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