netfilter: xt_TEE: resolve oif using netdevice notifiers
Patrick McHardy [Tue, 20 Apr 2010 13:07:32 +0000 (15:07 +0200)]
Replace the runtime oif name resolving by netdevice notifier based
resolving. When an oif is given, a netdevice notifier is registered
to resolve the name on NETDEV_REGISTER or NETDEV_CHANGE and unresolve
it again on NETDEV_UNREGISTER or NETDEV_CHANGE to a different name.

Signed-off-by: Patrick McHardy <kaber@trash.net>

include/linux/netfilter/xt_TEE.h
net/netfilter/xt_TEE.c

index 55d4a50..5c21d5c 100644 (file)
@@ -4,6 +4,9 @@
 struct xt_tee_tginfo {
        union nf_inet_addr gw;
        char oif[16];
+
+       /* used internally by the kernel */
+       struct xt_tee_priv *priv __attribute__((aligned(8)));
 };
 
 #endif /* _XT_TEE_TARGET_H */
index 842e701..49da6c0 100644 (file)
@@ -15,6 +15,7 @@
 #include <linux/percpu.h>
 #include <linux/route.h>
 #include <linux/skbuff.h>
+#include <linux/notifier.h>
 #include <net/checksum.h>
 #include <net/icmp.h>
 #include <net/ip.h>
 #      define WITH_IPV6 1
 #endif
 
+struct xt_tee_priv {
+       struct notifier_block   notifier;
+       struct xt_tee_tginfo    *tginfo;
+       int                     oif;
+};
+
 static const union nf_inet_addr tee_zero_address;
 static DEFINE_PER_CPU(bool, tee_active);
 
@@ -49,20 +56,6 @@ static struct net *pick_net(struct sk_buff *skb)
        return &init_net;
 }
 
-static bool tee_tg_route_oif(struct flowi *f, struct net *net,
-                            const struct xt_tee_tginfo *info)
-{
-       const struct net_device *dev;
-
-       if (*info->oif != '\0')
-               return true;
-       dev = dev_get_by_name(net, info->oif);
-       if (dev == NULL)
-               return false;
-       f->oif = dev->ifindex;
-       return true;
-}
-
 static bool
 tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
 {
@@ -72,8 +65,11 @@ tee_tg_route4(struct sk_buff *skb, const struct xt_tee_tginfo *info)
        struct flowi fl;
 
        memset(&fl, 0, sizeof(fl));
-       if (!tee_tg_route_oif(&fl, net, info))
-               return false;
+       if (info->priv) {
+               if (info->priv->oif == -1)
+                       return false;
+               fl.oif = info->priv->oif;
+       }
        fl.nl_u.ip4_u.daddr = info->gw.ip;
        fl.nl_u.ip4_u.tos   = RT_TOS(iph->tos);
        fl.nl_u.ip4_u.scope = RT_SCOPE_UNIVERSE;
@@ -149,8 +145,11 @@ tee_tg_route6(struct sk_buff *skb, const struct xt_tee_tginfo *info)
        struct flowi fl;
 
        memset(&fl, 0, sizeof(fl));
-       if (!tee_tg_route_oif(&fl, net, info))
-               return false;
+       if (info->priv) {
+               if (info->priv->oif == -1)
+                       return false;
+               fl.oif = info->priv->oif;
+       }
        fl.nl_u.ip6_u.daddr = info->gw.in6;
        fl.nl_u.ip6_u.flowlabel = ((iph->flow_lbl[0] & 0xF) << 16) |
                                  (iph->flow_lbl[1] << 8) | iph->flow_lbl[2];
@@ -198,15 +197,71 @@ tee_tg6(struct sk_buff *skb, const struct xt_target_param *par)
 }
 #endif /* WITH_IPV6 */
 
+static int tee_netdev_event(struct notifier_block *this, unsigned long event,
+                           void *ptr)
+{
+       struct net_device *dev = ptr;
+       struct xt_tee_priv *priv;
+
+       priv = container_of(this, struct xt_tee_priv, notifier);
+       switch (event) {
+       case NETDEV_REGISTER:
+               if (!strcmp(dev->name, priv->tginfo->oif))
+                       priv->oif = dev->ifindex;
+               break;
+       case NETDEV_UNREGISTER:
+               if (dev->ifindex == priv->oif)
+                       priv->oif = -1;
+               break;
+       case NETDEV_CHANGENAME:
+               if (!strcmp(dev->name, priv->tginfo->oif))
+                       priv->oif = dev->ifindex;
+               else if (dev->ifindex == priv->oif)
+                       priv->oif = -1;
+               break;
+       }
+
+       return NOTIFY_DONE;
+}
+
 static int tee_tg_check(const struct xt_tgchk_param *par)
 {
-       const struct xt_tee_tginfo *info = par->targinfo;
+       struct xt_tee_tginfo *info = par->targinfo;
+       struct xt_tee_priv *priv;
 
-       if (info->oif[sizeof(info->oif)-1] != '\0')
-               return -EINVAL;
        /* 0.0.0.0 and :: not allowed */
-       return (memcmp(&info->gw, &tee_zero_address,
-              sizeof(tee_zero_address)) == 0) ? -EINVAL : 0;
+       if (memcmp(&info->gw, &tee_zero_address,
+                  sizeof(tee_zero_address)) == 0)
+               return -EINVAL;
+
+       if (info->oif[0]) {
+               if (info->oif[sizeof(info->oif)-1] != '\0')
+                       return -EINVAL;
+
+               priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+               if (priv == NULL)
+                       return -ENOMEM;
+
+               priv->tginfo  = info;
+               priv->oif     = -1;
+               priv->notifier.notifier_call = tee_netdev_event;
+               info->priv    = priv;
+
+               register_netdevice_notifier(&priv->notifier);
+       } else
+               info->priv = NULL;
+
+       return 0;
+}
+
+static void tee_tg_destroy(const struct xt_tgdtor_param *par)
+{
+       struct xt_tee_tginfo *info = par->targinfo;
+
+       if (info->priv) {
+               unregister_netdevice_notifier(&info->priv->notifier);
+               kfree(info->priv);
+       }
 }
 
 static struct xt_target tee_tg_reg[] __read_mostly = {
@@ -217,6 +272,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
                .target     = tee_tg4,
                .targetsize = sizeof(struct xt_tee_tginfo),
                .checkentry = tee_tg_check,
+               .destroy    = tee_tg_destroy,
                .me         = THIS_MODULE,
        },
 #ifdef WITH_IPV6
@@ -227,6 +283,7 @@ static struct xt_target tee_tg_reg[] __read_mostly = {
                .target     = tee_tg6,
                .targetsize = sizeof(struct xt_tee_tginfo),
                .checkentry = tee_tg_check,
+               .destroy    = tee_tg_destroy,
                .me         = THIS_MODULE,
        },
 #endif