On Fri 2009-11-06 12:55:33, Eric W. Biederman wrote: > Pavel Machek <pavel@xxxxxx> writes: > > > On Thu 2009-11-05 15:27:06, Miklos Szeredi wrote: > >> On Thu, 5 Nov 2009, Alan Cox wrote: > >> > > - re-opening normally after checking file type (there's a debate > >> > > whether this would have security issues, but currently we do allow > >> > > re-opening with increased permissions thorugh /proc/*/fd) > >> > > >> > Which has already been demonstrated to be an (unfixed) security hole. > >> > >> No it hasn't :) Jamie theorized that there *might* be a real world > >> situation where the application writer didn't anticipate this > >> behavior. But as to actual demonstration, we have not seen one yet, I > >> think. > > > > See bugtraq, or lkml thread about symlinks with permissions. There's > > demo script there. > > Exactly a theoretical discussion, that demonstrates user space > applications with security holes can be written if they make > assumptions about the world that are not true. > > So far no one who believes this to be a security hole has found it > worth their while to look at nd->intent.open in proc_pid_follow_link > and write a patch. Pavel you started out asking for help on how > to do that and I think I have answered the original question. > I am tired of the whining. If no one who is persuaded the kernel is > wrong can be bothered to write a possibly buggy 5 line patch this is > clearly not a security hole. "I did not get a patch so it can't be security hole". Interesting. I still hope to write it one day, but as I do not have untrusted users on my systems, it is not particulary urgent. (And I still hope distro security people do they job.) 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-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
