File::Policy(3) Site policy for file I/O functions


This defines the policy for file I/O with modules such as File::Slurp::WithinPolicy. The purpose is to allow systems administrators to define locations and restrictions for applications' file I/O and give app developers a policy to follow. Note that the module doesn't ENFORCE the policy - application developers can choose to ignore it (and systems administrators can choose not to install their applications if they do!).

You may control which policy gets applied by creating a File::Policy::Config module with an IMPLEMENTATION constant. You may write your own policy as a module within the File::Policy:: namespace.

By default (if no File::Policy::Config is present), the File::Policy::Default policy gets applied which doesn't impose any restrictions and provides reasonable default locations for temporary and log files.

The motivation behind this module was a standard, flexible approach to allow a site wide file policy to be defined. This will be most useful in large environments where a few sysadmins are responsible for code written by many other people. Simply ensuring that submitted code calls check_safe() ensures file access is sane, reducing the amount of effort required to do a security audit.

If your code is not security audit'd, or you are the only developer at your site, this might be overkill. However you may consider it good practise regardless and protection against paths in your code getting corrupted accidently or maliciously in the future.

There are two major benefits of using this module. One, sites that do implement a policy can more easily integrate your code in a standard way. If you have a file policy at your site, you can apply different policies (via File::Policy::Config) in different environments (production, integration test, development) and the appropriate policy is automatically applied without having to change your code or configs.