From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>, Willy Tarreau <w@1wt.eu>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [RFC PATCH v2 2/6] x86/arch_prctl: add ARCH_GET_NOPTI and ARCH_SET_NOPTI to enable/disable PTI
Date: Wed, 10 Jan 2018 08:25:08 +0100 [thread overview]
Message-ID: <20180110072508.rhrhnwktbl7g5oxm@gmail.com> (raw)
In-Reply-To: <20180109212940.ffvqb6wmehmxre4i@pd.tnic>
* Borislav Petkov <bp@alien8.de> wrote:
> On Tue, Jan 09, 2018 at 01:26:57PM -0800, Andy Lutomirski wrote:
> > 2.Turning off PTI is, in general, a terrible idea. It totally breaks
> > any semblance of a security model on a Meltdown-affected CPU. So I
> > think we should require CAP_SYS_RAWIO *and* that the system is booted
> > with pti=allow_optout or something like that.
>
> Uhh, I like that.
>
> Maybe also taint the kernel ...
Tainting the kernel is really a bad idea: a CAP_SYS_RAWIO user _already_ has the
privilege to directly write to the hardware. The binary makes use of that
privilege to allow execution of ring 3 code that has the theoretical ability to
_read_ kernel memory.
Unless we plan on tainting all uses of /dev/mem as well this is totally over the
top.
We could taint the kernel and warn prominently in the syslog when PTI is disabled
globally on the boot line though, if running on affected CPUs.
Something like:
"x86/intel: Page Table Isolation (PTI) is disabled globally. This allows unprivileged, untrusted code to exploit the Meltdown CPU bug to read kernel data."
Thanks,
Ingo
next prev parent reply other threads:[~2018-01-10 7:25 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 12:56 [RFC PATCH v2 0/6] Per process PTI activation Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 1/6] x86/mm: add a pti_disable entry in mm_context_t Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 2/6] x86/arch_prctl: add ARCH_GET_NOPTI and ARCH_SET_NOPTI to enable/disable PTI Willy Tarreau
2018-01-09 14:17 ` Borislav Petkov
2018-01-09 14:36 ` Willy Tarreau
2018-01-09 14:51 ` Borislav Petkov
2018-01-09 14:54 ` Willy Tarreau
2018-01-09 21:26 ` Andy Lutomirski
2018-01-09 21:29 ` Borislav Petkov
2018-01-09 21:32 ` Willy Tarreau
2018-01-09 21:46 ` Borislav Petkov
2018-01-09 22:06 ` Willy Tarreau
2018-01-09 22:20 ` Borislav Petkov
2018-01-09 22:29 ` Dave Hansen
2018-01-09 22:40 ` Willy Tarreau
2018-01-10 14:42 ` Borislav Petkov
2018-01-10 15:39 ` Willy Tarreau
2018-01-10 16:09 ` Borislav Petkov
2018-01-10 16:19 ` Willy Tarreau
2018-01-10 17:28 ` Borislav Petkov
2018-01-10 7:31 ` Ingo Molnar
2018-01-10 7:37 ` Willy Tarreau
2018-01-10 7:59 ` Ingo Molnar
2018-01-09 23:53 ` Andy Lutomirski
2018-01-10 4:25 ` Willy Tarreau
2018-01-10 7:25 ` Ingo Molnar [this message]
2018-01-10 14:45 ` Borislav Petkov
2018-01-10 15:43 ` Willy Tarreau
2018-01-10 15:45 ` Ingo Molnar
2018-01-09 21:34 ` Kees Cook
2018-01-09 21:41 ` Willy Tarreau
2018-01-09 21:50 ` Kees Cook
2018-01-09 22:03 ` Willy Tarreau
2018-01-10 7:13 ` Ingo Molnar
2018-01-12 15:03 ` David Laight
2018-01-12 15:06 ` Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 3/6] x86/pti: add a per-cpu variable pti_disable Willy Tarreau
2018-01-10 7:19 ` Ingo Molnar
2018-01-10 7:29 ` Willy Tarreau
2018-01-10 8:01 ` Ingo Molnar
2018-01-10 8:50 ` Willy Tarreau
2018-01-10 8:59 ` Ingo Molnar
2018-01-10 9:00 ` Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 4/6] x86/pti: don't mark the user PGD with _PAGE_NX Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 5/6] x86/entry/pti: avoid setting CR3 when it's already correct Willy Tarreau
2018-01-10 7:16 ` Ingo Molnar
2018-01-10 7:18 ` Willy Tarreau
2018-01-10 20:29 ` Dave Hansen
2018-01-11 6:46 ` Willy Tarreau
2018-01-09 12:56 ` [RFC PATCH v2 6/6] x86/entry/pti: don't switch PGD on when pti_disable is set Willy Tarreau
2018-01-10 7:15 ` Ingo Molnar
2018-01-10 7:23 ` Willy Tarreau
2018-01-10 8:22 ` Peter Zijlstra
2018-01-10 9:11 ` Willy Tarreau
2018-01-10 19:21 ` Andy Lutomirski
2018-01-10 19:39 ` Willy Tarreau
2018-01-10 19:44 ` Andy Lutomirski
2018-01-10 19:50 ` Linus Torvalds
2018-01-10 20:04 ` Andy Lutomirski
2018-01-11 6:42 ` Willy Tarreau
2018-01-11 15:29 ` Dave Hansen
2018-01-11 15:44 ` Willy Tarreau
2018-01-11 15:51 ` Dave Hansen
2018-01-11 17:02 ` Andy Lutomirski
2018-01-11 18:21 ` Alexei Starovoitov
2018-01-11 18:30 ` Dave Hansen
2018-01-11 18:32 ` Josh Poimboeuf
2018-01-11 18:36 ` Linus Torvalds
2018-01-11 18:38 ` Dave Hansen
2018-01-11 18:51 ` Linus Torvalds
2018-01-11 18:57 ` Dave Hansen
2018-01-11 19:05 ` Josh Poimboeuf
2018-01-11 19:07 ` Borislav Petkov
2018-01-11 19:17 ` Dave Hansen
2018-01-11 19:19 ` Olivier Galibert
2018-01-11 19:26 ` Josh Poimboeuf
2018-01-11 19:34 ` Alan Cox
2018-01-11 21:23 ` Willy Tarreau
2018-01-11 21:28 ` Linus Torvalds
2018-01-11 22:06 ` Willy Tarreau
2018-01-12 16:37 ` David Laight
2018-01-11 19:12 ` Linus Torvalds
2018-01-11 19:38 ` Alexei Starovoitov
2018-01-11 19:11 ` Willy Tarreau
2018-01-11 20:00 ` Dave Hansen
2018-01-11 17:09 ` Andy Lutomirski
2018-01-11 17:40 ` Willy Tarreau
2018-01-11 17:53 ` Andy Lutomirski
2018-01-11 18:05 ` Willy Tarreau
2018-01-11 18:15 ` Dave Hansen
2018-01-11 18:31 ` Linus Torvalds
2018-01-11 18:25 ` Linus Torvalds
2018-01-11 18:26 ` Linus Torvalds
2018-01-11 19:33 ` Andy Lutomirski
2018-01-12 20:22 ` Ingo Molnar
2018-01-12 21:18 ` Andy Lutomirski
2018-01-12 21:54 ` Willy Tarreau
2018-01-11 21:59 ` Willy Tarreau
2018-01-12 16:27 ` David Laight
2018-01-12 17:55 ` Linus Torvalds
2018-01-12 19:36 ` Willy Tarreau
2018-01-11 18:35 ` Dave Hansen
2018-01-11 21:49 ` Willy Tarreau
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