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| author | Florian Westphal <fw@strlen.de> | 2014-05-02 15:32:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-16 13:42:53 -0700 |
| commit | ed6b7164b4a932f91630da7dadaa1aeb33029d25 (patch) | |
| tree | a5a61187c1be0cbb6bacb413603d2290c0efc7cb | |
| parent | 3f3a34d420f0d08d81379c03cc7d258f2f42dc3f (diff) | |
| download | lwn-ed6b7164b4a932f91630da7dadaa1aeb33029d25.tar.gz lwn-ed6b7164b4a932f91630da7dadaa1aeb33029d25.zip | |
netfilter: ipv4: defrag: set local_df flag on defragmented skb
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>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/netfilter/nf_defrag_ipv4.c | 5 |
1 files 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; } |