src/core/umount.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 ProFUSION embedded systems
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <string.h>
  25 #include <sys/mount.h>
  26 #include <sys/swap.h>
  27 #include <unistd.h>
  28 #include <linux/loop.h>
  29 #include <linux/dm-ioctl.h>
  30 #include <libudev.h>
  31
  32 #include "list.h"
  33 #include "mount-setup.h"
  34 #include "umount.h"
  35 #include "path-util.h"
  36 #include "util.h"
  37 #include "virt.h"
  38
  39 typedef struct MountPoint {
  40         char *path;
  41         dev_t devnum;
  42         LIST_FIELDS (struct MountPoint, mount_point);
  43 } MountPoint;
  44
  45 static void mount_point_free(MountPoint **head, MountPoint *m) {
  46         assert(head);
  47         assert(m);
  48
  49         LIST_REMOVE(MountPoint, mount_point, *head, m);
  50
  51         free(m->path);
  52         free(m);
  53 }
  54
  55 static void mount_points_list_free(MountPoint **head) {
  56         assert(head);
  57
  58         while (*head)
  59                 mount_point_free(head, *head);
  60 }
  61
  62 static int mount_points_list_get(MountPoint **head) {
  63         FILE *proc_self_mountinfo;
  64         char *path, *p;
  65         unsigned int i;
  66         int r;
  67
  68         assert(head);
  69
  70         if (!(proc_self_mountinfo = fopen("/proc/self/mountinfo", "re")))
  71                 return -errno;
  72
  73         for (i = 1;; i++) {
  74                 int k;
  75                 MountPoint *m;
  76
  77                 path = p = NULL;
  78
  79                 if ((k = fscanf(proc_self_mountinfo,
  80                                 "%*s "       /* (1) mount id */
  81                                 "%*s "       /* (2) parent id */
  82                                 "%*s "       /* (3) major:minor */
  83                                 "%*s "       /* (4) root */
  84                                 "%ms "       /* (5) mount point */
  85                                 "%*s"        /* (6) mount options */
  86                                 "%*[^-]"     /* (7) optional fields */
  87                                 "- "         /* (8) separator */
  88                                 "%*s "       /* (9) file system type */
  89                                 "%*s"        /* (10) mount source */
  90                                 "%*s"        /* (11) mount options 2 */
  91                                 "%*[^\n]",   /* some rubbish at the end */
  92                                 &path)) != 1) {
  93                         if (k == EOF)
  94                                 break;
  95
  96                         log_warning("Failed to parse /proc/self/mountinfo:%u.", i);
  97
  98                         free(path);
  99                         continue;
 100                 }
 101
 102                 p = cunescape(path);
 103                 free(path);
 104
 105                 if (!p) {
 106                         r = -ENOMEM;
 107                         goto finish;
 108                 }
 109
 110                 /* Ignore mount points we can't unmount because they
 111                  * are API or because we are keeping them open (like
 112                  * /dev/console) */
 113                 if (mount_point_is_api(p) ||
 114                     mount_point_ignore(p) ||
 115                     path_equal(p, "/dev/console")) {
 116                         free(p);
 117                         continue;
 118                 }
 119
 120                 if (!(m = new0(MountPoint, 1))) {
 121                         free(p);
 122                         r = -ENOMEM;
 123                         goto finish;
 124                 }
 125
 126                 m->path = p;
 127                 LIST_PREPEND(MountPoint, mount_point, *head, m);
 128         }
 129
 130         r = 0;
 131
 132 finish:
 133         fclose(proc_self_mountinfo);
 134
 135         return r;
 136 }
 137
 138 static int swap_list_get(MountPoint **head) {
 139         FILE *proc_swaps;
 140         unsigned int i;
 141         int r;
 142
 143         assert(head);
 144
 145         if (!(proc_swaps = fopen("/proc/swaps", "re")))
 146                 return (errno == ENOENT) ? 0 : -errno;
 147
 148         (void) fscanf(proc_swaps, "%*s %*s %*s %*s %*s\n");
 149
 150         for (i = 2;; i++) {
 151                 MountPoint *swap;
 152                 char *dev = NULL, *d;
 153                 int k;
 154
 155                 if ((k = fscanf(proc_swaps,
 156                                 "%ms " /* device/file */
 157                                 "%*s " /* type of swap */
 158                                 "%*s " /* swap size */
 159                                 "%*s " /* used */
 160                                 "%*s\n", /* priority */
 161                                 &dev)) != 1) {
 162
 163                         if (k == EOF)
 164                                 break;
 165
 166                         log_warning("Failed to parse /proc/swaps:%u.", i);
 167
 168                         free(dev);
 169                         continue;
 170                 }
 171
 172                 if (endswith(dev, "(deleted)")) {
 173                         free(dev);
 174                         continue;
 175                 }
 176
 177                 d = cunescape(dev);
 178                 free(dev);
 179
 180                 if (!d) {
 181                         r = -ENOMEM;
 182                         goto finish;
 183                 }
 184
 185                 if (!(swap = new0(MountPoint, 1))) {
 186                         free(d);
 187                         r = -ENOMEM;
 188                         goto finish;
 189                 }
 190
 191                 swap->path = d;
 192                 LIST_PREPEND(MountPoint, mount_point, *head, swap);
 193         }
 194
 195         r = 0;
 196
 197 finish:
 198         fclose(proc_swaps);
 199
 200         return r;
 201 }
 202
 203 static int loopback_list_get(MountPoint **head) {
 204         int r;
 205         struct udev *udev;
 206         struct udev_enumerate *e = NULL;
 207         struct udev_list_entry *item = NULL, *first = NULL;
 208
 209         assert(head);
 210
 211         if (!(udev = udev_new())) {
 212                 r = -ENOMEM;
 213                 goto finish;
 214         }
 215
 216         if (!(e = udev_enumerate_new(udev))) {
 217                 r = -ENOMEM;
 218                 goto finish;
 219         }
 220
 221         if (udev_enumerate_add_match_subsystem(e, "block") < 0 ||
 222             udev_enumerate_add_match_sysname(e, "loop*") < 0 ||
 223             udev_enumerate_add_match_sysattr(e, "loop/backing_file", NULL) < 0) {
 224                 r = -EIO;
 225                 goto finish;
 226         }
 227
 228         if (udev_enumerate_scan_devices(e) < 0) {
 229                 r = -EIO;
 230                 goto finish;
 231         }
 232
 233         first = udev_enumerate_get_list_entry(e);
 234         udev_list_entry_foreach(item, first) {
 235                 MountPoint *lb;
 236                 struct udev_device *d;
 237                 char *loop;
 238                 const char *dn;
 239
 240                 if (!(d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)))) {
 241                         r = -ENOMEM;
 242                         goto finish;
 243                 }
 244
 245                 if (!(dn = udev_device_get_devnode(d))) {
 246                         udev_device_unref(d);
 247                         continue;
 248                 }
 249
 250                 loop = strdup(dn);
 251                 udev_device_unref(d);
 252
 253                 if (!loop) {
 254                         r = -ENOMEM;
 255                         goto finish;
 256                 }
 257
 258                 if (!(lb = new0(MountPoint, 1))) {
 259                         free(loop);
 260                         r = -ENOMEM;
 261                         goto finish;
 262                 }
 263
 264                 lb->path = loop;
 265                 LIST_PREPEND(MountPoint, mount_point, *head, lb);
 266         }
 267
 268         r = 0;
 269
 270 finish:
 271         if (e)
 272                 udev_enumerate_unref(e);
 273
 274         if (udev)
 275                 udev_unref(udev);
 276
 277         return r;
 278 }
 279
 280 static int dm_list_get(MountPoint **head) {
 281         int r;
 282         struct udev *udev;
 283         struct udev_enumerate *e = NULL;
 284         struct udev_list_entry *item = NULL, *first = NULL;
 285
 286         assert(head);
 287
 288         if (!(udev = udev_new())) {
 289                 r = -ENOMEM;
 290                 goto finish;
 291         }
 292
 293         if (!(e = udev_enumerate_new(udev))) {
 294                 r = -ENOMEM;
 295                 goto finish;
 296         }
 297
 298         if (udev_enumerate_add_match_subsystem(e, "block") < 0 ||
 299             udev_enumerate_add_match_sysname(e, "dm-*") < 0) {
 300                 r = -EIO;
 301                 goto finish;
 302         }
 303
 304         if (udev_enumerate_scan_devices(e) < 0) {
 305                 r = -EIO;
 306                 goto finish;
 307         }
 308
 309         first = udev_enumerate_get_list_entry(e);
 310
 311         udev_list_entry_foreach(item, first) {
 312                 MountPoint *m;
 313                 struct udev_device *d;
 314                 dev_t devnum;
 315                 char *node;
 316                 const char *dn;
 317
 318                 if (!(d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)))) {
 319                         r = -ENOMEM;
 320                         goto finish;
 321                 }
 322
 323                 devnum = udev_device_get_devnum(d);
 324                 dn = udev_device_get_devnode(d);
 325
 326                 if (major(devnum) == 0 || !dn) {
 327                         udev_device_unref(d);
 328                         continue;
 329                 }
 330
 331                 node = strdup(dn);
 332                 udev_device_unref(d);
 333
 334                 if (!node) {
 335                         r = -ENOMEM;
 336                         goto finish;
 337                 }
 338
 339                 if (!(m = new(MountPoint, 1))) {
 340                         free(node);
 341                         r = -ENOMEM;
 342                         goto finish;
 343                 }
 344
 345                 m->path = node;
 346                 m->devnum = devnum;
 347                 LIST_PREPEND(MountPoint, mount_point, *head, m);
 348         }
 349
 350         r = 0;
 351
 352 finish:
 353         if (e)
 354                 udev_enumerate_unref(e);
 355
 356         if (udev)
 357                 udev_unref(udev);
 358
 359         return r;
 360 }
 361
 362 static int delete_loopback(const char *device) {
 363         int fd, r;
 364
 365         if ((fd = open(device, O_RDONLY|O_CLOEXEC)) < 0)
 366                 return errno == ENOENT ? 0 : -errno;
 367
 368         r = ioctl(fd, LOOP_CLR_FD, 0);
 369         close_nointr_nofail(fd);
 370
 371         if (r >= 0)
 372                 return 1;
 373
 374         /* ENXIO: not bound, so no error */
 375         if (errno == ENXIO)
 376                 return 0;
 377
 378         return -errno;
 379 }
 380
 381 static int delete_dm(dev_t devnum) {
 382         int _cleanup_close_ fd = -1;
 383         int r;
 384         struct dm_ioctl dm = {
 385                 .version = {DM_VERSION_MAJOR,
 386                             DM_VERSION_MINOR,
 387                             DM_VERSION_PATCHLEVEL},
 388                 .data_size = sizeof(dm),
 389                 .dev = devnum,
 390         };
 391
 392         assert(major(devnum) != 0);
 393
 394         fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
 395         if (fd < 0)
 396                 return -errno;
 397
 398         r = ioctl(fd, DM_DEV_REMOVE, &dm);
 399         return r >= 0 ? 0 : -errno;
 400 }
 401
 402 static int mount_points_list_umount(MountPoint **head, bool *changed, bool log_error) {
 403         MountPoint *m, *n;
 404         int n_failed = 0;
 405
 406         assert(head);
 407
 408         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 409
 410                 /* If we are in a container, don't attempt to
 411                    read-only mount anything as that brings no real
 412                    benefits, but might confuse the host, as we remount
 413                    the superblock here, not the bind mound. */
 414                 if (detect_container(NULL) <= 0)  {
 415                         /* We always try to remount directories
 416                          * read-only first, before we go on and umount
 417                          * them.
 418                          *
 419                          * Mount points can be stacked. If a mount
 420                          * point is stacked below / or /usr, we
 421                          * cannnot umount or remount it directly,
 422                          * since there is no way to refer to the
 423                          * underlying mount. There's nothing we can do
 424                          * about it for the general case, but we can
 425                          * do something about it if it is aliased
 426                          * somehwere else via a bind mount. If we
 427                          * explicitly remount the super block of that
 428                          * alias read-only we hence should be
 429                          * relatively safe regarding keeping the fs we
 430                          * can otherwise not see dirty. */
 431                         mount(NULL, m->path, NULL, MS_REMOUNT|MS_RDONLY, NULL);
 432                 }
 433
 434                 /* Skip / and /usr since we cannot unmount that
 435                  * anyway, since we are running from it. They have
 436                  * already been remounted ro. */
 437                 if (path_equal(m->path, "/")
 438 #ifndef HAVE_SPLIT_USR
 439                     || path_equal(m->path, "/usr")
 440 #endif
 441                 )
 442                         continue;
 443
 444                 /* Trying to umount. We don't force here since we rely
 445                  * on busy NFS and FUSE file systems to return EBUSY
 446                  * until we closed everything on top of them. */
 447                 log_info("Unmounting %s.", m->path);
 448                 if (umount2(m->path, 0) == 0) {
 449                         if (changed)
 450                                 *changed = true;
 451
 452                         mount_point_free(head, m);
 453                 } else if (log_error) {
 454                         log_warning("Could not unmount %s: %m", m->path);
 455                         n_failed++;
 456                 }
 457         }
 458
 459         return n_failed;
 460 }
 461
 462 static int swap_points_list_off(MountPoint **head, bool *changed) {
 463         MountPoint *m, *n;
 464         int n_failed = 0;
 465
 466         assert(head);
 467
 468         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 469                 log_info("Deactivating swap %s.", m->path);
 470                 if (swapoff(m->path) == 0) {
 471                         if (changed)
 472                                 *changed = true;
 473
 474                         mount_point_free(head, m);
 475                 } else {
 476                         log_warning("Could not deactivate swap %s: %m", m->path);
 477                         n_failed++;
 478                 }
 479         }
 480
 481         return n_failed;
 482 }
 483
 484 static int loopback_points_list_detach(MountPoint **head, bool *changed) {
 485         MountPoint *m, *n;
 486         int n_failed = 0, k;
 487         struct stat root_st;
 488
 489         assert(head);
 490
 491         k = lstat("/", &root_st);
 492
 493         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 494                 int r;
 495                 struct stat loopback_st;
 496
 497                 if (k >= 0 &&
 498                     major(root_st.st_dev) != 0 &&
 499                     lstat(m->path, &loopback_st) >= 0 &&
 500                     root_st.st_dev == loopback_st.st_rdev) {
 501                         n_failed ++;
 502                         continue;
 503                 }
 504
 505                 log_info("Detaching loopback %s.", m->path);
 506                 r = delete_loopback(m->path);
 507                 if (r >= 0) {
 508                         if (r > 0 && changed)
 509                                 *changed = true;
 510
 511                         mount_point_free(head, m);
 512                 } else {
 513                         log_warning("Could not detach loopback %s: %m", m->path);
 514                         n_failed++;
 515                 }
 516         }
 517
 518         return n_failed;
 519 }
 520
 521 static int dm_points_list_detach(MountPoint **head, bool *changed) {
 522         MountPoint *m, *n;
 523         int n_failed = 0, k;
 524         struct stat root_st;
 525
 526         assert(head);
 527
 528         k = lstat("/", &root_st);
 529
 530         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 531                 int r;
 532
 533                 if (k >= 0 &&
 534                     major(root_st.st_dev) != 0 &&
 535                     root_st.st_dev == m->devnum) {
 536                         n_failed ++;
 537                         continue;
 538                 }
 539
 540                 log_info("Detaching DM %u:%u.", major(m->devnum), minor(m->devnum));
 541                 r = delete_dm(m->devnum);
 542                 if (r >= 0) {
 543                         if (changed)
 544                                 *changed = true;
 545
 546                         mount_point_free(head, m);
 547                 } else {
 548                         log_warning("Could not detach DM %s: %m", m->path);
 549                         n_failed++;
 550                 }
 551         }
 552
 553         return n_failed;
 554 }
 555
 556 int umount_all(bool *changed) {
 557         int r;
 558         bool umount_changed;
 559         LIST_HEAD(MountPoint, mp_list_head);
 560
 561         LIST_HEAD_INIT(MountPoint, mp_list_head);
 562         r = mount_points_list_get(&mp_list_head);
 563         if (r < 0)
 564                 goto end;
 565
 566         /* retry umount, until nothing can be umounted anymore */
 567         do {
 568                 umount_changed = false;
 569
 570                 mount_points_list_umount(&mp_list_head, &umount_changed, false);
 571                 if (umount_changed)
 572                         *changed = true;
 573
 574         } while (umount_changed);
 575
 576         /* umount one more time with logging enabled */
 577         r = mount_points_list_umount(&mp_list_head, &umount_changed, true);
 578         if (r <= 0)
 579                 goto end;
 580
 581   end:
 582         mount_points_list_free(&mp_list_head);
 583
 584         return r;
 585 }
 586
 587 int swapoff_all(bool *changed) {
 588         int r;
 589         LIST_HEAD(MountPoint, swap_list_head);
 590
 591         LIST_HEAD_INIT(MountPoint, swap_list_head);
 592
 593         r = swap_list_get(&swap_list_head);
 594         if (r < 0)
 595                 goto end;
 596
 597         r = swap_points_list_off(&swap_list_head, changed);
 598
 599   end:
 600         mount_points_list_free(&swap_list_head);
 601
 602         return r;
 603 }
 604
 605 int loopback_detach_all(bool *changed) {
 606         int r;
 607         LIST_HEAD(MountPoint, loopback_list_head);
 608
 609         LIST_HEAD_INIT(MountPoint, loopback_list_head);
 610
 611         r = loopback_list_get(&loopback_list_head);
 612         if (r < 0)
 613                 goto end;
 614
 615         r = loopback_points_list_detach(&loopback_list_head, changed);
 616
 617   end:
 618         mount_points_list_free(&loopback_list_head);
 619
 620         return r;
 621 }
 622
 623 int dm_detach_all(bool *changed) {
 624         int r;
 625         LIST_HEAD(MountPoint, dm_list_head);
 626
 627         LIST_HEAD_INIT(MountPoint, dm_list_head);
 628
 629         r = dm_list_get(&dm_list_head);
 630         if (r < 0)
 631                 goto end;
 632
 633         r = dm_points_list_detach(&dm_list_head, changed);
 634
 635   end:
 636         mount_points_list_free(&dm_list_head);
 637
 638         return r;
 639 }