net: Push capable(CAP_NET_ADMIN) into the rtnl methods

- In rtnetlink_rcv_msg convert the capable(CAP_NET_ADMIN) check
  to ns_capable(net->user-ns, CAP_NET_ADMIN).  Allowing unprivileged
  users to make netlink calls to modify their local network
  namespace.

- In the rtnetlink doit methods add capable(CAP_NET_ADMIN) so
  that calls that are not safe for unprivileged users are still
  protected.

Later patches will remove the extra capable calls from methods
that are safe for unprivilged users.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a810f6a..a40c10b 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1547,6 +1547,9 @@
 	struct nlattr *tb[IFLA_MAX+1];
 	char ifname[IFNAMSIZ];
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy);
 	if (err < 0)
 		goto errout;
@@ -1590,6 +1593,9 @@
 	int err;
 	LIST_HEAD(list_kill);
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy);
 	if (err < 0)
 		return err;
@@ -1720,6 +1726,9 @@
 	struct nlattr *linkinfo[IFLA_INFO_MAX+1];
 	int err;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 #ifdef CONFIG_MODULES
 replay:
 #endif
@@ -2057,6 +2066,9 @@
 	u8 *addr;
 	int err;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL);
 	if (err < 0)
 		return err;
@@ -2123,6 +2135,9 @@
 	int err = -EINVAL;
 	__u8 *addr;
 
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (nlmsg_len(nlh) < sizeof(*ndm))
 		return -EINVAL;
 
@@ -2488,7 +2503,7 @@
 	sz_idx = type>>2;
 	kind = type&3;
 
-	if (kind != 2 && !capable(CAP_NET_ADMIN))
+	if (kind != 2 && !ns_capable(net->user_ns, CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {