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=-3.8 required=3.0 tests=BAYES_00, 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 59544C433E0 for ; Thu, 14 Jan 2021 17:56:00 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 0221C23B54 for ; Thu, 14 Jan 2021 17:55:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0221C23B54 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=containers-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 41AC986BE6; Thu, 14 Jan 2021 17:55:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rz-NqdD2bv2F; Thu, 14 Jan 2021 17:55:56 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 4E7FC868F8; Thu, 14 Jan 2021 17:55:56 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 41497C088B; Thu, 14 Jan 2021 17:55:56 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id F3AB6C013A for ; Thu, 14 Jan 2021 17:55:54 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id E47F286BA4 for ; Thu, 14 Jan 2021 17:55:54 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9Pf04HW4Fnxr for ; Thu, 14 Jan 2021 17:55:53 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by whitealder.osuosl.org (Postfix) with ESMTPS id A8BD8868F8 for ; Thu, 14 Jan 2021 17:55:53 +0000 (UTC) Received: from ip5f5af0a0.dynamic.kabel-deutschland.de ([95.90.240.160] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1l06pa-0006dG-Cq; Thu, 14 Jan 2021 17:54:46 +0000 Date: Thu, 14 Jan 2021 18:54:41 +0100 From: Christian Brauner To: "Darrick J. Wong" Subject: Re: [PATCH v5 00/42] idmapped mounts Message-ID: <20210114175441.v5cbtzad3ejjcjsw@wittgenstein> References: <20210112220124.837960-1-christian.brauner@ubuntu.com> <20210114171241.GA1164240@magnolia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210114171241.GA1164240@magnolia> Cc: Lennart Poettering , Mimi Zohar , David Howells , Andreas Dilger , containers@lists.linux-foundation.org, Tycho Andersen , Paul Moore , Jonathan Corbet , smbarber@chromium.org, Christoph Hellwig , Alban Crequy , linux-ext4@vger.kernel.org, Mrunal Patel , Kees Cook , Arnd Bergmann , selinux@vger.kernel.org, Josh Triplett , Seth Forshee , Aleksa Sarai , Alexander Viro , Andy Lutomirski , OGAWA Hirofumi , Geoffrey Thomas , James Bottomley , John Johansen , Theodore Tso , Dmitry Kasatkin , Stephen Smalley , linux-xfs@vger.kernel.org, linux-security-module@vger.kernel.org, "Eric W. Biederman" , linux-api@vger.kernel.org, Casey Schaufler , linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, Linus Torvalds , Todd Kjos X-BeenThere: containers@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux Containers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: containers-bounces@lists.linux-foundation.org Sender: "Containers" On Thu, Jan 14, 2021 at 09:12:41AM -0800, Darrick J. Wong wrote: > On Tue, Jan 12, 2021 at 11:00:42PM +0100, Christian Brauner wrote: > > Hey everyone, > > > > The only major change is the inclusion of hch's patch to port XFS to > > support idmapped mounts. Thanks to Christoph for doing that work. > > Yay :) > > > (For a full list of major changes between versions see the end of this > > cover letter. > > Please also note the large xfstests testsuite in patch 42 that has been > > kept as part of this series. It verifies correct vfs behavior with and > > without idmapped mounts including covering newer vfs features such as > > io_uring. > > I currently still plan to target the v5.12 merge window.) > > > > With this patchset we make it possible to attach idmappings to mounts, > > i.e. simply put different bind mounts can expose the same file or > > directory with different ownership. > > Shifting of ownership on a per-mount basis handles a wide range of > > long standing use-cases. Here are just a few: > > - Shifting of a subset of ownership-less filesystems (vfat) for use by > > multiple users, effectively allowing for DAC on such devices > > (systemd, Android, ...) > > - Allow remapping uid/gid on external filesystems or paths (USB sticks, > > network filesystem, ...) to match the local system's user and groups. > > (David Howells intends to port AFS as a first candidate.) > > - Shifting of a container rootfs or base image without having to mangle > > every file (runc, Docker, containerd, k8s, LXD, systemd ...) > > - Sharing of data between host or privileged containers with > > unprivileged containers (runC, Docker, containerd, k8s, LXD, ...) > > - Data sharing between multiple user namespaces with incompatible maps > > (LXD, k8s, ...) > > That sounds neat. AFAICT, the VFS passes the filesystem a mount userns > structure, which is then carried down the call stack to whatever > functions actually care about mapping kernel [ug]ids to their ondisk > versions? Yes. This requires not too many changes to the actual filesystems as you can see from the xfs conversion that Christoph has done. > > Does quota still work after this patchset is applied? There isn't any > mention of that in the cover letter and I don't see a code patch, so > does that mean everything just works? I'm particularly curious about The most interesting quota codepaths I audited are dquot_transfer that transfers quota from one inode to another one during setattr. That happens via a struct iattr which will already contain correctly translated ia_uid and ia_gid values according to the mount the caller is coming from. I'll take another close look at that now and add tests for that if I can find some in xfstests. > whether there can exist processes with CAP_SYS_ADMIN and an idmapped > mount? Syscalls like bulkstat and quotactl present file [ug]ids to Yes, that should be possible. > programs, but afaict there won't be any translating going on? quotactl operates on the superblock. So the caller would need a mapping in the user namespace of the superblock. That doesn't need to change. But we could in the future extend this to be on a per-mount basis if this was a desired use-case. I don't think it needs to happen right now though. > > (To be fair, bulkstat is an xfs-only thing, but quota control isn't.) I'm certain we'll find more things to cover after the first version has landed. :) We for sure won't cover it all in the first iteration. > > I'll start skimming the patchset... Thanks! Christian _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/containers