Re: [PATCH v3 2/2] nsfs: Add an ioctl() to return owner UID of a userns

On 17 January 2017 at 14:19, W. Trevor King [off-list ref] wrote:

On Tue, Jan 17, 2017 at 02:03:29PM +1300, Michael Kerrisk (man-pages) wrote:

quoted

+     case NS_GET_OWNER_UID:
+             if (ns->ops->type != CLONE_NEWUSER)
+                     return -EINVAL;
+             user_ns = container_of(ns, struct user_namespace, ns);
+             argp = (unsigned int __user *) arg;
+             uid = from_kuid_munged(current_user_ns(), user_ns->owner);
+             return put_user(uid, argp);
…
+/* Get owner UID for a user namespace */
+#define NS_GET_OWNER_UID     _IO(NSIO, 0x4)

The comment here should probably be:

  Get owner UID (in the current user namespace) for a user namespace

or some such, to convey that current_user_ns is being passed to
from_kuid_munged.

Thanks, Trevor. I'll fix that. From a user-space perspective though
"in the current user namespace" should be "in the caller's user
namespace".

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/