Bugtraq mailing list archives
Re: /proc filesystem allows bypassing directory permissions on Linux
From: Pavel Machek <pavel () ucw cz>
Date: Sat, 24 Oct 2009 00:39:24 +0200
Original owner did chmod 666... after making sure traditional unix permissions protect the file. Please look at original mail; it was subtle but I believe I got it right, and file would not be writable with /proc unmounted.I remember the original mail content. You're right, you can't reach the file if the procfs is not mounted, but you forget about the race, allowing the guest to create a hardlink to the file in an unrestricted location before the directory access becomes restricted. Again, procfs is just another, specific kind of hardlinks.
Check it again. There's no race; I check link count before chmod 666. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Current thread:
- Re: /proc filesystem allows bypassing directory permissions on Linux, (continued)
- Re: /proc filesystem allows bypassing directory permissions on Linux Pavel Machek (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Dan Yefimov (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Derek Martin (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Ansgar Wiechers (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Derek Martin (Oct 28)
- Re: /proc filesystem allows bypassing directory permissions on Linux CaT (Oct 29)
- Re: /proc filesystem allows bypassing directory permissions on Linux Dan Yefimov (Oct 23)
- Re: /proc filesystem allows bypassing directory permissions on Linux Arturo 'Buanzo' Busleiman (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Pavel Machek (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Dan Yefimov (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Pavel Machek (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Dan Yefimov (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Tamber Penketh (Oct 26)
- Re: /proc filesystem allows bypassing directory permissions on Linux Pavel Machek (Oct 27)