af_packet: Teach to listen for multiple unicast addresses.

The the PACKET_ADD_MEMBERSHIP and the PACKET_DROP_MEMBERSHIP setsockopt
calls for af_packet already has all of the infrastructure needed to subscribe
to multiple mac addresses.  All that is missing is a flag to say that
the address we want to listen on is a unicast address.

So introduce PACKET_MR_UNICAST and wire it up to dev_unicast_add and
dev_unicast_delete.

Additionally I noticed that errors from dev_mc_add were not propagated
from packet_dev_mc so fix that.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 2 deletions

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 5b2badeb9497..dea7d6b7cf98 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -145,5 +145,6 @@ struct packet_mreq
 #define PACKET_MR_MULTICAST     0
 #define PACKET_MR_PROMISC       1
 #define PACKET_MR_ALLMULTI      2
+#define PACKET_MR_UNICAST       3
 
 #endif
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 766e6b41f7ca..c7c5d524967e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1570,9 +1570,9 @@ static int packet_dev_mc(struct net_device *dev, struct packet_mclist *i,
         switch (i->type) {
         case PACKET_MR_MULTICAST:
                 if (what > 0)
-                        dev_mc_add(dev, i->addr, i->alen, 0);
+                        return dev_mc_add(dev, i->addr, i->alen, 0);
                 else
-                        dev_mc_delete(dev, i->addr, i->alen, 0);
+                        return dev_mc_delete(dev, i->addr, i->alen, 0);
                 break;
         case PACKET_MR_PROMISC:
                 return dev_set_promiscuity(dev, what);
@@ -1580,6 +1580,12 @@ static int packet_dev_mc(struct net_device *dev, struct packet_mclist *i,
         case PACKET_MR_ALLMULTI:
                 return dev_set_allmulti(dev, what);
                 break;
+        case PACKET_MR_UNICAST:
+                if (what > 0)
+                        return dev_unicast_add(dev, i->addr, i->alen);
+                else
+                        return dev_unicast_delete(dev, i->addr, i->alen);
+                break;
         default:;
         }
         return 0;