From: Thomas Gleixner <tglx@linutronix.de>
To: Sami Tolvanen <samitolvanen@google.com>, x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Sami Tolvanen <samitolvanen@google.com>
Subject: Re: [PATCH 06/15] x86: Avoid CFI jump tables in IDT and entry points
Date: Sat, 17 Apr 2021 00:26:56 +0200 [thread overview]
Message-ID: <87im4luaq7.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210416203844.3803177-7-samitolvanen@google.com>
On Fri, Apr 16 2021 at 13:38, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, the compiler replaces function addresses in C
> code with jump table addresses.
Fine.
> To avoid referring to jump tables in entry code with PTI,
What has this to do with PTI?
> disable CFI for IDT and paravirt code, and use function_nocfi() to
> prevent jump table addresses from being added to the IDT or system
> call entry points.
How does this changelog make sense for anyone not familiar with the
matter at hand?
Where is the analysis why excluding
> +CFLAGS_REMOVE_idt.o := $(CC_FLAGS_CFI)
> +CFLAGS_REMOVE_paravirt.o := $(CC_FLAGS_CFI)
all of idt.c and paravirt.c is correct and how that is going to be
correct in the future?
These files are excluded from CFI, so I can add whatever I want to them
and circumvent the purpose of CFI, right?
Brilliant plan that. But I know, sekurity ...
Thanks,
tglx
next prev parent reply other threads:[~2021-04-16 22:26 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 20:38 [PATCH 00/15] x86: Add support for Clang CFI Sami Tolvanen
2021-04-16 20:38 ` [PATCH 01/15] objtool: Find a destination for jumps beyond the section end Sami Tolvanen
2021-04-20 18:14 ` Josh Poimboeuf
2021-04-20 20:25 ` Sami Tolvanen
2021-04-20 22:55 ` Josh Poimboeuf
2021-04-20 22:58 ` Nick Desaulniers
2021-04-16 20:38 ` [PATCH 02/15] objtool: Add CONFIG_CFI_CLANG support Sami Tolvanen
2021-04-20 19:47 ` Josh Poimboeuf
2021-04-20 20:45 ` Sami Tolvanen
2021-04-16 20:38 ` [PATCH 03/15] objtool: Add ASM_STACK_FRAME_NON_STANDARD Sami Tolvanen
2021-04-16 20:38 ` [PATCH 04/15] static_call: Use global functions for the self-test Sami Tolvanen
2021-04-16 21:37 ` Thomas Gleixner
2021-04-17 0:16 ` Thomas Gleixner
2021-04-16 20:38 ` [PATCH 05/15] x86: Implement function_nocfi Sami Tolvanen
2021-04-16 21:18 ` Borislav Petkov
2021-04-16 21:49 ` Sami Tolvanen
2021-04-16 22:02 ` Borislav Petkov
2021-04-16 22:06 ` Andy Lutomirski
2021-04-16 22:14 ` Borislav Petkov
2021-04-16 22:20 ` Andy Lutomirski
2021-04-16 22:37 ` Kees Cook
2021-04-16 23:02 ` Thomas Gleixner
2021-04-17 10:16 ` Thomas Gleixner
2021-04-19 15:13 ` Sami Tolvanen
2021-04-16 22:28 ` Kees Cook
2021-04-16 22:52 ` Andy Lutomirski
2021-04-16 22:58 ` Kees Cook
2021-04-16 23:40 ` Kees Cook
2021-04-17 23:19 ` Andy Lutomirski
2021-04-17 23:53 ` Thomas Gleixner
2021-04-18 0:11 ` Andy Lutomirski
2021-04-18 16:17 ` Thomas Gleixner
2021-04-18 22:57 ` Andy Lutomirski
2021-04-19 15:20 ` Sami Tolvanen
2021-04-19 15:26 ` David Laight
2021-04-19 17:46 ` Andy Lutomirski
2021-04-17 14:20 ` David Laight
2021-04-17 15:48 ` Andy Lutomirski
2021-04-19 8:40 ` Rasmus Villemoes
2021-04-19 16:45 ` Joao Moreira
2021-04-19 21:52 ` David Laight
2021-04-16 22:16 ` Kees Cook
2021-04-16 22:13 ` Thomas Gleixner
2021-04-16 20:38 ` [PATCH 06/15] x86: Avoid CFI jump tables in IDT and entry points Sami Tolvanen
2021-04-16 22:26 ` Thomas Gleixner [this message]
2021-04-16 23:56 ` Kees Cook
2021-04-17 0:02 ` Thomas Gleixner
2021-04-16 20:38 ` [PATCH 07/15] x86/ftrace: Use function_nocfi in MCOUNT_ADDR Sami Tolvanen
2021-04-16 20:38 ` [PATCH 08/15] x86/extable: Do not mark exception callback as CFI Sami Tolvanen
2021-04-16 20:38 ` [PATCH 09/15] x86/alternatives: Use C int3 selftest but disable KASAN Sami Tolvanen
2021-04-17 11:37 ` Peter Zijlstra
2021-04-19 15:26 ` Sami Tolvanen
2021-04-20 7:19 ` Peter Zijlstra
2021-04-16 20:38 ` [PATCH 10/15] x86/purgatory: Disable CFI Sami Tolvanen
2021-04-16 20:38 ` [PATCH 11/15] x86, relocs: Ignore __typeid__ relocations Sami Tolvanen
2021-04-16 20:38 ` [PATCH 12/15] x86, module: " Sami Tolvanen
2021-04-16 20:38 ` [PATCH 13/15] x86, cpu: Use LTO for cpu.c with CFI Sami Tolvanen
2021-04-16 20:38 ` [PATCH 14/15] x86, kprobes: Fix optprobe_template_func type mismatch Sami Tolvanen
2021-04-16 20:38 ` [PATCH 15/15] x86, build: Allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
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