[PATCH 6/9] user namespaces: convert all capable checks in kernel/sys.c

[Andrew Morton]

On Thu, 17 Feb 2011 15:03:42 +0000
"Serge E. Hallyn" <serge at hallyn.com> wrote:

> This allows setuid/setgid in containers.  It also fixes some
> corner cases where kernel logic foregoes capability checks when
> uids are equivalent.  The latter will need to be done throughout
> the whole kernel.
> 
>
> ...
>
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -118,17 +118,29 @@ EXPORT_SYMBOL(cad_pid);
>  
>  void (*pm_power_off_prepare)(void);
>  
> +/* called with rcu_read_lock, creds are safe */
> +static inline int set_one_prio_perm(struct task_struct *p)
> +{
> +	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
> +
> +	if (pcred->user->user_ns == cred->user->user_ns &&
> +	    (pcred->uid  == cred->euid ||
> +	     pcred->euid == cred->euid))
> +		return 1;
> +	if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE))
> +		return 1;
> +	return 0;
> +}

uninline.  Document return value?

>
> ...
>