From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751873AbdJTGiv (ORCPT ); Fri, 20 Oct 2017 02:38:51 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:50930 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751019AbdJTGit (ORCPT ); Fri, 20 Oct 2017 02:38:49 -0400 Date: Fri, 20 Oct 2017 14:38:37 +0800 From: joeyli To: David Howells Cc: linux-security-module@vger.kernel.org, gnomes@lxorguk.ukuu.org.uk, linux-efi@vger.kernel.org, matthew.garrett@nebula.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, jforbes@redhat.com Subject: Re: [PATCH 05/27] kexec: Disable at runtime if the kernel is locked down Message-ID: <20171020063837.GN3285@linux-l9pv.suse> References: <150842463163.7923.11081723749106843698.stgit@warthog.procyon.org.uk> <150842466996.7923.17995994984545441369.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150842466996.7923.17995994984545441369.stgit@warthog.procyon.org.uk> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: On Thu, Oct 19, 2017 at 03:51:09PM +0100, David Howells wrote: > From: Matthew Garrett > > kexec permits the loading and execution of arbitrary code in ring 0, which > is something that lock-down is meant to prevent. It makes sense to disable > kexec in this situation. > > This does not affect kexec_file_load() which can check for a signature on the > image to be booted. > > Signed-off-by: Matthew Garrett > Signed-off-by: David Howells > Acked-by: Dave Young I have reviewed and tested this patch. Please feel free to add: Reviewed-by: "Lee, Chun-Yi" Thanks a lot! Joey Lee > cc: kexec@lists.infradead.org > --- > > kernel/kexec.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/kexec.c b/kernel/kexec.c > index e62ec4dc6620..7dadfed9b676 100644 > --- a/kernel/kexec.c > +++ b/kernel/kexec.c > @@ -202,6 +202,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, > return -EPERM; > > /* > + * kexec can be used to circumvent module loading restrictions, so > + * prevent loading in that case > + */ > + if (kernel_is_locked_down("kexec of unsigned images")) > + return -EPERM; > + > + /* > * Verify we have a legal set of flags > * This leaves us room for future extensions. > */ > > -- > To unsubscribe from this list: send the line "unsubscribe linux-efi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html