Re: [PATCH v4 4/4] sched/core: Add permission checks for setting the latency_nice value

[chris hyser <chris.hyser@oracle.com>]

On 2/24/20 3:59 AM, Parth Shah wrote:
> Since the latency_nice uses the similar infrastructure as NICE, use the
> already existing CAP_SYS_NICE security checks for the latency_nice. This
> should return -EPERM for the non-root user when trying to set the task
> latency_nice value to any lower than the current value.
> 
> Signed-off-by: Parth Shah <parth@linux.ibm.com>

Reviewed-by: Chris Hyser <chris.hyser@oracle.com>

> ---
>   kernel/sched/core.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index e1dc536d4ca3..f883e1d3cd10 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4887,6 +4887,10 @@ static int __sched_setscheduler(struct task_struct *p,
>   			return -EINVAL;
>   		if (attr->sched_latency_nice < MIN_LATENCY_NICE)
>   			return -EINVAL;
> +		/* Use the same security checks as NICE */
> +		if (attr->sched_latency_nice < p->latency_nice &&
> +		    !can_nice(p, attr->sched_latency_nice))
> +			return -EPERM;
>   	}
>   
>   	if (pi)
>