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=-12.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 8E5D3C433FE for ; Mon, 20 Jul 2020 16:29:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62C6D2073A for ; Mon, 20 Jul 2020 16:29:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lPa5yVLl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388788AbgGTQ3o (ORCPT ); Mon, 20 Jul 2020 12:29:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732133AbgGTP7K (ORCPT ); Mon, 20 Jul 2020 11:59:10 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DFFAC061794; Mon, 20 Jul 2020 08:59:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Mve+Dlm9ghe+CtbJJNJRDGZqsefQbVhzZmTfjwbVfnE=; b=lPa5yVLloGIdsTwK0lG0MESgU7 JGay3UB80aIc6ZPD0MHDSOYVV2qNaGs/E6isgE0N/THfb/pPOEehzQVe13Zcg7WO3g9/GgxWt0/D/ pbaWiudyNCzGu7mBvxK13tykrosoq+9xVxAJnqRrFO+k4l1tEczfvr52mGapxthm9qfiG9HxD5Olb dahuUdanft2Q9dcCdsHXo3kB90v2XxbrgC9b2TRbFEC0NNomNe9RUe3QcddtZhgqoM3LhDeA/U/XT YbqoWNybv3RdTpiBcN0uwvOeKSJCilgj323HF9Iit6RHVKJp+gp6eWdex4TzLtJkfs1OQyZBm+LIX cMM8rlOQ==; Received: from [2001:4bb8:105:4a81:db56:edb1:dbf2:5cc3] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jxYC2-0007mv-DR; Mon, 20 Jul 2020 15:59:06 +0000 From: Christoph Hellwig To: Al Viro , Linus Torvalds Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH 02/24] fs: add a do_kern_mount helper Date: Mon, 20 Jul 2020 17:58:40 +0200 Message-Id: <20200720155902.181712-3-hch@lst.de> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720155902.181712-1-hch@lst.de> References: <20200720155902.181712-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Like do_mount, but takes a kernel pointer for the destination path. Switch over the mounts in the init code and devtmpfs to it, which just happen to work due to the implicit set_fs(KERNEL_DS) during early init right now. Signed-off-by: Christoph Hellwig --- drivers/base/devtmpfs.c | 4 +- fs/namespace.c | 81 +++++++++++++++++++++++++---------------- include/linux/fs.h | 2 + init/do_mounts.c | 8 ++-- init/do_mounts_initrd.c | 6 +-- 5 files changed, 60 insertions(+), 41 deletions(-) diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index c9017e0584c003..03221ca708c91c 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -359,7 +359,7 @@ int __init devtmpfs_mount(void) if (!thread) return 0; - err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL); + err = do_kern_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL); if (err) printk(KERN_INFO "devtmpfs: error mounting %i\n", err); else @@ -385,7 +385,7 @@ static int devtmpfs_setup(void *p) err = ksys_unshare(CLONE_NEWNS); if (err) goto out; - err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL); + err = do_kern_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL); if (err) goto out; ksys_chdir("/.."); /* will traverse into overmounted root */ diff --git a/fs/namespace.c b/fs/namespace.c index f30ed401cc6d7a..d208a389aac3c0 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3115,12 +3115,11 @@ char *copy_mount_string(const void __user *data) * Therefore, if this magic number is present, it carries no information * and must be discarded. */ -long do_mount(const char *dev_name, const char __user *dir_name, +static int path_mount(const char *dev_name, struct path *path, const char *type_page, unsigned long flags, void *data_page) { - struct path path; unsigned int mnt_flags = 0, sb_flags; - int retval = 0; + int ret = 0; /* Discard magic */ if ((flags & MS_MGC_MSK) == MS_MGC_VAL) @@ -3133,19 +3132,13 @@ long do_mount(const char *dev_name, const char __user *dir_name, if (flags & MS_NOUSER) return -EINVAL; - /* ... and get the mountpoint */ - retval = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); - if (retval) - return retval; - - retval = security_sb_mount(dev_name, &path, - type_page, flags, data_page); - if (!retval && !may_mount()) - retval = -EPERM; - if (!retval && (flags & SB_MANDLOCK) && !may_mandlock()) - retval = -EPERM; - if (retval) - goto dput_out; + ret = security_sb_mount(dev_name, path, type_page, flags, data_page); + if (ret) + return ret; + if (!may_mount()) + return -EPERM; + if ((flags & SB_MANDLOCK) && !may_mandlock()) + return -EPERM; /* Default to relatime unless overriden */ if (!(flags & MS_NOATIME)) @@ -3172,7 +3165,7 @@ long do_mount(const char *dev_name, const char __user *dir_name, ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_STRICTATIME)) == 0)) { mnt_flags &= ~MNT_ATIME_MASK; - mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; + mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; } sb_flags = flags & (SB_RDONLY | @@ -3185,22 +3178,46 @@ long do_mount(const char *dev_name, const char __user *dir_name, SB_I_VERSION); if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) - retval = do_reconfigure_mnt(&path, mnt_flags); - else if (flags & MS_REMOUNT) - retval = do_remount(&path, flags, sb_flags, mnt_flags, - data_page); - else if (flags & MS_BIND) - retval = do_loopback(&path, dev_name, flags & MS_REC); - else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) - retval = do_change_type(&path, flags); - else if (flags & MS_MOVE) - retval = do_move_mount_old(&path, dev_name); - else - retval = do_new_mount(&path, type_page, sb_flags, mnt_flags, - dev_name, data_page); -dput_out: + return do_reconfigure_mnt(path, mnt_flags); + if (flags & MS_REMOUNT) + return do_remount(path, flags, sb_flags, mnt_flags, data_page); + if (flags & MS_BIND) + return do_loopback(path, dev_name, flags & MS_REC); + if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) + return do_change_type(path, flags); + if (flags & MS_MOVE) + return do_move_mount_old(path, dev_name); + + return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, + data_page); +} + +long do_mount(const char *dev_name, const char __user *dir_name, + const char *type_page, unsigned long flags, void *data_page) +{ + struct path path; + int ret; + + ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); + if (ret) + return ret; + ret = path_mount(dev_name, &path, type_page, flags, data_page); path_put(&path); - return retval; + return ret; +} + +int do_kern_mount(const char *dev_name, const char *dir_name, + const char *type_page, unsigned long flags, void *data_page) +{ + struct path path; + int ret; + + ret = kern_path(dir_name, LOOKUP_FOLLOW, &path); + if (ret) + return ret; + ret = path_mount(dev_name, &path, type_page, flags, data_page); + path_put(&path); + return ret; } static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) diff --git a/include/linux/fs.h b/include/linux/fs.h index a1d2685a487868..8f628f9868711d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2337,6 +2337,8 @@ extern int may_umount_tree(struct vfsmount *); extern int may_umount(struct vfsmount *); extern long do_mount(const char *, const char __user *, const char *, unsigned long, void *); +int do_kern_mount(const char *dev_name, const char *dir_name, + const char *type_page, unsigned long flags, void *data_page); extern struct vfsmount *collect_mounts(const struct path *); extern void drop_collected_mounts(struct vfsmount *); extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *, diff --git a/init/do_mounts.c b/init/do_mounts.c index 4f4ceb35805503..2fef92a8ed3c15 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -395,16 +395,16 @@ static int __init do_mount_root(const char *name, const char *fs, int ret; if (data) { - /* do_mount() requires a full page as fifth argument */ + /* do_kern_mount() requires a full page as fifth argument */ p = alloc_page(GFP_KERNEL); if (!p) return -ENOMEM; data_page = page_address(p); - /* zero-pad. do_mount() will make sure it's terminated */ + /* zero-pad. do_kern_mount() will make sure it's terminated */ strncpy(data_page, data, PAGE_SIZE); } - ret = do_mount(name, "/root", fs, flags, data_page); + ret = do_kern_mount(name, "/root", fs, flags, data_page); if (ret) goto out; @@ -628,7 +628,7 @@ void __init prepare_namespace(void) mount_root(); out: devtmpfs_mount(); - do_mount(".", "/", NULL, MS_MOVE, NULL); + do_kern_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); } diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index e08669187d63be..604ce78af9acfa 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -62,7 +62,7 @@ static int __init init_linuxrc(struct subprocess_info *info, struct cred *new) console_on_rootfs(); /* move initrd over / and chdir/chroot in initrd root */ ksys_chdir("/root"); - do_mount(".", "/", NULL, MS_MOVE, NULL); + do_kern_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); ksys_setsid(); return 0; @@ -99,7 +99,7 @@ static void __init handle_initrd(void) current->flags &= ~PF_FREEZER_SKIP; /* move initrd to rootfs' /old */ - do_mount("..", ".", NULL, MS_MOVE, NULL); + do_kern_mount("..", ".", NULL, MS_MOVE, NULL); /* switch root and cwd back to / of rootfs */ ksys_chroot(".."); @@ -113,7 +113,7 @@ static void __init handle_initrd(void) mount_root(); printk(KERN_NOTICE "Trying to move old root to /initrd ... "); - error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL); + error = do_kern_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL); if (!error) printk("okay\n"); else { -- 2.27.0