Re: [RFC PATCH v3 00/20] KCFI support

From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <keescook@chromium.org>
Cc: Sami Tolvanen <samitolvanen@google.com>,
	linux-kernel@vger.kernel.org,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [RFC PATCH v3 00/20] KCFI support
Date: Mon, 18 Jul 2022 23:46:24 +0200	[thread overview]
Message-ID: <YtXUsIjT9IDGKUCv@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <202206131001.6BA9933C@keescook>

On Mon, Jun 13, 2022 at 10:04:12AM -0700, Kees Cook wrote:
> On Fri, Jun 10, 2022 at 04:34:53PM -0700, Sami Tolvanen wrote:
> > KCFI is a proposed forward-edge control-flow integrity scheme for
> > Clang, which is more suitable for kernel use than the existing CFI
> > scheme used by CONFIG_CFI_CLANG. KCFI doesn't require LTO, doesn't
> > alter function references to point to a jump table, and won't break
> > function address equality. The latest LLVM patch is here:
> > 
> >   https://reviews.llvm.org/D119296
> > 
> > This RFC series replaces the current arm64 CFI implementation with
> > KCFI and adds support for x86_64.
> 
> I think the "RFC" prefix for this series can be dropped. :)
> 
> It looks to me like all of Peter's concerns have been addressed. I'd say
> let's get the Clang side landed, and once that's done, land this via x86
> -tip?
> 
> Peter and Will does this sound right to you? It touches arm64, so if
> -tip isn't okay, I could take it in one of my trees?

Sorry, I was a bit pre-occupied with this retbleed crud, I'll try and
have a look at things shortly.