From: Kees Cook <keescook@chromium.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
linux-hardening@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hardening: Refresh KCFI options, add some more
Date: Tue, 30 Apr 2024 14:15:53 -0700 [thread overview]
Message-ID: <202404301409.D3BC98D5@keescook> (raw)
In-Reply-To: <202404301037.9E34D4811@keescook>
On Tue, Apr 30, 2024 at 10:48:36AM -0700, Kees Cook wrote:
> On Tue, Apr 30, 2024 at 11:21:40AM +0200, Peter Zijlstra wrote:
> > On Fri, Apr 26, 2024 at 03:29:44PM -0700, Kees Cook wrote:
> >
> > > - CONFIG_CFI_CLANG=y for x86 and arm64. (And disable FINEIBT since
> > > it isn't as secure as straight KCFI.)
> >
> > Oi ?
>
> Same objection I always had[1]: moving the check into the destination
> means attacks with control over executable memory contents can just omit
> the check.
>
> But now that I went to go look I see 0c3e806ec0f9 ("x86/cfi: Add boot
> time hash randomization") is only enabled under FINEIBT... seems better
> if that were always enabled...
And FINEIBT actually can't be disabled... :|
And as it turns out CFI_CLANG doesn't work at all on v6.9...
[ 0.587220] no CFI hash found at: __call_sites+0x339a8/0x34450 ffffffffac20cef8 00 00 00 00 00
[ 0.588226] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/alternative.c:1182 __apply_fineibt+0x7a9/0x820
...
[ 0.619220] SMP alternatives: Something went horribly wrong trying to rewrite the CFI implementation.
*hang*
--
Kees Cook
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next prev parent reply other threads:[~2024-04-30 21:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 22:29 [PATCH] hardening: Refresh KCFI options, add some more Kees Cook
2024-04-29 22:16 ` Nathan Chancellor
2024-04-30 5:35 ` Kees Cook
2024-04-30 15:12 ` Nathan Chancellor
2024-04-30 9:21 ` Peter Zijlstra
2024-04-30 17:48 ` Kees Cook
2024-04-30 21:15 ` Kees Cook [this message]
2024-04-30 21:25 ` Kees Cook
2024-05-01 11:06 ` Peter Zijlstra
2024-05-01 19:27 ` Kees Cook
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