Commit 739e4505 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

bridge: netfilter: don't call iptables on vlan packets if sysctl is off 



When net.bridge.bridge-nf-filter-vlan-tagged is 0 (default), vlan packets
arriving should not be sent to ip(6)tables by bridge netfilter.

However, it turns out that we currently always send VLAN packets to
netfilter, if ..
a), CONFIG_VLAN_8021Q is enabled ; or
b), CONFIG_VLAN_8021Q is not set but rx vlan offload is enabled
   on the bridge port.

This is because bridge netfilter treats skb with
skb->protocol == ETH_P_IP{V6} as "non-vlan packet".

With rx vlan offload on or CONFIG_VLAN_8021Q=y, the vlan header has
already been removed here, and we cannot rely on skb->protocol alone.

Fix this by only using skb->protocol if the skb has no vlan tag,
or if a vlan tag is present and filter-vlan-tagged bridge netfilter
sysctl is enabled.

We cannot remove the skb->protocol == htons(ETH_P_8021Q) test
because the vlan tag is still around in the CONFIG_VLAN_8021Q=n &&
"ethtool -K $itf rxvlan off" case.

reproducer:
iptables -t raw -I PREROUTING -i br0
iptables -t raw -I PREROUTING -i br0.1

Then send packets to an ip address configured on br0.1 interface.
Even with net.bridge.bridge-nf-filter-vlan-tagged=0, the 1st rule
will match instead of the 2nd one.

With this patch applied, the 2nd rule will match instead.
In the non-local address case, netfilter won't be consulted after
this patch unless the sysctl is switched on.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a157b9d5

net/bridge/br_netfilter.c

+18 −14
Original line number Diff line number Diff line
@@ -62,6 +62,15 @@ static int brnf_filter_pppoe_tagged __read_mostly = 0; 
#define brnf_filter_pppoe_tagged 0

#endif



#define IS_IP(skb) \

	(!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_IP))



#define IS_IPV6(skb) \

	(!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))



#define IS_ARP(skb) \

	(!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))



static inline __be16 vlan_proto(const struct sk_buff *skb)

{

	if (vlan_tx_tag_present(skb))
@@ -639,8 +648,7 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb, 
		return NF_DROP;

	br = p->br;



	if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||

	    IS_PPPOE_IPV6(skb)) {

	if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {

		if (!brnf_call_ip6tables && !br->nf_call_ip6tables)

			return NF_ACCEPT;
@@ -651,8 +659,7 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb, 
	if (!brnf_call_iptables && !br->nf_call_iptables)

		return NF_ACCEPT;



	if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&

	    !IS_PPPOE_IP(skb))

	if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))

		return NF_ACCEPT;



	nf_bridge_pull_encap_header_rcsum(skb);
@@ -701,7 +708,7 @@ static int br_nf_forward_finish(struct sk_buff *skb) 
	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

	struct net_device *in;



	if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {

	if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {

		in = nf_bridge->physindev;

		if (nf_bridge->mask & BRNF_PKT_TYPE) {

			skb->pkt_type = PACKET_OTHERHOST;
@@ -718,6 +725,7 @@ static int br_nf_forward_finish(struct sk_buff *skb) 
	return 0;

}





/* This is the 'purely bridged' case.  For IP, we pass the packet to

 * netfilter with indev and outdev set to the bridge device,

 * but we are still able to filter on the 'real' indev/outdev
@@ -744,11 +752,9 @@ static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb, 
	if (!parent)

		return NF_DROP;



	if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||

	    IS_PPPOE_IP(skb))

	if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))

		pf = PF_INET;

	else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||

		 IS_PPPOE_IPV6(skb))

	else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))

		pf = PF_INET6;

	else

		return NF_ACCEPT;
@@ -795,7 +801,7 @@ static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb, 
	if (!brnf_call_arptables && !br->nf_call_arptables)

		return NF_ACCEPT;



	if (skb->protocol != htons(ETH_P_ARP)) {

	if (!IS_ARP(skb)) {

		if (!IS_VLAN_ARP(skb))

			return NF_ACCEPT;

		nf_bridge_pull_encap_header(skb);
@@ -853,11 +859,9 @@ static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb, 
	if (!realoutdev)

		return NF_DROP;



	if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||

	    IS_PPPOE_IP(skb))

	if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))

		pf = PF_INET;

	else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||

		 IS_PPPOE_IPV6(skb))

	else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))

		pf = PF_INET6;

	else

		return NF_ACCEPT;

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