pax11publish

pax11publish [options]

--help
    Display help message and exit.

--version
    Output version information and exit.

The pax11publish command is a specialized utility designed to work within a PaX or grsecurity hardened Linux environment. Its primary purpose is to publish critical X11 display and related environment variables (like $DISPLAY) into a shared memory segment.

This information is then accessible to other PaX-related tools, such as paxrat, which might need to connect to the X server from a highly restricted or chrooted environment. By providing a secure and controlled method for sharing X11 session details, pax11publish helps in maintaining the integrity and security of applications running under PaX protections, especially those interacting with the graphical user interface.

pax11publish is a highly specialized command primarily found in systems utilizing the PaX or grsecurity security enhancements for the Linux kernel. It is not a standard utility on most general-purpose Linux distributions.

Its functionality is dependent on the presence of a PaX-enabled kernel and related user-space tools. Without this specific security infrastructure, the command is likely to be absent or non-functional.

The primary consumer of information published by pax11publish is the paxrat utility. paxrat is designed to run applications in a highly restricted environment, often with chroot and other security measures. For these applications to interact with the X server, they need access to the $DISPLAY variable and potentially other X11-related environment variables. pax11publish provides this information via a shared memory segment, allowing paxrat to securely transfer it to the sandboxed application.

pax11publish writes the X11 environment variables (e.g., $DISPLAY, $XAUTHORITY) to a specific shared memory segment. The name or ID of this segment is typically predefined or configured by the PaX/grsecurity setup. This allows other PaX tools with appropriate permissions to read this information without relying on less secure methods like passing environment variables directly, which might be stripped in hardened environments.

The PaX project was initiated in 2000 as a pioneering effort to provide memory protection features for Linux, including Address Space Layout Randomization (ASLR), Non-Executable (NX) pages, and other exploit mitigation techniques. grsecurity later integrated many of these PaX features, along with additional hardening.

pax11publish emerged as a utility within this ecosystem to address the specific challenge of securely sharing X11 session details with highly restricted processes (like those run by paxrat) without compromising the overall system's security posture. Its development is tied to the evolution of the PaX/grsecurity project and its focus on fine-grained application hardening.

paxrat(1), paxctl(8), chpax(1), X(7)