Re: [PATCH] userns: Allow unprivileged reboot

[Serge Hallyn <serge.hallyn@canonical.com>]

Quoting Li Zefan (lizefan@huawei.com):
> In a container with its own pid namespace and user namespace, rebooting
> the system won't reboot the host, but terminate all the processes in
> it and thus have the container shutdown, so it's safe.
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Thanks, Li.

fwiw,
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

-serge

> ---
>  kernel/sys.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 265b376..24d1ef5 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -433,11 +433,12 @@ static DEFINE_MUTEX(reboot_mutex);
>  SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
>  		void __user *, arg)
>  {
> +	struct pid_namespace *pid_ns = task_active_pid_ns(current);
>  	char buffer[256];
>  	int ret = 0;
>  
>  	/* We only trust the superuser with rebooting the system. */
> -	if (!capable(CAP_SYS_BOOT))
> +	if (!ns_capable(pid_ns->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(pid_ns, cmd);
>  	if (ret)
>  		return ret;
>  
> -- 
> 1.8.0.2
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