Mitigate Security vulnerability in the git hook feature

[Niklas974]

Git hooks are a dangerous feature that allows users with the relevant privilege to perform remote code execution on the host system and elevate their privileges to gitea administrator. Details are provided in the vulnerability report.

This pull request thus:

• disables the git hook feature by default
• improves documentation on it
• Extends the warning tooltip that is shown when giving git hook privileges to

The problem was first reported to the gitea security team in April who released a patch. In our opinion this patch only partly mitigates the vulnerability, though. For details see the report linked above.

[Niklas974]

Thanks for merging this quickly!

I suggest to add a warning for the next release. Disabling the git hook feature by default will affect the settings on existing gitea instances, admins of existing gitea instances should be informed about the issue to be able to change the setting on their instance if needed.

[lunny]

@Niklas974 All break changes will be displayed on release notes.

[Niklas974]

@Niklas974 All break changes will be displayed on release notes.

The change in the default config in this PR (DISABLE_GIT_HOOKS = true) should only affect new installations for gitea. Thus in existing installations, git hooks will stay as they were (mostly enabled, I guess). These existing installations are still endangered, thus I think the admins should be warned in the release notes.

Or am I missing something, here?

[lafriks]

depends on what you have in your app.ini. If you have no DISABLE_GIT_HOOKS entry in app.ini it will default to new value than.