Commit | Line | Data |
---|---|---|
51580e79 | 1 | /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
969bf05e | 2 | * Copyright (c) 2016 Facebook |
51580e79 AS |
3 | * |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
11 | * General Public License for more details. | |
12 | */ | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/bpf.h> | |
17 | #include <linux/filter.h> | |
18 | #include <net/netlink.h> | |
19 | #include <linux/file.h> | |
20 | #include <linux/vmalloc.h> | |
21 | ||
22 | /* bpf_check() is a static code analyzer that walks eBPF program | |
23 | * instruction by instruction and updates register/stack state. | |
24 | * All paths of conditional branches are analyzed until 'bpf_exit' insn. | |
25 | * | |
26 | * The first pass is depth-first-search to check that the program is a DAG. | |
27 | * It rejects the following programs: | |
28 | * - larger than BPF_MAXINSNS insns | |
29 | * - if loop is present (detected via back-edge) | |
30 | * - unreachable insns exist (shouldn't be a forest. program = one function) | |
31 | * - out of bounds or malformed jumps | |
32 | * The second pass is all possible path descent from the 1st insn. | |
33 | * Since it's analyzing all pathes through the program, the length of the | |
34 | * analysis is limited to 32k insn, which may be hit even if total number of | |
35 | * insn is less then 4K, but there are too many branches that change stack/regs. | |
36 | * Number of 'branches to be analyzed' is limited to 1k | |
37 | * | |
38 | * On entry to each instruction, each register has a type, and the instruction | |
39 | * changes the types of the registers depending on instruction semantics. | |
40 | * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is | |
41 | * copied to R1. | |
42 | * | |
43 | * All registers are 64-bit. | |
44 | * R0 - return register | |
45 | * R1-R5 argument passing registers | |
46 | * R6-R9 callee saved registers | |
47 | * R10 - frame pointer read-only | |
48 | * | |
49 | * At the start of BPF program the register R1 contains a pointer to bpf_context | |
50 | * and has type PTR_TO_CTX. | |
51 | * | |
52 | * Verifier tracks arithmetic operations on pointers in case: | |
53 | * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), | |
54 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), | |
55 | * 1st insn copies R10 (which has FRAME_PTR) type into R1 | |
56 | * and 2nd arithmetic instruction is pattern matched to recognize | |
57 | * that it wants to construct a pointer to some element within stack. | |
58 | * So after 2nd insn, the register R1 has type PTR_TO_STACK | |
59 | * (and -20 constant is saved for further stack bounds checking). | |
60 | * Meaning that this reg is a pointer to stack plus known immediate constant. | |
61 | * | |
62 | * Most of the time the registers have UNKNOWN_VALUE type, which | |
63 | * means the register has some value, but it's not a valid pointer. | |
64 | * (like pointer plus pointer becomes UNKNOWN_VALUE type) | |
65 | * | |
66 | * When verifier sees load or store instructions the type of base register | |
67 | * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer | |
68 | * types recognized by check_mem_access() function. | |
69 | * | |
70 | * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' | |
71 | * and the range of [ptr, ptr + map's value_size) is accessible. | |
72 | * | |
73 | * registers used to pass values to function calls are checked against | |
74 | * function argument constraints. | |
75 | * | |
76 | * ARG_PTR_TO_MAP_KEY is one of such argument constraints. | |
77 | * It means that the register type passed to this function must be | |
78 | * PTR_TO_STACK and it will be used inside the function as | |
79 | * 'pointer to map element key' | |
80 | * | |
81 | * For example the argument constraints for bpf_map_lookup_elem(): | |
82 | * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, | |
83 | * .arg1_type = ARG_CONST_MAP_PTR, | |
84 | * .arg2_type = ARG_PTR_TO_MAP_KEY, | |
85 | * | |
86 | * ret_type says that this function returns 'pointer to map elem value or null' | |
87 | * function expects 1st argument to be a const pointer to 'struct bpf_map' and | |
88 | * 2nd argument should be a pointer to stack, which will be used inside | |
89 | * the helper function as a pointer to map element key. | |
90 | * | |
91 | * On the kernel side the helper function looks like: | |
92 | * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
93 | * { | |
94 | * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
95 | * void *key = (void *) (unsigned long) r2; | |
96 | * void *value; | |
97 | * | |
98 | * here kernel can access 'key' and 'map' pointers safely, knowing that | |
99 | * [key, key + map->key_size) bytes are valid and were initialized on | |
100 | * the stack of eBPF program. | |
101 | * } | |
102 | * | |
103 | * Corresponding eBPF program may look like: | |
104 | * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR | |
105 | * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK | |
106 | * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP | |
107 | * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
108 | * here verifier looks at prototype of map_lookup_elem() and sees: | |
109 | * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, | |
110 | * Now verifier knows that this map has key of R1->map_ptr->key_size bytes | |
111 | * | |
112 | * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, | |
113 | * Now verifier checks that [R2, R2 + map's key_size) are within stack limits | |
114 | * and were initialized prior to this call. | |
115 | * If it's ok, then verifier allows this BPF_CALL insn and looks at | |
116 | * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets | |
117 | * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function | |
118 | * returns ether pointer to map value or NULL. | |
119 | * | |
120 | * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' | |
121 | * insn, the register holding that pointer in the true branch changes state to | |
122 | * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false | |
123 | * branch. See check_cond_jmp_op(). | |
124 | * | |
125 | * After the call R0 is set to return type of the function and registers R1-R5 | |
126 | * are set to NOT_INIT to indicate that they are no longer readable. | |
127 | */ | |
128 | ||
17a52670 AS |
129 | /* types of values stored in eBPF registers */ |
130 | enum bpf_reg_type { | |
131 | NOT_INIT = 0, /* nothing was written into register */ | |
132 | UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */ | |
133 | PTR_TO_CTX, /* reg points to bpf_context */ | |
134 | CONST_PTR_TO_MAP, /* reg points to struct bpf_map */ | |
135 | PTR_TO_MAP_VALUE, /* reg points to map element value */ | |
136 | PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */ | |
137 | FRAME_PTR, /* reg == frame_pointer */ | |
138 | PTR_TO_STACK, /* reg == frame_pointer + imm */ | |
139 | CONST_IMM, /* constant integer value */ | |
969bf05e AS |
140 | |
141 | /* PTR_TO_PACKET represents: | |
142 | * skb->data | |
143 | * skb->data + imm | |
144 | * skb->data + (u16) var | |
145 | * skb->data + (u16) var + imm | |
146 | * if (range > 0) then [ptr, ptr + range - off) is safe to access | |
147 | * if (id > 0) means that some 'var' was added | |
148 | * if (off > 0) menas that 'imm' was added | |
149 | */ | |
150 | PTR_TO_PACKET, | |
151 | PTR_TO_PACKET_END, /* skb->data + headlen */ | |
17a52670 AS |
152 | }; |
153 | ||
154 | struct reg_state { | |
155 | enum bpf_reg_type type; | |
156 | union { | |
969bf05e AS |
157 | /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ |
158 | s64 imm; | |
159 | ||
160 | /* valid when type == PTR_TO_PACKET* */ | |
161 | struct { | |
162 | u32 id; | |
163 | u16 off; | |
164 | u16 range; | |
165 | }; | |
17a52670 AS |
166 | |
167 | /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | | |
168 | * PTR_TO_MAP_VALUE_OR_NULL | |
169 | */ | |
170 | struct bpf_map *map_ptr; | |
171 | }; | |
172 | }; | |
173 | ||
174 | enum bpf_stack_slot_type { | |
175 | STACK_INVALID, /* nothing was stored in this stack slot */ | |
9c399760 | 176 | STACK_SPILL, /* register spilled into stack */ |
17a52670 AS |
177 | STACK_MISC /* BPF program wrote some data into this slot */ |
178 | }; | |
179 | ||
9c399760 | 180 | #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ |
17a52670 AS |
181 | |
182 | /* state of the program: | |
183 | * type of all registers and stack info | |
184 | */ | |
185 | struct verifier_state { | |
186 | struct reg_state regs[MAX_BPF_REG]; | |
9c399760 AS |
187 | u8 stack_slot_type[MAX_BPF_STACK]; |
188 | struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; | |
17a52670 AS |
189 | }; |
190 | ||
191 | /* linked list of verifier states used to prune search */ | |
192 | struct verifier_state_list { | |
193 | struct verifier_state state; | |
194 | struct verifier_state_list *next; | |
195 | }; | |
196 | ||
197 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ | |
198 | struct verifier_stack_elem { | |
199 | /* verifer state is 'st' | |
200 | * before processing instruction 'insn_idx' | |
201 | * and after processing instruction 'prev_insn_idx' | |
202 | */ | |
203 | struct verifier_state st; | |
204 | int insn_idx; | |
205 | int prev_insn_idx; | |
206 | struct verifier_stack_elem *next; | |
207 | }; | |
208 | ||
0246e64d AS |
209 | #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ |
210 | ||
cbd35700 AS |
211 | /* single container for all structs |
212 | * one verifier_env per bpf_check() call | |
213 | */ | |
214 | struct verifier_env { | |
0246e64d | 215 | struct bpf_prog *prog; /* eBPF program being verified */ |
17a52670 AS |
216 | struct verifier_stack_elem *head; /* stack of verifier states to be processed */ |
217 | int stack_size; /* number of states to be processed */ | |
218 | struct verifier_state cur_state; /* current verifier state */ | |
f1bca824 | 219 | struct verifier_state_list **explored_states; /* search pruning optimization */ |
0246e64d AS |
220 | struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ |
221 | u32 used_map_cnt; /* number of used maps */ | |
1be7f75d | 222 | bool allow_ptr_leaks; |
cbd35700 AS |
223 | }; |
224 | ||
07016151 DB |
225 | #define BPF_COMPLEXITY_LIMIT_INSNS 65536 |
226 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 | |
227 | ||
33ff9823 DB |
228 | struct bpf_call_arg_meta { |
229 | struct bpf_map *map_ptr; | |
435faee1 DB |
230 | bool raw_mode; |
231 | int regno; | |
232 | int access_size; | |
33ff9823 DB |
233 | }; |
234 | ||
cbd35700 AS |
235 | /* verbose verifier prints what it's seeing |
236 | * bpf_check() is called under lock, so no race to access these global vars | |
237 | */ | |
238 | static u32 log_level, log_size, log_len; | |
239 | static char *log_buf; | |
240 | ||
241 | static DEFINE_MUTEX(bpf_verifier_lock); | |
242 | ||
243 | /* log_level controls verbosity level of eBPF verifier. | |
244 | * verbose() is used to dump the verification trace to the log, so the user | |
245 | * can figure out what's wrong with the program | |
246 | */ | |
1d056d9c | 247 | static __printf(1, 2) void verbose(const char *fmt, ...) |
cbd35700 AS |
248 | { |
249 | va_list args; | |
250 | ||
251 | if (log_level == 0 || log_len >= log_size - 1) | |
252 | return; | |
253 | ||
254 | va_start(args, fmt); | |
255 | log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); | |
256 | va_end(args); | |
257 | } | |
258 | ||
17a52670 AS |
259 | /* string representation of 'enum bpf_reg_type' */ |
260 | static const char * const reg_type_str[] = { | |
261 | [NOT_INIT] = "?", | |
262 | [UNKNOWN_VALUE] = "inv", | |
263 | [PTR_TO_CTX] = "ctx", | |
264 | [CONST_PTR_TO_MAP] = "map_ptr", | |
265 | [PTR_TO_MAP_VALUE] = "map_value", | |
266 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
267 | [FRAME_PTR] = "fp", | |
268 | [PTR_TO_STACK] = "fp", | |
269 | [CONST_IMM] = "imm", | |
969bf05e AS |
270 | [PTR_TO_PACKET] = "pkt", |
271 | [PTR_TO_PACKET_END] = "pkt_end", | |
17a52670 AS |
272 | }; |
273 | ||
1a0dc1ac | 274 | static void print_verifier_state(struct verifier_state *state) |
17a52670 | 275 | { |
1a0dc1ac | 276 | struct reg_state *reg; |
17a52670 AS |
277 | enum bpf_reg_type t; |
278 | int i; | |
279 | ||
280 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
281 | reg = &state->regs[i]; |
282 | t = reg->type; | |
17a52670 AS |
283 | if (t == NOT_INIT) |
284 | continue; | |
285 | verbose(" R%d=%s", i, reg_type_str[t]); | |
286 | if (t == CONST_IMM || t == PTR_TO_STACK) | |
969bf05e AS |
287 | verbose("%lld", reg->imm); |
288 | else if (t == PTR_TO_PACKET) | |
289 | verbose("(id=%d,off=%d,r=%d)", | |
290 | reg->id, reg->off, reg->range); | |
291 | else if (t == UNKNOWN_VALUE && reg->imm) | |
292 | verbose("%lld", reg->imm); | |
17a52670 AS |
293 | else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || |
294 | t == PTR_TO_MAP_VALUE_OR_NULL) | |
295 | verbose("(ks=%d,vs=%d)", | |
1a0dc1ac AS |
296 | reg->map_ptr->key_size, |
297 | reg->map_ptr->value_size); | |
17a52670 | 298 | } |
9c399760 | 299 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 300 | if (state->stack_slot_type[i] == STACK_SPILL) |
17a52670 | 301 | verbose(" fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 302 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 AS |
303 | } |
304 | verbose("\n"); | |
305 | } | |
306 | ||
cbd35700 AS |
307 | static const char *const bpf_class_string[] = { |
308 | [BPF_LD] = "ld", | |
309 | [BPF_LDX] = "ldx", | |
310 | [BPF_ST] = "st", | |
311 | [BPF_STX] = "stx", | |
312 | [BPF_ALU] = "alu", | |
313 | [BPF_JMP] = "jmp", | |
314 | [BPF_RET] = "BUG", | |
315 | [BPF_ALU64] = "alu64", | |
316 | }; | |
317 | ||
687f0715 | 318 | static const char *const bpf_alu_string[16] = { |
cbd35700 AS |
319 | [BPF_ADD >> 4] = "+=", |
320 | [BPF_SUB >> 4] = "-=", | |
321 | [BPF_MUL >> 4] = "*=", | |
322 | [BPF_DIV >> 4] = "/=", | |
323 | [BPF_OR >> 4] = "|=", | |
324 | [BPF_AND >> 4] = "&=", | |
325 | [BPF_LSH >> 4] = "<<=", | |
326 | [BPF_RSH >> 4] = ">>=", | |
327 | [BPF_NEG >> 4] = "neg", | |
328 | [BPF_MOD >> 4] = "%=", | |
329 | [BPF_XOR >> 4] = "^=", | |
330 | [BPF_MOV >> 4] = "=", | |
331 | [BPF_ARSH >> 4] = "s>>=", | |
332 | [BPF_END >> 4] = "endian", | |
333 | }; | |
334 | ||
335 | static const char *const bpf_ldst_string[] = { | |
336 | [BPF_W >> 3] = "u32", | |
337 | [BPF_H >> 3] = "u16", | |
338 | [BPF_B >> 3] = "u8", | |
339 | [BPF_DW >> 3] = "u64", | |
340 | }; | |
341 | ||
687f0715 | 342 | static const char *const bpf_jmp_string[16] = { |
cbd35700 AS |
343 | [BPF_JA >> 4] = "jmp", |
344 | [BPF_JEQ >> 4] = "==", | |
345 | [BPF_JGT >> 4] = ">", | |
346 | [BPF_JGE >> 4] = ">=", | |
347 | [BPF_JSET >> 4] = "&", | |
348 | [BPF_JNE >> 4] = "!=", | |
349 | [BPF_JSGT >> 4] = "s>", | |
350 | [BPF_JSGE >> 4] = "s>=", | |
351 | [BPF_CALL >> 4] = "call", | |
352 | [BPF_EXIT >> 4] = "exit", | |
353 | }; | |
354 | ||
355 | static void print_bpf_insn(struct bpf_insn *insn) | |
356 | { | |
357 | u8 class = BPF_CLASS(insn->code); | |
358 | ||
359 | if (class == BPF_ALU || class == BPF_ALU64) { | |
360 | if (BPF_SRC(insn->code) == BPF_X) | |
361 | verbose("(%02x) %sr%d %s %sr%d\n", | |
362 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
363 | insn->dst_reg, | |
364 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
365 | class == BPF_ALU ? "(u32) " : "", | |
366 | insn->src_reg); | |
367 | else | |
368 | verbose("(%02x) %sr%d %s %s%d\n", | |
369 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
370 | insn->dst_reg, | |
371 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
372 | class == BPF_ALU ? "(u32) " : "", | |
373 | insn->imm); | |
374 | } else if (class == BPF_STX) { | |
375 | if (BPF_MODE(insn->code) == BPF_MEM) | |
376 | verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", | |
377 | insn->code, | |
378 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
379 | insn->dst_reg, | |
380 | insn->off, insn->src_reg); | |
381 | else if (BPF_MODE(insn->code) == BPF_XADD) | |
382 | verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", | |
383 | insn->code, | |
384 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
385 | insn->dst_reg, insn->off, | |
386 | insn->src_reg); | |
387 | else | |
388 | verbose("BUG_%02x\n", insn->code); | |
389 | } else if (class == BPF_ST) { | |
390 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
391 | verbose("BUG_st_%02x\n", insn->code); | |
392 | return; | |
393 | } | |
394 | verbose("(%02x) *(%s *)(r%d %+d) = %d\n", | |
395 | insn->code, | |
396 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
397 | insn->dst_reg, | |
398 | insn->off, insn->imm); | |
399 | } else if (class == BPF_LDX) { | |
400 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
401 | verbose("BUG_ldx_%02x\n", insn->code); | |
402 | return; | |
403 | } | |
404 | verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", | |
405 | insn->code, insn->dst_reg, | |
406 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
407 | insn->src_reg, insn->off); | |
408 | } else if (class == BPF_LD) { | |
409 | if (BPF_MODE(insn->code) == BPF_ABS) { | |
410 | verbose("(%02x) r0 = *(%s *)skb[%d]\n", | |
411 | insn->code, | |
412 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
413 | insn->imm); | |
414 | } else if (BPF_MODE(insn->code) == BPF_IND) { | |
415 | verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", | |
416 | insn->code, | |
417 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
418 | insn->src_reg, insn->imm); | |
419 | } else if (BPF_MODE(insn->code) == BPF_IMM) { | |
420 | verbose("(%02x) r%d = 0x%x\n", | |
421 | insn->code, insn->dst_reg, insn->imm); | |
422 | } else { | |
423 | verbose("BUG_ld_%02x\n", insn->code); | |
424 | return; | |
425 | } | |
426 | } else if (class == BPF_JMP) { | |
427 | u8 opcode = BPF_OP(insn->code); | |
428 | ||
429 | if (opcode == BPF_CALL) { | |
430 | verbose("(%02x) call %d\n", insn->code, insn->imm); | |
431 | } else if (insn->code == (BPF_JMP | BPF_JA)) { | |
432 | verbose("(%02x) goto pc%+d\n", | |
433 | insn->code, insn->off); | |
434 | } else if (insn->code == (BPF_JMP | BPF_EXIT)) { | |
435 | verbose("(%02x) exit\n", insn->code); | |
436 | } else if (BPF_SRC(insn->code) == BPF_X) { | |
437 | verbose("(%02x) if r%d %s r%d goto pc%+d\n", | |
438 | insn->code, insn->dst_reg, | |
439 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
440 | insn->src_reg, insn->off); | |
441 | } else { | |
442 | verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", | |
443 | insn->code, insn->dst_reg, | |
444 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
445 | insn->imm, insn->off); | |
446 | } | |
447 | } else { | |
448 | verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); | |
449 | } | |
450 | } | |
451 | ||
17a52670 AS |
452 | static int pop_stack(struct verifier_env *env, int *prev_insn_idx) |
453 | { | |
454 | struct verifier_stack_elem *elem; | |
455 | int insn_idx; | |
456 | ||
457 | if (env->head == NULL) | |
458 | return -1; | |
459 | ||
460 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
461 | insn_idx = env->head->insn_idx; | |
462 | if (prev_insn_idx) | |
463 | *prev_insn_idx = env->head->prev_insn_idx; | |
464 | elem = env->head->next; | |
465 | kfree(env->head); | |
466 | env->head = elem; | |
467 | env->stack_size--; | |
468 | return insn_idx; | |
469 | } | |
470 | ||
471 | static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx, | |
472 | int prev_insn_idx) | |
473 | { | |
474 | struct verifier_stack_elem *elem; | |
475 | ||
476 | elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL); | |
477 | if (!elem) | |
478 | goto err; | |
479 | ||
480 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
481 | elem->insn_idx = insn_idx; | |
482 | elem->prev_insn_idx = prev_insn_idx; | |
483 | elem->next = env->head; | |
484 | env->head = elem; | |
485 | env->stack_size++; | |
07016151 | 486 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
17a52670 AS |
487 | verbose("BPF program is too complex\n"); |
488 | goto err; | |
489 | } | |
490 | return &elem->st; | |
491 | err: | |
492 | /* pop all elements and return */ | |
493 | while (pop_stack(env, NULL) >= 0); | |
494 | return NULL; | |
495 | } | |
496 | ||
497 | #define CALLER_SAVED_REGS 6 | |
498 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
499 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
500 | }; | |
501 | ||
502 | static void init_reg_state(struct reg_state *regs) | |
503 | { | |
504 | int i; | |
505 | ||
506 | for (i = 0; i < MAX_BPF_REG; i++) { | |
507 | regs[i].type = NOT_INIT; | |
508 | regs[i].imm = 0; | |
17a52670 AS |
509 | } |
510 | ||
511 | /* frame pointer */ | |
512 | regs[BPF_REG_FP].type = FRAME_PTR; | |
513 | ||
514 | /* 1st arg to a function */ | |
515 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
516 | } | |
517 | ||
518 | static void mark_reg_unknown_value(struct reg_state *regs, u32 regno) | |
519 | { | |
520 | BUG_ON(regno >= MAX_BPF_REG); | |
521 | regs[regno].type = UNKNOWN_VALUE; | |
522 | regs[regno].imm = 0; | |
17a52670 AS |
523 | } |
524 | ||
525 | enum reg_arg_type { | |
526 | SRC_OP, /* register is used as source operand */ | |
527 | DST_OP, /* register is used as destination operand */ | |
528 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
529 | }; | |
530 | ||
531 | static int check_reg_arg(struct reg_state *regs, u32 regno, | |
532 | enum reg_arg_type t) | |
533 | { | |
534 | if (regno >= MAX_BPF_REG) { | |
535 | verbose("R%d is invalid\n", regno); | |
536 | return -EINVAL; | |
537 | } | |
538 | ||
539 | if (t == SRC_OP) { | |
540 | /* check whether register used as source operand can be read */ | |
541 | if (regs[regno].type == NOT_INIT) { | |
542 | verbose("R%d !read_ok\n", regno); | |
543 | return -EACCES; | |
544 | } | |
545 | } else { | |
546 | /* check whether register used as dest operand can be written to */ | |
547 | if (regno == BPF_REG_FP) { | |
548 | verbose("frame pointer is read only\n"); | |
549 | return -EACCES; | |
550 | } | |
551 | if (t == DST_OP) | |
552 | mark_reg_unknown_value(regs, regno); | |
553 | } | |
554 | return 0; | |
555 | } | |
556 | ||
557 | static int bpf_size_to_bytes(int bpf_size) | |
558 | { | |
559 | if (bpf_size == BPF_W) | |
560 | return 4; | |
561 | else if (bpf_size == BPF_H) | |
562 | return 2; | |
563 | else if (bpf_size == BPF_B) | |
564 | return 1; | |
565 | else if (bpf_size == BPF_DW) | |
566 | return 8; | |
567 | else | |
568 | return -EINVAL; | |
569 | } | |
570 | ||
1be7f75d AS |
571 | static bool is_spillable_regtype(enum bpf_reg_type type) |
572 | { | |
573 | switch (type) { | |
574 | case PTR_TO_MAP_VALUE: | |
575 | case PTR_TO_MAP_VALUE_OR_NULL: | |
576 | case PTR_TO_STACK: | |
577 | case PTR_TO_CTX: | |
969bf05e AS |
578 | case PTR_TO_PACKET: |
579 | case PTR_TO_PACKET_END: | |
1be7f75d AS |
580 | case FRAME_PTR: |
581 | case CONST_PTR_TO_MAP: | |
582 | return true; | |
583 | default: | |
584 | return false; | |
585 | } | |
586 | } | |
587 | ||
17a52670 AS |
588 | /* check_stack_read/write functions track spill/fill of registers, |
589 | * stack boundary and alignment are checked in check_mem_access() | |
590 | */ | |
591 | static int check_stack_write(struct verifier_state *state, int off, int size, | |
592 | int value_regno) | |
593 | { | |
17a52670 | 594 | int i; |
9c399760 AS |
595 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
596 | * so it's aligned access and [off, off + size) are within stack limits | |
597 | */ | |
17a52670 AS |
598 | |
599 | if (value_regno >= 0 && | |
1be7f75d | 600 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
601 | |
602 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 603 | if (size != BPF_REG_SIZE) { |
17a52670 AS |
604 | verbose("invalid size of register spill\n"); |
605 | return -EACCES; | |
606 | } | |
607 | ||
17a52670 | 608 | /* save register state */ |
9c399760 AS |
609 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
610 | state->regs[value_regno]; | |
17a52670 | 611 | |
9c399760 AS |
612 | for (i = 0; i < BPF_REG_SIZE; i++) |
613 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
614 | } else { | |
17a52670 | 615 | /* regular write of data into stack */ |
9c399760 AS |
616 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
617 | (struct reg_state) {}; | |
618 | ||
619 | for (i = 0; i < size; i++) | |
620 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
621 | } |
622 | return 0; | |
623 | } | |
624 | ||
625 | static int check_stack_read(struct verifier_state *state, int off, int size, | |
626 | int value_regno) | |
627 | { | |
9c399760 | 628 | u8 *slot_type; |
17a52670 | 629 | int i; |
17a52670 | 630 | |
9c399760 | 631 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 632 | |
9c399760 AS |
633 | if (slot_type[0] == STACK_SPILL) { |
634 | if (size != BPF_REG_SIZE) { | |
17a52670 AS |
635 | verbose("invalid size of register spill\n"); |
636 | return -EACCES; | |
637 | } | |
9c399760 AS |
638 | for (i = 1; i < BPF_REG_SIZE; i++) { |
639 | if (slot_type[i] != STACK_SPILL) { | |
17a52670 AS |
640 | verbose("corrupted spill memory\n"); |
641 | return -EACCES; | |
642 | } | |
643 | } | |
644 | ||
645 | if (value_regno >= 0) | |
646 | /* restore register state from stack */ | |
9c399760 AS |
647 | state->regs[value_regno] = |
648 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; | |
17a52670 AS |
649 | return 0; |
650 | } else { | |
651 | for (i = 0; i < size; i++) { | |
9c399760 | 652 | if (slot_type[i] != STACK_MISC) { |
17a52670 AS |
653 | verbose("invalid read from stack off %d+%d size %d\n", |
654 | off, i, size); | |
655 | return -EACCES; | |
656 | } | |
657 | } | |
658 | if (value_regno >= 0) | |
659 | /* have read misc data from the stack */ | |
660 | mark_reg_unknown_value(state->regs, value_regno); | |
661 | return 0; | |
662 | } | |
663 | } | |
664 | ||
665 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
666 | static int check_map_access(struct verifier_env *env, u32 regno, int off, | |
667 | int size) | |
668 | { | |
669 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
670 | ||
671 | if (off < 0 || off + size > map->value_size) { | |
672 | verbose("invalid access to map value, value_size=%d off=%d size=%d\n", | |
673 | map->value_size, off, size); | |
674 | return -EACCES; | |
675 | } | |
676 | return 0; | |
677 | } | |
678 | ||
969bf05e AS |
679 | #define MAX_PACKET_OFF 0xffff |
680 | ||
681 | static int check_packet_access(struct verifier_env *env, u32 regno, int off, | |
682 | int size) | |
683 | { | |
684 | struct reg_state *regs = env->cur_state.regs; | |
685 | struct reg_state *reg = ®s[regno]; | |
969bf05e | 686 | |
d91b28ed AS |
687 | off += reg->off; |
688 | if (off < 0 || off + size > reg->range) { | |
689 | verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", | |
690 | off, size, regno, reg->id, reg->off, reg->range); | |
969bf05e AS |
691 | return -EACCES; |
692 | } | |
693 | return 0; | |
694 | } | |
695 | ||
17a52670 AS |
696 | /* check access to 'struct bpf_context' fields */ |
697 | static int check_ctx_access(struct verifier_env *env, int off, int size, | |
698 | enum bpf_access_type t) | |
699 | { | |
700 | if (env->prog->aux->ops->is_valid_access && | |
32bbe007 AS |
701 | env->prog->aux->ops->is_valid_access(off, size, t)) { |
702 | /* remember the offset of last byte accessed in ctx */ | |
703 | if (env->prog->aux->max_ctx_offset < off + size) | |
704 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 705 | return 0; |
32bbe007 | 706 | } |
17a52670 AS |
707 | |
708 | verbose("invalid bpf_context access off=%d size=%d\n", off, size); | |
709 | return -EACCES; | |
710 | } | |
711 | ||
1be7f75d AS |
712 | static bool is_pointer_value(struct verifier_env *env, int regno) |
713 | { | |
714 | if (env->allow_ptr_leaks) | |
715 | return false; | |
716 | ||
717 | switch (env->cur_state.regs[regno].type) { | |
718 | case UNKNOWN_VALUE: | |
719 | case CONST_IMM: | |
720 | return false; | |
721 | default: | |
722 | return true; | |
723 | } | |
724 | } | |
725 | ||
969bf05e AS |
726 | static int check_ptr_alignment(struct verifier_env *env, struct reg_state *reg, |
727 | int off, int size) | |
728 | { | |
729 | if (reg->type != PTR_TO_PACKET) { | |
730 | if (off % size != 0) { | |
731 | verbose("misaligned access off %d size %d\n", off, size); | |
732 | return -EACCES; | |
733 | } else { | |
734 | return 0; | |
735 | } | |
736 | } | |
737 | ||
738 | switch (env->prog->type) { | |
739 | case BPF_PROG_TYPE_SCHED_CLS: | |
740 | case BPF_PROG_TYPE_SCHED_ACT: | |
741 | break; | |
742 | default: | |
743 | verbose("verifier is misconfigured\n"); | |
744 | return -EACCES; | |
745 | } | |
746 | ||
747 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
748 | /* misaligned access to packet is ok on x86,arm,arm64 */ | |
749 | return 0; | |
750 | ||
751 | if (reg->id && size != 1) { | |
752 | verbose("Unknown packet alignment. Only byte-sized access allowed\n"); | |
753 | return -EACCES; | |
754 | } | |
755 | ||
756 | /* skb->data is NET_IP_ALIGN-ed */ | |
757 | if ((NET_IP_ALIGN + reg->off + off) % size != 0) { | |
758 | verbose("misaligned packet access off %d+%d+%d size %d\n", | |
759 | NET_IP_ALIGN, reg->off, off, size); | |
760 | return -EACCES; | |
761 | } | |
762 | return 0; | |
763 | } | |
764 | ||
17a52670 AS |
765 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
766 | * if t==write, value_regno is a register which value is stored into memory | |
767 | * if t==read, value_regno is a register which will receive the value from memory | |
768 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
769 | * if t==read && value_regno==-1, don't care what we read from memory | |
770 | */ | |
771 | static int check_mem_access(struct verifier_env *env, u32 regno, int off, | |
772 | int bpf_size, enum bpf_access_type t, | |
773 | int value_regno) | |
774 | { | |
775 | struct verifier_state *state = &env->cur_state; | |
1a0dc1ac | 776 | struct reg_state *reg = &state->regs[regno]; |
17a52670 AS |
777 | int size, err = 0; |
778 | ||
1a0dc1ac AS |
779 | if (reg->type == PTR_TO_STACK) |
780 | off += reg->imm; | |
24b4d2ab | 781 | |
17a52670 AS |
782 | size = bpf_size_to_bytes(bpf_size); |
783 | if (size < 0) | |
784 | return size; | |
785 | ||
969bf05e AS |
786 | err = check_ptr_alignment(env, reg, off, size); |
787 | if (err) | |
788 | return err; | |
17a52670 | 789 | |
1a0dc1ac | 790 | if (reg->type == PTR_TO_MAP_VALUE) { |
1be7f75d AS |
791 | if (t == BPF_WRITE && value_regno >= 0 && |
792 | is_pointer_value(env, value_regno)) { | |
793 | verbose("R%d leaks addr into map\n", value_regno); | |
794 | return -EACCES; | |
795 | } | |
17a52670 AS |
796 | err = check_map_access(env, regno, off, size); |
797 | if (!err && t == BPF_READ && value_regno >= 0) | |
798 | mark_reg_unknown_value(state->regs, value_regno); | |
799 | ||
1a0dc1ac | 800 | } else if (reg->type == PTR_TO_CTX) { |
1be7f75d AS |
801 | if (t == BPF_WRITE && value_regno >= 0 && |
802 | is_pointer_value(env, value_regno)) { | |
803 | verbose("R%d leaks addr into ctx\n", value_regno); | |
804 | return -EACCES; | |
805 | } | |
17a52670 | 806 | err = check_ctx_access(env, off, size, t); |
969bf05e | 807 | if (!err && t == BPF_READ && value_regno >= 0) { |
17a52670 | 808 | mark_reg_unknown_value(state->regs, value_regno); |
969bf05e AS |
809 | if (off == offsetof(struct __sk_buff, data) && |
810 | env->allow_ptr_leaks) | |
811 | /* note that reg.[id|off|range] == 0 */ | |
812 | state->regs[value_regno].type = PTR_TO_PACKET; | |
813 | else if (off == offsetof(struct __sk_buff, data_end) && | |
814 | env->allow_ptr_leaks) | |
815 | state->regs[value_regno].type = PTR_TO_PACKET_END; | |
816 | } | |
17a52670 | 817 | |
1a0dc1ac | 818 | } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { |
17a52670 AS |
819 | if (off >= 0 || off < -MAX_BPF_STACK) { |
820 | verbose("invalid stack off=%d size=%d\n", off, size); | |
821 | return -EACCES; | |
822 | } | |
1be7f75d AS |
823 | if (t == BPF_WRITE) { |
824 | if (!env->allow_ptr_leaks && | |
825 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
826 | size != BPF_REG_SIZE) { | |
827 | verbose("attempt to corrupt spilled pointer on stack\n"); | |
828 | return -EACCES; | |
829 | } | |
17a52670 | 830 | err = check_stack_write(state, off, size, value_regno); |
1be7f75d | 831 | } else { |
17a52670 | 832 | err = check_stack_read(state, off, size, value_regno); |
1be7f75d | 833 | } |
969bf05e AS |
834 | } else if (state->regs[regno].type == PTR_TO_PACKET) { |
835 | if (t == BPF_WRITE) { | |
836 | verbose("cannot write into packet\n"); | |
837 | return -EACCES; | |
838 | } | |
839 | err = check_packet_access(env, regno, off, size); | |
840 | if (!err && t == BPF_READ && value_regno >= 0) | |
841 | mark_reg_unknown_value(state->regs, value_regno); | |
17a52670 AS |
842 | } else { |
843 | verbose("R%d invalid mem access '%s'\n", | |
1a0dc1ac | 844 | regno, reg_type_str[reg->type]); |
17a52670 AS |
845 | return -EACCES; |
846 | } | |
969bf05e AS |
847 | |
848 | if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && | |
849 | state->regs[value_regno].type == UNKNOWN_VALUE) { | |
850 | /* 1 or 2 byte load zero-extends, determine the number of | |
851 | * zero upper bits. Not doing it fo 4 byte load, since | |
852 | * such values cannot be added to ptr_to_packet anyway. | |
853 | */ | |
854 | state->regs[value_regno].imm = 64 - size * 8; | |
855 | } | |
17a52670 AS |
856 | return err; |
857 | } | |
858 | ||
859 | static int check_xadd(struct verifier_env *env, struct bpf_insn *insn) | |
860 | { | |
861 | struct reg_state *regs = env->cur_state.regs; | |
862 | int err; | |
863 | ||
864 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
865 | insn->imm != 0) { | |
866 | verbose("BPF_XADD uses reserved fields\n"); | |
867 | return -EINVAL; | |
868 | } | |
869 | ||
870 | /* check src1 operand */ | |
871 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
872 | if (err) | |
873 | return err; | |
874 | ||
875 | /* check src2 operand */ | |
876 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
877 | if (err) | |
878 | return err; | |
879 | ||
880 | /* check whether atomic_add can read the memory */ | |
881 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
882 | BPF_SIZE(insn->code), BPF_READ, -1); | |
883 | if (err) | |
884 | return err; | |
885 | ||
886 | /* check whether atomic_add can write into the same memory */ | |
887 | return check_mem_access(env, insn->dst_reg, insn->off, | |
888 | BPF_SIZE(insn->code), BPF_WRITE, -1); | |
889 | } | |
890 | ||
891 | /* when register 'regno' is passed into function that will read 'access_size' | |
892 | * bytes from that pointer, make sure that it's within stack boundary | |
893 | * and all elements of stack are initialized | |
894 | */ | |
8e2fe1d9 | 895 | static int check_stack_boundary(struct verifier_env *env, int regno, |
435faee1 DB |
896 | int access_size, bool zero_size_allowed, |
897 | struct bpf_call_arg_meta *meta) | |
17a52670 AS |
898 | { |
899 | struct verifier_state *state = &env->cur_state; | |
900 | struct reg_state *regs = state->regs; | |
901 | int off, i; | |
902 | ||
8e2fe1d9 DB |
903 | if (regs[regno].type != PTR_TO_STACK) { |
904 | if (zero_size_allowed && access_size == 0 && | |
905 | regs[regno].type == CONST_IMM && | |
906 | regs[regno].imm == 0) | |
907 | return 0; | |
908 | ||
909 | verbose("R%d type=%s expected=%s\n", regno, | |
910 | reg_type_str[regs[regno].type], | |
911 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 912 | return -EACCES; |
8e2fe1d9 | 913 | } |
17a52670 AS |
914 | |
915 | off = regs[regno].imm; | |
916 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || | |
917 | access_size <= 0) { | |
918 | verbose("invalid stack type R%d off=%d access_size=%d\n", | |
919 | regno, off, access_size); | |
920 | return -EACCES; | |
921 | } | |
922 | ||
435faee1 DB |
923 | if (meta && meta->raw_mode) { |
924 | meta->access_size = access_size; | |
925 | meta->regno = regno; | |
926 | return 0; | |
927 | } | |
928 | ||
17a52670 | 929 | for (i = 0; i < access_size; i++) { |
9c399760 | 930 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
17a52670 AS |
931 | verbose("invalid indirect read from stack off %d+%d size %d\n", |
932 | off, i, access_size); | |
933 | return -EACCES; | |
934 | } | |
935 | } | |
936 | return 0; | |
937 | } | |
938 | ||
939 | static int check_func_arg(struct verifier_env *env, u32 regno, | |
33ff9823 DB |
940 | enum bpf_arg_type arg_type, |
941 | struct bpf_call_arg_meta *meta) | |
17a52670 AS |
942 | { |
943 | struct reg_state *reg = env->cur_state.regs + regno; | |
944 | enum bpf_reg_type expected_type; | |
945 | int err = 0; | |
946 | ||
80f1d68c | 947 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
948 | return 0; |
949 | ||
950 | if (reg->type == NOT_INIT) { | |
951 | verbose("R%d !read_ok\n", regno); | |
952 | return -EACCES; | |
953 | } | |
954 | ||
1be7f75d AS |
955 | if (arg_type == ARG_ANYTHING) { |
956 | if (is_pointer_value(env, regno)) { | |
957 | verbose("R%d leaks addr into helper function\n", regno); | |
958 | return -EACCES; | |
959 | } | |
80f1d68c | 960 | return 0; |
1be7f75d | 961 | } |
80f1d68c | 962 | |
8e2fe1d9 | 963 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
964 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
965 | expected_type = PTR_TO_STACK; | |
8e2fe1d9 DB |
966 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
967 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
17a52670 AS |
968 | expected_type = CONST_IMM; |
969 | } else if (arg_type == ARG_CONST_MAP_PTR) { | |
970 | expected_type = CONST_PTR_TO_MAP; | |
608cd71a AS |
971 | } else if (arg_type == ARG_PTR_TO_CTX) { |
972 | expected_type = PTR_TO_CTX; | |
435faee1 DB |
973 | } else if (arg_type == ARG_PTR_TO_STACK || |
974 | arg_type == ARG_PTR_TO_RAW_STACK) { | |
8e2fe1d9 DB |
975 | expected_type = PTR_TO_STACK; |
976 | /* One exception here. In case function allows for NULL to be | |
977 | * passed in as argument, it's a CONST_IMM type. Final test | |
978 | * happens during stack boundary checking. | |
979 | */ | |
980 | if (reg->type == CONST_IMM && reg->imm == 0) | |
981 | expected_type = CONST_IMM; | |
435faee1 | 982 | meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK; |
17a52670 AS |
983 | } else { |
984 | verbose("unsupported arg_type %d\n", arg_type); | |
985 | return -EFAULT; | |
986 | } | |
987 | ||
988 | if (reg->type != expected_type) { | |
989 | verbose("R%d type=%s expected=%s\n", regno, | |
990 | reg_type_str[reg->type], reg_type_str[expected_type]); | |
991 | return -EACCES; | |
992 | } | |
993 | ||
994 | if (arg_type == ARG_CONST_MAP_PTR) { | |
995 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 996 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
997 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
998 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
999 | * check that [key, key + map->key_size) are within | |
1000 | * stack limits and initialized | |
1001 | */ | |
33ff9823 | 1002 | if (!meta->map_ptr) { |
17a52670 AS |
1003 | /* in function declaration map_ptr must come before |
1004 | * map_key, so that it's verified and known before | |
1005 | * we have to check map_key here. Otherwise it means | |
1006 | * that kernel subsystem misconfigured verifier | |
1007 | */ | |
1008 | verbose("invalid map_ptr to access map->key\n"); | |
1009 | return -EACCES; | |
1010 | } | |
33ff9823 | 1011 | err = check_stack_boundary(env, regno, meta->map_ptr->key_size, |
435faee1 | 1012 | false, NULL); |
17a52670 AS |
1013 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1014 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1015 | * check [value, value + map->value_size) validity | |
1016 | */ | |
33ff9823 | 1017 | if (!meta->map_ptr) { |
17a52670 AS |
1018 | /* kernel subsystem misconfigured verifier */ |
1019 | verbose("invalid map_ptr to access map->value\n"); | |
1020 | return -EACCES; | |
1021 | } | |
33ff9823 | 1022 | err = check_stack_boundary(env, regno, |
435faee1 DB |
1023 | meta->map_ptr->value_size, |
1024 | false, NULL); | |
8e2fe1d9 DB |
1025 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
1026 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
1027 | bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO); | |
17a52670 | 1028 | |
17a52670 AS |
1029 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1030 | * from stack pointer 'buf'. Check it | |
1031 | * note: regno == len, regno - 1 == buf | |
1032 | */ | |
1033 | if (regno == 0) { | |
1034 | /* kernel subsystem misconfigured verifier */ | |
1035 | verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); | |
1036 | return -EACCES; | |
1037 | } | |
8e2fe1d9 | 1038 | err = check_stack_boundary(env, regno - 1, reg->imm, |
435faee1 | 1039 | zero_size_allowed, meta); |
17a52670 AS |
1040 | } |
1041 | ||
1042 | return err; | |
1043 | } | |
1044 | ||
35578d79 KX |
1045 | static int check_map_func_compatibility(struct bpf_map *map, int func_id) |
1046 | { | |
35578d79 KX |
1047 | if (!map) |
1048 | return 0; | |
1049 | ||
6aff67c8 AS |
1050 | /* We need a two way check, first is from map perspective ... */ |
1051 | switch (map->map_type) { | |
1052 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1053 | if (func_id != BPF_FUNC_tail_call) | |
1054 | goto error; | |
1055 | break; | |
1056 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1057 | if (func_id != BPF_FUNC_perf_event_read && | |
1058 | func_id != BPF_FUNC_perf_event_output) | |
1059 | goto error; | |
1060 | break; | |
1061 | case BPF_MAP_TYPE_STACK_TRACE: | |
1062 | if (func_id != BPF_FUNC_get_stackid) | |
1063 | goto error; | |
1064 | break; | |
1065 | default: | |
1066 | break; | |
1067 | } | |
1068 | ||
1069 | /* ... and second from the function itself. */ | |
1070 | switch (func_id) { | |
1071 | case BPF_FUNC_tail_call: | |
1072 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1073 | goto error; | |
1074 | break; | |
1075 | case BPF_FUNC_perf_event_read: | |
1076 | case BPF_FUNC_perf_event_output: | |
1077 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) | |
1078 | goto error; | |
1079 | break; | |
1080 | case BPF_FUNC_get_stackid: | |
1081 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1082 | goto error; | |
1083 | break; | |
1084 | default: | |
1085 | break; | |
35578d79 KX |
1086 | } |
1087 | ||
1088 | return 0; | |
6aff67c8 AS |
1089 | error: |
1090 | verbose("cannot pass map_type %d into func %d\n", | |
1091 | map->map_type, func_id); | |
1092 | return -EINVAL; | |
35578d79 KX |
1093 | } |
1094 | ||
435faee1 DB |
1095 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1096 | { | |
1097 | int count = 0; | |
1098 | ||
1099 | if (fn->arg1_type == ARG_PTR_TO_RAW_STACK) | |
1100 | count++; | |
1101 | if (fn->arg2_type == ARG_PTR_TO_RAW_STACK) | |
1102 | count++; | |
1103 | if (fn->arg3_type == ARG_PTR_TO_RAW_STACK) | |
1104 | count++; | |
1105 | if (fn->arg4_type == ARG_PTR_TO_RAW_STACK) | |
1106 | count++; | |
1107 | if (fn->arg5_type == ARG_PTR_TO_RAW_STACK) | |
1108 | count++; | |
1109 | ||
1110 | return count > 1 ? -EINVAL : 0; | |
1111 | } | |
1112 | ||
969bf05e AS |
1113 | static void clear_all_pkt_pointers(struct verifier_env *env) |
1114 | { | |
1115 | struct verifier_state *state = &env->cur_state; | |
1116 | struct reg_state *regs = state->regs, *reg; | |
1117 | int i; | |
1118 | ||
1119 | for (i = 0; i < MAX_BPF_REG; i++) | |
1120 | if (regs[i].type == PTR_TO_PACKET || | |
1121 | regs[i].type == PTR_TO_PACKET_END) | |
1122 | mark_reg_unknown_value(regs, i); | |
1123 | ||
1124 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1125 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1126 | continue; | |
1127 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1128 | if (reg->type != PTR_TO_PACKET && | |
1129 | reg->type != PTR_TO_PACKET_END) | |
1130 | continue; | |
1131 | reg->type = UNKNOWN_VALUE; | |
1132 | reg->imm = 0; | |
1133 | } | |
1134 | } | |
1135 | ||
17a52670 AS |
1136 | static int check_call(struct verifier_env *env, int func_id) |
1137 | { | |
1138 | struct verifier_state *state = &env->cur_state; | |
1139 | const struct bpf_func_proto *fn = NULL; | |
1140 | struct reg_state *regs = state->regs; | |
17a52670 | 1141 | struct reg_state *reg; |
33ff9823 | 1142 | struct bpf_call_arg_meta meta; |
969bf05e | 1143 | bool changes_data; |
17a52670 AS |
1144 | int i, err; |
1145 | ||
1146 | /* find function prototype */ | |
1147 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
1148 | verbose("invalid func %d\n", func_id); | |
1149 | return -EINVAL; | |
1150 | } | |
1151 | ||
1152 | if (env->prog->aux->ops->get_func_proto) | |
1153 | fn = env->prog->aux->ops->get_func_proto(func_id); | |
1154 | ||
1155 | if (!fn) { | |
1156 | verbose("unknown func %d\n", func_id); | |
1157 | return -EINVAL; | |
1158 | } | |
1159 | ||
1160 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1161 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
17a52670 AS |
1162 | verbose("cannot call GPL only function from proprietary program\n"); |
1163 | return -EINVAL; | |
1164 | } | |
1165 | ||
969bf05e AS |
1166 | changes_data = bpf_helper_changes_skb_data(fn->func); |
1167 | ||
33ff9823 DB |
1168 | memset(&meta, 0, sizeof(meta)); |
1169 | ||
435faee1 DB |
1170 | /* We only support one arg being in raw mode at the moment, which |
1171 | * is sufficient for the helper functions we have right now. | |
1172 | */ | |
1173 | err = check_raw_mode(fn); | |
1174 | if (err) { | |
1175 | verbose("kernel subsystem misconfigured func %d\n", func_id); | |
1176 | return err; | |
1177 | } | |
1178 | ||
17a52670 | 1179 | /* check args */ |
33ff9823 | 1180 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1181 | if (err) |
1182 | return err; | |
33ff9823 | 1183 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1184 | if (err) |
1185 | return err; | |
33ff9823 | 1186 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1187 | if (err) |
1188 | return err; | |
33ff9823 | 1189 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1190 | if (err) |
1191 | return err; | |
33ff9823 | 1192 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1193 | if (err) |
1194 | return err; | |
1195 | ||
435faee1 DB |
1196 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1197 | * is inferred from register state. | |
1198 | */ | |
1199 | for (i = 0; i < meta.access_size; i++) { | |
1200 | err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); | |
1201 | if (err) | |
1202 | return err; | |
1203 | } | |
1204 | ||
17a52670 AS |
1205 | /* reset caller saved regs */ |
1206 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
1207 | reg = regs + caller_saved[i]; | |
1208 | reg->type = NOT_INIT; | |
1209 | reg->imm = 0; | |
1210 | } | |
1211 | ||
1212 | /* update return register */ | |
1213 | if (fn->ret_type == RET_INTEGER) { | |
1214 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1215 | } else if (fn->ret_type == RET_VOID) { | |
1216 | regs[BPF_REG_0].type = NOT_INIT; | |
1217 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
1218 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; | |
1219 | /* remember map_ptr, so that check_map_access() | |
1220 | * can check 'value_size' boundary of memory access | |
1221 | * to map element returned from bpf_map_lookup_elem() | |
1222 | */ | |
33ff9823 | 1223 | if (meta.map_ptr == NULL) { |
17a52670 AS |
1224 | verbose("kernel subsystem misconfigured verifier\n"); |
1225 | return -EINVAL; | |
1226 | } | |
33ff9823 | 1227 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
17a52670 AS |
1228 | } else { |
1229 | verbose("unknown return type %d of func %d\n", | |
1230 | fn->ret_type, func_id); | |
1231 | return -EINVAL; | |
1232 | } | |
04fd61ab | 1233 | |
33ff9823 | 1234 | err = check_map_func_compatibility(meta.map_ptr, func_id); |
35578d79 KX |
1235 | if (err) |
1236 | return err; | |
04fd61ab | 1237 | |
969bf05e AS |
1238 | if (changes_data) |
1239 | clear_all_pkt_pointers(env); | |
1240 | return 0; | |
1241 | } | |
1242 | ||
1243 | static int check_packet_ptr_add(struct verifier_env *env, struct bpf_insn *insn) | |
1244 | { | |
1245 | struct reg_state *regs = env->cur_state.regs; | |
1246 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1247 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1b9b69ec | 1248 | struct reg_state tmp_reg; |
969bf05e AS |
1249 | s32 imm; |
1250 | ||
1251 | if (BPF_SRC(insn->code) == BPF_K) { | |
1252 | /* pkt_ptr += imm */ | |
1253 | imm = insn->imm; | |
1254 | ||
1255 | add_imm: | |
1256 | if (imm <= 0) { | |
1257 | verbose("addition of negative constant to packet pointer is not allowed\n"); | |
1258 | return -EACCES; | |
1259 | } | |
1260 | if (imm >= MAX_PACKET_OFF || | |
1261 | imm + dst_reg->off >= MAX_PACKET_OFF) { | |
1262 | verbose("constant %d is too large to add to packet pointer\n", | |
1263 | imm); | |
1264 | return -EACCES; | |
1265 | } | |
1266 | /* a constant was added to pkt_ptr. | |
1267 | * Remember it while keeping the same 'id' | |
1268 | */ | |
1269 | dst_reg->off += imm; | |
1270 | } else { | |
1b9b69ec AS |
1271 | if (src_reg->type == PTR_TO_PACKET) { |
1272 | /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ | |
1273 | tmp_reg = *dst_reg; /* save r7 state */ | |
1274 | *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ | |
1275 | src_reg = &tmp_reg; /* pretend it's src_reg state */ | |
1276 | /* if the checks below reject it, the copy won't matter, | |
1277 | * since we're rejecting the whole program. If all ok, | |
1278 | * then imm22 state will be added to r7 | |
1279 | * and r7 will be pkt(id=0,off=22,r=62) while | |
1280 | * r6 will stay as pkt(id=0,off=0,r=62) | |
1281 | */ | |
1282 | } | |
1283 | ||
969bf05e AS |
1284 | if (src_reg->type == CONST_IMM) { |
1285 | /* pkt_ptr += reg where reg is known constant */ | |
1286 | imm = src_reg->imm; | |
1287 | goto add_imm; | |
1288 | } | |
1289 | /* disallow pkt_ptr += reg | |
1290 | * if reg is not uknown_value with guaranteed zero upper bits | |
1291 | * otherwise pkt_ptr may overflow and addition will become | |
1292 | * subtraction which is not allowed | |
1293 | */ | |
1294 | if (src_reg->type != UNKNOWN_VALUE) { | |
1295 | verbose("cannot add '%s' to ptr_to_packet\n", | |
1296 | reg_type_str[src_reg->type]); | |
1297 | return -EACCES; | |
1298 | } | |
1299 | if (src_reg->imm < 48) { | |
1300 | verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", | |
1301 | src_reg->imm); | |
1302 | return -EACCES; | |
1303 | } | |
1304 | /* dst_reg stays as pkt_ptr type and since some positive | |
1305 | * integer value was added to the pointer, increment its 'id' | |
1306 | */ | |
1307 | dst_reg->id++; | |
1308 | ||
1309 | /* something was added to pkt_ptr, set range and off to zero */ | |
1310 | dst_reg->off = 0; | |
1311 | dst_reg->range = 0; | |
1312 | } | |
1313 | return 0; | |
1314 | } | |
1315 | ||
1316 | static int evaluate_reg_alu(struct verifier_env *env, struct bpf_insn *insn) | |
1317 | { | |
1318 | struct reg_state *regs = env->cur_state.regs; | |
1319 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1320 | u8 opcode = BPF_OP(insn->code); | |
1321 | s64 imm_log2; | |
1322 | ||
1323 | /* for type == UNKNOWN_VALUE: | |
1324 | * imm > 0 -> number of zero upper bits | |
1325 | * imm == 0 -> don't track which is the same as all bits can be non-zero | |
1326 | */ | |
1327 | ||
1328 | if (BPF_SRC(insn->code) == BPF_X) { | |
1329 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1330 | ||
1331 | if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && | |
1332 | dst_reg->imm && opcode == BPF_ADD) { | |
1333 | /* dreg += sreg | |
1334 | * where both have zero upper bits. Adding them | |
1335 | * can only result making one more bit non-zero | |
1336 | * in the larger value. | |
1337 | * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) | |
1338 | * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) | |
1339 | */ | |
1340 | dst_reg->imm = min(dst_reg->imm, src_reg->imm); | |
1341 | dst_reg->imm--; | |
1342 | return 0; | |
1343 | } | |
1344 | if (src_reg->type == CONST_IMM && src_reg->imm > 0 && | |
1345 | dst_reg->imm && opcode == BPF_ADD) { | |
1346 | /* dreg += sreg | |
1347 | * where dreg has zero upper bits and sreg is const. | |
1348 | * Adding them can only result making one more bit | |
1349 | * non-zero in the larger value. | |
1350 | */ | |
1351 | imm_log2 = __ilog2_u64((long long)src_reg->imm); | |
1352 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1353 | dst_reg->imm--; | |
1354 | return 0; | |
1355 | } | |
1356 | /* all other cases non supported yet, just mark dst_reg */ | |
1357 | dst_reg->imm = 0; | |
1358 | return 0; | |
1359 | } | |
1360 | ||
1361 | /* sign extend 32-bit imm into 64-bit to make sure that | |
1362 | * negative values occupy bit 63. Note ilog2() would have | |
1363 | * been incorrect, since sizeof(insn->imm) == 4 | |
1364 | */ | |
1365 | imm_log2 = __ilog2_u64((long long)insn->imm); | |
1366 | ||
1367 | if (dst_reg->imm && opcode == BPF_LSH) { | |
1368 | /* reg <<= imm | |
1369 | * if reg was a result of 2 byte load, then its imm == 48 | |
1370 | * which means that upper 48 bits are zero and shifting this reg | |
1371 | * left by 4 would mean that upper 44 bits are still zero | |
1372 | */ | |
1373 | dst_reg->imm -= insn->imm; | |
1374 | } else if (dst_reg->imm && opcode == BPF_MUL) { | |
1375 | /* reg *= imm | |
1376 | * if multiplying by 14 subtract 4 | |
1377 | * This is conservative calculation of upper zero bits. | |
1378 | * It's not trying to special case insn->imm == 1 or 0 cases | |
1379 | */ | |
1380 | dst_reg->imm -= imm_log2 + 1; | |
1381 | } else if (opcode == BPF_AND) { | |
1382 | /* reg &= imm */ | |
1383 | dst_reg->imm = 63 - imm_log2; | |
1384 | } else if (dst_reg->imm && opcode == BPF_ADD) { | |
1385 | /* reg += imm */ | |
1386 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1387 | dst_reg->imm--; | |
1388 | } else if (opcode == BPF_RSH) { | |
1389 | /* reg >>= imm | |
1390 | * which means that after right shift, upper bits will be zero | |
1391 | * note that verifier already checked that | |
1392 | * 0 <= imm < 64 for shift insn | |
1393 | */ | |
1394 | dst_reg->imm += insn->imm; | |
1395 | if (unlikely(dst_reg->imm > 64)) | |
1396 | /* some dumb code did: | |
1397 | * r2 = *(u32 *)mem; | |
1398 | * r2 >>= 32; | |
1399 | * and all bits are zero now */ | |
1400 | dst_reg->imm = 64; | |
1401 | } else { | |
1402 | /* all other alu ops, means that we don't know what will | |
1403 | * happen to the value, mark it with unknown number of zero bits | |
1404 | */ | |
1405 | dst_reg->imm = 0; | |
1406 | } | |
1407 | ||
1408 | if (dst_reg->imm < 0) { | |
1409 | /* all 64 bits of the register can contain non-zero bits | |
1410 | * and such value cannot be added to ptr_to_packet, since it | |
1411 | * may overflow, mark it as unknown to avoid further eval | |
1412 | */ | |
1413 | dst_reg->imm = 0; | |
1414 | } | |
1415 | return 0; | |
1416 | } | |
1417 | ||
1418 | static int evaluate_reg_imm_alu(struct verifier_env *env, struct bpf_insn *insn) | |
1419 | { | |
1420 | struct reg_state *regs = env->cur_state.regs; | |
1421 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1422 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1423 | u8 opcode = BPF_OP(insn->code); | |
1424 | ||
1425 | /* dst_reg->type == CONST_IMM here, simulate execution of 'add' insn. | |
1426 | * Don't care about overflow or negative values, just add them | |
1427 | */ | |
1428 | if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) | |
1429 | dst_reg->imm += insn->imm; | |
1430 | else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && | |
1431 | src_reg->type == CONST_IMM) | |
1432 | dst_reg->imm += src_reg->imm; | |
1433 | else | |
1434 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1435 | return 0; |
1436 | } | |
1437 | ||
1438 | /* check validity of 32-bit and 64-bit arithmetic operations */ | |
1be7f75d | 1439 | static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn) |
17a52670 | 1440 | { |
1a0dc1ac | 1441 | struct reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1442 | u8 opcode = BPF_OP(insn->code); |
1443 | int err; | |
1444 | ||
1445 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
1446 | if (opcode == BPF_NEG) { | |
1447 | if (BPF_SRC(insn->code) != 0 || | |
1448 | insn->src_reg != BPF_REG_0 || | |
1449 | insn->off != 0 || insn->imm != 0) { | |
1450 | verbose("BPF_NEG uses reserved fields\n"); | |
1451 | return -EINVAL; | |
1452 | } | |
1453 | } else { | |
1454 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
1455 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { | |
1456 | verbose("BPF_END uses reserved fields\n"); | |
1457 | return -EINVAL; | |
1458 | } | |
1459 | } | |
1460 | ||
1461 | /* check src operand */ | |
1462 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1463 | if (err) | |
1464 | return err; | |
1465 | ||
1be7f75d AS |
1466 | if (is_pointer_value(env, insn->dst_reg)) { |
1467 | verbose("R%d pointer arithmetic prohibited\n", | |
1468 | insn->dst_reg); | |
1469 | return -EACCES; | |
1470 | } | |
1471 | ||
17a52670 AS |
1472 | /* check dest operand */ |
1473 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1474 | if (err) | |
1475 | return err; | |
1476 | ||
1477 | } else if (opcode == BPF_MOV) { | |
1478 | ||
1479 | if (BPF_SRC(insn->code) == BPF_X) { | |
1480 | if (insn->imm != 0 || insn->off != 0) { | |
1481 | verbose("BPF_MOV uses reserved fields\n"); | |
1482 | return -EINVAL; | |
1483 | } | |
1484 | ||
1485 | /* check src operand */ | |
1486 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1487 | if (err) | |
1488 | return err; | |
1489 | } else { | |
1490 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1491 | verbose("BPF_MOV uses reserved fields\n"); | |
1492 | return -EINVAL; | |
1493 | } | |
1494 | } | |
1495 | ||
1496 | /* check dest operand */ | |
1497 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1498 | if (err) | |
1499 | return err; | |
1500 | ||
1501 | if (BPF_SRC(insn->code) == BPF_X) { | |
1502 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
1503 | /* case: R1 = R2 | |
1504 | * copy register state to dest reg | |
1505 | */ | |
1506 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
1507 | } else { | |
1be7f75d AS |
1508 | if (is_pointer_value(env, insn->src_reg)) { |
1509 | verbose("R%d partial copy of pointer\n", | |
1510 | insn->src_reg); | |
1511 | return -EACCES; | |
1512 | } | |
17a52670 AS |
1513 | regs[insn->dst_reg].type = UNKNOWN_VALUE; |
1514 | regs[insn->dst_reg].map_ptr = NULL; | |
1515 | } | |
1516 | } else { | |
1517 | /* case: R = imm | |
1518 | * remember the value we stored into this reg | |
1519 | */ | |
1520 | regs[insn->dst_reg].type = CONST_IMM; | |
1521 | regs[insn->dst_reg].imm = insn->imm; | |
1522 | } | |
1523 | ||
1524 | } else if (opcode > BPF_END) { | |
1525 | verbose("invalid BPF_ALU opcode %x\n", opcode); | |
1526 | return -EINVAL; | |
1527 | ||
1528 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
1529 | ||
17a52670 AS |
1530 | if (BPF_SRC(insn->code) == BPF_X) { |
1531 | if (insn->imm != 0 || insn->off != 0) { | |
1532 | verbose("BPF_ALU uses reserved fields\n"); | |
1533 | return -EINVAL; | |
1534 | } | |
1535 | /* check src1 operand */ | |
1536 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1537 | if (err) | |
1538 | return err; | |
1539 | } else { | |
1540 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1541 | verbose("BPF_ALU uses reserved fields\n"); | |
1542 | return -EINVAL; | |
1543 | } | |
1544 | } | |
1545 | ||
1546 | /* check src2 operand */ | |
1547 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1548 | if (err) | |
1549 | return err; | |
1550 | ||
1551 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
1552 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
1553 | verbose("div by zero\n"); | |
1554 | return -EINVAL; | |
1555 | } | |
1556 | ||
229394e8 RV |
1557 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
1558 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
1559 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
1560 | ||
1561 | if (insn->imm < 0 || insn->imm >= size) { | |
1562 | verbose("invalid shift %d\n", insn->imm); | |
1563 | return -EINVAL; | |
1564 | } | |
1565 | } | |
1566 | ||
1a0dc1ac AS |
1567 | /* check dest operand */ |
1568 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
1569 | if (err) | |
1570 | return err; | |
1571 | ||
1572 | dst_reg = ®s[insn->dst_reg]; | |
1573 | ||
17a52670 AS |
1574 | /* pattern match 'bpf_add Rx, imm' instruction */ |
1575 | if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && | |
1a0dc1ac AS |
1576 | dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { |
1577 | dst_reg->type = PTR_TO_STACK; | |
1578 | dst_reg->imm = insn->imm; | |
1579 | return 0; | |
969bf05e AS |
1580 | } else if (opcode == BPF_ADD && |
1581 | BPF_CLASS(insn->code) == BPF_ALU64 && | |
1b9b69ec AS |
1582 | (dst_reg->type == PTR_TO_PACKET || |
1583 | (BPF_SRC(insn->code) == BPF_X && | |
1584 | regs[insn->src_reg].type == PTR_TO_PACKET))) { | |
969bf05e AS |
1585 | /* ptr_to_packet += K|X */ |
1586 | return check_packet_ptr_add(env, insn); | |
1587 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1588 | dst_reg->type == UNKNOWN_VALUE && | |
1589 | env->allow_ptr_leaks) { | |
1590 | /* unknown += K|X */ | |
1591 | return evaluate_reg_alu(env, insn); | |
1592 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1593 | dst_reg->type == CONST_IMM && | |
1594 | env->allow_ptr_leaks) { | |
1595 | /* reg_imm += K|X */ | |
1596 | return evaluate_reg_imm_alu(env, insn); | |
1be7f75d AS |
1597 | } else if (is_pointer_value(env, insn->dst_reg)) { |
1598 | verbose("R%d pointer arithmetic prohibited\n", | |
1599 | insn->dst_reg); | |
1600 | return -EACCES; | |
1601 | } else if (BPF_SRC(insn->code) == BPF_X && | |
1602 | is_pointer_value(env, insn->src_reg)) { | |
1603 | verbose("R%d pointer arithmetic prohibited\n", | |
1604 | insn->src_reg); | |
1605 | return -EACCES; | |
1606 | } | |
17a52670 | 1607 | |
1a0dc1ac AS |
1608 | /* mark dest operand */ |
1609 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1610 | } |
1611 | ||
1612 | return 0; | |
1613 | } | |
1614 | ||
969bf05e AS |
1615 | static void find_good_pkt_pointers(struct verifier_env *env, |
1616 | struct reg_state *dst_reg) | |
1617 | { | |
1618 | struct verifier_state *state = &env->cur_state; | |
1619 | struct reg_state *regs = state->regs, *reg; | |
1620 | int i; | |
1621 | /* r2 = r3; | |
1622 | * r2 += 8 | |
1623 | * if (r2 > pkt_end) goto somewhere | |
1624 | * r2 == dst_reg, pkt_end == src_reg, | |
1625 | * r2=pkt(id=n,off=8,r=0) | |
1626 | * r3=pkt(id=n,off=0,r=0) | |
1627 | * find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
1628 | * so that range of bytes [r3, r3 + 8) is safe to access | |
1629 | */ | |
1630 | for (i = 0; i < MAX_BPF_REG; i++) | |
1631 | if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) | |
1632 | regs[i].range = dst_reg->off; | |
1633 | ||
1634 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1635 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1636 | continue; | |
1637 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1638 | if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) | |
1639 | reg->range = dst_reg->off; | |
1640 | } | |
1641 | } | |
1642 | ||
17a52670 AS |
1643 | static int check_cond_jmp_op(struct verifier_env *env, |
1644 | struct bpf_insn *insn, int *insn_idx) | |
1645 | { | |
1a0dc1ac | 1646 | struct reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1647 | struct verifier_state *other_branch; |
1648 | u8 opcode = BPF_OP(insn->code); | |
1649 | int err; | |
1650 | ||
1651 | if (opcode > BPF_EXIT) { | |
1652 | verbose("invalid BPF_JMP opcode %x\n", opcode); | |
1653 | return -EINVAL; | |
1654 | } | |
1655 | ||
1656 | if (BPF_SRC(insn->code) == BPF_X) { | |
1657 | if (insn->imm != 0) { | |
1658 | verbose("BPF_JMP uses reserved fields\n"); | |
1659 | return -EINVAL; | |
1660 | } | |
1661 | ||
1662 | /* check src1 operand */ | |
1663 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1664 | if (err) | |
1665 | return err; | |
1be7f75d AS |
1666 | |
1667 | if (is_pointer_value(env, insn->src_reg)) { | |
1668 | verbose("R%d pointer comparison prohibited\n", | |
1669 | insn->src_reg); | |
1670 | return -EACCES; | |
1671 | } | |
17a52670 AS |
1672 | } else { |
1673 | if (insn->src_reg != BPF_REG_0) { | |
1674 | verbose("BPF_JMP uses reserved fields\n"); | |
1675 | return -EINVAL; | |
1676 | } | |
1677 | } | |
1678 | ||
1679 | /* check src2 operand */ | |
1680 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1681 | if (err) | |
1682 | return err; | |
1683 | ||
1a0dc1ac AS |
1684 | dst_reg = ®s[insn->dst_reg]; |
1685 | ||
17a52670 AS |
1686 | /* detect if R == 0 where R was initialized to zero earlier */ |
1687 | if (BPF_SRC(insn->code) == BPF_K && | |
1688 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
1a0dc1ac | 1689 | dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { |
17a52670 AS |
1690 | if (opcode == BPF_JEQ) { |
1691 | /* if (imm == imm) goto pc+off; | |
1692 | * only follow the goto, ignore fall-through | |
1693 | */ | |
1694 | *insn_idx += insn->off; | |
1695 | return 0; | |
1696 | } else { | |
1697 | /* if (imm != imm) goto pc+off; | |
1698 | * only follow fall-through branch, since | |
1699 | * that's where the program will go | |
1700 | */ | |
1701 | return 0; | |
1702 | } | |
1703 | } | |
1704 | ||
1705 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
1706 | if (!other_branch) | |
1707 | return -EFAULT; | |
1708 | ||
1709 | /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */ | |
1710 | if (BPF_SRC(insn->code) == BPF_K && | |
1a0dc1ac AS |
1711 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
1712 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
17a52670 AS |
1713 | if (opcode == BPF_JEQ) { |
1714 | /* next fallthrough insn can access memory via | |
1715 | * this register | |
1716 | */ | |
1717 | regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; | |
1718 | /* branch targer cannot access it, since reg == 0 */ | |
735b4333 AS |
1719 | mark_reg_unknown_value(other_branch->regs, |
1720 | insn->dst_reg); | |
17a52670 AS |
1721 | } else { |
1722 | other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; | |
735b4333 | 1723 | mark_reg_unknown_value(regs, insn->dst_reg); |
17a52670 | 1724 | } |
969bf05e AS |
1725 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
1726 | dst_reg->type == PTR_TO_PACKET && | |
1727 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
1728 | find_good_pkt_pointers(env, dst_reg); | |
1be7f75d AS |
1729 | } else if (is_pointer_value(env, insn->dst_reg)) { |
1730 | verbose("R%d pointer comparison prohibited\n", insn->dst_reg); | |
1731 | return -EACCES; | |
17a52670 AS |
1732 | } |
1733 | if (log_level) | |
1a0dc1ac | 1734 | print_verifier_state(&env->cur_state); |
17a52670 AS |
1735 | return 0; |
1736 | } | |
1737 | ||
0246e64d AS |
1738 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
1739 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
1740 | { | |
1741 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
1742 | ||
1743 | return (struct bpf_map *) (unsigned long) imm64; | |
1744 | } | |
1745 | ||
17a52670 AS |
1746 | /* verify BPF_LD_IMM64 instruction */ |
1747 | static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn) | |
1748 | { | |
1749 | struct reg_state *regs = env->cur_state.regs; | |
1750 | int err; | |
1751 | ||
1752 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
1753 | verbose("invalid BPF_LD_IMM insn\n"); | |
1754 | return -EINVAL; | |
1755 | } | |
1756 | if (insn->off != 0) { | |
1757 | verbose("BPF_LD_IMM64 uses reserved fields\n"); | |
1758 | return -EINVAL; | |
1759 | } | |
1760 | ||
1761 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1762 | if (err) | |
1763 | return err; | |
1764 | ||
1765 | if (insn->src_reg == 0) | |
1766 | /* generic move 64-bit immediate into a register */ | |
1767 | return 0; | |
1768 | ||
1769 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
1770 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
1771 | ||
1772 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
1773 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
1774 | return 0; | |
1775 | } | |
1776 | ||
96be4325 DB |
1777 | static bool may_access_skb(enum bpf_prog_type type) |
1778 | { | |
1779 | switch (type) { | |
1780 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
1781 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 1782 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
1783 | return true; |
1784 | default: | |
1785 | return false; | |
1786 | } | |
1787 | } | |
1788 | ||
ddd872bc AS |
1789 | /* verify safety of LD_ABS|LD_IND instructions: |
1790 | * - they can only appear in the programs where ctx == skb | |
1791 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
1792 | * preserve R6-R9, and store return value into R0 | |
1793 | * | |
1794 | * Implicit input: | |
1795 | * ctx == skb == R6 == CTX | |
1796 | * | |
1797 | * Explicit input: | |
1798 | * SRC == any register | |
1799 | * IMM == 32-bit immediate | |
1800 | * | |
1801 | * Output: | |
1802 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
1803 | */ | |
1804 | static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn) | |
1805 | { | |
1806 | struct reg_state *regs = env->cur_state.regs; | |
1807 | u8 mode = BPF_MODE(insn->code); | |
1808 | struct reg_state *reg; | |
1809 | int i, err; | |
1810 | ||
24701ece | 1811 | if (!may_access_skb(env->prog->type)) { |
1a0dc1ac | 1812 | verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
1813 | return -EINVAL; |
1814 | } | |
1815 | ||
1816 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 1817 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 1818 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
1a0dc1ac | 1819 | verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
1820 | return -EINVAL; |
1821 | } | |
1822 | ||
1823 | /* check whether implicit source operand (register R6) is readable */ | |
1824 | err = check_reg_arg(regs, BPF_REG_6, SRC_OP); | |
1825 | if (err) | |
1826 | return err; | |
1827 | ||
1828 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
1829 | verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
1830 | return -EINVAL; | |
1831 | } | |
1832 | ||
1833 | if (mode == BPF_IND) { | |
1834 | /* check explicit source operand */ | |
1835 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1836 | if (err) | |
1837 | return err; | |
1838 | } | |
1839 | ||
1840 | /* reset caller saved regs to unreadable */ | |
1841 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
1842 | reg = regs + caller_saved[i]; | |
1843 | reg->type = NOT_INIT; | |
1844 | reg->imm = 0; | |
1845 | } | |
1846 | ||
1847 | /* mark destination R0 register as readable, since it contains | |
1848 | * the value fetched from the packet | |
1849 | */ | |
1850 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1851 | return 0; | |
1852 | } | |
1853 | ||
475fb78f AS |
1854 | /* non-recursive DFS pseudo code |
1855 | * 1 procedure DFS-iterative(G,v): | |
1856 | * 2 label v as discovered | |
1857 | * 3 let S be a stack | |
1858 | * 4 S.push(v) | |
1859 | * 5 while S is not empty | |
1860 | * 6 t <- S.pop() | |
1861 | * 7 if t is what we're looking for: | |
1862 | * 8 return t | |
1863 | * 9 for all edges e in G.adjacentEdges(t) do | |
1864 | * 10 if edge e is already labelled | |
1865 | * 11 continue with the next edge | |
1866 | * 12 w <- G.adjacentVertex(t,e) | |
1867 | * 13 if vertex w is not discovered and not explored | |
1868 | * 14 label e as tree-edge | |
1869 | * 15 label w as discovered | |
1870 | * 16 S.push(w) | |
1871 | * 17 continue at 5 | |
1872 | * 18 else if vertex w is discovered | |
1873 | * 19 label e as back-edge | |
1874 | * 20 else | |
1875 | * 21 // vertex w is explored | |
1876 | * 22 label e as forward- or cross-edge | |
1877 | * 23 label t as explored | |
1878 | * 24 S.pop() | |
1879 | * | |
1880 | * convention: | |
1881 | * 0x10 - discovered | |
1882 | * 0x11 - discovered and fall-through edge labelled | |
1883 | * 0x12 - discovered and fall-through and branch edges labelled | |
1884 | * 0x20 - explored | |
1885 | */ | |
1886 | ||
1887 | enum { | |
1888 | DISCOVERED = 0x10, | |
1889 | EXPLORED = 0x20, | |
1890 | FALLTHROUGH = 1, | |
1891 | BRANCH = 2, | |
1892 | }; | |
1893 | ||
f1bca824 AS |
1894 | #define STATE_LIST_MARK ((struct verifier_state_list *) -1L) |
1895 | ||
475fb78f AS |
1896 | static int *insn_stack; /* stack of insns to process */ |
1897 | static int cur_stack; /* current stack index */ | |
1898 | static int *insn_state; | |
1899 | ||
1900 | /* t, w, e - match pseudo-code above: | |
1901 | * t - index of current instruction | |
1902 | * w - next instruction | |
1903 | * e - edge | |
1904 | */ | |
1905 | static int push_insn(int t, int w, int e, struct verifier_env *env) | |
1906 | { | |
1907 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
1908 | return 0; | |
1909 | ||
1910 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
1911 | return 0; | |
1912 | ||
1913 | if (w < 0 || w >= env->prog->len) { | |
1914 | verbose("jump out of range from insn %d to %d\n", t, w); | |
1915 | return -EINVAL; | |
1916 | } | |
1917 | ||
f1bca824 AS |
1918 | if (e == BRANCH) |
1919 | /* mark branch target for state pruning */ | |
1920 | env->explored_states[w] = STATE_LIST_MARK; | |
1921 | ||
475fb78f AS |
1922 | if (insn_state[w] == 0) { |
1923 | /* tree-edge */ | |
1924 | insn_state[t] = DISCOVERED | e; | |
1925 | insn_state[w] = DISCOVERED; | |
1926 | if (cur_stack >= env->prog->len) | |
1927 | return -E2BIG; | |
1928 | insn_stack[cur_stack++] = w; | |
1929 | return 1; | |
1930 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
1931 | verbose("back-edge from insn %d to %d\n", t, w); | |
1932 | return -EINVAL; | |
1933 | } else if (insn_state[w] == EXPLORED) { | |
1934 | /* forward- or cross-edge */ | |
1935 | insn_state[t] = DISCOVERED | e; | |
1936 | } else { | |
1937 | verbose("insn state internal bug\n"); | |
1938 | return -EFAULT; | |
1939 | } | |
1940 | return 0; | |
1941 | } | |
1942 | ||
1943 | /* non-recursive depth-first-search to detect loops in BPF program | |
1944 | * loop == back-edge in directed graph | |
1945 | */ | |
1946 | static int check_cfg(struct verifier_env *env) | |
1947 | { | |
1948 | struct bpf_insn *insns = env->prog->insnsi; | |
1949 | int insn_cnt = env->prog->len; | |
1950 | int ret = 0; | |
1951 | int i, t; | |
1952 | ||
1953 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
1954 | if (!insn_state) | |
1955 | return -ENOMEM; | |
1956 | ||
1957 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
1958 | if (!insn_stack) { | |
1959 | kfree(insn_state); | |
1960 | return -ENOMEM; | |
1961 | } | |
1962 | ||
1963 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
1964 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
1965 | cur_stack = 1; | |
1966 | ||
1967 | peek_stack: | |
1968 | if (cur_stack == 0) | |
1969 | goto check_state; | |
1970 | t = insn_stack[cur_stack - 1]; | |
1971 | ||
1972 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
1973 | u8 opcode = BPF_OP(insns[t].code); | |
1974 | ||
1975 | if (opcode == BPF_EXIT) { | |
1976 | goto mark_explored; | |
1977 | } else if (opcode == BPF_CALL) { | |
1978 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
1979 | if (ret == 1) | |
1980 | goto peek_stack; | |
1981 | else if (ret < 0) | |
1982 | goto err_free; | |
07016151 DB |
1983 | if (t + 1 < insn_cnt) |
1984 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
1985 | } else if (opcode == BPF_JA) { |
1986 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
1987 | ret = -EINVAL; | |
1988 | goto err_free; | |
1989 | } | |
1990 | /* unconditional jump with single edge */ | |
1991 | ret = push_insn(t, t + insns[t].off + 1, | |
1992 | FALLTHROUGH, env); | |
1993 | if (ret == 1) | |
1994 | goto peek_stack; | |
1995 | else if (ret < 0) | |
1996 | goto err_free; | |
f1bca824 AS |
1997 | /* tell verifier to check for equivalent states |
1998 | * after every call and jump | |
1999 | */ | |
c3de6317 AS |
2000 | if (t + 1 < insn_cnt) |
2001 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2002 | } else { |
2003 | /* conditional jump with two edges */ | |
2004 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2005 | if (ret == 1) | |
2006 | goto peek_stack; | |
2007 | else if (ret < 0) | |
2008 | goto err_free; | |
2009 | ||
2010 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
2011 | if (ret == 1) | |
2012 | goto peek_stack; | |
2013 | else if (ret < 0) | |
2014 | goto err_free; | |
2015 | } | |
2016 | } else { | |
2017 | /* all other non-branch instructions with single | |
2018 | * fall-through edge | |
2019 | */ | |
2020 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2021 | if (ret == 1) | |
2022 | goto peek_stack; | |
2023 | else if (ret < 0) | |
2024 | goto err_free; | |
2025 | } | |
2026 | ||
2027 | mark_explored: | |
2028 | insn_state[t] = EXPLORED; | |
2029 | if (cur_stack-- <= 0) { | |
2030 | verbose("pop stack internal bug\n"); | |
2031 | ret = -EFAULT; | |
2032 | goto err_free; | |
2033 | } | |
2034 | goto peek_stack; | |
2035 | ||
2036 | check_state: | |
2037 | for (i = 0; i < insn_cnt; i++) { | |
2038 | if (insn_state[i] != EXPLORED) { | |
2039 | verbose("unreachable insn %d\n", i); | |
2040 | ret = -EINVAL; | |
2041 | goto err_free; | |
2042 | } | |
2043 | } | |
2044 | ret = 0; /* cfg looks good */ | |
2045 | ||
2046 | err_free: | |
2047 | kfree(insn_state); | |
2048 | kfree(insn_stack); | |
2049 | return ret; | |
2050 | } | |
2051 | ||
969bf05e AS |
2052 | /* the following conditions reduce the number of explored insns |
2053 | * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet | |
2054 | */ | |
2055 | static bool compare_ptrs_to_packet(struct reg_state *old, struct reg_state *cur) | |
2056 | { | |
2057 | if (old->id != cur->id) | |
2058 | return false; | |
2059 | ||
2060 | /* old ptr_to_packet is more conservative, since it allows smaller | |
2061 | * range. Ex: | |
2062 | * old(off=0,r=10) is equal to cur(off=0,r=20), because | |
2063 | * old(off=0,r=10) means that with range=10 the verifier proceeded | |
2064 | * further and found no issues with the program. Now we're in the same | |
2065 | * spot with cur(off=0,r=20), so we're safe too, since anything further | |
2066 | * will only be looking at most 10 bytes after this pointer. | |
2067 | */ | |
2068 | if (old->off == cur->off && old->range < cur->range) | |
2069 | return true; | |
2070 | ||
2071 | /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) | |
2072 | * since both cannot be used for packet access and safe(old) | |
2073 | * pointer has smaller off that could be used for further | |
2074 | * 'if (ptr > data_end)' check | |
2075 | * Ex: | |
2076 | * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean | |
2077 | * that we cannot access the packet. | |
2078 | * The safe range is: | |
2079 | * [ptr, ptr + range - off) | |
2080 | * so whenever off >=range, it means no safe bytes from this pointer. | |
2081 | * When comparing old->off <= cur->off, it means that older code | |
2082 | * went with smaller offset and that offset was later | |
2083 | * used to figure out the safe range after 'if (ptr > data_end)' check | |
2084 | * Say, 'old' state was explored like: | |
2085 | * ... R3(off=0, r=0) | |
2086 | * R4 = R3 + 20 | |
2087 | * ... now R4(off=20,r=0) <-- here | |
2088 | * if (R4 > data_end) | |
2089 | * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. | |
2090 | * ... the code further went all the way to bpf_exit. | |
2091 | * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). | |
2092 | * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier | |
2093 | * goes further, such cur_R4 will give larger safe packet range after | |
2094 | * 'if (R4 > data_end)' and all further insn were already good with r=20, | |
2095 | * so they will be good with r=30 and we can prune the search. | |
2096 | */ | |
2097 | if (old->off <= cur->off && | |
2098 | old->off >= old->range && cur->off >= cur->range) | |
2099 | return true; | |
2100 | ||
2101 | return false; | |
2102 | } | |
2103 | ||
f1bca824 AS |
2104 | /* compare two verifier states |
2105 | * | |
2106 | * all states stored in state_list are known to be valid, since | |
2107 | * verifier reached 'bpf_exit' instruction through them | |
2108 | * | |
2109 | * this function is called when verifier exploring different branches of | |
2110 | * execution popped from the state stack. If it sees an old state that has | |
2111 | * more strict register state and more strict stack state then this execution | |
2112 | * branch doesn't need to be explored further, since verifier already | |
2113 | * concluded that more strict state leads to valid finish. | |
2114 | * | |
2115 | * Therefore two states are equivalent if register state is more conservative | |
2116 | * and explored stack state is more conservative than the current one. | |
2117 | * Example: | |
2118 | * explored current | |
2119 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
2120 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
2121 | * | |
2122 | * In other words if current stack state (one being explored) has more | |
2123 | * valid slots than old one that already passed validation, it means | |
2124 | * the verifier can stop exploring and conclude that current state is valid too | |
2125 | * | |
2126 | * Similarly with registers. If explored state has register type as invalid | |
2127 | * whereas register type in current state is meaningful, it means that | |
2128 | * the current state will reach 'bpf_exit' instruction safely | |
2129 | */ | |
2130 | static bool states_equal(struct verifier_state *old, struct verifier_state *cur) | |
2131 | { | |
1a0dc1ac | 2132 | struct reg_state *rold, *rcur; |
f1bca824 AS |
2133 | int i; |
2134 | ||
2135 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
2136 | rold = &old->regs[i]; |
2137 | rcur = &cur->regs[i]; | |
2138 | ||
2139 | if (memcmp(rold, rcur, sizeof(*rold)) == 0) | |
2140 | continue; | |
2141 | ||
2142 | if (rold->type == NOT_INIT || | |
2143 | (rold->type == UNKNOWN_VALUE && rcur->type != NOT_INIT)) | |
2144 | continue; | |
2145 | ||
969bf05e AS |
2146 | if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && |
2147 | compare_ptrs_to_packet(rold, rcur)) | |
2148 | continue; | |
2149 | ||
1a0dc1ac | 2150 | return false; |
f1bca824 AS |
2151 | } |
2152 | ||
2153 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
2154 | if (old->stack_slot_type[i] == STACK_INVALID) |
2155 | continue; | |
2156 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
2157 | /* Ex: old explored (safe) state has STACK_SPILL in | |
2158 | * this stack slot, but current has has STACK_MISC -> | |
2159 | * this verifier states are not equivalent, | |
2160 | * return false to continue verification of this path | |
2161 | */ | |
f1bca824 | 2162 | return false; |
9c399760 AS |
2163 | if (i % BPF_REG_SIZE) |
2164 | continue; | |
2165 | if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], | |
2166 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
2167 | sizeof(old->spilled_regs[0]))) | |
2168 | /* when explored and current stack slot types are | |
2169 | * the same, check that stored pointers types | |
2170 | * are the same as well. | |
2171 | * Ex: explored safe path could have stored | |
2172 | * (struct reg_state) {.type = PTR_TO_STACK, .imm = -8} | |
2173 | * but current path has stored: | |
2174 | * (struct reg_state) {.type = PTR_TO_STACK, .imm = -16} | |
2175 | * such verifier states are not equivalent. | |
2176 | * return false to continue verification of this path | |
2177 | */ | |
2178 | return false; | |
2179 | else | |
2180 | continue; | |
f1bca824 AS |
2181 | } |
2182 | return true; | |
2183 | } | |
2184 | ||
2185 | static int is_state_visited(struct verifier_env *env, int insn_idx) | |
2186 | { | |
2187 | struct verifier_state_list *new_sl; | |
2188 | struct verifier_state_list *sl; | |
2189 | ||
2190 | sl = env->explored_states[insn_idx]; | |
2191 | if (!sl) | |
2192 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
2193 | * be doing state search here | |
2194 | */ | |
2195 | return 0; | |
2196 | ||
2197 | while (sl != STATE_LIST_MARK) { | |
2198 | if (states_equal(&sl->state, &env->cur_state)) | |
2199 | /* reached equivalent register/stack state, | |
2200 | * prune the search | |
2201 | */ | |
2202 | return 1; | |
2203 | sl = sl->next; | |
2204 | } | |
2205 | ||
2206 | /* there were no equivalent states, remember current one. | |
2207 | * technically the current state is not proven to be safe yet, | |
2208 | * but it will either reach bpf_exit (which means it's safe) or | |
2209 | * it will be rejected. Since there are no loops, we won't be | |
2210 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
2211 | */ | |
2212 | new_sl = kmalloc(sizeof(struct verifier_state_list), GFP_USER); | |
2213 | if (!new_sl) | |
2214 | return -ENOMEM; | |
2215 | ||
2216 | /* add new state to the head of linked list */ | |
2217 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
2218 | new_sl->next = env->explored_states[insn_idx]; | |
2219 | env->explored_states[insn_idx] = new_sl; | |
2220 | return 0; | |
2221 | } | |
2222 | ||
17a52670 AS |
2223 | static int do_check(struct verifier_env *env) |
2224 | { | |
2225 | struct verifier_state *state = &env->cur_state; | |
2226 | struct bpf_insn *insns = env->prog->insnsi; | |
2227 | struct reg_state *regs = state->regs; | |
2228 | int insn_cnt = env->prog->len; | |
2229 | int insn_idx, prev_insn_idx = 0; | |
2230 | int insn_processed = 0; | |
2231 | bool do_print_state = false; | |
2232 | ||
2233 | init_reg_state(regs); | |
2234 | insn_idx = 0; | |
2235 | for (;;) { | |
2236 | struct bpf_insn *insn; | |
2237 | u8 class; | |
2238 | int err; | |
2239 | ||
2240 | if (insn_idx >= insn_cnt) { | |
2241 | verbose("invalid insn idx %d insn_cnt %d\n", | |
2242 | insn_idx, insn_cnt); | |
2243 | return -EFAULT; | |
2244 | } | |
2245 | ||
2246 | insn = &insns[insn_idx]; | |
2247 | class = BPF_CLASS(insn->code); | |
2248 | ||
07016151 | 2249 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
17a52670 AS |
2250 | verbose("BPF program is too large. Proccessed %d insn\n", |
2251 | insn_processed); | |
2252 | return -E2BIG; | |
2253 | } | |
2254 | ||
f1bca824 AS |
2255 | err = is_state_visited(env, insn_idx); |
2256 | if (err < 0) | |
2257 | return err; | |
2258 | if (err == 1) { | |
2259 | /* found equivalent state, can prune the search */ | |
2260 | if (log_level) { | |
2261 | if (do_print_state) | |
2262 | verbose("\nfrom %d to %d: safe\n", | |
2263 | prev_insn_idx, insn_idx); | |
2264 | else | |
2265 | verbose("%d: safe\n", insn_idx); | |
2266 | } | |
2267 | goto process_bpf_exit; | |
2268 | } | |
2269 | ||
17a52670 AS |
2270 | if (log_level && do_print_state) { |
2271 | verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx); | |
1a0dc1ac | 2272 | print_verifier_state(&env->cur_state); |
17a52670 AS |
2273 | do_print_state = false; |
2274 | } | |
2275 | ||
2276 | if (log_level) { | |
2277 | verbose("%d: ", insn_idx); | |
2278 | print_bpf_insn(insn); | |
2279 | } | |
2280 | ||
2281 | if (class == BPF_ALU || class == BPF_ALU64) { | |
1be7f75d | 2282 | err = check_alu_op(env, insn); |
17a52670 AS |
2283 | if (err) |
2284 | return err; | |
2285 | ||
2286 | } else if (class == BPF_LDX) { | |
9bac3d6d AS |
2287 | enum bpf_reg_type src_reg_type; |
2288 | ||
2289 | /* check for reserved fields is already done */ | |
2290 | ||
17a52670 AS |
2291 | /* check src operand */ |
2292 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2293 | if (err) | |
2294 | return err; | |
2295 | ||
2296 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
2297 | if (err) | |
2298 | return err; | |
2299 | ||
725f9dcd AS |
2300 | src_reg_type = regs[insn->src_reg].type; |
2301 | ||
17a52670 AS |
2302 | /* check that memory (src_reg + off) is readable, |
2303 | * the state of dst_reg will be updated by this func | |
2304 | */ | |
2305 | err = check_mem_access(env, insn->src_reg, insn->off, | |
2306 | BPF_SIZE(insn->code), BPF_READ, | |
2307 | insn->dst_reg); | |
2308 | if (err) | |
2309 | return err; | |
2310 | ||
725f9dcd AS |
2311 | if (BPF_SIZE(insn->code) != BPF_W) { |
2312 | insn_idx++; | |
2313 | continue; | |
2314 | } | |
9bac3d6d | 2315 | |
725f9dcd | 2316 | if (insn->imm == 0) { |
9bac3d6d AS |
2317 | /* saw a valid insn |
2318 | * dst_reg = *(u32 *)(src_reg + off) | |
2319 | * use reserved 'imm' field to mark this insn | |
2320 | */ | |
2321 | insn->imm = src_reg_type; | |
2322 | ||
2323 | } else if (src_reg_type != insn->imm && | |
2324 | (src_reg_type == PTR_TO_CTX || | |
2325 | insn->imm == PTR_TO_CTX)) { | |
2326 | /* ABuser program is trying to use the same insn | |
2327 | * dst_reg = *(u32*) (src_reg + off) | |
2328 | * with different pointer types: | |
2329 | * src_reg == ctx in one branch and | |
2330 | * src_reg == stack|map in some other branch. | |
2331 | * Reject it. | |
2332 | */ | |
2333 | verbose("same insn cannot be used with different pointers\n"); | |
2334 | return -EINVAL; | |
2335 | } | |
2336 | ||
17a52670 | 2337 | } else if (class == BPF_STX) { |
d691f9e8 AS |
2338 | enum bpf_reg_type dst_reg_type; |
2339 | ||
17a52670 AS |
2340 | if (BPF_MODE(insn->code) == BPF_XADD) { |
2341 | err = check_xadd(env, insn); | |
2342 | if (err) | |
2343 | return err; | |
2344 | insn_idx++; | |
2345 | continue; | |
2346 | } | |
2347 | ||
17a52670 AS |
2348 | /* check src1 operand */ |
2349 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2350 | if (err) | |
2351 | return err; | |
2352 | /* check src2 operand */ | |
2353 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2354 | if (err) | |
2355 | return err; | |
2356 | ||
d691f9e8 AS |
2357 | dst_reg_type = regs[insn->dst_reg].type; |
2358 | ||
17a52670 AS |
2359 | /* check that memory (dst_reg + off) is writeable */ |
2360 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2361 | BPF_SIZE(insn->code), BPF_WRITE, | |
2362 | insn->src_reg); | |
2363 | if (err) | |
2364 | return err; | |
2365 | ||
d691f9e8 AS |
2366 | if (insn->imm == 0) { |
2367 | insn->imm = dst_reg_type; | |
2368 | } else if (dst_reg_type != insn->imm && | |
2369 | (dst_reg_type == PTR_TO_CTX || | |
2370 | insn->imm == PTR_TO_CTX)) { | |
2371 | verbose("same insn cannot be used with different pointers\n"); | |
2372 | return -EINVAL; | |
2373 | } | |
2374 | ||
17a52670 AS |
2375 | } else if (class == BPF_ST) { |
2376 | if (BPF_MODE(insn->code) != BPF_MEM || | |
2377 | insn->src_reg != BPF_REG_0) { | |
2378 | verbose("BPF_ST uses reserved fields\n"); | |
2379 | return -EINVAL; | |
2380 | } | |
2381 | /* check src operand */ | |
2382 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2383 | if (err) | |
2384 | return err; | |
2385 | ||
2386 | /* check that memory (dst_reg + off) is writeable */ | |
2387 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2388 | BPF_SIZE(insn->code), BPF_WRITE, | |
2389 | -1); | |
2390 | if (err) | |
2391 | return err; | |
2392 | ||
2393 | } else if (class == BPF_JMP) { | |
2394 | u8 opcode = BPF_OP(insn->code); | |
2395 | ||
2396 | if (opcode == BPF_CALL) { | |
2397 | if (BPF_SRC(insn->code) != BPF_K || | |
2398 | insn->off != 0 || | |
2399 | insn->src_reg != BPF_REG_0 || | |
2400 | insn->dst_reg != BPF_REG_0) { | |
2401 | verbose("BPF_CALL uses reserved fields\n"); | |
2402 | return -EINVAL; | |
2403 | } | |
2404 | ||
2405 | err = check_call(env, insn->imm); | |
2406 | if (err) | |
2407 | return err; | |
2408 | ||
2409 | } else if (opcode == BPF_JA) { | |
2410 | if (BPF_SRC(insn->code) != BPF_K || | |
2411 | insn->imm != 0 || | |
2412 | insn->src_reg != BPF_REG_0 || | |
2413 | insn->dst_reg != BPF_REG_0) { | |
2414 | verbose("BPF_JA uses reserved fields\n"); | |
2415 | return -EINVAL; | |
2416 | } | |
2417 | ||
2418 | insn_idx += insn->off + 1; | |
2419 | continue; | |
2420 | ||
2421 | } else if (opcode == BPF_EXIT) { | |
2422 | if (BPF_SRC(insn->code) != BPF_K || | |
2423 | insn->imm != 0 || | |
2424 | insn->src_reg != BPF_REG_0 || | |
2425 | insn->dst_reg != BPF_REG_0) { | |
2426 | verbose("BPF_EXIT uses reserved fields\n"); | |
2427 | return -EINVAL; | |
2428 | } | |
2429 | ||
2430 | /* eBPF calling convetion is such that R0 is used | |
2431 | * to return the value from eBPF program. | |
2432 | * Make sure that it's readable at this time | |
2433 | * of bpf_exit, which means that program wrote | |
2434 | * something into it earlier | |
2435 | */ | |
2436 | err = check_reg_arg(regs, BPF_REG_0, SRC_OP); | |
2437 | if (err) | |
2438 | return err; | |
2439 | ||
1be7f75d AS |
2440 | if (is_pointer_value(env, BPF_REG_0)) { |
2441 | verbose("R0 leaks addr as return value\n"); | |
2442 | return -EACCES; | |
2443 | } | |
2444 | ||
f1bca824 | 2445 | process_bpf_exit: |
17a52670 AS |
2446 | insn_idx = pop_stack(env, &prev_insn_idx); |
2447 | if (insn_idx < 0) { | |
2448 | break; | |
2449 | } else { | |
2450 | do_print_state = true; | |
2451 | continue; | |
2452 | } | |
2453 | } else { | |
2454 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
2455 | if (err) | |
2456 | return err; | |
2457 | } | |
2458 | } else if (class == BPF_LD) { | |
2459 | u8 mode = BPF_MODE(insn->code); | |
2460 | ||
2461 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
2462 | err = check_ld_abs(env, insn); |
2463 | if (err) | |
2464 | return err; | |
2465 | ||
17a52670 AS |
2466 | } else if (mode == BPF_IMM) { |
2467 | err = check_ld_imm(env, insn); | |
2468 | if (err) | |
2469 | return err; | |
2470 | ||
2471 | insn_idx++; | |
2472 | } else { | |
2473 | verbose("invalid BPF_LD mode\n"); | |
2474 | return -EINVAL; | |
2475 | } | |
2476 | } else { | |
2477 | verbose("unknown insn class %d\n", class); | |
2478 | return -EINVAL; | |
2479 | } | |
2480 | ||
2481 | insn_idx++; | |
2482 | } | |
2483 | ||
1a0dc1ac | 2484 | verbose("processed %d insns\n", insn_processed); |
17a52670 AS |
2485 | return 0; |
2486 | } | |
2487 | ||
0246e64d AS |
2488 | /* look for pseudo eBPF instructions that access map FDs and |
2489 | * replace them with actual map pointers | |
2490 | */ | |
2491 | static int replace_map_fd_with_map_ptr(struct verifier_env *env) | |
2492 | { | |
2493 | struct bpf_insn *insn = env->prog->insnsi; | |
2494 | int insn_cnt = env->prog->len; | |
2495 | int i, j; | |
2496 | ||
2497 | for (i = 0; i < insn_cnt; i++, insn++) { | |
9bac3d6d | 2498 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 2499 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
9bac3d6d AS |
2500 | verbose("BPF_LDX uses reserved fields\n"); |
2501 | return -EINVAL; | |
2502 | } | |
2503 | ||
d691f9e8 AS |
2504 | if (BPF_CLASS(insn->code) == BPF_STX && |
2505 | ((BPF_MODE(insn->code) != BPF_MEM && | |
2506 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
2507 | verbose("BPF_STX uses reserved fields\n"); | |
2508 | return -EINVAL; | |
2509 | } | |
2510 | ||
0246e64d AS |
2511 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
2512 | struct bpf_map *map; | |
2513 | struct fd f; | |
2514 | ||
2515 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
2516 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
2517 | insn[1].off != 0) { | |
2518 | verbose("invalid bpf_ld_imm64 insn\n"); | |
2519 | return -EINVAL; | |
2520 | } | |
2521 | ||
2522 | if (insn->src_reg == 0) | |
2523 | /* valid generic load 64-bit imm */ | |
2524 | goto next_insn; | |
2525 | ||
2526 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
2527 | verbose("unrecognized bpf_ld_imm64 insn\n"); | |
2528 | return -EINVAL; | |
2529 | } | |
2530 | ||
2531 | f = fdget(insn->imm); | |
c2101297 | 2532 | map = __bpf_map_get(f); |
0246e64d AS |
2533 | if (IS_ERR(map)) { |
2534 | verbose("fd %d is not pointing to valid bpf_map\n", | |
2535 | insn->imm); | |
0246e64d AS |
2536 | return PTR_ERR(map); |
2537 | } | |
2538 | ||
2539 | /* store map pointer inside BPF_LD_IMM64 instruction */ | |
2540 | insn[0].imm = (u32) (unsigned long) map; | |
2541 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
2542 | ||
2543 | /* check whether we recorded this map already */ | |
2544 | for (j = 0; j < env->used_map_cnt; j++) | |
2545 | if (env->used_maps[j] == map) { | |
2546 | fdput(f); | |
2547 | goto next_insn; | |
2548 | } | |
2549 | ||
2550 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
2551 | fdput(f); | |
2552 | return -E2BIG; | |
2553 | } | |
2554 | ||
0246e64d AS |
2555 | /* hold the map. If the program is rejected by verifier, |
2556 | * the map will be released by release_maps() or it | |
2557 | * will be used by the valid program until it's unloaded | |
2558 | * and all maps are released in free_bpf_prog_info() | |
2559 | */ | |
92117d84 AS |
2560 | map = bpf_map_inc(map, false); |
2561 | if (IS_ERR(map)) { | |
2562 | fdput(f); | |
2563 | return PTR_ERR(map); | |
2564 | } | |
2565 | env->used_maps[env->used_map_cnt++] = map; | |
2566 | ||
0246e64d AS |
2567 | fdput(f); |
2568 | next_insn: | |
2569 | insn++; | |
2570 | i++; | |
2571 | } | |
2572 | } | |
2573 | ||
2574 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
2575 | * 'struct bpf_map *' into a register instead of user map_fd. | |
2576 | * These pointers will be used later by verifier to validate map access. | |
2577 | */ | |
2578 | return 0; | |
2579 | } | |
2580 | ||
2581 | /* drop refcnt of maps used by the rejected program */ | |
2582 | static void release_maps(struct verifier_env *env) | |
2583 | { | |
2584 | int i; | |
2585 | ||
2586 | for (i = 0; i < env->used_map_cnt; i++) | |
2587 | bpf_map_put(env->used_maps[i]); | |
2588 | } | |
2589 | ||
2590 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
2591 | static void convert_pseudo_ld_imm64(struct verifier_env *env) | |
2592 | { | |
2593 | struct bpf_insn *insn = env->prog->insnsi; | |
2594 | int insn_cnt = env->prog->len; | |
2595 | int i; | |
2596 | ||
2597 | for (i = 0; i < insn_cnt; i++, insn++) | |
2598 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
2599 | insn->src_reg = 0; | |
2600 | } | |
2601 | ||
9bac3d6d AS |
2602 | /* convert load instructions that access fields of 'struct __sk_buff' |
2603 | * into sequence of instructions that access fields of 'struct sk_buff' | |
2604 | */ | |
2605 | static int convert_ctx_accesses(struct verifier_env *env) | |
2606 | { | |
2607 | struct bpf_insn *insn = env->prog->insnsi; | |
2608 | int insn_cnt = env->prog->len; | |
2609 | struct bpf_insn insn_buf[16]; | |
2610 | struct bpf_prog *new_prog; | |
d691f9e8 | 2611 | enum bpf_access_type type; |
c237ee5e | 2612 | int i; |
9bac3d6d AS |
2613 | |
2614 | if (!env->prog->aux->ops->convert_ctx_access) | |
2615 | return 0; | |
2616 | ||
2617 | for (i = 0; i < insn_cnt; i++, insn++) { | |
c237ee5e DB |
2618 | u32 insn_delta, cnt; |
2619 | ||
d691f9e8 AS |
2620 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_W)) |
2621 | type = BPF_READ; | |
2622 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_W)) | |
2623 | type = BPF_WRITE; | |
2624 | else | |
9bac3d6d AS |
2625 | continue; |
2626 | ||
2627 | if (insn->imm != PTR_TO_CTX) { | |
2628 | /* clear internal mark */ | |
2629 | insn->imm = 0; | |
2630 | continue; | |
2631 | } | |
2632 | ||
2633 | cnt = env->prog->aux->ops-> | |
d691f9e8 | 2634 | convert_ctx_access(type, insn->dst_reg, insn->src_reg, |
ff936a04 | 2635 | insn->off, insn_buf, env->prog); |
9bac3d6d AS |
2636 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { |
2637 | verbose("bpf verifier is misconfigured\n"); | |
2638 | return -EINVAL; | |
2639 | } | |
2640 | ||
c237ee5e | 2641 | new_prog = bpf_patch_insn_single(env->prog, i, insn_buf, cnt); |
9bac3d6d AS |
2642 | if (!new_prog) |
2643 | return -ENOMEM; | |
2644 | ||
c237ee5e | 2645 | insn_delta = cnt - 1; |
9bac3d6d AS |
2646 | |
2647 | /* keep walking new program and skip insns we just inserted */ | |
2648 | env->prog = new_prog; | |
c237ee5e DB |
2649 | insn = new_prog->insnsi + i + insn_delta; |
2650 | ||
2651 | insn_cnt += insn_delta; | |
2652 | i += insn_delta; | |
9bac3d6d AS |
2653 | } |
2654 | ||
2655 | return 0; | |
2656 | } | |
2657 | ||
f1bca824 AS |
2658 | static void free_states(struct verifier_env *env) |
2659 | { | |
2660 | struct verifier_state_list *sl, *sln; | |
2661 | int i; | |
2662 | ||
2663 | if (!env->explored_states) | |
2664 | return; | |
2665 | ||
2666 | for (i = 0; i < env->prog->len; i++) { | |
2667 | sl = env->explored_states[i]; | |
2668 | ||
2669 | if (sl) | |
2670 | while (sl != STATE_LIST_MARK) { | |
2671 | sln = sl->next; | |
2672 | kfree(sl); | |
2673 | sl = sln; | |
2674 | } | |
2675 | } | |
2676 | ||
2677 | kfree(env->explored_states); | |
2678 | } | |
2679 | ||
9bac3d6d | 2680 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 2681 | { |
cbd35700 AS |
2682 | char __user *log_ubuf = NULL; |
2683 | struct verifier_env *env; | |
51580e79 AS |
2684 | int ret = -EINVAL; |
2685 | ||
9bac3d6d | 2686 | if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS) |
cbd35700 AS |
2687 | return -E2BIG; |
2688 | ||
2689 | /* 'struct verifier_env' can be global, but since it's not small, | |
2690 | * allocate/free it every time bpf_check() is called | |
2691 | */ | |
2692 | env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL); | |
2693 | if (!env) | |
2694 | return -ENOMEM; | |
2695 | ||
9bac3d6d | 2696 | env->prog = *prog; |
0246e64d | 2697 | |
cbd35700 AS |
2698 | /* grab the mutex to protect few globals used by verifier */ |
2699 | mutex_lock(&bpf_verifier_lock); | |
2700 | ||
2701 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
2702 | /* user requested verbose verifier output | |
2703 | * and supplied buffer to store the verification trace | |
2704 | */ | |
2705 | log_level = attr->log_level; | |
2706 | log_ubuf = (char __user *) (unsigned long) attr->log_buf; | |
2707 | log_size = attr->log_size; | |
2708 | log_len = 0; | |
2709 | ||
2710 | ret = -EINVAL; | |
2711 | /* log_* values have to be sane */ | |
2712 | if (log_size < 128 || log_size > UINT_MAX >> 8 || | |
2713 | log_level == 0 || log_ubuf == NULL) | |
2714 | goto free_env; | |
2715 | ||
2716 | ret = -ENOMEM; | |
2717 | log_buf = vmalloc(log_size); | |
2718 | if (!log_buf) | |
2719 | goto free_env; | |
2720 | } else { | |
2721 | log_level = 0; | |
2722 | } | |
2723 | ||
0246e64d AS |
2724 | ret = replace_map_fd_with_map_ptr(env); |
2725 | if (ret < 0) | |
2726 | goto skip_full_check; | |
2727 | ||
9bac3d6d | 2728 | env->explored_states = kcalloc(env->prog->len, |
f1bca824 AS |
2729 | sizeof(struct verifier_state_list *), |
2730 | GFP_USER); | |
2731 | ret = -ENOMEM; | |
2732 | if (!env->explored_states) | |
2733 | goto skip_full_check; | |
2734 | ||
475fb78f AS |
2735 | ret = check_cfg(env); |
2736 | if (ret < 0) | |
2737 | goto skip_full_check; | |
2738 | ||
1be7f75d AS |
2739 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
2740 | ||
17a52670 | 2741 | ret = do_check(env); |
cbd35700 | 2742 | |
0246e64d | 2743 | skip_full_check: |
17a52670 | 2744 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 2745 | free_states(env); |
0246e64d | 2746 | |
9bac3d6d AS |
2747 | if (ret == 0) |
2748 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
2749 | ret = convert_ctx_accesses(env); | |
2750 | ||
cbd35700 AS |
2751 | if (log_level && log_len >= log_size - 1) { |
2752 | BUG_ON(log_len >= log_size); | |
2753 | /* verifier log exceeded user supplied buffer */ | |
2754 | ret = -ENOSPC; | |
2755 | /* fall through to return what was recorded */ | |
2756 | } | |
2757 | ||
2758 | /* copy verifier log back to user space including trailing zero */ | |
2759 | if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { | |
2760 | ret = -EFAULT; | |
2761 | goto free_log_buf; | |
2762 | } | |
2763 | ||
0246e64d AS |
2764 | if (ret == 0 && env->used_map_cnt) { |
2765 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
2766 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
2767 | sizeof(env->used_maps[0]), | |
2768 | GFP_KERNEL); | |
0246e64d | 2769 | |
9bac3d6d | 2770 | if (!env->prog->aux->used_maps) { |
0246e64d AS |
2771 | ret = -ENOMEM; |
2772 | goto free_log_buf; | |
2773 | } | |
2774 | ||
9bac3d6d | 2775 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 2776 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 2777 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
2778 | |
2779 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
2780 | * bpf_ld_imm64 instructions | |
2781 | */ | |
2782 | convert_pseudo_ld_imm64(env); | |
2783 | } | |
cbd35700 AS |
2784 | |
2785 | free_log_buf: | |
2786 | if (log_level) | |
2787 | vfree(log_buf); | |
2788 | free_env: | |
9bac3d6d | 2789 | if (!env->prog->aux->used_maps) |
0246e64d AS |
2790 | /* if we didn't copy map pointers into bpf_prog_info, release |
2791 | * them now. Otherwise free_bpf_prog_info() will release them. | |
2792 | */ | |
2793 | release_maps(env); | |
9bac3d6d | 2794 | *prog = env->prog; |
cbd35700 AS |
2795 | kfree(env); |
2796 | mutex_unlock(&bpf_verifier_lock); | |
51580e79 AS |
2797 | return ret; |
2798 | } |