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)))
