suid problems

[Nicolas Williams]

On Fri, Feb 15, 2002 at 01:29:31PM -0500, James M Craig wrote:
> 	The first problem that I am faced with is dealing with
> scripts that are suid and access files over nfs.  The way things work
> now, a student runs a program to submit their coursework.  This program
> is suid to a 'submit' uid, and this submit uid is allowed to dump files
> into the grader accounts, compile and run the projects, and provide
> feedback to the students.

Create a students-writeable, students-not-readable submission directory
and use that instead of a suid program.

> 	In my test Realm, I have noticed that if I run a program that is suid
> to another user, and attempt to write a file to an NFS mounted directory
> (exported with sec=krb5i), it doesn't work.  My understanding is that
> the process, which is now owned by someone else, does NOT have any
> credentials to manipulate the NFS mounted directory...

Right.

> 	Has anyone else had to deal with this?  What sort of changes are
> necessary?

See above. The good news is that with SecureNFS the server does all the
authorization checks, so you can rely on your files'/directories' ACLs.

> Jim Craig
> jmc at cs.rit.edu


Cheers,

Nico
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