netfilter: move reroute indirection to struct nf_ipv6_ops

We cannot make a direct call to nf_ip6_reroute() because that would result
in autoloading the 'ipv6' module because of symbol dependencies.
Therefore, define reroute indirection in nf_ipv6_ops where this really
belongs to.

For IPv4, we can indeed make a direct function call, which is faster,
given IPv4 is built-in in the networking code by default. Still,
CONFIG_INET=n and CONFIG_NETFILTER=y is possible, so define empty inline
stub for IPv4 in such case.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

8 files changed, 39 insertions, 19 deletions

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 02c35eabd348..8358e717eabd 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -311,8 +311,6 @@ struct nf_queue_entry;
 
 struct nf_afinfo {
         unsigned short  family;
-        int             (*reroute)(struct net *net, struct sk_buff *skb,
-                                   const struct nf_queue_entry *entry);
         int             route_key_size;
 };
 
@@ -331,6 +329,7 @@ __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
                             u_int8_t protocol, unsigned short family);
 int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
              bool strict, unsigned short family);
+int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry);
 
 int nf_register_afinfo(const struct nf_afinfo *afinfo);
 void nf_unregister_afinfo(const struct nf_afinfo *afinfo);
diff --git a/include/linux/netfilter_ipv4.h b/include/linux/netfilter_ipv4.h
index 2a4e2c415647..b31dabfdb453 100644
--- a/include/linux/netfilter_ipv4.h
+++ b/include/linux/netfilter_ipv4.h
@@ -18,6 +18,8 @@ struct ip_rt_info {
 
 int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned addr_type);
 
+struct nf_queue_entry;
+
 #ifdef CONFIG_INET
 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
                        unsigned int dataoff, u_int8_t protocol);
@@ -26,6 +28,7 @@ __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
                                u_int8_t protocol);
 int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
                 bool strict);
+int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry);
 #else
 static inline __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
                                      unsigned int dataoff, u_int8_t protocol)
@@ -45,6 +48,11 @@ static inline int nf_ip_route(struct net *net, struct dst_entry **dst,
 {
         return -EOPNOTSUPP;
 }
+static inline int nf_ip_reroute(struct sk_buff *skb,
+                                const struct nf_queue_entry *entry)
+{
+        return -EOPNOTSUPP;
+}
 #endif /* CONFIG_INET */
 
 #endif /*__LINUX_IP_NETFILTER_H*/
diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index e5700bb314a1..288c597e75b3 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -18,6 +18,8 @@ struct ip6_rt_info {
         u_int32_t mark;
 };
 
+struct nf_queue_entry;
+
 /*
  * Hook functions for ipv6 to allow xt_* modules to be built-in even
  * if IPv6 is a module.
@@ -35,6 +37,7 @@ struct nf_ipv6_ops {
                                     u_int8_t protocol);
         int (*route)(struct net *net, struct dst_entry **dst, struct flowi *fl,
                      bool strict);
+        int (*reroute)(struct sk_buff *skb, const struct nf_queue_entry *entry);
 };
 
 #ifdef CONFIG_NETFILTER
diff --git a/net/bridge/netfilter/nf_tables_bridge.c b/net/bridge/netfilter/nf_tables_bridge.c
index 014b6571f2ac..e7348b49bc0d 100644
--- a/net/bridge/netfilter/nf_tables_bridge.c
+++ b/net/bridge/netfilter/nf_tables_bridge.c
@@ -95,15 +95,8 @@ static const struct nf_chain_type filter_bridge = {
         },
 };
 
-static int nf_br_reroute(struct net *net, struct sk_buff *skb,
-                         const struct nf_queue_entry *entry)
-{
-        return 0;
-}
-
 static const struct nf_afinfo nf_br_afinfo = {
         .family                 = AF_BRIDGE,
-        .reroute                = nf_br_reroute,
         .route_key_size         = 0,
 };
 
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index e9d47e4ec182..ec73be3b2f14 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -80,8 +80,7 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_t
 }
 EXPORT_SYMBOL(ip_route_me_harder);
 
-static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
-                         const struct nf_queue_entry *entry)
+int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry)
 {
         const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
 
@@ -92,10 +91,12 @@ static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
                       skb->mark == rt_info->mark &&
                       iph->daddr == rt_info->daddr &&
                       iph->saddr == rt_info->saddr))
-                        return ip_route_me_harder(net, skb, RTN_UNSPEC);
+                        return ip_route_me_harder(entry->state.net, skb,
+                                                  RTN_UNSPEC);
         }
         return 0;
 }
+EXPORT_SYMBOL_GPL(nf_ip_reroute);
 
 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
                             unsigned int dataoff, u_int8_t protocol)
@@ -163,7 +164,6 @@ EXPORT_SYMBOL_GPL(nf_ip_route);
 
 static const struct nf_afinfo nf_ip_afinfo = {
         .family                 = AF_INET,
-        .reroute                = nf_ip_reroute,
         .route_key_size         = sizeof(struct ip_rt_info),
 };
 
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index f03bb043e4e4..d633b78be06f 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -68,7 +68,7 @@ int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(ip6_route_me_harder);
 
-static int nf_ip6_reroute(struct net *net, struct sk_buff *skb,
+static int nf_ip6_reroute(struct sk_buff *skb,
                           const struct nf_queue_entry *entry)
 {
         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
@@ -78,7 +78,7 @@ static int nf_ip6_reroute(struct net *net, struct sk_buff *skb,
                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
                     skb->mark != rt_info->mark)
-                        return ip6_route_me_harder(net, skb);
+                        return ip6_route_me_harder(entry->state.net, skb);
         }
         return 0;
 }
@@ -171,11 +171,11 @@ static const struct nf_ipv6_ops ipv6ops = {
         .checksum               = nf_ip6_checksum,
         .checksum_partial       = nf_ip6_checksum_partial,
         .route                  = nf_ip6_route,
+        .reroute                = nf_ip6_reroute,
 };
 
 static const struct nf_afinfo nf_ip6_afinfo = {
         .family                 = AF_INET6,
-        .reroute                = nf_ip6_reroute,
         .route_key_size         = sizeof(struct ip6_rt_info),
 };
 
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index dfa35bd292c8..15382ff83e7a 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -266,7 +266,6 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
         const struct nf_hook_entry *hook_entry;
         const struct nf_hook_entries *hooks;
         struct sk_buff *skb = entry->skb;
-        const struct nf_afinfo *afinfo;
         const struct net *net;
         unsigned int i;
         int err;
@@ -293,8 +292,7 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
                 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);
 
         if (verdict == NF_ACCEPT) {
-                afinfo = nf_get_afinfo(entry->state.pf);
-                if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0)
+                if (nf_reroute(skb, entry) < 0)
                         verdict = NF_DROP;
         }
 
diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
index 45c22418c955..0b660c568156 100644
--- a/net/netfilter/utils.c
+++ b/net/netfilter/utils.c
@@ -2,6 +2,7 @@
 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv4.h>
 #include <linux/netfilter_ipv6.h>
+#include <net/netfilter/nf_queue.h>
 
 __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
                     unsigned int dataoff, u_int8_t protocol,
@@ -69,3 +70,21 @@ int nf_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
         return ret;
 }
 EXPORT_SYMBOL_GPL(nf_route);
+
+int nf_reroute(struct sk_buff *skb, struct nf_queue_entry *entry)
+{
+        const struct nf_ipv6_ops *v6ops;
+        int ret = 0;
+
+        switch (entry->state.pf) {
+        case AF_INET:
+                ret = nf_ip_reroute(skb, entry);
+                break;
+        case AF_INET6:
+                v6ops = rcu_dereference(nf_ipv6_ops);
+                if (v6ops)
+                        ret = v6ops->reroute(skb, entry);
+                break;
+        }
+        return ret;
+}