1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 2 * 3 * This program is free software; you can redistribute it and/or 4 * modify it under the terms of version 2 of the GNU General Public 5 * License as published by the Free Software Foundation. 6 * 7 * This program is distributed in the hope that it will be useful, but 8 * WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 10 * General Public License for more details. 11 */ 12 #include <linux/kernel.h> 13 #include <linux/types.h> 14 #include <linux/slab.h> 15 #include <linux/bpf.h> 16 #include <linux/filter.h> 17 #include <net/netlink.h> 18 #include <linux/file.h> 19 #include <linux/vmalloc.h> 20 21 /* bpf_check() is a static code analyzer that walks eBPF program 22 * instruction by instruction and updates register/stack state. 23 * All paths of conditional branches are analyzed until 'bpf_exit' insn. 24 * 25 * The first pass is depth-first-search to check that the program is a DAG. 26 * It rejects the following programs: 27 * - larger than BPF_MAXINSNS insns 28 * - if loop is present (detected via back-edge) 29 * - unreachable insns exist (shouldn't be a forest. program = one function) 30 * - out of bounds or malformed jumps 31 * The second pass is all possible path descent from the 1st insn. 32 * Since it's analyzing all pathes through the program, the length of the 33 * analysis is limited to 32k insn, which may be hit even if total number of 34 * insn is less then 4K, but there are too many branches that change stack/regs. 35 * Number of 'branches to be analyzed' is limited to 1k 36 * 37 * On entry to each instruction, each register has a type, and the instruction 38 * changes the types of the registers depending on instruction semantics. 39 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is 40 * copied to R1. 41 * 42 * All registers are 64-bit. 43 * R0 - return register 44 * R1-R5 argument passing registers 45 * R6-R9 callee saved registers 46 * R10 - frame pointer read-only 47 * 48 * At the start of BPF program the register R1 contains a pointer to bpf_context 49 * and has type PTR_TO_CTX. 50 * 51 * Verifier tracks arithmetic operations on pointers in case: 52 * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), 53 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20), 54 * 1st insn copies R10 (which has FRAME_PTR) type into R1 55 * and 2nd arithmetic instruction is pattern matched to recognize 56 * that it wants to construct a pointer to some element within stack. 57 * So after 2nd insn, the register R1 has type PTR_TO_STACK 58 * (and -20 constant is saved for further stack bounds checking). 59 * Meaning that this reg is a pointer to stack plus known immediate constant. 60 * 61 * Most of the time the registers have UNKNOWN_VALUE type, which 62 * means the register has some value, but it's not a valid pointer. 63 * (like pointer plus pointer becomes UNKNOWN_VALUE type) 64 * 65 * When verifier sees load or store instructions the type of base register 66 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer 67 * types recognized by check_mem_access() function. 68 * 69 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value' 70 * and the range of [ptr, ptr + map's value_size) is accessible. 71 * 72 * registers used to pass values to function calls are checked against 73 * function argument constraints. 74 * 75 * ARG_PTR_TO_MAP_KEY is one of such argument constraints. 76 * It means that the register type passed to this function must be 77 * PTR_TO_STACK and it will be used inside the function as 78 * 'pointer to map element key' 79 * 80 * For example the argument constraints for bpf_map_lookup_elem(): 81 * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 82 * .arg1_type = ARG_CONST_MAP_PTR, 83 * .arg2_type = ARG_PTR_TO_MAP_KEY, 84 * 85 * ret_type says that this function returns 'pointer to map elem value or null' 86 * function expects 1st argument to be a const pointer to 'struct bpf_map' and 87 * 2nd argument should be a pointer to stack, which will be used inside 88 * the helper function as a pointer to map element key. 89 * 90 * On the kernel side the helper function looks like: 91 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 92 * { 93 * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 94 * void *key = (void *) (unsigned long) r2; 95 * void *value; 96 * 97 * here kernel can access 'key' and 'map' pointers safely, knowing that 98 * [key, key + map->key_size) bytes are valid and were initialized on 99 * the stack of eBPF program. 100 * } 101 * 102 * Corresponding eBPF program may look like: 103 * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR 104 * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK 105 * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP 106 * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), 107 * here verifier looks at prototype of map_lookup_elem() and sees: 108 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok, 109 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes 110 * 111 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far, 112 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits 113 * and were initialized prior to this call. 114 * If it's ok, then verifier allows this BPF_CALL insn and looks at 115 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets 116 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function 117 * returns ether pointer to map value or NULL. 118 * 119 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off' 120 * insn, the register holding that pointer in the true branch changes state to 121 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false 122 * branch. See check_cond_jmp_op(). 123 * 124 * After the call R0 is set to return type of the function and registers R1-R5 125 * are set to NOT_INIT to indicate that they are no longer readable. 126 */ 127 128 /* types of values stored in eBPF registers */ 129 enum bpf_reg_type { 130 NOT_INIT = 0, /* nothing was written into register */ 131 UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */ 132 PTR_TO_CTX, /* reg points to bpf_context */ 133 CONST_PTR_TO_MAP, /* reg points to struct bpf_map */ 134 PTR_TO_MAP_VALUE, /* reg points to map element value */ 135 PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */ 136 FRAME_PTR, /* reg == frame_pointer */ 137 PTR_TO_STACK, /* reg == frame_pointer + imm */ 138 CONST_IMM, /* constant integer value */ 139 }; 140 141 struct reg_state { 142 enum bpf_reg_type type; 143 union { 144 /* valid when type == CONST_IMM | PTR_TO_STACK */ 145 int imm; 146 147 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | 148 * PTR_TO_MAP_VALUE_OR_NULL 149 */ 150 struct bpf_map *map_ptr; 151 }; 152 }; 153 154 enum bpf_stack_slot_type { 155 STACK_INVALID, /* nothing was stored in this stack slot */ 156 STACK_SPILL, /* register spilled into stack */ 157 STACK_MISC /* BPF program wrote some data into this slot */ 158 }; 159 160 #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ 161 162 /* state of the program: 163 * type of all registers and stack info 164 */ 165 struct verifier_state { 166 struct reg_state regs[MAX_BPF_REG]; 167 u8 stack_slot_type[MAX_BPF_STACK]; 168 struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; 169 }; 170 171 /* linked list of verifier states used to prune search */ 172 struct verifier_state_list { 173 struct verifier_state state; 174 struct verifier_state_list *next; 175 }; 176 177 /* verifier_state + insn_idx are pushed to stack when branch is encountered */ 178 struct verifier_stack_elem { 179 /* verifer state is 'st' 180 * before processing instruction 'insn_idx' 181 * and after processing instruction 'prev_insn_idx' 182 */ 183 struct verifier_state st; 184 int insn_idx; 185 int prev_insn_idx; 186 struct verifier_stack_elem *next; 187 }; 188 189 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ 190 191 /* single container for all structs 192 * one verifier_env per bpf_check() call 193 */ 194 struct verifier_env { 195 struct bpf_prog *prog; /* eBPF program being verified */ 196 struct verifier_stack_elem *head; /* stack of verifier states to be processed */ 197 int stack_size; /* number of states to be processed */ 198 struct verifier_state cur_state; /* current verifier state */ 199 struct verifier_state_list **explored_states; /* search pruning optimization */ 200 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ 201 u32 used_map_cnt; /* number of used maps */ 202 }; 203 204 /* verbose verifier prints what it's seeing 205 * bpf_check() is called under lock, so no race to access these global vars 206 */ 207 static u32 log_level, log_size, log_len; 208 static char *log_buf; 209 210 static DEFINE_MUTEX(bpf_verifier_lock); 211 212 /* log_level controls verbosity level of eBPF verifier. 213 * verbose() is used to dump the verification trace to the log, so the user 214 * can figure out what's wrong with the program 215 */ 216 static void verbose(const char *fmt, ...) 217 { 218 va_list args; 219 220 if (log_level == 0 || log_len >= log_size - 1) 221 return; 222 223 va_start(args, fmt); 224 log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args); 225 va_end(args); 226 } 227 228 /* string representation of 'enum bpf_reg_type' */ 229 static const char * const reg_type_str[] = { 230 [NOT_INIT] = "?", 231 [UNKNOWN_VALUE] = "inv", 232 [PTR_TO_CTX] = "ctx", 233 [CONST_PTR_TO_MAP] = "map_ptr", 234 [PTR_TO_MAP_VALUE] = "map_value", 235 [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null", 236 [FRAME_PTR] = "fp", 237 [PTR_TO_STACK] = "fp", 238 [CONST_IMM] = "imm", 239 }; 240 241 static void print_verifier_state(struct verifier_env *env) 242 { 243 enum bpf_reg_type t; 244 int i; 245 246 for (i = 0; i < MAX_BPF_REG; i++) { 247 t = env->cur_state.regs[i].type; 248 if (t == NOT_INIT) 249 continue; 250 verbose(" R%d=%s", i, reg_type_str[t]); 251 if (t == CONST_IMM || t == PTR_TO_STACK) 252 verbose("%d", env->cur_state.regs[i].imm); 253 else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE || 254 t == PTR_TO_MAP_VALUE_OR_NULL) 255 verbose("(ks=%d,vs=%d)", 256 env->cur_state.regs[i].map_ptr->key_size, 257 env->cur_state.regs[i].map_ptr->value_size); 258 } 259 for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) { 260 if (env->cur_state.stack_slot_type[i] == STACK_SPILL) 261 verbose(" fp%d=%s", -MAX_BPF_STACK + i, 262 reg_type_str[env->cur_state.spilled_regs[i / BPF_REG_SIZE].type]); 263 } 264 verbose("\n"); 265 } 266 267 static const char *const bpf_class_string[] = { 268 [BPF_LD] = "ld", 269 [BPF_LDX] = "ldx", 270 [BPF_ST] = "st", 271 [BPF_STX] = "stx", 272 [BPF_ALU] = "alu", 273 [BPF_JMP] = "jmp", 274 [BPF_RET] = "BUG", 275 [BPF_ALU64] = "alu64", 276 }; 277 278 static const char *const bpf_alu_string[] = { 279 [BPF_ADD >> 4] = "+=", 280 [BPF_SUB >> 4] = "-=", 281 [BPF_MUL >> 4] = "*=", 282 [BPF_DIV >> 4] = "/=", 283 [BPF_OR >> 4] = "|=", 284 [BPF_AND >> 4] = "&=", 285 [BPF_LSH >> 4] = "<<=", 286 [BPF_RSH >> 4] = ">>=", 287 [BPF_NEG >> 4] = "neg", 288 [BPF_MOD >> 4] = "%=", 289 [BPF_XOR >> 4] = "^=", 290 [BPF_MOV >> 4] = "=", 291 [BPF_ARSH >> 4] = "s>>=", 292 [BPF_END >> 4] = "endian", 293 }; 294 295 static const char *const bpf_ldst_string[] = { 296 [BPF_W >> 3] = "u32", 297 [BPF_H >> 3] = "u16", 298 [BPF_B >> 3] = "u8", 299 [BPF_DW >> 3] = "u64", 300 }; 301 302 static const char *const bpf_jmp_string[] = { 303 [BPF_JA >> 4] = "jmp", 304 [BPF_JEQ >> 4] = "==", 305 [BPF_JGT >> 4] = ">", 306 [BPF_JGE >> 4] = ">=", 307 [BPF_JSET >> 4] = "&", 308 [BPF_JNE >> 4] = "!=", 309 [BPF_JSGT >> 4] = "s>", 310 [BPF_JSGE >> 4] = "s>=", 311 [BPF_CALL >> 4] = "call", 312 [BPF_EXIT >> 4] = "exit", 313 }; 314 315 static void print_bpf_insn(struct bpf_insn *insn) 316 { 317 u8 class = BPF_CLASS(insn->code); 318 319 if (class == BPF_ALU || class == BPF_ALU64) { 320 if (BPF_SRC(insn->code) == BPF_X) 321 verbose("(%02x) %sr%d %s %sr%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->src_reg); 327 else 328 verbose("(%02x) %sr%d %s %s%d\n", 329 insn->code, class == BPF_ALU ? "(u32) " : "", 330 insn->dst_reg, 331 bpf_alu_string[BPF_OP(insn->code) >> 4], 332 class == BPF_ALU ? "(u32) " : "", 333 insn->imm); 334 } else if (class == BPF_STX) { 335 if (BPF_MODE(insn->code) == BPF_MEM) 336 verbose("(%02x) *(%s *)(r%d %+d) = r%d\n", 337 insn->code, 338 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 339 insn->dst_reg, 340 insn->off, insn->src_reg); 341 else if (BPF_MODE(insn->code) == BPF_XADD) 342 verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n", 343 insn->code, 344 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 345 insn->dst_reg, insn->off, 346 insn->src_reg); 347 else 348 verbose("BUG_%02x\n", insn->code); 349 } else if (class == BPF_ST) { 350 if (BPF_MODE(insn->code) != BPF_MEM) { 351 verbose("BUG_st_%02x\n", insn->code); 352 return; 353 } 354 verbose("(%02x) *(%s *)(r%d %+d) = %d\n", 355 insn->code, 356 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 357 insn->dst_reg, 358 insn->off, insn->imm); 359 } else if (class == BPF_LDX) { 360 if (BPF_MODE(insn->code) != BPF_MEM) { 361 verbose("BUG_ldx_%02x\n", insn->code); 362 return; 363 } 364 verbose("(%02x) r%d = *(%s *)(r%d %+d)\n", 365 insn->code, insn->dst_reg, 366 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 367 insn->src_reg, insn->off); 368 } else if (class == BPF_LD) { 369 if (BPF_MODE(insn->code) == BPF_ABS) { 370 verbose("(%02x) r0 = *(%s *)skb[%d]\n", 371 insn->code, 372 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 373 insn->imm); 374 } else if (BPF_MODE(insn->code) == BPF_IND) { 375 verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n", 376 insn->code, 377 bpf_ldst_string[BPF_SIZE(insn->code) >> 3], 378 insn->src_reg, insn->imm); 379 } else if (BPF_MODE(insn->code) == BPF_IMM) { 380 verbose("(%02x) r%d = 0x%x\n", 381 insn->code, insn->dst_reg, insn->imm); 382 } else { 383 verbose("BUG_ld_%02x\n", insn->code); 384 return; 385 } 386 } else if (class == BPF_JMP) { 387 u8 opcode = BPF_OP(insn->code); 388 389 if (opcode == BPF_CALL) { 390 verbose("(%02x) call %d\n", insn->code, insn->imm); 391 } else if (insn->code == (BPF_JMP | BPF_JA)) { 392 verbose("(%02x) goto pc%+d\n", 393 insn->code, insn->off); 394 } else if (insn->code == (BPF_JMP | BPF_EXIT)) { 395 verbose("(%02x) exit\n", insn->code); 396 } else if (BPF_SRC(insn->code) == BPF_X) { 397 verbose("(%02x) if r%d %s r%d goto pc%+d\n", 398 insn->code, insn->dst_reg, 399 bpf_jmp_string[BPF_OP(insn->code) >> 4], 400 insn->src_reg, insn->off); 401 } else { 402 verbose("(%02x) if r%d %s 0x%x goto pc%+d\n", 403 insn->code, insn->dst_reg, 404 bpf_jmp_string[BPF_OP(insn->code) >> 4], 405 insn->imm, insn->off); 406 } 407 } else { 408 verbose("(%02x) %s\n", insn->code, bpf_class_string[class]); 409 } 410 } 411 412 static int pop_stack(struct verifier_env *env, int *prev_insn_idx) 413 { 414 struct verifier_stack_elem *elem; 415 int insn_idx; 416 417 if (env->head == NULL) 418 return -1; 419 420 memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state)); 421 insn_idx = env->head->insn_idx; 422 if (prev_insn_idx) 423 *prev_insn_idx = env->head->prev_insn_idx; 424 elem = env->head->next; 425 kfree(env->head); 426 env->head = elem; 427 env->stack_size--; 428 return insn_idx; 429 } 430 431 static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx, 432 int prev_insn_idx) 433 { 434 struct verifier_stack_elem *elem; 435 436 elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL); 437 if (!elem) 438 goto err; 439 440 memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state)); 441 elem->insn_idx = insn_idx; 442 elem->prev_insn_idx = prev_insn_idx; 443 elem->next = env->head; 444 env->head = elem; 445 env->stack_size++; 446 if (env->stack_size > 1024) { 447 verbose("BPF program is too complex\n"); 448 goto err; 449 } 450 return &elem->st; 451 err: 452 /* pop all elements and return */ 453 while (pop_stack(env, NULL) >= 0); 454 return NULL; 455 } 456 457 #define CALLER_SAVED_REGS 6 458 static const int caller_saved[CALLER_SAVED_REGS] = { 459 BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5 460 }; 461 462 static void init_reg_state(struct reg_state *regs) 463 { 464 int i; 465 466 for (i = 0; i < MAX_BPF_REG; i++) { 467 regs[i].type = NOT_INIT; 468 regs[i].imm = 0; 469 regs[i].map_ptr = NULL; 470 } 471 472 /* frame pointer */ 473 regs[BPF_REG_FP].type = FRAME_PTR; 474 475 /* 1st arg to a function */ 476 regs[BPF_REG_1].type = PTR_TO_CTX; 477 } 478 479 static void mark_reg_unknown_value(struct reg_state *regs, u32 regno) 480 { 481 BUG_ON(regno >= MAX_BPF_REG); 482 regs[regno].type = UNKNOWN_VALUE; 483 regs[regno].imm = 0; 484 regs[regno].map_ptr = NULL; 485 } 486 487 enum reg_arg_type { 488 SRC_OP, /* register is used as source operand */ 489 DST_OP, /* register is used as destination operand */ 490 DST_OP_NO_MARK /* same as above, check only, don't mark */ 491 }; 492 493 static int check_reg_arg(struct reg_state *regs, u32 regno, 494 enum reg_arg_type t) 495 { 496 if (regno >= MAX_BPF_REG) { 497 verbose("R%d is invalid\n", regno); 498 return -EINVAL; 499 } 500 501 if (t == SRC_OP) { 502 /* check whether register used as source operand can be read */ 503 if (regs[regno].type == NOT_INIT) { 504 verbose("R%d !read_ok\n", regno); 505 return -EACCES; 506 } 507 } else { 508 /* check whether register used as dest operand can be written to */ 509 if (regno == BPF_REG_FP) { 510 verbose("frame pointer is read only\n"); 511 return -EACCES; 512 } 513 if (t == DST_OP) 514 mark_reg_unknown_value(regs, regno); 515 } 516 return 0; 517 } 518 519 static int bpf_size_to_bytes(int bpf_size) 520 { 521 if (bpf_size == BPF_W) 522 return 4; 523 else if (bpf_size == BPF_H) 524 return 2; 525 else if (bpf_size == BPF_B) 526 return 1; 527 else if (bpf_size == BPF_DW) 528 return 8; 529 else 530 return -EINVAL; 531 } 532 533 /* check_stack_read/write functions track spill/fill of registers, 534 * stack boundary and alignment are checked in check_mem_access() 535 */ 536 static int check_stack_write(struct verifier_state *state, int off, int size, 537 int value_regno) 538 { 539 int i; 540 /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0, 541 * so it's aligned access and [off, off + size) are within stack limits 542 */ 543 544 if (value_regno >= 0 && 545 (state->regs[value_regno].type == PTR_TO_MAP_VALUE || 546 state->regs[value_regno].type == PTR_TO_STACK || 547 state->regs[value_regno].type == PTR_TO_CTX)) { 548 549 /* register containing pointer is being spilled into stack */ 550 if (size != BPF_REG_SIZE) { 551 verbose("invalid size of register spill\n"); 552 return -EACCES; 553 } 554 555 /* save register state */ 556 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 557 state->regs[value_regno]; 558 559 for (i = 0; i < BPF_REG_SIZE; i++) 560 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL; 561 } else { 562 /* regular write of data into stack */ 563 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] = 564 (struct reg_state) {}; 565 566 for (i = 0; i < size; i++) 567 state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC; 568 } 569 return 0; 570 } 571 572 static int check_stack_read(struct verifier_state *state, int off, int size, 573 int value_regno) 574 { 575 u8 *slot_type; 576 int i; 577 578 slot_type = &state->stack_slot_type[MAX_BPF_STACK + off]; 579 580 if (slot_type[0] == STACK_SPILL) { 581 if (size != BPF_REG_SIZE) { 582 verbose("invalid size of register spill\n"); 583 return -EACCES; 584 } 585 for (i = 1; i < BPF_REG_SIZE; i++) { 586 if (slot_type[i] != STACK_SPILL) { 587 verbose("corrupted spill memory\n"); 588 return -EACCES; 589 } 590 } 591 592 if (value_regno >= 0) 593 /* restore register state from stack */ 594 state->regs[value_regno] = 595 state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE]; 596 return 0; 597 } else { 598 for (i = 0; i < size; i++) { 599 if (slot_type[i] != STACK_MISC) { 600 verbose("invalid read from stack off %d+%d size %d\n", 601 off, i, size); 602 return -EACCES; 603 } 604 } 605 if (value_regno >= 0) 606 /* have read misc data from the stack */ 607 mark_reg_unknown_value(state->regs, value_regno); 608 return 0; 609 } 610 } 611 612 /* check read/write into map element returned by bpf_map_lookup_elem() */ 613 static int check_map_access(struct verifier_env *env, u32 regno, int off, 614 int size) 615 { 616 struct bpf_map *map = env->cur_state.regs[regno].map_ptr; 617 618 if (off < 0 || off + size > map->value_size) { 619 verbose("invalid access to map value, value_size=%d off=%d size=%d\n", 620 map->value_size, off, size); 621 return -EACCES; 622 } 623 return 0; 624 } 625 626 /* check access to 'struct bpf_context' fields */ 627 static int check_ctx_access(struct verifier_env *env, int off, int size, 628 enum bpf_access_type t) 629 { 630 if (env->prog->aux->ops->is_valid_access && 631 env->prog->aux->ops->is_valid_access(off, size, t)) 632 return 0; 633 634 verbose("invalid bpf_context access off=%d size=%d\n", off, size); 635 return -EACCES; 636 } 637 638 /* check whether memory at (regno + off) is accessible for t = (read | write) 639 * if t==write, value_regno is a register which value is stored into memory 640 * if t==read, value_regno is a register which will receive the value from memory 641 * if t==write && value_regno==-1, some unknown value is stored into memory 642 * if t==read && value_regno==-1, don't care what we read from memory 643 */ 644 static int check_mem_access(struct verifier_env *env, u32 regno, int off, 645 int bpf_size, enum bpf_access_type t, 646 int value_regno) 647 { 648 struct verifier_state *state = &env->cur_state; 649 int size, err = 0; 650 651 size = bpf_size_to_bytes(bpf_size); 652 if (size < 0) 653 return size; 654 655 if (off % size != 0) { 656 verbose("misaligned access off %d size %d\n", off, size); 657 return -EACCES; 658 } 659 660 if (state->regs[regno].type == PTR_TO_MAP_VALUE) { 661 err = check_map_access(env, regno, off, size); 662 if (!err && t == BPF_READ && value_regno >= 0) 663 mark_reg_unknown_value(state->regs, value_regno); 664 665 } else if (state->regs[regno].type == PTR_TO_CTX) { 666 err = check_ctx_access(env, off, size, t); 667 if (!err && t == BPF_READ && value_regno >= 0) 668 mark_reg_unknown_value(state->regs, value_regno); 669 670 } else if (state->regs[regno].type == FRAME_PTR) { 671 if (off >= 0 || off < -MAX_BPF_STACK) { 672 verbose("invalid stack off=%d size=%d\n", off, size); 673 return -EACCES; 674 } 675 if (t == BPF_WRITE) 676 err = check_stack_write(state, off, size, value_regno); 677 else 678 err = check_stack_read(state, off, size, value_regno); 679 } else { 680 verbose("R%d invalid mem access '%s'\n", 681 regno, reg_type_str[state->regs[regno].type]); 682 return -EACCES; 683 } 684 return err; 685 } 686 687 static int check_xadd(struct verifier_env *env, struct bpf_insn *insn) 688 { 689 struct reg_state *regs = env->cur_state.regs; 690 int err; 691 692 if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || 693 insn->imm != 0) { 694 verbose("BPF_XADD uses reserved fields\n"); 695 return -EINVAL; 696 } 697 698 /* check src1 operand */ 699 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 700 if (err) 701 return err; 702 703 /* check src2 operand */ 704 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 705 if (err) 706 return err; 707 708 /* check whether atomic_add can read the memory */ 709 err = check_mem_access(env, insn->dst_reg, insn->off, 710 BPF_SIZE(insn->code), BPF_READ, -1); 711 if (err) 712 return err; 713 714 /* check whether atomic_add can write into the same memory */ 715 return check_mem_access(env, insn->dst_reg, insn->off, 716 BPF_SIZE(insn->code), BPF_WRITE, -1); 717 } 718 719 /* when register 'regno' is passed into function that will read 'access_size' 720 * bytes from that pointer, make sure that it's within stack boundary 721 * and all elements of stack are initialized 722 */ 723 static int check_stack_boundary(struct verifier_env *env, 724 int regno, int access_size) 725 { 726 struct verifier_state *state = &env->cur_state; 727 struct reg_state *regs = state->regs; 728 int off, i; 729 730 if (regs[regno].type != PTR_TO_STACK) 731 return -EACCES; 732 733 off = regs[regno].imm; 734 if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 || 735 access_size <= 0) { 736 verbose("invalid stack type R%d off=%d access_size=%d\n", 737 regno, off, access_size); 738 return -EACCES; 739 } 740 741 for (i = 0; i < access_size; i++) { 742 if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) { 743 verbose("invalid indirect read from stack off %d+%d size %d\n", 744 off, i, access_size); 745 return -EACCES; 746 } 747 } 748 return 0; 749 } 750 751 static int check_func_arg(struct verifier_env *env, u32 regno, 752 enum bpf_arg_type arg_type, struct bpf_map **mapp) 753 { 754 struct reg_state *reg = env->cur_state.regs + regno; 755 enum bpf_reg_type expected_type; 756 int err = 0; 757 758 if (arg_type == ARG_ANYTHING) 759 return 0; 760 761 if (reg->type == NOT_INIT) { 762 verbose("R%d !read_ok\n", regno); 763 return -EACCES; 764 } 765 766 if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY || 767 arg_type == ARG_PTR_TO_MAP_VALUE) { 768 expected_type = PTR_TO_STACK; 769 } else if (arg_type == ARG_CONST_STACK_SIZE) { 770 expected_type = CONST_IMM; 771 } else if (arg_type == ARG_CONST_MAP_PTR) { 772 expected_type = CONST_PTR_TO_MAP; 773 } else { 774 verbose("unsupported arg_type %d\n", arg_type); 775 return -EFAULT; 776 } 777 778 if (reg->type != expected_type) { 779 verbose("R%d type=%s expected=%s\n", regno, 780 reg_type_str[reg->type], reg_type_str[expected_type]); 781 return -EACCES; 782 } 783 784 if (arg_type == ARG_CONST_MAP_PTR) { 785 /* bpf_map_xxx(map_ptr) call: remember that map_ptr */ 786 *mapp = reg->map_ptr; 787 788 } else if (arg_type == ARG_PTR_TO_MAP_KEY) { 789 /* bpf_map_xxx(..., map_ptr, ..., key) call: 790 * check that [key, key + map->key_size) are within 791 * stack limits and initialized 792 */ 793 if (!*mapp) { 794 /* in function declaration map_ptr must come before 795 * map_key, so that it's verified and known before 796 * we have to check map_key here. Otherwise it means 797 * that kernel subsystem misconfigured verifier 798 */ 799 verbose("invalid map_ptr to access map->key\n"); 800 return -EACCES; 801 } 802 err = check_stack_boundary(env, regno, (*mapp)->key_size); 803 804 } else if (arg_type == ARG_PTR_TO_MAP_VALUE) { 805 /* bpf_map_xxx(..., map_ptr, ..., value) call: 806 * check [value, value + map->value_size) validity 807 */ 808 if (!*mapp) { 809 /* kernel subsystem misconfigured verifier */ 810 verbose("invalid map_ptr to access map->value\n"); 811 return -EACCES; 812 } 813 err = check_stack_boundary(env, regno, (*mapp)->value_size); 814 815 } else if (arg_type == ARG_CONST_STACK_SIZE) { 816 /* bpf_xxx(..., buf, len) call will access 'len' bytes 817 * from stack pointer 'buf'. Check it 818 * note: regno == len, regno - 1 == buf 819 */ 820 if (regno == 0) { 821 /* kernel subsystem misconfigured verifier */ 822 verbose("ARG_CONST_STACK_SIZE cannot be first argument\n"); 823 return -EACCES; 824 } 825 err = check_stack_boundary(env, regno - 1, reg->imm); 826 } 827 828 return err; 829 } 830 831 static int check_call(struct verifier_env *env, int func_id) 832 { 833 struct verifier_state *state = &env->cur_state; 834 const struct bpf_func_proto *fn = NULL; 835 struct reg_state *regs = state->regs; 836 struct bpf_map *map = NULL; 837 struct reg_state *reg; 838 int i, err; 839 840 /* find function prototype */ 841 if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) { 842 verbose("invalid func %d\n", func_id); 843 return -EINVAL; 844 } 845 846 if (env->prog->aux->ops->get_func_proto) 847 fn = env->prog->aux->ops->get_func_proto(func_id); 848 849 if (!fn) { 850 verbose("unknown func %d\n", func_id); 851 return -EINVAL; 852 } 853 854 /* eBPF programs must be GPL compatible to use GPL-ed functions */ 855 if (!env->prog->aux->is_gpl_compatible && fn->gpl_only) { 856 verbose("cannot call GPL only function from proprietary program\n"); 857 return -EINVAL; 858 } 859 860 /* check args */ 861 err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &map); 862 if (err) 863 return err; 864 err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &map); 865 if (err) 866 return err; 867 err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &map); 868 if (err) 869 return err; 870 err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &map); 871 if (err) 872 return err; 873 err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &map); 874 if (err) 875 return err; 876 877 /* reset caller saved regs */ 878 for (i = 0; i < CALLER_SAVED_REGS; i++) { 879 reg = regs + caller_saved[i]; 880 reg->type = NOT_INIT; 881 reg->imm = 0; 882 } 883 884 /* update return register */ 885 if (fn->ret_type == RET_INTEGER) { 886 regs[BPF_REG_0].type = UNKNOWN_VALUE; 887 } else if (fn->ret_type == RET_VOID) { 888 regs[BPF_REG_0].type = NOT_INIT; 889 } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { 890 regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; 891 /* remember map_ptr, so that check_map_access() 892 * can check 'value_size' boundary of memory access 893 * to map element returned from bpf_map_lookup_elem() 894 */ 895 if (map == NULL) { 896 verbose("kernel subsystem misconfigured verifier\n"); 897 return -EINVAL; 898 } 899 regs[BPF_REG_0].map_ptr = map; 900 } else { 901 verbose("unknown return type %d of func %d\n", 902 fn->ret_type, func_id); 903 return -EINVAL; 904 } 905 return 0; 906 } 907 908 /* check validity of 32-bit and 64-bit arithmetic operations */ 909 static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn) 910 { 911 u8 opcode = BPF_OP(insn->code); 912 int err; 913 914 if (opcode == BPF_END || opcode == BPF_NEG) { 915 if (opcode == BPF_NEG) { 916 if (BPF_SRC(insn->code) != 0 || 917 insn->src_reg != BPF_REG_0 || 918 insn->off != 0 || insn->imm != 0) { 919 verbose("BPF_NEG uses reserved fields\n"); 920 return -EINVAL; 921 } 922 } else { 923 if (insn->src_reg != BPF_REG_0 || insn->off != 0 || 924 (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) { 925 verbose("BPF_END uses reserved fields\n"); 926 return -EINVAL; 927 } 928 } 929 930 /* check src operand */ 931 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 932 if (err) 933 return err; 934 935 /* check dest operand */ 936 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 937 if (err) 938 return err; 939 940 } else if (opcode == BPF_MOV) { 941 942 if (BPF_SRC(insn->code) == BPF_X) { 943 if (insn->imm != 0 || insn->off != 0) { 944 verbose("BPF_MOV uses reserved fields\n"); 945 return -EINVAL; 946 } 947 948 /* check src operand */ 949 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 950 if (err) 951 return err; 952 } else { 953 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 954 verbose("BPF_MOV uses reserved fields\n"); 955 return -EINVAL; 956 } 957 } 958 959 /* check dest operand */ 960 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 961 if (err) 962 return err; 963 964 if (BPF_SRC(insn->code) == BPF_X) { 965 if (BPF_CLASS(insn->code) == BPF_ALU64) { 966 /* case: R1 = R2 967 * copy register state to dest reg 968 */ 969 regs[insn->dst_reg] = regs[insn->src_reg]; 970 } else { 971 regs[insn->dst_reg].type = UNKNOWN_VALUE; 972 regs[insn->dst_reg].map_ptr = NULL; 973 } 974 } else { 975 /* case: R = imm 976 * remember the value we stored into this reg 977 */ 978 regs[insn->dst_reg].type = CONST_IMM; 979 regs[insn->dst_reg].imm = insn->imm; 980 } 981 982 } else if (opcode > BPF_END) { 983 verbose("invalid BPF_ALU opcode %x\n", opcode); 984 return -EINVAL; 985 986 } else { /* all other ALU ops: and, sub, xor, add, ... */ 987 988 bool stack_relative = false; 989 990 if (BPF_SRC(insn->code) == BPF_X) { 991 if (insn->imm != 0 || insn->off != 0) { 992 verbose("BPF_ALU uses reserved fields\n"); 993 return -EINVAL; 994 } 995 /* check src1 operand */ 996 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 997 if (err) 998 return err; 999 } else { 1000 if (insn->src_reg != BPF_REG_0 || insn->off != 0) { 1001 verbose("BPF_ALU uses reserved fields\n"); 1002 return -EINVAL; 1003 } 1004 } 1005 1006 /* check src2 operand */ 1007 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1008 if (err) 1009 return err; 1010 1011 if ((opcode == BPF_MOD || opcode == BPF_DIV) && 1012 BPF_SRC(insn->code) == BPF_K && insn->imm == 0) { 1013 verbose("div by zero\n"); 1014 return -EINVAL; 1015 } 1016 1017 /* pattern match 'bpf_add Rx, imm' instruction */ 1018 if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 && 1019 regs[insn->dst_reg].type == FRAME_PTR && 1020 BPF_SRC(insn->code) == BPF_K) 1021 stack_relative = true; 1022 1023 /* check dest operand */ 1024 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1025 if (err) 1026 return err; 1027 1028 if (stack_relative) { 1029 regs[insn->dst_reg].type = PTR_TO_STACK; 1030 regs[insn->dst_reg].imm = insn->imm; 1031 } 1032 } 1033 1034 return 0; 1035 } 1036 1037 static int check_cond_jmp_op(struct verifier_env *env, 1038 struct bpf_insn *insn, int *insn_idx) 1039 { 1040 struct reg_state *regs = env->cur_state.regs; 1041 struct verifier_state *other_branch; 1042 u8 opcode = BPF_OP(insn->code); 1043 int err; 1044 1045 if (opcode > BPF_EXIT) { 1046 verbose("invalid BPF_JMP opcode %x\n", opcode); 1047 return -EINVAL; 1048 } 1049 1050 if (BPF_SRC(insn->code) == BPF_X) { 1051 if (insn->imm != 0) { 1052 verbose("BPF_JMP uses reserved fields\n"); 1053 return -EINVAL; 1054 } 1055 1056 /* check src1 operand */ 1057 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1058 if (err) 1059 return err; 1060 } else { 1061 if (insn->src_reg != BPF_REG_0) { 1062 verbose("BPF_JMP uses reserved fields\n"); 1063 return -EINVAL; 1064 } 1065 } 1066 1067 /* check src2 operand */ 1068 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1069 if (err) 1070 return err; 1071 1072 /* detect if R == 0 where R was initialized to zero earlier */ 1073 if (BPF_SRC(insn->code) == BPF_K && 1074 (opcode == BPF_JEQ || opcode == BPF_JNE) && 1075 regs[insn->dst_reg].type == CONST_IMM && 1076 regs[insn->dst_reg].imm == insn->imm) { 1077 if (opcode == BPF_JEQ) { 1078 /* if (imm == imm) goto pc+off; 1079 * only follow the goto, ignore fall-through 1080 */ 1081 *insn_idx += insn->off; 1082 return 0; 1083 } else { 1084 /* if (imm != imm) goto pc+off; 1085 * only follow fall-through branch, since 1086 * that's where the program will go 1087 */ 1088 return 0; 1089 } 1090 } 1091 1092 other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx); 1093 if (!other_branch) 1094 return -EFAULT; 1095 1096 /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */ 1097 if (BPF_SRC(insn->code) == BPF_K && 1098 insn->imm == 0 && (opcode == BPF_JEQ || 1099 opcode == BPF_JNE) && 1100 regs[insn->dst_reg].type == PTR_TO_MAP_VALUE_OR_NULL) { 1101 if (opcode == BPF_JEQ) { 1102 /* next fallthrough insn can access memory via 1103 * this register 1104 */ 1105 regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; 1106 /* branch targer cannot access it, since reg == 0 */ 1107 other_branch->regs[insn->dst_reg].type = CONST_IMM; 1108 other_branch->regs[insn->dst_reg].imm = 0; 1109 } else { 1110 other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE; 1111 regs[insn->dst_reg].type = CONST_IMM; 1112 regs[insn->dst_reg].imm = 0; 1113 } 1114 } else if (BPF_SRC(insn->code) == BPF_K && 1115 (opcode == BPF_JEQ || opcode == BPF_JNE)) { 1116 1117 if (opcode == BPF_JEQ) { 1118 /* detect if (R == imm) goto 1119 * and in the target state recognize that R = imm 1120 */ 1121 other_branch->regs[insn->dst_reg].type = CONST_IMM; 1122 other_branch->regs[insn->dst_reg].imm = insn->imm; 1123 } else { 1124 /* detect if (R != imm) goto 1125 * and in the fall-through state recognize that R = imm 1126 */ 1127 regs[insn->dst_reg].type = CONST_IMM; 1128 regs[insn->dst_reg].imm = insn->imm; 1129 } 1130 } 1131 if (log_level) 1132 print_verifier_state(env); 1133 return 0; 1134 } 1135 1136 /* return the map pointer stored inside BPF_LD_IMM64 instruction */ 1137 static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn) 1138 { 1139 u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32; 1140 1141 return (struct bpf_map *) (unsigned long) imm64; 1142 } 1143 1144 /* verify BPF_LD_IMM64 instruction */ 1145 static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn) 1146 { 1147 struct reg_state *regs = env->cur_state.regs; 1148 int err; 1149 1150 if (BPF_SIZE(insn->code) != BPF_DW) { 1151 verbose("invalid BPF_LD_IMM insn\n"); 1152 return -EINVAL; 1153 } 1154 if (insn->off != 0) { 1155 verbose("BPF_LD_IMM64 uses reserved fields\n"); 1156 return -EINVAL; 1157 } 1158 1159 err = check_reg_arg(regs, insn->dst_reg, DST_OP); 1160 if (err) 1161 return err; 1162 1163 if (insn->src_reg == 0) 1164 /* generic move 64-bit immediate into a register */ 1165 return 0; 1166 1167 /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ 1168 BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); 1169 1170 regs[insn->dst_reg].type = CONST_PTR_TO_MAP; 1171 regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn); 1172 return 0; 1173 } 1174 1175 /* verify safety of LD_ABS|LD_IND instructions: 1176 * - they can only appear in the programs where ctx == skb 1177 * - since they are wrappers of function calls, they scratch R1-R5 registers, 1178 * preserve R6-R9, and store return value into R0 1179 * 1180 * Implicit input: 1181 * ctx == skb == R6 == CTX 1182 * 1183 * Explicit input: 1184 * SRC == any register 1185 * IMM == 32-bit immediate 1186 * 1187 * Output: 1188 * R0 - 8/16/32-bit skb data converted to cpu endianness 1189 */ 1190 static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn) 1191 { 1192 struct reg_state *regs = env->cur_state.regs; 1193 u8 mode = BPF_MODE(insn->code); 1194 struct reg_state *reg; 1195 int i, err; 1196 1197 if (env->prog->aux->prog_type != BPF_PROG_TYPE_SOCKET_FILTER) { 1198 verbose("BPF_LD_ABS|IND instructions are only allowed in socket filters\n"); 1199 return -EINVAL; 1200 } 1201 1202 if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || 1203 (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) { 1204 verbose("BPF_LD_ABS uses reserved fields\n"); 1205 return -EINVAL; 1206 } 1207 1208 /* check whether implicit source operand (register R6) is readable */ 1209 err = check_reg_arg(regs, BPF_REG_6, SRC_OP); 1210 if (err) 1211 return err; 1212 1213 if (regs[BPF_REG_6].type != PTR_TO_CTX) { 1214 verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n"); 1215 return -EINVAL; 1216 } 1217 1218 if (mode == BPF_IND) { 1219 /* check explicit source operand */ 1220 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1221 if (err) 1222 return err; 1223 } 1224 1225 /* reset caller saved regs to unreadable */ 1226 for (i = 0; i < CALLER_SAVED_REGS; i++) { 1227 reg = regs + caller_saved[i]; 1228 reg->type = NOT_INIT; 1229 reg->imm = 0; 1230 } 1231 1232 /* mark destination R0 register as readable, since it contains 1233 * the value fetched from the packet 1234 */ 1235 regs[BPF_REG_0].type = UNKNOWN_VALUE; 1236 return 0; 1237 } 1238 1239 /* non-recursive DFS pseudo code 1240 * 1 procedure DFS-iterative(G,v): 1241 * 2 label v as discovered 1242 * 3 let S be a stack 1243 * 4 S.push(v) 1244 * 5 while S is not empty 1245 * 6 t <- S.pop() 1246 * 7 if t is what we're looking for: 1247 * 8 return t 1248 * 9 for all edges e in G.adjacentEdges(t) do 1249 * 10 if edge e is already labelled 1250 * 11 continue with the next edge 1251 * 12 w <- G.adjacentVertex(t,e) 1252 * 13 if vertex w is not discovered and not explored 1253 * 14 label e as tree-edge 1254 * 15 label w as discovered 1255 * 16 S.push(w) 1256 * 17 continue at 5 1257 * 18 else if vertex w is discovered 1258 * 19 label e as back-edge 1259 * 20 else 1260 * 21 // vertex w is explored 1261 * 22 label e as forward- or cross-edge 1262 * 23 label t as explored 1263 * 24 S.pop() 1264 * 1265 * convention: 1266 * 0x10 - discovered 1267 * 0x11 - discovered and fall-through edge labelled 1268 * 0x12 - discovered and fall-through and branch edges labelled 1269 * 0x20 - explored 1270 */ 1271 1272 enum { 1273 DISCOVERED = 0x10, 1274 EXPLORED = 0x20, 1275 FALLTHROUGH = 1, 1276 BRANCH = 2, 1277 }; 1278 1279 #define STATE_LIST_MARK ((struct verifier_state_list *) -1L) 1280 1281 static int *insn_stack; /* stack of insns to process */ 1282 static int cur_stack; /* current stack index */ 1283 static int *insn_state; 1284 1285 /* t, w, e - match pseudo-code above: 1286 * t - index of current instruction 1287 * w - next instruction 1288 * e - edge 1289 */ 1290 static int push_insn(int t, int w, int e, struct verifier_env *env) 1291 { 1292 if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) 1293 return 0; 1294 1295 if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) 1296 return 0; 1297 1298 if (w < 0 || w >= env->prog->len) { 1299 verbose("jump out of range from insn %d to %d\n", t, w); 1300 return -EINVAL; 1301 } 1302 1303 if (e == BRANCH) 1304 /* mark branch target for state pruning */ 1305 env->explored_states[w] = STATE_LIST_MARK; 1306 1307 if (insn_state[w] == 0) { 1308 /* tree-edge */ 1309 insn_state[t] = DISCOVERED | e; 1310 insn_state[w] = DISCOVERED; 1311 if (cur_stack >= env->prog->len) 1312 return -E2BIG; 1313 insn_stack[cur_stack++] = w; 1314 return 1; 1315 } else if ((insn_state[w] & 0xF0) == DISCOVERED) { 1316 verbose("back-edge from insn %d to %d\n", t, w); 1317 return -EINVAL; 1318 } else if (insn_state[w] == EXPLORED) { 1319 /* forward- or cross-edge */ 1320 insn_state[t] = DISCOVERED | e; 1321 } else { 1322 verbose("insn state internal bug\n"); 1323 return -EFAULT; 1324 } 1325 return 0; 1326 } 1327 1328 /* non-recursive depth-first-search to detect loops in BPF program 1329 * loop == back-edge in directed graph 1330 */ 1331 static int check_cfg(struct verifier_env *env) 1332 { 1333 struct bpf_insn *insns = env->prog->insnsi; 1334 int insn_cnt = env->prog->len; 1335 int ret = 0; 1336 int i, t; 1337 1338 insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 1339 if (!insn_state) 1340 return -ENOMEM; 1341 1342 insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL); 1343 if (!insn_stack) { 1344 kfree(insn_state); 1345 return -ENOMEM; 1346 } 1347 1348 insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */ 1349 insn_stack[0] = 0; /* 0 is the first instruction */ 1350 cur_stack = 1; 1351 1352 peek_stack: 1353 if (cur_stack == 0) 1354 goto check_state; 1355 t = insn_stack[cur_stack - 1]; 1356 1357 if (BPF_CLASS(insns[t].code) == BPF_JMP) { 1358 u8 opcode = BPF_OP(insns[t].code); 1359 1360 if (opcode == BPF_EXIT) { 1361 goto mark_explored; 1362 } else if (opcode == BPF_CALL) { 1363 ret = push_insn(t, t + 1, FALLTHROUGH, env); 1364 if (ret == 1) 1365 goto peek_stack; 1366 else if (ret < 0) 1367 goto err_free; 1368 } else if (opcode == BPF_JA) { 1369 if (BPF_SRC(insns[t].code) != BPF_K) { 1370 ret = -EINVAL; 1371 goto err_free; 1372 } 1373 /* unconditional jump with single edge */ 1374 ret = push_insn(t, t + insns[t].off + 1, 1375 FALLTHROUGH, env); 1376 if (ret == 1) 1377 goto peek_stack; 1378 else if (ret < 0) 1379 goto err_free; 1380 /* tell verifier to check for equivalent states 1381 * after every call and jump 1382 */ 1383 env->explored_states[t + 1] = STATE_LIST_MARK; 1384 } else { 1385 /* conditional jump with two edges */ 1386 ret = push_insn(t, t + 1, FALLTHROUGH, env); 1387 if (ret == 1) 1388 goto peek_stack; 1389 else if (ret < 0) 1390 goto err_free; 1391 1392 ret = push_insn(t, t + insns[t].off + 1, BRANCH, env); 1393 if (ret == 1) 1394 goto peek_stack; 1395 else if (ret < 0) 1396 goto err_free; 1397 } 1398 } else { 1399 /* all other non-branch instructions with single 1400 * fall-through edge 1401 */ 1402 ret = push_insn(t, t + 1, FALLTHROUGH, env); 1403 if (ret == 1) 1404 goto peek_stack; 1405 else if (ret < 0) 1406 goto err_free; 1407 } 1408 1409 mark_explored: 1410 insn_state[t] = EXPLORED; 1411 if (cur_stack-- <= 0) { 1412 verbose("pop stack internal bug\n"); 1413 ret = -EFAULT; 1414 goto err_free; 1415 } 1416 goto peek_stack; 1417 1418 check_state: 1419 for (i = 0; i < insn_cnt; i++) { 1420 if (insn_state[i] != EXPLORED) { 1421 verbose("unreachable insn %d\n", i); 1422 ret = -EINVAL; 1423 goto err_free; 1424 } 1425 } 1426 ret = 0; /* cfg looks good */ 1427 1428 err_free: 1429 kfree(insn_state); 1430 kfree(insn_stack); 1431 return ret; 1432 } 1433 1434 /* compare two verifier states 1435 * 1436 * all states stored in state_list are known to be valid, since 1437 * verifier reached 'bpf_exit' instruction through them 1438 * 1439 * this function is called when verifier exploring different branches of 1440 * execution popped from the state stack. If it sees an old state that has 1441 * more strict register state and more strict stack state then this execution 1442 * branch doesn't need to be explored further, since verifier already 1443 * concluded that more strict state leads to valid finish. 1444 * 1445 * Therefore two states are equivalent if register state is more conservative 1446 * and explored stack state is more conservative than the current one. 1447 * Example: 1448 * explored current 1449 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC) 1450 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC) 1451 * 1452 * In other words if current stack state (one being explored) has more 1453 * valid slots than old one that already passed validation, it means 1454 * the verifier can stop exploring and conclude that current state is valid too 1455 * 1456 * Similarly with registers. If explored state has register type as invalid 1457 * whereas register type in current state is meaningful, it means that 1458 * the current state will reach 'bpf_exit' instruction safely 1459 */ 1460 static bool states_equal(struct verifier_state *old, struct verifier_state *cur) 1461 { 1462 int i; 1463 1464 for (i = 0; i < MAX_BPF_REG; i++) { 1465 if (memcmp(&old->regs[i], &cur->regs[i], 1466 sizeof(old->regs[0])) != 0) { 1467 if (old->regs[i].type == NOT_INIT || 1468 (old->regs[i].type == UNKNOWN_VALUE && 1469 cur->regs[i].type != NOT_INIT)) 1470 continue; 1471 return false; 1472 } 1473 } 1474 1475 for (i = 0; i < MAX_BPF_STACK; i++) { 1476 if (old->stack_slot_type[i] == STACK_INVALID) 1477 continue; 1478 if (old->stack_slot_type[i] != cur->stack_slot_type[i]) 1479 /* Ex: old explored (safe) state has STACK_SPILL in 1480 * this stack slot, but current has has STACK_MISC -> 1481 * this verifier states are not equivalent, 1482 * return false to continue verification of this path 1483 */ 1484 return false; 1485 if (i % BPF_REG_SIZE) 1486 continue; 1487 if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE], 1488 &cur->spilled_regs[i / BPF_REG_SIZE], 1489 sizeof(old->spilled_regs[0]))) 1490 /* when explored and current stack slot types are 1491 * the same, check that stored pointers types 1492 * are the same as well. 1493 * Ex: explored safe path could have stored 1494 * (struct reg_state) {.type = PTR_TO_STACK, .imm = -8} 1495 * but current path has stored: 1496 * (struct reg_state) {.type = PTR_TO_STACK, .imm = -16} 1497 * such verifier states are not equivalent. 1498 * return false to continue verification of this path 1499 */ 1500 return false; 1501 else 1502 continue; 1503 } 1504 return true; 1505 } 1506 1507 static int is_state_visited(struct verifier_env *env, int insn_idx) 1508 { 1509 struct verifier_state_list *new_sl; 1510 struct verifier_state_list *sl; 1511 1512 sl = env->explored_states[insn_idx]; 1513 if (!sl) 1514 /* this 'insn_idx' instruction wasn't marked, so we will not 1515 * be doing state search here 1516 */ 1517 return 0; 1518 1519 while (sl != STATE_LIST_MARK) { 1520 if (states_equal(&sl->state, &env->cur_state)) 1521 /* reached equivalent register/stack state, 1522 * prune the search 1523 */ 1524 return 1; 1525 sl = sl->next; 1526 } 1527 1528 /* there were no equivalent states, remember current one. 1529 * technically the current state is not proven to be safe yet, 1530 * but it will either reach bpf_exit (which means it's safe) or 1531 * it will be rejected. Since there are no loops, we won't be 1532 * seeing this 'insn_idx' instruction again on the way to bpf_exit 1533 */ 1534 new_sl = kmalloc(sizeof(struct verifier_state_list), GFP_USER); 1535 if (!new_sl) 1536 return -ENOMEM; 1537 1538 /* add new state to the head of linked list */ 1539 memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state)); 1540 new_sl->next = env->explored_states[insn_idx]; 1541 env->explored_states[insn_idx] = new_sl; 1542 return 0; 1543 } 1544 1545 static int do_check(struct verifier_env *env) 1546 { 1547 struct verifier_state *state = &env->cur_state; 1548 struct bpf_insn *insns = env->prog->insnsi; 1549 struct reg_state *regs = state->regs; 1550 int insn_cnt = env->prog->len; 1551 int insn_idx, prev_insn_idx = 0; 1552 int insn_processed = 0; 1553 bool do_print_state = false; 1554 1555 init_reg_state(regs); 1556 insn_idx = 0; 1557 for (;;) { 1558 struct bpf_insn *insn; 1559 u8 class; 1560 int err; 1561 1562 if (insn_idx >= insn_cnt) { 1563 verbose("invalid insn idx %d insn_cnt %d\n", 1564 insn_idx, insn_cnt); 1565 return -EFAULT; 1566 } 1567 1568 insn = &insns[insn_idx]; 1569 class = BPF_CLASS(insn->code); 1570 1571 if (++insn_processed > 32768) { 1572 verbose("BPF program is too large. Proccessed %d insn\n", 1573 insn_processed); 1574 return -E2BIG; 1575 } 1576 1577 err = is_state_visited(env, insn_idx); 1578 if (err < 0) 1579 return err; 1580 if (err == 1) { 1581 /* found equivalent state, can prune the search */ 1582 if (log_level) { 1583 if (do_print_state) 1584 verbose("\nfrom %d to %d: safe\n", 1585 prev_insn_idx, insn_idx); 1586 else 1587 verbose("%d: safe\n", insn_idx); 1588 } 1589 goto process_bpf_exit; 1590 } 1591 1592 if (log_level && do_print_state) { 1593 verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx); 1594 print_verifier_state(env); 1595 do_print_state = false; 1596 } 1597 1598 if (log_level) { 1599 verbose("%d: ", insn_idx); 1600 print_bpf_insn(insn); 1601 } 1602 1603 if (class == BPF_ALU || class == BPF_ALU64) { 1604 err = check_alu_op(regs, insn); 1605 if (err) 1606 return err; 1607 1608 } else if (class == BPF_LDX) { 1609 if (BPF_MODE(insn->code) != BPF_MEM || 1610 insn->imm != 0) { 1611 verbose("BPF_LDX uses reserved fields\n"); 1612 return -EINVAL; 1613 } 1614 /* check src operand */ 1615 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1616 if (err) 1617 return err; 1618 1619 err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK); 1620 if (err) 1621 return err; 1622 1623 /* check that memory (src_reg + off) is readable, 1624 * the state of dst_reg will be updated by this func 1625 */ 1626 err = check_mem_access(env, insn->src_reg, insn->off, 1627 BPF_SIZE(insn->code), BPF_READ, 1628 insn->dst_reg); 1629 if (err) 1630 return err; 1631 1632 } else if (class == BPF_STX) { 1633 if (BPF_MODE(insn->code) == BPF_XADD) { 1634 err = check_xadd(env, insn); 1635 if (err) 1636 return err; 1637 insn_idx++; 1638 continue; 1639 } 1640 1641 if (BPF_MODE(insn->code) != BPF_MEM || 1642 insn->imm != 0) { 1643 verbose("BPF_STX uses reserved fields\n"); 1644 return -EINVAL; 1645 } 1646 /* check src1 operand */ 1647 err = check_reg_arg(regs, insn->src_reg, SRC_OP); 1648 if (err) 1649 return err; 1650 /* check src2 operand */ 1651 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1652 if (err) 1653 return err; 1654 1655 /* check that memory (dst_reg + off) is writeable */ 1656 err = check_mem_access(env, insn->dst_reg, insn->off, 1657 BPF_SIZE(insn->code), BPF_WRITE, 1658 insn->src_reg); 1659 if (err) 1660 return err; 1661 1662 } else if (class == BPF_ST) { 1663 if (BPF_MODE(insn->code) != BPF_MEM || 1664 insn->src_reg != BPF_REG_0) { 1665 verbose("BPF_ST uses reserved fields\n"); 1666 return -EINVAL; 1667 } 1668 /* check src operand */ 1669 err = check_reg_arg(regs, insn->dst_reg, SRC_OP); 1670 if (err) 1671 return err; 1672 1673 /* check that memory (dst_reg + off) is writeable */ 1674 err = check_mem_access(env, insn->dst_reg, insn->off, 1675 BPF_SIZE(insn->code), BPF_WRITE, 1676 -1); 1677 if (err) 1678 return err; 1679 1680 } else if (class == BPF_JMP) { 1681 u8 opcode = BPF_OP(insn->code); 1682 1683 if (opcode == BPF_CALL) { 1684 if (BPF_SRC(insn->code) != BPF_K || 1685 insn->off != 0 || 1686 insn->src_reg != BPF_REG_0 || 1687 insn->dst_reg != BPF_REG_0) { 1688 verbose("BPF_CALL uses reserved fields\n"); 1689 return -EINVAL; 1690 } 1691 1692 err = check_call(env, insn->imm); 1693 if (err) 1694 return err; 1695 1696 } else if (opcode == BPF_JA) { 1697 if (BPF_SRC(insn->code) != BPF_K || 1698 insn->imm != 0 || 1699 insn->src_reg != BPF_REG_0 || 1700 insn->dst_reg != BPF_REG_0) { 1701 verbose("BPF_JA uses reserved fields\n"); 1702 return -EINVAL; 1703 } 1704 1705 insn_idx += insn->off + 1; 1706 continue; 1707 1708 } else if (opcode == BPF_EXIT) { 1709 if (BPF_SRC(insn->code) != BPF_K || 1710 insn->imm != 0 || 1711 insn->src_reg != BPF_REG_0 || 1712 insn->dst_reg != BPF_REG_0) { 1713 verbose("BPF_EXIT uses reserved fields\n"); 1714 return -EINVAL; 1715 } 1716 1717 /* eBPF calling convetion is such that R0 is used 1718 * to return the value from eBPF program. 1719 * Make sure that it's readable at this time 1720 * of bpf_exit, which means that program wrote 1721 * something into it earlier 1722 */ 1723 err = check_reg_arg(regs, BPF_REG_0, SRC_OP); 1724 if (err) 1725 return err; 1726 1727 process_bpf_exit: 1728 insn_idx = pop_stack(env, &prev_insn_idx); 1729 if (insn_idx < 0) { 1730 break; 1731 } else { 1732 do_print_state = true; 1733 continue; 1734 } 1735 } else { 1736 err = check_cond_jmp_op(env, insn, &insn_idx); 1737 if (err) 1738 return err; 1739 } 1740 } else if (class == BPF_LD) { 1741 u8 mode = BPF_MODE(insn->code); 1742 1743 if (mode == BPF_ABS || mode == BPF_IND) { 1744 err = check_ld_abs(env, insn); 1745 if (err) 1746 return err; 1747 1748 } else if (mode == BPF_IMM) { 1749 err = check_ld_imm(env, insn); 1750 if (err) 1751 return err; 1752 1753 insn_idx++; 1754 } else { 1755 verbose("invalid BPF_LD mode\n"); 1756 return -EINVAL; 1757 } 1758 } else { 1759 verbose("unknown insn class %d\n", class); 1760 return -EINVAL; 1761 } 1762 1763 insn_idx++; 1764 } 1765 1766 return 0; 1767 } 1768 1769 /* look for pseudo eBPF instructions that access map FDs and 1770 * replace them with actual map pointers 1771 */ 1772 static int replace_map_fd_with_map_ptr(struct verifier_env *env) 1773 { 1774 struct bpf_insn *insn = env->prog->insnsi; 1775 int insn_cnt = env->prog->len; 1776 int i, j; 1777 1778 for (i = 0; i < insn_cnt; i++, insn++) { 1779 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) { 1780 struct bpf_map *map; 1781 struct fd f; 1782 1783 if (i == insn_cnt - 1 || insn[1].code != 0 || 1784 insn[1].dst_reg != 0 || insn[1].src_reg != 0 || 1785 insn[1].off != 0) { 1786 verbose("invalid bpf_ld_imm64 insn\n"); 1787 return -EINVAL; 1788 } 1789 1790 if (insn->src_reg == 0) 1791 /* valid generic load 64-bit imm */ 1792 goto next_insn; 1793 1794 if (insn->src_reg != BPF_PSEUDO_MAP_FD) { 1795 verbose("unrecognized bpf_ld_imm64 insn\n"); 1796 return -EINVAL; 1797 } 1798 1799 f = fdget(insn->imm); 1800 1801 map = bpf_map_get(f); 1802 if (IS_ERR(map)) { 1803 verbose("fd %d is not pointing to valid bpf_map\n", 1804 insn->imm); 1805 fdput(f); 1806 return PTR_ERR(map); 1807 } 1808 1809 /* store map pointer inside BPF_LD_IMM64 instruction */ 1810 insn[0].imm = (u32) (unsigned long) map; 1811 insn[1].imm = ((u64) (unsigned long) map) >> 32; 1812 1813 /* check whether we recorded this map already */ 1814 for (j = 0; j < env->used_map_cnt; j++) 1815 if (env->used_maps[j] == map) { 1816 fdput(f); 1817 goto next_insn; 1818 } 1819 1820 if (env->used_map_cnt >= MAX_USED_MAPS) { 1821 fdput(f); 1822 return -E2BIG; 1823 } 1824 1825 /* remember this map */ 1826 env->used_maps[env->used_map_cnt++] = map; 1827 1828 /* hold the map. If the program is rejected by verifier, 1829 * the map will be released by release_maps() or it 1830 * will be used by the valid program until it's unloaded 1831 * and all maps are released in free_bpf_prog_info() 1832 */ 1833 atomic_inc(&map->refcnt); 1834 1835 fdput(f); 1836 next_insn: 1837 insn++; 1838 i++; 1839 } 1840 } 1841 1842 /* now all pseudo BPF_LD_IMM64 instructions load valid 1843 * 'struct bpf_map *' into a register instead of user map_fd. 1844 * These pointers will be used later by verifier to validate map access. 1845 */ 1846 return 0; 1847 } 1848 1849 /* drop refcnt of maps used by the rejected program */ 1850 static void release_maps(struct verifier_env *env) 1851 { 1852 int i; 1853 1854 for (i = 0; i < env->used_map_cnt; i++) 1855 bpf_map_put(env->used_maps[i]); 1856 } 1857 1858 /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */ 1859 static void convert_pseudo_ld_imm64(struct verifier_env *env) 1860 { 1861 struct bpf_insn *insn = env->prog->insnsi; 1862 int insn_cnt = env->prog->len; 1863 int i; 1864 1865 for (i = 0; i < insn_cnt; i++, insn++) 1866 if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) 1867 insn->src_reg = 0; 1868 } 1869 1870 static void free_states(struct verifier_env *env) 1871 { 1872 struct verifier_state_list *sl, *sln; 1873 int i; 1874 1875 if (!env->explored_states) 1876 return; 1877 1878 for (i = 0; i < env->prog->len; i++) { 1879 sl = env->explored_states[i]; 1880 1881 if (sl) 1882 while (sl != STATE_LIST_MARK) { 1883 sln = sl->next; 1884 kfree(sl); 1885 sl = sln; 1886 } 1887 } 1888 1889 kfree(env->explored_states); 1890 } 1891 1892 int bpf_check(struct bpf_prog *prog, union bpf_attr *attr) 1893 { 1894 char __user *log_ubuf = NULL; 1895 struct verifier_env *env; 1896 int ret = -EINVAL; 1897 1898 if (prog->len <= 0 || prog->len > BPF_MAXINSNS) 1899 return -E2BIG; 1900 1901 /* 'struct verifier_env' can be global, but since it's not small, 1902 * allocate/free it every time bpf_check() is called 1903 */ 1904 env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL); 1905 if (!env) 1906 return -ENOMEM; 1907 1908 env->prog = prog; 1909 1910 /* grab the mutex to protect few globals used by verifier */ 1911 mutex_lock(&bpf_verifier_lock); 1912 1913 if (attr->log_level || attr->log_buf || attr->log_size) { 1914 /* user requested verbose verifier output 1915 * and supplied buffer to store the verification trace 1916 */ 1917 log_level = attr->log_level; 1918 log_ubuf = (char __user *) (unsigned long) attr->log_buf; 1919 log_size = attr->log_size; 1920 log_len = 0; 1921 1922 ret = -EINVAL; 1923 /* log_* values have to be sane */ 1924 if (log_size < 128 || log_size > UINT_MAX >> 8 || 1925 log_level == 0 || log_ubuf == NULL) 1926 goto free_env; 1927 1928 ret = -ENOMEM; 1929 log_buf = vmalloc(log_size); 1930 if (!log_buf) 1931 goto free_env; 1932 } else { 1933 log_level = 0; 1934 } 1935 1936 ret = replace_map_fd_with_map_ptr(env); 1937 if (ret < 0) 1938 goto skip_full_check; 1939 1940 env->explored_states = kcalloc(prog->len, 1941 sizeof(struct verifier_state_list *), 1942 GFP_USER); 1943 ret = -ENOMEM; 1944 if (!env->explored_states) 1945 goto skip_full_check; 1946 1947 ret = check_cfg(env); 1948 if (ret < 0) 1949 goto skip_full_check; 1950 1951 ret = do_check(env); 1952 1953 skip_full_check: 1954 while (pop_stack(env, NULL) >= 0); 1955 free_states(env); 1956 1957 if (log_level && log_len >= log_size - 1) { 1958 BUG_ON(log_len >= log_size); 1959 /* verifier log exceeded user supplied buffer */ 1960 ret = -ENOSPC; 1961 /* fall through to return what was recorded */ 1962 } 1963 1964 /* copy verifier log back to user space including trailing zero */ 1965 if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) { 1966 ret = -EFAULT; 1967 goto free_log_buf; 1968 } 1969 1970 if (ret == 0 && env->used_map_cnt) { 1971 /* if program passed verifier, update used_maps in bpf_prog_info */ 1972 prog->aux->used_maps = kmalloc_array(env->used_map_cnt, 1973 sizeof(env->used_maps[0]), 1974 GFP_KERNEL); 1975 1976 if (!prog->aux->used_maps) { 1977 ret = -ENOMEM; 1978 goto free_log_buf; 1979 } 1980 1981 memcpy(prog->aux->used_maps, env->used_maps, 1982 sizeof(env->used_maps[0]) * env->used_map_cnt); 1983 prog->aux->used_map_cnt = env->used_map_cnt; 1984 1985 /* program is valid. Convert pseudo bpf_ld_imm64 into generic 1986 * bpf_ld_imm64 instructions 1987 */ 1988 convert_pseudo_ld_imm64(env); 1989 } 1990 1991 free_log_buf: 1992 if (log_level) 1993 vfree(log_buf); 1994 free_env: 1995 if (!prog->aux->used_maps) 1996 /* if we didn't copy map pointers into bpf_prog_info, release 1997 * them now. Otherwise free_bpf_prog_info() will release them. 1998 */ 1999 release_maps(env); 2000 kfree(env); 2001 mutex_unlock(&bpf_verifier_lock); 2002 return ret; 2003 } 2004