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=-6.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 2B7BAC04EB9 for ; Mon, 3 Dec 2018 18:53:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA1BE208A3 for ; Mon, 3 Dec 2018 18:53:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="gsgifdt/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA1BE208A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726042AbeLCSxK (ORCPT ); Mon, 3 Dec 2018 13:53:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:60894 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725973AbeLCSxK (ORCPT ); Mon, 3 Dec 2018 13:53:10 -0500 Received: from gmail.com (unknown [104.132.1.85]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E0B6720850; Mon, 3 Dec 2018 18:53:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543863188; bh=qTtQoEAQMnRL2UxwLwNdoeClO9iiUNdc2TRBaQckeho=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gsgifdt//G9ifsf4XKK2cGPMku3OsSypJU6QVfcOWV40ui6pRX5sS7JDp2MHSS5cM 519xZl+vQMMB+nPeORpDI9rHR5QrHEDTbrM1eYZEDBCOlogxCHarVSAMQ1GtGgwDAx 2Us507pJBgbAtIeFZJW7gs6ywwO0M8ys5ka/RDJc= Date: Mon, 3 Dec 2018 10:53:06 -0800 From: Eric Biggers To: Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, olga.kornievskaia@gmail.com, linux-nfs@vger.kernel.org, linux-unionfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org Subject: Re: [PATCH 05/11] vfs: use inode_permission in copy_file_range() Message-ID: <20181203185305.GA32539@gmail.com> References: <20181203083416.28978-1-david@fromorbit.com> <20181203083416.28978-6-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181203083416.28978-6-david@fromorbit.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, Dec 03, 2018 at 07:34:10PM +1100, Dave Chinner wrote: > From: Dave Chinner > > Similar to FI_DEDUPERANGE, make copy_file_range() check that we have > write permissions to the destination inode. > > Signed-off-by: Dave Chinner > --- > mm/filemap.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 0a170425935b..876df5275514 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -3013,6 +3013,11 @@ int generic_copy_file_checks(struct file *file_in, loff_t pos_in, > (file_out->f_flags & O_APPEND)) > return -EBADF; > > + /* may sure we really are allowed to write to the destination inode */ > + ret = inode_permission(inode_out, MAY_WRITE); > + if (ret < 0) > + return ret; > + > /* Ensure offsets don't wrap. */ > if (pos_in + count < pos_in || pos_out + count < pos_out) > return -EOVERFLOW; > -- > 2.19.1 > Why? The file descriptor was already checked for write permission above: if (!(file_in->f_mode & FMODE_READ) || !(file_out->f_mode & FMODE_WRITE) || (file_out->f_flags & O_APPEND)) return -EBADF; Yes, that doesn't detect removing write permission from the *inode*, but write() doesn't either. - Eric