I have a program which runs a bunch of tasks as root at launch. After that it needs to drop to a different user. How can that be done?
And just wondering, is it possible to reacquire root without relaunching the program?
+3
A:
The short answer is to use the setuid() function.
It is not possible to reacquire root privileges after switching to a non-root user.
Greg Hewgill
2010-08-08 21:20:27
"It is not possible to reacquire root privileges after switching to a non-root user." As a matter of fact, this is *the whole point* of dropping superuser privs. You want to limit the impact of any security holes in your program. If you could re-escalate, so could any exploit targeting your program...
sleske
2010-08-08 21:34:58
@sleske: actually, if your effective UID is not root, and the implementation supports _POSIX_SAVED_IDS, you can regain the original effective UID.
ninjalj
2010-08-08 21:38:58