From patchwork Wed May 25 22:34:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 12861775 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 0DE3CC433EF for ; Wed, 25 May 2022 22:34:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 90D508D000B; Wed, 25 May 2022 18:34:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 896F48D0001; Wed, 25 May 2022 18:34:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 696468D000B; Wed, 25 May 2022 18:34:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 534C48D0001 for ; Wed, 25 May 2022 18:34:54 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 234616D1 for ; Wed, 25 May 2022 22:34:54 +0000 (UTC) X-FDA: 79505721708.25.67E19C5 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by imf03.hostedemail.com (Postfix) with ESMTP id E7CA22002B for ; Wed, 25 May 2022 22:34:40 +0000 (UTC) Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24PGta4k023116 for ; Wed, 25 May 2022 15:34:52 -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=Fx9Ydqg3gwwtYMpBZFzoM6rR2Mzc7v3vEUHPpZGCjiM=; b=MeDYB2LomSaP4KXdH5Ku/CMgVclc6ihnBQIHfM9xR8smHSftkoy5UdM6XtNdqVNyTXf4 jiT1Adfcz1A31eTDmliv30Tc2irO6Q3rD1MM9C/prXw81w1QmAT0F6H4FoLmhVx1uSbc 7uB2q3tVH96ztdx+lzu9NvucoMbAQrUyfhg= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3g93upsd8y-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 25 May 2022 15:34:52 -0700 Received: from twshared10560.18.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 25 May 2022 15:34:51 -0700 Received: by devvm225.atn0.facebook.com (Postfix, from userid 425415) id 191D7F9E1B5E; Wed, 25 May 2022 15:34:35 -0700 (PDT) From: Stefan Roesch To: , , , , CC: , , , Subject: [PATCH v5 07/16] fs: add __remove_file_privs() with flags parameter Date: Wed, 25 May 2022 15:34:23 -0700 Message-ID: <20220525223432.205676-8-shr@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220525223432.205676-1-shr@fb.com> References: <20220525223432.205676-1-shr@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: eTs4p9M-EMttdb8FESQRiixakE-yG6G1 X-Proofpoint-GUID: eTs4p9M-EMttdb8FESQRiixakE-yG6G1 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=2022-05-25_07,2022-05-25_02,2022-02-23_01 X-Rspam-User: X-Rspamd-Queue-Id: E7CA22002B X-Stat-Signature: f9xk7dwkf6s5otkuxmtoi3k8podzkuaw Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=MeDYB2Lo; spf=none (imf03.hostedemail.com: domain of "prvs=61440c7716=shr@fb.com" has no SPF policy when checking 67.231.145.42) smtp.mailfrom="prvs=61440c7716=shr@fb.com"; dmarc=pass (policy=reject) header.from=fb.com X-Rspamd-Server: rspam03 X-HE-Tag: 1653518080-795942 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 adds the function __remove_file_privs, which allows the caller to pass the kiocb flags parameter. No intended functional changes in this patch. Signed-off-by: Stefan Roesch --- fs/inode.c | 57 +++++++++++++++++++++++++++++++++++------------------- 1 file changed, 37 insertions(+), 20 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 9d9b422504d1..ac1cf5aa78c8 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2010,36 +2010,43 @@ 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_remove_privs(struct file *file, unsigned int flags) { struct dentry *dentry = file_dentry(file); struct inode *inode = file_inode(file); + int error; int kill; - int error = 0; - /* - * Fast path for nothing security related. - * As well for non-regular files, e.g. blkdev inodes. - * For example, blkdev_write_iter() might get here - * trying to remove privs which it is not allowed to. - */ if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) return 0; kill = dentry_needs_remove_privs(dentry); - if (kill < 0) + if (kill <= 0) return kill; - if (kill) - error = __remove_privs(file_mnt_user_ns(file), dentry, kill); + + if (flags & IOCB_NOWAIT) + return -EAGAIN; + + 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) +{ + return __file_remove_privs(file, 0); +} EXPORT_SYMBOL(file_remove_privs); /** @@ -2090,18 +2097,28 @@ 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; /* * 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_remove_privs(file, 0); + if (ret) + return ret; if (unlikely(file->f_mode & FMODE_NOCMTIME)) return 0;