Best practice for Web-Interface modifying config-file

Question

For a new project, I have to write a webinterface, which has the capability of modifying a configuration file. The system this will run on is a standard debian installation with apache and php5. The only idea I came up with so far, is to write small c programms, setting the setuid bit to root and supplying the string to be inserted in the config file as a parameter. However I really have a bad feeling about this, since I would rather avoid any setuid programms in my system, for security reasons. Unfortunatelly, the programm to witch the config file belongs refuses to start, if the config file hasn't exclusive root permissions.

How do projects like webmin adress this issue? I would really appreciate some best-practice tipps, of how to implement this.

Thanks in advance

Answer 1

You don't need the Web server to write this file at all. In fact, that just seems like a very bad idea altogether. I'm assuming that this is an Intranet-only website? IF it were me I'd simply store the public key in a database and later have a cron job script come through and validate the certificate and then insert it. Sure, the script has to run as root (stick it in the root's crontab) but you don't have to lose sleep about your webserver writing to files with root permissions. :)