Generallly (assuming no exploit is found) it's not possible to escalate the privileges of an already running process, except via code that itself has kernel level access (running in ring 0 - this is presumably how systemd is able to do it). But from your own Python program running in user-land (as a script being interpreted by the python executable), you can only do this by starting a new process.

Fortunately, it's easy enough in Python to start new processes using the subprocess standard library. We can also use os.geteuid to determine Python's "effective user id" - i.e., 0 when the script is running as root, and nonzero otherwise. This allows us to create a script that spawns itself via sudo when not already running as root, and proceeds normally when it is. Something like:

#!/usr/bin/env python
# (or whatever other shebang is appropriate)

import os, sys, subprocess

# actual code to run as root, when this file is run as a script
def main(): 
    ...

if __name__ == '__main__':
    if os.geteuid() == 0:
        sys.exit(main())
    else:
        # assuming our script has chmod+x
        sys.exit(subprocess.call(['sudo', *sys.argv]))

Of course, the sudoers file can also be modified to allow running the script as root without a password. But for the use case of a script that only occasionally expects escalated privileges, it might be better to ask each time (the user likely wants a warning!) - and to defer the subprocess logic until it's actually necessary. This is tricky to set up; it may be easier to put the root-requiring logic in a separate script file (and perhaps use the standard output and/or error code of the root process to communicate back to the main program).

References:

• Elevate privileges of running process on Stack Overflow

• Write to a file with sudo privileges in Python on Stack Overflow

• How do I sudo a command in a script without being asked for a password? on Ask Ubuntu

posted 9 months ago

CC BY-SA 4.0

9mo ago

Karl Knechtel‭

2180 reputation 39 54 281 87