From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757172Ab3BMNoU (ORCPT ); Wed, 13 Feb 2013 08:44:20 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:57450 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755904Ab3BMNoS (ORCPT ); Wed, 13 Feb 2013 08:44:18 -0500 Message-ID: <1360763044.3524.367.camel@falcor1.watson.ibm.com> Subject: Re: [PATCH 2/2] ima: Support appraise_type=imasig_optional From: Mimi Zohar To: "Kasatkin, Dmitry" Cc: Vivek Goyal , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 13 Feb 2013 08:44:04 -0500 In-Reply-To: References: <1360613493-11969-1-git-send-email-vgoyal@redhat.com> <1360613493-11969-3-git-send-email-vgoyal@redhat.com> <1360760195.3524.355.camel@falcor1.watson.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-3.fc16) Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13021313-2876-0000-0000-0000053CD441 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-02-13 at 15:13 +0200, Kasatkin, Dmitry wrote: > On Wed, Feb 13, 2013 at 2:56 PM, Mimi Zohar wrote: > > On Wed, 2013-02-13 at 14:31 +0200, Kasatkin, Dmitry wrote: > >> On Mon, Feb 11, 2013 at 10:11 PM, Vivek Goyal wrote: > > > >> > @@ -158,7 +165,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint, > >> > } > >> > switch (xattr_value->type) { > >> > case IMA_XATTR_DIGEST: > >> > - if (iint->flags & IMA_DIGSIG_REQUIRED) { > >> > + if (iint->flags & IMA_DIGSIG_REQUIRED || > >> > + iint->flags & IMA_DIGSIG_OPTIONAL) { > >> > cause = "IMA signature required"; > >> > status = INTEGRITY_FAIL; > >> > break; > >> > >> This looks a bit odd... If "optional" signature is missing - we fail.. > >> It is optional... Why we should fail? > > > > 'imasig_optional' does not only mean that the signature is optional, but > > also implies that it has to be a digital signature, not a hash. This > > latter part is what IMA_DIGSIG_REQUIRED means. > > > > If 'imasig_optional' set both 'IMA_DIGSIG_OPTIONAL' and > > 'IMA_DIGSIG_REQUIRED', then this change wouldn't be necessary. > > > > IMA_DIGSIG_REQUIRED would enforce that it is a signature. > > IMA_DIGSIG_OPTIONAL would fail only for files with invalid signatures. > > > > It sounds odd that optional signature is actually required. > Optional for me means that it may be there or may be not. > If it is not there, then it may be hash or nothing. > > I see it is more logical if it is "appraise_type=optional", > which means that we might have no xattr value, hash or signature. > It if happens to be a signature, then IMA_DIGSIG flag will be set. Right, 'appraise_type=' could have been defined either as a comma separated list of options (eg. appraise_type=imassig,optional) or, as Vivek implemented, a new option. Eventually, we will need to extend 'appraise_type=' (eg. required algorithm), but for now I don't have a problem with the new option. thanks, Mimi > I asked Vivek to send a policy file he uses in his system. > I would like to see how system configured as a whole... > > - Dmitry