54 lines
1.7 KiB
Diff
54 lines
1.7 KiB
Diff
From: Florian Westphal <fw@strlen.de>
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Date: Fri, 2 May 2014 15:32:16 +0200
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Subject: netfilter: ipv4: defrag: set local_df flag on defragmented skb
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Origin: https://git.kernel.org/linus/895162b1101b3ea5db08ca6822ae9672717efec0
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else we may fail to forward skb even if original fragments do fit
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outgoing link mtu:
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1. remote sends 2k packets in two 1000 byte frags, DF set
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2. we want to forward but only see '2k > mtu and DF set'
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3. we then send icmp error saying that outgoing link is 1500
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But original sender never sent a packet that would not fit
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the outgoing link.
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Setting local_df makes outgoing path test size vs.
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IPCB(skb)->frag_max_size, so we will still send the correct
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error in case the largest original size did not fit
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outgoing link mtu.
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Reported-by: Maxime Bizon <mbizon@freebox.fr>
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Suggested-by: Maxime Bizon <mbizon@freebox.fr>
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Fixes: 5f2d04f1f9 (ipv4: fix path MTU discovery with connection tracking)
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Signed-off-by: Florian Westphal <fw@strlen.de>
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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---
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net/ipv4/netfilter/nf_defrag_ipv4.c | 5 +++--
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1 file changed, 3 insertions(+), 2 deletions(-)
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diff --git a/net/ipv4/netfilter/nf_defrag_ipv4.c b/net/ipv4/netfilter/nf_defrag_ipv4.c
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index 12e13bd..f40f321 100644
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--- a/net/ipv4/netfilter/nf_defrag_ipv4.c
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+++ b/net/ipv4/netfilter/nf_defrag_ipv4.c
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@@ -22,7 +22,6 @@
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#endif
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#include <net/netfilter/nf_conntrack_zones.h>
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-/* Returns new sk_buff, or NULL */
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static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
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{
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int err;
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@@ -33,8 +32,10 @@ static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
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err = ip_defrag(skb, user);
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local_bh_enable();
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- if (!err)
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+ if (!err) {
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ip_send_check(ip_hdr(skb));
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+ skb->local_df = 1;
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+ }
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return err;
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}
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