From: Dan Li <ashimida.1990@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Sami Tolvanen <samitolvanen@google.com>,
Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Qing Zhao <qing.zhao@oracle.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Marco Elver <elver@google.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Song Liu <song@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Uros Bizjak <ubizjak@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Juergen Gross <jgross@suse.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Borislav Petkov <bp@suse.de>,
Masami Hiramatsu <mhiramat@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Aaron Tomlin <atomlin@redhat.com>,
Kalesh Singh <kaleshsingh@google.com>,
Yuntao Wang <ytcoode@gmail.com>,
Changbin Du <changbin.du@intel.com>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [RFC/RFT] CFI: Add support for gcc CFI in aarch64
Date: Sat, 7 Jan 2023 07:42:13 -0800 [thread overview]
Message-ID: <20230107154213.ocyghxd2k66gbvv6@ubuntu> (raw)
In-Reply-To: <202301061929.6881F6CD40@keescook>
Hi Kees,
On 01/06, Kees Cook wrote:
> On Mon, Dec 19, 2022 at 05:32:04AM -0800, Dan Li wrote:
> > Hi Peter,
> Hi!
>
> First of all, thank you thank you for working on this in GCC. This will
> make a big difference for folks that don't have the option to build with
> Clang to gain CFI coverage.
>
> As for the implementation details, the core issue is really that this
> type of CFI is specifically designed for the Linux kernel, and it took a
> rather long time to figure out all the specifics needed (down to the
> byte counts and instruction layouts). GCC's version will ultimately need
> to exactly match the Clang output, or Linux is unlikely to support it.
>
> We're already on our second CFI -- the original Clang CFI was just too
> clunky for long-term use in Linux, so unless we're going to improve on
> the latest Clang KCFI implementation in some way, it's better to stick
> to exactly byte-for-byte identical results. The KCFI support in Linux
> depends on the arm64 and x86_64 runtimes for catching the traps, and the
> post-processing done (on x86_64) with objtool that prepares the kernel
> for IBT use, and converts to the optional FineIBT CFI mechanism. With
> all those moving parts, there needs to be a very compelling reason to
> have GCC KCFI implementation differ from Clang's.
>
> Hopefully that context helps a little. I'm excited to try out future
> versions!
Thanks for the context, it makes sense and helped me a lot. :)
In the next version I'll make the gcc implementation consistent with clang.
Thanks,
Dan.
>
> -Kees
>
> --
> Kees Cook
next prev parent reply other threads:[~2023-01-07 15:42 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-19 6:17 [RFC/RFT] CFI: Add support for gcc CFI in aarch64 Dan Li
2022-12-19 6:38 ` Dan Li
2022-12-19 10:40 ` Peter Zijlstra
2022-12-19 13:32 ` Dan Li
2022-12-19 15:04 ` Peter Zijlstra
2022-12-19 23:38 ` Dan Li
2023-01-03 8:55 ` Mark Rutland
2023-01-07 3:36 ` Kees Cook
2023-01-07 15:42 ` Dan Li [this message]
2023-02-08 19:35 ` Kees Cook
2023-02-10 16:14 ` Dan Li
2023-01-03 8:53 ` Mark Rutland
2023-01-07 15:37 ` Dan Li
2023-03-25 8:54 ` [RFC/RFT,V2] " Dan Li
2023-03-27 9:30 ` Peter Zijlstra
2023-03-27 22:17 ` Sami Tolvanen
2023-04-05 11:49 ` Dan Li
2023-12-13 8:48 ` Dan Li
[not found] ` <4a84af95-6270-6764-6a40-875ec20fc3e1@lixiang.com>
2023-12-13 14:45 ` Mark Rutland
2023-12-13 19:35 ` Kees Cook
2023-04-05 11:48 ` Dan Li
2023-12-13 8:28 ` [RFC/RFT] " Dan Li
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