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