net: sctp: fix ASCONF to allow non SCTP_ADDR_SRC addresses in ipv6

Commit 8a07eb0 ("sctp: Add ASCONF operation on the single-homed host")
implemented possible use of IPv4 addresses with non SCTP_ADDR_SRC state
as source address when sending ASCONF (ADD) packets, but IPv6 part for
that was not implemented in 8a07eb0. Therefore, as this is not restricted
to IPv4-only, fix this up to allow the same for IPv6 addresses in SCTP.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Michio Honda <micchie@sfc.wide.ad.jp>
Acked-by: Michio Honda <micchie@sfc.wide.ad.jp>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/ipv6.c

@@ -279,7 +279,9 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 		sctp_v6_to_addr(&dst_saddr, &fl6->saddr, htons(bp->port));
 		rcu_read_lock();
 		list_for_each_entry_rcu(laddr, &bp->address_list, list) {
-			if (!laddr->valid || (laddr->state != SCTP_ADDR_SRC))
+			if (!laddr->valid || laddr->state == SCTP_ADDR_DEL ||
+			    (laddr->state != SCTP_ADDR_SRC &&
+			     !asoc->src_out_of_asoc_ok))
 				continue;
 
 			/* Do not compare against v4 addrs */