netfilter: nf_conntrack_sip: add TCP support

Add TCP support, which is mandated by RFC3261 for all SIP elements.

SIP over TCP is similar to UDP, except that messages are delimited
by Content-Length: headers and multiple messages may appear in one
packet.

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 176 insertions, 29 deletions

diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 0ec37d6a2df7..1cc75c5a822b 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -16,6 +16,7 @@
 #include <linux/inet.h>
 #include <linux/in.h>
 #include <linux/udp.h>
+#include <linux/tcp.h>
 #include <linux/netfilter.h>
 
 #include <net/netfilter/nf_conntrack.h>
@@ -287,7 +288,8 @@ static const struct sip_header ct_sip_hdrs[] = {
         [SIP_HDR_FROM]                  = SIP_HDR("From", "f", "sip:", skp_epaddr_len),
         [SIP_HDR_TO]                    = SIP_HDR("To", "t", "sip:", skp_epaddr_len),
         [SIP_HDR_CONTACT]               = SIP_HDR("Contact", "m", "sip:", skp_epaddr_len),
-        [SIP_HDR_VIA]                   = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+        [SIP_HDR_VIA_UDP]               = SIP_HDR("Via", "v", "UDP ", epaddr_len),
+        [SIP_HDR_VIA_TCP]               = SIP_HDR("Via", "v", "TCP ", epaddr_len),
         [SIP_HDR_EXPIRES]               = SIP_HDR("Expires", NULL, NULL, digits_len),
         [SIP_HDR_CONTENT_LENGTH]        = SIP_HDR("Content-Length", "l", NULL, digits_len),
 };
@@ -519,6 +521,33 @@ int ct_sip_parse_header_uri(const struct nf_conn *ct, const char *dptr,
 }
 EXPORT_SYMBOL_GPL(ct_sip_parse_header_uri);
 
+static int ct_sip_parse_param(const struct nf_conn *ct, const char *dptr,
+                              unsigned int dataoff, unsigned int datalen,
+                              const char *name,
+                              unsigned int *matchoff, unsigned int *matchlen)
+{
+        const char *limit = dptr + datalen;
+        const char *start;
+        const char *end;
+
+        limit = ct_sip_header_search(dptr + dataoff, limit, ",", strlen(","));
+        if (!limit)
+                limit = dptr + datalen;
+
+        start = ct_sip_header_search(dptr + dataoff, limit, name, strlen(name));
+        if (!start)
+                return 0;
+        start += strlen(name);
+
+        end = ct_sip_header_search(start, limit, ";", strlen(";"));
+        if (!end)
+                end = limit;
+
+        *matchoff = start - dptr;
+        *matchlen = end - start;
+        return 1;
+}
+
 /* Parse address from header parameter and return address, offset and length */
 int ct_sip_parse_address_param(const struct nf_conn *ct, const char *dptr,
                                unsigned int dataoff, unsigned int datalen,
@@ -577,6 +606,29 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
 }
 EXPORT_SYMBOL_GPL(ct_sip_parse_numerical_param);
 
+static int ct_sip_parse_transport(struct nf_conn *ct, const char *dptr,
+                                  unsigned int dataoff, unsigned int datalen,
+                                  u8 *proto)
+{
+        unsigned int matchoff, matchlen;
+
+        if (ct_sip_parse_param(ct, dptr, dataoff, datalen, "transport=",
+                               &matchoff, &matchlen)) {
+                if (!strnicmp(dptr + matchoff, "TCP", strlen("TCP")))
+                        *proto = IPPROTO_TCP;
+                else if (!strnicmp(dptr + matchoff, "UDP", strlen("UDP")))
+                        *proto = IPPROTO_UDP;
+                else
+                        return 0;
+
+                if (*proto != nf_ct_protonum(ct))
+                        return 0;
+        } else
+                *proto = nf_ct_protonum(ct);
+
+        return 1;
+}
+
 /* SDP header parsing: a SDP session description contains an ordered set of
  * headers, starting with a section containing general session parameters,
  * optionally followed by multiple media descriptions.
@@ -685,7 +737,7 @@ static int ct_sip_parse_sdp_addr(const struct nf_conn *ct, const char *dptr,
 
 static int refresh_signalling_expectation(struct nf_conn *ct,
                                           union nf_inet_addr *addr,
-                                          __be16 port,
+                                          u8 proto, __be16 port,
                                           unsigned int expires)
 {
         struct nf_conn_help *help = nfct_help(ct);
@@ -697,6 +749,7 @@ static int refresh_signalling_expectation(struct nf_conn *ct,
         hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
                 if (exp->class != SIP_EXPECT_SIGNALLING ||
                     !nf_inet_addr_cmp(&exp->tuple.dst.u3, addr) ||
+                    exp->tuple.dst.protonum != proto ||
                     exp->tuple.dst.u.udp.port != port)
                         continue;
                 if (!del_timer(&exp->timeout))
@@ -1048,6 +1101,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
         struct nf_conntrack_expect *exp;
         union nf_inet_addr *saddr, daddr;
         __be16 port;
+        u8 proto;
         unsigned int expires = 0;
         int ret;
         typeof(nf_nat_sip_expect_hook) nf_nat_sip_expect;
@@ -1080,6 +1134,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
         if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, &daddr))
                 return NF_ACCEPT;
 
+        if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen, *datalen,
+                                   &proto) == 0)
+                return NF_ACCEPT;
+
         if (ct_sip_parse_numerical_param(ct, *dptr,
                                          matchoff + matchlen, *datalen,
                                          "expires=", NULL, NULL, &expires) < 0)
@@ -1099,7 +1157,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int dataoff,
                 saddr = &ct->tuplehash[!dir].tuple.src.u3;
 
         nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct),
-                          saddr, &daddr, IPPROTO_UDP, NULL, &port);
+                          saddr, &daddr, proto, NULL, &port);
         exp->timeout.expires = sip_timeout * HZ;
         exp->helper = nfct_help(ct)->helper;
         exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
@@ -1132,6 +1190,7 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
         enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
         union nf_inet_addr addr;
         __be16 port;
+        u8 proto;
         unsigned int matchoff, matchlen, coff = 0;
         unsigned int expires = 0;
         int in_contact = 0, ret;
@@ -1172,6 +1231,10 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, &addr))
                         continue;
 
+                if (ct_sip_parse_transport(ct, *dptr, matchoff + matchlen,
+                                           *datalen, &proto) == 0)
+                        continue;
+
                 ret = ct_sip_parse_numerical_param(ct, *dptr,
                                                    matchoff + matchlen,
                                                    *datalen, "expires=",
@@ -1180,7 +1243,8 @@ static int process_register_response(struct sk_buff *skb, unsigned int dataoff,
                         return NF_DROP;
                 if (c_expires == 0)
                         break;
-                if (refresh_signalling_expectation(ct, &addr, port, c_expires))
+                if (refresh_signalling_expectation(ct, &addr, proto, port,
+                                                   c_expires))
                         return NF_ACCEPT;
         }
 
@@ -1265,50 +1329,123 @@ static int process_sip_request(struct sk_buff *skb, unsigned int dataoff,
         return NF_ACCEPT;
 }
 
-static int sip_help(struct sk_buff *skb,
-                    unsigned int protoff,
-                    struct nf_conn *ct,
-                    enum ip_conntrack_info ctinfo)
+static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
+                           unsigned int dataoff, const char **dptr,
+                           unsigned int *datalen)
+{
+        typeof(nf_nat_sip_hook) nf_nat_sip;
+        int ret;
+
+        if (strnicmp(*dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
+                ret = process_sip_request(skb, dataoff, dptr, datalen);
+        else
+                ret = process_sip_response(skb, dataoff, dptr, datalen);
+
+        if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
+                nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
+                if (nf_nat_sip && !nf_nat_sip(skb, dataoff, dptr, datalen))
+                        ret = NF_DROP;
+        }
+
+        return ret;
+}
+
+static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
+                        struct nf_conn *ct, enum ip_conntrack_info ctinfo)
 {
+        struct tcphdr *th, _tcph;
         unsigned int dataoff, datalen;
-        const char *dptr;
+        unsigned int matchoff, matchlen, clen;
+        unsigned int msglen, origlen;
+        const char *dptr, *end;
+        s16 diff, tdiff = 0;
         int ret;
-        typeof(nf_nat_sip_hook) nf_nat_sip;
+
+        if (ctinfo != IP_CT_ESTABLISHED &&
+            ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
+                return NF_ACCEPT;
 
         /* No Data ? */
-        dataoff = protoff + sizeof(struct udphdr);
+        th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
+        if (th == NULL)
+                return NF_ACCEPT;
+        dataoff = protoff + th->doff * 4;
         if (dataoff >= skb->len)
                 return NF_ACCEPT;
 
         nf_ct_refresh(ct, skb, sip_timeout * HZ);
 
-        if (!skb_is_nonlinear(skb))
-                dptr = skb->data + dataoff;
-        else {
+        if (skb_is_nonlinear(skb)) {
                 pr_debug("Copy of skbuff not supported yet.\n");
                 return NF_ACCEPT;
         }
 
+        dptr = skb->data + dataoff;
         datalen = skb->len - dataoff;
         if (datalen < strlen("SIP/2.0 200"))
                 return NF_ACCEPT;
 
-        if (strnicmp(dptr, "SIP/2.0 ", strlen("SIP/2.0 ")) != 0)
-                ret = process_sip_request(skb, dataoff, &dptr, &datalen);
-        else
-                ret = process_sip_response(skb, dataoff, &dptr, &datalen);
+        while (1) {
+                if (ct_sip_get_header(ct, dptr, 0, datalen,
+                                      SIP_HDR_CONTENT_LENGTH,
+                                      &matchoff, &matchlen) <= 0)
+                        break;
 
-        if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
-                nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
-                if (nf_nat_sip && !nf_nat_sip(skb, dataoff, &dptr, &datalen))
-                        ret = NF_DROP;
+                clen = simple_strtoul(dptr + matchoff, (char **)&end, 10);
+                if (dptr + matchoff == end)
+                        break;
+
+                if (end + strlen("\r\n\r\n") > dptr + datalen)
+                        break;
+                if (end[0] != '\r' || end[1] != '\n' ||
+                    end[2] != '\r' || end[3] != '\n')
+                        break;
+                end += strlen("\r\n\r\n") + clen;
+
+                msglen = origlen = end - dptr;
+
+                ret = process_sip_msg(skb, ct, dataoff, &dptr, &msglen);
+                if (ret != NF_ACCEPT)
+                        break;
+                diff     = msglen - origlen;
+                tdiff   += diff;
+
+                dataoff += msglen;
+                dptr    += msglen;
+                datalen  = datalen + diff - msglen;
         }
 
         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 int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
+                        struct nf_conn *ct, enum ip_conntrack_info ctinfo)
+{
+        unsigned int dataoff, datalen;
+        const char *dptr;
+
+        /* No Data ? */
+        dataoff = protoff + sizeof(struct udphdr);
+        if (dataoff >= skb->len)
+                return NF_ACCEPT;
+
+        nf_ct_refresh(ct, skb, sip_timeout * HZ);
+
+        if (skb_is_nonlinear(skb)) {
+                pr_debug("Copy of skbuff not supported yet.\n");
+                return NF_ACCEPT;
+        }
+
+        dptr = skb->data + dataoff;
+        datalen = skb->len - dataoff;
+        if (datalen < strlen("SIP/2.0 200"))
+                return NF_ACCEPT;
+
+        return process_sip_msg(skb, ct, dataoff, &dptr, &datalen);
+}
+
+static struct nf_conntrack_helper sip[MAX_PORTS][4] __read_mostly;
+static char sip_names[MAX_PORTS][4][sizeof("sip-65535")] __read_mostly;
 
 static const struct nf_conntrack_expect_policy sip_exp_policy[SIP_EXPECT_MAX + 1] = {
         [SIP_EXPECT_SIGNALLING] = {
@@ -1333,7 +1470,7 @@ static void nf_conntrack_sip_fini(void)
         int i, j;
 
         for (i = 0; i < ports_c; i++) {
-                for (j = 0; j < 2; j++) {
+                for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
                         if (sip[i][j].me == NULL)
                                 continue;
                         nf_conntrack_helper_unregister(&sip[i][j]);
@@ -1353,14 +1490,24 @@ static int __init nf_conntrack_sip_init(void)
                 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][0].tuple.dst.protonum = IPPROTO_UDP;
+                sip[i][0].help = sip_help_udp;
+                sip[i][1].tuple.src.l3num = AF_INET;
+                sip[i][1].tuple.dst.protonum = IPPROTO_TCP;
+                sip[i][1].help = sip_help_tcp;
+
+                sip[i][2].tuple.src.l3num = AF_INET6;
+                sip[i][2].tuple.dst.protonum = IPPROTO_UDP;
+                sip[i][2].help = sip_help_udp;
+                sip[i][3].tuple.src.l3num = AF_INET6;
+                sip[i][3].tuple.dst.protonum = IPPROTO_TCP;
+                sip[i][3].help = sip_help_tcp;
+
+                for (j = 0; j < ARRAY_SIZE(sip[i]); j++) {
                         sip[i][j].tuple.src.u.udp.port = htons(ports[i]);
                         sip[i][j].expect_policy = sip_exp_policy;
                         sip[i][j].expect_class_max = SIP_EXPECT_MAX;
                         sip[i][j].me = THIS_MODULE;
-                        sip[i][j].help = sip_help;
 
                         tmpname = &sip_names[i][j][0];
                         if (ports[i] == SIP_PORT)