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=-0.7 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 A3DF3C004C9 for ; Tue, 7 May 2019 08:07:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 745C520578 for ; Tue, 7 May 2019 08:07:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="JciVvm+L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726924AbfEGIHe (ORCPT ); Tue, 7 May 2019 04:07:34 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:34018 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726561AbfEGIHe (ORCPT ); Tue, 7 May 2019 04:07:34 -0400 Received: by mail-io1-f65.google.com with SMTP id g84so5511701ioa.1 for ; Tue, 07 May 2019 01:07:33 -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=PEZVy9C+Z3ICJpvsn26xeqhO1e763sY5Q6qDpaKXZYs=; b=JciVvm+L8utAHEyD6sXVzJvXBWDDmLzUDru6e2Z6O7UUhE2uYt6t01+U9KuovpPXFK SVoBnOMRpR/M0jYtVyra7OBS30QfLjlk+10q3bu8kYLImeYysyY5BCIcTiaH8mJwq+lF dWqGpCsk3fQOh11X0sH7ux9nl+jIhQyw49PY4= 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=PEZVy9C+Z3ICJpvsn26xeqhO1e763sY5Q6qDpaKXZYs=; b=mHr7K37GlWx7bAuczNm/5QW4V6Y1DsmB2sBZcSjAgAuT+cJxNTMYU2vSJtF1R96KqT wZ48Gow0Xcw0R0T8qKVPsHS6uhsoBNN6ZtxlY4UKws6ebrEmJpJ0His8rhJWoSIETz7/ UXpC/Fp+O4225bEiQgorrdRbqNhlMNp2rSgySIovQngP/rKd0LR38qEmhwg7xzd/IVZy MBKemrXCfGeL5Y577Pb0stLu8CELaF8THf5EDu58H/wIIG/D4I8Wv+l5qJpjx2fshwTL 2PCrjPsp/m3OZEtTVpECNp/jMLQb3DnAOfNJEprKmyVLc4uN+nfemronlHp2cRCZ0knS RjUA== X-Gm-Message-State: APjAAAV5yPbhCiKnDVA3jKBm+MhKEu+XnE2wMoLMqeB2OwrbXBAEkIAF F7kqfFKwOehElg6ZPqXrwXjVBxCMxFs9/S1Lc0gfng== X-Google-Smtp-Source: APXvYqwG7Qhlz0ih1MCulvyvogd0VnUgA/VyGWATqTE+j80uOQBpCOYbueOcG/IyjFlZNjhBSEPaLFPbgVREQTdhdl0= X-Received: by 2002:a6b:ee04:: with SMTP id i4mr1817315ioh.246.1557216453174; Tue, 07 May 2019 01:07:33 -0700 (PDT) MIME-Version: 1.0 References: <20161205162559.GB17517@fieldses.org> <266c571f-e4e2-7c61-5ee2-8ece0c2d06e9@web.de> <20161206185806.GC31197@fieldses.org> <87bm0l4nra.fsf@notabene.neil.brown.name> <20190503153531.GJ12608@fieldses.org> In-Reply-To: <20190503153531.GJ12608@fieldses.org> From: Miklos Szeredi Date: Tue, 7 May 2019 04:07:21 -0400 Message-ID: Subject: Re: [PATCH] overlayfs: ignore empty NFSv4 ACLs in ext4 upperdir To: "J. Bruce Fields" Cc: NeilBrown , Andreas Gruenbacher , =?UTF-8?Q?Andreas_Gr=C3=BCnbacher?= , Patrick Plagwitz , "linux-unionfs@vger.kernel.org" , Linux NFS list , Linux FS-devel Mailing List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, May 3, 2019 at 11:35 AM J. Bruce Fields wrote: > > On Thu, May 02, 2019 at 12:02:33PM +1000, NeilBrown wrote: > > Silently not copying the ACLs is probably not a good idea as it might > > result in inappropriate permissions being given away. So if the > > sysadmin wants this (and some clearly do), they need a way to > > explicitly say "I accept the risk". > > So, I feel like silently copying ACLs up *also* carries a risk, if that > means switching from server-enforcement to client-enforcement of those > permissions. That's not correct: permissions are checked on the overlay layer, regardless of where the actual file resides. For filesystems using a server enforced permission model that means possibly different permissions for accesses through overlayfs than for accesses without overlayfs. Apparently this is missing from the documentation and definitely needs to be added. So I think it's perfectly fine to allow copying up ACLs, as long as the ACL is representable on the upper fs. If that cannot be ensured, then the only sane thing to do is to disable ACL checking across the overlay ("noacl" option). Thanks, Miklos