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[209.132.180.67]) by mx.google.com with ESMTP id b66si3261948pfa.104.2019.05.03.10.28.02; Fri, 03 May 2019 10:28:28 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-nfs-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=e0EVyFqE; spf=pass (google.com: best guess record for domain of linux-nfs-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-nfs-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726789AbfECR0O (ORCPT + 99 others); Fri, 3 May 2019 13:26:14 -0400 Received: from mail-yw1-f68.google.com ([209.85.161.68]:34355 "EHLO mail-yw1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbfECR0O (ORCPT ); Fri, 3 May 2019 13:26:14 -0400 Received: by mail-yw1-f68.google.com with SMTP id u14so4901288ywe.1; Fri, 03 May 2019 10:26:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=DocVtyuDeHQRG32pg5UwnwTFNToS8yf9UPgc4/qdeYU=; b=e0EVyFqETr57jizVPCvWUQZE7uxN6M2tTc+6UdysEiRdPcr1cUNisT47b8063Pc99g UOzOrmQa122NOXaPegyqwwhWpRsgnY4VhirbDLzS218imz+LgrEM5hQtIDAsBfl0BC3m OGmovcqBiT9YF2y4+QPlnfZhicVEvytgX5iu5ClPNMrbSYh/7TsFDq2/u62EJ2D1lBwv RrUBkzMqGsG+usGlzaJSsSYmubj2awu1HoPbW/2IiVdYlh6oRdW0qKj7vyj/RQs87ZUL fStnyKsmIJi+HGwogJQtm+woSVwvgBeC5/TWuNpjwt++JQMNG9NpAZZdtp+hrVt9rLwL 2Pyw== 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:content-transfer-encoding; bh=DocVtyuDeHQRG32pg5UwnwTFNToS8yf9UPgc4/qdeYU=; b=nSxqj+VRlnu2s41a7q7JhuDSjSDrfiHZYZ1Opk3A5A3PC2RAhRe7IhCxzzBsPH2Qys jN4/Nm4O8iUDo4mY/Tb3oAcRdst8vhYyEqvLYjxTmCD+wX10JPoBHEpcmvmq8FZNspp1 hGGVTaPLhpMA7N9eNYDRgyW9uzZ2ZTs9d4WP0ZyQ+GihULJnl3xxJmsw+UlOi50eawSE OSBNsZ8hKudxWjP6t5rcitRlpJYJipS1NEvTrdVCG5jEKQzeWVU1/YxvqzrPCpwFH4q/ r6egOcGfXaBGqOLJnHzt+EUdJOz6A1Q5chXEmgtG3K6dq8R1XDyT9riM1aFr/piMnjwS RkJw== X-Gm-Message-State: APjAAAVJfRzOjf7u/v/+eb6QHjUsM/lwjttrMoel0nAkRbdUZ2lc9hun qkUNzGFLp/YE8CurusfdrxCDTsDwxz0EMWXSWiFVSkJQkik= X-Received: by 2002:a25:74c9:: with SMTP id p192mr8777605ybc.507.1556904373293; Fri, 03 May 2019 10:26:13 -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: Amir Goldstein Date: Fri, 3 May 2019 13:26:01 -0400 Message-ID: Subject: Re: [PATCH] overlayfs: ignore empty NFSv4 ACLs in ext4 upperdir To: "J. Bruce Fields" Cc: NeilBrown , Andreas Gruenbacher , Miklos Szeredi , =?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" Content-Transfer-Encoding: quoted-printable Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Fri, May 3, 2019 at 12:03 PM J. Bruce Fields wrot= e: > > On Thu, May 02, 2019 at 12:02:33PM +1000, NeilBrown wrote: > > On Tue, Dec 06 2016, J. Bruce Fields wrote: > > > > > On Tue, Dec 06, 2016 at 02:18:31PM +0100, Andreas Gruenbacher wrote: > > >> On Tue, Dec 6, 2016 at 11:08 AM, Miklos Szeredi = wrote: > > >> > On Tue, Dec 6, 2016 at 12:24 AM, Andreas Gr=C3=BCnbacher > > >> > wrote: > > >> >> 2016-12-06 0:19 GMT+01:00 Andreas Gr=C3=BCnbacher : > > >> > > > >> >>> It's not hard to come up with a heuristic that determines if a > > >> >>> system.nfs4_acl value is equivalent to a file mode, and to ignor= e the > > >> >>> attribute in that case. (The file mode is transmitted in its own > > >> >>> attribute already, so actually converting .) That way, overlayfs= could > > >> >>> still fail copying up files that have an actual ACL. It's still = an > > >> >>> ugly hack ... > > >> >> > > >> >> Actually, that kind of heuristic would make sense in the NFS clie= nt > > >> >> which could then hide the "system.nfs4_acl" attribute. > > >> > > > >> > Even simpler would be if knfsd didn't send the attribute if not > > >> > necessary. Looks like there's code actively creating the nfs4_acl= on > > >> > the wire even if the filesystem had none: > > >> > > > >> > pacl =3D get_acl(inode, ACL_TYPE_ACCESS); > > >> > if (!pacl) > > >> > pacl =3D posix_acl_from_mode(inode->i_mode, GFP_KERNEL); > > >> > > > >> > What's the point? > > >> > > >> That's how the protocol is specified. > > > > > > Yep, even if we could make that change to nfsd it wouldn't help the > > > client with the large number of other servers that are out there > > > (including older knfsd's). > > > > > > --b. > > > > > >> (I'm not saying that that's very helpful.) > > >> > > >> Andreas > > > > Hi everyone..... > > I have a customer facing this problem, and so stumbled onto the email > > thread. > > Unfortunately it didn't resolve anything. Maybe I can help kick thing= s > > along??? > > > > The core problem here is that NFSv4 and ext4 use different and largely > > incompatible ACL implementations. There is no way to accurately > > translate from one to the other in general (common specific examples > > can be converted). > > > > This means that either: > > 1/ overlayfs cannot use ext4 for upper and NFS for lower (or vice > > versa) or > > 2/ overlayfs need to accept that sometimes it cannot copy ACLs, and > > that is OK. > > > > 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. > > Sorry, I know we had another thread recently about permissions in this > situation, and I've forgotten the conclusion. > > Out of curiosity, what's done with selinux labels? > overlayfs calls security_inode_copy_up_xattr(name) which can fail (<0) allow (0) or skip(1). selinux_inode_copy_up_xattr() as well as smack_inode_copy_up_xattr() skip their own xattr on copy up and fail any other xattr copy up. Thanks, Amir.