cap_copy_ext - Linux

Overview

cap_copy_ext is a command-line tool for copying extended capabilities from one file or directory to another. Extended capabilities are special privileges that can be assigned to processes or files, allowing them to perform privileged actions. This command is primarily used to grant or revoke extended capabilities from files or directories, enhancing the security of the system by implementing the principle of least privilege.

Syntax

cap_copy_ext [options] <operation> <source> <destination>

Options

  • -p, –pread: Preserve the capabilities of the destination file instead of overwriting them.
  • -f, –force: Overwrite the existing capabilities of the destination file without prompting.
  • -v, –verbose: Print verbose output.
  • -h, –help: Print help information.
  • -V, –version: Print version information.

Operations

  • a: Copy all capabilities.
  • s: Copy only the set capabilities.
  • d: Copy only the drop capabilities.

Arguments

  • : The source file or directory from which capabilities are copied.
  • : The destination file or directory to which capabilities are copied.

Examples

Granting Capabilities to a File

cap_copy_ext a /path/to/source /path/to/destination

This command will copy all extended capabilities from /path/to/source to /path/to/destination.

Revoking Capabilities from a Directory

cap_copy_ext d /path/to/source /path/to/destination

This command will remove all drop capabilities from /path/to/source and apply them to /path/to/destination.

Preserving Destination Capabilities

cap_copy_ext -p a /path/to/source /path/to/destination

This command will add the capabilities from /path/to/source to /path/to/destination while preserving any existing capabilities on the destination.

Common Issues

Permission Denied

Ensure that the user running the command has sufficient permissions to modify the capabilities of both the source and destination files or directories.

Invalid Operation

The specified operation must be either ‘a’, ‘s’, or ‘d’.

No Capabilities to Copy

If the source file or directory does not have any extended capabilities, the command will not perform any action.

Integration

cap_copy_ext can be combined with other tools for advanced security tasks:

  • chmod: To change file permissions and capabilities.
  • lscap: To list the extended capabilities of files and directories.
  • setcap: To set extended capabilities on files and directories.

Related Commands

  • getcap: Retrieves the capabilities of a file or directory.
  • setcap: Sets the capabilities of a file or directory.
  • capset: Changes the capabilities of a running process.