linux-kernel - Re: [PATCH v6] rust: support for shadow call stack sanitizer

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: <CABCJKucaxfOZki64Yb8vVEuGN+0mH9mh6NvsEKPE-NF5o2KHgQ@mail.gmail.com>
Date: Mon, 26 Aug 2024 14:08:01 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Ard Biesheuvel <ardb@...nel.org>, Jamie Cunliffe <Jamie.Cunliffe@....com>, 
	Nathan Chancellor <nathan@...nel.org>, Conor Dooley <conor@...nel.org>, Kees Cook <kees@...nel.org>, 
	Masahiro Yamada <masahiroy@...nel.org>, Nicolas Schier <nicolas@...sle.eu>, Marc Zyngier <maz@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, Mark Brown <broonie@...nel.org>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Miguel Ojeda <ojeda@...nel.org>, 
	Alex Gaynor <alex.gaynor@...il.com>, Wedson Almeida Filho <wedsonaf@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...sung.com>, 
	Valentin Obst <kernel@...entinobst.de>, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v6] rust: support for shadow call stack sanitizer

Hi Alice,

On Mon, Aug 26, 2024 at 7:23 AM Alice Ryhl <aliceryhl@...gle.com> wrote:
>
> This patch adds all of the flags that are needed to support the shadow
> call stack (SCS) sanitizer with Rust, and updates Kconfig to allow only
> configurations that work.
>
> The -Zfixed-x18 flag is required to use SCS on arm64, and requires rustc
> version 1.80.0 or greater. This restriction is reflected in Kconfig.
>
> When CONFIG_DYNAMIC_SCS is enabled, the build will be configured to
> include unwind tables in the build artifacts. Dynamic SCS uses the
> unwind tables at boot to find all places that need to be patched. The
> -Cforce-unwind-tables=y flag ensures that unwind tables are available
> for Rust code.
>
> In non-dynamic mode, the -Zsanitizer=shadow-call-stack flag is what
> enables the SCS sanitizer. Using this flag requires rustc version 1.82.0
> or greater on the targets used by Rust in the kernel. This restriction
> is reflected in Kconfig.
>
> It is possible to avoid the requirement of rustc 1.80.0 by using
> -Ctarget-feature=+reserve-x18 instead of -Zfixed-x18. However, this flag
> emits a warning during the build, so this patch does not add support for
> using it and instead requires 1.80.0 or greater.
>
> The dependency is placed on `select HAVE_RUST` to avoid a situation
> where enabling Rust silently turns off the sanitizer. Instead, turning
> on the sanitizer results in Rust being disabled. We generally do not
> want changes to CONFIG_RUST to result in any mitigations being changed
> or turned off.
>
> At the time of writing, rustc 1.82.0 only exists via the nightly release
> channel. There is a chance that the -Zsanitizer=shadow-call-stack flag
> will end up needing 1.83.0 instead, but I think it is small.
>
> Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>

Reviewed-by: Sami Tolvanen <samitolvanen@...gle.com>

Sami