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tailscale/cmd/pgproxy
Will Norris 3ec5be3f51 all: remove AUTHORS file and references to it
This file was never truly necessary and has never actually been used in
the history of Tailscale's open source releases.

A Brief History of AUTHORS files
---

The AUTHORS file was a pattern developed at Google, originally for
Chromium, then adopted by Go and a bunch of other projects. The problem
was that Chromium originally had a copyright line only recognizing
Google as the copyright holder. Because Google (and most open source
projects) do not require copyright assignemnt for contributions, each
contributor maintains their copyright. Some large corporate contributors
then tried to add their own name to the copyright line in the LICENSE
file or in file headers. This quickly becomes unwieldy, and puts a
tremendous burden on anyone building on top of Chromium, since the
license requires that they keep all copyright lines intact.

The compromise was to create an AUTHORS file that would list all of the
copyright holders. The LICENSE file and source file headers would then
include that list by reference, listing the copyright holder as "The
Chromium Authors".

This also become cumbersome to simply keep the file up to date with a
high rate of new contributors. Plus it's not always obvious who the
copyright holder is. Sometimes it is the individual making the
contribution, but many times it may be their employer. There is no way
for the proejct maintainer to know.

Eventually, Google changed their policy to no longer recommend trying to
keep the AUTHORS file up to date proactively, and instead to only add to
it when requested: https://opensource.google/docs/releasing/authors.
They are also clear that:

> Adding contributors to the AUTHORS file is entirely within the
> project's discretion and has no implications for copyright ownership.

It was primarily added to appease a small number of large contributors
that insisted that they be recognized as copyright holders (which was
entirely their right to do). But it's not truly necessary, and not even
the most accurate way of identifying contributors and/or copyright
holders.

In practice, we've never added anyone to our AUTHORS file. It only lists
Tailscale, so it's not really serving any purpose. It also causes
confusion because Tailscalars put the "Tailscale Inc & AUTHORS" header
in other open source repos which don't actually have an AUTHORS file, so
it's ambiguous what that means.

Instead, we just acknowledge that the contributors to Tailscale (whoever
they are) are copyright holders for their individual contributions. We
also have the benefit of using the DCO (developercertificate.org) which
provides some additional certification of their right to make the
contribution.

The source file changes were purely mechanical with:

    git ls-files | xargs sed -i -e 's/\(Tailscale Inc &\) AUTHORS/\1 contributors/g'

Updates #cleanup

Change-Id: Ia101a4a3005adb9118051b3416f5a64a4a45987d
Signed-off-by: Will Norris <will@tailscale.com>
2 days ago
..
README.md cmd/pgproxy: link to blog post at the top. 3 years ago
pgproxy.go all: remove AUTHORS file and references to it 2 days ago

README.md

pgproxy

The pgproxy server is a proxy for the Postgres wire protocol. Read more in our blog post about it!

The proxy runs an in-process Tailscale instance, accepts postgres client connections over Tailscale only, and proxies them to the configured upstream postgres server.

This proxy exists because postgres clients default to very insecure connection settings: either they "prefer" but do not require TLS; or they set sslmode=require, which merely requires that a TLS handshake took place, but don't verify the server's TLS certificate or the presented TLS hostname. In other words, sslmode=require enforces that a TLS session is created, but that session can trivially be machine-in-the-middled to steal credentials, data, inject malicious queries, and so forth.

Because this flaw is in the client's validation of the TLS session, you have no way of reliably detecting the misconfiguration server-side. You could fix the configuration of all the clients you know of, but the default makes it very easy to accidentally regress.

Instead of trying to verify client configuration over time, this proxy removes the need for postgres clients to be configured correctly: the upstream database is configured to only accept connections from the proxy, and the proxy is only available to clients over Tailscale.

Therefore, clients must use the proxy to connect to the database. The client<>proxy connection is secured end-to-end by Tailscale, which the proxy enforces by verifying that the connecting client is a known current Tailscale peer. The proxy<>server connection is established by the proxy itself, using strict TLS verification settings, and the client is only allowed to communicate with the server once we've established that the upstream connection is safe to use.

A couple side benefits: because clients can only connect via Tailscale, you can use Tailscale ACLs as an extra layer of defense on top of the postgres user/password authentication. And, the proxy can maintain an audit log of who connected to the database, complete with the strongly authenticated Tailscale identity of the client.