sctp: not copying duplicate addrs to the assoc's bind address list

sctp.local_addr_list is a global address list that is supposed to include
all the local addresses. sctp updates this list according to NETDEV_UP/
NETDEV_DOWN notifications.

However, if multiple NICs have the same address, the global list would
have duplicate addresses. Even if for one NIC, promote secondaries in
__inet_del_ifa can also lead to accumulating duplicate addresses.

When sctp binds address 'ANY' and creates a connection, it copies all
the addresses from global list into asoc's bind addr list, which makes
sctp pack the duplicate addresses into INIT/INIT_ACK packets.

This patch is to filter the duplicate addresses when copying the addrs
from global list in sctp_copy_local_addr_list and unpacking addr_param
from cookie in sctp_raw_to_bind_addrs to asoc's bind addr list.

Note that we can't filter the duplicate addrs when global address list
gets updated, As NETDEV_DOWN event may remove an addr that still exists
in another NIC.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/bind_addr.c

@@ -292,6 +292,8 @@ int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw_addr_list,
 		}
 
 		af->from_addr_param(&addr, rawaddr, htons(port), 0);
+		if (sctp_bind_addr_state(bp, &addr) != -1)
+			goto next;
 		retval = sctp_add_bind_addr(bp, &addr, sizeof(addr),
 					    SCTP_ADDR_SRC, gfp);
 		if (retval) {
@@ -300,6 +302,7 @@ int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw_addr_list,
 			break;
 		}
 
+next:
 		len = ntohs(param->length);
 		addrs_len -= len;
 		raw_addr_list += len;

net/sctp/protocol.c

@@ -220,6 +220,9 @@ int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
 		     !(copy_flags & SCTP_ADDR6_PEERSUPP)))
 			continue;
 
+		if (sctp_bind_addr_state(bp, &addr->a) != -1)
+			continue;
+
 		error = sctp_add_bind_addr(bp, &addr->a, sizeof(addr->a),
 					   SCTP_ADDR_SRC, GFP_ATOMIC);
 		if (error)