From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 2/6] netfilter: ipv4: defrag: set local_df flag on defragmented skb
Date: Fri, 9 May 2014 12:56:03 +0200 [thread overview]
Message-ID: <1399632967-4423-3-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1399632967-4423-1-git-send-email-pablo@netfilter.org>
From: Florian Westphal <fw@strlen.de>
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>
---
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 12e13bd..f40f321 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;
}
--
1.7.10.4
next prev parent reply other threads:[~2014-05-09 10:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 10:56 [PATCH 0/6] Netfilter fixes for net Pablo Neira Ayuso
2014-05-09 10:56 ` [PATCH 1/6] netfilter: ctnetlink: don't add null bindings if no nat requested Pablo Neira Ayuso
2014-05-09 10:56 ` Pablo Neira Ayuso [this message]
2014-05-09 10:56 ` [PATCH 3/6] netfilter: nfnetlink: Fix use after free when it fails to process batch Pablo Neira Ayuso
2014-05-09 10:56 ` [PATCH 4/6] ipv4: fix "conntrack zones" support for defrag user check in ip_expire Pablo Neira Ayuso
2014-05-09 10:56 ` [PATCH 5/6] bridge: superfluous skb->nfct check in br_nf_dev_queue_xmit Pablo Neira Ayuso
2014-05-09 10:56 ` [PATCH 6/6] netfilter: Fix potential use after free in ip6_route_me_harder() Pablo Neira Ayuso
2014-05-09 17:17 ` [PATCH 0/6] Netfilter fixes for net David Miller
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