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From: <timothee.cocault@orange.com>
To: Florian Westphal <fw@strlen.de>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
	"netfilter-devel@vger.kernel.org"
	<netfilter-devel@vger.kernel.org>
Subject: [PATCH] Fixes dropping of small packets in bridge nat
Date: Wed, 14 Oct 2020 12:36:15 +0000	[thread overview]
Message-ID: <585B71F7B267D04784B84104A88F7DEE0DB503A6@OPEXCAUBM34.corporate.adroot.infra.ftgroup> (raw)

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Fixes an error causing small packets to get dropped. skb_ensure_writable
expects the second parameter to be a length in the ethernet payload. 
If we want to write the ethernet header (src, dst), we should pass 0.
Otherwise, packets with small payloads (< ETH_ALEN) will get dropped.

Signed-off-by: Timothée COCAULT <timothee.cocault@orange.com>
---
 net/bridge/netfilter/ebt_dnat.c     | 2 +-
 net/bridge/netfilter/ebt_redirect.c | 2 +-
 net/bridge/netfilter/ebt_snat.c     | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/bridge/netfilter/ebt_dnat.c
b/net/bridge/netfilter/ebt_dnat.c
index 12a4f4d93681..3fda71a8579d 100644
--- a/net/bridge/netfilter/ebt_dnat.c
+++ b/net/bridge/netfilter/ebt_dnat.c
@@ -21,7 +21,7 @@ ebt_dnat_tg(struct sk_buff *skb, const struct
xt_action_param *par)
 {
 	const struct ebt_nat_info *info = par->targinfo;
 
-	if (skb_ensure_writable(skb, ETH_ALEN))
+	if (skb_ensure_writable(skb, 0))
 		return EBT_DROP;
 
 	ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);
diff --git a/net/bridge/netfilter/ebt_redirect.c
b/net/bridge/netfilter/ebt_redirect.c
index 0cad62a4052b..307790562b49 100644
--- a/net/bridge/netfilter/ebt_redirect.c
+++ b/net/bridge/netfilter/ebt_redirect.c
@@ -21,7 +21,7 @@ ebt_redirect_tg(struct sk_buff *skb, const struct
xt_action_param *par)
 {
 	const struct ebt_redirect_info *info = par->targinfo;
 
-	if (skb_ensure_writable(skb, ETH_ALEN))
+	if (skb_ensure_writable(skb, 0))
 		return EBT_DROP;
 
 	if (xt_hooknum(par) != NF_BR_BROUTING)
diff --git a/net/bridge/netfilter/ebt_snat.c
b/net/bridge/netfilter/ebt_snat.c
index 27443bf229a3..7dfbcdfc30e5 100644
--- a/net/bridge/netfilter/ebt_snat.c
+++ b/net/bridge/netfilter/ebt_snat.c
@@ -22,7 +22,7 @@ ebt_snat_tg(struct sk_buff *skb, const struct
xt_action_param *par)
 {
 	const struct ebt_nat_info *info = par->targinfo;
 
-	if (skb_ensure_writable(skb, ETH_ALEN * 2))
+	if (skb_ensure_writable(skb, 0))
 		return EBT_DROP;
 
 	ether_addr_copy(eth_hdr(skb)->h_source, info->mac);
-- 
2.25.1


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             reply	other threads:[~2020-10-14 12:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14 12:36 timothee.cocault [this message]
2020-10-14 12:47 ` [PATCH] Fixes dropping of small packets in bridge nat Florian Westphal
2020-10-20 15:18 ` Pablo Neira Ayuso

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