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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 AA0B2C4741F for ; Sun, 1 Nov 2020 14:45:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 709B62225C for ; Sun, 1 Nov 2020 14:45:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="TXCoiwu2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726813AbgKAOpr (ORCPT ); Sun, 1 Nov 2020 09:45:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726458AbgKAOpr (ORCPT ); Sun, 1 Nov 2020 09:45:47 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 126A6C0617A6; Sun, 1 Nov 2020 06:45:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=nVK1pkiziQ92kaQ/g40iRxNnuEGCqnYOXHidgZ1R1Sw=; b=TXCoiwu2LqeUACFNts/RtI1sNW AL3/iF3Fr92m5DK6yU59krsIzhlhvGU7WbruotfIWfVcCX9v9+eh0ewIy0MuYWUSA1pUjoHsM6UBa j7uutfCrr9Tr+r/GDt4Ug74KoxS5mAef22Yya/Fj4vg6YgJf/E/UEFPF/BlX/Jvy9xLPOK5ATkBB2 C/PkZYggOKQKIJGaVcnwY1WLgrcNW/vrVsKWXvte84lE6NZORjZd/hKVufdtiGryZ+Ks8yb16iik+ LQbI90fVQmt3eNgP583eFcHO3rYz2MkTxwhnEULzH/qY2/LT2RUFWQdQgdOriWrA701EA00Ks4GDQ 2EqUMtDg==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZEc4-0006Y5-Kp; Sun, 01 Nov 2020 14:45:44 +0000 Date: Sun, 1 Nov 2020 14:45:44 +0000 From: Christoph Hellwig To: Christian Brauner Cc: Alexander Viro , Christoph Hellwig , linux-fsdevel@vger.kernel.org, John Johansen , James Morris , Mimi Zohar , Dmitry Kasatkin , Stephen Smalley , Casey Schaufler , Arnd Bergmann , Andreas Dilger , OGAWA Hirofumi , Geoffrey Thomas , Mrunal Patel , Josh Triplett , Andy Lutomirski , Amir Goldstein , Miklos Szeredi , Theodore Tso , Alban Crequy , Tycho Andersen , David Howells , James Bottomley , Jann Horn , Seth Forshee , St??phane Graber , Aleksa Sarai , Lennart Poettering , "Eric W. Biederman" , smbarber@chromium.org, Phil Estes , Serge Hallyn , Kees Cook , Todd Kjos , Jonathan Corbet , containers@lists.linux-foundation.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, linux-ext4@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-audit@redhat.com, linux-integrity@vger.kernel.org, selinux@vger.kernel.org Subject: Re: [PATCH 05/34] fs: introduce MOUNT_ATTR_IDMAP Message-ID: <20201101144544.GC23378@infradead.org> References: <20201029003252.2128653-1-christian.brauner@ubuntu.com> <20201029003252.2128653-6-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201029003252.2128653-6-christian.brauner@ubuntu.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Thu, Oct 29, 2020 at 01:32:23AM +0100, Christian Brauner wrote: > Introduce a new mount bind mount property to allow idmapping mounts. The > MOUNT_ATTR_IDMAP flag can be set via the new mount_setattr() syscall > together with a file descriptor referring to a user namespace. Shouldn't this go to the end of the series once all the infrastructure is in place? > +config IDMAP_MOUNTS > + bool "Support id mappings per mount" > + default n n is the default default. But why do we need a config option here anyway? > +#ifdef CONFIG_IDMAP_MOUNTS > + if (kattr->attr_set & MNT_IDMAPPED) { > + struct user_namespace *user_ns; > + struct vfsmount *vmnt; All the code here looks like it should go into a helper. > + struct user_namespace *user_ns = READ_ONCE(m->mnt.mnt_user_ns); > + WRITE_ONCE(m->mnt.mnt_user_ns, get_user_ns(kattr->userns)); More unreadable long lines. > + if (attr->attr_set & MOUNT_ATTR_IDMAP) { > + struct ns_common *ns; > + struct user_namespace *user_ns; > + struct file *file; > + > + file = fget(attr->userns); The code here looks like another candidate for a self contained helper. > + > +static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt) > +{ > +#ifdef CONFIG_IDMAP_MOUNTS > + return READ_ONCE(mnt->mnt_user_ns); > +#else > + return &init_user_ns; > +#endif How is the READ_ONCE on a pointer going to work?