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[POWERPC] Make soft_enabled irqs preempt safe
[usb.git] / net / ipv4 / netfilter / ip_conntrack_sip.c
blob3a26d63eed88926b81baf934a002314c823217b9
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 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11 #include <linux/module.h>
12 #include <linux/ctype.h>
13 #include <linux/skbuff.h>
14 #include <linux/in.h>
15 #include <linux/ip.h>
16 #include <linux/udp.h>
17
18 #include <linux/netfilter.h>
19 #include <linux/netfilter_ipv4.h>
20 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
21 #include <linux/netfilter_ipv4/ip_conntrack_sip.h>
22
23 #if 0
24 #define DEBUGP printk
25 #else
26 #define DEBUGP(format, args...)
27 #endif
28
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
31 MODULE_DESCRIPTION("SIP connection tracking helper");
32
33 #define MAX_PORTS 8
34 static unsigned short ports[MAX_PORTS];
35 static int ports_c;
36 module_param_array(ports, ushort, &ports_c, 0400);
37 MODULE_PARM_DESC(ports, "port numbers of sip servers");
38
39 static unsigned int sip_timeout = SIP_TIMEOUT;
40 module_param(sip_timeout, uint, 0600);
41 MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
42
43 unsigned int (*ip_nat_sip_hook)(struct sk_buff **pskb,
44 enum ip_conntrack_info ctinfo,
45 struct ip_conntrack *ct,
46 const char **dptr);
47 EXPORT_SYMBOL_GPL(ip_nat_sip_hook);
48
49 unsigned int (*ip_nat_sdp_hook)(struct sk_buff **pskb,
50 enum ip_conntrack_info ctinfo,
51 struct ip_conntrack_expect *exp,
52 const char *dptr);
53 EXPORT_SYMBOL_GPL(ip_nat_sdp_hook);
54
55 static int digits_len(const char *dptr, const char *limit, int *shift);
56 static int epaddr_len(const char *dptr, const char *limit, int *shift);
57 static int skp_digits_len(const char *dptr, const char *limit, int *shift);
58 static int skp_epaddr_len(const char *dptr, const char *limit, int *shift);
59
60 struct sip_header_nfo {
61 const char *lname;
62 const char *sname;
63 const char *ln_str;
64 size_t lnlen;
65 size_t snlen;
66 size_t ln_strlen;
67 int case_sensitive;
68 int (*match_len)(const char *, const char *, int *);
69 };
70
71 static struct sip_header_nfo ct_sip_hdrs[] = {
72 [POS_REG_REQ_URI] = { /* SIP REGISTER request URI */
73 .lname = "sip:",
74 .lnlen = sizeof("sip:") - 1,
75 .ln_str = ":",
76 .ln_strlen = sizeof(":") - 1,
77 .match_len = epaddr_len
78 },
79 [POS_REQ_URI] = { /* SIP request URI */
80 .lname = "sip:",
81 .lnlen = sizeof("sip:") - 1,
82 .ln_str = "@",
83 .ln_strlen = sizeof("@") - 1,
84 .match_len = epaddr_len
85 },
86 [POS_FROM] = { /* SIP From header */
87 .lname = "From:",
88 .lnlen = sizeof("From:") - 1,
89 .sname = "\r\nf:",
90 .snlen = sizeof("\r\nf:") - 1,
91 .ln_str = "sip:",
92 .ln_strlen = sizeof("sip:") - 1,
93 .match_len = skp_epaddr_len,
94 },
95 [POS_TO] = { /* SIP To header */
96 .lname = "To:",
97 .lnlen = sizeof("To:") - 1,
98 .sname = "\r\nt:",
99 .snlen = sizeof("\r\nt:") - 1,
100 .ln_str = "sip:",
101 .ln_strlen = sizeof("sip:") - 1,
102 .match_len = skp_epaddr_len,
103 },
104 [POS_VIA] = { /* SIP Via header */
105 .lname = "Via:",
106 .lnlen = sizeof("Via:") - 1,
107 .sname = "\r\nv:",
108 .snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
109 .ln_str = "UDP ",
110 .ln_strlen = sizeof("UDP ") - 1,
111 .match_len = epaddr_len,
112 },
113 [POS_CONTACT] = { /* SIP Contact header */
114 .lname = "Contact:",
115 .lnlen = sizeof("Contact:") - 1,
116 .sname = "\r\nm:",
117 .snlen = sizeof("\r\nm:") - 1,
118 .ln_str = "sip:",
119 .ln_strlen = sizeof("sip:") - 1,
120 .match_len = skp_epaddr_len
121 },
122 [POS_CONTENT] = { /* SIP Content length header */
123 .lname = "Content-Length:",
124 .lnlen = sizeof("Content-Length:") - 1,
125 .sname = "\r\nl:",
126 .snlen = sizeof("\r\nl:") - 1,
127 .ln_str = ":",
128 .ln_strlen = sizeof(":") - 1,
129 .match_len = skp_digits_len
130 },
131 [POS_MEDIA] = { /* SDP media info */
132 .case_sensitive = 1,
133 .lname = "\nm=",
134 .lnlen = sizeof("\nm=") - 1,
135 .sname = "\rm=",
136 .snlen = sizeof("\rm=") - 1,
137 .ln_str = "audio ",
138 .ln_strlen = sizeof("audio ") - 1,
139 .match_len = digits_len
140 },
141 [POS_OWNER] = { /* SDP owner address*/
142 .case_sensitive = 1,
143 .lname = "\no=",
144 .lnlen = sizeof("\no=") - 1,
145 .sname = "\ro=",
146 .snlen = sizeof("\ro=") - 1,
147 .ln_str = "IN IP4 ",
148 .ln_strlen = sizeof("IN IP4 ") - 1,
149 .match_len = epaddr_len
150 },
151 [POS_CONNECTION] = { /* SDP connection info */
152 .case_sensitive = 1,
153 .lname = "\nc=",
154 .lnlen = sizeof("\nc=") - 1,
155 .sname = "\rc=",
156 .snlen = sizeof("\rc=") - 1,
157 .ln_str = "IN IP4 ",
158 .ln_strlen = sizeof("IN IP4 ") - 1,
159 .match_len = epaddr_len
160 },
161 [POS_SDP_HEADER] = { /* SDP version header */
162 .case_sensitive = 1,
163 .lname = "\nv=",
164 .lnlen = sizeof("\nv=") - 1,
165 .sname = "\rv=",
166 .snlen = sizeof("\rv=") - 1,
167 .ln_str = "=",
168 .ln_strlen = sizeof("=") - 1,
169 .match_len = digits_len
170 }
171 };
172
173 /* get line lenght until first CR or LF seen. */
174 int ct_sip_lnlen(const char *line, const char *limit)
175 {
176 const char *k = line;
177
178 while ((line <= limit) && (*line == '\r' || *line == '\n'))
179 line++;
180
181 while (line <= limit) {
182 if (*line == '\r' || *line == '\n')
183 break;
184 line++;
185 }
186 return line - k;
187 }
188 EXPORT_SYMBOL_GPL(ct_sip_lnlen);
189
190 /* Linear string search, case sensitive. */
191 const char *ct_sip_search(const char *needle, const char *haystack,
192 size_t needle_len, size_t haystack_len,
193 int case_sensitive)
194 {
195 const char *limit = haystack + (haystack_len - needle_len);
196
197 while (haystack <= limit) {
198 if (case_sensitive) {
199 if (strncmp(haystack, needle, needle_len) == 0)
200 return haystack;
201 } else {
202 if (strnicmp(haystack, needle, needle_len) == 0)
203 return haystack;
204 }
205 haystack++;
206 }
207 return NULL;
208 }
209 EXPORT_SYMBOL_GPL(ct_sip_search);
210
211 static int digits_len(const char *dptr, const char *limit, int *shift)
212 {
213 int len = 0;
214 while (dptr <= limit && isdigit(*dptr)) {
215 dptr++;
216 len++;
217 }
218 return len;
219 }
220
221 /* get digits lenght, skiping blank spaces. */
222 static int skp_digits_len(const char *dptr, const char *limit, int *shift)
223 {
224 for (; dptr <= limit && *dptr == ' '; dptr++)
225 (*shift)++;
226
227 return digits_len(dptr, limit, shift);
228 }
229
230 /* Simple ipaddr parser.. */
231 static int parse_ipaddr(const char *cp, const char **endp,
232 __be32 *ipaddr, const char *limit)
233 {
234 unsigned long int val;
235 int i, digit = 0;
236
237 for (i = 0, *ipaddr = 0; cp <= limit && i < 4; i++) {
238 digit = 0;
239 if (!isdigit(*cp))
240 break;
241
242 val = simple_strtoul(cp, (char **)&cp, 10);
243 if (val > 0xFF)
244 return -1;
245
246 ((u_int8_t *)ipaddr)[i] = val;
247 digit = 1;
248
249 if (*cp != '.')
250 break;
251 cp++;
252 }
253 if (!digit)
254 return -1;
255
256 if (endp)
257 *endp = cp;
258
259 return 0;
260 }
261
262 /* skip ip address. returns it lenght. */
263 static int epaddr_len(const char *dptr, const char *limit, int *shift)
264 {
265 const char *aux = dptr;
266 __be32 ip;
267
268 if (parse_ipaddr(dptr, &dptr, &ip, limit) < 0) {
269 DEBUGP("ip: %s parse failed.!\n", dptr);
270 return 0;
271 }
272
273 /* Port number */
274 if (*dptr == ':') {
275 dptr++;
276 dptr += digits_len(dptr, limit, shift);
277 }
278 return dptr - aux;
279 }
280
281 /* get address length, skiping user info. */
282 static int skp_epaddr_len(const char *dptr, const char *limit, int *shift)
283 {
284 int s = *shift;
285
286 for (; dptr <= limit && *dptr != '@'; dptr++)
287 (*shift)++;
288
289 if (*dptr == '@') {
290 dptr++;
291 (*shift)++;
292 } else
293 *shift = s;
294
295 return epaddr_len(dptr, limit, shift);
296 }
297
298 /* Returns 0 if not found, -1 error parsing. */
299 int ct_sip_get_info(const char *dptr, size_t dlen,
300 unsigned int *matchoff,
301 unsigned int *matchlen,
302 enum sip_header_pos pos)
303 {
304 struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
305 const char *limit, *aux, *k = dptr;
306 int shift = 0;
307
308 limit = dptr + (dlen - hnfo->lnlen);
309
310 while (dptr <= limit) {
311 if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
312 (hnfo->sname == NULL ||
313 strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
314 dptr++;
315 continue;
316 }
317 aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
318 ct_sip_lnlen(dptr, limit),
319 hnfo->case_sensitive);
320 if (!aux) {
321 DEBUGP("'%s' not found in '%s'.\n", hnfo->ln_str,
322 hnfo->lname);
323 return -1;
324 }
325 aux += hnfo->ln_strlen;
326
327 *matchlen = hnfo->match_len(aux, limit, &shift);
328 if (!*matchlen)
329 return -1;
330
331 *matchoff = (aux - k) + shift;
332
333 DEBUGP("%s match succeeded! - len: %u\n", hnfo->lname,
334 *matchlen);
335 return 1;
336 }
337 DEBUGP("%s header not found.\n", hnfo->lname);
338 return 0;
339 }
340 EXPORT_SYMBOL_GPL(ct_sip_get_info);
341
342 static int set_expected_rtp(struct sk_buff **pskb,
343 struct ip_conntrack *ct,
344 enum ip_conntrack_info ctinfo,
345 __be32 ipaddr, u_int16_t port,
346 const char *dptr)
347 {
348 struct ip_conntrack_expect *exp;
349 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
350 int ret;
351 typeof(ip_nat_sdp_hook) ip_nat_sdp;
352
353 exp = ip_conntrack_expect_alloc(ct);
354 if (exp == NULL)
355 return NF_DROP;
356
357 exp->tuple.src.ip = ct->tuplehash[!dir].tuple.src.ip;
358 exp->tuple.src.u.udp.port = 0;
359 exp->tuple.dst.ip = ipaddr;
360 exp->tuple.dst.u.udp.port = htons(port);
361 exp->tuple.dst.protonum = IPPROTO_UDP;
362
363 exp->mask.src.ip = htonl(0xFFFFFFFF);
364 exp->mask.src.u.udp.port = 0;
365 exp->mask.dst.ip = htonl(0xFFFFFFFF);
366 exp->mask.dst.u.udp.port = htons(0xFFFF);
367 exp->mask.dst.protonum = 0xFF;
368
369 exp->expectfn = NULL;
370 exp->flags = 0;
371
372 ip_nat_sdp = rcu_dereference(ip_nat_sdp_hook);
373 if (ip_nat_sdp)
374 ret = ip_nat_sdp(pskb, ctinfo, exp, dptr);
375 else {
376 if (ip_conntrack_expect_related(exp) != 0)
377 ret = NF_DROP;
378 else
379 ret = NF_ACCEPT;
380 }
381 ip_conntrack_expect_put(exp);
382
383 return ret;
384 }
385
386 static int sip_help(struct sk_buff **pskb,
387 struct ip_conntrack *ct,
388 enum ip_conntrack_info ctinfo)
389 {
390 unsigned int dataoff, datalen;
391 const char *dptr;
392 int ret = NF_ACCEPT;
393 int matchoff, matchlen;
394 __be32 ipaddr;
395 u_int16_t port;
396 typeof(ip_nat_sip_hook) ip_nat_sip;
397
398 /* No Data ? */
399 dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
400 if (dataoff >= (*pskb)->len) {
401 DEBUGP("skb->len = %u\n", (*pskb)->len);
402 return NF_ACCEPT;
403 }
404
405 ip_ct_refresh(ct, *pskb, sip_timeout * HZ);
406
407 if (!skb_is_nonlinear(*pskb))
408 dptr = (*pskb)->data + dataoff;
409 else {
410 DEBUGP("Copy of skbuff not supported yet.\n");
411 goto out;
412 }
413
414 ip_nat_sip = rcu_dereference(ip_nat_sip_hook);
415 if (ip_nat_sip) {
416 if (!ip_nat_sip(pskb, ctinfo, ct, &dptr)) {
417 ret = NF_DROP;
418 goto out;
419 }
420 }
421
422 /* After this point NAT, could have mangled skb, so
423 we need to recalculate payload lenght. */
424 datalen = (*pskb)->len - dataoff;
425
426 if (datalen < (sizeof("SIP/2.0 200") - 1))
427 goto out;
428
429 /* RTP info only in some SDP pkts */
430 if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
431 memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
432 goto out;
433 }
434 /* Get ip and port address from SDP packet. */
435 if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
436 POS_CONNECTION) > 0) {
437
438 /* We'll drop only if there are parse problems. */
439 if (parse_ipaddr(dptr + matchoff, NULL, &ipaddr,
440 dptr + datalen) < 0) {
441 ret = NF_DROP;
442 goto out;
443 }
444 if (ct_sip_get_info(dptr, datalen, &matchoff, &matchlen,
445 POS_MEDIA) > 0) {
446
447 port = simple_strtoul(dptr + matchoff, NULL, 10);
448 if (port < 1024) {
449 ret = NF_DROP;
450 goto out;
451 }
452 ret = set_expected_rtp(pskb, ct, ctinfo,
453 ipaddr, port, dptr);
454 }
455 }
456 out:
457 return ret;
458 }
459
460 static struct ip_conntrack_helper sip[MAX_PORTS];
461 static char sip_names[MAX_PORTS][10];
462
463 static void fini(void)
464 {
465 int i;
466 for (i = 0; i < ports_c; i++) {
467 DEBUGP("unregistering helper for port %d\n", ports[i]);
468 ip_conntrack_helper_unregister(&sip[i]);
469 }
470 }
471
472 static int __init init(void)
473 {
474 int i, ret;
475 char *tmpname;
476
477 if (ports_c == 0)
478 ports[ports_c++] = SIP_PORT;
479
480 for (i = 0; i < ports_c; i++) {
481 /* Create helper structure */
482 memset(&sip[i], 0, sizeof(struct ip_conntrack_helper));
483
484 sip[i].tuple.dst.protonum = IPPROTO_UDP;
485 sip[i].tuple.src.u.udp.port = htons(ports[i]);
486 sip[i].mask.src.u.udp.port = htons(0xFFFF);
487 sip[i].mask.dst.protonum = 0xFF;
488 sip[i].max_expected = 2;
489 sip[i].timeout = 3 * 60; /* 3 minutes */
490 sip[i].me = THIS_MODULE;
491 sip[i].help = sip_help;
492
493 tmpname = &sip_names[i][0];
494 if (ports[i] == SIP_PORT)
495 sprintf(tmpname, "sip");
496 else
497 sprintf(tmpname, "sip-%d", i);
498 sip[i].name = tmpname;
499
500 DEBUGP("port #%d: %d\n", i, ports[i]);
501
502 ret = ip_conntrack_helper_register(&sip[i]);
503 if (ret) {
504 printk("ERROR registering helper for port %d\n",
505 ports[i]);
506 fini();
507 return ret;
508 }
509 }
510 return 0;
511 }
512
513 module_init(init);
514 module_exit(fini);
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