linux-kernel - RE: [PATCH v5 1/2] x86/speculation: apply IBPB more strictly to avoid cross-process data leak

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Message-ID: <nycvar.YFH.7.76.1809102111410.15880@cbobk.fhfr.pm>
Date:   Mon, 10 Sep 2018 21:14:11 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     "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>,
        Andi Kleen <ak@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: RE: [PATCH v5 1/2] x86/speculation: apply IBPB more strictly to
 avoid cross-process data leak

On Mon, 10 Sep 2018, Schaufler, Casey wrote:

> Why are you dropping the LSM check here, when in v4 you fixed the
> SELinux audit locking issue? We can avoid introducing an LSM hook
> and all the baggage around it if you can do the security_ptrace_access_check()
> here.

So what guarantees that none of the hooks that 
security_ptrace_access_check() is invoking will not be taking locks (from 
scheduler context in this case)?

Thanks,

-- 
Jiri Kosina
SUSE Labs