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From: Joao Moreira <joao@overdrivepizza.com>
To: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org, Sami Tolvanen <samitolvanen@google.com>,
	linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH] x86/ibt: Implement FineIBT
Date: Tue, 01 Nov 2022 14:50:22 -0700	[thread overview]
Message-ID: <1f6069657f4630c36d60baab2e9b3d10@overdrivepizza.com> (raw)
In-Reply-To: <202211011437.F82B61B8C@keescook>

On 2022-11-01 14:39, Kees Cook wrote:
> On Mon, Oct 31, 2022 at 12:13:50PM -0700, Joao Moreira wrote:
>> On 2022-10-18 22:19, Kees Cook wrote:
>> > On Tue, Oct 18, 2022 at 09:48:42PM -0700, Joao Moreira wrote:
>> > > > > Is it useful to get the compiler to emit 0xcc with
>> > > > > -fpatchable-function-entry under any circumstance? I can probably
>> > > > > change
>> > > > > that quickly if needed/useful.
>> > > >
>> > > > Having it emit 0xcc for the bytes in front of the symbol might be
>> > > > interesting. It would mean a few kernel changes, but nothing too hard.
>> 
>> Should I push for this within clang? I have the patch semi-ready 
>> (below) and
>> would have some cycles this week for polishing it.
> 
> Sure! While the NOP vs CC issue isn't very interesting when IBT is
> available, it's nice for non-IBT to make attackers have to target
> addresses precisely.
> 
> If it's really invasive or hard to maintain in Clang (or objtool),
> then I'd say leave it as-is.

The Clang implementation is actually quite simple and, IIRC, I heard in 
the past someone mentioning that trapping instructions actually provide 
benefits for holding undesired straight-line speculation. Maybe someone 
can comment on that, or even if that is really relevant.

Meanwhile I'll work on pushing it then.

  reply	other threads:[~2022-11-01 21:50 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-18 13:35 [PATCH] x86/ibt: Implement FineIBT Peter Zijlstra
2022-10-18 14:43 ` David Laight
2022-10-18 15:58   ` Joao Moreira
2022-10-18 17:20     ` Kees Cook
2022-10-18 20:09       ` Joao Moreira
2022-10-19  5:33         ` Kees Cook
2022-10-18 21:27     ` David Laight
2022-10-18 14:47 ` Peter Zijlstra
2022-10-18 18:09 ` Kees Cook
2022-10-18 19:56   ` Peter Zijlstra
2022-10-18 23:31     ` Josh Poimboeuf
2022-10-19  5:22       ` Kees Cook
2022-10-19 11:38       ` Peter Zijlstra
2022-10-19  5:14     ` Kees Cook
2022-10-18 19:59   ` Peter Zijlstra
2022-10-18 21:09     ` Peter Zijlstra
2022-10-19  5:05     ` Kees Cook
2022-10-19 12:03       ` Peter Zijlstra
2022-10-19 15:22         ` Sami Tolvanen
2022-10-20 11:04           ` Peter Zijlstra
2022-10-18 19:59   ` Joao Moreira
2022-10-19  5:32     ` Kees Cook
2022-10-19 19:35       ` Joao Moreira
2022-10-18 20:05   ` Peter Zijlstra
2022-10-19  5:00     ` Kees Cook
2022-10-18 20:09   ` Peter Zijlstra
2022-10-18 20:17     ` Joao Moreira
2022-10-18 20:30       ` Peter Zijlstra
2022-10-19  4:48         ` Joao Moreira
2022-10-19  5:19           ` Kees Cook
2022-10-31 19:13             ` Joao Moreira
2022-11-01 21:39               ` Kees Cook
2022-11-01 21:50                 ` Joao Moreira [this message]
2024-05-06 17:36                   ` Kees Cook
2024-05-07  1:45                     ` Joao Moreira
2022-10-19  5:18         ` Kees Cook
2022-10-19  5:16     ` Kees Cook
2022-10-20 11:05   ` Peter Zijlstra
2022-10-18 23:38 ` Josh Poimboeuf
2022-10-19  7:29   ` Peter Zijlstra
2022-10-21 23:08 ` Josh Poimboeuf
2022-10-22 15:03   ` Peter Zijlstra
2022-10-24 17:15     ` Sami Tolvanen
2022-10-24 18:38       ` Joao Moreira

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