From cfd6c38096d75c8b86782683c5f45c415a505b78 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 3 May 2007 03:35:31 -0700 Subject: [PATCH] [NETFILTER]: sip: Fix RTP address NAT I needed to use this recently to talk to a Cisco server. In my case I only did SNAT while the Cisco server used a different address for RTP traffic than the one for SIP. I discovered that nf_nat_sip NATed the RTP address to the SIP one which was unnecessary but OK. However, in doing so it did not DNAT the destination address on the RTP traffic to the Cisco back to the original RTP address. This patch corrects this by noting down the RTP address and using it when the expectation fires. Signed-off-by: Herbert Xu Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/ipv4/netfilter/nf_nat_sip.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c index bfd88e4e0685..fac97cf51ae5 100644 --- a/net/ipv4/netfilter/nf_nat_sip.c +++ b/net/ipv4/netfilter/nf_nat_sip.c @@ -222,6 +222,29 @@ static unsigned int mangle_sdp(struct sk_buff **pskb, return mangle_content_len(pskb, ctinfo, ct, dptr); } +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); + + /* 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; + /* hook doesn't matter, but it has to do source manip */ + nf_nat_setup_info(ct, &range, NF_IP_POST_ROUTING); + + /* 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; + /* hook doesn't matter, but it has to do destination manip */ + nf_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING); +} + /* 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 **pskb, @@ -239,13 +262,14 @@ static unsigned int ip_nat_sdp(struct sk_buff **pskb, /* Connection will come from reply */ newip = ct->tuplehash[!dir].tuple.dst.u3.ip; + 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; /* When you see the packet, we need to NAT it the same as the this one. */ - exp->expectfn = nf_nat_follow_master; + exp->expectfn = ip_nat_sdp_expect; /* Try to get same port: if not, try to change it. */ for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) { -- 2.20.1