From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932144Ab3CDQU4 (ORCPT ); Mon, 4 Mar 2013 11:20:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37294 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758165Ab3CDQUy (ORCPT ); Mon, 4 Mar 2013 11:20:54 -0500 Date: Mon, 4 Mar 2013 11:20:33 -0500 From: Vivek Goyal To: Mimi Zohar Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dmitry.kasatkin@intel.com Subject: Re: [PATCH 2/6] ima: Return INTEGRITY_FAIL if digital signature can't be verified Message-ID: <20130304162033.GB15199@redhat.com> References: <1360871745-20616-1-git-send-email-vgoyal@redhat.com> <1360871745-20616-3-git-send-email-vgoyal@redhat.com> <1362404916.4392.25.camel@falcor1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1362404916.4392.25.camel@falcor1> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 04, 2013 at 08:48:36AM -0500, Mimi Zohar wrote: > On Thu, 2013-02-14 at 14:55 -0500, Vivek Goyal wrote: > > Digital signature verification happens using integrity_digsig_verify(). > > Curently we set integrity to FAIL for all error codes except -EOPNOTSUPP. > > This sounds out of line. > > > > - If appropriate kernel code is not compiled in to verify signature of > > a file, then prractically it is a failed signature. > > > > - For so many other possible errors we are setting the status to fail. > > For example, -EINVAL, -ENOKEY, -ENOMEM, -EINVAL, -ENOTSUPP etc, it > > beats me that why -EOPNOTSUPP is special. > > > > This patch should make the semantics more consistent. That is, if digital > > signature is present in security.ima, then any error happened during > > signature processing leads to status INTEGRITY_FAIL. > > > > AFAICS, it should not have any user visible effect on existing > > application. In some cases we will start returning INTEGRITY_FAIL > > instead of INTEGRITY_UNKNOWN. And process_measurement() will deny access > > to file both in case of INTEGRITY_UNKNOWN and INTEGRITY_FAIL. > > > > Signed-off-by: Vivek Goyal > > A number of patches in this patchset more finely differentiate return > codes, which is good. I agree with you totally that there is no good > reason for -EOPNOTSUPP to be handled differently. Unfortunately, the > initramfs is CPIO, which doesn't support xattrs. With the proposed > change and 'ima_appraise_tcb' flag enabled, we wouldn't be able to boot. > I really dislike hard coding policy in the kernel. Hi Mimi, If there are no xattr, then we will not even hit this code. We will bail out early in vfs_getxattr_alloc(). I thought that one of the DON_APPRAISE rules will kick in for initramfs and files in initramfs will not be appraised and boot will continue. {.action = DONT_APPRAISE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC}, Is that not the case here? Thanks Vivek