netdev - Re: [PATCH]: double SAs are created when using AH and ESP together

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Date:	Fri, 09 Mar 2007 19:54:15 -0500
From:	Eric Paris <eparis@...hat.com>
To:	David Miller <davem@...emloft.net>
Cc:	latten@...tin.ibm.com, netdev@...r.kernel.org,
	herbert@...dor.apana.org.au, jmorris@...ei.org, paul.moore@...com,
	vyekkirala@...stedCS.com
Subject: Re: [PATCH]: double SAs are created when using AH and ESP together

On Fri, 2007-03-09 at 16:20 -0800, David Miller wrote:
> From: Joy Latten <latten@...tin.ibm.com>
> Date: Fri, 9 Mar 2007 17:14:54 -0600
> 
> > I noticed that in xfrm_state_add we look for the larval SA in a few
> > places without checking for protocol match. So when using both 
> > AH and ESP, whichever one gets added first, deletes the larval SA. 
> > It seems AH always gets added first and ESP is always the larval 
> > SA's protocol since the xfrm->tmpl has it first. Thus causing the
> > additional km_query()
> > 
> > Adding the check eliminates the double SA creation. 
> > I know this may not seem like a complete solution and I will 
> > continue to test and be on the lookout, but isn't having the
> > check a good thing? So far I have tested SAs with just ESP, just AH
> > and with both and all seems ok. 
> > 
> > Please let me know if this patch is ok. 
> > My kernel was 2.6.20-rc3-git3.
> > 
> > Signed-off-by: Joy Latten <latten@...tin.ibm.com>
> 
> Generally it looks OK, but I'm going to let this one sit for
> a while before I apply it so that other folks can review it
> too and spot any unintended consequences.
> 
> In particular, I find it strance that we didn't check the
> protocol field all this time and I wonder whether that might
> be on purpose for some reason.

At least the first hunk of this patch used to be checked back in
net/ipv4/xfrm4_state.c in __xfrm4_find_acq and looks like it just was
accidentally forgotten when there was a transition to using
__find_acq_core

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2770834c9f44afd1bfa13914c7285470775af657

Since Joy found this problem on a 2.6.18 kernel originally which was
before this diff and had the proto check I'm guessing it is actually the
second hunk which is more relevant to the problem.

-Eric

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