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From: Maxime Devos <maximedevos@telenet.be>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: guix-devel@gnu.org
Subject: Re: Potential security weakness in Guix services
Date: Sat, 06 Feb 2021 23:01:49 +0100	[thread overview]
Message-ID: <3c869a8c38ba8c98e29a06de1404f9dbf8fe7a68.camel@telenet.be> (raw)
In-Reply-To: <87sg68zy15.fsf@gnu.org>

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On Sat, 2021-02-06 at 22:28 +0100, Ludovic Courtès wrote:
> Maxime Devos <maximedevos@telenet.be> skribis:
> 
> I just remembered this subtlety: during bootup, the activation code is
> evaluated by the Guile that’s in the initrd, which is a
> statically-linked Guile, and thus we can’t use ‘dynamic-link’ & co. in
> there.  :-/

I remember trying to use make-forkexec-constructor/container from activation
code, which didn't work, due to some uses of dynamic-func ...  I see two
possible options to take:

* extend gnu/packages/patches/guile-linux-syscalls.patch with, say,
  a "%extra-function-pointers" procedure returning a vector (or alist,
  or something else) of pointers to the relevant C functions.  This
  allows us to write the FFI code mostly in Scheme, and only write C
  code for obtaining function pointer.

* extend gnu/packages/patches/guile-linux-syscalls.patch with
  additional bindings, or write a patch extending guile itself with
  fchownat
and other *at support.  This (second) patch should be
  submitted upstream, but can be kept in gnu/packages/patches until
  support for *at
functionality makes it upstream.

The first option is the path I would find the most convenient myself
(though I'll probably write C code for parsing struct stat, as its
layout apparently varies much with kernel (Linux / Hurd) and
architecture), but the latter seems the way to go to prevent duplicate
effort upstream later on.

My C is a little rusty, but I'll have a try at the latter.

Maxime.

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  reply	other threads:[~2021-02-06 22:03 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-28 21:53 Potential security weakness in Guix services Leo Famulari
2021-01-29 13:33 ` Maxime Devos
2021-01-29 15:25   ` Maxime Devos
2021-02-01 15:35 ` Ludovic Courtès
2021-02-01 15:47   ` Julien Lepiller
2021-02-01 16:19     ` Maxime Devos
2021-02-02 13:07       ` Ludovic Courtès
2021-02-02 13:38         ` Maxime Devos
2021-02-02 15:30           ` Maxime Devos
2021-02-05  9:57           ` Ludovic Courtès
2021-02-05 12:20             ` Maxime Devos
2021-02-05 14:16               ` Maxime Devos
2021-02-06 21:28                 ` Ludovic Courtès
2021-02-06 22:01                   ` Maxime Devos [this message]
2021-02-10 20:45                     ` Ludovic Courtès
2021-02-06 21:26               ` Ludovic Courtès
2021-02-14 12:29                 ` TOCTTOU race (was: Potential security weakness in Guix services) Maxime Devos
2021-02-14 17:19                   ` Bengt Richter
2021-02-18 17:54                   ` TOCTTOU race Ludovic Courtès
2021-02-19 18:01                     ` Maxime Devos
2021-02-22  8:54                       ` Ludovic Courtès
2021-02-22 19:13                         ` Maxime Devos
2021-02-23 15:30                           ` Ludovic Courtès
2021-02-27  7:41                             ` Maxime Devos
2021-03-10 10:07                               ` Ludovic Courtès
2021-02-10 20:54             ` Potential security weakness in Guix services Christopher Lemmer Webber

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