RDFLib is designed to access arbitrary network and file resources, in some cases these are directly requested resources, in other cases they are indirectly referenced resources.
An example of where indirect resources are accessed is JSON-LD processing, where
network or file resources referenced by
@context values will be loaded and
RDFLib also supports SPARQL, which has federated query capabilities that allow queries to query arbitrary remote endpoints.
If you are using RDFLib to process untrusted documents or queries you should take measures to restrict file and network access.
Some measures that can be taken to restrict file and network access are:
Of these, operating system security measures are recommended. The other measures work, but they are not as effective as operating system security measures, and even if they are used they should be used in conjunction with operating system security measures.
Operating System Security Measures¶
Most operating systems provide functionality that can be used to restrict network and file access of a process.
Some examples of these include:
Open Container Initiative (OCI) Containers (aka Docker containers).
Most OCI runtimes provide mechanisms to restrict network and file access of containers. For example, using Docker, you can limit your container to only being access files explicitly mapped into the container and only access the network through a firewall. For more information refer to the documentation of the tool you use to manage your OCI containers:
firejail can be used to sandbox a process on Linux and restrict its network and file access.
File and network access restrictions.
Most operating systems provide a way to restrict operating system users to only being able to access files and network resources that are explicitly allowed. Applications that process untrusted input could be run as a user with these restrictions in place.
Many other measures are available, however, listing them outside the scope of this document.
Of the listed measures OCI containers are recommended. In most cases, OCI containers are constrained by default and can’t access the loopback interface and can only access files that are explicitly mapped into the container.
Python Runtime Audit Hooks¶
From Python 3.8 onwards, Python provides a mechanism to install runtime audit hooks that can be used to limit access to files and network resources.
The runtime audit hook system is described in more detail in PEP 578 – Python Runtime Audit Hooks.
Runtime audit hooks can be installed using the sys.addaudithook function, and will then get called when audit events occur. The audit events raised by the Python runtime and standard library are described in Python’s audit events table.
urllib.request.urlopen for HTTP, HTTPS and other network access,
and this function raises a
urllib.Request audit event. For file access,
open, which raises an
open audit event.
Users of RDFLib can install audit hooks that react to these audit events and raises an exception when an attempt is made to access files or network resources that are not explicitly allowed.
RDFLib’s test suite includes tests which verify that audit hooks can block access to network and file resources.
RDFLib also includes an example that shows how runtime audit hooks can be
used to restrict network and file access in
Custom URL Openers¶
RDFLib uses the
urllib.request.urlopen for HTTP, HTTPS and other network
access. This function will use a
urllib.request.OpenerDirector installed with
urllib.request.install_opener to open the URLs.
Users of RDFLib can install a custom URL opener that raise an exception when an attempt is made to access network resources that are not explicitly allowed.
RDFLib’s test suite includes tests which verify that custom URL openers can be used to block access to network resources.
RDFLib also includes an example that shows how a custom opener can be used to
restrict network access in