Subject: Re: FS possible security exposure ?
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: regatta <regatta@gmail.com>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <5a3ed5650512250129t434d2b42kc1ebac1c5b308986@mail.gmail.com>
References: <5a3ed5650512250129t434d2b42kc1ebac1c5b308986@mail.gmail.com>
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Date: Sun, 25 Dec 2005 10:45:42 +0100
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On Sun, 2005-12-25 at 12:29 +0300, regatta wrote:
> Hi everyone,
> 
> I have a question regarding how Linux handle the files permission ,
> here is what I found
> 
> When logged on to a Linux workstation a user can edit a file (even if
> the file on an NFS-mounted NAS directory) if he has write access at
> the directory level, even if the file is owned by root (or any other
> user) and is read-only.

Since you do not explain how you performed the test, it is hard to
comment, but I don't see this behaviour you describe:

trondmy@lade test$ ls -al
total 12
drwxrwxrwx   2 root root 4096 2005-12-25 10:42 .
drwxrwxrwt  10 root root 4096 2005-12-25 10:41 ..
-rw-r--r--   1 root root    5 2005-12-25 10:42 test
trondmy@lade test$ cat >test
bash: test: Permission denied


If I use 'vi' to edit the file, then it can be modified, but the way vi
does that is to delete the old file, and create a new one with the same
name (and it will only do this if you use 'w!'). That should ordinarily
work on Solaris too.

Cheers,
  Trond

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