From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0AEED811E2; Mon, 26 Aug 2024 20:12:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724703139; cv=none; b=g1Ai43ZDEUx5gAHFBYYMY3btbNmdGcbcGexuJgc3s7FnaMzmQUtUM29aK+IQqyywmWgw4XHN7AbOLN2ol1DXGMzWurK22EoMjjnags1NkcXr3rIOmuFTb0v8jKBikfTTOLWartNz7Rqh19guWMEK/8qVMLESPgRbtwtSVMCBqzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724703139; c=relaxed/simple; bh=rbSh8CmH7ijmLi8lho/8tDPvmVlxo2BscRK2x9bo/Fw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Y0tw8OHKehygAvlMDpzzpSFG4KaOsIc/5Ddm81S9O51q3wbAgUI3HIwnBan4kK2styPbQPCJV9+qL+ya2dp1QEIQ7qsEGWkMbHG2L394ZRP9/56xneDzMdhPoDeNfV7jHaYJGxIydfP/8ntFWn37Z0XoCos5rokLGIb+1U3LDLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j623cd1/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="j623cd1/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CCB9C8B7AA; Mon, 26 Aug 2024 20:12:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724703138; bh=rbSh8CmH7ijmLi8lho/8tDPvmVlxo2BscRK2x9bo/Fw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j623cd1/U+2g5Dgk9F6SU74+/4hy9tkDdQijiKKVQX7xKpQBNo4w8X3i97Zf7AH8F MAKj58+DtCiZHysZnZEx2lzG5YffQiYv0rF4QKSblwO48L9HfCtNUJc0Sdma1dAAsZ uLvB0jqLlFH0/+HMVcyrpNgZRa9N9ECKg7CkzqZDBno2E68wM8nR00nmjey4zEwgN2 CcBz8SBJz7Id8HQwf/u5R/2caJ3aJ0SqTJPohbSxZ1IoFsoTuI1yayYYJUDCdRKiVP Dozcyqa6rOiFOK/+MYs6H5qwnxeg104wP4JMhxlMYxFuHwJi1JXdgVxKKaTGhqbJUW B08nfstphiQaA== Date: Mon, 26 Aug 2024 13:12:18 -0700 From: Kees Cook To: Alice Ryhl Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , Jamie Cunliffe , Sami Tolvanen , Nathan Chancellor , Conor Dooley , Masahiro Yamada , Nicolas Schier , Marc Zyngier , Mark Rutland , Mark Brown , Nick Desaulniers , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Valentin Obst , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v6] rust: support for shadow call stack sanitizer Message-ID: <202408261311.3C191659@keescook> References: <20240826-shadow-call-stack-v6-1-495a7e3eb0ef@google.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240826-shadow-call-stack-v6-1-495a7e3eb0ef@google.com> On Mon, Aug 26, 2024 at 02:22:52PM +0000, Alice Ryhl 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 Thanks for continuing to chase this down. Reviewed-by: Kees Cook -- Kees Cook