net/netfilter/nf_conntrack_sip.c

   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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/module.h>
  16 #include <linux/ctype.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/inet.h>
  19 #include <linux/in.h>
  20 #include <linux/udp.h>
  21 #include <linux/tcp.h>
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter_ipv4.h>
  24 #include <linux/netfilter_ipv6.h>
  25
  26 #include <net/netfilter/nf_conntrack.h>
  27 #include <net/netfilter/nf_conntrack_core.h>
  28 #include <net/netfilter/nf_conntrack_expect.h>
  29 #include <net/netfilter/nf_conntrack_helper.h>
  30 #include <net/netfilter/nf_conntrack_zones.h>
  31 #include <linux/netfilter/nf_conntrack_sip.h>
  32
  33 MODULE_LICENSE("GPL");
  34 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
  35 MODULE_DESCRIPTION("SIP connection tracking helper");
  36 MODULE_ALIAS("ip_conntrack_sip");
  37 MODULE_ALIAS_NFCT_HELPER("sip");
  38
  39 #define MAX_PORTS       8
  40 static unsigned short ports[MAX_PORTS];
  41 static unsigned int ports_c;
  42 module_param_array(ports, ushort, &ports_c, 0400);
  43 MODULE_PARM_DESC(ports, "port numbers of SIP servers");
  44
  45 static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
  46 module_param(sip_timeout, uint, 0600);
  47 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
  48
  49 static int sip_direct_signalling __read_mostly = 1;
  50 module_param(sip_direct_signalling, int, 0600);
  51 MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
  52                                         "only (default 1)");
  53
  54 static int sip_direct_media __read_mostly = 1;
  55 module_param(sip_direct_media, int, 0600);
  56 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
  57                                    "endpoints only (default 1)");
  58
  59 static int sip_external_media __read_mostly = 0;
  60 module_param(sip_external_media, int, 0600);
  61 MODULE_PARM_DESC(sip_external_media, "Expect Media streams between external "
  62                                      "endpoints (default 0)");
  63
  64 const struct nf_nat_sip_hooks *nf_nat_sip_hooks;
  65 EXPORT_SYMBOL_GPL(nf_nat_sip_hooks);
  66
  67 static int string_len(const struct nf_conn *ct, const char *dptr,
  68                       const char *limit, int *shift)
  69 {
  70         int len = 0;
  71
  72         while (dptr < limit && isalpha(*dptr)) {
  73                 dptr++;
  74                 len++;
  75         }
  76         return len;
  77 }
  78
  79 static int digits_len(const struct nf_conn *ct, const char *dptr,
  80                       const char *limit, int *shift)
  81 {
  82         int len = 0;
  83         while (dptr < limit && isdigit(*dptr)) {
  84                 dptr++;
  85                 len++;
  86         }
  87         return len;
  88 }
  89
  90 static int iswordc(const char c)
  91 {
  92         if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
  93             (c >= '(' && c <= '+') || c == ':' || c == '<' || c == '>' ||
  94             c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
  95             c == '{' || c == '}' || c == '~' || (c >= '-' && c <= '/') ||
  96             c == '\'')
  97                 return 1;
  98         return 0;
  99 }
 100
 101 static int word_len(const char *dptr, const char *limit)
 102 {
 103         int len = 0;
 104         while (dptr < limit && iswordc(*dptr)) {
 105                 dptr++;
 106                 len++;
 107         }
 108         return len;
 109 }
 110
 111 static int callid_len(const struct nf_conn *ct, const char *dptr,
 112                       const char *limit, int *shift)
 113 {
 114         int len, domain_len;
 115
 116         len = word_len(dptr, limit);
 117         dptr += len;
 118         if (!len || dptr == limit || *dptr != '@')
 119                 return len;
 120         dptr++;
 121         len++;
 122
 123         domain_len = word_len(dptr, limit);
 124         if (!domain_len)
 125                 return 0;
 126         return len + domain_len;
 127 }
 128
 129 /* get media type + port length */
 130 static int media_len(const struct nf_conn *ct, const char *dptr,
 131                      const char *limit, int *shift)
 132 {
 133         int len = string_len(ct, dptr, limit, shift);
 134
 135         dptr += len;
 136         if (dptr >= limit || *dptr != ' ')
 137                 return 0;
 138         len++;
 139         dptr++;
 140
 141         return len + digits_len(ct, dptr, limit, shift);
 142 }
 143
 144 static int sip_parse_addr(const struct nf_conn *ct, const char *cp,
 145                           const char **endp, union nf_inet_addr *addr,
 146                           const char *limit, bool delim)
 147 {
 148         const char *end;
 149         int ret;
 150
 151         if (!ct)
 152                 return 0;
 153
 154         memset(addr, 0, sizeof(*addr));
 155         switch (nf_ct_l3num(ct)) {
 156         case AF_INET:
 157                 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
 158                 if (ret == 0)
 159                         return 0;
 160                 break;
 161         case AF_INET6:
 162                 if (cp < limit && *cp == '[')
 163                         cp++;
 164                 else if (delim)
 165                         return 0;
 166
 167                 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
 168                 if (ret == 0)
 169                         return 0;
 170
 171                 if (end < limit && *end == ']')
 172                         end++;
 173                 else if (delim)
 174                         return 0;
 175                 break;
 176         default:
 177                 BUG();
 178         }
 179
 180         if (endp)
 181                 *endp = end;
 182         return 1;
 183 }
 184
 185 /* skip ip address. returns its length. */
 186 static int epaddr_len(const struct nf_conn *ct, const char *dptr,
 187                       const char *limit, int *shift)
 188 {
 189         union nf_inet_addr addr;
 190         const char *aux = dptr;
 191
 192         if (!sip_parse_addr(ct, dptr, &dptr, &addr, limit, true)) {
 193                 pr_debug("ip: %s parse failed.!\n", dptr);
 194                 return 0;
 195         }
 196
 197         /* Port number */
 198         if (*dptr == ':') {
 199                 dptr++;
 200                 dptr += digits_len(ct, dptr, limit, shift);
 201         }
 202         return dptr - aux;
 203 }
 204
 205 /* get address length, skiping user info. */
 206 static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr,
 207                           const char *limit, int *shift)
 208 {
 209         const char *start = dptr;
 210         int s = *shift;
 211
 212         /* Search for @, but stop at the end of the line.
 213          * We are inside a sip: URI, so we don't need to worry about
 214          * continuation lines. */
 215         while (dptr < limit &&
 216                *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
 217                 (*shift)++;
 218                 dptr++;
 219         }
 220
 221         if (dptr < limit && *dptr == '@') {
 222                 dptr++;
 223                 (*shift)++;
 224         } else {
 225                 dptr = start;
 226                 *shift = s;
 227         }
 228
 229         return epaddr_len(ct, dptr, limit, shift);
 230 }
 231
 232 /* Parse a SIP request line of the form:
 233  *
 234  * Request-Line = Method SP Request-URI SP SIP-Version CRLF
 235  *
 236  * and return the offset and length of the address contained in the Request-URI.
 237  */
 238 int ct_sip_parse_request(const struct nf_conn *ct,
 239                          const char *dptr, unsigned int datalen,
 240                          unsigned int *matchoff, unsigned int *matchlen,
 241                          union nf_inet_addr *addr, __be16 *port)
 242 {
 243         const char *start = dptr, *limit = dptr + datalen, *end;
 244         unsigned int mlen;
 245         unsigned int p;
 246         int shift = 0;
 247
 248         /* Skip method and following whitespace */
 249         mlen = string_len(ct, dptr, limit, NULL);
 250         if (!mlen)
 251                 return 0;
 252         dptr += mlen;
 253         if (++dptr >= limit)
 254                 return 0;
 255
 256         /* Find SIP URI */
 257         for (; dptr < limit - strlen("sip:"); dptr++) {
 258                 if (*dptr == '\r' || *dptr == '\n')
 259                         return -1;
 260                 if (strncasecmp(dptr, "sip:", strlen("sip:")) == 0) {
 261                         dptr += strlen("sip:");
 262                         break;
 263                 }
 264         }
 265         if (!skp_epaddr_len(ct, dptr, limit, &shift))
 266                 return 0;
 267         dptr += shift;
 268
 269         if (!sip_parse_addr(ct, dptr, &end, addr, limit, true))
 270                 return -1;
 271         if (end < limit && *end == ':') {
 272                 end++;
 273                 p = simple_strtoul(end, (char **)&end, 10);
 274                 if (p < 1024 || p > 65535)
 275                         return -1;
 276                 *port = htons(p);
 277         } else
 278                 *port = htons(SIP_PORT);
 279
 280         if (end == dptr)
 281                 return 0;
 282         *matchoff = dptr - start;
 283         *matchlen = end - dptr;
 284         return 1;
 285 }
 286 EXPORT_SYMBOL_GPL(ct_sip_parse_request);
 287
 288 /* SIP header parsing: SIP headers are located at the beginning of a line, but
 289  * may span several lines, in which case the continuation lines begin with a
 290  * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
 291  * CRLF, RFC 3261 allows only CRLF, we support both.
 292  *
 293  * Headers are followed by (optionally) whitespace, a colon, again (optionally)
 294  * whitespace and the values. Whitespace in this context means any amount of
 295  * tabs, spaces and continuation lines, which are treated as a single whitespace
 296  * character.
 297  *
 298  * Some headers may appear multiple times. A comma separated list of values is
 299  * equivalent to multiple headers.
 300  */
 301 static const struct sip_header ct_sip_hdrs[] = {
 302         [SIP_HDR_CSEQ]                  = SIP_HDR("CSeq", NULL, NULL, digits_len),
 303         [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
 304         [SIP_HDR_TO]                    = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
 305         [SIP_HDR_CONTACT]               = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
 306         [SIP_HDR_VIA_UDP]               = SIP_HDR("Via", "v", "UDP ", epaddr_len),
 307         [SIP_HDR_VIA_TCP]               = SIP_HDR("Via", "v", "TCP ", epaddr_len),
 308         [SIP_HDR_EXPIRES]               = SIP_HDR("Expires", NULL, NULL, digits_len),
 309         [SIP_HDR_CONTENT_LENGTH]        = SIP_HDR("Content-Length", "l", NULL, digits_len),
 310         [SIP_HDR_CALL_ID]               = SIP_HDR("Call-Id", "i", NULL, callid_len),
 311 };
 312
 313 static const char *sip_follow_continuation(const char *dptr, const char *limit)
 314 {
 315         /* Walk past newline */
 316         if (++dptr >= limit)
 317                 return NULL;
 318
 319         /* Skip '\n' in CR LF */
 320         if (*(dptr - 1) == '\r' && *dptr == '\n') {
 321                 if (++dptr >= limit)
 322                         return NULL;
 323         }
 324
 325         /* Continuation line? */
 326         if (*dptr != ' ' && *dptr != '\t')
 327                 return NULL;
 328
 329         /* skip leading whitespace */
 330         for (; dptr < limit; dptr++) {
 331                 if (*dptr != ' ' && *dptr != '\t')
 332                         break;
 333         }
 334         return dptr;
 335 }
 336
 337 static const char *sip_skip_whitespace(const char *dptr, const char *limit)
 338 {
 339         for (; dptr < limit; dptr++) {
 340                 if (*dptr == ' ' || *dptr == '\t')
 341                         continue;
 342                 if (*dptr != '\r' && *dptr != '\n')
 343                         break;
 344                 dptr = sip_follow_continuation(dptr, limit);
 345                 break;
 346         }
 347         return dptr;
 348 }
 349
 350 /* Search within a SIP header value, dealing with continuation lines */
 351 static const char *ct_sip_header_search(const char *dptr, const char *limit,
 352                                         const char *needle, unsigned int len)
 353 {
 354         for (limit -= len; dptr < limit; dptr++) {
 355                 if (*dptr == '\r' || *dptr == '\n') {
 356                         dptr = sip_follow_continuation(dptr, limit);
 357                         if (dptr == NULL)
 358                                 break;
 359                         continue;
 360                 }
 361
 362                 if (strncasecmp(dptr, needle, len) == 0)
 363                         return dptr;
 364         }
 365         return NULL;
 366 }
 367
 368 int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
 369                       unsigned int dataoff, unsigned int datalen,
 370                       enum sip_header_types type,
 371                       unsigned int *matchoff, unsigned int *matchlen)
 372 {
 373         const struct sip_header *hdr = &ct_sip_hdrs[type];
 374         const char *start = dptr, *limit = dptr + datalen;
 375         int shift = 0;
 376
 377         for (dptr += dataoff; dptr < limit; dptr++) {
 378                 /* Find beginning of line */
 379                 if (*dptr != '\r' && *dptr != '\n')
 380                         continue;
 381                 if (++dptr >= limit)
 382                         break;
 383                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
 384                         if (++dptr >= limit)
 385                                 break;
 386                 }
 387
 388                 /* Skip continuation lines */
 389                 if (*dptr == ' ' || *dptr == '\t')
 390                         continue;
 391
 392                 /* Find header. Compact headers must be followed by a
 393                  * non-alphabetic character to avoid mismatches. */
 394                 if (limit - dptr >= hdr->len &&
 395                     strncasecmp(dptr, hdr->name, hdr->len) == 0)
 396                         dptr += hdr->len;
 397                 else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
 398                          strncasecmp(dptr, hdr->cname, hdr->clen) == 0 &&
 399                          !isalpha(*(dptr + hdr->clen)))
 400                         dptr += hdr->clen;
 401                 else
 402                         continue;
 403
 404                 /* Find and skip colon */
 405                 dptr = sip_skip_whitespace(dptr, limit);
 406                 if (dptr == NULL)
 407                         break;
 408                 if (*dptr != ':' || ++dptr >= limit)
 409                         break;
 410
 411                 /* Skip whitespace after colon */
 412                 dptr = sip_skip_whitespace(dptr, limit);
 413                 if (dptr == NULL)
 414                         break;
 415
 416                 *matchoff = dptr - start;
 417                 if (hdr->search) {
 418                         dptr = ct_sip_header_search(dptr, limit, hdr->search,
 419                                                     hdr->slen);
 420                         if (!dptr)
 421                                 return -1;
 422                         dptr += hdr->slen;
 423                 }
 424
 425                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 426                 if (!*matchlen)
 427                         return -1;
 428                 *matchoff = dptr - start + shift;
 429                 return 1;
 430         }
 431         return 0;
 432 }
 433 EXPORT_SYMBOL_GPL(ct_sip_get_header);
 434
 435 /* Get next header field in a list of comma separated values */
 436 static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
 437                               unsigned int dataoff, unsigned int datalen,
 438                               enum sip_header_types type,
 439                               unsigned int *matchoff, unsigned int *matchlen)
 440 {
 441         const struct sip_header *hdr = &ct_sip_hdrs[type];
 442         const char *start = dptr, *limit = dptr + datalen;
 443         int shift = 0;
 444
 445         dptr += dataoff;
 446
 447         dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
 448         if (!dptr)
 449                 return 0;
 450
 451         dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
 452         if (!dptr)
 453                 return 0;
 454         dptr += hdr->slen;
 455
 456         *matchoff = dptr - start;
 457         *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 458         if (!*matchlen)
 459                 return -1;
 460         *matchoff += shift;
 461         return 1;
 462 }
 463
 464 /* Walk through headers until a parsable one is found or no header of the
 465  * given type is left. */
 466 static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
 467                                unsigned int dataoff, unsigned int datalen,
 468                                enum sip_header_types type, int *in_header,
 469                                unsigned int *matchoff, unsigned int *matchlen)
 470 {
 471         int ret;
 472
 473         if (in_header && *in_header) {
 474                 while (1) {
 475                         ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
 476                                                  type, matchoff, matchlen);
 477                         if (ret > 0)
 478                                 return ret;
 479                         if (ret == 0)
 480                                 break;
 481                         dataoff += *matchoff;
 482                 }
 483                 *in_header = 0;
 484         }
 485
 486         while (1) {
 487                 ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
 488                                         type, matchoff, matchlen);
 489                 if (ret > 0)
 490                         break;
 491                 if (ret == 0)
 492                         return ret;
 493                 dataoff += *matchoff;
 494         }
 495
 496         if (in_header)
 497                 *in_header = 1;
 498         return 1;
 499 }
 500
 501 /* Locate a SIP header, parse the URI and return the offset and length of
 502  * the address as well as the address and port themselves. A stream of
 503  * headers can be parsed by handing in a non-NULL datalen and in_header
 504  * pointer.
 505  */
 506 int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
 507                             unsigned int *dataoff, unsigned int datalen,
 508                             enum sip_header_types type, int *in_header,
 509                             unsigned int *matchoff, unsigned int *matchlen,
 510                             union nf_inet_addr *addr, __be16 *port)
 511 {
 512         const char *c, *limit = dptr + datalen;
 513         unsigned int p;
 514         int ret;
 515
 516         ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
 517                                   type, in_header, matchoff, matchlen);
 518         WARN_ON(ret < 0);
 519         if (ret == 0)
 520                 return ret;
 521
 522         if (!sip_parse_addr(ct, dptr + *matchoff, &c, addr, limit, true))
 523                 return -1;
 524         if (*c == ':') {
 525                 c++;
 526                 p = simple_strtoul(c, (char **)&c, 10);
 527                 if (p < 1024 || p > 65535)
 528                         return -1;
 529                 *port = htons(p);
 530         } else
 531                 *port = htons(SIP_PORT);
 532
 533         if (dataoff)
 534                 *dataoff = c - dptr;
 535         return 1;
 536 }
 537 EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
 538
 539 static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
 540                               unsigned int dataoff, unsigned int datalen,
 541                               const char *name,
 542                               unsigned int *matchoff, unsigned int *matchlen)
 543 {
 544         const char *limit = dptr + datalen;
 545         const char *start;
 546         const char *end;
 547
 548         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
 549         if (!limit)
 550                 limit = dptr + datalen;
 551
 552         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
 553         if (!start)
 554                 return 0;
 555         start += strlen(name);
 556
 557         end = ct_sip_header_search(start, limit, ";", strlen(";"));
 558         if (!end)
 559                 end = limit;
 560
 561         *matchoff = start - dptr;
 562         *matchlen = end - start;
 563         return 1;
 564 }
 565
 566 /* Parse address from header parameter and return address, offset and length */
 567 int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
 568                                unsigned int dataoff, unsigned int datalen,
 569                                const char *name,
 570                                unsigned int *matchoff, unsigned int *matchlen,
 571                                union nf_inet_addr *addr, bool delim)
 572 {
 573         const char *limit = dptr + datalen;
 574         const char *start, *end;
 575
 576         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
 577         if (!limit)
 578                 limit = dptr + datalen;
 579
 580         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
 581         if (!start)
 582                 return 0;
 583
 584         start += strlen(name);
 585         if (!sip_parse_addr(ct, start, &end, addr, limit, delim))
 586                 return 0;
 587         *matchoff = start - dptr;
 588         *matchlen = end - start;
 589         return 1;
 590 }
 591 EXPORT_SYMBOL_GPL(ct_sip_parse_address_param);
 592
 593 /* Parse numerical header parameter and return value, offset and length */
 594 int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
 595                                  unsigned int dataoff, unsigned int datalen,
 596                                  const char *name,
 597                                  unsigned int *matchoff, unsigned int *matchlen,
 598                                  unsigned int *val)
 599 {
 600         const char *limit = dptr + datalen;
 601         const char *start;
 602         char *end;
 603
 604         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
 605         if (!limit)
 606                 limit = dptr + datalen;
 607
 608         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
 609         if (!start)
 610                 return 0;
 611
 612         start += strlen(name);
 613         *val = simple_strtoul(start, &end, 0);
 614         if (start == end)
 615                 return 0;
 616         if (matchoff && matchlen) {
 617                 *matchoff = start - dptr;
 618                 *matchlen = end - start;
 619         }
 620         return 1;
 621 }
 622 EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
 623
 624 static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
 625                                   unsigned int dataoff, unsigned int datalen,
 626                                   u8 *proto)
 627 {
 628         unsigned int matchoff, matchlen;
 629
 630         if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
 631                                &matchoff, &matchlen)) {
 632                 if (!strncasecmp(dptr + matchoff, "TCP", strlen("TCP")))
 633                         *proto = IPPROTO_TCP;
 634                 else if (!strncasecmp(dptr + matchoff, "UDP", strlen("UDP")))
 635                         *proto = IPPROTO_UDP;
 636                 else
 637                         return 0;
 638
 639                 if (*proto != nf_ct_protonum(ct))
 640                         return 0;
 641         } else
 642                 *proto = nf_ct_protonum(ct);
 643
 644         return 1;
 645 }
 646
 647 static int sdp_parse_addr(const struct nf_conn *ct, const char *cp,
 648                           const char **endp, union nf_inet_addr *addr,
 649                           const char *limit)
 650 {
 651         const char *end;
 652         int ret;
 653
 654         memset(addr, 0, sizeof(*addr));
 655         switch (nf_ct_l3num(ct)) {
 656         case AF_INET:
 657                 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
 658                 break;
 659         case AF_INET6:
 660                 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
 661                 break;
 662         default:
 663                 BUG();
 664         }
 665
 666         if (ret == 0)
 667                 return 0;
 668         if (endp)
 669                 *endp = end;
 670         return 1;
 671 }
 672
 673 /* skip ip address. returns its length. */
 674 static int sdp_addr_len(const struct nf_conn *ct, const char *dptr,
 675                         const char *limit, int *shift)
 676 {
 677         union nf_inet_addr addr;
 678         const char *aux = dptr;
 679
 680         if (!sdp_parse_addr(ct, dptr, &dptr, &addr, limit)) {
 681                 pr_debug("ip: %s parse failed.!\n", dptr);
 682                 return 0;
 683         }
 684
 685         return dptr - aux;
 686 }
 687
 688 /* SDP header parsing: a SDP session description contains an ordered set of
 689  * headers, starting with a section containing general session parameters,
 690  * optionally followed by multiple media descriptions.
 691  *
 692  * SDP headers always start at the beginning of a line. According to RFC 2327:
 693  * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
 694  * be tolerant and also accept records terminated with a single newline
 695  * character". We handle both cases.
 696  */
 697 static const struct sip_header ct_sdp_hdrs_v4[] = {
 698         [SDP_HDR_VERSION]       = SDP_HDR("v=", NULL, digits_len),
 699         [SDP_HDR_OWNER]         = SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
 700         [SDP_HDR_CONNECTION]    = SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
 701         [SDP_HDR_MEDIA]         = SDP_HDR("m=", NULL, media_len),
 702 };
 703
 704 static const struct sip_header ct_sdp_hdrs_v6[] = {
 705         [SDP_HDR_VERSION]       = SDP_HDR("v=", NULL, digits_len),
 706         [SDP_HDR_OWNER]         = SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
 707         [SDP_HDR_CONNECTION]    = SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
 708         [SDP_HDR_MEDIA]         = SDP_HDR("m=", NULL, media_len),
 709 };
 710
 711 /* Linear string search within SDP header values */
 712 static const char *ct_sdp_header_search(const char *dptr, const char *limit,
 713                                         const char *needle, unsigned int len)
 714 {
 715         for (limit -= len; dptr < limit; dptr++) {
 716                 if (*dptr == '\r' || *dptr == '\n')
 717                         break;
 718                 if (strncmp(dptr, needle, len) == 0)
 719                         return dptr;
 720         }
 721         return NULL;
 722 }
 723
 724 /* Locate a SDP header (optionally a substring within the header value),
 725  * optionally stopping at the first occurrence of the term header, parse
 726  * it and return the offset and length of the data we're interested in.
 727  */
 728 int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
 729                           unsigned int dataoff, unsigned int datalen,
 730                           enum sdp_header_types type,
 731                           enum sdp_header_types term,
 732                           unsigned int *matchoff, unsigned int *matchlen)
 733 {
 734         const struct sip_header *hdrs, *hdr, *thdr;
 735         const char *start = dptr, *limit = dptr + datalen;
 736         int shift = 0;
 737
 738         hdrs = nf_ct_l3num(ct) == NFPROTO_IPV4 ? ct_sdp_hdrs_v4 : ct_sdp_hdrs_v6;
 739         hdr = &hdrs[type];
 740         thdr = &hdrs[term];
 741
 742         for (dptr += dataoff; dptr < limit; dptr++) {
 743                 /* Find beginning of line */
 744                 if (*dptr != '\r' && *dptr != '\n')
 745                         continue;
 746                 if (++dptr >= limit)
 747                         break;
 748                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
 749                         if (++dptr >= limit)
 750                                 break;
 751                 }
 752
 753                 if (term != SDP_HDR_UNSPEC &&
 754                     limit - dptr >= thdr->len &&
 755                     strncasecmp(dptr, thdr->name, thdr->len) == 0)
 756                         break;
 757                 else if (limit - dptr >= hdr->len &&
 758                          strncasecmp(dptr, hdr->name, hdr->len) == 0)
 759                         dptr += hdr->len;
 760                 else
 761                         continue;
 762
 763                 *matchoff = dptr - start;
 764                 if (hdr->search) {
 765                         dptr = ct_sdp_header_search(dptr, limit, hdr->search,
 766                                                     hdr->slen);
 767                         if (!dptr)
 768                                 return -1;
 769                         dptr += hdr->slen;
 770                 }
 771
 772                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
 773                 if (!*matchlen)
 774                         return -1;
 775                 *matchoff = dptr - start + shift;
 776                 return 1;
 777         }
 778         return 0;
 779 }
 780 EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
 781
 782 static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
 783                                  unsigned int dataoff, unsigned int datalen,
 784                                  enum sdp_header_types type,
 785                                  enum sdp_header_types term,
 786                                  unsigned int *matchoff, unsigned int *matchlen,
 787                                  union nf_inet_addr *addr)
 788 {
 789         int ret;
 790
 791         ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
 792                                     matchoff, matchlen);
 793         if (ret <= 0)
 794                 return ret;
 795
 796         if (!sdp_parse_addr(ct, dptr + *matchoff, NULL, addr,
 797                             dptr + *matchoff + *matchlen))
 798                 return -1;
 799         return 1;
 800 }
 801
 802 static int refresh_signalling_expectation(struct nf_conn *ct,
 803                                           union nf_inet_addr *addr,
 804                                           u8 proto, __be16 port,
 805                                           unsigned int expires)
 806 {
 807         struct nf_conn_help *help = nfct_help(ct);
 808         struct nf_conntrack_expect *exp;
 809         struct hlist_node *next;
 810         int found = 0;
 811
 812         spin_lock_bh(&nf_conntrack_expect_lock);
 813         hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
 814                 if (exp->class != SIP_EXPECT_SIGNALLING ||
 815                     !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
 816                     exp->tuple.dst.protonum != proto ||
 817                     exp->tuple.dst.u.udp.port != port)
 818                         continue;
 819                 if (mod_timer_pending(&exp->timeout, jiffies + expires * HZ)) {
 820                         exp->flags &= ~NF_CT_EXPECT_INACTIVE;
 821                         found = 1;
 822                         break;
 823                 }
 824         }
 825         spin_unlock_bh(&nf_conntrack_expect_lock);
 826         return found;
 827 }
 828
 829 static void flush_expectations(struct nf_conn *ct, bool media)
 830 {
 831         struct nf_conn_help *help = nfct_help(ct);
 832         struct nf_conntrack_expect *exp;
 833         struct hlist_node *next;
 834
 835         spin_lock_bh(&nf_conntrack_expect_lock);
 836         hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
 837                 if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
 838                         continue;
 839                 if (!nf_ct_remove_expect(exp))
 840                         continue;
 841                 if (!media)
 842                         break;
 843         }
 844         spin_unlock_bh(&nf_conntrack_expect_lock);
 845 }
 846
 847 static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
 848                                  unsigned int dataoff,
 849                                  const char **dptr, unsigned int *datalen,
 850                                  union nf_inet_addr *daddr, __be16 port,
 851                                  enum sip_expectation_classes class,
 852                                  unsigned int mediaoff, unsigned int medialen)
 853 {
 854         struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
 855         enum ip_conntrack_info ctinfo;
 856         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 857         struct net *net = nf_ct_net(ct);
 858         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 859         union nf_inet_addr *saddr;
 860         struct nf_conntrack_tuple tuple;
 861         int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
 862         u_int16_t base_port;
 863         __be16 rtp_port, rtcp_port;
 864         const struct nf_nat_sip_hooks *hooks;
 865
 866         saddr = NULL;
 867         if (sip_direct_media) {
 868                 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
 869                         return NF_ACCEPT;
 870                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
 871         } else if (sip_external_media) {
 872                 struct net_device *dev = skb_dst(skb)->dev;
 873                 struct net *net = dev_net(dev);
 874                 struct flowi fl;
 875                 struct dst_entry *dst = NULL;
 876
 877                 memset(&fl, 0, sizeof(fl));
 878
 879                 switch (nf_ct_l3num(ct)) {
 880                         case NFPROTO_IPV4:
 881                                 fl.u.ip4.daddr = daddr->ip;
 882                                 nf_ip_route(net, &dst, &fl, false);
 883                                 break;
 884
 885                         case NFPROTO_IPV6:
 886                                 fl.u.ip6.daddr = daddr->in6;
 887                                 nf_ip6_route(net, &dst, &fl, false);
 888                                 break;
 889                 }
 890
 891                 /* Don't predict any conntracks when media endpoint is reachable
 892                  * through the same interface as the signalling peer.
 893                  */
 894                 if (dst) {
 895                         bool external_media = (dst->dev == dev);
 896
 897                         dst_release(dst);
 898                         if (external_media)
 899                                 return NF_ACCEPT;
 900                 }
 901         }
 902
 903         /* We need to check whether the registration exists before attempting
 904          * to register it since we can see the same media description multiple
 905          * times on different connections in case multiple endpoints receive
 906          * the same call.
 907          *
 908          * RTP optimization: if we find a matching media channel expectation
 909          * and both the expectation and this connection are SNATed, we assume
 910          * both sides can reach each other directly and use the final
 911          * destination address from the expectation. We still need to keep
 912          * the NATed expectations for media that might arrive from the
 913          * outside, and additionally need to expect the direct RTP stream
 914          * in case it passes through us even without NAT.
 915          */
 916         memset(&tuple, 0, sizeof(tuple));
 917         if (saddr)
 918                 tuple.src.u3 = *saddr;
 919         tuple.src.l3num         = nf_ct_l3num(ct);
 920         tuple.dst.protonum      = IPPROTO_UDP;
 921         tuple.dst.u3            = *daddr;
 922         tuple.dst.u.udp.port    = port;
 923
 924         do {
 925                 exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
 926
 927                 if (!exp || exp->master == ct ||
 928                     nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
 929                     exp->class != class)
 930                         break;
 931 #ifdef CONFIG_NF_NAT_NEEDED
 932                 if (!direct_rtp &&
 933                     (!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
 934                      exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
 935                     ct->status & IPS_NAT_MASK) {
 936                         *daddr                  = exp->saved_addr;
 937                         tuple.dst.u3            = exp->saved_addr;
 938                         tuple.dst.u.udp.port    = exp->saved_proto.udp.port;
 939                         direct_rtp = 1;
 940                 } else
 941 #endif
 942                         skip_expect = 1;
 943         } while (!skip_expect);
 944
 945         base_port = ntohs(tuple.dst.u.udp.port) & ~1;
 946         rtp_port = htons(base_port);
 947         rtcp_port = htons(base_port + 1);
 948
 949         if (direct_rtp) {
 950                 hooks = rcu_dereference(nf_nat_sip_hooks);
 951                 if (hooks &&
 952                     !hooks->sdp_port(skb, protoff, dataoff, dptr, datalen,
 953                                      mediaoff, medialen, ntohs(rtp_port)))
 954                         goto err1;
 955         }
 956
 957         if (skip_expect)
 958                 return NF_ACCEPT;
 959
 960         rtp_exp = nf_ct_expect_alloc(ct);
 961         if (rtp_exp == NULL)
 962                 goto err1;
 963         nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 964                           IPPROTO_UDP, NULL, &rtp_port);
 965
 966         rtcp_exp = nf_ct_expect_alloc(ct);
 967         if (rtcp_exp == NULL)
 968                 goto err2;
 969         nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 970                           IPPROTO_UDP, NULL, &rtcp_port);
 971
 972         hooks = rcu_dereference(nf_nat_sip_hooks);
 973         if (hooks && ct->status & IPS_NAT_MASK && !direct_rtp)
 974                 ret = hooks->sdp_media(skb, protoff, dataoff, dptr,
 975                                        datalen, rtp_exp, rtcp_exp,
 976                                        mediaoff, medialen, daddr);
 977         else {
 978                 /* -EALREADY handling works around end-points that send
 979                  * SDP messages with identical port but different media type,
 980                  * we pretend expectation was set up.
 981                  */
 982                 int errp = nf_ct_expect_related(rtp_exp);
 983
 984                 if (errp == 0 || errp == -EALREADY) {
 985                         int errcp = nf_ct_expect_related(rtcp_exp);
 986
 987                         if (errcp == 0 || errcp == -EALREADY)
 988                                 ret = NF_ACCEPT;
 989                         else if (errp == 0)
 990                                 nf_ct_unexpect_related(rtp_exp);
 991                 }
 992         }
 993         nf_ct_expect_put(rtcp_exp);
 994 err2:
 995         nf_ct_expect_put(rtp_exp);
 996 err1:
 997         return ret;
 998 }
 999
1000 static const struct sdp_media_type sdp_media_types[] = {
1001         SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
1002         SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
1003         SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE),
1004 };
1005
1006 static const struct sdp_media_type *sdp_media_type(const char *dptr,
1007                                                    unsigned int matchoff,
1008                                                    unsigned int matchlen)
1009 {
1010         const struct sdp_media_type *t;
1011         unsigned int i;
1012
1013         for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
1014                 t = &sdp_media_types[i];
1015                 if (matchlen < t->len ||
1016                     strncmp(dptr + matchoff, t->name, t->len))
1017                         continue;
1018                 return t;
1019         }
1020         return NULL;
1021 }
1022
1023 static int process_sdp(struct sk_buff *skb, unsigned int protoff,
1024                        unsigned int dataoff,
1025                        const char **dptr, unsigned int *datalen,
1026                        unsigned int cseq)
1027 {
1028         enum ip_conntrack_info ctinfo;
1029         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1030         unsigned int matchoff, matchlen;
1031         unsigned int mediaoff, medialen;
1032         unsigned int sdpoff;
1033         unsigned int caddr_len, maddr_len;
1034         unsigned int i;
1035         union nf_inet_addr caddr, maddr, rtp_addr;
1036         const struct nf_nat_sip_hooks *hooks;
1037         unsigned int port;
1038         const struct sdp_media_type *t;
1039         int ret = NF_ACCEPT;
1040
1041         hooks = rcu_dereference(nf_nat_sip_hooks);
1042
1043         /* Find beginning of session description */
1044         if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
1045                                   SDP_HDR_VERSION, SDP_HDR_UNSPEC,
1046                                   &matchoff, &matchlen) <= 0)
1047                 return NF_ACCEPT;
1048         sdpoff = matchoff;
1049
1050         /* The connection information is contained in the session description
1051          * and/or once per media description. The first media description marks
1052          * the end of the session description. */
1053         caddr_len = 0;
1054         if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
1055                                   SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1056                                   &matchoff, &matchlen, &caddr) > 0)
1057                 caddr_len = matchlen;
1058
1059         mediaoff = sdpoff;
1060         for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
1061                 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
1062                                           SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
1063                                           &mediaoff, &medialen) <= 0)
1064                         break;
1065
1066                 /* Get media type and port number. A media port value of zero
1067                  * indicates an inactive stream. */
1068                 t = sdp_media_type(*dptr, mediaoff, medialen);
1069                 if (!t) {
1070                         mediaoff += medialen;
1071                         continue;
1072                 }
1073                 mediaoff += t->len;
1074                 medialen -= t->len;
1075
1076                 port = simple_strtoul(*dptr + mediaoff, NULL, 10);
1077                 if (port == 0)
1078                         continue;
1079                 if (port < 1024 || port > 65535) {
1080                         nf_ct_helper_log(skb, ct, "wrong port %u", port);
1081                         return NF_DROP;
1082                 }
1083
1084                 /* The media description overrides the session description. */
1085                 maddr_len = 0;
1086                 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
1087                                           SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1088                                           &matchoff, &matchlen, &maddr) > 0) {
1089                         maddr_len = matchlen;
1090                         memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
1091                 } else if (caddr_len)
1092                         memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
1093                 else {
1094                         nf_ct_helper_log(skb, ct, "cannot parse SDP message");
1095                         return NF_DROP;
1096                 }
1097
1098                 ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
1099                                             dptr, datalen,
1100                                             &rtp_addr, htons(port), t->class,
1101                                             mediaoff, medialen);
1102                 if (ret != NF_ACCEPT) {
1103                         nf_ct_helper_log(skb, ct,
1104                                          "cannot add expectation for voice");
1105                         return ret;
1106                 }
1107
1108                 /* Update media connection address if present */
1109                 if (maddr_len && hooks && ct->status & IPS_NAT_MASK) {
1110                         ret = hooks->sdp_addr(skb, protoff, dataoff,
1111                                               dptr, datalen, mediaoff,
1112                                               SDP_HDR_CONNECTION,
1113                                               SDP_HDR_MEDIA,
1114                                               &rtp_addr);
1115                         if (ret != NF_ACCEPT) {
1116                                 nf_ct_helper_log(skb, ct, "cannot mangle SDP");
1117                                 return ret;
1118                         }
1119                 }
1120                 i++;
1121         }
1122
1123         /* Update session connection and owner addresses */
1124         hooks = rcu_dereference(nf_nat_sip_hooks);
1125         if (hooks && ct->status & IPS_NAT_MASK)
1126                 ret = hooks->sdp_session(skb, protoff, dataoff,
1127                                          dptr, datalen, sdpoff,
1128                                          &rtp_addr);
1129
1130         return ret;
1131 }
1132 static int process_invite_response(struct sk_buff *skb, unsigned int protoff,
1133                                    unsigned int dataoff,
1134                                    const char **dptr, unsigned int *datalen,
1135                                    unsigned int cseq, unsigned int code)
1136 {
1137         enum ip_conntrack_info ctinfo;
1138         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1139         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1140
1141         if ((code >= 100 && code <= 199) ||
1142             (code >= 200 && code <= 299))
1143                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1144         else if (ct_sip_info->invite_cseq == cseq)
1145                 flush_expectations(ct, true);
1146         return NF_ACCEPT;
1147 }
1148
1149 static int process_update_response(struct sk_buff *skb, unsigned int protoff,
1150                                    unsigned int dataoff,
1151                                    const char **dptr, unsigned int *datalen,
1152                                    unsigned int cseq, unsigned int code)
1153 {
1154         enum ip_conntrack_info ctinfo;
1155         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1156         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1157
1158         if ((code >= 100 && code <= 199) ||
1159             (code >= 200 && code <= 299))
1160                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1161         else if (ct_sip_info->invite_cseq == cseq)
1162                 flush_expectations(ct, true);
1163         return NF_ACCEPT;
1164 }
1165
1166 static int process_prack_response(struct sk_buff *skb, unsigned int protoff,
1167                                   unsigned int dataoff,
1168                                   const char **dptr, unsigned int *datalen,
1169                                   unsigned int cseq, unsigned int code)
1170 {
1171         enum ip_conntrack_info ctinfo;
1172         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1173         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1174
1175         if ((code >= 100 && code <= 199) ||
1176             (code >= 200 && code <= 299))
1177                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1178         else if (ct_sip_info->invite_cseq == cseq)
1179                 flush_expectations(ct, true);
1180         return NF_ACCEPT;
1181 }
1182
1183 static int process_invite_request(struct sk_buff *skb, unsigned int protoff,
1184                                   unsigned int dataoff,
1185                                   const char **dptr, unsigned int *datalen,
1186                                   unsigned int cseq)
1187 {
1188         enum ip_conntrack_info ctinfo;
1189         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1190         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1191         unsigned int ret;
1192
1193         flush_expectations(ct, true);
1194         ret = process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1195         if (ret == NF_ACCEPT)
1196                 ct_sip_info->invite_cseq = cseq;
1197         return ret;
1198 }
1199
1200 static int process_bye_request(struct sk_buff *skb, unsigned int protoff,
1201                                unsigned int dataoff,
1202                                const char **dptr, unsigned int *datalen,
1203                                unsigned int cseq)
1204 {
1205         enum ip_conntrack_info ctinfo;
1206         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1207
1208         flush_expectations(ct, true);
1209         return NF_ACCEPT;
1210 }
1211
1212 /* Parse a REGISTER request and create a permanent expectation for incoming
1213  * signalling connections. The expectation is marked inactive and is activated
1214  * when receiving a response indicating success from the registrar.
1215  */
1216 static int process_register_request(struct sk_buff *skb, unsigned int protoff,
1217                                     unsigned int dataoff,
1218                                     const char **dptr, unsigned int *datalen,
1219                                     unsigned int cseq)
1220 {
1221         enum ip_conntrack_info ctinfo;
1222         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1223         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1224         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1225         unsigned int matchoff, matchlen;
1226         struct nf_conntrack_expect *exp;
1227         union nf_inet_addr *saddr, daddr;
1228         const struct nf_nat_sip_hooks *hooks;
1229         __be16 port;
1230         u8 proto;
1231         unsigned int expires = 0;
1232         int ret;
1233
1234         /* Expected connections can not register again. */
1235         if (ct->status & IPS_EXPECTED)
1236                 return NF_ACCEPT;
1237
1238         /* We must check the expiration time: a value of zero signals the
1239          * registrar to release the binding. We'll remove our expectation
1240          * when receiving the new bindings in the response, but we don't
1241          * want to create new ones.
1242          *
1243          * The expiration time may be contained in Expires: header, the
1244          * Contact: header parameters or the URI parameters.
1245          */
1246         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1247                               &matchoff, &matchlen) > 0)
1248                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1249
1250         ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1251                                       SIP_HDR_CONTACT, NULL,
1252                                       &matchoff, &matchlen, &daddr, &port);
1253         if (ret < 0) {
1254                 nf_ct_helper_log(skb, ct, "cannot parse contact");
1255                 return NF_DROP;
1256         } else if (ret == 0)
1257                 return NF_ACCEPT;
1258
1259         /* We don't support third-party registrations */
1260         if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
1261                 return NF_ACCEPT;
1262
1263         if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
1264                                    &proto) == 0)
1265                 return NF_ACCEPT;
1266
1267         if (ct_sip_parse_numerical_param(ct, *dptr,
1268                                          matchoff + matchlen, *datalen,
1269                                          "expires=", NULL, NULL, &expires) < 0) {
1270                 nf_ct_helper_log(skb, ct, "cannot parse expires");
1271                 return NF_DROP;
1272         }
1273
1274         if (expires == 0) {
1275                 ret = NF_ACCEPT;
1276                 goto store_cseq;
1277         }
1278
1279         exp = nf_ct_expect_alloc(ct);
1280         if (!exp) {
1281                 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
1282                 return NF_DROP;
1283         }
1284
1285         saddr = NULL;
1286         if (sip_direct_signalling)
1287                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
1288
1289         nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
1290                           saddr, &daddr, proto, NULL, &port);
1291         exp->timeout.expires = sip_timeout * HZ;
1292         exp->helper = nfct_help(ct)->helper;
1293         exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
1294
1295         hooks = rcu_dereference(nf_nat_sip_hooks);
1296         if (hooks && ct->status & IPS_NAT_MASK)
1297                 ret = hooks->expect(skb, protoff, dataoff, dptr, datalen,
1298                                     exp, matchoff, matchlen);
1299         else {
1300                 if (nf_ct_expect_related(exp) != 0) {
1301                         nf_ct_helper_log(skb, ct, "cannot add expectation");
1302                         ret = NF_DROP;
1303                 } else
1304                         ret = NF_ACCEPT;
1305         }
1306         nf_ct_expect_put(exp);
1307
1308 store_cseq:
1309         if (ret == NF_ACCEPT)
1310                 ct_sip_info->register_cseq = cseq;
1311         return ret;
1312 }
1313
1314 static int process_register_response(struct sk_buff *skb, unsigned int protoff,
1315                                      unsigned int dataoff,
1316                                      const char **dptr, unsigned int *datalen,
1317                                      unsigned int cseq, unsigned int code)
1318 {
1319         enum ip_conntrack_info ctinfo;
1320         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1321         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1322         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1323         union nf_inet_addr addr;
1324         __be16 port;
1325         u8 proto;
1326         unsigned int matchoff, matchlen, coff = 0;
1327         unsigned int expires = 0;
1328         int in_contact = 0, ret;
1329
1330         /* According to RFC 3261, "UAs MUST NOT send a new registration until
1331          * they have received a final response from the registrar for the
1332          * previous one or the previous REGISTER request has timed out".
1333          *
1334          * However, some servers fail to detect retransmissions and send late
1335          * responses, so we store the sequence number of the last valid
1336          * request and compare it here.
1337          */
1338         if (ct_sip_info->register_cseq != cseq)
1339                 return NF_ACCEPT;
1340
1341         if (code >= 100 && code <= 199)
1342                 return NF_ACCEPT;
1343         if (code < 200 || code > 299)
1344                 goto flush;
1345
1346         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1347                               &matchoff, &matchlen) > 0)
1348                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1349
1350         while (1) {
1351                 unsigned int c_expires = expires;
1352
1353                 ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
1354                                               SIP_HDR_CONTACT, &in_contact,
1355                                               &matchoff, &matchlen,
1356                                               &addr, &port);
1357                 if (ret < 0) {
1358                         nf_ct_helper_log(skb, ct, "cannot parse contact");
1359                         return NF_DROP;
1360                 } else if (ret == 0)
1361                         break;
1362
1363                 /* We don't support third-party registrations */
1364                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
1365                         continue;
1366
1367                 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
1368                                            *datalen, &proto) == 0)
1369                         continue;
1370
1371                 ret = ct_sip_parse_numerical_param(ct, *dptr,
1372                                                    matchoff + matchlen,
1373                                                    *datalen, "expires=",
1374                                                    NULL, NULL, &c_expires);
1375                 if (ret < 0) {
1376                         nf_ct_helper_log(skb, ct, "cannot parse expires");
1377                         return NF_DROP;
1378                 }
1379                 if (c_expires == 0)
1380                         break;
1381                 if (refresh_signalling_expectation(ct, &addr, proto, port,
1382                                                    c_expires))
1383                         return NF_ACCEPT;
1384         }
1385
1386 flush:
1387         flush_expectations(ct, false);
1388         return NF_ACCEPT;
1389 }
1390
1391 static const struct sip_handler sip_handlers[] = {
1392         SIP_HANDLER("INVITE", process_invite_request, process_invite_response),
1393         SIP_HANDLER("UPDATE", process_sdp, process_update_response),
1394         SIP_HANDLER("ACK", process_sdp, NULL),
1395         SIP_HANDLER("PRACK", process_sdp, process_prack_response),
1396         SIP_HANDLER("BYE", process_bye_request, NULL),
1397         SIP_HANDLER("REGISTER", process_register_request, process_register_response),
1398 };
1399
1400 static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
1401                                 unsigned int dataoff,
1402                                 const char **dptr, unsigned int *datalen)
1403 {
1404         enum ip_conntrack_info ctinfo;
1405         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1406         unsigned int matchoff, matchlen, matchend;
1407         unsigned int code, cseq, i;
1408
1409         if (*datalen < strlen("SIP/2.0 200"))
1410                 return NF_ACCEPT;
1411         code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
1412         if (!code) {
1413                 nf_ct_helper_log(skb, ct, "cannot get code");
1414                 return NF_DROP;
1415         }
1416
1417         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1418                               &matchoff, &matchlen) <= 0) {
1419                 nf_ct_helper_log(skb, ct, "cannot parse cseq");
1420                 return NF_DROP;
1421         }
1422         cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1423         if (!cseq && *(*dptr + matchoff) != '0') {
1424                 nf_ct_helper_log(skb, ct, "cannot get cseq");
1425                 return NF_DROP;
1426         }
1427         matchend = matchoff + matchlen + 1;
1428
1429         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1430                 const struct sip_handler *handler;
1431
1432                 handler = &sip_handlers[i];
1433                 if (handler->response == NULL)
1434                         continue;
1435                 if (*datalen < matchend + handler->len ||
1436                     strncasecmp(*dptr + matchend, handler->method, handler->len))
1437                         continue;
1438                 return handler->response(skb, protoff, dataoff, dptr, datalen,
1439                                          cseq, code);
1440         }
1441         return NF_ACCEPT;
1442 }
1443
1444 static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
1445                                unsigned int dataoff,
1446                                const char **dptr, unsigned int *datalen)
1447 {
1448         enum ip_conntrack_info ctinfo;
1449         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1450         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1451         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1452         unsigned int matchoff, matchlen;
1453         unsigned int cseq, i;
1454         union nf_inet_addr addr;
1455         __be16 port;
1456
1457         /* Many Cisco IP phones use a high source port for SIP requests, but
1458          * listen for the response on port 5060.  If we are the local
1459          * router for one of these phones, save the port number from the
1460          * Via: header so that nf_nat_sip can redirect the responses to
1461          * the correct port.
1462          */
1463         if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1464                                     SIP_HDR_VIA_UDP, NULL, &matchoff,
1465                                     &matchlen, &addr, &port) > 0 &&
1466             port != ct->tuplehash[dir].tuple.src.u.udp.port &&
1467             nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
1468                 ct_sip_info->forced_dport = port;
1469
1470         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1471                 const struct sip_handler *handler;
1472
1473                 handler = &sip_handlers[i];
1474                 if (handler->request == NULL)
1475                         continue;
1476                 if (*datalen < handler->len + 2 ||
1477                     strncasecmp(*dptr, handler->method, handler->len))
1478                         continue;
1479                 if ((*dptr)[handler->len] != ' ' ||
1480                     !isalpha((*dptr)[handler->len+1]))
1481                         continue;
1482
1483                 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1484                                       &matchoff, &matchlen) <= 0) {
1485                         nf_ct_helper_log(skb, ct, "cannot parse cseq");
1486                         return NF_DROP;
1487                 }
1488                 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1489                 if (!cseq && *(*dptr + matchoff) != '0') {
1490                         nf_ct_helper_log(skb, ct, "cannot get cseq");
1491                         return NF_DROP;
1492                 }
1493
1494                 return handler->request(skb, protoff, dataoff, dptr, datalen,
1495                                         cseq);
1496         }
1497         return NF_ACCEPT;
1498 }
1499
1500 static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
1501                            unsigned int protoff, unsigned int dataoff,
1502                            const char **dptr, unsigned int *datalen)
1503 {
1504         const struct nf_nat_sip_hooks *hooks;
1505         int ret;
1506
1507         if (strncasecmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
1508                 ret = process_sip_request(skb, protoff, dataoff, dptr, datalen);
1509         else
1510                 ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
1511
1512         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1513                 hooks = rcu_dereference(nf_nat_sip_hooks);
1514                 if (hooks && !hooks->msg(skb, protoff, dataoff,
1515                                          dptr, datalen)) {
1516                         nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
1517                         ret = NF_DROP;
1518                 }
1519         }
1520
1521         return ret;
1522 }
1523
1524 static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
1525                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1526 {
1527         struct tcphdr *th, _tcph;
1528         unsigned int dataoff, datalen;
1529         unsigned int matchoff, matchlen, clen;
1530         unsigned int msglen, origlen;
1531         const char *dptr, *end;
1532         s16 diff, tdiff = 0;
1533         int ret = NF_ACCEPT;
1534         bool term;
1535
1536         if (ctinfo != IP_CT_ESTABLISHED &&
1537             ctinfo != IP_CT_ESTABLISHED_REPLY)
1538                 return NF_ACCEPT;
1539
1540         /* No Data ? */
1541         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
1542         if (th == NULL)
1543                 return NF_ACCEPT;
1544         dataoff = protoff + th->doff * 4;
1545         if (dataoff >= skb->len)
1546                 return NF_ACCEPT;
1547
1548         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1549
1550         if (unlikely(skb_linearize(skb)))
1551                 return NF_DROP;
1552
1553         dptr = skb->data + dataoff;
1554         datalen = skb->len - dataoff;
1555         if (datalen < strlen("SIP/2.0 200"))
1556                 return NF_ACCEPT;
1557
1558         while (1) {
1559                 if (ct_sip_get_header(ct, dptr, 0, datalen,
1560                                       SIP_HDR_CONTENT_LENGTH,
1561                                       &matchoff, &matchlen) <= 0)
1562                         break;
1563
1564                 clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
1565                 if (dptr + matchoff == end)
1566                         break;
1567
1568                 term = false;
1569                 for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) {
1570                         if (end[0] == '\r' && end[1] == '\n' &&
1571                             end[2] == '\r' && end[3] == '\n') {
1572                                 term = true;
1573                                 break;
1574                         }
1575                 }
1576                 if (!term)
1577                         break;
1578                 end += strlen("\r\n\r\n") + clen;
1579
1580                 msglen = origlen = end - dptr;
1581                 if (msglen > datalen)
1582                         return NF_ACCEPT;
1583
1584                 ret = process_sip_msg(skb, ct, protoff, dataoff,
1585                                       &dptr, &msglen);
1586                 /* process_sip_* functions report why this packet is dropped */
1587                 if (ret != NF_ACCEPT)
1588                         break;
1589                 diff     = msglen - origlen;
1590                 tdiff   += diff;
1591
1592                 dataoff += msglen;
1593                 dptr    += msglen;
1594                 datalen  = datalen + diff - msglen;
1595         }
1596
1597         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1598                 const struct nf_nat_sip_hooks *hooks;
1599
1600                 hooks = rcu_dereference(nf_nat_sip_hooks);
1601                 if (hooks)
1602                         hooks->seq_adjust(skb, protoff, tdiff);
1603         }
1604
1605         return ret;
1606 }
1607
1608 static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
1609                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1610 {
1611         unsigned int dataoff, datalen;
1612         const char *dptr;
1613
1614         /* No Data ? */
1615         dataoff = protoff + sizeof(struct udphdr);
1616         if (dataoff >= skb->len)
1617                 return NF_ACCEPT;
1618
1619         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1620
1621         if (unlikely(skb_linearize(skb)))
1622                 return NF_DROP;
1623
1624         dptr = skb->data + dataoff;
1625         datalen = skb->len - dataoff;
1626         if (datalen < strlen("SIP/2.0 200"))
1627                 return NF_ACCEPT;
1628
1629         return process_sip_msg(skb, ct, protoff, dataoff, &dptr, &datalen);
1630 }
1631
1632 static struct nf_conntrack_helper sip[MAX_PORTS * 4] __read_mostly;
1633
1634 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
1635         [SIP_EXPECT_SIGNALLING] = {
1636                 .name           = "signalling",
1637                 .max_expected   = 1,
1638                 .timeout        = 3 * 60,
1639         },
1640         [SIP_EXPECT_AUDIO] = {
1641                 .name           = "audio",
1642                 .max_expected   = 2 * IP_CT_DIR_MAX,
1643                 .timeout        = 3 * 60,
1644         },
1645         [SIP_EXPECT_VIDEO] = {
1646                 .name           = "video",
1647                 .max_expected   = 2 * IP_CT_DIR_MAX,
1648                 .timeout        = 3 * 60,
1649         },
1650         [SIP_EXPECT_IMAGE] = {
1651                 .name           = "image",
1652                 .max_expected   = IP_CT_DIR_MAX,
1653                 .timeout        = 3 * 60,
1654         },
1655 };
1656
1657 static void __exit nf_conntrack_sip_fini(void)
1658 {
1659         nf_conntrack_helpers_unregister(sip, ports_c * 4);
1660 }
1661
1662 static int __init nf_conntrack_sip_init(void)
1663 {
1664         int i, ret;
1665
1666         NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sip_master));
1667
1668         if (ports_c == 0)
1669                 ports[ports_c++] = SIP_PORT;
1670
1671         for (i = 0; i < ports_c; i++) {
1672                 nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP, "sip",
1673                                   SIP_PORT, ports[i], i, sip_exp_policy,
1674                                   SIP_EXPECT_MAX, sip_help_udp,
1675                                   NULL, THIS_MODULE);
1676                 nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP, "sip",
1677                                   SIP_PORT, ports[i], i, sip_exp_policy,
1678                                   SIP_EXPECT_MAX, sip_help_tcp,
1679                                   NULL, THIS_MODULE);
1680                 nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP, "sip",
1681                                   SIP_PORT, ports[i], i, sip_exp_policy,
1682                                   SIP_EXPECT_MAX, sip_help_udp,
1683                                   NULL, THIS_MODULE);
1684                 nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP, "sip",
1685                                   SIP_PORT, ports[i], i, sip_exp_policy,
1686                                   SIP_EXPECT_MAX, sip_help_tcp,
1687                                   NULL, THIS_MODULE);
1688         }
1689
1690         ret = nf_conntrack_helpers_register(sip, ports_c * 4);
1691         if (ret < 0) {
1692                 pr_err("failed to register helpers\n");
1693                 return ret;
1694         }
1695         return 0;
1696 }
1697
1698 module_init(nf_conntrack_sip_init);
1699 module_exit(nf_conntrack_sip_fini);