Return-path: Received: from mx2.suse.de ([195.135.220.15]:49305 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756021AbbIBVhV (ORCPT ); Wed, 2 Sep 2015 17:37:21 -0400 Date: Wed, 2 Sep 2015 23:37:17 +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 , Jay Schulist , Daniel Borkmann , Alexei Starovoitov Subject: Re: Linux Firmware Signing Message-ID: <20150902213717.GJ8051@wotan.suse.de> (sfid-20150902_233738_351028_106BBC2A) References: <1440464705.2737.36.camel@linux.vnet.ibm.com> <14540.1440599584@warthog.procyon.org.uk> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-wireless-owner@vger.kernel.org List-ID: 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: SECURITY_FILE_SYSDATA_FW SECURITY_FILE_SYSDATA_MICROCODE SECURITY_FILE_SYSDATA_EEPROM SECURITY_FILE_SYSDATA_POLICY (for 802.11 regulatory I suppose) If we do this then we could juse have: SECURITY_FILECHECK_KEXEC and on that have substypes: SECURITY_FILE_KEXEC_KERNEL SECURITY_FILE_KEXEC_INITRAMFS Would that be desirable and help grow this to be easily extensible? Luis