Re: [PATCH v1 0/2] gpg-interface: prefer check_signature() for GPG verification

> This patch refactors the use of verify_signed_buffer() for GPG
> verification to use check_signature() instead.
>
> Previously, both check_signature() and verify_signed_buffer() were used
> to verify signatures in various parts of Git.  However,
> verify_signed_buffer() does not parse the GPG status message.  Instead,
> it relies entirely on the exit code from GPG coupled with the existence
> of a GOODSIG string in the output buffer.  Unfortunately, the mere
> prescience of GOODSIG does not necessarily imply a valid signature, as
> shown by Michał Górny [1].
>
> verify_signed_buffer() should be reserved for internal use by
> check_signature() since check_signature() parses and verifies the status
> message.  This is accomplished in this patch.
>
> Changes since v0:
> * Added regression tests for log-tree and fmt-merge-msg.
> * Fixed a bug in log-tree.c that caused "No signature" to be shown
>   erroneously.
> * Fixed a similar bug in fmt-merge-msg.c.
> * Always invoke signature_check_clear() after check_signature().  The
>   check function may touch the signature_check structure on failure.

> [1] https://dev.gentoo.org/~mgorny/articles/attack-on-git-signature-verification.html
>
> Hans Jerry Illikainen (2):
>   t: increase test coverage of signature verification output
>   gpg-interface: prefer check_signature() for GPG verification
>
>  builtin/fmt-merge-msg.c  |  11 ++--
>  gpg-interface.c          |  97 +++++++++++++++++------------------
>  gpg-interface.h          |   9 ----
>  log-tree.c               |  34 ++++++-------
>  t/t4202-log.sh           | 106 +++++++++++++++++++++++++++++++++++++++
>  t/t6200-fmt-merge-msg.sh |  23 +++++++++
>  6 files changed, 202 insertions(+), 78 deletions(-)