From patchwork Thu Dec 8 12:30:53 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 9466265 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 1FB2660231 for ; Thu, 8 Dec 2016 12:31:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FAD9284FA for ; Thu, 8 Dec 2016 12:31:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 048B62855A; Thu, 8 Dec 2016 12:31:57 +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=unavailable 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 8C15C284FA for ; Thu, 8 Dec 2016 12:31:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932580AbcLHMbA (ORCPT ); Thu, 8 Dec 2016 07:31:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43320 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932578AbcLHMa4 (ORCPT ); Thu, 8 Dec 2016 07:30:56 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (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 ED81265D0E; Thu, 8 Dec 2016 12:30:55 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-116-110.phx2.redhat.com [10.3.116.110]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uB8CUrPC001629; Thu, 8 Dec 2016 07:30:54 -0500 Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 6/8] efi: Disable secure boot if shim is in insecure mode [ver #6] From: David Howells To: matt@codeblueprint.co.uk, ard.biesheuvel@linaro.org Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-arm-kernel@lists.infradead.org Date: Thu, 08 Dec 2016 12:30:53 +0000 Message-ID: <148120025337.5854.14162686732874030327.stgit@warthog.procyon.org.uk> In-Reply-To: <148120020832.5854.5448601415491330495.stgit@warthog.procyon.org.uk> References: <148120020832.5854.5448601415491330495.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Thu, 08 Dec 2016 12:30:56 +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 62d6904da800..39c91e091f6a 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[] = { */ enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg) { - u8 secboot, setupmode; + u32 attr; + u8 secboot, setupmode, moksbstate; unsigned long size; efi_status_t status; @@ -52,6 +59,21 @@ enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg) if (secboot == 0 || setupmode == 1) return efi_secureboot_mode_disabled; + /* 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) + goto secure_boot_enabled; + if (!(attr & EFI_VARIABLE_RUNTIME_ACCESS) && moksbstate == 1) + return efi_secureboot_mode_disabled; + +secure_boot_enabled: pr_efi(sys_table_arg, "UEFI Secure Boot is enabled.\n"); return efi_secureboot_mode_enabled;