linux-kernel - Re: Proposal: CAP_PAYLOAD to reduce Meltdown and Spectre mitigation costs

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Message-ID: <dc3d9f6b-248e-a201-004f-43d99bc7ada0@scylladb.com>
Date:   Sun, 7 Jan 2018 11:16:28 +0200
From:   Avi Kivity <avi@...lladb.com>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Proposal: CAP_PAYLOAD to reduce Meltdown and Spectre mitigation
 costs

On 01/06/2018 10:02 PM, Alan Cox wrote:
>> I propose to create a new capability, CAP_PAYLOAD, that allows the
>> system administrator to designate an application as the main workload in
>> that system. Other processes (like sshd or monitoring daemons) exist to
>> support it, and so it makes sense to protect the rest of the system from
>> their being compromised.
> Much more general would be to do this with cgroups both for group-group
> trust and group-kernel trust levels.
>

I think capabilities will work just as well with cgroups. The container 
manager will set CAP_PAYLOAD to payload containers; and if those run an 
init system or a container manager themselves, they'll drop CAP_PAYLOAD 
for all process/sub-containers but their payloads.