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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 | struct reg_state { |
130 | enum bpf_reg_type type; | |
131 | union { | |
969bf05e AS |
132 | /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ |
133 | s64 imm; | |
134 | ||
135 | /* valid when type == PTR_TO_PACKET* */ | |
136 | struct { | |
137 | u32 id; | |
138 | u16 off; | |
139 | u16 range; | |
140 | }; | |
17a52670 AS |
141 | |
142 | /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | | |
143 | * PTR_TO_MAP_VALUE_OR_NULL | |
144 | */ | |
145 | struct bpf_map *map_ptr; | |
146 | }; | |
147 | }; | |
148 | ||
149 | enum bpf_stack_slot_type { | |
150 | STACK_INVALID, /* nothing was stored in this stack slot */ | |
9c399760 | 151 | STACK_SPILL, /* register spilled into stack */ |
17a52670 AS |
152 | STACK_MISC /* BPF program wrote some data into this slot */ |
153 | }; | |
154 | ||
9c399760 | 155 | #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ |
17a52670 AS |
156 | |
157 | /* state of the program: | |
158 | * type of all registers and stack info | |
159 | */ | |
160 | struct verifier_state { | |
161 | struct reg_state regs[MAX_BPF_REG]; | |
9c399760 AS |
162 | u8 stack_slot_type[MAX_BPF_STACK]; |
163 | struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; | |
17a52670 AS |
164 | }; |
165 | ||
166 | /* linked list of verifier states used to prune search */ | |
167 | struct verifier_state_list { | |
168 | struct verifier_state state; | |
169 | struct verifier_state_list *next; | |
170 | }; | |
171 | ||
172 | /* verifier_state + insn_idx are pushed to stack when branch is encountered */ | |
173 | struct verifier_stack_elem { | |
174 | /* verifer state is 'st' | |
175 | * before processing instruction 'insn_idx' | |
176 | * and after processing instruction 'prev_insn_idx' | |
177 | */ | |
178 | struct verifier_state st; | |
179 | int insn_idx; | |
180 | int prev_insn_idx; | |
181 | struct verifier_stack_elem *next; | |
182 | }; | |
183 | ||
0246e64d AS |
184 | #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ |
185 | ||
cbd35700 AS |
186 | /* single container for all structs |
187 | * one verifier_env per bpf_check() call | |
188 | */ | |
189 | struct verifier_env { | |
0246e64d | 190 | struct bpf_prog *prog; /* eBPF program being verified */ |
17a52670 AS |
191 | struct verifier_stack_elem *head; /* stack of verifier states to be processed */ |
192 | int stack_size; /* number of states to be processed */ | |
193 | struct verifier_state cur_state; /* current verifier state */ | |
f1bca824 | 194 | struct verifier_state_list **explored_states; /* search pruning optimization */ |
0246e64d AS |
195 | struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ |
196 | u32 used_map_cnt; /* number of used maps */ | |
1f415a74 | 197 | u32 id_gen; /* used to generate unique reg IDs */ |
1be7f75d | 198 | bool allow_ptr_leaks; |
cbd35700 AS |
199 | }; |
200 | ||
07016151 DB |
201 | #define BPF_COMPLEXITY_LIMIT_INSNS 65536 |
202 | #define BPF_COMPLEXITY_LIMIT_STACK 1024 | |
203 | ||
33ff9823 DB |
204 | struct bpf_call_arg_meta { |
205 | struct bpf_map *map_ptr; | |
435faee1 DB |
206 | bool raw_mode; |
207 | int regno; | |
208 | int access_size; | |
33ff9823 DB |
209 | }; |
210 | ||
cbd35700 AS |
211 | /* verbose verifier prints what it's seeing |
212 | * bpf_check() is called under lock, so no race to access these global vars | |
213 | */ | |
214 | static u32 log_level, log_size, log_len; | |
215 | static char *log_buf; | |
216 | ||
217 | static DEFINE_MUTEX(bpf_verifier_lock); | |
218 | ||
219 | /* log_level controls verbosity level of eBPF verifier. | |
220 | * verbose() is used to dump the verification trace to the log, so the user | |
221 | * can figure out what's wrong with the program | |
222 | */ | |
1d056d9c | 223 | static __printf(1, 2) void verbose(const char *fmt, ...) |
cbd35700 AS |
224 | { |
225 | va_list args; | |
226 | ||
227 | if (log_level == 0 || log_len >= log_size - 1) | |
228 | return; | |
229 | ||
230 | va_start(args, fmt); | |
231 | log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); | |
232 | va_end(args); | |
233 | } | |
234 | ||
17a52670 AS |
235 | /* string representation of 'enum bpf_reg_type' */ |
236 | static const char * const reg_type_str[] = { | |
237 | [NOT_INIT] = "?", | |
238 | [UNKNOWN_VALUE] = "inv", | |
239 | [PTR_TO_CTX] = "ctx", | |
240 | [CONST_PTR_TO_MAP] = "map_ptr", | |
241 | [PTR_TO_MAP_VALUE] = "map_value", | |
242 | [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", | |
243 | [FRAME_PTR] = "fp", | |
244 | [PTR_TO_STACK] = "fp", | |
245 | [CONST_IMM] = "imm", | |
969bf05e AS |
246 | [PTR_TO_PACKET] = "pkt", |
247 | [PTR_TO_PACKET_END] = "pkt_end", | |
17a52670 AS |
248 | }; |
249 | ||
1a0dc1ac | 250 | static void print_verifier_state(struct verifier_state *state) |
17a52670 | 251 | { |
1a0dc1ac | 252 | struct reg_state *reg; |
17a52670 AS |
253 | enum bpf_reg_type t; |
254 | int i; | |
255 | ||
256 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
257 | reg = &state->regs[i]; |
258 | t = reg->type; | |
17a52670 AS |
259 | if (t == NOT_INIT) |
260 | continue; | |
261 | verbose(" R%d=%s", i, reg_type_str[t]); | |
262 | if (t == CONST_IMM || t == PTR_TO_STACK) | |
969bf05e AS |
263 | verbose("%lld", reg->imm); |
264 | else if (t == PTR_TO_PACKET) | |
265 | verbose("(id=%d,off=%d,r=%d)", | |
266 | reg->id, reg->off, reg->range); | |
267 | else if (t == UNKNOWN_VALUE && reg->imm) | |
268 | verbose("%lld", reg->imm); | |
17a52670 AS |
269 | else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || |
270 | t == PTR_TO_MAP_VALUE_OR_NULL) | |
271 | verbose("(ks=%d,vs=%d)", | |
1a0dc1ac AS |
272 | reg->map_ptr->key_size, |
273 | reg->map_ptr->value_size); | |
17a52670 | 274 | } |
9c399760 | 275 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { |
1a0dc1ac | 276 | if (state->stack_slot_type[i] == STACK_SPILL) |
17a52670 | 277 | verbose(" fp%d=%s", -MAX_BPF_STACK + i, |
1a0dc1ac | 278 | reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); |
17a52670 AS |
279 | } |
280 | verbose("\n"); | |
281 | } | |
282 | ||
cbd35700 AS |
283 | static const char *const bpf_class_string[] = { |
284 | [BPF_LD] = "ld", | |
285 | [BPF_LDX] = "ldx", | |
286 | [BPF_ST] = "st", | |
287 | [BPF_STX] = "stx", | |
288 | [BPF_ALU] = "alu", | |
289 | [BPF_JMP] = "jmp", | |
290 | [BPF_RET] = "BUG", | |
291 | [BPF_ALU64] = "alu64", | |
292 | }; | |
293 | ||
687f0715 | 294 | static const char *const bpf_alu_string[16] = { |
cbd35700 AS |
295 | [BPF_ADD >> 4] = "+=", |
296 | [BPF_SUB >> 4] = "-=", | |
297 | [BPF_MUL >> 4] = "*=", | |
298 | [BPF_DIV >> 4] = "/=", | |
299 | [BPF_OR >> 4] = "|=", | |
300 | [BPF_AND >> 4] = "&=", | |
301 | [BPF_LSH >> 4] = "<<=", | |
302 | [BPF_RSH >> 4] = ">>=", | |
303 | [BPF_NEG >> 4] = "neg", | |
304 | [BPF_MOD >> 4] = "%=", | |
305 | [BPF_XOR >> 4] = "^=", | |
306 | [BPF_MOV >> 4] = "=", | |
307 | [BPF_ARSH >> 4] = "s>>=", | |
308 | [BPF_END >> 4] = "endian", | |
309 | }; | |
310 | ||
311 | static const char *const bpf_ldst_string[] = { | |
312 | [BPF_W >> 3] = "u32", | |
313 | [BPF_H >> 3] = "u16", | |
314 | [BPF_B >> 3] = "u8", | |
315 | [BPF_DW >> 3] = "u64", | |
316 | }; | |
317 | ||
687f0715 | 318 | static const char *const bpf_jmp_string[16] = { |
cbd35700 AS |
319 | [BPF_JA >> 4] = "jmp", |
320 | [BPF_JEQ >> 4] = "==", | |
321 | [BPF_JGT >> 4] = ">", | |
322 | [BPF_JGE >> 4] = ">=", | |
323 | [BPF_JSET >> 4] = "&", | |
324 | [BPF_JNE >> 4] = "!=", | |
325 | [BPF_JSGT >> 4] = "s>", | |
326 | [BPF_JSGE >> 4] = "s>=", | |
327 | [BPF_CALL >> 4] = "call", | |
328 | [BPF_EXIT >> 4] = "exit", | |
329 | }; | |
330 | ||
331 | static void print_bpf_insn(struct bpf_insn *insn) | |
332 | { | |
333 | u8 class = BPF_CLASS(insn->code); | |
334 | ||
335 | if (class == BPF_ALU || class == BPF_ALU64) { | |
336 | if (BPF_SRC(insn->code) == BPF_X) | |
337 | verbose("(%02x) %sr%d %s %sr%d\n", | |
338 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
339 | insn->dst_reg, | |
340 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
341 | class == BPF_ALU ? "(u32) " : "", | |
342 | insn->src_reg); | |
343 | else | |
344 | verbose("(%02x) %sr%d %s %s%d\n", | |
345 | insn->code, class == BPF_ALU ? "(u32) " : "", | |
346 | insn->dst_reg, | |
347 | bpf_alu_string[BPF_OP(insn->code) >> 4], | |
348 | class == BPF_ALU ? "(u32) " : "", | |
349 | insn->imm); | |
350 | } else if (class == BPF_STX) { | |
351 | if (BPF_MODE(insn->code) == BPF_MEM) | |
352 | verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", | |
353 | insn->code, | |
354 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
355 | insn->dst_reg, | |
356 | insn->off, insn->src_reg); | |
357 | else if (BPF_MODE(insn->code) == BPF_XADD) | |
358 | verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", | |
359 | insn->code, | |
360 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
361 | insn->dst_reg, insn->off, | |
362 | insn->src_reg); | |
363 | else | |
364 | verbose("BUG_%02x\n", insn->code); | |
365 | } else if (class == BPF_ST) { | |
366 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
367 | verbose("BUG_st_%02x\n", insn->code); | |
368 | return; | |
369 | } | |
370 | verbose("(%02x) *(%s *)(r%d %+d) = %d\n", | |
371 | insn->code, | |
372 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
373 | insn->dst_reg, | |
374 | insn->off, insn->imm); | |
375 | } else if (class == BPF_LDX) { | |
376 | if (BPF_MODE(insn->code) != BPF_MEM) { | |
377 | verbose("BUG_ldx_%02x\n", insn->code); | |
378 | return; | |
379 | } | |
380 | verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", | |
381 | insn->code, insn->dst_reg, | |
382 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
383 | insn->src_reg, insn->off); | |
384 | } else if (class == BPF_LD) { | |
385 | if (BPF_MODE(insn->code) == BPF_ABS) { | |
386 | verbose("(%02x) r0 = *(%s *)skb[%d]\n", | |
387 | insn->code, | |
388 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
389 | insn->imm); | |
390 | } else if (BPF_MODE(insn->code) == BPF_IND) { | |
391 | verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", | |
392 | insn->code, | |
393 | bpf_ldst_string[BPF_SIZE(insn->code) >> 3], | |
394 | insn->src_reg, insn->imm); | |
395 | } else if (BPF_MODE(insn->code) == BPF_IMM) { | |
396 | verbose("(%02x) r%d = 0x%x\n", | |
397 | insn->code, insn->dst_reg, insn->imm); | |
398 | } else { | |
399 | verbose("BUG_ld_%02x\n", insn->code); | |
400 | return; | |
401 | } | |
402 | } else if (class == BPF_JMP) { | |
403 | u8 opcode = BPF_OP(insn->code); | |
404 | ||
405 | if (opcode == BPF_CALL) { | |
406 | verbose("(%02x) call %d\n", insn->code, insn->imm); | |
407 | } else if (insn->code == (BPF_JMP | BPF_JA)) { | |
408 | verbose("(%02x) goto pc%+d\n", | |
409 | insn->code, insn->off); | |
410 | } else if (insn->code == (BPF_JMP | BPF_EXIT)) { | |
411 | verbose("(%02x) exit\n", insn->code); | |
412 | } else if (BPF_SRC(insn->code) == BPF_X) { | |
413 | verbose("(%02x) if r%d %s r%d goto pc%+d\n", | |
414 | insn->code, insn->dst_reg, | |
415 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
416 | insn->src_reg, insn->off); | |
417 | } else { | |
418 | verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", | |
419 | insn->code, insn->dst_reg, | |
420 | bpf_jmp_string[BPF_OP(insn->code) >> 4], | |
421 | insn->imm, insn->off); | |
422 | } | |
423 | } else { | |
424 | verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); | |
425 | } | |
426 | } | |
427 | ||
17a52670 AS |
428 | static int pop_stack(struct verifier_env *env, int *prev_insn_idx) |
429 | { | |
430 | struct verifier_stack_elem *elem; | |
431 | int insn_idx; | |
432 | ||
433 | if (env->head == NULL) | |
434 | return -1; | |
435 | ||
436 | memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); | |
437 | insn_idx = env->head->insn_idx; | |
438 | if (prev_insn_idx) | |
439 | *prev_insn_idx = env->head->prev_insn_idx; | |
440 | elem = env->head->next; | |
441 | kfree(env->head); | |
442 | env->head = elem; | |
443 | env->stack_size--; | |
444 | return insn_idx; | |
445 | } | |
446 | ||
447 | static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx, | |
448 | int prev_insn_idx) | |
449 | { | |
450 | struct verifier_stack_elem *elem; | |
451 | ||
452 | elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL); | |
453 | if (!elem) | |
454 | goto err; | |
455 | ||
456 | memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); | |
457 | elem->insn_idx = insn_idx; | |
458 | elem->prev_insn_idx = prev_insn_idx; | |
459 | elem->next = env->head; | |
460 | env->head = elem; | |
461 | env->stack_size++; | |
07016151 | 462 | if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { |
17a52670 AS |
463 | verbose("BPF program is too complex\n"); |
464 | goto err; | |
465 | } | |
466 | return &elem->st; | |
467 | err: | |
468 | /* pop all elements and return */ | |
469 | while (pop_stack(env, NULL) >= 0); | |
470 | return NULL; | |
471 | } | |
472 | ||
473 | #define CALLER_SAVED_REGS 6 | |
474 | static const int caller_saved[CALLER_SAVED_REGS] = { | |
475 | BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 | |
476 | }; | |
477 | ||
478 | static void init_reg_state(struct reg_state *regs) | |
479 | { | |
480 | int i; | |
481 | ||
482 | for (i = 0; i < MAX_BPF_REG; i++) { | |
483 | regs[i].type = NOT_INIT; | |
484 | regs[i].imm = 0; | |
17a52670 AS |
485 | } |
486 | ||
487 | /* frame pointer */ | |
488 | regs[BPF_REG_FP].type = FRAME_PTR; | |
489 | ||
490 | /* 1st arg to a function */ | |
491 | regs[BPF_REG_1].type = PTR_TO_CTX; | |
492 | } | |
493 | ||
494 | static void mark_reg_unknown_value(struct reg_state *regs, u32 regno) | |
495 | { | |
496 | BUG_ON(regno >= MAX_BPF_REG); | |
497 | regs[regno].type = UNKNOWN_VALUE; | |
498 | regs[regno].imm = 0; | |
17a52670 AS |
499 | } |
500 | ||
501 | enum reg_arg_type { | |
502 | SRC_OP, /* register is used as source operand */ | |
503 | DST_OP, /* register is used as destination operand */ | |
504 | DST_OP_NO_MARK /* same as above, check only, don't mark */ | |
505 | }; | |
506 | ||
507 | static int check_reg_arg(struct reg_state *regs, u32 regno, | |
508 | enum reg_arg_type t) | |
509 | { | |
510 | if (regno >= MAX_BPF_REG) { | |
511 | verbose("R%d is invalid\n", regno); | |
512 | return -EINVAL; | |
513 | } | |
514 | ||
515 | if (t == SRC_OP) { | |
516 | /* check whether register used as source operand can be read */ | |
517 | if (regs[regno].type == NOT_INIT) { | |
518 | verbose("R%d !read_ok\n", regno); | |
519 | return -EACCES; | |
520 | } | |
521 | } else { | |
522 | /* check whether register used as dest operand can be written to */ | |
523 | if (regno == BPF_REG_FP) { | |
524 | verbose("frame pointer is read only\n"); | |
525 | return -EACCES; | |
526 | } | |
527 | if (t == DST_OP) | |
528 | mark_reg_unknown_value(regs, regno); | |
529 | } | |
530 | return 0; | |
531 | } | |
532 | ||
533 | static int bpf_size_to_bytes(int bpf_size) | |
534 | { | |
535 | if (bpf_size == BPF_W) | |
536 | return 4; | |
537 | else if (bpf_size == BPF_H) | |
538 | return 2; | |
539 | else if (bpf_size == BPF_B) | |
540 | return 1; | |
541 | else if (bpf_size == BPF_DW) | |
542 | return 8; | |
543 | else | |
544 | return -EINVAL; | |
545 | } | |
546 | ||
1be7f75d AS |
547 | static bool is_spillable_regtype(enum bpf_reg_type type) |
548 | { | |
549 | switch (type) { | |
550 | case PTR_TO_MAP_VALUE: | |
551 | case PTR_TO_MAP_VALUE_OR_NULL: | |
552 | case PTR_TO_STACK: | |
553 | case PTR_TO_CTX: | |
969bf05e AS |
554 | case PTR_TO_PACKET: |
555 | case PTR_TO_PACKET_END: | |
1be7f75d AS |
556 | case FRAME_PTR: |
557 | case CONST_PTR_TO_MAP: | |
558 | return true; | |
559 | default: | |
560 | return false; | |
561 | } | |
562 | } | |
563 | ||
17a52670 AS |
564 | /* check_stack_read/write functions track spill/fill of registers, |
565 | * stack boundary and alignment are checked in check_mem_access() | |
566 | */ | |
567 | static int check_stack_write(struct verifier_state *state, int off, int size, | |
568 | int value_regno) | |
569 | { | |
17a52670 | 570 | int i; |
9c399760 AS |
571 | /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, |
572 | * so it's aligned access and [off, off + size) are within stack limits | |
573 | */ | |
17a52670 AS |
574 | |
575 | if (value_regno >= 0 && | |
1be7f75d | 576 | is_spillable_regtype(state->regs[value_regno].type)) { |
17a52670 AS |
577 | |
578 | /* register containing pointer is being spilled into stack */ | |
9c399760 | 579 | if (size != BPF_REG_SIZE) { |
17a52670 AS |
580 | verbose("invalid size of register spill\n"); |
581 | return -EACCES; | |
582 | } | |
583 | ||
17a52670 | 584 | /* save register state */ |
9c399760 AS |
585 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
586 | state->regs[value_regno]; | |
17a52670 | 587 | |
9c399760 AS |
588 | for (i = 0; i < BPF_REG_SIZE; i++) |
589 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; | |
590 | } else { | |
17a52670 | 591 | /* regular write of data into stack */ |
9c399760 AS |
592 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = |
593 | (struct reg_state) {}; | |
594 | ||
595 | for (i = 0; i < size; i++) | |
596 | state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; | |
17a52670 AS |
597 | } |
598 | return 0; | |
599 | } | |
600 | ||
601 | static int check_stack_read(struct verifier_state *state, int off, int size, | |
602 | int value_regno) | |
603 | { | |
9c399760 | 604 | u8 *slot_type; |
17a52670 | 605 | int i; |
17a52670 | 606 | |
9c399760 | 607 | slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; |
17a52670 | 608 | |
9c399760 AS |
609 | if (slot_type[0] == STACK_SPILL) { |
610 | if (size != BPF_REG_SIZE) { | |
17a52670 AS |
611 | verbose("invalid size of register spill\n"); |
612 | return -EACCES; | |
613 | } | |
9c399760 AS |
614 | for (i = 1; i < BPF_REG_SIZE; i++) { |
615 | if (slot_type[i] != STACK_SPILL) { | |
17a52670 AS |
616 | verbose("corrupted spill memory\n"); |
617 | return -EACCES; | |
618 | } | |
619 | } | |
620 | ||
621 | if (value_regno >= 0) | |
622 | /* restore register state from stack */ | |
9c399760 AS |
623 | state->regs[value_regno] = |
624 | state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; | |
17a52670 AS |
625 | return 0; |
626 | } else { | |
627 | for (i = 0; i < size; i++) { | |
9c399760 | 628 | if (slot_type[i] != STACK_MISC) { |
17a52670 AS |
629 | verbose("invalid read from stack off %d+%d size %d\n", |
630 | off, i, size); | |
631 | return -EACCES; | |
632 | } | |
633 | } | |
634 | if (value_regno >= 0) | |
635 | /* have read misc data from the stack */ | |
636 | mark_reg_unknown_value(state->regs, value_regno); | |
637 | return 0; | |
638 | } | |
639 | } | |
640 | ||
641 | /* check read/write into map element returned by bpf_map_lookup_elem() */ | |
642 | static int check_map_access(struct verifier_env *env, u32 regno, int off, | |
643 | int size) | |
644 | { | |
645 | struct bpf_map *map = env->cur_state.regs[regno].map_ptr; | |
646 | ||
647 | if (off < 0 || off + size > map->value_size) { | |
648 | verbose("invalid access to map value, value_size=%d off=%d size=%d\n", | |
649 | map->value_size, off, size); | |
650 | return -EACCES; | |
651 | } | |
652 | return 0; | |
653 | } | |
654 | ||
969bf05e AS |
655 | #define MAX_PACKET_OFF 0xffff |
656 | ||
4acf6c0b BB |
657 | static bool may_write_pkt_data(enum bpf_prog_type type) |
658 | { | |
659 | switch (type) { | |
660 | case BPF_PROG_TYPE_XDP: | |
661 | return true; | |
662 | default: | |
663 | return false; | |
664 | } | |
665 | } | |
666 | ||
969bf05e AS |
667 | static int check_packet_access(struct verifier_env *env, u32 regno, int off, |
668 | int size) | |
669 | { | |
670 | struct reg_state *regs = env->cur_state.regs; | |
671 | struct reg_state *reg = ®s[regno]; | |
969bf05e | 672 | |
d91b28ed AS |
673 | off += reg->off; |
674 | if (off < 0 || off + size > reg->range) { | |
675 | verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", | |
676 | off, size, regno, reg->id, reg->off, reg->range); | |
969bf05e AS |
677 | return -EACCES; |
678 | } | |
679 | return 0; | |
680 | } | |
681 | ||
17a52670 AS |
682 | /* check access to 'struct bpf_context' fields */ |
683 | static int check_ctx_access(struct verifier_env *env, int off, int size, | |
19de99f7 | 684 | enum bpf_access_type t, enum bpf_reg_type *reg_type) |
17a52670 AS |
685 | { |
686 | if (env->prog->aux->ops->is_valid_access && | |
19de99f7 | 687 | env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { |
32bbe007 AS |
688 | /* remember the offset of last byte accessed in ctx */ |
689 | if (env->prog->aux->max_ctx_offset < off + size) | |
690 | env->prog->aux->max_ctx_offset = off + size; | |
17a52670 | 691 | return 0; |
32bbe007 | 692 | } |
17a52670 AS |
693 | |
694 | verbose("invalid bpf_context access off=%d size=%d\n", off, size); | |
695 | return -EACCES; | |
696 | } | |
697 | ||
1be7f75d AS |
698 | static bool is_pointer_value(struct verifier_env *env, int regno) |
699 | { | |
700 | if (env->allow_ptr_leaks) | |
701 | return false; | |
702 | ||
703 | switch (env->cur_state.regs[regno].type) { | |
704 | case UNKNOWN_VALUE: | |
705 | case CONST_IMM: | |
706 | return false; | |
707 | default: | |
708 | return true; | |
709 | } | |
710 | } | |
711 | ||
969bf05e AS |
712 | static int check_ptr_alignment(struct verifier_env *env, struct reg_state *reg, |
713 | int off, int size) | |
714 | { | |
715 | if (reg->type != PTR_TO_PACKET) { | |
716 | if (off % size != 0) { | |
717 | verbose("misaligned access off %d size %d\n", off, size); | |
718 | return -EACCES; | |
719 | } else { | |
720 | return 0; | |
721 | } | |
722 | } | |
723 | ||
724 | switch (env->prog->type) { | |
725 | case BPF_PROG_TYPE_SCHED_CLS: | |
726 | case BPF_PROG_TYPE_SCHED_ACT: | |
6a773a15 | 727 | case BPF_PROG_TYPE_XDP: |
969bf05e AS |
728 | break; |
729 | default: | |
730 | verbose("verifier is misconfigured\n"); | |
731 | return -EACCES; | |
732 | } | |
733 | ||
734 | if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) | |
735 | /* misaligned access to packet is ok on x86,arm,arm64 */ | |
736 | return 0; | |
737 | ||
738 | if (reg->id && size != 1) { | |
739 | verbose("Unknown packet alignment. Only byte-sized access allowed\n"); | |
740 | return -EACCES; | |
741 | } | |
742 | ||
743 | /* skb->data is NET_IP_ALIGN-ed */ | |
744 | if ((NET_IP_ALIGN + reg->off + off) % size != 0) { | |
745 | verbose("misaligned packet access off %d+%d+%d size %d\n", | |
746 | NET_IP_ALIGN, reg->off, off, size); | |
747 | return -EACCES; | |
748 | } | |
749 | return 0; | |
750 | } | |
751 | ||
17a52670 AS |
752 | /* check whether memory at (regno + off) is accessible for t = (read | write) |
753 | * if t==write, value_regno is a register which value is stored into memory | |
754 | * if t==read, value_regno is a register which will receive the value from memory | |
755 | * if t==write && value_regno==-1, some unknown value is stored into memory | |
756 | * if t==read && value_regno==-1, don't care what we read from memory | |
757 | */ | |
758 | static int check_mem_access(struct verifier_env *env, u32 regno, int off, | |
759 | int bpf_size, enum bpf_access_type t, | |
760 | int value_regno) | |
761 | { | |
762 | struct verifier_state *state = &env->cur_state; | |
1a0dc1ac | 763 | struct reg_state *reg = &state->regs[regno]; |
17a52670 AS |
764 | int size, err = 0; |
765 | ||
1a0dc1ac AS |
766 | if (reg->type == PTR_TO_STACK) |
767 | off += reg->imm; | |
24b4d2ab | 768 | |
17a52670 AS |
769 | size = bpf_size_to_bytes(bpf_size); |
770 | if (size < 0) | |
771 | return size; | |
772 | ||
969bf05e AS |
773 | err = check_ptr_alignment(env, reg, off, size); |
774 | if (err) | |
775 | return err; | |
17a52670 | 776 | |
1a0dc1ac | 777 | if (reg->type == PTR_TO_MAP_VALUE) { |
1be7f75d AS |
778 | if (t == BPF_WRITE && value_regno >= 0 && |
779 | is_pointer_value(env, value_regno)) { | |
780 | verbose("R%d leaks addr into map\n", value_regno); | |
781 | return -EACCES; | |
782 | } | |
17a52670 AS |
783 | err = check_map_access(env, regno, off, size); |
784 | if (!err && t == BPF_READ && value_regno >= 0) | |
785 | mark_reg_unknown_value(state->regs, value_regno); | |
786 | ||
1a0dc1ac | 787 | } else if (reg->type == PTR_TO_CTX) { |
19de99f7 AS |
788 | enum bpf_reg_type reg_type = UNKNOWN_VALUE; |
789 | ||
1be7f75d AS |
790 | if (t == BPF_WRITE && value_regno >= 0 && |
791 | is_pointer_value(env, value_regno)) { | |
792 | verbose("R%d leaks addr into ctx\n", value_regno); | |
793 | return -EACCES; | |
794 | } | |
19de99f7 | 795 | err = check_ctx_access(env, off, size, t, ®_type); |
969bf05e | 796 | if (!err && t == BPF_READ && value_regno >= 0) { |
17a52670 | 797 | mark_reg_unknown_value(state->regs, value_regno); |
19de99f7 | 798 | if (env->allow_ptr_leaks) |
969bf05e | 799 | /* note that reg.[id|off|range] == 0 */ |
19de99f7 | 800 | state->regs[value_regno].type = reg_type; |
969bf05e | 801 | } |
17a52670 | 802 | |
1a0dc1ac | 803 | } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { |
17a52670 AS |
804 | if (off >= 0 || off < -MAX_BPF_STACK) { |
805 | verbose("invalid stack off=%d size=%d\n", off, size); | |
806 | return -EACCES; | |
807 | } | |
1be7f75d AS |
808 | if (t == BPF_WRITE) { |
809 | if (!env->allow_ptr_leaks && | |
810 | state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && | |
811 | size != BPF_REG_SIZE) { | |
812 | verbose("attempt to corrupt spilled pointer on stack\n"); | |
813 | return -EACCES; | |
814 | } | |
17a52670 | 815 | err = check_stack_write(state, off, size, value_regno); |
1be7f75d | 816 | } else { |
17a52670 | 817 | err = check_stack_read(state, off, size, value_regno); |
1be7f75d | 818 | } |
969bf05e | 819 | } else if (state->regs[regno].type == PTR_TO_PACKET) { |
4acf6c0b | 820 | if (t == BPF_WRITE && !may_write_pkt_data(env->prog->type)) { |
969bf05e AS |
821 | verbose("cannot write into packet\n"); |
822 | return -EACCES; | |
823 | } | |
4acf6c0b BB |
824 | if (t == BPF_WRITE && value_regno >= 0 && |
825 | is_pointer_value(env, value_regno)) { | |
826 | verbose("R%d leaks addr into packet\n", value_regno); | |
827 | return -EACCES; | |
828 | } | |
969bf05e AS |
829 | err = check_packet_access(env, regno, off, size); |
830 | if (!err && t == BPF_READ && value_regno >= 0) | |
831 | mark_reg_unknown_value(state->regs, value_regno); | |
17a52670 AS |
832 | } else { |
833 | verbose("R%d invalid mem access '%s'\n", | |
1a0dc1ac | 834 | regno, reg_type_str[reg->type]); |
17a52670 AS |
835 | return -EACCES; |
836 | } | |
969bf05e AS |
837 | |
838 | if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && | |
839 | state->regs[value_regno].type == UNKNOWN_VALUE) { | |
840 | /* 1 or 2 byte load zero-extends, determine the number of | |
841 | * zero upper bits. Not doing it fo 4 byte load, since | |
842 | * such values cannot be added to ptr_to_packet anyway. | |
843 | */ | |
844 | state->regs[value_regno].imm = 64 - size * 8; | |
845 | } | |
17a52670 AS |
846 | return err; |
847 | } | |
848 | ||
849 | static int check_xadd(struct verifier_env *env, struct bpf_insn *insn) | |
850 | { | |
851 | struct reg_state *regs = env->cur_state.regs; | |
852 | int err; | |
853 | ||
854 | if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || | |
855 | insn->imm != 0) { | |
856 | verbose("BPF_XADD uses reserved fields\n"); | |
857 | return -EINVAL; | |
858 | } | |
859 | ||
860 | /* check src1 operand */ | |
861 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
862 | if (err) | |
863 | return err; | |
864 | ||
865 | /* check src2 operand */ | |
866 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
867 | if (err) | |
868 | return err; | |
869 | ||
870 | /* check whether atomic_add can read the memory */ | |
871 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
872 | BPF_SIZE(insn->code), BPF_READ, -1); | |
873 | if (err) | |
874 | return err; | |
875 | ||
876 | /* check whether atomic_add can write into the same memory */ | |
877 | return check_mem_access(env, insn->dst_reg, insn->off, | |
878 | BPF_SIZE(insn->code), BPF_WRITE, -1); | |
879 | } | |
880 | ||
881 | /* when register 'regno' is passed into function that will read 'access_size' | |
882 | * bytes from that pointer, make sure that it's within stack boundary | |
883 | * and all elements of stack are initialized | |
884 | */ | |
8e2fe1d9 | 885 | static int check_stack_boundary(struct verifier_env *env, int regno, |
435faee1 DB |
886 | int access_size, bool zero_size_allowed, |
887 | struct bpf_call_arg_meta *meta) | |
17a52670 AS |
888 | { |
889 | struct verifier_state *state = &env->cur_state; | |
890 | struct reg_state *regs = state->regs; | |
891 | int off, i; | |
892 | ||
8e2fe1d9 DB |
893 | if (regs[regno].type != PTR_TO_STACK) { |
894 | if (zero_size_allowed && access_size == 0 && | |
895 | regs[regno].type == CONST_IMM && | |
896 | regs[regno].imm == 0) | |
897 | return 0; | |
898 | ||
899 | verbose("R%d type=%s expected=%s\n", regno, | |
900 | reg_type_str[regs[regno].type], | |
901 | reg_type_str[PTR_TO_STACK]); | |
17a52670 | 902 | return -EACCES; |
8e2fe1d9 | 903 | } |
17a52670 AS |
904 | |
905 | off = regs[regno].imm; | |
906 | if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || | |
907 | access_size <= 0) { | |
908 | verbose("invalid stack type R%d off=%d access_size=%d\n", | |
909 | regno, off, access_size); | |
910 | return -EACCES; | |
911 | } | |
912 | ||
435faee1 DB |
913 | if (meta && meta->raw_mode) { |
914 | meta->access_size = access_size; | |
915 | meta->regno = regno; | |
916 | return 0; | |
917 | } | |
918 | ||
17a52670 | 919 | for (i = 0; i < access_size; i++) { |
9c399760 | 920 | if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { |
17a52670 AS |
921 | verbose("invalid indirect read from stack off %d+%d size %d\n", |
922 | off, i, access_size); | |
923 | return -EACCES; | |
924 | } | |
925 | } | |
926 | return 0; | |
927 | } | |
928 | ||
929 | static int check_func_arg(struct verifier_env *env, u32 regno, | |
33ff9823 DB |
930 | enum bpf_arg_type arg_type, |
931 | struct bpf_call_arg_meta *meta) | |
17a52670 | 932 | { |
6841de8b AS |
933 | struct reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; |
934 | enum bpf_reg_type expected_type, type = reg->type; | |
17a52670 AS |
935 | int err = 0; |
936 | ||
80f1d68c | 937 | if (arg_type == ARG_DONTCARE) |
17a52670 AS |
938 | return 0; |
939 | ||
6841de8b | 940 | if (type == NOT_INIT) { |
17a52670 AS |
941 | verbose("R%d !read_ok\n", regno); |
942 | return -EACCES; | |
943 | } | |
944 | ||
1be7f75d AS |
945 | if (arg_type == ARG_ANYTHING) { |
946 | if (is_pointer_value(env, regno)) { | |
947 | verbose("R%d leaks addr into helper function\n", regno); | |
948 | return -EACCES; | |
949 | } | |
80f1d68c | 950 | return 0; |
1be7f75d | 951 | } |
80f1d68c | 952 | |
6841de8b AS |
953 | if (type == PTR_TO_PACKET && !may_write_pkt_data(env->prog->type)) { |
954 | verbose("helper access to the packet is not allowed for clsact\n"); | |
955 | return -EACCES; | |
956 | } | |
957 | ||
8e2fe1d9 | 958 | if (arg_type == ARG_PTR_TO_MAP_KEY || |
17a52670 AS |
959 | arg_type == ARG_PTR_TO_MAP_VALUE) { |
960 | expected_type = PTR_TO_STACK; | |
6841de8b AS |
961 | if (type != PTR_TO_PACKET && type != expected_type) |
962 | goto err_type; | |
8e2fe1d9 DB |
963 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
964 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
17a52670 | 965 | expected_type = CONST_IMM; |
6841de8b AS |
966 | if (type != expected_type) |
967 | goto err_type; | |
17a52670 AS |
968 | } else if (arg_type == ARG_CONST_MAP_PTR) { |
969 | expected_type = CONST_PTR_TO_MAP; | |
6841de8b AS |
970 | if (type != expected_type) |
971 | goto err_type; | |
608cd71a AS |
972 | } else if (arg_type == ARG_PTR_TO_CTX) { |
973 | expected_type = PTR_TO_CTX; | |
6841de8b AS |
974 | if (type != expected_type) |
975 | goto err_type; | |
435faee1 DB |
976 | } else if (arg_type == ARG_PTR_TO_STACK || |
977 | arg_type == ARG_PTR_TO_RAW_STACK) { | |
8e2fe1d9 DB |
978 | expected_type = PTR_TO_STACK; |
979 | /* One exception here. In case function allows for NULL to be | |
980 | * passed in as argument, it's a CONST_IMM type. Final test | |
981 | * happens during stack boundary checking. | |
982 | */ | |
6841de8b AS |
983 | if (type == CONST_IMM && reg->imm == 0) |
984 | /* final test in check_stack_boundary() */; | |
985 | else if (type != PTR_TO_PACKET && type != expected_type) | |
986 | goto err_type; | |
435faee1 | 987 | meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK; |
17a52670 AS |
988 | } else { |
989 | verbose("unsupported arg_type %d\n", arg_type); | |
990 | return -EFAULT; | |
991 | } | |
992 | ||
17a52670 AS |
993 | if (arg_type == ARG_CONST_MAP_PTR) { |
994 | /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ | |
33ff9823 | 995 | meta->map_ptr = reg->map_ptr; |
17a52670 AS |
996 | } else if (arg_type == ARG_PTR_TO_MAP_KEY) { |
997 | /* bpf_map_xxx(..., map_ptr, ..., key) call: | |
998 | * check that [key, key + map->key_size) are within | |
999 | * stack limits and initialized | |
1000 | */ | |
33ff9823 | 1001 | if (!meta->map_ptr) { |
17a52670 AS |
1002 | /* in function declaration map_ptr must come before |
1003 | * map_key, so that it's verified and known before | |
1004 | * we have to check map_key here. Otherwise it means | |
1005 | * that kernel subsystem misconfigured verifier | |
1006 | */ | |
1007 | verbose("invalid map_ptr to access map->key\n"); | |
1008 | return -EACCES; | |
1009 | } | |
6841de8b AS |
1010 | if (type == PTR_TO_PACKET) |
1011 | err = check_packet_access(env, regno, 0, | |
1012 | meta->map_ptr->key_size); | |
1013 | else | |
1014 | err = check_stack_boundary(env, regno, | |
1015 | meta->map_ptr->key_size, | |
1016 | false, NULL); | |
17a52670 AS |
1017 | } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { |
1018 | /* bpf_map_xxx(..., map_ptr, ..., value) call: | |
1019 | * check [value, value + map->value_size) validity | |
1020 | */ | |
33ff9823 | 1021 | if (!meta->map_ptr) { |
17a52670 AS |
1022 | /* kernel subsystem misconfigured verifier */ |
1023 | verbose("invalid map_ptr to access map->value\n"); | |
1024 | return -EACCES; | |
1025 | } | |
6841de8b AS |
1026 | if (type == PTR_TO_PACKET) |
1027 | err = check_packet_access(env, regno, 0, | |
1028 | meta->map_ptr->value_size); | |
1029 | else | |
1030 | err = check_stack_boundary(env, regno, | |
1031 | meta->map_ptr->value_size, | |
1032 | false, NULL); | |
8e2fe1d9 DB |
1033 | } else if (arg_type == ARG_CONST_STACK_SIZE || |
1034 | arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { | |
1035 | bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO); | |
17a52670 | 1036 | |
17a52670 AS |
1037 | /* bpf_xxx(..., buf, len) call will access 'len' bytes |
1038 | * from stack pointer 'buf'. Check it | |
1039 | * note: regno == len, regno - 1 == buf | |
1040 | */ | |
1041 | if (regno == 0) { | |
1042 | /* kernel subsystem misconfigured verifier */ | |
1043 | verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); | |
1044 | return -EACCES; | |
1045 | } | |
6841de8b AS |
1046 | if (regs[regno - 1].type == PTR_TO_PACKET) |
1047 | err = check_packet_access(env, regno - 1, 0, reg->imm); | |
1048 | else | |
1049 | err = check_stack_boundary(env, regno - 1, reg->imm, | |
1050 | zero_size_allowed, meta); | |
17a52670 AS |
1051 | } |
1052 | ||
1053 | return err; | |
6841de8b AS |
1054 | err_type: |
1055 | verbose("R%d type=%s expected=%s\n", regno, | |
1056 | reg_type_str[type], reg_type_str[expected_type]); | |
1057 | return -EACCES; | |
17a52670 AS |
1058 | } |
1059 | ||
35578d79 KX |
1060 | static int check_map_func_compatibility(struct bpf_map *map, int func_id) |
1061 | { | |
35578d79 KX |
1062 | if (!map) |
1063 | return 0; | |
1064 | ||
6aff67c8 AS |
1065 | /* We need a two way check, first is from map perspective ... */ |
1066 | switch (map->map_type) { | |
1067 | case BPF_MAP_TYPE_PROG_ARRAY: | |
1068 | if (func_id != BPF_FUNC_tail_call) | |
1069 | goto error; | |
1070 | break; | |
1071 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: | |
1072 | if (func_id != BPF_FUNC_perf_event_read && | |
1073 | func_id != BPF_FUNC_perf_event_output) | |
1074 | goto error; | |
1075 | break; | |
1076 | case BPF_MAP_TYPE_STACK_TRACE: | |
1077 | if (func_id != BPF_FUNC_get_stackid) | |
1078 | goto error; | |
1079 | break; | |
4ed8ec52 | 1080 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
60747ef4 | 1081 | if (func_id != BPF_FUNC_skb_under_cgroup && |
60d20f91 | 1082 | func_id != BPF_FUNC_current_task_under_cgroup) |
4a482f34 MKL |
1083 | goto error; |
1084 | break; | |
6aff67c8 AS |
1085 | default: |
1086 | break; | |
1087 | } | |
1088 | ||
1089 | /* ... and second from the function itself. */ | |
1090 | switch (func_id) { | |
1091 | case BPF_FUNC_tail_call: | |
1092 | if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) | |
1093 | goto error; | |
1094 | break; | |
1095 | case BPF_FUNC_perf_event_read: | |
1096 | case BPF_FUNC_perf_event_output: | |
1097 | if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) | |
1098 | goto error; | |
1099 | break; | |
1100 | case BPF_FUNC_get_stackid: | |
1101 | if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) | |
1102 | goto error; | |
1103 | break; | |
60d20f91 | 1104 | case BPF_FUNC_current_task_under_cgroup: |
747ea55e | 1105 | case BPF_FUNC_skb_under_cgroup: |
4a482f34 MKL |
1106 | if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) |
1107 | goto error; | |
1108 | break; | |
6aff67c8 AS |
1109 | default: |
1110 | break; | |
35578d79 KX |
1111 | } |
1112 | ||
1113 | return 0; | |
6aff67c8 AS |
1114 | error: |
1115 | verbose("cannot pass map_type %d into func %d\n", | |
1116 | map->map_type, func_id); | |
1117 | return -EINVAL; | |
35578d79 KX |
1118 | } |
1119 | ||
435faee1 DB |
1120 | static int check_raw_mode(const struct bpf_func_proto *fn) |
1121 | { | |
1122 | int count = 0; | |
1123 | ||
1124 | if (fn->arg1_type == ARG_PTR_TO_RAW_STACK) | |
1125 | count++; | |
1126 | if (fn->arg2_type == ARG_PTR_TO_RAW_STACK) | |
1127 | count++; | |
1128 | if (fn->arg3_type == ARG_PTR_TO_RAW_STACK) | |
1129 | count++; | |
1130 | if (fn->arg4_type == ARG_PTR_TO_RAW_STACK) | |
1131 | count++; | |
1132 | if (fn->arg5_type == ARG_PTR_TO_RAW_STACK) | |
1133 | count++; | |
1134 | ||
1135 | return count > 1 ? -EINVAL : 0; | |
1136 | } | |
1137 | ||
969bf05e AS |
1138 | static void clear_all_pkt_pointers(struct verifier_env *env) |
1139 | { | |
1140 | struct verifier_state *state = &env->cur_state; | |
1141 | struct reg_state *regs = state->regs, *reg; | |
1142 | int i; | |
1143 | ||
1144 | for (i = 0; i < MAX_BPF_REG; i++) | |
1145 | if (regs[i].type == PTR_TO_PACKET || | |
1146 | regs[i].type == PTR_TO_PACKET_END) | |
1147 | mark_reg_unknown_value(regs, i); | |
1148 | ||
1149 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1150 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1151 | continue; | |
1152 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1153 | if (reg->type != PTR_TO_PACKET && | |
1154 | reg->type != PTR_TO_PACKET_END) | |
1155 | continue; | |
1156 | reg->type = UNKNOWN_VALUE; | |
1157 | reg->imm = 0; | |
1158 | } | |
1159 | } | |
1160 | ||
17a52670 AS |
1161 | static int check_call(struct verifier_env *env, int func_id) |
1162 | { | |
1163 | struct verifier_state *state = &env->cur_state; | |
1164 | const struct bpf_func_proto *fn = NULL; | |
1165 | struct reg_state *regs = state->regs; | |
17a52670 | 1166 | struct reg_state *reg; |
33ff9823 | 1167 | struct bpf_call_arg_meta meta; |
969bf05e | 1168 | bool changes_data; |
17a52670 AS |
1169 | int i, err; |
1170 | ||
1171 | /* find function prototype */ | |
1172 | if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { | |
1173 | verbose("invalid func %d\n", func_id); | |
1174 | return -EINVAL; | |
1175 | } | |
1176 | ||
1177 | if (env->prog->aux->ops->get_func_proto) | |
1178 | fn = env->prog->aux->ops->get_func_proto(func_id); | |
1179 | ||
1180 | if (!fn) { | |
1181 | verbose("unknown func %d\n", func_id); | |
1182 | return -EINVAL; | |
1183 | } | |
1184 | ||
1185 | /* eBPF programs must be GPL compatible to use GPL-ed functions */ | |
24701ece | 1186 | if (!env->prog->gpl_compatible && fn->gpl_only) { |
17a52670 AS |
1187 | verbose("cannot call GPL only function from proprietary program\n"); |
1188 | return -EINVAL; | |
1189 | } | |
1190 | ||
969bf05e AS |
1191 | changes_data = bpf_helper_changes_skb_data(fn->func); |
1192 | ||
33ff9823 DB |
1193 | memset(&meta, 0, sizeof(meta)); |
1194 | ||
435faee1 DB |
1195 | /* We only support one arg being in raw mode at the moment, which |
1196 | * is sufficient for the helper functions we have right now. | |
1197 | */ | |
1198 | err = check_raw_mode(fn); | |
1199 | if (err) { | |
1200 | verbose("kernel subsystem misconfigured func %d\n", func_id); | |
1201 | return err; | |
1202 | } | |
1203 | ||
17a52670 | 1204 | /* check args */ |
33ff9823 | 1205 | err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); |
17a52670 AS |
1206 | if (err) |
1207 | return err; | |
33ff9823 | 1208 | err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); |
17a52670 AS |
1209 | if (err) |
1210 | return err; | |
33ff9823 | 1211 | err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); |
17a52670 AS |
1212 | if (err) |
1213 | return err; | |
33ff9823 | 1214 | err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); |
17a52670 AS |
1215 | if (err) |
1216 | return err; | |
33ff9823 | 1217 | err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); |
17a52670 AS |
1218 | if (err) |
1219 | return err; | |
1220 | ||
435faee1 DB |
1221 | /* Mark slots with STACK_MISC in case of raw mode, stack offset |
1222 | * is inferred from register state. | |
1223 | */ | |
1224 | for (i = 0; i < meta.access_size; i++) { | |
1225 | err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); | |
1226 | if (err) | |
1227 | return err; | |
1228 | } | |
1229 | ||
17a52670 AS |
1230 | /* reset caller saved regs */ |
1231 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
1232 | reg = regs + caller_saved[i]; | |
1233 | reg->type = NOT_INIT; | |
1234 | reg->imm = 0; | |
1235 | } | |
1236 | ||
1237 | /* update return register */ | |
1238 | if (fn->ret_type == RET_INTEGER) { | |
1239 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1240 | } else if (fn->ret_type == RET_VOID) { | |
1241 | regs[BPF_REG_0].type = NOT_INIT; | |
1242 | } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { | |
1243 | regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; | |
1244 | /* remember map_ptr, so that check_map_access() | |
1245 | * can check 'value_size' boundary of memory access | |
1246 | * to map element returned from bpf_map_lookup_elem() | |
1247 | */ | |
33ff9823 | 1248 | if (meta.map_ptr == NULL) { |
17a52670 AS |
1249 | verbose("kernel subsystem misconfigured verifier\n"); |
1250 | return -EINVAL; | |
1251 | } | |
33ff9823 | 1252 | regs[BPF_REG_0].map_ptr = meta.map_ptr; |
17a52670 AS |
1253 | } else { |
1254 | verbose("unknown return type %d of func %d\n", | |
1255 | fn->ret_type, func_id); | |
1256 | return -EINVAL; | |
1257 | } | |
04fd61ab | 1258 | |
33ff9823 | 1259 | err = check_map_func_compatibility(meta.map_ptr, func_id); |
35578d79 KX |
1260 | if (err) |
1261 | return err; | |
04fd61ab | 1262 | |
969bf05e AS |
1263 | if (changes_data) |
1264 | clear_all_pkt_pointers(env); | |
1265 | return 0; | |
1266 | } | |
1267 | ||
1268 | static int check_packet_ptr_add(struct verifier_env *env, struct bpf_insn *insn) | |
1269 | { | |
1270 | struct reg_state *regs = env->cur_state.regs; | |
1271 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1272 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1b9b69ec | 1273 | struct reg_state tmp_reg; |
969bf05e AS |
1274 | s32 imm; |
1275 | ||
1276 | if (BPF_SRC(insn->code) == BPF_K) { | |
1277 | /* pkt_ptr += imm */ | |
1278 | imm = insn->imm; | |
1279 | ||
1280 | add_imm: | |
1281 | if (imm <= 0) { | |
1282 | verbose("addition of negative constant to packet pointer is not allowed\n"); | |
1283 | return -EACCES; | |
1284 | } | |
1285 | if (imm >= MAX_PACKET_OFF || | |
1286 | imm + dst_reg->off >= MAX_PACKET_OFF) { | |
1287 | verbose("constant %d is too large to add to packet pointer\n", | |
1288 | imm); | |
1289 | return -EACCES; | |
1290 | } | |
1291 | /* a constant was added to pkt_ptr. | |
1292 | * Remember it while keeping the same 'id' | |
1293 | */ | |
1294 | dst_reg->off += imm; | |
1295 | } else { | |
1b9b69ec AS |
1296 | if (src_reg->type == PTR_TO_PACKET) { |
1297 | /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ | |
1298 | tmp_reg = *dst_reg; /* save r7 state */ | |
1299 | *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ | |
1300 | src_reg = &tmp_reg; /* pretend it's src_reg state */ | |
1301 | /* if the checks below reject it, the copy won't matter, | |
1302 | * since we're rejecting the whole program. If all ok, | |
1303 | * then imm22 state will be added to r7 | |
1304 | * and r7 will be pkt(id=0,off=22,r=62) while | |
1305 | * r6 will stay as pkt(id=0,off=0,r=62) | |
1306 | */ | |
1307 | } | |
1308 | ||
969bf05e AS |
1309 | if (src_reg->type == CONST_IMM) { |
1310 | /* pkt_ptr += reg where reg is known constant */ | |
1311 | imm = src_reg->imm; | |
1312 | goto add_imm; | |
1313 | } | |
1314 | /* disallow pkt_ptr += reg | |
1315 | * if reg is not uknown_value with guaranteed zero upper bits | |
1316 | * otherwise pkt_ptr may overflow and addition will become | |
1317 | * subtraction which is not allowed | |
1318 | */ | |
1319 | if (src_reg->type != UNKNOWN_VALUE) { | |
1320 | verbose("cannot add '%s' to ptr_to_packet\n", | |
1321 | reg_type_str[src_reg->type]); | |
1322 | return -EACCES; | |
1323 | } | |
1324 | if (src_reg->imm < 48) { | |
1325 | verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", | |
1326 | src_reg->imm); | |
1327 | return -EACCES; | |
1328 | } | |
1329 | /* dst_reg stays as pkt_ptr type and since some positive | |
1330 | * integer value was added to the pointer, increment its 'id' | |
1331 | */ | |
1f415a74 | 1332 | dst_reg->id = ++env->id_gen; |
969bf05e AS |
1333 | |
1334 | /* something was added to pkt_ptr, set range and off to zero */ | |
1335 | dst_reg->off = 0; | |
1336 | dst_reg->range = 0; | |
1337 | } | |
1338 | return 0; | |
1339 | } | |
1340 | ||
1341 | static int evaluate_reg_alu(struct verifier_env *env, struct bpf_insn *insn) | |
1342 | { | |
1343 | struct reg_state *regs = env->cur_state.regs; | |
1344 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1345 | u8 opcode = BPF_OP(insn->code); | |
1346 | s64 imm_log2; | |
1347 | ||
1348 | /* for type == UNKNOWN_VALUE: | |
1349 | * imm > 0 -> number of zero upper bits | |
1350 | * imm == 0 -> don't track which is the same as all bits can be non-zero | |
1351 | */ | |
1352 | ||
1353 | if (BPF_SRC(insn->code) == BPF_X) { | |
1354 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1355 | ||
1356 | if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && | |
1357 | dst_reg->imm && opcode == BPF_ADD) { | |
1358 | /* dreg += sreg | |
1359 | * where both have zero upper bits. Adding them | |
1360 | * can only result making one more bit non-zero | |
1361 | * in the larger value. | |
1362 | * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) | |
1363 | * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) | |
1364 | */ | |
1365 | dst_reg->imm = min(dst_reg->imm, src_reg->imm); | |
1366 | dst_reg->imm--; | |
1367 | return 0; | |
1368 | } | |
1369 | if (src_reg->type == CONST_IMM && src_reg->imm > 0 && | |
1370 | dst_reg->imm && opcode == BPF_ADD) { | |
1371 | /* dreg += sreg | |
1372 | * where dreg has zero upper bits and sreg is const. | |
1373 | * Adding them can only result making one more bit | |
1374 | * non-zero in the larger value. | |
1375 | */ | |
1376 | imm_log2 = __ilog2_u64((long long)src_reg->imm); | |
1377 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1378 | dst_reg->imm--; | |
1379 | return 0; | |
1380 | } | |
1381 | /* all other cases non supported yet, just mark dst_reg */ | |
1382 | dst_reg->imm = 0; | |
1383 | return 0; | |
1384 | } | |
1385 | ||
1386 | /* sign extend 32-bit imm into 64-bit to make sure that | |
1387 | * negative values occupy bit 63. Note ilog2() would have | |
1388 | * been incorrect, since sizeof(insn->imm) == 4 | |
1389 | */ | |
1390 | imm_log2 = __ilog2_u64((long long)insn->imm); | |
1391 | ||
1392 | if (dst_reg->imm && opcode == BPF_LSH) { | |
1393 | /* reg <<= imm | |
1394 | * if reg was a result of 2 byte load, then its imm == 48 | |
1395 | * which means that upper 48 bits are zero and shifting this reg | |
1396 | * left by 4 would mean that upper 44 bits are still zero | |
1397 | */ | |
1398 | dst_reg->imm -= insn->imm; | |
1399 | } else if (dst_reg->imm && opcode == BPF_MUL) { | |
1400 | /* reg *= imm | |
1401 | * if multiplying by 14 subtract 4 | |
1402 | * This is conservative calculation of upper zero bits. | |
1403 | * It's not trying to special case insn->imm == 1 or 0 cases | |
1404 | */ | |
1405 | dst_reg->imm -= imm_log2 + 1; | |
1406 | } else if (opcode == BPF_AND) { | |
1407 | /* reg &= imm */ | |
1408 | dst_reg->imm = 63 - imm_log2; | |
1409 | } else if (dst_reg->imm && opcode == BPF_ADD) { | |
1410 | /* reg += imm */ | |
1411 | dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); | |
1412 | dst_reg->imm--; | |
1413 | } else if (opcode == BPF_RSH) { | |
1414 | /* reg >>= imm | |
1415 | * which means that after right shift, upper bits will be zero | |
1416 | * note that verifier already checked that | |
1417 | * 0 <= imm < 64 for shift insn | |
1418 | */ | |
1419 | dst_reg->imm += insn->imm; | |
1420 | if (unlikely(dst_reg->imm > 64)) | |
1421 | /* some dumb code did: | |
1422 | * r2 = *(u32 *)mem; | |
1423 | * r2 >>= 32; | |
1424 | * and all bits are zero now */ | |
1425 | dst_reg->imm = 64; | |
1426 | } else { | |
1427 | /* all other alu ops, means that we don't know what will | |
1428 | * happen to the value, mark it with unknown number of zero bits | |
1429 | */ | |
1430 | dst_reg->imm = 0; | |
1431 | } | |
1432 | ||
1433 | if (dst_reg->imm < 0) { | |
1434 | /* all 64 bits of the register can contain non-zero bits | |
1435 | * and such value cannot be added to ptr_to_packet, since it | |
1436 | * may overflow, mark it as unknown to avoid further eval | |
1437 | */ | |
1438 | dst_reg->imm = 0; | |
1439 | } | |
1440 | return 0; | |
1441 | } | |
1442 | ||
1443 | static int evaluate_reg_imm_alu(struct verifier_env *env, struct bpf_insn *insn) | |
1444 | { | |
1445 | struct reg_state *regs = env->cur_state.regs; | |
1446 | struct reg_state *dst_reg = ®s[insn->dst_reg]; | |
1447 | struct reg_state *src_reg = ®s[insn->src_reg]; | |
1448 | u8 opcode = BPF_OP(insn->code); | |
1449 | ||
1450 | /* dst_reg->type == CONST_IMM here, simulate execution of 'add' insn. | |
1451 | * Don't care about overflow or negative values, just add them | |
1452 | */ | |
1453 | if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) | |
1454 | dst_reg->imm += insn->imm; | |
1455 | else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && | |
1456 | src_reg->type == CONST_IMM) | |
1457 | dst_reg->imm += src_reg->imm; | |
1458 | else | |
1459 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1460 | return 0; |
1461 | } | |
1462 | ||
1463 | /* check validity of 32-bit and 64-bit arithmetic operations */ | |
1be7f75d | 1464 | static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn) |
17a52670 | 1465 | { |
1a0dc1ac | 1466 | struct reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1467 | u8 opcode = BPF_OP(insn->code); |
1468 | int err; | |
1469 | ||
1470 | if (opcode == BPF_END || opcode == BPF_NEG) { | |
1471 | if (opcode == BPF_NEG) { | |
1472 | if (BPF_SRC(insn->code) != 0 || | |
1473 | insn->src_reg != BPF_REG_0 || | |
1474 | insn->off != 0 || insn->imm != 0) { | |
1475 | verbose("BPF_NEG uses reserved fields\n"); | |
1476 | return -EINVAL; | |
1477 | } | |
1478 | } else { | |
1479 | if (insn->src_reg != BPF_REG_0 || insn->off != 0 || | |
1480 | (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { | |
1481 | verbose("BPF_END uses reserved fields\n"); | |
1482 | return -EINVAL; | |
1483 | } | |
1484 | } | |
1485 | ||
1486 | /* check src operand */ | |
1487 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1488 | if (err) | |
1489 | return err; | |
1490 | ||
1be7f75d AS |
1491 | if (is_pointer_value(env, insn->dst_reg)) { |
1492 | verbose("R%d pointer arithmetic prohibited\n", | |
1493 | insn->dst_reg); | |
1494 | return -EACCES; | |
1495 | } | |
1496 | ||
17a52670 AS |
1497 | /* check dest operand */ |
1498 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1499 | if (err) | |
1500 | return err; | |
1501 | ||
1502 | } else if (opcode == BPF_MOV) { | |
1503 | ||
1504 | if (BPF_SRC(insn->code) == BPF_X) { | |
1505 | if (insn->imm != 0 || insn->off != 0) { | |
1506 | verbose("BPF_MOV uses reserved fields\n"); | |
1507 | return -EINVAL; | |
1508 | } | |
1509 | ||
1510 | /* check src operand */ | |
1511 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1512 | if (err) | |
1513 | return err; | |
1514 | } else { | |
1515 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1516 | verbose("BPF_MOV uses reserved fields\n"); | |
1517 | return -EINVAL; | |
1518 | } | |
1519 | } | |
1520 | ||
1521 | /* check dest operand */ | |
1522 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1523 | if (err) | |
1524 | return err; | |
1525 | ||
1526 | if (BPF_SRC(insn->code) == BPF_X) { | |
1527 | if (BPF_CLASS(insn->code) == BPF_ALU64) { | |
1528 | /* case: R1 = R2 | |
1529 | * copy register state to dest reg | |
1530 | */ | |
1531 | regs[insn->dst_reg] = regs[insn->src_reg]; | |
1532 | } else { | |
1be7f75d AS |
1533 | if (is_pointer_value(env, insn->src_reg)) { |
1534 | verbose("R%d partial copy of pointer\n", | |
1535 | insn->src_reg); | |
1536 | return -EACCES; | |
1537 | } | |
17a52670 AS |
1538 | regs[insn->dst_reg].type = UNKNOWN_VALUE; |
1539 | regs[insn->dst_reg].map_ptr = NULL; | |
1540 | } | |
1541 | } else { | |
1542 | /* case: R = imm | |
1543 | * remember the value we stored into this reg | |
1544 | */ | |
1545 | regs[insn->dst_reg].type = CONST_IMM; | |
1546 | regs[insn->dst_reg].imm = insn->imm; | |
1547 | } | |
1548 | ||
1549 | } else if (opcode > BPF_END) { | |
1550 | verbose("invalid BPF_ALU opcode %x\n", opcode); | |
1551 | return -EINVAL; | |
1552 | ||
1553 | } else { /* all other ALU ops: and, sub, xor, add, ... */ | |
1554 | ||
17a52670 AS |
1555 | if (BPF_SRC(insn->code) == BPF_X) { |
1556 | if (insn->imm != 0 || insn->off != 0) { | |
1557 | verbose("BPF_ALU uses reserved fields\n"); | |
1558 | return -EINVAL; | |
1559 | } | |
1560 | /* check src1 operand */ | |
1561 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1562 | if (err) | |
1563 | return err; | |
1564 | } else { | |
1565 | if (insn->src_reg != BPF_REG_0 || insn->off != 0) { | |
1566 | verbose("BPF_ALU uses reserved fields\n"); | |
1567 | return -EINVAL; | |
1568 | } | |
1569 | } | |
1570 | ||
1571 | /* check src2 operand */ | |
1572 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1573 | if (err) | |
1574 | return err; | |
1575 | ||
1576 | if ((opcode == BPF_MOD || opcode == BPF_DIV) && | |
1577 | BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { | |
1578 | verbose("div by zero\n"); | |
1579 | return -EINVAL; | |
1580 | } | |
1581 | ||
229394e8 RV |
1582 | if ((opcode == BPF_LSH || opcode == BPF_RSH || |
1583 | opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { | |
1584 | int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; | |
1585 | ||
1586 | if (insn->imm < 0 || insn->imm >= size) { | |
1587 | verbose("invalid shift %d\n", insn->imm); | |
1588 | return -EINVAL; | |
1589 | } | |
1590 | } | |
1591 | ||
1a0dc1ac AS |
1592 | /* check dest operand */ |
1593 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
1594 | if (err) | |
1595 | return err; | |
1596 | ||
1597 | dst_reg = ®s[insn->dst_reg]; | |
1598 | ||
17a52670 AS |
1599 | /* pattern match 'bpf_add Rx, imm' instruction */ |
1600 | if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && | |
1a0dc1ac AS |
1601 | dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { |
1602 | dst_reg->type = PTR_TO_STACK; | |
1603 | dst_reg->imm = insn->imm; | |
1604 | return 0; | |
969bf05e AS |
1605 | } else if (opcode == BPF_ADD && |
1606 | BPF_CLASS(insn->code) == BPF_ALU64 && | |
1b9b69ec AS |
1607 | (dst_reg->type == PTR_TO_PACKET || |
1608 | (BPF_SRC(insn->code) == BPF_X && | |
1609 | regs[insn->src_reg].type == PTR_TO_PACKET))) { | |
969bf05e AS |
1610 | /* ptr_to_packet += K|X */ |
1611 | return check_packet_ptr_add(env, insn); | |
1612 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1613 | dst_reg->type == UNKNOWN_VALUE && | |
1614 | env->allow_ptr_leaks) { | |
1615 | /* unknown += K|X */ | |
1616 | return evaluate_reg_alu(env, insn); | |
1617 | } else if (BPF_CLASS(insn->code) == BPF_ALU64 && | |
1618 | dst_reg->type == CONST_IMM && | |
1619 | env->allow_ptr_leaks) { | |
1620 | /* reg_imm += K|X */ | |
1621 | return evaluate_reg_imm_alu(env, insn); | |
1be7f75d AS |
1622 | } else if (is_pointer_value(env, insn->dst_reg)) { |
1623 | verbose("R%d pointer arithmetic prohibited\n", | |
1624 | insn->dst_reg); | |
1625 | return -EACCES; | |
1626 | } else if (BPF_SRC(insn->code) == BPF_X && | |
1627 | is_pointer_value(env, insn->src_reg)) { | |
1628 | verbose("R%d pointer arithmetic prohibited\n", | |
1629 | insn->src_reg); | |
1630 | return -EACCES; | |
1631 | } | |
17a52670 | 1632 | |
1a0dc1ac AS |
1633 | /* mark dest operand */ |
1634 | mark_reg_unknown_value(regs, insn->dst_reg); | |
17a52670 AS |
1635 | } |
1636 | ||
1637 | return 0; | |
1638 | } | |
1639 | ||
969bf05e AS |
1640 | static void find_good_pkt_pointers(struct verifier_env *env, |
1641 | struct reg_state *dst_reg) | |
1642 | { | |
1643 | struct verifier_state *state = &env->cur_state; | |
1644 | struct reg_state *regs = state->regs, *reg; | |
1645 | int i; | |
1646 | /* r2 = r3; | |
1647 | * r2 += 8 | |
1648 | * if (r2 > pkt_end) goto somewhere | |
1649 | * r2 == dst_reg, pkt_end == src_reg, | |
1650 | * r2=pkt(id=n,off=8,r=0) | |
1651 | * r3=pkt(id=n,off=0,r=0) | |
1652 | * find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) | |
1653 | * so that range of bytes [r3, r3 + 8) is safe to access | |
1654 | */ | |
1655 | for (i = 0; i < MAX_BPF_REG; i++) | |
1656 | if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) | |
1657 | regs[i].range = dst_reg->off; | |
1658 | ||
1659 | for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { | |
1660 | if (state->stack_slot_type[i] != STACK_SPILL) | |
1661 | continue; | |
1662 | reg = &state->spilled_regs[i / BPF_REG_SIZE]; | |
1663 | if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) | |
1664 | reg->range = dst_reg->off; | |
1665 | } | |
1666 | } | |
1667 | ||
17a52670 AS |
1668 | static int check_cond_jmp_op(struct verifier_env *env, |
1669 | struct bpf_insn *insn, int *insn_idx) | |
1670 | { | |
1a0dc1ac | 1671 | struct reg_state *regs = env->cur_state.regs, *dst_reg; |
17a52670 AS |
1672 | struct verifier_state *other_branch; |
1673 | u8 opcode = BPF_OP(insn->code); | |
1674 | int err; | |
1675 | ||
1676 | if (opcode > BPF_EXIT) { | |
1677 | verbose("invalid BPF_JMP opcode %x\n", opcode); | |
1678 | return -EINVAL; | |
1679 | } | |
1680 | ||
1681 | if (BPF_SRC(insn->code) == BPF_X) { | |
1682 | if (insn->imm != 0) { | |
1683 | verbose("BPF_JMP uses reserved fields\n"); | |
1684 | return -EINVAL; | |
1685 | } | |
1686 | ||
1687 | /* check src1 operand */ | |
1688 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1689 | if (err) | |
1690 | return err; | |
1be7f75d AS |
1691 | |
1692 | if (is_pointer_value(env, insn->src_reg)) { | |
1693 | verbose("R%d pointer comparison prohibited\n", | |
1694 | insn->src_reg); | |
1695 | return -EACCES; | |
1696 | } | |
17a52670 AS |
1697 | } else { |
1698 | if (insn->src_reg != BPF_REG_0) { | |
1699 | verbose("BPF_JMP uses reserved fields\n"); | |
1700 | return -EINVAL; | |
1701 | } | |
1702 | } | |
1703 | ||
1704 | /* check src2 operand */ | |
1705 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
1706 | if (err) | |
1707 | return err; | |
1708 | ||
1a0dc1ac AS |
1709 | dst_reg = ®s[insn->dst_reg]; |
1710 | ||
17a52670 AS |
1711 | /* detect if R == 0 where R was initialized to zero earlier */ |
1712 | if (BPF_SRC(insn->code) == BPF_K && | |
1713 | (opcode == BPF_JEQ || opcode == BPF_JNE) && | |
1a0dc1ac | 1714 | dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { |
17a52670 AS |
1715 | if (opcode == BPF_JEQ) { |
1716 | /* if (imm == imm) goto pc+off; | |
1717 | * only follow the goto, ignore fall-through | |
1718 | */ | |
1719 | *insn_idx += insn->off; | |
1720 | return 0; | |
1721 | } else { | |
1722 | /* if (imm != imm) goto pc+off; | |
1723 | * only follow fall-through branch, since | |
1724 | * that's where the program will go | |
1725 | */ | |
1726 | return 0; | |
1727 | } | |
1728 | } | |
1729 | ||
1730 | other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); | |
1731 | if (!other_branch) | |
1732 | return -EFAULT; | |
1733 | ||
1734 | /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */ | |
1735 | if (BPF_SRC(insn->code) == BPF_K && | |
1a0dc1ac AS |
1736 | insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && |
1737 | dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { | |
17a52670 AS |
1738 | if (opcode == BPF_JEQ) { |
1739 | /* next fallthrough insn can access memory via | |
1740 | * this register | |
1741 | */ | |
1742 | regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; | |
1743 | /* branch targer cannot access it, since reg == 0 */ | |
735b4333 AS |
1744 | mark_reg_unknown_value(other_branch->regs, |
1745 | insn->dst_reg); | |
17a52670 AS |
1746 | } else { |
1747 | other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; | |
735b4333 | 1748 | mark_reg_unknown_value(regs, insn->dst_reg); |
17a52670 | 1749 | } |
969bf05e AS |
1750 | } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && |
1751 | dst_reg->type == PTR_TO_PACKET && | |
1752 | regs[insn->src_reg].type == PTR_TO_PACKET_END) { | |
1753 | find_good_pkt_pointers(env, dst_reg); | |
1be7f75d AS |
1754 | } else if (is_pointer_value(env, insn->dst_reg)) { |
1755 | verbose("R%d pointer comparison prohibited\n", insn->dst_reg); | |
1756 | return -EACCES; | |
17a52670 AS |
1757 | } |
1758 | if (log_level) | |
1a0dc1ac | 1759 | print_verifier_state(&env->cur_state); |
17a52670 AS |
1760 | return 0; |
1761 | } | |
1762 | ||
0246e64d AS |
1763 | /* return the map pointer stored inside BPF_LD_IMM64 instruction */ |
1764 | static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) | |
1765 | { | |
1766 | u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; | |
1767 | ||
1768 | return (struct bpf_map *) (unsigned long) imm64; | |
1769 | } | |
1770 | ||
17a52670 AS |
1771 | /* verify BPF_LD_IMM64 instruction */ |
1772 | static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn) | |
1773 | { | |
1774 | struct reg_state *regs = env->cur_state.regs; | |
1775 | int err; | |
1776 | ||
1777 | if (BPF_SIZE(insn->code) != BPF_DW) { | |
1778 | verbose("invalid BPF_LD_IMM insn\n"); | |
1779 | return -EINVAL; | |
1780 | } | |
1781 | if (insn->off != 0) { | |
1782 | verbose("BPF_LD_IMM64 uses reserved fields\n"); | |
1783 | return -EINVAL; | |
1784 | } | |
1785 | ||
1786 | err = check_reg_arg(regs, insn->dst_reg, DST_OP); | |
1787 | if (err) | |
1788 | return err; | |
1789 | ||
1790 | if (insn->src_reg == 0) | |
1791 | /* generic move 64-bit immediate into a register */ | |
1792 | return 0; | |
1793 | ||
1794 | /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ | |
1795 | BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); | |
1796 | ||
1797 | regs[insn->dst_reg].type = CONST_PTR_TO_MAP; | |
1798 | regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); | |
1799 | return 0; | |
1800 | } | |
1801 | ||
96be4325 DB |
1802 | static bool may_access_skb(enum bpf_prog_type type) |
1803 | { | |
1804 | switch (type) { | |
1805 | case BPF_PROG_TYPE_SOCKET_FILTER: | |
1806 | case BPF_PROG_TYPE_SCHED_CLS: | |
94caee8c | 1807 | case BPF_PROG_TYPE_SCHED_ACT: |
96be4325 DB |
1808 | return true; |
1809 | default: | |
1810 | return false; | |
1811 | } | |
1812 | } | |
1813 | ||
ddd872bc AS |
1814 | /* verify safety of LD_ABS|LD_IND instructions: |
1815 | * - they can only appear in the programs where ctx == skb | |
1816 | * - since they are wrappers of function calls, they scratch R1-R5 registers, | |
1817 | * preserve R6-R9, and store return value into R0 | |
1818 | * | |
1819 | * Implicit input: | |
1820 | * ctx == skb == R6 == CTX | |
1821 | * | |
1822 | * Explicit input: | |
1823 | * SRC == any register | |
1824 | * IMM == 32-bit immediate | |
1825 | * | |
1826 | * Output: | |
1827 | * R0 - 8/16/32-bit skb data converted to cpu endianness | |
1828 | */ | |
1829 | static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn) | |
1830 | { | |
1831 | struct reg_state *regs = env->cur_state.regs; | |
1832 | u8 mode = BPF_MODE(insn->code); | |
1833 | struct reg_state *reg; | |
1834 | int i, err; | |
1835 | ||
24701ece | 1836 | if (!may_access_skb(env->prog->type)) { |
1a0dc1ac | 1837 | verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); |
ddd872bc AS |
1838 | return -EINVAL; |
1839 | } | |
1840 | ||
1841 | if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || | |
d82bccc6 | 1842 | BPF_SIZE(insn->code) == BPF_DW || |
ddd872bc | 1843 | (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { |
1a0dc1ac | 1844 | verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); |
ddd872bc AS |
1845 | return -EINVAL; |
1846 | } | |
1847 | ||
1848 | /* check whether implicit source operand (register R6) is readable */ | |
1849 | err = check_reg_arg(regs, BPF_REG_6, SRC_OP); | |
1850 | if (err) | |
1851 | return err; | |
1852 | ||
1853 | if (regs[BPF_REG_6].type != PTR_TO_CTX) { | |
1854 | verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); | |
1855 | return -EINVAL; | |
1856 | } | |
1857 | ||
1858 | if (mode == BPF_IND) { | |
1859 | /* check explicit source operand */ | |
1860 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
1861 | if (err) | |
1862 | return err; | |
1863 | } | |
1864 | ||
1865 | /* reset caller saved regs to unreadable */ | |
1866 | for (i = 0; i < CALLER_SAVED_REGS; i++) { | |
1867 | reg = regs + caller_saved[i]; | |
1868 | reg->type = NOT_INIT; | |
1869 | reg->imm = 0; | |
1870 | } | |
1871 | ||
1872 | /* mark destination R0 register as readable, since it contains | |
1873 | * the value fetched from the packet | |
1874 | */ | |
1875 | regs[BPF_REG_0].type = UNKNOWN_VALUE; | |
1876 | return 0; | |
1877 | } | |
1878 | ||
475fb78f AS |
1879 | /* non-recursive DFS pseudo code |
1880 | * 1 procedure DFS-iterative(G,v): | |
1881 | * 2 label v as discovered | |
1882 | * 3 let S be a stack | |
1883 | * 4 S.push(v) | |
1884 | * 5 while S is not empty | |
1885 | * 6 t <- S.pop() | |
1886 | * 7 if t is what we're looking for: | |
1887 | * 8 return t | |
1888 | * 9 for all edges e in G.adjacentEdges(t) do | |
1889 | * 10 if edge e is already labelled | |
1890 | * 11 continue with the next edge | |
1891 | * 12 w <- G.adjacentVertex(t,e) | |
1892 | * 13 if vertex w is not discovered and not explored | |
1893 | * 14 label e as tree-edge | |
1894 | * 15 label w as discovered | |
1895 | * 16 S.push(w) | |
1896 | * 17 continue at 5 | |
1897 | * 18 else if vertex w is discovered | |
1898 | * 19 label e as back-edge | |
1899 | * 20 else | |
1900 | * 21 // vertex w is explored | |
1901 | * 22 label e as forward- or cross-edge | |
1902 | * 23 label t as explored | |
1903 | * 24 S.pop() | |
1904 | * | |
1905 | * convention: | |
1906 | * 0x10 - discovered | |
1907 | * 0x11 - discovered and fall-through edge labelled | |
1908 | * 0x12 - discovered and fall-through and branch edges labelled | |
1909 | * 0x20 - explored | |
1910 | */ | |
1911 | ||
1912 | enum { | |
1913 | DISCOVERED = 0x10, | |
1914 | EXPLORED = 0x20, | |
1915 | FALLTHROUGH = 1, | |
1916 | BRANCH = 2, | |
1917 | }; | |
1918 | ||
f1bca824 AS |
1919 | #define STATE_LIST_MARK ((struct verifier_state_list *) -1L) |
1920 | ||
475fb78f AS |
1921 | static int *insn_stack; /* stack of insns to process */ |
1922 | static int cur_stack; /* current stack index */ | |
1923 | static int *insn_state; | |
1924 | ||
1925 | /* t, w, e - match pseudo-code above: | |
1926 | * t - index of current instruction | |
1927 | * w - next instruction | |
1928 | * e - edge | |
1929 | */ | |
1930 | static int push_insn(int t, int w, int e, struct verifier_env *env) | |
1931 | { | |
1932 | if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) | |
1933 | return 0; | |
1934 | ||
1935 | if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) | |
1936 | return 0; | |
1937 | ||
1938 | if (w < 0 || w >= env->prog->len) { | |
1939 | verbose("jump out of range from insn %d to %d\n", t, w); | |
1940 | return -EINVAL; | |
1941 | } | |
1942 | ||
f1bca824 AS |
1943 | if (e == BRANCH) |
1944 | /* mark branch target for state pruning */ | |
1945 | env->explored_states[w] = STATE_LIST_MARK; | |
1946 | ||
475fb78f AS |
1947 | if (insn_state[w] == 0) { |
1948 | /* tree-edge */ | |
1949 | insn_state[t] = DISCOVERED | e; | |
1950 | insn_state[w] = DISCOVERED; | |
1951 | if (cur_stack >= env->prog->len) | |
1952 | return -E2BIG; | |
1953 | insn_stack[cur_stack++] = w; | |
1954 | return 1; | |
1955 | } else if ((insn_state[w] & 0xF0) == DISCOVERED) { | |
1956 | verbose("back-edge from insn %d to %d\n", t, w); | |
1957 | return -EINVAL; | |
1958 | } else if (insn_state[w] == EXPLORED) { | |
1959 | /* forward- or cross-edge */ | |
1960 | insn_state[t] = DISCOVERED | e; | |
1961 | } else { | |
1962 | verbose("insn state internal bug\n"); | |
1963 | return -EFAULT; | |
1964 | } | |
1965 | return 0; | |
1966 | } | |
1967 | ||
1968 | /* non-recursive depth-first-search to detect loops in BPF program | |
1969 | * loop == back-edge in directed graph | |
1970 | */ | |
1971 | static int check_cfg(struct verifier_env *env) | |
1972 | { | |
1973 | struct bpf_insn *insns = env->prog->insnsi; | |
1974 | int insn_cnt = env->prog->len; | |
1975 | int ret = 0; | |
1976 | int i, t; | |
1977 | ||
1978 | insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
1979 | if (!insn_state) | |
1980 | return -ENOMEM; | |
1981 | ||
1982 | insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); | |
1983 | if (!insn_stack) { | |
1984 | kfree(insn_state); | |
1985 | return -ENOMEM; | |
1986 | } | |
1987 | ||
1988 | insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ | |
1989 | insn_stack[0] = 0; /* 0 is the first instruction */ | |
1990 | cur_stack = 1; | |
1991 | ||
1992 | peek_stack: | |
1993 | if (cur_stack == 0) | |
1994 | goto check_state; | |
1995 | t = insn_stack[cur_stack - 1]; | |
1996 | ||
1997 | if (BPF_CLASS(insns[t].code) == BPF_JMP) { | |
1998 | u8 opcode = BPF_OP(insns[t].code); | |
1999 | ||
2000 | if (opcode == BPF_EXIT) { | |
2001 | goto mark_explored; | |
2002 | } else if (opcode == BPF_CALL) { | |
2003 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2004 | if (ret == 1) | |
2005 | goto peek_stack; | |
2006 | else if (ret < 0) | |
2007 | goto err_free; | |
07016151 DB |
2008 | if (t + 1 < insn_cnt) |
2009 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2010 | } else if (opcode == BPF_JA) { |
2011 | if (BPF_SRC(insns[t].code) != BPF_K) { | |
2012 | ret = -EINVAL; | |
2013 | goto err_free; | |
2014 | } | |
2015 | /* unconditional jump with single edge */ | |
2016 | ret = push_insn(t, t + insns[t].off + 1, | |
2017 | FALLTHROUGH, env); | |
2018 | if (ret == 1) | |
2019 | goto peek_stack; | |
2020 | else if (ret < 0) | |
2021 | goto err_free; | |
f1bca824 AS |
2022 | /* tell verifier to check for equivalent states |
2023 | * after every call and jump | |
2024 | */ | |
c3de6317 AS |
2025 | if (t + 1 < insn_cnt) |
2026 | env->explored_states[t + 1] = STATE_LIST_MARK; | |
475fb78f AS |
2027 | } else { |
2028 | /* conditional jump with two edges */ | |
2029 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2030 | if (ret == 1) | |
2031 | goto peek_stack; | |
2032 | else if (ret < 0) | |
2033 | goto err_free; | |
2034 | ||
2035 | ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); | |
2036 | if (ret == 1) | |
2037 | goto peek_stack; | |
2038 | else if (ret < 0) | |
2039 | goto err_free; | |
2040 | } | |
2041 | } else { | |
2042 | /* all other non-branch instructions with single | |
2043 | * fall-through edge | |
2044 | */ | |
2045 | ret = push_insn(t, t + 1, FALLTHROUGH, env); | |
2046 | if (ret == 1) | |
2047 | goto peek_stack; | |
2048 | else if (ret < 0) | |
2049 | goto err_free; | |
2050 | } | |
2051 | ||
2052 | mark_explored: | |
2053 | insn_state[t] = EXPLORED; | |
2054 | if (cur_stack-- <= 0) { | |
2055 | verbose("pop stack internal bug\n"); | |
2056 | ret = -EFAULT; | |
2057 | goto err_free; | |
2058 | } | |
2059 | goto peek_stack; | |
2060 | ||
2061 | check_state: | |
2062 | for (i = 0; i < insn_cnt; i++) { | |
2063 | if (insn_state[i] != EXPLORED) { | |
2064 | verbose("unreachable insn %d\n", i); | |
2065 | ret = -EINVAL; | |
2066 | goto err_free; | |
2067 | } | |
2068 | } | |
2069 | ret = 0; /* cfg looks good */ | |
2070 | ||
2071 | err_free: | |
2072 | kfree(insn_state); | |
2073 | kfree(insn_stack); | |
2074 | return ret; | |
2075 | } | |
2076 | ||
969bf05e AS |
2077 | /* the following conditions reduce the number of explored insns |
2078 | * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet | |
2079 | */ | |
2080 | static bool compare_ptrs_to_packet(struct reg_state *old, struct reg_state *cur) | |
2081 | { | |
2082 | if (old->id != cur->id) | |
2083 | return false; | |
2084 | ||
2085 | /* old ptr_to_packet is more conservative, since it allows smaller | |
2086 | * range. Ex: | |
2087 | * old(off=0,r=10) is equal to cur(off=0,r=20), because | |
2088 | * old(off=0,r=10) means that with range=10 the verifier proceeded | |
2089 | * further and found no issues with the program. Now we're in the same | |
2090 | * spot with cur(off=0,r=20), so we're safe too, since anything further | |
2091 | * will only be looking at most 10 bytes after this pointer. | |
2092 | */ | |
2093 | if (old->off == cur->off && old->range < cur->range) | |
2094 | return true; | |
2095 | ||
2096 | /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) | |
2097 | * since both cannot be used for packet access and safe(old) | |
2098 | * pointer has smaller off that could be used for further | |
2099 | * 'if (ptr > data_end)' check | |
2100 | * Ex: | |
2101 | * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean | |
2102 | * that we cannot access the packet. | |
2103 | * The safe range is: | |
2104 | * [ptr, ptr + range - off) | |
2105 | * so whenever off >=range, it means no safe bytes from this pointer. | |
2106 | * When comparing old->off <= cur->off, it means that older code | |
2107 | * went with smaller offset and that offset was later | |
2108 | * used to figure out the safe range after 'if (ptr > data_end)' check | |
2109 | * Say, 'old' state was explored like: | |
2110 | * ... R3(off=0, r=0) | |
2111 | * R4 = R3 + 20 | |
2112 | * ... now R4(off=20,r=0) <-- here | |
2113 | * if (R4 > data_end) | |
2114 | * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. | |
2115 | * ... the code further went all the way to bpf_exit. | |
2116 | * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). | |
2117 | * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier | |
2118 | * goes further, such cur_R4 will give larger safe packet range after | |
2119 | * 'if (R4 > data_end)' and all further insn were already good with r=20, | |
2120 | * so they will be good with r=30 and we can prune the search. | |
2121 | */ | |
2122 | if (old->off <= cur->off && | |
2123 | old->off >= old->range && cur->off >= cur->range) | |
2124 | return true; | |
2125 | ||
2126 | return false; | |
2127 | } | |
2128 | ||
f1bca824 AS |
2129 | /* compare two verifier states |
2130 | * | |
2131 | * all states stored in state_list are known to be valid, since | |
2132 | * verifier reached 'bpf_exit' instruction through them | |
2133 | * | |
2134 | * this function is called when verifier exploring different branches of | |
2135 | * execution popped from the state stack. If it sees an old state that has | |
2136 | * more strict register state and more strict stack state then this execution | |
2137 | * branch doesn't need to be explored further, since verifier already | |
2138 | * concluded that more strict state leads to valid finish. | |
2139 | * | |
2140 | * Therefore two states are equivalent if register state is more conservative | |
2141 | * and explored stack state is more conservative than the current one. | |
2142 | * Example: | |
2143 | * explored current | |
2144 | * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) | |
2145 | * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) | |
2146 | * | |
2147 | * In other words if current stack state (one being explored) has more | |
2148 | * valid slots than old one that already passed validation, it means | |
2149 | * the verifier can stop exploring and conclude that current state is valid too | |
2150 | * | |
2151 | * Similarly with registers. If explored state has register type as invalid | |
2152 | * whereas register type in current state is meaningful, it means that | |
2153 | * the current state will reach 'bpf_exit' instruction safely | |
2154 | */ | |
2155 | static bool states_equal(struct verifier_state *old, struct verifier_state *cur) | |
2156 | { | |
1a0dc1ac | 2157 | struct reg_state *rold, *rcur; |
f1bca824 AS |
2158 | int i; |
2159 | ||
2160 | for (i = 0; i < MAX_BPF_REG; i++) { | |
1a0dc1ac AS |
2161 | rold = &old->regs[i]; |
2162 | rcur = &cur->regs[i]; | |
2163 | ||
2164 | if (memcmp(rold, rcur, sizeof(*rold)) == 0) | |
2165 | continue; | |
2166 | ||
2167 | if (rold->type == NOT_INIT || | |
2168 | (rold->type == UNKNOWN_VALUE && rcur->type != NOT_INIT)) | |
2169 | continue; | |
2170 | ||
969bf05e AS |
2171 | if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && |
2172 | compare_ptrs_to_packet(rold, rcur)) | |
2173 | continue; | |
2174 | ||
1a0dc1ac | 2175 | return false; |
f1bca824 AS |
2176 | } |
2177 | ||
2178 | for (i = 0; i < MAX_BPF_STACK; i++) { | |
9c399760 AS |
2179 | if (old->stack_slot_type[i] == STACK_INVALID) |
2180 | continue; | |
2181 | if (old->stack_slot_type[i] != cur->stack_slot_type[i]) | |
2182 | /* Ex: old explored (safe) state has STACK_SPILL in | |
2183 | * this stack slot, but current has has STACK_MISC -> | |
2184 | * this verifier states are not equivalent, | |
2185 | * return false to continue verification of this path | |
2186 | */ | |
f1bca824 | 2187 | return false; |
9c399760 AS |
2188 | if (i % BPF_REG_SIZE) |
2189 | continue; | |
2190 | if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], | |
2191 | &cur->spilled_regs[i / BPF_REG_SIZE], | |
2192 | sizeof(old->spilled_regs[0]))) | |
2193 | /* when explored and current stack slot types are | |
2194 | * the same, check that stored pointers types | |
2195 | * are the same as well. | |
2196 | * Ex: explored safe path could have stored | |
2197 | * (struct reg_state) {.type = PTR_TO_STACK, .imm = -8} | |
2198 | * but current path has stored: | |
2199 | * (struct reg_state) {.type = PTR_TO_STACK, .imm = -16} | |
2200 | * such verifier states are not equivalent. | |
2201 | * return false to continue verification of this path | |
2202 | */ | |
2203 | return false; | |
2204 | else | |
2205 | continue; | |
f1bca824 AS |
2206 | } |
2207 | return true; | |
2208 | } | |
2209 | ||
2210 | static int is_state_visited(struct verifier_env *env, int insn_idx) | |
2211 | { | |
2212 | struct verifier_state_list *new_sl; | |
2213 | struct verifier_state_list *sl; | |
2214 | ||
2215 | sl = env->explored_states[insn_idx]; | |
2216 | if (!sl) | |
2217 | /* this 'insn_idx' instruction wasn't marked, so we will not | |
2218 | * be doing state search here | |
2219 | */ | |
2220 | return 0; | |
2221 | ||
2222 | while (sl != STATE_LIST_MARK) { | |
2223 | if (states_equal(&sl->state, &env->cur_state)) | |
2224 | /* reached equivalent register/stack state, | |
2225 | * prune the search | |
2226 | */ | |
2227 | return 1; | |
2228 | sl = sl->next; | |
2229 | } | |
2230 | ||
2231 | /* there were no equivalent states, remember current one. | |
2232 | * technically the current state is not proven to be safe yet, | |
2233 | * but it will either reach bpf_exit (which means it's safe) or | |
2234 | * it will be rejected. Since there are no loops, we won't be | |
2235 | * seeing this 'insn_idx' instruction again on the way to bpf_exit | |
2236 | */ | |
2237 | new_sl = kmalloc(sizeof(struct verifier_state_list), GFP_USER); | |
2238 | if (!new_sl) | |
2239 | return -ENOMEM; | |
2240 | ||
2241 | /* add new state to the head of linked list */ | |
2242 | memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); | |
2243 | new_sl->next = env->explored_states[insn_idx]; | |
2244 | env->explored_states[insn_idx] = new_sl; | |
2245 | return 0; | |
2246 | } | |
2247 | ||
17a52670 AS |
2248 | static int do_check(struct verifier_env *env) |
2249 | { | |
2250 | struct verifier_state *state = &env->cur_state; | |
2251 | struct bpf_insn *insns = env->prog->insnsi; | |
2252 | struct reg_state *regs = state->regs; | |
2253 | int insn_cnt = env->prog->len; | |
2254 | int insn_idx, prev_insn_idx = 0; | |
2255 | int insn_processed = 0; | |
2256 | bool do_print_state = false; | |
2257 | ||
2258 | init_reg_state(regs); | |
2259 | insn_idx = 0; | |
2260 | for (;;) { | |
2261 | struct bpf_insn *insn; | |
2262 | u8 class; | |
2263 | int err; | |
2264 | ||
2265 | if (insn_idx >= insn_cnt) { | |
2266 | verbose("invalid insn idx %d insn_cnt %d\n", | |
2267 | insn_idx, insn_cnt); | |
2268 | return -EFAULT; | |
2269 | } | |
2270 | ||
2271 | insn = &insns[insn_idx]; | |
2272 | class = BPF_CLASS(insn->code); | |
2273 | ||
07016151 | 2274 | if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { |
17a52670 AS |
2275 | verbose("BPF program is too large. Proccessed %d insn\n", |
2276 | insn_processed); | |
2277 | return -E2BIG; | |
2278 | } | |
2279 | ||
f1bca824 AS |
2280 | err = is_state_visited(env, insn_idx); |
2281 | if (err < 0) | |
2282 | return err; | |
2283 | if (err == 1) { | |
2284 | /* found equivalent state, can prune the search */ | |
2285 | if (log_level) { | |
2286 | if (do_print_state) | |
2287 | verbose("\nfrom %d to %d: safe\n", | |
2288 | prev_insn_idx, insn_idx); | |
2289 | else | |
2290 | verbose("%d: safe\n", insn_idx); | |
2291 | } | |
2292 | goto process_bpf_exit; | |
2293 | } | |
2294 | ||
17a52670 AS |
2295 | if (log_level && do_print_state) { |
2296 | verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx); | |
1a0dc1ac | 2297 | print_verifier_state(&env->cur_state); |
17a52670 AS |
2298 | do_print_state = false; |
2299 | } | |
2300 | ||
2301 | if (log_level) { | |
2302 | verbose("%d: ", insn_idx); | |
2303 | print_bpf_insn(insn); | |
2304 | } | |
2305 | ||
2306 | if (class == BPF_ALU || class == BPF_ALU64) { | |
1be7f75d | 2307 | err = check_alu_op(env, insn); |
17a52670 AS |
2308 | if (err) |
2309 | return err; | |
2310 | ||
2311 | } else if (class == BPF_LDX) { | |
9bac3d6d AS |
2312 | enum bpf_reg_type src_reg_type; |
2313 | ||
2314 | /* check for reserved fields is already done */ | |
2315 | ||
17a52670 AS |
2316 | /* check src operand */ |
2317 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2318 | if (err) | |
2319 | return err; | |
2320 | ||
2321 | err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); | |
2322 | if (err) | |
2323 | return err; | |
2324 | ||
725f9dcd AS |
2325 | src_reg_type = regs[insn->src_reg].type; |
2326 | ||
17a52670 AS |
2327 | /* check that memory (src_reg + off) is readable, |
2328 | * the state of dst_reg will be updated by this func | |
2329 | */ | |
2330 | err = check_mem_access(env, insn->src_reg, insn->off, | |
2331 | BPF_SIZE(insn->code), BPF_READ, | |
2332 | insn->dst_reg); | |
2333 | if (err) | |
2334 | return err; | |
2335 | ||
725f9dcd AS |
2336 | if (BPF_SIZE(insn->code) != BPF_W) { |
2337 | insn_idx++; | |
2338 | continue; | |
2339 | } | |
9bac3d6d | 2340 | |
725f9dcd | 2341 | if (insn->imm == 0) { |
9bac3d6d AS |
2342 | /* saw a valid insn |
2343 | * dst_reg = *(u32 *)(src_reg + off) | |
2344 | * use reserved 'imm' field to mark this insn | |
2345 | */ | |
2346 | insn->imm = src_reg_type; | |
2347 | ||
2348 | } else if (src_reg_type != insn->imm && | |
2349 | (src_reg_type == PTR_TO_CTX || | |
2350 | insn->imm == PTR_TO_CTX)) { | |
2351 | /* ABuser program is trying to use the same insn | |
2352 | * dst_reg = *(u32*) (src_reg + off) | |
2353 | * with different pointer types: | |
2354 | * src_reg == ctx in one branch and | |
2355 | * src_reg == stack|map in some other branch. | |
2356 | * Reject it. | |
2357 | */ | |
2358 | verbose("same insn cannot be used with different pointers\n"); | |
2359 | return -EINVAL; | |
2360 | } | |
2361 | ||
17a52670 | 2362 | } else if (class == BPF_STX) { |
d691f9e8 AS |
2363 | enum bpf_reg_type dst_reg_type; |
2364 | ||
17a52670 AS |
2365 | if (BPF_MODE(insn->code) == BPF_XADD) { |
2366 | err = check_xadd(env, insn); | |
2367 | if (err) | |
2368 | return err; | |
2369 | insn_idx++; | |
2370 | continue; | |
2371 | } | |
2372 | ||
17a52670 AS |
2373 | /* check src1 operand */ |
2374 | err = check_reg_arg(regs, insn->src_reg, SRC_OP); | |
2375 | if (err) | |
2376 | return err; | |
2377 | /* check src2 operand */ | |
2378 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2379 | if (err) | |
2380 | return err; | |
2381 | ||
d691f9e8 AS |
2382 | dst_reg_type = regs[insn->dst_reg].type; |
2383 | ||
17a52670 AS |
2384 | /* check that memory (dst_reg + off) is writeable */ |
2385 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2386 | BPF_SIZE(insn->code), BPF_WRITE, | |
2387 | insn->src_reg); | |
2388 | if (err) | |
2389 | return err; | |
2390 | ||
d691f9e8 AS |
2391 | if (insn->imm == 0) { |
2392 | insn->imm = dst_reg_type; | |
2393 | } else if (dst_reg_type != insn->imm && | |
2394 | (dst_reg_type == PTR_TO_CTX || | |
2395 | insn->imm == PTR_TO_CTX)) { | |
2396 | verbose("same insn cannot be used with different pointers\n"); | |
2397 | return -EINVAL; | |
2398 | } | |
2399 | ||
17a52670 AS |
2400 | } else if (class == BPF_ST) { |
2401 | if (BPF_MODE(insn->code) != BPF_MEM || | |
2402 | insn->src_reg != BPF_REG_0) { | |
2403 | verbose("BPF_ST uses reserved fields\n"); | |
2404 | return -EINVAL; | |
2405 | } | |
2406 | /* check src operand */ | |
2407 | err = check_reg_arg(regs, insn->dst_reg, SRC_OP); | |
2408 | if (err) | |
2409 | return err; | |
2410 | ||
2411 | /* check that memory (dst_reg + off) is writeable */ | |
2412 | err = check_mem_access(env, insn->dst_reg, insn->off, | |
2413 | BPF_SIZE(insn->code), BPF_WRITE, | |
2414 | -1); | |
2415 | if (err) | |
2416 | return err; | |
2417 | ||
2418 | } else if (class == BPF_JMP) { | |
2419 | u8 opcode = BPF_OP(insn->code); | |
2420 | ||
2421 | if (opcode == BPF_CALL) { | |
2422 | if (BPF_SRC(insn->code) != BPF_K || | |
2423 | insn->off != 0 || | |
2424 | insn->src_reg != BPF_REG_0 || | |
2425 | insn->dst_reg != BPF_REG_0) { | |
2426 | verbose("BPF_CALL uses reserved fields\n"); | |
2427 | return -EINVAL; | |
2428 | } | |
2429 | ||
2430 | err = check_call(env, insn->imm); | |
2431 | if (err) | |
2432 | return err; | |
2433 | ||
2434 | } else if (opcode == BPF_JA) { | |
2435 | if (BPF_SRC(insn->code) != BPF_K || | |
2436 | insn->imm != 0 || | |
2437 | insn->src_reg != BPF_REG_0 || | |
2438 | insn->dst_reg != BPF_REG_0) { | |
2439 | verbose("BPF_JA uses reserved fields\n"); | |
2440 | return -EINVAL; | |
2441 | } | |
2442 | ||
2443 | insn_idx += insn->off + 1; | |
2444 | continue; | |
2445 | ||
2446 | } else if (opcode == BPF_EXIT) { | |
2447 | if (BPF_SRC(insn->code) != BPF_K || | |
2448 | insn->imm != 0 || | |
2449 | insn->src_reg != BPF_REG_0 || | |
2450 | insn->dst_reg != BPF_REG_0) { | |
2451 | verbose("BPF_EXIT uses reserved fields\n"); | |
2452 | return -EINVAL; | |
2453 | } | |
2454 | ||
2455 | /* eBPF calling convetion is such that R0 is used | |
2456 | * to return the value from eBPF program. | |
2457 | * Make sure that it's readable at this time | |
2458 | * of bpf_exit, which means that program wrote | |
2459 | * something into it earlier | |
2460 | */ | |
2461 | err = check_reg_arg(regs, BPF_REG_0, SRC_OP); | |
2462 | if (err) | |
2463 | return err; | |
2464 | ||
1be7f75d AS |
2465 | if (is_pointer_value(env, BPF_REG_0)) { |
2466 | verbose("R0 leaks addr as return value\n"); | |
2467 | return -EACCES; | |
2468 | } | |
2469 | ||
f1bca824 | 2470 | process_bpf_exit: |
17a52670 AS |
2471 | insn_idx = pop_stack(env, &prev_insn_idx); |
2472 | if (insn_idx < 0) { | |
2473 | break; | |
2474 | } else { | |
2475 | do_print_state = true; | |
2476 | continue; | |
2477 | } | |
2478 | } else { | |
2479 | err = check_cond_jmp_op(env, insn, &insn_idx); | |
2480 | if (err) | |
2481 | return err; | |
2482 | } | |
2483 | } else if (class == BPF_LD) { | |
2484 | u8 mode = BPF_MODE(insn->code); | |
2485 | ||
2486 | if (mode == BPF_ABS || mode == BPF_IND) { | |
ddd872bc AS |
2487 | err = check_ld_abs(env, insn); |
2488 | if (err) | |
2489 | return err; | |
2490 | ||
17a52670 AS |
2491 | } else if (mode == BPF_IMM) { |
2492 | err = check_ld_imm(env, insn); | |
2493 | if (err) | |
2494 | return err; | |
2495 | ||
2496 | insn_idx++; | |
2497 | } else { | |
2498 | verbose("invalid BPF_LD mode\n"); | |
2499 | return -EINVAL; | |
2500 | } | |
2501 | } else { | |
2502 | verbose("unknown insn class %d\n", class); | |
2503 | return -EINVAL; | |
2504 | } | |
2505 | ||
2506 | insn_idx++; | |
2507 | } | |
2508 | ||
1a0dc1ac | 2509 | verbose("processed %d insns\n", insn_processed); |
17a52670 AS |
2510 | return 0; |
2511 | } | |
2512 | ||
0246e64d AS |
2513 | /* look for pseudo eBPF instructions that access map FDs and |
2514 | * replace them with actual map pointers | |
2515 | */ | |
2516 | static int replace_map_fd_with_map_ptr(struct verifier_env *env) | |
2517 | { | |
2518 | struct bpf_insn *insn = env->prog->insnsi; | |
2519 | int insn_cnt = env->prog->len; | |
2520 | int i, j; | |
2521 | ||
2522 | for (i = 0; i < insn_cnt; i++, insn++) { | |
9bac3d6d | 2523 | if (BPF_CLASS(insn->code) == BPF_LDX && |
d691f9e8 | 2524 | (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { |
9bac3d6d AS |
2525 | verbose("BPF_LDX uses reserved fields\n"); |
2526 | return -EINVAL; | |
2527 | } | |
2528 | ||
d691f9e8 AS |
2529 | if (BPF_CLASS(insn->code) == BPF_STX && |
2530 | ((BPF_MODE(insn->code) != BPF_MEM && | |
2531 | BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { | |
2532 | verbose("BPF_STX uses reserved fields\n"); | |
2533 | return -EINVAL; | |
2534 | } | |
2535 | ||
0246e64d AS |
2536 | if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { |
2537 | struct bpf_map *map; | |
2538 | struct fd f; | |
2539 | ||
2540 | if (i == insn_cnt - 1 || insn[1].code != 0 || | |
2541 | insn[1].dst_reg != 0 || insn[1].src_reg != 0 || | |
2542 | insn[1].off != 0) { | |
2543 | verbose("invalid bpf_ld_imm64 insn\n"); | |
2544 | return -EINVAL; | |
2545 | } | |
2546 | ||
2547 | if (insn->src_reg == 0) | |
2548 | /* valid generic load 64-bit imm */ | |
2549 | goto next_insn; | |
2550 | ||
2551 | if (insn->src_reg != BPF_PSEUDO_MAP_FD) { | |
2552 | verbose("unrecognized bpf_ld_imm64 insn\n"); | |
2553 | return -EINVAL; | |
2554 | } | |
2555 | ||
2556 | f = fdget(insn->imm); | |
c2101297 | 2557 | map = __bpf_map_get(f); |
0246e64d AS |
2558 | if (IS_ERR(map)) { |
2559 | verbose("fd %d is not pointing to valid bpf_map\n", | |
2560 | insn->imm); | |
0246e64d AS |
2561 | return PTR_ERR(map); |
2562 | } | |
2563 | ||
2564 | /* store map pointer inside BPF_LD_IMM64 instruction */ | |
2565 | insn[0].imm = (u32) (unsigned long) map; | |
2566 | insn[1].imm = ((u64) (unsigned long) map) >> 32; | |
2567 | ||
2568 | /* check whether we recorded this map already */ | |
2569 | for (j = 0; j < env->used_map_cnt; j++) | |
2570 | if (env->used_maps[j] == map) { | |
2571 | fdput(f); | |
2572 | goto next_insn; | |
2573 | } | |
2574 | ||
2575 | if (env->used_map_cnt >= MAX_USED_MAPS) { | |
2576 | fdput(f); | |
2577 | return -E2BIG; | |
2578 | } | |
2579 | ||
0246e64d AS |
2580 | /* hold the map. If the program is rejected by verifier, |
2581 | * the map will be released by release_maps() or it | |
2582 | * will be used by the valid program until it's unloaded | |
2583 | * and all maps are released in free_bpf_prog_info() | |
2584 | */ | |
92117d84 AS |
2585 | map = bpf_map_inc(map, false); |
2586 | if (IS_ERR(map)) { | |
2587 | fdput(f); | |
2588 | return PTR_ERR(map); | |
2589 | } | |
2590 | env->used_maps[env->used_map_cnt++] = map; | |
2591 | ||
0246e64d AS |
2592 | fdput(f); |
2593 | next_insn: | |
2594 | insn++; | |
2595 | i++; | |
2596 | } | |
2597 | } | |
2598 | ||
2599 | /* now all pseudo BPF_LD_IMM64 instructions load valid | |
2600 | * 'struct bpf_map *' into a register instead of user map_fd. | |
2601 | * These pointers will be used later by verifier to validate map access. | |
2602 | */ | |
2603 | return 0; | |
2604 | } | |
2605 | ||
2606 | /* drop refcnt of maps used by the rejected program */ | |
2607 | static void release_maps(struct verifier_env *env) | |
2608 | { | |
2609 | int i; | |
2610 | ||
2611 | for (i = 0; i < env->used_map_cnt; i++) | |
2612 | bpf_map_put(env->used_maps[i]); | |
2613 | } | |
2614 | ||
2615 | /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ | |
2616 | static void convert_pseudo_ld_imm64(struct verifier_env *env) | |
2617 | { | |
2618 | struct bpf_insn *insn = env->prog->insnsi; | |
2619 | int insn_cnt = env->prog->len; | |
2620 | int i; | |
2621 | ||
2622 | for (i = 0; i < insn_cnt; i++, insn++) | |
2623 | if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) | |
2624 | insn->src_reg = 0; | |
2625 | } | |
2626 | ||
9bac3d6d AS |
2627 | /* convert load instructions that access fields of 'struct __sk_buff' |
2628 | * into sequence of instructions that access fields of 'struct sk_buff' | |
2629 | */ | |
2630 | static int convert_ctx_accesses(struct verifier_env *env) | |
2631 | { | |
2632 | struct bpf_insn *insn = env->prog->insnsi; | |
2633 | int insn_cnt = env->prog->len; | |
2634 | struct bpf_insn insn_buf[16]; | |
2635 | struct bpf_prog *new_prog; | |
d691f9e8 | 2636 | enum bpf_access_type type; |
c237ee5e | 2637 | int i; |
9bac3d6d AS |
2638 | |
2639 | if (!env->prog->aux->ops->convert_ctx_access) | |
2640 | return 0; | |
2641 | ||
2642 | for (i = 0; i < insn_cnt; i++, insn++) { | |
c237ee5e DB |
2643 | u32 insn_delta, cnt; |
2644 | ||
d691f9e8 AS |
2645 | if (insn->code == (BPF_LDX | BPF_MEM | BPF_W)) |
2646 | type = BPF_READ; | |
2647 | else if (insn->code == (BPF_STX | BPF_MEM | BPF_W)) | |
2648 | type = BPF_WRITE; | |
2649 | else | |
9bac3d6d AS |
2650 | continue; |
2651 | ||
2652 | if (insn->imm != PTR_TO_CTX) { | |
2653 | /* clear internal mark */ | |
2654 | insn->imm = 0; | |
2655 | continue; | |
2656 | } | |
2657 | ||
2658 | cnt = env->prog->aux->ops-> | |
d691f9e8 | 2659 | convert_ctx_access(type, insn->dst_reg, insn->src_reg, |
ff936a04 | 2660 | insn->off, insn_buf, env->prog); |
9bac3d6d AS |
2661 | if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { |
2662 | verbose("bpf verifier is misconfigured\n"); | |
2663 | return -EINVAL; | |
2664 | } | |
2665 | ||
c237ee5e | 2666 | new_prog = bpf_patch_insn_single(env->prog, i, insn_buf, cnt); |
9bac3d6d AS |
2667 | if (!new_prog) |
2668 | return -ENOMEM; | |
2669 | ||
c237ee5e | 2670 | insn_delta = cnt - 1; |
9bac3d6d AS |
2671 | |
2672 | /* keep walking new program and skip insns we just inserted */ | |
2673 | env->prog = new_prog; | |
c237ee5e DB |
2674 | insn = new_prog->insnsi + i + insn_delta; |
2675 | ||
2676 | insn_cnt += insn_delta; | |
2677 | i += insn_delta; | |
9bac3d6d AS |
2678 | } |
2679 | ||
2680 | return 0; | |
2681 | } | |
2682 | ||
f1bca824 AS |
2683 | static void free_states(struct verifier_env *env) |
2684 | { | |
2685 | struct verifier_state_list *sl, *sln; | |
2686 | int i; | |
2687 | ||
2688 | if (!env->explored_states) | |
2689 | return; | |
2690 | ||
2691 | for (i = 0; i < env->prog->len; i++) { | |
2692 | sl = env->explored_states[i]; | |
2693 | ||
2694 | if (sl) | |
2695 | while (sl != STATE_LIST_MARK) { | |
2696 | sln = sl->next; | |
2697 | kfree(sl); | |
2698 | sl = sln; | |
2699 | } | |
2700 | } | |
2701 | ||
2702 | kfree(env->explored_states); | |
2703 | } | |
2704 | ||
9bac3d6d | 2705 | int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) |
51580e79 | 2706 | { |
cbd35700 AS |
2707 | char __user *log_ubuf = NULL; |
2708 | struct verifier_env *env; | |
51580e79 AS |
2709 | int ret = -EINVAL; |
2710 | ||
9bac3d6d | 2711 | if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS) |
cbd35700 AS |
2712 | return -E2BIG; |
2713 | ||
2714 | /* 'struct verifier_env' can be global, but since it's not small, | |
2715 | * allocate/free it every time bpf_check() is called | |
2716 | */ | |
2717 | env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL); | |
2718 | if (!env) | |
2719 | return -ENOMEM; | |
2720 | ||
9bac3d6d | 2721 | env->prog = *prog; |
0246e64d | 2722 | |
cbd35700 AS |
2723 | /* grab the mutex to protect few globals used by verifier */ |
2724 | mutex_lock(&bpf_verifier_lock); | |
2725 | ||
2726 | if (attr->log_level || attr->log_buf || attr->log_size) { | |
2727 | /* user requested verbose verifier output | |
2728 | * and supplied buffer to store the verification trace | |
2729 | */ | |
2730 | log_level = attr->log_level; | |
2731 | log_ubuf = (char __user *) (unsigned long) attr->log_buf; | |
2732 | log_size = attr->log_size; | |
2733 | log_len = 0; | |
2734 | ||
2735 | ret = -EINVAL; | |
2736 | /* log_* values have to be sane */ | |
2737 | if (log_size < 128 || log_size > UINT_MAX >> 8 || | |
2738 | log_level == 0 || log_ubuf == NULL) | |
2739 | goto free_env; | |
2740 | ||
2741 | ret = -ENOMEM; | |
2742 | log_buf = vmalloc(log_size); | |
2743 | if (!log_buf) | |
2744 | goto free_env; | |
2745 | } else { | |
2746 | log_level = 0; | |
2747 | } | |
2748 | ||
0246e64d AS |
2749 | ret = replace_map_fd_with_map_ptr(env); |
2750 | if (ret < 0) | |
2751 | goto skip_full_check; | |
2752 | ||
9bac3d6d | 2753 | env->explored_states = kcalloc(env->prog->len, |
f1bca824 AS |
2754 | sizeof(struct verifier_state_list *), |
2755 | GFP_USER); | |
2756 | ret = -ENOMEM; | |
2757 | if (!env->explored_states) | |
2758 | goto skip_full_check; | |
2759 | ||
475fb78f AS |
2760 | ret = check_cfg(env); |
2761 | if (ret < 0) | |
2762 | goto skip_full_check; | |
2763 | ||
1be7f75d AS |
2764 | env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); |
2765 | ||
17a52670 | 2766 | ret = do_check(env); |
cbd35700 | 2767 | |
0246e64d | 2768 | skip_full_check: |
17a52670 | 2769 | while (pop_stack(env, NULL) >= 0); |
f1bca824 | 2770 | free_states(env); |
0246e64d | 2771 | |
9bac3d6d AS |
2772 | if (ret == 0) |
2773 | /* program is valid, convert *(u32*)(ctx + off) accesses */ | |
2774 | ret = convert_ctx_accesses(env); | |
2775 | ||
cbd35700 AS |
2776 | if (log_level && log_len >= log_size - 1) { |
2777 | BUG_ON(log_len >= log_size); | |
2778 | /* verifier log exceeded user supplied buffer */ | |
2779 | ret = -ENOSPC; | |
2780 | /* fall through to return what was recorded */ | |
2781 | } | |
2782 | ||
2783 | /* copy verifier log back to user space including trailing zero */ | |
2784 | if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { | |
2785 | ret = -EFAULT; | |
2786 | goto free_log_buf; | |
2787 | } | |
2788 | ||
0246e64d AS |
2789 | if (ret == 0 && env->used_map_cnt) { |
2790 | /* if program passed verifier, update used_maps in bpf_prog_info */ | |
9bac3d6d AS |
2791 | env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, |
2792 | sizeof(env->used_maps[0]), | |
2793 | GFP_KERNEL); | |
0246e64d | 2794 | |
9bac3d6d | 2795 | if (!env->prog->aux->used_maps) { |
0246e64d AS |
2796 | ret = -ENOMEM; |
2797 | goto free_log_buf; | |
2798 | } | |
2799 | ||
9bac3d6d | 2800 | memcpy(env->prog->aux->used_maps, env->used_maps, |
0246e64d | 2801 | sizeof(env->used_maps[0]) * env->used_map_cnt); |
9bac3d6d | 2802 | env->prog->aux->used_map_cnt = env->used_map_cnt; |
0246e64d AS |
2803 | |
2804 | /* program is valid. Convert pseudo bpf_ld_imm64 into generic | |
2805 | * bpf_ld_imm64 instructions | |
2806 | */ | |
2807 | convert_pseudo_ld_imm64(env); | |
2808 | } | |
cbd35700 AS |
2809 | |
2810 | free_log_buf: | |
2811 | if (log_level) | |
2812 | vfree(log_buf); | |
2813 | free_env: | |
9bac3d6d | 2814 | if (!env->prog->aux->used_maps) |
0246e64d AS |
2815 | /* if we didn't copy map pointers into bpf_prog_info, release |
2816 | * them now. Otherwise free_bpf_prog_info() will release them. | |
2817 | */ | |
2818 | release_maps(env); | |
9bac3d6d | 2819 | *prog = env->prog; |
cbd35700 AS |
2820 | kfree(env); |
2821 | mutex_unlock(&bpf_verifier_lock); | |
51580e79 AS |
2822 | return ret; |
2823 | } |