Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758179Ab2KBVdF (ORCPT ); Fri, 2 Nov 2012 17:33:05 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:44173 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755651Ab2KBVdB (ORCPT ); Fri, 2 Nov 2012 17:33:01 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Vivek Goyal Cc: Matthew Garrett , Mimi Zohar , Khalid Aziz , kexec@lists.infradead.org, horms@verge.net.au, Dave Young , "H. Peter Anvin" , linux kernel mailing list , Dmitry Kasatkin , Roberto Sassu , Kees Cook , Peter Jones References: <20121025185520.GA17995@redhat.com> <1351214158.18115.186.camel@falcor> <20121026023916.GA16762@srcf.ucam.org> <20121026170609.GB24687@redhat.com> <1351276649.18115.217.camel@falcor> <20121101131003.GA14573@redhat.com> <20121101135356.GA15659@redhat.com> <1351780159.15708.17.camel@falcor> <20121101144304.GA15821@redhat.com> <20121101145225.GB10269@srcf.ucam.org> <20121102132318.GA3300@redhat.com> Date: Fri, 02 Nov 2012 14:32:48 -0700 In-Reply-To: <20121102132318.GA3300@redhat.com> (Vivek Goyal's message of "Fri, 2 Nov 2012 09:23:19 -0400") Message-ID: <87boffd727.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX18d9e1MJRTCc5Wv080FaESYHgU23+rdGvA= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Vivek Goyal X-Spam-Relay-Country: Subject: Re: Kdump with signed images X-SA-Exim-Version: 4.2.1 (built Sun, 08 Jan 2012 03:05:19 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2087 Lines: 50 Vivek Goyal writes: > On Thu, Nov 01, 2012 at 02:52:25PM +0000, Matthew Garrett wrote: >> On Thu, Nov 01, 2012 at 10:43:04AM -0400, Vivek Goyal wrote: >> >> > So I think this does satisfy the requirement matthew specified. Isn't it? >> > Matthew, what do you think? >> >> Sure, if you can ensure that. You'll need to figure out how to get the >> build system to sign the userspace binaries and you'll need to ensure >> that they're statically linked and don't dlopen anything (including the >> nsswitch modules), but otherwise that should work. >> > > [ CC peter jones ] > > Ok, so even if we build kexec-tools statically with glibc, we have the > issue of name service switch modules. glibc will still do dlopen on > these modules. So what are options now. > > - Sign glibc and associated shared libraries. Do not allow unsigned > shared library to dynamically link with signed executable. > > - Peter mentioned that work with uClibc for kexec-tools. > > I personally think that however hard it is but first option sounds like > a long term solution. We might have more user space processes which > we might have to trust a generic solution will help with that. For example, > we might have to sign and trust qemu at some point of time. > > Are there other ways of handing glibc issue? It needs to be checked but /sbin/kexec should not use any functions that trigger nss switch. No user or password or host name lookup should be happening. This is one part in hardening /sbin/kexec to deal with hostile root users. We need to check crazy things like do the files we open on /proc actually point to /proc after we have opened them. I believe glibc has some code which triggers for suid root applications that we should ensure gets triggered that avoid trusting things like LD_LIBRARY_PATH and company. Eric -- 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/