Subject: [bug#53608] [PATCH 0/2] Rejecting commits unrelated to the introductory commit

From: Ludovic Courtès <[email-masked]>
Date: Wed, 09 Feb 2022 00:02:11 +0100

Howdy Maxime & Attila,

Did you have a chance to look into this series?

  https://issues.guix.gnu.org/53608

It’s relatively simple but I’d rather have other eyeballs looking at it.

TIA.  :-)

Ludo’.

Ludovic Courtès <[email-masked]> skribis:

> Hello!
>
> This patch series fixes a bug in the checkout authentication code:
> it would be possible to authenticate a commit unrelated to the
> introductory commit, provided that target commit passes the
> authorization invariant (see the commit log for details).
>
> Users of Guix and of third-party channels are safe: this bug does
> not have any impact on checkout authentication in those cases.
>
> What concrete cases are affected?  Suppose someone forks Guix and
> publishes a new channel introduction for their fork.  The expectation
> is that any branch started before the introductory channel, for
> instance in the original Guix repo, would fail to be authenticated.
> However, because of this bug, such a branch would be considered
> authentic in the fork because all its commits pass the authorization
> invariant (IOW, they are authentic in the original repository).
>
> Thoughts?
>
> Ludo'.
>
> Ludovic Courtès (2):
>   git: Add 'commit-descendant?'.
>   git-authenticate: Ensure the target is a descendant of the
>     introductory commit.
>
>  doc/guix.texi                  |  4 ++-
>  guix/git-authenticate.scm      | 17 ++++++++--
>  guix/git.scm                   | 24 +++++++++++++-
>  tests/channels.scm             | 60 +++++++++++++++++++++++++++++++++-
>  tests/git-authenticate.scm     | 44 +++++++++++++++++++++++++
>  tests/git.scm                  | 52 ++++++++++++++++++++++++++++-
>  tests/guix-git-authenticate.sh | 17 ++++++++--
>  7 files changed, 210 insertions(+), 8 deletions(-)
>
>
> base-commit: 5052f76afd02e27d6484acf74c86bfa1b6f9cd0e