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 || pkt->fragoff) 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 goto err; 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 goto err; 255 256 if (skb_ensure_writable(pkt->skb, 257 nft_thoff(pkt) + i + priv->len)) 258 goto err; 259 260 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, 261 &tcphdr_len); 262 if (!tcph) 263 goto err; 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 return; 307 err: 308 regs->verdict.code = NFT_BREAK; 309 } 310 311 static void nft_exthdr_sctp_eval(const struct nft_expr *expr, 312 struct nft_regs *regs, 313 const struct nft_pktinfo *pkt) 314 { 315 unsigned int offset = nft_thoff(pkt) + sizeof(struct sctphdr); 316 struct nft_exthdr *priv = nft_expr_priv(expr); 317 u32 *dest = ®s->data[priv->dreg]; 318 const struct sctp_chunkhdr *sch; 319 struct sctp_chunkhdr _sch; 320 321 if (pkt->tprot != IPPROTO_SCTP) 322 goto err; 323 324 do { 325 sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch); 326 if (!sch || !sch->length) 327 break; 328 329 if (sch->type == priv->type) { 330 if (priv->flags & NFT_EXTHDR_F_PRESENT) { 331 nft_reg_store8(dest, true); 332 return; 333 } 334 if (priv->offset + priv->len > ntohs(sch->length) || 335 offset + ntohs(sch->length) > pkt->skb->len) 336 break; 337 338 dest[priv->len / NFT_REG32_SIZE] = 0; 339 if (skb_copy_bits(pkt->skb, offset + priv->offset, 340 dest, priv->len) < 0) 341 break; 342 return; 343 } 344 offset += SCTP_PAD4(ntohs(sch->length)); 345 } while (offset < pkt->skb->len); 346 err: 347 if (priv->flags & NFT_EXTHDR_F_PRESENT) 348 nft_reg_store8(dest, false); 349 else 350 regs->verdict.code = NFT_BREAK; 351 } 352 353 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = { 354 [NFTA_EXTHDR_DREG] = { .type = NLA_U32 }, 355 [NFTA_EXTHDR_TYPE] = { .type = NLA_U8 }, 356 [NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 }, 357 [NFTA_EXTHDR_LEN] = { .type = NLA_U32 }, 358 [NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 }, 359 [NFTA_EXTHDR_OP] = { .type = NLA_U32 }, 360 [NFTA_EXTHDR_SREG] = { .type = NLA_U32 }, 361 }; 362 363 static int nft_exthdr_init(const struct nft_ctx *ctx, 364 const struct nft_expr *expr, 365 const struct nlattr * const tb[]) 366 { 367 struct nft_exthdr *priv = nft_expr_priv(expr); 368 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6; 369 int err; 370 371 if (!tb[NFTA_EXTHDR_DREG] || 372 !tb[NFTA_EXTHDR_TYPE] || 373 !tb[NFTA_EXTHDR_OFFSET] || 374 !tb[NFTA_EXTHDR_LEN]) 375 return -EINVAL; 376 377 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset); 378 if (err < 0) 379 return err; 380 381 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len); 382 if (err < 0) 383 return err; 384 385 if (tb[NFTA_EXTHDR_FLAGS]) { 386 err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags); 387 if (err < 0) 388 return err; 389 390 if (flags & ~NFT_EXTHDR_F_PRESENT) 391 return -EINVAL; 392 } 393 394 if (tb[NFTA_EXTHDR_OP]) { 395 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op); 396 if (err < 0) 397 return err; 398 } 399 400 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); 401 priv->offset = offset; 402 priv->len = len; 403 priv->flags = flags; 404 priv->op = op; 405 406 return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG], 407 &priv->dreg, NULL, NFT_DATA_VALUE, 408 priv->len); 409 } 410 411 static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx, 412 const struct nft_expr *expr, 413 const struct nlattr * const tb[]) 414 { 415 struct nft_exthdr *priv = nft_expr_priv(expr); 416 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6; 417 int err; 418 419 if (!tb[NFTA_EXTHDR_SREG] || 420 !tb[NFTA_EXTHDR_TYPE] || 421 !tb[NFTA_EXTHDR_OFFSET] || 422 !tb[NFTA_EXTHDR_LEN]) 423 return -EINVAL; 424 425 if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS]) 426 return -EINVAL; 427 428 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset); 429 if (err < 0) 430 return err; 431 432 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len); 433 if (err < 0) 434 return err; 435 436 if (offset < 2) 437 return -EOPNOTSUPP; 438 439 switch (len) { 440 case 2: break; 441 case 4: break; 442 default: 443 return -EOPNOTSUPP; 444 } 445 446 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op); 447 if (err < 0) 448 return err; 449 450 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); 451 priv->offset = offset; 452 priv->len = len; 453 priv->flags = flags; 454 priv->op = op; 455 456 return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg, 457 priv->len); 458 } 459 460 static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx, 461 const struct nft_expr *expr, 462 const struct nlattr * const tb[]) 463 { 464 struct nft_exthdr *priv = nft_expr_priv(expr); 465 int err = nft_exthdr_init(ctx, expr, tb); 466 467 if (err < 0) 468 return err; 469 470 switch (priv->type) { 471 case IPOPT_SSRR: 472 case IPOPT_LSRR: 473 case IPOPT_RR: 474 case IPOPT_RA: 475 break; 476 default: 477 return -EOPNOTSUPP; 478 } 479 return 0; 480 } 481 482 static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv) 483 { 484 if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type)) 485 goto nla_put_failure; 486 if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset))) 487 goto nla_put_failure; 488 if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len))) 489 goto nla_put_failure; 490 if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags))) 491 goto nla_put_failure; 492 if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op))) 493 goto nla_put_failure; 494 return 0; 495 496 nla_put_failure: 497 return -1; 498 } 499 500 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr) 501 { 502 const struct nft_exthdr *priv = nft_expr_priv(expr); 503 504 if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg)) 505 return -1; 506 507 return nft_exthdr_dump_common(skb, priv); 508 } 509 510 static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr) 511 { 512 const struct nft_exthdr *priv = nft_expr_priv(expr); 513 514 if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg)) 515 return -1; 516 517 return nft_exthdr_dump_common(skb, priv); 518 } 519 520 static const struct nft_expr_ops nft_exthdr_ipv6_ops = { 521 .type = &nft_exthdr_type, 522 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 523 .eval = nft_exthdr_ipv6_eval, 524 .init = nft_exthdr_init, 525 .dump = nft_exthdr_dump, 526 }; 527 528 static const struct nft_expr_ops nft_exthdr_ipv4_ops = { 529 .type = &nft_exthdr_type, 530 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 531 .eval = nft_exthdr_ipv4_eval, 532 .init = nft_exthdr_ipv4_init, 533 .dump = nft_exthdr_dump, 534 }; 535 536 static const struct nft_expr_ops nft_exthdr_tcp_ops = { 537 .type = &nft_exthdr_type, 538 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 539 .eval = nft_exthdr_tcp_eval, 540 .init = nft_exthdr_init, 541 .dump = nft_exthdr_dump, 542 }; 543 544 static const struct nft_expr_ops nft_exthdr_tcp_set_ops = { 545 .type = &nft_exthdr_type, 546 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 547 .eval = nft_exthdr_tcp_set_eval, 548 .init = nft_exthdr_tcp_set_init, 549 .dump = nft_exthdr_dump_set, 550 }; 551 552 static const struct nft_expr_ops nft_exthdr_sctp_ops = { 553 .type = &nft_exthdr_type, 554 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)), 555 .eval = nft_exthdr_sctp_eval, 556 .init = nft_exthdr_init, 557 .dump = nft_exthdr_dump, 558 }; 559 560 static const struct nft_expr_ops * 561 nft_exthdr_select_ops(const struct nft_ctx *ctx, 562 const struct nlattr * const tb[]) 563 { 564 u32 op; 565 566 if (!tb[NFTA_EXTHDR_OP]) 567 return &nft_exthdr_ipv6_ops; 568 569 if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG]) 570 return ERR_PTR(-EOPNOTSUPP); 571 572 op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP])); 573 switch (op) { 574 case NFT_EXTHDR_OP_TCPOPT: 575 if (tb[NFTA_EXTHDR_SREG]) 576 return &nft_exthdr_tcp_set_ops; 577 if (tb[NFTA_EXTHDR_DREG]) 578 return &nft_exthdr_tcp_ops; 579 break; 580 case NFT_EXTHDR_OP_IPV6: 581 if (tb[NFTA_EXTHDR_DREG]) 582 return &nft_exthdr_ipv6_ops; 583 break; 584 case NFT_EXTHDR_OP_IPV4: 585 if (ctx->family != NFPROTO_IPV6) { 586 if (tb[NFTA_EXTHDR_DREG]) 587 return &nft_exthdr_ipv4_ops; 588 } 589 break; 590 case NFT_EXTHDR_OP_SCTP: 591 if (tb[NFTA_EXTHDR_DREG]) 592 return &nft_exthdr_sctp_ops; 593 break; 594 } 595 596 return ERR_PTR(-EOPNOTSUPP); 597 } 598 599 struct nft_expr_type nft_exthdr_type __read_mostly = { 600 .name = "exthdr", 601 .select_ops = nft_exthdr_select_ops, 602 .policy = nft_exthdr_policy, 603 .maxattr = NFTA_EXTHDR_MAX, 604 .owner = THIS_MODULE, 605 }; 606