cmd/mount_zfs/mount_zfs.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2011 Lawrence Livermore National Security, LLC.
  25  */
  26
  27 #include <libintl.h>
  28 #include <unistd.h>
  29 #include <sys/file.h>
  30 #include <sys/mount.h>
  31 #include <sys/mntent.h>
  32 #include <sys/stat.h>
  33 #include <libzfs.h>
  34 #include <libzutil.h>
  35 #include <locale.h>
  36 #include <getopt.h>
  37 #include <fcntl.h>
  38 #include <errno.h>
  39
  40 #define ZS_COMMENT      0x00000000      /* comment */
  41 #define ZS_ZFSUTIL      0x00000001      /* caller is zfs(8) */
  42
  43 libzfs_handle_t *g_zfs;
  44
  45 /*
  46  * Opportunistically convert a target string into a pool name. If the
  47  * string does not represent a block device with a valid zfs label
  48  * then it is passed through without modification.
  49  */
  50 static void
  51 parse_dataset(const char *target, char **dataset)
  52 {
  53         /*
  54          * Prior to util-linux 2.36.2, if a file or directory in the
  55          * current working directory was named 'dataset' then mount(8)
  56          * would prepend the current working directory to the dataset.
  57          * Check for it and strip the prepended path when it is added.
  58          */
  59         char cwd[PATH_MAX];
  60         if (getcwd(cwd, PATH_MAX) == NULL) {
  61                 perror("getcwd");
  62                 return;
  63         }
  64         int len = strlen(cwd);
  65         if (strncmp(cwd, target, len) == 0)
  66                 target += len;
  67
  68         /* Assume pool/dataset is more likely */
  69         strlcpy(*dataset, target, PATH_MAX);
  70
  71         int fd = open(target, O_RDONLY | O_CLOEXEC);
  72         if (fd < 0)
  73                 return;
  74
  75         nvlist_t *cfg = NULL;
  76         if (zpool_read_label(fd, &cfg, NULL) == 0) {
  77                 char *nm = NULL;
  78                 if (!nvlist_lookup_string(cfg, ZPOOL_CONFIG_POOL_NAME, &nm))
  79                         strlcpy(*dataset, nm, PATH_MAX);
  80                 nvlist_free(cfg);
  81         }
  82
  83         if (close(fd))
  84                 perror("close");
  85 }
  86
  87 /*
  88  * Update the mtab_* code to use the libmount library when it is commonly
  89  * available otherwise fallback to legacy mode.  The mount(8) utility will
  90  * manage the lock file for us to prevent racing updates to /etc/mtab.
  91  */
  92 static int
  93 mtab_is_writeable(void)
  94 {
  95         struct stat st;
  96         int error, fd;
  97
  98         error = lstat("/etc/mtab", &st);
  99         if (error || S_ISLNK(st.st_mode))
 100                 return (0);
 101
 102         fd = open("/etc/mtab", O_RDWR | O_CREAT, 0644);
 103         if (fd < 0)
 104                 return (0);
 105
 106         close(fd);
 107         return (1);
 108 }
 109
 110 static int
 111 mtab_update(char *dataset, char *mntpoint, char *type, char *mntopts)
 112 {
 113         struct mntent mnt;
 114         FILE *fp;
 115         int error;
 116
 117         mnt.mnt_fsname = dataset;
 118         mnt.mnt_dir = mntpoint;
 119         mnt.mnt_type = type;
 120         mnt.mnt_opts = mntopts ? mntopts : "";
 121         mnt.mnt_freq = 0;
 122         mnt.mnt_passno = 0;
 123
 124         fp = setmntent("/etc/mtab", "a+");
 125         if (!fp) {
 126                 (void) fprintf(stderr, gettext(
 127                     "filesystem '%s' was mounted, but /etc/mtab "
 128                     "could not be opened due to error: %s\n"),
 129                     dataset, strerror(errno));
 130                 return (MOUNT_FILEIO);
 131         }
 132
 133         error = addmntent(fp, &mnt);
 134         if (error) {
 135                 (void) fprintf(stderr, gettext(
 136                     "filesystem '%s' was mounted, but /etc/mtab "
 137                     "could not be updated due to error: %s\n"),
 138                     dataset, strerror(errno));
 139                 return (MOUNT_FILEIO);
 140         }
 141
 142         (void) endmntent(fp);
 143
 144         return (MOUNT_SUCCESS);
 145 }
 146
 147 int
 148 main(int argc, char **argv)
 149 {
 150         zfs_handle_t *zhp;
 151         char prop[ZFS_MAXPROPLEN];
 152         uint64_t zfs_version = 0;
 153         char mntopts[MNT_LINE_MAX] = { '\0' };
 154         char badopt[MNT_LINE_MAX] = { '\0' };
 155         char mtabopt[MNT_LINE_MAX] = { '\0' };
 156         char mntpoint[PATH_MAX];
 157         char dataset[PATH_MAX], *pdataset = dataset;
 158         unsigned long mntflags = 0, zfsflags = 0, remount = 0;
 159         int sloppy = 0, fake = 0, verbose = 0, nomtab = 0, zfsutil = 0;
 160         int error, c;
 161
 162         (void) setlocale(LC_ALL, "");
 163         (void) setlocale(LC_NUMERIC, "C");
 164         (void) textdomain(TEXT_DOMAIN);
 165
 166         opterr = 0;
 167
 168         /* check options */
 169         while ((c = getopt_long(argc, argv, "sfnvo:h?", 0, 0)) != -1) {
 170                 switch (c) {
 171                 case 's':
 172                         sloppy = 1;
 173                         break;
 174                 case 'f':
 175                         fake = 1;
 176                         break;
 177                 case 'n':
 178                         nomtab = 1;
 179                         break;
 180                 case 'v':
 181                         verbose++;
 182                         break;
 183                 case 'o':
 184                         (void) strlcpy(mntopts, optarg, sizeof (mntopts));
 185                         break;
 186                 case 'h':
 187                 case '?':
 188                         if (optopt)
 189                                 (void) fprintf(stderr,
 190                                     gettext("Invalid option '%c'\n"), optopt);
 191                         (void) fprintf(stderr, gettext("Usage: mount.zfs "
 192                             "[-sfnvh] [-o options] <dataset> <mountpoint>\n"));
 193                         return (MOUNT_USAGE);
 194                 }
 195         }
 196
 197         argc -= optind;
 198         argv += optind;
 199
 200         /* check that we only have two arguments */
 201         if (argc != 2) {
 202                 if (argc == 0)
 203                         (void) fprintf(stderr, gettext("missing dataset "
 204                             "argument\n"));
 205                 else if (argc == 1)
 206                         (void) fprintf(stderr,
 207                             gettext("missing mountpoint argument\n"));
 208                 else
 209                         (void) fprintf(stderr, gettext("too many arguments\n"));
 210                 (void) fprintf(stderr, "usage: mount <dataset> <mountpoint>\n");
 211                 return (MOUNT_USAGE);
 212         }
 213
 214         parse_dataset(argv[0], &pdataset);
 215
 216         /* canonicalize the mount point */
 217         if (realpath(argv[1], mntpoint) == NULL) {
 218                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 219                     "mounted at '%s' due to canonicalization error: %s\n"),
 220                     dataset, argv[1], strerror(errno));
 221                 return (MOUNT_SYSERR);
 222         }
 223
 224         /* validate mount options and set mntflags */
 225         error = zfs_parse_mount_options(mntopts, &mntflags, &zfsflags, sloppy,
 226             badopt, mtabopt);
 227         if (error) {
 228                 switch (error) {
 229                 case ENOMEM:
 230                         (void) fprintf(stderr, gettext("filesystem '%s' "
 231                             "cannot be mounted due to a memory allocation "
 232                             "failure.\n"), dataset);
 233                         return (MOUNT_SYSERR);
 234                 case ENOENT:
 235                         (void) fprintf(stderr, gettext("filesystem '%s' "
 236                             "cannot be mounted due to invalid option "
 237                             "'%s'.\n"), dataset, badopt);
 238                         (void) fprintf(stderr, gettext("Use the '-s' option "
 239                             "to ignore the bad mount option.\n"));
 240                         return (MOUNT_USAGE);
 241                 default:
 242                         (void) fprintf(stderr, gettext("filesystem '%s' "
 243                             "cannot be mounted due to internal error %d.\n"),
 244                             dataset, error);
 245                         return (MOUNT_SOFTWARE);
 246                 }
 247         }
 248
 249         if (mntflags & MS_REMOUNT) {
 250                 nomtab = 1;
 251                 remount = 1;
 252         }
 253
 254         if (zfsflags & ZS_ZFSUTIL)
 255                 zfsutil = 1;
 256
 257         if ((g_zfs = libzfs_init()) == NULL) {
 258                 (void) fprintf(stderr, "%s\n", libzfs_error_init(errno));
 259                 return (MOUNT_SYSERR);
 260         }
 261
 262         /* try to open the dataset to access the mount point */
 263         if ((zhp = zfs_open(g_zfs, dataset,
 264             ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT)) == NULL) {
 265                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 266                     "mounted, unable to open the dataset\n"), dataset);
 267                 libzfs_fini(g_zfs);
 268                 return (MOUNT_USAGE);
 269         }
 270
 271         if (!zfsutil || sloppy ||
 272             libzfs_envvar_is_set("ZFS_MOUNT_HELPER")) {
 273                 zfs_adjust_mount_options(zhp, mntpoint, mntopts, mtabopt);
 274         }
 275
 276         /* treat all snapshots as legacy mount points */
 277         if (zfs_get_type(zhp) == ZFS_TYPE_SNAPSHOT)
 278                 (void) strlcpy(prop, ZFS_MOUNTPOINT_LEGACY, ZFS_MAXPROPLEN);
 279         else
 280                 (void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, prop,
 281                     sizeof (prop), NULL, NULL, 0, B_FALSE);
 282
 283         /*
 284          * Fetch the max supported zfs version in case we get ENOTSUP
 285          * back from the mount command, since we need the zfs handle
 286          * to do so.
 287          */
 288         zfs_version = zfs_prop_get_int(zhp, ZFS_PROP_VERSION);
 289         if (zfs_version == 0) {
 290                 fprintf(stderr, gettext("unable to fetch "
 291                     "ZFS version for filesystem '%s'\n"), dataset);
 292                 zfs_close(zhp);
 293                 libzfs_fini(g_zfs);
 294                 return (MOUNT_SYSERR);
 295         }
 296
 297         /*
 298          * Legacy mount points may only be mounted using 'mount', never using
 299          * 'zfs mount'.  However, since 'zfs mount' actually invokes 'mount'
 300          * we differentiate the two cases using the 'zfsutil' mount option.
 301          * This mount option should only be supplied by the 'zfs mount' util.
 302          *
 303          * The only exception to the above rule is '-o remount' which is
 304          * always allowed for non-legacy datasets.  This is done because when
 305          * using zfs as your root file system both rc.sysinit/umountroot and
 306          * systemd depend on 'mount -o remount <mountpoint>' to work.
 307          */
 308         if (zfsutil && (strcmp(prop, ZFS_MOUNTPOINT_LEGACY) == 0)) {
 309                 (void) fprintf(stderr, gettext(
 310                     "filesystem '%s' cannot be mounted using 'zfs mount'.\n"
 311                     "Use 'zfs set mountpoint=%s' or 'mount -t zfs %s %s'.\n"
 312                     "See zfs(8) for more information.\n"),
 313                     dataset, mntpoint, dataset, mntpoint);
 314                 zfs_close(zhp);
 315                 libzfs_fini(g_zfs);
 316                 return (MOUNT_USAGE);
 317         }
 318
 319         if (!zfsutil && !(remount || fake) &&
 320             strcmp(prop, ZFS_MOUNTPOINT_LEGACY)) {
 321                 (void) fprintf(stderr, gettext(
 322                     "filesystem '%s' cannot be mounted using 'mount'.\n"
 323                     "Use 'zfs set mountpoint=%s' or 'zfs mount %s'.\n"
 324                     "See zfs(8) for more information.\n"),
 325                     dataset, "legacy", dataset);
 326                 zfs_close(zhp);
 327                 libzfs_fini(g_zfs);
 328                 return (MOUNT_USAGE);
 329         }
 330
 331         if (verbose)
 332                 (void) fprintf(stdout, gettext("mount.zfs:\n"
 333                     "  dataset:    \"%s\"\n  mountpoint: \"%s\"\n"
 334                     "  mountflags: 0x%lx\n  zfsflags:   0x%lx\n"
 335                     "  mountopts:  \"%s\"\n  mtabopts:   \"%s\"\n"),
 336                     dataset, mntpoint, mntflags, zfsflags, mntopts, mtabopt);
 337
 338         if (!fake) {
 339                 if (zfsutil && !sloppy &&
 340                     !libzfs_envvar_is_set("ZFS_MOUNT_HELPER")) {
 341                         error = zfs_mount_at(zhp, mntopts, mntflags, mntpoint);
 342                         if (error) {
 343                                 (void) fprintf(stderr, "zfs_mount_at() failed: "
 344                                     "%s", libzfs_error_description(g_zfs));
 345                                 zfs_close(zhp);
 346                                 libzfs_fini(g_zfs);
 347                                 return (MOUNT_SYSERR);
 348                         }
 349                 } else {
 350                         error = mount(dataset, mntpoint, MNTTYPE_ZFS,
 351                             mntflags, mntopts);
 352                 }
 353         }
 354
 355         zfs_close(zhp);
 356         libzfs_fini(g_zfs);
 357
 358         if (error) {
 359                 switch (errno) {
 360                 case ENOENT:
 361                         (void) fprintf(stderr, gettext("mount point "
 362                             "'%s' does not exist\n"), mntpoint);
 363                         return (MOUNT_SYSERR);
 364                 case EBUSY:
 365                         (void) fprintf(stderr, gettext("filesystem "
 366                             "'%s' is already mounted\n"), dataset);
 367                         return (MOUNT_BUSY);
 368                 case ENOTSUP:
 369                         if (zfs_version > ZPL_VERSION) {
 370                                 (void) fprintf(stderr,
 371                                     gettext("filesystem '%s' (v%d) is not "
 372                                     "supported by this implementation of "
 373                                     "ZFS (max v%d).\n"), dataset,
 374                                     (int)zfs_version, (int)ZPL_VERSION);
 375                         } else {
 376                                 (void) fprintf(stderr,
 377                                     gettext("filesystem '%s' mount "
 378                                     "failed for unknown reason.\n"), dataset);
 379                         }
 380                         return (MOUNT_SYSERR);
 381 #ifdef MS_MANDLOCK
 382                 case EPERM:
 383                         if (mntflags & MS_MANDLOCK) {
 384                                 (void) fprintf(stderr, gettext("filesystem "
 385                                     "'%s' has the 'nbmand=on' property set, "
 386                                     "this mount\noption may be disabled in "
 387                                     "your kernel.  Use 'zfs set nbmand=off'\n"
 388                                     "to disable this option and try to "
 389                                     "mount the filesystem again.\n"), dataset);
 390                                 return (MOUNT_SYSERR);
 391                         }
 392 #endif
 393                         zfs_fallthrough;
 394                 default:
 395                         (void) fprintf(stderr, gettext("filesystem "
 396                             "'%s' can not be mounted: %s\n"), dataset,
 397                             strerror(errno));
 398                         return (MOUNT_USAGE);
 399                 }
 400         }
 401
 402         if (!nomtab && mtab_is_writeable()) {
 403                 error = mtab_update(dataset, mntpoint, MNTTYPE_ZFS, mtabopt);
 404                 if (error)
 405                         return (error);
 406         }
 407
 408         return (MOUNT_SUCCESS);
 409 }