1/* SIP extension for IP connection tracking. 2 * 3 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar> 4 * based on RR's ip_conntrack_ftp.c and other modules. 5 * (C) 2007 United Security Providers 6 * (C) 2007, 2008 Patrick McHardy <kaber@trash.net> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13#include <linux/module.h> 14#include <linux/ctype.h> 15#include <linux/skbuff.h> 16#include <linux/inet.h> 17#include <linux/in.h> 18#include <linux/udp.h> 19#include <linux/tcp.h> 20#include <linux/netfilter.h> 21 22#include <net/netfilter/nf_conntrack.h> 23#include <net/netfilter/nf_conntrack_core.h> 24#include <net/netfilter/nf_conntrack_expect.h> 25#include <net/netfilter/nf_conntrack_helper.h> 26#include <net/netfilter/nf_conntrack_zones.h> 27#include <linux/netfilter/nf_conntrack_sip.h> 28 29MODULE_LICENSE("GPL"); 30MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); 31MODULE_DESCRIPTION("SIP connection tracking helper"); 32MODULE_ALIAS("ip_conntrack_sip"); 33MODULE_ALIAS_NFCT_HELPER("sip"); 34 35#define MAX_PORTS 8 36static unsigned short ports[MAX_PORTS]; 37static unsigned int ports_c; 38module_param_array(ports, ushort, &ports_c, 0400); 39MODULE_PARM_DESC(ports, "port numbers of SIP servers"); 40 41static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT; 42module_param(sip_timeout, uint, 0600); 43MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session"); 44 45static int sip_direct_signalling __read_mostly = 1; 46module_param(sip_direct_signalling, int, 0600); 47MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar " 48 "only (default 1)"); 49 50static int sip_direct_media __read_mostly = 1; 51module_param(sip_direct_media, int, 0600); 52MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling " 53 "endpoints only (default 1)"); 54 55unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int dataoff, 56 const char **dptr, 57 unsigned int *datalen) __read_mostly; 58EXPORT_SYMBOL_GPL(nf_nat_sip_hook); 59 60void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, s16 off) __read_mostly; 61EXPORT_SYMBOL_GPL(nf_nat_sip_seq_adjust_hook); 62 63unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb, 64 unsigned int dataoff, 65 const char **dptr, 66 unsigned int *datalen, 67 struct nf_conntrack_expect *exp, 68 unsigned int matchoff, 69 unsigned int matchlen) __read_mostly; 70EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook); 71 72unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb, unsigned int dataoff, 73 const char **dptr, 74 unsigned int *datalen, 75 unsigned int sdpoff, 76 enum sdp_header_types type, 77 enum sdp_header_types term, 78 const union nf_inet_addr *addr) 79 __read_mostly; 80EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook); 81 82unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb, unsigned int dataoff, 83 const char **dptr, 84 unsigned int *datalen, 85 unsigned int matchoff, 86 unsigned int matchlen, 87 u_int16_t port) __read_mostly; 88EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook); 89 90unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb, 91 unsigned int dataoff, 92 const char **dptr, 93 unsigned int *datalen, 94 unsigned int sdpoff, 95 const union nf_inet_addr *addr) 96 __read_mostly; 97EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook); 98 99unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb, unsigned int dataoff, 100 const char **dptr, 101 unsigned int *datalen, 102 struct nf_conntrack_expect *rtp_exp, 103 struct nf_conntrack_expect *rtcp_exp, 104 unsigned int mediaoff, 105 unsigned int medialen, 106 union nf_inet_addr *rtp_addr) 107 __read_mostly; 108EXPORT_SYMBOL_GPL(nf_nat_sdp_media_hook); 109 110static int string_len(const struct nf_conn *ct, const char *dptr, 111 const char *limit, int *shift) 112{ 113 int len = 0; 114 115 while (dptr < limit && isalpha(*dptr)) { 116 dptr++; 117 len++; 118 } 119 return len; 120} 121 122static int digits_len(const struct nf_conn *ct, const char *dptr, 123 const char *limit, int *shift) 124{ 125 int len = 0; 126 while (dptr < limit && isdigit(*dptr)) { 127 dptr++; 128 len++; 129 } 130 return len; 131} 132 133/* get media type + port length */ 134static int media_len(const struct nf_conn *ct, const char *dptr, 135 const char *limit, int *shift) 136{ 137 int len = string_len(ct, dptr, limit, shift); 138 139 dptr += len; 140 if (dptr >= limit || *dptr != ' ') 141 return 0; 142 len++; 143 dptr++; 144 145 return len + digits_len(ct, dptr, limit, shift); 146} 147 148static int parse_addr(const struct nf_conn *ct, const char *cp, 149 const char **endp, union nf_inet_addr *addr, 150 const char *limit) 151{ 152 const char *end; 153 int ret = 0; 154 155 memset(addr, 0, sizeof(*addr)); 156 switch (nf_ct_l3num(ct)) { 157 case AF_INET: 158 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end); 159 break; 160 case AF_INET6: 161 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end); 162 break; 163 default: 164 BUG(); 165 } 166 167 if (ret == 0 || end == cp) 168 return 0; 169 if (endp) 170 *endp = end; 171 return 1; 172} 173 174/* skip ip address. returns its length. */ 175static int epaddr_len(const struct nf_conn *ct, const char *dptr, 176 const char *limit, int *shift) 177{ 178 union nf_inet_addr addr; 179 const char *aux = dptr; 180 181 if (!parse_addr(ct, dptr, &dptr, &addr, limit)) { 182 pr_debug("ip: %s parse failed.!\n", dptr); 183 return 0; 184 } 185 186 /* Port number */ 187 if (*dptr == ':') { 188 dptr++; 189 dptr += digits_len(ct, dptr, limit, shift); 190 } 191 return dptr - aux; 192} 193 194/* get address length, skiping user info. */ 195static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr, 196 const char *limit, int *shift) 197{ 198 const char *start = dptr; 199 int s = *shift; 200 201 /* Search for @, but stop at the end of the line. 202 * We are inside a sip: URI, so we don't need to worry about 203 * continuation lines. */ 204 while (dptr < limit && 205 *dptr != '@' && *dptr != '\r' && *dptr != '\n') { 206 (*shift)++; 207 dptr++; 208 } 209 210 if (dptr < limit && *dptr == '@') { 211 dptr++; 212 (*shift)++; 213 } else { 214 dptr = start; 215 *shift = s; 216 } 217 218 return epaddr_len(ct, dptr, limit, shift); 219} 220 221/* Parse a SIP request line of the form: 222 * 223 * Request-Line = Method SP Request-URI SP SIP-Version CRLF 224 * 225 * and return the offset and length of the address contained in the Request-URI. 226 */ 227int ct_sip_parse_request(const struct nf_conn *ct, 228 const char *dptr, unsigned int datalen, 229 unsigned int *matchoff, unsigned int *matchlen, 230 union nf_inet_addr *addr, __be16 *port) 231{ 232 const char *start = dptr, *limit = dptr + datalen, *end; 233 unsigned int mlen; 234 unsigned int p; 235 int shift = 0; 236 237 /* Skip method and following whitespace */ 238 mlen = string_len(ct, dptr, limit, NULL); 239 if (!mlen) 240 return 0; 241 dptr += mlen; 242 if (++dptr >= limit) 243 return 0; 244 245 /* Find SIP URI */ 246 for (; dptr < limit - strlen("sip:"); dptr++) { 247 if (*dptr == '\r' || *dptr == '\n') 248 return -1; 249 if (strnicmp(dptr, "sip:", strlen("sip:")) == 0) { 250 dptr += strlen("sip:"); 251 break; 252 } 253 } 254 if (!skp_epaddr_len(ct, dptr, limit, &shift)) 255 return 0; 256 dptr += shift; 257 258 if (!parse_addr(ct, dptr, &end, addr, limit)) 259 return -1; 260 if (end < limit && *end == ':') { 261 end++; 262 p = simple_strtoul(end, (char **)&end, 10); 263 if (p < 1024 || p > 65535) 264 return -1; 265 *port = htons(p); 266 } else 267 *port = htons(SIP_PORT); 268 269 if (end == dptr) 270 return 0; 271 *matchoff = dptr - start; 272 *matchlen = end - dptr; 273 return 1; 274} 275EXPORT_SYMBOL_GPL(ct_sip_parse_request); 276 277/* SIP header parsing: SIP headers are located at the beginning of a line, but 278 * may span several lines, in which case the continuation lines begin with a 279 * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or 280 * CRLF, RFC 3261 allows only CRLF, we support both. 281 * 282 * Headers are followed by (optionally) whitespace, a colon, again (optionally) 283 * whitespace and the values. Whitespace in this context means any amount of 284 * tabs, spaces and continuation lines, which are treated as a single whitespace 285 * character. 286 * 287 * Some headers may appear multiple times. A comma separated list of values is 288 * equivalent to multiple headers. 289 */ 290static const struct sip_header ct_sip_hdrs[] = { 291 [SIP_HDR_CSEQ] = SIP_HDR("CSeq", NULL, NULL, digits_len), 292 [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len), 293 [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len), 294 [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len), 295 [SIP_HDR_VIA_UDP] = SIP_HDR("Via", "v", "UDP ", epaddr_len), 296 [SIP_HDR_VIA_TCP] = SIP_HDR("Via", "v", "TCP ", epaddr_len), 297 [SIP_HDR_EXPIRES] = SIP_HDR("Expires", NULL, NULL, digits_len), 298 [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len), 299}; 300 301static const char *sip_follow_continuation(const char *dptr, const char *limit) 302{ 303 /* Walk past newline */ 304 if (++dptr >= limit) 305 return NULL; 306 307 /* Skip '\n' in CR LF */ 308 if (*(dptr - 1) == '\r' && *dptr == '\n') { 309 if (++dptr >= limit) 310 return NULL; 311 } 312 313 /* Continuation line? */ 314 if (*dptr != ' ' && *dptr != '\t') 315 return NULL; 316 317 /* skip leading whitespace */ 318 for (; dptr < limit; dptr++) { 319 if (*dptr != ' ' && *dptr != '\t') 320 break; 321 } 322 return dptr; 323} 324 325static const char *sip_skip_whitespace(const char *dptr, const char *limit) 326{ 327 for (; dptr < limit; dptr++) { 328 if (*dptr == ' ') 329 continue; 330 if (*dptr != '\r' && *dptr != '\n') 331 break; 332 dptr = sip_follow_continuation(dptr, limit); 333 if (dptr == NULL) 334 return NULL; 335 } 336 return dptr; 337} 338 339/* Search within a SIP header value, dealing with continuation lines */ 340static const char *ct_sip_header_search(const char *dptr, const char *limit, 341 const char *needle, unsigned int len) 342{ 343 for (limit -= len; dptr < limit; dptr++) { 344 if (*dptr == '\r' || *dptr == '\n') { 345 dptr = sip_follow_continuation(dptr, limit); 346 if (dptr == NULL) 347 break; 348 continue; 349 } 350 351 if (strnicmp(dptr, needle, len) == 0) 352 return dptr; 353 } 354 return NULL; 355} 356 357int ct_sip_get_header(const struct nf_conn *ct, const char *dptr, 358 unsigned int dataoff, unsigned int datalen, 359 enum sip_header_types type, 360 unsigned int *matchoff, unsigned int *matchlen) 361{ 362 const struct sip_header *hdr = &ct_sip_hdrs[type]; 363 const char *start = dptr, *limit = dptr + datalen; 364 int shift = 0; 365 366 for (dptr += dataoff; dptr < limit; dptr++) { 367 /* Find beginning of line */ 368 if (*dptr != '\r' && *dptr != '\n') 369 continue; 370 if (++dptr >= limit) 371 break; 372 if (*(dptr - 1) == '\r' && *dptr == '\n') { 373 if (++dptr >= limit) 374 break; 375 } 376 377 /* Skip continuation lines */ 378 if (*dptr == ' ' || *dptr == '\t') 379 continue; 380 381 /* Find header. Compact headers must be followed by a 382 * non-alphabetic character to avoid mismatches. */ 383 if (limit - dptr >= hdr->len && 384 strnicmp(dptr, hdr->name, hdr->len) == 0) 385 dptr += hdr->len; 386 else if (hdr->cname && limit - dptr >= hdr->clen + 1 && 387 strnicmp(dptr, hdr->cname, hdr->clen) == 0 && 388 !isalpha(*(dptr + hdr->clen))) 389 dptr += hdr->clen; 390 else 391 continue; 392 393 /* Find and skip colon */ 394 dptr = sip_skip_whitespace(dptr, limit); 395 if (dptr == NULL) 396 break; 397 if (*dptr != ':' || ++dptr >= limit) 398 break; 399 400 /* Skip whitespace after colon */ 401 dptr = sip_skip_whitespace(dptr, limit); 402 if (dptr == NULL) 403 break; 404 405 *matchoff = dptr - start; 406 if (hdr->search) { 407 dptr = ct_sip_header_search(dptr, limit, hdr->search, 408 hdr->slen); 409 if (!dptr) 410 return -1; 411 dptr += hdr->slen; 412 } 413 414 *matchlen = hdr->match_len(ct, dptr, limit, &shift); 415 if (!*matchlen) 416 return -1; 417 *matchoff = dptr - start + shift; 418 return 1; 419 } 420 return 0; 421} 422EXPORT_SYMBOL_GPL(ct_sip_get_header); 423 424/* Get next header field in a list of comma separated values */ 425static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr, 426 unsigned int dataoff, unsigned int datalen, 427 enum sip_header_types type, 428 unsigned int *matchoff, unsigned int *matchlen) 429{ 430 const struct sip_header *hdr = &ct_sip_hdrs[type]; 431 const char *start = dptr, *limit = dptr + datalen; 432 int shift = 0; 433 434 dptr += dataoff; 435 436 dptr = ct_sip_header_search(dptr, limit, ",", strlen(",")); 437 if (!dptr) 438 return 0; 439 440 dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen); 441 if (!dptr) 442 return 0; 443 dptr += hdr->slen; 444 445 *matchoff = dptr - start; 446 *matchlen = hdr->match_len(ct, dptr, limit, &shift); 447 if (!*matchlen) 448 return -1; 449 *matchoff += shift; 450 return 1; 451} 452 453/* Walk through headers until a parsable one is found or no header of the 454 * given type is left. */ 455static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr, 456 unsigned int dataoff, unsigned int datalen, 457 enum sip_header_types type, int *in_header, 458 unsigned int *matchoff, unsigned int *matchlen) 459{ 460 int ret; 461 462 if (in_header && *in_header) { 463 while (1) { 464 ret = ct_sip_next_header(ct, dptr, dataoff, datalen, 465 type, matchoff, matchlen); 466 if (ret > 0) 467 return ret; 468 if (ret == 0) 469 break; 470 dataoff += *matchoff; 471 } 472 *in_header = 0; 473 } 474 475 while (1) { 476 ret = ct_sip_get_header(ct, dptr, dataoff, datalen, 477 type, matchoff, matchlen); 478 if (ret > 0) 479 break; 480 if (ret == 0) 481 return ret; 482 dataoff += *matchoff; 483 } 484 485 if (in_header) 486 *in_header = 1; 487 return 1; 488} 489 490/* Locate a SIP header, parse the URI and return the offset and length of 491 * the address as well as the address and port themselves. A stream of 492 * headers can be parsed by handing in a non-NULL datalen and in_header 493 * pointer. 494 */ 495int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr, 496 unsigned int *dataoff, unsigned int datalen, 497 enum sip_header_types type, int *in_header, 498 unsigned int *matchoff, unsigned int *matchlen, 499 union nf_inet_addr *addr, __be16 *port) 500{ 501 const char *c, *limit = dptr + datalen; 502 unsigned int p; 503 int ret; 504 505 ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen, 506 type, in_header, matchoff, matchlen); 507 WARN_ON(ret < 0); 508 if (ret == 0) 509 return ret; 510 511 if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit)) 512 return -1; 513 if (*c == ':') { 514 c++; 515 p = simple_strtoul(c, (char **)&c, 10); 516 if (p < 1024 || p > 65535) 517 return -1; 518 *port = htons(p); 519 } else 520 *port = htons(SIP_PORT); 521 522 if (dataoff) 523 *dataoff = c - dptr; 524 return 1; 525} 526EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri); 527 528static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr, 529 unsigned int dataoff, unsigned int datalen, 530 const char *name, 531 unsigned int *matchoff, unsigned int *matchlen) 532{ 533 const char *limit = dptr + datalen; 534 const char *start; 535 const char *end; 536 537 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); 538 if (!limit) 539 limit = dptr + datalen; 540 541 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); 542 if (!start) 543 return 0; 544 start += strlen(name); 545 546 end = ct_sip_header_search(start, limit, ";", strlen(";")); 547 if (!end) 548 end = limit; 549 550 *matchoff = start - dptr; 551 *matchlen = end - start; 552 return 1; 553} 554 555/* Parse address from header parameter and return address, offset and length */ 556int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr, 557 unsigned int dataoff, unsigned int datalen, 558 const char *name, 559 unsigned int *matchoff, unsigned int *matchlen, 560 union nf_inet_addr *addr) 561{ 562 const char *limit = dptr + datalen; 563 const char *start, *end; 564 565 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); 566 if (!limit) 567 limit = dptr + datalen; 568 569 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); 570 if (!start) 571 return 0; 572 573 start += strlen(name); 574 if (!parse_addr(ct, start, &end, addr, limit)) 575 return 0; 576 *matchoff = start - dptr; 577 *matchlen = end - start; 578 return 1; 579} 580EXPORT_SYMBOL_GPL(ct_sip_parse_address_param); 581 582/* Parse numerical header parameter and return value, offset and length */ 583int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr, 584 unsigned int dataoff, unsigned int datalen, 585 const char *name, 586 unsigned int *matchoff, unsigned int *matchlen, 587 unsigned int *val) 588{ 589 const char *limit = dptr + datalen; 590 const char *start; 591 char *end; 592 593 limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(",")); 594 if (!limit) 595 limit = dptr + datalen; 596 597 start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name)); 598 if (!start) 599 return 0; 600 601 start += strlen(name); 602 *val = simple_strtoul(start, &end, 0); 603 if (start == end) 604 return 0; 605 if (matchoff && matchlen) { 606 *matchoff = start - dptr; 607 *matchlen = end - start; 608 } 609 return 1; 610} 611EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param); 612 613static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr, 614 unsigned int dataoff, unsigned int datalen, 615 u8 *proto) 616{ 617 unsigned int matchoff, matchlen; 618 619 if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=", 620 &matchoff, &matchlen)) { 621 if (!strnicmp(dptr + matchoff, "TCP", strlen("TCP"))) 622 *proto = IPPROTO_TCP; 623 else if (!strnicmp(dptr + matchoff, "UDP", strlen("UDP"))) 624 *proto = IPPROTO_UDP; 625 else 626 return 0; 627 628 if (*proto != nf_ct_protonum(ct)) 629 return 0; 630 } else 631 *proto = nf_ct_protonum(ct); 632 633 return 1; 634} 635 636/* SDP header parsing: a SDP session description contains an ordered set of 637 * headers, starting with a section containing general session parameters, 638 * optionally followed by multiple media descriptions. 639 * 640 * SDP headers always start at the beginning of a line. According to RFC 2327: 641 * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should 642 * be tolerant and also accept records terminated with a single newline 643 * character". We handle both cases. 644 */ 645static const struct sip_header ct_sdp_hdrs[] = { 646 [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len), 647 [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len), 648 [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len), 649 [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len), 650 [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len), 651 [SDP_HDR_MEDIA] = SDP_HDR("m=", NULL, media_len), 652}; 653 654/* Linear string search within SDP header values */ 655static const char *ct_sdp_header_search(const char *dptr, const char *limit, 656 const char *needle, unsigned int len) 657{ 658 for (limit -= len; dptr < limit; dptr++) { 659 if (*dptr == '\r' || *dptr == '\n') 660 break; 661 if (strncmp(dptr, needle, len) == 0) 662 return dptr; 663 } 664 return NULL; 665} 666 667/* Locate a SDP header (optionally a substring within the header value), 668 * optionally stopping at the first occurence of the term header, parse 669 * it and return the offset and length of the data we're interested in. 670 */ 671int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, 672 unsigned int dataoff, unsigned int datalen, 673 enum sdp_header_types type, 674 enum sdp_header_types term, 675 unsigned int *matchoff, unsigned int *matchlen) 676{ 677 const struct sip_header *hdr = &ct_sdp_hdrs[type]; 678 const struct sip_header *thdr = &ct_sdp_hdrs[term]; 679 const char *start = dptr, *limit = dptr + datalen; 680 int shift = 0; 681 682 for (dptr += dataoff; dptr < limit; dptr++) { 683 /* Find beginning of line */ 684 if (*dptr != '\r' && *dptr != '\n') 685 continue; 686 if (++dptr >= limit) 687 break; 688 if (*(dptr - 1) == '\r' && *dptr == '\n') { 689 if (++dptr >= limit) 690 break; 691 } 692 693 if (term != SDP_HDR_UNSPEC && 694 limit - dptr >= thdr->len && 695 strnicmp(dptr, thdr->name, thdr->len) == 0) 696 break; 697 else if (limit - dptr >= hdr->len && 698 strnicmp(dptr, hdr->name, hdr->len) == 0) 699 dptr += hdr->len; 700 else 701 continue; 702 703 *matchoff = dptr - start; 704 if (hdr->search) { 705 dptr = ct_sdp_header_search(dptr, limit, hdr->search, 706 hdr->slen); 707 if (!dptr) 708 return -1; 709 dptr += hdr->slen; 710 } 711 712 *matchlen = hdr->match_len(ct, dptr, limit, &shift); 713 if (!*matchlen) 714 return -1; 715 *matchoff = dptr - start + shift; 716 return 1; 717 } 718 return 0; 719} 720EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header); 721 722static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr, 723 unsigned int dataoff, unsigned int datalen, 724 enum sdp_header_types type, 725 enum sdp_header_types term, 726 unsigned int *matchoff, unsigned int *matchlen, 727 union nf_inet_addr *addr) 728{ 729 int ret; 730 731 ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term, 732 matchoff, matchlen); 733 if (ret <= 0) 734 return ret; 735 736 if (!parse_addr(ct, dptr + *matchoff, NULL, addr, 737 dptr + *matchoff + *matchlen)) 738 return -1; 739 return 1; 740} 741 742static int refresh_signalling_expectation(struct nf_conn *ct, 743 union nf_inet_addr *addr, 744 u8 proto, __be16 port, 745 unsigned int expires) 746{ 747 struct nf_conn_help *help = nfct_help(ct); 748 struct nf_conntrack_expect *exp; 749 struct hlist_node *n, *next; 750 int found = 0; 751 752 spin_lock_bh(&nf_conntrack_lock); 753 hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) { 754 if (exp->class != SIP_EXPECT_SIGNALLING || 755 !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) || 756 exp->tuple.dst.protonum != proto || 757 exp->tuple.dst.u.udp.port != port) 758 continue; 759 if (!del_timer(&exp->timeout)) 760 continue; 761 exp->flags &= ~NF_CT_EXPECT_INACTIVE; 762 exp->timeout.expires = jiffies + expires * HZ; 763 add_timer(&exp->timeout); 764 found = 1; 765 break; 766 } 767 spin_unlock_bh(&nf_conntrack_lock); 768 return found; 769} 770 771static void flush_expectations(struct nf_conn *ct, bool media) 772{ 773 struct nf_conn_help *help = nfct_help(ct); 774 struct nf_conntrack_expect *exp; 775 struct hlist_node *n, *next; 776 777 spin_lock_bh(&nf_conntrack_lock); 778 hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) { 779 if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media) 780 continue; 781 if (!del_timer(&exp->timeout)) 782 continue; 783 nf_ct_unlink_expect(exp); 784 nf_ct_expect_put(exp); 785 if (!media) 786 break; 787 } 788 spin_unlock_bh(&nf_conntrack_lock); 789} 790 791static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int dataoff, 792 const char **dptr, unsigned int *datalen, 793 union nf_inet_addr *daddr, __be16 port, 794 enum sip_expectation_classes class, 795 unsigned int mediaoff, unsigned int medialen) 796{ 797 struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp; 798 enum ip_conntrack_info ctinfo; 799 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 800 struct net *net = nf_ct_net(ct); 801 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 802 union nf_inet_addr *saddr; 803 struct nf_conntrack_tuple tuple; 804 int direct_rtp = 0, skip_expect = 0, ret = NF_DROP; 805 u_int16_t base_port; 806 __be16 rtp_port, rtcp_port; 807 typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port; 808 typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media; 809 810 saddr = NULL; 811 if (sip_direct_media) { 812 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3)) 813 return NF_ACCEPT; 814 saddr = &ct->tuplehash[!dir].tuple.src.u3; 815 } 816 817 /* We need to check whether the registration exists before attempting 818 * to register it since we can see the same media description multiple 819 * times on different connections in case multiple endpoints receive 820 * the same call. 821 * 822 * RTP optimization: if we find a matching media channel expectation 823 * and both the expectation and this connection are SNATed, we assume 824 * both sides can reach each other directly and use the final 825 * destination address from the expectation. We still need to keep 826 * the NATed expectations for media that might arrive from the 827 * outside, and additionally need to expect the direct RTP stream 828 * in case it passes through us even without NAT. 829 */ 830 memset(&tuple, 0, sizeof(tuple)); 831 if (saddr) 832 tuple.src.u3 = *saddr; 833 tuple.src.l3num = nf_ct_l3num(ct); 834 tuple.dst.protonum = IPPROTO_UDP; 835 tuple.dst.u3 = *daddr; 836 tuple.dst.u.udp.port = port; 837 838 rcu_read_lock(); 839 do { 840 exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple); 841 842 if (!exp || exp->master == ct || 843 nfct_help(exp->master)->helper != nfct_help(ct)->helper || 844 exp->class != class) 845 break; 846#ifdef CONFIG_NF_NAT_NEEDED 847 if (exp->tuple.src.l3num == AF_INET && !direct_rtp && 848 (exp->saved_ip != exp->tuple.dst.u3.ip || 849 exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) && 850 ct->status & IPS_NAT_MASK) { 851 daddr->ip = exp->saved_ip; 852 tuple.dst.u3.ip = exp->saved_ip; 853 tuple.dst.u.udp.port = exp->saved_proto.udp.port; 854 direct_rtp = 1; 855 } else 856#endif 857 skip_expect = 1; 858 } while (!skip_expect); 859 rcu_read_unlock(); 860 861 base_port = ntohs(tuple.dst.u.udp.port) & ~1; 862 rtp_port = htons(base_port); 863 rtcp_port = htons(base_port + 1); 864 865 if (direct_rtp) { 866 nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook); 867 if (nf_nat_sdp_port && 868 !nf_nat_sdp_port(skb, dataoff, dptr, datalen, 869 mediaoff, medialen, ntohs(rtp_port))) 870 goto err1; 871 } 872 873 if (skip_expect) 874 return NF_ACCEPT; 875 876 rtp_exp = nf_ct_expect_alloc(ct); 877 if (rtp_exp == NULL) 878 goto err1; 879 nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr, 880 IPPROTO_UDP, NULL, &rtp_port); 881 882 rtcp_exp = nf_ct_expect_alloc(ct); 883 if (rtcp_exp == NULL) 884 goto err2; 885 nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr, 886 IPPROTO_UDP, NULL, &rtcp_port); 887 888 nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook); 889 if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp) 890 ret = nf_nat_sdp_media(skb, dataoff, dptr, datalen, 891 rtp_exp, rtcp_exp, 892 mediaoff, medialen, daddr); 893 else { 894 if (nf_ct_expect_related(rtp_exp) == 0) { 895 if (nf_ct_expect_related(rtcp_exp) != 0) 896 nf_ct_unexpect_related(rtp_exp); 897 else 898 ret = NF_ACCEPT; 899 } 900 } 901 nf_ct_expect_put(rtcp_exp); 902err2: 903 nf_ct_expect_put(rtp_exp); 904err1: 905 return ret; 906} 907 908static const struct sdp_media_type sdp_media_types[] = { 909 SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO), 910 SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO), 911 SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE), 912}; 913 914static const struct sdp_media_type *sdp_media_type(const char *dptr, 915 unsigned int matchoff, 916 unsigned int matchlen) 917{ 918 const struct sdp_media_type *t; 919 unsigned int i; 920 921 for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) { 922 t = &sdp_media_types[i]; 923 if (matchlen < t->len || 924 strncmp(dptr + matchoff, t->name, t->len)) 925 continue; 926 return t; 927 } 928 return NULL; 929} 930 931static int process_sdp(struct sk_buff *skb, unsigned int dataoff, 932 const char **dptr, unsigned int *datalen, 933 unsigned int cseq) 934{ 935 enum ip_conntrack_info ctinfo; 936 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 937 unsigned int matchoff, matchlen; 938 unsigned int mediaoff, medialen; 939 unsigned int sdpoff; 940 unsigned int caddr_len, maddr_len; 941 unsigned int i; 942 union nf_inet_addr caddr, maddr, rtp_addr; 943 unsigned int port; 944 enum sdp_header_types c_hdr; 945 const struct sdp_media_type *t; 946 int ret = NF_ACCEPT; 947 typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr; 948 typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session; 949 950 nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook); 951 c_hdr = nf_ct_l3num(ct) == AF_INET ? SDP_HDR_CONNECTION_IP4 : 952 SDP_HDR_CONNECTION_IP6; 953 954 /* Find beginning of session description */ 955 if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, 956 SDP_HDR_VERSION, SDP_HDR_UNSPEC, 957 &matchoff, &matchlen) <= 0) 958 return NF_ACCEPT; 959 sdpoff = matchoff; 960 961 /* The connection information is contained in the session description 962 * and/or once per media description. The first media description marks 963 * the end of the session description. */ 964 caddr_len = 0; 965 if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen, 966 c_hdr, SDP_HDR_MEDIA, 967 &matchoff, &matchlen, &caddr) > 0) 968 caddr_len = matchlen; 969 970 mediaoff = sdpoff; 971 for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) { 972 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen, 973 SDP_HDR_MEDIA, SDP_HDR_UNSPEC, 974 &mediaoff, &medialen) <= 0) 975 break; 976 977 /* Get media type and port number. A media port value of zero 978 * indicates an inactive stream. */ 979 t = sdp_media_type(*dptr, mediaoff, medialen); 980 if (!t) { 981 mediaoff += medialen; 982 continue; 983 } 984 mediaoff += t->len; 985 medialen -= t->len; 986 987 port = simple_strtoul(*dptr + mediaoff, NULL, 10); 988 if (port == 0) 989 continue; 990 if (port < 1024 || port > 65535) 991 return NF_DROP; 992 993 /* The media description overrides the session description. */ 994 maddr_len = 0; 995 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen, 996 c_hdr, SDP_HDR_MEDIA, 997 &matchoff, &matchlen, &maddr) > 0) { 998 maddr_len = matchlen; 999 memcpy(&rtp_addr, &maddr, sizeof(rtp_addr)); 1000 } else if (caddr_len) 1001 memcpy(&rtp_addr, &caddr, sizeof(rtp_addr)); 1002 else 1003 return NF_DROP; 1004 1005 ret = set_expected_rtp_rtcp(skb, dataoff, dptr, datalen, 1006 &rtp_addr, htons(port), t->class, 1007 mediaoff, medialen); 1008 if (ret != NF_ACCEPT) 1009 return ret; 1010 1011 /* Update media connection address if present */ 1012 if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) { 1013 ret = nf_nat_sdp_addr(skb, dataoff, dptr, datalen, 1014 mediaoff, c_hdr, SDP_HDR_MEDIA, 1015 &rtp_addr); 1016 if (ret != NF_ACCEPT) 1017 return ret; 1018 } 1019 i++; 1020 } 1021 1022 /* Update session connection and owner addresses */ 1023 nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook); 1024 if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK) 1025 ret = nf_nat_sdp_session(skb, dataoff, dptr, datalen, sdpoff, 1026 &rtp_addr); 1027 1028 return ret; 1029} 1030static int process_invite_response(struct sk_buff *skb, unsigned int dataoff, 1031 const char **dptr, unsigned int *datalen, 1032 unsigned int cseq, unsigned int code) 1033{ 1034 enum ip_conntrack_info ctinfo; 1035 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1036 struct nf_conn_help *help = nfct_help(ct); 1037 1038 if ((code >= 100 && code <= 199) || 1039 (code >= 200 && code <= 299)) 1040 return process_sdp(skb, dataoff, dptr, datalen, cseq); 1041 else if (help->help.ct_sip_info.invite_cseq == cseq) 1042 flush_expectations(ct, true); 1043 return NF_ACCEPT; 1044} 1045 1046static int process_update_response(struct sk_buff *skb, unsigned int dataoff, 1047 const char **dptr, unsigned int *datalen, 1048 unsigned int cseq, unsigned int code) 1049{ 1050 enum ip_conntrack_info ctinfo; 1051 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1052 struct nf_conn_help *help = nfct_help(ct); 1053 1054 if ((code >= 100 && code <= 199) || 1055 (code >= 200 && code <= 299)) 1056 return process_sdp(skb, dataoff, dptr, datalen, cseq); 1057 else if (help->help.ct_sip_info.invite_cseq == cseq) 1058 flush_expectations(ct, true); 1059 return NF_ACCEPT; 1060} 1061 1062static int process_prack_response(struct sk_buff *skb, unsigned int dataoff, 1063 const char **dptr, unsigned int *datalen, 1064 unsigned int cseq, unsigned int code) 1065{ 1066 enum ip_conntrack_info ctinfo; 1067 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1068 struct nf_conn_help *help = nfct_help(ct); 1069 1070 if ((code >= 100 && code <= 199) || 1071 (code >= 200 && code <= 299)) 1072 return process_sdp(skb, dataoff, dptr, datalen, cseq); 1073 else if (help->help.ct_sip_info.invite_cseq == cseq) 1074 flush_expectations(ct, true); 1075 return NF_ACCEPT; 1076} 1077 1078static int process_invite_request(struct sk_buff *skb, unsigned int dataoff, 1079 const char **dptr, unsigned int *datalen, 1080 unsigned int cseq) 1081{ 1082 enum ip_conntrack_info ctinfo; 1083 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1084 struct nf_conn_help *help = nfct_help(ct); 1085 unsigned int ret; 1086 1087 flush_expectations(ct, true); 1088 ret = process_sdp(skb, dataoff, dptr, datalen, cseq); 1089 if (ret == NF_ACCEPT) 1090 help->help.ct_sip_info.invite_cseq = cseq; 1091 return ret; 1092} 1093 1094static int process_bye_request(struct sk_buff *skb, unsigned int dataoff, 1095 const char **dptr, unsigned int *datalen, 1096 unsigned int cseq) 1097{ 1098 enum ip_conntrack_info ctinfo; 1099 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1100 1101 flush_expectations(ct, true); 1102 return NF_ACCEPT; 1103} 1104 1105/* Parse a REGISTER request and create a permanent expectation for incoming 1106 * signalling connections. The expectation is marked inactive and is activated 1107 * when receiving a response indicating success from the registrar. 1108 */ 1109static int process_register_request(struct sk_buff *skb, unsigned int dataoff, 1110 const char **dptr, unsigned int *datalen, 1111 unsigned int cseq) 1112{ 1113 enum ip_conntrack_info ctinfo; 1114 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1115 struct nf_conn_help *help = nfct_help(ct); 1116 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 1117 unsigned int matchoff, matchlen; 1118 struct nf_conntrack_expect *exp; 1119 union nf_inet_addr *saddr, daddr; 1120 __be16 port; 1121 u8 proto; 1122 unsigned int expires = 0; 1123 int ret; 1124 typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect; 1125 1126 /* Expected connections can not register again. */ 1127 if (ct->status & IPS_EXPECTED) 1128 return NF_ACCEPT; 1129 1130 /* We must check the expiration time: a value of zero signals the 1131 * registrar to release the binding. We'll remove our expectation 1132 * when receiving the new bindings in the response, but we don't 1133 * want to create new ones. 1134 * 1135 * The expiration time may be contained in Expires: header, the 1136 * Contact: header parameters or the URI parameters. 1137 */ 1138 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES, 1139 &matchoff, &matchlen) > 0) 1140 expires = simple_strtoul(*dptr + matchoff, NULL, 10); 1141 1142 ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, 1143 SIP_HDR_CONTACT, NULL, 1144 &matchoff, &matchlen, &daddr, &port); 1145 if (ret < 0) 1146 return NF_DROP; 1147 else if (ret == 0) 1148 return NF_ACCEPT; 1149 1150 /* We don't support third-party registrations */ 1151 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr)) 1152 return NF_ACCEPT; 1153 1154 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen, 1155 &proto) == 0) 1156 return NF_ACCEPT; 1157 1158 if (ct_sip_parse_numerical_param(ct, *dptr, 1159 matchoff + matchlen, *datalen, 1160 "expires=", NULL, NULL, &expires) < 0) 1161 return NF_DROP; 1162 1163 if (expires == 0) { 1164 ret = NF_ACCEPT; 1165 goto store_cseq; 1166 } 1167 1168 exp = nf_ct_expect_alloc(ct); 1169 if (!exp) 1170 return NF_DROP; 1171 1172 saddr = NULL; 1173 if (sip_direct_signalling) 1174 saddr = &ct->tuplehash[!dir].tuple.src.u3; 1175 1176 nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct), 1177 saddr, &daddr, proto, NULL, &port); 1178 exp->timeout.expires = sip_timeout * HZ; 1179 exp->helper = nfct_help(ct)->helper; 1180 exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE; 1181 1182 nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook); 1183 if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK) 1184 ret = nf_nat_sip_expect(skb, dataoff, dptr, datalen, exp, 1185 matchoff, matchlen); 1186 else { 1187 if (nf_ct_expect_related(exp) != 0) 1188 ret = NF_DROP; 1189 else 1190 ret = NF_ACCEPT; 1191 } 1192 nf_ct_expect_put(exp); 1193 1194store_cseq: 1195 if (ret == NF_ACCEPT) 1196 help->help.ct_sip_info.register_cseq = cseq; 1197 return ret; 1198} 1199 1200static int process_register_response(struct sk_buff *skb, unsigned int dataoff, 1201 const char **dptr, unsigned int *datalen, 1202 unsigned int cseq, unsigned int code) 1203{ 1204 enum ip_conntrack_info ctinfo; 1205 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1206 struct nf_conn_help *help = nfct_help(ct); 1207 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 1208 union nf_inet_addr addr; 1209 __be16 port; 1210 u8 proto; 1211 unsigned int matchoff, matchlen, coff = 0; 1212 unsigned int expires = 0; 1213 int in_contact = 0, ret; 1214 1215 /* According to RFC 3261, "UAs MUST NOT send a new registration until 1216 * they have received a final response from the registrar for the 1217 * previous one or the previous REGISTER request has timed out". 1218 * 1219 * However, some servers fail to detect retransmissions and send late 1220 * responses, so we store the sequence number of the last valid 1221 * request and compare it here. 1222 */ 1223 if (help->help.ct_sip_info.register_cseq != cseq) 1224 return NF_ACCEPT; 1225 1226 if (code >= 100 && code <= 199) 1227 return NF_ACCEPT; 1228 if (code < 200 || code > 299) 1229 goto flush; 1230 1231 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES, 1232 &matchoff, &matchlen) > 0) 1233 expires = simple_strtoul(*dptr + matchoff, NULL, 10); 1234 1235 while (1) { 1236 unsigned int c_expires = expires; 1237 1238 ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen, 1239 SIP_HDR_CONTACT, &in_contact, 1240 &matchoff, &matchlen, 1241 &addr, &port); 1242 if (ret < 0) 1243 return NF_DROP; 1244 else if (ret == 0) 1245 break; 1246 1247 /* We don't support third-party registrations */ 1248 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr)) 1249 continue; 1250 1251 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, 1252 *datalen, &proto) == 0) 1253 continue; 1254 1255 ret = ct_sip_parse_numerical_param(ct, *dptr, 1256 matchoff + matchlen, 1257 *datalen, "expires=", 1258 NULL, NULL, &c_expires); 1259 if (ret < 0) 1260 return NF_DROP; 1261 if (c_expires == 0) 1262 break; 1263 if (refresh_signalling_expectation(ct, &addr, proto, port, 1264 c_expires)) 1265 return NF_ACCEPT; 1266 } 1267 1268flush: 1269 flush_expectations(ct, false); 1270 return NF_ACCEPT; 1271} 1272 1273static const struct sip_handler sip_handlers[] = { 1274 SIP_HANDLER("INVITE", process_invite_request, process_invite_response), 1275 SIP_HANDLER("UPDATE", process_sdp, process_update_response), 1276 SIP_HANDLER("ACK", process_sdp, NULL), 1277 SIP_HANDLER("PRACK", process_sdp, process_prack_response), 1278 SIP_HANDLER("BYE", process_bye_request, NULL), 1279 SIP_HANDLER("REGISTER", process_register_request, process_register_response), 1280}; 1281 1282static int process_sip_response(struct sk_buff *skb, unsigned int dataoff, 1283 const char **dptr, unsigned int *datalen) 1284{ 1285 enum ip_conntrack_info ctinfo; 1286 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1287 unsigned int matchoff, matchlen, matchend; 1288 unsigned int code, cseq, i; 1289 1290 if (*datalen < strlen("SIP/2.0 200")) 1291 return NF_ACCEPT; 1292 code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10); 1293 if (!code) 1294 return NF_DROP; 1295 1296 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, 1297 &matchoff, &matchlen) <= 0) 1298 return NF_DROP; 1299 cseq = simple_strtoul(*dptr + matchoff, NULL, 10); 1300 if (!cseq) 1301 return NF_DROP; 1302 matchend = matchoff + matchlen + 1; 1303 1304 for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { 1305 const struct sip_handler *handler; 1306 1307 handler = &sip_handlers[i]; 1308 if (handler->response == NULL) 1309 continue; 1310 if (*datalen < matchend + handler->len || 1311 strnicmp(*dptr + matchend, handler->method, handler->len)) 1312 continue; 1313 return handler->response(skb, dataoff, dptr, datalen, 1314 cseq, code); 1315 } 1316 return NF_ACCEPT; 1317} 1318 1319static int process_sip_request(struct sk_buff *skb, unsigned int dataoff, 1320 const char **dptr, unsigned int *datalen) 1321{ 1322 enum ip_conntrack_info ctinfo; 1323 struct nf_conn *ct = nf_ct_get(skb, &ctinfo); 1324 unsigned int matchoff, matchlen; 1325 unsigned int cseq, i; 1326 1327 for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) { 1328 const struct sip_handler *handler; 1329 1330 handler = &sip_handlers[i]; 1331 if (handler->request == NULL) 1332 continue; 1333 if (*datalen < handler->len || 1334 strnicmp(*dptr, handler->method, handler->len)) 1335 continue; 1336 1337 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ, 1338 &matchoff, &matchlen) <= 0) 1339 return NF_DROP; 1340 cseq = simple_strtoul(*dptr + matchoff, NULL, 10); 1341 if (!cseq) 1342 return NF_DROP; 1343 1344 return handler->request(skb, dataoff, dptr, datalen, cseq); 1345 } 1346 return NF_ACCEPT; 1347} 1348 1349static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct, 1350 unsigned int dataoff, const char **dptr, 1351 unsigned int *datalen) 1352{ 1353 typeof(nf_nat_sip_hook) nf_nat_sip; 1354 int ret; 1355 1356 if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0) 1357 ret = process_sip_request(skb, dataoff, dptr, datalen); 1358 else 1359 ret = process_sip_response(skb, dataoff, dptr, datalen); 1360 1361 if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) { 1362 nf_nat_sip = rcu_dereference(nf_nat_sip_hook); 1363 if (nf_nat_sip && !nf_nat_sip(skb, dataoff, dptr, datalen)) 1364 ret = NF_DROP; 1365 } 1366 1367 return ret; 1368} 1369 1370static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff, 1371 struct nf_conn *ct, enum ip_conntrack_info ctinfo) 1372{ 1373 struct tcphdr *th, _tcph; 1374 unsigned int dataoff, datalen; 1375 unsigned int matchoff, matchlen, clen; 1376 unsigned int msglen, origlen; 1377 const char *dptr, *end; 1378 s16 diff, tdiff = 0; 1379 int ret = NF_ACCEPT; 1380 typeof(nf_nat_sip_seq_adjust_hook) nf_nat_sip_seq_adjust; 1381 1382 if (ctinfo != IP_CT_ESTABLISHED && 1383 ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) 1384 return NF_ACCEPT; 1385 1386 /* No Data ? */ 1387 th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); 1388 if (th == NULL) 1389 return NF_ACCEPT; 1390 dataoff = protoff + th->doff * 4; 1391 if (dataoff >= skb->len) 1392 return NF_ACCEPT; 1393 1394 nf_ct_refresh(ct, skb, sip_timeout * HZ); 1395 1396 if (unlikely(skb_linearize(skb))) 1397 return NF_DROP; 1398 1399 dptr = skb->data + dataoff; 1400 datalen = skb->len - dataoff; 1401 if (datalen < strlen("SIP/2.0 200")) 1402 return NF_ACCEPT; 1403 1404 while (1) { 1405 if (ct_sip_get_header(ct, dptr, 0, datalen, 1406 SIP_HDR_CONTENT_LENGTH, 1407 &matchoff, &matchlen) <= 0) 1408 break; 1409 1410 clen = simple_strtoul(dptr + matchoff, (char **)&end, 10); 1411 if (dptr + matchoff == end) 1412 break; 1413 1414 if (end + strlen("\r\n\r\n") > dptr + datalen) 1415 break; 1416 if (end[0] != '\r' || end[1] != '\n' || 1417 end[2] != '\r' || end[3] != '\n') 1418 break; 1419 end += strlen("\r\n\r\n") + clen; 1420 1421 msglen = origlen = end - dptr; 1422 1423 ret = process_sip_msg(skb, ct, dataoff, &dptr, &msglen); 1424 if (ret != NF_ACCEPT) 1425 break; 1426 diff = msglen - origlen; 1427 tdiff += diff; 1428 1429 dataoff += msglen; 1430 dptr += msglen; 1431 datalen = datalen + diff - msglen; 1432 } 1433 1434 if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) { 1435 nf_nat_sip_seq_adjust = rcu_dereference(nf_nat_sip_seq_adjust_hook); 1436 if (nf_nat_sip_seq_adjust) 1437 nf_nat_sip_seq_adjust(skb, tdiff); 1438 } 1439 1440 return ret; 1441} 1442 1443static int sip_help_udp(struct sk_buff *skb, unsigned int protoff, 1444 struct nf_conn *ct, enum ip_conntrack_info ctinfo) 1445{ 1446 unsigned int dataoff, datalen; 1447 const char *dptr; 1448 1449 /* No Data ? */ 1450 dataoff = protoff + sizeof(struct udphdr); 1451 if (dataoff >= skb->len) 1452 return NF_ACCEPT; 1453 1454 nf_ct_refresh(ct, skb, sip_timeout * HZ); 1455 1456 if (unlikely(skb_linearize(skb))) 1457 return NF_DROP; 1458 1459 dptr = skb->data + dataoff; 1460 datalen = skb->len - dataoff; 1461 if (datalen < strlen("SIP/2.0 200")) 1462 return NF_ACCEPT; 1463 1464 return process_sip_msg(skb, ct, dataoff, &dptr, &datalen); 1465} 1466 1467static struct nf_conntrack_helper sip[MAX_PORTS][4] __read_mostly; 1468static char sip_names[MAX_PORTS][4][sizeof("sip-65535")] __read_mostly; 1469 1470static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = { 1471 [SIP_EXPECT_SIGNALLING] = { 1472 .name = "signalling", 1473 .max_expected = 1, 1474 .timeout = 3 * 60, 1475 }, 1476 [SIP_EXPECT_AUDIO] = { 1477 .name = "audio", 1478 .max_expected = 2 * IP_CT_DIR_MAX, 1479 .timeout = 3 * 60, 1480 }, 1481 [SIP_EXPECT_VIDEO] = { 1482 .name = "video", 1483 .max_expected = 2 * IP_CT_DIR_MAX, 1484 .timeout = 3 * 60, 1485 }, 1486 [SIP_EXPECT_IMAGE] = { 1487 .name = "image", 1488 .max_expected = IP_CT_DIR_MAX, 1489 .timeout = 3 * 60, 1490 }, 1491}; 1492 1493static void nf_conntrack_sip_fini(void) 1494{ 1495 int i, j; 1496 1497 for (i = 0; i < ports_c; i++) { 1498 for (j = 0; j < ARRAY_SIZE(sip[i]); j++) { 1499 if (sip[i][j].me == NULL) 1500 continue; 1501 nf_conntrack_helper_unregister(&sip[i][j]); 1502 } 1503 } 1504} 1505 1506static int __init nf_conntrack_sip_init(void) 1507{ 1508 int i, j, ret; 1509 char *tmpname; 1510 1511 if (ports_c == 0) 1512 ports[ports_c++] = SIP_PORT; 1513 1514 for (i = 0; i < ports_c; i++) { 1515 memset(&sip[i], 0, sizeof(sip[i])); 1516 1517 sip[i][0].tuple.src.l3num = AF_INET; 1518 sip[i][0].tuple.dst.protonum = IPPROTO_UDP; 1519 sip[i][0].help = sip_help_udp; 1520 sip[i][1].tuple.src.l3num = AF_INET; 1521 sip[i][1].tuple.dst.protonum = IPPROTO_TCP; 1522 sip[i][1].help = sip_help_tcp; 1523 1524 sip[i][2].tuple.src.l3num = AF_INET6; 1525 sip[i][2].tuple.dst.protonum = IPPROTO_UDP; 1526 sip[i][2].help = sip_help_udp; 1527 sip[i][3].tuple.src.l3num = AF_INET6; 1528 sip[i][3].tuple.dst.protonum = IPPROTO_TCP; 1529 sip[i][3].help = sip_help_tcp; 1530 1531 for (j = 0; j < ARRAY_SIZE(sip[i]); j++) { 1532 sip[i][j].tuple.src.u.udp.port = htons(ports[i]); 1533 sip[i][j].expect_policy = sip_exp_policy; 1534 sip[i][j].expect_class_max = SIP_EXPECT_MAX; 1535 sip[i][j].me = THIS_MODULE; 1536 1537 tmpname = &sip_names[i][j][0]; 1538 if (ports[i] == SIP_PORT) 1539 sprintf(tmpname, "sip"); 1540 else 1541 sprintf(tmpname, "sip-%u", i); 1542 sip[i][j].name = tmpname; 1543 1544 pr_debug("port #%u: %u\n", i, ports[i]); 1545 1546 ret = nf_conntrack_helper_register(&sip[i][j]); 1547 if (ret) { 1548 printk(KERN_ERR "nf_ct_sip: failed to register" 1549 " helper for pf: %u port: %u\n", 1550 sip[i][j].tuple.src.l3num, ports[i]); 1551 nf_conntrack_sip_fini(); 1552 return ret; 1553 } 1554 } 1555 } 1556 return 0; 1557} 1558 1559module_init(nf_conntrack_sip_init); 1560module_exit(nf_conntrack_sip_fini); 1561