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From: bzs%bostonu.csnet@csnet-relay.arpa (Barry Shein)
Newsgroups: net.unix-wizards
Subject: 4.2bsd Oddity (BUG?)
Message-ID: <721@brl-tgr.ARPA>
Date: Mon, 16-Dec-85 09:56:15 EST
Article-I.D.: brl-tgr.721
Posted: Mon Dec 16 09:56:15 1985
Date-Received: Wed, 18-Dec-85 02:17:30 EST
Sender: news@brl-tgr.ARPA
Lines: 39


Here's one a faculty member pointed out, I suspect it was in
relation to one of his courses:

He makes a directory, call it 'gumby' and makes it 777 (world write
is what's important here.) Someone else comes along and creates
a directory 'gumby/pokey' (say protection 755) and puts a file (or
more) into it, call it gumby/pokey/foo.

At that point he can no longer remove the directory gumby because
it is not empty. 'rm -r' et al don't help because the directory
gumby/pokey is owned by the other user and does not allow him to
delete the file gumby/pokey/foo, nor chmod it. I think he is stuck
(obviously the student or myself can remove it.)

If I recall correctly, what he does is create a subdir for his students.
His students then create a subdir for themselves and put homeworks into
it, so the way he got there is fairly reasonable (it is a high level,
small course so security is not a big issue here I suspect, no need to
belabor that.)

Other than the obvious 'don't do it that way' am I missing something?
Is this a bug? Anyone want to suggest a fix?

	-Barry Shein, Boston University

P.S. If you think it's incredibly obvious you may have missed the
point, try the following first from root:

mkdir gumby
chown yournonprivacct gumby
chmod 777 gumby
mkdir gumby/pokey
chmod 755 gumby/pokey
echo hello > gumby/pokey/foo

Now make yourself non-prived (I just 'suspend' the 'su'd csh back to bzs)
and try to remove everything. pokey and foo should be owned by root
(or some other account.)