[RFC PATCH 3/4] allow sethostname in a container

["Serge E. Hallyn" <serge@hallyn.com>]

To test this, you can:
	1. clone a new user namespace without a new uts namespace.
	   You can NOT set hostname.
	2. clone both a new user and uts namespace.  You can set
	   hostname.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
---
 kernel/sys.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 2745dcd..9b9b03b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1171,7 +1171,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
 	int errno;
 	char tmp[__NEW_UTS_LEN];
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 	if (len < 0 || len > __NEW_UTS_LEN)
 		return -EINVAL;
-- 
1.7.2.3