netfilter: add inet ingress support

This patch adds the NF_INET_INGRESS pseudohook for the NFPROTO_INET
family. This is a mapping this new hook to the existing NFPROTO_NETDEV
and NF_NETDEV_INGRESS hook. The hook does not guarantee that packets are
inet only, users must filter out non-ip traffic explicitly.

This infrastructure makes it easier to support this new hook in nf_tables.

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

diff --git a/include/uapi/linux/netfilter.h b/include/uapi/linux/netfilter.h
index ca9e63d6e0e4dbdbf47466bf551c51eca6cafc3b..6a6179af0d7ca1406e35024d4cad45b613eadb12 100644 (file)
--- a/include/uapi/linux/netfilter.h
+++ b/include/uapi/linux/netfilter.h
@@ -45,6 +45,7 @@ enum nf_inet_hooks {
        NF_INET_FORWARD,
        NF_INET_LOCAL_OUT,
        NF_INET_POST_ROUTING,
+       NF_INET_INGRESS,
        NF_INET_NUMHOOKS
 };
 

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index c82f779a587e8b8a5bec218955b9360204aeb426..63d032191e6269acff9e48b51b6c0e09a411ceb1 100644 (file)
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -281,6 +281,16 @@ nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
                if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= hooknum))
                        return NULL;
                return net->nf.hooks_bridge + hooknum;
+#endif
+#ifdef CONFIG_NETFILTER_INGRESS
+       case NFPROTO_INET:
+               if (WARN_ON_ONCE(hooknum != NF_INET_INGRESS))
+                       return NULL;
+               if (!dev || dev_net(dev) != net) {
+                       WARN_ON_ONCE(1);
+                       return NULL;
+               }
+               return &dev->nf_hooks_ingress;
 #endif
        case NFPROTO_IPV4:
                if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= hooknum))
@@ -311,22 +321,56 @@ nf_hook_entry_head(struct net *net, int pf, unsigned int hooknum,
        return NULL;
 }
 
+static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
+                           int hooknum)
+{
+#ifndef CONFIG_NETFILTER_INGRESS
+       if (reg->hooknum == hooknum)
+               return -EOPNOTSUPP;
+#endif
+       if (reg->hooknum != hooknum ||
+           !reg->dev || dev_net(reg->dev) != net)
+               return -EINVAL;
+
+       return 0;
+}
+
 static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
 {
-       return pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS;
+       if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
+           (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
+               return true;
+
+       return false;
 }
 
 static void nf_static_key_inc(const struct nf_hook_ops *reg, int pf)
 {
 #ifdef CONFIG_JUMP_LABEL
-       static_key_slow_inc(&nf_hooks_needed[pf][reg->hooknum]);
+       int hooknum;
+
+       if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
+               pf = NFPROTO_NETDEV;
+               hooknum = NF_NETDEV_INGRESS;
+       } else {
+               hooknum = reg->hooknum;
+       }
+       static_key_slow_inc(&nf_hooks_needed[pf][hooknum]);
 #endif
 }
 
 static void nf_static_key_dec(const struct nf_hook_ops *reg, int pf)
 {
 #ifdef CONFIG_JUMP_LABEL
-       static_key_slow_dec(&nf_hooks_needed[pf][reg->hooknum]);
+       int hooknum;
+
+       if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
+               pf = NFPROTO_NETDEV;
+               hooknum = NF_NETDEV_INGRESS;
+       } else {
+               hooknum = reg->hooknum;
+       }
+       static_key_slow_dec(&nf_hooks_needed[pf][hooknum]);
 #endif
 }
 
@@ -335,15 +379,22 @@ static int __nf_register_net_hook(struct net *net, int pf,
 {
        struct nf_hook_entries *p, *new_hooks;
        struct nf_hook_entries __rcu **pp;
+       int err;
 
-       if (pf == NFPROTO_NETDEV) {
-#ifndef CONFIG_NETFILTER_INGRESS
-               if (reg->hooknum == NF_NETDEV_INGRESS)
-                       return -EOPNOTSUPP;
-#endif
-               if (reg->hooknum != NF_NETDEV_INGRESS ||
-                   !reg->dev || dev_net(reg->dev) != net)
-                       return -EINVAL;
+       switch (pf) {
+       case NFPROTO_NETDEV:
+               err = nf_ingress_check(net, reg, NF_NETDEV_INGRESS);
+               if (err < 0)
+                       return err;
+               break;
+       case NFPROTO_INET:
+               if (reg->hooknum != NF_INET_INGRESS)
+                       break;
+
+               err = nf_ingress_check(net, reg, NF_INET_INGRESS);
+               if (err < 0)
+                       return err;
+               break;
        }
 
        pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
@@ -441,8 +492,12 @@ static void __nf_unregister_net_hook(struct net *net, int pf,
 void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
 {
        if (reg->pf == NFPROTO_INET) {
-               __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
-               __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
+               if (reg->hooknum == NF_INET_INGRESS) {
+                       __nf_unregister_net_hook(net, NFPROTO_INET, reg);
+               } else {
+                       __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
+                       __nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
+               }
        } else {
                __nf_unregister_net_hook(net, reg->pf, reg);
        }
@@ -467,14 +522,20 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
        int err;
 
        if (reg->pf == NFPROTO_INET) {
-               err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
-               if (err < 0)
-                       return err;
-
-               err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
-               if (err < 0) {
-                       __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
-                       return err;
+               if (reg->hooknum == NF_INET_INGRESS) {
+                       err = __nf_register_net_hook(net, NFPROTO_INET, reg);
+                       if (err < 0)
+                               return err;
+               } else {
+                       err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
+                       if (err < 0)
+                               return err;
+
+                       err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
+                       if (err < 0) {
+                               __nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
+                               return err;
+                       }
                }
        } else {
                err = __nf_register_net_hook(net, reg->pf, reg);