Re: symlinks with permissions

[Pavel Machek]

On Mon 2009-10-26 14:22:16, Trond Myklebust wrote:
> On Sun, 2009-10-25 at 10:36 +0100, Pavel Machek wrote:
> > Well, it is unexpected and mild security hole.
> > 
> > Part of the problem is that even  if you have read-only
> > filedescriptor, you can upgrade it to read-write, even if path is
> > inaccessible to you.
> > 
> > So if someone passes you read-only filedescriptor, you can still write
> > to it.
> 
> If someone passes you a file descriptor, can't you in any case play
> games with, openat(fd,"",O_RDWR), in order to achieve the same thing? I
> must admit I haven't tried it yet, but at a first glance I can't see
> anything that prevents me from doing this...

According to my documentation, openat needs directory fd.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/