This is a note to let you know that I've just added the patch titled
netfilter: ipv4: defrag: set local_df flag on defragmented skb
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-ipv4-defrag-set-local_df-flag-on-defragmented-skb.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 895162b1101b3ea5db08ca6822ae9672717efec0 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@xxxxxxxxx>
Date: Fri, 2 May 2014 15:32:16 +0200
Subject: netfilter: ipv4: defrag: set local_df flag on defragmented skb
From: Florian Westphal <fw@xxxxxxxxx>
commit 895162b1101b3ea5db08ca6822ae9672717efec0 upstream.
else we may fail to forward skb even if original fragments do fit
outgoing link mtu:
1. remote sends 2k packets in two 1000 byte frags, DF set
2. we want to forward but only see '2k > mtu and DF set'
3. we then send icmp error saying that outgoing link is 1500
But original sender never sent a packet that would not fit
the outgoing link.
Setting local_df makes outgoing path test size vs.
IPCB(skb)->frag_max_size, so we will still send the correct
error in case the largest original size did not fit
outgoing link mtu.
Reported-by: Maxime Bizon <mbizon@xxxxxxxxxx>
Suggested-by: Maxime Bizon <mbizon@xxxxxxxxxx>
Fixes: 5f2d04f1f9 (ipv4: fix path MTU discovery with connection tracking)
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/netfilter/nf_defrag_ipv4.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
@@ -22,7 +22,6 @@
#endif
#include <net/netfilter/nf_conntrack_zones.h>
-/* Returns new sk_buff, or NULL */
static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
{
int err;
@@ -33,8 +32,10 @@ static int nf_ct_ipv4_gather_frags(struc
err = ip_defrag(skb, user);
local_bh_enable();
- if (!err)
+ if (!err) {
ip_send_check(ip_hdr(skb));
+ skb->local_df = 1;
+ }
return err;
}
Patches currently in stable-queue which might be from fw@xxxxxxxxx are
queue-3.4/netfilter-ipv4-defrag-set-local_df-flag-on-defragmented-skb.patch
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