| From | Luis Henriques <> | Subject | [PATCH 3.11 21/93] netfilter: ipv4: defrag: set local_df flag on defragmented skb | Date | Mon, 23 Jun 2014 14:02:00 +0100 |
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3.11.10.12 -stable review patch. If anyone has any objections, please let me know.
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From: Florian Westphal <fw@strlen.de>
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@freebox.fr> Suggested-by: Maxime Bizon <mbizon@freebox.fr> Fixes: 5f2d04f1f9 (ipv4: fix path MTU discovery with connection tracking) Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/ipv4/netfilter/nf_defrag_ipv4.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c index 742815518b0f..4cfb3bd1677c 100644 --- 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(struct sk_buff *skb, u_int32_t user) err = ip_defrag(skb, user); local_bh_enable(); - if (!err) + if (!err) { ip_send_check(ip_hdr(skb)); + skb->local_df = 1; + } return err; } -- 1.9.1
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