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@xxxxxxxxx>
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
[bernhard.thaler@xxxxxxxx: rebased, add indirect call to ip6_route_input()]
[bernhard.thaler@xxxxxxxx: rebased, split into separate patches]
Signed-off-by: Bernhard Thaler <bernhard.thaler@xxxxxxxx>
---
Patch revision history:
v4
* re-base again to davem's current net-next
* split into several patches
v3
* re-base again to davem's current net-next
* changed subject to include netfilter
v2
* re-base again to davem's current net-next
* add indirect call to ip6_route_input via nf_ipv6_ops to avoid
direct dependency to ipv6.ko just because of function calls
v1
* rebase "bridge: Allow to redirect IPv6 traffic to local machine"
to davem's current net-next
* adjust function order to avoid prototype for br_nf_pre_routing_finish_bridge
(v0)
* problem first mentioned by Artie Hamilton in "BUG: ip6tables IPv6-REDIRECT
over bridges"
* originally there were two similar patches solving this problem
* Patch from Sven Eckelmann was chosen to base solution on
see: bridge: Allow to redirect IPv6 traffic to local machine
see: bridge: Fix NAT66ed IPv6 packets not being bridged correctly
include/linux/netfilter_ipv6.h | 1 +
include/linux/skbuff.h | 6 ++++-
net/bridge/br_netfilter.c | 55 +++++++++++++++++++++++++++++++++-------
net/ipv6/netfilter.c | 1 +
4 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index 64dad1cc..e2d1969 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -25,6 +25,7 @@ void ipv6_netfilter_fini(void);
struct nf_ipv6_ops {
int (*chk_addr)(struct net *net, const struct in6_addr *addr,
const struct net_device *dev, int strict);
+ void (*route_input)(struct sk_buff *skb);
};
extern const struct nf_ipv6_ops __rcu *nf_ipv6_ops;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6b41c15..5b57cee 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -36,6 +36,7 @@
#include <linux/sched.h>
#include <net/flow_dissector.h>
#include <linux/splice.h>
+#include <linux/in6.h>
/* A. Checksumming of received packets by device.
*
@@ -179,7 +180,10 @@ struct nf_bridge_info {
struct net_device *physoutdev;
char neigh_header[8];
};
- __be32 ipv4_daddr;
+ union {
+ __be32 ipv4_daddr;
+ struct in6_addr ipv6_daddr;
+ };
};
#endif
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 6cb642c..9ac0c64 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,
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index d958718..bbca09f 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -191,6 +191,7 @@ static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
static const struct nf_ipv6_ops ipv6ops = {
.chk_addr = ipv6_chk_addr,
+ .route_input = ip6_route_input
};
static const struct nf_afinfo nf_ip6_afinfo = {
--
1.7.10.4
--
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