[v5,12/14] arm64: vdso: disable Shadow Call Stack

Message ID	20191105235608.107702-13-samitolvanen@google.com (mailing list archive)
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Headers	show Return-Path: <SRS0=mAHo=Y5=lists.infradead.org=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@kernel.org> DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A682F206B8 Date: Tue, 5 Nov 2019 15:56:06 -0800 In-Reply-To: <20191105235608.107702-1-samitolvanen@google.com> Message-Id: <20191105235608.107702-13-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191105235608.107702-1-samitolvanen@google.com> Subject: [PATCH v5 12/14] arm64: vdso: disable Shadow Call Stack From: Sami Tolvanen <samitolvanen@google.com> To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Steven Rostedt <rostedt@goodmis.org>, Masami Hiramatsu <mhiramat@kernel.org>, Ard Biesheuvel <ard.biesheuvel@linaro.org> summary: Content analysis details: (-7.7 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:84a listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -7.5 USER_IN_DEF_DKIM_WL From: address is in the default DKIM white-list 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.0 DKIMWL_WL_MED DKIMwl.org - Medium sender Precedence: list Cc: Mark Rutland <mark.rutland@arm.com>, Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>, Masahiro Yamada <yamada.masahiro@socionext.com>, Marc Zyngier <maz@kernel.org>, kernel-hardening@lists.openwall.com, Nick Desaulniers <ndesaulniers@google.com>, linux-kernel@vger.kernel.org, Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>, clang-built-linux@googlegroups.com, Sami Tolvanen <samitolvanen@google.com>, Laura Abbott <labbott@redhat.com>, Dave Martin <Dave.Martin@arm.com>, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org> Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org
Series	add support for Clang's Shadow Call Stack \| expand [v5,00/14] add support for Clang's Shadow Call Stack [v5,01/14] arm64: mm: avoid x18 in idmap_kpti_install_ng_mappings [v5,02/14] arm64/lib: copy_page: avoid x18 register in assembler code [v5,03/14] arm64: kvm: stop treating register x18 as caller save [v5,04/14] arm64: kernel: avoid x18 in __cpu_soft_restart [v5,05/14] add support for Clang's Shadow Call Stack (SCS) [v5,06/14] scs: add accounting [v5,07/14] scs: add support for stack usage debugging [v5,08/14] arm64: disable function graph tracing with SCS [v5,09/14] arm64: reserve x18 from general allocation with SCS [v5,10/14] arm64: preserve x18 when CPU is suspended [v5,11/14] arm64: efi: restore x18 if it was corrupted [v5,12/14] arm64: vdso: disable Shadow Call Stack [v5,13/14] arm64: disable SCS for hypervisor code [v5,14/14] arm64: implement Shadow Call Stack

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Subject: [PATCH v5 12/14] arm64: vdso: disable Shadow Call Stack
From: Sami Tolvanen <samitolvanen@google.com>
To: Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>,
 Steven Rostedt <rostedt@goodmis.org>,
 Masami Hiramatsu <mhiramat@kernel.org>,
 Ard Biesheuvel <ard.biesheuvel@linaro.org>
Precedence: list
Cc: Mark Rutland <mark.rutland@arm.com>, Kees Cook <keescook@chromium.org>,
 Jann Horn <jannh@google.com>,
 Masahiro Yamada <yamada.masahiro@socionext.com>,
 Marc Zyngier <maz@kernel.org>, kernel-hardening@lists.openwall.com,
 Nick Desaulniers <ndesaulniers@google.com>, linux-kernel@vger.kernel.org,
 Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
 clang-built-linux@googlegroups.com, Sami Tolvanen <samitolvanen@google.com>,
 Laura Abbott <labbott@redhat.com>, Dave Martin <Dave.Martin@arm.com>,
 linux-arm-kernel@lists.infradead.org
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Series

add support for Clang's Shadow Call Stack | expand

Commit Message

Sami Tolvanen Nov. 5, 2019, 11:56 p.m. UTC

Shadow stacks are only available in the kernel, so disable SCS
instrumentation for the vDSO.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 arch/arm64/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Mark Rutland Nov. 15, 2019, 2:43 p.m. UTC | #1

On Tue, Nov 05, 2019 at 03:56:06PM -0800, Sami Tolvanen wrote:
> Shadow stacks are only available in the kernel, so disable SCS
> instrumentation for the vDSO.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>

I gave this a spin, looked at objdump, and found everything in the vDSO
was a leaf function. I hacked the code around a bit to force a function
call, and I see that just uses x29 and x30 as expected, with nothing
touching x18.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
>  arch/arm64/kernel/vdso/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> index dd2514bb1511..a87a4f11724e 100644
> --- a/arch/arm64/kernel/vdso/Makefile
> +++ b/arch/arm64/kernel/vdso/Makefile
> @@ -25,7 +25,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING
>  
>  VDSO_LDFLAGS := -Bsymbolic
>  
> -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
> +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)
>  KBUILD_CFLAGS			+= $(DISABLE_LTO)
>  KASAN_SANITIZE			:= n
>  UBSAN_SANITIZE			:= n
> -- 
> 2.24.0.rc1.363.gb1bccd3e3d-goog
>

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index dd2514bb1511..a87a4f11724e 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -25,7 +25,7 @@  ccflags-y += -DDISABLE_BRANCH_PROFILING
 
 VDSO_LDFLAGS := -Bsymbolic
 
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)
 KBUILD_CFLAGS			+= $(DISABLE_LTO)
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n

[v5,12/14] arm64: vdso: disable Shadow Call Stack

Commit Message

Comments

Patch