[K12OSN] Hand-in directory permissions

Steven Santos steven at simplycircus.com
Mon Mar 5 05:58:19 UTC 2007

I am just thinking out loud here...

Couldn't you create your directory and make your handin script (and perhaps
make it append the username of the person running the script to the file
name?), then instead of setting permissions in that script, run a cron job
every x minutes that changes the perms in that folder to root:teacher or
teacher:teacher or some such?.  You would still be vunerable between script
exicutions, but that should be OK.

Perhaps this would even be a good first utility for an Fl_student_tool type
program?  Extend the concept out so that teachers can set up drop boxes in
FL_TT, then let students select the drop and turn in the assignment via a
student tool type program?


Steven Santos
Director, Simply Circus, Inc.
Email: Steven at SimplyCircus.com
 Mail: 14 Pierrepont Road
       Newton, MA 02462
Phone: 617-527-0667
  Web: www.SimplyCircus.com

> -----Original Message-----
> From: k12osn-bounces at redhat.com [mailto:k12osn-bounces at redhat.com]On
> Behalf Of Robert Arkiletian
> Sent: Friday, March 02, 2007 1:08 AM
> To: Support list for open source software in schools.
> Subject: [K12OSN] Hand-in directory permissions
> I set up a drop box (hand in) dir by
> mkdir /home/inbox
> which now has owner and group set to root
> chmod 1773 /home/inbox
> which allows writing and sets the sticky bit for others.
> Even if they know the filename of another student they can't
> delete it BUT,
> they can
> cp /home/inbox/filename ~
> if they know the filename.
> Any way to prevent this?
> BTW my umask is the default 0002
> Possible solution?
> The only thing I can think of would be to write a tiny script (handin)
> like this
> cp -p $1 $2
> where $1 is the filename, $2 is the dropbox dir, command line args
> The handin script would have to have perm 2755 (setgid)
> and have owner root and group teacher.
> chmod 2775 handin
> chown root:teacher handin
> Then set the perm for the dropbox dir /home/inbox to 1730
> owned by root with group teacher.
> chmod 1730 /home/inbox
> chown root:teacher /home/inbox
> Then ask students to
> handin filename /home/inbox
> Haven't tested this yet, any suggestions?
> --
> Robert Arkiletian
> Eric Hamber Secondary, Vancouver, Canada
> Fl_TeacherTool http://www3.telus.net/public/robark/Fl_TeacherTool/
> C++ GUI tutorial http://www3.telus.net/public/robark/
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