linux-kernel - Re: [5.2 REGRESSION] Generic vDSO breaks seccomp-enabled userspace on i386

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.21.1907240155080.2034@nanos.tec.linutronix.de>
Date:   Wed, 24 Jul 2019 01:56:34 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Kees Cook <keescook@...omium.org>
cc:     Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [5.2 REGRESSION] Generic vDSO breaks seccomp-enabled userspace
 on i386

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