From: Lennart Poettering <mzxreary@0pointer.de>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Florian Weimer <fweimer@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
systemd-devel@lists.freedesktop.org,
Kees Cook <keescook@chromium.org>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
Topi Miettinen <toiwoton@gmail.com>,
libc-alpha@sourceware.org, Dave Martin <dave.martin@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [systemd-devel] BTI interaction between seccomp filters in systemd and glibc mprotect calls, causing service failures
Date: Thu, 22 Oct 2020 10:38:23 +0200 [thread overview]
Message-ID: <20201022083823.GA324825@gardel-login> (raw)
In-Reply-To: <20201022082912.GQ3819@arm.com>
On Do, 22.10.20 09:29, Szabolcs Nagy (szabolcs.nagy@arm.com) wrote:
> > > The dynamic loader has to process the LOAD segments to get to the ELF
> > > note that says to enable BTI. Maybe we could do a first pass and load
> > > only the segments that cover notes. But that requires lots of changes
> > > to generic code in the loader.
> >
> > What if the loader always enabled BTI for PROT_EXEC pages, but then when
> > discovering that this was a mistake, mprotect() the pages without BTI? Then
> > both BTI and MDWX would work and the penalty of not getting MDWX would fall
> > to non-BTI programs. What's the expected proportion of BTI enabled code vs.
> > disabled in the future, is it perhaps expected that a distro would enable
> > the flag globally so eventually only a few legacy programs might be
> > unprotected?
>
> i thought mprotect(PROT_EXEC) would get filtered
> with or without bti, is that not the case?
We can adjust the filter in systemd to match any combination of
flags to allow and to deny.
Lennart
--
Lennart Poettering, Berlin
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next prev parent reply other threads:[~2020-10-22 8:39 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8584c14f-5c28-9d70-c054-7c78127d84ea@arm.com>
2020-10-22 7:18 ` [systemd-devel] BTI interaction between seccomp filters in systemd and glibc mprotect calls, causing service failures Lennart Poettering
2020-10-22 7:54 ` Florian Weimer
2020-10-22 8:17 ` Topi Miettinen
2020-10-22 8:25 ` Florian Weimer
2020-10-22 8:29 ` Szabolcs Nagy
2020-10-22 8:38 ` Lennart Poettering [this message]
2020-10-22 9:31 ` Catalin Marinas
2020-10-22 10:12 ` Topi Miettinen
2020-10-22 10:27 ` Florian Weimer
2020-10-23 6:13 ` Szabolcs Nagy
2020-10-23 9:04 ` Catalin Marinas
2020-10-22 10:03 ` Topi Miettinen
2020-10-22 8:05 ` Szabolcs Nagy
2020-10-22 8:31 ` Lennart Poettering
[not found] ` <20201022075447.GO3819@arm.com>
2020-10-22 10:39 ` Topi Miettinen
2020-10-22 20:02 ` Kees Cook
2020-10-22 22:24 ` Topi Miettinen
2020-10-23 17:52 ` Salvatore Mesoraca
2020-10-24 11:34 ` Topi Miettinen
2020-10-24 14:12 ` Salvatore Mesoraca
2020-10-25 13:42 ` Jordan Glover
2020-10-23 9:02 ` Catalin Marinas
2020-10-24 11:01 ` Topi Miettinen
2020-10-26 14:52 ` Catalin Marinas
2020-10-26 15:56 ` Dave Martin
2020-10-26 16:51 ` Mark Brown
2020-10-26 16:31 ` Topi Miettinen
2020-10-26 16:24 ` Dave Martin
2020-10-26 16:39 ` Topi Miettinen
2020-10-26 16:45 ` Florian Weimer
2020-10-27 14:22 ` Dave Martin
2020-10-27 14:41 ` Florian Weimer
2020-10-26 16:57 ` Szabolcs Nagy
2020-10-26 17:52 ` Dave Martin
2020-10-26 22:39 ` Jeremy Linton
2020-10-27 14:15 ` Dave Martin
2020-10-29 11:02 ` Catalin Marinas
2020-11-04 12:18 ` Dave Martin
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