Return-path: Received: from mx2.suse.de ([195.135.220.15]:58313 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932747AbbI3UeF (ORCPT ); Wed, 30 Sep 2015 16:34:05 -0400 Date: Wed, 30 Sep 2015 22:34:00 +0200 From: "Luis R. Rodriguez" To: Kees Cook Cc: Mimi Zohar , David Woodhouse , David Howells , Andy Lutomirski , "Roberts, William C" , "linux-security-module@vger.kernel.org" , LKML , linux-wireless , "james.l.morris@oracle.com" , "serge@hallyn.com" , Vitaly Kuznetsov , Paul Moore , Eric Paris , SE Linux , Stephen Smalley , "Schaufler, Casey" , "Luis R. Rodriguez" , Dmitry Kasatkin , Greg Kroah-Hartman , Peter Jones , Takashi Iwai , Ming Lei , Joey Lee , =?utf-8?Q?Vojt=C4=9Bch_Pavl=C3=ADk?= , Kyle McMartin , Seth Forshee , Matthew Garrett , Johannes Berg , Alexei Starovoitov Subject: Re: Linux Firmware Signing Message-ID: <20150930203400.GC14464@wotan.suse.de> (sfid-20150930_223428_776810_1205DBF5) References: <31228.1440671938@warthog.procyon.org.uk> <36ddb60c1d22756234392a2d065a02cb.squirrel@twosheds.infradead.org> <20150827212907.GF8051@wotan.suse.de> <20150902000915.GW8051@wotan.suse.de> <1441164905.17898.86.camel@linux.vnet.ibm.com> <20150902184604.GB8051@wotan.suse.de> <20150902213717.GJ8051@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Sep 03, 2015 at 02:14:18PM -0700, Kees Cook wrote: > [removed bounced email addresses] > > On Wed, Sep 2, 2015 at 2:37 PM, Luis R. Rodriguez wrote: > > On Wed, Sep 02, 2015 at 01:54:43PM -0700, Kees Cook wrote: > >> On Wed, Sep 2, 2015 at 11:46 AM, Luis R. Rodriguez wrote: > >> > On Tue, Sep 01, 2015 at 11:35:05PM -0400, Mimi Zohar wrote: > >> >> > OK great, I think that instead of passing the actual routine name we should > >> >> > instead pass an enum type for to the LSM, that'd be easier to parse and we'd > >> >> > then have each case well documented. Each LSM then could add its own > >> >> > documetnation for this and can switch on it. If we went with a name we'd have > >> >> > to to use something like __func__ and then parse that, its not clear if we need > >> >> > to get that specific. > >> >> > >> >> Agreed. IMA already defines an enumeration. > >> >> > >> >> /* IMA policy related functions */ > >> >> enum ima_hooks { FILE_CHECK = 1, MMAP_CHECK, BPRM_CHECK, MODULE_CHECK, > >> >> FIRMWARE_CHECK, POLICY_CHECK, POST_SETATTR }; > >> >> > >> > > >> > We want something that is not only useful for IMA but any other LSM, > >> > and FILE_CHECK seems very broad, not sure what BPRM_CHECK is even upon > >> > inspecting kernel code. Likewise for POST_SETATTR. POLICY_CHECK might > >> > be broad, perhaps its best we define then a generic set of enums to > >> > which IMA can map them to then and let it decide. This would ensure > >> > that the kernel defines each use caes for file inspection carefully, > >> > documents and defines them and if an LSM wants to bunch a set together > >> > it can do so easily with a switch statement to map set of generic > >> > file checks in kernel to a group it already handles. > >> > > >> > For instance at least in the short term we'd try to unify: > >> > > >> > security_kernel_fw_from_file() > >> > security_kernel_module_from_file() > >> > > >> > to perhaps: > >> > > >> > security_kernel_from_file() > >> > > >> > As far, as far as I can tell, the only ones we'd be ready to start > >> > grouping immediately or with small amount of work rather soon: > >> > > >> > /** > >> > * > >> > * enum security_filecheck - known kernel security file checks types > >> > * > >> > * @__SECURITY_FILECHECK_UNSPEC: attribute 0 reserved > >> > * @SECURITY_FILECHECK_MODULE: the file being processed is a Linux kernel module > >> > * @SECURITY_FILECHECK_SYSDATA: the file being processed is either a firmware > >> > * file or a system data file read from /lib/firmware/* by firmware_class > >> > >> I'd prefer a distinct category for firmware, as it carries an > >> implication that it is an executable blob of some sort (I know not all > >> are, though). > > > > The ship has sailed in terms of folks using frimrware API for things > > that are not-firmware per se. The first one I am aware of was the > > EEPROM override for the p54 driver. The other similar one was CPU > > microcode, but that's a bit more close to home with "firmware". We > > could ask users on the new system data request API I am building > > to describe the type of file being used, as I agree differentiating > > this for security purposes might be important. So other than just > > file type we could have sub type category, then we could have, > > > > SECURITY_FILECHECK_SYSDATA, and then: > > I object to executable code being called data. :) > > > SECURITY_FILE_SYSDATA_FW > > SECURITY_FILE_SYSDATA_MICROCODE > > SECURITY_FILE_SYSDATA_EEPROM > > SECURITY_FILE_SYSDATA_POLICY (for 802.11 regulatory I suppose) > > The exception to the firmware loading is data, so the primary name > should be firmware. Regardless, if we want distinct objects, just name > them: > > SECURITY_FILE_FIRMWARE > SECURITY_FILE_SYSDATA > > Do we need finer-grain sub types? These two work for me. Luis