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. The new socket option
MRT_FLUSH_ENTRIES will clear all multicast entries on the sockets table
and the MRT_FLUSH_VIFS will delete all multicast vifs on the socket
table.

Signed-off-by: Callum Sinclair <callum.sincl...@alliedtelesis.co.nz>
---
 include/uapi/linux/mroute.h  |  7 +++-
 include/uapi/linux/mroute6.h |  7 +++-
 net/ipv4/ipmr.c              | 69 ++++++++++++++++++++-------------
 net/ipv6/ip6mr.c             | 74 ++++++++++++++++++++++--------------
 4 files changed, 100 insertions(+), 57 deletions(-)

diff --git a/include/uapi/linux/mroute.h b/include/uapi/linux/mroute.h
index 5d37a9ccce63..673495ca3495 100644
--- a/include/uapi/linux/mroute.h
+++ b/include/uapi/linux/mroute.h
@@ -28,12 +28,17 @@
 #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_FLUSH      (MRT_BASE+12)   /* Flush all multicast entries and vifs 
*/
+#define MRT_MAX                (MRT_BASE+12)
 
 #define SIOCGETVIFCNT  SIOCPROTOPRIVATE        /* IP protocol privates */
 #define SIOCGETSGCNT   (SIOCPROTOPRIVATE+1)
 #define SIOCGETRPF     (SIOCPROTOPRIVATE+2)
 
+/* MRT_FLUSH optional flags */
+#define MRT_FLUSH_ENTRIES      1       /* For flushing all multicast entries */
+#define MRT_FLUSH_VIFS         2       /* For flushing all multicast vifs */
+
 #define MAXVIFS                32
 typedef unsigned long vifbitmap_t;     /* User mode code depends on this lot */
 typedef unsigned short vifi_t;
diff --git a/include/uapi/linux/mroute6.h b/include/uapi/linux/mroute6.h
index 9999cc006390..1f7ac3f0bc20 100644
--- a/include/uapi/linux/mroute6.h
+++ b/include/uapi/linux/mroute6.h
@@ -31,12 +31,17 @@
 #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_FLUSH     (MRT6_BASE+12)  /* Flush all multicast entries and vifs 
*/
+#define MRT6_MAX       (MRT6_BASE+12)
 
 #define SIOCGETMIFCNT_IN6      SIOCPROTOPRIVATE        /* IP protocol privates 
*/
 #define SIOCGETSGCNT_IN6       (SIOCPROTOPRIVATE+1)
 #define SIOCGETRPF     (SIOCPROTOPRIVATE+2)
 
+/* MRT6_FLUSH optional flags */
+#define MRT6_FLUSH_ENTRIES     1       /* For flushing all multicast entries */
+#define MRT6_FLUSH_VIFS                2       /* For flushing all multicast 
vifs */
+
 #define MAXMIFS                32
 typedef unsigned long mifbitmap_t;     /* User mode code depends on this lot */
 typedef unsigned short mifi_t;
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index e536970557dd..dc7a4ee1d7ca 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -110,7 +110,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
 static void mroute_netlink_event(struct mr_table *mrt, struct mfc_cache *mfc,
                                 int cmd);
 static void igmpmsg_netlink_event(struct mr_table *mrt, struct sk_buff *pkt);
-static void mroute_clean_tables(struct mr_table *mrt, bool all);
+static void mroute_clean_tables(struct mr_table *mrt, bool all, int flags);
 static void ipmr_expire_process(struct timer_list *t);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
@@ -415,7 +415,7 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 
id)
 static void ipmr_free_table(struct mr_table *mrt)
 {
        del_timer_sync(&mrt->ipmr_expire_timer);
-       mroute_clean_tables(mrt, true);
+       mroute_clean_tables(mrt, true, MRT_FLUSH_VIFS | MRT_FLUSH_ENTRIES);
        rhltable_destroy(&mrt->mfc_hash);
        kfree(mrt);
 }
@@ -1296,7 +1296,7 @@ static int ipmr_mfc_add(struct net *net, struct mr_table 
*mrt,
 }
 
 /* Close the multicast socket, and clear the vif tables etc */
-static void mroute_clean_tables(struct mr_table *mrt, bool all)
+static void mroute_clean_tables(struct mr_table *mrt, bool all, int flags)
 {
        struct net *net = read_pnet(&mrt->net);
        struct mr_mfc *c, *tmp;
@@ -1305,35 +1305,39 @@ static void mroute_clean_tables(struct mr_table *mrt, 
bool all)
        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);
+       if (flags & MRT_FLUSH_VIFS) {
+               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);
        }
-       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;
-               rhltable_remove(&mrt->mfc_hash, &c->mnode, ipmr_rht_params);
-               list_del_rcu(&c->list);
-               cache = (struct mfc_cache *)c;
-               call_ipmr_mfc_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, cache,
-                                             mrt->id);
-               mroute_netlink_event(mrt, cache, RTM_DELROUTE);
-               mr_cache_put(c);
-       }
-
-       if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
-               spin_lock_bh(&mfc_unres_lock);
-               list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
-                       list_del(&c->list);
+       if (flags & MRT_FLUSH_ENTRIES) {
+               list_for_each_entry_safe(c, tmp, &mrt->mfc_cache_list, list) {
+                       if (!all && (c->mfc_flags & MFC_STATIC))
+                               continue;
+                       rhltable_remove(&mrt->mfc_hash, &c->mnode, 
ipmr_rht_params);
+                       list_del_rcu(&c->list);
                        cache = (struct mfc_cache *)c;
+                       call_ipmr_mfc_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, 
cache,
+                                                                               
  mrt->id);
                        mroute_netlink_event(mrt, cache, RTM_DELROUTE);
-                       ipmr_destroy_unres(mrt, cache);
+                       mr_cache_put(c);
+               }
+
+               if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
+                       spin_lock_bh(&mfc_unres_lock);
+                       list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, 
list) {
+                               list_del(&c->list);
+                               cache = (struct mfc_cache *)c;
+                               mroute_netlink_event(mrt, cache, RTM_DELROUTE);
+                               ipmr_destroy_unres(mrt, cache);
+                       }
+                       spin_unlock_bh(&mfc_unres_lock);
                }
-               spin_unlock_bh(&mfc_unres_lock);
        }
 }
 
@@ -1354,7 +1358,7 @@ static void mrtsock_destruct(struct sock *sk)
                                                    NETCONFA_IFINDEX_ALL,
                                                    net->ipv4.devconf_all);
                        RCU_INIT_POINTER(mrt->mroute_sk, NULL);
-                       mroute_clean_tables(mrt, false);
+                       mroute_clean_tables(mrt, false, MRT_FLUSH_VIFS | 
MRT_FLUSH_ENTRIES);
                }
        }
        rtnl_unlock();
@@ -1479,6 +1483,17 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, 
char __user *optval,
                                           sk == 
rtnl_dereference(mrt->mroute_sk),
                                           parent);
                break;
+       case MRT_FLUSH:
+               if (optlen != sizeof(val)) {
+                       ret = -EINVAL;
+                       break;
+               }
+               if (get_user(val, (int __user *)optval)) {
+                       ret = -EFAULT;
+                       break;
+               }
+               mroute_clean_tables(mrt, true, val);
+               break;
        /* Control PIM assert. */
        case MRT_ASSERT:
                if (optlen != sizeof(val)) {
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index cc01aa3f2b5e..01f015fb33f0 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -97,7 +97,7 @@ static void mr6_netlink_event(struct mr_table *mrt, struct 
mfc6_cache *mfc,
 static void mrt6msg_netlink_event(struct mr_table *mrt, struct sk_buff *pkt);
 static int ip6mr_rtm_dumproute(struct sk_buff *skb,
                               struct netlink_callback *cb);
-static void mroute_clean_tables(struct mr_table *mrt, bool all);
+static void mroute_clean_tables(struct mr_table *mrt, bool all, int flags);
 static void ipmr_expire_process(struct timer_list *t);
 
 #ifdef CONFIG_IPV6_MROUTE_MULTIPLE_TABLES
@@ -393,7 +393,7 @@ static struct mr_table *ip6mr_new_table(struct net *net, 
u32 id)
 static void ip6mr_free_table(struct mr_table *mrt)
 {
        del_timer_sync(&mrt->ipmr_expire_timer);
-       mroute_clean_tables(mrt, true);
+       mroute_clean_tables(mrt, true, MRT6_FLUSH_VIFS | MRT6_FLUSH_ENTRIES);
        rhltable_destroy(&mrt->mfc_hash);
        kfree(mrt);
 }
@@ -1496,42 +1496,46 @@ static int ip6mr_mfc_add(struct net *net, struct 
mr_table *mrt,
  *     Close the multicast socket, and clear the vif tables etc
  */
 
-static void mroute_clean_tables(struct mr_table *mrt, bool all)
+static void mroute_clean_tables(struct mr_table *mrt, bool all, int flags)
 {
        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);
+       if (flags & MRT6_FLUSH_VIFS) {
+               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);
        }
-       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;
-               rhltable_remove(&mrt->mfc_hash, &c->mnode, ip6mr_rht_params);
-               list_del_rcu(&c->list);
-               call_ip6mr_mfc_entry_notifiers(read_pnet(&mrt->net),
-                                              FIB_EVENT_ENTRY_DEL,
-                                              (struct mfc6_cache *)c, mrt->id);
-               mr6_netlink_event(mrt, (struct mfc6_cache *)c, RTM_DELROUTE);
-               mr_cache_put(c);
-       }
+       if (flags & MRT6_FLUSH_ENTRIES) {
+               list_for_each_entry_safe(c, tmp, &mrt->mfc_cache_list, list) {
+                       if (!all && (c->mfc_flags & MFC_STATIC))
+                               continue;
+                       rhltable_remove(&mrt->mfc_hash, &c->mnode, 
ip6mr_rht_params);
+                       list_del_rcu(&c->list);
+                       call_ip6mr_mfc_entry_notifiers(read_pnet(&mrt->net),
+                                                                               
   FIB_EVENT_ENTRY_DEL,
+                                                                               
   (struct mfc6_cache *)c, mrt->id);
+                       mr6_netlink_event(mrt, (struct mfc6_cache *)c, 
RTM_DELROUTE);
+                       mr_cache_put(c);
+               }
 
-       if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
-               spin_lock_bh(&mfc_unres_lock);
-               list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, list) {
-                       list_del(&c->list);
-                       mr6_netlink_event(mrt, (struct mfc6_cache *)c,
-                                         RTM_DELROUTE);
-                       ip6mr_destroy_unres(mrt, (struct mfc6_cache *)c);
+               if (atomic_read(&mrt->cache_resolve_queue_len) != 0) {
+                       spin_lock_bh(&mfc_unres_lock);
+                       list_for_each_entry_safe(c, tmp, &mrt->mfc_unres_queue, 
list) {
+                               list_del(&c->list);
+                               mr6_netlink_event(mrt, (struct mfc6_cache *)c,
+                                                                 RTM_DELROUTE);
+                               ip6mr_destroy_unres(mrt, (struct mfc6_cache 
*)c);
+                       }
+                       spin_unlock_bh(&mfc_unres_lock);
                }
-               spin_unlock_bh(&mfc_unres_lock);
        }
 }
 
@@ -1587,7 +1591,7 @@ int ip6mr_sk_done(struct sock *sk)
                                                     NETCONFA_IFINDEX_ALL,
                                                     net->ipv6.devconf_all);
 
-                       mroute_clean_tables(mrt, false);
+                       mroute_clean_tables(mrt, false, MRT6_FLUSH_VIFS | 
MRT6_FLUSH_ENTRIES);
                        err = 0;
                        break;
                }
@@ -1703,6 +1707,20 @@ int ip6_mroute_setsockopt(struct sock *sk, int optname, 
char __user *optval, uns
                rtnl_unlock();
                return ret;
 
+       case MRT6_FLUSH:
+       {
+               int flags;
+
+               if (optlen != sizeof(flags))
+                       return -EINVAL;
+               if (get_user(flags, (int __user *)optval))
+                       return -EFAULT;
+               rtnl_lock();
+               mroute_clean_tables(mrt, true, flags);
+               rtnl_unlock();
+               return 0;
+       }
+
        /*
         *      Control PIM assert (to activate pim will activate assert)
         */
-- 
2.20.1

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