Securely Allow PHP Read & Write Access to System Files

Question

I have not been able to find solid information on preferred (best practices) and/or secure methods to allow php to access config or other types of files on a linux server not contained in the public web directory or owned by the apache user so I'm hoping to find some answers here.

I am a fairly competent PHP programmer but am increasingly tasked with writing web applications (most of which are not publicly accessible via the web however) that require updating, changing or adding to config files or files generated by some service or application on the server.

For instance, I need to create a web interface that will view, add or remove entries from a /etc/mail/spamassassin/white-list.cf file owned by root.

Another scenario is that I need php to parse mime messages in /var/vmail that are owned by user vmail.

These are just a couple examples, there will be other files in locations owned by other processes/users. How can I write PHP applications that securely access and manipulate these files without opening security risks?

Answer 1

If I were needing to implement something like this, I would probably look at using something like sudo to fine-tune permissions. I'm not a Linux CLI expert, so I'm sure there are issues that I haven't taken into account when typing this out.

I would probably determine what tasks need to be done, and would write a separate script for each task that needs to be completed. Using sudo , I'd assign the necessary level of permissions for that script only.

Obviously, as the number of tasks increase, so would the complexity and the amount of work involved. I'm not sure how this would affect you at the moment.