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 23 /* bpf_check() is a static code analyzer that walks eBPF program 24 * instruction by instruction and updates register/stack state. 25 * All paths of conditional branches are analyzed until 'bpf_exit' insn. 26 * 27 * The first pass is depth-first-search to check that the program is a DAG. 28 * It rejects the following programs: 29 * - larger than BPF_MAXINSNS insns 30 * - if loop is present (detected via back-edge) 31 * - unreachable insns exist (shouldn't be a forest. program = one function) 32 * - out of bounds or malformed jumps 33 * The second pass is all possible path descent from the 1st insn. 34 * Since it's analyzing all pathes through the program, the length of the 35 * analysis is limited to 32k insn, which may be hit even if total number of 36 * insn is less then 4K, but there are too many branches that change stack/regs. 37 * Number of 'branches to be analyzed' is limited to 1k 38 * 39 * On entry to each instruction, each register has a type, and the instruction 40 * changes the types of the registers depending on instruction semantics. 41 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is 42 * copied to R1. 43 * 44 * All registers are 64-bit. 45 * R0 - return register 46 * R1-R5 argument passing registers 47 * R6-R9 callee saved registers 48 * R10 - frame pointer read-only 49 * 50 * At the start of BPF program the register R1 contains a pointer to bpf_context 51 * and has type PTR_TO_CTX. 52 * 53 * Verifier tracks arithmetic operations on pointers in case: 54 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), 55 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), 56 * 1st insn copies R10 (which has FRAME_PTR) type into R1 57 * and 2nd arithmetic instruction is pattern matched to recognize 58 * that it wants to construct a pointer to some element within stack. 59 * So after 2nd insn, the register R1 has type PTR_TO_STACK 60 * (and -20 constant is saved for further stack bounds checking). 61 * Meaning that this reg is a pointer to stack plus known immediate constant. 62 * 63 * Most of the time the registers have UNKNOWN_VALUE type, which 64 * means the register has some value, but it's not a valid pointer. 65 * (like pointer plus pointer becomes UNKNOWN_VALUE type) 66 * 67 * When verifier sees load or store instructions the type of base register 68 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer 69 * types recognized by check_mem_access() function. 70 * 71 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' 72 * and the range of [ptr, ptr + map's value_size) is accessible. 73 * 74 * registers used to pass values to function calls are checked against 75 * function argument constraints. 76 * 77 * ARG_PTR_TO_MAP_KEY is one of such argument constraints. 78 * It means that the register type passed to this function must be 79 * PTR_TO_STACK and it will be used inside the function as 80 * 'pointer to map element key' 81 * 82 * For example the argument constraints for bpf_map_lookup_elem(): 83 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 84 * .arg1_type = ARG_CONST_MAP_PTR, 85 * .arg2_type = ARG_PTR_TO_MAP_KEY, 86 * 87 * ret_type says that this function returns 'pointer to map elem value or null' 88 * function expects 1st argument to be a const pointer to 'struct bpf_map' and 89 * 2nd argument should be a pointer to stack, which will be used inside 90 * the helper function as a pointer to map element key. 91 * 92 * On the kernel side the helper function looks like: 93 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 94 * { 95 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 96 * void *key = (void *) (unsigned long) r2; 97 * void *value; 98 * 99 * here kernel can access 'key' and 'map' pointers safely, knowing that 100 * [key, key + map->key_size) bytes are valid and were initialized on 101 * the stack of eBPF program. 102 * } 103 * 104 * Corresponding eBPF program may look like: 105 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR 106 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK 107 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP 108 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), 109 * here verifier looks at prototype of map_lookup_elem() and sees: 110 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, 111 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes 112 * 113 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, 114 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits 115 * and were initialized prior to this call. 116 * If it's ok, then verifier allows this BPF_CALL insn and looks at 117 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets 118 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function 119 * returns ether pointer to map value or NULL. 120 * 121 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' 122 * insn, the register holding that pointer in the true branch changes state to 123 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false 124 * branch. See check_cond_jmp_op(). 125 * 126 * After the call R0 is set to return type of the function and registers R1-R5 127 * are set to NOT_INIT to indicate that they are no longer readable. 128 */ 129 130 /* verifier_state + insn_idx are pushed to stack when branch is encountered */ 131 struct bpf_verifier_stack_elem { 132 /* verifer state is 'st' 133 * before processing instruction 'insn_idx' 134 * and after processing instruction 'prev_insn_idx' 135 */ 136 struct bpf_verifier_state st; 137 int insn_idx; 138 int prev_insn_idx; 139 struct bpf_verifier_stack_elem *next; 140 }; 141 142 #define BPF_COMPLEXITY_LIMIT_INSNS 65536 143 #define BPF_COMPLEXITY_LIMIT_STACK 1024 144 145 struct bpf_call_arg_meta { 146 struct bpf_map *map_ptr; 147 bool raw_mode; 148 bool pkt_access; 149 int regno; 150 int access_size; 151 }; 152 153 /* verbose verifier prints what it's seeing 154 * bpf_check() is called under lock, so no race to access these global vars 155 */ 156 static u32 log_level, log_size, log_len; 157 static char *log_buf; 158 159 static DEFINE_MUTEX(bpf_verifier_lock); 160 161 /* log_level controls verbosity level of eBPF verifier. 162 * verbose() is used to dump the verification trace to the log, so the user 163 * can figure out what's wrong with the program 164 */ 165 static __printf(1, 2) void verbose(const char *fmt, ...) 166 { 167 va_list args; 168 169 if (log_level == 0 || log_len >= log_size - 1) 170 return; 171 172 va_start(args, fmt); 173 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); 174 va_end(args); 175 } 176 177 /* string representation of 'enum bpf_reg_type' */ 178 static const char * const reg_type_str[] = { 179 [NOT_INIT] = "?", 180 [UNKNOWN_VALUE] = "inv", 181 [PTR_TO_CTX] = "ctx", 182 [CONST_PTR_TO_MAP] = "map_ptr", 183 [PTR_TO_MAP_VALUE] = "map_value", 184 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", 185 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj", 186 [FRAME_PTR] = "fp", 187 [PTR_TO_STACK] = "fp", 188 [CONST_IMM] = "imm", 189 [PTR_TO_PACKET] = "pkt", 190 [PTR_TO_PACKET_END] = "pkt_end", 191 }; 192 193 static void print_verifier_state(struct bpf_verifier_state *state) 194 { 195 struct bpf_reg_state *reg; 196 enum bpf_reg_type t; 197 int i; 198 199 for (i = 0; i < MAX_BPF_REG; i++) { 200 reg = &state->regs[i]; 201 t = reg->type; 202 if (t == NOT_INIT) 203 continue; 204 verbose(" R%d=%s", i, reg_type_str[t]); 205 if (t == CONST_IMM || t == PTR_TO_STACK) 206 verbose("%lld", reg->imm); 207 else if (t == PTR_TO_PACKET) 208 verbose("(id=%d,off=%d,r=%d)", 209 reg->id, reg->off, reg->range); 210 else if (t == UNKNOWN_VALUE && reg->imm) 211 verbose("%lld", reg->imm); 212 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || 213 t == PTR_TO_MAP_VALUE_OR_NULL || 214 t == PTR_TO_MAP_VALUE_ADJ) 215 verbose("(ks=%d,vs=%d)", 216 reg->map_ptr->key_size, 217 reg->map_ptr->value_size); 218 if (reg->min_value != BPF_REGISTER_MIN_RANGE) 219 verbose(",min_value=%llu", 220 (unsigned long long)reg->min_value); 221 if (reg->max_value != BPF_REGISTER_MAX_RANGE) 222 verbose(",max_value=%llu", 223 (unsigned long long)reg->max_value); 224 } 225 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 226 if (state->stack_slot_type[i] == STACK_SPILL) 227 verbose(" fp%d=%s", -MAX_BPF_STACK + i, 228 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); 229 } 230 verbose("\n"); 231 } 232 233 static const char *const bpf_class_string[] = { 234 [BPF_LD] = "ld", 235 [BPF_LDX] = "ldx", 236 [BPF_ST] = "st", 237 [BPF_STX] = "stx", 238 [BPF_ALU] = "alu", 239 [BPF_JMP] = "jmp", 240 [BPF_RET] = "BUG", 241 [BPF_ALU64] = "alu64", 242 }; 243 244 static const char *const bpf_alu_string[16] = { 245 [BPF_ADD >> 4] = "+=", 246 [BPF_SUB >> 4] = "-=", 247 [BPF_MUL >> 4] = "*=", 248 [BPF_DIV >> 4] = "/=", 249 [BPF_OR >> 4] = "|=", 250 [BPF_AND >> 4] = "&=", 251 [BPF_LSH >> 4] = "<<=", 252 [BPF_RSH >> 4] = ">>=", 253 [BPF_NEG >> 4] = "neg", 254 [BPF_MOD >> 4] = "%=", 255 [BPF_XOR >> 4] = "^=", 256 [BPF_MOV >> 4] = "=", 257 [BPF_ARSH >> 4] = "s>>=", 258 [BPF_END >> 4] = "endian", 259 }; 260 261 static const char *const bpf_ldst_string[] = { 262 [BPF_W >> 3] = "u32", 263 [BPF_H >> 3] = "u16", 264 [BPF_B >> 3] = "u8", 265 [BPF_DW >> 3] = "u64", 266 }; 267 268 static const char *const bpf_jmp_string[16] = { 269 [BPF_JA >> 4] = "jmp", 270 [BPF_JEQ >> 4] = "==", 271 [BPF_JGT >> 4] = ">", 272 [BPF_JGE >> 4] = ">=", 273 [BPF_JSET >> 4] = "&", 274 [BPF_JNE >> 4] = "!=", 275 [BPF_JSGT >> 4] = "s>", 276 [BPF_JSGE >> 4] = "s>=", 277 [BPF_CALL >> 4] = "call", 278 [BPF_EXIT >> 4] = "exit", 279 }; 280 281 static void print_bpf_insn(struct bpf_insn *insn) 282 { 283 u8 class = BPF_CLASS(insn->code); 284 285 if (class == BPF_ALU || class == BPF_ALU64) { 286 if (BPF_SRC(insn->code) == BPF_X) 287 verbose("(%02x) %sr%d %s %sr%d\n", 288 insn->code, class == BPF_ALU ? "(u32) " : "", 289 insn->dst_reg, 290 bpf_alu_string[BPF_OP(insn->code) >> 4], 291 class == BPF_ALU ? "(u32) " : "", 292 insn->src_reg); 293 else 294 verbose("(%02x) %sr%d %s %s%d\n", 295 insn->code, class == BPF_ALU ? "(u32) " : "", 296 insn->dst_reg, 297 bpf_alu_string[BPF_OP(insn->code) >> 4], 298 class == BPF_ALU ? "(u32) " : "", 299 insn->imm); 300 } else if (class == BPF_STX) { 301 if (BPF_MODE(insn->code) == BPF_MEM) 302 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", 303 insn->code, 304 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 305 insn->dst_reg, 306 insn->off, insn->src_reg); 307 else if (BPF_MODE(insn->code) == BPF_XADD) 308 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", 309 insn->code, 310 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 311 insn->dst_reg, insn->off, 312 insn->src_reg); 313 else 314 verbose("BUG_%02x\n", insn->code); 315 } else if (class == BPF_ST) { 316 if (BPF_MODE(insn->code) != BPF_MEM) { 317 verbose("BUG_st_%02x\n", insn->code); 318 return; 319 } 320 verbose("(%02x) *(%s *)(r%d %+d) = %d\n", 321 insn->code, 322 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 323 insn->dst_reg, 324 insn->off, insn->imm); 325 } else if (class == BPF_LDX) { 326 if (BPF_MODE(insn->code) != BPF_MEM) { 327 verbose("BUG_ldx_%02x\n", insn->code); 328 return; 329 } 330 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", 331 insn->code, insn->dst_reg, 332 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 333 insn->src_reg, insn->off); 334 } else if (class == BPF_LD) { 335 if (BPF_MODE(insn->code) == BPF_ABS) { 336 verbose("(%02x) r0 = *(%s *)skb[%d]\n", 337 insn->code, 338 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 339 insn->imm); 340 } else if (BPF_MODE(insn->code) == BPF_IND) { 341 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", 342 insn->code, 343 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 344 insn->src_reg, insn->imm); 345 } else if (BPF_MODE(insn->code) == BPF_IMM) { 346 verbose("(%02x) r%d = 0x%x\n", 347 insn->code, insn->dst_reg, insn->imm); 348 } else { 349 verbose("BUG_ld_%02x\n", insn->code); 350 return; 351 } 352 } else if (class == BPF_JMP) { 353 u8 opcode = BPF_OP(insn->code); 354 355 if (opcode == BPF_CALL) { 356 verbose("(%02x) call %d\n", insn->code, insn->imm); 357 } else if (insn->code == (BPF_JMP | BPF_JA)) { 358 verbose("(%02x) goto pc%+d\n", 359 insn->code, insn->off); 360 } else if (insn->code == (BPF_JMP | BPF_EXIT)) { 361 verbose("(%02x) exit\n", insn->code); 362 } else if (BPF_SRC(insn->code) == BPF_X) { 363 verbose("(%02x) if r%d %s r%d goto pc%+d\n", 364 insn->code, insn->dst_reg, 365 bpf_jmp_string[BPF_OP(insn->code) >> 4], 366 insn->src_reg, insn->off); 367 } else { 368 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", 369 insn->code, insn->dst_reg, 370 bpf_jmp_string[BPF_OP(insn->code) >> 4], 371 insn->imm, insn->off); 372 } 373 } else { 374 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); 375 } 376 } 377 378 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) 379 { 380 struct bpf_verifier_stack_elem *elem; 381 int insn_idx; 382 383 if (env->head == NULL) 384 return -1; 385 386 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); 387 insn_idx = env->head->insn_idx; 388 if (prev_insn_idx) 389 *prev_insn_idx = env->head->prev_insn_idx; 390 elem = env->head->next; 391 kfree(env->head); 392 env->head = elem; 393 env->stack_size--; 394 return insn_idx; 395 } 396 397 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, 398 int insn_idx, int prev_insn_idx) 399 { 400 struct bpf_verifier_stack_elem *elem; 401 402 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); 403 if (!elem) 404 goto err; 405 406 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); 407 elem->insn_idx = insn_idx; 408 elem->prev_insn_idx = prev_insn_idx; 409 elem->next = env->head; 410 env->head = elem; 411 env->stack_size++; 412 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { 413 verbose("BPF program is too complex\n"); 414 goto err; 415 } 416 return &elem->st; 417 err: 418 /* pop all elements and return */ 419 while (pop_stack(env, NULL) >= 0); 420 return NULL; 421 } 422 423 #define CALLER_SAVED_REGS 6 424 static const int caller_saved[CALLER_SAVED_REGS] = { 425 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 426 }; 427 428 static void init_reg_state(struct bpf_reg_state *regs) 429 { 430 int i; 431 432 for (i = 0; i < MAX_BPF_REG; i++) { 433 regs[i].type = NOT_INIT; 434 regs[i].imm = 0; 435 regs[i].min_value = BPF_REGISTER_MIN_RANGE; 436 regs[i].max_value = BPF_REGISTER_MAX_RANGE; 437 } 438 439 /* frame pointer */ 440 regs[BPF_REG_FP].type = FRAME_PTR; 441 442 /* 1st arg to a function */ 443 regs[BPF_REG_1].type = PTR_TO_CTX; 444 } 445 446 static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) 447 { 448 BUG_ON(regno >= MAX_BPF_REG); 449 regs[regno].type = UNKNOWN_VALUE; 450 regs[regno].imm = 0; 451 } 452 453 static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno) 454 { 455 regs[regno].min_value = BPF_REGISTER_MIN_RANGE; 456 regs[regno].max_value = BPF_REGISTER_MAX_RANGE; 457 } 458 459 enum reg_arg_type { 460 SRC_OP, /* register is used as source operand */ 461 DST_OP, /* register is used as destination operand */ 462 DST_OP_NO_MARK /* same as above, check only, don't mark */ 463 }; 464 465 static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, 466 enum reg_arg_type t) 467 { 468 if (regno >= MAX_BPF_REG) { 469 verbose("R%d is invalid\n", regno); 470 return -EINVAL; 471 } 472 473 if (t == SRC_OP) { 474 /* check whether register used as source operand can be read */ 475 if (regs[regno].type == NOT_INIT) { 476 verbose("R%d !read_ok\n", regno); 477 return -EACCES; 478 } 479 } else { 480 /* check whether register used as dest operand can be written to */ 481 if (regno == BPF_REG_FP) { 482 verbose("frame pointer is read only\n"); 483 return -EACCES; 484 } 485 if (t == DST_OP) 486 mark_reg_unknown_value(regs, regno); 487 } 488 return 0; 489 } 490 491 static int bpf_size_to_bytes(int bpf_size) 492 { 493 if (bpf_size == BPF_W) 494 return 4; 495 else if (bpf_size == BPF_H) 496 return 2; 497 else if (bpf_size == BPF_B) 498 return 1; 499 else if (bpf_size == BPF_DW) 500 return 8; 501 else 502 return -EINVAL; 503 } 504 505 static bool is_spillable_regtype(enum bpf_reg_type type) 506 { 507 switch (type) { 508 case PTR_TO_MAP_VALUE: 509 case PTR_TO_MAP_VALUE_OR_NULL: 510 case PTR_TO_STACK: 511 case PTR_TO_CTX: 512 case PTR_TO_PACKET: 513 case PTR_TO_PACKET_END: 514 case FRAME_PTR: 515 case CONST_PTR_TO_MAP: 516 return true; 517 default: 518 return false; 519 } 520 } 521 522 /* check_stack_read/write functions track spill/fill of registers, 523 * stack boundary and alignment are checked in check_mem_access() 524 */ 525 static int check_stack_write(struct bpf_verifier_state *state, int off, 526 int size, int value_regno) 527 { 528 int i; 529 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, 530 * so it's aligned access and [off, off + size) are within stack limits 531 */ 532 533 if (value_regno >= 0 && 534 is_spillable_regtype(state->regs[value_regno].type)) { 535 536 /* register containing pointer is being spilled into stack */ 537 if (size != BPF_REG_SIZE) { 538 verbose("invalid size of register spill\n"); 539 return -EACCES; 540 } 541 542 /* save register state */ 543 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 544 state->regs[value_regno]; 545 546 for (i = 0; i < BPF_REG_SIZE; i++) 547 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; 548 } else { 549 /* regular write of data into stack */ 550 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 551 (struct bpf_reg_state) {}; 552 553 for (i = 0; i < size; i++) 554 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; 555 } 556 return 0; 557 } 558 559 static int check_stack_read(struct bpf_verifier_state *state, int off, int size, 560 int value_regno) 561 { 562 u8 *slot_type; 563 int i; 564 565 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; 566 567 if (slot_type[0] == STACK_SPILL) { 568 if (size != BPF_REG_SIZE) { 569 verbose("invalid size of register spill\n"); 570 return -EACCES; 571 } 572 for (i = 1; i < BPF_REG_SIZE; i++) { 573 if (slot_type[i] != STACK_SPILL) { 574 verbose("corrupted spill memory\n"); 575 return -EACCES; 576 } 577 } 578 579 if (value_regno >= 0) 580 /* restore register state from stack */ 581 state->regs[value_regno] = 582 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; 583 return 0; 584 } else { 585 for (i = 0; i < size; i++) { 586 if (slot_type[i] != STACK_MISC) { 587 verbose("invalid read from stack off %d+%d size %d\n", 588 off, i, size); 589 return -EACCES; 590 } 591 } 592 if (value_regno >= 0) 593 /* have read misc data from the stack */ 594 mark_reg_unknown_value(state->regs, value_regno); 595 return 0; 596 } 597 } 598 599 /* check read/write into map element returned by bpf_map_lookup_elem() */ 600 static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, 601 int size) 602 { 603 struct bpf_map *map = env->cur_state.regs[regno].map_ptr; 604 605 if (off < 0 || off + size > map->value_size) { 606 verbose("invalid access to map value, value_size=%d off=%d size=%d\n", 607 map->value_size, off, size); 608 return -EACCES; 609 } 610 return 0; 611 } 612 613 #define MAX_PACKET_OFF 0xffff 614 615 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, 616 const struct bpf_call_arg_meta *meta) 617 { 618 switch (env->prog->type) { 619 case BPF_PROG_TYPE_SCHED_CLS: 620 case BPF_PROG_TYPE_SCHED_ACT: 621 case BPF_PROG_TYPE_XDP: 622 if (meta) 623 return meta->pkt_access; 624 625 env->seen_direct_write = true; 626 return true; 627 default: 628 return false; 629 } 630 } 631 632 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, 633 int size) 634 { 635 struct bpf_reg_state *regs = env->cur_state.regs; 636 struct bpf_reg_state *reg = ®s[regno]; 637 638 off += reg->off; 639 if (off < 0 || size <= 0 || off + size > reg->range) { 640 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", 641 off, size, regno, reg->id, reg->off, reg->range); 642 return -EACCES; 643 } 644 return 0; 645 } 646 647 /* check access to 'struct bpf_context' fields */ 648 static int check_ctx_access(struct bpf_verifier_env *env, int off, int size, 649 enum bpf_access_type t, enum bpf_reg_type *reg_type) 650 { 651 /* for analyzer ctx accesses are already validated and converted */ 652 if (env->analyzer_ops) 653 return 0; 654 655 if (env->prog->aux->ops->is_valid_access && 656 env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) { 657 /* remember the offset of last byte accessed in ctx */ 658 if (env->prog->aux->max_ctx_offset < off + size) 659 env->prog->aux->max_ctx_offset = off + size; 660 return 0; 661 } 662 663 verbose("invalid bpf_context access off=%d size=%d\n", off, size); 664 return -EACCES; 665 } 666 667 static bool is_pointer_value(struct bpf_verifier_env *env, int regno) 668 { 669 if (env->allow_ptr_leaks) 670 return false; 671 672 switch (env->cur_state.regs[regno].type) { 673 case UNKNOWN_VALUE: 674 case CONST_IMM: 675 return false; 676 default: 677 return true; 678 } 679 } 680 681 static int check_ptr_alignment(struct bpf_verifier_env *env, 682 struct bpf_reg_state *reg, int off, int size) 683 { 684 if (reg->type != PTR_TO_PACKET && reg->type != PTR_TO_MAP_VALUE_ADJ) { 685 if (off % size != 0) { 686 verbose("misaligned access off %d size %d\n", 687 off, size); 688 return -EACCES; 689 } else { 690 return 0; 691 } 692 } 693 694 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) 695 /* misaligned access to packet is ok on x86,arm,arm64 */ 696 return 0; 697 698 if (reg->id && size != 1) { 699 verbose("Unknown packet alignment. Only byte-sized access allowed\n"); 700 return -EACCES; 701 } 702 703 /* skb->data is NET_IP_ALIGN-ed */ 704 if (reg->type == PTR_TO_PACKET && 705 (NET_IP_ALIGN + reg->off + off) % size != 0) { 706 verbose("misaligned packet access off %d+%d+%d size %d\n", 707 NET_IP_ALIGN, reg->off, off, size); 708 return -EACCES; 709 } 710 return 0; 711 } 712 713 /* check whether memory at (regno + off) is accessible for t = (read | write) 714 * if t==write, value_regno is a register which value is stored into memory 715 * if t==read, value_regno is a register which will receive the value from memory 716 * if t==write && value_regno==-1, some unknown value is stored into memory 717 * if t==read && value_regno==-1, don't care what we read from memory 718 */ 719 static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off, 720 int bpf_size, enum bpf_access_type t, 721 int value_regno) 722 { 723 struct bpf_verifier_state *state = &env->cur_state; 724 struct bpf_reg_state *reg = &state->regs[regno]; 725 int size, err = 0; 726 727 if (reg->type == PTR_TO_STACK) 728 off += reg->imm; 729 730 size = bpf_size_to_bytes(bpf_size); 731 if (size < 0) 732 return size; 733 734 err = check_ptr_alignment(env, reg, off, size); 735 if (err) 736 return err; 737 738 if (reg->type == PTR_TO_MAP_VALUE || 739 reg->type == PTR_TO_MAP_VALUE_ADJ) { 740 if (t == BPF_WRITE && value_regno >= 0 && 741 is_pointer_value(env, value_regno)) { 742 verbose("R%d leaks addr into map\n", value_regno); 743 return -EACCES; 744 } 745 746 /* If we adjusted the register to this map value at all then we 747 * need to change off and size to min_value and max_value 748 * respectively to make sure our theoretical access will be 749 * safe. 750 */ 751 if (reg->type == PTR_TO_MAP_VALUE_ADJ) { 752 if (log_level) 753 print_verifier_state(state); 754 env->varlen_map_value_access = true; 755 /* The minimum value is only important with signed 756 * comparisons where we can't assume the floor of a 757 * value is 0. If we are using signed variables for our 758 * index'es we need to make sure that whatever we use 759 * will have a set floor within our range. 760 */ 761 if ((s64)reg->min_value < 0) { 762 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", 763 regno); 764 return -EACCES; 765 } 766 err = check_map_access(env, regno, reg->min_value + off, 767 size); 768 if (err) { 769 verbose("R%d min value is outside of the array range\n", 770 regno); 771 return err; 772 } 773 774 /* If we haven't set a max value then we need to bail 775 * since we can't be sure we won't do bad things. 776 */ 777 if (reg->max_value == BPF_REGISTER_MAX_RANGE) { 778 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", 779 regno); 780 return -EACCES; 781 } 782 off += reg->max_value; 783 } 784 err = check_map_access(env, regno, off, size); 785 if (!err && t == BPF_READ && value_regno >= 0) 786 mark_reg_unknown_value(state->regs, value_regno); 787 788 } else if (reg->type == PTR_TO_CTX) { 789 enum bpf_reg_type reg_type = UNKNOWN_VALUE; 790 791 if (t == BPF_WRITE && value_regno >= 0 && 792 is_pointer_value(env, value_regno)) { 793 verbose("R%d leaks addr into ctx\n", value_regno); 794 return -EACCES; 795 } 796 err = check_ctx_access(env, off, size, t, ®_type); 797 if (!err && t == BPF_READ && value_regno >= 0) { 798 mark_reg_unknown_value(state->regs, value_regno); 799 /* note that reg.[id|off|range] == 0 */ 800 state->regs[value_regno].type = reg_type; 801 } 802 803 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { 804 if (off >= 0 || off < -MAX_BPF_STACK) { 805 verbose("invalid stack off=%d size=%d\n", off, size); 806 return -EACCES; 807 } 808 if (t == BPF_WRITE) { 809 if (!env->allow_ptr_leaks && 810 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && 811 size != BPF_REG_SIZE) { 812 verbose("attempt to corrupt spilled pointer on stack\n"); 813 return -EACCES; 814 } 815 err = check_stack_write(state, off, size, value_regno); 816 } else { 817 err = check_stack_read(state, off, size, value_regno); 818 } 819 } else if (state->regs[regno].type == PTR_TO_PACKET) { 820 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL)) { 821 verbose("cannot write into packet\n"); 822 return -EACCES; 823 } 824 if (t == BPF_WRITE && value_regno >= 0 && 825 is_pointer_value(env, value_regno)) { 826 verbose("R%d leaks addr into packet\n", value_regno); 827 return -EACCES; 828 } 829 err = check_packet_access(env, regno, off, size); 830 if (!err && t == BPF_READ && value_regno >= 0) 831 mark_reg_unknown_value(state->regs, value_regno); 832 } else { 833 verbose("R%d invalid mem access '%s'\n", 834 regno, reg_type_str[reg->type]); 835 return -EACCES; 836 } 837 838 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && 839 state->regs[value_regno].type == UNKNOWN_VALUE) { 840 /* 1 or 2 byte load zero-extends, determine the number of 841 * zero upper bits. Not doing it fo 4 byte load, since 842 * such values cannot be added to ptr_to_packet anyway. 843 */ 844 state->regs[value_regno].imm = 64 - size * 8; 845 } 846 return err; 847 } 848 849 static int check_xadd(struct bpf_verifier_env *env, struct bpf_insn *insn) 850 { 851 struct bpf_reg_state *regs = env->cur_state.regs; 852 int err; 853 854 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || 855 insn->imm != 0) { 856 verbose("BPF_XADD uses reserved fields\n"); 857 return -EINVAL; 858 } 859 860 /* check src1 operand */ 861 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 862 if (err) 863 return err; 864 865 /* check src2 operand */ 866 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 867 if (err) 868 return err; 869 870 /* check whether atomic_add can read the memory */ 871 err = check_mem_access(env, insn->dst_reg, insn->off, 872 BPF_SIZE(insn->code), BPF_READ, -1); 873 if (err) 874 return err; 875 876 /* check whether atomic_add can write into the same memory */ 877 return check_mem_access(env, insn->dst_reg, insn->off, 878 BPF_SIZE(insn->code), BPF_WRITE, -1); 879 } 880 881 /* when register 'regno' is passed into function that will read 'access_size' 882 * bytes from that pointer, make sure that it's within stack boundary 883 * and all elements of stack are initialized 884 */ 885 static int check_stack_boundary(struct bpf_verifier_env *env, int regno, 886 int access_size, bool zero_size_allowed, 887 struct bpf_call_arg_meta *meta) 888 { 889 struct bpf_verifier_state *state = &env->cur_state; 890 struct bpf_reg_state *regs = state->regs; 891 int off, i; 892 893 if (regs[regno].type != PTR_TO_STACK) { 894 if (zero_size_allowed && access_size == 0 && 895 regs[regno].type == CONST_IMM && 896 regs[regno].imm == 0) 897 return 0; 898 899 verbose("R%d type=%s expected=%s\n", regno, 900 reg_type_str[regs[regno].type], 901 reg_type_str[PTR_TO_STACK]); 902 return -EACCES; 903 } 904 905 off = regs[regno].imm; 906 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || 907 access_size <= 0) { 908 verbose("invalid stack type R%d off=%d access_size=%d\n", 909 regno, off, access_size); 910 return -EACCES; 911 } 912 913 if (meta && meta->raw_mode) { 914 meta->access_size = access_size; 915 meta->regno = regno; 916 return 0; 917 } 918 919 for (i = 0; i < access_size; i++) { 920 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { 921 verbose("invalid indirect read from stack off %d+%d size %d\n", 922 off, i, access_size); 923 return -EACCES; 924 } 925 } 926 return 0; 927 } 928 929 static int check_func_arg(struct bpf_verifier_env *env, u32 regno, 930 enum bpf_arg_type arg_type, 931 struct bpf_call_arg_meta *meta) 932 { 933 struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; 934 enum bpf_reg_type expected_type, type = reg->type; 935 int err = 0; 936 937 if (arg_type == ARG_DONTCARE) 938 return 0; 939 940 if (type == NOT_INIT) { 941 verbose("R%d !read_ok\n", regno); 942 return -EACCES; 943 } 944 945 if (arg_type == ARG_ANYTHING) { 946 if (is_pointer_value(env, regno)) { 947 verbose("R%d leaks addr into helper function\n", regno); 948 return -EACCES; 949 } 950 return 0; 951 } 952 953 if (type == PTR_TO_PACKET && !may_access_direct_pkt_data(env, meta)) { 954 verbose("helper access to the packet is not allowed\n"); 955 return -EACCES; 956 } 957 958 if (arg_type == ARG_PTR_TO_MAP_KEY || 959 arg_type == ARG_PTR_TO_MAP_VALUE) { 960 expected_type = PTR_TO_STACK; 961 if (type != PTR_TO_PACKET && type != expected_type) 962 goto err_type; 963 } else if (arg_type == ARG_CONST_STACK_SIZE || 964 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { 965 expected_type = CONST_IMM; 966 if (type != expected_type) 967 goto err_type; 968 } else if (arg_type == ARG_CONST_MAP_PTR) { 969 expected_type = CONST_PTR_TO_MAP; 970 if (type != expected_type) 971 goto err_type; 972 } else if (arg_type == ARG_PTR_TO_CTX) { 973 expected_type = PTR_TO_CTX; 974 if (type != expected_type) 975 goto err_type; 976 } else if (arg_type == ARG_PTR_TO_STACK || 977 arg_type == ARG_PTR_TO_RAW_STACK) { 978 expected_type = PTR_TO_STACK; 979 /* One exception here. In case function allows for NULL to be 980 * passed in as argument, it's a CONST_IMM type. Final test 981 * happens during stack boundary checking. 982 */ 983 if (type == CONST_IMM && reg->imm == 0) 984 /* final test in check_stack_boundary() */; 985 else if (type != PTR_TO_PACKET && type != expected_type) 986 goto err_type; 987 meta->raw_mode = arg_type == ARG_PTR_TO_RAW_STACK; 988 } else { 989 verbose("unsupported arg_type %d\n", arg_type); 990 return -EFAULT; 991 } 992 993 if (arg_type == ARG_CONST_MAP_PTR) { 994 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ 995 meta->map_ptr = reg->map_ptr; 996 } else if (arg_type == ARG_PTR_TO_MAP_KEY) { 997 /* bpf_map_xxx(..., map_ptr, ..., key) call: 998 * check that [key, key + map->key_size) are within 999 * stack limits and initialized 1000 */ 1001 if (!meta->map_ptr) { 1002 /* in function declaration map_ptr must come before 1003 * map_key, so that it's verified and known before 1004 * we have to check map_key here. Otherwise it means 1005 * that kernel subsystem misconfigured verifier 1006 */ 1007 verbose("invalid map_ptr to access map->key\n"); 1008 return -EACCES; 1009 } 1010 if (type == PTR_TO_PACKET) 1011 err = check_packet_access(env, regno, 0, 1012 meta->map_ptr->key_size); 1013 else 1014 err = check_stack_boundary(env, regno, 1015 meta->map_ptr->key_size, 1016 false, NULL); 1017 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { 1018 /* bpf_map_xxx(..., map_ptr, ..., value) call: 1019 * check [value, value + map->value_size) validity 1020 */ 1021 if (!meta->map_ptr) { 1022 /* kernel subsystem misconfigured verifier */ 1023 verbose("invalid map_ptr to access map->value\n"); 1024 return -EACCES; 1025 } 1026 if (type == PTR_TO_PACKET) 1027 err = check_packet_access(env, regno, 0, 1028 meta->map_ptr->value_size); 1029 else 1030 err = check_stack_boundary(env, regno, 1031 meta->map_ptr->value_size, 1032 false, NULL); 1033 } else if (arg_type == ARG_CONST_STACK_SIZE || 1034 arg_type == ARG_CONST_STACK_SIZE_OR_ZERO) { 1035 bool zero_size_allowed = (arg_type == ARG_CONST_STACK_SIZE_OR_ZERO); 1036 1037 /* bpf_xxx(..., buf, len) call will access 'len' bytes 1038 * from stack pointer 'buf'. Check it 1039 * note: regno == len, regno - 1 == buf 1040 */ 1041 if (regno == 0) { 1042 /* kernel subsystem misconfigured verifier */ 1043 verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); 1044 return -EACCES; 1045 } 1046 if (regs[regno - 1].type == PTR_TO_PACKET) 1047 err = check_packet_access(env, regno - 1, 0, reg->imm); 1048 else 1049 err = check_stack_boundary(env, regno - 1, reg->imm, 1050 zero_size_allowed, meta); 1051 } 1052 1053 return err; 1054 err_type: 1055 verbose("R%d type=%s expected=%s\n", regno, 1056 reg_type_str[type], reg_type_str[expected_type]); 1057 return -EACCES; 1058 } 1059 1060 static int check_map_func_compatibility(struct bpf_map *map, int func_id) 1061 { 1062 if (!map) 1063 return 0; 1064 1065 /* We need a two way check, first is from map perspective ... */ 1066 switch (map->map_type) { 1067 case BPF_MAP_TYPE_PROG_ARRAY: 1068 if (func_id != BPF_FUNC_tail_call) 1069 goto error; 1070 break; 1071 case BPF_MAP_TYPE_PERF_EVENT_ARRAY: 1072 if (func_id != BPF_FUNC_perf_event_read && 1073 func_id != BPF_FUNC_perf_event_output) 1074 goto error; 1075 break; 1076 case BPF_MAP_TYPE_STACK_TRACE: 1077 if (func_id != BPF_FUNC_get_stackid) 1078 goto error; 1079 break; 1080 case BPF_MAP_TYPE_CGROUP_ARRAY: 1081 if (func_id != BPF_FUNC_skb_under_cgroup && 1082 func_id != BPF_FUNC_current_task_under_cgroup) 1083 goto error; 1084 break; 1085 default: 1086 break; 1087 } 1088 1089 /* ... and second from the function itself. */ 1090 switch (func_id) { 1091 case BPF_FUNC_tail_call: 1092 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) 1093 goto error; 1094 break; 1095 case BPF_FUNC_perf_event_read: 1096 case BPF_FUNC_perf_event_output: 1097 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) 1098 goto error; 1099 break; 1100 case BPF_FUNC_get_stackid: 1101 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) 1102 goto error; 1103 break; 1104 case BPF_FUNC_current_task_under_cgroup: 1105 case BPF_FUNC_skb_under_cgroup: 1106 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) 1107 goto error; 1108 break; 1109 default: 1110 break; 1111 } 1112 1113 return 0; 1114 error: 1115 verbose("cannot pass map_type %d into func %d\n", 1116 map->map_type, func_id); 1117 return -EINVAL; 1118 } 1119 1120 static int check_raw_mode(const struct bpf_func_proto *fn) 1121 { 1122 int count = 0; 1123 1124 if (fn->arg1_type == ARG_PTR_TO_RAW_STACK) 1125 count++; 1126 if (fn->arg2_type == ARG_PTR_TO_RAW_STACK) 1127 count++; 1128 if (fn->arg3_type == ARG_PTR_TO_RAW_STACK) 1129 count++; 1130 if (fn->arg4_type == ARG_PTR_TO_RAW_STACK) 1131 count++; 1132 if (fn->arg5_type == ARG_PTR_TO_RAW_STACK) 1133 count++; 1134 1135 return count > 1 ? -EINVAL : 0; 1136 } 1137 1138 static void clear_all_pkt_pointers(struct bpf_verifier_env *env) 1139 { 1140 struct bpf_verifier_state *state = &env->cur_state; 1141 struct bpf_reg_state *regs = state->regs, *reg; 1142 int i; 1143 1144 for (i = 0; i < MAX_BPF_REG; i++) 1145 if (regs[i].type == PTR_TO_PACKET || 1146 regs[i].type == PTR_TO_PACKET_END) 1147 mark_reg_unknown_value(regs, i); 1148 1149 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 1150 if (state->stack_slot_type[i] != STACK_SPILL) 1151 continue; 1152 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 1153 if (reg->type != PTR_TO_PACKET && 1154 reg->type != PTR_TO_PACKET_END) 1155 continue; 1156 reg->type = UNKNOWN_VALUE; 1157 reg->imm = 0; 1158 } 1159 } 1160 1161 static int check_call(struct bpf_verifier_env *env, int func_id) 1162 { 1163 struct bpf_verifier_state *state = &env->cur_state; 1164 const struct bpf_func_proto *fn = NULL; 1165 struct bpf_reg_state *regs = state->regs; 1166 struct bpf_reg_state *reg; 1167 struct bpf_call_arg_meta meta; 1168 bool changes_data; 1169 int i, err; 1170 1171 /* find function prototype */ 1172 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { 1173 verbose("invalid func %d\n", func_id); 1174 return -EINVAL; 1175 } 1176 1177 if (env->prog->aux->ops->get_func_proto) 1178 fn = env->prog->aux->ops->get_func_proto(func_id); 1179 1180 if (!fn) { 1181 verbose("unknown func %d\n", func_id); 1182 return -EINVAL; 1183 } 1184 1185 /* eBPF programs must be GPL compatible to use GPL-ed functions */ 1186 if (!env->prog->gpl_compatible && fn->gpl_only) { 1187 verbose("cannot call GPL only function from proprietary program\n"); 1188 return -EINVAL; 1189 } 1190 1191 changes_data = bpf_helper_changes_skb_data(fn->func); 1192 1193 memset(&meta, 0, sizeof(meta)); 1194 meta.pkt_access = fn->pkt_access; 1195 1196 /* We only support one arg being in raw mode at the moment, which 1197 * is sufficient for the helper functions we have right now. 1198 */ 1199 err = check_raw_mode(fn); 1200 if (err) { 1201 verbose("kernel subsystem misconfigured func %d\n", func_id); 1202 return err; 1203 } 1204 1205 /* check args */ 1206 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); 1207 if (err) 1208 return err; 1209 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); 1210 if (err) 1211 return err; 1212 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); 1213 if (err) 1214 return err; 1215 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); 1216 if (err) 1217 return err; 1218 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); 1219 if (err) 1220 return err; 1221 1222 /* Mark slots with STACK_MISC in case of raw mode, stack offset 1223 * is inferred from register state. 1224 */ 1225 for (i = 0; i < meta.access_size; i++) { 1226 err = check_mem_access(env, meta.regno, i, BPF_B, BPF_WRITE, -1); 1227 if (err) 1228 return err; 1229 } 1230 1231 /* reset caller saved regs */ 1232 for (i = 0; i < CALLER_SAVED_REGS; i++) { 1233 reg = regs + caller_saved[i]; 1234 reg->type = NOT_INIT; 1235 reg->imm = 0; 1236 } 1237 1238 /* update return register */ 1239 if (fn->ret_type == RET_INTEGER) { 1240 regs[BPF_REG_0].type = UNKNOWN_VALUE; 1241 } else if (fn->ret_type == RET_VOID) { 1242 regs[BPF_REG_0].type = NOT_INIT; 1243 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { 1244 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; 1245 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0; 1246 /* remember map_ptr, so that check_map_access() 1247 * can check 'value_size' boundary of memory access 1248 * to map element returned from bpf_map_lookup_elem() 1249 */ 1250 if (meta.map_ptr == NULL) { 1251 verbose("kernel subsystem misconfigured verifier\n"); 1252 return -EINVAL; 1253 } 1254 regs[BPF_REG_0].map_ptr = meta.map_ptr; 1255 } else { 1256 verbose("unknown return type %d of func %d\n", 1257 fn->ret_type, func_id); 1258 return -EINVAL; 1259 } 1260 1261 err = check_map_func_compatibility(meta.map_ptr, func_id); 1262 if (err) 1263 return err; 1264 1265 if (changes_data) 1266 clear_all_pkt_pointers(env); 1267 return 0; 1268 } 1269 1270 static int check_packet_ptr_add(struct bpf_verifier_env *env, 1271 struct bpf_insn *insn) 1272 { 1273 struct bpf_reg_state *regs = env->cur_state.regs; 1274 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1275 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1276 struct bpf_reg_state tmp_reg; 1277 s32 imm; 1278 1279 if (BPF_SRC(insn->code) == BPF_K) { 1280 /* pkt_ptr += imm */ 1281 imm = insn->imm; 1282 1283 add_imm: 1284 if (imm <= 0) { 1285 verbose("addition of negative constant to packet pointer is not allowed\n"); 1286 return -EACCES; 1287 } 1288 if (imm >= MAX_PACKET_OFF || 1289 imm + dst_reg->off >= MAX_PACKET_OFF) { 1290 verbose("constant %d is too large to add to packet pointer\n", 1291 imm); 1292 return -EACCES; 1293 } 1294 /* a constant was added to pkt_ptr. 1295 * Remember it while keeping the same 'id' 1296 */ 1297 dst_reg->off += imm; 1298 } else { 1299 if (src_reg->type == PTR_TO_PACKET) { 1300 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ 1301 tmp_reg = *dst_reg; /* save r7 state */ 1302 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ 1303 src_reg = &tmp_reg; /* pretend it's src_reg state */ 1304 /* if the checks below reject it, the copy won't matter, 1305 * since we're rejecting the whole program. If all ok, 1306 * then imm22 state will be added to r7 1307 * and r7 will be pkt(id=0,off=22,r=62) while 1308 * r6 will stay as pkt(id=0,off=0,r=62) 1309 */ 1310 } 1311 1312 if (src_reg->type == CONST_IMM) { 1313 /* pkt_ptr += reg where reg is known constant */ 1314 imm = src_reg->imm; 1315 goto add_imm; 1316 } 1317 /* disallow pkt_ptr += reg 1318 * if reg is not uknown_value with guaranteed zero upper bits 1319 * otherwise pkt_ptr may overflow and addition will become 1320 * subtraction which is not allowed 1321 */ 1322 if (src_reg->type != UNKNOWN_VALUE) { 1323 verbose("cannot add '%s' to ptr_to_packet\n", 1324 reg_type_str[src_reg->type]); 1325 return -EACCES; 1326 } 1327 if (src_reg->imm < 48) { 1328 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", 1329 src_reg->imm); 1330 return -EACCES; 1331 } 1332 /* dst_reg stays as pkt_ptr type and since some positive 1333 * integer value was added to the pointer, increment its 'id' 1334 */ 1335 dst_reg->id = ++env->id_gen; 1336 1337 /* something was added to pkt_ptr, set range and off to zero */ 1338 dst_reg->off = 0; 1339 dst_reg->range = 0; 1340 } 1341 return 0; 1342 } 1343 1344 static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) 1345 { 1346 struct bpf_reg_state *regs = env->cur_state.regs; 1347 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1348 u8 opcode = BPF_OP(insn->code); 1349 s64 imm_log2; 1350 1351 /* for type == UNKNOWN_VALUE: 1352 * imm > 0 -> number of zero upper bits 1353 * imm == 0 -> don't track which is the same as all bits can be non-zero 1354 */ 1355 1356 if (BPF_SRC(insn->code) == BPF_X) { 1357 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1358 1359 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && 1360 dst_reg->imm && opcode == BPF_ADD) { 1361 /* dreg += sreg 1362 * where both have zero upper bits. Adding them 1363 * can only result making one more bit non-zero 1364 * in the larger value. 1365 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) 1366 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) 1367 */ 1368 dst_reg->imm = min(dst_reg->imm, src_reg->imm); 1369 dst_reg->imm--; 1370 return 0; 1371 } 1372 if (src_reg->type == CONST_IMM && src_reg->imm > 0 && 1373 dst_reg->imm && opcode == BPF_ADD) { 1374 /* dreg += sreg 1375 * where dreg has zero upper bits and sreg is const. 1376 * Adding them can only result making one more bit 1377 * non-zero in the larger value. 1378 */ 1379 imm_log2 = __ilog2_u64((long long)src_reg->imm); 1380 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1381 dst_reg->imm--; 1382 return 0; 1383 } 1384 /* all other cases non supported yet, just mark dst_reg */ 1385 dst_reg->imm = 0; 1386 return 0; 1387 } 1388 1389 /* sign extend 32-bit imm into 64-bit to make sure that 1390 * negative values occupy bit 63. Note ilog2() would have 1391 * been incorrect, since sizeof(insn->imm) == 4 1392 */ 1393 imm_log2 = __ilog2_u64((long long)insn->imm); 1394 1395 if (dst_reg->imm && opcode == BPF_LSH) { 1396 /* reg <<= imm 1397 * if reg was a result of 2 byte load, then its imm == 48 1398 * which means that upper 48 bits are zero and shifting this reg 1399 * left by 4 would mean that upper 44 bits are still zero 1400 */ 1401 dst_reg->imm -= insn->imm; 1402 } else if (dst_reg->imm && opcode == BPF_MUL) { 1403 /* reg *= imm 1404 * if multiplying by 14 subtract 4 1405 * This is conservative calculation of upper zero bits. 1406 * It's not trying to special case insn->imm == 1 or 0 cases 1407 */ 1408 dst_reg->imm -= imm_log2 + 1; 1409 } else if (opcode == BPF_AND) { 1410 /* reg &= imm */ 1411 dst_reg->imm = 63 - imm_log2; 1412 } else if (dst_reg->imm && opcode == BPF_ADD) { 1413 /* reg += imm */ 1414 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1415 dst_reg->imm--; 1416 } else if (opcode == BPF_RSH) { 1417 /* reg >>= imm 1418 * which means that after right shift, upper bits will be zero 1419 * note that verifier already checked that 1420 * 0 <= imm < 64 for shift insn 1421 */ 1422 dst_reg->imm += insn->imm; 1423 if (unlikely(dst_reg->imm > 64)) 1424 /* some dumb code did: 1425 * r2 = *(u32 *)mem; 1426 * r2 >>= 32; 1427 * and all bits are zero now */ 1428 dst_reg->imm = 64; 1429 } else { 1430 /* all other alu ops, means that we don't know what will 1431 * happen to the value, mark it with unknown number of zero bits 1432 */ 1433 dst_reg->imm = 0; 1434 } 1435 1436 if (dst_reg->imm < 0) { 1437 /* all 64 bits of the register can contain non-zero bits 1438 * and such value cannot be added to ptr_to_packet, since it 1439 * may overflow, mark it as unknown to avoid further eval 1440 */ 1441 dst_reg->imm = 0; 1442 } 1443 return 0; 1444 } 1445 1446 static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, 1447 struct bpf_insn *insn) 1448 { 1449 struct bpf_reg_state *regs = env->cur_state.regs; 1450 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1451 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1452 u8 opcode = BPF_OP(insn->code); 1453 1454 /* dst_reg->type == CONST_IMM here, simulate execution of 'add' insn. 1455 * Don't care about overflow or negative values, just add them 1456 */ 1457 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) 1458 dst_reg->imm += insn->imm; 1459 else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && 1460 src_reg->type == CONST_IMM) 1461 dst_reg->imm += src_reg->imm; 1462 else 1463 mark_reg_unknown_value(regs, insn->dst_reg); 1464 return 0; 1465 } 1466 1467 static void check_reg_overflow(struct bpf_reg_state *reg) 1468 { 1469 if (reg->max_value > BPF_REGISTER_MAX_RANGE) 1470 reg->max_value = BPF_REGISTER_MAX_RANGE; 1471 if ((s64)reg->min_value < BPF_REGISTER_MIN_RANGE) 1472 reg->min_value = BPF_REGISTER_MIN_RANGE; 1473 } 1474 1475 static void adjust_reg_min_max_vals(struct bpf_verifier_env *env, 1476 struct bpf_insn *insn) 1477 { 1478 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1479 u64 min_val = BPF_REGISTER_MIN_RANGE, max_val = BPF_REGISTER_MAX_RANGE; 1480 bool min_set = false, max_set = false; 1481 u8 opcode = BPF_OP(insn->code); 1482 1483 dst_reg = ®s[insn->dst_reg]; 1484 if (BPF_SRC(insn->code) == BPF_X) { 1485 check_reg_overflow(®s[insn->src_reg]); 1486 min_val = regs[insn->src_reg].min_value; 1487 max_val = regs[insn->src_reg].max_value; 1488 1489 /* If the source register is a random pointer then the 1490 * min_value/max_value values represent the range of the known 1491 * accesses into that value, not the actual min/max value of the 1492 * register itself. In this case we have to reset the reg range 1493 * values so we know it is not safe to look at. 1494 */ 1495 if (regs[insn->src_reg].type != CONST_IMM && 1496 regs[insn->src_reg].type != UNKNOWN_VALUE) { 1497 min_val = BPF_REGISTER_MIN_RANGE; 1498 max_val = BPF_REGISTER_MAX_RANGE; 1499 } 1500 } else if (insn->imm < BPF_REGISTER_MAX_RANGE && 1501 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) { 1502 min_val = max_val = insn->imm; 1503 min_set = max_set = true; 1504 } 1505 1506 /* We don't know anything about what was done to this register, mark it 1507 * as unknown. 1508 */ 1509 if (min_val == BPF_REGISTER_MIN_RANGE && 1510 max_val == BPF_REGISTER_MAX_RANGE) { 1511 reset_reg_range_values(regs, insn->dst_reg); 1512 return; 1513 } 1514 1515 switch (opcode) { 1516 case BPF_ADD: 1517 dst_reg->min_value += min_val; 1518 dst_reg->max_value += max_val; 1519 break; 1520 case BPF_SUB: 1521 dst_reg->min_value -= min_val; 1522 dst_reg->max_value -= max_val; 1523 break; 1524 case BPF_MUL: 1525 dst_reg->min_value *= min_val; 1526 dst_reg->max_value *= max_val; 1527 break; 1528 case BPF_AND: 1529 /* & is special since it could end up with 0 bits set. */ 1530 dst_reg->min_value &= min_val; 1531 dst_reg->max_value = max_val; 1532 break; 1533 case BPF_LSH: 1534 /* Gotta have special overflow logic here, if we're shifting 1535 * more than MAX_RANGE then just assume we have an invalid 1536 * range. 1537 */ 1538 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) 1539 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1540 else 1541 dst_reg->min_value <<= min_val; 1542 1543 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE)) 1544 dst_reg->max_value = BPF_REGISTER_MAX_RANGE; 1545 else 1546 dst_reg->max_value <<= max_val; 1547 break; 1548 case BPF_RSH: 1549 dst_reg->min_value >>= min_val; 1550 dst_reg->max_value >>= max_val; 1551 break; 1552 case BPF_MOD: 1553 /* % is special since it is an unsigned modulus, so the floor 1554 * will always be 0. 1555 */ 1556 dst_reg->min_value = 0; 1557 dst_reg->max_value = max_val - 1; 1558 break; 1559 default: 1560 reset_reg_range_values(regs, insn->dst_reg); 1561 break; 1562 } 1563 1564 check_reg_overflow(dst_reg); 1565 } 1566 1567 /* check validity of 32-bit and 64-bit arithmetic operations */ 1568 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) 1569 { 1570 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1571 u8 opcode = BPF_OP(insn->code); 1572 int err; 1573 1574 if (opcode == BPF_END || opcode == BPF_NEG) { 1575 if (opcode == BPF_NEG) { 1576 if (BPF_SRC(insn->code) != 0 || 1577 insn->src_reg != BPF_REG_0 || 1578 insn->off != 0 || insn->imm != 0) { 1579 verbose("BPF_NEG uses reserved fields\n"); 1580 return -EINVAL; 1581 } 1582 } else { 1583 if (insn->src_reg != BPF_REG_0 || insn->off != 0 || 1584 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { 1585 verbose("BPF_END uses reserved fields\n"); 1586 return -EINVAL; 1587 } 1588 } 1589 1590 /* check src operand */ 1591 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1592 if (err) 1593 return err; 1594 1595 if (is_pointer_value(env, insn->dst_reg)) { 1596 verbose("R%d pointer arithmetic prohibited\n", 1597 insn->dst_reg); 1598 return -EACCES; 1599 } 1600 1601 /* check dest operand */ 1602 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1603 if (err) 1604 return err; 1605 1606 } else if (opcode == BPF_MOV) { 1607 1608 if (BPF_SRC(insn->code) == BPF_X) { 1609 if (insn->imm != 0 || insn->off != 0) { 1610 verbose("BPF_MOV uses reserved fields\n"); 1611 return -EINVAL; 1612 } 1613 1614 /* check src operand */ 1615 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1616 if (err) 1617 return err; 1618 } else { 1619 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 1620 verbose("BPF_MOV uses reserved fields\n"); 1621 return -EINVAL; 1622 } 1623 } 1624 1625 /* check dest operand */ 1626 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1627 if (err) 1628 return err; 1629 1630 /* we are setting our register to something new, we need to 1631 * reset its range values. 1632 */ 1633 reset_reg_range_values(regs, insn->dst_reg); 1634 1635 if (BPF_SRC(insn->code) == BPF_X) { 1636 if (BPF_CLASS(insn->code) == BPF_ALU64) { 1637 /* case: R1 = R2 1638 * copy register state to dest reg 1639 */ 1640 regs[insn->dst_reg] = regs[insn->src_reg]; 1641 } else { 1642 if (is_pointer_value(env, insn->src_reg)) { 1643 verbose("R%d partial copy of pointer\n", 1644 insn->src_reg); 1645 return -EACCES; 1646 } 1647 regs[insn->dst_reg].type = UNKNOWN_VALUE; 1648 regs[insn->dst_reg].map_ptr = NULL; 1649 } 1650 } else { 1651 /* case: R = imm 1652 * remember the value we stored into this reg 1653 */ 1654 regs[insn->dst_reg].type = CONST_IMM; 1655 regs[insn->dst_reg].imm = insn->imm; 1656 regs[insn->dst_reg].max_value = insn->imm; 1657 regs[insn->dst_reg].min_value = insn->imm; 1658 } 1659 1660 } else if (opcode > BPF_END) { 1661 verbose("invalid BPF_ALU opcode %x\n", opcode); 1662 return -EINVAL; 1663 1664 } else { /* all other ALU ops: and, sub, xor, add, ... */ 1665 1666 if (BPF_SRC(insn->code) == BPF_X) { 1667 if (insn->imm != 0 || insn->off != 0) { 1668 verbose("BPF_ALU uses reserved fields\n"); 1669 return -EINVAL; 1670 } 1671 /* check src1 operand */ 1672 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1673 if (err) 1674 return err; 1675 } else { 1676 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 1677 verbose("BPF_ALU uses reserved fields\n"); 1678 return -EINVAL; 1679 } 1680 } 1681 1682 /* check src2 operand */ 1683 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1684 if (err) 1685 return err; 1686 1687 if ((opcode == BPF_MOD || opcode == BPF_DIV) && 1688 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { 1689 verbose("div by zero\n"); 1690 return -EINVAL; 1691 } 1692 1693 if ((opcode == BPF_LSH || opcode == BPF_RSH || 1694 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { 1695 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; 1696 1697 if (insn->imm < 0 || insn->imm >= size) { 1698 verbose("invalid shift %d\n", insn->imm); 1699 return -EINVAL; 1700 } 1701 } 1702 1703 /* check dest operand */ 1704 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 1705 if (err) 1706 return err; 1707 1708 dst_reg = ®s[insn->dst_reg]; 1709 1710 /* first we want to adjust our ranges. */ 1711 adjust_reg_min_max_vals(env, insn); 1712 1713 /* pattern match 'bpf_add Rx, imm' instruction */ 1714 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && 1715 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { 1716 dst_reg->type = PTR_TO_STACK; 1717 dst_reg->imm = insn->imm; 1718 return 0; 1719 } else if (opcode == BPF_ADD && 1720 BPF_CLASS(insn->code) == BPF_ALU64 && 1721 (dst_reg->type == PTR_TO_PACKET || 1722 (BPF_SRC(insn->code) == BPF_X && 1723 regs[insn->src_reg].type == PTR_TO_PACKET))) { 1724 /* ptr_to_packet += K|X */ 1725 return check_packet_ptr_add(env, insn); 1726 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 1727 dst_reg->type == UNKNOWN_VALUE && 1728 env->allow_ptr_leaks) { 1729 /* unknown += K|X */ 1730 return evaluate_reg_alu(env, insn); 1731 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 1732 dst_reg->type == CONST_IMM && 1733 env->allow_ptr_leaks) { 1734 /* reg_imm += K|X */ 1735 return evaluate_reg_imm_alu(env, insn); 1736 } else if (is_pointer_value(env, insn->dst_reg)) { 1737 verbose("R%d pointer arithmetic prohibited\n", 1738 insn->dst_reg); 1739 return -EACCES; 1740 } else if (BPF_SRC(insn->code) == BPF_X && 1741 is_pointer_value(env, insn->src_reg)) { 1742 verbose("R%d pointer arithmetic prohibited\n", 1743 insn->src_reg); 1744 return -EACCES; 1745 } 1746 1747 /* If we did pointer math on a map value then just set it to our 1748 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or 1749 * loads to this register appropriately, otherwise just mark the 1750 * register as unknown. 1751 */ 1752 if (env->allow_ptr_leaks && 1753 (dst_reg->type == PTR_TO_MAP_VALUE || 1754 dst_reg->type == PTR_TO_MAP_VALUE_ADJ)) 1755 dst_reg->type = PTR_TO_MAP_VALUE_ADJ; 1756 else 1757 mark_reg_unknown_value(regs, insn->dst_reg); 1758 } 1759 1760 return 0; 1761 } 1762 1763 static void find_good_pkt_pointers(struct bpf_verifier_state *state, 1764 struct bpf_reg_state *dst_reg) 1765 { 1766 struct bpf_reg_state *regs = state->regs, *reg; 1767 int i; 1768 1769 /* LLVM can generate two kind of checks: 1770 * 1771 * Type 1: 1772 * 1773 * r2 = r3; 1774 * r2 += 8; 1775 * if (r2 > pkt_end) goto <handle exception> 1776 * <access okay> 1777 * 1778 * Where: 1779 * r2 == dst_reg, pkt_end == src_reg 1780 * r2=pkt(id=n,off=8,r=0) 1781 * r3=pkt(id=n,off=0,r=0) 1782 * 1783 * Type 2: 1784 * 1785 * r2 = r3; 1786 * r2 += 8; 1787 * if (pkt_end >= r2) goto <access okay> 1788 * <handle exception> 1789 * 1790 * Where: 1791 * pkt_end == dst_reg, r2 == src_reg 1792 * r2=pkt(id=n,off=8,r=0) 1793 * r3=pkt(id=n,off=0,r=0) 1794 * 1795 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) 1796 * so that range of bytes [r3, r3 + 8) is safe to access. 1797 */ 1798 1799 for (i = 0; i < MAX_BPF_REG; i++) 1800 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) 1801 regs[i].range = dst_reg->off; 1802 1803 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 1804 if (state->stack_slot_type[i] != STACK_SPILL) 1805 continue; 1806 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 1807 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) 1808 reg->range = dst_reg->off; 1809 } 1810 } 1811 1812 /* Adjusts the register min/max values in the case that the dst_reg is the 1813 * variable register that we are working on, and src_reg is a constant or we're 1814 * simply doing a BPF_K check. 1815 */ 1816 static void reg_set_min_max(struct bpf_reg_state *true_reg, 1817 struct bpf_reg_state *false_reg, u64 val, 1818 u8 opcode) 1819 { 1820 switch (opcode) { 1821 case BPF_JEQ: 1822 /* If this is false then we know nothing Jon Snow, but if it is 1823 * true then we know for sure. 1824 */ 1825 true_reg->max_value = true_reg->min_value = val; 1826 break; 1827 case BPF_JNE: 1828 /* If this is true we know nothing Jon Snow, but if it is false 1829 * we know the value for sure; 1830 */ 1831 false_reg->max_value = false_reg->min_value = val; 1832 break; 1833 case BPF_JGT: 1834 /* Unsigned comparison, the minimum value is 0. */ 1835 false_reg->min_value = 0; 1836 case BPF_JSGT: 1837 /* If this is false then we know the maximum val is val, 1838 * otherwise we know the min val is val+1. 1839 */ 1840 false_reg->max_value = val; 1841 true_reg->min_value = val + 1; 1842 break; 1843 case BPF_JGE: 1844 /* Unsigned comparison, the minimum value is 0. */ 1845 false_reg->min_value = 0; 1846 case BPF_JSGE: 1847 /* If this is false then we know the maximum value is val - 1, 1848 * otherwise we know the mimimum value is val. 1849 */ 1850 false_reg->max_value = val - 1; 1851 true_reg->min_value = val; 1852 break; 1853 default: 1854 break; 1855 } 1856 1857 check_reg_overflow(false_reg); 1858 check_reg_overflow(true_reg); 1859 } 1860 1861 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg 1862 * is the variable reg. 1863 */ 1864 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, 1865 struct bpf_reg_state *false_reg, u64 val, 1866 u8 opcode) 1867 { 1868 switch (opcode) { 1869 case BPF_JEQ: 1870 /* If this is false then we know nothing Jon Snow, but if it is 1871 * true then we know for sure. 1872 */ 1873 true_reg->max_value = true_reg->min_value = val; 1874 break; 1875 case BPF_JNE: 1876 /* If this is true we know nothing Jon Snow, but if it is false 1877 * we know the value for sure; 1878 */ 1879 false_reg->max_value = false_reg->min_value = val; 1880 break; 1881 case BPF_JGT: 1882 /* Unsigned comparison, the minimum value is 0. */ 1883 true_reg->min_value = 0; 1884 case BPF_JSGT: 1885 /* 1886 * If this is false, then the val is <= the register, if it is 1887 * true the register <= to the val. 1888 */ 1889 false_reg->min_value = val; 1890 true_reg->max_value = val - 1; 1891 break; 1892 case BPF_JGE: 1893 /* Unsigned comparison, the minimum value is 0. */ 1894 true_reg->min_value = 0; 1895 case BPF_JSGE: 1896 /* If this is false then constant < register, if it is true then 1897 * the register < constant. 1898 */ 1899 false_reg->min_value = val + 1; 1900 true_reg->max_value = val; 1901 break; 1902 default: 1903 break; 1904 } 1905 1906 check_reg_overflow(false_reg); 1907 check_reg_overflow(true_reg); 1908 } 1909 1910 static int check_cond_jmp_op(struct bpf_verifier_env *env, 1911 struct bpf_insn *insn, int *insn_idx) 1912 { 1913 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; 1914 struct bpf_reg_state *regs = this_branch->regs, *dst_reg; 1915 u8 opcode = BPF_OP(insn->code); 1916 int err; 1917 1918 if (opcode > BPF_EXIT) { 1919 verbose("invalid BPF_JMP opcode %x\n", opcode); 1920 return -EINVAL; 1921 } 1922 1923 if (BPF_SRC(insn->code) == BPF_X) { 1924 if (insn->imm != 0) { 1925 verbose("BPF_JMP uses reserved fields\n"); 1926 return -EINVAL; 1927 } 1928 1929 /* check src1 operand */ 1930 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1931 if (err) 1932 return err; 1933 1934 if (is_pointer_value(env, insn->src_reg)) { 1935 verbose("R%d pointer comparison prohibited\n", 1936 insn->src_reg); 1937 return -EACCES; 1938 } 1939 } else { 1940 if (insn->src_reg != BPF_REG_0) { 1941 verbose("BPF_JMP uses reserved fields\n"); 1942 return -EINVAL; 1943 } 1944 } 1945 1946 /* check src2 operand */ 1947 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1948 if (err) 1949 return err; 1950 1951 dst_reg = ®s[insn->dst_reg]; 1952 1953 /* detect if R == 0 where R was initialized to zero earlier */ 1954 if (BPF_SRC(insn->code) == BPF_K && 1955 (opcode == BPF_JEQ || opcode == BPF_JNE) && 1956 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { 1957 if (opcode == BPF_JEQ) { 1958 /* if (imm == imm) goto pc+off; 1959 * only follow the goto, ignore fall-through 1960 */ 1961 *insn_idx += insn->off; 1962 return 0; 1963 } else { 1964 /* if (imm != imm) goto pc+off; 1965 * only follow fall-through branch, since 1966 * that's where the program will go 1967 */ 1968 return 0; 1969 } 1970 } 1971 1972 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); 1973 if (!other_branch) 1974 return -EFAULT; 1975 1976 /* detect if we are comparing against a constant value so we can adjust 1977 * our min/max values for our dst register. 1978 */ 1979 if (BPF_SRC(insn->code) == BPF_X) { 1980 if (regs[insn->src_reg].type == CONST_IMM) 1981 reg_set_min_max(&other_branch->regs[insn->dst_reg], 1982 dst_reg, regs[insn->src_reg].imm, 1983 opcode); 1984 else if (dst_reg->type == CONST_IMM) 1985 reg_set_min_max_inv(&other_branch->regs[insn->src_reg], 1986 ®s[insn->src_reg], dst_reg->imm, 1987 opcode); 1988 } else { 1989 reg_set_min_max(&other_branch->regs[insn->dst_reg], 1990 dst_reg, insn->imm, opcode); 1991 } 1992 1993 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ 1994 if (BPF_SRC(insn->code) == BPF_K && 1995 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && 1996 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { 1997 if (opcode == BPF_JEQ) { 1998 /* next fallthrough insn can access memory via 1999 * this register 2000 */ 2001 regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; 2002 /* branch targer cannot access it, since reg == 0 */ 2003 mark_reg_unknown_value(other_branch->regs, 2004 insn->dst_reg); 2005 } else { 2006 other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; 2007 mark_reg_unknown_value(regs, insn->dst_reg); 2008 } 2009 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && 2010 dst_reg->type == PTR_TO_PACKET && 2011 regs[insn->src_reg].type == PTR_TO_PACKET_END) { 2012 find_good_pkt_pointers(this_branch, dst_reg); 2013 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && 2014 dst_reg->type == PTR_TO_PACKET_END && 2015 regs[insn->src_reg].type == PTR_TO_PACKET) { 2016 find_good_pkt_pointers(other_branch, ®s[insn->src_reg]); 2017 } else if (is_pointer_value(env, insn->dst_reg)) { 2018 verbose("R%d pointer comparison prohibited\n", insn->dst_reg); 2019 return -EACCES; 2020 } 2021 if (log_level) 2022 print_verifier_state(this_branch); 2023 return 0; 2024 } 2025 2026 /* return the map pointer stored inside BPF_LD_IMM64 instruction */ 2027 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) 2028 { 2029 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; 2030 2031 return (struct bpf_map *) (unsigned long) imm64; 2032 } 2033 2034 /* verify BPF_LD_IMM64 instruction */ 2035 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) 2036 { 2037 struct bpf_reg_state *regs = env->cur_state.regs; 2038 int err; 2039 2040 if (BPF_SIZE(insn->code) != BPF_DW) { 2041 verbose("invalid BPF_LD_IMM insn\n"); 2042 return -EINVAL; 2043 } 2044 if (insn->off != 0) { 2045 verbose("BPF_LD_IMM64 uses reserved fields\n"); 2046 return -EINVAL; 2047 } 2048 2049 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 2050 if (err) 2051 return err; 2052 2053 if (insn->src_reg == 0) { 2054 /* generic move 64-bit immediate into a register, 2055 * only analyzer needs to collect the ld_imm value. 2056 */ 2057 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; 2058 2059 if (!env->analyzer_ops) 2060 return 0; 2061 2062 regs[insn->dst_reg].type = CONST_IMM; 2063 regs[insn->dst_reg].imm = imm; 2064 return 0; 2065 } 2066 2067 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ 2068 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); 2069 2070 regs[insn->dst_reg].type = CONST_PTR_TO_MAP; 2071 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); 2072 return 0; 2073 } 2074 2075 static bool may_access_skb(enum bpf_prog_type type) 2076 { 2077 switch (type) { 2078 case BPF_PROG_TYPE_SOCKET_FILTER: 2079 case BPF_PROG_TYPE_SCHED_CLS: 2080 case BPF_PROG_TYPE_SCHED_ACT: 2081 return true; 2082 default: 2083 return false; 2084 } 2085 } 2086 2087 /* verify safety of LD_ABS|LD_IND instructions: 2088 * - they can only appear in the programs where ctx == skb 2089 * - since they are wrappers of function calls, they scratch R1-R5 registers, 2090 * preserve R6-R9, and store return value into R0 2091 * 2092 * Implicit input: 2093 * ctx == skb == R6 == CTX 2094 * 2095 * Explicit input: 2096 * SRC == any register 2097 * IMM == 32-bit immediate 2098 * 2099 * Output: 2100 * R0 - 8/16/32-bit skb data converted to cpu endianness 2101 */ 2102 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) 2103 { 2104 struct bpf_reg_state *regs = env->cur_state.regs; 2105 u8 mode = BPF_MODE(insn->code); 2106 struct bpf_reg_state *reg; 2107 int i, err; 2108 2109 if (!may_access_skb(env->prog->type)) { 2110 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); 2111 return -EINVAL; 2112 } 2113 2114 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || 2115 BPF_SIZE(insn->code) == BPF_DW || 2116 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { 2117 verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); 2118 return -EINVAL; 2119 } 2120 2121 /* check whether implicit source operand (register R6) is readable */ 2122 err = check_reg_arg(regs, BPF_REG_6, SRC_OP); 2123 if (err) 2124 return err; 2125 2126 if (regs[BPF_REG_6].type != PTR_TO_CTX) { 2127 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); 2128 return -EINVAL; 2129 } 2130 2131 if (mode == BPF_IND) { 2132 /* check explicit source operand */ 2133 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2134 if (err) 2135 return err; 2136 } 2137 2138 /* reset caller saved regs to unreadable */ 2139 for (i = 0; i < CALLER_SAVED_REGS; i++) { 2140 reg = regs + caller_saved[i]; 2141 reg->type = NOT_INIT; 2142 reg->imm = 0; 2143 } 2144 2145 /* mark destination R0 register as readable, since it contains 2146 * the value fetched from the packet 2147 */ 2148 regs[BPF_REG_0].type = UNKNOWN_VALUE; 2149 return 0; 2150 } 2151 2152 /* non-recursive DFS pseudo code 2153 * 1 procedure DFS-iterative(G,v): 2154 * 2 label v as discovered 2155 * 3 let S be a stack 2156 * 4 S.push(v) 2157 * 5 while S is not empty 2158 * 6 t <- S.pop() 2159 * 7 if t is what we're looking for: 2160 * 8 return t 2161 * 9 for all edges e in G.adjacentEdges(t) do 2162 * 10 if edge e is already labelled 2163 * 11 continue with the next edge 2164 * 12 w <- G.adjacentVertex(t,e) 2165 * 13 if vertex w is not discovered and not explored 2166 * 14 label e as tree-edge 2167 * 15 label w as discovered 2168 * 16 S.push(w) 2169 * 17 continue at 5 2170 * 18 else if vertex w is discovered 2171 * 19 label e as back-edge 2172 * 20 else 2173 * 21 // vertex w is explored 2174 * 22 label e as forward- or cross-edge 2175 * 23 label t as explored 2176 * 24 S.pop() 2177 * 2178 * convention: 2179 * 0x10 - discovered 2180 * 0x11 - discovered and fall-through edge labelled 2181 * 0x12 - discovered and fall-through and branch edges labelled 2182 * 0x20 - explored 2183 */ 2184 2185 enum { 2186 DISCOVERED = 0x10, 2187 EXPLORED = 0x20, 2188 FALLTHROUGH = 1, 2189 BRANCH = 2, 2190 }; 2191 2192 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) 2193 2194 static int *insn_stack; /* stack of insns to process */ 2195 static int cur_stack; /* current stack index */ 2196 static int *insn_state; 2197 2198 /* t, w, e - match pseudo-code above: 2199 * t - index of current instruction 2200 * w - next instruction 2201 * e - edge 2202 */ 2203 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) 2204 { 2205 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) 2206 return 0; 2207 2208 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) 2209 return 0; 2210 2211 if (w < 0 || w >= env->prog->len) { 2212 verbose("jump out of range from insn %d to %d\n", t, w); 2213 return -EINVAL; 2214 } 2215 2216 if (e == BRANCH) 2217 /* mark branch target for state pruning */ 2218 env->explored_states[w] = STATE_LIST_MARK; 2219 2220 if (insn_state[w] == 0) { 2221 /* tree-edge */ 2222 insn_state[t] = DISCOVERED | e; 2223 insn_state[w] = DISCOVERED; 2224 if (cur_stack >= env->prog->len) 2225 return -E2BIG; 2226 insn_stack[cur_stack++] = w; 2227 return 1; 2228 } else if ((insn_state[w] & 0xF0) == DISCOVERED) { 2229 verbose("back-edge from insn %d to %d\n", t, w); 2230 return -EINVAL; 2231 } else if (insn_state[w] == EXPLORED) { 2232 /* forward- or cross-edge */ 2233 insn_state[t] = DISCOVERED | e; 2234 } else { 2235 verbose("insn state internal bug\n"); 2236 return -EFAULT; 2237 } 2238 return 0; 2239 } 2240 2241 /* non-recursive depth-first-search to detect loops in BPF program 2242 * loop == back-edge in directed graph 2243 */ 2244 static int check_cfg(struct bpf_verifier_env *env) 2245 { 2246 struct bpf_insn *insns = env->prog->insnsi; 2247 int insn_cnt = env->prog->len; 2248 int ret = 0; 2249 int i, t; 2250 2251 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2252 if (!insn_state) 2253 return -ENOMEM; 2254 2255 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2256 if (!insn_stack) { 2257 kfree(insn_state); 2258 return -ENOMEM; 2259 } 2260 2261 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ 2262 insn_stack[0] = 0; /* 0 is the first instruction */ 2263 cur_stack = 1; 2264 2265 peek_stack: 2266 if (cur_stack == 0) 2267 goto check_state; 2268 t = insn_stack[cur_stack - 1]; 2269 2270 if (BPF_CLASS(insns[t].code) == BPF_JMP) { 2271 u8 opcode = BPF_OP(insns[t].code); 2272 2273 if (opcode == BPF_EXIT) { 2274 goto mark_explored; 2275 } else if (opcode == BPF_CALL) { 2276 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2277 if (ret == 1) 2278 goto peek_stack; 2279 else if (ret < 0) 2280 goto err_free; 2281 if (t + 1 < insn_cnt) 2282 env->explored_states[t + 1] = STATE_LIST_MARK; 2283 } else if (opcode == BPF_JA) { 2284 if (BPF_SRC(insns[t].code) != BPF_K) { 2285 ret = -EINVAL; 2286 goto err_free; 2287 } 2288 /* unconditional jump with single edge */ 2289 ret = push_insn(t, t + insns[t].off + 1, 2290 FALLTHROUGH, env); 2291 if (ret == 1) 2292 goto peek_stack; 2293 else if (ret < 0) 2294 goto err_free; 2295 /* tell verifier to check for equivalent states 2296 * after every call and jump 2297 */ 2298 if (t + 1 < insn_cnt) 2299 env->explored_states[t + 1] = STATE_LIST_MARK; 2300 } else { 2301 /* conditional jump with two edges */ 2302 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2303 if (ret == 1) 2304 goto peek_stack; 2305 else if (ret < 0) 2306 goto err_free; 2307 2308 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); 2309 if (ret == 1) 2310 goto peek_stack; 2311 else if (ret < 0) 2312 goto err_free; 2313 } 2314 } else { 2315 /* all other non-branch instructions with single 2316 * fall-through edge 2317 */ 2318 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2319 if (ret == 1) 2320 goto peek_stack; 2321 else if (ret < 0) 2322 goto err_free; 2323 } 2324 2325 mark_explored: 2326 insn_state[t] = EXPLORED; 2327 if (cur_stack-- <= 0) { 2328 verbose("pop stack internal bug\n"); 2329 ret = -EFAULT; 2330 goto err_free; 2331 } 2332 goto peek_stack; 2333 2334 check_state: 2335 for (i = 0; i < insn_cnt; i++) { 2336 if (insn_state[i] != EXPLORED) { 2337 verbose("unreachable insn %d\n", i); 2338 ret = -EINVAL; 2339 goto err_free; 2340 } 2341 } 2342 ret = 0; /* cfg looks good */ 2343 2344 err_free: 2345 kfree(insn_state); 2346 kfree(insn_stack); 2347 return ret; 2348 } 2349 2350 /* the following conditions reduce the number of explored insns 2351 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet 2352 */ 2353 static bool compare_ptrs_to_packet(struct bpf_reg_state *old, 2354 struct bpf_reg_state *cur) 2355 { 2356 if (old->id != cur->id) 2357 return false; 2358 2359 /* old ptr_to_packet is more conservative, since it allows smaller 2360 * range. Ex: 2361 * old(off=0,r=10) is equal to cur(off=0,r=20), because 2362 * old(off=0,r=10) means that with range=10 the verifier proceeded 2363 * further and found no issues with the program. Now we're in the same 2364 * spot with cur(off=0,r=20), so we're safe too, since anything further 2365 * will only be looking at most 10 bytes after this pointer. 2366 */ 2367 if (old->off == cur->off && old->range < cur->range) 2368 return true; 2369 2370 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) 2371 * since both cannot be used for packet access and safe(old) 2372 * pointer has smaller off that could be used for further 2373 * 'if (ptr > data_end)' check 2374 * Ex: 2375 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean 2376 * that we cannot access the packet. 2377 * The safe range is: 2378 * [ptr, ptr + range - off) 2379 * so whenever off >=range, it means no safe bytes from this pointer. 2380 * When comparing old->off <= cur->off, it means that older code 2381 * went with smaller offset and that offset was later 2382 * used to figure out the safe range after 'if (ptr > data_end)' check 2383 * Say, 'old' state was explored like: 2384 * ... R3(off=0, r=0) 2385 * R4 = R3 + 20 2386 * ... now R4(off=20,r=0) <-- here 2387 * if (R4 > data_end) 2388 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. 2389 * ... the code further went all the way to bpf_exit. 2390 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). 2391 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier 2392 * goes further, such cur_R4 will give larger safe packet range after 2393 * 'if (R4 > data_end)' and all further insn were already good with r=20, 2394 * so they will be good with r=30 and we can prune the search. 2395 */ 2396 if (old->off <= cur->off && 2397 old->off >= old->range && cur->off >= cur->range) 2398 return true; 2399 2400 return false; 2401 } 2402 2403 /* compare two verifier states 2404 * 2405 * all states stored in state_list are known to be valid, since 2406 * verifier reached 'bpf_exit' instruction through them 2407 * 2408 * this function is called when verifier exploring different branches of 2409 * execution popped from the state stack. If it sees an old state that has 2410 * more strict register state and more strict stack state then this execution 2411 * branch doesn't need to be explored further, since verifier already 2412 * concluded that more strict state leads to valid finish. 2413 * 2414 * Therefore two states are equivalent if register state is more conservative 2415 * and explored stack state is more conservative than the current one. 2416 * Example: 2417 * explored current 2418 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) 2419 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) 2420 * 2421 * In other words if current stack state (one being explored) has more 2422 * valid slots than old one that already passed validation, it means 2423 * the verifier can stop exploring and conclude that current state is valid too 2424 * 2425 * Similarly with registers. If explored state has register type as invalid 2426 * whereas register type in current state is meaningful, it means that 2427 * the current state will reach 'bpf_exit' instruction safely 2428 */ 2429 static bool states_equal(struct bpf_verifier_env *env, 2430 struct bpf_verifier_state *old, 2431 struct bpf_verifier_state *cur) 2432 { 2433 struct bpf_reg_state *rold, *rcur; 2434 int i; 2435 2436 for (i = 0; i < MAX_BPF_REG; i++) { 2437 rold = &old->regs[i]; 2438 rcur = &cur->regs[i]; 2439 2440 if (memcmp(rold, rcur, sizeof(*rold)) == 0) 2441 continue; 2442 2443 /* If the ranges were not the same, but everything else was and 2444 * we didn't do a variable access into a map then we are a-ok. 2445 */ 2446 if (!env->varlen_map_value_access && 2447 rold->type == rcur->type && rold->imm == rcur->imm) 2448 continue; 2449 2450 if (rold->type == NOT_INIT || 2451 (rold->type == UNKNOWN_VALUE && rcur->type != NOT_INIT)) 2452 continue; 2453 2454 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && 2455 compare_ptrs_to_packet(rold, rcur)) 2456 continue; 2457 2458 return false; 2459 } 2460 2461 for (i = 0; i < MAX_BPF_STACK; i++) { 2462 if (old->stack_slot_type[i] == STACK_INVALID) 2463 continue; 2464 if (old->stack_slot_type[i] != cur->stack_slot_type[i]) 2465 /* Ex: old explored (safe) state has STACK_SPILL in 2466 * this stack slot, but current has has STACK_MISC -> 2467 * this verifier states are not equivalent, 2468 * return false to continue verification of this path 2469 */ 2470 return false; 2471 if (i % BPF_REG_SIZE) 2472 continue; 2473 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], 2474 &cur->spilled_regs[i / BPF_REG_SIZE], 2475 sizeof(old->spilled_regs[0]))) 2476 /* when explored and current stack slot types are 2477 * the same, check that stored pointers types 2478 * are the same as well. 2479 * Ex: explored safe path could have stored 2480 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8} 2481 * but current path has stored: 2482 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16} 2483 * such verifier states are not equivalent. 2484 * return false to continue verification of this path 2485 */ 2486 return false; 2487 else 2488 continue; 2489 } 2490 return true; 2491 } 2492 2493 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) 2494 { 2495 struct bpf_verifier_state_list *new_sl; 2496 struct bpf_verifier_state_list *sl; 2497 2498 sl = env->explored_states[insn_idx]; 2499 if (!sl) 2500 /* this 'insn_idx' instruction wasn't marked, so we will not 2501 * be doing state search here 2502 */ 2503 return 0; 2504 2505 while (sl != STATE_LIST_MARK) { 2506 if (states_equal(env, &sl->state, &env->cur_state)) 2507 /* reached equivalent register/stack state, 2508 * prune the search 2509 */ 2510 return 1; 2511 sl = sl->next; 2512 } 2513 2514 /* there were no equivalent states, remember current one. 2515 * technically the current state is not proven to be safe yet, 2516 * but it will either reach bpf_exit (which means it's safe) or 2517 * it will be rejected. Since there are no loops, we won't be 2518 * seeing this 'insn_idx' instruction again on the way to bpf_exit 2519 */ 2520 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); 2521 if (!new_sl) 2522 return -ENOMEM; 2523 2524 /* add new state to the head of linked list */ 2525 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); 2526 new_sl->next = env->explored_states[insn_idx]; 2527 env->explored_states[insn_idx] = new_sl; 2528 return 0; 2529 } 2530 2531 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, 2532 int insn_idx, int prev_insn_idx) 2533 { 2534 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) 2535 return 0; 2536 2537 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); 2538 } 2539 2540 static int do_check(struct bpf_verifier_env *env) 2541 { 2542 struct bpf_verifier_state *state = &env->cur_state; 2543 struct bpf_insn *insns = env->prog->insnsi; 2544 struct bpf_reg_state *regs = state->regs; 2545 int insn_cnt = env->prog->len; 2546 int insn_idx, prev_insn_idx = 0; 2547 int insn_processed = 0; 2548 bool do_print_state = false; 2549 2550 init_reg_state(regs); 2551 insn_idx = 0; 2552 env->varlen_map_value_access = false; 2553 for (;;) { 2554 struct bpf_insn *insn; 2555 u8 class; 2556 int err; 2557 2558 if (insn_idx >= insn_cnt) { 2559 verbose("invalid insn idx %d insn_cnt %d\n", 2560 insn_idx, insn_cnt); 2561 return -EFAULT; 2562 } 2563 2564 insn = &insns[insn_idx]; 2565 class = BPF_CLASS(insn->code); 2566 2567 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { 2568 verbose("BPF program is too large. Proccessed %d insn\n", 2569 insn_processed); 2570 return -E2BIG; 2571 } 2572 2573 err = is_state_visited(env, insn_idx); 2574 if (err < 0) 2575 return err; 2576 if (err == 1) { 2577 /* found equivalent state, can prune the search */ 2578 if (log_level) { 2579 if (do_print_state) 2580 verbose("\nfrom %d to %d: safe\n", 2581 prev_insn_idx, insn_idx); 2582 else 2583 verbose("%d: safe\n", insn_idx); 2584 } 2585 goto process_bpf_exit; 2586 } 2587 2588 if (log_level && do_print_state) { 2589 verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx); 2590 print_verifier_state(&env->cur_state); 2591 do_print_state = false; 2592 } 2593 2594 if (log_level) { 2595 verbose("%d: ", insn_idx); 2596 print_bpf_insn(insn); 2597 } 2598 2599 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); 2600 if (err) 2601 return err; 2602 2603 if (class == BPF_ALU || class == BPF_ALU64) { 2604 err = check_alu_op(env, insn); 2605 if (err) 2606 return err; 2607 2608 } else if (class == BPF_LDX) { 2609 enum bpf_reg_type *prev_src_type, src_reg_type; 2610 2611 /* check for reserved fields is already done */ 2612 2613 /* check src operand */ 2614 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2615 if (err) 2616 return err; 2617 2618 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 2619 if (err) 2620 return err; 2621 2622 src_reg_type = regs[insn->src_reg].type; 2623 2624 /* check that memory (src_reg + off) is readable, 2625 * the state of dst_reg will be updated by this func 2626 */ 2627 err = check_mem_access(env, insn->src_reg, insn->off, 2628 BPF_SIZE(insn->code), BPF_READ, 2629 insn->dst_reg); 2630 if (err) 2631 return err; 2632 2633 reset_reg_range_values(regs, insn->dst_reg); 2634 if (BPF_SIZE(insn->code) != BPF_W && 2635 BPF_SIZE(insn->code) != BPF_DW) { 2636 insn_idx++; 2637 continue; 2638 } 2639 2640 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; 2641 2642 if (*prev_src_type == NOT_INIT) { 2643 /* saw a valid insn 2644 * dst_reg = *(u32 *)(src_reg + off) 2645 * save type to validate intersecting paths 2646 */ 2647 *prev_src_type = src_reg_type; 2648 2649 } else if (src_reg_type != *prev_src_type && 2650 (src_reg_type == PTR_TO_CTX || 2651 *prev_src_type == PTR_TO_CTX)) { 2652 /* ABuser program is trying to use the same insn 2653 * dst_reg = *(u32*) (src_reg + off) 2654 * with different pointer types: 2655 * src_reg == ctx in one branch and 2656 * src_reg == stack|map in some other branch. 2657 * Reject it. 2658 */ 2659 verbose("same insn cannot be used with different pointers\n"); 2660 return -EINVAL; 2661 } 2662 2663 } else if (class == BPF_STX) { 2664 enum bpf_reg_type *prev_dst_type, dst_reg_type; 2665 2666 if (BPF_MODE(insn->code) == BPF_XADD) { 2667 err = check_xadd(env, insn); 2668 if (err) 2669 return err; 2670 insn_idx++; 2671 continue; 2672 } 2673 2674 /* check src1 operand */ 2675 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2676 if (err) 2677 return err; 2678 /* check src2 operand */ 2679 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 2680 if (err) 2681 return err; 2682 2683 dst_reg_type = regs[insn->dst_reg].type; 2684 2685 /* check that memory (dst_reg + off) is writeable */ 2686 err = check_mem_access(env, insn->dst_reg, insn->off, 2687 BPF_SIZE(insn->code), BPF_WRITE, 2688 insn->src_reg); 2689 if (err) 2690 return err; 2691 2692 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; 2693 2694 if (*prev_dst_type == NOT_INIT) { 2695 *prev_dst_type = dst_reg_type; 2696 } else if (dst_reg_type != *prev_dst_type && 2697 (dst_reg_type == PTR_TO_CTX || 2698 *prev_dst_type == PTR_TO_CTX)) { 2699 verbose("same insn cannot be used with different pointers\n"); 2700 return -EINVAL; 2701 } 2702 2703 } else if (class == BPF_ST) { 2704 if (BPF_MODE(insn->code) != BPF_MEM || 2705 insn->src_reg != BPF_REG_0) { 2706 verbose("BPF_ST uses reserved fields\n"); 2707 return -EINVAL; 2708 } 2709 /* check src operand */ 2710 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 2711 if (err) 2712 return err; 2713 2714 /* check that memory (dst_reg + off) is writeable */ 2715 err = check_mem_access(env, insn->dst_reg, insn->off, 2716 BPF_SIZE(insn->code), BPF_WRITE, 2717 -1); 2718 if (err) 2719 return err; 2720 2721 } else if (class == BPF_JMP) { 2722 u8 opcode = BPF_OP(insn->code); 2723 2724 if (opcode == BPF_CALL) { 2725 if (BPF_SRC(insn->code) != BPF_K || 2726 insn->off != 0 || 2727 insn->src_reg != BPF_REG_0 || 2728 insn->dst_reg != BPF_REG_0) { 2729 verbose("BPF_CALL uses reserved fields\n"); 2730 return -EINVAL; 2731 } 2732 2733 err = check_call(env, insn->imm); 2734 if (err) 2735 return err; 2736 2737 } else if (opcode == BPF_JA) { 2738 if (BPF_SRC(insn->code) != BPF_K || 2739 insn->imm != 0 || 2740 insn->src_reg != BPF_REG_0 || 2741 insn->dst_reg != BPF_REG_0) { 2742 verbose("BPF_JA uses reserved fields\n"); 2743 return -EINVAL; 2744 } 2745 2746 insn_idx += insn->off + 1; 2747 continue; 2748 2749 } else if (opcode == BPF_EXIT) { 2750 if (BPF_SRC(insn->code) != BPF_K || 2751 insn->imm != 0 || 2752 insn->src_reg != BPF_REG_0 || 2753 insn->dst_reg != BPF_REG_0) { 2754 verbose("BPF_EXIT uses reserved fields\n"); 2755 return -EINVAL; 2756 } 2757 2758 /* eBPF calling convetion is such that R0 is used 2759 * to return the value from eBPF program. 2760 * Make sure that it's readable at this time 2761 * of bpf_exit, which means that program wrote 2762 * something into it earlier 2763 */ 2764 err = check_reg_arg(regs, BPF_REG_0, SRC_OP); 2765 if (err) 2766 return err; 2767 2768 if (is_pointer_value(env, BPF_REG_0)) { 2769 verbose("R0 leaks addr as return value\n"); 2770 return -EACCES; 2771 } 2772 2773 process_bpf_exit: 2774 insn_idx = pop_stack(env, &prev_insn_idx); 2775 if (insn_idx < 0) { 2776 break; 2777 } else { 2778 do_print_state = true; 2779 continue; 2780 } 2781 } else { 2782 err = check_cond_jmp_op(env, insn, &insn_idx); 2783 if (err) 2784 return err; 2785 } 2786 } else if (class == BPF_LD) { 2787 u8 mode = BPF_MODE(insn->code); 2788 2789 if (mode == BPF_ABS || mode == BPF_IND) { 2790 err = check_ld_abs(env, insn); 2791 if (err) 2792 return err; 2793 2794 } else if (mode == BPF_IMM) { 2795 err = check_ld_imm(env, insn); 2796 if (err) 2797 return err; 2798 2799 insn_idx++; 2800 } else { 2801 verbose("invalid BPF_LD mode\n"); 2802 return -EINVAL; 2803 } 2804 reset_reg_range_values(regs, insn->dst_reg); 2805 } else { 2806 verbose("unknown insn class %d\n", class); 2807 return -EINVAL; 2808 } 2809 2810 insn_idx++; 2811 } 2812 2813 verbose("processed %d insns\n", insn_processed); 2814 return 0; 2815 } 2816 2817 static int check_map_prog_compatibility(struct bpf_map *map, 2818 struct bpf_prog *prog) 2819 2820 { 2821 if (prog->type == BPF_PROG_TYPE_PERF_EVENT && 2822 (map->map_type == BPF_MAP_TYPE_HASH || 2823 map->map_type == BPF_MAP_TYPE_PERCPU_HASH) && 2824 (map->map_flags & BPF_F_NO_PREALLOC)) { 2825 verbose("perf_event programs can only use preallocated hash map\n"); 2826 return -EINVAL; 2827 } 2828 return 0; 2829 } 2830 2831 /* look for pseudo eBPF instructions that access map FDs and 2832 * replace them with actual map pointers 2833 */ 2834 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) 2835 { 2836 struct bpf_insn *insn = env->prog->insnsi; 2837 int insn_cnt = env->prog->len; 2838 int i, j, err; 2839 2840 for (i = 0; i < insn_cnt; i++, insn++) { 2841 if (BPF_CLASS(insn->code) == BPF_LDX && 2842 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { 2843 verbose("BPF_LDX uses reserved fields\n"); 2844 return -EINVAL; 2845 } 2846 2847 if (BPF_CLASS(insn->code) == BPF_STX && 2848 ((BPF_MODE(insn->code) != BPF_MEM && 2849 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { 2850 verbose("BPF_STX uses reserved fields\n"); 2851 return -EINVAL; 2852 } 2853 2854 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { 2855 struct bpf_map *map; 2856 struct fd f; 2857 2858 if (i == insn_cnt - 1 || insn[1].code != 0 || 2859 insn[1].dst_reg != 0 || insn[1].src_reg != 0 || 2860 insn[1].off != 0) { 2861 verbose("invalid bpf_ld_imm64 insn\n"); 2862 return -EINVAL; 2863 } 2864 2865 if (insn->src_reg == 0) 2866 /* valid generic load 64-bit imm */ 2867 goto next_insn; 2868 2869 if (insn->src_reg != BPF_PSEUDO_MAP_FD) { 2870 verbose("unrecognized bpf_ld_imm64 insn\n"); 2871 return -EINVAL; 2872 } 2873 2874 f = fdget(insn->imm); 2875 map = __bpf_map_get(f); 2876 if (IS_ERR(map)) { 2877 verbose("fd %d is not pointing to valid bpf_map\n", 2878 insn->imm); 2879 return PTR_ERR(map); 2880 } 2881 2882 err = check_map_prog_compatibility(map, env->prog); 2883 if (err) { 2884 fdput(f); 2885 return err; 2886 } 2887 2888 /* store map pointer inside BPF_LD_IMM64 instruction */ 2889 insn[0].imm = (u32) (unsigned long) map; 2890 insn[1].imm = ((u64) (unsigned long) map) >> 32; 2891 2892 /* check whether we recorded this map already */ 2893 for (j = 0; j < env->used_map_cnt; j++) 2894 if (env->used_maps[j] == map) { 2895 fdput(f); 2896 goto next_insn; 2897 } 2898 2899 if (env->used_map_cnt >= MAX_USED_MAPS) { 2900 fdput(f); 2901 return -E2BIG; 2902 } 2903 2904 /* hold the map. If the program is rejected by verifier, 2905 * the map will be released by release_maps() or it 2906 * will be used by the valid program until it's unloaded 2907 * and all maps are released in free_bpf_prog_info() 2908 */ 2909 map = bpf_map_inc(map, false); 2910 if (IS_ERR(map)) { 2911 fdput(f); 2912 return PTR_ERR(map); 2913 } 2914 env->used_maps[env->used_map_cnt++] = map; 2915 2916 fdput(f); 2917 next_insn: 2918 insn++; 2919 i++; 2920 } 2921 } 2922 2923 /* now all pseudo BPF_LD_IMM64 instructions load valid 2924 * 'struct bpf_map *' into a register instead of user map_fd. 2925 * These pointers will be used later by verifier to validate map access. 2926 */ 2927 return 0; 2928 } 2929 2930 /* drop refcnt of maps used by the rejected program */ 2931 static void release_maps(struct bpf_verifier_env *env) 2932 { 2933 int i; 2934 2935 for (i = 0; i < env->used_map_cnt; i++) 2936 bpf_map_put(env->used_maps[i]); 2937 } 2938 2939 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ 2940 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) 2941 { 2942 struct bpf_insn *insn = env->prog->insnsi; 2943 int insn_cnt = env->prog->len; 2944 int i; 2945 2946 for (i = 0; i < insn_cnt; i++, insn++) 2947 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) 2948 insn->src_reg = 0; 2949 } 2950 2951 /* convert load instructions that access fields of 'struct __sk_buff' 2952 * into sequence of instructions that access fields of 'struct sk_buff' 2953 */ 2954 static int convert_ctx_accesses(struct bpf_verifier_env *env) 2955 { 2956 const struct bpf_verifier_ops *ops = env->prog->aux->ops; 2957 const int insn_cnt = env->prog->len; 2958 struct bpf_insn insn_buf[16], *insn; 2959 struct bpf_prog *new_prog; 2960 enum bpf_access_type type; 2961 int i, cnt, delta = 0; 2962 2963 if (ops->gen_prologue) { 2964 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, 2965 env->prog); 2966 if (cnt >= ARRAY_SIZE(insn_buf)) { 2967 verbose("bpf verifier is misconfigured\n"); 2968 return -EINVAL; 2969 } else if (cnt) { 2970 new_prog = bpf_patch_insn_single(env->prog, 0, 2971 insn_buf, cnt); 2972 if (!new_prog) 2973 return -ENOMEM; 2974 env->prog = new_prog; 2975 delta += cnt - 1; 2976 } 2977 } 2978 2979 if (!ops->convert_ctx_access) 2980 return 0; 2981 2982 insn = env->prog->insnsi + delta; 2983 2984 for (i = 0; i < insn_cnt; i++, insn++) { 2985 if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) || 2986 insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) 2987 type = BPF_READ; 2988 else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) || 2989 insn->code == (BPF_STX | BPF_MEM | BPF_DW)) 2990 type = BPF_WRITE; 2991 else 2992 continue; 2993 2994 if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX) 2995 continue; 2996 2997 cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg, 2998 insn->off, insn_buf, env->prog); 2999 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { 3000 verbose("bpf verifier is misconfigured\n"); 3001 return -EINVAL; 3002 } 3003 3004 new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf, 3005 cnt); 3006 if (!new_prog) 3007 return -ENOMEM; 3008 3009 delta += cnt - 1; 3010 3011 /* keep walking new program and skip insns we just inserted */ 3012 env->prog = new_prog; 3013 insn = new_prog->insnsi + i + delta; 3014 } 3015 3016 return 0; 3017 } 3018 3019 static void free_states(struct bpf_verifier_env *env) 3020 { 3021 struct bpf_verifier_state_list *sl, *sln; 3022 int i; 3023 3024 if (!env->explored_states) 3025 return; 3026 3027 for (i = 0; i < env->prog->len; i++) { 3028 sl = env->explored_states[i]; 3029 3030 if (sl) 3031 while (sl != STATE_LIST_MARK) { 3032 sln = sl->next; 3033 kfree(sl); 3034 sl = sln; 3035 } 3036 } 3037 3038 kfree(env->explored_states); 3039 } 3040 3041 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) 3042 { 3043 char __user *log_ubuf = NULL; 3044 struct bpf_verifier_env *env; 3045 int ret = -EINVAL; 3046 3047 if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS) 3048 return -E2BIG; 3049 3050 /* 'struct bpf_verifier_env' can be global, but since it's not small, 3051 * allocate/free it every time bpf_check() is called 3052 */ 3053 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3054 if (!env) 3055 return -ENOMEM; 3056 3057 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3058 (*prog)->len); 3059 ret = -ENOMEM; 3060 if (!env->insn_aux_data) 3061 goto err_free_env; 3062 env->prog = *prog; 3063 3064 /* grab the mutex to protect few globals used by verifier */ 3065 mutex_lock(&bpf_verifier_lock); 3066 3067 if (attr->log_level || attr->log_buf || attr->log_size) { 3068 /* user requested verbose verifier output 3069 * and supplied buffer to store the verification trace 3070 */ 3071 log_level = attr->log_level; 3072 log_ubuf = (char __user *) (unsigned long) attr->log_buf; 3073 log_size = attr->log_size; 3074 log_len = 0; 3075 3076 ret = -EINVAL; 3077 /* log_* values have to be sane */ 3078 if (log_size < 128 || log_size > UINT_MAX >> 8 || 3079 log_level == 0 || log_ubuf == NULL) 3080 goto err_unlock; 3081 3082 ret = -ENOMEM; 3083 log_buf = vmalloc(log_size); 3084 if (!log_buf) 3085 goto err_unlock; 3086 } else { 3087 log_level = 0; 3088 } 3089 3090 ret = replace_map_fd_with_map_ptr(env); 3091 if (ret < 0) 3092 goto skip_full_check; 3093 3094 env->explored_states = kcalloc(env->prog->len, 3095 sizeof(struct bpf_verifier_state_list *), 3096 GFP_USER); 3097 ret = -ENOMEM; 3098 if (!env->explored_states) 3099 goto skip_full_check; 3100 3101 ret = check_cfg(env); 3102 if (ret < 0) 3103 goto skip_full_check; 3104 3105 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3106 3107 ret = do_check(env); 3108 3109 skip_full_check: 3110 while (pop_stack(env, NULL) >= 0); 3111 free_states(env); 3112 3113 if (ret == 0) 3114 /* program is valid, convert *(u32*)(ctx + off) accesses */ 3115 ret = convert_ctx_accesses(env); 3116 3117 if (log_level && log_len >= log_size - 1) { 3118 BUG_ON(log_len >= log_size); 3119 /* verifier log exceeded user supplied buffer */ 3120 ret = -ENOSPC; 3121 /* fall through to return what was recorded */ 3122 } 3123 3124 /* copy verifier log back to user space including trailing zero */ 3125 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { 3126 ret = -EFAULT; 3127 goto free_log_buf; 3128 } 3129 3130 if (ret == 0 && env->used_map_cnt) { 3131 /* if program passed verifier, update used_maps in bpf_prog_info */ 3132 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, 3133 sizeof(env->used_maps[0]), 3134 GFP_KERNEL); 3135 3136 if (!env->prog->aux->used_maps) { 3137 ret = -ENOMEM; 3138 goto free_log_buf; 3139 } 3140 3141 memcpy(env->prog->aux->used_maps, env->used_maps, 3142 sizeof(env->used_maps[0]) * env->used_map_cnt); 3143 env->prog->aux->used_map_cnt = env->used_map_cnt; 3144 3145 /* program is valid. Convert pseudo bpf_ld_imm64 into generic 3146 * bpf_ld_imm64 instructions 3147 */ 3148 convert_pseudo_ld_imm64(env); 3149 } 3150 3151 free_log_buf: 3152 if (log_level) 3153 vfree(log_buf); 3154 if (!env->prog->aux->used_maps) 3155 /* if we didn't copy map pointers into bpf_prog_info, release 3156 * them now. Otherwise free_bpf_prog_info() will release them. 3157 */ 3158 release_maps(env); 3159 *prog = env->prog; 3160 err_unlock: 3161 mutex_unlock(&bpf_verifier_lock); 3162 vfree(env->insn_aux_data); 3163 err_free_env: 3164 kfree(env); 3165 return ret; 3166 } 3167 3168 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, 3169 void *priv) 3170 { 3171 struct bpf_verifier_env *env; 3172 int ret; 3173 3174 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3175 if (!env) 3176 return -ENOMEM; 3177 3178 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3179 prog->len); 3180 ret = -ENOMEM; 3181 if (!env->insn_aux_data) 3182 goto err_free_env; 3183 env->prog = prog; 3184 env->analyzer_ops = ops; 3185 env->analyzer_priv = priv; 3186 3187 /* grab the mutex to protect few globals used by verifier */ 3188 mutex_lock(&bpf_verifier_lock); 3189 3190 log_level = 0; 3191 3192 env->explored_states = kcalloc(env->prog->len, 3193 sizeof(struct bpf_verifier_state_list *), 3194 GFP_KERNEL); 3195 ret = -ENOMEM; 3196 if (!env->explored_states) 3197 goto skip_full_check; 3198 3199 ret = check_cfg(env); 3200 if (ret < 0) 3201 goto skip_full_check; 3202 3203 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3204 3205 ret = do_check(env); 3206 3207 skip_full_check: 3208 while (pop_stack(env, NULL) >= 0); 3209 free_states(env); 3210 3211 mutex_unlock(&bpf_verifier_lock); 3212 vfree(env->insn_aux_data); 3213 err_free_env: 3214 kfree(env); 3215 return ret; 3216 } 3217 EXPORT_SYMBOL_GPL(bpf_analyzer); 3218