Authz File Administration Plugin
This plugin requires Trac 0.12 or later, and uses the repo names reported in the Version Control | Repositories admin panel to determine which repos to display when the show_all_repos option is set to false (default).
If you have any issues, create a new ticket.
Download the zipped source from here.
General instructions on installing Trac plugins can be found on the TracPlugins page.
It uses the authz_file setting from the [trac] section of your trac.ini file to find the svnauthz file.
There is a read_only_display option that, when enabled, prevents any changes to the authz_file being made. There is also a show_all_repos option to show all repo paths contained in the authz_file.
[components] svnauthz.* = enabled [svnauthzadmin] show_all_repos = true read_only_display = false