From patchwork Thu May 23 16:18:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10958389 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 D8788933 for ; Thu, 23 May 2019 16:20:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C486D27D4A for ; Thu, 23 May 2019 16:20:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B92D22846D; Thu, 23 May 2019 16:20:57 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 4F35827D4A for ; Thu, 23 May 2019 16:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731722AbfEWQU4 (ORCPT ); Thu, 23 May 2019 12:20:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:56360 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731354AbfEWQUk (ORCPT ); Thu, 23 May 2019 12:20:40 -0400 Received: from sol.localdomain (c-24-5-143-220.hsd1.ca.comcast.net [24.5.143.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E5A421855; Thu, 23 May 2019 16:20:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558628438; bh=IypddWdgpGQW98s/1LmMIKN+E0awwoanRr5vpkgTF8c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MAMyc0xNHquD9YW6+5HzRcneZT9WqRTjjzjI/g+EHazOH1ftZvl6WWXnNGuV6TMgf G7uqtVpqRLIDLms9VIw+gzOAJ1/8v7DHS4tbXBOtnCzAkCVcq6ca9rYJe4ipVvXCBD /vKRsIibnwrgWLcqcBwMZuWWqXRiBHwUh6kMdku8= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-api@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh Subject: [PATCH v3 10/15] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Date: Thu, 23 May 2019 09:18:06 -0700 Message-Id: <20190523161811.6259-11-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523161811.6259-1-ebiggers@kernel.org> References: <20190523161811.6259-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a function for filesystems to call to implement the FS_IOC_MEASURE_VERITY ioctl. This ioctl retrieves the file measurement that fs-verity calculated for the given file and is enforcing for reads; i.e., reads that don't match this hash will fail. This ioctl can be used for authentication or logging of file measurements in userspace. See the "FS_IOC_MEASURE_VERITY" section of Documentation/filesystems/fsverity.rst for the documentation. Signed-off-by: Eric Biggers --- fs/verity/Makefile | 1 + fs/verity/measure.c | 57 ++++++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 11 ++++++++ 3 files changed, 69 insertions(+) create mode 100644 fs/verity/measure.c diff --git a/fs/verity/Makefile b/fs/verity/Makefile index 04b37475fd280..6f7675ae0a311 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -3,5 +3,6 @@ obj-$(CONFIG_FS_VERITY) += enable.o \ hash_algs.o \ init.o \ + measure.o \ open.o \ verify.o diff --git a/fs/verity/measure.c b/fs/verity/measure.c new file mode 100644 index 0000000000000..f29557c0ee3da --- /dev/null +++ b/fs/verity/measure.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/measure.c: ioctl to get a verity file's measurement + * + * Copyright 2019 Google LLC + */ + +#include "fsverity_private.h" + +#include + +/** + * fsverity_ioctl_measure() - get a verity file's measurement + * + * Retrieve the file measurement that the kernel is enforcing for reads from a + * verity file. See the "FS_IOC_MEASURE_VERITY" section of + * Documentation/filesystems/fsverity.rst for the documentation. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) +{ + const struct inode *inode = file_inode(filp); + struct fsverity_digest __user *uarg = _uarg; + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + struct fsverity_digest arg; + + vi = get_verity_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + hash_alg = vi->tree_params.hash_alg; + + /* + * The user specifies the digest_size their buffer has space for; we can + * return the digest if it fits in the available space. We write back + * the actual size, which may be shorter than the user-specified size. + */ + + if (get_user(arg.digest_size, &uarg->digest_size)) + return -EFAULT; + if (arg.digest_size < hash_alg->digest_size) + return -EOVERFLOW; + + memset(&arg, 0, sizeof(arg)); + arg.digest_algorithm = hash_alg - fsverity_hash_algs; + arg.digest_size = hash_alg->digest_size; + + if (copy_to_user(uarg, &arg, sizeof(arg))) + return -EFAULT; + + if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 9a84fe4bcfc88..df0b620c6897f 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -110,6 +110,10 @@ struct fsverity_operations { extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg); +/* measure.c */ + +extern int fsverity_ioctl_measure(struct file *filp, void __user *arg); + /* open.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); @@ -132,6 +136,13 @@ static inline int fsverity_ioctl_enable(struct file *filp, return -EOPNOTSUPP; } +/* measure.c */ + +static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) +{ + return -EOPNOTSUPP; +} + /* open.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp)