1 /* 2 * Linux Socket Filter - Kernel level socket filtering 3 * 4 * Based on the design of the Berkeley Packet Filter. The new 5 * internal format has been designed by PLUMgrid: 6 * 7 * Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com 8 * 9 * Authors: 10 * 11 * Jay Schulist <jschlst@samba.org> 12 * Alexei Starovoitov <ast@plumgrid.com> 13 * Daniel Borkmann <dborkman@redhat.com> 14 * 15 * This program is free software; you can redistribute it and/or 16 * modify it under the terms of the GNU General Public License 17 * as published by the Free Software Foundation; either version 18 * 2 of the License, or (at your option) any later version. 19 * 20 * Andi Kleen - Fix a few bad bugs and races. 21 * Kris Katterjohn - Added many additional checks in bpf_check_classic() 22 */ 23 24 #include <linux/filter.h> 25 #include <linux/skbuff.h> 26 #include <linux/vmalloc.h> 27 #include <linux/random.h> 28 #include <linux/moduleloader.h> 29 #include <linux/bpf.h> 30 #include <linux/frame.h> 31 32 #include <asm/unaligned.h> 33 34 /* Registers */ 35 #define BPF_R0 regs[BPF_REG_0] 36 #define BPF_R1 regs[BPF_REG_1] 37 #define BPF_R2 regs[BPF_REG_2] 38 #define BPF_R3 regs[BPF_REG_3] 39 #define BPF_R4 regs[BPF_REG_4] 40 #define BPF_R5 regs[BPF_REG_5] 41 #define BPF_R6 regs[BPF_REG_6] 42 #define BPF_R7 regs[BPF_REG_7] 43 #define BPF_R8 regs[BPF_REG_8] 44 #define BPF_R9 regs[BPF_REG_9] 45 #define BPF_R10 regs[BPF_REG_10] 46 47 /* Named registers */ 48 #define DST regs[insn->dst_reg] 49 #define SRC regs[insn->src_reg] 50 #define FP regs[BPF_REG_FP] 51 #define ARG1 regs[BPF_REG_ARG1] 52 #define CTX regs[BPF_REG_CTX] 53 #define IMM insn->imm 54 55 /* No hurry in this branch 56 * 57 * Exported for the bpf jit load helper. 58 */ 59 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size) 60 { 61 u8 *ptr = NULL; 62 63 if (k >= SKF_NET_OFF) 64 ptr = skb_network_header(skb) + k - SKF_NET_OFF; 65 else if (k >= SKF_LL_OFF) 66 ptr = skb_mac_header(skb) + k - SKF_LL_OFF; 67 68 if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb)) 69 return ptr; 70 71 return NULL; 72 } 73 74 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) 75 { 76 gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO | 77 gfp_extra_flags; 78 struct bpf_prog_aux *aux; 79 struct bpf_prog *fp; 80 81 size = round_up(size, PAGE_SIZE); 82 fp = __vmalloc(size, gfp_flags, PAGE_KERNEL); 83 if (fp == NULL) 84 return NULL; 85 86 kmemcheck_annotate_bitfield(fp, meta); 87 88 aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags); 89 if (aux == NULL) { 90 vfree(fp); 91 return NULL; 92 } 93 94 fp->pages = size / PAGE_SIZE; 95 fp->aux = aux; 96 fp->aux->prog = fp; 97 98 return fp; 99 } 100 EXPORT_SYMBOL_GPL(bpf_prog_alloc); 101 102 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, 103 gfp_t gfp_extra_flags) 104 { 105 gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO | 106 gfp_extra_flags; 107 struct bpf_prog *fp; 108 109 BUG_ON(fp_old == NULL); 110 111 size = round_up(size, PAGE_SIZE); 112 if (size <= fp_old->pages * PAGE_SIZE) 113 return fp_old; 114 115 fp = __vmalloc(size, gfp_flags, PAGE_KERNEL); 116 if (fp != NULL) { 117 kmemcheck_annotate_bitfield(fp, meta); 118 119 memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE); 120 fp->pages = size / PAGE_SIZE; 121 fp->aux->prog = fp; 122 123 /* We keep fp->aux from fp_old around in the new 124 * reallocated structure. 125 */ 126 fp_old->aux = NULL; 127 __bpf_prog_free(fp_old); 128 } 129 130 return fp; 131 } 132 133 void __bpf_prog_free(struct bpf_prog *fp) 134 { 135 kfree(fp->aux); 136 vfree(fp); 137 } 138 139 #define SHA_BPF_RAW_SIZE \ 140 round_up(MAX_BPF_SIZE + sizeof(__be64) + 1, SHA_MESSAGE_BYTES) 141 142 /* Called under verifier mutex. */ 143 void bpf_prog_calc_digest(struct bpf_prog *fp) 144 { 145 const u32 bits_offset = SHA_MESSAGE_BYTES - sizeof(__be64); 146 static u32 ws[SHA_WORKSPACE_WORDS]; 147 static u8 raw[SHA_BPF_RAW_SIZE]; 148 struct bpf_insn *dst = (void *)raw; 149 u32 i, bsize, psize, blocks; 150 bool was_ld_map; 151 u8 *todo = raw; 152 __be32 *result; 153 __be64 *bits; 154 155 sha_init(fp->digest); 156 memset(ws, 0, sizeof(ws)); 157 158 /* We need to take out the map fd for the digest calculation 159 * since they are unstable from user space side. 160 */ 161 for (i = 0, was_ld_map = false; i < fp->len; i++) { 162 dst[i] = fp->insnsi[i]; 163 if (!was_ld_map && 164 dst[i].code == (BPF_LD | BPF_IMM | BPF_DW) && 165 dst[i].src_reg == BPF_PSEUDO_MAP_FD) { 166 was_ld_map = true; 167 dst[i].imm = 0; 168 } else if (was_ld_map && 169 dst[i].code == 0 && 170 dst[i].dst_reg == 0 && 171 dst[i].src_reg == 0 && 172 dst[i].off == 0) { 173 was_ld_map = false; 174 dst[i].imm = 0; 175 } else { 176 was_ld_map = false; 177 } 178 } 179 180 psize = fp->len * sizeof(struct bpf_insn); 181 memset(&raw[psize], 0, sizeof(raw) - psize); 182 raw[psize++] = 0x80; 183 184 bsize = round_up(psize, SHA_MESSAGE_BYTES); 185 blocks = bsize / SHA_MESSAGE_BYTES; 186 if (bsize - psize >= sizeof(__be64)) { 187 bits = (__be64 *)(todo + bsize - sizeof(__be64)); 188 } else { 189 bits = (__be64 *)(todo + bsize + bits_offset); 190 blocks++; 191 } 192 *bits = cpu_to_be64((psize - 1) << 3); 193 194 while (blocks--) { 195 sha_transform(fp->digest, todo, ws); 196 todo += SHA_MESSAGE_BYTES; 197 } 198 199 result = (__force __be32 *)fp->digest; 200 for (i = 0; i < SHA_DIGEST_WORDS; i++) 201 result[i] = cpu_to_be32(fp->digest[i]); 202 } 203 204 static bool bpf_is_jmp_and_has_target(const struct bpf_insn *insn) 205 { 206 return BPF_CLASS(insn->code) == BPF_JMP && 207 /* Call and Exit are both special jumps with no 208 * target inside the BPF instruction image. 209 */ 210 BPF_OP(insn->code) != BPF_CALL && 211 BPF_OP(insn->code) != BPF_EXIT; 212 } 213 214 static void bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta) 215 { 216 struct bpf_insn *insn = prog->insnsi; 217 u32 i, insn_cnt = prog->len; 218 219 for (i = 0; i < insn_cnt; i++, insn++) { 220 if (!bpf_is_jmp_and_has_target(insn)) 221 continue; 222 223 /* Adjust offset of jmps if we cross boundaries. */ 224 if (i < pos && i + insn->off + 1 > pos) 225 insn->off += delta; 226 else if (i > pos + delta && i + insn->off + 1 <= pos + delta) 227 insn->off -= delta; 228 } 229 } 230 231 struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, 232 const struct bpf_insn *patch, u32 len) 233 { 234 u32 insn_adj_cnt, insn_rest, insn_delta = len - 1; 235 struct bpf_prog *prog_adj; 236 237 /* Since our patchlet doesn't expand the image, we're done. */ 238 if (insn_delta == 0) { 239 memcpy(prog->insnsi + off, patch, sizeof(*patch)); 240 return prog; 241 } 242 243 insn_adj_cnt = prog->len + insn_delta; 244 245 /* Several new instructions need to be inserted. Make room 246 * for them. Likely, there's no need for a new allocation as 247 * last page could have large enough tailroom. 248 */ 249 prog_adj = bpf_prog_realloc(prog, bpf_prog_size(insn_adj_cnt), 250 GFP_USER); 251 if (!prog_adj) 252 return NULL; 253 254 prog_adj->len = insn_adj_cnt; 255 256 /* Patching happens in 3 steps: 257 * 258 * 1) Move over tail of insnsi from next instruction onwards, 259 * so we can patch the single target insn with one or more 260 * new ones (patching is always from 1 to n insns, n > 0). 261 * 2) Inject new instructions at the target location. 262 * 3) Adjust branch offsets if necessary. 263 */ 264 insn_rest = insn_adj_cnt - off - len; 265 266 memmove(prog_adj->insnsi + off + len, prog_adj->insnsi + off + 1, 267 sizeof(*patch) * insn_rest); 268 memcpy(prog_adj->insnsi + off, patch, sizeof(*patch) * len); 269 270 bpf_adj_branches(prog_adj, off, insn_delta); 271 272 return prog_adj; 273 } 274 275 #ifdef CONFIG_BPF_JIT 276 struct bpf_binary_header * 277 bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 278 unsigned int alignment, 279 bpf_jit_fill_hole_t bpf_fill_ill_insns) 280 { 281 struct bpf_binary_header *hdr; 282 unsigned int size, hole, start; 283 284 /* Most of BPF filters are really small, but if some of them 285 * fill a page, allow at least 128 extra bytes to insert a 286 * random section of illegal instructions. 287 */ 288 size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE); 289 hdr = module_alloc(size); 290 if (hdr == NULL) 291 return NULL; 292 293 /* Fill space with illegal/arch-dep instructions. */ 294 bpf_fill_ill_insns(hdr, size); 295 296 hdr->pages = size / PAGE_SIZE; 297 hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), 298 PAGE_SIZE - sizeof(*hdr)); 299 start = (get_random_int() % hole) & ~(alignment - 1); 300 301 /* Leave a random number of instructions before BPF code. */ 302 *image_ptr = &hdr->image[start]; 303 304 return hdr; 305 } 306 307 void bpf_jit_binary_free(struct bpf_binary_header *hdr) 308 { 309 module_memfree(hdr); 310 } 311 312 int bpf_jit_harden __read_mostly; 313 314 static int bpf_jit_blind_insn(const struct bpf_insn *from, 315 const struct bpf_insn *aux, 316 struct bpf_insn *to_buff) 317 { 318 struct bpf_insn *to = to_buff; 319 u32 imm_rnd = get_random_int(); 320 s16 off; 321 322 BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG); 323 BUILD_BUG_ON(MAX_BPF_REG + 1 != MAX_BPF_JIT_REG); 324 325 if (from->imm == 0 && 326 (from->code == (BPF_ALU | BPF_MOV | BPF_K) || 327 from->code == (BPF_ALU64 | BPF_MOV | BPF_K))) { 328 *to++ = BPF_ALU64_REG(BPF_XOR, from->dst_reg, from->dst_reg); 329 goto out; 330 } 331 332 switch (from->code) { 333 case BPF_ALU | BPF_ADD | BPF_K: 334 case BPF_ALU | BPF_SUB | BPF_K: 335 case BPF_ALU | BPF_AND | BPF_K: 336 case BPF_ALU | BPF_OR | BPF_K: 337 case BPF_ALU | BPF_XOR | BPF_K: 338 case BPF_ALU | BPF_MUL | BPF_K: 339 case BPF_ALU | BPF_MOV | BPF_K: 340 case BPF_ALU | BPF_DIV | BPF_K: 341 case BPF_ALU | BPF_MOD | BPF_K: 342 *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 343 *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 344 *to++ = BPF_ALU32_REG(from->code, from->dst_reg, BPF_REG_AX); 345 break; 346 347 case BPF_ALU64 | BPF_ADD | BPF_K: 348 case BPF_ALU64 | BPF_SUB | BPF_K: 349 case BPF_ALU64 | BPF_AND | BPF_K: 350 case BPF_ALU64 | BPF_OR | BPF_K: 351 case BPF_ALU64 | BPF_XOR | BPF_K: 352 case BPF_ALU64 | BPF_MUL | BPF_K: 353 case BPF_ALU64 | BPF_MOV | BPF_K: 354 case BPF_ALU64 | BPF_DIV | BPF_K: 355 case BPF_ALU64 | BPF_MOD | BPF_K: 356 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 357 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 358 *to++ = BPF_ALU64_REG(from->code, from->dst_reg, BPF_REG_AX); 359 break; 360 361 case BPF_JMP | BPF_JEQ | BPF_K: 362 case BPF_JMP | BPF_JNE | BPF_K: 363 case BPF_JMP | BPF_JGT | BPF_K: 364 case BPF_JMP | BPF_JGE | BPF_K: 365 case BPF_JMP | BPF_JSGT | BPF_K: 366 case BPF_JMP | BPF_JSGE | BPF_K: 367 case BPF_JMP | BPF_JSET | BPF_K: 368 /* Accommodate for extra offset in case of a backjump. */ 369 off = from->off; 370 if (off < 0) 371 off -= 2; 372 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 373 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 374 *to++ = BPF_JMP_REG(from->code, from->dst_reg, BPF_REG_AX, off); 375 break; 376 377 case BPF_LD | BPF_ABS | BPF_W: 378 case BPF_LD | BPF_ABS | BPF_H: 379 case BPF_LD | BPF_ABS | BPF_B: 380 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 381 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 382 *to++ = BPF_LD_IND(from->code, BPF_REG_AX, 0); 383 break; 384 385 case BPF_LD | BPF_IND | BPF_W: 386 case BPF_LD | BPF_IND | BPF_H: 387 case BPF_LD | BPF_IND | BPF_B: 388 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 389 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 390 *to++ = BPF_ALU32_REG(BPF_ADD, BPF_REG_AX, from->src_reg); 391 *to++ = BPF_LD_IND(from->code, BPF_REG_AX, 0); 392 break; 393 394 case BPF_LD | BPF_IMM | BPF_DW: 395 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[1].imm); 396 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 397 *to++ = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32); 398 *to++ = BPF_ALU64_REG(BPF_MOV, aux[0].dst_reg, BPF_REG_AX); 399 break; 400 case 0: /* Part 2 of BPF_LD | BPF_IMM | BPF_DW. */ 401 *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[0].imm); 402 *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 403 *to++ = BPF_ALU64_REG(BPF_OR, aux[0].dst_reg, BPF_REG_AX); 404 break; 405 406 case BPF_ST | BPF_MEM | BPF_DW: 407 case BPF_ST | BPF_MEM | BPF_W: 408 case BPF_ST | BPF_MEM | BPF_H: 409 case BPF_ST | BPF_MEM | BPF_B: 410 *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); 411 *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); 412 *to++ = BPF_STX_MEM(from->code, from->dst_reg, BPF_REG_AX, from->off); 413 break; 414 } 415 out: 416 return to - to_buff; 417 } 418 419 static struct bpf_prog *bpf_prog_clone_create(struct bpf_prog *fp_other, 420 gfp_t gfp_extra_flags) 421 { 422 gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO | 423 gfp_extra_flags; 424 struct bpf_prog *fp; 425 426 fp = __vmalloc(fp_other->pages * PAGE_SIZE, gfp_flags, PAGE_KERNEL); 427 if (fp != NULL) { 428 kmemcheck_annotate_bitfield(fp, meta); 429 430 /* aux->prog still points to the fp_other one, so 431 * when promoting the clone to the real program, 432 * this still needs to be adapted. 433 */ 434 memcpy(fp, fp_other, fp_other->pages * PAGE_SIZE); 435 } 436 437 return fp; 438 } 439 440 static void bpf_prog_clone_free(struct bpf_prog *fp) 441 { 442 /* aux was stolen by the other clone, so we cannot free 443 * it from this path! It will be freed eventually by the 444 * other program on release. 445 * 446 * At this point, we don't need a deferred release since 447 * clone is guaranteed to not be locked. 448 */ 449 fp->aux = NULL; 450 __bpf_prog_free(fp); 451 } 452 453 void bpf_jit_prog_release_other(struct bpf_prog *fp, struct bpf_prog *fp_other) 454 { 455 /* We have to repoint aux->prog to self, as we don't 456 * know whether fp here is the clone or the original. 457 */ 458 fp->aux->prog = fp; 459 bpf_prog_clone_free(fp_other); 460 } 461 462 struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog) 463 { 464 struct bpf_insn insn_buff[16], aux[2]; 465 struct bpf_prog *clone, *tmp; 466 int insn_delta, insn_cnt; 467 struct bpf_insn *insn; 468 int i, rewritten; 469 470 if (!bpf_jit_blinding_enabled()) 471 return prog; 472 473 clone = bpf_prog_clone_create(prog, GFP_USER); 474 if (!clone) 475 return ERR_PTR(-ENOMEM); 476 477 insn_cnt = clone->len; 478 insn = clone->insnsi; 479 480 for (i = 0; i < insn_cnt; i++, insn++) { 481 /* We temporarily need to hold the original ld64 insn 482 * so that we can still access the first part in the 483 * second blinding run. 484 */ 485 if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW) && 486 insn[1].code == 0) 487 memcpy(aux, insn, sizeof(aux)); 488 489 rewritten = bpf_jit_blind_insn(insn, aux, insn_buff); 490 if (!rewritten) 491 continue; 492 493 tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten); 494 if (!tmp) { 495 /* Patching may have repointed aux->prog during 496 * realloc from the original one, so we need to 497 * fix it up here on error. 498 */ 499 bpf_jit_prog_release_other(prog, clone); 500 return ERR_PTR(-ENOMEM); 501 } 502 503 clone = tmp; 504 insn_delta = rewritten - 1; 505 506 /* Walk new program and skip insns we just inserted. */ 507 insn = clone->insnsi + i + insn_delta; 508 insn_cnt += insn_delta; 509 i += insn_delta; 510 } 511 512 return clone; 513 } 514 #endif /* CONFIG_BPF_JIT */ 515 516 /* Base function for offset calculation. Needs to go into .text section, 517 * therefore keeping it non-static as well; will also be used by JITs 518 * anyway later on, so do not let the compiler omit it. 519 */ 520 noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 521 { 522 return 0; 523 } 524 EXPORT_SYMBOL_GPL(__bpf_call_base); 525 526 /** 527 * __bpf_prog_run - run eBPF program on a given context 528 * @ctx: is the data we are operating on 529 * @insn: is the array of eBPF instructions 530 * 531 * Decode and execute eBPF instructions. 532 */ 533 static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn) 534 { 535 u64 stack[MAX_BPF_STACK / sizeof(u64)]; 536 u64 regs[MAX_BPF_REG], tmp; 537 static const void *jumptable[256] = { 538 [0 ... 255] = &&default_label, 539 /* Now overwrite non-defaults ... */ 540 /* 32 bit ALU operations */ 541 [BPF_ALU | BPF_ADD | BPF_X] = &&ALU_ADD_X, 542 [BPF_ALU | BPF_ADD | BPF_K] = &&ALU_ADD_K, 543 [BPF_ALU | BPF_SUB | BPF_X] = &&ALU_SUB_X, 544 [BPF_ALU | BPF_SUB | BPF_K] = &&ALU_SUB_K, 545 [BPF_ALU | BPF_AND | BPF_X] = &&ALU_AND_X, 546 [BPF_ALU | BPF_AND | BPF_K] = &&ALU_AND_K, 547 [BPF_ALU | BPF_OR | BPF_X] = &&ALU_OR_X, 548 [BPF_ALU | BPF_OR | BPF_K] = &&ALU_OR_K, 549 [BPF_ALU | BPF_LSH | BPF_X] = &&ALU_LSH_X, 550 [BPF_ALU | BPF_LSH | BPF_K] = &&ALU_LSH_K, 551 [BPF_ALU | BPF_RSH | BPF_X] = &&ALU_RSH_X, 552 [BPF_ALU | BPF_RSH | BPF_K] = &&ALU_RSH_K, 553 [BPF_ALU | BPF_XOR | BPF_X] = &&ALU_XOR_X, 554 [BPF_ALU | BPF_XOR | BPF_K] = &&ALU_XOR_K, 555 [BPF_ALU | BPF_MUL | BPF_X] = &&ALU_MUL_X, 556 [BPF_ALU | BPF_MUL | BPF_K] = &&ALU_MUL_K, 557 [BPF_ALU | BPF_MOV | BPF_X] = &&ALU_MOV_X, 558 [BPF_ALU | BPF_MOV | BPF_K] = &&ALU_MOV_K, 559 [BPF_ALU | BPF_DIV | BPF_X] = &&ALU_DIV_X, 560 [BPF_ALU | BPF_DIV | BPF_K] = &&ALU_DIV_K, 561 [BPF_ALU | BPF_MOD | BPF_X] = &&ALU_MOD_X, 562 [BPF_ALU | BPF_MOD | BPF_K] = &&ALU_MOD_K, 563 [BPF_ALU | BPF_NEG] = &&ALU_NEG, 564 [BPF_ALU | BPF_END | BPF_TO_BE] = &&ALU_END_TO_BE, 565 [BPF_ALU | BPF_END | BPF_TO_LE] = &&ALU_END_TO_LE, 566 /* 64 bit ALU operations */ 567 [BPF_ALU64 | BPF_ADD | BPF_X] = &&ALU64_ADD_X, 568 [BPF_ALU64 | BPF_ADD | BPF_K] = &&ALU64_ADD_K, 569 [BPF_ALU64 | BPF_SUB | BPF_X] = &&ALU64_SUB_X, 570 [BPF_ALU64 | BPF_SUB | BPF_K] = &&ALU64_SUB_K, 571 [BPF_ALU64 | BPF_AND | BPF_X] = &&ALU64_AND_X, 572 [BPF_ALU64 | BPF_AND | BPF_K] = &&ALU64_AND_K, 573 [BPF_ALU64 | BPF_OR | BPF_X] = &&ALU64_OR_X, 574 [BPF_ALU64 | BPF_OR | BPF_K] = &&ALU64_OR_K, 575 [BPF_ALU64 | BPF_LSH | BPF_X] = &&ALU64_LSH_X, 576 [BPF_ALU64 | BPF_LSH | BPF_K] = &&ALU64_LSH_K, 577 [BPF_ALU64 | BPF_RSH | BPF_X] = &&ALU64_RSH_X, 578 [BPF_ALU64 | BPF_RSH | BPF_K] = &&ALU64_RSH_K, 579 [BPF_ALU64 | BPF_XOR | BPF_X] = &&ALU64_XOR_X, 580 [BPF_ALU64 | BPF_XOR | BPF_K] = &&ALU64_XOR_K, 581 [BPF_ALU64 | BPF_MUL | BPF_X] = &&ALU64_MUL_X, 582 [BPF_ALU64 | BPF_MUL | BPF_K] = &&ALU64_MUL_K, 583 [BPF_ALU64 | BPF_MOV | BPF_X] = &&ALU64_MOV_X, 584 [BPF_ALU64 | BPF_MOV | BPF_K] = &&ALU64_MOV_K, 585 [BPF_ALU64 | BPF_ARSH | BPF_X] = &&ALU64_ARSH_X, 586 [BPF_ALU64 | BPF_ARSH | BPF_K] = &&ALU64_ARSH_K, 587 [BPF_ALU64 | BPF_DIV | BPF_X] = &&ALU64_DIV_X, 588 [BPF_ALU64 | BPF_DIV | BPF_K] = &&ALU64_DIV_K, 589 [BPF_ALU64 | BPF_MOD | BPF_X] = &&ALU64_MOD_X, 590 [BPF_ALU64 | BPF_MOD | BPF_K] = &&ALU64_MOD_K, 591 [BPF_ALU64 | BPF_NEG] = &&ALU64_NEG, 592 /* Call instruction */ 593 [BPF_JMP | BPF_CALL] = &&JMP_CALL, 594 [BPF_JMP | BPF_CALL | BPF_X] = &&JMP_TAIL_CALL, 595 /* Jumps */ 596 [BPF_JMP | BPF_JA] = &&JMP_JA, 597 [BPF_JMP | BPF_JEQ | BPF_X] = &&JMP_JEQ_X, 598 [BPF_JMP | BPF_JEQ | BPF_K] = &&JMP_JEQ_K, 599 [BPF_JMP | BPF_JNE | BPF_X] = &&JMP_JNE_X, 600 [BPF_JMP | BPF_JNE | BPF_K] = &&JMP_JNE_K, 601 [BPF_JMP | BPF_JGT | BPF_X] = &&JMP_JGT_X, 602 [BPF_JMP | BPF_JGT | BPF_K] = &&JMP_JGT_K, 603 [BPF_JMP | BPF_JGE | BPF_X] = &&JMP_JGE_X, 604 [BPF_JMP | BPF_JGE | BPF_K] = &&JMP_JGE_K, 605 [BPF_JMP | BPF_JSGT | BPF_X] = &&JMP_JSGT_X, 606 [BPF_JMP | BPF_JSGT | BPF_K] = &&JMP_JSGT_K, 607 [BPF_JMP | BPF_JSGE | BPF_X] = &&JMP_JSGE_X, 608 [BPF_JMP | BPF_JSGE | BPF_K] = &&JMP_JSGE_K, 609 [BPF_JMP | BPF_JSET | BPF_X] = &&JMP_JSET_X, 610 [BPF_JMP | BPF_JSET | BPF_K] = &&JMP_JSET_K, 611 /* Program return */ 612 [BPF_JMP | BPF_EXIT] = &&JMP_EXIT, 613 /* Store instructions */ 614 [BPF_STX | BPF_MEM | BPF_B] = &&STX_MEM_B, 615 [BPF_STX | BPF_MEM | BPF_H] = &&STX_MEM_H, 616 [BPF_STX | BPF_MEM | BPF_W] = &&STX_MEM_W, 617 [BPF_STX | BPF_MEM | BPF_DW] = &&STX_MEM_DW, 618 [BPF_STX | BPF_XADD | BPF_W] = &&STX_XADD_W, 619 [BPF_STX | BPF_XADD | BPF_DW] = &&STX_XADD_DW, 620 [BPF_ST | BPF_MEM | BPF_B] = &&ST_MEM_B, 621 [BPF_ST | BPF_MEM | BPF_H] = &&ST_MEM_H, 622 [BPF_ST | BPF_MEM | BPF_W] = &&ST_MEM_W, 623 [BPF_ST | BPF_MEM | BPF_DW] = &&ST_MEM_DW, 624 /* Load instructions */ 625 [BPF_LDX | BPF_MEM | BPF_B] = &&LDX_MEM_B, 626 [BPF_LDX | BPF_MEM | BPF_H] = &&LDX_MEM_H, 627 [BPF_LDX | BPF_MEM | BPF_W] = &&LDX_MEM_W, 628 [BPF_LDX | BPF_MEM | BPF_DW] = &&LDX_MEM_DW, 629 [BPF_LD | BPF_ABS | BPF_W] = &&LD_ABS_W, 630 [BPF_LD | BPF_ABS | BPF_H] = &&LD_ABS_H, 631 [BPF_LD | BPF_ABS | BPF_B] = &&LD_ABS_B, 632 [BPF_LD | BPF_IND | BPF_W] = &&LD_IND_W, 633 [BPF_LD | BPF_IND | BPF_H] = &&LD_IND_H, 634 [BPF_LD | BPF_IND | BPF_B] = &&LD_IND_B, 635 [BPF_LD | BPF_IMM | BPF_DW] = &&LD_IMM_DW, 636 }; 637 u32 tail_call_cnt = 0; 638 void *ptr; 639 int off; 640 641 #define CONT ({ insn++; goto select_insn; }) 642 #define CONT_JMP ({ insn++; goto select_insn; }) 643 644 FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; 645 ARG1 = (u64) (unsigned long) ctx; 646 647 select_insn: 648 goto *jumptable[insn->code]; 649 650 /* ALU */ 651 #define ALU(OPCODE, OP) \ 652 ALU64_##OPCODE##_X: \ 653 DST = DST OP SRC; \ 654 CONT; \ 655 ALU_##OPCODE##_X: \ 656 DST = (u32) DST OP (u32) SRC; \ 657 CONT; \ 658 ALU64_##OPCODE##_K: \ 659 DST = DST OP IMM; \ 660 CONT; \ 661 ALU_##OPCODE##_K: \ 662 DST = (u32) DST OP (u32) IMM; \ 663 CONT; 664 665 ALU(ADD, +) 666 ALU(SUB, -) 667 ALU(AND, &) 668 ALU(OR, |) 669 ALU(LSH, <<) 670 ALU(RSH, >>) 671 ALU(XOR, ^) 672 ALU(MUL, *) 673 #undef ALU 674 ALU_NEG: 675 DST = (u32) -DST; 676 CONT; 677 ALU64_NEG: 678 DST = -DST; 679 CONT; 680 ALU_MOV_X: 681 DST = (u32) SRC; 682 CONT; 683 ALU_MOV_K: 684 DST = (u32) IMM; 685 CONT; 686 ALU64_MOV_X: 687 DST = SRC; 688 CONT; 689 ALU64_MOV_K: 690 DST = IMM; 691 CONT; 692 LD_IMM_DW: 693 DST = (u64) (u32) insn[0].imm | ((u64) (u32) insn[1].imm) << 32; 694 insn++; 695 CONT; 696 ALU64_ARSH_X: 697 (*(s64 *) &DST) >>= SRC; 698 CONT; 699 ALU64_ARSH_K: 700 (*(s64 *) &DST) >>= IMM; 701 CONT; 702 ALU64_MOD_X: 703 if (unlikely(SRC == 0)) 704 return 0; 705 div64_u64_rem(DST, SRC, &tmp); 706 DST = tmp; 707 CONT; 708 ALU_MOD_X: 709 if (unlikely(SRC == 0)) 710 return 0; 711 tmp = (u32) DST; 712 DST = do_div(tmp, (u32) SRC); 713 CONT; 714 ALU64_MOD_K: 715 div64_u64_rem(DST, IMM, &tmp); 716 DST = tmp; 717 CONT; 718 ALU_MOD_K: 719 tmp = (u32) DST; 720 DST = do_div(tmp, (u32) IMM); 721 CONT; 722 ALU64_DIV_X: 723 if (unlikely(SRC == 0)) 724 return 0; 725 DST = div64_u64(DST, SRC); 726 CONT; 727 ALU_DIV_X: 728 if (unlikely(SRC == 0)) 729 return 0; 730 tmp = (u32) DST; 731 do_div(tmp, (u32) SRC); 732 DST = (u32) tmp; 733 CONT; 734 ALU64_DIV_K: 735 DST = div64_u64(DST, IMM); 736 CONT; 737 ALU_DIV_K: 738 tmp = (u32) DST; 739 do_div(tmp, (u32) IMM); 740 DST = (u32) tmp; 741 CONT; 742 ALU_END_TO_BE: 743 switch (IMM) { 744 case 16: 745 DST = (__force u16) cpu_to_be16(DST); 746 break; 747 case 32: 748 DST = (__force u32) cpu_to_be32(DST); 749 break; 750 case 64: 751 DST = (__force u64) cpu_to_be64(DST); 752 break; 753 } 754 CONT; 755 ALU_END_TO_LE: 756 switch (IMM) { 757 case 16: 758 DST = (__force u16) cpu_to_le16(DST); 759 break; 760 case 32: 761 DST = (__force u32) cpu_to_le32(DST); 762 break; 763 case 64: 764 DST = (__force u64) cpu_to_le64(DST); 765 break; 766 } 767 CONT; 768 769 /* CALL */ 770 JMP_CALL: 771 /* Function call scratches BPF_R1-BPF_R5 registers, 772 * preserves BPF_R6-BPF_R9, and stores return value 773 * into BPF_R0. 774 */ 775 BPF_R0 = (__bpf_call_base + insn->imm)(BPF_R1, BPF_R2, BPF_R3, 776 BPF_R4, BPF_R5); 777 CONT; 778 779 JMP_TAIL_CALL: { 780 struct bpf_map *map = (struct bpf_map *) (unsigned long) BPF_R2; 781 struct bpf_array *array = container_of(map, struct bpf_array, map); 782 struct bpf_prog *prog; 783 u64 index = BPF_R3; 784 785 if (unlikely(index >= array->map.max_entries)) 786 goto out; 787 if (unlikely(tail_call_cnt > MAX_TAIL_CALL_CNT)) 788 goto out; 789 790 tail_call_cnt++; 791 792 prog = READ_ONCE(array->ptrs[index]); 793 if (!prog) 794 goto out; 795 796 /* ARG1 at this point is guaranteed to point to CTX from 797 * the verifier side due to the fact that the tail call is 798 * handeled like a helper, that is, bpf_tail_call_proto, 799 * where arg1_type is ARG_PTR_TO_CTX. 800 */ 801 insn = prog->insnsi; 802 goto select_insn; 803 out: 804 CONT; 805 } 806 /* JMP */ 807 JMP_JA: 808 insn += insn->off; 809 CONT; 810 JMP_JEQ_X: 811 if (DST == SRC) { 812 insn += insn->off; 813 CONT_JMP; 814 } 815 CONT; 816 JMP_JEQ_K: 817 if (DST == IMM) { 818 insn += insn->off; 819 CONT_JMP; 820 } 821 CONT; 822 JMP_JNE_X: 823 if (DST != SRC) { 824 insn += insn->off; 825 CONT_JMP; 826 } 827 CONT; 828 JMP_JNE_K: 829 if (DST != IMM) { 830 insn += insn->off; 831 CONT_JMP; 832 } 833 CONT; 834 JMP_JGT_X: 835 if (DST > SRC) { 836 insn += insn->off; 837 CONT_JMP; 838 } 839 CONT; 840 JMP_JGT_K: 841 if (DST > IMM) { 842 insn += insn->off; 843 CONT_JMP; 844 } 845 CONT; 846 JMP_JGE_X: 847 if (DST >= SRC) { 848 insn += insn->off; 849 CONT_JMP; 850 } 851 CONT; 852 JMP_JGE_K: 853 if (DST >= IMM) { 854 insn += insn->off; 855 CONT_JMP; 856 } 857 CONT; 858 JMP_JSGT_X: 859 if (((s64) DST) > ((s64) SRC)) { 860 insn += insn->off; 861 CONT_JMP; 862 } 863 CONT; 864 JMP_JSGT_K: 865 if (((s64) DST) > ((s64) IMM)) { 866 insn += insn->off; 867 CONT_JMP; 868 } 869 CONT; 870 JMP_JSGE_X: 871 if (((s64) DST) >= ((s64) SRC)) { 872 insn += insn->off; 873 CONT_JMP; 874 } 875 CONT; 876 JMP_JSGE_K: 877 if (((s64) DST) >= ((s64) IMM)) { 878 insn += insn->off; 879 CONT_JMP; 880 } 881 CONT; 882 JMP_JSET_X: 883 if (DST & SRC) { 884 insn += insn->off; 885 CONT_JMP; 886 } 887 CONT; 888 JMP_JSET_K: 889 if (DST & IMM) { 890 insn += insn->off; 891 CONT_JMP; 892 } 893 CONT; 894 JMP_EXIT: 895 return BPF_R0; 896 897 /* STX and ST and LDX*/ 898 #define LDST(SIZEOP, SIZE) \ 899 STX_MEM_##SIZEOP: \ 900 *(SIZE *)(unsigned long) (DST + insn->off) = SRC; \ 901 CONT; \ 902 ST_MEM_##SIZEOP: \ 903 *(SIZE *)(unsigned long) (DST + insn->off) = IMM; \ 904 CONT; \ 905 LDX_MEM_##SIZEOP: \ 906 DST = *(SIZE *)(unsigned long) (SRC + insn->off); \ 907 CONT; 908 909 LDST(B, u8) 910 LDST(H, u16) 911 LDST(W, u32) 912 LDST(DW, u64) 913 #undef LDST 914 STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */ 915 atomic_add((u32) SRC, (atomic_t *)(unsigned long) 916 (DST + insn->off)); 917 CONT; 918 STX_XADD_DW: /* lock xadd *(u64 *)(dst_reg + off16) += src_reg */ 919 atomic64_add((u64) SRC, (atomic64_t *)(unsigned long) 920 (DST + insn->off)); 921 CONT; 922 LD_ABS_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + imm32)) */ 923 off = IMM; 924 load_word: 925 /* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are 926 * only appearing in the programs where ctx == 927 * skb. All programs keep 'ctx' in regs[BPF_REG_CTX] 928 * == BPF_R6, bpf_convert_filter() saves it in BPF_R6, 929 * internal BPF verifier will check that BPF_R6 == 930 * ctx. 931 * 932 * BPF_ABS and BPF_IND are wrappers of function calls, 933 * so they scratch BPF_R1-BPF_R5 registers, preserve 934 * BPF_R6-BPF_R9, and store return value into BPF_R0. 935 * 936 * Implicit input: 937 * ctx == skb == BPF_R6 == CTX 938 * 939 * Explicit input: 940 * SRC == any register 941 * IMM == 32-bit immediate 942 * 943 * Output: 944 * BPF_R0 - 8/16/32-bit skb data converted to cpu endianness 945 */ 946 947 ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 4, &tmp); 948 if (likely(ptr != NULL)) { 949 BPF_R0 = get_unaligned_be32(ptr); 950 CONT; 951 } 952 953 return 0; 954 LD_ABS_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + imm32)) */ 955 off = IMM; 956 load_half: 957 ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 2, &tmp); 958 if (likely(ptr != NULL)) { 959 BPF_R0 = get_unaligned_be16(ptr); 960 CONT; 961 } 962 963 return 0; 964 LD_ABS_B: /* BPF_R0 = *(u8 *) (skb->data + imm32) */ 965 off = IMM; 966 load_byte: 967 ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 1, &tmp); 968 if (likely(ptr != NULL)) { 969 BPF_R0 = *(u8 *)ptr; 970 CONT; 971 } 972 973 return 0; 974 LD_IND_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + src_reg + imm32)) */ 975 off = IMM + SRC; 976 goto load_word; 977 LD_IND_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + src_reg + imm32)) */ 978 off = IMM + SRC; 979 goto load_half; 980 LD_IND_B: /* BPF_R0 = *(u8 *) (skb->data + src_reg + imm32) */ 981 off = IMM + SRC; 982 goto load_byte; 983 984 default_label: 985 /* If we ever reach this, we have a bug somewhere. */ 986 WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code); 987 return 0; 988 } 989 STACK_FRAME_NON_STANDARD(__bpf_prog_run); /* jump table */ 990 991 bool bpf_prog_array_compatible(struct bpf_array *array, 992 const struct bpf_prog *fp) 993 { 994 if (!array->owner_prog_type) { 995 /* There's no owner yet where we could check for 996 * compatibility. 997 */ 998 array->owner_prog_type = fp->type; 999 array->owner_jited = fp->jited; 1000 1001 return true; 1002 } 1003 1004 return array->owner_prog_type == fp->type && 1005 array->owner_jited == fp->jited; 1006 } 1007 1008 static int bpf_check_tail_call(const struct bpf_prog *fp) 1009 { 1010 struct bpf_prog_aux *aux = fp->aux; 1011 int i; 1012 1013 for (i = 0; i < aux->used_map_cnt; i++) { 1014 struct bpf_map *map = aux->used_maps[i]; 1015 struct bpf_array *array; 1016 1017 if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) 1018 continue; 1019 1020 array = container_of(map, struct bpf_array, map); 1021 if (!bpf_prog_array_compatible(array, fp)) 1022 return -EINVAL; 1023 } 1024 1025 return 0; 1026 } 1027 1028 /** 1029 * bpf_prog_select_runtime - select exec runtime for BPF program 1030 * @fp: bpf_prog populated with internal BPF program 1031 * @err: pointer to error variable 1032 * 1033 * Try to JIT eBPF program, if JIT is not available, use interpreter. 1034 * The BPF program will be executed via BPF_PROG_RUN() macro. 1035 */ 1036 struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err) 1037 { 1038 fp->bpf_func = (void *) __bpf_prog_run; 1039 1040 /* eBPF JITs can rewrite the program in case constant 1041 * blinding is active. However, in case of error during 1042 * blinding, bpf_int_jit_compile() must always return a 1043 * valid program, which in this case would simply not 1044 * be JITed, but falls back to the interpreter. 1045 */ 1046 fp = bpf_int_jit_compile(fp); 1047 bpf_prog_lock_ro(fp); 1048 1049 /* The tail call compatibility check can only be done at 1050 * this late stage as we need to determine, if we deal 1051 * with JITed or non JITed program concatenations and not 1052 * all eBPF JITs might immediately support all features. 1053 */ 1054 *err = bpf_check_tail_call(fp); 1055 1056 return fp; 1057 } 1058 EXPORT_SYMBOL_GPL(bpf_prog_select_runtime); 1059 1060 static void bpf_prog_free_deferred(struct work_struct *work) 1061 { 1062 struct bpf_prog_aux *aux; 1063 1064 aux = container_of(work, struct bpf_prog_aux, work); 1065 bpf_jit_free(aux->prog); 1066 } 1067 1068 /* Free internal BPF program */ 1069 void bpf_prog_free(struct bpf_prog *fp) 1070 { 1071 struct bpf_prog_aux *aux = fp->aux; 1072 1073 INIT_WORK(&aux->work, bpf_prog_free_deferred); 1074 schedule_work(&aux->work); 1075 } 1076 EXPORT_SYMBOL_GPL(bpf_prog_free); 1077 1078 /* RNG for unpriviledged user space with separated state from prandom_u32(). */ 1079 static DEFINE_PER_CPU(struct rnd_state, bpf_user_rnd_state); 1080 1081 void bpf_user_rnd_init_once(void) 1082 { 1083 prandom_init_once(&bpf_user_rnd_state); 1084 } 1085 1086 BPF_CALL_0(bpf_user_rnd_u32) 1087 { 1088 /* Should someone ever have the rather unwise idea to use some 1089 * of the registers passed into this function, then note that 1090 * this function is called from native eBPF and classic-to-eBPF 1091 * transformations. Register assignments from both sides are 1092 * different, f.e. classic always sets fn(ctx, A, X) here. 1093 */ 1094 struct rnd_state *state; 1095 u32 res; 1096 1097 state = &get_cpu_var(bpf_user_rnd_state); 1098 res = prandom_u32_state(state); 1099 put_cpu_var(bpf_user_rnd_state); 1100 1101 return res; 1102 } 1103 1104 /* Weak definitions of helper functions in case we don't have bpf syscall. */ 1105 const struct bpf_func_proto bpf_map_lookup_elem_proto __weak; 1106 const struct bpf_func_proto bpf_map_update_elem_proto __weak; 1107 const struct bpf_func_proto bpf_map_delete_elem_proto __weak; 1108 1109 const struct bpf_func_proto bpf_get_prandom_u32_proto __weak; 1110 const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak; 1111 const struct bpf_func_proto bpf_get_numa_node_id_proto __weak; 1112 const struct bpf_func_proto bpf_ktime_get_ns_proto __weak; 1113 1114 const struct bpf_func_proto bpf_get_current_pid_tgid_proto __weak; 1115 const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak; 1116 const struct bpf_func_proto bpf_get_current_comm_proto __weak; 1117 1118 const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void) 1119 { 1120 return NULL; 1121 } 1122 1123 u64 __weak 1124 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size, 1125 void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy) 1126 { 1127 return -ENOTSUPP; 1128 } 1129 1130 /* Always built-in helper functions. */ 1131 const struct bpf_func_proto bpf_tail_call_proto = { 1132 .func = NULL, 1133 .gpl_only = false, 1134 .ret_type = RET_VOID, 1135 .arg1_type = ARG_PTR_TO_CTX, 1136 .arg2_type = ARG_CONST_MAP_PTR, 1137 .arg3_type = ARG_ANYTHING, 1138 }; 1139 1140 /* For classic BPF JITs that don't implement bpf_int_jit_compile(). */ 1141 struct bpf_prog * __weak bpf_int_jit_compile(struct bpf_prog *prog) 1142 { 1143 return prog; 1144 } 1145 1146 bool __weak bpf_helper_changes_pkt_data(void *func) 1147 { 1148 return false; 1149 } 1150 1151 /* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call 1152 * skb_copy_bits(), so provide a weak definition of it for NET-less config. 1153 */ 1154 int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to, 1155 int len) 1156 { 1157 return -EFAULT; 1158 } 1159