xref: /openbmc/linux/init/do_mounts.c (revision f59a3ee6)
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 
22 #include <linux/nfs_fs.h>
23 #include <linux/nfs_fs_sb.h>
24 #include <linux/nfs_mount.h>
25 #include <linux/raid/detect.h>
26 #include <uapi/linux/mount.h>
27 
28 #include "do_mounts.h"
29 
30 int root_mountflags = MS_RDONLY | MS_SILENT;
31 static char * __initdata root_device_name;
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 #ifdef CONFIG_BLOCK
64 struct uuidcmp {
65 	const char *uuid;
66 	int len;
67 };
68 
69 /**
70  * match_dev_by_uuid - callback for finding a partition using its uuid
71  * @dev:	device passed in by the caller
72  * @data:	opaque pointer to the desired struct uuidcmp to match
73  *
74  * Returns 1 if the device matches, and 0 otherwise.
75  */
76 static int match_dev_by_uuid(struct device *dev, const void *data)
77 {
78 	struct block_device *bdev = dev_to_bdev(dev);
79 	const struct uuidcmp *cmp = data;
80 
81 	if (!bdev->bd_meta_info ||
82 	    strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
83 		return 0;
84 	return 1;
85 }
86 
87 /**
88  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
89  * @uuid_str:	char array containing ascii UUID
90  *
91  * The function will return the first partition which contains a matching
92  * UUID value in its partition_meta_info struct.  This does not search
93  * by filesystem UUIDs.
94  *
95  * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
96  * extracted and used as an offset from the partition identified by the UUID.
97  *
98  * Returns the matching dev_t on success or 0 on failure.
99  */
100 static dev_t devt_from_partuuid(const char *uuid_str)
101 {
102 	struct uuidcmp cmp;
103 	struct device *dev = NULL;
104 	dev_t devt = 0;
105 	int offset = 0;
106 	char *slash;
107 
108 	cmp.uuid = uuid_str;
109 
110 	slash = strchr(uuid_str, '/');
111 	/* Check for optional partition number offset attributes. */
112 	if (slash) {
113 		char c = 0;
114 
115 		/* Explicitly fail on poor PARTUUID syntax. */
116 		if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
117 			goto clear_root_wait;
118 		cmp.len = slash - uuid_str;
119 	} else {
120 		cmp.len = strlen(uuid_str);
121 	}
122 
123 	if (!cmp.len)
124 		goto clear_root_wait;
125 
126 	dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
127 	if (!dev)
128 		return 0;
129 
130 	if (offset) {
131 		/*
132 		 * Attempt to find the requested partition by adding an offset
133 		 * to the partition number found by UUID.
134 		 */
135 		devt = part_devt(dev_to_disk(dev),
136 				 dev_to_bdev(dev)->bd_partno + offset);
137 	} else {
138 		devt = dev->devt;
139 	}
140 
141 	put_device(dev);
142 	return devt;
143 
144 clear_root_wait:
145 	pr_err("VFS: PARTUUID= is invalid.\n"
146 	       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
147 	if (root_wait)
148 		pr_err("Disabling rootwait; root= is invalid.\n");
149 	root_wait = 0;
150 	return 0;
151 }
152 
153 /**
154  * match_dev_by_label - callback for finding a partition using its label
155  * @dev:	device passed in by the caller
156  * @data:	opaque pointer to the label to match
157  *
158  * Returns 1 if the device matches, and 0 otherwise.
159  */
160 static int match_dev_by_label(struct device *dev, const void *data)
161 {
162 	struct block_device *bdev = dev_to_bdev(dev);
163 	const char *label = data;
164 
165 	if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
166 		return 0;
167 	return 1;
168 }
169 
170 static dev_t devt_from_partlabel(const char *label)
171 {
172 	struct device *dev;
173 	dev_t devt = 0;
174 
175 	dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
176 	if (dev) {
177 		devt = dev->devt;
178 		put_device(dev);
179 	}
180 
181 	return devt;
182 }
183 
184 static dev_t devt_from_devname(const char *name)
185 {
186 	dev_t devt = 0;
187 	int part;
188 	char s[32];
189 	char *p;
190 
191 	if (strlen(name) > 31)
192 		return 0;
193 	strcpy(s, name);
194 	for (p = s; *p; p++) {
195 		if (*p == '/')
196 			*p = '!';
197 	}
198 
199 	devt = blk_lookup_devt(s, 0);
200 	if (devt)
201 		return devt;
202 
203 	/*
204 	 * Try non-existent, but valid partition, which may only exist after
205 	 * opening the device, like partitioned md devices.
206 	 */
207 	while (p > s && isdigit(p[-1]))
208 		p--;
209 	if (p == s || !*p || *p == '0')
210 		return 0;
211 
212 	/* try disk name without <part number> */
213 	part = simple_strtoul(p, NULL, 10);
214 	*p = '\0';
215 	devt = blk_lookup_devt(s, part);
216 	if (devt)
217 		return devt;
218 
219 	/* try disk name without p<part number> */
220 	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
221 		return 0;
222 	p[-1] = '\0';
223 	return blk_lookup_devt(s, part);
224 }
225 #endif /* CONFIG_BLOCK */
226 
227 static dev_t devt_from_devnum(const char *name)
228 {
229 	unsigned maj, min, offset;
230 	dev_t devt = 0;
231 	char *p, dummy;
232 
233 	if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
234 	    sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
235 		devt = MKDEV(maj, min);
236 		if (maj != MAJOR(devt) || min != MINOR(devt))
237 			return 0;
238 	} else {
239 		devt = new_decode_dev(simple_strtoul(name, &p, 16));
240 		if (*p)
241 			return 0;
242 	}
243 
244 	return devt;
245 }
246 
247 /*
248  *	Convert a name into device number.  We accept the following variants:
249  *
250  *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
251  *         no leading 0x, for example b302.
252  *	2) /dev/nfs represents Root_NFS (0xff)
253  *	3) /dev/<disk_name> represents the device number of disk
254  *	4) /dev/<disk_name><decimal> represents the device number
255  *         of partition - device number of disk plus the partition number
256  *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
257  *	   used when disk name of partitioned disk ends on a digit.
258  *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
259  *	   unique id of a partition if the partition table provides it.
260  *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
261  *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
262  *	   filled hex representation of the 32-bit "NT disk signature", and PP
263  *	   is a zero-filled hex representation of the 1-based partition number.
264  *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
265  *	   a partition with a known unique id.
266  *	8) <major>:<minor> major and minor number of the device separated by
267  *	   a colon.
268  *	9) PARTLABEL=<name> with name being the GPT partition label.
269  *	   MSDOS partitions do not support labels!
270  *	10) /dev/cifs represents Root_CIFS (0xfe)
271  *
272  *	If name doesn't have fall into the categories above, we return (0,0).
273  *	block_class is used to check if something is a disk name. If the disk
274  *	name contains slashes, the device name has them replaced with
275  *	bangs.
276  */
277 dev_t name_to_dev_t(const char *name)
278 {
279 	if (strcmp(name, "/dev/nfs") == 0)
280 		return Root_NFS;
281 	if (strcmp(name, "/dev/cifs") == 0)
282 		return Root_CIFS;
283 	if (strcmp(name, "/dev/ram") == 0)
284 		return Root_RAM0;
285 #ifdef CONFIG_BLOCK
286 	if (strncmp(name, "PARTUUID=", 9) == 0)
287 		return devt_from_partuuid(name + 9);
288 	if (strncmp(name, "PARTLABEL=", 10) == 0)
289 		return devt_from_partlabel(name + 10);
290 	if (strncmp(name, "/dev/", 5) == 0)
291 		return devt_from_devname(name + 5);
292 #endif
293 	return devt_from_devnum(name);
294 }
295 EXPORT_SYMBOL_GPL(name_to_dev_t);
296 
297 static int __init root_dev_setup(char *line)
298 {
299 	strscpy(saved_root_name, line, sizeof(saved_root_name));
300 	return 1;
301 }
302 
303 __setup("root=", root_dev_setup);
304 
305 static int __init rootwait_setup(char *str)
306 {
307 	if (*str)
308 		return 0;
309 	root_wait = 1;
310 	return 1;
311 }
312 
313 __setup("rootwait", rootwait_setup);
314 
315 static char * __initdata root_mount_data;
316 static int __init root_data_setup(char *str)
317 {
318 	root_mount_data = str;
319 	return 1;
320 }
321 
322 static char * __initdata root_fs_names;
323 static int __init fs_names_setup(char *str)
324 {
325 	root_fs_names = str;
326 	return 1;
327 }
328 
329 static unsigned int __initdata root_delay;
330 static int __init root_delay_setup(char *str)
331 {
332 	root_delay = simple_strtoul(str, NULL, 0);
333 	return 1;
334 }
335 
336 __setup("rootflags=", root_data_setup);
337 __setup("rootfstype=", fs_names_setup);
338 __setup("rootdelay=", root_delay_setup);
339 
340 /* This can return zero length strings. Caller should check */
341 static int __init split_fs_names(char *page, size_t size, char *names)
342 {
343 	int count = 1;
344 	char *p = page;
345 
346 	strscpy(p, root_fs_names, size);
347 	while (*p++) {
348 		if (p[-1] == ',') {
349 			p[-1] = '\0';
350 			count++;
351 		}
352 	}
353 
354 	return count;
355 }
356 
357 static int __init do_mount_root(const char *name, const char *fs,
358 				 const int flags, const void *data)
359 {
360 	struct super_block *s;
361 	struct page *p = NULL;
362 	char *data_page = NULL;
363 	int ret;
364 
365 	if (data) {
366 		/* init_mount() requires a full page as fifth argument */
367 		p = alloc_page(GFP_KERNEL);
368 		if (!p)
369 			return -ENOMEM;
370 		data_page = page_address(p);
371 		/* zero-pad. init_mount() will make sure it's terminated */
372 		strncpy(data_page, data, PAGE_SIZE);
373 	}
374 
375 	ret = init_mount(name, "/root", fs, flags, data_page);
376 	if (ret)
377 		goto out;
378 
379 	init_chdir("/root");
380 	s = current->fs->pwd.dentry->d_sb;
381 	ROOT_DEV = s->s_dev;
382 	printk(KERN_INFO
383 	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
384 	       s->s_type->name,
385 	       sb_rdonly(s) ? " readonly" : "",
386 	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
387 
388 out:
389 	if (p)
390 		put_page(p);
391 	return ret;
392 }
393 
394 void __init mount_block_root(char *name, int flags)
395 {
396 	struct page *page = alloc_page(GFP_KERNEL);
397 	char *fs_names = page_address(page);
398 	char *p;
399 	char b[BDEVNAME_SIZE];
400 	int num_fs, i;
401 
402 	scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
403 		  MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
404 	if (root_fs_names)
405 		num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
406 	else
407 		num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
408 retry:
409 	for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
410 		int err;
411 
412 		if (!*p)
413 			continue;
414 		err = do_mount_root(name, p, flags, root_mount_data);
415 		switch (err) {
416 			case 0:
417 				goto out;
418 			case -EACCES:
419 			case -EINVAL:
420 				continue;
421 		}
422 	        /*
423 		 * Allow the user to distinguish between failed sys_open
424 		 * and bad superblock on root device.
425 		 * and give them a list of the available devices
426 		 */
427 		printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
428 				root_device_name, b, err);
429 		printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
430 
431 		printk_all_partitions();
432 		panic("VFS: Unable to mount root fs on %s", b);
433 	}
434 	if (!(flags & SB_RDONLY)) {
435 		flags |= SB_RDONLY;
436 		goto retry;
437 	}
438 
439 	printk("List of all partitions:\n");
440 	printk_all_partitions();
441 	printk("No filesystem could mount root, tried: ");
442 	for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
443 		printk(" %s", p);
444 	printk("\n");
445 	panic("VFS: Unable to mount root fs on %s", b);
446 out:
447 	put_page(page);
448 }
449 
450 #ifdef CONFIG_ROOT_NFS
451 
452 #define NFSROOT_TIMEOUT_MIN	5
453 #define NFSROOT_TIMEOUT_MAX	30
454 #define NFSROOT_RETRY_MAX	5
455 
456 static int __init mount_nfs_root(void)
457 {
458 	char *root_dev, *root_data;
459 	unsigned int timeout;
460 	int try, err;
461 
462 	err = nfs_root_data(&root_dev, &root_data);
463 	if (err != 0)
464 		return 0;
465 
466 	/*
467 	 * The server or network may not be ready, so try several
468 	 * times.  Stop after a few tries in case the client wants
469 	 * to fall back to other boot methods.
470 	 */
471 	timeout = NFSROOT_TIMEOUT_MIN;
472 	for (try = 1; ; try++) {
473 		err = do_mount_root(root_dev, "nfs",
474 					root_mountflags, root_data);
475 		if (err == 0)
476 			return 1;
477 		if (try > NFSROOT_RETRY_MAX)
478 			break;
479 
480 		/* Wait, in case the server refused us immediately */
481 		ssleep(timeout);
482 		timeout <<= 1;
483 		if (timeout > NFSROOT_TIMEOUT_MAX)
484 			timeout = NFSROOT_TIMEOUT_MAX;
485 	}
486 	return 0;
487 }
488 #endif
489 
490 #ifdef CONFIG_CIFS_ROOT
491 
492 extern int cifs_root_data(char **dev, char **opts);
493 
494 #define CIFSROOT_TIMEOUT_MIN	5
495 #define CIFSROOT_TIMEOUT_MAX	30
496 #define CIFSROOT_RETRY_MAX	5
497 
498 static int __init mount_cifs_root(void)
499 {
500 	char *root_dev, *root_data;
501 	unsigned int timeout;
502 	int try, err;
503 
504 	err = cifs_root_data(&root_dev, &root_data);
505 	if (err != 0)
506 		return 0;
507 
508 	timeout = CIFSROOT_TIMEOUT_MIN;
509 	for (try = 1; ; try++) {
510 		err = do_mount_root(root_dev, "cifs", root_mountflags,
511 				    root_data);
512 		if (err == 0)
513 			return 1;
514 		if (try > CIFSROOT_RETRY_MAX)
515 			break;
516 
517 		ssleep(timeout);
518 		timeout <<= 1;
519 		if (timeout > CIFSROOT_TIMEOUT_MAX)
520 			timeout = CIFSROOT_TIMEOUT_MAX;
521 	}
522 	return 0;
523 }
524 #endif
525 
526 static bool __init fs_is_nodev(char *fstype)
527 {
528 	struct file_system_type *fs = get_fs_type(fstype);
529 	bool ret = false;
530 
531 	if (fs) {
532 		ret = !(fs->fs_flags & FS_REQUIRES_DEV);
533 		put_filesystem(fs);
534 	}
535 
536 	return ret;
537 }
538 
539 static int __init mount_nodev_root(void)
540 {
541 	char *fs_names, *fstype;
542 	int err = -EINVAL;
543 	int num_fs, i;
544 
545 	fs_names = (void *)__get_free_page(GFP_KERNEL);
546 	if (!fs_names)
547 		return -EINVAL;
548 	num_fs = split_fs_names(fs_names, PAGE_SIZE, root_fs_names);
549 
550 	for (i = 0, fstype = fs_names; i < num_fs;
551 	     i++, fstype += strlen(fstype) + 1) {
552 		if (!*fstype)
553 			continue;
554 		if (!fs_is_nodev(fstype))
555 			continue;
556 		err = do_mount_root(root_device_name, fstype, root_mountflags,
557 				    root_mount_data);
558 		if (!err)
559 			break;
560 	}
561 
562 	free_page((unsigned long)fs_names);
563 	return err;
564 }
565 
566 void __init mount_root(void)
567 {
568 #ifdef CONFIG_ROOT_NFS
569 	if (ROOT_DEV == Root_NFS) {
570 		if (!mount_nfs_root())
571 			printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
572 		return;
573 	}
574 #endif
575 #ifdef CONFIG_CIFS_ROOT
576 	if (ROOT_DEV == Root_CIFS) {
577 		if (!mount_cifs_root())
578 			printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
579 		return;
580 	}
581 #endif
582 	if (ROOT_DEV == 0 && root_device_name && root_fs_names) {
583 		if (mount_nodev_root() == 0)
584 			return;
585 	}
586 #ifdef CONFIG_BLOCK
587 	{
588 		int err = create_dev("/dev/root", ROOT_DEV);
589 
590 		if (err < 0)
591 			pr_emerg("Failed to create /dev/root: %d\n", err);
592 		mount_block_root("/dev/root", root_mountflags);
593 	}
594 #endif
595 }
596 
597 /*
598  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
599  */
600 void __init prepare_namespace(void)
601 {
602 	if (root_delay) {
603 		printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
604 		       root_delay);
605 		ssleep(root_delay);
606 	}
607 
608 	/*
609 	 * wait for the known devices to complete their probing
610 	 *
611 	 * Note: this is a potential source of long boot delays.
612 	 * For example, it is not atypical to wait 5 seconds here
613 	 * for the touchpad of a laptop to initialize.
614 	 */
615 	wait_for_device_probe();
616 
617 	md_run_setup();
618 
619 	if (saved_root_name[0]) {
620 		root_device_name = saved_root_name;
621 		if (!strncmp(root_device_name, "mtd", 3) ||
622 		    !strncmp(root_device_name, "ubi", 3)) {
623 			mount_block_root(root_device_name, root_mountflags);
624 			goto out;
625 		}
626 		ROOT_DEV = name_to_dev_t(root_device_name);
627 		if (strncmp(root_device_name, "/dev/", 5) == 0)
628 			root_device_name += 5;
629 	}
630 
631 	if (initrd_load())
632 		goto out;
633 
634 	/* wait for any asynchronous scanning to complete */
635 	if ((ROOT_DEV == 0) && root_wait) {
636 		printk(KERN_INFO "Waiting for root device %s...\n",
637 			saved_root_name);
638 		while (driver_probe_done() != 0 ||
639 			(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
640 			msleep(5);
641 		async_synchronize_full();
642 	}
643 
644 	mount_root();
645 out:
646 	devtmpfs_mount();
647 	init_mount(".", "/", NULL, MS_MOVE, NULL);
648 	init_chroot(".");
649 }
650 
651 static bool is_tmpfs;
652 static int rootfs_init_fs_context(struct fs_context *fc)
653 {
654 	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
655 		return shmem_init_fs_context(fc);
656 
657 	return ramfs_init_fs_context(fc);
658 }
659 
660 struct file_system_type rootfs_fs_type = {
661 	.name		= "rootfs",
662 	.init_fs_context = rootfs_init_fs_context,
663 	.kill_sb	= kill_litter_super,
664 };
665 
666 void __init init_rootfs(void)
667 {
668 	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
669 		(!root_fs_names || strstr(root_fs_names, "tmpfs")))
670 		is_tmpfs = true;
671 }
672