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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 4F3DFC76192 for ; Tue, 16 Jul 2019 08:04:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 23D50206C2 for ; Tue, 16 Jul 2019 08:04:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Kpm8zy9B" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23D50206C2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iF4cBXqYxyMzHmjAmIOL2w+MODk5k2xmV8FBzeLBEus=; b=Kpm8zy9BbXsZYmaFzvkXEB0cA w4F5rc5RuMO4TENa27aANHDIpaWPzmpjsvb+DUQbIvlJnc++nryM/RKUlhanHBL1zbu0JUMXqcuKq q3h5aJA+V897DyweCLe8nlzvTIDyBgRCC+YyRtv8MgdcTKsl2JSFHFilEcEfI483C8YG1epKfjuNx Aj9+KAvfz2x66GIMP8o0oACLjVO++MePbMOopl9uRITa5tTteoa/mNKpLYE2bJze+wFqd3tt6wvN3 UeURVjF7SWDWigkhFHsO1Zx730f0m82jUV8qWuRvL2b+ebgWnZFogXX3omcwsut47H+1pNI1nwWuD umNsOiPMw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hnIRZ-0006uD-7K; Tue, 16 Jul 2019 08:04:13 +0000 Received: from mx1.mailbox.org ([80.241.60.212]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hnIRV-0006sK-8u for linux-arm-kernel@lists.infradead.org; Tue, 16 Jul 2019 08:04:11 +0000 Received: from smtp1.mailbox.org (smtp1.mailbox.org [80.241.60.240]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx1.mailbox.org (Postfix) with ESMTPS id 65FB4506CB; Tue, 16 Jul 2019 10:03:57 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by gerste.heinlein-support.de (gerste.heinlein-support.de [91.198.250.173]) (amavisd-new, port 10030) with ESMTP id FP9J3tccLygu; Tue, 16 Jul 2019 10:03:51 +0200 (CEST) Date: Tue, 16 Jul 2019 18:03:38 +1000 From: Aleksa Sarai To: Al Viro Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190716080338.al4cnwdfvdbpzh3r@yavin> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> <20190712105745.nruaftgeat6irhzr@yavin> <20190712123924.GK17978@ZenIV.linux.org.uk> <20190712125552.GL17978@ZenIV.linux.org.uk> <20190712132553.GN17978@ZenIV.linux.org.uk> <20190712150026.GO17978@ZenIV.linux.org.uk> <20190713024153.GA3817@ZenIV.linux.org.uk> <20190714035826.GQ17978@ZenIV.linux.org.uk> MIME-Version: 1.0 In-Reply-To: <20190714035826.GQ17978@ZenIV.linux.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190716_010409_617594_C81CBF3A X-CRM114-Status: GOOD ( 24.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Tetsuo Handa , Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , raven@themaw.net, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , paul@paul-moore.com, Aleksa Sarai , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, Andy Lutomirski , Shuah Khan , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, rgb@redhat.com, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Content-Type: multipart/mixed; boundary="===============6358504605546429070==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============6358504605546429070== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lshvdcpckvdb4crm" Content-Disposition: inline --lshvdcpckvdb4crm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019-07-14, Al Viro wrote: > On Sat, Jul 13, 2019 at 03:41:53AM +0100, Al Viro wrote: > > On Fri, Jul 12, 2019 at 04:00:26PM +0100, Al Viro wrote: > > > On Fri, Jul 12, 2019 at 02:25:53PM +0100, Al Viro wrote: > > >=20 > > > > if (flags & LOOKUP_BENEATH) { > > > > nd->root =3D nd->path; > > > > if (!(flags & LOOKUP_RCU)) > > > > path_get(&nd->root); > > > > else > > > > nd->root_seq =3D nd->seq; > > >=20 > > > BTW, this assignment is needed for LOOKUP_RCU case. Without it > > > you are pretty much guaranteed that lazy pathwalk will fail, > > > when it comes to complete_walk(). > > >=20 > > > Speaking of which, what would happen if LOOKUP_ROOT/LOOKUP_BENEATH > > > combination would someday get passed? > >=20 > > I don't understand what's going on with ->r_seq in there - your > > call of path_is_under() is after having (re-)sampled rename_lock, > > but if that was the only .. in there, who's going to recheck > > the value? For that matter, what's to guarantee that the thing > > won't get moved just as you are returning from handle_dots()? > >=20 > > IOW, what does LOOKUP_IN_ROOT guarantee for caller (openat2())? >=20 > Sigh... Usual effects of trying to document things: >=20 > 1) LOOKUP_NO_EVAL looks bogus. It had been introduced by commit 57d46577= 16ac > (audit: ignore fcaps on umount) and AFAICS it's crap. It is set in > ksys_umount() and nowhere else. It's ignored by everything except > filename_mountpoint(). The thing is, call graph for filename_mountpoint() > is > filename_mountpoint() > <- user_path_mountpoint_at() > <- ksys_umount() > <- kern_path_mountpoint() > <- autofs_dev_ioctl_ismountpoint() > <- find_autofs_mount() > <- autofs_dev_ioctl_open_mountpoint() > <- autofs_dev_ioctl_requester() > <- autofs_dev_ioctl_ismountpoint() > In other words, that flag is basically "was filename_mountpoint() > been called by umount(2) or has it come from an autofs ioctl?". > And looking at the rationale in that commit, autofs ioctls need > it just as much as umount(2) does. Why is it not set for those > as well? And why is it conditional at all? In addition, LOOKUP_NO_EVAL =3D=3D LOOKUP_OPEN (0x100). Is that meant to be the case? Also I just saw you have a patch in work.namei that fixes this up -- do you want me to rebase on top of that? --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --lshvdcpckvdb4crm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSxZm6dtfE8gxLLfYqdlLljIbnQEgUCXS2E1wAKCRCdlLljIbnQ EvUWAP4hDKNKmCaghR/nSF7B9A3mjchQtut9n7vItMKjRPJjLAD9GRABOJCnZ47q TqUSuZfxKfq260PQMTx91hQd/K+//QE= =XoHc -----END PGP SIGNATURE----- --lshvdcpckvdb4crm-- --===============6358504605546429070== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============6358504605546429070==--