1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 2 * Copyright (c) 2016 Facebook 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of version 2 of the GNU General Public 6 * License as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, but 9 * WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 */ 13 #include <linux/kernel.h> 14 #include <linux/types.h> 15 #include <linux/slab.h> 16 #include <linux/bpf.h> 17 #include <linux/bpf_verifier.h> 18 #include <linux/filter.h> 19 #include <net/netlink.h> 20 #include <linux/file.h> 21 #include <linux/vmalloc.h> 22 #include <linux/stringify.h> 23 24 /* bpf_check() is a static code analyzer that walks eBPF program 25 * instruction by instruction and updates register/stack state. 26 * All paths of conditional branches are analyzed until 'bpf_exit' insn. 27 * 28 * The first pass is depth-first-search to check that the program is a DAG. 29 * It rejects the following programs: 30 * - larger than BPF_MAXINSNS insns 31 * - if loop is present (detected via back-edge) 32 * - unreachable insns exist (shouldn't be a forest. program = one function) 33 * - out of bounds or malformed jumps 34 * The second pass is all possible path descent from the 1st insn. 35 * Since it's analyzing all pathes through the program, the length of the 36 * analysis is limited to 64k insn, which may be hit even if total number of 37 * insn is less then 4K, but there are too many branches that change stack/regs. 38 * Number of 'branches to be analyzed' is limited to 1k 39 * 40 * On entry to each instruction, each register has a type, and the instruction 41 * changes the types of the registers depending on instruction semantics. 42 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is 43 * copied to R1. 44 * 45 * All registers are 64-bit. 46 * R0 - return register 47 * R1-R5 argument passing registers 48 * R6-R9 callee saved registers 49 * R10 - frame pointer read-only 50 * 51 * At the start of BPF program the register R1 contains a pointer to bpf_context 52 * and has type PTR_TO_CTX. 53 * 54 * Verifier tracks arithmetic operations on pointers in case: 55 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), 56 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), 57 * 1st insn copies R10 (which has FRAME_PTR) type into R1 58 * and 2nd arithmetic instruction is pattern matched to recognize 59 * that it wants to construct a pointer to some element within stack. 60 * So after 2nd insn, the register R1 has type PTR_TO_STACK 61 * (and -20 constant is saved for further stack bounds checking). 62 * Meaning that this reg is a pointer to stack plus known immediate constant. 63 * 64 * Most of the time the registers have UNKNOWN_VALUE type, which 65 * means the register has some value, but it's not a valid pointer. 66 * (like pointer plus pointer becomes UNKNOWN_VALUE type) 67 * 68 * When verifier sees load or store instructions the type of base register 69 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer 70 * types recognized by check_mem_access() function. 71 * 72 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' 73 * and the range of [ptr, ptr + map's value_size) is accessible. 74 * 75 * registers used to pass values to function calls are checked against 76 * function argument constraints. 77 * 78 * ARG_PTR_TO_MAP_KEY is one of such argument constraints. 79 * It means that the register type passed to this function must be 80 * PTR_TO_STACK and it will be used inside the function as 81 * 'pointer to map element key' 82 * 83 * For example the argument constraints for bpf_map_lookup_elem(): 84 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 85 * .arg1_type = ARG_CONST_MAP_PTR, 86 * .arg2_type = ARG_PTR_TO_MAP_KEY, 87 * 88 * ret_type says that this function returns 'pointer to map elem value or null' 89 * function expects 1st argument to be a const pointer to 'struct bpf_map' and 90 * 2nd argument should be a pointer to stack, which will be used inside 91 * the helper function as a pointer to map element key. 92 * 93 * On the kernel side the helper function looks like: 94 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 95 * { 96 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 97 * void *key = (void *) (unsigned long) r2; 98 * void *value; 99 * 100 * here kernel can access 'key' and 'map' pointers safely, knowing that 101 * [key, key + map->key_size) bytes are valid and were initialized on 102 * the stack of eBPF program. 103 * } 104 * 105 * Corresponding eBPF program may look like: 106 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR 107 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK 108 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP 109 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), 110 * here verifier looks at prototype of map_lookup_elem() and sees: 111 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, 112 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes 113 * 114 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, 115 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits 116 * and were initialized prior to this call. 117 * If it's ok, then verifier allows this BPF_CALL insn and looks at 118 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets 119 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function 120 * returns ether pointer to map value or NULL. 121 * 122 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' 123 * insn, the register holding that pointer in the true branch changes state to 124 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false 125 * branch. See check_cond_jmp_op(). 126 * 127 * After the call R0 is set to return type of the function and registers R1-R5 128 * are set to NOT_INIT to indicate that they are no longer readable. 129 */ 130 131 /* verifier_state + insn_idx are pushed to stack when branch is encountered */ 132 struct bpf_verifier_stack_elem { 133 /* verifer state is 'st' 134 * before processing instruction 'insn_idx' 135 * and after processing instruction 'prev_insn_idx' 136 */ 137 struct bpf_verifier_state st; 138 int insn_idx; 139 int prev_insn_idx; 140 struct bpf_verifier_stack_elem *next; 141 }; 142 143 #define BPF_COMPLEXITY_LIMIT_INSNS 98304 144 #define BPF_COMPLEXITY_LIMIT_STACK 1024 145 146 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) 147 148 struct bpf_call_arg_meta { 149 struct bpf_map *map_ptr; 150 bool raw_mode; 151 bool pkt_access; 152 int regno; 153 int access_size; 154 }; 155 156 /* verbose verifier prints what it's seeing 157 * bpf_check() is called under lock, so no race to access these global vars 158 */ 159 static u32 log_level, log_size, log_len; 160 static char *log_buf; 161 162 static DEFINE_MUTEX(bpf_verifier_lock); 163 164 /* log_level controls verbosity level of eBPF verifier. 165 * verbose() is used to dump the verification trace to the log, so the user 166 * can figure out what's wrong with the program 167 */ 168 static __printf(1, 2) void verbose(const char *fmt, ...) 169 { 170 va_list args; 171 172 if (log_level == 0 || log_len >= log_size - 1) 173 return; 174 175 va_start(args, fmt); 176 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); 177 va_end(args); 178 } 179 180 /* string representation of 'enum bpf_reg_type' */ 181 static const char * const reg_type_str[] = { 182 [NOT_INIT] = "?", 183 [UNKNOWN_VALUE] = "inv", 184 [PTR_TO_CTX] = "ctx", 185 [CONST_PTR_TO_MAP] = "map_ptr", 186 [PTR_TO_MAP_VALUE] = "map_value", 187 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", 188 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj", 189 [FRAME_PTR] = "fp", 190 [PTR_TO_STACK] = "fp", 191 [CONST_IMM] = "imm", 192 [PTR_TO_PACKET] = "pkt", 193 [PTR_TO_PACKET_END] = "pkt_end", 194 }; 195 196 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x) 197 static const char * const func_id_str[] = { 198 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN) 199 }; 200 #undef __BPF_FUNC_STR_FN 201 202 static const char *func_id_name(int id) 203 { 204 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID); 205 206 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id]) 207 return func_id_str[id]; 208 else 209 return "unknown"; 210 } 211 212 static void print_verifier_state(struct bpf_verifier_state *state) 213 { 214 struct bpf_reg_state *reg; 215 enum bpf_reg_type t; 216 int i; 217 218 for (i = 0; i < MAX_BPF_REG; i++) { 219 reg = &state->regs[i]; 220 t = reg->type; 221 if (t == NOT_INIT) 222 continue; 223 verbose(" R%d=%s", i, reg_type_str[t]); 224 if (t == CONST_IMM || t == PTR_TO_STACK) 225 verbose("%lld", reg->imm); 226 else if (t == PTR_TO_PACKET) 227 verbose("(id=%d,off=%d,r=%d)", 228 reg->id, reg->off, reg->range); 229 else if (t == UNKNOWN_VALUE && reg->imm) 230 verbose("%lld", reg->imm); 231 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || 232 t == PTR_TO_MAP_VALUE_OR_NULL || 233 t == PTR_TO_MAP_VALUE_ADJ) 234 verbose("(ks=%d,vs=%d,id=%u)", 235 reg->map_ptr->key_size, 236 reg->map_ptr->value_size, 237 reg->id); 238 if (reg->min_value != BPF_REGISTER_MIN_RANGE) 239 verbose(",min_value=%lld", 240 (long long)reg->min_value); 241 if (reg->max_value != BPF_REGISTER_MAX_RANGE) 242 verbose(",max_value=%llu", 243 (unsigned long long)reg->max_value); 244 if (reg->min_align) 245 verbose(",min_align=%u", reg->min_align); 246 if (reg->aux_off) 247 verbose(",aux_off=%u", reg->aux_off); 248 if (reg->aux_off_align) 249 verbose(",aux_off_align=%u", reg->aux_off_align); 250 } 251 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 252 if (state->stack_slot_type[i] == STACK_SPILL) 253 verbose(" fp%d=%s", -MAX_BPF_STACK + i, 254 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); 255 } 256 verbose("\n"); 257 } 258 259 static const char *const bpf_class_string[] = { 260 [BPF_LD] = "ld", 261 [BPF_LDX] = "ldx", 262 [BPF_ST] = "st", 263 [BPF_STX] = "stx", 264 [BPF_ALU] = "alu", 265 [BPF_JMP] = "jmp", 266 [BPF_RET] = "BUG", 267 [BPF_ALU64] = "alu64", 268 }; 269 270 static const char *const bpf_alu_string[16] = { 271 [BPF_ADD >> 4] = "+=", 272 [BPF_SUB >> 4] = "-=", 273 [BPF_MUL >> 4] = "*=", 274 [BPF_DIV >> 4] = "/=", 275 [BPF_OR >> 4] = "|=", 276 [BPF_AND >> 4] = "&=", 277 [BPF_LSH >> 4] = "<<=", 278 [BPF_RSH >> 4] = ">>=", 279 [BPF_NEG >> 4] = "neg", 280 [BPF_MOD >> 4] = "%=", 281 [BPF_XOR >> 4] = "^=", 282 [BPF_MOV >> 4] = "=", 283 [BPF_ARSH >> 4] = "s>>=", 284 [BPF_END >> 4] = "endian", 285 }; 286 287 static const char *const bpf_ldst_string[] = { 288 [BPF_W >> 3] = "u32", 289 [BPF_H >> 3] = "u16", 290 [BPF_B >> 3] = "u8", 291 [BPF_DW >> 3] = "u64", 292 }; 293 294 static const char *const bpf_jmp_string[16] = { 295 [BPF_JA >> 4] = "jmp", 296 [BPF_JEQ >> 4] = "==", 297 [BPF_JGT >> 4] = ">", 298 [BPF_JGE >> 4] = ">=", 299 [BPF_JSET >> 4] = "&", 300 [BPF_JNE >> 4] = "!=", 301 [BPF_JSGT >> 4] = "s>", 302 [BPF_JSGE >> 4] = "s>=", 303 [BPF_CALL >> 4] = "call", 304 [BPF_EXIT >> 4] = "exit", 305 }; 306 307 static void print_bpf_insn(const struct bpf_verifier_env *env, 308 const struct bpf_insn *insn) 309 { 310 u8 class = BPF_CLASS(insn->code); 311 312 if (class == BPF_ALU || class == BPF_ALU64) { 313 if (BPF_SRC(insn->code) == BPF_X) 314 verbose("(%02x) %sr%d %s %sr%d\n", 315 insn->code, class == BPF_ALU ? "(u32) " : "", 316 insn->dst_reg, 317 bpf_alu_string[BPF_OP(insn->code) >> 4], 318 class == BPF_ALU ? "(u32) " : "", 319 insn->src_reg); 320 else 321 verbose("(%02x) %sr%d %s %s%d\n", 322 insn->code, class == BPF_ALU ? "(u32) " : "", 323 insn->dst_reg, 324 bpf_alu_string[BPF_OP(insn->code) >> 4], 325 class == BPF_ALU ? "(u32) " : "", 326 insn->imm); 327 } else if (class == BPF_STX) { 328 if (BPF_MODE(insn->code) == BPF_MEM) 329 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", 330 insn->code, 331 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 332 insn->dst_reg, 333 insn->off, insn->src_reg); 334 else if (BPF_MODE(insn->code) == BPF_XADD) 335 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", 336 insn->code, 337 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 338 insn->dst_reg, insn->off, 339 insn->src_reg); 340 else 341 verbose("BUG_%02x\n", insn->code); 342 } else if (class == BPF_ST) { 343 if (BPF_MODE(insn->code) != BPF_MEM) { 344 verbose("BUG_st_%02x\n", insn->code); 345 return; 346 } 347 verbose("(%02x) *(%s *)(r%d %+d) = %d\n", 348 insn->code, 349 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 350 insn->dst_reg, 351 insn->off, insn->imm); 352 } else if (class == BPF_LDX) { 353 if (BPF_MODE(insn->code) != BPF_MEM) { 354 verbose("BUG_ldx_%02x\n", insn->code); 355 return; 356 } 357 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", 358 insn->code, insn->dst_reg, 359 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 360 insn->src_reg, insn->off); 361 } else if (class == BPF_LD) { 362 if (BPF_MODE(insn->code) == BPF_ABS) { 363 verbose("(%02x) r0 = *(%s *)skb[%d]\n", 364 insn->code, 365 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 366 insn->imm); 367 } else if (BPF_MODE(insn->code) == BPF_IND) { 368 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", 369 insn->code, 370 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 371 insn->src_reg, insn->imm); 372 } else if (BPF_MODE(insn->code) == BPF_IMM && 373 BPF_SIZE(insn->code) == BPF_DW) { 374 /* At this point, we already made sure that the second 375 * part of the ldimm64 insn is accessible. 376 */ 377 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; 378 bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD; 379 380 if (map_ptr && !env->allow_ptr_leaks) 381 imm = 0; 382 383 verbose("(%02x) r%d = 0x%llx\n", insn->code, 384 insn->dst_reg, (unsigned long long)imm); 385 } else { 386 verbose("BUG_ld_%02x\n", insn->code); 387 return; 388 } 389 } else if (class == BPF_JMP) { 390 u8 opcode = BPF_OP(insn->code); 391 392 if (opcode == BPF_CALL) { 393 verbose("(%02x) call %s#%d\n", insn->code, 394 func_id_name(insn->imm), insn->imm); 395 } else if (insn->code == (BPF_JMP | BPF_JA)) { 396 verbose("(%02x) goto pc%+d\n", 397 insn->code, insn->off); 398 } else if (insn->code == (BPF_JMP | BPF_EXIT)) { 399 verbose("(%02x) exit\n", insn->code); 400 } else if (BPF_SRC(insn->code) == BPF_X) { 401 verbose("(%02x) if r%d %s r%d goto pc%+d\n", 402 insn->code, insn->dst_reg, 403 bpf_jmp_string[BPF_OP(insn->code) >> 4], 404 insn->src_reg, insn->off); 405 } else { 406 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", 407 insn->code, insn->dst_reg, 408 bpf_jmp_string[BPF_OP(insn->code) >> 4], 409 insn->imm, insn->off); 410 } 411 } else { 412 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); 413 } 414 } 415 416 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) 417 { 418 struct bpf_verifier_stack_elem *elem; 419 int insn_idx; 420 421 if (env->head == NULL) 422 return -1; 423 424 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); 425 insn_idx = env->head->insn_idx; 426 if (prev_insn_idx) 427 *prev_insn_idx = env->head->prev_insn_idx; 428 elem = env->head->next; 429 kfree(env->head); 430 env->head = elem; 431 env->stack_size--; 432 return insn_idx; 433 } 434 435 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, 436 int insn_idx, int prev_insn_idx) 437 { 438 struct bpf_verifier_stack_elem *elem; 439 440 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); 441 if (!elem) 442 goto err; 443 444 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); 445 elem->insn_idx = insn_idx; 446 elem->prev_insn_idx = prev_insn_idx; 447 elem->next = env->head; 448 env->head = elem; 449 env->stack_size++; 450 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { 451 verbose("BPF program is too complex\n"); 452 goto err; 453 } 454 return &elem->st; 455 err: 456 /* pop all elements and return */ 457 while (pop_stack(env, NULL) >= 0); 458 return NULL; 459 } 460 461 #define CALLER_SAVED_REGS 6 462 static const int caller_saved[CALLER_SAVED_REGS] = { 463 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 464 }; 465 466 static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno) 467 { 468 BUG_ON(regno >= MAX_BPF_REG); 469 470 memset(®s[regno], 0, sizeof(regs[regno])); 471 regs[regno].type = NOT_INIT; 472 regs[regno].min_value = BPF_REGISTER_MIN_RANGE; 473 regs[regno].max_value = BPF_REGISTER_MAX_RANGE; 474 } 475 476 static void init_reg_state(struct bpf_reg_state *regs) 477 { 478 int i; 479 480 for (i = 0; i < MAX_BPF_REG; i++) 481 mark_reg_not_init(regs, i); 482 483 /* frame pointer */ 484 regs[BPF_REG_FP].type = FRAME_PTR; 485 486 /* 1st arg to a function */ 487 regs[BPF_REG_1].type = PTR_TO_CTX; 488 } 489 490 static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) 491 { 492 regs[regno].type = UNKNOWN_VALUE; 493 regs[regno].id = 0; 494 regs[regno].imm = 0; 495 } 496 497 static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) 498 { 499 BUG_ON(regno >= MAX_BPF_REG); 500 __mark_reg_unknown_value(regs, regno); 501 } 502 503 static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno) 504 { 505 regs[regno].min_value = BPF_REGISTER_MIN_RANGE; 506 regs[regno].max_value = BPF_REGISTER_MAX_RANGE; 507 regs[regno].min_align = 0; 508 } 509 510 static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs, 511 u32 regno) 512 { 513 mark_reg_unknown_value(regs, regno); 514 reset_reg_range_values(regs, regno); 515 } 516 517 enum reg_arg_type { 518 SRC_OP, /* register is used as source operand */ 519 DST_OP, /* register is used as destination operand */ 520 DST_OP_NO_MARK /* same as above, check only, don't mark */ 521 }; 522 523 static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, 524 enum reg_arg_type t) 525 { 526 if (regno >= MAX_BPF_REG) { 527 verbose("R%d is invalid\n", regno); 528 return -EINVAL; 529 } 530 531 if (t == SRC_OP) { 532 /* check whether register used as source operand can be read */ 533 if (regs[regno].type == NOT_INIT) { 534 verbose("R%d !read_ok\n", regno); 535 return -EACCES; 536 } 537 } else { 538 /* check whether register used as dest operand can be written to */ 539 if (regno == BPF_REG_FP) { 540 verbose("frame pointer is read only\n"); 541 return -EACCES; 542 } 543 if (t == DST_OP) 544 mark_reg_unknown_value(regs, regno); 545 } 546 return 0; 547 } 548 549 static int bpf_size_to_bytes(int bpf_size) 550 { 551 if (bpf_size == BPF_W) 552 return 4; 553 else if (bpf_size == BPF_H) 554 return 2; 555 else if (bpf_size == BPF_B) 556 return 1; 557 else if (bpf_size == BPF_DW) 558 return 8; 559 else 560 return -EINVAL; 561 } 562 563 static bool is_spillable_regtype(enum bpf_reg_type type) 564 { 565 switch (type) { 566 case PTR_TO_MAP_VALUE: 567 case PTR_TO_MAP_VALUE_OR_NULL: 568 case PTR_TO_MAP_VALUE_ADJ: 569 case PTR_TO_STACK: 570 case PTR_TO_CTX: 571 case PTR_TO_PACKET: 572 case PTR_TO_PACKET_END: 573 case FRAME_PTR: 574 case CONST_PTR_TO_MAP: 575 return true; 576 default: 577 return false; 578 } 579 } 580 581 /* check_stack_read/write functions track spill/fill of registers, 582 * stack boundary and alignment are checked in check_mem_access() 583 */ 584 static int check_stack_write(struct bpf_verifier_state *state, int off, 585 int size, int value_regno) 586 { 587 int i; 588 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, 589 * so it's aligned access and [off, off + size) are within stack limits 590 */ 591 592 if (value_regno >= 0 && 593 is_spillable_regtype(state->regs[value_regno].type)) { 594 595 /* register containing pointer is being spilled into stack */ 596 if (size != BPF_REG_SIZE) { 597 verbose("invalid size of register spill\n"); 598 return -EACCES; 599 } 600 601 /* save register state */ 602 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 603 state->regs[value_regno]; 604 605 for (i = 0; i < BPF_REG_SIZE; i++) 606 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; 607 } else { 608 /* regular write of data into stack */ 609 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 610 (struct bpf_reg_state) {}; 611 612 for (i = 0; i < size; i++) 613 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; 614 } 615 return 0; 616 } 617 618 static int check_stack_read(struct bpf_verifier_state *state, int off, int size, 619 int value_regno) 620 { 621 u8 *slot_type; 622 int i; 623 624 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; 625 626 if (slot_type[0] == STACK_SPILL) { 627 if (size != BPF_REG_SIZE) { 628 verbose("invalid size of register spill\n"); 629 return -EACCES; 630 } 631 for (i = 1; i < BPF_REG_SIZE; i++) { 632 if (slot_type[i] != STACK_SPILL) { 633 verbose("corrupted spill memory\n"); 634 return -EACCES; 635 } 636 } 637 638 if (value_regno >= 0) 639 /* restore register state from stack */ 640 state->regs[value_regno] = 641 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; 642 return 0; 643 } else { 644 for (i = 0; i < size; i++) { 645 if (slot_type[i] != STACK_MISC) { 646 verbose("invalid read from stack off %d+%d size %d\n", 647 off, i, size); 648 return -EACCES; 649 } 650 } 651 if (value_regno >= 0) 652 /* have read misc data from the stack */ 653 mark_reg_unknown_value_and_range(state->regs, 654 value_regno); 655 return 0; 656 } 657 } 658 659 /* check read/write into map element returned by bpf_map_lookup_elem() */ 660 static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, 661 int size) 662 { 663 struct bpf_map *map = env->cur_state.regs[regno].map_ptr; 664 665 if (off < 0 || size <= 0 || off + size > map->value_size) { 666 verbose("invalid access to map value, value_size=%d off=%d size=%d\n", 667 map->value_size, off, size); 668 return -EACCES; 669 } 670 return 0; 671 } 672 673 /* check read/write into an adjusted map element */ 674 static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno, 675 int off, int size) 676 { 677 struct bpf_verifier_state *state = &env->cur_state; 678 struct bpf_reg_state *reg = &state->regs[regno]; 679 int err; 680 681 /* We adjusted the register to this map value, so we 682 * need to change off and size to min_value and max_value 683 * respectively to make sure our theoretical access will be 684 * safe. 685 */ 686 if (log_level) 687 print_verifier_state(state); 688 env->varlen_map_value_access = true; 689 /* The minimum value is only important with signed 690 * comparisons where we can't assume the floor of a 691 * value is 0. If we are using signed variables for our 692 * index'es we need to make sure that whatever we use 693 * will have a set floor within our range. 694 */ 695 if (reg->min_value < 0) { 696 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", 697 regno); 698 return -EACCES; 699 } 700 err = check_map_access(env, regno, reg->min_value + off, size); 701 if (err) { 702 verbose("R%d min value is outside of the array range\n", 703 regno); 704 return err; 705 } 706 707 /* If we haven't set a max value then we need to bail 708 * since we can't be sure we won't do bad things. 709 */ 710 if (reg->max_value == BPF_REGISTER_MAX_RANGE) { 711 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", 712 regno); 713 return -EACCES; 714 } 715 return check_map_access(env, regno, reg->max_value + off, size); 716 } 717 718 #define MAX_PACKET_OFF 0xffff 719 720 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, 721 const struct bpf_call_arg_meta *meta, 722 enum bpf_access_type t) 723 { 724 switch (env->prog->type) { 725 case BPF_PROG_TYPE_LWT_IN: 726 case BPF_PROG_TYPE_LWT_OUT: 727 /* dst_input() and dst_output() can't write for now */ 728 if (t == BPF_WRITE) 729 return false; 730 /* fallthrough */ 731 case BPF_PROG_TYPE_SCHED_CLS: 732 case BPF_PROG_TYPE_SCHED_ACT: 733 case BPF_PROG_TYPE_XDP: 734 case BPF_PROG_TYPE_LWT_XMIT: 735 if (meta) 736 return meta->pkt_access; 737 738 env->seen_direct_write = true; 739 return true; 740 default: 741 return false; 742 } 743 } 744 745 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, 746 int size) 747 { 748 struct bpf_reg_state *regs = env->cur_state.regs; 749 struct bpf_reg_state *reg = ®s[regno]; 750 751 off += reg->off; 752 if (off < 0 || size <= 0 || off + size > reg->range) { 753 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", 754 off, size, regno, reg->id, reg->off, reg->range); 755 return -EACCES; 756 } 757 return 0; 758 } 759 760 /* check access to 'struct bpf_context' fields */ 761 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, 762 enum bpf_access_type t, enum bpf_reg_type *reg_type) 763 { 764 int ctx_field_size = 0; 765 766 /* for analyzer ctx accesses are already validated and converted */ 767 if (env->analyzer_ops) 768 return 0; 769 770 if (env->prog->aux->ops->is_valid_access && 771 env->prog->aux->ops->is_valid_access(off, size, t, reg_type, &ctx_field_size)) { 772 /* a non zero ctx_field_size indicates: 773 * . For this field, the prog type specific ctx conversion algorithm 774 * only supports whole field access. 775 * . This ctx access is a candiate for later verifier transformation 776 * to load the whole field and then apply a mask to get correct result. 777 */ 778 if (ctx_field_size) 779 env->insn_aux_data[insn_idx].ctx_field_size = ctx_field_size; 780 781 /* remember the offset of last byte accessed in ctx */ 782 if (env->prog->aux->max_ctx_offset < off + size) 783 env->prog->aux->max_ctx_offset = off + size; 784 return 0; 785 } 786 787 verbose("invalid bpf_context access off=%d size=%d\n", off, size); 788 return -EACCES; 789 } 790 791 static bool is_pointer_value(struct bpf_verifier_env *env, int regno) 792 { 793 if (env->allow_ptr_leaks) 794 return false; 795 796 switch (env->cur_state.regs[regno].type) { 797 case UNKNOWN_VALUE: 798 case CONST_IMM: 799 return false; 800 default: 801 return true; 802 } 803 } 804 805 static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg, 806 int off, int size, bool strict) 807 { 808 int ip_align; 809 int reg_off; 810 811 /* Byte size accesses are always allowed. */ 812 if (!strict || size == 1) 813 return 0; 814 815 reg_off = reg->off; 816 if (reg->id) { 817 if (reg->aux_off_align % size) { 818 verbose("Packet access is only %u byte aligned, %d byte access not allowed\n", 819 reg->aux_off_align, size); 820 return -EACCES; 821 } 822 reg_off += reg->aux_off; 823 } 824 825 /* For platforms that do not have a Kconfig enabling 826 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of 827 * NET_IP_ALIGN is universally set to '2'. And on platforms 828 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get 829 * to this code only in strict mode where we want to emulate 830 * the NET_IP_ALIGN==2 checking. Therefore use an 831 * unconditional IP align value of '2'. 832 */ 833 ip_align = 2; 834 if ((ip_align + reg_off + off) % size != 0) { 835 verbose("misaligned packet access off %d+%d+%d size %d\n", 836 ip_align, reg_off, off, size); 837 return -EACCES; 838 } 839 840 return 0; 841 } 842 843 static int check_val_ptr_alignment(const struct bpf_reg_state *reg, 844 int size, bool strict) 845 { 846 if (strict && size != 1) { 847 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n"); 848 return -EACCES; 849 } 850 851 return 0; 852 } 853 854 static int check_ptr_alignment(struct bpf_verifier_env *env, 855 const struct bpf_reg_state *reg, 856 int off, int size) 857 { 858 bool strict = env->strict_alignment; 859 860 switch (reg->type) { 861 case PTR_TO_PACKET: 862 return check_pkt_ptr_alignment(reg, off, size, strict); 863 case PTR_TO_MAP_VALUE_ADJ: 864 return check_val_ptr_alignment(reg, size, strict); 865 default: 866 if (off % size != 0) { 867 verbose("misaligned access off %d size %d\n", 868 off, size); 869 return -EACCES; 870 } 871 872 return 0; 873 } 874 } 875 876 /* check whether memory at (regno + off) is accessible for t = (read | write) 877 * if t==write, value_regno is a register which value is stored into memory 878 * if t==read, value_regno is a register which will receive the value from memory 879 * if t==write && value_regno==-1, some unknown value is stored into memory 880 * if t==read && value_regno==-1, don't care what we read from memory 881 */ 882 static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, 883 int bpf_size, enum bpf_access_type t, 884 int value_regno) 885 { 886 struct bpf_verifier_state *state = &env->cur_state; 887 struct bpf_reg_state *reg = &state->regs[regno]; 888 int size, err = 0; 889 890 if (reg->type == PTR_TO_STACK) 891 off += reg->imm; 892 893 size = bpf_size_to_bytes(bpf_size); 894 if (size < 0) 895 return size; 896 897 err = check_ptr_alignment(env, reg, off, size); 898 if (err) 899 return err; 900 901 if (reg->type == PTR_TO_MAP_VALUE || 902 reg->type == PTR_TO_MAP_VALUE_ADJ) { 903 if (t == BPF_WRITE && value_regno >= 0 && 904 is_pointer_value(env, value_regno)) { 905 verbose("R%d leaks addr into map\n", value_regno); 906 return -EACCES; 907 } 908 909 if (reg->type == PTR_TO_MAP_VALUE_ADJ) 910 err = check_map_access_adj(env, regno, off, size); 911 else 912 err = check_map_access(env, regno, off, size); 913 if (!err && t == BPF_READ && value_regno >= 0) 914 mark_reg_unknown_value_and_range(state->regs, 915 value_regno); 916 917 } else if (reg->type == PTR_TO_CTX) { 918 enum bpf_reg_type reg_type = UNKNOWN_VALUE; 919 920 if (t == BPF_WRITE && value_regno >= 0 && 921 is_pointer_value(env, value_regno)) { 922 verbose("R%d leaks addr into ctx\n", value_regno); 923 return -EACCES; 924 } 925 err = check_ctx_access(env, insn_idx, off, size, t, ®_type); 926 if (!err && t == BPF_READ && value_regno >= 0) { 927 mark_reg_unknown_value_and_range(state->regs, 928 value_regno); 929 /* note that reg.[id|off|range] == 0 */ 930 state->regs[value_regno].type = reg_type; 931 state->regs[value_regno].aux_off = 0; 932 state->regs[value_regno].aux_off_align = 0; 933 } 934 935 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { 936 if (off >= 0 || off < -MAX_BPF_STACK) { 937 verbose("invalid stack off=%d size=%d\n", off, size); 938 return -EACCES; 939 } 940 941 if (env->prog->aux->stack_depth < -off) 942 env->prog->aux->stack_depth = -off; 943 944 if (t == BPF_WRITE) { 945 if (!env->allow_ptr_leaks && 946 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && 947 size != BPF_REG_SIZE) { 948 verbose("attempt to corrupt spilled pointer on stack\n"); 949 return -EACCES; 950 } 951 err = check_stack_write(state, off, size, value_regno); 952 } else { 953 err = check_stack_read(state, off, size, value_regno); 954 } 955 } else if (state->regs[regno].type == PTR_TO_PACKET) { 956 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { 957 verbose("cannot write into packet\n"); 958 return -EACCES; 959 } 960 if (t == BPF_WRITE && value_regno >= 0 && 961 is_pointer_value(env, value_regno)) { 962 verbose("R%d leaks addr into packet\n", value_regno); 963 return -EACCES; 964 } 965 err = check_packet_access(env, regno, off, size); 966 if (!err && t == BPF_READ && value_regno >= 0) 967 mark_reg_unknown_value_and_range(state->regs, 968 value_regno); 969 } else { 970 verbose("R%d invalid mem access '%s'\n", 971 regno, reg_type_str[reg->type]); 972 return -EACCES; 973 } 974 975 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && 976 state->regs[value_regno].type == UNKNOWN_VALUE) { 977 /* 1 or 2 byte load zero-extends, determine the number of 978 * zero upper bits. Not doing it fo 4 byte load, since 979 * such values cannot be added to ptr_to_packet anyway. 980 */ 981 state->regs[value_regno].imm = 64 - size * 8; 982 } 983 return err; 984 } 985 986 static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) 987 { 988 struct bpf_reg_state *regs = env->cur_state.regs; 989 int err; 990 991 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || 992 insn->imm != 0) { 993 verbose("BPF_XADD uses reserved fields\n"); 994 return -EINVAL; 995 } 996 997 /* check src1 operand */ 998 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 999 if (err) 1000 return err; 1001 1002 /* check src2 operand */ 1003 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1004 if (err) 1005 return err; 1006 1007 /* check whether atomic_add can read the memory */ 1008 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 1009 BPF_SIZE(insn->code), BPF_READ, -1); 1010 if (err) 1011 return err; 1012 1013 /* check whether atomic_add can write into the same memory */ 1014 return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 1015 BPF_SIZE(insn->code), BPF_WRITE, -1); 1016 } 1017 1018 /* when register 'regno' is passed into function that will read 'access_size' 1019 * bytes from that pointer, make sure that it's within stack boundary 1020 * and all elements of stack are initialized 1021 */ 1022 static int check_stack_boundary(struct bpf_verifier_env *env, int regno, 1023 int access_size, bool zero_size_allowed, 1024 struct bpf_call_arg_meta *meta) 1025 { 1026 struct bpf_verifier_state *state = &env->cur_state; 1027 struct bpf_reg_state *regs = state->regs; 1028 int off, i; 1029 1030 if (regs[regno].type != PTR_TO_STACK) { 1031 if (zero_size_allowed && access_size == 0 && 1032 regs[regno].type == CONST_IMM && 1033 regs[regno].imm == 0) 1034 return 0; 1035 1036 verbose("R%d type=%s expected=%s\n", regno, 1037 reg_type_str[regs[regno].type], 1038 reg_type_str[PTR_TO_STACK]); 1039 return -EACCES; 1040 } 1041 1042 off = regs[regno].imm; 1043 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || 1044 access_size <= 0) { 1045 verbose("invalid stack type R%d off=%d access_size=%d\n", 1046 regno, off, access_size); 1047 return -EACCES; 1048 } 1049 1050 if (env->prog->aux->stack_depth < -off) 1051 env->prog->aux->stack_depth = -off; 1052 1053 if (meta && meta->raw_mode) { 1054 meta->access_size = access_size; 1055 meta->regno = regno; 1056 return 0; 1057 } 1058 1059 for (i = 0; i < access_size; i++) { 1060 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { 1061 verbose("invalid indirect read from stack off %d+%d size %d\n", 1062 off, i, access_size); 1063 return -EACCES; 1064 } 1065 } 1066 return 0; 1067 } 1068 1069 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, 1070 int access_size, bool zero_size_allowed, 1071 struct bpf_call_arg_meta *meta) 1072 { 1073 struct bpf_reg_state *regs = env->cur_state.regs; 1074 1075 switch (regs[regno].type) { 1076 case PTR_TO_PACKET: 1077 return check_packet_access(env, regno, 0, access_size); 1078 case PTR_TO_MAP_VALUE: 1079 return check_map_access(env, regno, 0, access_size); 1080 case PTR_TO_MAP_VALUE_ADJ: 1081 return check_map_access_adj(env, regno, 0, access_size); 1082 default: /* const_imm|ptr_to_stack or invalid ptr */ 1083 return check_stack_boundary(env, regno, access_size, 1084 zero_size_allowed, meta); 1085 } 1086 } 1087 1088 static int check_func_arg(struct bpf_verifier_env *env, u32 regno, 1089 enum bpf_arg_type arg_type, 1090 struct bpf_call_arg_meta *meta) 1091 { 1092 struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; 1093 enum bpf_reg_type expected_type, type = reg->type; 1094 int err = 0; 1095 1096 if (arg_type == ARG_DONTCARE) 1097 return 0; 1098 1099 if (type == NOT_INIT) { 1100 verbose("R%d !read_ok\n", regno); 1101 return -EACCES; 1102 } 1103 1104 if (arg_type == ARG_ANYTHING) { 1105 if (is_pointer_value(env, regno)) { 1106 verbose("R%d leaks addr into helper function\n", regno); 1107 return -EACCES; 1108 } 1109 return 0; 1110 } 1111 1112 if (type == PTR_TO_PACKET && 1113 !may_access_direct_pkt_data(env, meta, BPF_READ)) { 1114 verbose("helper access to the packet is not allowed\n"); 1115 return -EACCES; 1116 } 1117 1118 if (arg_type == ARG_PTR_TO_MAP_KEY || 1119 arg_type == ARG_PTR_TO_MAP_VALUE) { 1120 expected_type = PTR_TO_STACK; 1121 if (type != PTR_TO_PACKET && type != expected_type) 1122 goto err_type; 1123 } else if (arg_type == ARG_CONST_SIZE || 1124 arg_type == ARG_CONST_SIZE_OR_ZERO) { 1125 expected_type = CONST_IMM; 1126 /* One exception. Allow UNKNOWN_VALUE registers when the 1127 * boundaries are known and don't cause unsafe memory accesses 1128 */ 1129 if (type != UNKNOWN_VALUE && type != expected_type) 1130 goto err_type; 1131 } else if (arg_type == ARG_CONST_MAP_PTR) { 1132 expected_type = CONST_PTR_TO_MAP; 1133 if (type != expected_type) 1134 goto err_type; 1135 } else if (arg_type == ARG_PTR_TO_CTX) { 1136 expected_type = PTR_TO_CTX; 1137 if (type != expected_type) 1138 goto err_type; 1139 } else if (arg_type == ARG_PTR_TO_MEM || 1140 arg_type == ARG_PTR_TO_UNINIT_MEM) { 1141 expected_type = PTR_TO_STACK; 1142 /* One exception here. In case function allows for NULL to be 1143 * passed in as argument, it's a CONST_IMM type. Final test 1144 * happens during stack boundary checking. 1145 */ 1146 if (type == CONST_IMM && reg->imm == 0) 1147 /* final test in check_stack_boundary() */; 1148 else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE && 1149 type != PTR_TO_MAP_VALUE_ADJ && type != expected_type) 1150 goto err_type; 1151 meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; 1152 } else { 1153 verbose("unsupported arg_type %d\n", arg_type); 1154 return -EFAULT; 1155 } 1156 1157 if (arg_type == ARG_CONST_MAP_PTR) { 1158 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ 1159 meta->map_ptr = reg->map_ptr; 1160 } else if (arg_type == ARG_PTR_TO_MAP_KEY) { 1161 /* bpf_map_xxx(..., map_ptr, ..., key) call: 1162 * check that [key, key + map->key_size) are within 1163 * stack limits and initialized 1164 */ 1165 if (!meta->map_ptr) { 1166 /* in function declaration map_ptr must come before 1167 * map_key, so that it's verified and known before 1168 * we have to check map_key here. Otherwise it means 1169 * that kernel subsystem misconfigured verifier 1170 */ 1171 verbose("invalid map_ptr to access map->key\n"); 1172 return -EACCES; 1173 } 1174 if (type == PTR_TO_PACKET) 1175 err = check_packet_access(env, regno, 0, 1176 meta->map_ptr->key_size); 1177 else 1178 err = check_stack_boundary(env, regno, 1179 meta->map_ptr->key_size, 1180 false, NULL); 1181 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { 1182 /* bpf_map_xxx(..., map_ptr, ..., value) call: 1183 * check [value, value + map->value_size) validity 1184 */ 1185 if (!meta->map_ptr) { 1186 /* kernel subsystem misconfigured verifier */ 1187 verbose("invalid map_ptr to access map->value\n"); 1188 return -EACCES; 1189 } 1190 if (type == PTR_TO_PACKET) 1191 err = check_packet_access(env, regno, 0, 1192 meta->map_ptr->value_size); 1193 else 1194 err = check_stack_boundary(env, regno, 1195 meta->map_ptr->value_size, 1196 false, NULL); 1197 } else if (arg_type == ARG_CONST_SIZE || 1198 arg_type == ARG_CONST_SIZE_OR_ZERO) { 1199 bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); 1200 1201 /* bpf_xxx(..., buf, len) call will access 'len' bytes 1202 * from stack pointer 'buf'. Check it 1203 * note: regno == len, regno - 1 == buf 1204 */ 1205 if (regno == 0) { 1206 /* kernel subsystem misconfigured verifier */ 1207 verbose("ARG_CONST_SIZE cannot be first argument\n"); 1208 return -EACCES; 1209 } 1210 1211 /* If the register is UNKNOWN_VALUE, the access check happens 1212 * using its boundaries. Otherwise, just use its imm 1213 */ 1214 if (type == UNKNOWN_VALUE) { 1215 /* For unprivileged variable accesses, disable raw 1216 * mode so that the program is required to 1217 * initialize all the memory that the helper could 1218 * just partially fill up. 1219 */ 1220 meta = NULL; 1221 1222 if (reg->min_value < 0) { 1223 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n", 1224 regno); 1225 return -EACCES; 1226 } 1227 1228 if (reg->min_value == 0) { 1229 err = check_helper_mem_access(env, regno - 1, 0, 1230 zero_size_allowed, 1231 meta); 1232 if (err) 1233 return err; 1234 } 1235 1236 if (reg->max_value == BPF_REGISTER_MAX_RANGE) { 1237 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", 1238 regno); 1239 return -EACCES; 1240 } 1241 err = check_helper_mem_access(env, regno - 1, 1242 reg->max_value, 1243 zero_size_allowed, meta); 1244 if (err) 1245 return err; 1246 } else { 1247 /* register is CONST_IMM */ 1248 err = check_helper_mem_access(env, regno - 1, reg->imm, 1249 zero_size_allowed, meta); 1250 } 1251 } 1252 1253 return err; 1254 err_type: 1255 verbose("R%d type=%s expected=%s\n", regno, 1256 reg_type_str[type], reg_type_str[expected_type]); 1257 return -EACCES; 1258 } 1259 1260 static int check_map_func_compatibility(struct bpf_map *map, int func_id) 1261 { 1262 if (!map) 1263 return 0; 1264 1265 /* We need a two way check, first is from map perspective ... */ 1266 switch (map->map_type) { 1267 case BPF_MAP_TYPE_PROG_ARRAY: 1268 if (func_id != BPF_FUNC_tail_call) 1269 goto error; 1270 break; 1271 case BPF_MAP_TYPE_PERF_EVENT_ARRAY: 1272 if (func_id != BPF_FUNC_perf_event_read && 1273 func_id != BPF_FUNC_perf_event_output) 1274 goto error; 1275 break; 1276 case BPF_MAP_TYPE_STACK_TRACE: 1277 if (func_id != BPF_FUNC_get_stackid) 1278 goto error; 1279 break; 1280 case BPF_MAP_TYPE_CGROUP_ARRAY: 1281 if (func_id != BPF_FUNC_skb_under_cgroup && 1282 func_id != BPF_FUNC_current_task_under_cgroup) 1283 goto error; 1284 break; 1285 case BPF_MAP_TYPE_ARRAY_OF_MAPS: 1286 case BPF_MAP_TYPE_HASH_OF_MAPS: 1287 if (func_id != BPF_FUNC_map_lookup_elem) 1288 goto error; 1289 default: 1290 break; 1291 } 1292 1293 /* ... and second from the function itself. */ 1294 switch (func_id) { 1295 case BPF_FUNC_tail_call: 1296 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) 1297 goto error; 1298 break; 1299 case BPF_FUNC_perf_event_read: 1300 case BPF_FUNC_perf_event_output: 1301 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) 1302 goto error; 1303 break; 1304 case BPF_FUNC_get_stackid: 1305 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) 1306 goto error; 1307 break; 1308 case BPF_FUNC_current_task_under_cgroup: 1309 case BPF_FUNC_skb_under_cgroup: 1310 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) 1311 goto error; 1312 break; 1313 default: 1314 break; 1315 } 1316 1317 return 0; 1318 error: 1319 verbose("cannot pass map_type %d into func %s#%d\n", 1320 map->map_type, func_id_name(func_id), func_id); 1321 return -EINVAL; 1322 } 1323 1324 static int check_raw_mode(const struct bpf_func_proto *fn) 1325 { 1326 int count = 0; 1327 1328 if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) 1329 count++; 1330 if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) 1331 count++; 1332 if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) 1333 count++; 1334 if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) 1335 count++; 1336 if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) 1337 count++; 1338 1339 return count > 1 ? -EINVAL : 0; 1340 } 1341 1342 static void clear_all_pkt_pointers(struct bpf_verifier_env *env) 1343 { 1344 struct bpf_verifier_state *state = &env->cur_state; 1345 struct bpf_reg_state *regs = state->regs, *reg; 1346 int i; 1347 1348 for (i = 0; i < MAX_BPF_REG; i++) 1349 if (regs[i].type == PTR_TO_PACKET || 1350 regs[i].type == PTR_TO_PACKET_END) 1351 mark_reg_unknown_value(regs, i); 1352 1353 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 1354 if (state->stack_slot_type[i] != STACK_SPILL) 1355 continue; 1356 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 1357 if (reg->type != PTR_TO_PACKET && 1358 reg->type != PTR_TO_PACKET_END) 1359 continue; 1360 __mark_reg_unknown_value(state->spilled_regs, 1361 i / BPF_REG_SIZE); 1362 } 1363 } 1364 1365 static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) 1366 { 1367 struct bpf_verifier_state *state = &env->cur_state; 1368 const struct bpf_func_proto *fn = NULL; 1369 struct bpf_reg_state *regs = state->regs; 1370 struct bpf_call_arg_meta meta; 1371 bool changes_data; 1372 int i, err; 1373 1374 /* find function prototype */ 1375 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { 1376 verbose("invalid func %s#%d\n", func_id_name(func_id), func_id); 1377 return -EINVAL; 1378 } 1379 1380 if (env->prog->aux->ops->get_func_proto) 1381 fn = env->prog->aux->ops->get_func_proto(func_id); 1382 1383 if (!fn) { 1384 verbose("unknown func %s#%d\n", func_id_name(func_id), func_id); 1385 return -EINVAL; 1386 } 1387 1388 /* eBPF programs must be GPL compatible to use GPL-ed functions */ 1389 if (!env->prog->gpl_compatible && fn->gpl_only) { 1390 verbose("cannot call GPL only function from proprietary program\n"); 1391 return -EINVAL; 1392 } 1393 1394 changes_data = bpf_helper_changes_pkt_data(fn->func); 1395 1396 memset(&meta, 0, sizeof(meta)); 1397 meta.pkt_access = fn->pkt_access; 1398 1399 /* We only support one arg being in raw mode at the moment, which 1400 * is sufficient for the helper functions we have right now. 1401 */ 1402 err = check_raw_mode(fn); 1403 if (err) { 1404 verbose("kernel subsystem misconfigured func %s#%d\n", 1405 func_id_name(func_id), func_id); 1406 return err; 1407 } 1408 1409 /* check args */ 1410 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); 1411 if (err) 1412 return err; 1413 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); 1414 if (err) 1415 return err; 1416 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); 1417 if (err) 1418 return err; 1419 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); 1420 if (err) 1421 return err; 1422 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); 1423 if (err) 1424 return err; 1425 1426 /* Mark slots with STACK_MISC in case of raw mode, stack offset 1427 * is inferred from register state. 1428 */ 1429 for (i = 0; i < meta.access_size; i++) { 1430 err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); 1431 if (err) 1432 return err; 1433 } 1434 1435 /* reset caller saved regs */ 1436 for (i = 0; i < CALLER_SAVED_REGS; i++) 1437 mark_reg_not_init(regs, caller_saved[i]); 1438 1439 /* update return register */ 1440 if (fn->ret_type == RET_INTEGER) { 1441 regs[BPF_REG_0].type = UNKNOWN_VALUE; 1442 } else if (fn->ret_type == RET_VOID) { 1443 regs[BPF_REG_0].type = NOT_INIT; 1444 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { 1445 struct bpf_insn_aux_data *insn_aux; 1446 1447 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; 1448 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0; 1449 /* remember map_ptr, so that check_map_access() 1450 * can check 'value_size' boundary of memory access 1451 * to map element returned from bpf_map_lookup_elem() 1452 */ 1453 if (meta.map_ptr == NULL) { 1454 verbose("kernel subsystem misconfigured verifier\n"); 1455 return -EINVAL; 1456 } 1457 regs[BPF_REG_0].map_ptr = meta.map_ptr; 1458 regs[BPF_REG_0].id = ++env->id_gen; 1459 insn_aux = &env->insn_aux_data[insn_idx]; 1460 if (!insn_aux->map_ptr) 1461 insn_aux->map_ptr = meta.map_ptr; 1462 else if (insn_aux->map_ptr != meta.map_ptr) 1463 insn_aux->map_ptr = BPF_MAP_PTR_POISON; 1464 } else { 1465 verbose("unknown return type %d of func %s#%d\n", 1466 fn->ret_type, func_id_name(func_id), func_id); 1467 return -EINVAL; 1468 } 1469 1470 err = check_map_func_compatibility(meta.map_ptr, func_id); 1471 if (err) 1472 return err; 1473 1474 if (changes_data) 1475 clear_all_pkt_pointers(env); 1476 return 0; 1477 } 1478 1479 static int check_packet_ptr_add(struct bpf_verifier_env *env, 1480 struct bpf_insn *insn) 1481 { 1482 struct bpf_reg_state *regs = env->cur_state.regs; 1483 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1484 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1485 struct bpf_reg_state tmp_reg; 1486 s32 imm; 1487 1488 if (BPF_SRC(insn->code) == BPF_K) { 1489 /* pkt_ptr += imm */ 1490 imm = insn->imm; 1491 1492 add_imm: 1493 if (imm < 0) { 1494 verbose("addition of negative constant to packet pointer is not allowed\n"); 1495 return -EACCES; 1496 } 1497 if (imm >= MAX_PACKET_OFF || 1498 imm + dst_reg->off >= MAX_PACKET_OFF) { 1499 verbose("constant %d is too large to add to packet pointer\n", 1500 imm); 1501 return -EACCES; 1502 } 1503 /* a constant was added to pkt_ptr. 1504 * Remember it while keeping the same 'id' 1505 */ 1506 dst_reg->off += imm; 1507 } else { 1508 bool had_id; 1509 1510 if (src_reg->type == PTR_TO_PACKET) { 1511 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ 1512 tmp_reg = *dst_reg; /* save r7 state */ 1513 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ 1514 src_reg = &tmp_reg; /* pretend it's src_reg state */ 1515 /* if the checks below reject it, the copy won't matter, 1516 * since we're rejecting the whole program. If all ok, 1517 * then imm22 state will be added to r7 1518 * and r7 will be pkt(id=0,off=22,r=62) while 1519 * r6 will stay as pkt(id=0,off=0,r=62) 1520 */ 1521 } 1522 1523 if (src_reg->type == CONST_IMM) { 1524 /* pkt_ptr += reg where reg is known constant */ 1525 imm = src_reg->imm; 1526 goto add_imm; 1527 } 1528 /* disallow pkt_ptr += reg 1529 * if reg is not uknown_value with guaranteed zero upper bits 1530 * otherwise pkt_ptr may overflow and addition will become 1531 * subtraction which is not allowed 1532 */ 1533 if (src_reg->type != UNKNOWN_VALUE) { 1534 verbose("cannot add '%s' to ptr_to_packet\n", 1535 reg_type_str[src_reg->type]); 1536 return -EACCES; 1537 } 1538 if (src_reg->imm < 48) { 1539 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", 1540 src_reg->imm); 1541 return -EACCES; 1542 } 1543 1544 had_id = (dst_reg->id != 0); 1545 1546 /* dst_reg stays as pkt_ptr type and since some positive 1547 * integer value was added to the pointer, increment its 'id' 1548 */ 1549 dst_reg->id = ++env->id_gen; 1550 1551 /* something was added to pkt_ptr, set range to zero */ 1552 dst_reg->aux_off += dst_reg->off; 1553 dst_reg->off = 0; 1554 dst_reg->range = 0; 1555 if (had_id) 1556 dst_reg->aux_off_align = min(dst_reg->aux_off_align, 1557 src_reg->min_align); 1558 else 1559 dst_reg->aux_off_align = src_reg->min_align; 1560 } 1561 return 0; 1562 } 1563 1564 static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) 1565 { 1566 struct bpf_reg_state *regs = env->cur_state.regs; 1567 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1568 u8 opcode = BPF_OP(insn->code); 1569 s64 imm_log2; 1570 1571 /* for type == UNKNOWN_VALUE: 1572 * imm > 0 -> number of zero upper bits 1573 * imm == 0 -> don't track which is the same as all bits can be non-zero 1574 */ 1575 1576 if (BPF_SRC(insn->code) == BPF_X) { 1577 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1578 1579 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && 1580 dst_reg->imm && opcode == BPF_ADD) { 1581 /* dreg += sreg 1582 * where both have zero upper bits. Adding them 1583 * can only result making one more bit non-zero 1584 * in the larger value. 1585 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) 1586 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) 1587 */ 1588 dst_reg->imm = min(dst_reg->imm, src_reg->imm); 1589 dst_reg->imm--; 1590 return 0; 1591 } 1592 if (src_reg->type == CONST_IMM && src_reg->imm > 0 && 1593 dst_reg->imm && opcode == BPF_ADD) { 1594 /* dreg += sreg 1595 * where dreg has zero upper bits and sreg is const. 1596 * Adding them can only result making one more bit 1597 * non-zero in the larger value. 1598 */ 1599 imm_log2 = __ilog2_u64((long long)src_reg->imm); 1600 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1601 dst_reg->imm--; 1602 return 0; 1603 } 1604 /* all other cases non supported yet, just mark dst_reg */ 1605 dst_reg->imm = 0; 1606 return 0; 1607 } 1608 1609 /* sign extend 32-bit imm into 64-bit to make sure that 1610 * negative values occupy bit 63. Note ilog2() would have 1611 * been incorrect, since sizeof(insn->imm) == 4 1612 */ 1613 imm_log2 = __ilog2_u64((long long)insn->imm); 1614 1615 if (dst_reg->imm && opcode == BPF_LSH) { 1616 /* reg <<= imm 1617 * if reg was a result of 2 byte load, then its imm == 48 1618 * which means that upper 48 bits are zero and shifting this reg 1619 * left by 4 would mean that upper 44 bits are still zero 1620 */ 1621 dst_reg->imm -= insn->imm; 1622 } else if (dst_reg->imm && opcode == BPF_MUL) { 1623 /* reg *= imm 1624 * if multiplying by 14 subtract 4 1625 * This is conservative calculation of upper zero bits. 1626 * It's not trying to special case insn->imm == 1 or 0 cases 1627 */ 1628 dst_reg->imm -= imm_log2 + 1; 1629 } else if (opcode == BPF_AND) { 1630 /* reg &= imm */ 1631 dst_reg->imm = 63 - imm_log2; 1632 } else if (dst_reg->imm && opcode == BPF_ADD) { 1633 /* reg += imm */ 1634 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1635 dst_reg->imm--; 1636 } else if (opcode == BPF_RSH) { 1637 /* reg >>= imm 1638 * which means that after right shift, upper bits will be zero 1639 * note that verifier already checked that 1640 * 0 <= imm < 64 for shift insn 1641 */ 1642 dst_reg->imm += insn->imm; 1643 if (unlikely(dst_reg->imm > 64)) 1644 /* some dumb code did: 1645 * r2 = *(u32 *)mem; 1646 * r2 >>= 32; 1647 * and all bits are zero now */ 1648 dst_reg->imm = 64; 1649 } else { 1650 /* all other alu ops, means that we don't know what will 1651 * happen to the value, mark it with unknown number of zero bits 1652 */ 1653 dst_reg->imm = 0; 1654 } 1655 1656 if (dst_reg->imm < 0) { 1657 /* all 64 bits of the register can contain non-zero bits 1658 * and such value cannot be added to ptr_to_packet, since it 1659 * may overflow, mark it as unknown to avoid further eval 1660 */ 1661 dst_reg->imm = 0; 1662 } 1663 return 0; 1664 } 1665 1666 static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, 1667 struct bpf_insn *insn) 1668 { 1669 struct bpf_reg_state *regs = env->cur_state.regs; 1670 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1671 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1672 u8 opcode = BPF_OP(insn->code); 1673 u64 dst_imm = dst_reg->imm; 1674 1675 /* dst_reg->type == CONST_IMM here. Simulate execution of insns 1676 * containing ALU ops. Don't care about overflow or negative 1677 * values, just add/sub/... them; registers are in u64. 1678 */ 1679 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) { 1680 dst_imm += insn->imm; 1681 } else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && 1682 src_reg->type == CONST_IMM) { 1683 dst_imm += src_reg->imm; 1684 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) { 1685 dst_imm -= insn->imm; 1686 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X && 1687 src_reg->type == CONST_IMM) { 1688 dst_imm -= src_reg->imm; 1689 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) { 1690 dst_imm *= insn->imm; 1691 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X && 1692 src_reg->type == CONST_IMM) { 1693 dst_imm *= src_reg->imm; 1694 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) { 1695 dst_imm |= insn->imm; 1696 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X && 1697 src_reg->type == CONST_IMM) { 1698 dst_imm |= src_reg->imm; 1699 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) { 1700 dst_imm &= insn->imm; 1701 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X && 1702 src_reg->type == CONST_IMM) { 1703 dst_imm &= src_reg->imm; 1704 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) { 1705 dst_imm >>= insn->imm; 1706 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X && 1707 src_reg->type == CONST_IMM) { 1708 dst_imm >>= src_reg->imm; 1709 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) { 1710 dst_imm <<= insn->imm; 1711 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X && 1712 src_reg->type == CONST_IMM) { 1713 dst_imm <<= src_reg->imm; 1714 } else { 1715 mark_reg_unknown_value(regs, insn->dst_reg); 1716 goto out; 1717 } 1718 1719 dst_reg->imm = dst_imm; 1720 out: 1721 return 0; 1722 } 1723 1724 static void check_reg_overflow(struct bpf_reg_state *reg) 1725 { 1726 if (reg->max_value > BPF_REGISTER_MAX_RANGE) 1727 reg->max_value = BPF_REGISTER_MAX_RANGE; 1728 if (reg->min_value < BPF_REGISTER_MIN_RANGE || 1729 reg->min_value > BPF_REGISTER_MAX_RANGE) 1730 reg->min_value = BPF_REGISTER_MIN_RANGE; 1731 } 1732 1733 static u32 calc_align(u32 imm) 1734 { 1735 if (!imm) 1736 return 1U << 31; 1737 return imm - ((imm - 1) & imm); 1738 } 1739 1740 static void adjust_reg_min_max_vals(struct bpf_verifier_env *env, 1741 struct bpf_insn *insn) 1742 { 1743 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1744 s64 min_val = BPF_REGISTER_MIN_RANGE; 1745 u64 max_val = BPF_REGISTER_MAX_RANGE; 1746 u8 opcode = BPF_OP(insn->code); 1747 u32 dst_align, src_align; 1748 1749 dst_reg = ®s[insn->dst_reg]; 1750 src_align = 0; 1751 if (BPF_SRC(insn->code) == BPF_X) { 1752 check_reg_overflow(®s[insn->src_reg]); 1753 min_val = regs[insn->src_reg].min_value; 1754 max_val = regs[insn->src_reg].max_value; 1755 1756 /* If the source register is a random pointer then the 1757 * min_value/max_value values represent the range of the known 1758 * accesses into that value, not the actual min/max value of the 1759 * register itself. In this case we have to reset the reg range 1760 * values so we know it is not safe to look at. 1761 */ 1762 if (regs[insn->src_reg].type != CONST_IMM && 1763 regs[insn->src_reg].type != UNKNOWN_VALUE) { 1764 min_val = BPF_REGISTER_MIN_RANGE; 1765 max_val = BPF_REGISTER_MAX_RANGE; 1766 src_align = 0; 1767 } else { 1768 src_align = regs[insn->src_reg].min_align; 1769 } 1770 } else if (insn->imm < BPF_REGISTER_MAX_RANGE && 1771 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) { 1772 min_val = max_val = insn->imm; 1773 src_align = calc_align(insn->imm); 1774 } 1775 1776 dst_align = dst_reg->min_align; 1777 1778 /* We don't know anything about what was done to this register, mark it 1779 * as unknown. 1780 */ 1781 if (min_val == BPF_REGISTER_MIN_RANGE && 1782 max_val == BPF_REGISTER_MAX_RANGE) { 1783 reset_reg_range_values(regs, insn->dst_reg); 1784 return; 1785 } 1786 1787 /* If one of our values was at the end of our ranges then we can't just 1788 * do our normal operations to the register, we need to set the values 1789 * to the min/max since they are undefined. 1790 */ 1791 if (min_val == BPF_REGISTER_MIN_RANGE) 1792 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1793 if (max_val == BPF_REGISTER_MAX_RANGE) 1794 dst_reg->max_value = BPF_REGISTER_MAX_RANGE; 1795 1796 switch (opcode) { 1797 case BPF_ADD: 1798 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1799 dst_reg->min_value += min_val; 1800 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1801 dst_reg->max_value += max_val; 1802 dst_reg->min_align = min(src_align, dst_align); 1803 break; 1804 case BPF_SUB: 1805 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1806 dst_reg->min_value -= min_val; 1807 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1808 dst_reg->max_value -= max_val; 1809 dst_reg->min_align = min(src_align, dst_align); 1810 break; 1811 case BPF_MUL: 1812 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1813 dst_reg->min_value *= min_val; 1814 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1815 dst_reg->max_value *= max_val; 1816 dst_reg->min_align = max(src_align, dst_align); 1817 break; 1818 case BPF_AND: 1819 /* Disallow AND'ing of negative numbers, ain't nobody got time 1820 * for that. Otherwise the minimum is 0 and the max is the max 1821 * value we could AND against. 1822 */ 1823 if (min_val < 0) 1824 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1825 else 1826 dst_reg->min_value = 0; 1827 dst_reg->max_value = max_val; 1828 dst_reg->min_align = max(src_align, dst_align); 1829 break; 1830 case BPF_LSH: 1831 /* Gotta have special overflow logic here, if we're shifting 1832 * more than MAX_RANGE then just assume we have an invalid 1833 * range. 1834 */ 1835 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) { 1836 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1837 dst_reg->min_align = 1; 1838 } else { 1839 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1840 dst_reg->min_value <<= min_val; 1841 if (!dst_reg->min_align) 1842 dst_reg->min_align = 1; 1843 dst_reg->min_align <<= min_val; 1844 } 1845 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE)) 1846 dst_reg->max_value = BPF_REGISTER_MAX_RANGE; 1847 else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1848 dst_reg->max_value <<= max_val; 1849 break; 1850 case BPF_RSH: 1851 /* RSH by a negative number is undefined, and the BPF_RSH is an 1852 * unsigned shift, so make the appropriate casts. 1853 */ 1854 if (min_val < 0 || dst_reg->min_value < 0) { 1855 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1856 } else { 1857 dst_reg->min_value = 1858 (u64)(dst_reg->min_value) >> min_val; 1859 } 1860 if (min_val < 0) { 1861 dst_reg->min_align = 1; 1862 } else { 1863 dst_reg->min_align >>= (u64) min_val; 1864 if (!dst_reg->min_align) 1865 dst_reg->min_align = 1; 1866 } 1867 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1868 dst_reg->max_value >>= max_val; 1869 break; 1870 default: 1871 reset_reg_range_values(regs, insn->dst_reg); 1872 break; 1873 } 1874 1875 check_reg_overflow(dst_reg); 1876 } 1877 1878 /* check validity of 32-bit and 64-bit arithmetic operations */ 1879 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) 1880 { 1881 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1882 u8 opcode = BPF_OP(insn->code); 1883 int err; 1884 1885 if (opcode == BPF_END || opcode == BPF_NEG) { 1886 if (opcode == BPF_NEG) { 1887 if (BPF_SRC(insn->code) != 0 || 1888 insn->src_reg != BPF_REG_0 || 1889 insn->off != 0 || insn->imm != 0) { 1890 verbose("BPF_NEG uses reserved fields\n"); 1891 return -EINVAL; 1892 } 1893 } else { 1894 if (insn->src_reg != BPF_REG_0 || insn->off != 0 || 1895 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { 1896 verbose("BPF_END uses reserved fields\n"); 1897 return -EINVAL; 1898 } 1899 } 1900 1901 /* check src operand */ 1902 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1903 if (err) 1904 return err; 1905 1906 if (is_pointer_value(env, insn->dst_reg)) { 1907 verbose("R%d pointer arithmetic prohibited\n", 1908 insn->dst_reg); 1909 return -EACCES; 1910 } 1911 1912 /* check dest operand */ 1913 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1914 if (err) 1915 return err; 1916 1917 } else if (opcode == BPF_MOV) { 1918 1919 if (BPF_SRC(insn->code) == BPF_X) { 1920 if (insn->imm != 0 || insn->off != 0) { 1921 verbose("BPF_MOV uses reserved fields\n"); 1922 return -EINVAL; 1923 } 1924 1925 /* check src operand */ 1926 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1927 if (err) 1928 return err; 1929 } else { 1930 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 1931 verbose("BPF_MOV uses reserved fields\n"); 1932 return -EINVAL; 1933 } 1934 } 1935 1936 /* check dest operand */ 1937 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1938 if (err) 1939 return err; 1940 1941 /* we are setting our register to something new, we need to 1942 * reset its range values. 1943 */ 1944 reset_reg_range_values(regs, insn->dst_reg); 1945 1946 if (BPF_SRC(insn->code) == BPF_X) { 1947 if (BPF_CLASS(insn->code) == BPF_ALU64) { 1948 /* case: R1 = R2 1949 * copy register state to dest reg 1950 */ 1951 regs[insn->dst_reg] = regs[insn->src_reg]; 1952 } else { 1953 if (is_pointer_value(env, insn->src_reg)) { 1954 verbose("R%d partial copy of pointer\n", 1955 insn->src_reg); 1956 return -EACCES; 1957 } 1958 mark_reg_unknown_value(regs, insn->dst_reg); 1959 } 1960 } else { 1961 /* case: R = imm 1962 * remember the value we stored into this reg 1963 */ 1964 regs[insn->dst_reg].type = CONST_IMM; 1965 regs[insn->dst_reg].imm = insn->imm; 1966 regs[insn->dst_reg].id = 0; 1967 regs[insn->dst_reg].max_value = insn->imm; 1968 regs[insn->dst_reg].min_value = insn->imm; 1969 regs[insn->dst_reg].min_align = calc_align(insn->imm); 1970 } 1971 1972 } else if (opcode > BPF_END) { 1973 verbose("invalid BPF_ALU opcode %x\n", opcode); 1974 return -EINVAL; 1975 1976 } else { /* all other ALU ops: and, sub, xor, add, ... */ 1977 1978 if (BPF_SRC(insn->code) == BPF_X) { 1979 if (insn->imm != 0 || insn->off != 0) { 1980 verbose("BPF_ALU uses reserved fields\n"); 1981 return -EINVAL; 1982 } 1983 /* check src1 operand */ 1984 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1985 if (err) 1986 return err; 1987 } else { 1988 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 1989 verbose("BPF_ALU uses reserved fields\n"); 1990 return -EINVAL; 1991 } 1992 } 1993 1994 /* check src2 operand */ 1995 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1996 if (err) 1997 return err; 1998 1999 if ((opcode == BPF_MOD || opcode == BPF_DIV) && 2000 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { 2001 verbose("div by zero\n"); 2002 return -EINVAL; 2003 } 2004 2005 if ((opcode == BPF_LSH || opcode == BPF_RSH || 2006 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { 2007 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; 2008 2009 if (insn->imm < 0 || insn->imm >= size) { 2010 verbose("invalid shift %d\n", insn->imm); 2011 return -EINVAL; 2012 } 2013 } 2014 2015 /* check dest operand */ 2016 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 2017 if (err) 2018 return err; 2019 2020 dst_reg = ®s[insn->dst_reg]; 2021 2022 /* first we want to adjust our ranges. */ 2023 adjust_reg_min_max_vals(env, insn); 2024 2025 /* pattern match 'bpf_add Rx, imm' instruction */ 2026 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && 2027 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { 2028 dst_reg->type = PTR_TO_STACK; 2029 dst_reg->imm = insn->imm; 2030 return 0; 2031 } else if (opcode == BPF_ADD && 2032 BPF_CLASS(insn->code) == BPF_ALU64 && 2033 dst_reg->type == PTR_TO_STACK && 2034 ((BPF_SRC(insn->code) == BPF_X && 2035 regs[insn->src_reg].type == CONST_IMM) || 2036 BPF_SRC(insn->code) == BPF_K)) { 2037 if (BPF_SRC(insn->code) == BPF_X) 2038 dst_reg->imm += regs[insn->src_reg].imm; 2039 else 2040 dst_reg->imm += insn->imm; 2041 return 0; 2042 } else if (opcode == BPF_ADD && 2043 BPF_CLASS(insn->code) == BPF_ALU64 && 2044 (dst_reg->type == PTR_TO_PACKET || 2045 (BPF_SRC(insn->code) == BPF_X && 2046 regs[insn->src_reg].type == PTR_TO_PACKET))) { 2047 /* ptr_to_packet += K|X */ 2048 return check_packet_ptr_add(env, insn); 2049 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 2050 dst_reg->type == UNKNOWN_VALUE && 2051 env->allow_ptr_leaks) { 2052 /* unknown += K|X */ 2053 return evaluate_reg_alu(env, insn); 2054 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 2055 dst_reg->type == CONST_IMM && 2056 env->allow_ptr_leaks) { 2057 /* reg_imm += K|X */ 2058 return evaluate_reg_imm_alu(env, insn); 2059 } else if (is_pointer_value(env, insn->dst_reg)) { 2060 verbose("R%d pointer arithmetic prohibited\n", 2061 insn->dst_reg); 2062 return -EACCES; 2063 } else if (BPF_SRC(insn->code) == BPF_X && 2064 is_pointer_value(env, insn->src_reg)) { 2065 verbose("R%d pointer arithmetic prohibited\n", 2066 insn->src_reg); 2067 return -EACCES; 2068 } 2069 2070 /* If we did pointer math on a map value then just set it to our 2071 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or 2072 * loads to this register appropriately, otherwise just mark the 2073 * register as unknown. 2074 */ 2075 if (env->allow_ptr_leaks && 2076 BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD && 2077 (dst_reg->type == PTR_TO_MAP_VALUE || 2078 dst_reg->type == PTR_TO_MAP_VALUE_ADJ)) 2079 dst_reg->type = PTR_TO_MAP_VALUE_ADJ; 2080 else 2081 mark_reg_unknown_value(regs, insn->dst_reg); 2082 } 2083 2084 return 0; 2085 } 2086 2087 static void find_good_pkt_pointers(struct bpf_verifier_state *state, 2088 struct bpf_reg_state *dst_reg) 2089 { 2090 struct bpf_reg_state *regs = state->regs, *reg; 2091 int i; 2092 2093 /* LLVM can generate two kind of checks: 2094 * 2095 * Type 1: 2096 * 2097 * r2 = r3; 2098 * r2 += 8; 2099 * if (r2 > pkt_end) goto <handle exception> 2100 * <access okay> 2101 * 2102 * Where: 2103 * r2 == dst_reg, pkt_end == src_reg 2104 * r2=pkt(id=n,off=8,r=0) 2105 * r3=pkt(id=n,off=0,r=0) 2106 * 2107 * Type 2: 2108 * 2109 * r2 = r3; 2110 * r2 += 8; 2111 * if (pkt_end >= r2) goto <access okay> 2112 * <handle exception> 2113 * 2114 * Where: 2115 * pkt_end == dst_reg, r2 == src_reg 2116 * r2=pkt(id=n,off=8,r=0) 2117 * r3=pkt(id=n,off=0,r=0) 2118 * 2119 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) 2120 * so that range of bytes [r3, r3 + 8) is safe to access. 2121 */ 2122 2123 for (i = 0; i < MAX_BPF_REG; i++) 2124 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) 2125 /* keep the maximum range already checked */ 2126 regs[i].range = max(regs[i].range, dst_reg->off); 2127 2128 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 2129 if (state->stack_slot_type[i] != STACK_SPILL) 2130 continue; 2131 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 2132 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) 2133 reg->range = max(reg->range, dst_reg->off); 2134 } 2135 } 2136 2137 /* Adjusts the register min/max values in the case that the dst_reg is the 2138 * variable register that we are working on, and src_reg is a constant or we're 2139 * simply doing a BPF_K check. 2140 */ 2141 static void reg_set_min_max(struct bpf_reg_state *true_reg, 2142 struct bpf_reg_state *false_reg, u64 val, 2143 u8 opcode) 2144 { 2145 switch (opcode) { 2146 case BPF_JEQ: 2147 /* If this is false then we know nothing Jon Snow, but if it is 2148 * true then we know for sure. 2149 */ 2150 true_reg->max_value = true_reg->min_value = val; 2151 break; 2152 case BPF_JNE: 2153 /* If this is true we know nothing Jon Snow, but if it is false 2154 * we know the value for sure; 2155 */ 2156 false_reg->max_value = false_reg->min_value = val; 2157 break; 2158 case BPF_JGT: 2159 /* Unsigned comparison, the minimum value is 0. */ 2160 false_reg->min_value = 0; 2161 /* fallthrough */ 2162 case BPF_JSGT: 2163 /* If this is false then we know the maximum val is val, 2164 * otherwise we know the min val is val+1. 2165 */ 2166 false_reg->max_value = val; 2167 true_reg->min_value = val + 1; 2168 break; 2169 case BPF_JGE: 2170 /* Unsigned comparison, the minimum value is 0. */ 2171 false_reg->min_value = 0; 2172 /* fallthrough */ 2173 case BPF_JSGE: 2174 /* If this is false then we know the maximum value is val - 1, 2175 * otherwise we know the mimimum value is val. 2176 */ 2177 false_reg->max_value = val - 1; 2178 true_reg->min_value = val; 2179 break; 2180 default: 2181 break; 2182 } 2183 2184 check_reg_overflow(false_reg); 2185 check_reg_overflow(true_reg); 2186 } 2187 2188 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg 2189 * is the variable reg. 2190 */ 2191 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, 2192 struct bpf_reg_state *false_reg, u64 val, 2193 u8 opcode) 2194 { 2195 switch (opcode) { 2196 case BPF_JEQ: 2197 /* If this is false then we know nothing Jon Snow, but if it is 2198 * true then we know for sure. 2199 */ 2200 true_reg->max_value = true_reg->min_value = val; 2201 break; 2202 case BPF_JNE: 2203 /* If this is true we know nothing Jon Snow, but if it is false 2204 * we know the value for sure; 2205 */ 2206 false_reg->max_value = false_reg->min_value = val; 2207 break; 2208 case BPF_JGT: 2209 /* Unsigned comparison, the minimum value is 0. */ 2210 true_reg->min_value = 0; 2211 /* fallthrough */ 2212 case BPF_JSGT: 2213 /* 2214 * If this is false, then the val is <= the register, if it is 2215 * true the register <= to the val. 2216 */ 2217 false_reg->min_value = val; 2218 true_reg->max_value = val - 1; 2219 break; 2220 case BPF_JGE: 2221 /* Unsigned comparison, the minimum value is 0. */ 2222 true_reg->min_value = 0; 2223 /* fallthrough */ 2224 case BPF_JSGE: 2225 /* If this is false then constant < register, if it is true then 2226 * the register < constant. 2227 */ 2228 false_reg->min_value = val + 1; 2229 true_reg->max_value = val; 2230 break; 2231 default: 2232 break; 2233 } 2234 2235 check_reg_overflow(false_reg); 2236 check_reg_overflow(true_reg); 2237 } 2238 2239 static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, 2240 enum bpf_reg_type type) 2241 { 2242 struct bpf_reg_state *reg = ®s[regno]; 2243 2244 if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { 2245 if (type == UNKNOWN_VALUE) { 2246 __mark_reg_unknown_value(regs, regno); 2247 } else if (reg->map_ptr->inner_map_meta) { 2248 reg->type = CONST_PTR_TO_MAP; 2249 reg->map_ptr = reg->map_ptr->inner_map_meta; 2250 } else { 2251 reg->type = type; 2252 } 2253 /* We don't need id from this point onwards anymore, thus we 2254 * should better reset it, so that state pruning has chances 2255 * to take effect. 2256 */ 2257 reg->id = 0; 2258 } 2259 } 2260 2261 /* The logic is similar to find_good_pkt_pointers(), both could eventually 2262 * be folded together at some point. 2263 */ 2264 static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, 2265 enum bpf_reg_type type) 2266 { 2267 struct bpf_reg_state *regs = state->regs; 2268 u32 id = regs[regno].id; 2269 int i; 2270 2271 for (i = 0; i < MAX_BPF_REG; i++) 2272 mark_map_reg(regs, i, id, type); 2273 2274 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 2275 if (state->stack_slot_type[i] != STACK_SPILL) 2276 continue; 2277 mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type); 2278 } 2279 } 2280 2281 static int check_cond_jmp_op(struct bpf_verifier_env *env, 2282 struct bpf_insn *insn, int *insn_idx) 2283 { 2284 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; 2285 struct bpf_reg_state *regs = this_branch->regs, *dst_reg; 2286 u8 opcode = BPF_OP(insn->code); 2287 int err; 2288 2289 if (opcode > BPF_EXIT) { 2290 verbose("invalid BPF_JMP opcode %x\n", opcode); 2291 return -EINVAL; 2292 } 2293 2294 if (BPF_SRC(insn->code) == BPF_X) { 2295 if (insn->imm != 0) { 2296 verbose("BPF_JMP uses reserved fields\n"); 2297 return -EINVAL; 2298 } 2299 2300 /* check src1 operand */ 2301 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2302 if (err) 2303 return err; 2304 2305 if (is_pointer_value(env, insn->src_reg)) { 2306 verbose("R%d pointer comparison prohibited\n", 2307 insn->src_reg); 2308 return -EACCES; 2309 } 2310 } else { 2311 if (insn->src_reg != BPF_REG_0) { 2312 verbose("BPF_JMP uses reserved fields\n"); 2313 return -EINVAL; 2314 } 2315 } 2316 2317 /* check src2 operand */ 2318 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 2319 if (err) 2320 return err; 2321 2322 dst_reg = ®s[insn->dst_reg]; 2323 2324 /* detect if R == 0 where R was initialized to zero earlier */ 2325 if (BPF_SRC(insn->code) == BPF_K && 2326 (opcode == BPF_JEQ || opcode == BPF_JNE) && 2327 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { 2328 if (opcode == BPF_JEQ) { 2329 /* if (imm == imm) goto pc+off; 2330 * only follow the goto, ignore fall-through 2331 */ 2332 *insn_idx += insn->off; 2333 return 0; 2334 } else { 2335 /* if (imm != imm) goto pc+off; 2336 * only follow fall-through branch, since 2337 * that's where the program will go 2338 */ 2339 return 0; 2340 } 2341 } 2342 2343 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); 2344 if (!other_branch) 2345 return -EFAULT; 2346 2347 /* detect if we are comparing against a constant value so we can adjust 2348 * our min/max values for our dst register. 2349 */ 2350 if (BPF_SRC(insn->code) == BPF_X) { 2351 if (regs[insn->src_reg].type == CONST_IMM) 2352 reg_set_min_max(&other_branch->regs[insn->dst_reg], 2353 dst_reg, regs[insn->src_reg].imm, 2354 opcode); 2355 else if (dst_reg->type == CONST_IMM) 2356 reg_set_min_max_inv(&other_branch->regs[insn->src_reg], 2357 ®s[insn->src_reg], dst_reg->imm, 2358 opcode); 2359 } else { 2360 reg_set_min_max(&other_branch->regs[insn->dst_reg], 2361 dst_reg, insn->imm, opcode); 2362 } 2363 2364 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ 2365 if (BPF_SRC(insn->code) == BPF_K && 2366 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && 2367 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { 2368 /* Mark all identical map registers in each branch as either 2369 * safe or unknown depending R == 0 or R != 0 conditional. 2370 */ 2371 mark_map_regs(this_branch, insn->dst_reg, 2372 opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE); 2373 mark_map_regs(other_branch, insn->dst_reg, 2374 opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE); 2375 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && 2376 dst_reg->type == PTR_TO_PACKET && 2377 regs[insn->src_reg].type == PTR_TO_PACKET_END) { 2378 find_good_pkt_pointers(this_branch, dst_reg); 2379 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && 2380 dst_reg->type == PTR_TO_PACKET_END && 2381 regs[insn->src_reg].type == PTR_TO_PACKET) { 2382 find_good_pkt_pointers(other_branch, ®s[insn->src_reg]); 2383 } else if (is_pointer_value(env, insn->dst_reg)) { 2384 verbose("R%d pointer comparison prohibited\n", insn->dst_reg); 2385 return -EACCES; 2386 } 2387 if (log_level) 2388 print_verifier_state(this_branch); 2389 return 0; 2390 } 2391 2392 /* return the map pointer stored inside BPF_LD_IMM64 instruction */ 2393 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) 2394 { 2395 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; 2396 2397 return (struct bpf_map *) (unsigned long) imm64; 2398 } 2399 2400 /* verify BPF_LD_IMM64 instruction */ 2401 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) 2402 { 2403 struct bpf_reg_state *regs = env->cur_state.regs; 2404 int err; 2405 2406 if (BPF_SIZE(insn->code) != BPF_DW) { 2407 verbose("invalid BPF_LD_IMM insn\n"); 2408 return -EINVAL; 2409 } 2410 if (insn->off != 0) { 2411 verbose("BPF_LD_IMM64 uses reserved fields\n"); 2412 return -EINVAL; 2413 } 2414 2415 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 2416 if (err) 2417 return err; 2418 2419 if (insn->src_reg == 0) { 2420 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; 2421 2422 regs[insn->dst_reg].type = CONST_IMM; 2423 regs[insn->dst_reg].imm = imm; 2424 regs[insn->dst_reg].id = 0; 2425 return 0; 2426 } 2427 2428 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ 2429 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); 2430 2431 regs[insn->dst_reg].type = CONST_PTR_TO_MAP; 2432 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); 2433 return 0; 2434 } 2435 2436 static bool may_access_skb(enum bpf_prog_type type) 2437 { 2438 switch (type) { 2439 case BPF_PROG_TYPE_SOCKET_FILTER: 2440 case BPF_PROG_TYPE_SCHED_CLS: 2441 case BPF_PROG_TYPE_SCHED_ACT: 2442 return true; 2443 default: 2444 return false; 2445 } 2446 } 2447 2448 /* verify safety of LD_ABS|LD_IND instructions: 2449 * - they can only appear in the programs where ctx == skb 2450 * - since they are wrappers of function calls, they scratch R1-R5 registers, 2451 * preserve R6-R9, and store return value into R0 2452 * 2453 * Implicit input: 2454 * ctx == skb == R6 == CTX 2455 * 2456 * Explicit input: 2457 * SRC == any register 2458 * IMM == 32-bit immediate 2459 * 2460 * Output: 2461 * R0 - 8/16/32-bit skb data converted to cpu endianness 2462 */ 2463 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) 2464 { 2465 struct bpf_reg_state *regs = env->cur_state.regs; 2466 u8 mode = BPF_MODE(insn->code); 2467 int i, err; 2468 2469 if (!may_access_skb(env->prog->type)) { 2470 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); 2471 return -EINVAL; 2472 } 2473 2474 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || 2475 BPF_SIZE(insn->code) == BPF_DW || 2476 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { 2477 verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); 2478 return -EINVAL; 2479 } 2480 2481 /* check whether implicit source operand (register R6) is readable */ 2482 err = check_reg_arg(regs, BPF_REG_6, SRC_OP); 2483 if (err) 2484 return err; 2485 2486 if (regs[BPF_REG_6].type != PTR_TO_CTX) { 2487 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); 2488 return -EINVAL; 2489 } 2490 2491 if (mode == BPF_IND) { 2492 /* check explicit source operand */ 2493 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2494 if (err) 2495 return err; 2496 } 2497 2498 /* reset caller saved regs to unreadable */ 2499 for (i = 0; i < CALLER_SAVED_REGS; i++) 2500 mark_reg_not_init(regs, caller_saved[i]); 2501 2502 /* mark destination R0 register as readable, since it contains 2503 * the value fetched from the packet 2504 */ 2505 regs[BPF_REG_0].type = UNKNOWN_VALUE; 2506 return 0; 2507 } 2508 2509 /* non-recursive DFS pseudo code 2510 * 1 procedure DFS-iterative(G,v): 2511 * 2 label v as discovered 2512 * 3 let S be a stack 2513 * 4 S.push(v) 2514 * 5 while S is not empty 2515 * 6 t <- S.pop() 2516 * 7 if t is what we're looking for: 2517 * 8 return t 2518 * 9 for all edges e in G.adjacentEdges(t) do 2519 * 10 if edge e is already labelled 2520 * 11 continue with the next edge 2521 * 12 w <- G.adjacentVertex(t,e) 2522 * 13 if vertex w is not discovered and not explored 2523 * 14 label e as tree-edge 2524 * 15 label w as discovered 2525 * 16 S.push(w) 2526 * 17 continue at 5 2527 * 18 else if vertex w is discovered 2528 * 19 label e as back-edge 2529 * 20 else 2530 * 21 // vertex w is explored 2531 * 22 label e as forward- or cross-edge 2532 * 23 label t as explored 2533 * 24 S.pop() 2534 * 2535 * convention: 2536 * 0x10 - discovered 2537 * 0x11 - discovered and fall-through edge labelled 2538 * 0x12 - discovered and fall-through and branch edges labelled 2539 * 0x20 - explored 2540 */ 2541 2542 enum { 2543 DISCOVERED = 0x10, 2544 EXPLORED = 0x20, 2545 FALLTHROUGH = 1, 2546 BRANCH = 2, 2547 }; 2548 2549 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) 2550 2551 static int *insn_stack; /* stack of insns to process */ 2552 static int cur_stack; /* current stack index */ 2553 static int *insn_state; 2554 2555 /* t, w, e - match pseudo-code above: 2556 * t - index of current instruction 2557 * w - next instruction 2558 * e - edge 2559 */ 2560 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) 2561 { 2562 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) 2563 return 0; 2564 2565 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) 2566 return 0; 2567 2568 if (w < 0 || w >= env->prog->len) { 2569 verbose("jump out of range from insn %d to %d\n", t, w); 2570 return -EINVAL; 2571 } 2572 2573 if (e == BRANCH) 2574 /* mark branch target for state pruning */ 2575 env->explored_states[w] = STATE_LIST_MARK; 2576 2577 if (insn_state[w] == 0) { 2578 /* tree-edge */ 2579 insn_state[t] = DISCOVERED | e; 2580 insn_state[w] = DISCOVERED; 2581 if (cur_stack >= env->prog->len) 2582 return -E2BIG; 2583 insn_stack[cur_stack++] = w; 2584 return 1; 2585 } else if ((insn_state[w] & 0xF0) == DISCOVERED) { 2586 verbose("back-edge from insn %d to %d\n", t, w); 2587 return -EINVAL; 2588 } else if (insn_state[w] == EXPLORED) { 2589 /* forward- or cross-edge */ 2590 insn_state[t] = DISCOVERED | e; 2591 } else { 2592 verbose("insn state internal bug\n"); 2593 return -EFAULT; 2594 } 2595 return 0; 2596 } 2597 2598 /* non-recursive depth-first-search to detect loops in BPF program 2599 * loop == back-edge in directed graph 2600 */ 2601 static int check_cfg(struct bpf_verifier_env *env) 2602 { 2603 struct bpf_insn *insns = env->prog->insnsi; 2604 int insn_cnt = env->prog->len; 2605 int ret = 0; 2606 int i, t; 2607 2608 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2609 if (!insn_state) 2610 return -ENOMEM; 2611 2612 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2613 if (!insn_stack) { 2614 kfree(insn_state); 2615 return -ENOMEM; 2616 } 2617 2618 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ 2619 insn_stack[0] = 0; /* 0 is the first instruction */ 2620 cur_stack = 1; 2621 2622 peek_stack: 2623 if (cur_stack == 0) 2624 goto check_state; 2625 t = insn_stack[cur_stack - 1]; 2626 2627 if (BPF_CLASS(insns[t].code) == BPF_JMP) { 2628 u8 opcode = BPF_OP(insns[t].code); 2629 2630 if (opcode == BPF_EXIT) { 2631 goto mark_explored; 2632 } else if (opcode == BPF_CALL) { 2633 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2634 if (ret == 1) 2635 goto peek_stack; 2636 else if (ret < 0) 2637 goto err_free; 2638 if (t + 1 < insn_cnt) 2639 env->explored_states[t + 1] = STATE_LIST_MARK; 2640 } else if (opcode == BPF_JA) { 2641 if (BPF_SRC(insns[t].code) != BPF_K) { 2642 ret = -EINVAL; 2643 goto err_free; 2644 } 2645 /* unconditional jump with single edge */ 2646 ret = push_insn(t, t + insns[t].off + 1, 2647 FALLTHROUGH, env); 2648 if (ret == 1) 2649 goto peek_stack; 2650 else if (ret < 0) 2651 goto err_free; 2652 /* tell verifier to check for equivalent states 2653 * after every call and jump 2654 */ 2655 if (t + 1 < insn_cnt) 2656 env->explored_states[t + 1] = STATE_LIST_MARK; 2657 } else { 2658 /* conditional jump with two edges */ 2659 env->explored_states[t] = STATE_LIST_MARK; 2660 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2661 if (ret == 1) 2662 goto peek_stack; 2663 else if (ret < 0) 2664 goto err_free; 2665 2666 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); 2667 if (ret == 1) 2668 goto peek_stack; 2669 else if (ret < 0) 2670 goto err_free; 2671 } 2672 } else { 2673 /* all other non-branch instructions with single 2674 * fall-through edge 2675 */ 2676 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2677 if (ret == 1) 2678 goto peek_stack; 2679 else if (ret < 0) 2680 goto err_free; 2681 } 2682 2683 mark_explored: 2684 insn_state[t] = EXPLORED; 2685 if (cur_stack-- <= 0) { 2686 verbose("pop stack internal bug\n"); 2687 ret = -EFAULT; 2688 goto err_free; 2689 } 2690 goto peek_stack; 2691 2692 check_state: 2693 for (i = 0; i < insn_cnt; i++) { 2694 if (insn_state[i] != EXPLORED) { 2695 verbose("unreachable insn %d\n", i); 2696 ret = -EINVAL; 2697 goto err_free; 2698 } 2699 } 2700 ret = 0; /* cfg looks good */ 2701 2702 err_free: 2703 kfree(insn_state); 2704 kfree(insn_stack); 2705 return ret; 2706 } 2707 2708 /* the following conditions reduce the number of explored insns 2709 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet 2710 */ 2711 static bool compare_ptrs_to_packet(struct bpf_verifier_env *env, 2712 struct bpf_reg_state *old, 2713 struct bpf_reg_state *cur) 2714 { 2715 if (old->id != cur->id) 2716 return false; 2717 2718 /* old ptr_to_packet is more conservative, since it allows smaller 2719 * range. Ex: 2720 * old(off=0,r=10) is equal to cur(off=0,r=20), because 2721 * old(off=0,r=10) means that with range=10 the verifier proceeded 2722 * further and found no issues with the program. Now we're in the same 2723 * spot with cur(off=0,r=20), so we're safe too, since anything further 2724 * will only be looking at most 10 bytes after this pointer. 2725 */ 2726 if (old->off == cur->off && old->range < cur->range) 2727 return true; 2728 2729 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) 2730 * since both cannot be used for packet access and safe(old) 2731 * pointer has smaller off that could be used for further 2732 * 'if (ptr > data_end)' check 2733 * Ex: 2734 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean 2735 * that we cannot access the packet. 2736 * The safe range is: 2737 * [ptr, ptr + range - off) 2738 * so whenever off >=range, it means no safe bytes from this pointer. 2739 * When comparing old->off <= cur->off, it means that older code 2740 * went with smaller offset and that offset was later 2741 * used to figure out the safe range after 'if (ptr > data_end)' check 2742 * Say, 'old' state was explored like: 2743 * ... R3(off=0, r=0) 2744 * R4 = R3 + 20 2745 * ... now R4(off=20,r=0) <-- here 2746 * if (R4 > data_end) 2747 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. 2748 * ... the code further went all the way to bpf_exit. 2749 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). 2750 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier 2751 * goes further, such cur_R4 will give larger safe packet range after 2752 * 'if (R4 > data_end)' and all further insn were already good with r=20, 2753 * so they will be good with r=30 and we can prune the search. 2754 */ 2755 if (!env->strict_alignment && old->off <= cur->off && 2756 old->off >= old->range && cur->off >= cur->range) 2757 return true; 2758 2759 return false; 2760 } 2761 2762 /* compare two verifier states 2763 * 2764 * all states stored in state_list are known to be valid, since 2765 * verifier reached 'bpf_exit' instruction through them 2766 * 2767 * this function is called when verifier exploring different branches of 2768 * execution popped from the state stack. If it sees an old state that has 2769 * more strict register state and more strict stack state then this execution 2770 * branch doesn't need to be explored further, since verifier already 2771 * concluded that more strict state leads to valid finish. 2772 * 2773 * Therefore two states are equivalent if register state is more conservative 2774 * and explored stack state is more conservative than the current one. 2775 * Example: 2776 * explored current 2777 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) 2778 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) 2779 * 2780 * In other words if current stack state (one being explored) has more 2781 * valid slots than old one that already passed validation, it means 2782 * the verifier can stop exploring and conclude that current state is valid too 2783 * 2784 * Similarly with registers. If explored state has register type as invalid 2785 * whereas register type in current state is meaningful, it means that 2786 * the current state will reach 'bpf_exit' instruction safely 2787 */ 2788 static bool states_equal(struct bpf_verifier_env *env, 2789 struct bpf_verifier_state *old, 2790 struct bpf_verifier_state *cur) 2791 { 2792 bool varlen_map_access = env->varlen_map_value_access; 2793 struct bpf_reg_state *rold, *rcur; 2794 int i; 2795 2796 for (i = 0; i < MAX_BPF_REG; i++) { 2797 rold = &old->regs[i]; 2798 rcur = &cur->regs[i]; 2799 2800 if (memcmp(rold, rcur, sizeof(*rold)) == 0) 2801 continue; 2802 2803 /* If the ranges were not the same, but everything else was and 2804 * we didn't do a variable access into a map then we are a-ok. 2805 */ 2806 if (!varlen_map_access && 2807 memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0) 2808 continue; 2809 2810 /* If we didn't map access then again we don't care about the 2811 * mismatched range values and it's ok if our old type was 2812 * UNKNOWN and we didn't go to a NOT_INIT'ed reg. 2813 */ 2814 if (rold->type == NOT_INIT || 2815 (!varlen_map_access && rold->type == UNKNOWN_VALUE && 2816 rcur->type != NOT_INIT)) 2817 continue; 2818 2819 /* Don't care about the reg->id in this case. */ 2820 if (rold->type == PTR_TO_MAP_VALUE_OR_NULL && 2821 rcur->type == PTR_TO_MAP_VALUE_OR_NULL && 2822 rold->map_ptr == rcur->map_ptr) 2823 continue; 2824 2825 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && 2826 compare_ptrs_to_packet(env, rold, rcur)) 2827 continue; 2828 2829 return false; 2830 } 2831 2832 for (i = 0; i < MAX_BPF_STACK; i++) { 2833 if (old->stack_slot_type[i] == STACK_INVALID) 2834 continue; 2835 if (old->stack_slot_type[i] != cur->stack_slot_type[i]) 2836 /* Ex: old explored (safe) state has STACK_SPILL in 2837 * this stack slot, but current has has STACK_MISC -> 2838 * this verifier states are not equivalent, 2839 * return false to continue verification of this path 2840 */ 2841 return false; 2842 if (i % BPF_REG_SIZE) 2843 continue; 2844 if (old->stack_slot_type[i] != STACK_SPILL) 2845 continue; 2846 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], 2847 &cur->spilled_regs[i / BPF_REG_SIZE], 2848 sizeof(old->spilled_regs[0]))) 2849 /* when explored and current stack slot types are 2850 * the same, check that stored pointers types 2851 * are the same as well. 2852 * Ex: explored safe path could have stored 2853 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8} 2854 * but current path has stored: 2855 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16} 2856 * such verifier states are not equivalent. 2857 * return false to continue verification of this path 2858 */ 2859 return false; 2860 else 2861 continue; 2862 } 2863 return true; 2864 } 2865 2866 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) 2867 { 2868 struct bpf_verifier_state_list *new_sl; 2869 struct bpf_verifier_state_list *sl; 2870 2871 sl = env->explored_states[insn_idx]; 2872 if (!sl) 2873 /* this 'insn_idx' instruction wasn't marked, so we will not 2874 * be doing state search here 2875 */ 2876 return 0; 2877 2878 while (sl != STATE_LIST_MARK) { 2879 if (states_equal(env, &sl->state, &env->cur_state)) 2880 /* reached equivalent register/stack state, 2881 * prune the search 2882 */ 2883 return 1; 2884 sl = sl->next; 2885 } 2886 2887 /* there were no equivalent states, remember current one. 2888 * technically the current state is not proven to be safe yet, 2889 * but it will either reach bpf_exit (which means it's safe) or 2890 * it will be rejected. Since there are no loops, we won't be 2891 * seeing this 'insn_idx' instruction again on the way to bpf_exit 2892 */ 2893 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); 2894 if (!new_sl) 2895 return -ENOMEM; 2896 2897 /* add new state to the head of linked list */ 2898 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); 2899 new_sl->next = env->explored_states[insn_idx]; 2900 env->explored_states[insn_idx] = new_sl; 2901 return 0; 2902 } 2903 2904 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, 2905 int insn_idx, int prev_insn_idx) 2906 { 2907 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) 2908 return 0; 2909 2910 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); 2911 } 2912 2913 static int do_check(struct bpf_verifier_env *env) 2914 { 2915 struct bpf_verifier_state *state = &env->cur_state; 2916 struct bpf_insn *insns = env->prog->insnsi; 2917 struct bpf_reg_state *regs = state->regs; 2918 int insn_cnt = env->prog->len; 2919 int insn_idx, prev_insn_idx = 0; 2920 int insn_processed = 0; 2921 bool do_print_state = false; 2922 2923 init_reg_state(regs); 2924 insn_idx = 0; 2925 env->varlen_map_value_access = false; 2926 for (;;) { 2927 struct bpf_insn *insn; 2928 u8 class; 2929 int err; 2930 2931 if (insn_idx >= insn_cnt) { 2932 verbose("invalid insn idx %d insn_cnt %d\n", 2933 insn_idx, insn_cnt); 2934 return -EFAULT; 2935 } 2936 2937 insn = &insns[insn_idx]; 2938 class = BPF_CLASS(insn->code); 2939 2940 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { 2941 verbose("BPF program is too large. Processed %d insn\n", 2942 insn_processed); 2943 return -E2BIG; 2944 } 2945 2946 err = is_state_visited(env, insn_idx); 2947 if (err < 0) 2948 return err; 2949 if (err == 1) { 2950 /* found equivalent state, can prune the search */ 2951 if (log_level) { 2952 if (do_print_state) 2953 verbose("\nfrom %d to %d: safe\n", 2954 prev_insn_idx, insn_idx); 2955 else 2956 verbose("%d: safe\n", insn_idx); 2957 } 2958 goto process_bpf_exit; 2959 } 2960 2961 if (need_resched()) 2962 cond_resched(); 2963 2964 if (log_level > 1 || (log_level && do_print_state)) { 2965 if (log_level > 1) 2966 verbose("%d:", insn_idx); 2967 else 2968 verbose("\nfrom %d to %d:", 2969 prev_insn_idx, insn_idx); 2970 print_verifier_state(&env->cur_state); 2971 do_print_state = false; 2972 } 2973 2974 if (log_level) { 2975 verbose("%d: ", insn_idx); 2976 print_bpf_insn(env, insn); 2977 } 2978 2979 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); 2980 if (err) 2981 return err; 2982 2983 if (class == BPF_ALU || class == BPF_ALU64) { 2984 err = check_alu_op(env, insn); 2985 if (err) 2986 return err; 2987 2988 } else if (class == BPF_LDX) { 2989 enum bpf_reg_type *prev_src_type, src_reg_type; 2990 2991 /* check for reserved fields is already done */ 2992 2993 /* check src operand */ 2994 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2995 if (err) 2996 return err; 2997 2998 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 2999 if (err) 3000 return err; 3001 3002 src_reg_type = regs[insn->src_reg].type; 3003 3004 /* check that memory (src_reg + off) is readable, 3005 * the state of dst_reg will be updated by this func 3006 */ 3007 err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, 3008 BPF_SIZE(insn->code), BPF_READ, 3009 insn->dst_reg); 3010 if (err) 3011 return err; 3012 3013 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; 3014 3015 if (*prev_src_type == NOT_INIT) { 3016 /* saw a valid insn 3017 * dst_reg = *(u32 *)(src_reg + off) 3018 * save type to validate intersecting paths 3019 */ 3020 *prev_src_type = src_reg_type; 3021 3022 } else if (src_reg_type != *prev_src_type && 3023 (src_reg_type == PTR_TO_CTX || 3024 *prev_src_type == PTR_TO_CTX)) { 3025 /* ABuser program is trying to use the same insn 3026 * dst_reg = *(u32*) (src_reg + off) 3027 * with different pointer types: 3028 * src_reg == ctx in one branch and 3029 * src_reg == stack|map in some other branch. 3030 * Reject it. 3031 */ 3032 verbose("same insn cannot be used with different pointers\n"); 3033 return -EINVAL; 3034 } 3035 3036 } else if (class == BPF_STX) { 3037 enum bpf_reg_type *prev_dst_type, dst_reg_type; 3038 3039 if (BPF_MODE(insn->code) == BPF_XADD) { 3040 err = check_xadd(env, insn_idx, insn); 3041 if (err) 3042 return err; 3043 insn_idx++; 3044 continue; 3045 } 3046 3047 /* check src1 operand */ 3048 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 3049 if (err) 3050 return err; 3051 /* check src2 operand */ 3052 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 3053 if (err) 3054 return err; 3055 3056 dst_reg_type = regs[insn->dst_reg].type; 3057 3058 /* check that memory (dst_reg + off) is writeable */ 3059 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 3060 BPF_SIZE(insn->code), BPF_WRITE, 3061 insn->src_reg); 3062 if (err) 3063 return err; 3064 3065 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; 3066 3067 if (*prev_dst_type == NOT_INIT) { 3068 *prev_dst_type = dst_reg_type; 3069 } else if (dst_reg_type != *prev_dst_type && 3070 (dst_reg_type == PTR_TO_CTX || 3071 *prev_dst_type == PTR_TO_CTX)) { 3072 verbose("same insn cannot be used with different pointers\n"); 3073 return -EINVAL; 3074 } 3075 3076 } else if (class == BPF_ST) { 3077 if (BPF_MODE(insn->code) != BPF_MEM || 3078 insn->src_reg != BPF_REG_0) { 3079 verbose("BPF_ST uses reserved fields\n"); 3080 return -EINVAL; 3081 } 3082 /* check src operand */ 3083 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 3084 if (err) 3085 return err; 3086 3087 /* check that memory (dst_reg + off) is writeable */ 3088 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 3089 BPF_SIZE(insn->code), BPF_WRITE, 3090 -1); 3091 if (err) 3092 return err; 3093 3094 } else if (class == BPF_JMP) { 3095 u8 opcode = BPF_OP(insn->code); 3096 3097 if (opcode == BPF_CALL) { 3098 if (BPF_SRC(insn->code) != BPF_K || 3099 insn->off != 0 || 3100 insn->src_reg != BPF_REG_0 || 3101 insn->dst_reg != BPF_REG_0) { 3102 verbose("BPF_CALL uses reserved fields\n"); 3103 return -EINVAL; 3104 } 3105 3106 err = check_call(env, insn->imm, insn_idx); 3107 if (err) 3108 return err; 3109 3110 } else if (opcode == BPF_JA) { 3111 if (BPF_SRC(insn->code) != BPF_K || 3112 insn->imm != 0 || 3113 insn->src_reg != BPF_REG_0 || 3114 insn->dst_reg != BPF_REG_0) { 3115 verbose("BPF_JA uses reserved fields\n"); 3116 return -EINVAL; 3117 } 3118 3119 insn_idx += insn->off + 1; 3120 continue; 3121 3122 } else if (opcode == BPF_EXIT) { 3123 if (BPF_SRC(insn->code) != BPF_K || 3124 insn->imm != 0 || 3125 insn->src_reg != BPF_REG_0 || 3126 insn->dst_reg != BPF_REG_0) { 3127 verbose("BPF_EXIT uses reserved fields\n"); 3128 return -EINVAL; 3129 } 3130 3131 /* eBPF calling convetion is such that R0 is used 3132 * to return the value from eBPF program. 3133 * Make sure that it's readable at this time 3134 * of bpf_exit, which means that program wrote 3135 * something into it earlier 3136 */ 3137 err = check_reg_arg(regs, BPF_REG_0, SRC_OP); 3138 if (err) 3139 return err; 3140 3141 if (is_pointer_value(env, BPF_REG_0)) { 3142 verbose("R0 leaks addr as return value\n"); 3143 return -EACCES; 3144 } 3145 3146 process_bpf_exit: 3147 insn_idx = pop_stack(env, &prev_insn_idx); 3148 if (insn_idx < 0) { 3149 break; 3150 } else { 3151 do_print_state = true; 3152 continue; 3153 } 3154 } else { 3155 err = check_cond_jmp_op(env, insn, &insn_idx); 3156 if (err) 3157 return err; 3158 } 3159 } else if (class == BPF_LD) { 3160 u8 mode = BPF_MODE(insn->code); 3161 3162 if (mode == BPF_ABS || mode == BPF_IND) { 3163 err = check_ld_abs(env, insn); 3164 if (err) 3165 return err; 3166 3167 } else if (mode == BPF_IMM) { 3168 err = check_ld_imm(env, insn); 3169 if (err) 3170 return err; 3171 3172 insn_idx++; 3173 } else { 3174 verbose("invalid BPF_LD mode\n"); 3175 return -EINVAL; 3176 } 3177 reset_reg_range_values(regs, insn->dst_reg); 3178 } else { 3179 verbose("unknown insn class %d\n", class); 3180 return -EINVAL; 3181 } 3182 3183 insn_idx++; 3184 } 3185 3186 verbose("processed %d insns, stack depth %d\n", 3187 insn_processed, env->prog->aux->stack_depth); 3188 return 0; 3189 } 3190 3191 static int check_map_prealloc(struct bpf_map *map) 3192 { 3193 return (map->map_type != BPF_MAP_TYPE_HASH && 3194 map->map_type != BPF_MAP_TYPE_PERCPU_HASH && 3195 map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || 3196 !(map->map_flags & BPF_F_NO_PREALLOC); 3197 } 3198 3199 static int check_map_prog_compatibility(struct bpf_map *map, 3200 struct bpf_prog *prog) 3201 3202 { 3203 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use 3204 * preallocated hash maps, since doing memory allocation 3205 * in overflow_handler can crash depending on where nmi got 3206 * triggered. 3207 */ 3208 if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { 3209 if (!check_map_prealloc(map)) { 3210 verbose("perf_event programs can only use preallocated hash map\n"); 3211 return -EINVAL; 3212 } 3213 if (map->inner_map_meta && 3214 !check_map_prealloc(map->inner_map_meta)) { 3215 verbose("perf_event programs can only use preallocated inner hash map\n"); 3216 return -EINVAL; 3217 } 3218 } 3219 return 0; 3220 } 3221 3222 /* look for pseudo eBPF instructions that access map FDs and 3223 * replace them with actual map pointers 3224 */ 3225 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) 3226 { 3227 struct bpf_insn *insn = env->prog->insnsi; 3228 int insn_cnt = env->prog->len; 3229 int i, j, err; 3230 3231 err = bpf_prog_calc_tag(env->prog); 3232 if (err) 3233 return err; 3234 3235 for (i = 0; i < insn_cnt; i++, insn++) { 3236 if (BPF_CLASS(insn->code) == BPF_LDX && 3237 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { 3238 verbose("BPF_LDX uses reserved fields\n"); 3239 return -EINVAL; 3240 } 3241 3242 if (BPF_CLASS(insn->code) == BPF_STX && 3243 ((BPF_MODE(insn->code) != BPF_MEM && 3244 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { 3245 verbose("BPF_STX uses reserved fields\n"); 3246 return -EINVAL; 3247 } 3248 3249 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { 3250 struct bpf_map *map; 3251 struct fd f; 3252 3253 if (i == insn_cnt - 1 || insn[1].code != 0 || 3254 insn[1].dst_reg != 0 || insn[1].src_reg != 0 || 3255 insn[1].off != 0) { 3256 verbose("invalid bpf_ld_imm64 insn\n"); 3257 return -EINVAL; 3258 } 3259 3260 if (insn->src_reg == 0) 3261 /* valid generic load 64-bit imm */ 3262 goto next_insn; 3263 3264 if (insn->src_reg != BPF_PSEUDO_MAP_FD) { 3265 verbose("unrecognized bpf_ld_imm64 insn\n"); 3266 return -EINVAL; 3267 } 3268 3269 f = fdget(insn->imm); 3270 map = __bpf_map_get(f); 3271 if (IS_ERR(map)) { 3272 verbose("fd %d is not pointing to valid bpf_map\n", 3273 insn->imm); 3274 return PTR_ERR(map); 3275 } 3276 3277 err = check_map_prog_compatibility(map, env->prog); 3278 if (err) { 3279 fdput(f); 3280 return err; 3281 } 3282 3283 /* store map pointer inside BPF_LD_IMM64 instruction */ 3284 insn[0].imm = (u32) (unsigned long) map; 3285 insn[1].imm = ((u64) (unsigned long) map) >> 32; 3286 3287 /* check whether we recorded this map already */ 3288 for (j = 0; j < env->used_map_cnt; j++) 3289 if (env->used_maps[j] == map) { 3290 fdput(f); 3291 goto next_insn; 3292 } 3293 3294 if (env->used_map_cnt >= MAX_USED_MAPS) { 3295 fdput(f); 3296 return -E2BIG; 3297 } 3298 3299 /* hold the map. If the program is rejected by verifier, 3300 * the map will be released by release_maps() or it 3301 * will be used by the valid program until it's unloaded 3302 * and all maps are released in free_bpf_prog_info() 3303 */ 3304 map = bpf_map_inc(map, false); 3305 if (IS_ERR(map)) { 3306 fdput(f); 3307 return PTR_ERR(map); 3308 } 3309 env->used_maps[env->used_map_cnt++] = map; 3310 3311 fdput(f); 3312 next_insn: 3313 insn++; 3314 i++; 3315 } 3316 } 3317 3318 /* now all pseudo BPF_LD_IMM64 instructions load valid 3319 * 'struct bpf_map *' into a register instead of user map_fd. 3320 * These pointers will be used later by verifier to validate map access. 3321 */ 3322 return 0; 3323 } 3324 3325 /* drop refcnt of maps used by the rejected program */ 3326 static void release_maps(struct bpf_verifier_env *env) 3327 { 3328 int i; 3329 3330 for (i = 0; i < env->used_map_cnt; i++) 3331 bpf_map_put(env->used_maps[i]); 3332 } 3333 3334 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ 3335 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) 3336 { 3337 struct bpf_insn *insn = env->prog->insnsi; 3338 int insn_cnt = env->prog->len; 3339 int i; 3340 3341 for (i = 0; i < insn_cnt; i++, insn++) 3342 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) 3343 insn->src_reg = 0; 3344 } 3345 3346 /* single env->prog->insni[off] instruction was replaced with the range 3347 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying 3348 * [0, off) and [off, end) to new locations, so the patched range stays zero 3349 */ 3350 static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, 3351 u32 off, u32 cnt) 3352 { 3353 struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; 3354 3355 if (cnt == 1) 3356 return 0; 3357 new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); 3358 if (!new_data) 3359 return -ENOMEM; 3360 memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); 3361 memcpy(new_data + off + cnt - 1, old_data + off, 3362 sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); 3363 env->insn_aux_data = new_data; 3364 vfree(old_data); 3365 return 0; 3366 } 3367 3368 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, 3369 const struct bpf_insn *patch, u32 len) 3370 { 3371 struct bpf_prog *new_prog; 3372 3373 new_prog = bpf_patch_insn_single(env->prog, off, patch, len); 3374 if (!new_prog) 3375 return NULL; 3376 if (adjust_insn_aux_data(env, new_prog->len, off, len)) 3377 return NULL; 3378 return new_prog; 3379 } 3380 3381 /* convert load instructions that access fields of 'struct __sk_buff' 3382 * into sequence of instructions that access fields of 'struct sk_buff' 3383 */ 3384 static int convert_ctx_accesses(struct bpf_verifier_env *env) 3385 { 3386 const struct bpf_verifier_ops *ops = env->prog->aux->ops; 3387 const int insn_cnt = env->prog->len; 3388 struct bpf_insn insn_buf[16], *insn; 3389 struct bpf_prog *new_prog; 3390 enum bpf_access_type type; 3391 int i, cnt, off, size, ctx_field_size, is_narrower_load, delta = 0; 3392 3393 if (ops->gen_prologue) { 3394 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, 3395 env->prog); 3396 if (cnt >= ARRAY_SIZE(insn_buf)) { 3397 verbose("bpf verifier is misconfigured\n"); 3398 return -EINVAL; 3399 } else if (cnt) { 3400 new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); 3401 if (!new_prog) 3402 return -ENOMEM; 3403 3404 env->prog = new_prog; 3405 delta += cnt - 1; 3406 } 3407 } 3408 3409 if (!ops->convert_ctx_access) 3410 return 0; 3411 3412 insn = env->prog->insnsi + delta; 3413 3414 for (i = 0; i < insn_cnt; i++, insn++) { 3415 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || 3416 insn->code == (BPF_LDX | BPF_MEM | BPF_H) || 3417 insn->code == (BPF_LDX | BPF_MEM | BPF_W) || 3418 insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) 3419 type = BPF_READ; 3420 else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || 3421 insn->code == (BPF_STX | BPF_MEM | BPF_H) || 3422 insn->code == (BPF_STX | BPF_MEM | BPF_W) || 3423 insn->code == (BPF_STX | BPF_MEM | BPF_DW)) 3424 type = BPF_WRITE; 3425 else 3426 continue; 3427 3428 if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) 3429 continue; 3430 3431 off = insn->off; 3432 size = bpf_size_to_bytes(BPF_SIZE(insn->code)); 3433 ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; 3434 is_narrower_load = (type == BPF_READ && size < ctx_field_size); 3435 3436 /* If the read access is a narrower load of the field, 3437 * convert to a 4/8-byte load, to minimum program type specific 3438 * convert_ctx_access changes. If conversion is successful, 3439 * we will apply proper mask to the result. 3440 */ 3441 if (is_narrower_load) { 3442 int size_code = BPF_H; 3443 3444 if (ctx_field_size == 4) 3445 size_code = BPF_W; 3446 else if (ctx_field_size == 8) 3447 size_code = BPF_DW; 3448 insn->off = off & ~(ctx_field_size - 1); 3449 insn->code = BPF_LDX | BPF_MEM | size_code; 3450 } 3451 cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog); 3452 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { 3453 verbose("bpf verifier is misconfigured\n"); 3454 return -EINVAL; 3455 } 3456 if (is_narrower_load) { 3457 if (ctx_field_size <= 4) 3458 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, 3459 (1 << size * 8) - 1); 3460 else 3461 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, 3462 (1 << size * 8) - 1); 3463 } 3464 3465 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); 3466 if (!new_prog) 3467 return -ENOMEM; 3468 3469 delta += cnt - 1; 3470 3471 /* keep walking new program and skip insns we just inserted */ 3472 env->prog = new_prog; 3473 insn = new_prog->insnsi + i + delta; 3474 } 3475 3476 return 0; 3477 } 3478 3479 /* fixup insn->imm field of bpf_call instructions 3480 * and inline eligible helpers as explicit sequence of BPF instructions 3481 * 3482 * this function is called after eBPF program passed verification 3483 */ 3484 static int fixup_bpf_calls(struct bpf_verifier_env *env) 3485 { 3486 struct bpf_prog *prog = env->prog; 3487 struct bpf_insn *insn = prog->insnsi; 3488 const struct bpf_func_proto *fn; 3489 const int insn_cnt = prog->len; 3490 struct bpf_insn insn_buf[16]; 3491 struct bpf_prog *new_prog; 3492 struct bpf_map *map_ptr; 3493 int i, cnt, delta = 0; 3494 3495 for (i = 0; i < insn_cnt; i++, insn++) { 3496 if (insn->code != (BPF_JMP | BPF_CALL)) 3497 continue; 3498 3499 if (insn->imm == BPF_FUNC_get_route_realm) 3500 prog->dst_needed = 1; 3501 if (insn->imm == BPF_FUNC_get_prandom_u32) 3502 bpf_user_rnd_init_once(); 3503 if (insn->imm == BPF_FUNC_tail_call) { 3504 /* If we tail call into other programs, we 3505 * cannot make any assumptions since they can 3506 * be replaced dynamically during runtime in 3507 * the program array. 3508 */ 3509 prog->cb_access = 1; 3510 env->prog->aux->stack_depth = MAX_BPF_STACK; 3511 3512 /* mark bpf_tail_call as different opcode to avoid 3513 * conditional branch in the interpeter for every normal 3514 * call and to prevent accidental JITing by JIT compiler 3515 * that doesn't support bpf_tail_call yet 3516 */ 3517 insn->imm = 0; 3518 insn->code = BPF_JMP | BPF_TAIL_CALL; 3519 continue; 3520 } 3521 3522 if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) { 3523 map_ptr = env->insn_aux_data[i + delta].map_ptr; 3524 if (map_ptr == BPF_MAP_PTR_POISON || 3525 !map_ptr->ops->map_gen_lookup) 3526 goto patch_call_imm; 3527 3528 cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); 3529 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { 3530 verbose("bpf verifier is misconfigured\n"); 3531 return -EINVAL; 3532 } 3533 3534 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 3535 cnt); 3536 if (!new_prog) 3537 return -ENOMEM; 3538 3539 delta += cnt - 1; 3540 3541 /* keep walking new program and skip insns we just inserted */ 3542 env->prog = prog = new_prog; 3543 insn = new_prog->insnsi + i + delta; 3544 continue; 3545 } 3546 3547 patch_call_imm: 3548 fn = prog->aux->ops->get_func_proto(insn->imm); 3549 /* all functions that have prototype and verifier allowed 3550 * programs to call them, must be real in-kernel functions 3551 */ 3552 if (!fn->func) { 3553 verbose("kernel subsystem misconfigured func %s#%d\n", 3554 func_id_name(insn->imm), insn->imm); 3555 return -EFAULT; 3556 } 3557 insn->imm = fn->func - __bpf_call_base; 3558 } 3559 3560 return 0; 3561 } 3562 3563 static void free_states(struct bpf_verifier_env *env) 3564 { 3565 struct bpf_verifier_state_list *sl, *sln; 3566 int i; 3567 3568 if (!env->explored_states) 3569 return; 3570 3571 for (i = 0; i < env->prog->len; i++) { 3572 sl = env->explored_states[i]; 3573 3574 if (sl) 3575 while (sl != STATE_LIST_MARK) { 3576 sln = sl->next; 3577 kfree(sl); 3578 sl = sln; 3579 } 3580 } 3581 3582 kfree(env->explored_states); 3583 } 3584 3585 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) 3586 { 3587 char __user *log_ubuf = NULL; 3588 struct bpf_verifier_env *env; 3589 int ret = -EINVAL; 3590 3591 /* 'struct bpf_verifier_env' can be global, but since it's not small, 3592 * allocate/free it every time bpf_check() is called 3593 */ 3594 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3595 if (!env) 3596 return -ENOMEM; 3597 3598 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3599 (*prog)->len); 3600 ret = -ENOMEM; 3601 if (!env->insn_aux_data) 3602 goto err_free_env; 3603 env->prog = *prog; 3604 3605 /* grab the mutex to protect few globals used by verifier */ 3606 mutex_lock(&bpf_verifier_lock); 3607 3608 if (attr->log_level || attr->log_buf || attr->log_size) { 3609 /* user requested verbose verifier output 3610 * and supplied buffer to store the verification trace 3611 */ 3612 log_level = attr->log_level; 3613 log_ubuf = (char __user *) (unsigned long) attr->log_buf; 3614 log_size = attr->log_size; 3615 log_len = 0; 3616 3617 ret = -EINVAL; 3618 /* log_* values have to be sane */ 3619 if (log_size < 128 || log_size > UINT_MAX >> 8 || 3620 log_level == 0 || log_ubuf == NULL) 3621 goto err_unlock; 3622 3623 ret = -ENOMEM; 3624 log_buf = vmalloc(log_size); 3625 if (!log_buf) 3626 goto err_unlock; 3627 } else { 3628 log_level = 0; 3629 } 3630 3631 env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); 3632 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) 3633 env->strict_alignment = true; 3634 3635 ret = replace_map_fd_with_map_ptr(env); 3636 if (ret < 0) 3637 goto skip_full_check; 3638 3639 env->explored_states = kcalloc(env->prog->len, 3640 sizeof(struct bpf_verifier_state_list *), 3641 GFP_USER); 3642 ret = -ENOMEM; 3643 if (!env->explored_states) 3644 goto skip_full_check; 3645 3646 ret = check_cfg(env); 3647 if (ret < 0) 3648 goto skip_full_check; 3649 3650 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3651 3652 ret = do_check(env); 3653 3654 skip_full_check: 3655 while (pop_stack(env, NULL) >= 0); 3656 free_states(env); 3657 3658 if (ret == 0) 3659 /* program is valid, convert *(u32*)(ctx + off) accesses */ 3660 ret = convert_ctx_accesses(env); 3661 3662 if (ret == 0) 3663 ret = fixup_bpf_calls(env); 3664 3665 if (log_level && log_len >= log_size - 1) { 3666 BUG_ON(log_len >= log_size); 3667 /* verifier log exceeded user supplied buffer */ 3668 ret = -ENOSPC; 3669 /* fall through to return what was recorded */ 3670 } 3671 3672 /* copy verifier log back to user space including trailing zero */ 3673 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { 3674 ret = -EFAULT; 3675 goto free_log_buf; 3676 } 3677 3678 if (ret == 0 && env->used_map_cnt) { 3679 /* if program passed verifier, update used_maps in bpf_prog_info */ 3680 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, 3681 sizeof(env->used_maps[0]), 3682 GFP_KERNEL); 3683 3684 if (!env->prog->aux->used_maps) { 3685 ret = -ENOMEM; 3686 goto free_log_buf; 3687 } 3688 3689 memcpy(env->prog->aux->used_maps, env->used_maps, 3690 sizeof(env->used_maps[0]) * env->used_map_cnt); 3691 env->prog->aux->used_map_cnt = env->used_map_cnt; 3692 3693 /* program is valid. Convert pseudo bpf_ld_imm64 into generic 3694 * bpf_ld_imm64 instructions 3695 */ 3696 convert_pseudo_ld_imm64(env); 3697 } 3698 3699 free_log_buf: 3700 if (log_level) 3701 vfree(log_buf); 3702 if (!env->prog->aux->used_maps) 3703 /* if we didn't copy map pointers into bpf_prog_info, release 3704 * them now. Otherwise free_bpf_prog_info() will release them. 3705 */ 3706 release_maps(env); 3707 *prog = env->prog; 3708 err_unlock: 3709 mutex_unlock(&bpf_verifier_lock); 3710 vfree(env->insn_aux_data); 3711 err_free_env: 3712 kfree(env); 3713 return ret; 3714 } 3715 3716 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, 3717 void *priv) 3718 { 3719 struct bpf_verifier_env *env; 3720 int ret; 3721 3722 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3723 if (!env) 3724 return -ENOMEM; 3725 3726 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3727 prog->len); 3728 ret = -ENOMEM; 3729 if (!env->insn_aux_data) 3730 goto err_free_env; 3731 env->prog = prog; 3732 env->analyzer_ops = ops; 3733 env->analyzer_priv = priv; 3734 3735 /* grab the mutex to protect few globals used by verifier */ 3736 mutex_lock(&bpf_verifier_lock); 3737 3738 log_level = 0; 3739 3740 env->strict_alignment = false; 3741 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) 3742 env->strict_alignment = true; 3743 3744 env->explored_states = kcalloc(env->prog->len, 3745 sizeof(struct bpf_verifier_state_list *), 3746 GFP_KERNEL); 3747 ret = -ENOMEM; 3748 if (!env->explored_states) 3749 goto skip_full_check; 3750 3751 ret = check_cfg(env); 3752 if (ret < 0) 3753 goto skip_full_check; 3754 3755 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3756 3757 ret = do_check(env); 3758 3759 skip_full_check: 3760 while (pop_stack(env, NULL) >= 0); 3761 free_states(env); 3762 3763 mutex_unlock(&bpf_verifier_lock); 3764 vfree(env->insn_aux_data); 3765 err_free_env: 3766 kfree(env); 3767 return ret; 3768 } 3769 EXPORT_SYMBOL_GPL(bpf_analyzer); 3770