netdev - Re: H.245v10+ support in nf_conntrack

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20090908130424.GB7273@urbino.open.ch>
Date:	Tue, 8 Sep 2009 15:04:24 +0200
From:	Andreas Jaggi <aj@...n.ch>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Jing Min Zhao <zhaojingmin@...rs.sourceforge.net>,
	netdev@...r.kernel.org
Subject: Re: H.245v10+ support in nf_conntrack_h323?

By using the tcpdumps made during the video conferencing test, I was
able to reproduce the problem with tcpreplay.

Further investigation (eg. sprinkling a couple printks over
nf_conntrack_h323_main.c) showed that the H.245 packet is dropped
because the __nf_ct_expect_check() fails with -EMFILE.
This because max_expected of the H.245 expect policy is reached.

max_expected is set to 'H323_RTP_CHANNEL_MAX * 4 + 2' in
nf_conntrack_h323_main.c and H323_RTP_CHANNEL_MAX is defined as '4'.

Increasing H323_RTP_CHANNEL_MAX solves the problem that H.245 packets
are dropped!

Now I would like to propose a patch to fix this permanently, but I don't
know what a reasonable value for H323_RTP_CHANNEL_MAX would be (only
that the current value is too low for our video conferencing setup).

How was the current value of H323_RTP_CHANNEL_MAX determined? And what
would be the implications of increasing this value?

Andreas
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html