From patchwork Wed Nov 16 16:16:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 625240 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BE1AC4167D for ; Wed, 16 Nov 2022 16:17:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234223AbiKPQRV (ORCPT ); Wed, 16 Nov 2022 11:17:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238085AbiKPQRR (ORCPT ); Wed, 16 Nov 2022 11:17:17 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8514BD135; Wed, 16 Nov 2022 08:17:16 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 42997B81DD9; Wed, 16 Nov 2022 16:17:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CD32C433D6; Wed, 16 Nov 2022 16:17:13 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="DO7/xtKp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1668615433; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=SutN9URRaDRkoRI4sfbAAJPIQ0pLYtrJHZUE/tUAx5Q=; b=DO7/xtKpmJ+qbHUkvjOiJl95LOYlJrLNXrCH1BXJ5r/WuFITUd9HEjZ/RqdSLzoGooTmYc gfHssY9a8mQGQCUu90xJOpKx3QeILTHlt5an1KxtzQ2WBAcZ4bsfucAykgwEOaq44uGweW bOC9xpFA89pnO1UW3k8kh5xasxnPH/E= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 8e977426 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 16 Nov 2022 16:17:12 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Ard Biesheuvel , Lennart Poettering Subject: [PATCH RFC v1 5/6] efi: efivarfs: prohibit reading random seed variables Date: Wed, 16 Nov 2022 17:16:41 +0100 Message-Id: <20221116161642.1670235-6-Jason@zx2c4.com> In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Variables in the random seed GUID must remain secret, so deny all reads to them. Signed-off-by: Jason A. Donenfeld --- fs/efivarfs/file.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c index d57ee15874f9..08996ba3a373 100644 --- a/fs/efivarfs/file.c +++ b/fs/efivarfs/file.c @@ -76,6 +76,9 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, while (!__ratelimit(&file->f_cred->user->ratelimit)) msleep(50); + if (guid_equal(&var->var.VendorGuid, &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) + return -EPERM; + err = efivar_entry_size(var, &datasize); /*