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Date:   Wed, 24 Jul 2019 01:56:34 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     Kees Cook <keescook@chromium.org>
cc:     Andy Lutomirski <luto@kernel.org>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [5.2 REGRESSION] Generic vDSO breaks seccomp-enabled userspace
 on i386
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On Tue, 23 Jul 2019, Kees Cook wrote:

> On Wed, Jul 24, 2019 at 12:59:03AM +0200, Thomas Gleixner wrote:
> > And as we have sys_clock_gettime64() exposed for 32bit anyway you need to
> > deal with that in seccomp independently of the VDSO. It does not make sense
> > to treat sys_clock_gettime() differently than sys_clock_gettime64(). They
> > both expose the same information, but the latter is y2038 safe.
> 
> Okay, so combining Andy's ideas on aliasing and "more seccomp flags",
> we could declare that clock_gettime64() is not filterable on 32-bit at
> all without the magic SECCOMP_IGNORE_ALIASES flag or something. Then we
> would alias clock_gettime64 to clock_gettime _before_ the first evaluation
> (unless SECCOMP_IGNORE_ALIASES is set)?
> 
> (When was clock_gettime64() introduced? Is it too long ago to do this
> "you can't filter it without a special flag" change?)

clock_gettime64() and the other sys_*time64() syscalls which address the
y2038 issue were added in 5.1

Thanks,

	tglx