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

From: Ludovic Courtès <[email-masked]>
Date: Fri, 28 Jan 2022 18:31:42 +0100

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
-- 
2.34.0