Re: how to switch user

If you want to go from root to a normal user, that's easy. Just drop $EUID/$EGID to your real $UID/$GID (respecitivily):

use English; # For saner var names

# Do some stuff as root

$EUID = $UID;
$EGID = $GID;

# Now we're running as a normal user
[download]

Going up in privileges is harder. Probably the only realistic option is to execute the actual su (or maybe sudo) command and feed it the data to execute. (On GNU/Linux, you can pass in the data via the '-c' option to su, but this isn't portable).

----
I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated

Comment on Re: how to switch user Download Code

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Re: Re: how to switch user by bluto (Curate) on Jun 23, 2003 at 15:44 UTC
I'm not sure I understand your solution. If your script is running as root, chances are good that $UID and $EUID are already zero so your assignment won't do anything. Did you want to say something like this instead? `unless ($UID) { $EUID = $unpriviledged_uid; $EGID = $unpriviledged_gid; } ...` [download] Note that setting $EUID lets you act like the user, but on AIX at least it doesn't prevent you (or a child process you spawn) from resetting this back to zero and becomming root again, which can have security implications if you really want to run a child process unpriviledged. You can try setting $UID directly, but that isn't supported on some systems (e.g. AIX again). bluto	[reply] [d/l]

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Re: Re: how to switch user
by bluto (Curate) on Jun 23, 2003 at 15:44 UTC

unless ($UID) {
    $EUID = $unpriviledged_uid;
    $EGID = $unpriviledged_gid;
}
...
[download]

Note that setting $EUID lets you act like the user, but on AIX at least it doesn't prevent you (or a child process you spawn) from resetting this back to zero and becomming root again, which can have security implications if you really want to run a child process unpriviledged. You can try setting $UID directly, but that isn't supported on some systems (e.g. AIX again).

bluto

[reply]
[d/l]