From patchwork Thu Jul 18 19:44:14 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11049481 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0428C138D for ; Thu, 18 Jul 2019 19:45:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E8AAF27FA5 for ; Thu, 18 Jul 2019 19:45:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DCBF82837D; Thu, 18 Jul 2019 19:45:45 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL 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 8BB4F27FA5 for ; Thu, 18 Jul 2019 19:45:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404167AbfGRTpl (ORCPT ); Thu, 18 Jul 2019 15:45:41 -0400 Received: from mail-pl1-f202.google.com ([209.85.214.202]:46833 "EHLO mail-pl1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404123AbfGRTpb (ORCPT ); Thu, 18 Jul 2019 15:45:31 -0400 Received: by mail-pl1-f202.google.com with SMTP id k9so14451827pls.13 for ; Thu, 18 Jul 2019 12:45:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=1gkPgS/LUQWYTDhNcm4n5VtrDpueDO81OkRBGTKoxwg=; b=pXA0X1WYESnUxeTUYFiBCooMuuh4vW22b03ZXSm5zMUF8YBE6F9xjLpiSkz32ut3dV sVCzdtElGnDxQykLV1WTTmAb4YgbqMhw/hJhKNId5sf+lP1WkFe0DHEDbRiM4z2hfhLJ iK6U7KPrBHEEp8izpgpV6X73LDyuvV6V+9ToWMovS4380QxL1/U7mzutzATNB8OaZYHm Kh4FpkPv0Fv9auWT8s+aCImHbJyjCZGGXPxuA7yH/Mz+sBDaleVUmj4UhNsPTyHTjynY rYOMdVuEtQROB+t1c2KOrP0kx5v/9LJmd1xN+mRHEQjwWOj18vFW99Kt5KEGb6PYfMR2 S60g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=1gkPgS/LUQWYTDhNcm4n5VtrDpueDO81OkRBGTKoxwg=; b=uUYcr/15w6/Vagx1lfKHIB/hqL/6UegbsBQRljIgFxTCzKi5EfgMFULB74aZtjgyCS H6+1nPmLmNU4ro0ftk6TRazPdUAHv7NvROlb11BPzC3gp6csZ12d5odoI2DlAcV/25uq YmVQn/8zeZ8r7r4OdEtioB171ALqLrxLlj+NrUF1l8jQFvpuCo6EUX8Cv66ltZBP1JTQ CXATktbBhypCWvBNSIqvDlMsS76NeM7+RVxqzEmgeYKNXVQyXvX/d2V5i9qH161qGxDu aVMMgRXCj4l49KtQhkT4ob0exIyHlDs/R5PNeZGlGnc6yCoGAUAodNaQTVoVf7USk1VW CT6g== X-Gm-Message-State: APjAAAWbpHBZuUCJTvLJmmYAFvzPfKK4iejmJBG+QRokpIoZiE/T1kHL S3itkzOZa7Z2hmFkmSUOC/ijotIKgijHTNogwcAtDQ== X-Google-Smtp-Source: APXvYqxwqkDrXVnqXgFX8V2quFdORdqeEDNkSG6F+hbmam7qsgt7IU5OHfo3gKWFROaZ4LnpcXcAdTeF5PDp8QS5kQDg+Q== X-Received: by 2002:a63:24a:: with SMTP id 71mr24650403pgc.273.1563479131021; Thu, 18 Jul 2019 12:45:31 -0700 (PDT) Date: Thu, 18 Jul 2019 12:44:14 -0700 In-Reply-To: <20190718194415.108476-1-matthewgarrett@google.com> Message-Id: <20190718194415.108476-29-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190718194415.108476-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.510.g264f2c817a-goog Subject: [PATCH V36 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Matthew Garrett , Matthew Garrett , Ard Biesheuvel , Kees Cook , linux-efi@vger.kernel.org Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an EFI variable, which gives arbitrary code execution in ring 0. Prevent that when the kernel is locked down. Signed-off-by: Matthew Garrett Acked-by: Ard Biesheuvel Reviewed-by: Kees Cook Cc: Ard Biesheuvel Cc: linux-efi@vger.kernel.org --- drivers/firmware/efi/efi.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index ad3b1f4866b3..776f479e5499 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -30,6 +30,7 @@ #include #include #include +#include #include @@ -242,6 +243,11 @@ static void generic_ops_unregister(void) static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata; static int __init efivar_ssdt_setup(char *str) { + int ret = security_locked_down(LOCKDOWN_ACPI_TABLES); + + if (ret) + return ret; + if (strlen(str) < sizeof(efivar_ssdt)) memcpy(efivar_ssdt, str, strlen(str)); else