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authorPatrick McHardy <kaber@trash.net>2008-03-25 20:25:13 -0700
committerDavid S. Miller <davem@davemloft.net>2008-03-25 20:25:13 -0700
commit0f32a40fc91a9ebbbf66e826ac2a829ab37d9cf8 (patch)
tree0c221d19a91fa5ab4d746480438ea0f47031062d /net/ipv4/netfilter
parentc978cd3a937141deaf7995b849824af6dacdeae7 (diff)
[NETFILTER]: nf_conntrack_sip: create signalling expectations
Create expectations for incoming signalling connections when seeing a REGISTER request. This is needed when the registrar uses a different source port number for signalling messages and for receiving incoming calls from other endpoints than the registrar. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/netfilter')
-rw-r--r--net/ipv4/netfilter/nf_nat_sip.c111
1 files changed, 89 insertions, 22 deletions
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index b443618a857f..4b85e21a2a4a 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -205,6 +205,91 @@ next:
return NF_ACCEPT;
}
+/* Handles expected signalling connections and media streams */
+static void ip_nat_sip_expected(struct nf_conn *ct,
+ struct nf_conntrack_expect *exp)
+{
+ struct nf_nat_range range;
+
+ /* This must be a fresh one. */
+ BUG_ON(ct->status & IPS_NAT_DONE_MASK);
+
+ /* For DST manip, map port here to where it's expected. */
+ range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+ range.min = range.max = exp->saved_proto;
+ range.min_ip = range.max_ip = exp->saved_ip;
+ nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
+
+ /* Change src to where master sends to, but only if the connection
+ * actually came from the same source. */
+ if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
+ ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip
+ = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
+ nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
+ }
+}
+
+static unsigned int ip_nat_sip_expect(struct sk_buff *skb,
+ const char **dptr, unsigned int *datalen,
+ struct nf_conntrack_expect *exp,
+ unsigned int matchoff,
+ unsigned int matchlen)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ __be32 newip;
+ u_int16_t port;
+ char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
+ unsigned buflen;
+
+ /* Connection will come from reply */
+ if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
+ newip = exp->tuple.dst.u3.ip;
+ else
+ newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
+
+ /* If the signalling port matches the connection's source port in the
+ * original direction, try to use the destination port in the opposite
+ * direction. */
+ if (exp->tuple.dst.u.udp.port ==
+ ct->tuplehash[dir].tuple.src.u.udp.port)
+ port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
+ else
+ port = ntohs(exp->tuple.dst.u.udp.port);
+
+ exp->saved_ip = exp->tuple.dst.u3.ip;
+ exp->tuple.dst.u3.ip = newip;
+ exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
+ exp->dir = !dir;
+ exp->expectfn = ip_nat_sip_expected;
+
+ for (; port != 0; port++) {
+ exp->tuple.dst.u.udp.port = htons(port);
+ if (nf_ct_expect_related(exp) == 0)
+ break;
+ }
+
+ if (port == 0)
+ return NF_DROP;
+
+ if (exp->tuple.dst.u3.ip != exp->saved_ip ||
+ exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
+ buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
+ NIPQUAD(newip), port);
+ if (!mangle_packet(skb, dptr, datalen, matchoff, matchlen,
+ buffer, buflen))
+ goto err;
+ }
+ return NF_ACCEPT;
+
+err:
+ nf_ct_unexpect_related(exp);
+ return NF_DROP;
+}
+
static int mangle_content_len(struct sk_buff *skb,
const char **dptr, unsigned int *datalen)
{
@@ -275,27 +360,6 @@ static unsigned int mangle_sdp(struct sk_buff *skb,
return mangle_content_len(skb, dptr, datalen);
}
-static void ip_nat_sdp_expect(struct nf_conn *ct,
- struct nf_conntrack_expect *exp)
-{
- struct nf_nat_range range;
-
- /* This must be a fresh one. */
- BUG_ON(ct->status & IPS_NAT_DONE_MASK);
-
- /* For DST manip, map port here to where it's expected. */
- range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
- range.min = range.max = exp->saved_proto;
- range.min_ip = range.max_ip = exp->saved_ip;
- nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
-
- /* Change src to where master sends to */
- range.flags = IP_NAT_RANGE_MAP_IPS;
- range.min_ip = range.max_ip
- = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
- nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
-}
-
/* So, this packet has hit the connection tracking matching code.
Mangle it, and change the expectation to match the new version. */
static unsigned int ip_nat_sdp(struct sk_buff *skb,
@@ -322,7 +386,7 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
/* When you see the packet, we need to NAT it the same as the
this one. */
- exp->expectfn = ip_nat_sdp_expect;
+ exp->expectfn = ip_nat_sip_expected;
/* Try to get same port: if not, try to change it. */
for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
@@ -344,6 +408,7 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
static void __exit nf_nat_sip_fini(void)
{
rcu_assign_pointer(nf_nat_sip_hook, NULL);
+ rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_hook, NULL);
synchronize_rcu();
}
@@ -351,8 +416,10 @@ static void __exit nf_nat_sip_fini(void)
static int __init nf_nat_sip_init(void)
{
BUG_ON(nf_nat_sip_hook != NULL);
+ BUG_ON(nf_nat_sip_expect_hook != NULL);
BUG_ON(nf_nat_sdp_hook != NULL);
rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
+ rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
return 0;
}