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