understanding the suid bit

[bobbybobbertson]

I'm trying to understand the suid bit. I want a group to be able to run a script with the permissions of the owner.

I have a script called test.pl with the following permissions:

-rwxr-sr-x 1 bob home 45 Dec 4 13:37 test.pl

When I try to run this as jim, I get:
%jim: ./test.pl
Can't do setuid

Why cat jim run this script. Both bob and jim are in the same group 'home'

 

[bobbybobbertson]

for correctness, i should have said the set gid bit.

 

[ifincham]

Hi,

In general linux ignores those bits - see -->

http://www.linuxdoc.org/HOWTO/Secure-Programs-HOWTO/avoid-setuid.html

With perl you can do it if you use the -s flag on the #! line inside the script :

#!/usr/bin/perl -s

Setuid is used to run with the owner's permissions :

chmod 4755 test.pl

-rws--x--x 1 bob home 45 Dec 4 13:37 test.pl

The way you have it above is with group id which is really used to ensure that everything in a directory retains the group id of the directory irrespective of who created it.

Regards

 

[bobbybobbertson]

ok, I switched it to what you said, but I still get that error!!!

 

[ifincham]

Hi,



Actually it should have been -s -T -U but I have to say I can't seem to get it to work either. It may be the way that redhat built the perl rpm. I'll let you know if I crack it...



If you want to run something as a regular user with root's (or anyone else's) permissions it might be better and more secure to use 'sudo' instead. See 'man sudo' .



Regards

 

[bobbybobbertson]

i don't have 'sudo' for some reason. i have red hat. does that come with red hat?>

 

[ifincham]

Hi,





Yes sudo is supplied by redhat in a rpm of the same name. Maybe you never installed it. I don't know what version of redhat you have but you should be able to use one of these :




ftp://rpmfind.net/linux/redhat/7.2/en/os/i386/RedHat/RPMS/sudo-1.6.3p7-2.i386.rpm


(7.2)


ftp://rpmfind.net/linux/redhat/7.1/en/os/i386/RedHat/RPMS/sudo-1.6.3p6-1.i386.rpm


(7.1)


ftp://rpmfind.net/linux/redhat/updates/7.0/en/os/i386/sudo-1.6.3p6-1.i386.rpm


(7.0)


ftp://rpmfind.net/linux/redhat/6.2/en/powertools/i386/i386/sudo-1.6.1-1.i386.rpm


(6.2)





Just download somewhere and install as root with :





rpm -Uvh sudo*.rpm





The sudo home page is here -->

http://www.courtesan.com/sudo/

.





Regards