Auditing Active io_uring File Descriptors and SQPOLL via Procfs

This shell script iterates through the virtual procfs directory structure to identify processes holding open anon_inode:[io_uring] file descriptors and extracts detailed subsystem parameters from the kernel. Internally, when an application calls io_uring_setup, the kernel returns a file descriptor pointing to an anonymous inode that wraps the Submission Queue (SQ) and Completion Queue (CQ) ring buffers. Querying /proc/[pid]/fdinfo/[fd] causes the kernel to export ring metadata, including SqThread, SqThreadCpu, UserTable, and memory page counts directly from the kernel ring context.

Systems engineers use this inspection pattern during live incident response and performance optimization exercises on storage-intensive servers. It enables precise accounting of which processes are utilizing submission queue polling (SQPOLL), mapping kernel worker threads to physical CPU cores, and detecting potential resource leaks caused by orphaned io_uring rings in long-running daemon processes.

Executing this pipeline incurs minimal overhead as procfs reads only format internal kernel structs on demand. However, scanning thousands of file descriptors on high-density production nodes can cause transient CPU utilization spikes. Security teams must ensure proper permissions when inspecting non-owned process structures, as unprivileged users will encounter permission denied errors when attempting to access fdinfo trees belonging to other user accounts.

> System.Execute()

for fd in /proc/[0-9]*/fd/*; do link=$(readlink "$fd" 2>/dev/null); if [ "$link" = "anon_inode:[io_uring]" ]; then pid=$(echo "$fd" | cut -d/ -f3); echo "PID: $pid | FD: $(basename "$fd")"; cat "/proc/$pid/fdinfo/$(basename "$fd")" 2>/dev/null; fi; done

> Architecture & Security Context

Verified for Valters IT Hub. When deploying this configuration in a production homelab or enterprise environment, ensure that you monitor system resources and implement strict access controls. Administrator privileges are required.

ID: VALTERSIT-2338E8A8B1B4