From patchwork Mon Jul 1 15:32:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 11026367 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 673441398 for ; Mon, 1 Jul 2019 15:34:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 57EC028703 for ; Mon, 1 Jul 2019 15:34:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4C37D28707; Mon, 1 Jul 2019 15:34:29 +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=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 E723E286E6 for ; Mon, 1 Jul 2019 15:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729587AbfGAPe2 (ORCPT ); Mon, 1 Jul 2019 11:34:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:42740 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729425AbfGAPeH (ORCPT ); Mon, 1 Jul 2019 11:34:07 -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 028242184B; Mon, 1 Jul 2019 15:34:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561995246; bh=K+NemXguOV0dTgX86NywEULK+bYljcPqx+IErwSAPPw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IMGQtvzuI50Dsn8CxBQL7EJkWsCPSlPlnr3uT3sckNaS+M+7jQiOu/+P2UKYLTGUX HGNxdlYnCQTatrtZzftTHzKbyQi8HpFUD8TlWn0+Tse56dyxuAILRgwoWXIa/9yk3R YFU1SzBnE2QvN+fsGDbpt04NVgwmnZ4B3a0mzVrs= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-integrity@vger.kernel.org, Jaegeuk Kim , "Theodore Y . Ts'o" , Victor Hsieh , Chandan Rajendra , Dave Chinner , Christoph Hellwig , "Darrick J . Wong" , Linus Torvalds Subject: [PATCH v6 08/17] fs-verity: add the hook for file ->setattr() Date: Mon, 1 Jul 2019 08:32:28 -0700 Message-Id: <20190701153237.1777-9-ebiggers@kernel.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190701153237.1777-1-ebiggers@kernel.org> References: <20190701153237.1777-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a function fsverity_prepare_setattr() which filesystems that support fs-verity must call to deny truncates of verity files. Reviewed-by: Theodore Ts'o Reviewed-by: Jaegeuk Kim Signed-off-by: Eric Biggers --- fs/verity/open.c | 21 +++++++++++++++++++++ include/linux/fsverity.h | 7 +++++++ 2 files changed, 28 insertions(+) diff --git a/fs/verity/open.c b/fs/verity/open.c index 8013f77f907e..2cb2fe8082bf 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -295,6 +295,27 @@ int fsverity_file_open(struct inode *inode, struct file *filp) } EXPORT_SYMBOL_GPL(fsverity_file_open); +/** + * fsverity_prepare_setattr() - prepare to change a verity inode's attributes + * @dentry: dentry through which the inode is being changed + * @attr: attributes to change + * + * Verity files are immutable, so deny truncates. This isn't covered by the + * open-time check because sys_truncate() takes a path, not a file descriptor. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr) +{ + if (IS_VERITY(d_inode(dentry)) && (attr->ia_valid & ATTR_SIZE)) { + pr_debug("Denying truncate of verity file (ino %lu)\n", + d_inode(dentry)->i_ino); + return -EPERM; + } + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_prepare_setattr); + /** * fsverity_cleanup_inode() - free the inode's verity info, if present * diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 09b04dab6452..cbd0f84e1620 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -46,6 +46,7 @@ static inline struct fsverity_info *fsverity_get_info(const struct inode *inode) /* open.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); +extern int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr); extern void fsverity_cleanup_inode(struct inode *inode); #else /* !CONFIG_FS_VERITY */ @@ -62,6 +63,12 @@ static inline int fsverity_file_open(struct inode *inode, struct file *filp) return IS_VERITY(inode) ? -EOPNOTSUPP : 0; } +static inline int fsverity_prepare_setattr(struct dentry *dentry, + struct iattr *attr) +{ + return IS_VERITY(d_inode(dentry)) ? -EOPNOTSUPP : 0; +} + static inline void fsverity_cleanup_inode(struct inode *inode) { }