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