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		/* 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
179out:
180	if (p)
181		put_page(p);
182	return ret;
183}
184
185void __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);
199retry:
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);
251out:
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
261static 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	}
288fail:
289	pr_err("VFS: Unable to mount root fs via NFS.\n");
290}
291#else
292static 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
303static 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	}
325fail:
326	pr_err("VFS: Unable to mount root fs via SMB.\n");
327}
328#else
329static inline void mount_cifs_root(void)
330{
331}
332#endif /* CONFIG_CIFS_ROOT */
333
334static 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
347static 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
375static 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
384static inline void mount_block_root(char *root_device_name)
385{
386}
387#endif /* CONFIG_BLOCK */
388
389void __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 */
414static 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
436static 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 */
465void __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);
493out:
494	devtmpfs_mount();
495	init_mount(".", "/", NULL, MS_MOVE, NULL);
496	init_chroot(".");
497}
498
499static bool is_tmpfs;
500static 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
508struct 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
514void __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}
523