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                 /* zero-pad. init_mount() will make sure it's terminated */
 163                 strncpy(data_page, data, PAGE_SIZE);
 164         }
 165
 166         ret = init_mount(name, "/root", fs, flags, data_page);
 167         if (ret)
 168                 goto out;
 169
 170         init_chdir("/root");
 171         s = current->fs->pwd.dentry->d_sb;
 172         ROOT_DEV = s->s_dev;
 173         printk(KERN_INFO
 174                "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
 175                s->s_type->name,
 176                sb_rdonly(s) ? " readonly" : "",
 177                MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 178
 179 out:
 180         if (p)
 181                 put_page(p);
 182         return ret;
 183 }
 184
 185 void __init mount_root_generic(char *name, char *pretty_name, int flags)
 186 {
 187         struct page *page = alloc_page(GFP_KERNEL);
 188         char *fs_names = page_address(page);
 189         char *p;
 190         char b[BDEVNAME_SIZE];
 191         int num_fs, i;
 192
 193         scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
 194                   MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 195         if (root_fs_names)
 196                 num_fs = split_fs_names(fs_names, PAGE_SIZE);
 197         else
 198                 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
 199 retry:
 200         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
 201                 int err;
 202
 203                 if (!*p)
 204                         continue;
 205                 err = do_mount_root(name, p, flags, root_mount_data);
 206                 switch (err) {
 207                         case 0:
 208                                 goto out;
 209                         case -EACCES:
 210                         case -EINVAL:
 211 #ifdef CONFIG_BLOCK
 212                                 init_flush_fput();
 213 #endif
 214                                 continue;
 215                 }
 216                 /*
 217                  * Allow the user to distinguish between failed sys_open
 218                  * and bad superblock on root device.
 219                  * and give them a list of the available devices
 220                  */
 221                 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
 222                                 pretty_name, b, err);
 223                 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 224                 printk_all_partitions();
 225
 226                 if (root_fs_names)
 227                         num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
 228                 if (!num_fs)
 229                         pr_err("Can't find any bdev filesystem to be used for mount!\n");
 230                 else {
 231                         pr_err("List of all bdev filesystems:\n");
 232                         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
 233                                 pr_err(" %s", p);
 234                         pr_err("\n");
 235                 }
 236
 237                 panic("VFS: Unable to mount root fs on %s", b);
 238         }
 239         if (!(flags & SB_RDONLY)) {
 240                 flags |= SB_RDONLY;
 241                 goto retry;
 242         }
 243
 244         printk("List of all partitions:\n");
 245         printk_all_partitions();
 246         printk("No filesystem could mount root, tried: ");
 247         for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
 248                 printk(" %s", p);
 249         printk("\n");
 250         panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
 251 out:
 252         put_page(page);
 253 }
 254
 255 #ifdef CONFIG_ROOT_NFS
 256
 257 #define NFSROOT_TIMEOUT_MIN     5
 258 #define NFSROOT_TIMEOUT_MAX     30
 259 #define NFSROOT_RETRY_MAX       5
 260
 261 static void __init mount_nfs_root(void)
 262 {
 263         char *root_dev, *root_data;
 264         unsigned int timeout;
 265         int try;
 266
 267         if (nfs_root_data(&root_dev, &root_data))
 268                 goto fail;
 269
 270         /*
 271          * The server or network may not be ready, so try several
 272          * times.  Stop after a few tries in case the client wants
 273          * to fall back to other boot methods.
 274          */
 275         timeout = NFSROOT_TIMEOUT_MIN;
 276         for (try = 1; ; try++) {
 277                 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
 278                         return;
 279                 if (try > NFSROOT_RETRY_MAX)
 280                         break;
 281
 282                 /* Wait, in case the server refused us immediately */
 283                 ssleep(timeout);
 284                 timeout <<= 1;
 285                 if (timeout > NFSROOT_TIMEOUT_MAX)
 286                         timeout = NFSROOT_TIMEOUT_MAX;
 287         }
 288 fail:
 289         pr_err("VFS: Unable to mount root fs via NFS.\n");
 290 }
 291 #else
 292 static inline void mount_nfs_root(void)
 293 {
 294 }
 295 #endif /* CONFIG_ROOT_NFS */
 296
 297 #ifdef CONFIG_CIFS_ROOT
 298
 299 #define CIFSROOT_TIMEOUT_MIN    5
 300 #define CIFSROOT_TIMEOUT_MAX    30
 301 #define CIFSROOT_RETRY_MAX      5
 302
 303 static void __init mount_cifs_root(void)
 304 {
 305         char *root_dev, *root_data;
 306         unsigned int timeout;
 307         int try;
 308
 309         if (cifs_root_data(&root_dev, &root_data))
 310                 goto fail;
 311
 312         timeout = CIFSROOT_TIMEOUT_MIN;
 313         for (try = 1; ; try++) {
 314                 if (!do_mount_root(root_dev, "cifs", root_mountflags,
 315                                    root_data))
 316                         return;
 317                 if (try > CIFSROOT_RETRY_MAX)
 318                         break;
 319
 320                 ssleep(timeout);
 321                 timeout <<= 1;
 322                 if (timeout > CIFSROOT_TIMEOUT_MAX)
 323                         timeout = CIFSROOT_TIMEOUT_MAX;
 324         }
 325 fail:
 326         pr_err("VFS: Unable to mount root fs via SMB.\n");
 327 }
 328 #else
 329 static inline void mount_cifs_root(void)
 330 {
 331 }
 332 #endif /* CONFIG_CIFS_ROOT */
 333
 334 static bool __init fs_is_nodev(char *fstype)
 335 {
 336         struct file_system_type *fs = get_fs_type(fstype);
 337         bool ret = false;
 338
 339         if (fs) {
 340                 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
 341                 put_filesystem(fs);
 342         }
 343
 344         return ret;
 345 }
 346
 347 static int __init mount_nodev_root(char *root_device_name)
 348 {
 349         char *fs_names, *fstype;
 350         int err = -EINVAL;
 351         int num_fs, i;
 352
 353         fs_names = (void *)__get_free_page(GFP_KERNEL);
 354         if (!fs_names)
 355                 return -EINVAL;
 356         num_fs = split_fs_names(fs_names, PAGE_SIZE);
 357
 358         for (i = 0, fstype = fs_names; i < num_fs;
 359              i++, fstype += strlen(fstype) + 1) {
 360                 if (!*fstype)
 361                         continue;
 362                 if (!fs_is_nodev(fstype))
 363                         continue;
 364                 err = do_mount_root(root_device_name, fstype, root_mountflags,
 365                                     root_mount_data);
 366                 if (!err)
 367                         break;
 368         }
 369
 370         free_page((unsigned long)fs_names);
 371         return err;
 372 }
 373
 374 #ifdef CONFIG_BLOCK
 375 static void __init mount_block_root(char *root_device_name)
 376 {
 377         int err = create_dev("/dev/root", ROOT_DEV);
 378
 379         if (err < 0)
 380                 pr_emerg("Failed to create /dev/root: %d\n", err);
 381         mount_root_generic("/dev/root", root_device_name, root_mountflags);
 382 }
 383 #else
 384 static inline void mount_block_root(char *root_device_name)
 385 {
 386 }
 387 #endif /* CONFIG_BLOCK */
 388
 389 void __init mount_root(char *root_device_name)
 390 {
 391         switch (ROOT_DEV) {
 392         case Root_NFS:
 393                 mount_nfs_root();
 394                 break;
 395         case Root_CIFS:
 396                 mount_cifs_root();
 397                 break;
 398         case Root_Generic:
 399                 mount_root_generic(root_device_name, root_device_name,
 400                                    root_mountflags);
 401                 break;
 402         case 0:
 403                 if (root_device_name && root_fs_names &&
 404                     mount_nodev_root(root_device_name) == 0)
 405                         break;
 406                 fallthrough;
 407         default:
 408                 mount_block_root(root_device_name);
 409                 break;
 410         }
 411 }
 412
 413 /* wait for any asynchronous scanning to complete */
 414 static void __init wait_for_root(char *root_device_name)
 415 {
 416         ktime_t end;
 417
 418         if (ROOT_DEV != 0)
 419                 return;
 420
 421         pr_info("Waiting for root device %s...\n", root_device_name);
 422
 423         end = ktime_add_ms(ktime_get_raw(), root_wait);
 424
 425         while (!driver_probe_done() ||
 426                early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
 427                 msleep(5);
 428                 if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
 429                         break;
 430         }
 431
 432         async_synchronize_full();
 433
 434 }
 435
 436 static dev_t __init parse_root_device(char *root_device_name)
 437 {
 438         int error;
 439         dev_t dev;
 440
 441         if (!strncmp(root_device_name, "mtd", 3) ||
 442             !strncmp(root_device_name, "ubi", 3))
 443                 return Root_Generic;
 444         if (strcmp(root_device_name, "/dev/nfs") == 0)
 445                 return Root_NFS;
 446         if (strcmp(root_device_name, "/dev/cifs") == 0)
 447                 return Root_CIFS;
 448         if (strcmp(root_device_name, "/dev/ram") == 0)
 449                 return Root_RAM0;
 450
 451         error = early_lookup_bdev(root_device_name, &dev);
 452         if (error) {
 453                 if (error == -EINVAL && root_wait) {
 454                         pr_err("Disabling rootwait; root= is invalid.\n");
 455                         root_wait = 0;
 456                 }
 457                 return 0;
 458         }
 459         return dev;
 460 }
 461
 462 /*
 463  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 464  */
 465 void __init prepare_namespace(void)
 466 {
 467         if (root_delay) {
 468                 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
 469                        root_delay);
 470                 ssleep(root_delay);
 471         }
 472
 473         /*
 474          * wait for the known devices to complete their probing
 475          *
 476          * Note: this is a potential source of long boot delays.
 477          * For example, it is not atypical to wait 5 seconds here
 478          * for the touchpad of a laptop to initialize.
 479          */
 480         wait_for_device_probe();
 481
 482         md_run_setup();
 483
 484         if (saved_root_name[0])
 485                 ROOT_DEV = parse_root_device(saved_root_name);
 486
 487         if (initrd_load(saved_root_name))
 488                 goto out;
 489
 490         if (root_wait)
 491                 wait_for_root(saved_root_name);
 492         mount_root(saved_root_name);
 493 out:
 494         devtmpfs_mount();
 495         init_mount(".", "/", NULL, MS_MOVE, NULL);
 496         init_chroot(".");
 497 }
 498
 499 static bool is_tmpfs;
 500 static int rootfs_init_fs_context(struct fs_context *fc)
 501 {
 502         if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
 503                 return shmem_init_fs_context(fc);
 504
 505         return ramfs_init_fs_context(fc);
 506 }
 507
 508 struct file_system_type rootfs_fs_type = {
 509         .name           = "rootfs",
 510         .init_fs_context = rootfs_init_fs_context,
 511         .kill_sb        = kill_litter_super,
 512 };
 513
 514 void __init init_rootfs(void)
 515 {
 516         if (IS_ENABLED(CONFIG_TMPFS)) {
 517                 if (!saved_root_name[0] && !root_fs_names)
 518                         is_tmpfs = true;
 519                 else if (root_fs_names && !!strstr(root_fs_names, "tmpfs"))
 520                         is_tmpfs = true;
 521         }
 522 }