setuid

chapod21

Hi

I created a simple script called test that creates a file in the sbin directory called testx. i changed the permissions on the script to 4755 and the owner to root. I try to run it as another user and the script cannot create the file. It works fine when the root user runs it. the permissions on the file are

-rwsr-xr-x 1 root root 18 Jan 18 19:59 test


Can some one tell me where i am going wrong

matrim

chapod21 wrote: »

Hi

I created a simple script called test that creates a file in the sbin directory called testx. i changed the permissions on the script to 4755 and the owner to root. I try to run it as another user and the script cannot create the file. It works fine when the root user runs it. the permissions on the file are

-rwsr-xr-x 1 root root 18 Jan 18 19:59 test


Can some one tell me where i am going wrong

I would assume the problem is because writing to the sbin directory would require the script to be run with root permissions, as sbin is only gives write permission to root.

chapod21

That would normally be the case but from what i have read if you use the setuid permissions the excutable script/file will be run as the owner of the file in this case root

http://en.wikipedia.org/wiki/Setuid

an example of this is the passwd command.

djmarkus

Scripts cannot be setuid'd. Only binaries.

chapod21

ok

thanks for the info

brianmc

djmarkus wrote: »

Scripts cannot be setuid'd. Only binaries.

Not certain about latest Linux versions but this can certainly be configured in some versions of Unix. It's only a recent* thing to disallow it.


*Recent meaning, only in the last couple of decades.


Edit: But of course it would still be a bad idea security-wise. The problem is that scripts are too easily hacked and so a script with suid is potentially a big hole.

djmarkus

Not without an unsupported patch.

The only way to run a script as another user is to use a binary wrapper.

sudo being a good example.

chapod21

Thanks for the information. It clears everything up