All of lore.kernel.org
 help / color / mirror / Atom feed
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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Lennart Poettering <mzxreary@0pointer.de>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: 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>,
	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>,
	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

  reply	other threads:[~2020-10-22  8:39 UTC|newest]

Thread overview: 76+ 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 [this message]
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
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 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
2020-10-24 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
2020-10-25 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
2020-10-24 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 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 16:31             ` 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

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=20201022083823.GA324825@gardel-login \
    --to=mzxreary@0pointer.de \
    --cc=Catalin.Marinas@arm.com \
    --cc=broonie@kernel.org \
    --cc=dave.martin@arm.com \
    --cc=fweimer@redhat.com \
    --cc=keescook@chromium.org \
    --cc=libc-alpha@sourceware.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=systemd-devel@lists.freedesktop.org \
    --cc=szabolcs.nagy@arm.com \
    --cc=toiwoton@gmail.com \
    --cc=will.deacon@arm.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.