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/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 4f5f220..24b384b 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -474,6 +474,7 @@
 	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 @@
 			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 @@
 
 	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