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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C8326C12002 for ; Wed, 21 Jul 2021 13:14:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A2664610D2 for ; Wed, 21 Jul 2021 13:14:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236827AbhGUMeS (ORCPT ); Wed, 21 Jul 2021 08:34:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231680AbhGUMeR (ORCPT ); Wed, 21 Jul 2021 08:34:17 -0400 Received: from mail-vk1-xa34.google.com (mail-vk1-xa34.google.com [IPv6:2607:f8b0:4864:20::a34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2216C061574 for ; Wed, 21 Jul 2021 06:14:53 -0700 (PDT) Received: by mail-vk1-xa34.google.com with SMTP id v186so519833vka.1 for ; Wed, 21 Jul 2021 06:14:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BsCammn3h4jNtxj8Zw1Mb6jUfKsu4I4W+UoqAu+qlzY=; b=BtMs3ozmUQU514MOktu2TwI10XCm5YcwhOiafrUvvSt5kgzQWEVv5yeETnTVh1Qb8P p5TGPFRKkvHtyaGW4nzStl1p+WIXlNxFy3hSMVN7MA/UfEgoaLT82ojcEUXaUC9bu1vY xkxK+6UEWHkZvKQgVwjC57gWu/QnyAef8yB58= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BsCammn3h4jNtxj8Zw1Mb6jUfKsu4I4W+UoqAu+qlzY=; b=srEUqhjz9t1KOwSOs4DgiiDr9ICOuT+ybH6Au5Z5L4OnXi9g6L4M87804ZRqR7h1WN MD9NcseFrS0DgzTmHMZelV0ywKQv70IZ9m+AK7Pm7MtmLQoBOmm61QQLcQb496su/y0R 566/POb40MMQWM+14183xjut+oJe0NtuspwgRBr2h71LZP3cwu46D8QVn7pZI+MU858l 62UxRtZdgL2ASKn36lGl6wc0R3OfRfVI2lWRbetPMmaDNzuEJNxsfXNUGbFsTloFdUQE TWOpDX58+DTERoQY9fZoKChnipAcU5Cfa/VPA894J28bsMaT4wrSzs+Oeixf4+o3W2iQ FBZQ== X-Gm-Message-State: AOAM531UxOt/SJXN5yGyx+iUt9CZQ3/DDxkKZ9TeP6LOveEgvFm93sph 3vmXRxPKVgy5wPJh51koPDvN759PKS2tDzVXmFR5kw== X-Google-Smtp-Source: ABdhPJzZagwtOCRyARVRFIPP5WYrB+JoM+046KL9UyY8pt0SfXFEfav89cEh4SsJhREgwmCPl3Z5Z4cEEZWD1laT5Fs= X-Received: by 2002:ac5:c5a9:: with SMTP id f9mr1879818vkl.3.1626873292657; Wed, 21 Jul 2021 06:14:52 -0700 (PDT) MIME-Version: 1.0 References: <20210424140316.485444-1-cgxu519@mykernel.net> <20210424140316.485444-2-cgxu519@mykernel.net> In-Reply-To: <20210424140316.485444-2-cgxu519@mykernel.net> From: Miklos Szeredi Date: Wed, 21 Jul 2021 15:14:42 +0200 Message-ID: Subject: Re: [RFC PATCH 2/2] ovl: enhance write permission check for writable open To: Chengguang Xu Cc: overlayfs Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Sat, 24 Apr 2021 at 16:04, Chengguang Xu wrote: > > Check upper file's write permission when open on writable mode. This should already be done in ovl_open() -> ovl_open_realfile() -> open_with_fake_path() -> do_dentry_open(). Do you have a test case indicating that the writecount test is not working? Thanks, Miklos > > 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, struct fd *real) > static int ovl_open(struct inode *inode, struct file *file) > { > struct file *realfile; > + struct inode *upperinode; > int err; > > err = ovl_maybe_copy_up(file_dentry(file), file->f_flags); > if (err) > return err; > > + upperinode = ovl_inode_upper(inode); > + if (((file->f_mode & FMODE_WRITE) || file->f_flags & O_TRUNC) && > + (upperinode && atomic_read(&upperinode->i_writecount) < 0)) > + return -ETXTBSY; > + > /* No longer need these flags, so don't pass them on to underlying fs */ > file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); > > -- > 2.27.0 > >