Re: [PATCHv5 01/37] ns: Introduce Time Namespace

Hi Andy,

Thank you for the review,

On 8/1/19 6:29 AM, Andy Lutomirski wrote:

On Mon, Jul 29, 2019 at 2:58 PM Dmitry Safonov [off-list ref] wrote:

quoted

From: Andrei Vagin <redacted>

Time Namespace isolates clock values.

quoted

+static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+       struct time_namespace *ns = to_time_ns(new);
+
+       if (!thread_group_empty(current))
+               return -EINVAL;

You also need to check for other users of the mm.

Oops. It seems like, if the check was

if (!current_is_single_threaded())
    return -EUSERS;

instead of thread_group_empty(current), it would address the concerns
from 23/37 and 25/37 patches, too?

quoted

+
+       if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+           !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+               return -EPERM;
+
+       get_time_ns(ns);
+       get_time_ns(ns);
+       put_time_ns(nsproxy->time_ns);
+       put_time_ns(nsproxy->time_ns_for_children);
+       nsproxy->time_ns = ns;
+       nsproxy->time_ns_for_children = ns;
+       ns->initialized = true;

I really really wish that setns() took an explicit flag for "change
now" or "change for children", since the semantics are different.  Oh
well.

Thanks,
          Dmitry