From patchwork Tue Feb 19 16:29:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 10820185 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BD022922 for ; Tue, 19 Feb 2019 16:29:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A59152CBC8 for ; Tue, 19 Feb 2019 16:29:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 99D2B2CBCD; Tue, 19 Feb 2019 16:29:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 292562CBC8 for ; Tue, 19 Feb 2019 16:29:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726110AbfBSQ3e (ORCPT ); Tue, 19 Feb 2019 11:29:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53474 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726342AbfBSQ3e (ORCPT ); Tue, 19 Feb 2019 11:29:34 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 08735599C2; Tue, 19 Feb 2019 16:29:34 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-129.rdu2.redhat.com [10.10.121.129]) by smtp.corp.redhat.com (Postfix) with ESMTP id A90BE60C1D; Tue, 19 Feb 2019 16:29:32 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 08/43] teach vfs_get_tree() to handle subtype, switch do_new_mount() to it From: David Howells To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, dhowells@redhat.com, torvalds@linux-foundation.org, ebiederm@xmission.com, linux-security-module@vger.kernel.org Date: Tue, 19 Feb 2019 16:29:30 +0000 Message-ID: <155059377086.12449.48912929800325479.stgit@warthog.procyon.org.uk> In-Reply-To: <155059366914.12449.4669870128936536848.stgit@warthog.procyon.org.uk> References: <155059366914.12449.4669870128936536848.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 19 Feb 2019 16:29:34 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: Al Viro Roll the handling of subtypes into do_new_mount() and vfs_get_tree(). The former determines any subtype string and hangs it off the fs_context; the latter applies it. Make do_new_mount() create, parameterise and commit an fs_context and create a mount for itself rather than calling vfs_kern_mount(). [AV -- missing kstrdup()] [AV -- ... and no kstrdup() if we get to setting ->s_submount - we simply transfer it from fc, leaving NULL behind] [AV -- constify ->s_submount, while we are at it] Reviewed-by: David Howells Signed-off-by: Al Viro --- fs/namespace.c | 77 +++++++++++++++++++++++++++++++--------------------- fs/super.c | 5 +++ include/linux/fs.h | 2 + 3 files changed, 52 insertions(+), 32 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 156771f5745a..0354cb6ac2d3 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2479,29 +2479,6 @@ static int do_move_mount(struct path *path, const char *old_name) return err; } -static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) -{ - int err; - const char *subtype = strchr(fstype, '.'); - if (subtype) { - subtype++; - err = -EINVAL; - if (!subtype[0]) - goto err; - } else - subtype = ""; - - mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); - err = -ENOMEM; - if (!mnt->mnt_sb->s_subtype) - goto err; - return mnt; - - err: - mntput(mnt); - return ERR_PTR(err); -} - /* * add a mount into a namespace's mount tree */ @@ -2557,7 +2534,9 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, { struct file_system_type *type; struct vfsmount *mnt; - int err; + struct fs_context *fc; + const char *subtype = NULL; + int err = 0; if (!fstype) return -EINVAL; @@ -2566,23 +2545,59 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, if (!type) return -ENODEV; - mnt = vfs_kern_mount(type, sb_flags, name, data); - if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && - !mnt->mnt_sb->s_subtype) - mnt = fs_set_subtype(mnt, fstype); + if (type->fs_flags & FS_HAS_SUBTYPE) { + subtype = strchr(fstype, '.'); + if (subtype) { + subtype++; + if (!*subtype) { + put_filesystem(type); + return -EINVAL; + } + } else { + subtype = ""; + } + } + fc = fs_context_for_mount(type, sb_flags); put_filesystem(type); - if (IS_ERR(mnt)) - return PTR_ERR(mnt); + if (IS_ERR(fc)) + return PTR_ERR(fc); + + if (subtype) { + fc->subtype = kstrdup(subtype, GFP_KERNEL); + if (!fc->subtype) + err = -ENOMEM; + } + if (!err && name) { + fc->source = kstrdup(name, GFP_KERNEL); + if (!fc->source) + err = -ENOMEM; + } + if (!err) + err = parse_monolithic_mount_data(fc, data); + if (!err) + err = vfs_get_tree(fc); + if (err) + goto out; + + up_write(&fc->root->d_sb->s_umount); + mnt = vfs_create_mount(fc); + if (IS_ERR(mnt)) { + err = PTR_ERR(mnt); + goto out; + } if (mount_too_revealing(mnt, &mnt_flags)) { mntput(mnt); - return -EPERM; + err = -EPERM; + goto out; } err = do_add_mount(real_mount(mnt), path, mnt_flags); if (err) mntput(mnt); +out: + put_fs_context(fc); return err; } diff --git a/fs/super.c b/fs/super.c index fc3887277ad1..b91b6df05b67 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1262,6 +1262,11 @@ int vfs_get_tree(struct fs_context *fc) sb = fc->root->d_sb; WARN_ON(!sb->s_bdi); + if (fc->subtype && !sb->s_subtype) { + sb->s_subtype = fc->subtype; + fc->subtype = NULL; + } + /* * Write barrier is for super_cache_count(). We place it before setting * SB_BORN as the data dependency between the two functions is the diff --git a/include/linux/fs.h b/include/linux/fs.h index 811c77743dad..36fff12ab890 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1447,7 +1447,7 @@ struct super_block { * Filesystem subtype. If non-empty the filesystem type field * in /proc/mounts will be "type.subtype" */ - char *s_subtype; + const char *s_subtype; const struct dentry_operations *s_d_op; /* default d_op for dentries */