From: Alexander Duyck Subject: [PATCH] xfrm6: Do not use xfrm_local_error for path MTU issues in tunnels Date: Wed, 27 May 2015 10:40:32 -0700 Message-ID: <20150527173823.1415.96248.stgit@ahduyck-vm-fedora22> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-crypto@vger.kernel.org To: steffen.klassert@secunet.com, davem@davemloft.net, herbert@gondor.apana.org.au Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53669 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546AbbE0Rkp (ORCPT ); Wed, 27 May 2015 13:40:45 -0400 Sender: linux-crypto-owner@vger.kernel.org List-ID: 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 --- net/ipv6/xfrm6_output.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c index 09c76a7b474d..6f9b514d0e38 100644 --- a/net/ipv6/xfrm6_output.c +++ b/net/ipv6/xfrm6_output.c @@ -72,6 +72,7 @@ static int xfrm6_tunnel_check_size(struct sk_buff *skb) { int mtu, ret = 0; struct dst_entry *dst = skb_dst(skb); + struct xfrm_state *x = dst->xfrm; mtu = dst_mtu(dst); if (mtu < IPV6_MIN_MTU) @@ -82,7 +83,7 @@ static int xfrm6_tunnel_check_size(struct sk_buff *skb) if (xfrm6_local_dontfrag(skb)) xfrm6_local_rxpmtu(skb, mtu); - else if (skb->sk) + else if (skb->sk && x->props.mode != XFRM_MODE_TUNNEL) xfrm_local_error(skb, mtu); else icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); @@ -149,11 +150,16 @@ static int __xfrm6_output(struct sock *sk, struct sk_buff *skb) else mtu = dst_mtu(skb_dst(skb)); - if (skb->len > mtu && xfrm6_local_dontfrag(skb)) { - xfrm6_local_rxpmtu(skb, mtu); - return -EMSGSIZE; - } else if (!skb->ignore_df && skb->len > mtu && skb->sk) { - xfrm_local_error(skb, mtu); + if (!skb->ignore_df && skb->len > mtu) { + skb->dev = dst->dev; + + if (xfrm6_local_dontfrag(skb)) + xfrm6_local_rxpmtu(skb, mtu); + else if (skb->sk && x->props.mode != XFRM_MODE_TUNNEL) + xfrm_local_error(skb, mtu); + else + icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); + return -EMSGSIZE; }