From ae878ae280bea286ff2b1e1cb6e609dd8cb4501d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Maciej=20=C5=BBenczykowski?= Date: Sun, 3 Oct 2010 14:49:00 -0700 Subject: [PATCH] net: Fix IPv6 PMTU disc. w/ asymmetric routes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Maciej Żenczykowski Signed-off-by: David S. Miller --- net/ipv6/route.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 8323136bdc54..a275c6e1e25c 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1556,14 +1556,13 @@ void rt6_redirect(struct in6_addr *dest, struct in6_addr *src, * i.e. Path MTU discovery */ -void rt6_pmtu_discovery(struct in6_addr *daddr, struct in6_addr *saddr, - struct net_device *dev, u32 pmtu) +static void rt6_do_pmtu_disc(struct in6_addr *daddr, struct in6_addr *saddr, + struct net *net, u32 pmtu, int ifindex) { struct rt6_info *rt, *nrt; - struct net *net = dev_net(dev); int allfrag = 0; - rt = rt6_lookup(net, daddr, saddr, dev->ifindex, 0); + rt = rt6_lookup(net, daddr, saddr, ifindex, 0); if (rt == NULL) return; @@ -1631,6 +1630,27 @@ void rt6_pmtu_discovery(struct in6_addr *daddr, struct in6_addr *saddr, dst_release(&rt->dst); } +void rt6_pmtu_discovery(struct in6_addr *daddr, struct in6_addr *saddr, + struct net_device *dev, u32 pmtu) +{ + struct net *net = dev_net(dev); + + /* + * RFC 1981 states that a node "MUST reduce the size of the packets it + * is sending along the path" that caused the Packet Too Big message. + * Since it's not possible in the general case to determine which + * interface was used to send the original packet, we update the MTU + * on the interface that will be used to send future packets. We also + * update the MTU on the interface that received the Packet Too Big in + * case the original packet was forced out that interface with + * SO_BINDTODEVICE or similar. This is the next best thing to the + * correct behaviour, which would be to update the MTU on all + * interfaces. + */ + rt6_do_pmtu_disc(daddr, saddr, net, pmtu, 0); + rt6_do_pmtu_disc(daddr, saddr, net, pmtu, dev->ifindex); +} + /* * Misc support functions */