[K12OSN] Dropbox directory permissions
James P. Kinney III
jkinney at localnetsolutions.com
Mon Mar 5 03:10:55 UTC 2007
OK. A quick test was done.
Make the directory group writeable and set the file mask for that
directory to make all files -w- for the group. The teacher can still
read and move the files but students can only drop them. They can't copy
them or list them.
Anything a bunch of kids can dream up, a dedicated bunch of old farts
can squash.
:)
On Sun, 2007-03-04 at 20:59 -0600, Petre Scheie wrote:
> It's not as convenient, but perhaps you could give each student her/his
> own directory within /home/inbox, with permissions set to 770, and put
> the teacher into each student's primary group so the teacher can get to
> the files. Give each student's directory the same name as the student's
> ID, e.g., bob's directory would be /home/inbox/bob. Modify your script
> so that is automatically uses the caller's ID to specify the path to the
> directory. This way, only the student and the teacher have access to
> that student's work. It would be harder to hunt through all the
> directories for the students' work, but you could write a script that
> parses through all those directories and moves any files found to one
> folder in the teacher's $HOME. Give the teacher an icon to call it with
> sudo, call it something like "Gather up handed in assignments".
>
> HTH
>
> Petre
>
> Robert Arkiletian wrote:
> > mkdir /home/inbox
> > chmod 1773 /home/inbox (Not readable by others and sticky bit
> > prevents overwriting)
> >
> > But if a clever kid happens to know the filename of another kid
> >
> > cp /home/inbox/filename ~
> >
> > unfortunately works. Not good.
> > ==============================
> > My solution:
> > Write a 1 line bashscript /usr/bin/handin
> >
> > cp -p $1 /home/inbox/
> >
> > chgrp teacher /usr/bin/handin
> > chmod 2755 /usr/bin/handin (setgid escalate priviliges to teacher group)
> >
> > now
> >
> > chgrp teacher /home/inbox
> > chmod 1770 /home/inbox
> >
> > To hand-in a test students go
> > handin filename
> >
> > But it does not work. I get
> >
> > cp: cannot stat `/home/inbox/filename': Permission denied
> >
> > Why? Apparently, setgid cannot change the group of the process to one
> > which you don't already belong to. So I have to add the teacher group
> > to all students, which defeats the purpose. So much for privilege
> > escalation of setgid. I even tried using setuid.
> >
> > [root at server ~]# ls -ld /home/inbox/
> > drwxrwx--T 2 root root 4096 Mar 4 16:02 /home/inbox/
> > [root at server ~]# ls -l /usr/bin/handin
> > -rwsr-xr-x 1 root root 79 Mar 3 14:40 /usr/bin/handin
> >
> > I get the same stat Permission denied error. Any suggestions?
> >
> >
>
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--
James P. Kinney III
CEO & Director of Engineering
Local Net Solutions,LLC
770-493-8244
http://www.localnetsolutions.com
GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7
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