[PATCH] ipmr: ip6mr: Create new sockopt to clear mfc cache only

[Callum Sinclair]

Currently the only way to clear the mfc cache was to delete the entries
one by one using the MRT_DEL_MFC socket option or to destroy and
recreate the socket.

Create a new socket option which will clear the multicast forwarding
cache on the socket without destroying the socket.

Signed-off-by: Callum Sinclair <callum.sinclair@xxxxxxxxxxxxxxxxxxx>
---
 include/uapi/linux/mroute.h  |  3 ++-
 include/uapi/linux/mroute6.h |  3 ++-
 net/ipv4/ipmr.c              | 40 +++++++++++++++++++++----------
 net/ipv6/ip6mr.c             | 46 +++++++++++++++++++++++-------------
 4 files changed, 61 insertions(+), 31 deletions(-)

diff --git a/include/uapi/linux/mroute.h b/include/uapi/linux/mroute.h
index 5d37a9ccce63..8a0beb885cd9 100644
--- a/include/uapi/linux/mroute.h
+++ b/include/uapi/linux/mroute.h
@@ -28,7 +28,8 @@
 #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 MRT_DEL_MFC_ALL		(MRT_BASE+12)	/* Del all multicast entries	*/
+#define MRT_MAX		(MRT_BASE+12)
 
 #define SIOCGETVIFCNT	SIOCPROTOPRIVATE	/* IP protocol privates */
 #define SIOCGETSGCNT	(SIOCPROTOPRIVATE+1)
diff --git a/include/uapi/linux/mroute6.h b/include/uapi/linux/mroute6.h
index 9999cc006390..7def70cdf571 100644
--- a/include/uapi/linux/mroute6.h
+++ b/include/uapi/linux/mroute6.h
@@ -31,7 +31,8 @@
 #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 MRT6_DEL_MFC_ALL	(MRT6_BASE+12)	/* Del all multicast entries	*/
+#define MRT6_MAX	(MRT6_BASE+12)
 
 #define SIOCGETMIFCNT_IN6	SIOCPROTOPRIVATE	/* IP protocol privates */
 #define SIOCGETSGCNT_IN6	(SIOCPROTOPRIVATE+1)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index ddbf8c9a1abb..b996d0f70e5c 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1298,22 +1298,12 @@ static int ipmr_mfc_add(struct net *net, struct mr_table *mrt,
 	return 0;
 }
 
-/* Close the multicast socket, and clear the vif tables etc */
-static void mroute_clean_tables(struct mr_table *mrt, bool all)
+/* Clear the vif tables */
+static void mroute_clean_cache(struct mr_table *mrt, bool all)
 {
-	struct net *net = read_pnet(&mrt->net);
 	struct mr_mfc *c, *tmp;
 	struct mfc_cache *cache;
-	LIST_HEAD(list);
-	int i;
-
-	/* Shut down all active vif entries */
-	for (i = 0; i < mrt->maxvif; i++) {
-		if (!all && (mrt->vif_table[i].flags & VIFF_STATIC))
-			continue;
-		vif_delete(mrt, i, 0, &list);
-	}
-	unregister_netdevice_many(&list);
+	struct net *net = read_pnet(&mrt->net);
 
 	/* Wipe the cache */
 	list_for_each_entry_safe(c, tmp, &mrt->mfc_cache_list, list) {
@@ -1340,6 +1330,23 @@ static void mroute_clean_tables(struct mr_table *mrt, bool all)
 	}
 }
 
+/* Close the multicast socket, and clear the vif tables etc */
+static void mroute_clean_tables(struct mr_table *mrt, bool all)
+{
+	LIST_HEAD(list);
+	int i;
+
+	/* Shut down all active vif entries */
+	for (i = 0; i < mrt->maxvif; i++) {
+		if (!all && (mrt->vif_table[i].flags & VIFF_STATIC))
+			continue;
+		vif_delete(mrt, i, 0, &list);
+	}
+	unregister_netdevice_many(&list);
+
+	mroute_clean_cache(mrt, all);
+}
+
 /* called from ip_ra_control(), before an RCU grace period,
  * we dont need to call synchronize_rcu() here
  */
@@ -1482,6 +1489,13 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval,
 					   sk == rtnl_dereference(mrt->mroute_sk),
 					   parent);
 		break;
+	case MRT_DEL_MFC_ALL:
+		rtnl_lock();
+		ipmr_for_each_table(mrt, net) {
+			mroute_clean_cache(mrt, true);
+		}
+		rtnl_unlock();
+		break;
 	/* Control PIM assert. */
 	case MRT_ASSERT:
 		if (optlen != sizeof(val)) {
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 30337b38274b..0168420d217b 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -1492,25 +1492,11 @@ static int ip6mr_mfc_add(struct net *net, struct mr_table *mrt,
 	return 0;
 }
 
-/*
- *	Close the multicast socket, and clear the vif tables etc
- */
-
-static void mroute_clean_tables(struct mr_table *mrt, bool all)
+/* Clear the vif tables */
+static void mroute_clean_cache(struct mr_table *mrt, bool all)
 {
 	struct mr_mfc *c, *tmp;
-	LIST_HEAD(list);
-	int i;
-
-	/* Shut down all active vif entries */
-	for (i = 0; i < mrt->maxvif; i++) {
-		if (!all && (mrt->vif_table[i].flags & VIFF_STATIC))
-			continue;
-		mif6_delete(mrt, i, 0, &list);
-	}
-	unregister_netdevice_many(&list);
 
-	/* Wipe the cache */
 	list_for_each_entry_safe(c, tmp, &mrt->mfc_cache_list, list) {
 		if (!all && (c->mfc_flags & MFC_STATIC))
 			continue;
@@ -1536,6 +1522,27 @@ static void mroute_clean_tables(struct mr_table *mrt, bool all)
 	}
 }
 
+/*
+ *	Close the multicast socket, and clear the vif tables etc
+ */
+
+static void mroute_clean_tables(struct mr_table *mrt, bool all)
+{
+	LIST_HEAD(list);
+	int i;
+
+	/* Shut down all active vif entries */
+	for (i = 0; i < mrt->maxvif; i++) {
+		if (!all && (mrt->vif_table[i].flags & VIFF_STATIC))
+			continue;
+		mif6_delete(mrt, i, 0, &list);
+	}
+	unregister_netdevice_many(&list);
+
+	/* Wipe the cache */
+	mroute_clean_cache(mrt, all);
+}
+
 static int ip6mr_sk_init(struct mr_table *mrt, struct sock *sk)
 {
 	int err = 0;
@@ -1703,6 +1710,13 @@ int ip6_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, uns
 					    parent);
 		rtnl_unlock();
 		return ret;
+	case MRT6_DEL_MFC_ALL:
+		rtnl_lock();
+		ip6mr_for_each_table(mrt, net) {
+			mroute_clean_cache(mrt, true);
+		}
+		rtnl_unlock();
+		return 0;
 
 	/*
 	 *	Control PIM assert (to activate pim will activate assert)
-- 
2.20.1