On Wed, 10 August 2011 Daniel Lezcano <daniel.lezcano@xxxxxxx> wrote:
> On 08/10/2011 10:10 PM, Bruno Prémont wrote:
> > Hi Daniel,
> >
> > [I'm adding containers ml as we had a discussion there some time ago
> > for this feature]
>
> [ ... ]
>
> >> + if (cmd == LINUX_REBOOT_CMD_RESTART2)
> >> + if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0)
> >> + return -EFAULT;
> >> +
> >> + /* If we are not in the initial pid namespace, we send a signal
> >> + * to the parent of this init pid namespace, notifying a shutdown
> >> + * occured */
> >> + if (pid_ns != &init_pid_ns)
> >> + pid_namespace_reboot(pid_ns, cmd, buffer);
> > Should there be a return here?
> > Or does pid_namespace_reboot() never return by submitting signal to
> > parent?
>
> Yes, it does not return a value, like 'do_notify_parent_cldstop'
So execution flow continues reaching the whole "host reboot code"?
That's not so good as it then prevents using CAP_SYS_BOOT inside PID namespace
to limit access to rebooting the container from inside as giving a process
inside container CAP_SYS_BOOT would cause host to reboot (and when not given
process inside container would get -EPERM in all cases).
Wouldn't the following be better?:
...
+
+ /* We only trust the superuser with rebooting the system. */
+ if (!capable(CAP_SYS_BOOT))
+ return -EPERM;
+
+ /* If we are not in the initial pid namespace, we send a signal
+ * to the parent of this init pid namespace, notifying a shutdown
+ * occured */
+ if (pid_ns != &init_pid_ns) {
+ pid_namespace_reboot(pid_ns, cmd, buffer);
+ return 0;
+ }
+
mutex_lock(&reboot_mutex);
switch (cmd) {
...
If I misunderstood, please correct me.
Thanks,
Bruno
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