Date: Tue, 22 Feb 2011 11:14:54 -0800
From: Greg KH <gregkh@suse.de>
To: Kees Cook <kees.cook@canonical.com>
Cc: 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: <20110222191454.GB9991@suse.de>
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>
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On Tue, Feb 22, 2011 at 10:47:26AM -0800, Kees Cook wrote:
> On Tue, Feb 22, 2011 at 10:32:19AM -0800, David Daney wrote:
> > On 02/22/2011 10:16 AM, 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.
> > >
> > >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?
> > >
> > 
> > It depends if you consider use of ftrace and kprobes 'debugging'.
> > In any event, you really have to be root to be able to manipulate
> > them.
> > 
> > I can currently do 'cat /sys/kernel/debug/tracing/trace' as a normal
> > user.  With your change I don't think it would be possible.  This is
> > not something I often (ever) do, but it is a change.
> 
> Right, my thinking is that all the manipulations on this tree should be
> root-only (non-root stuff shouldn't live in something named "debug"),
> so we might as well lock it down a bit more so we can avoid all the CVEs[1]
> being assigned for glitches in this tree.

The CVEs are for non-root writes to debugfs, same thing for sysfs.  It's
just stupid mistakes being made here, don't try to lock down the whole
filesystem for just a handfull of bugs.

So I really can't accept these patches, sorry.

thanks,

greg k-h
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