idx)
2533{
2534 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
2535 return 0;
2536
2537 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
2538}
2539
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002540static int do_check(struct bpf_verifier_env *env)
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002541{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002542 struct bpf_verifier_state *state = &env->cur_state;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002543 struct bpf_insn *insns = env->prog->insnsi;
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002544 struct bpf_reg_state *regs = state->regs;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002545 int insn_cnt = env->prog->len;
2546 int insn_idx, prev_insn_idx = 0;
2547 int insn_processed = 0;
2548 bool do_print_state = false;
2549
2550 init_reg_state(regs);
2551 insn_idx = 0;
Josef Bacik48461132016-09-28 10:54:32 -04002552 env->varlen_map_value_access = false;
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002553 for (;;) {
2554 struct bpf_insn *insn;
2555 u8 class;
2556 int err;
2557
2558 if (insn_idx >= insn_cnt) {
2559 verbose("invalid insn idx %d insn_cnt %d\n",
2560 insn_idx, insn_cnt);
2561 return -EFAULT;
2562 }
2563
2564 insn = &insns[insn_idx];
2565 class = BPF_CLASS(insn->code);
2566
Daniel Borkmann07016152016-04-05 22:33:17 +02002567 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002568 verbose("BPF program is too large. Proccessed %d insn\n",
2569 insn_processed);
2570 return -E2BIG;
2571 }
2572
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002573 err = is_state_visited(env, insn_idx);
2574 if (err < 0)
2575 return err;
2576 if (err == 1) {
2577 /* found equivalent state, can prune the search */
2578 if (log_level) {
2579 if (do_print_state)
2580 verbose("\nfrom %d to %d: safe\n",
2581 prev_insn_idx, insn_idx);
2582 else
2583 verbose("%d: safe\n", insn_idx);
2584 }
2585 goto process_bpf_exit;
2586 }
2587
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002588 if (log_level && do_print_state) {
2589 verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002590 print_verifier_state(&env->cur_state);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002591 do_print_state = false;
2592 }
2593
2594 if (log_level) {
2595 verbose("%d: ", insn_idx);
2596 print_bpf_insn(insn);
2597 }
2598
Jakub Kicinski13a27df2016-09-21 11:43:58 +01002599 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
2600 if (err)
2601 return err;
2602
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002603 if (class == BPF_ALU || class == BPF_ALU64) {
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07002604 err = check_alu_op(env, insn);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002605 if (err)
2606 return err;
2607
2608 } else if (class == BPF_LDX) {
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002609 enum bpf_reg_type *prev_src_type, src_reg_type;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002610
2611 /* check for reserved fields is already done */
2612
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002613 /* check src operand */
2614 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2615 if (err)
2616 return err;
2617
2618 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
2619 if (err)
2620 return err;
2621
Alexei Starovoitov725f9dc2015-04-15 16:19:33 -07002622 src_reg_type = regs[insn->src_reg].type;
2623
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002624 /* check that memory (src_reg + off) is readable,
2625 * the state of dst_reg will be updated by this func
2626 */
2627 err = check_mem_access(env, insn->src_reg, insn->off,
2628 BPF_SIZE(insn->code), BPF_READ,
2629 insn->dst_reg);
2630 if (err)
2631 return err;
2632
Josef Bacik48461132016-09-28 10:54:32 -04002633 reset_reg_range_values(regs, insn->dst_reg);
Alexei Starovoitovea2e7ce2016-09-01 18:37:21 -07002634 if (BPF_SIZE(insn->code) != BPF_W &&
2635 BPF_SIZE(insn->code) != BPF_DW) {
Alexei Starovoitov725f9dc2015-04-15 16:19:33 -07002636 insn_idx++;
2637 continue;
2638 }
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002639
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002640 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type;
2641
2642 if (*prev_src_type == NOT_INIT) {
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002643 /* saw a valid insn
2644 * dst_reg = *(u32 *)(src_reg + off)
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002645 * save type to validate intersecting paths
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002646 */
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002647 *prev_src_type = src_reg_type;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002648
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002649 } else if (src_reg_type != *prev_src_type &&
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002650 (src_reg_type == PTR_TO_CTX ||
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002651 *prev_src_type == PTR_TO_CTX)) {
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002652 /* ABuser program is trying to use the same insn
2653 * dst_reg = *(u32*) (src_reg + off)
2654 * with different pointer types:
2655 * src_reg == ctx in one branch and
2656 * src_reg == stack|map in some other branch.
2657 * Reject it.
2658 */
2659 verbose("same insn cannot be used with different pointers\n");
2660 return -EINVAL;
2661 }
2662
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002663 } else if (class == BPF_STX) {
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002664 enum bpf_reg_type *prev_dst_type, dst_reg_type;
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002665
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002666 if (BPF_MODE(insn->code) == BPF_XADD) {
2667 err = check_xadd(env, insn);
2668 if (err)
2669 return err;
2670 insn_idx++;
2671 continue;
2672 }
2673
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002674 /* check src1 operand */
2675 err = check_reg_arg(regs, insn->src_reg, SRC_OP);
2676 if (err)
2677 return err;
2678 /* check src2 operand */
2679 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2680 if (err)
2681 return err;
2682
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002683 dst_reg_type = regs[insn->dst_reg].type;
2684
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002685 /* check that memory (dst_reg + off) is writeable */
2686 err = check_mem_access(env, insn->dst_reg, insn->off,
2687 BPF_SIZE(insn->code), BPF_WRITE,
2688 insn->src_reg);
2689 if (err)
2690 return err;
2691
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002692 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type;
2693
2694 if (*prev_dst_type == NOT_INIT) {
2695 *prev_dst_type = dst_reg_type;
2696 } else if (dst_reg_type != *prev_dst_type &&
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002697 (dst_reg_type == PTR_TO_CTX ||
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002698 *prev_dst_type == PTR_TO_CTX)) {
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002699 verbose("same insn cannot be used with different pointers\n");
2700 return -EINVAL;
2701 }
2702
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002703 } else if (class == BPF_ST) {
2704 if (BPF_MODE(insn->code) != BPF_MEM ||
2705 insn->src_reg != BPF_REG_0) {
2706 verbose("BPF_ST uses reserved fields\n");
2707 return -EINVAL;
2708 }
2709 /* check src operand */
2710 err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
2711 if (err)
2712 return err;
2713
2714 /* check that memory (dst_reg + off) is writeable */
2715 err = check_mem_access(env, insn->dst_reg, insn->off,
2716 BPF_SIZE(insn->code), BPF_WRITE,
2717 -1);
2718 if (err)
2719 return err;
2720
2721 } else if (class == BPF_JMP) {
2722 u8 opcode = BPF_OP(insn->code);
2723
2724 if (opcode == BPF_CALL) {
2725 if (BPF_SRC(insn->code) != BPF_K ||
2726 insn->off != 0 ||
2727 insn->src_reg != BPF_REG_0 ||
2728 insn->dst_reg != BPF_REG_0) {
2729 verbose("BPF_CALL uses reserved fields\n");
2730 return -EINVAL;
2731 }
2732
2733 err = check_call(env, insn->imm);
2734 if (err)
2735 return err;
2736
2737 } else if (opcode == BPF_JA) {
2738 if (BPF_SRC(insn->code) != BPF_K ||
2739 insn->imm != 0 ||
2740 insn->src_reg != BPF_REG_0 ||
2741 insn->dst_reg != BPF_REG_0) {
2742 verbose("BPF_JA uses reserved fields\n");
2743 return -EINVAL;
2744 }
2745
2746 insn_idx += insn->off + 1;
2747 continue;
2748
2749 } else if (opcode == BPF_EXIT) {
2750 if (BPF_SRC(insn->code) != BPF_K ||
2751 insn->imm != 0 ||
2752 insn->src_reg != BPF_REG_0 ||
2753 insn->dst_reg != BPF_REG_0) {
2754 verbose("BPF_EXIT uses reserved fields\n");
2755 return -EINVAL;
2756 }
2757
2758 /* eBPF calling convetion is such that R0 is used
2759 * to return the value from eBPF program.
2760 * Make sure that it's readable at this time
2761 * of bpf_exit, which means that program wrote
2762 * something into it earlier
2763 */
2764 err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
2765 if (err)
2766 return err;
2767
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07002768 if (is_pointer_value(env, BPF_REG_0)) {
2769 verbose("R0 leaks addr as return value\n");
2770 return -EACCES;
2771 }
2772
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07002773process_bpf_exit:
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002774 insn_idx = pop_stack(env, &prev_insn_idx);
2775 if (insn_idx < 0) {
2776 break;
2777 } else {
2778 do_print_state = true;
2779 continue;
2780 }
2781 } else {
2782 err = check_cond_jmp_op(env, insn, &insn_idx);
2783 if (err)
2784 return err;
2785 }
2786 } else if (class == BPF_LD) {
2787 u8 mode = BPF_MODE(insn->code);
2788
2789 if (mode == BPF_ABS || mode == BPF_IND) {
Alexei Starovoitovddd872b2014-12-01 15:06:34 -08002790 err = check_ld_abs(env, insn);
2791 if (err)
2792 return err;
2793
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002794 } else if (mode == BPF_IMM) {
2795 err = check_ld_imm(env, insn);
2796 if (err)
2797 return err;
2798
2799 insn_idx++;
2800 } else {
2801 verbose("invalid BPF_LD mode\n");
2802 return -EINVAL;
2803 }
Josef Bacik48461132016-09-28 10:54:32 -04002804 reset_reg_range_values(regs, insn->dst_reg);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002805 } else {
2806 verbose("unknown insn class %d\n", class);
2807 return -EINVAL;
2808 }
2809
2810 insn_idx++;
2811 }
2812
Alexei Starovoitov1a0dc1a2016-05-05 19:49:09 -07002813 verbose("processed %d insns\n", insn_processed);
Alexei Starovoitov17a52672014-09-26 00:17:06 -07002814 return 0;
2815}
2816
Alexei Starovoitovfdc15d32016-09-01 18:37:23 -07002817static int check_map_prog_compatibility(struct bpf_map *map,
2818 struct bpf_prog *prog)
2819
2820{
2821 if (prog->type == BPF_PROG_TYPE_PERF_EVENT &&
2822 (map->map_type == BPF_MAP_TYPE_HASH ||
2823 map->map_type == BPF_MAP_TYPE_PERCPU_HASH) &&
2824 (map->map_flags & BPF_F_NO_PREALLOC)) {
2825 verbose("perf_event programs can only use preallocated hash map\n");
2826 return -EINVAL;
2827 }
2828 return 0;
2829}
2830
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002831/* look for pseudo eBPF instructions that access map FDs and
2832 * replace them with actual map pointers
2833 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002834static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002835{
2836 struct bpf_insn *insn = env->prog->insnsi;
2837 int insn_cnt = env->prog->len;
Alexei Starovoitovfdc15d32016-09-01 18:37:23 -07002838 int i, j, err;
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002839
2840 for (i = 0; i < insn_cnt; i++, insn++) {
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002841 if (BPF_CLASS(insn->code) == BPF_LDX &&
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002842 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002843 verbose("BPF_LDX uses reserved fields\n");
2844 return -EINVAL;
2845 }
2846
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002847 if (BPF_CLASS(insn->code) == BPF_STX &&
2848 ((BPF_MODE(insn->code) != BPF_MEM &&
2849 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
2850 verbose("BPF_STX uses reserved fields\n");
2851 return -EINVAL;
2852 }
2853
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002854 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
2855 struct bpf_map *map;
2856 struct fd f;
2857
2858 if (i == insn_cnt - 1 || insn[1].code != 0 ||
2859 insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
2860 insn[1].off != 0) {
2861 verbose("invalid bpf_ld_imm64 insn\n");
2862 return -EINVAL;
2863 }
2864
2865 if (insn->src_reg == 0)
2866 /* valid generic load 64-bit imm */
2867 goto next_insn;
2868
2869 if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
2870 verbose("unrecognized bpf_ld_imm64 insn\n");
2871 return -EINVAL;
2872 }
2873
2874 f = fdget(insn->imm);
Daniel Borkmannc2101292015-10-29 14:58:07 +01002875 map = __bpf_map_get(f);
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002876 if (IS_ERR(map)) {
2877 verbose("fd %d is not pointing to valid bpf_map\n",
2878 insn->imm);
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002879 return PTR_ERR(map);
2880 }
2881
Alexei Starovoitovfdc15d32016-09-01 18:37:23 -07002882 err = check_map_prog_compatibility(map, env->prog);
2883 if (err) {
2884 fdput(f);
2885 return err;
2886 }
2887
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002888 /* store map pointer inside BPF_LD_IMM64 instruction */
2889 insn[0].imm = (u32) (unsigned long) map;
2890 insn[1].imm = ((u64) (unsigned long) map) >> 32;
2891
2892 /* check whether we recorded this map already */
2893 for (j = 0; j < env->used_map_cnt; j++)
2894 if (env->used_maps[j] == map) {
2895 fdput(f);
2896 goto next_insn;
2897 }
2898
2899 if (env->used_map_cnt >= MAX_USED_MAPS) {
2900 fdput(f);
2901 return -E2BIG;
2902 }
2903
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002904 /* hold the map. If the program is rejected by verifier,
2905 * the map will be released by release_maps() or it
2906 * will be used by the valid program until it's unloaded
2907 * and all maps are released in free_bpf_prog_info()
2908 */
Alexei Starovoitov92117d82016-04-27 18:56:20 -07002909 map = bpf_map_inc(map, false);
2910 if (IS_ERR(map)) {
2911 fdput(f);
2912 return PTR_ERR(map);
2913 }
2914 env->used_maps[env->used_map_cnt++] = map;
2915
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002916 fdput(f);
2917next_insn:
2918 insn++;
2919 i++;
2920 }
2921 }
2922
2923 /* now all pseudo BPF_LD_IMM64 instructions load valid
2924 * 'struct bpf_map *' into a register instead of user map_fd.
2925 * These pointers will be used later by verifier to validate map access.
2926 */
2927 return 0;
2928}
2929
2930/* drop refcnt of maps used by the rejected program */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002931static void release_maps(struct bpf_verifier_env *env)
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002932{
2933 int i;
2934
2935 for (i = 0; i < env->used_map_cnt; i++)
2936 bpf_map_put(env->used_maps[i]);
2937}
2938
2939/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002940static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
Alexei Starovoitov0246e642014-09-26 00:17:04 -07002941{
2942 struct bpf_insn *insn = env->prog->insnsi;
2943 int insn_cnt = env->prog->len;
2944 int i;
2945
2946 for (i = 0; i < insn_cnt; i++, insn++)
2947 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
2948 insn->src_reg = 0;
2949}
2950
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002951/* convert load instructions that access fields of 'struct __sk_buff'
2952 * into sequence of instructions that access fields of 'struct sk_buff'
2953 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01002954static int convert_ctx_accesses(struct bpf_verifier_env *env)
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002955{
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002956 const struct bpf_verifier_ops *ops = env->prog->aux->ops;
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002957 const int insn_cnt = env->prog->len;
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002958 struct bpf_insn insn_buf[16], *insn;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002959 struct bpf_prog *new_prog;
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002960 enum bpf_access_type type;
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002961 int i, cnt, delta = 0;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002962
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002963 if (ops->gen_prologue) {
2964 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
2965 env->prog);
2966 if (cnt >= ARRAY_SIZE(insn_buf)) {
2967 verbose("bpf verifier is misconfigured\n");
2968 return -EINVAL;
2969 } else if (cnt) {
2970 new_prog = bpf_patch_insn_single(env->prog, 0,
2971 insn_buf, cnt);
2972 if (!new_prog)
2973 return -ENOMEM;
2974 env->prog = new_prog;
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002975 delta += cnt - 1;
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002976 }
2977 }
2978
2979 if (!ops->convert_ctx_access)
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002980 return 0;
2981
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002982 insn = env->prog->insnsi + delta;
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002983
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002984 for (i = 0; i < insn_cnt; i++, insn++) {
Alexei Starovoitovea2e7ce2016-09-01 18:37:21 -07002985 if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
2986 insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002987 type = BPF_READ;
Alexei Starovoitovea2e7ce2016-09-01 18:37:21 -07002988 else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
2989 insn->code == (BPF_STX | BPF_MEM | BPF_DW))
Alexei Starovoitovd691f9e2015-06-04 10:11:54 -07002990 type = BPF_WRITE;
2991 else
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002992 continue;
2993
Jakub Kicinski3df126f2016-09-21 11:43:56 +01002994 if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX)
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002995 continue;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002996
Daniel Borkmann36bbef52016-09-20 00:26:13 +02002997 cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg,
2998 insn->off, insn_buf, env->prog);
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07002999 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
3000 verbose("bpf verifier is misconfigured\n");
3001 return -EINVAL;
3002 }
3003
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003004 new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf,
3005 cnt);
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003006 if (!new_prog)
3007 return -ENOMEM;
3008
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003009 delta += cnt - 1;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003010
3011 /* keep walking new program and skip insns we just inserted */
3012 env->prog = new_prog;
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003013 insn = new_prog->insnsi + i + delta;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003014 }
3015
3016 return 0;
3017}
3018
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003019static void free_states(struct bpf_verifier_env *env)
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07003020{
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003021 struct bpf_verifier_state_list *sl, *sln;
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07003022 int i;
3023
3024 if (!env->explored_states)
3025 return;
3026
3027 for (i = 0; i < env->prog->len; i++) {
3028 sl = env->explored_states[i];
3029
3030 if (sl)
3031 while (sl != STATE_LIST_MARK) {
3032 sln = sl->next;
3033 kfree(sl);
3034 sl = sln;
3035 }
3036 }
3037
3038 kfree(env->explored_states);
3039}
3040
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003041int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
Alexei Starovoitov51580e72014-09-26 00:17:02 -07003042{
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003043 char __user *log_ubuf = NULL;
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003044 struct bpf_verifier_env *env;
Alexei Starovoitov51580e72014-09-26 00:17:02 -07003045 int ret = -EINVAL;
3046
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003047 if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS)
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003048 return -E2BIG;
3049
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003050 /* 'struct bpf_verifier_env' can be global, but since it's not small,
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003051 * allocate/free it every time bpf_check() is called
3052 */
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003053 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003054 if (!env)
3055 return -ENOMEM;
3056
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003057 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3058 (*prog)->len);
3059 ret = -ENOMEM;
3060 if (!env->insn_aux_data)
3061 goto err_free_env;
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003062 env->prog = *prog;
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003063
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003064 /* grab the mutex to protect few globals used by verifier */
3065 mutex_lock(&bpf_verifier_lock);
3066
3067 if (attr->log_level || attr->log_buf || attr->log_size) {
3068 /* user requested verbose verifier output
3069 * and supplied buffer to store the verification trace
3070 */
3071 log_level = attr->log_level;
3072 log_ubuf = (char __user *) (unsigned long) attr->log_buf;
3073 log_size = attr->log_size;
3074 log_len = 0;
3075
3076 ret = -EINVAL;
3077 /* log_* values have to be sane */
3078 if (log_size < 128 || log_size > UINT_MAX >> 8 ||
3079 log_level == 0 || log_ubuf == NULL)
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003080 goto err_unlock;
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003081
3082 ret = -ENOMEM;
3083 log_buf = vmalloc(log_size);
3084 if (!log_buf)
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003085 goto err_unlock;
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003086 } else {
3087 log_level = 0;
3088 }
3089
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003090 ret = replace_map_fd_with_map_ptr(env);
3091 if (ret < 0)
3092 goto skip_full_check;
3093
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003094 env->explored_states = kcalloc(env->prog->len,
Jakub Kicinski58e2af82016-09-21 11:43:57 +01003095 sizeof(struct bpf_verifier_state_list *),
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07003096 GFP_USER);
3097 ret = -ENOMEM;
3098 if (!env->explored_states)
3099 goto skip_full_check;
3100
Alexei Starovoitov475fb782014-09-26 00:17:05 -07003101 ret = check_cfg(env);
3102 if (ret < 0)
3103 goto skip_full_check;
3104
Alexei Starovoitov1be7f752015-10-07 22:23:21 -07003105 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3106
Alexei Starovoitov17a52672014-09-26 00:17:06 -07003107 ret = do_check(env);
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003108
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003109skip_full_check:
Alexei Starovoitov17a52672014-09-26 00:17:06 -07003110 while (pop_stack(env, NULL) >= 0);
Alexei Starovoitovf1bca822014-09-29 18:50:01 -07003111 free_states(env);
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003112
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003113 if (ret == 0)
3114 /* program is valid, convert *(u32*)(ctx + off) accesses */
3115 ret = convert_ctx_accesses(env);
3116
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003117 if (log_level && log_len >= log_size - 1) {
3118 BUG_ON(log_len >= log_size);
3119 /* verifier log exceeded user supplied buffer */
3120 ret = -ENOSPC;
3121 /* fall through to return what was recorded */
3122 }
3123
3124 /* copy verifier log back to user space including trailing zero */
3125 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
3126 ret = -EFAULT;
3127 goto free_log_buf;
3128 }
3129
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003130 if (ret == 0 && env->used_map_cnt) {
3131 /* if program passed verifier, update used_maps in bpf_prog_info */
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003132 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
3133 sizeof(env->used_maps[0]),
3134 GFP_KERNEL);
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003135
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003136 if (!env->prog->aux->used_maps) {
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003137 ret = -ENOMEM;
3138 goto free_log_buf;
3139 }
3140
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003141 memcpy(env->prog->aux->used_maps, env->used_maps,
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003142 sizeof(env->used_maps[0]) * env->used_map_cnt);
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003143 env->prog->aux->used_map_cnt = env->used_map_cnt;
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003144
3145 /* program is valid. Convert pseudo bpf_ld_imm64 into generic
3146 * bpf_ld_imm64 instructions
3147 */
3148 convert_pseudo_ld_imm64(env);
3149 }
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003150
3151free_log_buf:
3152 if (log_level)
3153 vfree(log_buf);
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003154 if (!env->prog->aux->used_maps)
Alexei Starovoitov0246e642014-09-26 00:17:04 -07003155 /* if we didn't copy map pointers into bpf_prog_info, release
3156 * them now. Otherwise free_bpf_prog_info() will release them.
3157 */
3158 release_maps(env);
Alexei Starovoitov9bac3d62015-03-13 11:57:42 -07003159 *prog = env->prog;
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003160err_unlock:
Alexei Starovoitovcbd35702014-09-26 00:17:03 -07003161 mutex_unlock(&bpf_verifier_lock);
Jakub Kicinski3df126f2016-09-21 11:43:56 +01003162 vfree(env->insn_aux_data);
3163err_free_env:
3164 kfree(env);
Alexei Starovoitov51580e72014-09-26 00:17:02 -07003165 return ret;
3166}
Jakub Kicinski13a27df2016-09-21 11:43:58 +01003167
3168int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
3169 void *priv)
3170{
3171 struct bpf_verifier_env *env;
3172 int ret;
3173
3174 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
3175 if (!env)
3176 return -ENOMEM;
3177
3178 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
3179 prog->len);
3180 ret = -ENOMEM;
3181 if (!env->insn_aux_data)
3182 goto err_free_env;
3183 env->prog = prog;
3184 env->analyzer_ops = ops;
3185 env->analyzer_priv = priv;
3186
3187 /* grab the mutex to protect few globals used by verifier */
3188 mutex_lock(&bpf_verifier_lock);
3189
3190 log_level = 0;
3191
3192 env->explored_states = kcalloc(env->prog->len,
3193 sizeof(struct bpf_verifier_state_list *),
3194 GFP_KERNEL);
3195 ret = -ENOMEM;
3196 if (!env->explored_states)
3197 goto skip_full_check;
3198
3199 ret = check_cfg(env);
3200 if (ret < 0)
3201 goto skip_full_check;
3202
3203 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
3204
3205 ret = do_check(env);
3206
3207skip_full_check:
3208 while (pop_stack(env, NULL) >= 0);
3209 free_states(env);
3210
3211 mutex_unlock(&bpf_verifier_lock);
3212 vfree(env->insn_aux_data);
3213err_free_env:
3214 kfree(env);
3215 return ret;
3216}
3217EXPORT_SYMBOL_GPL(bpf_analyzer);