[PATCH 2/2] user namespaces: require cap_set{ug}id for CLONE_NEWUSER

["Serge E. Hallyn" <serue@us.ibm.com>]

While ideally CLONE_NEWUSER will eventually require no
privilege, the required permission checks are currently
not there.  As a result, CLONE_NEWUSER has the same effect
as a setuid(0)+setgroups(1,"0").  While we already require
CAP_SYS_ADMIN, requiring CAP_SETUID and CAP_SETGID seems
appropriate.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
 kernel/fork.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 1dd8945..e3a85b3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1344,7 +1344,8 @@ long do_fork(unsigned long clone_flags,
 		/* hopefully this check will go away when userns support is
 		 * complete
 		 */
-		if (!capable(CAP_SYS_ADMIN))
+		if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
+				!capable(CAP_SETGID))
 			return -EPERM;
 	}
 
-- 
1.5.4.3