Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 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/inet.h> |
| 15 | #include <linux/in.h> |
| 16 | #include <linux/udp.h> |
Yasuyuki Kozakai | 1863f09 | 2006-12-02 22:12:54 -0800 | [diff] [blame] | 17 | #include <linux/netfilter.h> |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 18 | |
| 19 | #include <net/netfilter/nf_conntrack.h> |
| 20 | #include <net/netfilter/nf_conntrack_expect.h> |
| 21 | #include <net/netfilter/nf_conntrack_helper.h> |
| 22 | #include <linux/netfilter/nf_conntrack_sip.h> |
| 23 | |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 24 | MODULE_LICENSE("GPL"); |
| 25 | MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>"); |
| 26 | MODULE_DESCRIPTION("SIP connection tracking helper"); |
| 27 | MODULE_ALIAS("ip_conntrack_sip"); |
| 28 | |
| 29 | #define MAX_PORTS 8 |
| 30 | static unsigned short ports[MAX_PORTS]; |
Stephen Hemminger | 2f0d2f1 | 2008-01-31 04:08:10 -0800 | [diff] [blame] | 31 | static unsigned int ports_c; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 32 | module_param_array(ports, ushort, &ports_c, 0400); |
| 33 | MODULE_PARM_DESC(ports, "port numbers of SIP servers"); |
| 34 | |
| 35 | static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT; |
| 36 | module_param(sip_timeout, uint, 0600); |
| 37 | MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session"); |
| 38 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 39 | unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, |
Patrick McHardy | 2a6cfb2 | 2008-03-25 20:16:54 -0700 | [diff] [blame] | 40 | const char **dptr, |
| 41 | unsigned int *datalen) __read_mostly; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 42 | EXPORT_SYMBOL_GPL(nf_nat_sip_hook); |
| 43 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 44 | unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb, |
Patrick McHardy | 2a6cfb2 | 2008-03-25 20:16:54 -0700 | [diff] [blame] | 45 | const char **dptr, |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 46 | unsigned int *datalen, |
| 47 | struct nf_conntrack_expect *exp) __read_mostly; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 48 | EXPORT_SYMBOL_GPL(nf_nat_sdp_hook); |
| 49 | |
Patrick McHardy | ac36774 | 2008-03-25 20:18:40 -0700 | [diff] [blame] | 50 | static int string_len(const struct nf_conn *ct, const char *dptr, |
| 51 | const char *limit, int *shift) |
| 52 | { |
| 53 | int len = 0; |
| 54 | |
| 55 | while (dptr < limit && isalpha(*dptr)) { |
| 56 | dptr++; |
| 57 | len++; |
| 58 | } |
| 59 | return len; |
| 60 | } |
| 61 | |
Jan Engelhardt | 13f7d63 | 2008-01-31 04:50:25 -0800 | [diff] [blame] | 62 | static int digits_len(const struct nf_conn *ct, const char *dptr, |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 63 | const char *limit, int *shift) |
| 64 | { |
| 65 | int len = 0; |
Patrick McHardy | b1ec488 | 2008-03-25 20:10:11 -0700 | [diff] [blame] | 66 | while (dptr < limit && isdigit(*dptr)) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 67 | dptr++; |
| 68 | len++; |
| 69 | } |
| 70 | return len; |
| 71 | } |
| 72 | |
Jan Engelhardt | 13f7d63 | 2008-01-31 04:50:25 -0800 | [diff] [blame] | 73 | static int parse_addr(const struct nf_conn *ct, const char *cp, |
| 74 | const char **endp, union nf_inet_addr *addr, |
| 75 | const char *limit) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 76 | { |
| 77 | const char *end; |
| 78 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; |
| 79 | int ret = 0; |
| 80 | |
| 81 | switch (family) { |
| 82 | case AF_INET: |
| 83 | ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end); |
| 84 | break; |
| 85 | case AF_INET6: |
| 86 | ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end); |
| 87 | break; |
| 88 | default: |
| 89 | BUG(); |
| 90 | } |
| 91 | |
| 92 | if (ret == 0 || end == cp) |
| 93 | return 0; |
| 94 | if (endp) |
| 95 | *endp = end; |
| 96 | return 1; |
| 97 | } |
| 98 | |
| 99 | /* skip ip address. returns its length. */ |
Jan Engelhardt | 13f7d63 | 2008-01-31 04:50:25 -0800 | [diff] [blame] | 100 | static int epaddr_len(const struct nf_conn *ct, const char *dptr, |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 101 | const char *limit, int *shift) |
| 102 | { |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 103 | union nf_inet_addr addr; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 104 | const char *aux = dptr; |
| 105 | |
| 106 | if (!parse_addr(ct, dptr, &dptr, &addr, limit)) { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 107 | pr_debug("ip: %s parse failed.!\n", dptr); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | /* Port number */ |
| 112 | if (*dptr == ':') { |
| 113 | dptr++; |
| 114 | dptr += digits_len(ct, dptr, limit, shift); |
| 115 | } |
| 116 | return dptr - aux; |
| 117 | } |
| 118 | |
| 119 | /* get address length, skiping user info. */ |
Jan Engelhardt | 13f7d63 | 2008-01-31 04:50:25 -0800 | [diff] [blame] | 120 | static int skp_epaddr_len(const struct nf_conn *ct, const char *dptr, |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 121 | const char *limit, int *shift) |
| 122 | { |
Patrick McHardy | aa584ed | 2007-08-14 13:14:35 -0700 | [diff] [blame] | 123 | const char *start = dptr; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 124 | int s = *shift; |
| 125 | |
Lars Immisch | 7da5bfb | 2007-01-30 14:24:57 -0800 | [diff] [blame] | 126 | /* Search for @, but stop at the end of the line. |
| 127 | * We are inside a sip: URI, so we don't need to worry about |
| 128 | * continuation lines. */ |
Patrick McHardy | b1ec488 | 2008-03-25 20:10:11 -0700 | [diff] [blame] | 129 | while (dptr < limit && |
Lars Immisch | 7da5bfb | 2007-01-30 14:24:57 -0800 | [diff] [blame] | 130 | *dptr != '@' && *dptr != '\r' && *dptr != '\n') { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 131 | (*shift)++; |
Lars Immisch | 7da5bfb | 2007-01-30 14:24:57 -0800 | [diff] [blame] | 132 | dptr++; |
| 133 | } |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 134 | |
Patrick McHardy | b1ec488 | 2008-03-25 20:10:11 -0700 | [diff] [blame] | 135 | if (dptr < limit && *dptr == '@') { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 136 | dptr++; |
| 137 | (*shift)++; |
Patrick McHardy | aa584ed | 2007-08-14 13:14:35 -0700 | [diff] [blame] | 138 | } else { |
| 139 | dptr = start; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 140 | *shift = s; |
Patrick McHardy | aa584ed | 2007-08-14 13:14:35 -0700 | [diff] [blame] | 141 | } |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 142 | |
| 143 | return epaddr_len(ct, dptr, limit, shift); |
| 144 | } |
| 145 | |
Patrick McHardy | ac36774 | 2008-03-25 20:18:40 -0700 | [diff] [blame] | 146 | /* Parse a SIP request line of the form: |
| 147 | * |
| 148 | * Request-Line = Method SP Request-URI SP SIP-Version CRLF |
| 149 | * |
| 150 | * and return the offset and length of the address contained in the Request-URI. |
| 151 | */ |
| 152 | int ct_sip_parse_request(const struct nf_conn *ct, |
| 153 | const char *dptr, unsigned int datalen, |
| 154 | unsigned int *matchoff, unsigned int *matchlen) |
| 155 | { |
| 156 | const char *start = dptr, *limit = dptr + datalen; |
| 157 | unsigned int mlen; |
| 158 | int shift = 0; |
| 159 | |
| 160 | /* Skip method and following whitespace */ |
| 161 | mlen = string_len(ct, dptr, limit, NULL); |
| 162 | if (!mlen) |
| 163 | return 0; |
| 164 | dptr += mlen; |
| 165 | if (++dptr >= limit) |
| 166 | return 0; |
| 167 | |
| 168 | /* Find SIP URI */ |
| 169 | limit -= strlen("sip:"); |
| 170 | for (; dptr < limit; dptr++) { |
| 171 | if (*dptr == '\r' || *dptr == '\n') |
| 172 | return -1; |
| 173 | if (strnicmp(dptr, "sip:", strlen("sip:")) == 0) |
| 174 | break; |
| 175 | } |
| 176 | *matchlen = skp_epaddr_len(ct, dptr, limit, &shift); |
| 177 | if (!*matchlen) |
| 178 | return 0; |
| 179 | *matchoff = dptr - start + shift; |
| 180 | return 1; |
| 181 | } |
| 182 | EXPORT_SYMBOL_GPL(ct_sip_parse_request); |
| 183 | |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 184 | /* SIP header parsing: SIP headers are located at the beginning of a line, but |
| 185 | * may span several lines, in which case the continuation lines begin with a |
| 186 | * whitespace character. RFC 2543 allows lines to be terminated with CR, LF or |
| 187 | * CRLF, RFC 3261 allows only CRLF, we support both. |
| 188 | * |
| 189 | * Headers are followed by (optionally) whitespace, a colon, again (optionally) |
| 190 | * whitespace and the values. Whitespace in this context means any amount of |
| 191 | * tabs, spaces and continuation lines, which are treated as a single whitespace |
| 192 | * character. |
Patrick McHardy | 05e3ced | 2008-03-25 20:19:13 -0700 | [diff] [blame^] | 193 | * |
| 194 | * Some headers may appear multiple times. A comma seperated list of values is |
| 195 | * equivalent to multiple headers. |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 196 | */ |
| 197 | static const struct sip_header ct_sip_hdrs[] = { |
| 198 | [SIP_HDR_FROM] = SIP_HDR("From", "f", "sip:", skp_epaddr_len), |
| 199 | [SIP_HDR_TO] = SIP_HDR("To", "t", "sip:", skp_epaddr_len), |
| 200 | [SIP_HDR_CONTACT] = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len), |
| 201 | [SIP_HDR_VIA] = SIP_HDR("Via", "v", "UDP ", epaddr_len), |
| 202 | [SIP_HDR_CONTENT_LENGTH] = SIP_HDR("Content-Length", "l", NULL, digits_len), |
| 203 | }; |
| 204 | |
| 205 | static const char *sip_follow_continuation(const char *dptr, const char *limit) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 206 | { |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 207 | /* Walk past newline */ |
| 208 | if (++dptr >= limit) |
| 209 | return NULL; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 210 | |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 211 | /* Skip '\n' in CR LF */ |
| 212 | if (*(dptr - 1) == '\r' && *dptr == '\n') { |
| 213 | if (++dptr >= limit) |
| 214 | return NULL; |
| 215 | } |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 216 | |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 217 | /* Continuation line? */ |
| 218 | if (*dptr != ' ' && *dptr != '\t') |
| 219 | return NULL; |
| 220 | |
| 221 | /* skip leading whitespace */ |
| 222 | for (; dptr < limit; dptr++) { |
| 223 | if (*dptr != ' ' && *dptr != '\t') |
| 224 | break; |
| 225 | } |
| 226 | return dptr; |
| 227 | } |
| 228 | |
| 229 | static const char *sip_skip_whitespace(const char *dptr, const char *limit) |
| 230 | { |
| 231 | for (; dptr < limit; dptr++) { |
| 232 | if (*dptr == ' ') |
| 233 | continue; |
| 234 | if (*dptr != '\r' && *dptr != '\n') |
| 235 | break; |
| 236 | dptr = sip_follow_continuation(dptr, limit); |
| 237 | if (dptr == NULL) |
| 238 | return NULL; |
| 239 | } |
| 240 | return dptr; |
| 241 | } |
| 242 | |
| 243 | /* Search within a SIP header value, dealing with continuation lines */ |
| 244 | static const char *ct_sip_header_search(const char *dptr, const char *limit, |
| 245 | const char *needle, unsigned int len) |
| 246 | { |
| 247 | for (limit -= len; dptr < limit; dptr++) { |
| 248 | if (*dptr == '\r' || *dptr == '\n') { |
| 249 | dptr = sip_follow_continuation(dptr, limit); |
| 250 | if (dptr == NULL) |
| 251 | break; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 252 | continue; |
| 253 | } |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 254 | |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 255 | if (strnicmp(dptr, needle, len) == 0) |
| 256 | return dptr; |
| 257 | } |
| 258 | return NULL; |
| 259 | } |
| 260 | |
| 261 | int ct_sip_get_header(const struct nf_conn *ct, const char *dptr, |
| 262 | unsigned int dataoff, unsigned int datalen, |
| 263 | enum sip_header_types type, |
| 264 | unsigned int *matchoff, unsigned int *matchlen) |
| 265 | { |
| 266 | const struct sip_header *hdr = &ct_sip_hdrs[type]; |
| 267 | const char *start = dptr, *limit = dptr + datalen; |
| 268 | int shift = 0; |
| 269 | |
| 270 | for (dptr += dataoff; dptr < limit; dptr++) { |
| 271 | /* Find beginning of line */ |
| 272 | if (*dptr != '\r' && *dptr != '\n') |
| 273 | continue; |
| 274 | if (++dptr >= limit) |
| 275 | break; |
| 276 | if (*(dptr - 1) == '\r' && *dptr == '\n') { |
| 277 | if (++dptr >= limit) |
| 278 | break; |
| 279 | } |
| 280 | |
| 281 | /* Skip continuation lines */ |
| 282 | if (*dptr == ' ' || *dptr == '\t') |
| 283 | continue; |
| 284 | |
| 285 | /* Find header. Compact headers must be followed by a |
| 286 | * non-alphabetic character to avoid mismatches. */ |
| 287 | if (limit - dptr >= hdr->len && |
| 288 | strnicmp(dptr, hdr->name, hdr->len) == 0) |
| 289 | dptr += hdr->len; |
| 290 | else if (hdr->cname && limit - dptr >= hdr->clen + 1 && |
| 291 | strnicmp(dptr, hdr->cname, hdr->clen) == 0 && |
| 292 | !isalpha(*(dptr + hdr->clen + 1))) |
| 293 | dptr += hdr->clen; |
| 294 | else |
| 295 | continue; |
| 296 | |
| 297 | /* Find and skip colon */ |
| 298 | dptr = sip_skip_whitespace(dptr, limit); |
| 299 | if (dptr == NULL) |
| 300 | break; |
| 301 | if (*dptr != ':' || ++dptr >= limit) |
| 302 | break; |
| 303 | |
| 304 | /* Skip whitespace after colon */ |
| 305 | dptr = sip_skip_whitespace(dptr, limit); |
| 306 | if (dptr == NULL) |
| 307 | break; |
| 308 | |
| 309 | *matchoff = dptr - start; |
| 310 | if (hdr->search) { |
| 311 | dptr = ct_sip_header_search(dptr, limit, hdr->search, |
| 312 | hdr->slen); |
| 313 | if (!dptr) |
| 314 | return -1; |
| 315 | dptr += hdr->slen; |
| 316 | } |
| 317 | |
| 318 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 319 | if (!*matchlen) |
| 320 | return -1; |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 321 | *matchoff = dptr - start + shift; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 322 | return 1; |
| 323 | } |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 324 | return 0; |
| 325 | } |
Patrick McHardy | ea45f12 | 2008-03-25 20:18:57 -0700 | [diff] [blame] | 326 | EXPORT_SYMBOL_GPL(ct_sip_get_header); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 327 | |
Patrick McHardy | 05e3ced | 2008-03-25 20:19:13 -0700 | [diff] [blame^] | 328 | /* Get next header field in a list of comma seperated values */ |
| 329 | static int ct_sip_next_header(const struct nf_conn *ct, const char *dptr, |
| 330 | unsigned int dataoff, unsigned int datalen, |
| 331 | enum sip_header_types type, |
| 332 | unsigned int *matchoff, unsigned int *matchlen) |
| 333 | { |
| 334 | const struct sip_header *hdr = &ct_sip_hdrs[type]; |
| 335 | const char *start = dptr, *limit = dptr + datalen; |
| 336 | int shift = 0; |
| 337 | |
| 338 | dptr += dataoff; |
| 339 | |
| 340 | dptr = ct_sip_header_search(dptr, limit, ",", strlen(",")); |
| 341 | if (!dptr) |
| 342 | return 0; |
| 343 | |
| 344 | dptr = ct_sip_header_search(dptr, limit, hdr->search, hdr->slen); |
| 345 | if (!dptr) |
| 346 | return 0; |
| 347 | dptr += hdr->slen; |
| 348 | |
| 349 | *matchoff = dptr - start; |
| 350 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); |
| 351 | if (!*matchlen) |
| 352 | return -1; |
| 353 | *matchoff += shift; |
| 354 | return 1; |
| 355 | } |
| 356 | |
| 357 | /* Walk through headers until a parsable one is found or no header of the |
| 358 | * given type is left. */ |
| 359 | static int ct_sip_walk_headers(const struct nf_conn *ct, const char *dptr, |
| 360 | unsigned int dataoff, unsigned int datalen, |
| 361 | enum sip_header_types type, int *in_header, |
| 362 | unsigned int *matchoff, unsigned int *matchlen) |
| 363 | { |
| 364 | int ret; |
| 365 | |
| 366 | if (in_header && *in_header) { |
| 367 | while (1) { |
| 368 | ret = ct_sip_next_header(ct, dptr, dataoff, datalen, |
| 369 | type, matchoff, matchlen); |
| 370 | if (ret > 0) |
| 371 | return ret; |
| 372 | if (ret == 0) |
| 373 | break; |
| 374 | dataoff += *matchoff; |
| 375 | } |
| 376 | *in_header = 0; |
| 377 | } |
| 378 | |
| 379 | while (1) { |
| 380 | ret = ct_sip_get_header(ct, dptr, dataoff, datalen, |
| 381 | type, matchoff, matchlen); |
| 382 | if (ret > 0) |
| 383 | break; |
| 384 | if (ret == 0) |
| 385 | return ret; |
| 386 | dataoff += *matchoff; |
| 387 | } |
| 388 | |
| 389 | if (in_header) |
| 390 | *in_header = 1; |
| 391 | return 1; |
| 392 | } |
| 393 | |
| 394 | /* Locate a SIP header, parse the URI and return the offset and length of |
| 395 | * the address as well as the address and port themselves. A stream of |
| 396 | * headers can be parsed by handing in a non-NULL datalen and in_header |
| 397 | * pointer. |
| 398 | */ |
| 399 | int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr, |
| 400 | unsigned int *dataoff, unsigned int datalen, |
| 401 | enum sip_header_types type, int *in_header, |
| 402 | unsigned int *matchoff, unsigned int *matchlen, |
| 403 | union nf_inet_addr *addr, __be16 *port) |
| 404 | { |
| 405 | const char *c, *limit = dptr + datalen; |
| 406 | unsigned int p; |
| 407 | int ret; |
| 408 | |
| 409 | ret = ct_sip_walk_headers(ct, dptr, dataoff ? *dataoff : 0, datalen, |
| 410 | type, in_header, matchoff, matchlen); |
| 411 | WARN_ON(ret < 0); |
| 412 | if (ret == 0) |
| 413 | return ret; |
| 414 | |
| 415 | if (!parse_addr(ct, dptr + *matchoff, &c, addr, limit)) |
| 416 | return -1; |
| 417 | if (*c == ':') { |
| 418 | c++; |
| 419 | p = simple_strtoul(c, (char **)&c, 10); |
| 420 | if (p < 1024 || p > 65535) |
| 421 | return -1; |
| 422 | *port = htons(p); |
| 423 | } else |
| 424 | *port = htons(SIP_PORT); |
| 425 | |
| 426 | if (dataoff) |
| 427 | *dataoff = c - dptr; |
| 428 | return 1; |
| 429 | } |
| 430 | EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri); |
| 431 | |
Patrick McHardy | 3e9b4600b | 2008-03-25 20:17:55 -0700 | [diff] [blame] | 432 | /* SDP header parsing: a SDP session description contains an ordered set of |
| 433 | * headers, starting with a section containing general session parameters, |
| 434 | * optionally followed by multiple media descriptions. |
| 435 | * |
| 436 | * SDP headers always start at the beginning of a line. According to RFC 2327: |
| 437 | * "The sequence CRLF (0x0d0a) is used to end a record, although parsers should |
| 438 | * be tolerant and also accept records terminated with a single newline |
| 439 | * character". We handle both cases. |
| 440 | */ |
| 441 | static const struct sip_header ct_sdp_hdrs[] = { |
| 442 | [SDP_HDR_VERSION] = SDP_HDR("v=", NULL, digits_len), |
| 443 | [SDP_HDR_OWNER_IP4] = SDP_HDR("o=", "IN IP4 ", epaddr_len), |
| 444 | [SDP_HDR_CONNECTION_IP4] = SDP_HDR("c=", "IN IP4 ", epaddr_len), |
| 445 | [SDP_HDR_OWNER_IP6] = SDP_HDR("o=", "IN IP6 ", epaddr_len), |
| 446 | [SDP_HDR_CONNECTION_IP6] = SDP_HDR("c=", "IN IP6 ", epaddr_len), |
| 447 | [SDP_HDR_MEDIA] = SDP_HDR("m=", "audio ", digits_len), |
| 448 | }; |
| 449 | |
| 450 | /* Linear string search within SDP header values */ |
| 451 | static const char *ct_sdp_header_search(const char *dptr, const char *limit, |
| 452 | const char *needle, unsigned int len) |
| 453 | { |
| 454 | for (limit -= len; dptr < limit; dptr++) { |
| 455 | if (*dptr == '\r' || *dptr == '\n') |
| 456 | break; |
| 457 | if (strncmp(dptr, needle, len) == 0) |
| 458 | return dptr; |
| 459 | } |
| 460 | return NULL; |
| 461 | } |
| 462 | |
| 463 | /* Locate a SDP header (optionally a substring within the header value), |
| 464 | * optionally stopping at the first occurence of the term header, parse |
| 465 | * it and return the offset and length of the data we're interested in. |
| 466 | */ |
| 467 | int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr, |
| 468 | unsigned int dataoff, unsigned int datalen, |
| 469 | enum sdp_header_types type, |
| 470 | enum sdp_header_types term, |
| 471 | unsigned int *matchoff, unsigned int *matchlen) |
| 472 | { |
| 473 | const struct sip_header *hdr = &ct_sdp_hdrs[type]; |
| 474 | const struct sip_header *thdr = &ct_sdp_hdrs[term]; |
| 475 | const char *start = dptr, *limit = dptr + datalen; |
| 476 | int shift = 0; |
| 477 | |
| 478 | for (dptr += dataoff; dptr < limit; dptr++) { |
| 479 | /* Find beginning of line */ |
| 480 | if (*dptr != '\r' && *dptr != '\n') |
| 481 | continue; |
| 482 | if (++dptr >= limit) |
| 483 | break; |
| 484 | if (*(dptr - 1) == '\r' && *dptr == '\n') { |
| 485 | if (++dptr >= limit) |
| 486 | break; |
| 487 | } |
| 488 | |
| 489 | if (term != SDP_HDR_UNSPEC && |
| 490 | limit - dptr >= thdr->len && |
| 491 | strnicmp(dptr, thdr->name, thdr->len) == 0) |
| 492 | break; |
| 493 | else if (limit - dptr >= hdr->len && |
| 494 | strnicmp(dptr, hdr->name, hdr->len) == 0) |
| 495 | dptr += hdr->len; |
| 496 | else |
| 497 | continue; |
| 498 | |
| 499 | *matchoff = dptr - start; |
| 500 | if (hdr->search) { |
| 501 | dptr = ct_sdp_header_search(dptr, limit, hdr->search, |
| 502 | hdr->slen); |
| 503 | if (!dptr) |
| 504 | return -1; |
| 505 | dptr += hdr->slen; |
| 506 | } |
| 507 | |
| 508 | *matchlen = hdr->match_len(ct, dptr, limit, &shift); |
| 509 | if (!*matchlen) |
| 510 | return -1; |
| 511 | *matchoff = dptr - start + shift; |
| 512 | return 1; |
| 513 | } |
| 514 | return 0; |
| 515 | } |
| 516 | EXPORT_SYMBOL_GPL(ct_sip_get_sdp_header); |
| 517 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 518 | static int set_expected_rtp(struct sk_buff *skb, |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 519 | const char **dptr, unsigned int *datalen, |
| 520 | union nf_inet_addr *addr, __be16 port) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 521 | { |
| 522 | struct nf_conntrack_expect *exp; |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 523 | enum ip_conntrack_info ctinfo; |
| 524 | struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 525 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| 526 | int family = ct->tuplehash[!dir].tuple.src.l3num; |
| 527 | int ret; |
| 528 | typeof(nf_nat_sdp_hook) nf_nat_sdp; |
| 529 | |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 530 | exp = nf_ct_expect_alloc(ct); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 531 | if (exp == NULL) |
| 532 | return NF_DROP; |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 533 | nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, family, |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 534 | &ct->tuplehash[!dir].tuple.src.u3, addr, |
| 535 | IPPROTO_UDP, NULL, &port); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 536 | |
| 537 | nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook); |
| 538 | if (nf_nat_sdp && ct->status & IPS_NAT_MASK) |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 539 | ret = nf_nat_sdp(skb, dptr, datalen, exp); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 540 | else { |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 541 | if (nf_ct_expect_related(exp) != 0) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 542 | ret = NF_DROP; |
| 543 | else |
| 544 | ret = NF_ACCEPT; |
| 545 | } |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 546 | nf_ct_expect_put(exp); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 547 | |
| 548 | return ret; |
| 549 | } |
| 550 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 551 | static int sip_help(struct sk_buff *skb, |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 552 | unsigned int protoff, |
| 553 | struct nf_conn *ct, |
| 554 | enum ip_conntrack_info ctinfo) |
| 555 | { |
| 556 | int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num; |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 557 | union nf_inet_addr addr; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 558 | unsigned int dataoff, datalen; |
| 559 | const char *dptr; |
| 560 | int ret = NF_ACCEPT; |
Stephen Hemminger | 2f0d2f1 | 2008-01-31 04:08:10 -0800 | [diff] [blame] | 561 | unsigned int matchoff, matchlen; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 562 | u_int16_t port; |
Patrick McHardy | 3e9b4600b | 2008-03-25 20:17:55 -0700 | [diff] [blame] | 563 | enum sdp_header_types type; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 564 | typeof(nf_nat_sip_hook) nf_nat_sip; |
| 565 | |
| 566 | /* No Data ? */ |
| 567 | dataoff = protoff + sizeof(struct udphdr); |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 568 | if (dataoff >= skb->len) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 569 | return NF_ACCEPT; |
| 570 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 571 | nf_ct_refresh(ct, skb, sip_timeout * HZ); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 572 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 573 | if (!skb_is_nonlinear(skb)) |
| 574 | dptr = skb->data + dataoff; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 575 | else { |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 576 | pr_debug("Copy of skbuff not supported yet.\n"); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 577 | goto out; |
| 578 | } |
| 579 | |
| 580 | nf_nat_sip = rcu_dereference(nf_nat_sip_hook); |
| 581 | if (nf_nat_sip && ct->status & IPS_NAT_MASK) { |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 582 | if (!nf_nat_sip(skb, &dptr, &datalen)) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 583 | ret = NF_DROP; |
| 584 | goto out; |
| 585 | } |
| 586 | } |
| 587 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 588 | datalen = skb->len - dataoff; |
Patrick McHardy | 779382e | 2008-03-25 20:17:36 -0700 | [diff] [blame] | 589 | if (datalen < strlen("SIP/2.0 200")) |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 590 | goto out; |
| 591 | |
| 592 | /* RTP info only in some SDP pkts */ |
Patrick McHardy | 779382e | 2008-03-25 20:17:36 -0700 | [diff] [blame] | 593 | if (strnicmp(dptr, "INVITE", strlen("INVITE")) != 0 && |
| 594 | strnicmp(dptr, "UPDATE", strlen("UPDATE")) != 0 && |
| 595 | strnicmp(dptr, "SIP/2.0 180", strlen("SIP/2.0 180")) != 0 && |
| 596 | strnicmp(dptr, "SIP/2.0 183", strlen("SIP/2.0 183")) != 0 && |
| 597 | strnicmp(dptr, "SIP/2.0 200", strlen("SIP/2.0 200")) != 0) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 598 | goto out; |
| 599 | } |
| 600 | /* Get address and port from SDP packet. */ |
Patrick McHardy | 3e9b4600b | 2008-03-25 20:17:55 -0700 | [diff] [blame] | 601 | type = family == AF_INET ? SDP_HDR_CONNECTION_IP4 : |
| 602 | SDP_HDR_CONNECTION_IP6; |
| 603 | if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, type, SDP_HDR_UNSPEC, |
| 604 | &matchoff, &matchlen) > 0) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 605 | |
| 606 | /* We'll drop only if there are parse problems. */ |
| 607 | if (!parse_addr(ct, dptr + matchoff, NULL, &addr, |
YOSHIFUJI Hideaki | 601e68e | 2007-02-12 11:15:49 -0800 | [diff] [blame] | 608 | dptr + datalen)) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 609 | ret = NF_DROP; |
| 610 | goto out; |
| 611 | } |
Patrick McHardy | 3e9b4600b | 2008-03-25 20:17:55 -0700 | [diff] [blame] | 612 | if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, |
| 613 | SDP_HDR_MEDIA, SDP_HDR_UNSPEC, |
| 614 | &matchoff, &matchlen) > 0) { |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 615 | |
| 616 | port = simple_strtoul(dptr + matchoff, NULL, 10); |
| 617 | if (port < 1024) { |
| 618 | ret = NF_DROP; |
| 619 | goto out; |
| 620 | } |
Patrick McHardy | 212440a | 2008-03-25 20:17:13 -0700 | [diff] [blame] | 621 | ret = set_expected_rtp(skb, &dptr, &datalen, |
| 622 | &addr, htons(port)); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 623 | } |
| 624 | } |
| 625 | out: |
| 626 | return ret; |
| 627 | } |
| 628 | |
| 629 | static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly; |
| 630 | static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly; |
| 631 | |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 632 | static const struct nf_conntrack_expect_policy sip_exp_policy = { |
| 633 | .max_expected = 2, |
| 634 | .timeout = 3 * 60, |
| 635 | }; |
| 636 | |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 637 | static void nf_conntrack_sip_fini(void) |
| 638 | { |
| 639 | int i, j; |
| 640 | |
| 641 | for (i = 0; i < ports_c; i++) { |
| 642 | for (j = 0; j < 2; j++) { |
| 643 | if (sip[i][j].me == NULL) |
| 644 | continue; |
| 645 | nf_conntrack_helper_unregister(&sip[i][j]); |
| 646 | } |
| 647 | } |
| 648 | } |
| 649 | |
| 650 | static int __init nf_conntrack_sip_init(void) |
| 651 | { |
| 652 | int i, j, ret; |
| 653 | char *tmpname; |
| 654 | |
| 655 | if (ports_c == 0) |
| 656 | ports[ports_c++] = SIP_PORT; |
| 657 | |
| 658 | for (i = 0; i < ports_c; i++) { |
| 659 | memset(&sip[i], 0, sizeof(sip[i])); |
| 660 | |
| 661 | sip[i][0].tuple.src.l3num = AF_INET; |
| 662 | sip[i][1].tuple.src.l3num = AF_INET6; |
| 663 | for (j = 0; j < 2; j++) { |
| 664 | sip[i][j].tuple.dst.protonum = IPPROTO_UDP; |
| 665 | sip[i][j].tuple.src.u.udp.port = htons(ports[i]); |
Patrick McHardy | 6002f266 | 2008-03-25 20:09:15 -0700 | [diff] [blame] | 666 | sip[i][j].expect_policy = &sip_exp_policy; |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 667 | sip[i][j].me = THIS_MODULE; |
| 668 | sip[i][j].help = sip_help; |
| 669 | |
| 670 | tmpname = &sip_names[i][j][0]; |
| 671 | if (ports[i] == SIP_PORT) |
| 672 | sprintf(tmpname, "sip"); |
| 673 | else |
| 674 | sprintf(tmpname, "sip-%u", i); |
| 675 | sip[i][j].name = tmpname; |
| 676 | |
Patrick McHardy | 0d53778 | 2007-07-07 22:39:38 -0700 | [diff] [blame] | 677 | pr_debug("port #%u: %u\n", i, ports[i]); |
Patrick McHardy | 9fafcd7 | 2006-12-02 22:09:57 -0800 | [diff] [blame] | 678 | |
| 679 | ret = nf_conntrack_helper_register(&sip[i][j]); |
| 680 | if (ret) { |
| 681 | printk("nf_ct_sip: failed to register helper " |
| 682 | "for pf: %u port: %u\n", |
| 683 | sip[i][j].tuple.src.l3num, ports[i]); |
| 684 | nf_conntrack_sip_fini(); |
| 685 | return ret; |
| 686 | } |
| 687 | } |
| 688 | } |
| 689 | return 0; |
| 690 | } |
| 691 | |
| 692 | module_init(nf_conntrack_sip_init); |
| 693 | module_exit(nf_conntrack_sip_fini); |