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 #include <linux/ktime.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 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 static int __init root_dev_setup(char *line)
  64 {
  65         strscpy(saved_root_name, line, sizeof(saved_root_name));
  66         return 1;
  67 }
  68
  69 __setup("root=", root_dev_setup);
  70
  71 static int __init rootwait_setup(char *str)
  72 {
  73         if (*str)
  74                 return 0;
  75         root_wait = -1;
  76         return 1;
  77 }
  78
  79 __setup("rootwait", rootwait_setup);
  80
  81 static int __init rootwait_timeout_setup(char *str)
  82 {
  83         int sec;
  84
  85         if (kstrtoint(str, 0, &sec) || sec < 0) {
  86                 pr_warn("ignoring invalid rootwait value\n");
  87                 goto ignore;
  88         }
  89
  90         if (check_mul_overflow(sec, MSEC_PER_SEC, &root_wait)) {
  91                 pr_warn("ignoring excessive rootwait value\n");
  92                 goto ignore;
  93         }
  94
  95         return 1;
  96
  97 ignore:
  98         /* Fallback to indefinite wait */
  99         root_wait = -1;
 100
 101         return 1;
 102 }
 103
 104 __setup("rootwait=", rootwait_timeout_setup);
 105
 106 static char * __initdata root_mount_data;
 107 static int __init root_data_setup(char *str)
 108 {
 109         root_mount_data = str;
 110         return 1;
 111 }
 112
 113 static char * __initdata root_fs_names;
 114 static int __init fs_names_setup(char *str)
 115 {
 116         root_fs_names = str;
 117         return 1;
 118 }
 119
 120 static unsigned int __initdata root_delay;
 121 static int __init root_delay_setup(char *str)
 122 {
 123         root_delay = simple_strtoul(str, NULL, 0);
 124         return 1;
 125 }
 126
 127 __setup("rootflags=", root_data_setup);
 128 __setup("rootfstype=", fs_names_setup);
 129 __setup("rootdelay=", root_delay_setup);
 130
 131 /* This can return zero length strings. Caller should check */
 132 static int __init split_fs_names(char *page, size_t size)
 133 {
 134         int count = 1;
 135         char *p = page;
 136
 137         strscpy(p, root_fs_names, size);
 138         while (*p++) {
 139                 if (p[-1] == ',') {
 140                         p[-1] = '\0';
 141                         count++;
 142                 }
 143         }
 144
 145         return count;
 146 }
 147
 148 static int __init do_mount_root(const char *name, const char *fs,
 149                                  const int flags, const void *data)
 150 {
 151         struct super_block *s;
 152         struct page *p = NULL;
 153         char *data_page = NULL;
 154         int ret;
 155
 156         if (data) {
 157                 /* init_mount() requires a full page as fifth argument */
 158                 p = alloc_page(GFP_KERNEL);
 159                 if (!p)
 160                         return -ENOMEM;
 161                 data_page = page_address(p);
 162                 strscpy_pad(data_page, data, PAGE_SIZE);
 163         }
 164
 165         ret = init_mount(name, "/root", fs, flags, data_page);
 166         if (ret)
 167                 goto out;
 168
 169         init_chdir("/root");
 170         s = current->fs->pwd.dentry->d_sb;
 171         ROOT_DEV = s->s_dev;
 172         printk(KERN_INFO
 173                "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
 174                s->s_type->name,
 175                sb_rdonly(s) ? " readonly" : "",
 176                MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 177
 178 out:
 179         if (p)
 180                 put_page(p);
 181         return ret;
 182 }
 183
 184 void __init mount_root_generic(char *name, char *pretty_name, int flags)
 185 {
 186         struct page *page = alloc_page(GFP_KERNEL);
 187         char *fs_names = page_address(page);
 188         char *p;
 189         char b[BDEVNAME_SIZE];
 190         int num_fs, i;
 191
 192         scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
 193                   MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 194         if (root_fs_names)
 195                 num_fs = split_fs_names(fs_names, PAGE_SIZE);
 196         else
 197                 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
 198 retry:
 199         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
 200                 int err;
 201
 202                 if (!*p)
 203                         continue;
 204                 err = do_mount_root(name, p, flags, root_mount_data);
 205                 switch (err) {
 206                         case 0:
 207                                 goto out;
 208                         case -EACCES:
 209                         case -EINVAL:
 210 #ifdef CONFIG_BLOCK
 211                                 init_flush_fput();
 212 #endif
 213                                 continue;
 214                 }
 215                 /*
 216                  * Allow the user to distinguish between failed sys_open
 217                  * and bad superblock on root device.
 218                  * and give them a list of the available devices
 219                  */
 220                 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
 221                                 pretty_name, b, err);
 222                 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 223                 printk_all_partitions();
 224
 225                 if (root_fs_names)
 226                         num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
 227                 if (!num_fs)
 228                         pr_err("Can't find any bdev filesystem to be used for mount!\n");
 229                 else {
 230                         pr_err("List of all bdev filesystems:\n");
 231                         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
 232                                 pr_err(" %s", p);
 233                         pr_err("\n");
 234                 }
 235
 236                 panic("VFS: Unable to mount root fs on %s", b);
 237         }
 238         if (!(flags & SB_RDONLY)) {
 239                 flags |= SB_RDONLY;
 240                 goto retry;
 241         }
 242
 243         printk("List of all partitions:\n");
 244         printk_all_partitions();
 245         printk("No filesystem could mount root, tried: ");
 246         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
 247                 printk(" %s", p);
 248         printk("\n");
 249         panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
 250 out:
 251         put_page(page);
 252 }
 253
 254 #ifdef CONFIG_ROOT_NFS
 255
 256 #define NFSROOT_TIMEOUT_MIN     5
 257 #define NFSROOT_TIMEOUT_MAX     30
 258 #define NFSROOT_RETRY_MAX       5
 259
 260 static void __init mount_nfs_root(void)
 261 {
 262         char *root_dev, *root_data;
 263         unsigned int timeout;
 264         int try;
 265
 266         if (nfs_root_data(&root_dev, &root_data))
 267                 goto fail;
 268
 269         /*
 270          * The server or network may not be ready, so try several
 271          * times.  Stop after a few tries in case the client wants
 272          * to fall back to other boot methods.
 273          */
 274         timeout = NFSROOT_TIMEOUT_MIN;
 275         for (try = 1; ; try++) {
 276                 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
 277                         return;
 278                 if (try > NFSROOT_RETRY_MAX)
 279                         break;
 280
 281                 /* Wait, in case the server refused us immediately */
 282                 ssleep(timeout);
 283                 timeout <<= 1;
 284                 if (timeout > NFSROOT_TIMEOUT_MAX)
 285                         timeout = NFSROOT_TIMEOUT_MAX;
 286         }
 287 fail:
 288         pr_err("VFS: Unable to mount root fs via NFS.\n");
 289 }
 290 #else
 291 static inline void mount_nfs_root(void)
 292 {
 293 }
 294 #endif /* CONFIG_ROOT_NFS */
 295
 296 #ifdef CONFIG_CIFS_ROOT
 297
 298 #define CIFSROOT_TIMEOUT_MIN    5
 299 #define CIFSROOT_TIMEOUT_MAX    30
 300 #define CIFSROOT_RETRY_MAX      5
 301
 302 static void __init mount_cifs_root(void)
 303 {
 304         char *root_dev, *root_data;
 305         unsigned int timeout;
 306         int try;
 307
 308         if (cifs_root_data(&root_dev, &root_data))
 309                 goto fail;
 310
 311         timeout = CIFSROOT_TIMEOUT_MIN;
 312         for (try = 1; ; try++) {
 313                 if (!do_mount_root(root_dev, "cifs", root_mountflags,
 314                                    root_data))
 315                         return;
 316                 if (try > CIFSROOT_RETRY_MAX)
 317                         break;
 318
 319                 ssleep(timeout);
 320                 timeout <<= 1;
 321                 if (timeout > CIFSROOT_TIMEOUT_MAX)
 322                         timeout = CIFSROOT_TIMEOUT_MAX;
 323         }
 324 fail:
 325         pr_err("VFS: Unable to mount root fs via SMB.\n");
 326 }
 327 #else
 328 static inline void mount_cifs_root(void)
 329 {
 330 }
 331 #endif /* CONFIG_CIFS_ROOT */
 332
 333 static bool __init fs_is_nodev(char *fstype)
 334 {
 335         struct file_system_type *fs = get_fs_type(fstype);
 336         bool ret = false;
 337
 338         if (fs) {
 339                 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
 340                 put_filesystem(fs);
 341         }
 342
 343         return ret;
 344 }
 345
 346 static int __init mount_nodev_root(char *root_device_name)
 347 {
 348         char *fs_names, *fstype;
 349         int err = -EINVAL;
 350         int num_fs, i;
 351
 352         fs_names = (void *)__get_free_page(GFP_KERNEL);
 353         if (!fs_names)
 354                 return -EINVAL;
 355         num_fs = split_fs_names(fs_names, PAGE_SIZE);
 356
 357         for (i = 0, fstype = fs_names; i < num_fs;
 358              i++, fstype += strlen(fstype) + 1) {
 359                 if (!*fstype)
 360                         continue;
 361                 if (!fs_is_nodev(fstype))
 362                         continue;
 363                 err = do_mount_root(root_device_name, fstype, root_mountflags,
 364                                     root_mount_data);
 365                 if (!err)
 366                         break;
 367         }
 368
 369         free_page((unsigned long)fs_names);
 370         return err;
 371 }
 372
 373 #ifdef CONFIG_BLOCK
 374 static void __init mount_block_root(char *root_device_name)
 375 {
 376         int err = create_dev("/dev/root", ROOT_DEV);
 377
 378         if (err < 0)
 379                 pr_emerg("Failed to create /dev/root: %d\n", err);
 380         mount_root_generic("/dev/root", root_device_name, root_mountflags);
 381 }
 382 #else
 383 static inline void mount_block_root(char *root_device_name)
 384 {
 385 }
 386 #endif /* CONFIG_BLOCK */
 387
 388 void __init mount_root(char *root_device_name)
 389 {
 390         switch (ROOT_DEV) {
 391         case Root_NFS:
 392                 mount_nfs_root();
 393                 break;
 394         case Root_CIFS:
 395                 mount_cifs_root();
 396                 break;
 397         case Root_Generic:
 398                 mount_root_generic(root_device_name, root_device_name,
 399                                    root_mountflags);
 400                 break;
 401         case 0:
 402                 if (root_device_name && root_fs_names &&
 403                     mount_nodev_root(root_device_name) == 0)
 404                         break;
 405                 fallthrough;
 406         default:
 407                 mount_block_root(root_device_name);
 408                 break;
 409         }
 410 }
 411
 412 /* wait for any asynchronous scanning to complete */
 413 static void __init wait_for_root(char *root_device_name)
 414 {
 415         ktime_t end;
 416
 417         if (ROOT_DEV != 0)
 418                 return;
 419
 420         pr_info("Waiting for root device %s...\n", root_device_name);
 421
 422         end = ktime_add_ms(ktime_get_raw(), root_wait);
 423
 424         while (!driver_probe_done() ||
 425                early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
 426                 msleep(5);
 427                 if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
 428                         break;
 429         }
 430
 431         async_synchronize_full();
 432
 433 }
 434
 435 static dev_t __init parse_root_device(char *root_device_name)
 436 {
 437         int error;
 438         dev_t dev;
 439
 440         if (!strncmp(root_device_name, "mtd", 3) ||
 441             !strncmp(root_device_name, "ubi", 3))
 442                 return Root_Generic;
 443         if (strcmp(root_device_name, "/dev/nfs") == 0)
 444                 return Root_NFS;
 445         if (strcmp(root_device_name, "/dev/cifs") == 0)
 446                 return Root_CIFS;
 447         if (strcmp(root_device_name, "/dev/ram") == 0)
 448                 return Root_RAM0;
 449
 450         error = early_lookup_bdev(root_device_name, &dev);
 451         if (error) {
 452                 if (error == -EINVAL && root_wait) {
 453                         pr_err("Disabling rootwait; root= is invalid.\n");
 454                         root_wait = 0;
 455                 }
 456                 return 0;
 457         }
 458         return dev;
 459 }
 460
 461 /*
 462  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 463  */
 464 void __init prepare_namespace(void)
 465 {
 466         if (root_delay) {
 467                 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
 468                        root_delay);
 469                 ssleep(root_delay);
 470         }
 471
 472         /*
 473          * wait for the known devices to complete their probing
 474          *
 475          * Note: this is a potential source of long boot delays.
 476          * For example, it is not atypical to wait 5 seconds here
 477          * for the touchpad of a laptop to initialize.
 478          */
 479         wait_for_device_probe();
 480
 481         md_run_setup();
 482
 483         if (saved_root_name[0])
 484                 ROOT_DEV = parse_root_device(saved_root_name);
 485
 486         if (initrd_load(saved_root_name))
 487                 goto out;
 488
 489         if (root_wait)
 490                 wait_for_root(saved_root_name);
 491         mount_root(saved_root_name);
 492 out:
 493         devtmpfs_mount();
 494         init_mount(".", "/", NULL, MS_MOVE, NULL);
 495         init_chroot(".");
 496 }
 497
 498 static bool is_tmpfs;
 499 static int rootfs_init_fs_context(struct fs_context *fc)
 500 {
 501         if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
 502                 return shmem_init_fs_context(fc);
 503
 504         return ramfs_init_fs_context(fc);
 505 }
 506
 507 struct file_system_type rootfs_fs_type = {
 508         .name           = "rootfs",
 509         .init_fs_context = rootfs_init_fs_context,
 510         .kill_sb        = kill_litter_super,
 511 };
 512
 513 void __init init_rootfs(void)
 514 {
 515         if (IS_ENABLED(CONFIG_TMPFS)) {
 516                 if (!saved_root_name[0] && !root_fs_names)
 517                         is_tmpfs = true;
 518                 else if (root_fs_names && !!strstr(root_fs_names, "tmpfs"))
 519                         is_tmpfs = true;
 520         }
 521 }