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netfilter: nf_ct_h323: fix bug in rtcp natting

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The nat_rtp_rtcp hook takes two separate parameters port and rtp_port.

port is expected to be the real h245 address (found inside the packet).
rtp_port is the even number closest to port (RTP ports are even and
RTCP ports are odd).

However currently, both port and rtp_port are having same value (both are
rounded to nearest even numbers).

This works well in case of openlogicalchannel with media (RTP/even) port.

But in case of openlogicalchannel for media control (RTCP/odd) port,
h245 address in the packet is wrongly modified to have an even port.

I am attaching a pcap demonstrating the problem, for any further analysis.

This behavior was introduced around v2.6.19 while rewriting the helper.

Signed-off-by: Jagdish Motwani <jagdish.motwani@elitecore.com>
Signed-off-by: Sanket Shah <sanket.shah@elitecore.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2012-06-04 13:31:04 +02:00
parent d1992b169d
commit d109e9af61
1 changed files with 2 additions and 3 deletions
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5
net/netfilter/nf_conntrack_h323_main.c
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@ -270,9 +270,8 @@ static int expect_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
return 0;
/* RTP port is even */
port &= htons(~1);
rtp_port = port;
rtcp_port = htons(ntohs(port) + 1);
rtp_port = port & ~htons(1);
rtcp_port = port | htons(1);
/* Create expect for RTP */
if ((rtp_exp = nf_ct_expect_alloc(ct)) == NULL)