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authorFlorian Westphal <fw@strlen.de>2019-11-03 20:54:28 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2019-11-04 20:58:34 +0100
commitb23c0742c2ce7e33ed79d10e451f70fdb5ca85d1 (patch)
treeeeaa498c92df51c2684353329d289d88b3c987db
parent9fedd894b4e1c7ad5e5f711899f6a0a1da01d996 (diff)
bridge: ebtables: don't crash when using dnat target in output chains
xt_in() returns NULL in the output hook, skip the pkt_type change for that case, redirection only makes sense in broute/prerouting hooks. Reported-by: Tom Yan <tom.ty89@gmail.com> Cc: Linus Lüssing <linus.luessing@c0d3.blue> Fixes: cf3cb246e277d ("bridge: ebtables: fix reception of frames DNAT-ed to bridge device/port") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
-rw-r--r--net/bridge/netfilter/ebt_dnat.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/net/bridge/netfilter/ebt_dnat.c b/net/bridge/netfilter/ebt_dnat.c
index ed91ea31978a..12a4f4d93681 100644
--- a/net/bridge/netfilter/ebt_dnat.c
+++ b/net/bridge/netfilter/ebt_dnat.c
@@ -20,7 +20,6 @@ static unsigned int
ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct ebt_nat_info *info = par->targinfo;
- struct net_device *dev;
if (skb_ensure_writable(skb, ETH_ALEN))
return EBT_DROP;
@@ -33,10 +32,22 @@ ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
else
skb->pkt_type = PACKET_MULTICAST;
} else {
- if (xt_hooknum(par) != NF_BR_BROUTING)
- dev = br_port_get_rcu(xt_in(par))->br->dev;
- else
+ const struct net_device *dev;
+
+ switch (xt_hooknum(par)) {
+ case NF_BR_BROUTING:
dev = xt_in(par);
+ break;
+ case NF_BR_PRE_ROUTING:
+ dev = br_port_get_rcu(xt_in(par))->br->dev;
+ break;
+ default:
+ dev = NULL;
+ break;
+ }
+
+ if (!dev) /* NF_BR_LOCAL_OUT */
+ return info->target;
if (ether_addr_equal(info->mac, dev->dev_addr))
skb->pkt_type = PACKET_HOST;