capng_clear - Linux

Overview

capng_clear is a command-line tool for manipulating capabilities in Linux using the newer capabilities API introduced in Linux 2.2. It allows you to clear all capabilities from a given process or thread, effectively reverting it to a state of minimal privilege.

Syntax

capng_clear [-h] [-g] [-p <pid>] [-t <tid>]

Options/Flags

  • -h, –help: Display usage information.
  • -g: Clear capabilities for all threads in the current process.
  • -p : Clear capabilities for the specified process ID (<pid>).
  • -t : Clear capabilities for the specified thread ID (<tid>).

Examples

Simple Usage:

Clear all capabilities from the current process:

capng_clear

Clearing Capabilities for a Specific Process:

Clear capabilities for a process with PID 1234:

capng_clear -p 1234

Clearing Capabilities for a Specific Thread:

Clear capabilities for a thread with TID 5678:

capng_clear -t 5678

Common Issues

  • Permission Denied: Ensure you have sufficient privileges (root or CAP_SETPCAP) to clear capabilities.
  • Invalid PID or TID: Verify that the provided process or thread ID is valid.

Integration

capng_clear can be used in combination with other commands to manage capabilities:

# Get current capabilities
getcapng -i <pid>

# Clear capabilities
capng_clear -p <pid>

# Set specific capabilities
setcapng -s <caplist> <pid>

Related Commands

  • getcapng: Get capabilities
  • setcapng: Set capabilities
  • capabilities: Display capabilities
  • cap_get_proc: Get capabilities for a specific file descriptor
  • cap_set_proc: Set capabilities for a specific file descriptor