linux-kernel - Re: [PATCH v5] 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: <CAH5fLgh6ywHeFSwbnaOu-QYrt_Jytv_y3zb1QbJzK-w4kQ617w@mail.gmail.com>
Date: Fri, 23 Aug 2024 14:38:20 +0200
From: Alice Ryhl <aliceryhl@...gle.com>
To: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>, Jamie Cunliffe <Jamie.Cunliffe@....com>, 
	Sami Tolvanen <samitolvanen@...gle.com>, Nathan Chancellor <nathan@...nel.org>, 
	Conor Dooley <conor@...nel.org>, Masahiro Yamada <masahiroy@...nel.org>, 
	Nicolas Schier <nicolas@...sle.eu>, Ard Biesheuvel <ardb@...nel.org>, 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, Kees Cook <kees@...nel.org>
Subject: Re: [PATCH v5] rust: support for shadow call stack sanitizer

On Fri, Aug 23, 2024 at 2:24 PM Will Deacon <will@...nel.org> wrote:
>
> On Tue, Aug 20, 2024 at 05:13:58PM +0200, Alice Ryhl wrote:
> > On Tue, Aug 20, 2024 at 4:35 PM Will Deacon <will@...nel.org> wrote:
> > > On Tue, Aug 06, 2024 at 10:01:44AM +0000, Alice Ryhl wrote:
> > > > diff --git a/init/Kconfig b/init/Kconfig
> > > > index fe76c5d0a72e..d857f6f90885 100644
> > > > --- a/init/Kconfig
> > > > +++ b/init/Kconfig
> > > > @@ -1909,7 +1909,7 @@ config RUST
> > > >       depends on !MODVERSIONS
> > > >       depends on !GCC_PLUGINS
> > > >       depends on !RANDSTRUCT
> > > > -     depends on !SHADOW_CALL_STACK
> > > > +     depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SCS
> > >
> > > Sorry, I didn't spot this in v4, but since UNWIND_PATCH_PAC_INTO_SCS is
> > > specific to arm64 and the only other architecture selecting
> > > ARCH_SUPPORTS_SHADOW_CALL_STACK is riscv, I can't help but feel it would
> > > be cleaner to move this logic into the arch code selecting HAVE_RUST.
> > >
> > > That is, it's up to the architecture to make sure that it has whatever
> > > it needs for SCS to work with Rust if it claims to support Rust.
> > >
> > > What do you think?
> >
> > The `select RUST if ...` is going to get really complicated if we
> > apply that rule in general. Having options here allows us to split
> > them across several `depends on` clauses. I'm not sure it will even
> > work, I had issues with cyclic Kconfig errors previously. I also don't
> > think it's unreasonable for the architecture to say it supports both
> > options when it really does support both; they are just mutually
> > exclusive. I also think there is value in having all of the options
> > that Rust doesn't work with in one place.
>
> I'm not sure I follow why this will get really complicated. Isn't it as
> straightforward as the diff below, or did I miss something?

Hmm. I tried this but I wasn't able to enable Rust with this setup.
Even though the deps of RUSTC_SUPPORTS_ARM64 are ok, it doesn't seem
to be enabled and I can't find it in menuconfig. I think we need to
have a `select RUSTC_SUPPORTS_ARM64` somewhere.

Alice

> --->8
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index a2f8ff354ca6..2f5702cb9dac 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -231,7 +231,7 @@ config ARM64
>         select HAVE_FUNCTION_ARG_ACCESS_API
>         select MMU_GATHER_RCU_TABLE_FREE
>         select HAVE_RSEQ
> -       select HAVE_RUST if CPU_LITTLE_ENDIAN
> +       select HAVE_RUST if RUSTC_SUPPORTS_ARM64
>         select HAVE_STACKPROTECTOR
>         select HAVE_SYSCALL_TRACEPOINTS
>         select HAVE_KPROBES
> @@ -265,6 +265,11 @@ config ARM64
>         help
>           ARM 64-bit (AArch64) Linux support.
>
> +config RUSTC_SUPPORTS_ARM64
> +       bool
> +       depends on CPU_LITTLE_ENDIAN
> +       depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SC
> +
>  config CLANG_SUPPORTS_DYNAMIC_FTRACE_WITH_ARGS
>         def_bool CC_IS_CLANG
>         # https://github.com/ClangBuiltLinux/linux/issues/1507
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 0f3cd7c3a436..93858dbfefc0 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -172,7 +172,7 @@ config RISCV
>         select HAVE_REGS_AND_STACK_ACCESS_API
>         select HAVE_RETHOOK if !XIP_KERNEL
>         select HAVE_RSEQ
> -       select HAVE_RUST if 64BIT
> +       select HAVE_RUST if 64BIT && !SHADOW_CALL_STACK
>         select HAVE_SAMPLE_FTRACE_DIRECT
>         select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
>         select HAVE_STACKPROTECTOR
> diff --git a/init/Kconfig b/init/Kconfig
> index 5783a0b87517..3ada33b1d681 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1902,7 +1902,6 @@ config RUST
>         depends on !MODVERSIONS
>         depends on !GCC_PLUGINS
>         depends on !RANDSTRUCT
> -       depends on !SHADOW_CALL_STACK
>         depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
>         help
>           Enables Rust support in the kernel.
>