init/do_mounts.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/module.h>
   3 #include <linux/sched.h>
   4 #include <linux/ctype.h>
   5 #include <linux/fd.h>
   6 #include <linux/tty.h>
   7 #include <linux/suspend.h>
   8 #include <linux/root_dev.h>
   9 #include <linux/security.h>
  10 #include <linux/delay.h>
  11 #include <linux/mount.h>
  12 #include <linux/device.h>
  13 #include <linux/init.h>
  14 #include <linux/fs.h>
  15 #include <linux/initrd.h>
  16 #include <linux/async.h>
  17 #include <linux/fs_struct.h>
  18 #include <linux/slab.h>
  19 #include <linux/ramfs.h>
  20 #include <linux/shmem_fs.h>
  21
  22 #include <linux/nfs_fs.h>
  23 #include <linux/nfs_fs_sb.h>
  24 #include <linux/nfs_mount.h>
  25 #include <linux/raid/detect.h>
  26 #include <uapi/linux/mount.h>
  27
  28 #include "do_mounts.h"
  29
  30 int root_mountflags = MS_RDONLY | MS_SILENT;
  31 static char * __initdata root_device_name;
  32 static char __initdata saved_root_name[64];
  33 static int root_wait;
  34
  35 dev_t ROOT_DEV;
  36
  37 static int __init load_ramdisk(char *str)
  38 {
  39         pr_warn("ignoring the deprecated load_ramdisk= option\n");
  40         return 1;
  41 }
  42 __setup("load_ramdisk=", load_ramdisk);
  43
  44 static int __init readonly(char *str)
  45 {
  46         if (*str)
  47                 return 0;
  48         root_mountflags |= MS_RDONLY;
  49         return 1;
  50 }
  51
  52 static int __init readwrite(char *str)
  53 {
  54         if (*str)
  55                 return 0;
  56         root_mountflags &= ~MS_RDONLY;
  57         return 1;
  58 }
  59
  60 __setup("ro", readonly);
  61 __setup("rw", readwrite);
  62
  63 #ifdef CONFIG_BLOCK
  64 struct uuidcmp {
  65         const char *uuid;
  66         int len;
  67 };
  68
  69 /**
  70  * match_dev_by_uuid - callback for finding a partition using its uuid
  71  * @dev:        device passed in by the caller
  72  * @data:       opaque pointer to the desired struct uuidcmp to match
  73  *
  74  * Returns 1 if the device matches, and 0 otherwise.
  75  */
  76 static int match_dev_by_uuid(struct device *dev, const void *data)
  77 {
  78         struct block_device *bdev = dev_to_bdev(dev);
  79         const struct uuidcmp *cmp = data;
  80
  81         if (!bdev->bd_meta_info ||
  82             strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
  83                 return 0;
  84         return 1;
  85 }
  86
  87 /**
  88  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
  89  * @uuid_str:   char array containing ascii UUID
  90  *
  91  * The function will return the first partition which contains a matching
  92  * UUID value in its partition_meta_info struct.  This does not search
  93  * by filesystem UUIDs.
  94  *
  95  * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
  96  * extracted and used as an offset from the partition identified by the UUID.
  97  *
  98  * Returns the matching dev_t on success or 0 on failure.
  99  */
 100 static dev_t devt_from_partuuid(const char *uuid_str)
 101 {
 102         struct uuidcmp cmp;
 103         struct device *dev = NULL;
 104         dev_t devt = 0;
 105         int offset = 0;
 106         char *slash;
 107
 108         cmp.uuid = uuid_str;
 109
 110         slash = strchr(uuid_str, '/');
 111         /* Check for optional partition number offset attributes. */
 112         if (slash) {
 113                 char c = 0;
 114
 115                 /* Explicitly fail on poor PARTUUID syntax. */
 116                 if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
 117                         goto clear_root_wait;
 118                 cmp.len = slash - uuid_str;
 119         } else {
 120                 cmp.len = strlen(uuid_str);
 121         }
 122
 123         if (!cmp.len)
 124                 goto clear_root_wait;
 125
 126         dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
 127         if (!dev)
 128                 return 0;
 129
 130         if (offset) {
 131                 /*
 132                  * Attempt to find the requested partition by adding an offset
 133                  * to the partition number found by UUID.
 134                  */
 135                 devt = part_devt(dev_to_disk(dev),
 136                                  dev_to_bdev(dev)->bd_partno + offset);
 137         } else {
 138                 devt = dev->devt;
 139         }
 140
 141         put_device(dev);
 142         return devt;
 143
 144 clear_root_wait:
 145         pr_err("VFS: PARTUUID= is invalid.\n"
 146                "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
 147         if (root_wait)
 148                 pr_err("Disabling rootwait; root= is invalid.\n");
 149         root_wait = 0;
 150         return 0;
 151 }
 152
 153 /**
 154  * match_dev_by_label - callback for finding a partition using its label
 155  * @dev:        device passed in by the caller
 156  * @data:       opaque pointer to the label to match
 157  *
 158  * Returns 1 if the device matches, and 0 otherwise.
 159  */
 160 static int match_dev_by_label(struct device *dev, const void *data)
 161 {
 162         struct block_device *bdev = dev_to_bdev(dev);
 163         const char *label = data;
 164
 165         if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
 166                 return 0;
 167         return 1;
 168 }
 169
 170 static dev_t devt_from_partlabel(const char *label)
 171 {
 172         struct device *dev;
 173         dev_t devt = 0;
 174
 175         dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
 176         if (dev) {
 177                 devt = dev->devt;
 178                 put_device(dev);
 179         }
 180
 181         return devt;
 182 }
 183
 184 static dev_t devt_from_devname(const char *name)
 185 {
 186         dev_t devt = 0;
 187         int part;
 188         char s[32];
 189         char *p;
 190
 191         if (strlen(name) > 31)
 192                 return 0;
 193         strcpy(s, name);
 194         for (p = s; *p; p++) {
 195                 if (*p == '/')
 196                         *p = '!';
 197         }
 198
 199         devt = blk_lookup_devt(s, 0);
 200         if (devt)
 201                 return devt;
 202
 203         /*
 204          * Try non-existent, but valid partition, which may only exist after
 205          * opening the device, like partitioned md devices.
 206          */
 207         while (p > s && isdigit(p[-1]))
 208                 p--;
 209         if (p == s || !*p || *p == '0')
 210                 return 0;
 211
 212         /* try disk name without <part number> */
 213         part = simple_strtoul(p, NULL, 10);
 214         *p = '\0';
 215         devt = blk_lookup_devt(s, part);
 216         if (devt)
 217                 return devt;
 218
 219         /* try disk name without p<part number> */
 220         if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
 221                 return 0;
 222         p[-1] = '\0';
 223         return blk_lookup_devt(s, part);
 224 }
 225 #endif /* CONFIG_BLOCK */
 226
 227 static dev_t devt_from_devnum(const char *name)
 228 {
 229         unsigned maj, min, offset;
 230         dev_t devt = 0;
 231         char *p, dummy;
 232
 233         if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
 234             sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
 235                 devt = MKDEV(maj, min);
 236                 if (maj != MAJOR(devt) || min != MINOR(devt))
 237                         return 0;
 238         } else {
 239                 devt = new_decode_dev(simple_strtoul(name, &p, 16));
 240                 if (*p)
 241                         return 0;
 242         }
 243
 244         return devt;
 245 }
 246
 247 /*
 248  *      Convert a name into device number.  We accept the following variants:
 249  *
 250  *      1) <hex_major><hex_minor> device number in hexadecimal represents itself
 251  *         no leading 0x, for example b302.
 252  *      2) /dev/nfs represents Root_NFS (0xff)
 253  *      3) /dev/<disk_name> represents the device number of disk
 254  *      4) /dev/<disk_name><decimal> represents the device number
 255  *         of partition - device number of disk plus the partition number
 256  *      5) /dev/<disk_name>p<decimal> - same as the above, that form is
 257  *         used when disk name of partitioned disk ends on a digit.
 258  *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 259  *         unique id of a partition if the partition table provides it.
 260  *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 261  *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 262  *         filled hex representation of the 32-bit "NT disk signature", and PP
 263  *         is a zero-filled hex representation of the 1-based partition number.
 264  *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 265  *         a partition with a known unique id.
 266  *      8) <major>:<minor> major and minor number of the device separated by
 267  *         a colon.
 268  *      9) PARTLABEL=<name> with name being the GPT partition label.
 269  *         MSDOS partitions do not support labels!
 270  *      10) /dev/cifs represents Root_CIFS (0xfe)
 271  *
 272  *      If name doesn't have fall into the categories above, we return (0,0).
 273  *      block_class is used to check if something is a disk name. If the disk
 274  *      name contains slashes, the device name has them replaced with
 275  *      bangs.
 276  */
 277 dev_t name_to_dev_t(const char *name)
 278 {
 279         if (strcmp(name, "/dev/nfs") == 0)
 280                 return Root_NFS;
 281         if (strcmp(name, "/dev/cifs") == 0)
 282                 return Root_CIFS;
 283         if (strcmp(name, "/dev/ram") == 0)
 284                 return Root_RAM0;
 285 #ifdef CONFIG_BLOCK
 286         if (strncmp(name, "PARTUUID=", 9) == 0)
 287                 return devt_from_partuuid(name + 9);
 288         if (strncmp(name, "PARTLABEL=", 10) == 0)
 289                 return devt_from_partlabel(name + 10);
 290         if (strncmp(name, "/dev/", 5) == 0)
 291                 return devt_from_devname(name + 5);
 292 #endif
 293         return devt_from_devnum(name);
 294 }
 295 EXPORT_SYMBOL_GPL(name_to_dev_t);
 296
 297 static int __init root_dev_setup(char *line)
 298 {
 299         strlcpy(saved_root_name, line, sizeof(saved_root_name));
 300         return 1;
 301 }
 302
 303 __setup("root=", root_dev_setup);
 304
 305 static int __init rootwait_setup(char *str)
 306 {
 307         if (*str)
 308                 return 0;
 309         root_wait = 1;
 310         return 1;
 311 }
 312
 313 __setup("rootwait", rootwait_setup);
 314
 315 static char * __initdata root_mount_data;
 316 static int __init root_data_setup(char *str)
 317 {
 318         root_mount_data = str;
 319         return 1;
 320 }
 321
 322 static char * __initdata root_fs_names;
 323 static int __init fs_names_setup(char *str)
 324 {
 325         root_fs_names = str;
 326         return 1;
 327 }
 328
 329 static unsigned int __initdata root_delay;
 330 static int __init root_delay_setup(char *str)
 331 {
 332         root_delay = simple_strtoul(str, NULL, 0);
 333         return 1;
 334 }
 335
 336 __setup("rootflags=", root_data_setup);
 337 __setup("rootfstype=", fs_names_setup);
 338 __setup("rootdelay=", root_delay_setup);
 339
 340 /* This can return zero length strings. Caller should check */
 341 static int __init split_fs_names(char *page, size_t size, char *names)
 342 {
 343         int count = 1;
 344         char *p = page;
 345
 346         strlcpy(p, root_fs_names, size);
 347         while (*p++) {
 348                 if (p[-1] == ',') {
 349                         p[-1] = '\0';
 350                         count++;
 351                 }
 352         }
 353
 354         return count;
 355 }
 356
 357 static int __init do_mount_root(const char *name, const char *fs,
 358                                  const int flags, const void *data)
 359 {
 360         struct super_block *s;
 361         struct page *p = NULL;
 362         char *data_page = NULL;
 363         int ret;
 364
 365         if (data) {
 366                 /* init_mount() requires a full page as fifth argument */
 367                 p = alloc_page(GFP_KERNEL);
 368                 if (!p)
 369                         return -ENOMEM;
 370                 data_page = page_address(p);
 371                 /* zero-pad. init_mount() will make sure it's terminated */
 372                 strncpy(data_page, data, PAGE_SIZE);
 373         }
 374
 375         ret = init_mount(name, "/root", fs, flags, data_page);
 376         if (ret)
 377                 goto out;
 378
 379         init_chdir("/root");
 380         s = current->fs->pwd.dentry->d_sb;
 381         ROOT_DEV = s->s_dev;
 382         printk(KERN_INFO
 383                "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
 384                s->s_type->name,
 385                sb_rdonly(s) ? " readonly" : "",
 386                MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 387
 388 out:
 389         if (p)
 390                 put_page(p);
 391         return ret;
 392 }
 393
 394 void __init mount_block_root(char *name, int flags)
 395 {
 396         struct page *page = alloc_page(GFP_KERNEL);
 397         char *fs_names = page_address(page);
 398         char *p;
 399         char b[BDEVNAME_SIZE];
 400         int num_fs, i;
 401
 402         scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
 403                   MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 404         if (root_fs_names)
 405                 num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
 406         else
 407                 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
 408 retry:
 409         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
 410                 int err;
 411
 412                 if (!*p)
 413                         continue;
 414                 err = do_mount_root(name, p, flags, root_mount_data);
 415                 switch (err) {
 416                         case 0:
 417                                 goto out;
 418                         case -EACCES:
 419                         case -EINVAL:
 420                                 continue;
 421                 }
 422                 /*
 423                  * Allow the user to distinguish between failed sys_open
 424                  * and bad superblock on root device.
 425                  * and give them a list of the available devices
 426                  */
 427                 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
 428                                 root_device_name, b, err);
 429                 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 430
 431                 printk_all_partitions();
 432                 panic("VFS: Unable to mount root fs on %s", b);
 433         }
 434         if (!(flags & SB_RDONLY)) {
 435                 flags |= SB_RDONLY;
 436                 goto retry;
 437         }
 438
 439         printk("List of all partitions:\n");
 440         printk_all_partitions();
 441         printk("No filesystem could mount root, tried: ");
 442         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
 443                 printk(" %s", p);
 444         printk("\n");
 445         panic("VFS: Unable to mount root fs on %s", b);
 446 out:
 447         put_page(page);
 448 }
 449
 450 #ifdef CONFIG_ROOT_NFS
 451
 452 #define NFSROOT_TIMEOUT_MIN     5
 453 #define NFSROOT_TIMEOUT_MAX     30
 454 #define NFSROOT_RETRY_MAX       5
 455
 456 static int __init mount_nfs_root(void)
 457 {
 458         char *root_dev, *root_data;
 459         unsigned int timeout;
 460         int try, err;
 461
 462         err = nfs_root_data(&root_dev, &root_data);
 463         if (err != 0)
 464                 return 0;
 465
 466         /*
 467          * The server or network may not be ready, so try several
 468          * times.  Stop after a few tries in case the client wants
 469          * to fall back to other boot methods.
 470          */
 471         timeout = NFSROOT_TIMEOUT_MIN;
 472         for (try = 1; ; try++) {
 473                 err = do_mount_root(root_dev, "nfs",
 474                                         root_mountflags, root_data);
 475                 if (err == 0)
 476                         return 1;
 477                 if (try > NFSROOT_RETRY_MAX)
 478                         break;
 479
 480                 /* Wait, in case the server refused us immediately */
 481                 ssleep(timeout);
 482                 timeout <<= 1;
 483                 if (timeout > NFSROOT_TIMEOUT_MAX)
 484                         timeout = NFSROOT_TIMEOUT_MAX;
 485         }
 486         return 0;
 487 }
 488 #endif
 489
 490 #ifdef CONFIG_CIFS_ROOT
 491
 492 extern int cifs_root_data(char **dev, char **opts);
 493
 494 #define CIFSROOT_TIMEOUT_MIN    5
 495 #define CIFSROOT_TIMEOUT_MAX    30
 496 #define CIFSROOT_RETRY_MAX      5
 497
 498 static int __init mount_cifs_root(void)
 499 {
 500         char *root_dev, *root_data;
 501         unsigned int timeout;
 502         int try, err;
 503
 504         err = cifs_root_data(&root_dev, &root_data);
 505         if (err != 0)
 506                 return 0;
 507
 508         timeout = CIFSROOT_TIMEOUT_MIN;
 509         for (try = 1; ; try++) {
 510                 err = do_mount_root(root_dev, "cifs", root_mountflags,
 511                                     root_data);
 512                 if (err == 0)
 513                         return 1;
 514                 if (try > CIFSROOT_RETRY_MAX)
 515                         break;
 516
 517                 ssleep(timeout);
 518                 timeout <<= 1;
 519                 if (timeout > CIFSROOT_TIMEOUT_MAX)
 520                         timeout = CIFSROOT_TIMEOUT_MAX;
 521         }
 522         return 0;
 523 }
 524 #endif
 525
 526 static bool __init fs_is_nodev(char *fstype)
 527 {
 528         struct file_system_type *fs = get_fs_type(fstype);
 529         bool ret = false;
 530
 531         if (fs) {
 532                 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
 533                 put_filesystem(fs);
 534         }
 535
 536         return ret;
 537 }
 538
 539 static int __init mount_nodev_root(void)
 540 {
 541         char *fs_names, *fstype;
 542         int err = -EINVAL;
 543         int num_fs, i;
 544
 545         fs_names = (void *)__get_free_page(GFP_KERNEL);
 546         if (!fs_names)
 547                 return -EINVAL;
 548         num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
 549
 550         for (i = 0, fstype = fs_names; i < num_fs;
 551              i++, fstype += strlen(fstype) + 1) {
 552                 if (!*fstype)
 553                         continue;
 554                 if (!fs_is_nodev(fstype))
 555                         continue;
 556                 err = do_mount_root(root_device_name, fstype, root_mountflags,
 557                                     root_mount_data);
 558                 if (!err)
 559                         break;
 560         }
 561
 562         free_page((unsigned long)fs_names);
 563         return err;
 564 }
 565
 566 void __init mount_root(void)
 567 {
 568 #ifdef CONFIG_ROOT_NFS
 569         if (ROOT_DEV == Root_NFS) {
 570                 if (!mount_nfs_root())
 571                         printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
 572                 return;
 573         }
 574 #endif
 575 #ifdef CONFIG_CIFS_ROOT
 576         if (ROOT_DEV == Root_CIFS) {
 577                 if (!mount_cifs_root())
 578                         printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
 579                 return;
 580         }
 581 #endif
 582         if (ROOT_DEV == 0 && root_device_name && root_fs_names) {
 583                 if (mount_nodev_root() == 0)
 584                         return;
 585         }
 586 #ifdef CONFIG_BLOCK
 587         {
 588                 int err = create_dev("/dev/root", ROOT_DEV);
 589
 590                 if (err < 0)
 591                         pr_emerg("Failed to create /dev/root: %d\n", err);
 592                 mount_block_root("/dev/root", root_mountflags);
 593         }
 594 #endif
 595 }
 596
 597 /*
 598  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 599  */
 600 void __init prepare_namespace(void)
 601 {
 602         if (root_delay) {
 603                 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
 604                        root_delay);
 605                 ssleep(root_delay);
 606         }
 607
 608         /*
 609          * wait for the known devices to complete their probing
 610          *
 611          * Note: this is a potential source of long boot delays.
 612          * For example, it is not atypical to wait 5 seconds here
 613          * for the touchpad of a laptop to initialize.
 614          */
 615         wait_for_device_probe();
 616
 617         md_run_setup();
 618
 619         if (saved_root_name[0]) {
 620                 root_device_name = saved_root_name;
 621                 if (!strncmp(root_device_name, "mtd", 3) ||
 622                     !strncmp(root_device_name, "ubi", 3)) {
 623                         mount_block_root(root_device_name, root_mountflags);
 624                         goto out;
 625                 }
 626                 ROOT_DEV = name_to_dev_t(root_device_name);
 627                 if (strncmp(root_device_name, "/dev/", 5) == 0)
 628                         root_device_name += 5;
 629         }
 630
 631         if (initrd_load())
 632                 goto out;
 633
 634         /* wait for any asynchronous scanning to complete */
 635         if ((ROOT_DEV == 0) && root_wait) {
 636                 printk(KERN_INFO "Waiting for root device %s...\n",
 637                         saved_root_name);
 638                 while (driver_probe_done() != 0 ||
 639                         (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
 640                         msleep(5);
 641                 async_synchronize_full();
 642         }
 643
 644         mount_root();
 645 out:
 646         devtmpfs_mount();
 647         init_mount(".", "/", NULL, MS_MOVE, NULL);
 648         init_chroot(".");
 649 }
 650
 651 static bool is_tmpfs;
 652 static int rootfs_init_fs_context(struct fs_context *fc)
 653 {
 654         if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
 655                 return shmem_init_fs_context(fc);
 656
 657         return ramfs_init_fs_context(fc);
 658 }
 659
 660 struct file_system_type rootfs_fs_type = {
 661         .name           = "rootfs",
 662         .init_fs_context = rootfs_init_fs_context,
 663         .kill_sb        = kill_litter_super,
 664 };
 665
 666 void __init init_rootfs(void)
 667 {
 668         if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
 669                 (!root_fs_names || strstr(root_fs_names, "tmpfs")))
 670                 is_tmpfs = true;
 671 }