On 02/14/2013 12:56 PM, Glauber Costa wrote:
> Reboot support for pid namespaces is already implemented and it works
> well. However, in most containers the tasks will join all namespaces,
> including the now supported user namespace. In that situation, we will
> fail the "capable" test and won't be able to reboot.
>
> The proposed solution is to allow reboots for CAP_SYS_BOOT processes
> in the user namespace that owns the pid namespace.
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxx>
> kernel/sys.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 265b376..3b0958e 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -435,9 +435,10 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
> {
> char buffer[256];
> int ret = 0;
> + struct pid_namespace *curr_pidns = task_active_pid_ns(current);
>
> /* We only trust the superuser with rebooting the system. */
> - if (!capable(CAP_SYS_BOOT))
> + if (!ns_capable(curr_pidns->user_ns, CAP_SYS_BOOT))
> return -EPERM;
>
> /* For safety, we require "magic" arguments. */
> @@ -453,7 +454,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
> * pid_namespace, the command is handled by reboot_pid_ns() which will
> * call do_exit().
> */
> - ret = reboot_pid_ns(task_active_pid_ns(current), cmd);
> + ret = reboot_pid_ns(curr_pidns, cmd);
> if (ret)
> return ret;
>
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