--- /dev/null
+/* SIP extension for IP connection tracking.
+ *
+ * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
+ * based on RR's ip_conntrack_ftp.c and other modules.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/skbuff.h>
+#include <linux/inet.h>
+#include <linux/in.h>
+#include <linux/udp.h>
+#include <linux/netfilter.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <linux/netfilter/nf_conntrack_sip.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
+MODULE_DESCRIPTION("SIP connection tracking helper");
+MODULE_ALIAS("ip_conntrack_sip");
+
+#define MAX_PORTS 8
+static unsigned short ports[MAX_PORTS];
+static int ports_c;
+module_param_array(ports, ushort, &ports_c, 0400);
+MODULE_PARM_DESC(ports, "port numbers of SIP servers");
+
+static unsigned int sip_timeout __read_mostly = SIP_TIMEOUT;
+module_param(sip_timeout, uint, 0600);
+MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
+
+unsigned int (*nf_nat_sip_hook)(struct sk_buff **pskb,
+ enum ip_conntrack_info ctinfo,
+ struct nf_conn *ct,
+ const char **dptr) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
+
+unsigned int (*nf_nat_sdp_hook)(struct sk_buff **pskb,
+ enum ip_conntrack_info ctinfo,
+ struct nf_conntrack_expect *exp,
+ const char *dptr) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);
+
+static int digits_len(struct nf_conn *, const char *, const char *, int *);
+static int epaddr_len(struct nf_conn *, const char *, const char *, int *);
+static int skp_digits_len(struct nf_conn *, const char *, const char *, int *);
+static int skp_epaddr_len(struct nf_conn *, const char *, const char *, int *);
+
+struct sip_header_nfo {
+ const char *lname;
+ const char *sname;
+ const char *ln_str;
+ size_t lnlen;
+ size_t snlen;
+ size_t ln_strlen;
+ int case_sensitive;
+ int (*match_len)(struct nf_conn *, const char *,
+ const char *, int *);
+};
+
+static const struct sip_header_nfo ct_sip_hdrs[] = {
+ [POS_REG_REQ_URI] = { /* SIP REGISTER request URI */
+ .lname = "sip:",
+ .lnlen = sizeof("sip:") - 1,
+ .ln_str = ":",
+ .ln_strlen = sizeof(":") - 1,
+ .match_len = epaddr_len,
+ },
+ [POS_REQ_URI] = { /* SIP request URI */
+ .lname = "sip:",
+ .lnlen = sizeof("sip:") - 1,
+ .ln_str = "@",
+ .ln_strlen = sizeof("@") - 1,
+ .match_len = epaddr_len,
+ },
+ [POS_FROM] = { /* SIP From header */
+ .lname = "From:",
+ .lnlen = sizeof("From:") - 1,
+ .sname = "\r\nf:",
+ .snlen = sizeof("\r\nf:") - 1,
+ .ln_str = "sip:",
+ .ln_strlen = sizeof("sip:") - 1,
+ .match_len = skp_epaddr_len,
+ },
+ [POS_TO] = { /* SIP To header */
+ .lname = "To:",
+ .lnlen = sizeof("To:") - 1,
+ .sname = "\r\nt:",
+ .snlen = sizeof("\r\nt:") - 1,
+ .ln_str = "sip:",
+ .ln_strlen = sizeof("sip:") - 1,
+ .match_len = skp_epaddr_len
+ },
+ [POS_VIA] = { /* SIP Via header */
+ .lname = "Via:",
+ .lnlen = sizeof("Via:") - 1,
+ .sname = "\r\nv:",
+ .snlen = sizeof("\r\nv:") - 1, /* rfc3261 "\r\n" */
+ .ln_str = "UDP ",
+ .ln_strlen = sizeof("UDP ") - 1,
+ .match_len = epaddr_len,
+ },
+ [POS_CONTACT] = { /* SIP Contact header */
+ .lname = "Contact:",
+ .lnlen = sizeof("Contact:") - 1,
+ .sname = "\r\nm:",
+ .snlen = sizeof("\r\nm:") - 1,
+ .ln_str = "sip:",
+ .ln_strlen = sizeof("sip:") - 1,
+ .match_len = skp_epaddr_len
+ },
+ [POS_CONTENT] = { /* SIP Content length header */
+ .lname = "Content-Length:",
+ .lnlen = sizeof("Content-Length:") - 1,
+ .sname = "\r\nl:",
+ .snlen = sizeof("\r\nl:") - 1,
+ .ln_str = ":",
+ .ln_strlen = sizeof(":") - 1,
+ .match_len = skp_digits_len
+ },
+ [POS_MEDIA] = { /* SDP media info */
+ .case_sensitive = 1,
+ .lname = "\nm=",
+ .lnlen = sizeof("\nm=") - 1,
+ .sname = "\rm=",
+ .snlen = sizeof("\rm=") - 1,
+ .ln_str = "audio ",
+ .ln_strlen = sizeof("audio ") - 1,
+ .match_len = digits_len
+ },
+ [POS_OWNER_IP4] = { /* SDP owner address*/
+ .case_sensitive = 1,
+ .lname = "\no=",
+ .lnlen = sizeof("\no=") - 1,
+ .sname = "\ro=",
+ .snlen = sizeof("\ro=") - 1,
+ .ln_str = "IN IP4 ",
+ .ln_strlen = sizeof("IN IP4 ") - 1,
+ .match_len = epaddr_len
+ },
+ [POS_CONNECTION_IP4] = {/* SDP connection info */
+ .case_sensitive = 1,
+ .lname = "\nc=",
+ .lnlen = sizeof("\nc=") - 1,
+ .sname = "\rc=",
+ .snlen = sizeof("\rc=") - 1,
+ .ln_str = "IN IP4 ",
+ .ln_strlen = sizeof("IN IP4 ") - 1,
+ .match_len = epaddr_len
+ },
+ [POS_OWNER_IP6] = { /* SDP owner address*/
+ .case_sensitive = 1,
+ .lname = "\no=",
+ .lnlen = sizeof("\no=") - 1,
+ .sname = "\ro=",
+ .snlen = sizeof("\ro=") - 1,
+ .ln_str = "IN IP6 ",
+ .ln_strlen = sizeof("IN IP6 ") - 1,
+ .match_len = epaddr_len
+ },
+ [POS_CONNECTION_IP6] = {/* SDP connection info */
+ .case_sensitive = 1,
+ .lname = "\nc=",
+ .lnlen = sizeof("\nc=") - 1,
+ .sname = "\rc=",
+ .snlen = sizeof("\rc=") - 1,
+ .ln_str = "IN IP6 ",
+ .ln_strlen = sizeof("IN IP6 ") - 1,
+ .match_len = epaddr_len
+ },
+ [POS_SDP_HEADER] = { /* SDP version header */
+ .case_sensitive = 1,
+ .lname = "\nv=",
+ .lnlen = sizeof("\nv=") - 1,
+ .sname = "\rv=",
+ .snlen = sizeof("\rv=") - 1,
+ .ln_str = "=",
+ .ln_strlen = sizeof("=") - 1,
+ .match_len = digits_len
+ }
+};
+
+/* get line lenght until first CR or LF seen. */
+int ct_sip_lnlen(const char *line, const char *limit)
+{
+ const char *k = line;
+
+ while ((line <= limit) && (*line == '\r' || *line == '\n'))
+ line++;
+
+ while (line <= limit) {
+ if (*line == '\r' || *line == '\n')
+ break;
+ line++;
+ }
+ return line - k;
+}
+EXPORT_SYMBOL_GPL(ct_sip_lnlen);
+
+/* Linear string search, case sensitive. */
+const char *ct_sip_search(const char *needle, const char *haystack,
+ size_t needle_len, size_t haystack_len,
+ int case_sensitive)
+{
+ const char *limit = haystack + (haystack_len - needle_len);
+
+ while (haystack <= limit) {
+ if (case_sensitive) {
+ if (strncmp(haystack, needle, needle_len) == 0)
+ return haystack;
+ } else {
+ if (strnicmp(haystack, needle, needle_len) == 0)
+ return haystack;
+ }
+ haystack++;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(ct_sip_search);
+
+static int digits_len(struct nf_conn *ct, const char *dptr,
+ const char *limit, int *shift)
+{
+ int len = 0;
+ while (dptr <= limit && isdigit(*dptr)) {
+ dptr++;
+ len++;
+ }
+ return len;
+}
+
+/* get digits lenght, skiping blank spaces. */
+static int skp_digits_len(struct nf_conn *ct, const char *dptr,
+ const char *limit, int *shift)
+{
+ for (; dptr <= limit && *dptr == ' '; dptr++)
+ (*shift)++;
+
+ return digits_len(ct, dptr, limit, shift);
+}
+
+static int parse_addr(struct nf_conn *ct, const char *cp, const char **endp,
+ union nf_conntrack_address *addr, const char *limit)
+{
+ const char *end;
+ int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
+ int ret = 0;
+
+ switch (family) {
+ case AF_INET:
+ ret = in4_pton(cp, limit - cp, (u8 *)&addr->ip, -1, &end);
+ break;
+ case AF_INET6:
+ ret = in6_pton(cp, limit - cp, (u8 *)&addr->ip6, -1, &end);
+ break;
+ default:
+ BUG();
+ }
+
+ if (ret == 0 || end == cp)
+ return 0;
+ if (endp)
+ *endp = end;
+ return 1;
+}
+
+/* skip ip address. returns its length. */
+static int epaddr_len(struct nf_conn *ct, const char *dptr,
+ const char *limit, int *shift)
+{
+ union nf_conntrack_address addr;
+ const char *aux = dptr;
+
+ if (!parse_addr(ct, dptr, &dptr, &addr, limit)) {
+ DEBUGP("ip: %s parse failed.!\n", dptr);
+ return 0;
+ }
+
+ /* Port number */
+ if (*dptr == ':') {
+ dptr++;
+ dptr += digits_len(ct, dptr, limit, shift);
+ }
+ return dptr - aux;
+}
+
+/* get address length, skiping user info. */
+static int skp_epaddr_len(struct nf_conn *ct, const char *dptr,
+ const char *limit, int *shift)
+{
+ int s = *shift;
+
+ /* Search for @, but stop at the end of the line.
+ * We are inside a sip: URI, so we don't need to worry about
+ * continuation lines. */
+ while (dptr <= limit &&
+ *dptr != '@' && *dptr != '\r' && *dptr != '\n') {
+ (*shift)++;
+ dptr++;
+ }
+
+ if (dptr <= limit && *dptr == '@') {
+ dptr++;
+ (*shift)++;
+ } else
+ *shift = s;
+
+ return epaddr_len(ct, dptr, limit, shift);
+}
+
+/* Returns 0 if not found, -1 error parsing. */
+int ct_sip_get_info(struct nf_conn *ct,
+ const char *dptr, size_t dlen,
+ unsigned int *matchoff,
+ unsigned int *matchlen,
+ enum sip_header_pos pos)
+{
+ const struct sip_header_nfo *hnfo = &ct_sip_hdrs[pos];
+ const char *limit, *aux, *k = dptr;
+ int shift = 0;
+
+ limit = dptr + (dlen - hnfo->lnlen);
+
+ while (dptr <= limit) {
+ if ((strncmp(dptr, hnfo->lname, hnfo->lnlen) != 0) &&
+ (strncmp(dptr, hnfo->sname, hnfo->snlen) != 0)) {
+ dptr++;
+ continue;
+ }
+ aux = ct_sip_search(hnfo->ln_str, dptr, hnfo->ln_strlen,
+ ct_sip_lnlen(dptr, limit),
+ hnfo->case_sensitive);
+ if (!aux) {
+ DEBUGP("'%s' not found in '%s'.\n", hnfo->ln_str,
+ hnfo->lname);
+ return -1;
+ }
+ aux += hnfo->ln_strlen;
+
+ *matchlen = hnfo->match_len(ct, aux, limit, &shift);
+ if (!*matchlen)
+ return -1;
+
+ *matchoff = (aux - k) + shift;
+
+ DEBUGP("%s match succeeded! - len: %u\n", hnfo->lname,
+ *matchlen);
+ return 1;
+ }
+ DEBUGP("%s header not found.\n", hnfo->lname);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(ct_sip_get_info);
+
+static int set_expected_rtp(struct sk_buff **pskb,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ union nf_conntrack_address *addr,
+ __be16 port,
+ const char *dptr)
+{
+ struct nf_conntrack_expect *exp;
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ int family = ct->tuplehash[!dir].tuple.src.l3num;
+ int ret;
+ typeof(nf_nat_sdp_hook) nf_nat_sdp;
+
+ exp = nf_conntrack_expect_alloc(ct);
+ if (exp == NULL)
+ return NF_DROP;
+ nf_conntrack_expect_init(exp, family,
+ &ct->tuplehash[!dir].tuple.src.u3, addr,
+ IPPROTO_UDP, NULL, &port);
+
+ nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook);
+ if (nf_nat_sdp && ct->status & IPS_NAT_MASK)
+ ret = nf_nat_sdp(pskb, ctinfo, exp, dptr);
+ else {
+ if (nf_conntrack_expect_related(exp) != 0)
+ ret = NF_DROP;
+ else
+ ret = NF_ACCEPT;
+ }
+ nf_conntrack_expect_put(exp);
+
+ return ret;
+}
+
+static int sip_help(struct sk_buff **pskb,
+ unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
+ union nf_conntrack_address addr;
+ unsigned int dataoff, datalen;
+ const char *dptr;
+ int ret = NF_ACCEPT;
+ int matchoff, matchlen;
+ u_int16_t port;
+ enum sip_header_pos pos;
+ typeof(nf_nat_sip_hook) nf_nat_sip;
+
+ /* No Data ? */
+ dataoff = protoff + sizeof(struct udphdr);
+ if (dataoff >= (*pskb)->len)
+ return NF_ACCEPT;
+
+ nf_ct_refresh(ct, *pskb, sip_timeout * HZ);
+
+ if (!skb_is_nonlinear(*pskb))
+ dptr = (*pskb)->data + dataoff;
+ else {
+ DEBUGP("Copy of skbuff not supported yet.\n");
+ goto out;
+ }
+
+ nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
+ if (nf_nat_sip && ct->status & IPS_NAT_MASK) {
+ if (!nf_nat_sip(pskb, ctinfo, ct, &dptr)) {
+ ret = NF_DROP;
+ goto out;
+ }
+ }
+
+ datalen = (*pskb)->len - dataoff;
+ if (datalen < sizeof("SIP/2.0 200") - 1)
+ goto out;
+
+ /* RTP info only in some SDP pkts */
+ if (memcmp(dptr, "INVITE", sizeof("INVITE") - 1) != 0 &&
+ memcmp(dptr, "SIP/2.0 200", sizeof("SIP/2.0 200") - 1) != 0) {
+ goto out;
+ }
+ /* Get address and port from SDP packet. */
+ pos = family == AF_INET ? POS_CONNECTION_IP4 : POS_CONNECTION_IP6;
+ if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen, pos) > 0) {
+
+ /* We'll drop only if there are parse problems. */
+ if (!parse_addr(ct, dptr + matchoff, NULL, &addr,
+ dptr + datalen)) {
+ ret = NF_DROP;
+ goto out;
+ }
+ if (ct_sip_get_info(ct, dptr, datalen, &matchoff, &matchlen,
+ POS_MEDIA) > 0) {
+
+ port = simple_strtoul(dptr + matchoff, NULL, 10);
+ if (port < 1024) {
+ ret = NF_DROP;
+ goto out;
+ }
+ ret = set_expected_rtp(pskb, ct, ctinfo, &addr,
+ htons(port), dptr);
+ }
+ }
+out:
+ return ret;
+}
+
+static struct nf_conntrack_helper sip[MAX_PORTS][2] __read_mostly;
+static char sip_names[MAX_PORTS][2][sizeof("sip-65535")] __read_mostly;
+
+static void nf_conntrack_sip_fini(void)
+{
+ int i, j;
+
+ for (i = 0; i < ports_c; i++) {
+ for (j = 0; j < 2; j++) {
+ if (sip[i][j].me == NULL)
+ continue;
+ nf_conntrack_helper_unregister(&sip[i][j]);
+ }
+ }
+}
+
+static int __init nf_conntrack_sip_init(void)
+{
+ int i, j, ret;
+ char *tmpname;
+
+ if (ports_c == 0)
+ ports[ports_c++] = SIP_PORT;
+
+ for (i = 0; i < ports_c; i++) {
+ memset(&sip[i], 0, sizeof(sip[i]));
+
+ sip[i][0].tuple.src.l3num = AF_INET;
+ sip[i][1].tuple.src.l3num = AF_INET6;
+ for (j = 0; j < 2; j++) {
+ sip[i][j].tuple.dst.protonum = IPPROTO_UDP;
+ sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
+ sip[i][j].mask.src.l3num = 0xFFFF;
+ sip[i][j].mask.src.u.udp.port = htons(0xFFFF);
+ sip[i][j].mask.dst.protonum = 0xFF;
+ sip[i][j].max_expected = 2;
+ sip[i][j].timeout = 3 * 60; /* 3 minutes */
+ sip[i][j].me = THIS_MODULE;
+ sip[i][j].help = sip_help;
+
+ tmpname = &sip_names[i][j][0];
+ if (ports[i] == SIP_PORT)
+ sprintf(tmpname, "sip");
+ else
+ sprintf(tmpname, "sip-%u", i);
+ sip[i][j].name = tmpname;
+
+ DEBUGP("port #%u: %u\n", i, ports[i]);
+
+ ret = nf_conntrack_helper_register(&sip[i][j]);
+ if (ret) {
+ printk("nf_ct_sip: failed to register helper "
+ "for pf: %u port: %u\n",
+ sip[i][j].tuple.src.l3num, ports[i]);
+ nf_conntrack_sip_fini();
+ return ret;
+ }
+ }
+ }
+ return 0;
+}
+
+module_init(nf_conntrack_sip_init);
+module_exit(nf_conntrack_sip_fini);
git://git.onelab.eu / linux-2.6.git / blobdiff