From: "H.J. Lu" <hjl.tools@gmail.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Mark Brown <broonie@kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Yu-cheng Yu <yu-cheng.yu@intel.com>,
GNU C Library <libc-alpha@sourceware.org>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
Jeremy Linton <jeremy.linton@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 0/4] arm64: Enable BTI for the executable as well as the interpreter
Date: Mon, 17 Jan 2022 11:01:25 -0800 [thread overview]
Message-ID: <CAMe9rOo5zWO1BwZGhqGdWuCjsq86YUo4ptqXkFVNSwXbU+ZS-Q@mail.gmail.com> (raw)
In-Reply-To: <20ae043b-a013-068d-2d83-16e63f5b4989@linaro.org>
On Mon, Jan 17, 2022 at 10:17 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
>
>
> On 17/01/2022 14:54, Catalin Marinas via Libc-alpha wrote:
> > On Fri, Jan 07, 2022 at 12:01:17PM +0000, Catalin Marinas wrote:
> >> I think we can look at this from two angles:
> >>
> >> 1. Ignoring MDWE, should whoever does the original mmap() also honour
> >> PROT_BTI? We do this for static binaries but, for consistency, should
> >> we extend it to dynamic executable?
> >>
> >> 2. A 'simple' fix to allow MDWE together with BTI.
> >
> > Thinking about it, (1) is not that different from the kernel setting
> > PROT_EXEC on the main executable when the dynamic loader could've done
> > it as well. There is a case for making this more consistent: whoever
> > does the mmap() should use the full attributes.
> >
> > Question for the toolchain people: would the compiler ever generate
> > relocations in the main executable that the linker needs to resolve via
> > an mprotect(READ|WRITE) followed by mprotect(READ|EXEC)? If yes, we'd
> > better go for a proper MDWE implementation in the kernel.
> >
>
> Yes, text relocations. However these are deprecated (some libcs even do
> not support it) and have a lot of drawbacks.
We are taking a different approach for CET enabling. CET will be
changed to be enabled from user space:
https://gitlab.com/x86-glibc/glibc/-/tree/users/hjl/cet/enable
and the CET kernel no longer enables CET automatically:
https://github.com/hjl-tools/linux/tree/hjl/cet%2F5.16.0-v4
--
H.J.
next prev parent reply other threads:[~2022-01-17 19:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-15 15:27 Mark Brown
2021-11-15 15:27 ` [PATCH v7 1/4] elf: Allow architectures to parse properties on the main executable Mark Brown
2021-11-15 15:27 ` [PATCH v7 2/4] arm64: Enable BTI for main executable as well as the interpreter Mark Brown
2021-11-15 15:27 ` [PATCH v7 3/4] elf: Remove has_interp property from arch_adjust_elf_prot() Mark Brown
2021-11-15 15:27 ` [PATCH v7 4/4] elf: Remove has_interp property from arch_parse_elf_property() Mark Brown
2021-12-08 18:23 ` [PATCH v7 0/4] arm64: Enable BTI for the executable as well as the interpreter Catalin Marinas
2021-12-09 11:10 ` Szabolcs Nagy
2022-01-04 17:32 ` Mark Brown
2022-01-05 22:42 ` Jeremy Linton
2022-01-06 11:00 ` Catalin Marinas
2022-01-06 16:09 ` Jeremy Linton
2022-01-06 18:13 ` Catalin Marinas
2022-01-06 19:07 ` Mark Brown
2022-01-07 12:01 ` Catalin Marinas
2022-01-07 13:10 ` Mark Brown
2022-01-17 17:54 ` Catalin Marinas
2022-01-17 18:16 ` Adhemerval Zanella
2022-01-17 19:01 ` H.J. Lu [this message]
2022-01-18 11:22 ` Szabolcs Nagy
2022-01-18 12:55 ` H.J. Lu
2022-01-18 11:02 ` Szabolcs Nagy
2022-01-27 12:24 ` Catalin Marinas
2022-01-27 14:48 ` Szabolcs Nagy
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