From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH] don't allow CAP_NET_ADMIN to load non-netdev kernel modules Date: Fri, 25 Feb 2011 19:30:16 +0000 Message-ID: <1298662216.2554.33.camel@bwh-desktop> References: <20110225190205.GA4541@albatros> <20110225.110529.39178636.davem@davemloft.net> <1298660879.2554.23.camel@bwh-desktop> <20110225.111606.115927805.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: segoon@openwall.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru, pekkas@netcore.fi, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, eric.dumazet@gmail.com, therbert@google.com, xiaosuo@gmail.com, jesse@nicira.com, kees.cook@canonical.com, eugene@redhat.com, dan.j.rosenberg@gmail.com, akpm@linux-foundation.org To: David Miller Return-path: In-Reply-To: <20110225.111606.115927805.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 2011-02-25 at 11:16 -0800, David Miller wrote: > From: Ben Hutchings > Date: Fri, 25 Feb 2011 19:07:59 +0000 > > > You realise that module loading doesn't actually run in the context of > > request_module(), right? > > Why is that a barrier? We could simply pass a capability mask into > request_module if necessary. > > It's an implementation detail, and not a deterrant to my suggested > scheme. It's not an implementation detail. modprobe currently runs with full capabilities; your proposal requires its capabilities to be limited to those of the capabilities of the process that triggered the request_module() (plus, presumably, CAP_SYS_MODULE). Now modprobe doesn't have CAP_DAC_OVERRIDE and can't read modprobe configuration files that belong to users other than root. It doesn't have CAP_SYS_MKNOD so it can't run hooks that call mknod. etc. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.