linux-kernel - Re: [patch 5/6] posix-cpu-timers: Sanitize thread clock permissions

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: <20190905122108.GO2349@hirez.programming.kicks-ass.net>
Date:   Thu, 5 Sep 2019 14:21:08 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [patch 5/6] posix-cpu-timers: Sanitize thread clock permissions

On Thu, Sep 05, 2019 at 02:03:44PM +0200, Thomas Gleixner wrote:
> The thread clock permissions are restricted to tasks of the same thread
> group, but that also prevents a ptracer from reading them. This is
> inconsistent vs. the process restrictions and unnecessary strict.
> 
> Relax it to ptrace permissions in the same way as process permissions are
> handled.

More of a meta comment on the added permission checking; so where
clock_getcpuclockid() is allowed to return -EPERM, it doesn't because
that's in glibc and it has no clue.

And these patches implement the ptrace checks and result in -EINVAL for
timer_create() and clock_gettime(), even though it should arguably be
-EPERM, but we're not allowed to return that here.