net: Make CAP_NET_BIND_SERVICE per user namespace

Allow privileged users in any user namespace to bind to
privileged sockets in network namespaces they control.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 15379ac..2e89706 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -335,6 +335,7 @@
 /* Bind a local address either to an endpoint or to an association.  */
 SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
 {
+	struct net *net = sock_net(sk);
 	struct sctp_sock *sp = sctp_sk(sk);
 	struct sctp_endpoint *ep = sp->ep;
 	struct sctp_bind_addr *bp = &ep->base.bind_addr;
@@ -378,7 +379,8 @@
 		}
 	}
 
-	if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+	if (snum && snum < PROT_SOCK &&
+	    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))
 		return -EACCES;
 
 	/* See if the address matches any of the addresses we may have
@@ -1161,7 +1163,7 @@
 				 * be permitted to open new associations.
 				 */
 				if (ep->base.bind_addr.port < PROT_SOCK &&
-				    !capable(CAP_NET_BIND_SERVICE)) {
+				    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) {
 					err = -EACCES;
 					goto out_free;
 				}
@@ -1790,7 +1792,7 @@
 			 * associations.
 			 */
 			if (ep->base.bind_addr.port < PROT_SOCK &&
-			    !capable(CAP_NET_BIND_SERVICE)) {
+			    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) {
 				err = -EACCES;
 				goto out_unlock;
 			}