From: Ashwanth Goli <ashwanth@codeaurora.org>
To: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, maloney@google.com, edumazet@google.com,
David Ahern <dsahern@gmail.com>,
netdev-owner@vger.kernel.org
Subject: Re: ip6-in-ip{4,6} ipsec tunnel issues with 1280 MTU
Date: Fri, 27 Apr 2018 16:32:06 +0530 [thread overview]
Message-ID: <a3e39b94de731f86d2e9ecd8f0230643@codeaurora.org> (raw)
In-Reply-To: <1524743477.2658.38.camel@redhat.com>
On 2018-04-26 17:21, Paolo Abeni wrote:
> Hi,
>
> [fixed CC list]
>
> On Wed, 2018-04-25 at 21:43 +0530, Ashwanth Goli wrote:
>> Hi Pablo,
>
> Actually I'm Paolo, but yours is a recurring mistake ;)
>
>> I am noticing an issue similar to the one reported by Alexis Perez
>> [Regression for ip6-in-ip4 IPsec tunnel in 4.14.16]
>>
>> In my IPsec setup outer MTU is set to 1280, ip6_setup_cork sees an MTU
>> less than IPV6_MIN_MTU because of the tunnel headers. -EINVAL is being
>> returned as a result of the MTU check that got added with below patch.
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/net/ipv6/ip6_output.c?h=v4.14.34&id=8278804e05f6bcfe3fdfea4a404020752ead15a6
>>
>> Can we remove this MTU check since your recent patch [ipv6: the entire
>> IPv6 header chain must fit the first fragment] fixes a similar issue?
>
> AFAICS, RFC 2473 implies we can have MTU below 1280 for tunnel devices
> so we can probably relax the MTU check for such devices, but I think we
> would still need it in the general case.
>
> Cheers,
>
> Paolo
Should I send out the following change as a patch?
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 2e891d2..c4c3313 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1235,7 +1235,7 @@ static int ip6_setup_cork(struct sock *sk, struct
inet_cork_full *cork,
if (np->frag_size)
mtu = np->frag_size;
}
- if (mtu < IPV6_MIN_MTU)
+ if (!(rt->dst.flags & DST_XFRM_TUNNEL) && mtu < IPV6_MIN_MTU)
return -EINVAL;
cork->base.fragsize = mtu;
if (dst_allfrag(xfrm_dst_path(&rt->dst)))
next prev parent reply other threads:[~2018-04-27 11:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <c3a1f2fc545b622bbb362e98313d7eba@codeaurora.org>
2018-04-26 11:51 ` ip6-in-ip{4,6} ipsec tunnel issues with 1280 MTU Paolo Abeni
2018-04-27 11:02 ` Ashwanth Goli [this message]
2018-04-27 14:48 ` David Ahern
2018-04-27 15:44 ` Ashwanth Goli
2018-04-29 1:05 ` David Ahern
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