On Tue 2009-10-27 11:49:32, CaT wrote: > On Tue, Oct 27, 2009 at 12:29:09AM +0300, Dan Yefimov wrote: > > and testing them. Remember the scenario from the original mail and try > > finding a window, during which creating a hardlink would still work thus > > evading directory permissions check. > > The main thing this does is allow a hardlink-like attack to work across > mountpoints afaics. Yes, plus it allows "hardlinks" on deleted files, and this "strange hard links" can not be seen on link count. > You can't actually use /proc/*/fd to gain access to files opened by > processes you do not own. Only ones you do (at least in a mainline kernel) > which is fair enough. This means that you can't have user a open a file > owned by user b and then let user c have access to it via > /proc/$pid/fd. No, but you can upgrade file from read-only to read-write using /proc. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
