1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 2 * Copyright (c) 2016 Facebook 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of version 2 of the GNU General Public 6 * License as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, but 9 * WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 */ 13 #include <linux/kernel.h> 14 #include <linux/types.h> 15 #include <linux/slab.h> 16 #include <linux/bpf.h> 17 #include <linux/bpf_verifier.h> 18 #include <linux/filter.h> 19 #include <net/netlink.h> 20 #include <linux/file.h> 21 #include <linux/vmalloc.h> 22 #include <linux/stringify.h> 23 24 /* bpf_check() is a static code analyzer that walks eBPF program 25 * instruction by instruction and updates register/stack state. 26 * All paths of conditional branches are analyzed until 'bpf_exit' insn. 27 * 28 * The first pass is depth-first-search to check that the program is a DAG. 29 * It rejects the following programs: 30 * - larger than BPF_MAXINSNS insns 31 * - if loop is present (detected via back-edge) 32 * - unreachable insns exist (shouldn't be a forest. program = one function) 33 * - out of bounds or malformed jumps 34 * The second pass is all possible path descent from the 1st insn. 35 * Since it's analyzing all pathes through the program, the length of the 36 * analysis is limited to 64k insn, which may be hit even if total number of 37 * insn is less then 4K, but there are too many branches that change stack/regs. 38 * Number of 'branches to be analyzed' is limited to 1k 39 * 40 * On entry to each instruction, each register has a type, and the instruction 41 * changes the types of the registers depending on instruction semantics. 42 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is 43 * copied to R1. 44 * 45 * All registers are 64-bit. 46 * R0 - return register 47 * R1-R5 argument passing registers 48 * R6-R9 callee saved registers 49 * R10 - frame pointer read-only 50 * 51 * At the start of BPF program the register R1 contains a pointer to bpf_context 52 * and has type PTR_TO_CTX. 53 * 54 * Verifier tracks arithmetic operations on pointers in case: 55 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), 56 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), 57 * 1st insn copies R10 (which has FRAME_PTR) type into R1 58 * and 2nd arithmetic instruction is pattern matched to recognize 59 * that it wants to construct a pointer to some element within stack. 60 * So after 2nd insn, the register R1 has type PTR_TO_STACK 61 * (and -20 constant is saved for further stack bounds checking). 62 * Meaning that this reg is a pointer to stack plus known immediate constant. 63 * 64 * Most of the time the registers have UNKNOWN_VALUE type, which 65 * means the register has some value, but it's not a valid pointer. 66 * (like pointer plus pointer becomes UNKNOWN_VALUE type) 67 * 68 * When verifier sees load or store instructions the type of base register 69 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer 70 * types recognized by check_mem_access() function. 71 * 72 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' 73 * and the range of [ptr, ptr + map's value_size) is accessible. 74 * 75 * registers used to pass values to function calls are checked against 76 * function argument constraints. 77 * 78 * ARG_PTR_TO_MAP_KEY is one of such argument constraints. 79 * It means that the register type passed to this function must be 80 * PTR_TO_STACK and it will be used inside the function as 81 * 'pointer to map element key' 82 * 83 * For example the argument constraints for bpf_map_lookup_elem(): 84 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 85 * .arg1_type = ARG_CONST_MAP_PTR, 86 * .arg2_type = ARG_PTR_TO_MAP_KEY, 87 * 88 * ret_type says that this function returns 'pointer to map elem value or null' 89 * function expects 1st argument to be a const pointer to 'struct bpf_map' and 90 * 2nd argument should be a pointer to stack, which will be used inside 91 * the helper function as a pointer to map element key. 92 * 93 * On the kernel side the helper function looks like: 94 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 95 * { 96 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 97 * void *key = (void *) (unsigned long) r2; 98 * void *value; 99 * 100 * here kernel can access 'key' and 'map' pointers safely, knowing that 101 * [key, key + map->key_size) bytes are valid and were initialized on 102 * the stack of eBPF program. 103 * } 104 * 105 * Corresponding eBPF program may look like: 106 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR 107 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK 108 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP 109 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), 110 * here verifier looks at prototype of map_lookup_elem() and sees: 111 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, 112 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes 113 * 114 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, 115 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits 116 * and were initialized prior to this call. 117 * If it's ok, then verifier allows this BPF_CALL insn and looks at 118 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets 119 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function 120 * returns ether pointer to map value or NULL. 121 * 122 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' 123 * insn, the register holding that pointer in the true branch changes state to 124 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false 125 * branch. See check_cond_jmp_op(). 126 * 127 * After the call R0 is set to return type of the function and registers R1-R5 128 * are set to NOT_INIT to indicate that they are no longer readable. 129 */ 130 131 /* verifier_state + insn_idx are pushed to stack when branch is encountered */ 132 struct bpf_verifier_stack_elem { 133 /* verifer state is 'st' 134 * before processing instruction 'insn_idx' 135 * and after processing instruction 'prev_insn_idx' 136 */ 137 struct bpf_verifier_state st; 138 int insn_idx; 139 int prev_insn_idx; 140 struct bpf_verifier_stack_elem *next; 141 }; 142 143 #define BPF_COMPLEXITY_LIMIT_INSNS 98304 144 #define BPF_COMPLEXITY_LIMIT_STACK 1024 145 146 #define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA) 147 148 struct bpf_call_arg_meta { 149 struct bpf_map *map_ptr; 150 bool raw_mode; 151 bool pkt_access; 152 int regno; 153 int access_size; 154 }; 155 156 /* verbose verifier prints what it's seeing 157 * bpf_check() is called under lock, so no race to access these global vars 158 */ 159 static u32 log_level, log_size, log_len; 160 static char *log_buf; 161 162 static DEFINE_MUTEX(bpf_verifier_lock); 163 164 /* log_level controls verbosity level of eBPF verifier. 165 * verbose() is used to dump the verification trace to the log, so the user 166 * can figure out what's wrong with the program 167 */ 168 static __printf(1, 2) void verbose(const char *fmt, ...) 169 { 170 va_list args; 171 172 if (log_level == 0 || log_len >= log_size - 1) 173 return; 174 175 va_start(args, fmt); 176 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); 177 va_end(args); 178 } 179 180 /* string representation of 'enum bpf_reg_type' */ 181 static const char * const reg_type_str[] = { 182 [NOT_INIT] = "?", 183 [UNKNOWN_VALUE] = "inv", 184 [PTR_TO_CTX] = "ctx", 185 [CONST_PTR_TO_MAP] = "map_ptr", 186 [PTR_TO_MAP_VALUE] = "map_value", 187 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", 188 [PTR_TO_MAP_VALUE_ADJ] = "map_value_adj", 189 [FRAME_PTR] = "fp", 190 [PTR_TO_STACK] = "fp", 191 [CONST_IMM] = "imm", 192 [PTR_TO_PACKET] = "pkt", 193 [PTR_TO_PACKET_END] = "pkt_end", 194 }; 195 196 #define __BPF_FUNC_STR_FN(x) [BPF_FUNC_ ## x] = __stringify(bpf_ ## x) 197 static const char * const func_id_str[] = { 198 __BPF_FUNC_MAPPER(__BPF_FUNC_STR_FN) 199 }; 200 #undef __BPF_FUNC_STR_FN 201 202 static const char *func_id_name(int id) 203 { 204 BUILD_BUG_ON(ARRAY_SIZE(func_id_str) != __BPF_FUNC_MAX_ID); 205 206 if (id >= 0 && id < __BPF_FUNC_MAX_ID && func_id_str[id]) 207 return func_id_str[id]; 208 else 209 return "unknown"; 210 } 211 212 static void print_verifier_state(struct bpf_verifier_state *state) 213 { 214 struct bpf_reg_state *reg; 215 enum bpf_reg_type t; 216 int i; 217 218 for (i = 0; i < MAX_BPF_REG; i++) { 219 reg = &state->regs[i]; 220 t = reg->type; 221 if (t == NOT_INIT) 222 continue; 223 verbose(" R%d=%s", i, reg_type_str[t]); 224 if (t == CONST_IMM || t == PTR_TO_STACK) 225 verbose("%lld", reg->imm); 226 else if (t == PTR_TO_PACKET) 227 verbose("(id=%d,off=%d,r=%d)", 228 reg->id, reg->off, reg->range); 229 else if (t == UNKNOWN_VALUE && reg->imm) 230 verbose("%lld", reg->imm); 231 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || 232 t == PTR_TO_MAP_VALUE_OR_NULL || 233 t == PTR_TO_MAP_VALUE_ADJ) 234 verbose("(ks=%d,vs=%d,id=%u)", 235 reg->map_ptr->key_size, 236 reg->map_ptr->value_size, 237 reg->id); 238 if (reg->min_value != BPF_REGISTER_MIN_RANGE) 239 verbose(",min_value=%lld", 240 (long long)reg->min_value); 241 if (reg->max_value != BPF_REGISTER_MAX_RANGE) 242 verbose(",max_value=%llu", 243 (unsigned long long)reg->max_value); 244 if (reg->min_align) 245 verbose(",min_align=%u", reg->min_align); 246 if (reg->aux_off) 247 verbose(",aux_off=%u", reg->aux_off); 248 if (reg->aux_off_align) 249 verbose(",aux_off_align=%u", reg->aux_off_align); 250 } 251 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 252 if (state->stack_slot_type[i] == STACK_SPILL) 253 verbose(" fp%d=%s", -MAX_BPF_STACK + i, 254 reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]); 255 } 256 verbose("\n"); 257 } 258 259 static const char *const bpf_class_string[] = { 260 [BPF_LD] = "ld", 261 [BPF_LDX] = "ldx", 262 [BPF_ST] = "st", 263 [BPF_STX] = "stx", 264 [BPF_ALU] = "alu", 265 [BPF_JMP] = "jmp", 266 [BPF_RET] = "BUG", 267 [BPF_ALU64] = "alu64", 268 }; 269 270 static const char *const bpf_alu_string[16] = { 271 [BPF_ADD >> 4] = "+=", 272 [BPF_SUB >> 4] = "-=", 273 [BPF_MUL >> 4] = "*=", 274 [BPF_DIV >> 4] = "/=", 275 [BPF_OR >> 4] = "|=", 276 [BPF_AND >> 4] = "&=", 277 [BPF_LSH >> 4] = "<<=", 278 [BPF_RSH >> 4] = ">>=", 279 [BPF_NEG >> 4] = "neg", 280 [BPF_MOD >> 4] = "%=", 281 [BPF_XOR >> 4] = "^=", 282 [BPF_MOV >> 4] = "=", 283 [BPF_ARSH >> 4] = "s>>=", 284 [BPF_END >> 4] = "endian", 285 }; 286 287 static const char *const bpf_ldst_string[] = { 288 [BPF_W >> 3] = "u32", 289 [BPF_H >> 3] = "u16", 290 [BPF_B >> 3] = "u8", 291 [BPF_DW >> 3] = "u64", 292 }; 293 294 static const char *const bpf_jmp_string[16] = { 295 [BPF_JA >> 4] = "jmp", 296 [BPF_JEQ >> 4] = "==", 297 [BPF_JGT >> 4] = ">", 298 [BPF_JGE >> 4] = ">=", 299 [BPF_JSET >> 4] = "&", 300 [BPF_JNE >> 4] = "!=", 301 [BPF_JSGT >> 4] = "s>", 302 [BPF_JSGE >> 4] = "s>=", 303 [BPF_CALL >> 4] = "call", 304 [BPF_EXIT >> 4] = "exit", 305 }; 306 307 static void print_bpf_insn(const struct bpf_verifier_env *env, 308 const struct bpf_insn *insn) 309 { 310 u8 class = BPF_CLASS(insn->code); 311 312 if (class == BPF_ALU || class == BPF_ALU64) { 313 if (BPF_SRC(insn->code) == BPF_X) 314 verbose("(%02x) %sr%d %s %sr%d\n", 315 insn->code, class == BPF_ALU ? "(u32) " : "", 316 insn->dst_reg, 317 bpf_alu_string[BPF_OP(insn->code) >> 4], 318 class == BPF_ALU ? "(u32) " : "", 319 insn->src_reg); 320 else 321 verbose("(%02x) %sr%d %s %s%d\n", 322 insn->code, class == BPF_ALU ? "(u32) " : "", 323 insn->dst_reg, 324 bpf_alu_string[BPF_OP(insn->code) >> 4], 325 class == BPF_ALU ? "(u32) " : "", 326 insn->imm); 327 } else if (class == BPF_STX) { 328 if (BPF_MODE(insn->code) == BPF_MEM) 329 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", 330 insn->code, 331 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 332 insn->dst_reg, 333 insn->off, insn->src_reg); 334 else if (BPF_MODE(insn->code) == BPF_XADD) 335 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", 336 insn->code, 337 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 338 insn->dst_reg, insn->off, 339 insn->src_reg); 340 else 341 verbose("BUG_%02x\n", insn->code); 342 } else if (class == BPF_ST) { 343 if (BPF_MODE(insn->code) != BPF_MEM) { 344 verbose("BUG_st_%02x\n", insn->code); 345 return; 346 } 347 verbose("(%02x) *(%s *)(r%d %+d) = %d\n", 348 insn->code, 349 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 350 insn->dst_reg, 351 insn->off, insn->imm); 352 } else if (class == BPF_LDX) { 353 if (BPF_MODE(insn->code) != BPF_MEM) { 354 verbose("BUG_ldx_%02x\n", insn->code); 355 return; 356 } 357 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", 358 insn->code, insn->dst_reg, 359 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 360 insn->src_reg, insn->off); 361 } else if (class == BPF_LD) { 362 if (BPF_MODE(insn->code) == BPF_ABS) { 363 verbose("(%02x) r0 = *(%s *)skb[%d]\n", 364 insn->code, 365 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 366 insn->imm); 367 } else if (BPF_MODE(insn->code) == BPF_IND) { 368 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", 369 insn->code, 370 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 371 insn->src_reg, insn->imm); 372 } else if (BPF_MODE(insn->code) == BPF_IMM && 373 BPF_SIZE(insn->code) == BPF_DW) { 374 /* At this point, we already made sure that the second 375 * part of the ldimm64 insn is accessible. 376 */ 377 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; 378 bool map_ptr = insn->src_reg == BPF_PSEUDO_MAP_FD; 379 380 if (map_ptr && !env->allow_ptr_leaks) 381 imm = 0; 382 383 verbose("(%02x) r%d = 0x%llx\n", insn->code, 384 insn->dst_reg, (unsigned long long)imm); 385 } else { 386 verbose("BUG_ld_%02x\n", insn->code); 387 return; 388 } 389 } else if (class == BPF_JMP) { 390 u8 opcode = BPF_OP(insn->code); 391 392 if (opcode == BPF_CALL) { 393 verbose("(%02x) call %s#%d\n", insn->code, 394 func_id_name(insn->imm), insn->imm); 395 } else if (insn->code == (BPF_JMP | BPF_JA)) { 396 verbose("(%02x) goto pc%+d\n", 397 insn->code, insn->off); 398 } else if (insn->code == (BPF_JMP | BPF_EXIT)) { 399 verbose("(%02x) exit\n", insn->code); 400 } else if (BPF_SRC(insn->code) == BPF_X) { 401 verbose("(%02x) if r%d %s r%d goto pc%+d\n", 402 insn->code, insn->dst_reg, 403 bpf_jmp_string[BPF_OP(insn->code) >> 4], 404 insn->src_reg, insn->off); 405 } else { 406 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", 407 insn->code, insn->dst_reg, 408 bpf_jmp_string[BPF_OP(insn->code) >> 4], 409 insn->imm, insn->off); 410 } 411 } else { 412 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); 413 } 414 } 415 416 static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx) 417 { 418 struct bpf_verifier_stack_elem *elem; 419 int insn_idx; 420 421 if (env->head == NULL) 422 return -1; 423 424 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); 425 insn_idx = env->head->insn_idx; 426 if (prev_insn_idx) 427 *prev_insn_idx = env->head->prev_insn_idx; 428 elem = env->head->next; 429 kfree(env->head); 430 env->head = elem; 431 env->stack_size--; 432 return insn_idx; 433 } 434 435 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, 436 int insn_idx, int prev_insn_idx) 437 { 438 struct bpf_verifier_stack_elem *elem; 439 440 elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL); 441 if (!elem) 442 goto err; 443 444 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); 445 elem->insn_idx = insn_idx; 446 elem->prev_insn_idx = prev_insn_idx; 447 elem->next = env->head; 448 env->head = elem; 449 env->stack_size++; 450 if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) { 451 verbose("BPF program is too complex\n"); 452 goto err; 453 } 454 return &elem->st; 455 err: 456 /* pop all elements and return */ 457 while (pop_stack(env, NULL) >= 0); 458 return NULL; 459 } 460 461 #define CALLER_SAVED_REGS 6 462 static const int caller_saved[CALLER_SAVED_REGS] = { 463 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 464 }; 465 466 static void mark_reg_not_init(struct bpf_reg_state *regs, u32 regno) 467 { 468 BUG_ON(regno >= MAX_BPF_REG); 469 470 memset(®s[regno], 0, sizeof(regs[regno])); 471 regs[regno].type = NOT_INIT; 472 regs[regno].min_value = BPF_REGISTER_MIN_RANGE; 473 regs[regno].max_value = BPF_REGISTER_MAX_RANGE; 474 } 475 476 static void init_reg_state(struct bpf_reg_state *regs) 477 { 478 int i; 479 480 for (i = 0; i < MAX_BPF_REG; i++) 481 mark_reg_not_init(regs, i); 482 483 /* frame pointer */ 484 regs[BPF_REG_FP].type = FRAME_PTR; 485 486 /* 1st arg to a function */ 487 regs[BPF_REG_1].type = PTR_TO_CTX; 488 } 489 490 static void __mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) 491 { 492 regs[regno].type = UNKNOWN_VALUE; 493 regs[regno].id = 0; 494 regs[regno].imm = 0; 495 } 496 497 static void mark_reg_unknown_value(struct bpf_reg_state *regs, u32 regno) 498 { 499 BUG_ON(regno >= MAX_BPF_REG); 500 __mark_reg_unknown_value(regs, regno); 501 } 502 503 static void reset_reg_range_values(struct bpf_reg_state *regs, u32 regno) 504 { 505 regs[regno].min_value = BPF_REGISTER_MIN_RANGE; 506 regs[regno].max_value = BPF_REGISTER_MAX_RANGE; 507 regs[regno].value_from_signed = false; 508 regs[regno].min_align = 0; 509 } 510 511 static void mark_reg_unknown_value_and_range(struct bpf_reg_state *regs, 512 u32 regno) 513 { 514 mark_reg_unknown_value(regs, regno); 515 reset_reg_range_values(regs, regno); 516 } 517 518 enum reg_arg_type { 519 SRC_OP, /* register is used as source operand */ 520 DST_OP, /* register is used as destination operand */ 521 DST_OP_NO_MARK /* same as above, check only, don't mark */ 522 }; 523 524 static int check_reg_arg(struct bpf_reg_state *regs, u32 regno, 525 enum reg_arg_type t) 526 { 527 if (regno >= MAX_BPF_REG) { 528 verbose("R%d is invalid\n", regno); 529 return -EINVAL; 530 } 531 532 if (t == SRC_OP) { 533 /* check whether register used as source operand can be read */ 534 if (regs[regno].type == NOT_INIT) { 535 verbose("R%d !read_ok\n", regno); 536 return -EACCES; 537 } 538 } else { 539 /* check whether register used as dest operand can be written to */ 540 if (regno == BPF_REG_FP) { 541 verbose("frame pointer is read only\n"); 542 return -EACCES; 543 } 544 if (t == DST_OP) 545 mark_reg_unknown_value(regs, regno); 546 } 547 return 0; 548 } 549 550 static bool is_spillable_regtype(enum bpf_reg_type type) 551 { 552 switch (type) { 553 case PTR_TO_MAP_VALUE: 554 case PTR_TO_MAP_VALUE_OR_NULL: 555 case PTR_TO_MAP_VALUE_ADJ: 556 case PTR_TO_STACK: 557 case PTR_TO_CTX: 558 case PTR_TO_PACKET: 559 case PTR_TO_PACKET_END: 560 case FRAME_PTR: 561 case CONST_PTR_TO_MAP: 562 return true; 563 default: 564 return false; 565 } 566 } 567 568 /* check_stack_read/write functions track spill/fill of registers, 569 * stack boundary and alignment are checked in check_mem_access() 570 */ 571 static int check_stack_write(struct bpf_verifier_state *state, int off, 572 int size, int value_regno) 573 { 574 int i; 575 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, 576 * so it's aligned access and [off, off + size) are within stack limits 577 */ 578 579 if (value_regno >= 0 && 580 is_spillable_regtype(state->regs[value_regno].type)) { 581 582 /* register containing pointer is being spilled into stack */ 583 if (size != BPF_REG_SIZE) { 584 verbose("invalid size of register spill\n"); 585 return -EACCES; 586 } 587 588 /* save register state */ 589 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 590 state->regs[value_regno]; 591 592 for (i = 0; i < BPF_REG_SIZE; i++) 593 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; 594 } else { 595 /* regular write of data into stack */ 596 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 597 (struct bpf_reg_state) {}; 598 599 for (i = 0; i < size; i++) 600 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; 601 } 602 return 0; 603 } 604 605 static int check_stack_read(struct bpf_verifier_state *state, int off, int size, 606 int value_regno) 607 { 608 u8 *slot_type; 609 int i; 610 611 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; 612 613 if (slot_type[0] == STACK_SPILL) { 614 if (size != BPF_REG_SIZE) { 615 verbose("invalid size of register spill\n"); 616 return -EACCES; 617 } 618 for (i = 1; i < BPF_REG_SIZE; i++) { 619 if (slot_type[i] != STACK_SPILL) { 620 verbose("corrupted spill memory\n"); 621 return -EACCES; 622 } 623 } 624 625 if (value_regno >= 0) 626 /* restore register state from stack */ 627 state->regs[value_regno] = 628 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; 629 return 0; 630 } else { 631 for (i = 0; i < size; i++) { 632 if (slot_type[i] != STACK_MISC) { 633 verbose("invalid read from stack off %d+%d size %d\n", 634 off, i, size); 635 return -EACCES; 636 } 637 } 638 if (value_regno >= 0) 639 /* have read misc data from the stack */ 640 mark_reg_unknown_value_and_range(state->regs, 641 value_regno); 642 return 0; 643 } 644 } 645 646 /* check read/write into map element returned by bpf_map_lookup_elem() */ 647 static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, 648 int size) 649 { 650 struct bpf_map *map = env->cur_state.regs[regno].map_ptr; 651 652 if (off < 0 || size <= 0 || off + size > map->value_size) { 653 verbose("invalid access to map value, value_size=%d off=%d size=%d\n", 654 map->value_size, off, size); 655 return -EACCES; 656 } 657 return 0; 658 } 659 660 /* check read/write into an adjusted map element */ 661 static int check_map_access_adj(struct bpf_verifier_env *env, u32 regno, 662 int off, int size) 663 { 664 struct bpf_verifier_state *state = &env->cur_state; 665 struct bpf_reg_state *reg = &state->regs[regno]; 666 int err; 667 668 /* We adjusted the register to this map value, so we 669 * need to change off and size to min_value and max_value 670 * respectively to make sure our theoretical access will be 671 * safe. 672 */ 673 if (log_level) 674 print_verifier_state(state); 675 env->varlen_map_value_access = true; 676 /* The minimum value is only important with signed 677 * comparisons where we can't assume the floor of a 678 * value is 0. If we are using signed variables for our 679 * index'es we need to make sure that whatever we use 680 * will have a set floor within our range. 681 */ 682 if (reg->min_value < 0) { 683 verbose("R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", 684 regno); 685 return -EACCES; 686 } 687 err = check_map_access(env, regno, reg->min_value + off, size); 688 if (err) { 689 verbose("R%d min value is outside of the array range\n", 690 regno); 691 return err; 692 } 693 694 /* If we haven't set a max value then we need to bail 695 * since we can't be sure we won't do bad things. 696 */ 697 if (reg->max_value == BPF_REGISTER_MAX_RANGE) { 698 verbose("R%d unbounded memory access, make sure to bounds check any array access into a map\n", 699 regno); 700 return -EACCES; 701 } 702 return check_map_access(env, regno, reg->max_value + off, size); 703 } 704 705 #define MAX_PACKET_OFF 0xffff 706 707 static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, 708 const struct bpf_call_arg_meta *meta, 709 enum bpf_access_type t) 710 { 711 switch (env->prog->type) { 712 case BPF_PROG_TYPE_LWT_IN: 713 case BPF_PROG_TYPE_LWT_OUT: 714 /* dst_input() and dst_output() can't write for now */ 715 if (t == BPF_WRITE) 716 return false; 717 /* fallthrough */ 718 case BPF_PROG_TYPE_SCHED_CLS: 719 case BPF_PROG_TYPE_SCHED_ACT: 720 case BPF_PROG_TYPE_XDP: 721 case BPF_PROG_TYPE_LWT_XMIT: 722 if (meta) 723 return meta->pkt_access; 724 725 env->seen_direct_write = true; 726 return true; 727 default: 728 return false; 729 } 730 } 731 732 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, 733 int size) 734 { 735 struct bpf_reg_state *regs = env->cur_state.regs; 736 struct bpf_reg_state *reg = ®s[regno]; 737 738 off += reg->off; 739 if (off < 0 || size <= 0 || off + size > reg->range) { 740 verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", 741 off, size, regno, reg->id, reg->off, reg->range); 742 return -EACCES; 743 } 744 return 0; 745 } 746 747 /* check access to 'struct bpf_context' fields */ 748 static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, 749 enum bpf_access_type t, enum bpf_reg_type *reg_type) 750 { 751 struct bpf_insn_access_aux info = { 752 .reg_type = *reg_type, 753 }; 754 755 /* for analyzer ctx accesses are already validated and converted */ 756 if (env->analyzer_ops) 757 return 0; 758 759 if (env->prog->aux->ops->is_valid_access && 760 env->prog->aux->ops->is_valid_access(off, size, t, &info)) { 761 /* A non zero info.ctx_field_size indicates that this field is a 762 * candidate for later verifier transformation to load the whole 763 * field and then apply a mask when accessed with a narrower 764 * access than actual ctx access size. A zero info.ctx_field_size 765 * will only allow for whole field access and rejects any other 766 * type of narrower access. 767 */ 768 env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; 769 *reg_type = info.reg_type; 770 771 /* remember the offset of last byte accessed in ctx */ 772 if (env->prog->aux->max_ctx_offset < off + size) 773 env->prog->aux->max_ctx_offset = off + size; 774 return 0; 775 } 776 777 verbose("invalid bpf_context access off=%d size=%d\n", off, size); 778 return -EACCES; 779 } 780 781 static bool __is_pointer_value(bool allow_ptr_leaks, 782 const struct bpf_reg_state *reg) 783 { 784 if (allow_ptr_leaks) 785 return false; 786 787 switch (reg->type) { 788 case UNKNOWN_VALUE: 789 case CONST_IMM: 790 return false; 791 default: 792 return true; 793 } 794 } 795 796 static bool is_pointer_value(struct bpf_verifier_env *env, int regno) 797 { 798 return __is_pointer_value(env->allow_ptr_leaks, &env->cur_state.regs[regno]); 799 } 800 801 static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg, 802 int off, int size, bool strict) 803 { 804 int ip_align; 805 int reg_off; 806 807 /* Byte size accesses are always allowed. */ 808 if (!strict || size == 1) 809 return 0; 810 811 reg_off = reg->off; 812 if (reg->id) { 813 if (reg->aux_off_align % size) { 814 verbose("Packet access is only %u byte aligned, %d byte access not allowed\n", 815 reg->aux_off_align, size); 816 return -EACCES; 817 } 818 reg_off += reg->aux_off; 819 } 820 821 /* For platforms that do not have a Kconfig enabling 822 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of 823 * NET_IP_ALIGN is universally set to '2'. And on platforms 824 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get 825 * to this code only in strict mode where we want to emulate 826 * the NET_IP_ALIGN==2 checking. Therefore use an 827 * unconditional IP align value of '2'. 828 */ 829 ip_align = 2; 830 if ((ip_align + reg_off + off) % size != 0) { 831 verbose("misaligned packet access off %d+%d+%d size %d\n", 832 ip_align, reg_off, off, size); 833 return -EACCES; 834 } 835 836 return 0; 837 } 838 839 static int check_val_ptr_alignment(const struct bpf_reg_state *reg, 840 int size, bool strict) 841 { 842 if (strict && size != 1) { 843 verbose("Unknown alignment. Only byte-sized access allowed in value access.\n"); 844 return -EACCES; 845 } 846 847 return 0; 848 } 849 850 static int check_ptr_alignment(struct bpf_verifier_env *env, 851 const struct bpf_reg_state *reg, 852 int off, int size) 853 { 854 bool strict = env->strict_alignment; 855 856 switch (reg->type) { 857 case PTR_TO_PACKET: 858 return check_pkt_ptr_alignment(reg, off, size, strict); 859 case PTR_TO_MAP_VALUE_ADJ: 860 return check_val_ptr_alignment(reg, size, strict); 861 default: 862 if (off % size != 0) { 863 verbose("misaligned access off %d size %d\n", 864 off, size); 865 return -EACCES; 866 } 867 868 return 0; 869 } 870 } 871 872 /* check whether memory at (regno + off) is accessible for t = (read | write) 873 * if t==write, value_regno is a register which value is stored into memory 874 * if t==read, value_regno is a register which will receive the value from memory 875 * if t==write && value_regno==-1, some unknown value is stored into memory 876 * if t==read && value_regno==-1, don't care what we read from memory 877 */ 878 static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, 879 int bpf_size, enum bpf_access_type t, 880 int value_regno) 881 { 882 struct bpf_verifier_state *state = &env->cur_state; 883 struct bpf_reg_state *reg = &state->regs[regno]; 884 int size, err = 0; 885 886 if (reg->type == PTR_TO_STACK) 887 off += reg->imm; 888 889 size = bpf_size_to_bytes(bpf_size); 890 if (size < 0) 891 return size; 892 893 err = check_ptr_alignment(env, reg, off, size); 894 if (err) 895 return err; 896 897 if (reg->type == PTR_TO_MAP_VALUE || 898 reg->type == PTR_TO_MAP_VALUE_ADJ) { 899 if (t == BPF_WRITE && value_regno >= 0 && 900 is_pointer_value(env, value_regno)) { 901 verbose("R%d leaks addr into map\n", value_regno); 902 return -EACCES; 903 } 904 905 if (reg->type == PTR_TO_MAP_VALUE_ADJ) 906 err = check_map_access_adj(env, regno, off, size); 907 else 908 err = check_map_access(env, regno, off, size); 909 if (!err && t == BPF_READ && value_regno >= 0) 910 mark_reg_unknown_value_and_range(state->regs, 911 value_regno); 912 913 } else if (reg->type == PTR_TO_CTX) { 914 enum bpf_reg_type reg_type = UNKNOWN_VALUE; 915 916 if (t == BPF_WRITE && value_regno >= 0 && 917 is_pointer_value(env, value_regno)) { 918 verbose("R%d leaks addr into ctx\n", value_regno); 919 return -EACCES; 920 } 921 err = check_ctx_access(env, insn_idx, off, size, t, ®_type); 922 if (!err && t == BPF_READ && value_regno >= 0) { 923 mark_reg_unknown_value_and_range(state->regs, 924 value_regno); 925 /* note that reg.[id|off|range] == 0 */ 926 state->regs[value_regno].type = reg_type; 927 state->regs[value_regno].aux_off = 0; 928 state->regs[value_regno].aux_off_align = 0; 929 } 930 931 } else if (reg->type == FRAME_PTR || reg->type == PTR_TO_STACK) { 932 if (off >= 0 || off < -MAX_BPF_STACK) { 933 verbose("invalid stack off=%d size=%d\n", off, size); 934 return -EACCES; 935 } 936 937 if (env->prog->aux->stack_depth < -off) 938 env->prog->aux->stack_depth = -off; 939 940 if (t == BPF_WRITE) { 941 if (!env->allow_ptr_leaks && 942 state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL && 943 size != BPF_REG_SIZE) { 944 verbose("attempt to corrupt spilled pointer on stack\n"); 945 return -EACCES; 946 } 947 err = check_stack_write(state, off, size, value_regno); 948 } else { 949 err = check_stack_read(state, off, size, value_regno); 950 } 951 } else if (state->regs[regno].type == PTR_TO_PACKET) { 952 if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) { 953 verbose("cannot write into packet\n"); 954 return -EACCES; 955 } 956 if (t == BPF_WRITE && value_regno >= 0 && 957 is_pointer_value(env, value_regno)) { 958 verbose("R%d leaks addr into packet\n", value_regno); 959 return -EACCES; 960 } 961 err = check_packet_access(env, regno, off, size); 962 if (!err && t == BPF_READ && value_regno >= 0) 963 mark_reg_unknown_value_and_range(state->regs, 964 value_regno); 965 } else { 966 verbose("R%d invalid mem access '%s'\n", 967 regno, reg_type_str[reg->type]); 968 return -EACCES; 969 } 970 971 if (!err && size <= 2 && value_regno >= 0 && env->allow_ptr_leaks && 972 state->regs[value_regno].type == UNKNOWN_VALUE) { 973 /* 1 or 2 byte load zero-extends, determine the number of 974 * zero upper bits. Not doing it fo 4 byte load, since 975 * such values cannot be added to ptr_to_packet anyway. 976 */ 977 state->regs[value_regno].imm = 64 - size * 8; 978 } 979 return err; 980 } 981 982 static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) 983 { 984 struct bpf_reg_state *regs = env->cur_state.regs; 985 int err; 986 987 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || 988 insn->imm != 0) { 989 verbose("BPF_XADD uses reserved fields\n"); 990 return -EINVAL; 991 } 992 993 /* check src1 operand */ 994 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 995 if (err) 996 return err; 997 998 /* check src2 operand */ 999 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1000 if (err) 1001 return err; 1002 1003 if (is_pointer_value(env, insn->src_reg)) { 1004 verbose("R%d leaks addr into mem\n", insn->src_reg); 1005 return -EACCES; 1006 } 1007 1008 /* check whether atomic_add can read the memory */ 1009 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 1010 BPF_SIZE(insn->code), BPF_READ, -1); 1011 if (err) 1012 return err; 1013 1014 /* check whether atomic_add can write into the same memory */ 1015 return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 1016 BPF_SIZE(insn->code), BPF_WRITE, -1); 1017 } 1018 1019 /* when register 'regno' is passed into function that will read 'access_size' 1020 * bytes from that pointer, make sure that it's within stack boundary 1021 * and all elements of stack are initialized 1022 */ 1023 static int check_stack_boundary(struct bpf_verifier_env *env, int regno, 1024 int access_size, bool zero_size_allowed, 1025 struct bpf_call_arg_meta *meta) 1026 { 1027 struct bpf_verifier_state *state = &env->cur_state; 1028 struct bpf_reg_state *regs = state->regs; 1029 int off, i; 1030 1031 if (regs[regno].type != PTR_TO_STACK) { 1032 if (zero_size_allowed && access_size == 0 && 1033 regs[regno].type == CONST_IMM && 1034 regs[regno].imm == 0) 1035 return 0; 1036 1037 verbose("R%d type=%s expected=%s\n", regno, 1038 reg_type_str[regs[regno].type], 1039 reg_type_str[PTR_TO_STACK]); 1040 return -EACCES; 1041 } 1042 1043 off = regs[regno].imm; 1044 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || 1045 access_size <= 0) { 1046 verbose("invalid stack type R%d off=%d access_size=%d\n", 1047 regno, off, access_size); 1048 return -EACCES; 1049 } 1050 1051 if (env->prog->aux->stack_depth < -off) 1052 env->prog->aux->stack_depth = -off; 1053 1054 if (meta && meta->raw_mode) { 1055 meta->access_size = access_size; 1056 meta->regno = regno; 1057 return 0; 1058 } 1059 1060 for (i = 0; i < access_size; i++) { 1061 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { 1062 verbose("invalid indirect read from stack off %d+%d size %d\n", 1063 off, i, access_size); 1064 return -EACCES; 1065 } 1066 } 1067 return 0; 1068 } 1069 1070 static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, 1071 int access_size, bool zero_size_allowed, 1072 struct bpf_call_arg_meta *meta) 1073 { 1074 struct bpf_reg_state *regs = env->cur_state.regs; 1075 1076 switch (regs[regno].type) { 1077 case PTR_TO_PACKET: 1078 return check_packet_access(env, regno, 0, access_size); 1079 case PTR_TO_MAP_VALUE: 1080 return check_map_access(env, regno, 0, access_size); 1081 case PTR_TO_MAP_VALUE_ADJ: 1082 return check_map_access_adj(env, regno, 0, access_size); 1083 default: /* const_imm|ptr_to_stack or invalid ptr */ 1084 return check_stack_boundary(env, regno, access_size, 1085 zero_size_allowed, meta); 1086 } 1087 } 1088 1089 static int check_func_arg(struct bpf_verifier_env *env, u32 regno, 1090 enum bpf_arg_type arg_type, 1091 struct bpf_call_arg_meta *meta) 1092 { 1093 struct bpf_reg_state *regs = env->cur_state.regs, *reg = ®s[regno]; 1094 enum bpf_reg_type expected_type, type = reg->type; 1095 int err = 0; 1096 1097 if (arg_type == ARG_DONTCARE) 1098 return 0; 1099 1100 if (type == NOT_INIT) { 1101 verbose("R%d !read_ok\n", regno); 1102 return -EACCES; 1103 } 1104 1105 if (arg_type == ARG_ANYTHING) { 1106 if (is_pointer_value(env, regno)) { 1107 verbose("R%d leaks addr into helper function\n", regno); 1108 return -EACCES; 1109 } 1110 return 0; 1111 } 1112 1113 if (type == PTR_TO_PACKET && 1114 !may_access_direct_pkt_data(env, meta, BPF_READ)) { 1115 verbose("helper access to the packet is not allowed\n"); 1116 return -EACCES; 1117 } 1118 1119 if (arg_type == ARG_PTR_TO_MAP_KEY || 1120 arg_type == ARG_PTR_TO_MAP_VALUE) { 1121 expected_type = PTR_TO_STACK; 1122 if (type != PTR_TO_PACKET && type != expected_type) 1123 goto err_type; 1124 } else if (arg_type == ARG_CONST_SIZE || 1125 arg_type == ARG_CONST_SIZE_OR_ZERO) { 1126 expected_type = CONST_IMM; 1127 /* One exception. Allow UNKNOWN_VALUE registers when the 1128 * boundaries are known and don't cause unsafe memory accesses 1129 */ 1130 if (type != UNKNOWN_VALUE && type != expected_type) 1131 goto err_type; 1132 } else if (arg_type == ARG_CONST_MAP_PTR) { 1133 expected_type = CONST_PTR_TO_MAP; 1134 if (type != expected_type) 1135 goto err_type; 1136 } else if (arg_type == ARG_PTR_TO_CTX) { 1137 expected_type = PTR_TO_CTX; 1138 if (type != expected_type) 1139 goto err_type; 1140 } else if (arg_type == ARG_PTR_TO_MEM || 1141 arg_type == ARG_PTR_TO_UNINIT_MEM) { 1142 expected_type = PTR_TO_STACK; 1143 /* One exception here. In case function allows for NULL to be 1144 * passed in as argument, it's a CONST_IMM type. Final test 1145 * happens during stack boundary checking. 1146 */ 1147 if (type == CONST_IMM && reg->imm == 0) 1148 /* final test in check_stack_boundary() */; 1149 else if (type != PTR_TO_PACKET && type != PTR_TO_MAP_VALUE && 1150 type != PTR_TO_MAP_VALUE_ADJ && type != expected_type) 1151 goto err_type; 1152 meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; 1153 } else { 1154 verbose("unsupported arg_type %d\n", arg_type); 1155 return -EFAULT; 1156 } 1157 1158 if (arg_type == ARG_CONST_MAP_PTR) { 1159 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ 1160 meta->map_ptr = reg->map_ptr; 1161 } else if (arg_type == ARG_PTR_TO_MAP_KEY) { 1162 /* bpf_map_xxx(..., map_ptr, ..., key) call: 1163 * check that [key, key + map->key_size) are within 1164 * stack limits and initialized 1165 */ 1166 if (!meta->map_ptr) { 1167 /* in function declaration map_ptr must come before 1168 * map_key, so that it's verified and known before 1169 * we have to check map_key here. Otherwise it means 1170 * that kernel subsystem misconfigured verifier 1171 */ 1172 verbose("invalid map_ptr to access map->key\n"); 1173 return -EACCES; 1174 } 1175 if (type == PTR_TO_PACKET) 1176 err = check_packet_access(env, regno, 0, 1177 meta->map_ptr->key_size); 1178 else 1179 err = check_stack_boundary(env, regno, 1180 meta->map_ptr->key_size, 1181 false, NULL); 1182 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { 1183 /* bpf_map_xxx(..., map_ptr, ..., value) call: 1184 * check [value, value + map->value_size) validity 1185 */ 1186 if (!meta->map_ptr) { 1187 /* kernel subsystem misconfigured verifier */ 1188 verbose("invalid map_ptr to access map->value\n"); 1189 return -EACCES; 1190 } 1191 if (type == PTR_TO_PACKET) 1192 err = check_packet_access(env, regno, 0, 1193 meta->map_ptr->value_size); 1194 else 1195 err = check_stack_boundary(env, regno, 1196 meta->map_ptr->value_size, 1197 false, NULL); 1198 } else if (arg_type == ARG_CONST_SIZE || 1199 arg_type == ARG_CONST_SIZE_OR_ZERO) { 1200 bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); 1201 1202 /* bpf_xxx(..., buf, len) call will access 'len' bytes 1203 * from stack pointer 'buf'. Check it 1204 * note: regno == len, regno - 1 == buf 1205 */ 1206 if (regno == 0) { 1207 /* kernel subsystem misconfigured verifier */ 1208 verbose("ARG_CONST_SIZE cannot be first argument\n"); 1209 return -EACCES; 1210 } 1211 1212 /* If the register is UNKNOWN_VALUE, the access check happens 1213 * using its boundaries. Otherwise, just use its imm 1214 */ 1215 if (type == UNKNOWN_VALUE) { 1216 /* For unprivileged variable accesses, disable raw 1217 * mode so that the program is required to 1218 * initialize all the memory that the helper could 1219 * just partially fill up. 1220 */ 1221 meta = NULL; 1222 1223 if (reg->min_value < 0) { 1224 verbose("R%d min value is negative, either use unsigned or 'var &= const'\n", 1225 regno); 1226 return -EACCES; 1227 } 1228 1229 if (reg->min_value == 0) { 1230 err = check_helper_mem_access(env, regno - 1, 0, 1231 zero_size_allowed, 1232 meta); 1233 if (err) 1234 return err; 1235 } 1236 1237 if (reg->max_value == BPF_REGISTER_MAX_RANGE) { 1238 verbose("R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", 1239 regno); 1240 return -EACCES; 1241 } 1242 err = check_helper_mem_access(env, regno - 1, 1243 reg->max_value, 1244 zero_size_allowed, meta); 1245 if (err) 1246 return err; 1247 } else { 1248 /* register is CONST_IMM */ 1249 err = check_helper_mem_access(env, regno - 1, reg->imm, 1250 zero_size_allowed, meta); 1251 } 1252 } 1253 1254 return err; 1255 err_type: 1256 verbose("R%d type=%s expected=%s\n", regno, 1257 reg_type_str[type], reg_type_str[expected_type]); 1258 return -EACCES; 1259 } 1260 1261 static int check_map_func_compatibility(struct bpf_map *map, int func_id) 1262 { 1263 if (!map) 1264 return 0; 1265 1266 /* We need a two way check, first is from map perspective ... */ 1267 switch (map->map_type) { 1268 case BPF_MAP_TYPE_PROG_ARRAY: 1269 if (func_id != BPF_FUNC_tail_call) 1270 goto error; 1271 break; 1272 case BPF_MAP_TYPE_PERF_EVENT_ARRAY: 1273 if (func_id != BPF_FUNC_perf_event_read && 1274 func_id != BPF_FUNC_perf_event_output) 1275 goto error; 1276 break; 1277 case BPF_MAP_TYPE_STACK_TRACE: 1278 if (func_id != BPF_FUNC_get_stackid) 1279 goto error; 1280 break; 1281 case BPF_MAP_TYPE_CGROUP_ARRAY: 1282 if (func_id != BPF_FUNC_skb_under_cgroup && 1283 func_id != BPF_FUNC_current_task_under_cgroup) 1284 goto error; 1285 break; 1286 case BPF_MAP_TYPE_ARRAY_OF_MAPS: 1287 case BPF_MAP_TYPE_HASH_OF_MAPS: 1288 if (func_id != BPF_FUNC_map_lookup_elem) 1289 goto error; 1290 default: 1291 break; 1292 } 1293 1294 /* ... and second from the function itself. */ 1295 switch (func_id) { 1296 case BPF_FUNC_tail_call: 1297 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) 1298 goto error; 1299 break; 1300 case BPF_FUNC_perf_event_read: 1301 case BPF_FUNC_perf_event_output: 1302 if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) 1303 goto error; 1304 break; 1305 case BPF_FUNC_get_stackid: 1306 if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) 1307 goto error; 1308 break; 1309 case BPF_FUNC_current_task_under_cgroup: 1310 case BPF_FUNC_skb_under_cgroup: 1311 if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) 1312 goto error; 1313 break; 1314 default: 1315 break; 1316 } 1317 1318 return 0; 1319 error: 1320 verbose("cannot pass map_type %d into func %s#%d\n", 1321 map->map_type, func_id_name(func_id), func_id); 1322 return -EINVAL; 1323 } 1324 1325 static int check_raw_mode(const struct bpf_func_proto *fn) 1326 { 1327 int count = 0; 1328 1329 if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) 1330 count++; 1331 if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) 1332 count++; 1333 if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) 1334 count++; 1335 if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) 1336 count++; 1337 if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) 1338 count++; 1339 1340 return count > 1 ? -EINVAL : 0; 1341 } 1342 1343 static void clear_all_pkt_pointers(struct bpf_verifier_env *env) 1344 { 1345 struct bpf_verifier_state *state = &env->cur_state; 1346 struct bpf_reg_state *regs = state->regs, *reg; 1347 int i; 1348 1349 for (i = 0; i < MAX_BPF_REG; i++) 1350 if (regs[i].type == PTR_TO_PACKET || 1351 regs[i].type == PTR_TO_PACKET_END) 1352 mark_reg_unknown_value(regs, i); 1353 1354 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 1355 if (state->stack_slot_type[i] != STACK_SPILL) 1356 continue; 1357 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 1358 if (reg->type != PTR_TO_PACKET && 1359 reg->type != PTR_TO_PACKET_END) 1360 continue; 1361 __mark_reg_unknown_value(state->spilled_regs, 1362 i / BPF_REG_SIZE); 1363 } 1364 } 1365 1366 static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx) 1367 { 1368 struct bpf_verifier_state *state = &env->cur_state; 1369 const struct bpf_func_proto *fn = NULL; 1370 struct bpf_reg_state *regs = state->regs; 1371 struct bpf_call_arg_meta meta; 1372 bool changes_data; 1373 int i, err; 1374 1375 /* find function prototype */ 1376 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { 1377 verbose("invalid func %s#%d\n", func_id_name(func_id), func_id); 1378 return -EINVAL; 1379 } 1380 1381 if (env->prog->aux->ops->get_func_proto) 1382 fn = env->prog->aux->ops->get_func_proto(func_id); 1383 1384 if (!fn) { 1385 verbose("unknown func %s#%d\n", func_id_name(func_id), func_id); 1386 return -EINVAL; 1387 } 1388 1389 /* eBPF programs must be GPL compatible to use GPL-ed functions */ 1390 if (!env->prog->gpl_compatible && fn->gpl_only) { 1391 verbose("cannot call GPL only function from proprietary program\n"); 1392 return -EINVAL; 1393 } 1394 1395 changes_data = bpf_helper_changes_pkt_data(fn->func); 1396 1397 memset(&meta, 0, sizeof(meta)); 1398 meta.pkt_access = fn->pkt_access; 1399 1400 /* We only support one arg being in raw mode at the moment, which 1401 * is sufficient for the helper functions we have right now. 1402 */ 1403 err = check_raw_mode(fn); 1404 if (err) { 1405 verbose("kernel subsystem misconfigured func %s#%d\n", 1406 func_id_name(func_id), func_id); 1407 return err; 1408 } 1409 1410 /* check args */ 1411 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta); 1412 if (err) 1413 return err; 1414 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta); 1415 if (err) 1416 return err; 1417 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta); 1418 if (err) 1419 return err; 1420 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta); 1421 if (err) 1422 return err; 1423 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta); 1424 if (err) 1425 return err; 1426 1427 /* Mark slots with STACK_MISC in case of raw mode, stack offset 1428 * is inferred from register state. 1429 */ 1430 for (i = 0; i < meta.access_size; i++) { 1431 err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1); 1432 if (err) 1433 return err; 1434 } 1435 1436 /* reset caller saved regs */ 1437 for (i = 0; i < CALLER_SAVED_REGS; i++) 1438 mark_reg_not_init(regs, caller_saved[i]); 1439 1440 /* update return register */ 1441 if (fn->ret_type == RET_INTEGER) { 1442 regs[BPF_REG_0].type = UNKNOWN_VALUE; 1443 } else if (fn->ret_type == RET_VOID) { 1444 regs[BPF_REG_0].type = NOT_INIT; 1445 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { 1446 struct bpf_insn_aux_data *insn_aux; 1447 1448 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; 1449 regs[BPF_REG_0].max_value = regs[BPF_REG_0].min_value = 0; 1450 /* remember map_ptr, so that check_map_access() 1451 * can check 'value_size' boundary of memory access 1452 * to map element returned from bpf_map_lookup_elem() 1453 */ 1454 if (meta.map_ptr == NULL) { 1455 verbose("kernel subsystem misconfigured verifier\n"); 1456 return -EINVAL; 1457 } 1458 regs[BPF_REG_0].map_ptr = meta.map_ptr; 1459 regs[BPF_REG_0].id = ++env->id_gen; 1460 insn_aux = &env->insn_aux_data[insn_idx]; 1461 if (!insn_aux->map_ptr) 1462 insn_aux->map_ptr = meta.map_ptr; 1463 else if (insn_aux->map_ptr != meta.map_ptr) 1464 insn_aux->map_ptr = BPF_MAP_PTR_POISON; 1465 } else { 1466 verbose("unknown return type %d of func %s#%d\n", 1467 fn->ret_type, func_id_name(func_id), func_id); 1468 return -EINVAL; 1469 } 1470 1471 err = check_map_func_compatibility(meta.map_ptr, func_id); 1472 if (err) 1473 return err; 1474 1475 if (changes_data) 1476 clear_all_pkt_pointers(env); 1477 return 0; 1478 } 1479 1480 static int check_packet_ptr_add(struct bpf_verifier_env *env, 1481 struct bpf_insn *insn) 1482 { 1483 struct bpf_reg_state *regs = env->cur_state.regs; 1484 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1485 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1486 struct bpf_reg_state tmp_reg; 1487 s32 imm; 1488 1489 if (BPF_SRC(insn->code) == BPF_K) { 1490 /* pkt_ptr += imm */ 1491 imm = insn->imm; 1492 1493 add_imm: 1494 if (imm < 0) { 1495 verbose("addition of negative constant to packet pointer is not allowed\n"); 1496 return -EACCES; 1497 } 1498 if (imm >= MAX_PACKET_OFF || 1499 imm + dst_reg->off >= MAX_PACKET_OFF) { 1500 verbose("constant %d is too large to add to packet pointer\n", 1501 imm); 1502 return -EACCES; 1503 } 1504 /* a constant was added to pkt_ptr. 1505 * Remember it while keeping the same 'id' 1506 */ 1507 dst_reg->off += imm; 1508 } else { 1509 bool had_id; 1510 1511 if (src_reg->type == PTR_TO_PACKET) { 1512 /* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */ 1513 tmp_reg = *dst_reg; /* save r7 state */ 1514 *dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */ 1515 src_reg = &tmp_reg; /* pretend it's src_reg state */ 1516 /* if the checks below reject it, the copy won't matter, 1517 * since we're rejecting the whole program. If all ok, 1518 * then imm22 state will be added to r7 1519 * and r7 will be pkt(id=0,off=22,r=62) while 1520 * r6 will stay as pkt(id=0,off=0,r=62) 1521 */ 1522 } 1523 1524 if (src_reg->type == CONST_IMM) { 1525 /* pkt_ptr += reg where reg is known constant */ 1526 imm = src_reg->imm; 1527 goto add_imm; 1528 } 1529 /* disallow pkt_ptr += reg 1530 * if reg is not uknown_value with guaranteed zero upper bits 1531 * otherwise pkt_ptr may overflow and addition will become 1532 * subtraction which is not allowed 1533 */ 1534 if (src_reg->type != UNKNOWN_VALUE) { 1535 verbose("cannot add '%s' to ptr_to_packet\n", 1536 reg_type_str[src_reg->type]); 1537 return -EACCES; 1538 } 1539 if (src_reg->imm < 48) { 1540 verbose("cannot add integer value with %lld upper zero bits to ptr_to_packet\n", 1541 src_reg->imm); 1542 return -EACCES; 1543 } 1544 1545 had_id = (dst_reg->id != 0); 1546 1547 /* dst_reg stays as pkt_ptr type and since some positive 1548 * integer value was added to the pointer, increment its 'id' 1549 */ 1550 dst_reg->id = ++env->id_gen; 1551 1552 /* something was added to pkt_ptr, set range to zero */ 1553 dst_reg->aux_off += dst_reg->off; 1554 dst_reg->off = 0; 1555 dst_reg->range = 0; 1556 if (had_id) 1557 dst_reg->aux_off_align = min(dst_reg->aux_off_align, 1558 src_reg->min_align); 1559 else 1560 dst_reg->aux_off_align = src_reg->min_align; 1561 } 1562 return 0; 1563 } 1564 1565 static int evaluate_reg_alu(struct bpf_verifier_env *env, struct bpf_insn *insn) 1566 { 1567 struct bpf_reg_state *regs = env->cur_state.regs; 1568 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1569 u8 opcode = BPF_OP(insn->code); 1570 s64 imm_log2; 1571 1572 /* for type == UNKNOWN_VALUE: 1573 * imm > 0 -> number of zero upper bits 1574 * imm == 0 -> don't track which is the same as all bits can be non-zero 1575 */ 1576 1577 if (BPF_SRC(insn->code) == BPF_X) { 1578 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1579 1580 if (src_reg->type == UNKNOWN_VALUE && src_reg->imm > 0 && 1581 dst_reg->imm && opcode == BPF_ADD) { 1582 /* dreg += sreg 1583 * where both have zero upper bits. Adding them 1584 * can only result making one more bit non-zero 1585 * in the larger value. 1586 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) 1587 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) 1588 */ 1589 dst_reg->imm = min(dst_reg->imm, src_reg->imm); 1590 dst_reg->imm--; 1591 return 0; 1592 } 1593 if (src_reg->type == CONST_IMM && src_reg->imm > 0 && 1594 dst_reg->imm && opcode == BPF_ADD) { 1595 /* dreg += sreg 1596 * where dreg has zero upper bits and sreg is const. 1597 * Adding them can only result making one more bit 1598 * non-zero in the larger value. 1599 */ 1600 imm_log2 = __ilog2_u64((long long)src_reg->imm); 1601 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1602 dst_reg->imm--; 1603 return 0; 1604 } 1605 /* all other cases non supported yet, just mark dst_reg */ 1606 dst_reg->imm = 0; 1607 return 0; 1608 } 1609 1610 /* sign extend 32-bit imm into 64-bit to make sure that 1611 * negative values occupy bit 63. Note ilog2() would have 1612 * been incorrect, since sizeof(insn->imm) == 4 1613 */ 1614 imm_log2 = __ilog2_u64((long long)insn->imm); 1615 1616 if (dst_reg->imm && opcode == BPF_LSH) { 1617 /* reg <<= imm 1618 * if reg was a result of 2 byte load, then its imm == 48 1619 * which means that upper 48 bits are zero and shifting this reg 1620 * left by 4 would mean that upper 44 bits are still zero 1621 */ 1622 dst_reg->imm -= insn->imm; 1623 } else if (dst_reg->imm && opcode == BPF_MUL) { 1624 /* reg *= imm 1625 * if multiplying by 14 subtract 4 1626 * This is conservative calculation of upper zero bits. 1627 * It's not trying to special case insn->imm == 1 or 0 cases 1628 */ 1629 dst_reg->imm -= imm_log2 + 1; 1630 } else if (opcode == BPF_AND) { 1631 /* reg &= imm */ 1632 dst_reg->imm = 63 - imm_log2; 1633 } else if (dst_reg->imm && opcode == BPF_ADD) { 1634 /* reg += imm */ 1635 dst_reg->imm = min(dst_reg->imm, 63 - imm_log2); 1636 dst_reg->imm--; 1637 } else if (opcode == BPF_RSH) { 1638 /* reg >>= imm 1639 * which means that after right shift, upper bits will be zero 1640 * note that verifier already checked that 1641 * 0 <= imm < 64 for shift insn 1642 */ 1643 dst_reg->imm += insn->imm; 1644 if (unlikely(dst_reg->imm > 64)) 1645 /* some dumb code did: 1646 * r2 = *(u32 *)mem; 1647 * r2 >>= 32; 1648 * and all bits are zero now */ 1649 dst_reg->imm = 64; 1650 } else { 1651 /* all other alu ops, means that we don't know what will 1652 * happen to the value, mark it with unknown number of zero bits 1653 */ 1654 dst_reg->imm = 0; 1655 } 1656 1657 if (dst_reg->imm < 0) { 1658 /* all 64 bits of the register can contain non-zero bits 1659 * and such value cannot be added to ptr_to_packet, since it 1660 * may overflow, mark it as unknown to avoid further eval 1661 */ 1662 dst_reg->imm = 0; 1663 } 1664 return 0; 1665 } 1666 1667 static int evaluate_reg_imm_alu_unknown(struct bpf_verifier_env *env, 1668 struct bpf_insn *insn) 1669 { 1670 struct bpf_reg_state *regs = env->cur_state.regs; 1671 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1672 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1673 u8 opcode = BPF_OP(insn->code); 1674 s64 imm_log2 = __ilog2_u64((long long)dst_reg->imm); 1675 1676 /* BPF_X code with src_reg->type UNKNOWN_VALUE here. */ 1677 if (src_reg->imm > 0 && dst_reg->imm) { 1678 switch (opcode) { 1679 case BPF_ADD: 1680 /* dreg += sreg 1681 * where both have zero upper bits. Adding them 1682 * can only result making one more bit non-zero 1683 * in the larger value. 1684 * Ex. 0xffff (imm=48) + 1 (imm=63) = 0x10000 (imm=47) 1685 * 0xffff (imm=48) + 0xffff = 0x1fffe (imm=47) 1686 */ 1687 dst_reg->imm = min(src_reg->imm, 63 - imm_log2); 1688 dst_reg->imm--; 1689 break; 1690 case BPF_AND: 1691 /* dreg &= sreg 1692 * AND can not extend zero bits only shrink 1693 * Ex. 0x00..00ffffff 1694 * & 0x0f..ffffffff 1695 * ---------------- 1696 * 0x00..00ffffff 1697 */ 1698 dst_reg->imm = max(src_reg->imm, 63 - imm_log2); 1699 break; 1700 case BPF_OR: 1701 /* dreg |= sreg 1702 * OR can only extend zero bits 1703 * Ex. 0x00..00ffffff 1704 * | 0x0f..ffffffff 1705 * ---------------- 1706 * 0x0f..00ffffff 1707 */ 1708 dst_reg->imm = min(src_reg->imm, 63 - imm_log2); 1709 break; 1710 case BPF_SUB: 1711 case BPF_MUL: 1712 case BPF_RSH: 1713 case BPF_LSH: 1714 /* These may be flushed out later */ 1715 default: 1716 mark_reg_unknown_value(regs, insn->dst_reg); 1717 } 1718 } else { 1719 mark_reg_unknown_value(regs, insn->dst_reg); 1720 } 1721 1722 dst_reg->type = UNKNOWN_VALUE; 1723 return 0; 1724 } 1725 1726 static int evaluate_reg_imm_alu(struct bpf_verifier_env *env, 1727 struct bpf_insn *insn) 1728 { 1729 struct bpf_reg_state *regs = env->cur_state.regs; 1730 struct bpf_reg_state *dst_reg = ®s[insn->dst_reg]; 1731 struct bpf_reg_state *src_reg = ®s[insn->src_reg]; 1732 u8 opcode = BPF_OP(insn->code); 1733 u64 dst_imm = dst_reg->imm; 1734 1735 if (BPF_SRC(insn->code) == BPF_X && src_reg->type == UNKNOWN_VALUE) 1736 return evaluate_reg_imm_alu_unknown(env, insn); 1737 1738 /* dst_reg->type == CONST_IMM here. Simulate execution of insns 1739 * containing ALU ops. Don't care about overflow or negative 1740 * values, just add/sub/... them; registers are in u64. 1741 */ 1742 if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_K) { 1743 dst_imm += insn->imm; 1744 } else if (opcode == BPF_ADD && BPF_SRC(insn->code) == BPF_X && 1745 src_reg->type == CONST_IMM) { 1746 dst_imm += src_reg->imm; 1747 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_K) { 1748 dst_imm -= insn->imm; 1749 } else if (opcode == BPF_SUB && BPF_SRC(insn->code) == BPF_X && 1750 src_reg->type == CONST_IMM) { 1751 dst_imm -= src_reg->imm; 1752 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_K) { 1753 dst_imm *= insn->imm; 1754 } else if (opcode == BPF_MUL && BPF_SRC(insn->code) == BPF_X && 1755 src_reg->type == CONST_IMM) { 1756 dst_imm *= src_reg->imm; 1757 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_K) { 1758 dst_imm |= insn->imm; 1759 } else if (opcode == BPF_OR && BPF_SRC(insn->code) == BPF_X && 1760 src_reg->type == CONST_IMM) { 1761 dst_imm |= src_reg->imm; 1762 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_K) { 1763 dst_imm &= insn->imm; 1764 } else if (opcode == BPF_AND && BPF_SRC(insn->code) == BPF_X && 1765 src_reg->type == CONST_IMM) { 1766 dst_imm &= src_reg->imm; 1767 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_K) { 1768 dst_imm >>= insn->imm; 1769 } else if (opcode == BPF_RSH && BPF_SRC(insn->code) == BPF_X && 1770 src_reg->type == CONST_IMM) { 1771 dst_imm >>= src_reg->imm; 1772 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_K) { 1773 dst_imm <<= insn->imm; 1774 } else if (opcode == BPF_LSH && BPF_SRC(insn->code) == BPF_X && 1775 src_reg->type == CONST_IMM) { 1776 dst_imm <<= src_reg->imm; 1777 } else { 1778 mark_reg_unknown_value(regs, insn->dst_reg); 1779 goto out; 1780 } 1781 1782 dst_reg->imm = dst_imm; 1783 out: 1784 return 0; 1785 } 1786 1787 static void check_reg_overflow(struct bpf_reg_state *reg) 1788 { 1789 if (reg->max_value > BPF_REGISTER_MAX_RANGE) 1790 reg->max_value = BPF_REGISTER_MAX_RANGE; 1791 if (reg->min_value < BPF_REGISTER_MIN_RANGE || 1792 reg->min_value > BPF_REGISTER_MAX_RANGE) 1793 reg->min_value = BPF_REGISTER_MIN_RANGE; 1794 } 1795 1796 static u32 calc_align(u32 imm) 1797 { 1798 if (!imm) 1799 return 1U << 31; 1800 return imm - ((imm - 1) & imm); 1801 } 1802 1803 static void adjust_reg_min_max_vals(struct bpf_verifier_env *env, 1804 struct bpf_insn *insn) 1805 { 1806 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1807 s64 min_val = BPF_REGISTER_MIN_RANGE; 1808 u64 max_val = BPF_REGISTER_MAX_RANGE; 1809 u8 opcode = BPF_OP(insn->code); 1810 u32 dst_align, src_align; 1811 1812 dst_reg = ®s[insn->dst_reg]; 1813 src_align = 0; 1814 if (BPF_SRC(insn->code) == BPF_X) { 1815 check_reg_overflow(®s[insn->src_reg]); 1816 min_val = regs[insn->src_reg].min_value; 1817 max_val = regs[insn->src_reg].max_value; 1818 1819 /* If the source register is a random pointer then the 1820 * min_value/max_value values represent the range of the known 1821 * accesses into that value, not the actual min/max value of the 1822 * register itself. In this case we have to reset the reg range 1823 * values so we know it is not safe to look at. 1824 */ 1825 if (regs[insn->src_reg].type != CONST_IMM && 1826 regs[insn->src_reg].type != UNKNOWN_VALUE) { 1827 min_val = BPF_REGISTER_MIN_RANGE; 1828 max_val = BPF_REGISTER_MAX_RANGE; 1829 src_align = 0; 1830 } else { 1831 src_align = regs[insn->src_reg].min_align; 1832 } 1833 } else if (insn->imm < BPF_REGISTER_MAX_RANGE && 1834 (s64)insn->imm > BPF_REGISTER_MIN_RANGE) { 1835 min_val = max_val = insn->imm; 1836 src_align = calc_align(insn->imm); 1837 } 1838 1839 dst_align = dst_reg->min_align; 1840 1841 /* We don't know anything about what was done to this register, mark it 1842 * as unknown. Also, if both derived bounds came from signed/unsigned 1843 * mixed compares and one side is unbounded, we cannot really do anything 1844 * with them as boundaries cannot be trusted. Thus, arithmetic of two 1845 * regs of such kind will get invalidated bounds on the dst side. 1846 */ 1847 if ((min_val == BPF_REGISTER_MIN_RANGE && 1848 max_val == BPF_REGISTER_MAX_RANGE) || 1849 (BPF_SRC(insn->code) == BPF_X && 1850 ((min_val != BPF_REGISTER_MIN_RANGE && 1851 max_val == BPF_REGISTER_MAX_RANGE) || 1852 (min_val == BPF_REGISTER_MIN_RANGE && 1853 max_val != BPF_REGISTER_MAX_RANGE) || 1854 (dst_reg->min_value != BPF_REGISTER_MIN_RANGE && 1855 dst_reg->max_value == BPF_REGISTER_MAX_RANGE) || 1856 (dst_reg->min_value == BPF_REGISTER_MIN_RANGE && 1857 dst_reg->max_value != BPF_REGISTER_MAX_RANGE)) && 1858 regs[insn->dst_reg].value_from_signed != 1859 regs[insn->src_reg].value_from_signed)) { 1860 reset_reg_range_values(regs, insn->dst_reg); 1861 return; 1862 } 1863 1864 /* If one of our values was at the end of our ranges then we can't just 1865 * do our normal operations to the register, we need to set the values 1866 * to the min/max since they are undefined. 1867 */ 1868 if (min_val == BPF_REGISTER_MIN_RANGE) 1869 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1870 if (max_val == BPF_REGISTER_MAX_RANGE) 1871 dst_reg->max_value = BPF_REGISTER_MAX_RANGE; 1872 1873 switch (opcode) { 1874 case BPF_ADD: 1875 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1876 dst_reg->min_value += min_val; 1877 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1878 dst_reg->max_value += max_val; 1879 dst_reg->min_align = min(src_align, dst_align); 1880 break; 1881 case BPF_SUB: 1882 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1883 dst_reg->min_value -= min_val; 1884 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1885 dst_reg->max_value -= max_val; 1886 dst_reg->min_align = min(src_align, dst_align); 1887 break; 1888 case BPF_MUL: 1889 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1890 dst_reg->min_value *= min_val; 1891 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1892 dst_reg->max_value *= max_val; 1893 dst_reg->min_align = max(src_align, dst_align); 1894 break; 1895 case BPF_AND: 1896 /* Disallow AND'ing of negative numbers, ain't nobody got time 1897 * for that. Otherwise the minimum is 0 and the max is the max 1898 * value we could AND against. 1899 */ 1900 if (min_val < 0) 1901 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1902 else 1903 dst_reg->min_value = 0; 1904 dst_reg->max_value = max_val; 1905 dst_reg->min_align = max(src_align, dst_align); 1906 break; 1907 case BPF_LSH: 1908 /* Gotta have special overflow logic here, if we're shifting 1909 * more than MAX_RANGE then just assume we have an invalid 1910 * range. 1911 */ 1912 if (min_val > ilog2(BPF_REGISTER_MAX_RANGE)) { 1913 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1914 dst_reg->min_align = 1; 1915 } else { 1916 if (dst_reg->min_value != BPF_REGISTER_MIN_RANGE) 1917 dst_reg->min_value <<= min_val; 1918 if (!dst_reg->min_align) 1919 dst_reg->min_align = 1; 1920 dst_reg->min_align <<= min_val; 1921 } 1922 if (max_val > ilog2(BPF_REGISTER_MAX_RANGE)) 1923 dst_reg->max_value = BPF_REGISTER_MAX_RANGE; 1924 else if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1925 dst_reg->max_value <<= max_val; 1926 break; 1927 case BPF_RSH: 1928 /* RSH by a negative number is undefined, and the BPF_RSH is an 1929 * unsigned shift, so make the appropriate casts. 1930 */ 1931 if (min_val < 0 || dst_reg->min_value < 0) { 1932 dst_reg->min_value = BPF_REGISTER_MIN_RANGE; 1933 } else { 1934 dst_reg->min_value = 1935 (u64)(dst_reg->min_value) >> min_val; 1936 } 1937 if (min_val < 0) { 1938 dst_reg->min_align = 1; 1939 } else { 1940 dst_reg->min_align >>= (u64) min_val; 1941 if (!dst_reg->min_align) 1942 dst_reg->min_align = 1; 1943 } 1944 if (dst_reg->max_value != BPF_REGISTER_MAX_RANGE) 1945 dst_reg->max_value >>= max_val; 1946 break; 1947 default: 1948 reset_reg_range_values(regs, insn->dst_reg); 1949 break; 1950 } 1951 1952 check_reg_overflow(dst_reg); 1953 } 1954 1955 /* check validity of 32-bit and 64-bit arithmetic operations */ 1956 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) 1957 { 1958 struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg; 1959 u8 opcode = BPF_OP(insn->code); 1960 int err; 1961 1962 if (opcode == BPF_END || opcode == BPF_NEG) { 1963 if (opcode == BPF_NEG) { 1964 if (BPF_SRC(insn->code) != 0 || 1965 insn->src_reg != BPF_REG_0 || 1966 insn->off != 0 || insn->imm != 0) { 1967 verbose("BPF_NEG uses reserved fields\n"); 1968 return -EINVAL; 1969 } 1970 } else { 1971 if (insn->src_reg != BPF_REG_0 || insn->off != 0 || 1972 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { 1973 verbose("BPF_END uses reserved fields\n"); 1974 return -EINVAL; 1975 } 1976 } 1977 1978 /* check src operand */ 1979 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1980 if (err) 1981 return err; 1982 1983 if (is_pointer_value(env, insn->dst_reg)) { 1984 verbose("R%d pointer arithmetic prohibited\n", 1985 insn->dst_reg); 1986 return -EACCES; 1987 } 1988 1989 /* check dest operand */ 1990 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1991 if (err) 1992 return err; 1993 1994 } else if (opcode == BPF_MOV) { 1995 1996 if (BPF_SRC(insn->code) == BPF_X) { 1997 if (insn->imm != 0 || insn->off != 0) { 1998 verbose("BPF_MOV uses reserved fields\n"); 1999 return -EINVAL; 2000 } 2001 2002 /* check src operand */ 2003 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2004 if (err) 2005 return err; 2006 } else { 2007 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 2008 verbose("BPF_MOV uses reserved fields\n"); 2009 return -EINVAL; 2010 } 2011 } 2012 2013 /* check dest operand */ 2014 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 2015 if (err) 2016 return err; 2017 2018 /* we are setting our register to something new, we need to 2019 * reset its range values. 2020 */ 2021 reset_reg_range_values(regs, insn->dst_reg); 2022 2023 if (BPF_SRC(insn->code) == BPF_X) { 2024 if (BPF_CLASS(insn->code) == BPF_ALU64) { 2025 /* case: R1 = R2 2026 * copy register state to dest reg 2027 */ 2028 regs[insn->dst_reg] = regs[insn->src_reg]; 2029 } else { 2030 if (is_pointer_value(env, insn->src_reg)) { 2031 verbose("R%d partial copy of pointer\n", 2032 insn->src_reg); 2033 return -EACCES; 2034 } 2035 mark_reg_unknown_value(regs, insn->dst_reg); 2036 } 2037 } else { 2038 /* case: R = imm 2039 * remember the value we stored into this reg 2040 */ 2041 regs[insn->dst_reg].type = CONST_IMM; 2042 regs[insn->dst_reg].imm = insn->imm; 2043 regs[insn->dst_reg].id = 0; 2044 regs[insn->dst_reg].max_value = insn->imm; 2045 regs[insn->dst_reg].min_value = insn->imm; 2046 regs[insn->dst_reg].min_align = calc_align(insn->imm); 2047 regs[insn->dst_reg].value_from_signed = false; 2048 } 2049 2050 } else if (opcode > BPF_END) { 2051 verbose("invalid BPF_ALU opcode %x\n", opcode); 2052 return -EINVAL; 2053 2054 } else { /* all other ALU ops: and, sub, xor, add, ... */ 2055 2056 if (BPF_SRC(insn->code) == BPF_X) { 2057 if (insn->imm != 0 || insn->off != 0) { 2058 verbose("BPF_ALU uses reserved fields\n"); 2059 return -EINVAL; 2060 } 2061 /* check src1 operand */ 2062 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2063 if (err) 2064 return err; 2065 } else { 2066 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 2067 verbose("BPF_ALU uses reserved fields\n"); 2068 return -EINVAL; 2069 } 2070 } 2071 2072 /* check src2 operand */ 2073 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 2074 if (err) 2075 return err; 2076 2077 if ((opcode == BPF_MOD || opcode == BPF_DIV) && 2078 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { 2079 verbose("div by zero\n"); 2080 return -EINVAL; 2081 } 2082 2083 if ((opcode == BPF_LSH || opcode == BPF_RSH || 2084 opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) { 2085 int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32; 2086 2087 if (insn->imm < 0 || insn->imm >= size) { 2088 verbose("invalid shift %d\n", insn->imm); 2089 return -EINVAL; 2090 } 2091 } 2092 2093 /* check dest operand */ 2094 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 2095 if (err) 2096 return err; 2097 2098 dst_reg = ®s[insn->dst_reg]; 2099 2100 /* first we want to adjust our ranges. */ 2101 adjust_reg_min_max_vals(env, insn); 2102 2103 /* pattern match 'bpf_add Rx, imm' instruction */ 2104 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && 2105 dst_reg->type == FRAME_PTR && BPF_SRC(insn->code) == BPF_K) { 2106 dst_reg->type = PTR_TO_STACK; 2107 dst_reg->imm = insn->imm; 2108 return 0; 2109 } else if (opcode == BPF_ADD && 2110 BPF_CLASS(insn->code) == BPF_ALU64 && 2111 dst_reg->type == PTR_TO_STACK && 2112 ((BPF_SRC(insn->code) == BPF_X && 2113 regs[insn->src_reg].type == CONST_IMM) || 2114 BPF_SRC(insn->code) == BPF_K)) { 2115 if (BPF_SRC(insn->code) == BPF_X) 2116 dst_reg->imm += regs[insn->src_reg].imm; 2117 else 2118 dst_reg->imm += insn->imm; 2119 return 0; 2120 } else if (opcode == BPF_ADD && 2121 BPF_CLASS(insn->code) == BPF_ALU64 && 2122 (dst_reg->type == PTR_TO_PACKET || 2123 (BPF_SRC(insn->code) == BPF_X && 2124 regs[insn->src_reg].type == PTR_TO_PACKET))) { 2125 /* ptr_to_packet += K|X */ 2126 return check_packet_ptr_add(env, insn); 2127 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 2128 dst_reg->type == UNKNOWN_VALUE && 2129 env->allow_ptr_leaks) { 2130 /* unknown += K|X */ 2131 return evaluate_reg_alu(env, insn); 2132 } else if (BPF_CLASS(insn->code) == BPF_ALU64 && 2133 dst_reg->type == CONST_IMM && 2134 env->allow_ptr_leaks) { 2135 /* reg_imm += K|X */ 2136 return evaluate_reg_imm_alu(env, insn); 2137 } else if (is_pointer_value(env, insn->dst_reg)) { 2138 verbose("R%d pointer arithmetic prohibited\n", 2139 insn->dst_reg); 2140 return -EACCES; 2141 } else if (BPF_SRC(insn->code) == BPF_X && 2142 is_pointer_value(env, insn->src_reg)) { 2143 verbose("R%d pointer arithmetic prohibited\n", 2144 insn->src_reg); 2145 return -EACCES; 2146 } 2147 2148 /* If we did pointer math on a map value then just set it to our 2149 * PTR_TO_MAP_VALUE_ADJ type so we can deal with any stores or 2150 * loads to this register appropriately, otherwise just mark the 2151 * register as unknown. 2152 */ 2153 if (env->allow_ptr_leaks && 2154 BPF_CLASS(insn->code) == BPF_ALU64 && opcode == BPF_ADD && 2155 (dst_reg->type == PTR_TO_MAP_VALUE || 2156 dst_reg->type == PTR_TO_MAP_VALUE_ADJ)) 2157 dst_reg->type = PTR_TO_MAP_VALUE_ADJ; 2158 else 2159 mark_reg_unknown_value(regs, insn->dst_reg); 2160 } 2161 2162 return 0; 2163 } 2164 2165 static void find_good_pkt_pointers(struct bpf_verifier_state *state, 2166 struct bpf_reg_state *dst_reg) 2167 { 2168 struct bpf_reg_state *regs = state->regs, *reg; 2169 int i; 2170 2171 /* LLVM can generate two kind of checks: 2172 * 2173 * Type 1: 2174 * 2175 * r2 = r3; 2176 * r2 += 8; 2177 * if (r2 > pkt_end) goto <handle exception> 2178 * <access okay> 2179 * 2180 * Where: 2181 * r2 == dst_reg, pkt_end == src_reg 2182 * r2=pkt(id=n,off=8,r=0) 2183 * r3=pkt(id=n,off=0,r=0) 2184 * 2185 * Type 2: 2186 * 2187 * r2 = r3; 2188 * r2 += 8; 2189 * if (pkt_end >= r2) goto <access okay> 2190 * <handle exception> 2191 * 2192 * Where: 2193 * pkt_end == dst_reg, r2 == src_reg 2194 * r2=pkt(id=n,off=8,r=0) 2195 * r3=pkt(id=n,off=0,r=0) 2196 * 2197 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8) 2198 * so that range of bytes [r3, r3 + 8) is safe to access. 2199 */ 2200 2201 for (i = 0; i < MAX_BPF_REG; i++) 2202 if (regs[i].type == PTR_TO_PACKET && regs[i].id == dst_reg->id) 2203 /* keep the maximum range already checked */ 2204 regs[i].range = max(regs[i].range, dst_reg->off); 2205 2206 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 2207 if (state->stack_slot_type[i] != STACK_SPILL) 2208 continue; 2209 reg = &state->spilled_regs[i / BPF_REG_SIZE]; 2210 if (reg->type == PTR_TO_PACKET && reg->id == dst_reg->id) 2211 reg->range = max(reg->range, dst_reg->off); 2212 } 2213 } 2214 2215 /* Adjusts the register min/max values in the case that the dst_reg is the 2216 * variable register that we are working on, and src_reg is a constant or we're 2217 * simply doing a BPF_K check. 2218 */ 2219 static void reg_set_min_max(struct bpf_reg_state *true_reg, 2220 struct bpf_reg_state *false_reg, u64 val, 2221 u8 opcode) 2222 { 2223 bool value_from_signed = true; 2224 bool is_range = true; 2225 2226 switch (opcode) { 2227 case BPF_JEQ: 2228 /* If this is false then we know nothing Jon Snow, but if it is 2229 * true then we know for sure. 2230 */ 2231 true_reg->max_value = true_reg->min_value = val; 2232 is_range = false; 2233 break; 2234 case BPF_JNE: 2235 /* If this is true we know nothing Jon Snow, but if it is false 2236 * we know the value for sure; 2237 */ 2238 false_reg->max_value = false_reg->min_value = val; 2239 is_range = false; 2240 break; 2241 case BPF_JGT: 2242 value_from_signed = false; 2243 /* fallthrough */ 2244 case BPF_JSGT: 2245 if (true_reg->value_from_signed != value_from_signed) 2246 reset_reg_range_values(true_reg, 0); 2247 if (false_reg->value_from_signed != value_from_signed) 2248 reset_reg_range_values(false_reg, 0); 2249 if (opcode == BPF_JGT) { 2250 /* Unsigned comparison, the minimum value is 0. */ 2251 false_reg->min_value = 0; 2252 } 2253 /* If this is false then we know the maximum val is val, 2254 * otherwise we know the min val is val+1. 2255 */ 2256 false_reg->max_value = val; 2257 false_reg->value_from_signed = value_from_signed; 2258 true_reg->min_value = val + 1; 2259 true_reg->value_from_signed = value_from_signed; 2260 break; 2261 case BPF_JGE: 2262 value_from_signed = false; 2263 /* fallthrough */ 2264 case BPF_JSGE: 2265 if (true_reg->value_from_signed != value_from_signed) 2266 reset_reg_range_values(true_reg, 0); 2267 if (false_reg->value_from_signed != value_from_signed) 2268 reset_reg_range_values(false_reg, 0); 2269 if (opcode == BPF_JGE) { 2270 /* Unsigned comparison, the minimum value is 0. */ 2271 false_reg->min_value = 0; 2272 } 2273 /* If this is false then we know the maximum value is val - 1, 2274 * otherwise we know the mimimum value is val. 2275 */ 2276 false_reg->max_value = val - 1; 2277 false_reg->value_from_signed = value_from_signed; 2278 true_reg->min_value = val; 2279 true_reg->value_from_signed = value_from_signed; 2280 break; 2281 default: 2282 break; 2283 } 2284 2285 check_reg_overflow(false_reg); 2286 check_reg_overflow(true_reg); 2287 if (is_range) { 2288 if (__is_pointer_value(false, false_reg)) 2289 reset_reg_range_values(false_reg, 0); 2290 if (__is_pointer_value(false, true_reg)) 2291 reset_reg_range_values(true_reg, 0); 2292 } 2293 } 2294 2295 /* Same as above, but for the case that dst_reg is a CONST_IMM reg and src_reg 2296 * is the variable reg. 2297 */ 2298 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, 2299 struct bpf_reg_state *false_reg, u64 val, 2300 u8 opcode) 2301 { 2302 bool value_from_signed = true; 2303 bool is_range = true; 2304 2305 switch (opcode) { 2306 case BPF_JEQ: 2307 /* If this is false then we know nothing Jon Snow, but if it is 2308 * true then we know for sure. 2309 */ 2310 true_reg->max_value = true_reg->min_value = val; 2311 is_range = false; 2312 break; 2313 case BPF_JNE: 2314 /* If this is true we know nothing Jon Snow, but if it is false 2315 * we know the value for sure; 2316 */ 2317 false_reg->max_value = false_reg->min_value = val; 2318 is_range = false; 2319 break; 2320 case BPF_JGT: 2321 value_from_signed = false; 2322 /* fallthrough */ 2323 case BPF_JSGT: 2324 if (true_reg->value_from_signed != value_from_signed) 2325 reset_reg_range_values(true_reg, 0); 2326 if (false_reg->value_from_signed != value_from_signed) 2327 reset_reg_range_values(false_reg, 0); 2328 if (opcode == BPF_JGT) { 2329 /* Unsigned comparison, the minimum value is 0. */ 2330 true_reg->min_value = 0; 2331 } 2332 /* 2333 * If this is false, then the val is <= the register, if it is 2334 * true the register <= to the val. 2335 */ 2336 false_reg->min_value = val; 2337 false_reg->value_from_signed = value_from_signed; 2338 true_reg->max_value = val - 1; 2339 true_reg->value_from_signed = value_from_signed; 2340 break; 2341 case BPF_JGE: 2342 value_from_signed = false; 2343 /* fallthrough */ 2344 case BPF_JSGE: 2345 if (true_reg->value_from_signed != value_from_signed) 2346 reset_reg_range_values(true_reg, 0); 2347 if (false_reg->value_from_signed != value_from_signed) 2348 reset_reg_range_values(false_reg, 0); 2349 if (opcode == BPF_JGE) { 2350 /* Unsigned comparison, the minimum value is 0. */ 2351 true_reg->min_value = 0; 2352 } 2353 /* If this is false then constant < register, if it is true then 2354 * the register < constant. 2355 */ 2356 false_reg->min_value = val + 1; 2357 false_reg->value_from_signed = value_from_signed; 2358 true_reg->max_value = val; 2359 true_reg->value_from_signed = value_from_signed; 2360 break; 2361 default: 2362 break; 2363 } 2364 2365 check_reg_overflow(false_reg); 2366 check_reg_overflow(true_reg); 2367 if (is_range) { 2368 if (__is_pointer_value(false, false_reg)) 2369 reset_reg_range_values(false_reg, 0); 2370 if (__is_pointer_value(false, true_reg)) 2371 reset_reg_range_values(true_reg, 0); 2372 } 2373 } 2374 2375 static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id, 2376 enum bpf_reg_type type) 2377 { 2378 struct bpf_reg_state *reg = ®s[regno]; 2379 2380 if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) { 2381 if (type == UNKNOWN_VALUE) { 2382 __mark_reg_unknown_value(regs, regno); 2383 } else if (reg->map_ptr->inner_map_meta) { 2384 reg->type = CONST_PTR_TO_MAP; 2385 reg->map_ptr = reg->map_ptr->inner_map_meta; 2386 } else { 2387 reg->type = type; 2388 } 2389 /* We don't need id from this point onwards anymore, thus we 2390 * should better reset it, so that state pruning has chances 2391 * to take effect. 2392 */ 2393 reg->id = 0; 2394 } 2395 } 2396 2397 /* The logic is similar to find_good_pkt_pointers(), both could eventually 2398 * be folded together at some point. 2399 */ 2400 static void mark_map_regs(struct bpf_verifier_state *state, u32 regno, 2401 enum bpf_reg_type type) 2402 { 2403 struct bpf_reg_state *regs = state->regs; 2404 u32 id = regs[regno].id; 2405 int i; 2406 2407 for (i = 0; i < MAX_BPF_REG; i++) 2408 mark_map_reg(regs, i, id, type); 2409 2410 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 2411 if (state->stack_slot_type[i] != STACK_SPILL) 2412 continue; 2413 mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, type); 2414 } 2415 } 2416 2417 static int check_cond_jmp_op(struct bpf_verifier_env *env, 2418 struct bpf_insn *insn, int *insn_idx) 2419 { 2420 struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state; 2421 struct bpf_reg_state *regs = this_branch->regs, *dst_reg; 2422 u8 opcode = BPF_OP(insn->code); 2423 int err; 2424 2425 if (opcode > BPF_EXIT) { 2426 verbose("invalid BPF_JMP opcode %x\n", opcode); 2427 return -EINVAL; 2428 } 2429 2430 if (BPF_SRC(insn->code) == BPF_X) { 2431 if (insn->imm != 0) { 2432 verbose("BPF_JMP uses reserved fields\n"); 2433 return -EINVAL; 2434 } 2435 2436 /* check src1 operand */ 2437 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2438 if (err) 2439 return err; 2440 2441 if (is_pointer_value(env, insn->src_reg)) { 2442 verbose("R%d pointer comparison prohibited\n", 2443 insn->src_reg); 2444 return -EACCES; 2445 } 2446 } else { 2447 if (insn->src_reg != BPF_REG_0) { 2448 verbose("BPF_JMP uses reserved fields\n"); 2449 return -EINVAL; 2450 } 2451 } 2452 2453 /* check src2 operand */ 2454 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 2455 if (err) 2456 return err; 2457 2458 dst_reg = ®s[insn->dst_reg]; 2459 2460 /* detect if R == 0 where R was initialized to zero earlier */ 2461 if (BPF_SRC(insn->code) == BPF_K && 2462 (opcode == BPF_JEQ || opcode == BPF_JNE) && 2463 dst_reg->type == CONST_IMM && dst_reg->imm == insn->imm) { 2464 if (opcode == BPF_JEQ) { 2465 /* if (imm == imm) goto pc+off; 2466 * only follow the goto, ignore fall-through 2467 */ 2468 *insn_idx += insn->off; 2469 return 0; 2470 } else { 2471 /* if (imm != imm) goto pc+off; 2472 * only follow fall-through branch, since 2473 * that's where the program will go 2474 */ 2475 return 0; 2476 } 2477 } 2478 2479 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); 2480 if (!other_branch) 2481 return -EFAULT; 2482 2483 /* detect if we are comparing against a constant value so we can adjust 2484 * our min/max values for our dst register. 2485 */ 2486 if (BPF_SRC(insn->code) == BPF_X) { 2487 if (regs[insn->src_reg].type == CONST_IMM) 2488 reg_set_min_max(&other_branch->regs[insn->dst_reg], 2489 dst_reg, regs[insn->src_reg].imm, 2490 opcode); 2491 else if (dst_reg->type == CONST_IMM) 2492 reg_set_min_max_inv(&other_branch->regs[insn->src_reg], 2493 ®s[insn->src_reg], dst_reg->imm, 2494 opcode); 2495 } else { 2496 reg_set_min_max(&other_branch->regs[insn->dst_reg], 2497 dst_reg, insn->imm, opcode); 2498 } 2499 2500 /* detect if R == 0 where R is returned from bpf_map_lookup_elem() */ 2501 if (BPF_SRC(insn->code) == BPF_K && 2502 insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) && 2503 dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) { 2504 /* Mark all identical map registers in each branch as either 2505 * safe or unknown depending R == 0 or R != 0 conditional. 2506 */ 2507 mark_map_regs(this_branch, insn->dst_reg, 2508 opcode == BPF_JEQ ? PTR_TO_MAP_VALUE : UNKNOWN_VALUE); 2509 mark_map_regs(other_branch, insn->dst_reg, 2510 opcode == BPF_JEQ ? UNKNOWN_VALUE : PTR_TO_MAP_VALUE); 2511 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT && 2512 dst_reg->type == PTR_TO_PACKET && 2513 regs[insn->src_reg].type == PTR_TO_PACKET_END) { 2514 find_good_pkt_pointers(this_branch, dst_reg); 2515 } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE && 2516 dst_reg->type == PTR_TO_PACKET_END && 2517 regs[insn->src_reg].type == PTR_TO_PACKET) { 2518 find_good_pkt_pointers(other_branch, ®s[insn->src_reg]); 2519 } else if (is_pointer_value(env, insn->dst_reg)) { 2520 verbose("R%d pointer comparison prohibited\n", insn->dst_reg); 2521 return -EACCES; 2522 } 2523 if (log_level) 2524 print_verifier_state(this_branch); 2525 return 0; 2526 } 2527 2528 /* return the map pointer stored inside BPF_LD_IMM64 instruction */ 2529 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) 2530 { 2531 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; 2532 2533 return (struct bpf_map *) (unsigned long) imm64; 2534 } 2535 2536 /* verify BPF_LD_IMM64 instruction */ 2537 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) 2538 { 2539 struct bpf_reg_state *regs = env->cur_state.regs; 2540 int err; 2541 2542 if (BPF_SIZE(insn->code) != BPF_DW) { 2543 verbose("invalid BPF_LD_IMM insn\n"); 2544 return -EINVAL; 2545 } 2546 if (insn->off != 0) { 2547 verbose("BPF_LD_IMM64 uses reserved fields\n"); 2548 return -EINVAL; 2549 } 2550 2551 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 2552 if (err) 2553 return err; 2554 2555 if (insn->src_reg == 0) { 2556 u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; 2557 2558 regs[insn->dst_reg].type = CONST_IMM; 2559 regs[insn->dst_reg].imm = imm; 2560 regs[insn->dst_reg].id = 0; 2561 return 0; 2562 } 2563 2564 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ 2565 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); 2566 2567 regs[insn->dst_reg].type = CONST_PTR_TO_MAP; 2568 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); 2569 return 0; 2570 } 2571 2572 static bool may_access_skb(enum bpf_prog_type type) 2573 { 2574 switch (type) { 2575 case BPF_PROG_TYPE_SOCKET_FILTER: 2576 case BPF_PROG_TYPE_SCHED_CLS: 2577 case BPF_PROG_TYPE_SCHED_ACT: 2578 return true; 2579 default: 2580 return false; 2581 } 2582 } 2583 2584 /* verify safety of LD_ABS|LD_IND instructions: 2585 * - they can only appear in the programs where ctx == skb 2586 * - since they are wrappers of function calls, they scratch R1-R5 registers, 2587 * preserve R6-R9, and store return value into R0 2588 * 2589 * Implicit input: 2590 * ctx == skb == R6 == CTX 2591 * 2592 * Explicit input: 2593 * SRC == any register 2594 * IMM == 32-bit immediate 2595 * 2596 * Output: 2597 * R0 - 8/16/32-bit skb data converted to cpu endianness 2598 */ 2599 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) 2600 { 2601 struct bpf_reg_state *regs = env->cur_state.regs; 2602 u8 mode = BPF_MODE(insn->code); 2603 int i, err; 2604 2605 if (!may_access_skb(env->prog->type)) { 2606 verbose("BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); 2607 return -EINVAL; 2608 } 2609 2610 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || 2611 BPF_SIZE(insn->code) == BPF_DW || 2612 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { 2613 verbose("BPF_LD_[ABS|IND] uses reserved fields\n"); 2614 return -EINVAL; 2615 } 2616 2617 /* check whether implicit source operand (register R6) is readable */ 2618 err = check_reg_arg(regs, BPF_REG_6, SRC_OP); 2619 if (err) 2620 return err; 2621 2622 if (regs[BPF_REG_6].type != PTR_TO_CTX) { 2623 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); 2624 return -EINVAL; 2625 } 2626 2627 if (mode == BPF_IND) { 2628 /* check explicit source operand */ 2629 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 2630 if (err) 2631 return err; 2632 } 2633 2634 /* reset caller saved regs to unreadable */ 2635 for (i = 0; i < CALLER_SAVED_REGS; i++) 2636 mark_reg_not_init(regs, caller_saved[i]); 2637 2638 /* mark destination R0 register as readable, since it contains 2639 * the value fetched from the packet 2640 */ 2641 regs[BPF_REG_0].type = UNKNOWN_VALUE; 2642 return 0; 2643 } 2644 2645 /* non-recursive DFS pseudo code 2646 * 1 procedure DFS-iterative(G,v): 2647 * 2 label v as discovered 2648 * 3 let S be a stack 2649 * 4 S.push(v) 2650 * 5 while S is not empty 2651 * 6 t <- S.pop() 2652 * 7 if t is what we're looking for: 2653 * 8 return t 2654 * 9 for all edges e in G.adjacentEdges(t) do 2655 * 10 if edge e is already labelled 2656 * 11 continue with the next edge 2657 * 12 w <- G.adjacentVertex(t,e) 2658 * 13 if vertex w is not discovered and not explored 2659 * 14 label e as tree-edge 2660 * 15 label w as discovered 2661 * 16 S.push(w) 2662 * 17 continue at 5 2663 * 18 else if vertex w is discovered 2664 * 19 label e as back-edge 2665 * 20 else 2666 * 21 // vertex w is explored 2667 * 22 label e as forward- or cross-edge 2668 * 23 label t as explored 2669 * 24 S.pop() 2670 * 2671 * convention: 2672 * 0x10 - discovered 2673 * 0x11 - discovered and fall-through edge labelled 2674 * 0x12 - discovered and fall-through and branch edges labelled 2675 * 0x20 - explored 2676 */ 2677 2678 enum { 2679 DISCOVERED = 0x10, 2680 EXPLORED = 0x20, 2681 FALLTHROUGH = 1, 2682 BRANCH = 2, 2683 }; 2684 2685 #define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L) 2686 2687 static int *insn_stack; /* stack of insns to process */ 2688 static int cur_stack; /* current stack index */ 2689 static int *insn_state; 2690 2691 /* t, w, e - match pseudo-code above: 2692 * t - index of current instruction 2693 * w - next instruction 2694 * e - edge 2695 */ 2696 static int push_insn(int t, int w, int e, struct bpf_verifier_env *env) 2697 { 2698 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) 2699 return 0; 2700 2701 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) 2702 return 0; 2703 2704 if (w < 0 || w >= env->prog->len) { 2705 verbose("jump out of range from insn %d to %d\n", t, w); 2706 return -EINVAL; 2707 } 2708 2709 if (e == BRANCH) 2710 /* mark branch target for state pruning */ 2711 env->explored_states[w] = STATE_LIST_MARK; 2712 2713 if (insn_state[w] == 0) { 2714 /* tree-edge */ 2715 insn_state[t] = DISCOVERED | e; 2716 insn_state[w] = DISCOVERED; 2717 if (cur_stack >= env->prog->len) 2718 return -E2BIG; 2719 insn_stack[cur_stack++] = w; 2720 return 1; 2721 } else if ((insn_state[w] & 0xF0) == DISCOVERED) { 2722 verbose("back-edge from insn %d to %d\n", t, w); 2723 return -EINVAL; 2724 } else if (insn_state[w] == EXPLORED) { 2725 /* forward- or cross-edge */ 2726 insn_state[t] = DISCOVERED | e; 2727 } else { 2728 verbose("insn state internal bug\n"); 2729 return -EFAULT; 2730 } 2731 return 0; 2732 } 2733 2734 /* non-recursive depth-first-search to detect loops in BPF program 2735 * loop == back-edge in directed graph 2736 */ 2737 static int check_cfg(struct bpf_verifier_env *env) 2738 { 2739 struct bpf_insn *insns = env->prog->insnsi; 2740 int insn_cnt = env->prog->len; 2741 int ret = 0; 2742 int i, t; 2743 2744 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2745 if (!insn_state) 2746 return -ENOMEM; 2747 2748 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 2749 if (!insn_stack) { 2750 kfree(insn_state); 2751 return -ENOMEM; 2752 } 2753 2754 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ 2755 insn_stack[0] = 0; /* 0 is the first instruction */ 2756 cur_stack = 1; 2757 2758 peek_stack: 2759 if (cur_stack == 0) 2760 goto check_state; 2761 t = insn_stack[cur_stack - 1]; 2762 2763 if (BPF_CLASS(insns[t].code) == BPF_JMP) { 2764 u8 opcode = BPF_OP(insns[t].code); 2765 2766 if (opcode == BPF_EXIT) { 2767 goto mark_explored; 2768 } else if (opcode == BPF_CALL) { 2769 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2770 if (ret == 1) 2771 goto peek_stack; 2772 else if (ret < 0) 2773 goto err_free; 2774 if (t + 1 < insn_cnt) 2775 env->explored_states[t + 1] = STATE_LIST_MARK; 2776 } else if (opcode == BPF_JA) { 2777 if (BPF_SRC(insns[t].code) != BPF_K) { 2778 ret = -EINVAL; 2779 goto err_free; 2780 } 2781 /* unconditional jump with single edge */ 2782 ret = push_insn(t, t + insns[t].off + 1, 2783 FALLTHROUGH, env); 2784 if (ret == 1) 2785 goto peek_stack; 2786 else if (ret < 0) 2787 goto err_free; 2788 /* tell verifier to check for equivalent states 2789 * after every call and jump 2790 */ 2791 if (t + 1 < insn_cnt) 2792 env->explored_states[t + 1] = STATE_LIST_MARK; 2793 } else { 2794 /* conditional jump with two edges */ 2795 env->explored_states[t] = STATE_LIST_MARK; 2796 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2797 if (ret == 1) 2798 goto peek_stack; 2799 else if (ret < 0) 2800 goto err_free; 2801 2802 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); 2803 if (ret == 1) 2804 goto peek_stack; 2805 else if (ret < 0) 2806 goto err_free; 2807 } 2808 } else { 2809 /* all other non-branch instructions with single 2810 * fall-through edge 2811 */ 2812 ret = push_insn(t, t + 1, FALLTHROUGH, env); 2813 if (ret == 1) 2814 goto peek_stack; 2815 else if (ret < 0) 2816 goto err_free; 2817 } 2818 2819 mark_explored: 2820 insn_state[t] = EXPLORED; 2821 if (cur_stack-- <= 0) { 2822 verbose("pop stack internal bug\n"); 2823 ret = -EFAULT; 2824 goto err_free; 2825 } 2826 goto peek_stack; 2827 2828 check_state: 2829 for (i = 0; i < insn_cnt; i++) { 2830 if (insn_state[i] != EXPLORED) { 2831 verbose("unreachable insn %d\n", i); 2832 ret = -EINVAL; 2833 goto err_free; 2834 } 2835 } 2836 ret = 0; /* cfg looks good */ 2837 2838 err_free: 2839 kfree(insn_state); 2840 kfree(insn_stack); 2841 return ret; 2842 } 2843 2844 /* the following conditions reduce the number of explored insns 2845 * from ~140k to ~80k for ultra large programs that use a lot of ptr_to_packet 2846 */ 2847 static bool compare_ptrs_to_packet(struct bpf_verifier_env *env, 2848 struct bpf_reg_state *old, 2849 struct bpf_reg_state *cur) 2850 { 2851 if (old->id != cur->id) 2852 return false; 2853 2854 /* old ptr_to_packet is more conservative, since it allows smaller 2855 * range. Ex: 2856 * old(off=0,r=10) is equal to cur(off=0,r=20), because 2857 * old(off=0,r=10) means that with range=10 the verifier proceeded 2858 * further and found no issues with the program. Now we're in the same 2859 * spot with cur(off=0,r=20), so we're safe too, since anything further 2860 * will only be looking at most 10 bytes after this pointer. 2861 */ 2862 if (old->off == cur->off && old->range < cur->range) 2863 return true; 2864 2865 /* old(off=20,r=10) is equal to cur(off=22,re=22 or 5 or 0) 2866 * since both cannot be used for packet access and safe(old) 2867 * pointer has smaller off that could be used for further 2868 * 'if (ptr > data_end)' check 2869 * Ex: 2870 * old(off=20,r=10) and cur(off=22,r=22) and cur(off=22,r=0) mean 2871 * that we cannot access the packet. 2872 * The safe range is: 2873 * [ptr, ptr + range - off) 2874 * so whenever off >=range, it means no safe bytes from this pointer. 2875 * When comparing old->off <= cur->off, it means that older code 2876 * went with smaller offset and that offset was later 2877 * used to figure out the safe range after 'if (ptr > data_end)' check 2878 * Say, 'old' state was explored like: 2879 * ... R3(off=0, r=0) 2880 * R4 = R3 + 20 2881 * ... now R4(off=20,r=0) <-- here 2882 * if (R4 > data_end) 2883 * ... R4(off=20,r=20), R3(off=0,r=20) and R3 can be used to access. 2884 * ... the code further went all the way to bpf_exit. 2885 * Now the 'cur' state at the mark 'here' has R4(off=30,r=0). 2886 * old_R4(off=20,r=0) equal to cur_R4(off=30,r=0), since if the verifier 2887 * goes further, such cur_R4 will give larger safe packet range after 2888 * 'if (R4 > data_end)' and all further insn were already good with r=20, 2889 * so they will be good with r=30 and we can prune the search. 2890 */ 2891 if (!env->strict_alignment && old->off <= cur->off && 2892 old->off >= old->range && cur->off >= cur->range) 2893 return true; 2894 2895 return false; 2896 } 2897 2898 /* compare two verifier states 2899 * 2900 * all states stored in state_list are known to be valid, since 2901 * verifier reached 'bpf_exit' instruction through them 2902 * 2903 * this function is called when verifier exploring different branches of 2904 * execution popped from the state stack. If it sees an old state that has 2905 * more strict register state and more strict stack state then this execution 2906 * branch doesn't need to be explored further, since verifier already 2907 * concluded that more strict state leads to valid finish. 2908 * 2909 * Therefore two states are equivalent if register state is more conservative 2910 * and explored stack state is more conservative than the current one. 2911 * Example: 2912 * explored current 2913 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) 2914 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) 2915 * 2916 * In other words if current stack state (one being explored) has more 2917 * valid slots than old one that already passed validation, it means 2918 * the verifier can stop exploring and conclude that current state is valid too 2919 * 2920 * Similarly with registers. If explored state has register type as invalid 2921 * whereas register type in current state is meaningful, it means that 2922 * the current state will reach 'bpf_exit' instruction safely 2923 */ 2924 static bool states_equal(struct bpf_verifier_env *env, 2925 struct bpf_verifier_state *old, 2926 struct bpf_verifier_state *cur) 2927 { 2928 bool varlen_map_access = env->varlen_map_value_access; 2929 struct bpf_reg_state *rold, *rcur; 2930 int i; 2931 2932 for (i = 0; i < MAX_BPF_REG; i++) { 2933 rold = &old->regs[i]; 2934 rcur = &cur->regs[i]; 2935 2936 if (memcmp(rold, rcur, sizeof(*rold)) == 0) 2937 continue; 2938 2939 /* If the ranges were not the same, but everything else was and 2940 * we didn't do a variable access into a map then we are a-ok. 2941 */ 2942 if (!varlen_map_access && 2943 memcmp(rold, rcur, offsetofend(struct bpf_reg_state, id)) == 0) 2944 continue; 2945 2946 /* If we didn't map access then again we don't care about the 2947 * mismatched range values and it's ok if our old type was 2948 * UNKNOWN and we didn't go to a NOT_INIT'ed reg. 2949 */ 2950 if (rold->type == NOT_INIT || 2951 (!varlen_map_access && rold->type == UNKNOWN_VALUE && 2952 rcur->type != NOT_INIT)) 2953 continue; 2954 2955 /* Don't care about the reg->id in this case. */ 2956 if (rold->type == PTR_TO_MAP_VALUE_OR_NULL && 2957 rcur->type == PTR_TO_MAP_VALUE_OR_NULL && 2958 rold->map_ptr == rcur->map_ptr) 2959 continue; 2960 2961 if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && 2962 compare_ptrs_to_packet(env, rold, rcur)) 2963 continue; 2964 2965 return false; 2966 } 2967 2968 for (i = 0; i < MAX_BPF_STACK; i++) { 2969 if (old->stack_slot_type[i] == STACK_INVALID) 2970 continue; 2971 if (old->stack_slot_type[i] != cur->stack_slot_type[i]) 2972 /* Ex: old explored (safe) state has STACK_SPILL in 2973 * this stack slot, but current has has STACK_MISC -> 2974 * this verifier states are not equivalent, 2975 * return false to continue verification of this path 2976 */ 2977 return false; 2978 if (i % BPF_REG_SIZE) 2979 continue; 2980 if (old->stack_slot_type[i] != STACK_SPILL) 2981 continue; 2982 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], 2983 &cur->spilled_regs[i / BPF_REG_SIZE], 2984 sizeof(old->spilled_regs[0]))) 2985 /* when explored and current stack slot types are 2986 * the same, check that stored pointers types 2987 * are the same as well. 2988 * Ex: explored safe path could have stored 2989 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -8} 2990 * but current path has stored: 2991 * (bpf_reg_state) {.type = PTR_TO_STACK, .imm = -16} 2992 * such verifier states are not equivalent. 2993 * return false to continue verification of this path 2994 */ 2995 return false; 2996 else 2997 continue; 2998 } 2999 return true; 3000 } 3001 3002 static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) 3003 { 3004 struct bpf_verifier_state_list *new_sl; 3005 struct bpf_verifier_state_list *sl; 3006 3007 sl = env->explored_states[insn_idx]; 3008 if (!sl) 3009 /* this 'insn_idx' instruction wasn't marked, so we will not 3010 * be doing state search here 3011 */ 3012 return 0; 3013 3014 while (sl != STATE_LIST_MARK) { 3015 if (states_equal(env, &sl->state, &env->cur_state)) 3016 /* reached equivalent register/stack state, 3017 * prune the search 3018 */ 3019 return 1; 3020 sl = sl->next; 3021 } 3022 3023 /* there were no equivalent states, remember current one. 3024 * technically the current state is not proven to be safe yet, 3025 * but it will either reach bpf_exit (which means it's safe) or 3026 * it will be rejected. Since there are no loops, we won't be 3027 * seeing this 'insn_idx' instruction again on the way to bpf_exit 3028 */ 3029 new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER); 3030 if (!new_sl) 3031 return -ENOMEM; 3032 3033 /* add new state to the head of linked list */ 3034 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); 3035 new_sl->next = env->explored_states[insn_idx]; 3036 env->explored_states[insn_idx] = new_sl; 3037 return 0; 3038 } 3039 3040 static int ext_analyzer_insn_hook(struct bpf_verifier_env *env, 3041 int insn_idx, int prev_insn_idx) 3042 { 3043 if (!env->analyzer_ops || !env->analyzer_ops->insn_hook) 3044 return 0; 3045 3046 return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx); 3047 } 3048 3049 static int do_check(struct bpf_verifier_env *env) 3050 { 3051 struct bpf_verifier_state *state = &env->cur_state; 3052 struct bpf_insn *insns = env->prog->insnsi; 3053 struct bpf_reg_state *regs = state->regs; 3054 int insn_cnt = env->prog->len; 3055 int insn_idx, prev_insn_idx = 0; 3056 int insn_processed = 0; 3057 bool do_print_state = false; 3058 3059 init_reg_state(regs); 3060 insn_idx = 0; 3061 env->varlen_map_value_access = false; 3062 for (;;) { 3063 struct bpf_insn *insn; 3064 u8 class; 3065 int err; 3066 3067 if (insn_idx >= insn_cnt) { 3068 verbose("invalid insn idx %d insn_cnt %d\n", 3069 insn_idx, insn_cnt); 3070 return -EFAULT; 3071 } 3072 3073 insn = &insns[insn_idx]; 3074 class = BPF_CLASS(insn->code); 3075 3076 if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) { 3077 verbose("BPF program is too large. Processed %d insn\n", 3078 insn_processed); 3079 return -E2BIG; 3080 } 3081 3082 err = is_state_visited(env, insn_idx); 3083 if (err < 0) 3084 return err; 3085 if (err == 1) { 3086 /* found equivalent state, can prune the search */ 3087 if (log_level) { 3088 if (do_print_state) 3089 verbose("\nfrom %d to %d: safe\n", 3090 prev_insn_idx, insn_idx); 3091 else 3092 verbose("%d: safe\n", insn_idx); 3093 } 3094 goto process_bpf_exit; 3095 } 3096 3097 if (need_resched()) 3098 cond_resched(); 3099 3100 if (log_level > 1 || (log_level && do_print_state)) { 3101 if (log_level > 1) 3102 verbose("%d:", insn_idx); 3103 else 3104 verbose("\nfrom %d to %d:", 3105 prev_insn_idx, insn_idx); 3106 print_verifier_state(&env->cur_state); 3107 do_print_state = false; 3108 } 3109 3110 if (log_level) { 3111 verbose("%d: ", insn_idx); 3112 print_bpf_insn(env, insn); 3113 } 3114 3115 err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx); 3116 if (err) 3117 return err; 3118 3119 if (class == BPF_ALU || class == BPF_ALU64) { 3120 err = check_alu_op(env, insn); 3121 if (err) 3122 return err; 3123 3124 } else if (class == BPF_LDX) { 3125 enum bpf_reg_type *prev_src_type, src_reg_type; 3126 3127 /* check for reserved fields is already done */ 3128 3129 /* check src operand */ 3130 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 3131 if (err) 3132 return err; 3133 3134 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 3135 if (err) 3136 return err; 3137 3138 src_reg_type = regs[insn->src_reg].type; 3139 3140 /* check that memory (src_reg + off) is readable, 3141 * the state of dst_reg will be updated by this func 3142 */ 3143 err = check_mem_access(env, insn_idx, insn->src_reg, insn->off, 3144 BPF_SIZE(insn->code), BPF_READ, 3145 insn->dst_reg); 3146 if (err) 3147 return err; 3148 3149 prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; 3150 3151 if (*prev_src_type == NOT_INIT) { 3152 /* saw a valid insn 3153 * dst_reg = *(u32 *)(src_reg + off) 3154 * save type to validate intersecting paths 3155 */ 3156 *prev_src_type = src_reg_type; 3157 3158 } else if (src_reg_type != *prev_src_type && 3159 (src_reg_type == PTR_TO_CTX || 3160 *prev_src_type == PTR_TO_CTX)) { 3161 /* ABuser program is trying to use the same insn 3162 * dst_reg = *(u32*) (src_reg + off) 3163 * with different pointer types: 3164 * src_reg == ctx in one branch and 3165 * src_reg == stack|map in some other branch. 3166 * Reject it. 3167 */ 3168 verbose("same insn cannot be used with different pointers\n"); 3169 return -EINVAL; 3170 } 3171 3172 } else if (class == BPF_STX) { 3173 enum bpf_reg_type *prev_dst_type, dst_reg_type; 3174 3175 if (BPF_MODE(insn->code) == BPF_XADD) { 3176 err = check_xadd(env, insn_idx, insn); 3177 if (err) 3178 return err; 3179 insn_idx++; 3180 continue; 3181 } 3182 3183 /* check src1 operand */ 3184 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 3185 if (err) 3186 return err; 3187 /* check src2 operand */ 3188 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 3189 if (err) 3190 return err; 3191 3192 dst_reg_type = regs[insn->dst_reg].type; 3193 3194 /* check that memory (dst_reg + off) is writeable */ 3195 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 3196 BPF_SIZE(insn->code), BPF_WRITE, 3197 insn->src_reg); 3198 if (err) 3199 return err; 3200 3201 prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; 3202 3203 if (*prev_dst_type == NOT_INIT) { 3204 *prev_dst_type = dst_reg_type; 3205 } else if (dst_reg_type != *prev_dst_type && 3206 (dst_reg_type == PTR_TO_CTX || 3207 *prev_dst_type == PTR_TO_CTX)) { 3208 verbose("same insn cannot be used with different pointers\n"); 3209 return -EINVAL; 3210 } 3211 3212 } else if (class == BPF_ST) { 3213 if (BPF_MODE(insn->code) != BPF_MEM || 3214 insn->src_reg != BPF_REG_0) { 3215 verbose("BPF_ST uses reserved fields\n"); 3216 return -EINVAL; 3217 } 3218 /* check src operand */ 3219 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 3220 if (err) 3221 return err; 3222 3223 /* check that memory (dst_reg + off) is writeable */ 3224 err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, 3225 BPF_SIZE(insn->code), BPF_WRITE, 3226 -1); 3227 if (err) 3228 return err; 3229 3230 } else if (class == BPF_JMP) { 3231 u8 opcode = BPF_OP(insn->code); 3232 3233 if (opcode == BPF_CALL) { 3234 if (BPF_SRC(insn->code) != BPF_K || 3235 insn->off != 0 || 3236 insn->src_reg != BPF_REG_0 || 3237 insn->dst_reg != BPF_REG_0) { 3238 verbose("BPF_CALL uses reserved fields\n"); 3239 return -EINVAL; 3240 } 3241 3242 err = check_call(env, insn->imm, insn_idx); 3243 if (err) 3244 return err; 3245 3246 } else if (opcode == BPF_JA) { 3247 if (BPF_SRC(insn->code) != BPF_K || 3248 insn->imm != 0 || 3249 insn->src_reg != BPF_REG_0 || 3250 insn->dst_reg != BPF_REG_0) { 3251 verbose("BPF_JA uses reserved fields\n"); 3252 return -EINVAL; 3253 } 3254 3255 insn_idx += insn->off + 1; 3256 continue; 3257 3258 } else if (opcode == BPF_EXIT) { 3259 if (BPF_SRC(insn->code) != BPF_K || 3260 insn->imm != 0 || 3261 insn->src_reg != BPF_REG_0 || 3262 insn->dst_reg != BPF_REG_0) { 3263 verbose("BPF_EXIT uses reserved fields\n"); 3264 return -EINVAL; 3265 } 3266 3267 /* eBPF calling convetion is such that R0 is used 3268 * to return the value from eBPF program. 3269 * Make sure that it's readable at this time 3270 * of bpf_exit, which means that program wrote 3271 * something into it earlier 3272 */ 3273 err = check_reg_arg(regs, BPF_REG_0, SRC_OP); 3274 if (err) 3275 return err; 3276 3277 if (is_pointer_value(env, BPF_REG_0)) { 3278 verbose("R0 leaks addr as return value\n"); 3279 return -EACCES; 3280 } 3281 3282 process_bpf_exit: 3283 insn_idx = pop_stack(env, &prev_insn_idx); 3284 if (insn_idx < 0) { 3285 break; 3286 } else { 3287 do_print_state = true; 3288 continue; 3289 } 3290 } else { 3291 err = check_cond_jmp_op(env, insn, &insn_idx); 3292 if (err) 3293 return err; 3294 } 3295 } else if (class == BPF_LD) { 3296 u8 mode = BPF_MODE(insn->code); 3297 3298 if (mode == BPF_ABS || mode == BPF_IND) { 3299 err = check_ld_abs(env, insn); 3300 if (err) 3301 return err; 3302 3303 } else if (mode == BPF_IMM) { 3304 err = check_ld_imm(env, insn); 3305 if (err) 3306 return err; 3307 3308 insn_idx++; 3309 } else { 3310 verbose("invalid BPF_LD mode\n"); 3311 return -EINVAL; 3312 } 3313 reset_reg_range_values(regs, insn->dst_reg); 3314 } else { 3315 verbose("unknown insn class %d\n", class); 3316 return -EINVAL; 3317 } 3318 3319 insn_idx++; 3320 } 3321 3322 verbose("processed %d insns, stack depth %d\n", 3323 insn_processed, env->prog->aux->stack_depth); 3324 return 0; 3325 } 3326 3327 static int check_map_prealloc(struct bpf_map *map) 3328 { 3329 return (map->map_type != BPF_MAP_TYPE_HASH && 3330 map->map_type != BPF_MAP_TYPE_PERCPU_HASH && 3331 map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) || 3332 !(map->map_flags & BPF_F_NO_PREALLOC); 3333 } 3334 3335 static int check_map_prog_compatibility(struct bpf_map *map, 3336 struct bpf_prog *prog) 3337 3338 { 3339 /* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use 3340 * preallocated hash maps, since doing memory allocation 3341 * in overflow_handler can crash depending on where nmi got 3342 * triggered. 3343 */ 3344 if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { 3345 if (!check_map_prealloc(map)) { 3346 verbose("perf_event programs can only use preallocated hash map\n"); 3347 return -EINVAL; 3348 } 3349 if (map->inner_map_meta && 3350 !check_map_prealloc(map->inner_map_meta)) { 3351 verbose("perf_event programs can only use preallocated inner hash map\n"); 3352 return -EINVAL; 3353 } 3354 } 3355 return 0; 3356 } 3357 3358 /* look for pseudo eBPF instructions that access map FDs and 3359 * replace them with actual map pointers 3360 */ 3361 static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env) 3362 { 3363 struct bpf_insn *insn = env->prog->insnsi; 3364 int insn_cnt = env->prog->len; 3365 int i, j, err; 3366 3367 err = bpf_prog_calc_tag(env->prog); 3368 if (err) 3369 return err; 3370 3371 for (i = 0; i < insn_cnt; i++, insn++) { 3372 if (BPF_CLASS(insn->code) == BPF_LDX && 3373 (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) { 3374 verbose("BPF_LDX uses reserved fields\n"); 3375 return -EINVAL; 3376 } 3377 3378 if (BPF_CLASS(insn->code) == BPF_STX && 3379 ((BPF_MODE(insn->code) != BPF_MEM && 3380 BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) { 3381 verbose("BPF_STX uses reserved fields\n"); 3382 return -EINVAL; 3383 } 3384 3385 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { 3386 struct bpf_map *map; 3387 struct fd f; 3388 3389 if (i == insn_cnt - 1 || insn[1].code != 0 || 3390 insn[1].dst_reg != 0 || insn[1].src_reg != 0 || 3391 insn[1].off != 0) { 3392 verbose("invalid bpf_ld_imm64 insn\n"); 3393 return -EINVAL; 3394 } 3395 3396 if (insn->src_reg == 0) 3397 /* valid generic load 64-bit imm */ 3398 goto next_insn; 3399 3400 if (insn->src_reg != BPF_PSEUDO_MAP_FD) { 3401 verbose("unrecognized bpf_ld_imm64 insn\n"); 3402 return -EINVAL; 3403 } 3404 3405 f = fdget(insn->imm); 3406 map = __bpf_map_get(f); 3407 if (IS_ERR(map)) { 3408 verbose("fd %d is not pointing to valid bpf_map\n", 3409 insn->imm); 3410 return PTR_ERR(map); 3411 } 3412 3413 err = check_map_prog_compatibility(map, env->prog); 3414 if (err) { 3415 fdput(f); 3416 return err; 3417 } 3418 3419 /* store map pointer inside BPF_LD_IMM64 instruction */ 3420 insn[0].imm = (u32) (unsigned long) map; 3421 insn[1].imm = ((u64) (unsigned long) map) >> 32; 3422 3423 /* check whether we recorded this map already */ 3424 for (j = 0; j < env->used_map_cnt; j++) 3425 if (env->used_maps[j] == map) { 3426 fdput(f); 3427 goto next_insn; 3428 } 3429 3430 if (env->used_map_cnt >= MAX_USED_MAPS) { 3431 fdput(f); 3432 return -E2BIG; 3433 } 3434 3435 /* hold the map. If the program is rejected by verifier, 3436 * the map will be released by release_maps() or it 3437 * will be used by the valid program until it's unloaded 3438 * and all maps are released in free_bpf_prog_info() 3439 */ 3440 map = bpf_map_inc(map, false); 3441 if (IS_ERR(map)) { 3442 fdput(f); 3443 return PTR_ERR(map); 3444 } 3445 env->used_maps[env->used_map_cnt++] = map; 3446 3447 fdput(f); 3448 next_insn: 3449 insn++; 3450 i++; 3451 } 3452 } 3453 3454 /* now all pseudo BPF_LD_IMM64 instructions load valid 3455 * 'struct bpf_map *' into a register instead of user map_fd. 3456 * These pointers will be used later by verifier to validate map access. 3457 */ 3458 return 0; 3459 } 3460 3461 /* drop refcnt of maps used by the rejected program */ 3462 static void release_maps(struct bpf_verifier_env *env) 3463 { 3464 int i; 3465 3466 for (i = 0; i < env->used_map_cnt; i++) 3467 bpf_map_put(env->used_maps[i]); 3468 } 3469 3470 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ 3471 static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env) 3472 { 3473 struct bpf_insn *insn = env->prog->insnsi; 3474 int insn_cnt = env->prog->len; 3475 int i; 3476 3477 for (i = 0; i < insn_cnt; i++, insn++) 3478 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) 3479 insn->src_reg = 0; 3480 } 3481 3482 /* single env->prog->insni[off] instruction was replaced with the range 3483 * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying 3484 * [0, off) and [off, end) to new locations, so the patched range stays zero 3485 */ 3486 static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len, 3487 u32 off, u32 cnt) 3488 { 3489 struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data; 3490 3491 if (cnt == 1) 3492 return 0; 3493 new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len); 3494 if (!new_data) 3495 return -ENOMEM; 3496 memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off); 3497 memcpy(new_data + off + cnt - 1, old_data + off, 3498 sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1)); 3499 env->insn_aux_data = new_data; 3500 vfree(old_data); 3501 return 0; 3502 } 3503 3504 static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, 3505 const struct bpf_insn *patch, u32 len) 3506 { 3507 struct bpf_prog *new_prog; 3508 3509 new_prog = bpf_patch_insn_single(env->prog, off, patch, len); 3510 if (!new_prog) 3511 return NULL; 3512 if (adjust_insn_aux_data(env, new_prog->len, off, len)) 3513 return NULL; 3514 return new_prog; 3515 } 3516 3517 /* convert load instructions that access fields of 'struct __sk_buff' 3518 * into sequence of instructions that access fields of 'struct sk_buff' 3519 */ 3520 static int convert_ctx_accesses(struct bpf_verifier_env *env) 3521 { 3522 const struct bpf_verifier_ops *ops = env->prog->aux->ops; 3523 int i, cnt, size, ctx_field_size, delta = 0; 3524 const int insn_cnt = env->prog->len; 3525 struct bpf_insn insn_buf[16], *insn; 3526 struct bpf_prog *new_prog; 3527 enum bpf_access_type type; 3528 bool is_narrower_load; 3529 u32 target_size; 3530 3531 if (ops->gen_prologue) { 3532 cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, 3533 env->prog); 3534 if (cnt >= ARRAY_SIZE(insn_buf)) { 3535 verbose("bpf verifier is misconfigured\n"); 3536 return -EINVAL; 3537 } else if (cnt) { 3538 new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt); 3539 if (!new_prog) 3540 return -ENOMEM; 3541 3542 env->prog = new_prog; 3543 delta += cnt - 1; 3544 } 3545 } 3546 3547 if (!ops->convert_ctx_access) 3548 return 0; 3549 3550 insn = env->prog->insnsi + delta; 3551 3552 for (i = 0; i < insn_cnt; i++, insn++) { 3553 if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || 3554 insn->code == (BPF_LDX | BPF_MEM | BPF_H) || 3555 insn->code == (BPF_LDX | BPF_MEM | BPF_W) || 3556 insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) 3557 type = BPF_READ; 3558 else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || 3559 insn->code == (BPF_STX | BPF_MEM | BPF_H) || 3560 insn->code == (BPF_STX | BPF_MEM | BPF_W) || 3561 insn->code == (BPF_STX | BPF_MEM | BPF_DW)) 3562 type = BPF_WRITE; 3563 else 3564 continue; 3565 3566 if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX) 3567 continue; 3568 3569 ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size; 3570 size = BPF_LDST_BYTES(insn); 3571 3572 /* If the read access is a narrower load of the field, 3573 * convert to a 4/8-byte load, to minimum program type specific 3574 * convert_ctx_access changes. If conversion is successful, 3575 * we will apply proper mask to the result. 3576 */ 3577 is_narrower_load = size < ctx_field_size; 3578 if (is_narrower_load) { 3579 u32 off = insn->off; 3580 u8 size_code; 3581 3582 if (type == BPF_WRITE) { 3583 verbose("bpf verifier narrow ctx access misconfigured\n"); 3584 return -EINVAL; 3585 } 3586 3587 size_code = BPF_H; 3588 if (ctx_field_size == 4) 3589 size_code = BPF_W; 3590 else if (ctx_field_size == 8) 3591 size_code = BPF_DW; 3592 3593 insn->off = off & ~(ctx_field_size - 1); 3594 insn->code = BPF_LDX | BPF_MEM | size_code; 3595 } 3596 3597 target_size = 0; 3598 cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog, 3599 &target_size); 3600 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || 3601 (ctx_field_size && !target_size)) { 3602 verbose("bpf verifier is misconfigured\n"); 3603 return -EINVAL; 3604 } 3605 3606 if (is_narrower_load && size < target_size) { 3607 if (ctx_field_size <= 4) 3608 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, 3609 (1 << size * 8) - 1); 3610 else 3611 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, 3612 (1 << size * 8) - 1); 3613 } 3614 3615 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); 3616 if (!new_prog) 3617 return -ENOMEM; 3618 3619 delta += cnt - 1; 3620 3621 /* keep walking new program and skip insns we just inserted */ 3622 env->prog = new_prog; 3623 insn = new_prog->insnsi + i + delta; 3624 } 3625 3626 return 0; 3627 } 3628 3629 /* fixup insn->imm field of bpf_call instructions 3630 * and inline eligible helpers as explicit sequence of BPF instructions 3631 * 3632 * this function is called after eBPF program passed verification 3633 */ 3634 static int fixup_bpf_calls(struct bpf_verifier_env *env) 3635 { 3636 struct bpf_prog *prog = env->prog; 3637 struct bpf_insn *insn = prog->insnsi; 3638 const struct bpf_func_proto *fn; 3639 const int insn_cnt = prog->len; 3640 struct bpf_insn insn_buf[16]; 3641 struct bpf_prog *new_prog; 3642 struct bpf_map *map_ptr; 3643 int i, cnt, delta = 0; 3644 3645 for (i = 0; i < insn_cnt; i++, insn++) { 3646 if (insn->code != (BPF_JMP | BPF_CALL)) 3647 continue; 3648 3649 if (insn->imm == BPF_FUNC_get_route_realm) 3650 prog->dst_needed = 1; 3651 if (insn->imm == BPF_FUNC_get_prandom_u32) 3652 bpf_user_rnd_init_once(); 3653 if (insn->imm == BPF_FUNC_tail_call) { 3654 /* If we tail call into other programs, we 3655 * cannot make any assumptions since they can 3656 * be replaced dynamically during runtime in 3657 * the program array. 3658 */ 3659 prog->cb_access = 1; 3660 env->prog->aux->stack_depth = MAX_BPF_STACK; 3661 3662 /* mark bpf_tail_call as different opcode to avoid 3663 * conditional branch in the interpeter for every normal 3664 * call and to prevent accidental JITing by JIT compiler 3665 * that doesn't support bpf_tail_call yet 3666 */ 3667 insn->imm = 0; 3668 insn->code = BPF_JMP | BPF_TAIL_CALL; 3669 continue; 3670 } 3671 3672 if (ebpf_jit_enabled() && insn->imm == BPF_FUNC_map_lookup_elem) { 3673 map_ptr = env->insn_aux_data[i + delta].map_ptr; 3674 if (map_ptr == BPF_MAP_PTR_POISON || 3675 !map_ptr->ops->map_gen_lookup) 3676 goto patch_call_imm; 3677 3678 cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf); 3679 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) { 3680 verbose("bpf verifier is misconfigured\n"); 3681 return -EINVAL; 3682 } 3683 3684 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 3685 cnt); 3686 if (!new_prog) 3687 return -ENOMEM; 3688 3689 delta += cnt - 1; 3690 3691 /* keep walking new program and skip insns we just inserted */ 3692 env->prog = prog = new_prog; 3693 insn = new_prog->insnsi + i + delta; 3694 continue; 3695 } 3696 3697 patch_call_imm: 3698 fn = prog->aux->ops->get_func_proto(insn->imm); 3699 /* all functions that have prototype and verifier allowed 3700 * programs to call them, must be real in-kernel functions 3701 */ 3702 if (!fn->func) { 3703 verbose("kernel subsystem misconfigured func %s#%d\n", 3704 func_id_name(insn->imm), insn->imm); 3705 return -EFAULT; 3706 } 3707 insn->imm = fn->func - __bpf_call_base; 3708 } 3709 3710 return 0; 3711 } 3712 3713 static void free_states(struct bpf_verifier_env *env) 3714 { 3715 struct bpf_verifier_state_list *sl, *sln; 3716 int i; 3717 3718 if (!env->explored_states) 3719 return; 3720 3721 for (i = 0; i < env->prog->len; i++) { 3722 sl = env->explored_states[i]; 3723 3724 if (sl) 3725 while (sl != STATE_LIST_MARK) { 3726 sln = sl->next; 3727 kfree(sl); 3728 sl = sln; 3729 } 3730 } 3731 3732 kfree(env->explored_states); 3733 } 3734 3735 int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) 3736 { 3737 char __user *log_ubuf = NULL; 3738 struct bpf_verifier_env *env; 3739 int ret = -EINVAL; 3740 3741 /* 'struct bpf_verifier_env' can be global, but since it's not small, 3742 * allocate/free it every time bpf_check() is called 3743 */ 3744 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3745 if (!env) 3746 return -ENOMEM; 3747 3748 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3749 (*prog)->len); 3750 ret = -ENOMEM; 3751 if (!env->insn_aux_data) 3752 goto err_free_env; 3753 env->prog = *prog; 3754 3755 /* grab the mutex to protect few globals used by verifier */ 3756 mutex_lock(&bpf_verifier_lock); 3757 3758 if (attr->log_level || attr->log_buf || attr->log_size) { 3759 /* user requested verbose verifier output 3760 * and supplied buffer to store the verification trace 3761 */ 3762 log_level = attr->log_level; 3763 log_ubuf = (char __user *) (unsigned long) attr->log_buf; 3764 log_size = attr->log_size; 3765 log_len = 0; 3766 3767 ret = -EINVAL; 3768 /* log_* values have to be sane */ 3769 if (log_size < 128 || log_size > UINT_MAX >> 8 || 3770 log_level == 0 || log_ubuf == NULL) 3771 goto err_unlock; 3772 3773 ret = -ENOMEM; 3774 log_buf = vmalloc(log_size); 3775 if (!log_buf) 3776 goto err_unlock; 3777 } else { 3778 log_level = 0; 3779 } 3780 3781 env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); 3782 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) 3783 env->strict_alignment = true; 3784 3785 ret = replace_map_fd_with_map_ptr(env); 3786 if (ret < 0) 3787 goto skip_full_check; 3788 3789 env->explored_states = kcalloc(env->prog->len, 3790 sizeof(struct bpf_verifier_state_list *), 3791 GFP_USER); 3792 ret = -ENOMEM; 3793 if (!env->explored_states) 3794 goto skip_full_check; 3795 3796 ret = check_cfg(env); 3797 if (ret < 0) 3798 goto skip_full_check; 3799 3800 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3801 3802 ret = do_check(env); 3803 3804 skip_full_check: 3805 while (pop_stack(env, NULL) >= 0); 3806 free_states(env); 3807 3808 if (ret == 0) 3809 /* program is valid, convert *(u32*)(ctx + off) accesses */ 3810 ret = convert_ctx_accesses(env); 3811 3812 if (ret == 0) 3813 ret = fixup_bpf_calls(env); 3814 3815 if (log_level && log_len >= log_size - 1) { 3816 BUG_ON(log_len >= log_size); 3817 /* verifier log exceeded user supplied buffer */ 3818 ret = -ENOSPC; 3819 /* fall through to return what was recorded */ 3820 } 3821 3822 /* copy verifier log back to user space including trailing zero */ 3823 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { 3824 ret = -EFAULT; 3825 goto free_log_buf; 3826 } 3827 3828 if (ret == 0 && env->used_map_cnt) { 3829 /* if program passed verifier, update used_maps in bpf_prog_info */ 3830 env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, 3831 sizeof(env->used_maps[0]), 3832 GFP_KERNEL); 3833 3834 if (!env->prog->aux->used_maps) { 3835 ret = -ENOMEM; 3836 goto free_log_buf; 3837 } 3838 3839 memcpy(env->prog->aux->used_maps, env->used_maps, 3840 sizeof(env->used_maps[0]) * env->used_map_cnt); 3841 env->prog->aux->used_map_cnt = env->used_map_cnt; 3842 3843 /* program is valid. Convert pseudo bpf_ld_imm64 into generic 3844 * bpf_ld_imm64 instructions 3845 */ 3846 convert_pseudo_ld_imm64(env); 3847 } 3848 3849 free_log_buf: 3850 if (log_level) 3851 vfree(log_buf); 3852 if (!env->prog->aux->used_maps) 3853 /* if we didn't copy map pointers into bpf_prog_info, release 3854 * them now. Otherwise free_bpf_prog_info() will release them. 3855 */ 3856 release_maps(env); 3857 *prog = env->prog; 3858 err_unlock: 3859 mutex_unlock(&bpf_verifier_lock); 3860 vfree(env->insn_aux_data); 3861 err_free_env: 3862 kfree(env); 3863 return ret; 3864 } 3865 3866 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, 3867 void *priv) 3868 { 3869 struct bpf_verifier_env *env; 3870 int ret; 3871 3872 env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL); 3873 if (!env) 3874 return -ENOMEM; 3875 3876 env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * 3877 prog->len); 3878 ret = -ENOMEM; 3879 if (!env->insn_aux_data) 3880 goto err_free_env; 3881 env->prog = prog; 3882 env->analyzer_ops = ops; 3883 env->analyzer_priv = priv; 3884 3885 /* grab the mutex to protect few globals used by verifier */ 3886 mutex_lock(&bpf_verifier_lock); 3887 3888 log_level = 0; 3889 3890 env->strict_alignment = false; 3891 if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) 3892 env->strict_alignment = true; 3893 3894 env->explored_states = kcalloc(env->prog->len, 3895 sizeof(struct bpf_verifier_state_list *), 3896 GFP_KERNEL); 3897 ret = -ENOMEM; 3898 if (!env->explored_states) 3899 goto skip_full_check; 3900 3901 ret = check_cfg(env); 3902 if (ret < 0) 3903 goto skip_full_check; 3904 3905 env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); 3906 3907 ret = do_check(env); 3908 3909 skip_full_check: 3910 while (pop_stack(env, NULL) >= 0); 3911 free_states(env); 3912 3913 mutex_unlock(&bpf_verifier_lock); 3914 vfree(env->insn_aux_data); 3915 err_free_env: 3916 kfree(env); 3917 return ret; 3918 } 3919 EXPORT_SYMBOL_GPL(bpf_analyzer); 3920