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authorBernhard Thaler <bernhard.thaler@wvnet.at>2015-05-30 15:27:40 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2015-06-12 14:08:07 +0200
commit72b31f7271df34c6aab36c01305287924826678f (patch)
tree9fb9ccc3f92d03b3eca9fa600ce508922a768b49 /net/bridge/br_netfilter.c
parent8cae308d2bc81f95c320e7a345b92be6c238f510 (diff)
netfilter: bridge: detect NAT66 correctly and change MAC address
IPv4 iptables allows to REDIRECT/DNAT/SNAT any traffic over a bridge. e.g. REDIRECT $ sysctl -w net.bridge.bridge-nf-call-iptables=1 $ iptables -t nat -A PREROUTING -p tcp -m tcp --dport 8080 \ -j REDIRECT --to-ports 81 This does not work with ip6tables on a bridge in NAT66 scenario because the REDIRECT/DNAT/SNAT is not correctly detected. The bridge pre-routing (finish) netfilter hook has to check for a possible redirect and then fix the destination mac address. This allows to use the ip6tables rules for local REDIRECT/DNAT/SNAT REDIRECT similar to the IPv4 iptables version. e.g. REDIRECT $ sysctl -w net.bridge.bridge-nf-call-ip6tables=1 $ ip6tables -t nat -A PREROUTING -p tcp -m tcp --dport 8080 \ -j REDIRECT --to-ports 81 This patch makes it possible to use IPv6 NAT66 on a bridge. It was tested on a bridge with two interfaces using SNAT/DNAT NAT66 rules. Reported-by: Artie Hamilton <artiemhamilton@yahoo.com> Signed-off-by: Sven Eckelmann <sven@open-mesh.com> [bernhard.thaler@wvnet.at: rebased, add indirect call to ip6_route_input()] [bernhard.thaler@wvnet.at: rebased, split into separate patches] Signed-off-by: Bernhard Thaler <bernhard.thaler@wvnet.at> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/bridge/br_netfilter.c')
-rw-r--r--net/bridge/br_netfilter.c55
1 files changed, 46 insertions, 9 deletions
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 6cb642c43451..9ac0c6417c77 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -326,30 +326,63 @@ free_skb:
static bool daddr_was_changed(const struct sk_buff *skb,
const struct nf_bridge_info *nf_bridge)
{
- return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
+ switch (skb->protocol) {
+ case htons(ETH_P_IP):
+ return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
+ case htons(ETH_P_IPV6):
+ return memcmp(&nf_bridge->ipv6_daddr, &ipv6_hdr(skb)->daddr,
+ sizeof(ipv6_hdr(skb)->daddr)) != 0;
+ default:
+ return false;
+ }
}
-/* PF_BRIDGE/PRE_ROUTING *********************************************/
-/* Undo the changes made for ip6tables PREROUTING and continue the
- * bridge PRE_ROUTING hook.
+/* PF_BRIDGE/PRE_ROUTING: Undo the changes made for ip6tables
+ * PREROUTING and continue the bridge PRE_ROUTING hook. See comment
+ * for br_nf_pre_routing_finish(), same logic is used here but
+ * equivalent IPv6 function ip6_route_input() called indirectly.
*/
static int br_nf_pre_routing_finish_ipv6(struct sock *sk, struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
struct rtable *rt;
+ struct net_device *dev = skb->dev;
+ const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
if (nf_bridge->pkt_otherhost) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->pkt_otherhost = false;
}
nf_bridge->mask &= ~BRNF_NF_BRIDGE_PREROUTING;
+ if (daddr_was_changed(skb, nf_bridge)) {
+ skb_dst_drop(skb);
+ v6ops->route_input(skb);
- rt = bridge_parent_rtable(nf_bridge->physindev);
- if (!rt) {
- kfree_skb(skb);
- return 0;
+ if (skb_dst(skb)->error) {
+ kfree_skb(skb);
+ return 0;
+ }
+
+ if (skb_dst(skb)->dev == dev) {
+ skb->dev = nf_bridge->physindev;
+ nf_bridge_update_protocol(skb);
+ nf_bridge_push_encap_header(skb);
+ NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
+ sk, skb, skb->dev, NULL,
+ br_nf_pre_routing_finish_bridge,
+ 1);
+ return 0;
+ }
+ ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
+ skb->pkt_type = PACKET_HOST;
+ } else {
+ rt = bridge_parent_rtable(nf_bridge->physindev);
+ if (!rt) {
+ kfree_skb(skb);
+ return 0;
+ }
+ skb_dst_set_noref(skb, &rt->dst);
}
- skb_dst_set_noref(skb, &rt->dst);
skb->dev = nf_bridge->physindev;
nf_bridge_update_protocol(skb);
@@ -579,6 +612,7 @@ static unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
+ struct nf_bridge_info *nf_bridge;
const struct ipv6hdr *hdr;
u32 pkt_len;
@@ -610,6 +644,9 @@ static unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops,
if (!setup_pre_routing(skb))
return NF_DROP;
+ nf_bridge = nf_bridge_info_get(skb);
+ nf_bridge->ipv6_daddr = ipv6_hdr(skb)->daddr;
+
skb->protocol = htons(ETH_P_IPV6);
NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->sk, skb,
skb->dev, NULL,

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