These are the three conflicted changes from #4716:
* https://github.com/go-gitea/gitea/pull/31632
* https://github.com/go-gitea/gitea/pull/31688
* https://github.com/go-gitea/gitea/pull/31706
cc @earl-warren; as per discussion on https://github.com/go-gitea/gitea/pull/31632 this involves a small compatibility break (OIDC introspection requests now require a valid client ID and secret, instead of a valid OIDC token)
## Checklist
The [developer guide](https://forgejo.org/docs/next/developer/) contains information that will be helpful to first time contributors. There also are a few [conditions for merging Pull Requests in Forgejo repositories](https://codeberg.org/forgejo/governance/src/branch/main/PullRequestsAgreement.md). You are also welcome to join the [Forgejo development chatroom](https://matrix.to/#/#forgejo-development:matrix.org).
### Tests
- I added test coverage for Go changes...
- [ ] in their respective `*_test.go` for unit tests.
- [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
### Documentation
- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [ ] I did not document these changes and I do not expect someone else to do it.
### Release notes
- [ ] I do not want this change to show in the release notes.
- [ ] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.
<!--start release-notes-assistant-->
## Draft release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Breaking features
- [PR](https://codeberg.org/forgejo/forgejo/pulls/4724): <!--number 4724 --><!--line 0 --><!--description T0lEQyBpbnRlZ3JhdGlvbnMgdGhhdCBQT1NUIHRvIGAvbG9naW4vb2F1dGgvaW50cm9zcGVjdGAgd2l0aG91dCBzZW5kaW5nIEhUVFAgYmFzaWMgYXV0aGVudGljYXRpb24gd2lsbCBub3cgZmFpbCB3aXRoIGEgNDAxIEhUVFAgVW5hdXRob3JpemVkIGVycm9yLiBUbyBmaXggdGhlIGVycm9yLCB0aGUgY2xpZW50IG11c3QgYmVnaW4gc2VuZGluZyBIVFRQIGJhc2ljIGF1dGhlbnRpY2F0aW9uIHdpdGggYSB2YWxpZCBjbGllbnQgSUQgYW5kIHNlY3JldC4gVGhpcyBlbmRwb2ludCB3YXMgcHJldmlvdXNseSBhdXRoZW50aWNhdGVkIHZpYSB0aGUgaW50cm9zcGVjdGlvbiB0b2tlbiBpdHNlbGYsIHdoaWNoIGlzIGxlc3Mgc2VjdXJlLg==-->OIDC integrations that POST to `/login/oauth/introspect` without sending HTTP basic authentication will now fail with a 401 HTTP Unauthorized error. To fix the error, the client must begin sending HTTP basic authentication with a valid client ID and secret. This endpoint was previously authenticated via the introspection token itself, which is less secure.<!--description-->
<!--end release-notes-assistant-->
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4724
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Co-committed-by: Shivaram Lingamneni <slingamn@cs.stanford.edu>
The PKCE flow according to [RFC
7636](https://datatracker.ietf.org/doc/html/rfc7636) allows for secure
authorization without the requirement to provide a client secret for the
OAuth app.
It is implemented in Gitea since #5378 (v1.8.0), however without being
able to omit client secret.
Since #21316 Gitea supports setting client type at OAuth app
registration.
As public clients are already forced to use PKCE since #21316, in this
PR the client secret check is being skipped if a public client is
detected. As Gitea seems to implement PKCE authorization correctly
according to the spec, this would allow for PKCE flow without providing
a client secret.
Also add some docs for it, please check language as I'm not a native
English speaker.
Closes#17107Closes#25047
Change all license headers to comply with REUSE specification.
Fix#16132
Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
The OAuth spec [defines two types of
client](https://datatracker.ietf.org/doc/html/rfc6749#section-2.1),
confidential and public. Previously Gitea assumed all clients to be
confidential.
> OAuth defines two client types, based on their ability to authenticate
securely with the authorization server (i.e., ability to
> maintain the confidentiality of their client credentials):
>
> confidential
> Clients capable of maintaining the confidentiality of their
credentials (e.g., client implemented on a secure server with
> restricted access to the client credentials), or capable of secure
client authentication using other means.
>
> **public
> Clients incapable of maintaining the confidentiality of their
credentials (e.g., clients executing on the device used by the resource
owner, such as an installed native application or a web browser-based
application), and incapable of secure client authentication via any
other means.**
>
> The client type designation is based on the authorization server's
definition of secure authentication and its acceptable exposure levels
of client credentials. The authorization server SHOULD NOT make
assumptions about the client type.
https://datatracker.ietf.org/doc/html/rfc8252#section-8.4
> Authorization servers MUST record the client type in the client
registration details in order to identify and process requests
accordingly.
Require PKCE for public clients:
https://datatracker.ietf.org/doc/html/rfc8252#section-8.1
> Authorization servers SHOULD reject authorization requests from native
apps that don't use PKCE by returning an error message
Fixes#21299
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
According to the OAuth spec
https://datatracker.ietf.org/doc/html/rfc6749#section-6 when "Refreshing
an Access Token"
> The authorization server MUST ... require client authentication for
confidential clients
Fixes#21418
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Shivaram Lingamneni