netdev - Re: [PATCH] xfrm6: Do not use xfrm_local_error for path MTU issues in tunnels

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20150528045622.GE27342@secunet.com>
Date:	Thu, 28 May 2015 06:56:22 +0200
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	Alexander Duyck <alexander.h.duyck@...hat.com>,
	<davem@...emloft.net>, <netdev@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>
Subject: Re: [PATCH] xfrm6: Do not use xfrm_local_error for path MTU issues
 in tunnels

On Thu, May 28, 2015 at 12:49:19PM +0800, Herbert Xu wrote:
> On Wed, May 27, 2015 at 10:40:32AM -0700, Alexander Duyck wrote:
> > This change makes it so that we use icmpv6_send to report PMTU issues back
> > into tunnels in the case that the resulting packet is larger than the MTU
> > of the outgoing interface.  Previously xfrm_local_error was being used in
> > this case, however this was resulting in no changes, I suspect due to the
> > fact that the tunnel itself was being kept out of the loop.
> > 
> > This patch fixes PMTU problems seen on ip6_vti tunnels and is based on the
> > behavior seen if the socket was orphaned.  Instead of requiring the socket
> > to be orphaned this patch simply defaults to using icmpv6_send in the case
> > that the frame came though a tunnel.
> > 
> > Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
> 
> Does this still work with normal tunnel mode and identical inner
> and outer addresses? I recall we used to have a bug where in that
> situation the kernel would interpret the ICMP message as a reduction
> in outer MTU and thus resulting in a loop where the MTU keeps
> getting smaller.

Right, I think this reintroduces a bug that I fixed some years ago with
commit dd767856a36e ("xfrm6: Don't call icmpv6_send on local error")
--
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