From c7f485abd618e0d249bdd1abdc586bd10fee1954 Mon Sep 17 00:00:00 2001
From: Patrick McHardy <kaber@trash.net>
Date: Tue, 25 Mar 2008 20:26:43 -0700
Subject: [PATCH] [NETFILTER]: nf_conntrack_sip: RTP routing optimization
Optimize call routing between NATed endpoints: when an external
registrar sends a media description that contains an existing RTP
expectation from a different SNATed connection, the gatekeeper
is trying to route the call directly between the two endpoints.
We assume both endpoints can reach each other directly and
"un-NAT" the addresses, which makes the media stream go between
the two endpoints directly.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/netfilter/nf_conntrack_sip.h | 6 +++
net/ipv4/netfilter/nf_nat_sip.c | 3 ++
net/netfilter/nf_conntrack_sip.c | 59 ++++++++++++++++++----
3 files changed, 58 insertions(+), 10 deletions(-)
diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index 71fa3eb5f485..5da04e586a3f 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -114,6 +114,12 @@ extern unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb,
enum sdp_header_types type,
enum sdp_header_types term,
const union nf_inet_addr *addr);
+extern unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
+ const char **dptr,
+ unsigned int *datalen,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ u_int16_t port);
extern unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int dataoff,
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index 4429069d9b42..bcddccddf768 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -461,6 +461,7 @@ 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_addr_hook, NULL);
+ rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_session_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_media_hook, NULL);
synchronize_rcu();
@@ -471,11 +472,13 @@ 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_addr_hook != NULL);
+ BUG_ON(nf_nat_sdp_port_hook != NULL);
BUG_ON(nf_nat_sdp_session_hook != NULL);
BUG_ON(nf_nat_sdp_media_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_addr_hook, ip_nat_sdp_addr);
+ rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
rcu_assign_pointer(nf_nat_sdp_session_hook, ip_nat_sdp_session);
rcu_assign_pointer(nf_nat_sdp_media_hook, ip_nat_sdp_media);
return 0;
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index f40a525732d1..57de22c770a3 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -70,6 +70,14 @@ unsigned int (*nf_nat_sdp_addr_hook)(struct sk_buff *skb,
__read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sdp_addr_hook);
+unsigned int (*nf_nat_sdp_port_hook)(struct sk_buff *skb,
+ const char **dptr,
+ unsigned int *datalen,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ u_int16_t port) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_sdp_port_hook);
+
unsigned int (*nf_nat_sdp_session_hook)(struct sk_buff *skb,
const char **dptr,
unsigned int dataoff,
@@ -730,9 +738,10 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
union nf_inet_addr *saddr;
struct nf_conntrack_tuple tuple;
int family = ct->tuplehash[!dir].tuple.src.l3num;
- int skip_expect = 0, ret = NF_DROP;
+ int direct_rtp = 0, skip_expect = 0, ret = NF_DROP;
u_int16_t base_port;
__be16 rtp_port, rtcp_port;
+ typeof(nf_nat_sdp_port_hook) nf_nat_sdp_port;
typeof(nf_nat_sdp_media_hook) nf_nat_sdp_media;
saddr = NULL;
@@ -746,6 +755,14 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
* to register it since we can see the same media description multiple
* times on different connections in case multiple endpoints receive
* the same call.
+ *
+ * RTP optimization: if we find a matching media channel expectation
+ * and both the expectation and this connection are SNATed, we assume
+ * both sides can reach each other directly and use the final
+ * destination address from the expectation. We still need to keep
+ * the NATed expectations for media that might arrive from the
+ * outside, and additionally need to expect the direct RTP stream
+ * in case it passes through us even without NAT.
*/
memset(&tuple, 0, sizeof(tuple));
if (saddr)
@@ -756,20 +773,42 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
tuple.dst.u.udp.port = port;
rcu_read_lock();
- exp = __nf_ct_expect_find(&tuple);
- if (exp && exp->master != ct &&
- nfct_help(exp->master)->helper == nfct_help(ct)->helper &&
- exp->class == class)
- skip_expect = 1;
- rcu_read_unlock();
+ do {
+ exp = __nf_ct_expect_find(&tuple);
- if (skip_expect)
- return NF_ACCEPT;
+ if (!exp || exp->master == ct ||
+ nfct_help(exp->master)->helper != nfct_help(ct)->helper ||
+ exp->class != class)
+ break;
+
+ if (exp->tuple.src.l3num == AF_INET && !direct_rtp &&
+ (exp->saved_ip != exp->tuple.dst.u3.ip ||
+ exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
+ ct->status & IPS_NAT_MASK) {
+ daddr->ip = exp->saved_ip;
+ tuple.dst.u3.ip = exp->saved_ip;
+ tuple.dst.u.udp.port = exp->saved_proto.udp.port;
+ direct_rtp = 1;
+ } else
+ skip_expect = 1;
+ } while (!skip_expect);
+ rcu_read_unlock();
base_port = ntohs(tuple.dst.u.udp.port) & ~1;
rtp_port = htons(base_port);
rtcp_port = htons(base_port + 1);
+ if (direct_rtp) {
+ nf_nat_sdp_port = rcu_dereference(nf_nat_sdp_port_hook);
+ if (nf_nat_sdp_port &&
+ !nf_nat_sdp_port(skb, dptr, datalen,
+ mediaoff, medialen, ntohs(rtp_port)))
+ goto err1;
+ }
+
+ if (skip_expect)
+ return NF_ACCEPT;
+
rtp_exp = nf_ct_expect_alloc(ct);
if (rtp_exp == NULL)
goto err1;
@@ -783,7 +822,7 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb,
IPPROTO_UDP, NULL, &rtcp_port);
nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
- if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK)
+ if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
ret = nf_nat_sdp_media(skb, dptr, datalen, rtp_exp, rtcp_exp,
mediaoff, medialen, daddr);
else {
--
2.20.1