Date: Tue, 22 Feb 2011 19:34:18 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Kees Cook <kees.cook@canonical.com>
Cc: Greg KH <gregkh@suse.de>, David Daney <ddaney@caviumnetworks.com>,
        linux-kernel@vger.kernel.org, Eugene Teo <eugeneteo@kernel.sg>,
        Ralph Campbell <infinipath@qlogic.com>,
        Roland Dreier <roland@kernel.org>, Sean Hefty <sean.hefty@intel.com>,
        Hal Rosenstock <hal.rosenstock@gmail.com>,
        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Miklos Szeredi <miklos@szeredi.hu>,
        "J. Bruce Fields" <bfields@fieldses.org>, Neil Brown <neilb@suse.de>,
        Matthew Wilcox <matthew@wil.cx>, James Morris <jmorris@namei.org>,
        Stephen Smalley <sds@tycho.nsa.gov>,
        Eric Paris <eparis@parisplace.org>, Nick Piggin <npiggin@kernel.dk>,
        Arnd Bergmann <arnd@arndb.de>, Ian Campbell <ian.campbell@citrix.com>,
        Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com>,
        Tejun Heo <tj@kernel.org>, Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [PATCH 2/2] debugfs: only allow root access to debugging
 interfaces
Message-ID: <20110222193418.773ccd4b@lxorguk.ukuu.org.uk>
In-Reply-To: <20110222192532.GY4000@outflux.net>
References: <1298398198-18482-1-git-send-email-kees.cook@canonical.com>
	<1298398198-18482-2-git-send-email-kees.cook@canonical.com>
	<20110222181613.GU4000@outflux.net>
	<4D640133.9020901@caviumnetworks.com>
	<20110222184726.GV4000@outflux.net>
	<20110222191454.GB9991@suse.de>
	<20110222192532.GY4000@outflux.net>
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> What system do you proposed to keep these "stupid mistakes" from
> continuing to happen? If debugfs had already been mode 0700, we could have
> avoided all of these CVEs, including the full-blown local root escalation.

And all sorts of features would have put themselves in sysfs instead and
broken no doubt.

> The "no rules" approach to debugfs is not a good idea, IMO.

It's a debugging fs, it needs to be "no rules" other than the obvious
"don't mount it on production systems"

Anyway - we don't mostly have a "root/non-root" model - it went out
around Linux 1.2. So any model for dealing with should be respecting of
capabilities, SELinux and the like.

Or of course you could just chmod it 0700 in the distro !
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