linux-kernel - Re: [PATCH 1/1] cgroup-v1: Grant CAP_SYS_NICE holders permission to move tasks between cgroups

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Date:   Thu, 17 Jun 2021 13:01:54 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>, cgroups@...r.kernel.org
Subject: Re: [PATCH 1/1] cgroup-v1: Grant CAP_SYS_NICE holders permission to
 move tasks between cgroups

Hi Tejun,

Thanks for your reply.

On Thu, 17 Jun 2021, Tejun Heo wrote:
> On Thu, Jun 17, 2021 at 10:09:41AM +0100, Lee Jones wrote:
> > It should be possible for processes with CAP_SYS_NICE capabilities
> > (privileges) to move lower priority tasks within the same namespace to
> > different cgroups.
> 
> I'm not sure that "should" is justified that easily given that cgroup can
> affect things like device access permissions and basic system organization.

The latter part of that sentence does provide some additional caveats.

> > One extremely common example of this is Android's 'system_server',
> > which moves processes around to different cgroups/cpusets, but should
> > not require any other root privileges.
> 
> Why is this being brought up now after all the years?

This has been discussed before?

I didn't find any evidence of that on the lists.

> Isn't android moving onto cgroup2 anyway?

That I would have to check.

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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