Re: buglet in ext2 sticky bit?

Frank van Maarseveen (F.vanMaarseveen@inter.NL.net)
Sun, 24 Oct 1999 23:57:37 +0200

On Sun, Oct 24, 1999 at 10:06:15PM +0100, Matthew Kirkwood wrote:
> On Sun, 24 Oct 1999, Jan Kara wrote:
> > When it has sticky bit set than file can be deleted only by its owner
> > or owner of the directory.
> Intestingly, this works on Solaris 2.6 (both tmpfs and ufs).
>
> I seem to be able to delete any file in /tmp which I own _or_ can write
> to.
>
> Stevens' APUE doesn't mention this feature, so I'd be tempted to call
> it a bug in Solaris (can't test other OSes, unfortunately).
Oops, I remember something about ownership of symlinks. A symlink in /tmp
owned by root should never be unlinkable. Now we all know that the mode
of a symlink is meaningless so its owner must be meaningful in order to
create a difference in /tmp.

As far as I can recall many UNIXes deviate with respect to being able
to unlink files not owned by the euid in a 01777 directory like /tmp
The same UNIXes fail to restore the ownership of symlinks. For example,
on OSF/1 4.x "tar x.." doesn't lchown() symlinks to the original owner
when invoked as root. At the other side, the meaningless effect umask(2)
sometimes has on these symlinks is confusing as well (OSF/1 and linux
do the right thing though).

This dark corner in commercial UNIXes needs to be cleaned up but that's
not our task :-)

-- 
Frank van Maarseveen                               Driebergen
f.vanmaarseveen@inter.nl.net                  The Netherlands
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