From 5f2d04f1f9b52604fca6ee08a77972c0df67e082 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sun, 26 Aug 2012 19:13:55 +0200 Subject: ipv4: fix path MTU discovery with connection tracking IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and (in case of forwarded packets) refragments them at POST_ROUTING independent of the IP_DF flag. Refragmentation uses the dst_mtu() of the local route without caring about the original fragment sizes, thereby breaking PMTUD. This patch fixes this by keeping track of the largest received fragment with IP_DF set and generates an ICMP fragmentation required error during refragmentation if that size exceeds the MTU. Signed-off-by: Patrick McHardy Acked-by: Eric Dumazet Acked-by: David S. Miller --- include/net/inet_frag.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/net/inet_frag.h') diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index 2431cf83aec..5098ee7b7e0 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -29,6 +29,8 @@ struct inet_frag_queue { #define INET_FRAG_COMPLETE 4 #define INET_FRAG_FIRST_IN 2 #define INET_FRAG_LAST_IN 1 + + u16 max_size; }; #define INETFRAGS_HASHSZ 64 -- cgit v1.2.3-70-g09d2