From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH v2] kptr_restrict for hiding kernel pointers from unprivileged users Date: Fri, 17 Dec 2010 17:22:31 -0800 Message-ID: <20101217172231.8842f5cc.akpm@linux-foundation.org> References: <1292025924.2965.20.camel@Dan> <20101217164431.08f3e730.akpm@linux-foundation.org> <1292634759.9764.26.camel@Dan> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, jmorris@namei.org, eugeneteo@kernel.org, kees.cook@canonical.com, mingo@elte.hu, davem@davemloft.net To: Dan Rosenberg Return-path: In-Reply-To: <1292634759.9764.26.camel@Dan> Sender: linux-security-module-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 17 Dec 2010 20:12:39 -0500 Dan Rosenberg wrote: > > > > So what's next? We need to convert 1,000,000 %p callsites to use %pK? > > That'll be fun. Please consider adding a new checkpatch rule which > > detects %p and asks people whether they should have used %pK. > > The goal of this format specifier is specifically for pointers that are > exposed to unprivileged users. I agree that hiding all kernel pointers > would be nice, but I don't expect the angry masses to ever agree to > that. For now, I'll isolate specific cases, especially in /proc, that > are clear risks in terms of information leakage. I'll also be skipping > over pointers written to the syslog, since I think hiding that > information is dmesg_restrict's job. Well... some administrators may wish to hide the pointer values even for privileged callers. That's a pretty trivial add-on for the code which you have, and means that those admins can also suppress the pointers for IRQ-time callers. More /proc knobs :) Then again, perhaps those admins would be OK if we simply disabled plain old %p everywhere. In which case we're looking at a separate patch, I suggest.