xref: /illumos-gate/usr/src/lib/libzfs/common/libzfs_mount.c (revision 0dfe541e)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * Copyright 2019 Nexenta Systems, Inc.
 * Copyright (c) 2014, 2016 by Delphix. All rights reserved.
 * Copyright 2016 Igor Kozhukhov <ikozhukhov@gmail.com>
 * Copyright 2017 Joyent, Inc.
 * Copyright 2017 RackTop Systems.
 * Copyright 2018 OmniOS Community Edition (OmniOSce) Association.
 */

/*
 * Routines to manage ZFS mounts.  We separate all the nasty routines that have
 * to deal with the OS.  The following functions are the main entry points --
 * they are used by mount and unmount and when changing a filesystem's
 * mountpoint.
 *
 *	zfs_is_mounted()
 *	zfs_mount()
 *	zfs_unmount()
 *	zfs_unmountall()
 *
 * This file also contains the functions used to manage sharing filesystems via
 * NFS and iSCSI:
 *
 *	zfs_is_shared()
 *	zfs_share()
 *	zfs_unshare()
 *
 *	zfs_is_shared_nfs()
 *	zfs_is_shared_smb()
 *	zfs_share_proto()
 *	zfs_shareall();
 *	zfs_unshare_nfs()
 *	zfs_unshare_smb()
 *	zfs_unshareall_nfs()
 *	zfs_unshareall_smb()
 *	zfs_unshareall()
 *	zfs_unshareall_bypath()
 *
 * The following functions are available for pool consumers, and will
 * mount/unmount and share/unshare all datasets within pool:
 *
 *	zpool_enable_datasets()
 *	zpool_disable_datasets()
 */

#include <dirent.h>
#include <dlfcn.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <zone.h>
#include <sys/mntent.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/dsl_crypt.h>

#include <libzfs.h>

#include "libzfs_impl.h"
#include "libzfs_taskq.h"

#include <libshare.h>
#include <sys/systeminfo.h>
#define	MAXISALEN	257	/* based on sysinfo(2) man page */

static int mount_tq_nthr = 512;	/* taskq threads for multi-threaded mounting */

static void zfs_mount_task(void *);
static int zfs_share_proto(zfs_handle_t *, zfs_share_proto_t *);
zfs_share_type_t zfs_is_shared_proto(zfs_handle_t *, char **,
    zfs_share_proto_t);

/*
 * The share protocols table must be in the same order as the zfs_share_proto_t
 * enum in libzfs_impl.h
 */
typedef struct {
	zfs_prop_t p_prop;
	char *p_name;
	int p_share_err;
	int p_unshare_err;
} proto_table_t;

proto_table_t proto_table[PROTO_END] = {
	{ZFS_PROP_SHARENFS, "nfs", EZFS_SHARENFSFAILED, EZFS_UNSHARENFSFAILED},
	{ZFS_PROP_SHARESMB, "smb", EZFS_SHARESMBFAILED, EZFS_UNSHARESMBFAILED},
};

zfs_share_proto_t nfs_only[] = {
	PROTO_NFS,
	PROTO_END
};

zfs_share_proto_t smb_only[] = {
	PROTO_SMB,
	PROTO_END
};
zfs_share_proto_t share_all_proto[] = {
	PROTO_NFS,
	PROTO_SMB,
	PROTO_END
};

/*
 * Search the sharetab for the given mountpoint and protocol, returning
 * a zfs_share_type_t value.
 */
static zfs_share_type_t
is_shared(libzfs_handle_t *hdl, const char *mountpoint, zfs_share_proto_t proto)
{
	char buf[MAXPATHLEN], *tab;
	char *ptr;

	if (hdl->libzfs_sharetab == NULL)
		return (SHARED_NOT_SHARED);

	(void) fseek(hdl->libzfs_sharetab, 0, SEEK_SET);

	while (fgets(buf, sizeof (buf), hdl->libzfs_sharetab) != NULL) {

		/* the mountpoint is the first entry on each line */
		if ((tab = strchr(buf, '\t')) == NULL)
			continue;

		*tab = '\0';
		if (strcmp(buf, mountpoint) == 0) {
			/*
			 * the protocol field is the third field
			 * skip over second field
			 */
			ptr = ++tab;
			if ((tab = strchr(ptr, '\t')) == NULL)
				continue;
			ptr = ++tab;
			if ((tab = strchr(ptr, '\t')) == NULL)
				continue;
			*tab = '\0';
			if (strcmp(ptr,
			    proto_table[proto].p_name) == 0) {
				switch (proto) {
				case PROTO_NFS:
					return (SHARED_NFS);
				case PROTO_SMB:
					return (SHARED_SMB);
				default:
					return (0);
				}
			}
		}
	}

	return (SHARED_NOT_SHARED);
}

static boolean_t
dir_is_empty_stat(const char *dirname)
{
	struct stat st;

	/*
	 * We only want to return false if the given path is a non empty
	 * directory, all other errors are handled elsewhere.
	 */
	if (stat(dirname, &st) < 0 || !S_ISDIR(st.st_mode)) {
		return (B_TRUE);
	}

	/*
	 * An empty directory will still have two entries in it, one
	 * entry for each of "." and "..".
	 */
	if (st.st_size > 2) {
		return (B_FALSE);
	}

	return (B_TRUE);
}

static boolean_t
dir_is_empty_readdir(const char *dirname)
{
	DIR *dirp;
	struct dirent64 *dp;
	int dirfd;

	if ((dirfd = openat(AT_FDCWD, dirname,
	    O_RDONLY | O_NDELAY | O_LARGEFILE | O_CLOEXEC, 0)) < 0) {
		return (B_TRUE);
	}

	if ((dirp = fdopendir(dirfd)) == NULL) {
		(void) close(dirfd);
		return (B_TRUE);
	}

	while ((dp = readdir64(dirp)) != NULL) {

		if (strcmp(dp->d_name, ".") == 0 ||
		    strcmp(dp->d_name, "..") == 0)
			continue;

		(void) closedir(dirp);
		return (B_FALSE);
	}

	(void) closedir(dirp);
	return (B_TRUE);
}

/*
 * Returns true if the specified directory is empty.  If we can't open the
 * directory at all, return true so that the mount can fail with a more
 * informative error message.
 */
static boolean_t
dir_is_empty(const char *dirname)
{
	struct statvfs64 st;

	/*
	 * If the statvfs call fails or the filesystem is not a ZFS
	 * filesystem, fall back to the slow path which uses readdir.
	 */
	if ((statvfs64(dirname, &st) != 0) ||
	    (strcmp(st.f_basetype, "zfs") != 0)) {
		return (dir_is_empty_readdir(dirname));
	}

	/*
	 * At this point, we know the provided path is on a ZFS
	 * filesystem, so we can use stat instead of readdir to
	 * determine if the directory is empty or not. We try to avoid
	 * using readdir because that requires opening "dirname"; this
	 * open file descriptor can potentially end up in a child
	 * process if there's a concurrent fork, thus preventing the
	 * zfs_mount() from otherwise succeeding (the open file
	 * descriptor inherited by the child process will cause the
	 * parent's mount to fail with EBUSY). The performance
	 * implications of replacing the open, read, and close with a
	 * single stat is nice; but is not the main motivation for the
	 * added complexity.
	 */
	return (dir_is_empty_stat(dirname));
}

/*
 * Checks to see if the mount is active.  If the filesystem is mounted, we fill
 * in 'where' with the current mountpoint, and return 1.  Otherwise, we return
 * 0.
 */
boolean_t
is_mounted(libzfs_handle_t *zfs_hdl, const char *special, char **where)
{
	struct mnttab entry;

	if (libzfs_mnttab_find(zfs_hdl, special, &entry) != 0)
		return (B_FALSE);

	if (where != NULL)
		*where = zfs_strdup(zfs_hdl, entry.mnt_mountp);

	return (B_TRUE);
}

boolean_t
zfs_is_mounted(zfs_handle_t *zhp, char **where)
{
	return (is_mounted(zhp->zfs_hdl, zfs_get_name(zhp), where));
}

/*
 * Returns true if the given dataset is mountable, false otherwise.  Returns the
 * mountpoint in 'buf'.
 */
static boolean_t
zfs_is_mountable(zfs_handle_t *zhp, char *buf, size_t buflen,
    zprop_source_t *source)
{
	char sourceloc[MAXNAMELEN];
	zprop_source_t sourcetype;

	if (!zfs_prop_valid_for_type(ZFS_PROP_MOUNTPOINT, zhp->zfs_type))
		return (B_FALSE);

	verify(zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, buf, buflen,
	    &sourcetype, sourceloc, sizeof (sourceloc), B_FALSE) == 0);

	if (strcmp(buf, ZFS_MOUNTPOINT_NONE) == 0 ||
	    strcmp(buf, ZFS_MOUNTPOINT_LEGACY) == 0)
		return (B_FALSE);

	if (zfs_prop_get_int(zhp, ZFS_PROP_CANMOUNT) == ZFS_CANMOUNT_OFF)
		return (B_FALSE);

	if (zfs_prop_get_int(zhp, ZFS_PROP_ZONED) &&
	    getzoneid() == GLOBAL_ZONEID)
		return (B_FALSE);

	if (source)
		*source = sourcetype;

	return (B_TRUE);
}

/*
 * Mount the given filesystem.
 */
int
zfs_mount(zfs_handle_t *zhp, const char *options, int flags)
{
	struct stat buf;
	char mountpoint[ZFS_MAXPROPLEN];
	char mntopts[MNT_LINE_MAX];
	libzfs_handle_t *hdl = zhp->zfs_hdl;
	uint64_t keystatus;
	int rc;

	if (options == NULL)
		mntopts[0] = '\0';
	else
		(void) strlcpy(mntopts, options, sizeof (mntopts));

	/*
	 * If the pool is imported read-only then all mounts must be read-only
	 */
	if (zpool_get_prop_int(zhp->zpool_hdl, ZPOOL_PROP_READONLY, NULL))
		flags |= MS_RDONLY;

	if (!zfs_is_mountable(zhp, mountpoint, sizeof (mountpoint), NULL))
		return (0);

	/*
	 * If the filesystem is encrypted the key must be loaded  in order to
	 * mount. If the key isn't loaded, the MS_CRYPT flag decides whether
	 * or not we attempt to load the keys. Note: we must call
	 * zfs_refresh_properties() here since some callers of this function
	 * (most notably zpool_enable_datasets()) may implicitly load our key
	 * by loading the parent's key first.
	 */
	if (zfs_prop_get_int(zhp, ZFS_PROP_ENCRYPTION) != ZIO_CRYPT_OFF) {
		zfs_refresh_properties(zhp);
		keystatus = zfs_prop_get_int(zhp, ZFS_PROP_KEYSTATUS);

		/*
		 * If the key is unavailable and MS_CRYPT is set give the
		 * user a chance to enter the key. Otherwise just fail
		 * immediately.
		 */
		if (keystatus == ZFS_KEYSTATUS_UNAVAILABLE) {