From patchwork Wed Nov 23 12:54:18 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 9443133 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 E87F9600BA for ; Wed, 23 Nov 2016 12:54:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E034025E13 for ; Wed, 23 Nov 2016 12:54:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D141F208E3; Wed, 23 Nov 2016 12:54:42 +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 54A2B208E3 for ; Wed, 23 Nov 2016 12:54:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936460AbcKWMyc (ORCPT ); Wed, 23 Nov 2016 07:54:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59832 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936596AbcKWMyU (ORCPT ); Wed, 23 Nov 2016 07:54:20 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 22DDD4E03F; Wed, 23 Nov 2016 12:54:20 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-116-110.phx2.redhat.com [10.3.116.110]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uANCsIk9021974; Wed, 23 Nov 2016 07:54:18 -0500 Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 6/7] efi: Disable secure boot if shim is in insecure mode [ver #3] From: David Howells To: lukas@wunner.de Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, Josh Boyer , keyrings@vger.kernel.org, linux-arm-kernel@lists.infradead.org Date: Wed, 23 Nov 2016 12:54:18 +0000 Message-ID: <147990565792.7576.13384993017190259260.stgit@warthog.procyon.org.uk> In-Reply-To: <147990561294.7576.6464430479448167484.stgit@warthog.procyon.org.uk> References: <147990561294.7576.6464430479448167484.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 23 Nov 2016 12:54:20 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: Josh Boyer A user can manually tell the shim boot loader to disable validation of images it loads. When a user does this, it creates a UEFI variable called MokSBState that does not have the runtime attribute set. Given that the user explicitly disabled validation, we can honor that and not enable secure boot mode if that variable is set. Signed-off-by: Josh Boyer Signed-off-by: David Howells --- drivers/firmware/efi/libstub/secureboot.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/firmware/efi/libstub/secureboot.c b/drivers/firmware/efi/libstub/secureboot.c index 466fe24f5866..ca643eba5a4b 100644 --- a/drivers/firmware/efi/libstub/secureboot.c +++ b/drivers/firmware/efi/libstub/secureboot.c @@ -23,6 +23,12 @@ static const efi_char16_t const efi_SetupMode_name[] = { 'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0 }; +/* SHIM variables */ +static const efi_guid_t shim_guid = EFI_SHIM_LOCK_GUID; +static efi_char16_t const shim_MokSBState_name[] = { + 'M', 'o', 'k', 'S', 'B', 'S', 't', 'a', 't', 'e', 0 +}; + #define get_efi_var(name, vendor, ...) \ efi_call_runtime(get_variable, \ (efi_char16_t *)(name), (efi_guid_t *)(vendor), \ @@ -33,7 +39,8 @@ static const efi_char16_t const efi_SetupMode_name[] = { */ int efi_get_secureboot(efi_system_table_t *sys_table_arg) { - u8 val; + u32 attr; + u8 val, moksbstate; unsigned long size = sizeof(val); efi_status_t status; @@ -55,6 +62,21 @@ int efi_get_secureboot(efi_system_table_t *sys_table_arg) if (val == 1) return 0; + /* See if a user has put shim into insecure mode. If so, and if the + * variable doesn't have the runtime attribute set, we might as well + * honor that. + */ + size = sizeof(moksbstate); + status = get_efi_var(shim_MokSBState_name, &shim_guid, + &attr, &size, &moksbstate); + + /* If it fails, we don't care why. Default to secure */ + if (status != EFI_SUCCESS) + return 1; + + if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS) && moksbstate == 1) + return 0; + return 1; out_efi_err: