weird permitions

Oliver Fromme olli at
Wed Nov 29 09:19:05 PST 2006

Stefan Lambrev wrote:
 > Can someone explain to me why next can happened on freebsd:
 > 1. add 2 users in same group - user test and test-ro in group test
 > 2. as user test: cd /home/test ; mkdir test; chmod 775 test; echo 
 > "asdasd" > ~/test/

What was your umask?  I assume 022, i.e. the file was
created with mdoe 644.

 > 3. su - test-ro ; cd /home/test; vim - make changes; force save (:x!)

I suspect that vim -- upon force save -- deleted the
original file, which is perfectly possible because the
test-ro user had write permission to the directory.

Then vim created a new file with the same name, which
is again perfectly possible because of the writability
of the directory.  The new file belongs to the test-ro
user, of course.

So ...

 > ls -l
 > total 2
 > -rw-r--r--  1 test-ro  test  10 Nov 29 18:19 (how is that possible ?)
 > back "su - test" and try to edit this file - impossible!

.. That's to be expected.

 > I do not know what the RFC says about it, but it is ultra weird for me
 > that such ownership takeover is possible.

It is standard and perfectly correct behaviour.

There was no "ownership takeover".  One file was deleted,
and a new file was created, all allowed by the given

Best regards

Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
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