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/stat.h>
  32 #include <libzfs.h>
  33 #include <locale.h>
  34 #ifdef HAVE_LIBSELINUX
  35 #include <selinux/selinux.h>
  36 #endif /* HAVE_LIBSELINUX */
  37
  38 libzfs_handle_t *g_zfs;
  39
  40 typedef struct option_map {
  41         const char *name;
  42         unsigned long mntmask;
  43         unsigned long zfsmask;
  44 } option_map_t;
  45
  46 static const option_map_t option_map[] = {
  47         /* Canonicalized filesystem independent options from mount(8) */
  48         { MNTOPT_NOAUTO,        MS_COMMENT,     ZS_COMMENT      },
  49         { MNTOPT_DEFAULTS,      MS_COMMENT,     ZS_COMMENT      },
  50         { MNTOPT_NODEVICES,     MS_NODEV,       ZS_COMMENT      },
  51         { MNTOPT_DIRSYNC,       MS_DIRSYNC,     ZS_COMMENT      },
  52         { MNTOPT_NOEXEC,        MS_NOEXEC,      ZS_COMMENT      },
  53         { MNTOPT_GROUP,         MS_GROUP,       ZS_COMMENT      },
  54         { MNTOPT_NETDEV,        MS_COMMENT,     ZS_COMMENT      },
  55         { MNTOPT_NOFAIL,        MS_COMMENT,     ZS_COMMENT      },
  56         { MNTOPT_NOSUID,        MS_NOSUID,      ZS_COMMENT      },
  57         { MNTOPT_OWNER,         MS_OWNER,       ZS_COMMENT      },
  58         { MNTOPT_REMOUNT,       MS_REMOUNT,     ZS_COMMENT      },
  59         { MNTOPT_RO,            MS_RDONLY,      ZS_COMMENT      },
  60         { MNTOPT_RW,            MS_COMMENT,     ZS_COMMENT      },
  61         { MNTOPT_SYNC,          MS_SYNCHRONOUS, ZS_COMMENT      },
  62         { MNTOPT_USER,          MS_USERS,       ZS_COMMENT      },
  63         { MNTOPT_USERS,         MS_USERS,       ZS_COMMENT      },
  64         /* acl flags passed with util-linux-2.24 mount command */
  65         { MNTOPT_ACL,           MS_POSIXACL,    ZS_COMMENT      },
  66         { MNTOPT_NOACL,         MS_COMMENT,     ZS_COMMENT      },
  67         { MNTOPT_POSIXACL,      MS_POSIXACL,    ZS_COMMENT      },
  68 #ifdef MS_NOATIME
  69         { MNTOPT_NOATIME,       MS_NOATIME,     ZS_COMMENT      },
  70 #endif
  71 #ifdef MS_NODIRATIME
  72         { MNTOPT_NODIRATIME,    MS_NODIRATIME,  ZS_COMMENT      },
  73 #endif
  74 #ifdef MS_RELATIME
  75         { MNTOPT_RELATIME,      MS_RELATIME,    ZS_COMMENT      },
  76 #endif
  77 #ifdef MS_STRICTATIME
  78         { MNTOPT_DFRATIME,      MS_STRICTATIME, ZS_COMMENT      },
  79 #endif
  80         { MNTOPT_CONTEXT,       MS_COMMENT,     ZS_NOCONTEXT    },
  81         { MNTOPT_NOCONTEXT,     MS_COMMENT,     ZS_NOCONTEXT    },
  82         { MNTOPT_FSCONTEXT,     MS_COMMENT,     ZS_NOCONTEXT    },
  83         { MNTOPT_DEFCONTEXT,    MS_COMMENT,     ZS_NOCONTEXT    },
  84         { MNTOPT_ROOTCONTEXT,   MS_COMMENT,     ZS_NOCONTEXT    },
  85 #ifdef MS_I_VERSION
  86         { MNTOPT_IVERSION,      MS_I_VERSION,   ZS_COMMENT      },
  87 #endif
  88 #ifdef MS_MANDLOCK
  89         { MNTOPT_NBMAND,        MS_MANDLOCK,    ZS_COMMENT      },
  90 #endif
  91         /* Valid options not found in mount(8) */
  92         { MNTOPT_BIND,          MS_BIND,        ZS_COMMENT      },
  93 #ifdef MS_REC
  94         { MNTOPT_RBIND,         MS_BIND|MS_REC, ZS_COMMENT      },
  95 #endif
  96         { MNTOPT_COMMENT,       MS_COMMENT,     ZS_COMMENT      },
  97 #ifdef MS_NOSUB
  98         { MNTOPT_NOSUB,         MS_NOSUB,       ZS_COMMENT      },
  99 #endif
 100 #ifdef MS_SILENT
 101         { MNTOPT_QUIET,         MS_SILENT,      ZS_COMMENT      },
 102 #endif
 103         /* Custom zfs options */
 104         { MNTOPT_XATTR,         MS_COMMENT,     ZS_COMMENT      },
 105         { MNTOPT_NOXATTR,       MS_COMMENT,     ZS_COMMENT      },
 106         { MNTOPT_ZFSUTIL,       MS_COMMENT,     ZS_ZFSUTIL      },
 107         { NULL,                 0,              0               } };
 108
 109 /*
 110  * Break the mount option in to a name/value pair.  The name is
 111  * validated against the option map and mount flags set accordingly.
 112  */
 113 static int
 114 parse_option(char *mntopt, unsigned long *mntflags,
 115     unsigned long *zfsflags, int sloppy)
 116 {
 117         const option_map_t *opt;
 118         char *ptr, *name, *value = NULL;
 119         int error = 0;
 120
 121         name = strdup(mntopt);
 122         if (name == NULL)
 123                 return (ENOMEM);
 124
 125         for (ptr = name; ptr && *ptr; ptr++) {
 126                 if (*ptr == '=') {
 127                         *ptr = '\0';
 128                         value = ptr+1;
 129                         VERIFY3P(value, !=, NULL);
 130                         break;
 131                 }
 132         }
 133
 134         for (opt = option_map; opt->name != NULL; opt++) {
 135                 if (strncmp(name, opt->name, strlen(name)) == 0) {
 136                         *mntflags |= opt->mntmask;
 137                         *zfsflags |= opt->zfsmask;
 138                         error = 0;
 139                         goto out;
 140                 }
 141         }
 142
 143         if (!sloppy)
 144                 error = ENOENT;
 145 out:
 146         /* If required further process on the value may be done here */
 147         free(name);
 148         return (error);
 149 }
 150
 151 /*
 152  * Translate the mount option string in to MS_* mount flags for the
 153  * kernel vfs.  When sloppy is non-zero unknown options will be ignored
 154  * otherwise they are considered fatal are copied in to badopt.
 155  */
 156 static int
 157 parse_options(char *mntopts, unsigned long *mntflags, unsigned long *zfsflags,
 158     int sloppy, char *badopt, char *mtabopt)
 159 {
 160         int error = 0, quote = 0, flag = 0, count = 0;
 161         char *ptr, *opt, *opts;
 162
 163         opts = strdup(mntopts);
 164         if (opts == NULL)
 165                 return (ENOMEM);
 166
 167         *mntflags = 0;
 168         opt = NULL;
 169
 170         /*
 171          * Scan through all mount options which must be comma delimited.
 172          * We must be careful to notice regions which are double quoted
 173          * and skip commas in these regions.  Each option is then checked
 174          * to determine if it is a known option.
 175          */
 176         for (ptr = opts; ptr && !flag; ptr++) {
 177                 if (opt == NULL)
 178                         opt = ptr;
 179
 180                 if (*ptr == '"')
 181                         quote = !quote;
 182
 183                 if (quote)
 184                         continue;
 185
 186                 if (*ptr == '\0')
 187                         flag = 1;
 188
 189                 if ((*ptr == ',') || (*ptr == '\0')) {
 190                         *ptr = '\0';
 191
 192                         error = parse_option(opt, mntflags, zfsflags, sloppy);
 193                         if (error) {
 194                                 strcpy(badopt, opt);
 195                                 goto out;
 196
 197                         }
 198
 199                         if (!(*mntflags & MS_REMOUNT) &&
 200                             !(*zfsflags & ZS_ZFSUTIL)) {
 201                                 if (count > 0)
 202                                         strlcat(mtabopt, ",", MNT_LINE_MAX);
 203
 204                                 strlcat(mtabopt, opt, MNT_LINE_MAX);
 205                                 count++;
 206                         }
 207
 208                         opt = NULL;
 209                 }
 210         }
 211
 212 out:
 213         free(opts);
 214         return (error);
 215 }
 216
 217 /*
 218  * Return the pool/dataset to mount given the name passed to mount.  This
 219  * is expected to be of the form pool/dataset, however may also refer to
 220  * a block device if that device contains a valid zfs label.
 221  */
 222 static char *
 223 parse_dataset(char *dataset)
 224 {
 225         char cwd[PATH_MAX];
 226         struct stat64 statbuf;
 227         int error;
 228         int len;
 229
 230         /*
 231          * We expect a pool/dataset to be provided, however if we're
 232          * given a device which is a member of a zpool we attempt to
 233          * extract the pool name stored in the label.  Given the pool
 234          * name we can mount the root dataset.
 235          */
 236         error = stat64(dataset, &statbuf);
 237         if (error == 0) {
 238                 nvlist_t *config;
 239                 char *name;
 240                 int fd;
 241
 242                 fd = open(dataset, O_RDONLY);
 243                 if (fd < 0)
 244                         goto out;
 245
 246                 error = zpool_read_label(fd, &config);
 247                 (void) close(fd);
 248                 if (error)
 249                         goto out;
 250
 251                 error = nvlist_lookup_string(config,
 252                     ZPOOL_CONFIG_POOL_NAME, &name);
 253                 if (error) {
 254                         nvlist_free(config);
 255                 } else {
 256                         dataset = strdup(name);
 257                         nvlist_free(config);
 258                         return (dataset);
 259                 }
 260         }
 261 out:
 262         /*
 263          * If a file or directory in your current working directory is
 264          * named 'dataset' then mount(8) will prepend your current working
 265          * directory to the dataset.  There is no way to prevent this
 266          * behavior so we simply check for it and strip the prepended
 267          * patch when it is added.
 268          */
 269         if (getcwd(cwd, PATH_MAX) == NULL)
 270                 return (dataset);
 271
 272         len = strlen(cwd);
 273
 274         /* Do not add one when cwd already ends in a trailing '/' */
 275         if (strncmp(cwd, dataset, len) == 0)
 276                 return (dataset + len + (cwd[len-1] != '/'));
 277
 278         return (dataset);
 279 }
 280
 281 /*
 282  * Update the mtab_* code to use the libmount library when it is commonly
 283  * available otherwise fallback to legacy mode.  The mount(8) utility will
 284  * manage the lock file for us to prevent racing updates to /etc/mtab.
 285  */
 286 static int
 287 mtab_is_writeable(void)
 288 {
 289         struct stat st;
 290         int error, fd;
 291
 292         error = lstat(MNTTAB, &st);
 293         if (error || S_ISLNK(st.st_mode))
 294                 return (0);
 295
 296         fd = open(MNTTAB, O_RDWR | O_CREAT, 0644);
 297         if (fd < 0)
 298                 return (0);
 299
 300         close(fd);
 301         return (1);
 302 }
 303
 304 static int
 305 mtab_update(char *dataset, char *mntpoint, char *type, char *mntopts)
 306 {
 307         struct mntent mnt;
 308         FILE *fp;
 309         int error;
 310
 311         mnt.mnt_fsname = dataset;
 312         mnt.mnt_dir = mntpoint;
 313         mnt.mnt_type = type;
 314         mnt.mnt_opts = mntopts ? mntopts : "";
 315         mnt.mnt_freq = 0;
 316         mnt.mnt_passno = 0;
 317
 318         fp = setmntent(MNTTAB, "a+");
 319         if (!fp) {
 320                 (void) fprintf(stderr, gettext(
 321                     "filesystem '%s' was mounted, but %s "
 322                     "could not be opened due to error %d\n"),
 323                     dataset, MNTTAB, errno);
 324                 return (MOUNT_FILEIO);
 325         }
 326
 327         error = addmntent(fp, &mnt);
 328         if (error) {
 329                 (void) fprintf(stderr, gettext(
 330                     "filesystem '%s' was mounted, but %s "
 331                     "could not be updated due to error %d\n"),
 332                     dataset, MNTTAB, errno);
 333                 return (MOUNT_FILEIO);
 334         }
 335
 336         (void) endmntent(fp);
 337
 338         return (MOUNT_SUCCESS);
 339 }
 340
 341 int
 342 main(int argc, char **argv)
 343 {
 344         zfs_handle_t *zhp;
 345         char legacy[ZFS_MAXPROPLEN];
 346         char mntopts[MNT_LINE_MAX] = { '\0' };
 347         char badopt[MNT_LINE_MAX] = { '\0' };
 348         char mtabopt[MNT_LINE_MAX] = { '\0' };
 349         char mntpoint[PATH_MAX];
 350         char *dataset;
 351         unsigned long mntflags = 0, zfsflags = 0, remount = 0;
 352         int sloppy = 0, fake = 0, verbose = 0, nomtab = 0, zfsutil = 0;
 353         int error, c;
 354
 355         (void) setlocale(LC_ALL, "");
 356         (void) textdomain(TEXT_DOMAIN);
 357
 358         opterr = 0;
 359
 360         /* check options */
 361         while ((c = getopt(argc, argv, "sfnvo:h?")) != -1) {
 362                 switch (c) {
 363                 case 's':
 364                         sloppy = 1;
 365                         break;
 366                 case 'f':
 367                         fake = 1;
 368                         break;
 369                 case 'n':
 370                         nomtab = 1;
 371                         break;
 372                 case 'v':
 373                         verbose++;
 374                         break;
 375                 case 'o':
 376                         (void) strlcpy(mntopts, optarg, sizeof (mntopts));
 377                         break;
 378                 case 'h':
 379                 case '?':
 380                         (void) fprintf(stderr, gettext("Invalid option '%c'\n"),
 381                             optopt);
 382                         (void) fprintf(stderr, gettext("Usage: mount.zfs "
 383                             "[-sfnv] [-o options] <dataset> <mountpoint>\n"));
 384                         return (MOUNT_USAGE);
 385                 }
 386         }
 387
 388         argc -= optind;
 389         argv += optind;
 390
 391         /* check that we only have two arguments */
 392         if (argc != 2) {
 393                 if (argc == 0)
 394                         (void) fprintf(stderr, gettext("missing dataset "
 395                             "argument\n"));
 396                 else if (argc == 1)
 397                         (void) fprintf(stderr,
 398                             gettext("missing mountpoint argument\n"));
 399                 else
 400                         (void) fprintf(stderr, gettext("too many arguments\n"));
 401                 (void) fprintf(stderr, "usage: mount <dataset> <mountpoint>\n");
 402                 return (MOUNT_USAGE);
 403         }
 404
 405         dataset = parse_dataset(argv[0]);
 406
 407         /* canonicalize the mount point */
 408         if (realpath(argv[1], mntpoint) == NULL) {
 409                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 410                     "mounted at '%s' due to canonicalization error %d.\n"),
 411                     dataset, argv[1], errno);
 412                 return (MOUNT_SYSERR);
 413         }
 414
 415         /* validate mount options and set mntflags */
 416         error = parse_options(mntopts, &mntflags, &zfsflags, sloppy,
 417             badopt, mtabopt);
 418         if (error) {
 419                 switch (error) {
 420                 case ENOMEM:
 421                         (void) fprintf(stderr, gettext("filesystem '%s' "
 422                             "cannot be mounted due to a memory allocation "
 423                             "failure.\n"), dataset);
 424                         return (MOUNT_SYSERR);
 425                 case ENOENT:
 426                         (void) fprintf(stderr, gettext("filesystem '%s' "
 427                             "cannot be mounted due to invalid option "
 428                             "'%s'.\n"), dataset, badopt);
 429                         (void) fprintf(stderr, gettext("Use the '-s' option "
 430                             "to ignore the bad mount option.\n"));
 431                         return (MOUNT_USAGE);
 432                 default:
 433                         (void) fprintf(stderr, gettext("filesystem '%s' "
 434                             "cannot be mounted due to internal error %d.\n"),
 435                             dataset, error);
 436                         return (MOUNT_SOFTWARE);
 437                 }
 438         }
 439
 440 #ifdef HAVE_LIBSELINUX
 441         /*
 442          * Automatically add the default zfs context when selinux is enabled
 443          * and the caller has not specified their own context.  This must be
 444          * done until zfs is added to the default selinux policy configuration
 445          * as a known filesystem type which supports xattrs.
 446          */
 447         if (is_selinux_enabled() && !(zfsflags & ZS_NOCONTEXT)) {
 448                 (void) strlcat(mntopts, ",context=\"system_u:"
 449                     "object_r:file_t:s0\"", sizeof (mntopts));
 450                 (void) strlcat(mtabopt, ",context=\"system_u:"
 451                     "object_r:file_t:s0\"", sizeof (mtabopt));
 452         }
 453 #endif /* HAVE_LIBSELINUX */
 454
 455
 456         if (verbose)
 457                 (void) fprintf(stdout, gettext("mount.zfs:\n"
 458                     "  dataset:    \"%s\"\n  mountpoint: \"%s\"\n"
 459                     "  mountflags: 0x%lx\n  zfsflags:   0x%lx\n"
 460                     "  mountopts:  \"%s\"\n  mtabopts:   \"%s\"\n"),
 461                     dataset, mntpoint, mntflags, zfsflags, mntopts, mtabopt);
 462
 463         if (mntflags & MS_REMOUNT) {
 464                 nomtab = 1;
 465                 remount = 1;
 466         }
 467
 468         if (zfsflags & ZS_ZFSUTIL)
 469                 zfsutil = 1;
 470
 471         if ((g_zfs = libzfs_init()) == NULL)
 472                 return (MOUNT_SYSERR);
 473
 474         /* try to open the dataset to access the mount point */
 475         if ((zhp = zfs_open(g_zfs, dataset,
 476             ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT)) == NULL) {
 477                 (void) fprintf(stderr, gettext("filesystem '%s' cannot be "
 478                     "mounted, unable to open the dataset\n"), dataset);
 479                 libzfs_fini(g_zfs);
 480                 return (MOUNT_USAGE);
 481         }
 482
 483         /* treat all snapshots as legacy mount points */
 484         if (zfs_get_type(zhp) == ZFS_TYPE_SNAPSHOT)
 485                 (void) strlcpy(legacy, ZFS_MOUNTPOINT_LEGACY, ZFS_MAXPROPLEN);
 486         else
 487                 (void) zfs_prop_get(zhp, ZFS_PROP_MOUNTPOINT, legacy,
 488                     sizeof (legacy), NULL, NULL, 0, B_FALSE);
 489
 490         zfs_close(zhp);
 491         libzfs_fini(g_zfs);
 492
 493         /*
 494          * Legacy mount points may only be mounted using 'mount', never using
 495          * 'zfs mount'.  However, since 'zfs mount' actually invokes 'mount'
 496          * we differentiate the two cases using the 'zfsutil' mount option.
 497          * This mount option should only be supplied by the 'zfs mount' util.
 498          *
 499          * The only exception to the above rule is '-o remount' which is
 500          * always allowed for non-legacy datasets.  This is done because when
 501          * using zfs as your root file system both rc.sysinit/umountroot and
 502          * systemd depend on 'mount -o remount <mountpoint>' to work.
 503          */
 504         if (zfsutil && (strcmp(legacy, ZFS_MOUNTPOINT_LEGACY) == 0)) {
 505                 (void) fprintf(stderr, gettext(
 506                     "filesystem '%s' cannot be mounted using 'zfs mount'.\n"
 507                     "Use 'zfs set mountpoint=%s' or 'mount -t zfs %s %s'.\n"
 508                     "See zfs(8) for more information.\n"),
 509                     dataset, mntpoint, dataset, mntpoint);
 510                 return (MOUNT_USAGE);
 511         }
 512
 513         if (!zfsutil && !(remount || fake) &&
 514             strcmp(legacy, ZFS_MOUNTPOINT_LEGACY)) {
 515                 (void) fprintf(stderr, gettext(
 516                     "filesystem '%s' cannot be mounted using 'mount'.\n"
 517                     "Use 'zfs set mountpoint=%s' or 'zfs mount %s'.\n"
 518                     "See zfs(8) for more information.\n"),
 519                     dataset, "legacy", dataset);
 520                 return (MOUNT_USAGE);
 521         }
 522
 523         if (!fake) {
 524                 error = mount(dataset, mntpoint, MNTTYPE_ZFS,
 525                     mntflags, mntopts);
 526                 if (error) {
 527                         switch (errno) {
 528                         case ENOENT:
 529                                 (void) fprintf(stderr, gettext("mount point "
 530                                     "'%s' does not exist\n"), mntpoint);
 531                                 return (MOUNT_SYSERR);
 532                         case EBUSY:
 533                                 (void) fprintf(stderr, gettext("filesystem "
 534                                     "'%s' is already mounted\n"), dataset);
 535                                 return (MOUNT_BUSY);
 536                         default:
 537                                 (void) fprintf(stderr, gettext("filesystem "
 538                                     "'%s' can not be mounted due to error "
 539                                     "%d\n"), dataset, errno);
 540                                 return (MOUNT_USAGE);
 541                         }
 542                 }
 543         }
 544
 545         if (!nomtab && mtab_is_writeable()) {
 546                 error = mtab_update(dataset, mntpoint, MNTTYPE_ZFS, mtabopt);
 547                 if (error)
 548                         return (error);
 549         }
 550
 551         return (MOUNT_SUCCESS);
 552 }