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 7631FC433E5 for ; Mon, 20 Jul 2020 16:29:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 520A2207DD for ; Mon, 20 Jul 2020 16:29:52 +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="SUGwTGF8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388800AbgGTQ3u (ORCPT ); Mon, 20 Jul 2020 12:29:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731850AbgGTP7L (ORCPT ); Mon, 20 Jul 2020 11:59:11 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFF7DC061794; 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=YknGFmw1HdnT1qStqOT9wnRgOHrqfYkyqpqGeX9Gd5g=; b=SUGwTGF87+Bvn4/tsKZJsW65zw fmZtDW/2RCy6fXfMqQcTWNFpaZSYQGDdqENP66n9PGzgZbCLrZtjNmFGqCizXYlbVd/+xRN1Y+xnD lROPbgblyoVZu5icjsZ5LUMYTyYBHSf8ZfFIEuSi2FP95MBSdRF1w6mhfucFrQ5dqSqV81WtlilGw IcWO6eP7Hc3qoiuyBrgiOSYEkM97zA4Y+wnaMulONkuwC1ahJIgvlOmLFhhpnPqmig4eQES3TkB74 5ssCdnBJyB+do5/mCWVjnVsOtBZoTV49fxrXlJ4gnIpR0uNGOcCAaJRfeJZNjXS1JpN3UP+/TP3xl ZJEOa2HA==; 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 1jxYC3-0007n1-N9; Mon, 20 Jul 2020 15:59:08 +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 03/24] fs: add a kern_umount helper Date: Mon, 20 Jul 2020 17:58:41 +0200 Message-Id: <20200720155902.181712-4-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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Like ksys_umount, but takes a kernel pointer for the destination path. Switch over the umount in the init code to it, which just happens to work due to the implicit set_fs(KERNEL_DS) during early init right now. Signed-off-by: Christoph Hellwig --- fs/namespace.c | 53 ++++++++++++++++++++++++---------------- include/linux/fs.h | 1 + include/linux/syscalls.h | 1 - init/do_mounts_initrd.c | 2 +- 4 files changed, 34 insertions(+), 23 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index d208a389aac3c0..cfcee6a1bd5dd2 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1706,36 +1706,26 @@ static inline bool may_mandlock(void) } #endif -/* - * Now umount can handle mount points as well as block devices. - * This is important for filesystems which use unnamed block devices. - * - * We now support a flag for forced unmount like the other 'big iron' - * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD - */ +static int umount_lookup_flags(int flags) +{ + if (flags & UMOUNT_NOFOLLOW) + return LOOKUP_MOUNTPOINT; + return LOOKUP_MOUNTPOINT | LOOKUP_FOLLOW; +} -int ksys_umount(char __user *name, int flags) +static int path_umount(struct path *path, int flags) { - struct path path; struct mount *mnt; int retval; - int lookup_flags = LOOKUP_MOUNTPOINT; if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) return -EINVAL; - if (!may_mount()) return -EPERM; - if (!(flags & UMOUNT_NOFOLLOW)) - lookup_flags |= LOOKUP_FOLLOW; - - retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); - if (retval) - goto out; - mnt = real_mount(path.mnt); + mnt = real_mount(path->mnt); retval = -EINVAL; - if (path.dentry != path.mnt->mnt_root) + if (path->dentry != path->mnt->mnt_root) goto dput_and_out; if (!check_mnt(mnt)) goto dput_and_out; @@ -1748,12 +1738,33 @@ int ksys_umount(char __user *name, int flags) retval = do_umount(mnt, flags); dput_and_out: /* we mustn't call path_put() as that would clear mnt_expiry_mark */ - dput(path.dentry); + dput(path->dentry); mntput_no_expire(mnt); -out: return retval; } +static int ksys_umount(char __user *name, int flags) +{ + struct path path; + int ret; + + ret = user_path_at(AT_FDCWD, name, umount_lookup_flags(flags), &path); + if (ret) + return ret; + return path_umount(&path, flags); +} + +int __init kern_umount(char *name, int flags) +{ + struct path path; + int ret; + + ret = kern_path(name, umount_lookup_flags(flags), &path); + if (ret) + return ret; + return path_umount(&path, flags); +} + SYSCALL_DEFINE2(umount, char __user *, name, int, flags) { return ksys_umount(name, flags); diff --git a/include/linux/fs.h b/include/linux/fs.h index 8f628f9868711d..fbeadaa1a185fb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2339,6 +2339,7 @@ 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); +int __init kern_umount(char *name, int flags); 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/include/linux/syscalls.h b/include/linux/syscalls.h index 5b0f1fca4cfb9d..3b1b8ebcda1d8c 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1236,7 +1236,6 @@ asmlinkage long sys_ni_syscall(void); * the ksys_xyzyyz() functions prototyped below. */ -int ksys_umount(char __user *name, int flags); int ksys_chroot(const char __user *filename); ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count); int ksys_chdir(const char __user *filename); diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index 604ce78af9acfa..d3858620707893 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -122,7 +122,7 @@ static void __init handle_initrd(void) else printk("failed\n"); printk(KERN_NOTICE "Unmounting old root\n"); - ksys_umount("/old", MNT_DETACH); + kern_umount("/old", MNT_DETACH); } } -- 2.27.0