From: Dave Martin <Dave.Martin@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: linux-arch@vger.kernel.org, Yu-cheng Yu <yu-cheng.yu@intel.com>,
libc-alpha@sourceware.org, Szabolcs Nagy <szabolcs.nagy@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Jeremy Linton <jeremy.linton@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 0/3] arm64: Enable BTI for the executable as well as the interpreter
Date: Tue, 15 Jun 2021 16:41:08 +0100 [thread overview]
Message-ID: <20210615154106.GS4187@arm.com> (raw)
In-Reply-To: <20210615153341.GI5149@sirena.org.uk>
On Tue, Jun 15, 2021 at 04:33:41PM +0100, Mark Brown via Libc-alpha wrote:
> On Tue, Jun 15, 2021 at 04:22:06PM +0100, Dave Martin wrote:
> > On Thu, Jun 10, 2021 at 11:28:12AM -0500, Jeremy Linton via Libc-alpha wrote:
>
> > > Thus, I expect that with his patch applied to 5.13 the service will fail to
> > > start regardless of the state of MDWE, but it seems to continue starting
> > > when I set MDWE=yes. Same behavior with v1 FWTW.
>
> > If the failure we're trying to detect is that BTI is undesirably left
> > off for the main executable, surely replacing BTIs with NOPs will make
> > no differenece? The behaviour with PROT_BTI clear is strictly more
> > permissive than with PROT_BTI set, so I'm not sure we can test the
> > behaviour this way.
>
> > Maybe I'm missing sometihng / confused myself somewhere.
>
> The issue this patch series is intended to address is that BTI gets
> left off since the dynamic linker is unable to enable PROT_BTI on the
> main executable. We're looking to see that we end up with the stricter
> permissions checking of BTI, with the issue present landing pads
> replaced by NOPs will not fault but once the issue is addressed they
> should start faulting.
Ah, right -- I got the test backwards in my head. Yes, that sounds
reasonable.
> > Looking at /proc/<pid>/maps after the process starts up may be a more
> > reliable approach, so see what the actual prot value is on the main
> > executable's text pages.
>
> smaps rather than maps but yes, executable pages show up as "ex" and BTI
> adds a "bt" tag in VmFlags.
Fumbled that -- yes, I meant smaps!
Ignore me...
Cheers
---Dave
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-15 19:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-04 11:24 [PATCH v2 0/3] arm64: Enable BTI for the executable as well as the interpreter Mark Brown
2021-06-04 11:24 ` [PATCH v2 1/3] elf: Allow architectures to parse properties on the main executable Mark Brown
2021-06-09 15:16 ` Dave Martin
2021-06-10 13:41 ` Mark Brown
2021-06-04 11:24 ` [PATCH v2 2/3] arm64: Enable BTI for main executable as well as the interpreter Mark Brown
2021-06-09 15:17 ` Dave Martin
2021-06-10 13:19 ` Mark Brown
2021-06-10 15:34 ` Dave Martin
2021-06-04 11:24 ` [PATCH v2 3/3] elf: Remove has_interp property from arch_adjust_elf_prot() Mark Brown
2021-06-09 15:17 ` Dave Martin
2021-06-09 16:55 ` Yu, Yu-cheng
2021-06-10 9:58 ` Dave Martin
2021-06-10 18:17 ` Yu, Yu-cheng
2021-06-10 13:34 ` Mark Brown
2021-06-10 15:40 ` Dave Martin
2021-06-10 16:28 ` [PATCH v2 0/3] arm64: Enable BTI for the executable as well as the interpreter Jeremy Linton
2021-06-14 16:00 ` Mark Brown
2021-06-15 15:22 ` Dave Martin
2021-06-15 15:33 ` Mark Brown
2021-06-15 15:41 ` Dave Martin [this message]
2021-06-16 5:12 ` Jeremy Linton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210615154106.GS4187@arm.com \
--to=dave.martin@arm.com \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=jeremy.linton@arm.com \
--cc=libc-alpha@sourceware.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=szabolcs.nagy@arm.com \
--cc=will@kernel.org \
--cc=yu-cheng.yu@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).