git/Documentation/howto/coordinate-embargoed-releases.txt

Content-type: text/asciidoc
Abstract: When a critical vulnerability is discovered and fixed, we follow this
 script to coordinate a public release.

How we coordinate embargoed releases
====================================

To protect Git users from critical vulnerabilities, we do not just release
fixed versions like regular maintenance releases. Instead, we coordinate
releases with packagers, keeping the fixes under an embargo until the release
date. That way, users will have a chance to upgrade on that date, no matter
what Operating System or distribution they run.

Open a Security Advisory draft
------------------------------

The first step is to https://github.com/git/git/security/advisories/new[open an
advisory]. Technically, it is not necessary, but it is convenient and saves a
bit of hassle. This advisory can also be used to obtain the CVE number and it
will give us a private fork associated with it that can be used to collaborate
on a fix.

Release date of the embargoed version
-------------------------------------

If the vulnerability affects Windows users, we want to have our friends over at
Visual Studio on board. This means we need to target a "Patch Tuesday" (i.e. a
second Tuesday of the month), at the minimum three weeks from heads-up to
coordinated release.

If the vulnerability affects the server side, or can benefit from scans on the
server side (i.e. if `git fsck` can detect an attack), it is important to give
all involved Git repository hosting sites enough time to scan all of those
repositories.

Notifying the Linux distributions
---------------------------------

At most two weeks before release date, we need to send a notification to
distros@vs.openwall.org, preferably less than 7 days before the release date.
This will reach most (all?) Linux distributions. See an example below, and the
guidelines for this mailing list at
https://oss-security.openwall.org/wiki/mailing-lists/distros#how-to-use-the-lists[here].

Once the version has been published, we send a note about that to oss-security.
As an example, see https://www.openwall.com/lists/oss-security/2019/12/13/1[the
v2.24.1 mail];
https://oss-security.openwall.org/wiki/mailing-lists/oss-security[Here] are
their guidelines.

The mail to oss-security should also describe the exploit, and give credit to
the reporter(s): security researchers still receive too little respect for the
invaluable service they provide, and public credit goes a long way to keep them
paid by their respective organizations.

Technically, describing any exploit can be delayed up to 7 days, but we usually
refrain from doing that, including it right away.

As a courtesy we typically attach a Git bundle (as `.tar.xz` because the list
will drop `.bundle` attachments) in the mail to distros@ so that the involved
parties can take care of integrating/backporting them. This bundle is typically
created using a command like this:

	git bundle create cve-xxx.bundle ^origin/master vA.B.C vD.E.F
	tar cJvf cve-xxx.bundle.tar.xz cve-xxx.bundle

Example mail to distros@vs.openwall.org
---------------------------------------

....
To: distros@vs.openwall.org
Cc: git-security@googlegroups.com, <other people involved in the report/fix>
Subject: [vs] Upcoming Git security fix release

Team,

The Git project will release new versions on <date> at 10am Pacific Time or
soon thereafter. I have attached a Git bundle (embedded in a `.tar.xz` to avoid
it being dropped) which you can fetch into a clone of
https://github.com/git/git via `git fetch --tags /path/to/cve-xxx.bundle`,
containing the tags for versions <versions>.

You can verify with `git tag -v <tag>` that the versions were signed by
the Git maintainer, using the same GPG key as e.g. v2.24.0.

Please use these tags to prepare `git` packages for your various
distributions, using the appropriate tagged versions. The added test cases
help verify the correctness.

The addressed issues are:

<list of CVEs with a short description, typically copy/pasted from Git's
release notes, usually demo exploit(s), too>

Credit for finding the vulnerability goes to <reporter>, credit for fixing
it goes to <developer>.

Thanks,
<name>

....

Example mail to oss-security@lists.openwall.com
-----------------------------------------------

....
To: oss-security@lists.openwall.com
Cc: git-security@googlegroups.com, <other people involved in the report/fix>
Subject: git: <copy from security advisory>

Team,

The Git project released new versions on <date>, addressing <CVE>.

All supported platforms are affected in one way or another, and all Git
versions all the way back to <version> are affected. The fixed versions are:
<versions>.

Link to the announcement: <link to lore.kernel.org/git>

We highly recommend to upgrade.

The addressed issues are:
* <list of CVEs and their explanations, along with demo exploits>

Credit for finding the vulnerability goes to <reporter>, credit for fixing
it goes to <developer>.

Thanks,
<name>
....