From: Sabrina Dubroca <sd@queasysnail.net>
To: Jiri Bohac <jbohac@suse.cz>
Cc: Mike Maloney <maloneykernel@gmail.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
davem@davemloft.net, netdev@vger.kernel.org,
Steffen Klassert <steffen.klassert@secunet.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: Re: [RFC PATCH] fix xfrm MTU regression
Date: Thu, 29 Apr 2021 21:48:09 +0200 [thread overview]
Message-ID: <YIsNeUTQ7qjzhpos@hog> (raw)
In-Reply-To: <20210429170254.5grfgsz2hgy2qjhk@dwarf.suse.cz>
2021-04-29, 19:02:54 +0200, Jiri Bohac wrote:
> Hi,
>
> Commit 749439bfac6e1a2932c582e2699f91d329658196 ("ipv6: fix udpv6
> sendmsg crash caused by too small MTU") breaks PMTU for xfrm.
>
> A Packet Too Big ICMPv6 message received in response to an ESP
> packet will prevent all further communication through the tunnel
> if the reported MTU minus the ESP overhead is smaller than 1280.
>
> E.g. in a case of a tunnel-mode ESP with sha256/aes the overhead
> is 92 bytes. Receiving a PTB with MTU of 1371 or less will result
> in all further packets in the tunnel dropped. A ping through the
> tunnel fails with "ping: sendmsg: Invalid argument".
>
> Apparently the MTU on the xfrm route is smaller than 1280 and
> fails the check inside ip6_setup_cork() added by 749439bf.
>
> We found this by debugging USGv6/ipv6ready failures. Failing
> tests are: "Phase-2 Interoperability Test Scenario IPsec" /
> 5.3.11 and 5.4.11 (Tunnel Mode: Fragmentation).
That should be fixed with commit b515d2637276 ("xfrm: xfrm_state_mtu
should return at least 1280 for ipv6"), currently in Steffen's ipsec
tree:
https://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec.git/commit/?id=b515d2637276
--
Sabrina
next prev parent reply other threads:[~2021-04-29 19:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 17:02 [RFC PATCH] fix xfrm MTU regression Jiri Bohac
2021-04-29 19:48 ` Sabrina Dubroca [this message]
2021-04-29 20:25 ` Jiri Bohac
2021-05-01 10:23 ` Sabrina Dubroca
2021-04-30 5:36 ` [RFC PATCH v2] " Jiri Bohac
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