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 (!nf_ct_remove_expect(exp))
 833                         continue;
 834                 if (!media)
 835                         break;
 836         }
 837         spin_unlock_bh(&nf_conntrack_expect_lock);
 838 }
 839
 840 static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
 841                                  unsigned int dataoff,
 842                                  const char **dptr, unsigned int *datalen,
 843                                  union nf_inet_addr *daddr, __be16 port,
 844                                  enum sip_expectation_classes class,
 845                                  unsigned int mediaoff, unsigned int medialen)
 846 {
 847         struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
 848         enum ip_conntrack_info ctinfo;
 849         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 850         struct net *net = nf_ct_net(ct);
 851         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 852         union nf_inet_addr *saddr;
 853         struct nf_conntrack_tuple tuple;
 854         int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
 855         u_int16_t base_port;
 856         __be16 rtp_port, rtcp_port;
 857         const struct nf_nat_sip_hooks *hooks;
 858
 859         saddr = NULL;
 860         if (sip_direct_media) {
 861                 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
 862                         return NF_ACCEPT;
 863                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
 864         }
 865
 866         /* We need to check whether the registration exists before attempting
 867          * to register it since we can see the same media description multiple
 868          * times on different connections in case multiple endpoints receive
 869          * the same call.
 870          *
 871          * RTP optimization: if we find a matching media channel expectation
 872          * and both the expectation and this connection are SNATed, we assume
 873          * both sides can reach each other directly and use the final
 874          * destination address from the expectation. We still need to keep
 875          * the NATed expectations for media that might arrive from the
 876          * outside, and additionally need to expect the direct RTP stream
 877          * in case it passes through us even without NAT.
 878          */
 879         memset(&tuple, 0, sizeof(tuple));
 880         if (saddr)
 881                 tuple.src.u3 = *saddr;
 882         tuple.src.l3num         = nf_ct_l3num(ct);
 883         tuple.dst.protonum      = IPPROTO_UDP;
 884         tuple.dst.u3            = *daddr;
 885         tuple.dst.u.udp.port    = port;
 886
 887         do {
 888                 exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
 889
 890                 if (!exp || exp->master == ct ||
 891                     nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
 892                     exp->class != class)
 893                         break;
 894 #ifdef CONFIG_NF_NAT_NEEDED
 895                 if (!direct_rtp &&
 896                     (!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
 897                      exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
 898                     ct->status & IPS_NAT_MASK) {
 899                         *daddr                  = exp->saved_addr;
 900                         tuple.dst.u3            = exp->saved_addr;
 901                         tuple.dst.u.udp.port    = exp->saved_proto.udp.port;
 902                         direct_rtp = 1;
 903                 } else
 904 #endif
 905                         skip_expect = 1;
 906         } while (!skip_expect);
 907
 908         base_port = ntohs(tuple.dst.u.udp.port) & ~1;
 909         rtp_port = htons(base_port);
 910         rtcp_port = htons(base_port + 1);
 911
 912         if (direct_rtp) {
 913                 hooks = rcu_dereference(nf_nat_sip_hooks);
 914                 if (hooks &&
 915                     !hooks->sdp_port(skb, protoff, dataoff, dptr, datalen,
 916                                      mediaoff, medialen, ntohs(rtp_port)))
 917                         goto err1;
 918         }
 919
 920         if (skip_expect)
 921                 return NF_ACCEPT;
 922
 923         rtp_exp = nf_ct_expect_alloc(ct);
 924         if (rtp_exp == NULL)
 925                 goto err1;
 926         nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 927                           IPPROTO_UDP, NULL, &rtp_port);
 928
 929         rtcp_exp = nf_ct_expect_alloc(ct);
 930         if (rtcp_exp == NULL)
 931                 goto err2;
 932         nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
 933                           IPPROTO_UDP, NULL, &rtcp_port);
 934
 935         hooks = rcu_dereference(nf_nat_sip_hooks);
 936         if (hooks && ct->status & IPS_NAT_MASK && !direct_rtp)
 937                 ret = hooks->sdp_media(skb, protoff, dataoff, dptr,
 938                                        datalen, rtp_exp, rtcp_exp,
 939                                        mediaoff, medialen, daddr);
 940         else {
 941                 if (nf_ct_expect_related(rtp_exp) == 0) {
 942                         if (nf_ct_expect_related(rtcp_exp) != 0)
 943                                 nf_ct_unexpect_related(rtp_exp);
 944                         else
 945                                 ret = NF_ACCEPT;
 946                 }
 947         }
 948         nf_ct_expect_put(rtcp_exp);
 949 err2:
 950         nf_ct_expect_put(rtp_exp);
 951 err1:
 952         return ret;
 953 }
 954
 955 static const struct sdp_media_type sdp_media_types[] = {
 956         SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
 957         SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
 958         SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE),
 959 };
 960
 961 static const struct sdp_media_type *sdp_media_type(const char *dptr,
 962                                                    unsigned int matchoff,
 963                                                    unsigned int matchlen)
 964 {
 965         const struct sdp_media_type *t;
 966         unsigned int i;
 967
 968         for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
 969                 t = &sdp_media_types[i];
 970                 if (matchlen < t->len ||
 971                     strncmp(dptr + matchoff, t->name, t->len))
 972                         continue;
 973                 return t;
 974         }
 975         return NULL;
 976 }
 977
 978 static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 979                        unsigned int dataoff,
 980                        const char **dptr, unsigned int *datalen,
 981                        unsigned int cseq)
 982 {
 983         enum ip_conntrack_info ctinfo;
 984         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
 985         unsigned int matchoff, matchlen;
 986         unsigned int mediaoff, medialen;
 987         unsigned int sdpoff;
 988         unsigned int caddr_len, maddr_len;
 989         unsigned int i;
 990         union nf_inet_addr caddr, maddr, rtp_addr;
 991         const struct nf_nat_sip_hooks *hooks;
 992         unsigned int port;
 993         const struct sdp_media_type *t;
 994         int ret = NF_ACCEPT;
 995
 996         hooks = rcu_dereference(nf_nat_sip_hooks);
 997
 998         /* Find beginning of session description */
 999         if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
1000                                   SDP_HDR_VERSION, SDP_HDR_UNSPEC,
1001                                   &matchoff, &matchlen) <= 0)
1002                 return NF_ACCEPT;
1003         sdpoff = matchoff;
1004
1005         /* The connection information is contained in the session description
1006          * and/or once per media description. The first media description marks
1007          * the end of the session description. */
1008         caddr_len = 0;
1009         if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
1010                                   SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1011                                   &matchoff, &matchlen, &caddr) > 0)
1012                 caddr_len = matchlen;
1013
1014         mediaoff = sdpoff;
1015         for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
1016                 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
1017                                           SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
1018                                           &mediaoff, &medialen) <= 0)
1019                         break;
1020
1021                 /* Get media type and port number. A media port value of zero
1022                  * indicates an inactive stream. */
1023                 t = sdp_media_type(*dptr, mediaoff, medialen);
1024                 if (!t) {
1025                         mediaoff += medialen;
1026                         continue;
1027                 }
1028                 mediaoff += t->len;
1029                 medialen -= t->len;
1030
1031                 port = simple_strtoul(*dptr + mediaoff, NULL, 10);
1032                 if (port == 0)
1033                         continue;
1034                 if (port < 1024 || port > 65535) {
1035                         nf_ct_helper_log(skb, ct, "wrong port %u", port);
1036                         return NF_DROP;
1037                 }
1038
1039                 /* The media description overrides the session description. */
1040                 maddr_len = 0;
1041                 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
1042                                           SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1043                                           &matchoff, &matchlen, &maddr) > 0) {
1044                         maddr_len = matchlen;
1045                         memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
1046                 } else if (caddr_len)
1047                         memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
1048                 else {
1049                         nf_ct_helper_log(skb, ct, "cannot parse SDP message");
1050                         return NF_DROP;
1051                 }
1052
1053                 ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
1054                                             dptr, datalen,
1055                                             &rtp_addr, htons(port), t->class,
1056                                             mediaoff, medialen);
1057                 if (ret != NF_ACCEPT) {
1058                         nf_ct_helper_log(skb, ct,
1059                                          "cannot add expectation for voice");
1060                         return ret;
1061                 }
1062
1063                 /* Update media connection address if present */
1064                 if (maddr_len && hooks && ct->status & IPS_NAT_MASK) {
1065                         ret = hooks->sdp_addr(skb, protoff, dataoff,
1066                                               dptr, datalen, mediaoff,
1067                                               SDP_HDR_CONNECTION,
1068                                               SDP_HDR_MEDIA,
1069                                               &rtp_addr);
1070                         if (ret != NF_ACCEPT) {
1071                                 nf_ct_helper_log(skb, ct, "cannot mangle SDP");
1072                                 return ret;
1073                         }
1074                 }
1075                 i++;
1076         }
1077
1078         /* Update session connection and owner addresses */
1079         hooks = rcu_dereference(nf_nat_sip_hooks);
1080         if (hooks && ct->status & IPS_NAT_MASK)
1081                 ret = hooks->sdp_session(skb, protoff, dataoff,
1082                                          dptr, datalen, sdpoff,
1083                                          &rtp_addr);
1084
1085         return ret;
1086 }
1087 static int process_invite_response(struct sk_buff *skb, unsigned int protoff,
1088                                    unsigned int dataoff,
1089                                    const char **dptr, unsigned int *datalen,
1090                                    unsigned int cseq, unsigned int code)
1091 {
1092         enum ip_conntrack_info ctinfo;
1093         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1094         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1095
1096         if ((code >= 100 && code <= 199) ||
1097             (code >= 200 && code <= 299))
1098                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1099         else if (ct_sip_info->invite_cseq == cseq)
1100                 flush_expectations(ct, true);
1101         return NF_ACCEPT;
1102 }
1103
1104 static int process_update_response(struct sk_buff *skb, unsigned int protoff,
1105                                    unsigned int dataoff,
1106                                    const char **dptr, unsigned int *datalen,
1107                                    unsigned int cseq, unsigned int code)
1108 {
1109         enum ip_conntrack_info ctinfo;
1110         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1111         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1112
1113         if ((code >= 100 && code <= 199) ||
1114             (code >= 200 && code <= 299))
1115                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1116         else if (ct_sip_info->invite_cseq == cseq)
1117                 flush_expectations(ct, true);
1118         return NF_ACCEPT;
1119 }
1120
1121 static int process_prack_response(struct sk_buff *skb, unsigned int protoff,
1122                                   unsigned int dataoff,
1123                                   const char **dptr, unsigned int *datalen,
1124                                   unsigned int cseq, unsigned int code)
1125 {
1126         enum ip_conntrack_info ctinfo;
1127         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1128         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1129
1130         if ((code >= 100 && code <= 199) ||
1131             (code >= 200 && code <= 299))
1132                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1133         else if (ct_sip_info->invite_cseq == cseq)
1134                 flush_expectations(ct, true);
1135         return NF_ACCEPT;
1136 }
1137
1138 static int process_invite_request(struct sk_buff *skb, unsigned int protoff,
1139                                   unsigned int dataoff,
1140                                   const char **dptr, unsigned int *datalen,
1141                                   unsigned int cseq)
1142 {
1143         enum ip_conntrack_info ctinfo;
1144         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1145         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1146         unsigned int ret;
1147
1148         flush_expectations(ct, true);
1149         ret = process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1150         if (ret == NF_ACCEPT)
1151                 ct_sip_info->invite_cseq = cseq;
1152         return ret;
1153 }
1154
1155 static int process_bye_request(struct sk_buff *skb, unsigned int protoff,
1156                                unsigned int dataoff,
1157                                const char **dptr, unsigned int *datalen,
1158                                unsigned int cseq)
1159 {
1160         enum ip_conntrack_info ctinfo;
1161         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1162
1163         flush_expectations(ct, true);
1164         return NF_ACCEPT;
1165 }
1166
1167 /* Parse a REGISTER request and create a permanent expectation for incoming
1168  * signalling connections. The expectation is marked inactive and is activated
1169  * when receiving a response indicating success from the registrar.
1170  */
1171 static int process_register_request(struct sk_buff *skb, unsigned int protoff,
1172                                     unsigned int dataoff,
1173                                     const char **dptr, unsigned int *datalen,
1174                                     unsigned int cseq)
1175 {
1176         enum ip_conntrack_info ctinfo;
1177         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1178         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1179         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1180         unsigned int matchoff, matchlen;
1181         struct nf_conntrack_expect *exp;
1182         union nf_inet_addr *saddr, daddr;
1183         const struct nf_nat_sip_hooks *hooks;
1184         __be16 port;
1185         u8 proto;
1186         unsigned int expires = 0;
1187         int ret;
1188
1189         /* Expected connections can not register again. */
1190         if (ct->status & IPS_EXPECTED)
1191                 return NF_ACCEPT;
1192
1193         /* We must check the expiration time: a value of zero signals the
1194          * registrar to release the binding. We'll remove our expectation
1195          * when receiving the new bindings in the response, but we don't
1196          * want to create new ones.
1197          *
1198          * The expiration time may be contained in Expires: header, the
1199          * Contact: header parameters or the URI parameters.
1200          */
1201         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1202                               &matchoff, &matchlen) > 0)
1203                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1204
1205         ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1206                                       SIP_HDR_CONTACT, NULL,
1207                                       &matchoff, &matchlen, &daddr, &port);
1208         if (ret < 0) {
1209                 nf_ct_helper_log(skb, ct, "cannot parse contact");
1210                 return NF_DROP;
1211         } else if (ret == 0)
1212                 return NF_ACCEPT;
1213
1214         /* We don't support third-party registrations */
1215         if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
1216                 return NF_ACCEPT;
1217
1218         if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
1219                                    &proto) == 0)
1220                 return NF_ACCEPT;
1221
1222         if (ct_sip_parse_numerical_param(ct, *dptr,
1223                                          matchoff + matchlen, *datalen,
1224                                          "expires=", NULL, NULL, &expires) < 0) {
1225                 nf_ct_helper_log(skb, ct, "cannot parse expires");
1226                 return NF_DROP;
1227         }
1228
1229         if (expires == 0) {
1230                 ret = NF_ACCEPT;
1231                 goto store_cseq;
1232         }
1233
1234         exp = nf_ct_expect_alloc(ct);
1235         if (!exp) {
1236                 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
1237                 return NF_DROP;
1238         }
1239
1240         saddr = NULL;
1241         if (sip_direct_signalling)
1242                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
1243
1244         nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
1245                           saddr, &daddr, proto, NULL, &port);
1246         exp->timeout.expires = sip_timeout * HZ;
1247         exp->helper = nfct_help(ct)->helper;
1248         exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
1249
1250         hooks = rcu_dereference(nf_nat_sip_hooks);
1251         if (hooks && ct->status & IPS_NAT_MASK)
1252                 ret = hooks->expect(skb, protoff, dataoff, dptr, datalen,
1253                                     exp, matchoff, matchlen);
1254         else {
1255                 if (nf_ct_expect_related(exp) != 0) {
1256                         nf_ct_helper_log(skb, ct, "cannot add expectation");
1257                         ret = NF_DROP;
1258                 } else
1259                         ret = NF_ACCEPT;
1260         }
1261         nf_ct_expect_put(exp);
1262
1263 store_cseq:
1264         if (ret == NF_ACCEPT)
1265                 ct_sip_info->register_cseq = cseq;
1266         return ret;
1267 }
1268
1269 static int process_register_response(struct sk_buff *skb, unsigned int protoff,
1270                                      unsigned int dataoff,
1271                                      const char **dptr, unsigned int *datalen,
1272                                      unsigned int cseq, unsigned int code)
1273 {
1274         enum ip_conntrack_info ctinfo;
1275         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1276         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1277         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1278         union nf_inet_addr addr;
1279         __be16 port;
1280         u8 proto;
1281         unsigned int matchoff, matchlen, coff = 0;
1282         unsigned int expires = 0;
1283         int in_contact = 0, ret;
1284
1285         /* According to RFC 3261, "UAs MUST NOT send a new registration until
1286          * they have received a final response from the registrar for the
1287          * previous one or the previous REGISTER request has timed out".
1288          *
1289          * However, some servers fail to detect retransmissions and send late
1290          * responses, so we store the sequence number of the last valid
1291          * request and compare it here.
1292          */
1293         if (ct_sip_info->register_cseq != cseq)
1294                 return NF_ACCEPT;
1295
1296         if (code >= 100 && code <= 199)
1297                 return NF_ACCEPT;
1298         if (code < 200 || code > 299)
1299                 goto flush;
1300
1301         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1302                               &matchoff, &matchlen) > 0)
1303                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1304
1305         while (1) {
1306                 unsigned int c_expires = expires;
1307
1308                 ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
1309                                               SIP_HDR_CONTACT, &in_contact,
1310                                               &matchoff, &matchlen,
1311                                               &addr, &port);
1312                 if (ret < 0) {
1313                         nf_ct_helper_log(skb, ct, "cannot parse contact");
1314                         return NF_DROP;
1315                 } else if (ret == 0)
1316                         break;
1317
1318                 /* We don't support third-party registrations */
1319                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
1320                         continue;
1321
1322                 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
1323                                            *datalen, &proto) == 0)
1324                         continue;
1325
1326                 ret = ct_sip_parse_numerical_param(ct, *dptr,
1327                                                    matchoff + matchlen,
1328                                                    *datalen, "expires=",
1329                                                    NULL, NULL, &c_expires);
1330                 if (ret < 0) {
1331                         nf_ct_helper_log(skb, ct, "cannot parse expires");
1332                         return NF_DROP;
1333                 }
1334                 if (c_expires == 0)
1335                         break;
1336                 if (refresh_signalling_expectation(ct, &addr, proto, port,
1337                                                    c_expires))
1338                         return NF_ACCEPT;
1339         }
1340
1341 flush:
1342         flush_expectations(ct, false);
1343         return NF_ACCEPT;
1344 }
1345
1346 static const struct sip_handler sip_handlers[] = {
1347         SIP_HANDLER("INVITE", process_invite_request, process_invite_response),
1348         SIP_HANDLER("UPDATE", process_sdp, process_update_response),
1349         SIP_HANDLER("ACK", process_sdp, NULL),
1350         SIP_HANDLER("PRACK", process_sdp, process_prack_response),
1351         SIP_HANDLER("BYE", process_bye_request, NULL),
1352         SIP_HANDLER("REGISTER", process_register_request, process_register_response),
1353 };
1354
1355 static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
1356                                 unsigned int dataoff,
1357                                 const char **dptr, unsigned int *datalen)
1358 {
1359         enum ip_conntrack_info ctinfo;
1360         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1361         unsigned int matchoff, matchlen, matchend;
1362         unsigned int code, cseq, i;
1363
1364         if (*datalen < strlen("SIP/2.0 200"))
1365                 return NF_ACCEPT;
1366         code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
1367         if (!code) {
1368                 nf_ct_helper_log(skb, ct, "cannot get code");
1369                 return NF_DROP;
1370         }
1371
1372         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1373                               &matchoff, &matchlen) <= 0) {
1374                 nf_ct_helper_log(skb, ct, "cannot parse cseq");
1375                 return NF_DROP;
1376         }
1377         cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1378         if (!cseq && *(*dptr + matchoff) != '0') {
1379                 nf_ct_helper_log(skb, ct, "cannot get cseq");
1380                 return NF_DROP;
1381         }
1382         matchend = matchoff + matchlen + 1;
1383
1384         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1385                 const struct sip_handler *handler;
1386
1387                 handler = &sip_handlers[i];
1388                 if (handler->response == NULL)
1389                         continue;
1390                 if (*datalen < matchend + handler->len ||
1391                     strncasecmp(*dptr + matchend, handler->method, handler->len))
1392                         continue;
1393                 return handler->response(skb, protoff, dataoff, dptr, datalen,
1394                                          cseq, code);
1395         }
1396         return NF_ACCEPT;
1397 }
1398
1399 static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
1400                                unsigned int dataoff,
1401                                const char **dptr, unsigned int *datalen)
1402 {
1403         enum ip_conntrack_info ctinfo;
1404         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1405         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1406         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1407         unsigned int matchoff, matchlen;
1408         unsigned int cseq, i;
1409         union nf_inet_addr addr;
1410         __be16 port;
1411
1412         /* Many Cisco IP phones use a high source port for SIP requests, but
1413          * listen for the response on port 5060.  If we are the local
1414          * router for one of these phones, save the port number from the
1415          * Via: header so that nf_nat_sip can redirect the responses to
1416          * the correct port.
1417          */
1418         if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1419                                     SIP_HDR_VIA_UDP, NULL, &matchoff,
1420                                     &matchlen, &addr, &port) > 0 &&
1421             port != ct->tuplehash[dir].tuple.src.u.udp.port &&
1422             nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
1423                 ct_sip_info->forced_dport = port;
1424
1425         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1426                 const struct sip_handler *handler;
1427
1428                 handler = &sip_handlers[i];
1429                 if (handler->request == NULL)
1430                         continue;
1431                 if (*datalen < handler->len + 2 ||
1432                     strncasecmp(*dptr, handler->method, handler->len))
1433                         continue;
1434                 if ((*dptr)[handler->len] != ' ' ||
1435                     !isalpha((*dptr)[handler->len+1]))
1436                         continue;
1437
1438                 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1439                                       &matchoff, &matchlen) <= 0) {
1440                         nf_ct_helper_log(skb, ct, "cannot parse cseq");
1441                         return NF_DROP;
1442                 }
1443                 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1444                 if (!cseq && *(*dptr + matchoff) != '0') {
1445                         nf_ct_helper_log(skb, ct, "cannot get cseq");
1446                         return NF_DROP;
1447                 }
1448
1449                 return handler->request(skb, protoff, dataoff, dptr, datalen,
1450                                         cseq);
1451         }
1452         return NF_ACCEPT;
1453 }
1454
1455 static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
1456                            unsigned int protoff, unsigned int dataoff,
1457                            const char **dptr, unsigned int *datalen)
1458 {
1459         const struct nf_nat_sip_hooks *hooks;
1460         int ret;
1461
1462         if (strncasecmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
1463                 ret = process_sip_request(skb, protoff, dataoff, dptr, datalen);
1464         else
1465                 ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
1466
1467         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1468                 hooks = rcu_dereference(nf_nat_sip_hooks);
1469                 if (hooks && !hooks->msg(skb, protoff, dataoff,
1470                                          dptr, datalen)) {
1471                         nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
1472                         ret = NF_DROP;
1473                 }
1474         }
1475
1476         return ret;
1477 }
1478
1479 static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
1480                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1481 {
1482         struct tcphdr *th, _tcph;
1483         unsigned int dataoff, datalen;
1484         unsigned int matchoff, matchlen, clen;
1485         unsigned int msglen, origlen;
1486         const char *dptr, *end;
1487         s16 diff, tdiff = 0;
1488         int ret = NF_ACCEPT;
1489         bool term;
1490
1491         if (ctinfo != IP_CT_ESTABLISHED &&
1492             ctinfo != IP_CT_ESTABLISHED_REPLY)
1493                 return NF_ACCEPT;
1494
1495         /* No Data ? */
1496         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
1497         if (th == NULL)
1498                 return NF_ACCEPT;
1499         dataoff = protoff + th->doff * 4;
1500         if (dataoff >= skb->len)
1501                 return NF_ACCEPT;
1502
1503         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1504
1505         if (unlikely(skb_linearize(skb)))
1506                 return NF_DROP;
1507
1508         dptr = skb->data + dataoff;
1509         datalen = skb->len - dataoff;
1510         if (datalen < strlen("SIP/2.0 200"))
1511                 return NF_ACCEPT;
1512
1513         while (1) {
1514                 if (ct_sip_get_header(ct, dptr, 0, datalen,
1515                                       SIP_HDR_CONTENT_LENGTH,
1516                                       &matchoff, &matchlen) <= 0)
1517                         break;
1518
1519                 clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
1520                 if (dptr + matchoff == end)
1521                         break;
1522
1523                 term = false;
1524                 for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) {
1525                         if (end[0] == '\r' && end[1] == '\n' &&
1526                             end[2] == '\r' && end[3] == '\n') {
1527                                 term = true;
1528                                 break;
1529                         }
1530                 }
1531                 if (!term)
1532                         break;
1533                 end += strlen("\r\n\r\n") + clen;
1534
1535                 msglen = origlen = end - dptr;
1536                 if (msglen > datalen)
1537                         return NF_ACCEPT;
1538
1539                 ret = process_sip_msg(skb, ct, protoff, dataoff,
1540                                       &dptr, &msglen);
1541                 /* process_sip_* functions report why this packet is dropped */
1542                 if (ret != NF_ACCEPT)
1543                         break;
1544                 diff     = msglen - origlen;
1545                 tdiff   += diff;
1546
1547                 dataoff += msglen;
1548                 dptr    += msglen;
1549                 datalen  = datalen + diff - msglen;
1550         }
1551
1552         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1553                 const struct nf_nat_sip_hooks *hooks;
1554
1555                 hooks = rcu_dereference(nf_nat_sip_hooks);
1556                 if (hooks)
1557                         hooks->seq_adjust(skb, protoff, tdiff);
1558         }
1559
1560         return ret;
1561 }
1562
1563 static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
1564                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1565 {
1566         unsigned int dataoff, datalen;
1567         const char *dptr;
1568
1569         /* No Data ? */
1570         dataoff = protoff + sizeof(struct udphdr);
1571         if (dataoff >= skb->len)
1572                 return NF_ACCEPT;
1573
1574         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1575
1576         if (unlikely(skb_linearize(skb)))
1577                 return NF_DROP;
1578
1579         dptr = skb->data + dataoff;
1580         datalen = skb->len - dataoff;
1581         if (datalen < strlen("SIP/2.0 200"))
1582                 return NF_ACCEPT;
1583
1584         return process_sip_msg(skb, ct, protoff, dataoff, &dptr, &datalen);
1585 }
1586
1587 static struct nf_conntrack_helper sip[MAX_PORTS * 4] __read_mostly;
1588
1589 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
1590         [SIP_EXPECT_SIGNALLING] = {
1591                 .name           = "signalling",
1592                 .max_expected   = 1,
1593                 .timeout        = 3 * 60,
1594         },
1595         [SIP_EXPECT_AUDIO] = {
1596                 .name           = "audio",
1597                 .max_expected   = 2 * IP_CT_DIR_MAX,
1598                 .timeout        = 3 * 60,
1599         },
1600         [SIP_EXPECT_VIDEO] = {
1601                 .name           = "video",
1602                 .max_expected   = 2 * IP_CT_DIR_MAX,
1603                 .timeout        = 3 * 60,
1604         },
1605         [SIP_EXPECT_IMAGE] = {
1606                 .name           = "image",
1607                 .max_expected   = IP_CT_DIR_MAX,
1608                 .timeout        = 3 * 60,
1609         },
1610 };
1611
1612 static void nf_conntrack_sip_fini(void)
1613 {
1614         nf_conntrack_helpers_unregister(sip, ports_c * 4);
1615 }
1616
1617 static int __init nf_conntrack_sip_init(void)
1618 {
1619         int i, ret;
1620
1621         NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sip_master));
1622
1623         if (ports_c == 0)
1624                 ports[ports_c++] = SIP_PORT;
1625
1626         for (i = 0; i < ports_c; i++) {
1627                 nf_ct_helper_init(&sip[4 * i], AF_INET, IPPROTO_UDP, "sip",
1628                                   SIP_PORT, ports[i], i, sip_exp_policy,
1629                                   SIP_EXPECT_MAX, sip_help_udp,
1630                                   NULL, THIS_MODULE);
1631                 nf_ct_helper_init(&sip[4 * i + 1], AF_INET, IPPROTO_TCP, "sip",
1632                                   SIP_PORT, ports[i], i, sip_exp_policy,
1633                                   SIP_EXPECT_MAX, sip_help_tcp,
1634                                   NULL, THIS_MODULE);
1635                 nf_ct_helper_init(&sip[4 * i + 2], AF_INET6, IPPROTO_UDP, "sip",
1636                                   SIP_PORT, ports[i], i, sip_exp_policy,
1637                                   SIP_EXPECT_MAX, sip_help_udp,
1638                                   NULL, THIS_MODULE);
1639                 nf_ct_helper_init(&sip[4 * i + 3], AF_INET6, IPPROTO_TCP, "sip",
1640                                   SIP_PORT, ports[i], i, sip_exp_policy,
1641                                   SIP_EXPECT_MAX, sip_help_tcp,
1642                                   NULL, THIS_MODULE);
1643         }
1644
1645         ret = nf_conntrack_helpers_register(sip, ports_c * 4);
1646         if (ret < 0) {
1647                 pr_err("failed to register helpers\n");
1648                 return ret;
1649         }
1650         return 0;
1651 }
1652
1653 module_init(nf_conntrack_sip_init);
1654 module_exit(nf_conntrack_sip_fini);