A security vulnerability that was fixed in #9840 had the potential to corrupt the `authorized_keys` file that Forgejo is managing to allow ssh access. In the event that it was corrupted, the existing behaviour of Forgejo is to maintain the contents that it finds in the `authorized_keys` file, potentially making an exploit of a Forgejo server persistent despite attempts to rewrite the key file.
This feature adds a new layer of security resiliency in order to prevent persistent ssh key corruption. When Forgejo starts up, if relevant, Forgejo will read the `authorized_keys` file and validate the file's contents. If any keys are found in the file that are not expected, then Forgejo will terminate its startup in order to signal to the server administrator that a critical security risk is present that must be addressed:
```
2025/11/07 10:13:50 modules/ssh/init.go:86:Init() [F] An unexpected ssh public key was discovered. Forgejo will shutdown to require this to be fixed. Fix by either:
Option 1: Delete the file /home/forgejo/.ssh/authorized_keys, and Forgejo will recreate it with only expected ssh public keys.
Option 2: Permit unexpected keys by setting [server].SSH_ALLOW_UNEXPECTED_AUTHORIZED_KEYS=true in Forgejo's config file.
Unexpected key on line 1 of /home/forgejo/.ssh/authorized_keys
Unexpected key on line 2 of /home/forgejo/.ssh/authorized_keys
Unexpected key on line 3 of /home/forgejo/.ssh/authorized_keys
Unexpected key on line 4 of /home/forgejo/.ssh/authorized_keys
Unexpected key on line 5 of /home/forgejo/.ssh/authorized_keys
```
As noted in the log message, the server administrator can address this problem in one of two ways:
- If they delete the file that contains the unexpected keys, Forgejo will regenerate it containing only the expected keys from the Forgejo database.
- If they would like to run their server with ssh keys that are not managed by Forgejo (for example, if they're reusing a `git` ssh user that is accessed through `git@server` and does not invoke Forgejo's ssh handlers), then they can disable the new security check by setting `[server].SSH_ALLOW_UNEXPECTED_AUTHORIZED_KEYS = true` in their `app.ini`.
**This is a breaking change**: the default behaviour is to be restrictive in the contents of `authorized_keys` in order to ensure that server administrators with unexpected keys in `authorized_keys` are aware of those keys.
If `SSH_ALLOW_UNEXPECTED_AUTHORIZED_KEYS=false`, then the behaviour when Forgejo rewrites the `authorized_keys` file is changed to not maintain any unexpected keys in the file. If the value is `true`, then the old behaviour is retained.
The `doctor check` subcommand is updated to use the new validity routines:
```
[4] Check if OpenSSH authorized_keys file is up-to-date
- [E] Unexpected key on line 1 of /home/forgejo/.ssh/authorized_keys
- [E] Key in database is not present in /home/forgejo/.ssh/authorized_keys: ...
- [E] authorized_keys file "/home/forgejo/.ssh/authorized_keys" contains validity errors.
Regenerate it with:
"forgejo admin regenerate keys"
or
"forgejo doctor check --run authorized-keys --fix"
ERROR
```
## Checklist
The [contributor guide](https://forgejo.org/docs/next/contributor/) 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...
- [x] in their respective `*_test.go` for unit tests.
- [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
- [ ] in `web_src/js/*.test.js` if it can be unit tested.
- [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).
### Documentation
- [x] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- **Documentation updates required**; pending initial reviews of 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.
- [x] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10010
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: mfenniak <mfenniak@noreply.codeberg.org>
Co-committed-by: mfenniak <mfenniak@noreply.codeberg.org>
This prevents the disk from overflowing with auth keys file
Fixes#17117
## ⚠️ BREAKING
This changes the default option for creating a backup of the authorized
key file when an update is made to default to false.
Without this patch, the setting SSH.StartBuiltinServer decides whether
the native (Go) implementation is used rather than calling 'ssh-keygen'.
It's possible for 'using ssh-keygen' and 'using the built-in server' to
be independent.
In fact, the gitea rootless container doesn't ship ssh-keygen and can be
configured to use the host's SSH server - which will cause the public
key parsing mechanism to break.
This commit changes the decision to be based on SSH.KeygenPath instead.
Any existing configurations with a custom KeygenPath set will continue
to function. The new default value of '' selects the native version. The
downside of this approach is that anyone who has relying on plain
'ssh-keygen' to have special properties will now be using the native
version instead.
I assume the exec-variant is only there because /x/crypto/ssh didn't
support ssh-ed25519 until 2016. I don't see any other reason for using
it so it might be an acceptable risk.
Fixes#23363
EDIT: this message was garbled when I tried to get the commit
description back in.. Trying to reconstruct it:
## ⚠️ BREAKING ⚠️ Users who don't have SSH.KeygenPath
explicitly set and rely on the ssh-keygen binary need to set
SSH.KeygenPath to 'ssh-keygen' in order to be able to continue using it
for public key parsing.
There was something else but I can't remember at the moment.
EDIT2: It was about `make test` and `make lint`. Can't get them to run.
To reproduce the issue, I installed `golang` in `docker.io/node:16` and
got:
```
...
go: mvdan.cc/xurls/v2@v2.4.0: unknown revision mvdan.cc/xurls/v2.4.0
go: gotest.tools/v3@v3.4.0: unknown revision gotest.tools/v3.4.0
...
go: gotest.tools/v3@v3.0.3: unknown revision gotest.tools/v3.0.3
...
go: error loading module requirements
```
Signed-off-by: Leon M. Busch-George <leon@georgemail.eu>
Some bugs caused by less unit tests in fundamental packages. This PR
refactor `setting` package so that create a unit test will be easier
than before.
- All `LoadFromXXX` files has been splited as two functions, one is
`InitProviderFromXXX` and `LoadCommonSettings`. The first functions will
only include the code to create or new a ini file. The second function
will load common settings.
- It also renames all functions in setting from `newXXXService` to
`loadXXXSetting` or `loadXXXFrom` to make the function name less
confusing.
- Move `XORMLog` to `SQLLog` because it's a better name for that.
Maybe we should finally move these `loadXXXSetting` into the `XXXInit`
function? Any idea?
---------
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>
