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
31int root_mountflags = MS_RDONLY | MS_SILENT;
32static char __initdata saved_root_name[64];
33static int root_wait;
34
35dev_t ROOT_DEV;
36
37static 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
44static int __init readonly(char *str)
45{
46 if (*str)
47 return 0;
48 root_mountflags |= MS_RDONLY;
49 return 1;
50}
51
52static 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
63static 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
71static 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
81static int __init rootwait_timeout_setup(char *str)
82{
83 int sec;
84
85 if (kstrtoint(s: str, base: 0, res: &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
97ignore:
98 /* Fallback to indefinite wait */
99 root_wait = -1;
100
101 return 1;
102}
103
104__setup("rootwait=", rootwait_timeout_setup);
105
106static char * __initdata root_mount_data;
107static int __init root_data_setup(char *str)
108{
109 root_mount_data = str;
110 return 1;
111}
112
113static char * __initdata root_fs_names;
114static int __init fs_names_setup(char *str)
115{
116 root_fs_names = str;
117 return 1;
118}
119
120static unsigned int __initdata root_delay;
121static 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 */
132static 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
148static 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(dev_name: name, dir_name: "/root", type_page: fs, flags, data_page);
166 if (ret)
167 goto out;
168
169 init_chdir(filename: "/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
178out:
179 if (p)
180 put_page(page: p);
181 return ret;
182}
183
184void __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(buf: b, BDEVNAME_SIZE, fmt: "unknown-block(%u,%u)",
193 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
194 if (root_fs_names)
195 num_fs = split_fs_names(page: fs_names, PAGE_SIZE);
196 else
197 num_fs = list_bdev_fs_names(buf: fs_names, PAGE_SIZE);
198retry:
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, fs: p, flags, data: 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(buf: 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(fmt: "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(fmt: "VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
250out:
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
260static 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_device: &root_dev, root_data: &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(name: root_dev, fs: "nfs", flags: root_mountflags, data: root_data))
277 return;
278 if (try > NFSROOT_RETRY_MAX)
279 break;
280
281 /* Wait, in case the server refused us immediately */
282 ssleep(seconds: timeout);
283 timeout <<= 1;
284 if (timeout > NFSROOT_TIMEOUT_MAX)
285 timeout = NFSROOT_TIMEOUT_MAX;
286 }
287fail:
288 pr_err("VFS: Unable to mount root fs via NFS.\n");
289}
290#else
291static 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
302static 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 }
324fail:
325 pr_err("VFS: Unable to mount root fs via SMB.\n");
326}
327#else
328static inline void mount_cifs_root(void)
329{
330}
331#endif /* CONFIG_CIFS_ROOT */
332
333static bool __init fs_is_nodev(char *fstype)
334{
335 struct file_system_type *fs = get_fs_type(name: 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
346static 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(page: 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(name: root_device_name, fs: fstype, flags: root_mountflags,
364 data: 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
374static void __init mount_block_root(char *root_device_name)
375{
376 int err = create_dev(name: "/dev/root", dev: ROOT_DEV);
377
378 if (err < 0)
379 pr_emerg("Failed to create /dev/root: %d\n", err);
380 mount_root_generic(name: "/dev/root", pretty_name: root_device_name, flags: root_mountflags);
381}
382#else
383static inline void mount_block_root(char *root_device_name)
384{
385}
386#endif /* CONFIG_BLOCK */
387
388void __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(name: root_device_name, pretty_name: root_device_name,
399 flags: 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 */
413static 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(kt: ktime_get_raw(), msec: root_wait);
423
424 while (!driver_probe_done() ||
425 early_lookup_bdev(pathname: root_device_name, dev: &ROOT_DEV) < 0) {
426 msleep(msecs: 5);
427 if (root_wait > 0 && ktime_after(cmp1: ktime_get_raw(), cmp2: end))
428 break;
429 }
430
431 async_synchronize_full();
432
433}
434
435static 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(pathname: root_device_name, dev: &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 */
464void __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(seconds: 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(root_device_name: saved_root_name);
485
486 if (initrd_load(root_device_name: saved_root_name))
487 goto out;
488
489 if (root_wait)
490 wait_for_root(root_device_name: saved_root_name);
491 mount_root(root_device_name: saved_root_name);
492out:
493 devtmpfs_mount();
494 init_mount(dev_name: ".", dir_name: "/", NULL, MS_MOVE, NULL);
495 init_chroot(filename: ".");
496}
497
498static bool is_tmpfs;
499static 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
507struct 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
513void __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}
522