Messages in this thread | | | Date | Tue, 22 Feb 2011 11:22:48 -0800 | From | Kees Cook <> | Subject | Re: [PATCH 2/2] debugfs: only allow root access to debugging interfaces |
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Hi Greg,
On Tue, Feb 22, 2011 at 11:13:33AM -0800, Greg KH wrote: > On Tue, Feb 22, 2011 at 10:16:13AM -0800, Kees Cook wrote: > > Har har, I forgot --compose to "git send-email". > > > > Anyway, with the continuing deluge of bugs in the "debug" filesystem, I > > would like to make that filesystem's root directory mode 0700 by default > > since it's filled with crazy stuff that regular users do not need to see. > > But that will break existing users of this interface, right? > > > Better to try to just close the door completely on all the stuff in there. > > It is, after all, supposed to only be used for debugging, right? > > No, not really, people use it for all sorts of crazy things. > > Remember, the only rule in debugfs is: > There are no rules in debugfs.
Right, which seems extremely dangerous to me. I think debugfs should either be: a) used only by the root user (would prefer this was actually CAP_DEBUG or something) or b) used by userspace tools
But not both. Creating interfaces with no rules for userspace consumption is going to lead to disaster. You can't disallow "break[ing] existing users of this interface" and say there are no rules at the same time. :)
-Kees
-- Kees Cook Ubuntu Security Team
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