From: Nick Desaulniers <ndesaulniers@google.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
Nathan Chancellor <nathan@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Christoph Hellwig <hch@infradead.org>, bpf <bpf@vger.kernel.org>,
linux-hardening@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
PCI <linux-pci@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 04/17] module: ensure __cfi_check alignment
Date: Thu, 18 Mar 2021 12:27:43 -0700 [thread overview]
Message-ID: <CAKwvOdkbok-BoYGfvHH1HR=cMztaBYZKB-UHRDZ4g5YjSCuq2A@mail.gmail.com> (raw)
In-Reply-To: <20210318171111.706303-5-samitolvanen@google.com>
On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> CONFIG_CFI_CLANG_SHADOW assumes the __cfi_check() function is page
> aligned and at the beginning of the .text section. While Clang would
> normally align the function correctly, it fails to do so for modules
> with no executable code.
>
> This change ensures the correct __cfi_check() location and
> alignment. It also discards the .eh_frame section, which Clang can
> generate with certain sanitizers, such as CFI.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=46293
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> scripts/module.lds.S | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/module.lds.S b/scripts/module.lds.S
> index 168cd27e6122..93518579cf5d 100644
> --- a/scripts/module.lds.S
> +++ b/scripts/module.lds.S
> @@ -3,10 +3,19 @@
> * Archs are free to supply their own linker scripts. ld will
> * combine them automatically.
> */
> +#include <asm/page.h>
> +
> +#ifdef CONFIG_CFI_CLANG
> +# define ALIGN_CFI ALIGN(PAGE_SIZE)
> +#else
> +# define ALIGN_CFI
> +#endif
> +
> SECTIONS {
> /DISCARD/ : {
> *(.discard)
> *(.discard.*)
> + *(.eh_frame)
Do we want to unconditionally discard this section from modules for
all arches/configs? I like how we conditionally do so on
SANITIZER_DISCARDS in include/asm-generic/vmlinux.lds.h for example.
> }
>
> __ksymtab 0 : { *(SORT(___ksymtab+*)) }
> @@ -40,7 +49,14 @@ SECTIONS {
> *(.rodata..L*)
> }
>
> - .text : { *(.text .text.[0-9a-zA-Z_]*) }
> + /*
> + * With CONFIG_CFI_CLANG, we assume __cfi_check is at the beginning
> + * of the .text section, and is aligned to PAGE_SIZE.
> + */
> + .text : ALIGN_CFI {
> + *(.text.__cfi_check)
> + *(.text .text.[0-9a-zA-Z_]* .text..L.cfi*)
> + }
> }
>
> /* bring in arch-specific sections */
> --
> 2.31.0.291.g576ba9dcdaf-goog
>
--
Thanks,
~Nick Desaulniers
next prev parent reply other threads:[~2021-03-18 19:28 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 17:10 [PATCH v2 00/17] Add support for Clang CFI Sami Tolvanen
2021-03-18 17:10 ` [PATCH v2 01/17] add " Sami Tolvanen
2021-03-18 22:29 ` Peter Zijlstra
2021-03-18 23:48 ` Sami Tolvanen
2021-03-19 12:26 ` Peter Zijlstra
2021-03-19 13:52 ` Paul E. McKenney
2021-03-19 16:17 ` Sami Tolvanen
2021-03-19 17:03 ` Paul E. McKenney
2021-03-18 17:10 ` [PATCH v2 02/17] cfi: add __cficanonical Sami Tolvanen
2021-03-18 17:49 ` Nick Desaulniers
2021-03-18 17:10 ` [PATCH v2 03/17] mm: add generic __va_function and __pa_function macros Sami Tolvanen
2021-03-18 17:10 ` [PATCH v2 04/17] module: ensure __cfi_check alignment Sami Tolvanen
2021-03-18 19:27 ` Nick Desaulniers [this message]
2021-03-18 21:43 ` Sami Tolvanen
2021-03-18 17:10 ` [PATCH v2 05/17] workqueue: use WARN_ON_FUNCTION_MISMATCH Sami Tolvanen
2021-03-18 18:50 ` Nick Desaulniers
2021-03-18 21:38 ` Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 06/17] kthread: " Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 07/17] kallsyms: strip ThinLTO hashes from static functions Sami Tolvanen
2021-03-18 19:00 ` Nick Desaulniers
2021-03-18 21:41 ` Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 08/17] bpf: disable CFI in dispatcher functions Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 09/17] lib/list_sort: fix function type mismatches Sami Tolvanen
2021-03-18 18:31 ` Nick Desaulniers
2021-03-18 21:31 ` Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 10/17] lkdtm: use __va_function Sami Tolvanen
2021-03-18 18:43 ` Nick Desaulniers
2021-03-18 18:45 ` Nick Desaulniers
2021-03-18 17:11 ` [PATCH v2 11/17] psci: use __pa_function for cpu_resume Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 12/17] arm64: implement __va_function Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 13/17] arm64: use __pa_function Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 14/17] arm64: add __nocfi to functions that jump to a physical address Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 15/17] arm64: add __nocfi to __apply_alternatives Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 16/17] KVM: arm64: Disable CFI for nVHE Sami Tolvanen
2021-03-18 17:11 ` [PATCH v2 17/17] arm64: allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
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