netfilter: bridge: query conntrack about skb dnat

ask conntrack instead of storing ipv4 address in nf_bridge_info->data.

Ths avoids the need to use ->data during NF_PRE_ROUTING.
Only two functions that need ->data remain.

These will be addressed in followup patches.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 21 insertions, 6 deletions

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index b260a97275db..261fcd5a42d6 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -37,17 +37,16 @@
 #include <net/route.h>
 #include <net/netfilter/br_netfilter.h>
 
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
 #include <asm/uaccess.h>
 #include "br_private.h"
 #ifdef CONFIG_SYSCTL
 #include <linux/sysctl.h>
 #endif
 
-#define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
-                                 (skb->nf_bridge->data))->daddr.ipv4)
-#define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
-#define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
-
 #ifdef CONFIG_SYSCTL
 static struct ctl_table_header *brnf_sysctl_header;
 static int brnf_call_iptables __read_mostly = 1;
@@ -322,6 +321,22 @@ free_skb:
         return 0;
 }
 
+static bool dnat_took_place(const struct sk_buff *skb)
+{
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+        enum ip_conntrack_info ctinfo;
+        struct nf_conn *ct;
+
+        ct = nf_ct_get(skb, &ctinfo);
+        if (!ct || nf_ct_is_untracked(ct))
+                return false;
+
+        return test_bit(IPS_DST_NAT_BIT, &ct->status);
+#else
+        return false;
+#endif
+}
+
 /* This requires some explaining. If DNAT has taken place,
  * we will need to fix up the destination Ethernet address.
  *
@@ -625,7 +640,7 @@ static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
                 return NF_DROP;
         if (!setup_pre_routing(skb))
                 return NF_DROP;
-        store_orig_dstaddr(skb);
+
         skb->protocol = htons(ETH_P_IP);
 
         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,