Merge branch 'mcast'

Nicolas Dichtel says:

====================
The goal of this serie is to add the support of proxy multicast, ie being able
to build a static multicast tree. In other words, it adds the support of (*,G)
mf[6]c entries.

v2: use INADDR_ANY instead of 0 for IPv4 addresses
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/mroute.h

@@ -9,7 +9,7 @@
 #ifdef CONFIG_IP_MROUTE
 static inline int ip_mroute_opt(int opt)
 {
-	return (opt >= MRT_BASE) && (opt <= MRT_BASE + 10);
+	return (opt >= MRT_BASE) && (opt <= MRT_MAX);
 }
 #else
 static inline int ip_mroute_opt(int opt)

include/linux/mroute6.h

@@ -10,7 +10,7 @@
 #ifdef CONFIG_IPV6_MROUTE
 static inline int ip6_mroute_opt(int opt)
 {
-	return (opt >= MRT6_BASE) && (opt <= MRT6_BASE + 10);
+	return (opt >= MRT6_BASE) && (opt <= MRT6_MAX);
 }
 #else
 static inline int ip6_mroute_opt(int opt)

include/uapi/linux/in6.h

@@ -259,17 +259,10 @@ struct in6_flowlabel_req {
 
 /*
  * Multicast Routing:
- * see include/linux/mroute6.h.
+ * see include/uapi/linux/mroute6.h.
  *
- * MRT6_INIT			200
- * MRT6_DONE			201
- * MRT6_ADD_MIF			202
- * MRT6_DEL_MIF			203
- * MRT6_ADD_MFC			204
- * MRT6_DEL_MFC			205
- * MRT6_VERSION			206
- * MRT6_ASSERT			207
- * MRT6_PIM			208
- * (reserved)			209
+ * MRT6_BASE			200
+ * ...
+ * MRT6_MAX
  */
 #endif /* _UAPI_LINUX_IN6_H */

include/uapi/linux/mroute.h

@@ -26,6 +26,9 @@
 #define MRT_ASSERT	(MRT_BASE+7)	/* Activate PIM assert mode		*/
 #define MRT_PIM		(MRT_BASE+8)	/* enable PIM code			*/
 #define MRT_TABLE	(MRT_BASE+9)	/* Specify mroute table ID		*/
+#define MRT_ADD_MFC_PROXY	(MRT_BASE+10)	/* Add a (*,*|G) mfc entry	*/
+#define MRT_DEL_MFC_PROXY	(MRT_BASE+11)	/* Del a (*,*|G) mfc entry	*/
+#define MRT_MAX		(MRT_BASE+11)
 
 #define SIOCGETVIFCNT	SIOCPROTOPRIVATE	/* IP protocol privates */
 #define SIOCGETSGCNT	(SIOCPROTOPRIVATE+1)

include/uapi/linux/mroute6.h

@@ -26,6 +26,9 @@
 #define MRT6_ASSERT	(MRT6_BASE+7)	/* Activate PIM assert mode		*/
 #define MRT6_PIM	(MRT6_BASE+8)	/* enable PIM code			*/
 #define MRT6_TABLE	(MRT6_BASE+9)	/* Specify mroute table ID		*/
+#define MRT6_ADD_MFC_PROXY	(MRT6_BASE+10)	/* Add a (*,*|G) mfc entry	*/
+#define MRT6_DEL_MFC_PROXY	(MRT6_BASE+11)	/* Del a (*,*|G) mfc entry	*/
+#define MRT6_MAX	(MRT6_BASE+11)
 
 #define SIOCGETMIFCNT_IN6	SIOCPROTOPRIVATE	/* IP protocol privates */
 #define SIOCGETSGCNT_IN6	(SIOCPROTOPRIVATE+1)

net/ipv4/ipmr.c

@@ -828,6 +828,49 @@ static struct mfc_cache *ipmr_cache_find(struct mr_table *mrt,
 	return NULL;
 }
 
+/* Look for a (*,*,oif) entry */
+static struct mfc_cache *ipmr_cache_find_any_parent(struct mr_table *mrt,
+						    int vifi)
+{
+	int line = MFC_HASH(INADDR_ANY, INADDR_ANY);
+	struct mfc_cache *c;
+
+	list_for_each_entry_rcu(c, &mrt->mfc_cache_array[line], list)
+		if (c->mfc_origin == INADDR_ANY &&
+		    c->mfc_mcastgrp == INADDR_ANY &&
+		    c->mfc_un.res.ttls[vifi] < 255)
+			return c;
+
+	return NULL;
+}
+
+/* Look for a (*,G) entry */
+static struct mfc_cache *ipmr_cache_find_any(struct mr_table *mrt,
+					     __be32 mcastgrp, int vifi)
+{
+	int line = MFC_HASH(mcastgrp, INADDR_ANY);
+	struct mfc_cache *c, *proxy;
+
+	if (mcastgrp == INADDR_ANY)
+		goto skip;
+
+	list_for_each_entry_rcu(c, &mrt->mfc_cache_array[line], list)
+		if (c->mfc_origin == INADDR_ANY &&
+		    c->mfc_mcastgrp == mcastgrp) {
+			if (c->mfc_un.res.ttls[vifi] < 255)
+				return c;
+
+			/* It's ok if the vifi is part of the static tree */
+			proxy = ipmr_cache_find_any_parent(mrt,
+							   c->mfc_parent);
+			if (proxy && proxy->mfc_un.res.ttls[vifi] < 255)
+				return c;
+		}
+
+skip:
+	return ipmr_cache_find_any_parent(mrt, vifi);
+}
+
 /*
  *	Allocate a multicast cache entry
  */
@@ -1053,7 +1096,7 @@ ipmr_cache_unresolved(struct mr_table *mrt, vifi_t vifi, struct sk_buff *skb)
  *	MFC cache manipulation by user space mroute daemon
  */
 
-static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
+static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc, int parent)
 {
 	int line;
 	struct mfc_cache *c, *next;
@@ -1062,7 +1105,8 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
 
 	list_for_each_entry_safe(c, next, &mrt->mfc_cache_array[line], list) {
 		if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
-		    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
+		    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr &&
+		    (parent == -1 || parent == c->mfc_parent)) {
 			list_del_rcu(&c->list);
 			mroute_netlink_event(mrt, c, RTM_DELROUTE);
 			ipmr_cache_free(c);
@@ -1073,7 +1117,7 @@ static int ipmr_mfc_delete(struct mr_table *mrt, struct mfcctl *mfc)
 }
 
 static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
-			struct mfcctl *mfc, int mrtsock)
+			struct mfcctl *mfc, int mrtsock, int parent)
 {
 	bool found = false;
 	int line;
@@ -1086,7 +1130,8 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
 
 	list_for_each_entry(c, &mrt->mfc_cache_array[line], list) {
 		if (c->mfc_origin == mfc->mfcc_origin.s_addr &&
-		    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr) {
+		    c->mfc_mcastgrp == mfc->mfcc_mcastgrp.s_addr &&
+		    (parent == -1 || parent == c->mfc_parent)) {
 			found = true;
 			break;
 		}
@@ -1103,7 +1148,8 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
 		return 0;
 	}
 
-	if (!ipv4_is_multicast(mfc->mfcc_mcastgrp.s_addr))
+	if (mfc->mfcc_mcastgrp.s_addr != INADDR_ANY &&
+	    !ipv4_is_multicast(mfc->mfcc_mcastgrp.s_addr))
 		return -EINVAL;
 
 	c = ipmr_cache_alloc();
@@ -1218,7 +1264,7 @@ static void mrtsock_destruct(struct sock *sk)
 
 int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen)
 {
-	int ret;
+	int ret, parent = 0;
 	struct vifctl vif;
 	struct mfcctl mfc;
 	struct net *net = sock_net(sk);
@@ -1287,16 +1333,22 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
 		 */
 	case MRT_ADD_MFC:
 	case MRT_DEL_MFC:
+		parent = -1;
+	case MRT_ADD_MFC_PROXY:
+	case MRT_DEL_MFC_PROXY:
 		if (optlen != sizeof(mfc))
 			return -EINVAL;
 		if (copy_from_user(&mfc, optval, sizeof(mfc)))
 			return -EFAULT;
+		if (parent == 0)
+			parent = mfc.mfcc_parent;
 		rtnl_lock();
-		if (optname == MRT_DEL_MFC)
-			ret = ipmr_mfc_delete(mrt, &mfc);
+		if (optname == MRT_DEL_MFC || optname == MRT_DEL_MFC_PROXY)
+			ret = ipmr_mfc_delete(mrt, &mfc, parent);
 		else
 			ret = ipmr_mfc_add(net, mrt, &mfc,
-					   sk == rtnl_dereference(mrt->mroute_sk));
+					   sk == rtnl_dereference(mrt->mroute_sk),
+					   parent);
 		rtnl_unlock();
 		return ret;
 		/*
@@ -1749,17 +1801,28 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
 {
 	int psend = -1;
 	int vif, ct;
+	int true_vifi = ipmr_find_vif(mrt, skb->dev);
 
 	vif = cache->mfc_parent;
 	cache->mfc_un.res.pkt++;
 	cache->mfc_un.res.bytes += skb->len;
 
+	if (cache->mfc_origin == INADDR_ANY && true_vifi >= 0) {
+		struct mfc_cache *cache_proxy;
+
+		/* For an (*,G) entry, we only check that the incomming
+		 * interface is part of the static tree.
+		 */
+		cache_proxy = ipmr_cache_find_any_parent(mrt, vif);
+		if (cache_proxy &&
+		    cache_proxy->mfc_un.res.ttls[true_vifi] < 255)
+			goto forward;
+	}
+
 	/*
 	 * Wrong interface: drop packet and (maybe) send PIM assert.
 	 */
 	if (mrt->vif_table[vif].dev != skb->dev) {
-		int true_vifi;
-
 		if (rt_is_output_route(skb_rtable(skb))) {
 			/* It is our own packet, looped back.
 			 * Very complicated situation...
@@ -1776,7 +1839,6 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
 		}
 
 		cache->mfc_un.res.wrong_if++;
-		true_vifi = ipmr_find_vif(mrt, skb->dev);
 
 		if (true_vifi >= 0 && mrt->mroute_do_assert &&
 		    /* pimsm uses asserts, when switching from RPT to SPT,
@@ -1794,15 +1856,33 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
 		goto dont_forward;
 	}
 
+forward:
 	mrt->vif_table[vif].pkt_in++;
 	mrt->vif_table[vif].bytes_in += skb->len;
 
 	/*
 	 *	Forward the frame
 	 */
+	if (cache->mfc_origin == INADDR_ANY &&
+	    cache->mfc_mcastgrp == INADDR_ANY) {
+		if (true_vifi >= 0 &&
+		    true_vifi != cache->mfc_parent &&
+		    ip_hdr(skb)->ttl >
+				cache->mfc_un.res.ttls[cache->mfc_parent]) {
+			/* It's an (*,*) entry and the packet is not coming from
+			 * the upstream: forward the packet to the upstream
+			 * only.
+			 */
+			psend = cache->mfc_parent;
+			goto last_forward;
+		}
+		goto dont_forward;
+	}
 	for (ct = cache->mfc_un.res.maxvif - 1;
 	     ct >= cache->mfc_un.res.minvif; ct--) {
-		if (ip_hdr(skb)->ttl > cache->mfc_un.res.ttls[ct]) {
+		/* For (*,G) entry, don't forward to the incoming interface */
+		if ((cache->mfc_origin != INADDR_ANY || ct != true_vifi) &&
+		    ip_hdr(skb)->ttl > cache->mfc_un.res.ttls[ct]) {
 			if (psend != -1) {
 				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 
@@ -1813,6 +1893,7 @@ static int ip_mr_forward(struct net *net, struct mr_table *mrt,
 			psend = ct;
 		}
 	}
+last_forward:
 	if (psend != -1) {
 		if (local) {
 			struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
@@ -1902,6 +1983,13 @@ int ip_mr_input(struct sk_buff *skb)
 
 	/* already under rcu_read_lock() */
 	cache = ipmr_cache_find(mrt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);
+	if (cache == NULL) {
+		int vif = ipmr_find_vif(mrt, skb->dev);
+
+		if (vif >= 0)
+			cache = ipmr_cache_find_any(mrt, ip_hdr(skb)->daddr,
+						    vif);
+	}
 
 	/*
 	 *	No usable cache entry
@@ -2107,7 +2195,12 @@ int ipmr_get_route(struct net *net, struct sk_buff *skb,
 
 	rcu_read_lock();
 	cache = ipmr_cache_find(mrt, saddr, daddr);
+	if (cache == NULL && skb->dev) {
+		int vif = ipmr_find_vif(mrt, skb->dev);
 
+		if (vif >= 0)
+			cache = ipmr_cache_find_any(mrt, daddr, vif);
+	}
 	if (cache == NULL) {
 		struct sk_buff *skb2;
 		struct iphdr *iph;

net/ipv6/ip6mr.c

@@ -1017,6 +1017,50 @@ static struct mfc6_cache *ip6mr_cache_find(struct mr6_table *mrt,
 	return NULL;
 }
 
+/* Look for a (*,*,oif) entry */
+static struct mfc6_cache *ip6mr_cache_find_any_parent(struct mr6_table *mrt,
+						      mifi_t mifi)
+{
+	int line = MFC6_HASH(&in6addr_any, &in6addr_any);
+	struct mfc6_cache *c;
+
+	list_for_each_entry(c, &mrt->mfc6_cache_array[line], list)
+		if (ipv6_addr_any(&c->mf6c_origin) &&
+		    ipv6_addr_any(&c->mf6c_mcastgrp) &&
+		    (c->mfc_un.res.ttls[mifi] < 255))
+			return c;
+
+	return NULL;
+}
+
+/* Look for a (*,G) entry */
+static struct mfc6_cache *ip6mr_cache_find_any(struct mr6_table *mrt,
+					       struct in6_addr *mcastgrp,
+					       mifi_t mifi)
+{
+	int line = MFC6_HASH(mcastgrp, &in6addr_any);
+	struct mfc6_cache *c, *proxy;
+
+	if (ipv6_addr_any(mcastgrp))
+		goto skip;
+
+	list_for_each_entry(c, &mrt->mfc6_cache_array[line], list)
+		if (ipv6_addr_any(&c->mf6c_origin) &&
+		    ipv6_addr_equal(&c->mf6c_mcastgrp, mcastgrp)) {
+			if (c->mfc_un.res.ttls[mifi] < 255)
+				return c;
+
+			/* It's ok if the mifi is part of the static tree */
+			proxy = ip6mr_cache_find_any_parent(mrt,
+							    c->mf6c_parent);
+			if (proxy && proxy->mfc_un.res.ttls[mifi] < 255)
+				return c;
+		}
+
+skip:
+	return ip6mr_cache_find_any_parent(mrt, mifi);
+}
+
 /*
  *	Allocate a multicast cache entry
  */
@@ -1247,7 +1291,8 @@ ip6mr_cache_unresolved(struct mr6_table *mrt, mifi_t mifi, struct sk_buff *skb)
  *	MFC6 cache manipulation by user space
  */
 
-static int ip6mr_mfc_delete(struct mr6_table *mrt, struct mf6cctl *mfc)
+static int ip6mr_mfc_delete(struct mr6_table *mrt, struct mf6cctl *mfc,
+			    int parent)
 {
 	int line;
 	struct mfc6_cache *c, *next;
@@ -1256,7 +1301,9 @@ static int ip6mr_mfc_delete(struct mr6_table *mrt, struct mf6cctl *mfc)
 
 	list_for_each_entry_safe(c, next, &mrt->mfc6_cache_array[line], list) {
 		if (ipv6_addr_equal(&c->mf6c_origin, &mfc->mf6cc_origin.sin6_addr) &&
-		    ipv6_addr_equal(&c->mf6c_mcastgrp, &mfc->mf6cc_mcastgrp.sin6_addr)) {
+		    ipv6_addr_equal(&c->mf6c_mcastgrp,
+				    &mfc->mf6cc_mcastgrp.sin6_addr) &&
+		    (parent == -1 || parent == c->mf6c_parent)) {
 			write_lock_bh(&mrt_lock);
 			list_del(&c->list);
 			write_unlock_bh(&mrt_lock);
@@ -1391,7 +1438,7 @@ void ip6_mr_cleanup(void)
 }
 
 static int ip6mr_mfc_add(struct net *net, struct mr6_table *mrt,
-			 struct mf6cctl *mfc, int mrtsock)
+			 struct mf6cctl *mfc, int mrtsock, int parent)
 {
 	bool found = false;
 	int line;
@@ -1413,7 +1460,9 @@ static int ip6mr_mfc_add(struct net *net, struct mr6_table *mrt,
 
 	list_for_each_entry(c, &mrt->mfc6_cache_array[line], list) {
 		if (ipv6_addr_equal(&c->mf6c_origin, &mfc->mf6cc_origin.sin6_addr) &&
-		    ipv6_addr_equal(&c->mf6c_mcastgrp, &mfc->mf6cc_mcastgrp.sin6_addr)) {
+		    ipv6_addr_equal(&c->mf6c_mcastgrp,
+				    &mfc->mf6cc_mcastgrp.sin6_addr) &&
+		    (parent == -1 || parent == mfc->mf6cc_parent)) {
 			found = true;
 			break;
 		}
@@ -1430,7 +1479,8 @@ static int ip6mr_mfc_add(struct net *net, struct mr6_table *mrt,
 		return 0;
 	}
 
-	if (!ipv6_addr_is_multicast(&mfc->mf6cc_mcastgrp.sin6_addr))
+	if (!ipv6_addr_any(&mfc->mf6cc_mcastgrp.sin6_addr) &&
+	    !ipv6_addr_is_multicast(&mfc->mf6cc_mcastgrp.sin6_addr))
 		return -EINVAL;
 
 	c = ip6mr_cache_alloc();
@@ -1596,7 +1646,7 @@ struct sock *mroute6_socket(struct net *net, struct sk_buff *skb)
 
 int ip6_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsigned int optlen)
 {
-	int ret;
+	int ret, parent = 0;
 	struct mif6ctl vif;
 	struct mf6cctl mfc;
 	mifi_t mifi;
@@ -1653,15 +1703,21 @@ int ip6_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, uns
 	 */
 	case MRT6_ADD_MFC:
 	case MRT6_DEL_MFC:
+		parent = -1;
+	case MRT6_ADD_MFC_PROXY:
+	case MRT6_DEL_MFC_PROXY:
 		if (optlen < sizeof(mfc))
 			return -EINVAL;
 		if (copy_from_user(&mfc, optval, sizeof(mfc)))
 			return -EFAULT;
+		if (parent == 0)
+			parent = mfc.mf6cc_parent;
 		rtnl_lock();
-		if (optname == MRT6_DEL_MFC)
-			ret = ip6mr_mfc_delete(mrt, &mfc);
+		if (optname == MRT6_DEL_MFC || optname == MRT6_DEL_MFC_PROXY)
+			ret = ip6mr_mfc_delete(mrt, &mfc, parent);
 		else
-			ret = ip6mr_mfc_add(net, mrt, &mfc, sk == mrt->mroute6_sk);
+			ret = ip6mr_mfc_add(net, mrt, &mfc,
+					    sk == mrt->mroute6_sk, parent);
 		rtnl_unlock();
 		return ret;
 
@@ -2015,19 +2071,29 @@ static int ip6_mr_forward(struct net *net, struct mr6_table *mrt,
 {
 	int psend = -1;
 	int vif, ct;
+	int true_vifi = ip6mr_find_vif(mrt, skb->dev);
 
 	vif = cache->mf6c_parent;
 	cache->mfc_un.res.pkt++;
 	cache->mfc_un.res.bytes += skb->len;
 
+	if (ipv6_addr_any(&cache->mf6c_origin) && true_vifi >= 0) {
+		struct mfc6_cache *cache_proxy;
+
+		/* For an (*,G) entry, we only check that the incomming
+		 * interface is part of the static tree.
+		 */
+		cache_proxy = ip6mr_cache_find_any_parent(mrt, vif);
+		if (cache_proxy &&
+		    cache_proxy->mfc_un.res.ttls[true_vifi] < 255)
+			goto forward;
+	}
+
 	/*
 	 * Wrong interface: drop packet and (maybe) send PIM assert.
 	 */
 	if (mrt->vif6_table[vif].dev != skb->dev) {
-		int true_vifi;
-
 		cache->mfc_un.res.wrong_if++;
-		true_vifi = ip6mr_find_vif(mrt, skb->dev);
 
 		if (true_vifi >= 0 && mrt->mroute_do_assert &&
 		    /* pimsm uses asserts, when switching from RPT to SPT,
@@ -2045,14 +2111,32 @@ static int ip6_mr_forward(struct net *net, struct mr6_table *mrt,
 		goto dont_forward;
 	}
 
+forward:
 	mrt->vif6_table[vif].pkt_in++;
 	mrt->vif6_table[vif].bytes_in += skb->len;
 
 	/*
 	 *	Forward the frame
 	 */
+	if (ipv6_addr_any(&cache->mf6c_origin) &&
+	    ipv6_addr_any(&cache->mf6c_mcastgrp)) {
+		if (true_vifi >= 0 &&
+		    true_vifi != cache->mf6c_parent &&
+		    ipv6_hdr(skb)->hop_limit >
+				cache->mfc_un.res.ttls[cache->mf6c_parent]) {
+			/* It's an (*,*) entry and the packet is not coming from
+			 * the upstream: forward the packet to the upstream
+			 * only.
+			 */
+			psend = cache->mf6c_parent;
+			goto last_forward;
+		}
+		goto dont_forward;
+	}
 	for (ct = cache->mfc_un.res.maxvif - 1; ct >= cache->mfc_un.res.minvif; ct--) {
-		if (ipv6_hdr(skb)->hop_limit > cache->mfc_un.res.ttls[ct]) {
+		/* For (*,G) entry, don't forward to the incoming interface */
+		if ((!ipv6_addr_any(&cache->mf6c_origin) || ct != true_vifi) &&
+		    ipv6_hdr(skb)->hop_limit > cache->mfc_un.res.ttls[ct]) {
 			if (psend != -1) {
 				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 				if (skb2)
@@ -2061,6 +2145,7 @@ static int ip6_mr_forward(struct net *net, struct mr6_table *mrt,
 			psend = ct;
 		}
 	}
+last_forward:
 	if (psend != -1) {
 		ip6mr_forward2(net, mrt, skb, cache, psend);
 		return 0;
@@ -2096,6 +2181,14 @@ int ip6_mr_input(struct sk_buff *skb)
 	read_lock(&mrt_lock);
 	cache = ip6mr_cache_find(mrt,
 				 &ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr);
+	if (cache == NULL) {
+		int vif = ip6mr_find_vif(mrt, skb->dev);
+
+		if (vif >= 0)
+			cache = ip6mr_cache_find_any(mrt,
+						     &ipv6_hdr(skb)->daddr,
+						     vif);
+	}
 
 	/*
 	 *	No usable cache entry
@@ -2183,6 +2276,13 @@ int ip6mr_get_route(struct net *net,
 
 	read_lock(&mrt_lock);
 	cache = ip6mr_cache_find(mrt, &rt->rt6i_src.addr, &rt->rt6i_dst.addr);
+	if (!cache && skb->dev) {
+		int vif = ip6mr_find_vif(mrt, skb->dev);
+
+		if (vif >= 0)
+			cache = ip6mr_cache_find_any(mrt, &rt->rt6i_dst.addr,
+						     vif);
+	}
 
 	if (!cache) {
 		struct sk_buff *skb2;