OpenSolaris Launch

1 files changed, 188 insertions, 0 deletions

diff --git a/usr/src/uts/common/syscall/umount.c b/usr/src/uts/common/syscall/umount.c
new file mode 100644
index 0000000000..f5fb881f5d
--- /dev/null
+++ b/usr/src/uts/common/syscall/umount.c
@@ -0,0 +1,188 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License").  You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
+/*	  All Rights Reserved  	*/
+
+/*
+ * Portions of this source code were derived from Berkeley 4.3 BSD
+ * under license from the Regents of the University of California.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <sys/types.h>
+#include <sys/t_lock.h>
+#include <sys/param.h>
+#include <sys/errno.h>
+#include <sys/fstyp.h>
+#include <sys/kmem.h>
+#include <sys/systm.h>
+#include <sys/mount.h>
+#include <sys/vfs.h>
+#include <sys/cred.h>
+#include <sys/vnode.h>
+#include <sys/cmn_err.h>
+#include <sys/debug.h>
+#include <sys/pathname.h>
+#include <sys/policy.h>
+#include <sys/zone.h>
+
+
+/*
+ * New umount() system call (for force unmount flag and perhaps others later).
+ */
+int
+umount2(char *pathp, int flag)
+{
+	struct pathname pn;
+	struct vfs *vfsp;
+	int error;
+
+	/*
+	 * Some flags are disallowed through the system call interface.
+	 */
+	flag &= MS_UMOUNT_MASK;
+
+	/*
+	 * Lookup user-supplied name by trying to match it against the
+	 * mount points recorded at mount time.  If no match is found
+	 * (which can happen if the path to the mount point is specified
+	 * differently between mount & umount, or if a block device were
+	 * passed to umount) then we fall back to calling lookupname()
+	 * to find the vfs.  Doing it this way prevents calling lookupname()
+	 * in most cases and that allows forcible umount to work even if
+	 * lookupname() would hang (i.e. because an NFS server is dead).
+	 */
+
+	if (error = pn_get(pathp, UIO_USERSPACE, &pn))
+		return (set_errno(error));
+
+	/*
+	 * Only a privileged user is allowed to bypass the security
+	 * checks done by lookupname() and use the results from
+	 * vfs_mntpoint2vfsp() instead.  It could be argued that the
+	 * proper check is FILE_DAC_SEARCH but we put it all
+	 * under the mount privilege.  Also, make sure the caller
+	 * isn't in an environment with an alternate root (to the zone's root)
+	 * directory, i.e. chroot(2).
+	 */
+	if (secpolicy_fs_unmount(CRED(), NULL) != 0 ||
+	    (PTOU(curproc)->u_rdir != NULL &&
+	    PTOU(curproc)->u_rdir != curproc->p_zone->zone_rootvp) ||
+	    (vfsp = vfs_mntpoint2vfsp(pn.pn_path)) == NULL) {
+		vnode_t *fsrootvp;
+
+		/* fall back to lookupname() on path given to us */
+		if (error = lookupname(pn.pn_path, UIO_SYSSPACE, FOLLOW,
+		    NULLVPP, &fsrootvp)) {
+			pn_free(&pn);
+			return (set_errno(error));
+		}
+		/*
+		 * Find the vfs to be unmounted.  The caller may have specified
+		 * either the directory mount point (preferred) or else (for a
+		 * disk-based file system) the block device which was mounted.
+		 * Check to see which it is; if it's the device, search the VFS
+		 * list to find the associated vfs entry.
+		 */
+		if (fsrootvp->v_flag & VROOT) {
+			vfsp = fsrootvp->v_vfsp;
+			VFS_HOLD(vfsp);
+		} else if (fsrootvp->v_type == VBLK)
+			vfsp = vfs_dev2vfsp(fsrootvp->v_rdev);
+		else
+			vfsp = NULL;
+
+		VN_RELE(fsrootvp);
+
+		if (vfsp == NULL) {
+			pn_free(&pn);
+			return (set_errno(EINVAL));
+		}
+	}
+	pn_free(&pn);
+
+	/*
+	 * Protect the call to vn_vfswlock() with the vfs reflock.  This
+	 * ensures vfs_vnodecovered will either be NULL (because someone
+	 * beat us to the umount) or valid (because vfs_lock() prevents
+	 * another umount from getting through here until we've called
+	 * vn_vfswlock() on the covered vnode).
+	 *
+	 * At one point, we did the non-blocking version (vfs_lock()),
+	 * and if it failed, bailed out with EBUSY.  However, dounmount()
+	 * calls vfs_lock_wait() and we drop the vfs lock before calling
+	 * dounmount(), so there's no difference between waiting here
+	 * for the lock or waiting there because grabbed it as soon as
+	 * we drop it below.  No returning with EBUSY at this point
+	 * reduces the number of spurious unmount failures that happen
+	 * as a side-effect of fsflush() and other mount and unmount
+	 * operations that might be going on simultaneously.
+	 */
+	vfs_lock_wait(vfsp);
+
+	/*
+	 * Call vn_vfswlock() on the covered vnode so that dounmount()
+	 * can do its thing.  It will call the corresponding vn_vfsunlock().
+	 * Note that vfsp->vfs_vnodecovered can be NULL here, either because
+	 * someone did umount on "/" or because someone beat us to the umount
+	 * before we did the vfs_lock() above.  In these cases, vn_vfswlock()
+	 * returns EBUSY and we just pass that up.  Also note that we're
+	 * looking at a vnode without doing a VN_HOLD() on it.  This is
+	 * safe because it can't go away while something is mounted on it
+	 * and we're locking out other umounts at this point.
+	 */
+	if (vn_vfswlock(vfsp->vfs_vnodecovered)) {
+		vfs_unlock(vfsp);
+		VFS_RELE(vfsp);
+		return (set_errno(EBUSY));
+	}
+
+	/*
+	 * Now that the VVFSLOCK in the covered vnode is protecting this
+	 * path, we don't need the vfs reflock or the hold on the vfs anymore.
+	 */
+	vfs_unlock(vfsp);
+	VFS_RELE(vfsp);
+
+	/*
+	 * Perform the unmount.
+	 */
+	if ((error = dounmount(vfsp, flag, CRED())) != 0)
+		return (set_errno(error));
+	return (0);
+}
+
+/*
+ * Old umount() system call for compatibility.
+ * Changes due to support for forced unmount.
+ */
+int
+umount(char *pathp)
+{
+	return (umount2(pathp, 0));
+}