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: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -474,6 +474,7 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 	struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
 	struct sock *sk = sock->sk;
 	struct inet_sock *inet = inet_sk(sk);
+	struct net *net = sock_net(sk);
 	unsigned short snum;
 	int chk_addr_ret;
 	int err;
@@ -497,7 +498,7 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 			goto out;
 	}
 
-	chk_addr_ret = inet_addr_type(sock_net(sk), addr->sin_addr.s_addr);
+	chk_addr_ret = inet_addr_type(net, addr->sin_addr.s_addr);
 
 	/* Not specified by any standard per-se, however it breaks too
 	 * many applications when removed.  It is unfortunate since
@@ -517,7 +518,8 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 
 	snum = ntohs(addr->sin_port);
 	err = -EACCES;
-	if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
+	if (snum && snum < PROT_SOCK &&
+	    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))
 		goto out;
 
 	/*      We keep a pair of addresses. rcv_saddr is the one

net/ipv6/af_inet6.c

@@ -283,7 +283,7 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 		return -EINVAL;
 
 	snum = ntohs(addr->sin6_port);
-	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;
 
 	lock_sock(sk);

net/sctp/socket.c

@@ -335,6 +335,7 @@ static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
 /* 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 @@ SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
 		}
 	}
 
-	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 @@ static int __sctp_connect(struct sock* sk,
 				 * 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 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 			 * 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;
 			}