linux-kernel - Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can be applied on arbitrary tasks

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Date:   Tue, 4 Sep 2018 16:26:54 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Jiri Kosina <jikos@...nel.org>,
        "Schaufler, Casey" <casey.schaufler@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        Oleg Nesterov <oleg@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can be
 applied on arbitrary tasks

On 09/04/2018 11:48 AM, Jiri Kosina wrote:
> On Tue, 4 Sep 2018, Schaufler, Casey wrote:
> 
>>> So if this should be done in LSM, it'd probably have to be written by
>>> someone else than me :) who actually understands how the "sidechannel LSM"
>>> idea works.
>>
>> Yes. That would be me. 
> 
> Ok, cool. Then 1/2 and 2/3 can be ignored / replaced by Casey's LSM stuff. 
> 
> Some form of 3/3 still should be merged independently on that.


I think STIBP should be an opt in option as it will have significant
impact on performance.  The attack from neighbor thread is pretty
difficult to pull off considering you have to know what the sibling
thread is running and its address allocation.

We could also use a security module to opt in the STIBP policy.

Tim 

> 
> Thanks,
>