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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 359A7C43142 for ; Tue, 26 Jun 2018 08:57:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E02062672B for ; Tue, 26 Jun 2018 08:57:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E02062672B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933436AbeFZI5M convert rfc822-to-8bit (ORCPT ); Tue, 26 Jun 2018 04:57:12 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:48586 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932206AbeFZI5J (ORCPT ); Tue, 26 Jun 2018 04:57:09 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CE6E64079F09; Tue, 26 Jun 2018 08:57:08 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-238.rdu2.redhat.com [10.10.120.238]) by smtp.corp.redhat.com (Postfix) with ESMTP id C4B1B2166B5D; Tue, 26 Jun 2018 08:57:07 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20180626072736.GA31860@outlook.office365.com> References: <20180626072736.GA31860@outlook.office365.com> <152414474815.23902.6952548431423168966.stgit@warthog.procyon.org.uk> <20180619033450.GA11639@outlook.office365.com> <20180626061320.GA12548@outlook.office365.com> To: Andrei Vagin Cc: dhowells@redhat.com, viro@zeniv.linux.org.uk, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org Subject: Re: [12/24] proc: Add fs_context support to procfs [ver #7] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <31830.1530003427.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Tue, 26 Jun 2018 09:57:07 +0100 Message-ID: <31831.1530003427@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 26 Jun 2018 08:57:08 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 26 Jun 2018 08:57:08 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrei Vagin wrote: > > > > - mnt = kern_mount_data(&proc_fs_type, ns, 0); > > > > Here ns->user_ns and get_current_cred()->user_ns are not always equal > > What do you think about the attached patch? > ... > - fc = vfs_new_fs_context(&proc_fs_type, NULL, 0, > - FS_CONTEXT_FOR_KERNEL_MOUNT); > + fc = vfs_new_fs_context_userns(&proc_fs_type, NULL, 0, > + FS_CONTEXT_FOR_KERNEL_MOUNT, ns->user_ns); Or you could just change fc->user_ns immediately after calling vfs_new_fs_context(). This is what network filesystems should do with fc->net_ns, for example. > -struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type, > +struct fs_context *vfs_new_fs_context_userns(struct file_system_type *fs_type, > struct dentry *reference, > unsigned int sb_flags, > - enum fs_context_purpose purpose) > + enum fs_context_purpose purpose, > + struct user_namespace *user_ns) If you'd really rather add a new parameter, please don't rename the function to vfs_new_fs_context_userns() - just add a new parameter. There don't need to be two versions of it. This brings me to another thought: I want to add the ability to let namespaces be configured by userspace, for example: fd = fsopen("nfs"); sprintf(buf, "ns user %d", my_user_ns_fd); write(fd, buf); sprintf(buf, "ns net %d", my_net_ns_fd); write(fd, buf); write(fd, "s fedoraproject.org:/pub"); write(fd, "o intr"); ... I think therefore, I might need to insert another phase between creating the context and calling the filesystem initialiser: fc = vfs_new_fs_context(&afs_fs_type, mntpt, 0, FS_CONTEXT_FOR_SUBMOUNT); followed by: vfs_sb_set_namespace(fc, THIS_IS_USER_NS, user_ns); vfs_sb_set_namespace(fc, THIS_IS_NET_NS, net_ns); but then we'd need to do: vfs_begin_options(fc); before continuing (unless we made this happen automatically on the receipt of the first option): afs_mntpt_set_params(fc, mntpt); vfs_get_tree(fc); mnt = vfs_create_mount(fc, 0); Alternatively, we could do the namespace setting after initialisation and let the fs apply the changes itself. David