ipvs: convert lblc scheduler to rcu
[linux-3.10.git] / 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 #include <linux/module.h>
14 #include <linux/ctype.h>
15 #include <linux/skbuff.h>
16 #include <linux/inet.h>
17 #include <linux/in.h>
18 #include <linux/udp.h>
19 #include <linux/tcp.h>
20 #include <linux/netfilter.h>
21
22 #include <net/netfilter/nf_conntrack.h>
23 #include <net/netfilter/nf_conntrack_core.h>
24 #include <net/netfilter/nf_conntrack_expect.h>
25 #include <net/netfilter/nf_conntrack_helper.h>
26 #include <net/netfilter/nf_conntrack_zones.h>
27 #include <linux/netfilter/nf_conntrack_sip.h>
28
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
31 MODULE_DESCRIPTION("SIP connection tracking helper");
32 MODULE_ALIAS("ip_conntrack_sip");
33 MODULE_ALIAS_NFCT_HELPER("sip");
34
35 #define MAX_PORTS       8
36 static unsigned short ports[MAX_PORTS];
37 static unsigned int ports_c;
38 module_param_array(ports, ushort, &ports_c, 0400);
39 MODULE_PARM_DESC(ports, "port numbers of SIP servers");
40
41 static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
42 module_param(sip_timeout, uint, 0600);
43 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
44
45 static int sip_direct_signalling __read_mostly = 1;
46 module_param(sip_direct_signalling, int, 0600);
47 MODULE_PARM_DESC(sip_direct_signalling, "expect incoming calls from registrar "
48                                         "only (default 1)");
49
50 static int sip_direct_media __read_mostly = 1;
51 module_param(sip_direct_media, int, 0600);
52 MODULE_PARM_DESC(sip_direct_media, "Expect Media streams between signalling "
53                                    "endpoints only (default 1)");
54
55 unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int protoff,
56                                 unsigned int dataoff, const char **dptr,
57                                 unsigned int *datalen) __read_mostly;
58 EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
59
60 void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, unsigned int protoff,
61                                    s16 off) __read_mostly;
62 EXPORT_SYMBOL_GPL(nf_nat_sip_seq_adjust_hook);
63
64 unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
65                                        unsigned int protoff,
66                                        unsigned int dataoff,
67                                        const char **dptr,
68                                        unsigned int *datalen,
69                                        struct nf_conntrack_expect *exp,
70                                        unsigned int matchoff,
71                                        unsigned int matchlen) __read_mostly;
72 EXPORT_SYMBOL_GPL(nf_nat_sip_expect_hook);
73
74 unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb, unsigned int protoff,
75                                      unsigned int dataoff,
76                                      const char **dptr,
77                                      unsigned int *datalen,
78                                      unsigned int sdpoff,
79                                      enum sdp_header_types type,
80                                      enum sdp_header_types term,
81                                      const union nf_inet_addr *addr)
82                                      __read_mostly;
83 EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook);
84
85 unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb, unsigned int protoff,
86                                      unsigned int dataoff,
87                                      const char **dptr,
88                                      unsigned int *datalen,
89                                      unsigned int matchoff,
90                                      unsigned int matchlen,
91                                      u_int16_t port) __read_mostly;
92 EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook);
93
94 unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
95                                         unsigned int protoff,
96                                         unsigned int dataoff,
97                                         const char **dptr,
98                                         unsigned int *datalen,
99                                         unsigned int sdpoff,
100                                         const union nf_inet_addr *addr)
101                                         __read_mostly;
102 EXPORT_SYMBOL_GPL(nf_nat_sdp_session_hook);
103
104 unsigned int (*nf_nat_sdp_media_hook)(struct sk_buff *skb, unsigned int protoff,
105                                       unsigned int dataoff,
106                                       const char **dptr,
107                                       unsigned int *datalen,
108                                       struct nf_conntrack_expect *rtp_exp,
109                                       struct nf_conntrack_expect *rtcp_exp,
110                                       unsigned int mediaoff,
111                                       unsigned int medialen,
112                                       union nf_inet_addr *rtp_addr)
113                                       __read_mostly;
114 EXPORT_SYMBOL_GPL(nf_nat_sdp_media_hook);
115
116 static int string_len(const struct nf_conn *ct, const char *dptr,
117                       const char *limit, int *shift)
118 {
119         int len = 0;
120
121         while (dptr < limit && isalpha(*dptr)) {
122                 dptr++;
123                 len++;
124         }
125         return len;
126 }
127
128 static int digits_len(const struct nf_conn *ct, const char *dptr,
129                       const char *limit, int *shift)
130 {
131         int len = 0;
132         while (dptr < limit && isdigit(*dptr)) {
133                 dptr++;
134                 len++;
135         }
136         return len;
137 }
138
139 static int iswordc(const char c)
140 {
141         if (isalnum(c) || c == '!' || c == '"' || c == '%' ||
142             (c >= '(' && c <= '/') || c == ':' || c == '<' || c == '>' ||
143             c == '?' || (c >= '[' && c <= ']') || c == '_' || c == '`' ||
144             c == '{' || c == '}' || c == '~')
145                 return 1;
146         return 0;
147 }
148
149 static int word_len(const char *dptr, const char *limit)
150 {
151         int len = 0;
152         while (dptr < limit && iswordc(*dptr)) {
153                 dptr++;
154                 len++;
155         }
156         return len;
157 }
158
159 static int callid_len(const struct nf_conn *ct, const char *dptr,
160                       const char *limit, int *shift)
161 {
162         int len, domain_len;
163
164         len = word_len(dptr, limit);
165         dptr += len;
166         if (!len || dptr == limit || *dptr != '@')
167                 return len;
168         dptr++;
169         len++;
170
171         domain_len = word_len(dptr, limit);
172         if (!domain_len)
173                 return 0;
174         return len + domain_len;
175 }
176
177 /* get media type + port length */
178 static int media_len(const struct nf_conn *ct, const char *dptr,
179                      const char *limit, int *shift)
180 {
181         int len = string_len(ct, dptr, limit, shift);
182
183         dptr += len;
184         if (dptr >= limit || *dptr != ' ')
185                 return 0;
186         len++;
187         dptr++;
188
189         return len + digits_len(ct, dptr, limit, shift);
190 }
191
192 static int sip_parse_addr(const struct nf_conn *ct, const char *cp,
193                           const char **endp, union nf_inet_addr *addr,
194                           const char *limit, bool delim)
195 {
196         const char *end;
197         int ret;
198
199         if (!ct)
200                 return 0;
201
202         memset(addr, 0, sizeof(*addr));
203         switch (nf_ct_l3num(ct)) {
204         case AF_INET:
205                 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
206                 if (ret == 0)
207                         return 0;
208                 break;
209         case AF_INET6:
210                 if (cp < limit && *cp == '[')
211                         cp++;
212                 else if (delim)
213                         return 0;
214
215                 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
216                 if (ret == 0)
217                         return 0;
218
219                 if (end < limit && *end == ']')
220                         end++;
221                 else if (delim)
222                         return 0;
223                 break;
224         default:
225                 BUG();
226         }
227
228         if (endp)
229                 *endp = end;
230         return 1;
231 }
232
233 /* skip ip address. returns its length. */
234 static int epaddr_len(const struct nf_conn *ct, const char *dptr,
235                       const char *limit, int *shift)
236 {
237         union nf_inet_addr addr;
238         const char *aux = dptr;
239
240         if (!sip_parse_addr(ct, dptr, &dptr, &addr, limit, true)) {
241                 pr_debug("ip: %s parse failed.!\n", dptr);
242                 return 0;
243         }
244
245         /* Port number */
246         if (*dptr == ':') {
247                 dptr++;
248                 dptr += digits_len(ct, dptr, limit, shift);
249         }
250         return dptr - aux;
251 }
252
253 /* get address length, skiping user info. */
254 static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr,
255                           const char *limit, int *shift)
256 {
257         const char *start = dptr;
258         int s = *shift;
259
260         /* Search for @, but stop at the end of the line.
261          * We are inside a sip: URI, so we don't need to worry about
262          * continuation lines. */
263         while (dptr < limit &&
264                *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
265                 (*shift)++;
266                 dptr++;
267         }
268
269         if (dptr < limit && *dptr == '@') {
270                 dptr++;
271                 (*shift)++;
272         } else {
273                 dptr = start;
274                 *shift = s;
275         }
276
277         return epaddr_len(ct, dptr, limit, shift);
278 }
279
280 /* Parse a SIP request line of the form:
281  *
282  * Request-Line = Method SP Request-URI SP SIP-Version CRLF
283  *
284  * and return the offset and length of the address contained in the Request-URI.
285  */
286 int ct_sip_parse_request(const struct nf_conn *ct,
287                          const char *dptr, unsigned int datalen,
288                          unsigned int *matchoff, unsigned int *matchlen,
289                          union nf_inet_addr *addr, __be16 *port)
290 {
291         const char *start = dptr, *limit = dptr + datalen, *end;
292         unsigned int mlen;
293         unsigned int p;
294         int shift = 0;
295
296         /* Skip method and following whitespace */
297         mlen = string_len(ct, dptr, limit, NULL);
298         if (!mlen)
299                 return 0;
300         dptr += mlen;
301         if (++dptr >= limit)
302                 return 0;
303
304         /* Find SIP URI */
305         for (; dptr < limit - strlen("sip:"); dptr++) {
306                 if (*dptr == '\r' || *dptr == '\n')
307                         return -1;
308                 if (strnicmp(dptr, "sip:", strlen("sip:")) == 0) {
309                         dptr += strlen("sip:");
310                         break;
311                 }
312         }
313         if (!skp_epaddr_len(ct, dptr, limit, &shift))
314                 return 0;
315         dptr += shift;
316
317         if (!sip_parse_addr(ct, dptr, &end, addr, limit, true))
318                 return -1;
319         if (end < limit && *end == ':') {
320                 end++;
321                 p = simple_strtoul(end, (char **)&end, 10);
322                 if (p < 1024 || p > 65535)
323                         return -1;
324                 *port = htons(p);
325         } else
326                 *port = htons(SIP_PORT);
327
328         if (end == dptr)
329                 return 0;
330         *matchoff = dptr - start;
331         *matchlen = end - dptr;
332         return 1;
333 }
334 EXPORT_SYMBOL_GPL(ct_sip_parse_request);
335
336 /* SIP header parsing: SIP headers are located at the beginning of a line, but
337  * may span several lines, in which case the continuation lines begin with a
338  * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or
339  * CRLF, RFC 3261 allows only CRLF, we support both.
340  *
341  * Headers are followed by (optionally) whitespace, a colon, again (optionally)
342  * whitespace and the values. Whitespace in this context means any amount of
343  * tabs, spaces and continuation lines, which are treated as a single whitespace
344  * character.
345  *
346  * Some headers may appear multiple times. A comma separated list of values is
347  * equivalent to multiple headers.
348  */
349 static const struct sip_header ct_sip_hdrs[] = {
350         [SIP_HDR_CSEQ]                  = SIP_HDR("CSeq", NULL, NULL, digits_len),
351         [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
352         [SIP_HDR_TO]                    = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
353         [SIP_HDR_CONTACT]               = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
354         [SIP_HDR_VIA_UDP]               = SIP_HDR("Via", "v", "UDP ", epaddr_len),
355         [SIP_HDR_VIA_TCP]               = SIP_HDR("Via", "v", "TCP ", epaddr_len),
356         [SIP_HDR_EXPIRES]               = SIP_HDR("Expires", NULL, NULL, digits_len),
357         [SIP_HDR_CONTENT_LENGTH]        = SIP_HDR("Content-Length", "l", NULL, digits_len),
358         [SIP_HDR_CALL_ID]               = SIP_HDR("Call-Id", "i", NULL, callid_len),
359 };
360
361 static const char *sip_follow_continuation(const char *dptr, const char *limit)
362 {
363         /* Walk past newline */
364         if (++dptr >= limit)
365                 return NULL;
366
367         /* Skip '\n' in CR LF */
368         if (*(dptr - 1) == '\r' && *dptr == '\n') {
369                 if (++dptr >= limit)
370                         return NULL;
371         }
372
373         /* Continuation line? */
374         if (*dptr != ' ' && *dptr != '\t')
375                 return NULL;
376
377         /* skip leading whitespace */
378         for (; dptr < limit; dptr++) {
379                 if (*dptr != ' ' && *dptr != '\t')
380                         break;
381         }
382         return dptr;
383 }
384
385 static const char *sip_skip_whitespace(const char *dptr, const char *limit)
386 {
387         for (; dptr < limit; dptr++) {
388                 if (*dptr == ' ')
389                         continue;
390                 if (*dptr != '\r' && *dptr != '\n')
391                         break;
392                 dptr = sip_follow_continuation(dptr, limit);
393                 if (dptr == NULL)
394                         return NULL;
395         }
396         return dptr;
397 }
398
399 /* Search within a SIP header value, dealing with continuation lines */
400 static const char *ct_sip_header_search(const char *dptr, const char *limit,
401                                         const char *needle, unsigned int len)
402 {
403         for (limit -= len; dptr < limit; dptr++) {
404                 if (*dptr == '\r' || *dptr == '\n') {
405                         dptr = sip_follow_continuation(dptr, limit);
406                         if (dptr == NULL)
407                                 break;
408                         continue;
409                 }
410
411                 if (strnicmp(dptr, needle, len) == 0)
412                         return dptr;
413         }
414         return NULL;
415 }
416
417 int ct_sip_get_header(const struct nf_conn *ct, const char *dptr,
418                       unsigned int dataoff, unsigned int datalen,
419                       enum sip_header_types type,
420                       unsigned int *matchoff, unsigned int *matchlen)
421 {
422         const struct sip_header *hdr = &ct_sip_hdrs[type];
423         const char *start = dptr, *limit = dptr + datalen;
424         int shift = 0;
425
426         for (dptr += dataoff; dptr < limit; dptr++) {
427                 /* Find beginning of line */
428                 if (*dptr != '\r' && *dptr != '\n')
429                         continue;
430                 if (++dptr >= limit)
431                         break;
432                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
433                         if (++dptr >= limit)
434                                 break;
435                 }
436
437                 /* Skip continuation lines */
438                 if (*dptr == ' ' || *dptr == '\t')
439                         continue;
440
441                 /* Find header. Compact headers must be followed by a
442                  * non-alphabetic character to avoid mismatches. */
443                 if (limit - dptr >= hdr->len &&
444                     strnicmp(dptr, hdr->name, hdr->len) == 0)
445                         dptr += hdr->len;
446                 else if (hdr->cname && limit - dptr >= hdr->clen + 1 &&
447                          strnicmp(dptr, hdr->cname, hdr->clen) == 0 &&
448                          !isalpha(*(dptr + hdr->clen)))
449                         dptr += hdr->clen;
450                 else
451                         continue;
452
453                 /* Find and skip colon */
454                 dptr = sip_skip_whitespace(dptr, limit);
455                 if (dptr == NULL)
456                         break;
457                 if (*dptr != ':' || ++dptr >= limit)
458                         break;
459
460                 /* Skip whitespace after colon */
461                 dptr = sip_skip_whitespace(dptr, limit);
462                 if (dptr == NULL)
463                         break;
464
465                 *matchoff = dptr - start;
466                 if (hdr->search) {
467                         dptr = ct_sip_header_search(dptr, limit, hdr->search,
468                                                     hdr->slen);
469                         if (!dptr)
470                                 return -1;
471                         dptr += hdr->slen;
472                 }
473
474                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
475                 if (!*matchlen)
476                         return -1;
477                 *matchoff = dptr - start + shift;
478                 return 1;
479         }
480         return 0;
481 }
482 EXPORT_SYMBOL_GPL(ct_sip_get_header);
483
484 /* Get next header field in a list of comma separated values */
485 static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr,
486                               unsigned int dataoff, unsigned int datalen,
487                               enum sip_header_types type,
488                               unsigned int *matchoff, unsigned int *matchlen)
489 {
490         const struct sip_header *hdr = &ct_sip_hdrs[type];
491         const char *start = dptr, *limit = dptr + datalen;
492         int shift = 0;
493
494         dptr += dataoff;
495
496         dptr = ct_sip_header_search(dptr, limit, ",", strlen(","));
497         if (!dptr)
498                 return 0;
499
500         dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen);
501         if (!dptr)
502                 return 0;
503         dptr += hdr->slen;
504
505         *matchoff = dptr - start;
506         *matchlen = hdr->match_len(ct, dptr, limit, &shift);
507         if (!*matchlen)
508                 return -1;
509         *matchoff += shift;
510         return 1;
511 }
512
513 /* Walk through headers until a parsable one is found or no header of the
514  * given type is left. */
515 static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr,
516                                unsigned int dataoff, unsigned int datalen,
517                                enum sip_header_types type, int *in_header,
518                                unsigned int *matchoff, unsigned int *matchlen)
519 {
520         int ret;
521
522         if (in_header && *in_header) {
523                 while (1) {
524                         ret = ct_sip_next_header(ct, dptr, dataoff, datalen,
525                                                  type, matchoff, matchlen);
526                         if (ret > 0)
527                                 return ret;
528                         if (ret == 0)
529                                 break;
530                         dataoff += *matchoff;
531                 }
532                 *in_header = 0;
533         }
534
535         while (1) {
536                 ret = ct_sip_get_header(ct, dptr, dataoff, datalen,
537                                         type, matchoff, matchlen);
538                 if (ret > 0)
539                         break;
540                 if (ret == 0)
541                         return ret;
542                 dataoff += *matchoff;
543         }
544
545         if (in_header)
546                 *in_header = 1;
547         return 1;
548 }
549
550 /* Locate a SIP header, parse the URI and return the offset and length of
551  * the address as well as the address and port themselves. A stream of
552  * headers can be parsed by handing in a non-NULL datalen and in_header
553  * pointer.
554  */
555 int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
556                             unsigned int *dataoff, unsigned int datalen,
557                             enum sip_header_types type, int *in_header,
558                             unsigned int *matchoff, unsigned int *matchlen,
559                             union nf_inet_addr *addr, __be16 *port)
560 {
561         const char *c, *limit = dptr + datalen;
562         unsigned int p;
563         int ret;
564
565         ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen,
566                                   type, in_header, matchoff, matchlen);
567         WARN_ON(ret < 0);
568         if (ret == 0)
569                 return ret;
570
571         if (!sip_parse_addr(ct, dptr + *matchoff, &c, addr, limit, true))
572                 return -1;
573         if (*c == ':') {
574                 c++;
575                 p = simple_strtoul(c, (char **)&c, 10);
576                 if (p < 1024 || p > 65535)
577                         return -1;
578                 *port = htons(p);
579         } else
580                 *port = htons(SIP_PORT);
581
582         if (dataoff)
583                 *dataoff = c - dptr;
584         return 1;
585 }
586 EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
587
588 static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
589                               unsigned int dataoff, unsigned int datalen,
590                               const char *name,
591                               unsigned int *matchoff, unsigned int *matchlen)
592 {
593         const char *limit = dptr + datalen;
594         const char *start;
595         const 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         start += strlen(name);
605
606         end = ct_sip_header_search(start, limit, ";", strlen(";"));
607         if (!end)
608                 end = limit;
609
610         *matchoff = start - dptr;
611         *matchlen = end - start;
612         return 1;
613 }
614
615 /* Parse address from header parameter and return address, offset and length */
616 int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
617                                unsigned int dataoff, unsigned int datalen,
618                                const char *name,
619                                unsigned int *matchoff, unsigned int *matchlen,
620                                union nf_inet_addr *addr, bool delim)
621 {
622         const char *limit = dptr + datalen;
623         const char *start, *end;
624
625         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
626         if (!limit)
627                 limit = dptr + datalen;
628
629         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
630         if (!start)
631                 return 0;
632
633         start += strlen(name);
634         if (!sip_parse_addr(ct, start, &end, addr, limit, delim))
635                 return 0;
636         *matchoff = start - dptr;
637         *matchlen = end - start;
638         return 1;
639 }
640 EXPORT_SYMBOL_GPL(ct_sip_parse_address_param);
641
642 /* Parse numerical header parameter and return value, offset and length */
643 int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
644                                  unsigned int dataoff, unsigned int datalen,
645                                  const char *name,
646                                  unsigned int *matchoff, unsigned int *matchlen,
647                                  unsigned int *val)
648 {
649         const char *limit = dptr + datalen;
650         const char *start;
651         char *end;
652
653         limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
654         if (!limit)
655                 limit = dptr + datalen;
656
657         start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
658         if (!start)
659                 return 0;
660
661         start += strlen(name);
662         *val = simple_strtoul(start, &end, 0);
663         if (start == end)
664                 return 0;
665         if (matchoff && matchlen) {
666                 *matchoff = start - dptr;
667                 *matchlen = end - start;
668         }
669         return 1;
670 }
671 EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
672
673 static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
674                                   unsigned int dataoff, unsigned int datalen,
675                                   u8 *proto)
676 {
677         unsigned int matchoff, matchlen;
678
679         if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
680                                &matchoff, &matchlen)) {
681                 if (!strnicmp(dptr + matchoff, "TCP", strlen("TCP")))
682                         *proto = IPPROTO_TCP;
683                 else if (!strnicmp(dptr + matchoff, "UDP", strlen("UDP")))
684                         *proto = IPPROTO_UDP;
685                 else
686                         return 0;
687
688                 if (*proto != nf_ct_protonum(ct))
689                         return 0;
690         } else
691                 *proto = nf_ct_protonum(ct);
692
693         return 1;
694 }
695
696 static int sdp_parse_addr(const struct nf_conn *ct, const char *cp,
697                           const char **endp, union nf_inet_addr *addr,
698                           const char *limit)
699 {
700         const char *end;
701         int ret;
702
703         memset(addr, 0, sizeof(*addr));
704         switch (nf_ct_l3num(ct)) {
705         case AF_INET:
706                 ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
707                 break;
708         case AF_INET6:
709                 ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
710                 break;
711         default:
712                 BUG();
713         }
714
715         if (ret == 0)
716                 return 0;
717         if (endp)
718                 *endp = end;
719         return 1;
720 }
721
722 /* skip ip address. returns its length. */
723 static int sdp_addr_len(const struct nf_conn *ct, const char *dptr,
724                         const char *limit, int *shift)
725 {
726         union nf_inet_addr addr;
727         const char *aux = dptr;
728
729         if (!sdp_parse_addr(ct, dptr, &dptr, &addr, limit)) {
730                 pr_debug("ip: %s parse failed.!\n", dptr);
731                 return 0;
732         }
733
734         return dptr - aux;
735 }
736
737 /* SDP header parsing: a SDP session description contains an ordered set of
738  * headers, starting with a section containing general session parameters,
739  * optionally followed by multiple media descriptions.
740  *
741  * SDP headers always start at the beginning of a line. According to RFC 2327:
742  * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should
743  * be tolerant and also accept records terminated with a single newline
744  * character". We handle both cases.
745  */
746 static const struct sip_header ct_sdp_hdrs_v4[] = {
747         [SDP_HDR_VERSION]       = SDP_HDR("v=", NULL, digits_len),
748         [SDP_HDR_OWNER]         = SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
749         [SDP_HDR_CONNECTION]    = SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
750         [SDP_HDR_MEDIA]         = SDP_HDR("m=", NULL, media_len),
751 };
752
753 static const struct sip_header ct_sdp_hdrs_v6[] = {
754         [SDP_HDR_VERSION]       = SDP_HDR("v=", NULL, digits_len),
755         [SDP_HDR_OWNER]         = SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
756         [SDP_HDR_CONNECTION]    = SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
757         [SDP_HDR_MEDIA]         = SDP_HDR("m=", NULL, media_len),
758 };
759
760 /* Linear string search within SDP header values */
761 static const char *ct_sdp_header_search(const char *dptr, const char *limit,
762                                         const char *needle, unsigned int len)
763 {
764         for (limit -= len; dptr < limit; dptr++) {
765                 if (*dptr == '\r' || *dptr == '\n')
766                         break;
767                 if (strncmp(dptr, needle, len) == 0)
768                         return dptr;
769         }
770         return NULL;
771 }
772
773 /* Locate a SDP header (optionally a substring within the header value),
774  * optionally stopping at the first occurrence of the term header, parse
775  * it and return the offset and length of the data we're interested in.
776  */
777 int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
778                           unsigned int dataoff, unsigned int datalen,
779                           enum sdp_header_types type,
780                           enum sdp_header_types term,
781                           unsigned int *matchoff, unsigned int *matchlen)
782 {
783         const struct sip_header *hdrs, *hdr, *thdr;
784         const char *start = dptr, *limit = dptr + datalen;
785         int shift = 0;
786
787         hdrs = nf_ct_l3num(ct) == NFPROTO_IPV4 ? ct_sdp_hdrs_v4 : ct_sdp_hdrs_v6;
788         hdr = &hdrs[type];
789         thdr = &hdrs[term];
790
791         for (dptr += dataoff; dptr < limit; dptr++) {
792                 /* Find beginning of line */
793                 if (*dptr != '\r' && *dptr != '\n')
794                         continue;
795                 if (++dptr >= limit)
796                         break;
797                 if (*(dptr - 1) == '\r' && *dptr == '\n') {
798                         if (++dptr >= limit)
799                                 break;
800                 }
801
802                 if (term != SDP_HDR_UNSPEC &&
803                     limit - dptr >= thdr->len &&
804                     strnicmp(dptr, thdr->name, thdr->len) == 0)
805                         break;
806                 else if (limit - dptr >= hdr->len &&
807                          strnicmp(dptr, hdr->name, hdr->len) == 0)
808                         dptr += hdr->len;
809                 else
810                         continue;
811
812                 *matchoff = dptr - start;
813                 if (hdr->search) {
814                         dptr = ct_sdp_header_search(dptr, limit, hdr->search,
815                                                     hdr->slen);
816                         if (!dptr)
817                                 return -1;
818                         dptr += hdr->slen;
819                 }
820
821                 *matchlen = hdr->match_len(ct, dptr, limit, &shift);
822                 if (!*matchlen)
823                         return -1;
824                 *matchoff = dptr - start + shift;
825                 return 1;
826         }
827         return 0;
828 }
829 EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header);
830
831 static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
832                                  unsigned int dataoff, unsigned int datalen,
833                                  enum sdp_header_types type,
834                                  enum sdp_header_types term,
835                                  unsigned int *matchoff, unsigned int *matchlen,
836                                  union nf_inet_addr *addr)
837 {
838         int ret;
839
840         ret = ct_sip_get_sdp_header(ct, dptr, dataoff, datalen, type, term,
841                                     matchoff, matchlen);
842         if (ret <= 0)
843                 return ret;
844
845         if (!sdp_parse_addr(ct, dptr + *matchoff, NULL, addr,
846                             dptr + *matchoff + *matchlen))
847                 return -1;
848         return 1;
849 }
850
851 static int refresh_signalling_expectation(struct nf_conn *ct,
852                                           union nf_inet_addr *addr,
853                                           u8 proto, __be16 port,
854                                           unsigned int expires)
855 {
856         struct nf_conn_help *help = nfct_help(ct);
857         struct nf_conntrack_expect *exp;
858         struct hlist_node *next;
859         int found = 0;
860
861         spin_lock_bh(&nf_conntrack_lock);
862         hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
863                 if (exp->class != SIP_EXPECT_SIGNALLING ||
864                     !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
865                     exp->tuple.dst.protonum != proto ||
866                     exp->tuple.dst.u.udp.port != port)
867                         continue;
868                 if (!del_timer(&exp->timeout))
869                         continue;
870                 exp->flags &= ~NF_CT_EXPECT_INACTIVE;
871                 exp->timeout.expires = jiffies + expires * HZ;
872                 add_timer(&exp->timeout);
873                 found = 1;
874                 break;
875         }
876         spin_unlock_bh(&nf_conntrack_lock);
877         return found;
878 }
879
880 static void flush_expectations(struct nf_conn *ct, bool media)
881 {
882         struct nf_conn_help *help = nfct_help(ct);
883         struct nf_conntrack_expect *exp;
884         struct hlist_node *next;
885
886         spin_lock_bh(&nf_conntrack_lock);
887         hlist_for_each_entry_safe(exp, next, &help->expectations, lnode) {
888                 if ((exp->class != SIP_EXPECT_SIGNALLING) ^ media)
889                         continue;
890                 if (!del_timer(&exp->timeout))
891                         continue;
892                 nf_ct_unlink_expect(exp);
893                 nf_ct_expect_put(exp);
894                 if (!media)
895                         break;
896         }
897         spin_unlock_bh(&nf_conntrack_lock);
898 }
899
900 static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
901                                  unsigned int dataoff,
902                                  const char **dptr, unsigned int *datalen,
903                                  union nf_inet_addr *daddr, __be16 port,
904                                  enum sip_expectation_classes class,
905                                  unsigned int mediaoff, unsigned int medialen)
906 {
907         struct nf_conntrack_expect *exp, *rtp_exp, *rtcp_exp;
908         enum ip_conntrack_info ctinfo;
909         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
910         struct net *net = nf_ct_net(ct);
911         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
912         union nf_inet_addr *saddr;
913         struct nf_conntrack_tuple tuple;
914         int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
915         u_int16_t base_port;
916         __be16 rtp_port, rtcp_port;
917         typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port;
918         typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media;
919
920         saddr = NULL;
921         if (sip_direct_media) {
922                 if (!nf_inet_addr_cmp(daddr, &ct->tuplehash[dir].tuple.src.u3))
923                         return NF_ACCEPT;
924                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
925         }
926
927         /* We need to check whether the registration exists before attempting
928          * to register it since we can see the same media description multiple
929          * times on different connections in case multiple endpoints receive
930          * the same call.
931          *
932          * RTP optimization: if we find a matching media channel expectation
933          * and both the expectation and this connection are SNATed, we assume
934          * both sides can reach each other directly and use the final
935          * destination address from the expectation. We still need to keep
936          * the NATed expectations for media that might arrive from the
937          * outside, and additionally need to expect the direct RTP stream
938          * in case it passes through us even without NAT.
939          */
940         memset(&tuple, 0, sizeof(tuple));
941         if (saddr)
942                 tuple.src.u3 = *saddr;
943         tuple.src.l3num         = nf_ct_l3num(ct);
944         tuple.dst.protonum      = IPPROTO_UDP;
945         tuple.dst.u3            = *daddr;
946         tuple.dst.u.udp.port    = port;
947
948         rcu_read_lock();
949         do {
950                 exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
951
952                 if (!exp || exp->master == ct ||
953                     nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
954                     exp->class != class)
955                         break;
956 #ifdef CONFIG_NF_NAT_NEEDED
957                 if (!direct_rtp &&
958                     (!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
959                      exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
960                     ct->status & IPS_NAT_MASK) {
961                         *daddr                  = exp->saved_addr;
962                         tuple.dst.u3            = exp->saved_addr;
963                         tuple.dst.u.udp.port    = exp->saved_proto.udp.port;
964                         direct_rtp = 1;
965                 } else
966 #endif
967                         skip_expect = 1;
968         } while (!skip_expect);
969         rcu_read_unlock();
970
971         base_port = ntohs(tuple.dst.u.udp.port) & ~1;
972         rtp_port = htons(base_port);
973         rtcp_port = htons(base_port + 1);
974
975         if (direct_rtp) {
976                 nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook);
977                 if (nf_nat_sdp_port &&
978                     !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
979                                      mediaoff, medialen, ntohs(rtp_port)))
980                         goto err1;
981         }
982
983         if (skip_expect)
984                 return NF_ACCEPT;
985
986         rtp_exp = nf_ct_expect_alloc(ct);
987         if (rtp_exp == NULL)
988                 goto err1;
989         nf_ct_expect_init(rtp_exp, class, nf_ct_l3num(ct), saddr, daddr,
990                           IPPROTO_UDP, NULL, &rtp_port);
991
992         rtcp_exp = nf_ct_expect_alloc(ct);
993         if (rtcp_exp == NULL)
994                 goto err2;
995         nf_ct_expect_init(rtcp_exp, class, nf_ct_l3num(ct), saddr, daddr,
996                           IPPROTO_UDP, NULL, &rtcp_port);
997
998         nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
999         if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
1000                 ret = nf_nat_sdp_media(skb, protoff, dataoff, dptr, datalen,
1001                                        rtp_exp, rtcp_exp,
1002                                        mediaoff, medialen, daddr);
1003         else {
1004                 if (nf_ct_expect_related(rtp_exp) == 0) {
1005                         if (nf_ct_expect_related(rtcp_exp) != 0)
1006                                 nf_ct_unexpect_related(rtp_exp);
1007                         else
1008                                 ret = NF_ACCEPT;
1009                 }
1010         }
1011         nf_ct_expect_put(rtcp_exp);
1012 err2:
1013         nf_ct_expect_put(rtp_exp);
1014 err1:
1015         return ret;
1016 }
1017
1018 static const struct sdp_media_type sdp_media_types[] = {
1019         SDP_MEDIA_TYPE("audio ", SIP_EXPECT_AUDIO),
1020         SDP_MEDIA_TYPE("video ", SIP_EXPECT_VIDEO),
1021         SDP_MEDIA_TYPE("image ", SIP_EXPECT_IMAGE),
1022 };
1023
1024 static const struct sdp_media_type *sdp_media_type(const char *dptr,
1025                                                    unsigned int matchoff,
1026                                                    unsigned int matchlen)
1027 {
1028         const struct sdp_media_type *t;
1029         unsigned int i;
1030
1031         for (i = 0; i < ARRAY_SIZE(sdp_media_types); i++) {
1032                 t = &sdp_media_types[i];
1033                 if (matchlen < t->len ||
1034                     strncmp(dptr + matchoff, t->name, t->len))
1035                         continue;
1036                 return t;
1037         }
1038         return NULL;
1039 }
1040
1041 static int process_sdp(struct sk_buff *skb, unsigned int protoff,
1042                        unsigned int dataoff,
1043                        const char **dptr, unsigned int *datalen,
1044                        unsigned int cseq)
1045 {
1046         enum ip_conntrack_info ctinfo;
1047         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1048         unsigned int matchoff, matchlen;
1049         unsigned int mediaoff, medialen;
1050         unsigned int sdpoff;
1051         unsigned int caddr_len, maddr_len;
1052         unsigned int i;
1053         union nf_inet_addr caddr, maddr, rtp_addr;
1054         unsigned int port;
1055         const struct sdp_media_type *t;
1056         int ret = NF_ACCEPT;
1057         typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr;
1058         typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session;
1059
1060         nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook);
1061
1062         /* Find beginning of session description */
1063         if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
1064                                   SDP_HDR_VERSION, SDP_HDR_UNSPEC,
1065                                   &matchoff, &matchlen) <= 0)
1066                 return NF_ACCEPT;
1067         sdpoff = matchoff;
1068
1069         /* The connection information is contained in the session description
1070          * and/or once per media description. The first media description marks
1071          * the end of the session description. */
1072         caddr_len = 0;
1073         if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
1074                                   SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1075                                   &matchoff, &matchlen, &caddr) > 0)
1076                 caddr_len = matchlen;
1077
1078         mediaoff = sdpoff;
1079         for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) {
1080                 if (ct_sip_get_sdp_header(ct, *dptr, mediaoff, *datalen,
1081                                           SDP_HDR_MEDIA, SDP_HDR_UNSPEC,
1082                                           &mediaoff, &medialen) <= 0)
1083                         break;
1084
1085                 /* Get media type and port number. A media port value of zero
1086                  * indicates an inactive stream. */
1087                 t = sdp_media_type(*dptr, mediaoff, medialen);
1088                 if (!t) {
1089                         mediaoff += medialen;
1090                         continue;
1091                 }
1092                 mediaoff += t->len;
1093                 medialen -= t->len;
1094
1095                 port = simple_strtoul(*dptr + mediaoff, NULL, 10);
1096                 if (port == 0)
1097                         continue;
1098                 if (port < 1024 || port > 65535) {
1099                         nf_ct_helper_log(skb, ct, "wrong port %u", port);
1100                         return NF_DROP;
1101                 }
1102
1103                 /* The media description overrides the session description. */
1104                 maddr_len = 0;
1105                 if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
1106                                           SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1107                                           &matchoff, &matchlen, &maddr) > 0) {
1108                         maddr_len = matchlen;
1109                         memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
1110                 } else if (caddr_len)
1111                         memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
1112                 else {
1113                         nf_ct_helper_log(skb, ct, "cannot parse SDP message");
1114                         return NF_DROP;
1115                 }
1116
1117                 ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
1118                                             dptr, datalen,
1119                                             &rtp_addr, htons(port), t->class,
1120                                             mediaoff, medialen);
1121                 if (ret != NF_ACCEPT) {
1122                         nf_ct_helper_log(skb, ct,
1123                                          "cannot add expectation for voice");
1124                         return ret;
1125                 }
1126
1127                 /* Update media connection address if present */
1128                 if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
1129                         ret = nf_nat_sdp_addr(skb, protoff, dataoff,
1130                                               dptr, datalen, mediaoff,
1131                                               SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
1132                                               &rtp_addr);
1133                         if (ret != NF_ACCEPT) {
1134                                 nf_ct_helper_log(skb, ct, "cannot mangle SDP");
1135                                 return ret;
1136                         }
1137                 }
1138                 i++;
1139         }
1140
1141         /* Update session connection and owner addresses */
1142         nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook);
1143         if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK)
1144                 ret = nf_nat_sdp_session(skb, protoff, dataoff,
1145                                          dptr, datalen, sdpoff, &rtp_addr);
1146
1147         return ret;
1148 }
1149 static int process_invite_response(struct sk_buff *skb, unsigned int protoff,
1150                                    unsigned int dataoff,
1151                                    const char **dptr, unsigned int *datalen,
1152                                    unsigned int cseq, unsigned int code)
1153 {
1154         enum ip_conntrack_info ctinfo;
1155         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1156         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1157
1158         if ((code >= 100 && code <= 199) ||
1159             (code >= 200 && code <= 299))
1160                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1161         else if (ct_sip_info->invite_cseq == cseq)
1162                 flush_expectations(ct, true);
1163         return NF_ACCEPT;
1164 }
1165
1166 static int process_update_response(struct sk_buff *skb, unsigned int protoff,
1167                                    unsigned int dataoff,
1168                                    const char **dptr, unsigned int *datalen,
1169                                    unsigned int cseq, unsigned int code)
1170 {
1171         enum ip_conntrack_info ctinfo;
1172         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1173         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1174
1175         if ((code >= 100 && code <= 199) ||
1176             (code >= 200 && code <= 299))
1177                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1178         else if (ct_sip_info->invite_cseq == cseq)
1179                 flush_expectations(ct, true);
1180         return NF_ACCEPT;
1181 }
1182
1183 static int process_prack_response(struct sk_buff *skb, unsigned int protoff,
1184                                   unsigned int dataoff,
1185                                   const char **dptr, unsigned int *datalen,
1186                                   unsigned int cseq, unsigned int code)
1187 {
1188         enum ip_conntrack_info ctinfo;
1189         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1190         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1191
1192         if ((code >= 100 && code <= 199) ||
1193             (code >= 200 && code <= 299))
1194                 return process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1195         else if (ct_sip_info->invite_cseq == cseq)
1196                 flush_expectations(ct, true);
1197         return NF_ACCEPT;
1198 }
1199
1200 static int process_invite_request(struct sk_buff *skb, unsigned int protoff,
1201                                   unsigned int dataoff,
1202                                   const char **dptr, unsigned int *datalen,
1203                                   unsigned int cseq)
1204 {
1205         enum ip_conntrack_info ctinfo;
1206         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1207         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1208         unsigned int ret;
1209
1210         flush_expectations(ct, true);
1211         ret = process_sdp(skb, protoff, dataoff, dptr, datalen, cseq);
1212         if (ret == NF_ACCEPT)
1213                 ct_sip_info->invite_cseq = cseq;
1214         return ret;
1215 }
1216
1217 static int process_bye_request(struct sk_buff *skb, unsigned int protoff,
1218                                unsigned int dataoff,
1219                                const char **dptr, unsigned int *datalen,
1220                                unsigned int cseq)
1221 {
1222         enum ip_conntrack_info ctinfo;
1223         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1224
1225         flush_expectations(ct, true);
1226         return NF_ACCEPT;
1227 }
1228
1229 /* Parse a REGISTER request and create a permanent expectation for incoming
1230  * signalling connections. The expectation is marked inactive and is activated
1231  * when receiving a response indicating success from the registrar.
1232  */
1233 static int process_register_request(struct sk_buff *skb, unsigned int protoff,
1234                                     unsigned int dataoff,
1235                                     const char **dptr, unsigned int *datalen,
1236                                     unsigned int cseq)
1237 {
1238         enum ip_conntrack_info ctinfo;
1239         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1240         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1241         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1242         unsigned int matchoff, matchlen;
1243         struct nf_conntrack_expect *exp;
1244         union nf_inet_addr *saddr, daddr;
1245         __be16 port;
1246         u8 proto;
1247         unsigned int expires = 0;
1248         int ret;
1249         typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
1250
1251         /* Expected connections can not register again. */
1252         if (ct->status & IPS_EXPECTED)
1253                 return NF_ACCEPT;
1254
1255         /* We must check the expiration time: a value of zero signals the
1256          * registrar to release the binding. We'll remove our expectation
1257          * when receiving the new bindings in the response, but we don't
1258          * want to create new ones.
1259          *
1260          * The expiration time may be contained in Expires: header, the
1261          * Contact: header parameters or the URI parameters.
1262          */
1263         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1264                               &matchoff, &matchlen) > 0)
1265                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1266
1267         ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1268                                       SIP_HDR_CONTACT, NULL,
1269                                       &matchoff, &matchlen, &daddr, &port);
1270         if (ret < 0) {
1271                 nf_ct_helper_log(skb, ct, "cannot parse contact");
1272                 return NF_DROP;
1273         } else if (ret == 0)
1274                 return NF_ACCEPT;
1275
1276         /* We don't support third-party registrations */
1277         if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
1278                 return NF_ACCEPT;
1279
1280         if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
1281                                    &proto) == 0)
1282                 return NF_ACCEPT;
1283
1284         if (ct_sip_parse_numerical_param(ct, *dptr,
1285                                          matchoff + matchlen, *datalen,
1286                                          "expires=", NULL, NULL, &expires) < 0) {
1287                 nf_ct_helper_log(skb, ct, "cannot parse expires");
1288                 return NF_DROP;
1289         }
1290
1291         if (expires == 0) {
1292                 ret = NF_ACCEPT;
1293                 goto store_cseq;
1294         }
1295
1296         exp = nf_ct_expect_alloc(ct);
1297         if (!exp) {
1298                 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
1299                 return NF_DROP;
1300         }
1301
1302         saddr = NULL;
1303         if (sip_direct_signalling)
1304                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
1305
1306         nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
1307                           saddr, &daddr, proto, NULL, &port);
1308         exp->timeout.expires = sip_timeout * HZ;
1309         exp->helper = nfct_help(ct)->helper;
1310         exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
1311
1312         nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
1313         if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
1314                 ret = nf_nat_sip_expect(skb, protoff, dataoff, dptr, datalen,
1315                                         exp, matchoff, matchlen);
1316         else {
1317                 if (nf_ct_expect_related(exp) != 0) {
1318                         nf_ct_helper_log(skb, ct, "cannot add expectation");
1319                         ret = NF_DROP;
1320                 } else
1321                         ret = NF_ACCEPT;
1322         }
1323         nf_ct_expect_put(exp);
1324
1325 store_cseq:
1326         if (ret == NF_ACCEPT)
1327                 ct_sip_info->register_cseq = cseq;
1328         return ret;
1329 }
1330
1331 static int process_register_response(struct sk_buff *skb, unsigned int protoff,
1332                                      unsigned int dataoff,
1333                                      const char **dptr, unsigned int *datalen,
1334                                      unsigned int cseq, unsigned int code)
1335 {
1336         enum ip_conntrack_info ctinfo;
1337         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1338         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1339         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1340         union nf_inet_addr addr;
1341         __be16 port;
1342         u8 proto;
1343         unsigned int matchoff, matchlen, coff = 0;
1344         unsigned int expires = 0;
1345         int in_contact = 0, ret;
1346
1347         /* According to RFC 3261, "UAs MUST NOT send a new registration until
1348          * they have received a final response from the registrar for the
1349          * previous one or the previous REGISTER request has timed out".
1350          *
1351          * However, some servers fail to detect retransmissions and send late
1352          * responses, so we store the sequence number of the last valid
1353          * request and compare it here.
1354          */
1355         if (ct_sip_info->register_cseq != cseq)
1356                 return NF_ACCEPT;
1357
1358         if (code >= 100 && code <= 199)
1359                 return NF_ACCEPT;
1360         if (code < 200 || code > 299)
1361                 goto flush;
1362
1363         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_EXPIRES,
1364                               &matchoff, &matchlen) > 0)
1365                 expires = simple_strtoul(*dptr + matchoff, NULL, 10);
1366
1367         while (1) {
1368                 unsigned int c_expires = expires;
1369
1370                 ret = ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
1371                                               SIP_HDR_CONTACT, &in_contact,
1372                                               &matchoff, &matchlen,
1373                                               &addr, &port);
1374                 if (ret < 0) {
1375                         nf_ct_helper_log(skb, ct, "cannot parse contact");
1376                         return NF_DROP;
1377                 } else if (ret == 0)
1378                         break;
1379
1380                 /* We don't support third-party registrations */
1381                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
1382                         continue;
1383
1384                 if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
1385                                            *datalen, &proto) == 0)
1386                         continue;
1387
1388                 ret = ct_sip_parse_numerical_param(ct, *dptr,
1389                                                    matchoff + matchlen,
1390                                                    *datalen, "expires=",
1391                                                    NULL, NULL, &c_expires);
1392                 if (ret < 0) {
1393                         nf_ct_helper_log(skb, ct, "cannot parse expires");
1394                         return NF_DROP;
1395                 }
1396                 if (c_expires == 0)
1397                         break;
1398                 if (refresh_signalling_expectation(ct, &addr, proto, port,
1399                                                    c_expires))
1400                         return NF_ACCEPT;
1401         }
1402
1403 flush:
1404         flush_expectations(ct, false);
1405         return NF_ACCEPT;
1406 }
1407
1408 static const struct sip_handler sip_handlers[] = {
1409         SIP_HANDLER("INVITE", process_invite_request, process_invite_response),
1410         SIP_HANDLER("UPDATE", process_sdp, process_update_response),
1411         SIP_HANDLER("ACK", process_sdp, NULL),
1412         SIP_HANDLER("PRACK", process_sdp, process_prack_response),
1413         SIP_HANDLER("BYE", process_bye_request, NULL),
1414         SIP_HANDLER("REGISTER", process_register_request, process_register_response),
1415 };
1416
1417 static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
1418                                 unsigned int dataoff,
1419                                 const char **dptr, unsigned int *datalen)
1420 {
1421         enum ip_conntrack_info ctinfo;
1422         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1423         unsigned int matchoff, matchlen, matchend;
1424         unsigned int code, cseq, i;
1425
1426         if (*datalen < strlen("SIP/2.0 200"))
1427                 return NF_ACCEPT;
1428         code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
1429         if (!code) {
1430                 nf_ct_helper_log(skb, ct, "cannot get code");
1431                 return NF_DROP;
1432         }
1433
1434         if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1435                               &matchoff, &matchlen) <= 0) {
1436                 nf_ct_helper_log(skb, ct, "cannot parse cseq");
1437                 return NF_DROP;
1438         }
1439         cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1440         if (!cseq) {
1441                 nf_ct_helper_log(skb, ct, "cannot get cseq");
1442                 return NF_DROP;
1443         }
1444         matchend = matchoff + matchlen + 1;
1445
1446         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1447                 const struct sip_handler *handler;
1448
1449                 handler = &sip_handlers[i];
1450                 if (handler->response == NULL)
1451                         continue;
1452                 if (*datalen < matchend + handler->len ||
1453                     strnicmp(*dptr + matchend, handler->method, handler->len))
1454                         continue;
1455                 return handler->response(skb, protoff, dataoff, dptr, datalen,
1456                                          cseq, code);
1457         }
1458         return NF_ACCEPT;
1459 }
1460
1461 static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
1462                                unsigned int dataoff,
1463                                const char **dptr, unsigned int *datalen)
1464 {
1465         enum ip_conntrack_info ctinfo;
1466         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
1467         struct nf_ct_sip_master *ct_sip_info = nfct_help_data(ct);
1468         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
1469         unsigned int matchoff, matchlen;
1470         unsigned int cseq, i;
1471         union nf_inet_addr addr;
1472         __be16 port;
1473
1474         /* Many Cisco IP phones use a high source port for SIP requests, but
1475          * listen for the response on port 5060.  If we are the local
1476          * router for one of these phones, save the port number from the
1477          * Via: header so that nf_nat_sip can redirect the responses to
1478          * the correct port.
1479          */
1480         if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
1481                                     SIP_HDR_VIA_UDP, NULL, &matchoff,
1482                                     &matchlen, &addr, &port) > 0 &&
1483             port != ct->tuplehash[dir].tuple.src.u.udp.port &&
1484             nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3))
1485                 ct_sip_info->forced_dport = port;
1486
1487         for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
1488                 const struct sip_handler *handler;
1489
1490                 handler = &sip_handlers[i];
1491                 if (handler->request == NULL)
1492                         continue;
1493                 if (*datalen < handler->len ||
1494                     strnicmp(*dptr, handler->method, handler->len))
1495                         continue;
1496
1497                 if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
1498                                       &matchoff, &matchlen) <= 0) {
1499                         nf_ct_helper_log(skb, ct, "cannot parse cseq");
1500                         return NF_DROP;
1501                 }
1502                 cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
1503                 if (!cseq) {
1504                         nf_ct_helper_log(skb, ct, "cannot get cseq");
1505                         return NF_DROP;
1506                 }
1507
1508                 return handler->request(skb, protoff, dataoff, dptr, datalen,
1509                                         cseq);
1510         }
1511         return NF_ACCEPT;
1512 }
1513
1514 static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
1515                            unsigned int protoff, unsigned int dataoff,
1516                            const char **dptr, unsigned int *datalen)
1517 {
1518         typeof(nf_nat_sip_hook) nf_nat_sip;
1519         int ret;
1520
1521         if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
1522                 ret = process_sip_request(skb, protoff, dataoff, dptr, datalen);
1523         else
1524                 ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
1525
1526         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1527                 nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
1528                 if (nf_nat_sip && !nf_nat_sip(skb, protoff, dataoff,
1529                                               dptr, datalen)) {
1530                         nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
1531                         ret = NF_DROP;
1532                 }
1533         }
1534
1535         return ret;
1536 }
1537
1538 static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
1539                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1540 {
1541         struct tcphdr *th, _tcph;
1542         unsigned int dataoff, datalen;
1543         unsigned int matchoff, matchlen, clen;
1544         unsigned int msglen, origlen;
1545         const char *dptr, *end;
1546         s16 diff, tdiff = 0;
1547         int ret = NF_ACCEPT;
1548         bool term;
1549         typeof(nf_nat_sip_seq_adjust_hook) nf_nat_sip_seq_adjust;
1550
1551         if (ctinfo != IP_CT_ESTABLISHED &&
1552             ctinfo != IP_CT_ESTABLISHED_REPLY)
1553                 return NF_ACCEPT;
1554
1555         /* No Data ? */
1556         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
1557         if (th == NULL)
1558                 return NF_ACCEPT;
1559         dataoff = protoff + th->doff * 4;
1560         if (dataoff >= skb->len)
1561                 return NF_ACCEPT;
1562
1563         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1564
1565         if (unlikely(skb_linearize(skb)))
1566                 return NF_DROP;
1567
1568         dptr = skb->data + dataoff;
1569         datalen = skb->len - dataoff;
1570         if (datalen < strlen("SIP/2.0 200"))
1571                 return NF_ACCEPT;
1572
1573         while (1) {
1574                 if (ct_sip_get_header(ct, dptr, 0, datalen,
1575                                       SIP_HDR_CONTENT_LENGTH,
1576                                       &matchoff, &matchlen) <= 0)
1577                         break;
1578
1579                 clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
1580                 if (dptr + matchoff == end)
1581                         break;
1582
1583                 term = false;
1584                 for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) {
1585                         if (end[0] == '\r' && end[1] == '\n' &&
1586                             end[2] == '\r' && end[3] == '\n') {
1587                                 term = true;
1588                                 break;
1589                         }
1590                 }
1591                 if (!term)
1592                         break;
1593                 end += strlen("\r\n\r\n") + clen;
1594
1595                 msglen = origlen = end - dptr;
1596                 if (msglen > datalen) {
1597                         nf_ct_helper_log(skb, ct, "incomplete/bad SIP message");
1598                         return NF_DROP;
1599                 }
1600
1601                 ret = process_sip_msg(skb, ct, protoff, dataoff,
1602                                       &dptr, &msglen);
1603                 /* process_sip_* functions report why this packet is dropped */
1604                 if (ret != NF_ACCEPT)
1605                         break;
1606                 diff     = msglen - origlen;
1607                 tdiff   += diff;
1608
1609                 dataoff += msglen;
1610                 dptr    += msglen;
1611                 datalen  = datalen + diff - msglen;
1612         }
1613
1614         if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
1615                 nf_nat_sip_seq_adjust = rcu_dereference(nf_nat_sip_seq_adjust_hook);
1616                 if (nf_nat_sip_seq_adjust)
1617                         nf_nat_sip_seq_adjust(skb, protoff, tdiff);
1618         }
1619
1620         return ret;
1621 }
1622
1623 static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
1624                         struct nf_conn *ct, enum ip_conntrack_info ctinfo)
1625 {
1626         unsigned int dataoff, datalen;
1627         const char *dptr;
1628
1629         /* No Data ? */
1630         dataoff = protoff + sizeof(struct udphdr);
1631         if (dataoff >= skb->len)
1632                 return NF_ACCEPT;
1633
1634         nf_ct_refresh(ct, skb, sip_timeout * HZ);
1635
1636         if (unlikely(skb_linearize(skb)))
1637                 return NF_DROP;
1638
1639         dptr = skb->data + dataoff;
1640         datalen = skb->len - dataoff;
1641         if (datalen < strlen("SIP/2.0 200"))
1642                 return NF_ACCEPT;
1643
1644         return process_sip_msg(skb, ct, protoff, dataoff, &dptr, &datalen);
1645 }
1646
1647 static struct nf_conntrack_helper sip[MAX_PORTS][4] __read_mostly;
1648
1649 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
1650         [SIP_EXPECT_SIGNALLING] = {
1651                 .name           = "signalling",
1652                 .max_expected   = 1,
1653                 .timeout        = 3 * 60,
1654         },
1655         [SIP_EXPECT_AUDIO] = {
1656                 .name           = "audio",
1657                 .max_expected   = 2 * IP_CT_DIR_MAX,
1658                 .timeout        = 3 * 60,
1659         },
1660         [SIP_EXPECT_VIDEO] = {
1661                 .name           = "video",
1662                 .max_expected   = 2 * IP_CT_DIR_MAX,
1663                 .timeout        = 3 * 60,
1664         },
1665         [SIP_EXPECT_IMAGE] = {
1666                 .name           = "image",
1667                 .max_expected   = IP_CT_DIR_MAX,
1668                 .timeout        = 3 * 60,
1669         },
1670 };
1671
1672 static void nf_conntrack_sip_fini(void)
1673 {
1674         int i, j;
1675
1676         for (i = 0; i < ports_c; i++) {
1677                 for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
1678                         if (sip[i][j].me == NULL)
1679                                 continue;
1680                         nf_conntrack_helper_unregister(&sip[i][j]);
1681                 }
1682         }
1683 }
1684
1685 static int __init nf_conntrack_sip_init(void)
1686 {
1687         int i, j, ret;
1688
1689         if (ports_c == 0)
1690                 ports[ports_c++] = SIP_PORT;
1691
1692         for (i = 0; i < ports_c; i++) {
1693                 memset(&sip[i], 0, sizeof(sip[i]));
1694
1695                 sip[i][0].tuple.src.l3num = AF_INET;
1696                 sip[i][0].tuple.dst.protonum = IPPROTO_UDP;
1697                 sip[i][0].help = sip_help_udp;
1698                 sip[i][1].tuple.src.l3num = AF_INET;
1699                 sip[i][1].tuple.dst.protonum = IPPROTO_TCP;
1700                 sip[i][1].help = sip_help_tcp;
1701
1702                 sip[i][2].tuple.src.l3num = AF_INET6;
1703                 sip[i][2].tuple.dst.protonum = IPPROTO_UDP;
1704                 sip[i][2].help = sip_help_udp;
1705                 sip[i][3].tuple.src.l3num = AF_INET6;
1706                 sip[i][3].tuple.dst.protonum = IPPROTO_TCP;
1707                 sip[i][3].help = sip_help_tcp;
1708
1709                 for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
1710                         sip[i][j].data_len = sizeof(struct nf_ct_sip_master);
1711                         sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
1712                         sip[i][j].expect_policy = sip_exp_policy;
1713                         sip[i][j].expect_class_max = SIP_EXPECT_MAX;
1714                         sip[i][j].me = THIS_MODULE;
1715
1716                         if (ports[i] == SIP_PORT)
1717                                 sprintf(sip[i][j].name, "sip");
1718                         else
1719                                 sprintf(sip[i][j].name, "sip-%u", i);
1720
1721                         pr_debug("port #%u: %u\n", i, ports[i]);
1722
1723                         ret = nf_conntrack_helper_register(&sip[i][j]);
1724                         if (ret) {
1725                                 printk(KERN_ERR "nf_ct_sip: failed to register"
1726                                        " helper for pf: %u port: %u\n",
1727                                        sip[i][j].tuple.src.l3num, ports[i]);
1728                                 nf_conntrack_sip_fini();
1729                                 return ret;
1730                         }
1731                 }
1732         }
1733         return 0;
1734 }
1735
1736 module_init(nf_conntrack_sip_init);
1737 module_exit(nf_conntrack_sip_fini);