From patchwork Thu Oct 26 07:42:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: joeyli X-Patchwork-Id: 10027547 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6DD626022E for ; Thu, 26 Oct 2017 07:42:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 59A2428D48 for ; Thu, 26 Oct 2017 07:42:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B16228D4A; Thu, 26 Oct 2017 07:42:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 96B9B28D48 for ; Thu, 26 Oct 2017 07:42:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751027AbdJZHm4 (ORCPT ); Thu, 26 Oct 2017 03:42:56 -0400 Received: from smtp.nue.novell.com ([195.135.221.5]:49158 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751001AbdJZHmz (ORCPT ); Thu, 26 Oct 2017 03:42:55 -0400 Received: from linux-l9pv.suse (unknown.telstraglobal.net [134.159.103.118]) by smtp.nue.novell.com with ESMTP (TLS encrypted); Thu, 26 Oct 2017 09:42:50 +0200 Date: Thu, 26 Oct 2017 15:42:43 +0800 From: joeyli To: Mimi Zohar Cc: David Howells , 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 07/27] kexec_file: Disable at runtime if securelevel has been set Message-ID: <20171026074243.GM8550@linux-l9pv.suse> References: <150842463163.7923.11081723749106843698.stgit@warthog.procyon.org.uk> <150842468754.7923.10037578333644594134.stgit@warthog.procyon.org.uk> <1508774083.3639.124.camel@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1508774083.3639.124.camel@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Hi Mimi, Thank you for reviewing. On Mon, Oct 23, 2017 at 11:54:43AM -0400, Mimi Zohar wrote: > On Thu, 2017-10-19 at 15:51 +0100, David Howells wrote: > > From: Chun-Yi Lee > > > > When KEXEC_VERIFY_SIG is not enabled, kernel should not loads image > > through kexec_file systemcall if securelevel has been set. > > The patch title and description needs to be updated to refer to > lockdown, not securelevel. > > As previously mentioned the last time these patches were posted, this > leaves out testing to see if the integrity subsystem is enabled. > > Commit 503ceaef8e2e "ima: define a set of appraisal rules requiring > file signatures" was upstreamed.  An additional patch could force > these rules to be added to the custom policy, if lockdown is enabled. >  This and other patches in this series could then check to see if > is_ima_appraise_enabled() is true. > > Mimi > I have updated the patch title and description, and I also added is_ima_appraise_enabled() as the following. Is it good to you? On the other hand, I am not good on IMA. I have traced the code path in kimage_file_prepare_segments(). Looks that the READING_KEXEC_IMAGE doesn't show in selinux_kernel_read_file(). Where is the exact code in IMA for checking the signature when loading crash kernel file? Thanks a lot! Joey Lee --- From 274a2125132ba5aff49e4ccd167f52982732361f Mon Sep 17 00:00:00 2001 From: "Lee, Chun-Yi" Date: Thu, 26 Oct 2017 15:24:50 +0800 Subject: [PATCH] kexec_file: The integrity must be checked when the kernel is locked down When KEXEC_VERIFY_SIG and IMA appraise are not enabled, kernel should not allow that the image to be loaded by kexec_file systemcall when the kernel is locked down. The original code was showed in Matthew's patch but not in the later patch set: https://lkml.org/lkml/2015/3/13/778 Signed-off-by: "Lee, Chun-Yi" --- kernel/kexec_file.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 9f48f44..b6dc218 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -255,6 +255,14 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; + /* Don't permit images to be loaded into trusted kernels if we're not + * going to check the integrity on them + */ + if (!IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) && + !is_ima_appraise_enabled() && + kernel_is_locked_down("kexec of unsigned images")) + return -EPERM; + /* Make sure we have a legal set of flags */ if (flags != (flags & KEXEC_FILE_FLAGS)) return -EINVAL;