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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64968C64EC4 for ; Wed, 1 Mar 2023 01:50:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229672AbjCABuh (ORCPT ); Tue, 28 Feb 2023 20:50:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229560AbjCABug (ORCPT ); Tue, 28 Feb 2023 20:50:36 -0500 Received: from mail-qv1-xf32.google.com (mail-qv1-xf32.google.com [IPv6:2607:f8b0:4864:20::f32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD86D193E4 for ; Tue, 28 Feb 2023 17:50:35 -0800 (PST) Received: by mail-qv1-xf32.google.com with SMTP id ff4so8305100qvb.2 for ; Tue, 28 Feb 2023 17:50:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficientek-com.20210112.gappssmtp.com; s=20210112; t=1677635435; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=mcrDBIGtrTEDjzonWUNUAc4MXuRWYEApdBnj/prlZpU=; b=dDKs5CP907SyA/Bjl9QDsBGZ56nJyMPapGC8bBkngXXKV1sqgR27+HEkCACRSCaOLl vLHnnYCcap/MfQncsNX7nqNofY9v49OyxdDsfwIE6LLSzmDCIpX8tNjBgM7wCd6ZBBjG 92Xvh11XoHf0jiIbyL+CcMt++wiEAXwEph+dDblB0/3r0CuJ7n3E4U9XvRP47Yg9Q74o nSpWC690N+qR//1QyrR58O/7PNRJsuAYpiiqkCQTCihzM+i7RoiKGTIjMe2kBKBmvOQt JdoHVszfYpgUSAfwRN0LLNVztjr+MOfYHS0rADQ0TPR0lkgOQoQgaINpKmeJGV02/bzN ANEw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677635435; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=mcrDBIGtrTEDjzonWUNUAc4MXuRWYEApdBnj/prlZpU=; b=CmG6cBKyDqlittYxdd6Co849MKIp8a7T0r0wlXb2PWv5LkrsxKL13GbKI94vrGtWIy +KJx+PoB7E7gvRFrnHkGhLT/8hFGBlJq51zd8b9ybaRszMssi0vz54PkkOJ+D3lkNRyz 0+Tv/4clUkbI3zUr5HBSrhkqWCPLtfuS2mkifaL9DjcrkgZx+gzcA1nDQLv1gLwKpjiv +Vk95d0YNt7OUNR8GQrCd9SoDCIPrFaYVeZL/8TjG6IiZWmefuR1kSyxMDGitx2onSSW k70otlGQFAh5TLQETp12kPuOAmVbmJXxEVATom0qSXxqB4nDo5ygxBFi4u86eXH8efDX tJ4w== X-Gm-Message-State: AO0yUKU1xgoQgNmR43sj4TCY51JMh7yILOecWAZPqgw4uQaPoWPf+bn/ /a/UyyWM7L3FaJ/jAC00/qeGCA== X-Google-Smtp-Source: AK7set9a/p6WWFIvBuX9pL8jdiOxPQ2UPXugNGMeAAUTu0K6mSLmk0zzIXFguEf4CPa4Hbqn9ECGyA== X-Received: by 2002:a05:6214:c43:b0:56e:9ab5:cd9f with SMTP id r3-20020a0562140c4300b0056e9ab5cd9fmr8229751qvj.39.1677635434870; Tue, 28 Feb 2023 17:50:34 -0800 (PST) Received: from localhost.localdomain ([37.218.244.251]) by smtp.gmail.com with ESMTPSA id d184-20020a37b4c1000000b0073b69922cfesm7750267qkf.85.2023.02.28.17.50.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Feb 2023 17:50:34 -0800 (PST) From: Glenn Washburn To: Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org Cc: Glenn Washburn , linux-kernel@vger.kernel.org, Christian Brauner , Seth Forshee , linux-fsdevel@vger.kernel.org Subject: [RFC PATCH v2] hostfs: handle idmapped mounts Date: Tue, 28 Feb 2023 19:50:02 -0600 Message-Id: <20230301015002.2402544-1-development@efficientek.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Let hostfs handle idmapped mounts. This allows to have the same hostfs mount appear in multiple locations with different id mappings. root@(none):/media# id uid=0(root) gid=0(root) groups=0(root) root@(none):/media# mkdir mnt idmapped root@(none):/media# mount -thostfs -o/home/user hostfs mnt root@(none):/media# touch mnt/aaa root@(none):/media# mount-idmapped --map-mount u:`id -u user`:0:1 --map-mount g:`id -g user`:0:1 /media/mnt /media/idmapped root@(none):/media# ls -l mnt/aaa idmapped/aaa -rw-r--r-- 1 root root 0 Jan 28 01:23 idmapped/aaa -rw-r--r-- 1 user user 0 Jan 28 01:23 mnt/aaa root@(none):/media# touch idmapped/bbb root@(none):/media# ls -l mnt/bbb idmapped/bbb -rw-r--r-- 1 root root 0 Jan 28 01:26 idmapped/bbb -rw-r--r-- 1 user user 0 Jan 28 01:26 mnt/bbb Signed-off-by: Glenn Washburn --- Changes from v1: * Rebase on to tip. The above commands work and have the results expected. The __vfsuid_val(make_vfsuid(...)) seems ugly to get the uid_t, but it seemed like the best one I've come across. Is there a better way? Glenn --- fs/hostfs/hostfs_kern.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index c18bb50c31b6..9459da99a0db 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -786,7 +786,7 @@ static int hostfs_permission(struct mnt_idmap *idmap, err = access_file(name, r, w, x); __putname(name); if (!err) - err = generic_permission(&nop_mnt_idmap, ino, desired); + err = generic_permission(idmap, ino, desired); return err; } @@ -794,13 +794,14 @@ static int hostfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_inode(dentry); + struct user_namespace *fs_userns = i_user_ns(inode); struct hostfs_iattr attrs; char *name; int err; int fd = HOSTFS_I(inode)->fd; - err = setattr_prepare(&nop_mnt_idmap, dentry, attr); + err = setattr_prepare(idmap, dentry, attr); if (err) return err; @@ -814,11 +815,11 @@ static int hostfs_setattr(struct mnt_idmap *idmap, } if (attr->ia_valid & ATTR_UID) { attrs.ia_valid |= HOSTFS_ATTR_UID; - attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); + attrs.ia_uid = __vfsuid_val(make_vfsuid(idmap, fs_userns, attr->ia_uid)); } if (attr->ia_valid & ATTR_GID) { attrs.ia_valid |= HOSTFS_ATTR_GID; - attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); + attrs.ia_gid = __vfsgid_val(make_vfsgid(idmap, fs_userns, attr->ia_gid)); } if (attr->ia_valid & ATTR_SIZE) { attrs.ia_valid |= HOSTFS_ATTR_SIZE; @@ -857,7 +858,7 @@ static int hostfs_setattr(struct mnt_idmap *idmap, attr->ia_size != i_size_read(inode)) truncate_setsize(inode, attr->ia_size); - setattr_copy(&nop_mnt_idmap, inode, attr); + setattr_copy(idmap, inode, attr); mark_inode_dirty(inode); return 0; } @@ -991,7 +992,7 @@ static struct file_system_type hostfs_type = { .name = "hostfs", .mount = hostfs_read_sb, .kill_sb = hostfs_kill_sb, - .fs_flags = 0, + .fs_flags = FS_ALLOW_IDMAP, }; MODULE_ALIAS_FS("hostfs"); base-commit: 7fa08de735e41001a70c8ca869b2b159d74c2339 -- 2.30.2