From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C371C433B4 for ; Sat, 24 Apr 2021 14:06:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0351614A7 for ; Sat, 24 Apr 2021 14:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234144AbhDXOHF (ORCPT ); Sat, 24 Apr 2021 10:07:05 -0400 Received: from sender2-op-o12.zoho.com.cn ([163.53.93.243]:17109 "EHLO sender2-op-o12.zoho.com.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238056AbhDXOEp (ORCPT ); Sat, 24 Apr 2021 10:04:45 -0400 ARC-Seal: i=1; a=rsa-sha256; t=1619273037; cv=none; d=zoho.com.cn; s=zohoarc; b=aw1uNQKm+lclRfDoFl9A92VvG1sjtjoFi5F2KkO4Kb2VvCw2x8tpk5GxDbef7GhjYG3tCqQweFA+NM9Uk7UHCyv/izzBCCOgad82x5HTNRrFNKEOvrSaECoJJCOCosS1PXFxOjGKyJInvaZ5rjuUKaElQvYZogUjw8zX8S9dQ+0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com.cn; s=zohoarc; t=1619273037; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To; bh=DLyFUVZEVGrNMvopQICBA0uayw7m1MLk32GJMNo9GC0=; b=okRCVcnXk2OMD4rFB+amUqV0ZDeKawPR+MW7mIRZiTUK6AjER49Jp0qm09qliFAQSMenLbPlw/mLOJj2glTsAVQuYynJ2qK3KyrsaX3jtkTCENudvl8z2Ba/936x0BAi53GM9cmkzvDlFbFP1nvX5NXvCQ7w6/gm5nhqxChL+D4= ARC-Authentication-Results: i=1; mx.zoho.com.cn; dkim=pass header.i=mykernel.net; spf=pass smtp.mailfrom=cgxu519@mykernel.net; dmarc=pass header.from= header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1619273037; s=zohomail; d=mykernel.net; i=cgxu519@mykernel.net; h=From:To:Cc:Message-ID:Subject:Date:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Content-Type; bh=DLyFUVZEVGrNMvopQICBA0uayw7m1MLk32GJMNo9GC0=; b=MYaRK6zkqfFiwKlDZBQfGpmwnK5WY37GO9NT/4x2EMu8kzZ8W5knGQ4At2n5Vpnv ID6jXSwB53d5WAp5zhMyjQAYelzkjR+v1wME00zF0VctVFPcaK9AymDE1IdwQNxXVqF wGrq4FzporL8c1zBer1NE+xtTHBDxjx/EW7xsjd0= Received: from localhost.localdomain (159.75.42.226 [159.75.42.226]) by mx.zoho.com.cn with SMTPS id 1619273035620313.50233205996597; Sat, 24 Apr 2021 22:03:55 +0800 (CST) From: Chengguang Xu To: miklos@szeredi.hu Cc: linux-unionfs@vger.kernel.org, Chengguang Xu Message-ID: <20210424140316.485444-2-cgxu519@mykernel.net> Subject: [RFC PATCH 2/2] ovl: enhance write permission check for writable open Date: Sat, 24 Apr 2021 22:03:16 +0800 X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210424140316.485444-1-cgxu519@mykernel.net> References: <20210424140316.485444-1-cgxu519@mykernel.net> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoCNMailClient: External Content-Type: text/plain; charset=utf8 Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org Check upper file's write permission when open on writable mode. NOTE: lower files may be shared between differnt overlayfs instances, so we skip the check of lower file to avoid introducing interferes. Signed-off-by: Chengguang Xu --- fs/overlayfs/file.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 6e454a294046..1c3c24d07d01 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -144,12 +144,18 @@ static int ovl_real_fdget(const struct file *file, st= ruct fd *real) static int ovl_open(struct inode *inode, struct file *file) { =09struct file *realfile; +=09struct inode *upperinode; =09int err; =20 =09err =3D ovl_maybe_copy_up(file_dentry(file), file->f_flags); =09if (err) =09=09return err; =20 +=09upperinode =3D ovl_inode_upper(inode); +=09if (((file->f_mode & FMODE_WRITE) || file->f_flags & O_TRUNC) && +=09 (upperinode && atomic_read(&upperinode->i_writecount) < 0)) +=09=09return -ETXTBSY; + =09/* No longer need these flags, so don't pass them on to underlying fs *= / =09file->f_flags &=3D ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); =20 --=20 2.27.0