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/genhd.h>
12 #include <linux/mount.h>
13 #include <linux/device.h>
14 #include <linux/init.h>
15 #include <linux/fs.h>
16 #include <linux/initrd.h>
17 #include <linux/async.h>
18 #include <linux/fs_struct.h>
19 #include <linux/slab.h>
20 #include <linux/ramfs.h>
21 #include <linux/shmem_fs.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 root_device_name;
33 static char __initdata saved_root_name[64];
34 static int root_wait;
35 
36 dev_t ROOT_DEV;
37 
load_ramdisk(char * str)38 static int __init load_ramdisk(char *str)
39 {
40 	pr_warn("ignoring the deprecated load_ramdisk= option\n");
41 	return 1;
42 }
43 __setup("load_ramdisk=", load_ramdisk);
44 
readonly(char * str)45 static int __init readonly(char *str)
46 {
47 	if (*str)
48 		return 0;
49 	root_mountflags |= MS_RDONLY;
50 	return 1;
51 }
52 
readwrite(char * str)53 static int __init readwrite(char *str)
54 {
55 	if (*str)
56 		return 0;
57 	root_mountflags &= ~MS_RDONLY;
58 	return 1;
59 }
60 
61 __setup("ro", readonly);
62 __setup("rw", readwrite);
63 
64 #ifdef CONFIG_BLOCK
65 struct uuidcmp {
66 	const char *uuid;
67 	int len;
68 };
69 
70 /**
71  * match_dev_by_uuid - callback for finding a partition using its uuid
72  * @dev:	device passed in by the caller
73  * @data:	opaque pointer to the desired struct uuidcmp to match
74  *
75  * Returns 1 if the device matches, and 0 otherwise.
76  */
match_dev_by_uuid(struct device * dev,const void * data)77 static int match_dev_by_uuid(struct device *dev, const void *data)
78 {
79 	struct block_device *bdev = dev_to_bdev(dev);
80 	const struct uuidcmp *cmp = data;
81 
82 	if (!bdev->bd_meta_info ||
83 	    strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
84 		return 0;
85 	return 1;
86 }
87 
88 /**
89  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
90  * @uuid_str:	char array containing ascii UUID
91  *
92  * The function will return the first partition which contains a matching
93  * UUID value in its partition_meta_info struct.  This does not search
94  * by filesystem UUIDs.
95  *
96  * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
97  * extracted and used as an offset from the partition identified by the UUID.
98  *
99  * Returns the matching dev_t on success or 0 on failure.
100  */
devt_from_partuuid(const char * uuid_str)101 static dev_t devt_from_partuuid(const char *uuid_str)
102 {
103 	struct uuidcmp cmp;
104 	struct device *dev = NULL;
105 	dev_t devt = 0;
106 	int offset = 0;
107 	char *slash;
108 
109 	cmp.uuid = uuid_str;
110 
111 	slash = strchr(uuid_str, '/');
112 	/* Check for optional partition number offset attributes. */
113 	if (slash) {
114 		char c = 0;
115 
116 		/* Explicitly fail on poor PARTUUID syntax. */
117 		if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
118 			goto clear_root_wait;
119 		cmp.len = slash - uuid_str;
120 	} else {
121 		cmp.len = strlen(uuid_str);
122 	}
123 
124 	if (!cmp.len)
125 		goto clear_root_wait;
126 
127 	dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
128 	if (!dev)
129 		return 0;
130 
131 	if (offset) {
132 		/*
133 		 * Attempt to find the requested partition by adding an offset
134 		 * to the partition number found by UUID.
135 		 */
136 		devt = part_devt(dev_to_disk(dev),
137 				 dev_to_bdev(dev)->bd_partno + offset);
138 	} else {
139 		devt = dev->devt;
140 	}
141 
142 	put_device(dev);
143 	return devt;
144 
145 clear_root_wait:
146 	pr_err("VFS: PARTUUID= is invalid.\n"
147 	       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
148 	if (root_wait)
149 		pr_err("Disabling rootwait; root= is invalid.\n");
150 	root_wait = 0;
151 	return 0;
152 }
153 
154 /**
155  * match_dev_by_label - callback for finding a partition using its label
156  * @dev:	device passed in by the caller
157  * @data:	opaque pointer to the label to match
158  *
159  * Returns 1 if the device matches, and 0 otherwise.
160  */
match_dev_by_label(struct device * dev,const void * data)161 static int match_dev_by_label(struct device *dev, const void *data)
162 {
163 	struct block_device *bdev = dev_to_bdev(dev);
164 	const char *label = data;
165 
166 	if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
167 		return 0;
168 	return 1;
169 }
170 
devt_from_partlabel(const char * label)171 static dev_t devt_from_partlabel(const char *label)
172 {
173 	struct device *dev;
174 	dev_t devt = 0;
175 
176 	dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
177 	if (dev) {
178 		devt = dev->devt;
179 		put_device(dev);
180 	}
181 
182 	return devt;
183 }
184 
devt_from_devname(const char * name)185 static dev_t devt_from_devname(const char *name)
186 {
187 	dev_t devt = 0;
188 	int part;
189 	char s[32];
190 	char *p;
191 
192 	if (strlen(name) > 31)
193 		return 0;
194 	strcpy(s, name);
195 	for (p = s; *p; p++) {
196 		if (*p == '/')
197 			*p = '!';
198 	}
199 
200 	devt = blk_lookup_devt(s, 0);
201 	if (devt)
202 		return devt;
203 
204 	/*
205 	 * Try non-existent, but valid partition, which may only exist after
206 	 * opening the device, like partitioned md devices.
207 	 */
208 	while (p > s && isdigit(p[-1]))
209 		p--;
210 	if (p == s || !*p || *p == '0')
211 		return 0;
212 
213 	/* try disk name without <part number> */
214 	part = simple_strtoul(p, NULL, 10);
215 	*p = '\0';
216 	devt = blk_lookup_devt(s, part);
217 	if (devt)
218 		return devt;
219 
220 	/* try disk name without p<part number> */
221 	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
222 		return 0;
223 	p[-1] = '\0';
224 	return blk_lookup_devt(s, part);
225 }
226 #endif /* CONFIG_BLOCK */
227 
devt_from_devnum(const char * name)228 static dev_t devt_from_devnum(const char *name)
229 {
230 	unsigned maj, min, offset;
231 	dev_t devt = 0;
232 	char *p, dummy;
233 
234 	if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
235 	    sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
236 		devt = MKDEV(maj, min);
237 		if (maj != MAJOR(devt) || min != MINOR(devt))
238 			return 0;
239 	} else {
240 		devt = new_decode_dev(simple_strtoul(name, &p, 16));
241 		if (*p)
242 			return 0;
243 	}
244 
245 	return devt;
246 }
247 
248 /*
249  *	Convert a name into device number.  We accept the following variants:
250  *
251  *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
252  *         no leading 0x, for example b302.
253  *	2) /dev/nfs represents Root_NFS (0xff)
254  *	3) /dev/<disk_name> represents the device number of disk
255  *	4) /dev/<disk_name><decimal> represents the device number
256  *         of partition - device number of disk plus the partition number
257  *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
258  *	   used when disk name of partitioned disk ends on a digit.
259  *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
260  *	   unique id of a partition if the partition table provides it.
261  *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
262  *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
263  *	   filled hex representation of the 32-bit "NT disk signature", and PP
264  *	   is a zero-filled hex representation of the 1-based partition number.
265  *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
266  *	   a partition with a known unique id.
267  *	8) <major>:<minor> major and minor number of the device separated by
268  *	   a colon.
269  *	9) PARTLABEL=<name> with name being the GPT partition label.
270  *	   MSDOS partitions do not support labels!
271  *	10) /dev/cifs represents Root_CIFS (0xfe)
272  *
273  *	If name doesn't have fall into the categories above, we return (0,0).
274  *	block_class is used to check if something is a disk name. If the disk
275  *	name contains slashes, the device name has them replaced with
276  *	bangs.
277  */
name_to_dev_t(const char * name)278 dev_t name_to_dev_t(const char *name)
279 {
280 	if (strcmp(name, "/dev/nfs") == 0)
281 		return Root_NFS;
282 	if (strcmp(name, "/dev/cifs") == 0)
283 		return Root_CIFS;
284 	if (strcmp(name, "/dev/ram") == 0)
285 		return Root_RAM0;
286 #ifdef CONFIG_BLOCK
287 	if (strncmp(name, "PARTUUID=", 9) == 0)
288 		return devt_from_partuuid(name + 9);
289 	if (strncmp(name, "PARTLABEL=", 10) == 0)
290 		return devt_from_partlabel(name + 10);
291 	if (strncmp(name, "/dev/", 5) == 0)
292 		return devt_from_devname(name + 5);
293 #endif
294 	return devt_from_devnum(name);
295 }
296 EXPORT_SYMBOL_GPL(name_to_dev_t);
297 
root_dev_setup(char * line)298 static int __init root_dev_setup(char *line)
299 {
300 	strlcpy(saved_root_name, line, sizeof(saved_root_name));
301 	return 1;
302 }
303 
304 __setup("root=", root_dev_setup);
305 
rootwait_setup(char * str)306 static int __init rootwait_setup(char *str)
307 {
308 	if (*str)
309 		return 0;
310 	root_wait = 1;
311 	return 1;
312 }
313 
314 __setup("rootwait", rootwait_setup);
315 
316 static char * __initdata root_mount_data;
root_data_setup(char * str)317 static int __init root_data_setup(char *str)
318 {
319 	root_mount_data = str;
320 	return 1;
321 }
322 
323 static char * __initdata root_fs_names;
fs_names_setup(char * str)324 static int __init fs_names_setup(char *str)
325 {
326 	root_fs_names = str;
327 	return 1;
328 }
329 
330 static unsigned int __initdata root_delay;
root_delay_setup(char * str)331 static int __init root_delay_setup(char *str)
332 {
333 	root_delay = simple_strtoul(str, NULL, 0);
334 	return 1;
335 }
336 
337 __setup("rootflags=", root_data_setup);
338 __setup("rootfstype=", fs_names_setup);
339 __setup("rootdelay=", root_delay_setup);
340 
341 /* This can return zero length strings. Caller should check */
split_fs_names(char * page,size_t size,char * names)342 static int __init split_fs_names(char *page, size_t size, char *names)
343 {
344 	int count = 1;
345 	char *p = page;
346 
347 	strlcpy(p, root_fs_names, size);
348 	while (*p++) {
349 		if (p[-1] == ',') {
350 			p[-1] = '\0';
351 			count++;
352 		}
353 	}
354 
355 	return count;
356 }
357 
do_mount_root(const char * name,const char * fs,const int flags,const void * data)358 static int __init do_mount_root(const char *name, const char *fs,
359 				 const int flags, const void *data)
360 {
361 	struct super_block *s;
362 	struct page *p = NULL;
363 	char *data_page = NULL;
364 	int ret;
365 
366 	if (data) {
367 		/* init_mount() requires a full page as fifth argument */
368 		p = alloc_page(GFP_KERNEL);
369 		if (!p)
370 			return -ENOMEM;
371 		data_page = page_address(p);
372 		/* zero-pad. init_mount() will make sure it's terminated */
373 		strncpy(data_page, data, PAGE_SIZE);
374 	}
375 
376 	ret = init_mount(name, "/root", fs, flags, data_page);
377 	if (ret)
378 		goto out;
379 
380 	init_chdir("/root");
381 	s = current->fs->pwd.dentry->d_sb;
382 	ROOT_DEV = s->s_dev;
383 	printk(KERN_INFO
384 	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
385 	       s->s_type->name,
386 	       sb_rdonly(s) ? " readonly" : "",
387 	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
388 
389 out:
390 	if (p)
391 		put_page(p);
392 	return ret;
393 }
394 
mount_block_root(char * name,int flags)395 void __init mount_block_root(char *name, int flags)
396 {
397 	struct page *page = alloc_page(GFP_KERNEL);
398 	char *fs_names = page_address(page);
399 	char *p;
400 	char b[BDEVNAME_SIZE];
401 	int num_fs, i;
402 
403 	scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
404 		  MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
405 	if (root_fs_names)
406 		num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
407 	else
408 		num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
409 retry:
410 	for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
411 		int err;
412 
413 		if (!*p)
414 			continue;
415 		err = do_mount_root(name, p, flags, root_mount_data);
416 		switch (err) {
417 			case 0:
418 				goto out;
419 			case -EACCES:
420 			case -EINVAL:
421 				continue;
422 		}
423 	        /*
424 		 * Allow the user to distinguish between failed sys_open
425 		 * and bad superblock on root device.
426 		 * and give them a list of the available devices
427 		 */
428 		printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
429 				root_device_name, b, err);
430 		printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
431 
432 		printk_all_partitions();
433 		panic("VFS: Unable to mount root fs on %s", b);
434 	}
435 	if (!(flags & SB_RDONLY)) {
436 		flags |= SB_RDONLY;
437 		goto retry;
438 	}
439 
440 	printk("List of all partitions:\n");
441 	printk_all_partitions();
442 	printk("No filesystem could mount root, tried: ");
443 	for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
444 		printk(" %s", p);
445 	printk("\n");
446 	panic("VFS: Unable to mount root fs on %s", b);
447 out:
448 	put_page(page);
449 }
450 
451 #ifdef CONFIG_ROOT_NFS
452 
453 #define NFSROOT_TIMEOUT_MIN	5
454 #define NFSROOT_TIMEOUT_MAX	30
455 #define NFSROOT_RETRY_MAX	5
456 
mount_nfs_root(void)457 static int __init mount_nfs_root(void)
458 {
459 	char *root_dev, *root_data;
460 	unsigned int timeout;
461 	int try, err;
462 
463 	err = nfs_root_data(&root_dev, &root_data);
464 	if (err != 0)
465 		return 0;
466 
467 	/*
468 	 * The server or network may not be ready, so try several
469 	 * times.  Stop after a few tries in case the client wants
470 	 * to fall back to other boot methods.
471 	 */
472 	timeout = NFSROOT_TIMEOUT_MIN;
473 	for (try = 1; ; try++) {
474 		err = do_mount_root(root_dev, "nfs",
475 					root_mountflags, root_data);
476 		if (err == 0)
477 			return 1;
478 		if (try > NFSROOT_RETRY_MAX)
479 			break;
480 
481 		/* Wait, in case the server refused us immediately */
482 		ssleep(timeout);
483 		timeout <<= 1;
484 		if (timeout > NFSROOT_TIMEOUT_MAX)
485 			timeout = NFSROOT_TIMEOUT_MAX;
486 	}
487 	return 0;
488 }
489 #endif
490 
491 #ifdef CONFIG_CIFS_ROOT
492 
493 extern int cifs_root_data(char **dev, char **opts);
494 
495 #define CIFSROOT_TIMEOUT_MIN	5
496 #define CIFSROOT_TIMEOUT_MAX	30
497 #define CIFSROOT_RETRY_MAX	5
498 
mount_cifs_root(void)499 static int __init mount_cifs_root(void)
500 {
501 	char *root_dev, *root_data;
502 	unsigned int timeout;
503 	int try, err;
504 
505 	err = cifs_root_data(&root_dev, &root_data);
506 	if (err != 0)
507 		return 0;
508 
509 	timeout = CIFSROOT_TIMEOUT_MIN;
510 	for (try = 1; ; try++) {
511 		err = do_mount_root(root_dev, "cifs", root_mountflags,
512 				    root_data);
513 		if (err == 0)
514 			return 1;
515 		if (try > CIFSROOT_RETRY_MAX)
516 			break;
517 
518 		ssleep(timeout);
519 		timeout <<= 1;
520 		if (timeout > CIFSROOT_TIMEOUT_MAX)
521 			timeout = CIFSROOT_TIMEOUT_MAX;
522 	}
523 	return 0;
524 }
525 #endif
526 
fs_is_nodev(char * fstype)527 static bool __init fs_is_nodev(char *fstype)
528 {
529 	struct file_system_type *fs = get_fs_type(fstype);
530 	bool ret = false;
531 
532 	if (fs) {
533 		ret = !(fs->fs_flags & FS_REQUIRES_DEV);
534 		put_filesystem(fs);
535 	}
536 
537 	return ret;
538 }
539 
mount_nodev_root(void)540 static int __init mount_nodev_root(void)
541 {
542 	char *fs_names, *fstype;
543 	int err = -EINVAL;
544 	int num_fs, i;
545 
546 	fs_names = (void *)__get_free_page(GFP_KERNEL);
547 	if (!fs_names)
548 		return -EINVAL;
549 	num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
550 
551 	for (i = 0, fstype = fs_names; i < num_fs;
552 	     i++, fstype += strlen(fstype) + 1) {
553 		if (!*fstype)
554 			continue;
555 		if (!fs_is_nodev(fstype))
556 			continue;
557 		err = do_mount_root(root_device_name, fstype, root_mountflags,
558 				    root_mount_data);
559 		if (!err)
560 			break;
561 	}
562 
563 	free_page((unsigned long)fs_names);
564 	return err;
565 }
566 
mount_root(void)567 void __init mount_root(void)
568 {
569 #ifdef CONFIG_ROOT_NFS
570 	if (ROOT_DEV == Root_NFS) {
571 		if (!mount_nfs_root())
572 			printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
573 		return;
574 	}
575 #endif
576 #ifdef CONFIG_CIFS_ROOT
577 	if (ROOT_DEV == Root_CIFS) {
578 		if (!mount_cifs_root())
579 			printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
580 		return;
581 	}
582 #endif
583 	if (ROOT_DEV == 0 && root_device_name && root_fs_names) {
584 		if (mount_nodev_root() == 0)
585 			return;
586 	}
587 #ifdef CONFIG_BLOCK
588 	{
589 		int err = create_dev("/dev/root", ROOT_DEV);
590 
591 		if (err < 0)
592 			pr_emerg("Failed to create /dev/root: %d\n", err);
593 		mount_block_root("/dev/root", root_mountflags);
594 	}
595 #endif
596 }
597 
598 /*
599  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
600  */
prepare_namespace(void)601 void __init prepare_namespace(void)
602 {
603 	if (root_delay) {
604 		printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
605 		       root_delay);
606 		ssleep(root_delay);
607 	}
608 
609 	/*
610 	 * wait for the known devices to complete their probing
611 	 *
612 	 * Note: this is a potential source of long boot delays.
613 	 * For example, it is not atypical to wait 5 seconds here
614 	 * for the touchpad of a laptop to initialize.
615 	 */
616 	wait_for_device_probe();
617 
618 	md_run_setup();
619 
620 	if (saved_root_name[0]) {
621 		root_device_name = saved_root_name;
622 		if (!strncmp(root_device_name, "mtd", 3) ||
623 		    !strncmp(root_device_name, "ubi", 3)) {
624 			mount_block_root(root_device_name, root_mountflags);
625 			goto out;
626 		}
627 		ROOT_DEV = name_to_dev_t(root_device_name);
628 		if (strncmp(root_device_name, "/dev/", 5) == 0)
629 			root_device_name += 5;
630 	}
631 
632 	if (initrd_load())
633 		goto out;
634 
635 	/* wait for any asynchronous scanning to complete */
636 	if ((ROOT_DEV == 0) && root_wait) {
637 		printk(KERN_INFO "Waiting for root device %s...\n",
638 			saved_root_name);
639 		while (driver_probe_done() != 0 ||
640 			(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
641 			msleep(5);
642 		async_synchronize_full();
643 	}
644 
645 	mount_root();
646 out:
647 	devtmpfs_mount();
648 	init_mount(".", "/", NULL, MS_MOVE, NULL);
649 	init_chroot(".");
650 }
651 
652 static bool is_tmpfs;
rootfs_init_fs_context(struct fs_context * fc)653 static int rootfs_init_fs_context(struct fs_context *fc)
654 {
655 	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
656 		return shmem_init_fs_context(fc);
657 
658 	return ramfs_init_fs_context(fc);
659 }
660 
661 struct file_system_type rootfs_fs_type = {
662 	.name		= "rootfs",
663 	.init_fs_context = rootfs_init_fs_context,
664 	.kill_sb	= kill_litter_super,
665 };
666 
init_rootfs(void)667 void __init init_rootfs(void)
668 {
669 	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
670 		(!root_fs_names || strstr(root_fs_names, "tmpfs")))
671 		is_tmpfs = true;
672 }
673