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bridge: ebtables: fix reception of frames DNAT-ed to bridge device/port

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When trying to redirect bridged frames to the bridge device itself or
a bridge port (brouting) via the dnat target then this currently fails:

The ethernet destination of the frame is dnat'ed to the MAC address of
the bridge device or port just fine. However, the IP code drops it in
the beginning of ip_input.c/ip_rcv() as the dnat target left
the skb->pkt_type as PACKET_OTHERHOST.

Fixing this by resetting skb->pkt_type to an appropriate type after
dnat'ing.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Linus Lüssing 2017-04-19 21:47:33 +02:00 committed by Pablo Neira Ayuso
parent 6bd3d19292
commit cf3cb246e2
1 changed files with 20 additions and 0 deletions
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20
net/bridge/netfilter/ebt_dnat.c
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@ -9,6 +9,7 @@
*/ */
#include <linux/module.h> #include <linux/module.h>
#include <net/sock.h> #include <net/sock.h>
#include "../br_private.h"
#include <linux/netfilter.h> #include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h> #include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h> #include <linux/netfilter_bridge/ebtables.h>
@ -18,11 +19,30 @@ static unsigned int
ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par) ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{ {
const struct ebt_nat_info *info = par->targinfo; const struct ebt_nat_info *info = par->targinfo;
struct net_device *dev;
if (!skb_make_writable(skb, 0)) if (!skb_make_writable(skb, 0))
return EBT_DROP; return EBT_DROP;
ether_addr_copy(eth_hdr(skb)->h_dest, info->mac); ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);
if (is_multicast_ether_addr(info->mac)) {
if (is_broadcast_ether_addr(info->mac))
skb->pkt_type = PACKET_BROADCAST;
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
dev = xt_in(par);
if (ether_addr_equal(info->mac, dev->dev_addr))
skb->pkt_type = PACKET_HOST;
else
skb->pkt_type = PACKET_OTHERHOST;
}
return info->target; return info->target;
} }