Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbaL3DGe (ORCPT ); Mon, 29 Dec 2014 22:06:34 -0500 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:35588 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751538AbaL3DGb (ORCPT ); Mon, 29 Dec 2014 22:06:31 -0500 Message-ID: <1419908780.14143.75.camel@dhcp-9-2-203-236.watson.ibm.com> Subject: Re: [Linux-ima-user] Initramfs and IMA Appraisal From: Mimi Zohar To: David Lang Cc: Rob Landley , Christophe Fillot , linux-ima-user@lists.sourceforge.net, linux-security-module , linux-kernel Date: Mon, 29 Dec 2014 22:06:20 -0500 In-Reply-To: References: <5463ABC8.10308@utc.fr> <1415827252.18773.33.camel@dhcp-9-2-203-236.watson.ibm.com> <547617AF.6000604@utc.fr> <1417039941.26016.46.camel@dhcp-9-2-203-236.watson.ibm.com> <5476EBAC.8090103@utc.fr> <1419860736.14143.13.camel@dhcp-9-2-203-236.watson.ibm.com> <54A1BAEE.6000101@landley.net> <1419889608.14143.40.camel@dhcp-9-2-203-236.watson.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4 (3.6.4-3.fc18) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14123003-4790-0000-0000-000005E1D109 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-12-29 at 18:25 -0800, David Lang wrote: > On Mon, 29 Dec 2014, Mimi Zohar wrote: > > > Thanks Rob for the explanation. The problem is that ramfs does not > > support extended attributes, while tmpfs does. The boot loader could > > "measure" (trusted boot) the initramfs, but as the initramfs is > > generated on the target system, the initramfs is not signed, preventing > > it from being appraised (secure Boot). To close the initramfs integrity > > appraisal gap requires verifying the individual initramfs file > > signatures, which are stored as extended attributes. > > what's the point of checking the files on the filesystem against signatures > stored on the same filesystem? If someone could alter the file contents they can > alter the signatures as well. It's all about limiting which public keys can be used to verify the file signatures. As of 3.17, only keys signed by a "trusted" key on the system keyring may be added to the IMA keyring. Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/