From patchwork Wed May 18 23:36:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 12854331 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 B1F1EC433FE for ; Wed, 18 May 2022 23:38:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231486AbiERXiJ (ORCPT ); Wed, 18 May 2022 19:38:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231575AbiERXiG (ORCPT ); Wed, 18 May 2022 19:38:06 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74315939F1 for ; Wed, 18 May 2022 16:37:44 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24IN6AdT017366 for ; Wed, 18 May 2022 16:37:44 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=LjQjeu05KJ6rwhAZwVJii+/tlMhhh5HkUUbhHoJms8c=; b=qOgnI2YbIv9/5s9m6mk6DoODtHG46NDgGVf3KaJrf8F2X+rm16Y6aE0mOIWrtI4PYm3o Tx1p4Awqz05hIkpwB1r/ToZl1YT4Iesd70+If1NeiO58HGiwrmVB0GX9eidlQh5xbw+0 7A/uGNqma9LqocbvWyNWD9kyIsoC8dZeitg= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3g4ck0m9vj-5 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 18 May 2022 16:37:44 -0700 Received: from twshared8307.18.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 18 May 2022 16:37:38 -0700 Received: by devvm225.atn0.facebook.com (Postfix, from userid 425415) id C6D65F3ED85D; Wed, 18 May 2022 16:37:12 -0700 (PDT) From: Stefan Roesch To: , , , , CC: , , Subject: [RFC PATCH v3 06/18] fs: Split off remove_needs_file_privs() __remove_file_privs() Date: Wed, 18 May 2022 16:36:57 -0700 Message-ID: <20220518233709.1937634-7-shr@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220518233709.1937634-1-shr@fb.com> References: <20220518233709.1937634-1-shr@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: iAVReF_yaXPJ5o-69CHHDFnODbxmaree X-Proofpoint-ORIG-GUID: iAVReF_yaXPJ5o-69CHHDFnODbxmaree X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-18_06,2022-05-17_02,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This splits off the function remove_needs_file_privs() from the function __remove_file_privs() from the function file_remove_privs(). No intended functional changes in this patch. Signed-off-by: Stefan Roesch --- fs/inode.c | 75 +++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 55 insertions(+), 20 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 9d9b422504d1..1bb8b7db836f 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2010,17 +2010,8 @@ static int __remove_privs(struct user_namespace *mnt_userns, return notify_change(mnt_userns, dentry, &newattrs, NULL); } -/* - * Remove special file priviledges (suid, capabilities) when file is written - * to or truncated. - */ -int file_remove_privs(struct file *file) +static int file_needs_remove_privs(struct inode *inode, struct dentry *dentry) { - struct dentry *dentry = file_dentry(file); - struct inode *inode = file_inode(file); - int kill; - int error = 0; - /* * Fast path for nothing security related. * As well for non-regular files, e.g. blkdev inodes. @@ -2030,16 +2021,42 @@ int file_remove_privs(struct file *file) if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) return 0; - kill = dentry_needs_remove_privs(dentry); - if (kill < 0) - return kill; - if (kill) - error = __remove_privs(file_mnt_user_ns(file), dentry, kill); + return dentry_needs_remove_privs(dentry); +} + +static int __file_remove_privs(struct file *file, struct inode *inode, + struct dentry *dentry, int kill) +{ + int error = 0; + + error = __remove_privs(file_mnt_user_ns(file), dentry, kill); if (!error) inode_has_no_xattr(inode); return error; } + +/** + * file_remove_privs - remove special file privileges (suid, capabilities) + * @file: file to remove privileges from + * + * When file is modified by a write or truncation ensure that special + * file privileges are removed. + * + * Return: 0 on success, negative errno on failure. + */ +int file_remove_privs(struct file *file) +{ + struct dentry *dentry = file_dentry(file); + struct inode *inode = file_inode(file); + int kill; + + kill = file_needs_remove_privs(inode, dentry); + if (kill <= 0) + return kill; + + return __file_remove_privs(file, inode, dentry, kill); +} EXPORT_SYMBOL(file_remove_privs); /** @@ -2090,18 +2107,36 @@ int file_update_time(struct file *file) } EXPORT_SYMBOL(file_update_time); -/* Caller must hold the file's inode lock */ +/** + * file_modified - handle mandated vfs changes when modifying a file + * @file: file that was modified + * + * When file has been modified ensure that special + * file privileges are removed and time settings are updated. + * + * Context: Caller must hold the file's inode lock. + * + * Return: 0 on success, negative errno on failure. + */ int file_modified(struct file *file) { - int err; + int ret; + struct dentry *dentry = file_dentry(file); + struct inode *inode = file_inode(file); /* * Clear the security bits if the process is not being run by root. * This keeps people from modifying setuid and setgid binaries. */ - err = file_remove_privs(file); - if (err) - return err; + ret = file_needs_remove_privs(inode, dentry); + if (ret < 0) + return ret; + + if (ret > 0) { + ret = __file_remove_privs(file, inode, dentry, ret); + if (ret) + return ret; + } if (unlikely(file->f_mode & FMODE_NOCMTIME)) return 0;