From patchwork Fri May 20 18:36:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 12857269 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E46D8C4332F for ; Fri, 20 May 2022 18:37:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C70C28D0003; Fri, 20 May 2022 14:37:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BABEF8D0001; Fri, 20 May 2022 14:37:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 994EF8D0003; Fri, 20 May 2022 14:37:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 729EF8D0001 for ; Fri, 20 May 2022 14:37:38 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 43BA661AF6 for ; Fri, 20 May 2022 18:37:38 +0000 (UTC) X-FDA: 79486979796.21.AD29F5C Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by imf25.hostedemail.com (Postfix) with ESMTP id 5241AA00C4 for ; Fri, 20 May 2022 18:37:11 +0000 (UTC) Received: from pps.filterd (m0148460.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24KHT2cT021415 for ; Fri, 20 May 2022 11:37:36 -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=gC1n0WZzBxoCH+wECZ6OHpXO2phJjsKw0caLbf5hcbDm/QvQFGWdItF+soh3rCPMVpw3 NV9utU1xIasPiv5kK8jKdtsEvOru5f4B1d2whSGYC8uACCB+Uns/faMnYgy6i33432xR D8nCGT0u8IIAyAPo6cVy1QnbDrDmavascTE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3g5rgj8vh7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 20 May 2022 11:37:36 -0700 Received: from snc-exhub201.TheFacebook.com (2620:10d:c085:21d::7) by snc-exhub103.TheFacebook.com (2620:10d:c085:11d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Fri, 20 May 2022 11:37:34 -0700 Received: from twshared8307.18.frc3.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:21d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Fri, 20 May 2022 11:37:34 -0700 Received: by devvm225.atn0.facebook.com (Postfix, from userid 425415) id 8E9BDF5E5B31; Fri, 20 May 2022 11:37:16 -0700 (PDT) From: Stefan Roesch To: , , , , CC: , , , Subject: [RFC PATCH v4 09/17] fs: Split off remove_needs_file_privs() __remove_file_privs() Date: Fri, 20 May 2022 11:36:38 -0700 Message-ID: <20220520183646.2002023-10-shr@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220520183646.2002023-1-shr@fb.com> References: <20220520183646.2002023-1-shr@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: DviDX8p0HcI-235lVzqxay0Ozcvr5lpo X-Proofpoint-ORIG-GUID: DviDX8p0HcI-235lVzqxay0Ozcvr5lpo 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=2022-05-20_06,2022-05-20_02,2022-02-23_01 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 5241AA00C4 X-Stat-Signature: 7nfyb91o4y44jn4p3w4nujyoobh14933 X-Rspam-User: Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=gC1n0WZz; spf=none (imf25.hostedemail.com: domain of "prvs=6139886598=shr@fb.com" has no SPF policy when checking 67.231.153.30) smtp.mailfrom="prvs=6139886598=shr@fb.com"; dmarc=pass (policy=reject) header.from=fb.com X-HE-Tag: 1653071831-449542 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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;