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From: Catalin Marinas <catalin.marinas@arm.com>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>,
	Topi Miettinen <toiwoton@gmail.com>,
	Florian Weimer <fweimer@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	systemd-devel@lists.freedesktop.org,
	Kees Cook <keescook@chromium.org>,
	Will Deacon <will.deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Mark Brown <broonie@kernel.org>,
	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: Fri, 23 Oct 2020 10:04:51 +0100	[thread overview]
Message-ID: <20201023090451.GB25736@gaia> (raw)
In-Reply-To: <20201023061316.GR3819@arm.com>

On Fri, Oct 23, 2020 at 07:13:17AM +0100, Szabolcs Nagy wrote:
> The 10/22/2020 10:31, Catalin Marinas wrote:
> > IIUC, the problem is with the main executable which is mapped by the
> > kernel without PROT_BTI. The dynamic loader wants to set PROT_BTI but
> > does not have the original file descriptor to be able to remap. Its only
> > choice is mprotect() and this fails because of the MDWX policy.
> > 
> > Not sure whether the kernel has the right information but could it map
> > the main executable with PROT_BTI if the corresponding PT_GNU_PROPERTY
> > is found? The current ABI states it only sets PROT_BTI for the
> > interpreter who'd be responsible for setting the PROT_BTI on the main
> > executable. I can't tell whether it would break anything but it's worth
> > a try:
> 
> i think it would work, but now i can't easily
> tell from the libc if i have to do the mprotect
> on the main exe or not.
> 
> i guess i can just always mprotect and ignore
> the failure?

I replied to Keys before reading your email. So yeah, still issue
mprotect() but ignore the failure.

-- 
Catalin

WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com>
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>,
	libc-alpha@sourceware.org, 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>,
	Lennart Poettering <mzxreary@0pointer.de>,
	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: Fri, 23 Oct 2020 10:04:51 +0100	[thread overview]
Message-ID: <20201023090451.GB25736@gaia> (raw)
In-Reply-To: <20201023061316.GR3819@arm.com>

On Fri, Oct 23, 2020 at 07:13:17AM +0100, Szabolcs Nagy wrote:
> The 10/22/2020 10:31, Catalin Marinas wrote:
> > IIUC, the problem is with the main executable which is mapped by the
> > kernel without PROT_BTI. The dynamic loader wants to set PROT_BTI but
> > does not have the original file descriptor to be able to remap. Its only
> > choice is mprotect() and this fails because of the MDWX policy.
> > 
> > Not sure whether the kernel has the right information but could it map
> > the main executable with PROT_BTI if the corresponding PT_GNU_PROPERTY
> > is found? The current ABI states it only sets PROT_BTI for the
> > interpreter who'd be responsible for setting the PROT_BTI on the main
> > executable. I can't tell whether it would break anything but it's worth
> > a try:
> 
> i think it would work, but now i can't easily
> tell from the libc if i have to do the mprotect
> on the main exe or not.
> 
> i guess i can just always mprotect and ignore
> the failure?

I replied to Keys before reading your email. So yeah, still issue
mprotect() but ignore the failure.

-- 
Catalin

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  reply	other threads:[~2020-10-23  9:04 UTC|newest]

Thread overview: 88+ 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  7:18   ` Lennart Poettering
2020-10-22  7:54   ` Florian Weimer
2020-10-22  7:54     ` Florian Weimer
2020-10-22  8:17     ` Topi Miettinen
2020-10-22  8:17       ` Topi Miettinen
2020-10-22  8:25       ` Florian Weimer
2020-10-22  8:25         ` Florian Weimer
2020-10-22  8:29       ` Szabolcs Nagy
2020-10-22  8:29         ` Szabolcs Nagy
2020-10-22  8:38         ` Lennart Poettering
2020-10-22  8:38           ` Lennart Poettering
2020-10-22  9:31           ` Catalin Marinas
2020-10-22  9:31             ` Catalin Marinas
2020-10-22 10:12             ` Topi Miettinen
2020-10-22 10:12               ` Topi Miettinen
2020-10-22 10:27               ` Florian Weimer
2020-10-22 10:27                 ` Florian Weimer
2020-10-23  6:13             ` Szabolcs Nagy
2020-10-23  6:13               ` Szabolcs Nagy
2020-10-23  9:04               ` Catalin Marinas [this message]
2020-10-23  9:04                 ` Catalin Marinas
2020-10-22 10:03         ` Topi Miettinen
2020-10-22 10:03           ` Topi Miettinen
2020-10-22  8:05   ` Szabolcs Nagy
2020-10-22  8:05     ` Szabolcs Nagy
2020-10-22  8:31     ` Lennart Poettering
2020-10-22  8:31       ` Lennart Poettering
     [not found] ` <20201022075447.GO3819@arm.com>
2020-10-22 10:39   ` Topi Miettinen
2020-10-22 10:39     ` Topi Miettinen
2020-10-22 20:02     ` Kees Cook
2020-10-22 20:02       ` Kees Cook
2020-10-22 20:02       ` Kees Cook
2020-10-22 22:24       ` Topi Miettinen
2020-10-22 22:24         ` Topi Miettinen
2020-10-22 22:24         ` Topi Miettinen
2020-10-23 17:52         ` Salvatore Mesoraca
2020-10-23 17:52           ` Salvatore Mesoraca
2020-10-23 17:52           ` Salvatore Mesoraca
2020-10-24 11:34           ` Topi Miettinen
2020-10-24 11:34             ` Topi Miettinen
2020-10-24 11:34             ` Topi Miettinen
2020-10-24 14:12             ` Salvatore Mesoraca
2020-10-24 14:12               ` Salvatore Mesoraca
2020-10-24 14:12               ` Salvatore Mesoraca
2020-10-25 13:42               ` Jordan Glover
2020-10-25 13:42                 ` Jordan Glover
2020-10-25 13:42                 ` Jordan Glover
2020-10-23  9:02       ` Catalin Marinas
2020-10-23  9:02         ` Catalin Marinas
2020-10-23  9:02         ` Catalin Marinas
2020-10-24 11:01         ` Topi Miettinen
2020-10-24 11:01           ` Topi Miettinen
2020-10-24 11:01           ` Topi Miettinen
2020-10-26 14:52           ` Catalin Marinas
2020-10-26 14:52             ` Catalin Marinas
2020-10-26 14:52             ` Catalin Marinas
2020-10-26 15:56             ` Dave Martin
2020-10-26 15:56               ` Dave Martin
2020-10-26 15:56               ` Dave Martin
2020-10-26 16:51               ` Mark Brown
2020-10-26 16:51                 ` Mark Brown
2020-10-26 16:51                 ` Mark Brown
2020-10-26 16:31             ` Topi Miettinen
2020-10-26 16:31               ` Topi Miettinen
2020-10-26 16:31               ` Topi Miettinen
2020-10-26 16:24 ` Dave Martin
2020-10-26 16:24   ` Dave Martin
2020-10-26 16:39   ` Topi Miettinen
2020-10-26 16:39     ` Topi Miettinen
2020-10-26 16:45   ` Florian Weimer
2020-10-26 16:45     ` Florian Weimer
2020-10-27 14:22     ` Dave Martin
2020-10-27 14:22       ` Dave Martin
2020-10-27 14:41       ` Florian Weimer
2020-10-27 14:41         ` Florian Weimer
2020-10-26 16:57   ` Szabolcs Nagy
2020-10-26 16:57     ` Szabolcs Nagy
2020-10-26 17:52     ` Dave Martin
2020-10-26 17:52       ` Dave Martin
2020-10-26 22:39       ` Jeremy Linton
2020-10-26 22:39         ` Jeremy Linton
2020-10-27 14:15         ` Dave Martin
2020-10-27 14:15           ` Dave Martin
2020-10-29 11:02           ` Catalin Marinas
2020-10-29 11:02             ` Catalin Marinas
2020-11-04 12:18             ` Dave Martin
2020-11-04 12:18               ` Dave Martin

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