1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> 4 * 5 * Development of this code funded by Astaro AG (http://www.astaro.com/) 6 */ 7 8 #include <asm/unaligned.h> 9 #include <linux/kernel.h> 10 #include <linux/netlink.h> 11 #include <linux/netfilter.h> 12 #include <linux/netfilter/nf_tables.h> 13 #include <linux/sctp.h> 14 #include <net/netfilter/nf_tables_core.h> 15 #include <net/netfilter/nf_tables.h> 16 #include <net/sctp/sctp.h> 17 #include <net/tcp.h> 18 19 struct nft_exthdr { 20 u8 type; 21 u8 offset; 22 u8 len; 23 u8 op; 24 u8 dreg; 25 u8 sreg; 26 u8 flags; 27 }; 28 29 static unsigned int optlen(const u8 *opt, unsigned int offset) 30 { 31 /* Beware zero-length options: make finite progress */ 32 if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0) 33 return 1; 34 else 35 return opt[offset + 1]; 36 } 37 38 static void nft_exthdr_ipv6_eval(const struct nft_expr *expr, 39 struct nft_regs *regs, 40 const struct nft_pktinfo *pkt) 41 { 42 struct nft_exthdr *priv = nft_expr_priv(expr); 43 u32 *dest = ®s->data[priv->dreg]; 44 unsigned int offset = 0; 45 int err; 46 47 if (pkt->skb->protocol != htons(ETH_P_IPV6)) 48 goto err; 49 50 err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL); 51 if (priv->flags & NFT_EXTHDR_F_PRESENT) { 52 nft_reg_store8(dest, err >= 0); 53 return; 54 } else if (err < 0) { 55 goto err; 56 } 57 offset += priv->offset; 58 59 dest[priv->len / NFT_REG32_SIZE] = 0; 60 if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0) 61 goto err; 62 return; 63 err: 64 regs->verdict.code = NFT_BREAK; 65 } 66 67 /* find the offset to specified option. 68 * 69 * If target header is found, its offset is set in *offset and return option 70 * number. Otherwise, return negative error. 71 * 72 * If the first fragment doesn't contain the End of Options it is considered 73 * invalid. 74 */ 75 static int ipv4_find_option(struct net *net, struct sk_buff *skb, 76 unsigned int *offset, int target) 77 { 78 unsigned char optbuf[sizeof(struct ip_options) + 40]; 79 struct ip_options *opt = (struct ip_options *)optbuf; 80 struct iphdr *iph, _iph; 81 unsigned int start; 82 bool found = false; 83 __be32 info; 84 int optlen; 85 86 iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph); 87 if (!iph) 88 return -EBADMSG; 89 start = sizeof(struct iphdr); 90 91 optlen = iph->ihl * 4 - (int)sizeof(struct iphdr); 92 if (optlen <= 0) 93 return -ENOENT; 94 95 memset(opt, 0, sizeof(struct ip_options)); 96 /* Copy the options since __ip_options_compile() modifies 97 * the options. 98 */ 99 if (skb_copy_bits(skb, start, opt->__data, optlen)) 100 return -EBADMSG; 101 opt->optlen = optlen; 102 103 if (__ip_options_compile(net, opt, NULL, &info)) 104 return -EBADMSG; 105 106 switch (target) { 107 case IPOPT_SSRR: 108 case IPOPT_LSRR: 109 if (!opt->srr) 110 break; 111 found = target == IPOPT_SSRR ? opt->is_strictroute : 112 !opt->is_strictroute; 113 if (found) 114 *offset = opt->srr + start; 115 break; 116 case IPOPT_RR: 117 if (!opt->rr) 118 break; 119 *offset = opt->rr + start; 120 found = true; 121 break; 122 case IPOPT_RA: 123 if (!opt->router_alert) 124 break; 125 *offset = opt->router_alert + start; 126 found = true; 127 break; 128 default: 129 return -EOPNOTSUPP; 130 } 131 return found ? target : -ENOENT; 132 } 133 134 static void nft_exthdr_ipv4_eval(const struct nft_expr *expr, 135 struct nft_regs *regs, 136 const struct nft_pktinfo *pkt) 137 { 138 struct nft_exthdr *priv = nft_expr_priv(expr); 139 u32 *dest = ®s->data[priv->dreg]; 140 struct sk_buff *skb = pkt->skb; 141 unsigned int offset; 142 int err; 143 144 if (skb->protocol != htons(ETH_P_IP)) 145 goto err; 146 147 err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type); 148 if (priv->flags & NFT_EXTHDR_F_PRESENT) { 149 nft_reg_store8(dest, err >= 0); 150 return; 151 } else if (err < 0) { 152 goto err; 153 } 154 offset += priv->offset; 155 156 dest[priv->len / NFT_REG32_SIZE] = 0; 157 if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0) 158 goto err; 159 return; 160 err: 161 regs->verdict.code = NFT_BREAK; 162 } 163 164 static void * 165 nft_tcp_header_pointer(const struct nft_pktinfo *pkt, 166 unsigned int len, void *buffer, unsigned int *tcphdr_len) 167 { 168 struct tcphdr *tcph; 169 170 if (pkt->tprot != IPPROTO_TCP) 171 return NULL; 172 173 tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt), sizeof(*tcph), buffer); 174 if (!tcph) 175 return NULL; 176 177 *tcphdr_len = __tcp_hdrlen(tcph); 178 if (*tcphdr_len < sizeof(*tcph) || *tcphdr_len > len) 179 return NULL; 180 181 return skb_header_pointer(pkt->skb, nft_thoff(pkt), *tcphdr_len, buffer); 182 } 183 184 static void nft_exthdr_tcp_eval(const struct nft_expr *expr, 185 struct nft_regs *regs, 186 const struct nft_pktinfo *pkt) 187 { 188 u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE]; 189 struct nft_exthdr *priv = nft_expr_priv(expr); 190 unsigned int i, optl, tcphdr_len, offset; 191 u32 *dest = ®s->data[priv->dreg]; 192 struct tcphdr *tcph; 193 u8 *opt; 194 195 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len); 196 if (!tcph) 197 goto err; 198 199 opt = (u8 *)tcph; 200 for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) { 201 optl = optlen(opt, i); 202 203 if (priv->type != opt[i]) 204 continue; 205 206 if (i + optl > tcphdr_len || priv->len + priv->offset > optl) 207 goto err; 208 209 offset = i + priv->offset; 210 if (priv->flags & NFT_EXTHDR_F_PRESENT) { 211 *dest = 1; 212 } else { 213 dest[priv->len / NFT_REG32_SIZE] = 0; 214 memcpy(dest, opt + offset, priv->len); 215 } 216 217 return; 218 } 219 220 err: 221 if (priv->flags & NFT_EXTHDR_F_PRESENT) 222 *dest = 0; 223 else 224 regs->verdict.code = NFT_BREAK; 225 } 226 227 static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr, 228 struct nft_regs *regs, 229 const struct nft_pktinfo *pkt) 230 { 231 u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE]; 232 struct nft_exthdr *priv = nft_expr_priv(expr); 233 unsigned int i, optl, tcphdr_len, offset; 234 struct tcphdr *tcph; 235 u8 *opt; 236 237 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len); 238 if (!tcph) 239 return; 240 241 opt = (u8 *)tcph; 242 for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) { 243 union { 244 __be16 v16; 245 __be32 v32; 246 } old, new; 247 248 optl = optlen(opt, i); 249 250 if (priv->type != opt[i]) 251 continue; 252 253 if (i + optl > tcphdr_len || priv->len + priv->offset > optl) 254 return; 255 256 if (skb_ensure_writable(pkt->skb, 257 nft_thoff(pkt) + i + priv->len)) 258 return; 259 260 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, 261 &tcphdr_len); 262 if (!tcph) 263 return; 264 265 offset = i + priv->offset; 266 267 switch (priv->len) { 268 case 2: 269 old.v16 = get_unaligned((u16 *)(opt + offset)); 270 new.v16 = (__force __be16)nft_reg_load16( 271 ®s->data[priv->sreg]); 272 273 switch (priv->type) { 274 case TCPOPT_MSS: 275 /* increase can cause connection to stall */ 276 if (ntohs(old.v16) <= ntohs(new.v16)) 277 return; 278 break; 279 } 280 281 if (old.v16 == new.v16) 282 return; 283 284 put_unaligned(new.v16, (u16*)(opt + offset)); 285 inet_proto_csum_replace2(&tcph->check, pkt->skb, 286 old.v16, new.v16, false); 287 break; 288 case 4: 289 new.v32 = regs->data[priv->sreg]; 290 old.v32 = get_unaligned((u32 *)(opt + offset)); 291 292 if (old.v32 == new.v32) 293 return; 294 295 put_unaligned(new.v32, (u32*)(opt + offset)); 296 inet_proto_csum_replace4(&tcph->check, pkt->skb, 297 old.v32, new.v32, false); 298 break; 299 default: 300 WARN_ON_ONCE(1); 301 break; 302 } 303 304 return; 305 } 306 } 307 308 static void nft_exthdr_sctp_eval(const struct nft_expr *expr, 309 struct nft_regs *regs, 310 const struct nft_pktinfo *pkt) 311 { 312 unsigned int offset = nft_thoff(pkt) + sizeof(struct sctphdr); 313 struct nft_exthdr *priv = nft_expr_priv(expr); 314 u32 *dest = ®s->data[priv->dreg]; 315 const struct sctp_chunkhdr *sch; 316 struct sctp_chunkhdr _sch; 317 318 if (pkt->tprot != IPPROTO_SCTP) 319 goto err; 320 321 do { 322 sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch); 323 if (!sch || !sch->length) 324 break; 325 326 if (sch->type == priv->type) { 327 if (priv->flags & NFT_EXTHDR_F_PRESENT) { 328 nft_reg_store8(dest, true); 329 return; 330 } 331 if (priv->offset + priv->len > ntohs(sch->length) || 332 offset + ntohs(sch->length) > pkt->skb->len) 333 break; 334 335 dest[priv->len / NFT_REG32_SIZE] = 0; 336 if (skb_copy_bits(pkt->skb, offset + priv->offset, 337 dest, priv->len) < 0) 338 break; 339 return; 340 } 341 offset += SCTP_PAD4(ntohs(sch->length)); 342 } while (offset < pkt->skb->len); 343 err: 344 if (priv->flags & NFT_EXTHDR_F_PRESENT) 345 nft_reg_store8(dest, false); 346 else 347 regs->verdict.code = NFT_BREAK; 348 } 349 350 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = { 351 [NFTA_EXTHDR_DREG] = { .type = NLA_U32 }, 352 [NFTA_EXTHDR_TYPE] = { .type = NLA_U8 }, 353 [NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 }, 354 [NFTA_EXTHDR_LEN] = { .type = NLA_U32 }, 355 [NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 }, 356 [NFTA_EXTHDR_OP] = { .type = NLA_U32 }, 357 [NFTA_EXTHDR_SREG] = { .type = NLA_U32 }, 358 }; 359 360 static int nft_exthdr_init(const struct nft_ctx *ctx, 361 const struct nft_expr *expr, 362 const struct nlattr * const tb[]) 363 { 364 struct nft_exthdr *priv = nft_expr_priv(expr); 365 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6; 366 int err; 367 368 if (!tb[NFTA_EXTHDR_DREG] || 369 !tb[NFTA_EXTHDR_TYPE] || 370 !tb[NFTA_EXTHDR_OFFSET] || 371 !tb[NFTA_EXTHDR_LEN]) 372 return -EINVAL; 373 374 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset); 375 if (err < 0) 376 return err; 377 378 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len); 379 if (err < 0) 380 return err; 381 382 if (tb[NFTA_EXTHDR_FLAGS]) { 383 err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags); 384 if (err < 0) 385 return err; 386 387 if (flags & ~NFT_EXTHDR_F_PRESENT) 388 return -EINVAL; 389 } 390 391 if (tb[NFTA_EXTHDR_OP]) { 392 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op); 393 if (err < 0) 394 return err; 395 } 396 397 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); 398 priv->offset = offset; 399 priv->len = len; 400 priv->flags = flags; 401 priv->op = op; 402 403 return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG], 404 &priv->dreg, NULL, NFT_DATA_VALUE, 405 priv->len); 406 } 407 408 static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx, 409 const struct nft_expr *expr, 410 const struct nlattr * const tb[]) 411 { 412 struct nft_exthdr *priv = nft_expr_priv(expr); 413 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6; 414 int err; 415 416 if (!tb[NFTA_EXTHDR_SREG] || 417 !tb[NFTA_EXTHDR_TYPE] || 418 !tb[NFTA_EXTHDR_OFFSET] || 419 !tb[NFTA_EXTHDR_LEN]) 420 return -EINVAL; 421 422 if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS]) 423 return -EINVAL; 424 425 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset); 426 if (err < 0) 427 return err; 428 429 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len); 430 if (err < 0) 431 return err; 432 433 if (offset < 2) 434 return -EOPNOTSUPP; 435 436 switch (len) { 437 case 2: break; 438 case 4: break; 439 default: 440 return -EOPNOTSUPP; 441 } 442 443 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op); 444 if (err < 0) 445 return err; 446 447 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); 448 priv->offset = offset; 449 priv->len = len; 450 priv->flags = flags; 451 priv->op = op; 452 453 return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg, 454 priv->len); 455 } 456 457 static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx, 458 const struct nft_expr *expr, 459 const struct nlattr * const tb[]) 460 { 461 struct nft_exthdr *priv = nft_expr_priv(expr); 462 int err = nft_exthdr_init(ctx, expr, tb); 463 464 if (err < 0) 465 return err; 466 467 switch (priv->type) { 468 case IPOPT_SSRR: 469 case IPOPT_LSRR: 470 case IPOPT_RR: 471 case IPOPT_RA: 472 break; 473 default: 474 return -EOPNOTSUPP; 475 } 476 return 0; 477 } 478 479 static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv) 480 { 481 if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type)) 482 goto nla_put_failure; 483 if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset))) 484 goto nla_put_failure; 485 if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len))) 486 goto nla_put_failure; 487 if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags))) 488 goto nla_put_failure; 489 if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op))) 490 goto nla_put_failure; 491 return 0; 492 493 nla_put_failure: 494 return -1; 495 } 496 497 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr) 498 { 499 const struct nft_exthdr *priv = nft_expr_priv(expr); 500 501 if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg)) 502 return -1; 503 504 return nft_exthdr_dump_common(skb, priv); 505 } 506 507 static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr) 508 { 509 const struct nft_exthdr *priv = nft_expr_priv(expr); 510 511 if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg)) 512 return -1; 513 514 return nft_exthdr_dump_common(skb, priv); 515 } 516 517 static const struct nft_expr_ops nft_exthdr_ipv6_ops = { 518 .type = &nft_exthdr_type, 519 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 520 .eval = nft_exthdr_ipv6_eval, 521 .init = nft_exthdr_init, 522 .dump = nft_exthdr_dump, 523 }; 524 525 static const struct nft_expr_ops nft_exthdr_ipv4_ops = { 526 .type = &nft_exthdr_type, 527 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 528 .eval = nft_exthdr_ipv4_eval, 529 .init = nft_exthdr_ipv4_init, 530 .dump = nft_exthdr_dump, 531 }; 532 533 static const struct nft_expr_ops nft_exthdr_tcp_ops = { 534 .type = &nft_exthdr_type, 535 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 536 .eval = nft_exthdr_tcp_eval, 537 .init = nft_exthdr_init, 538 .dump = nft_exthdr_dump, 539 }; 540 541 static const struct nft_expr_ops nft_exthdr_tcp_set_ops = { 542 .type = &nft_exthdr_type, 543 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 544 .eval = nft_exthdr_tcp_set_eval, 545 .init = nft_exthdr_tcp_set_init, 546 .dump = nft_exthdr_dump_set, 547 }; 548 549 static const struct nft_expr_ops nft_exthdr_sctp_ops = { 550 .type = &nft_exthdr_type, 551 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 552 .eval = nft_exthdr_sctp_eval, 553 .init = nft_exthdr_init, 554 .dump = nft_exthdr_dump, 555 }; 556 557 static const struct nft_expr_ops * 558 nft_exthdr_select_ops(const struct nft_ctx *ctx, 559 const struct nlattr * const tb[]) 560 { 561 u32 op; 562 563 if (!tb[NFTA_EXTHDR_OP]) 564 return &nft_exthdr_ipv6_ops; 565 566 if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG]) 567 return ERR_PTR(-EOPNOTSUPP); 568 569 op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP])); 570 switch (op) { 571 case NFT_EXTHDR_OP_TCPOPT: 572 if (tb[NFTA_EXTHDR_SREG]) 573 return &nft_exthdr_tcp_set_ops; 574 if (tb[NFTA_EXTHDR_DREG]) 575 return &nft_exthdr_tcp_ops; 576 break; 577 case NFT_EXTHDR_OP_IPV6: 578 if (tb[NFTA_EXTHDR_DREG]) 579 return &nft_exthdr_ipv6_ops; 580 break; 581 case NFT_EXTHDR_OP_IPV4: 582 if (ctx->family != NFPROTO_IPV6) { 583 if (tb[NFTA_EXTHDR_DREG]) 584 return &nft_exthdr_ipv4_ops; 585 } 586 break; 587 case NFT_EXTHDR_OP_SCTP: 588 if (tb[NFTA_EXTHDR_DREG]) 589 return &nft_exthdr_sctp_ops; 590 break; 591 } 592 593 return ERR_PTR(-EOPNOTSUPP); 594 } 595 596 struct nft_expr_type nft_exthdr_type __read_mostly = { 597 .name = "exthdr", 598 .select_ops = nft_exthdr_select_ops, 599 .policy = nft_exthdr_policy, 600 .maxattr = NFTA_EXTHDR_MAX, 601 .owner = THIS_MODULE, 602 }; 603