Re: Proposal: CAP_PAYLOAD to reduce Meltdown and Spectre mitigation costs

[Ozgur <ozgur@goosey.org>]

07.01.2018, 15:29, "Theodore Ts'o" <tytso@mit.edu>:
> On Sun, Jan 07, 2018 at 11:16:28AM +0200, Avi Kivity wrote:
>>  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.
>
> The reason why cgroups are better is Spectre can be used to steal
> information from within the same privilege level --- e.g., you could
> use Javascript to steal a user's Coindesk credentials or Lastpass
> data, which is going to be *way* more lucrative than trying to mine
> cryptocurrency in the sly in a user's browser. :-)

I think the web coin mining pages also work with this method they probably use JS in the background but currently, impossible to do kernel-level operations.
All process start on the browser level and Spectre not read kernel memory, right?

Ozgur

> As a result, you probably want Spectre mitigations to be enabled in a
> root process --- which means capabilities aren't the right answer.
>
> Regards,
>
>                                                 - Ted