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(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
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(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
178out:
179	if (p)
180		put_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(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);
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, 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);
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_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	}
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(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(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
374static 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
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(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 */
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(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
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(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 */
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(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);
492out:
493	devtmpfs_mount();
494	init_mount(".", "/", NULL, MS_MOVE, NULL);
495	init_chroot(".");
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