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
31 int root_mountflags = MS_RDONLY | MS_SILENT;
32 static char __initdata saved_root_name[64];
33 static int root_wait;
34
35 dev_t ROOT_DEV;
36
load_ramdisk(char * str)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
readonly(char * str)44 static int __init readonly(char *str)
45 {
46 if (*str)
47 return 0;
48 root_mountflags |= MS_RDONLY;
49 return 1;
50 }
51
readwrite(char * str)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
root_dev_setup(char * line)63 static 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
rootwait_setup(char * str)71 static 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
rootwait_timeout_setup(char * str)81 static 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
97 ignore:
98 /* Fallback to indefinite wait */
99 root_wait = -1;
100
101 return 1;
102 }
103
104 __setup("rootwait=", rootwait_timeout_setup);
105
106 static char * __initdata root_mount_data;
root_data_setup(char * str)107 static int __init root_data_setup(char *str)
108 {
109 root_mount_data = str;
110 return 1;
111 }
112
113 static char * __initdata root_fs_names;
fs_names_setup(char * str)114 static int __init fs_names_setup(char *str)
115 {
116 root_fs_names = str;
117 return 1;
118 }
119
120 static unsigned int __initdata root_delay;
root_delay_setup(char * str)121 static 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 */
split_fs_names(char * page,size_t size)132 static 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
do_mount_root(const char * name,const char * fs,const int flags,const void * data)148 static 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
179 out:
180 if (p)
181 put_page(p);
182 return ret;
183 }
184
mount_root_generic(char * name,char * pretty_name,int flags)185 void __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);
199 retry:
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 continue;
212 }
213 /*
214 * Allow the user to distinguish between failed sys_open
215 * and bad superblock on root device.
216 * and give them a list of the available devices
217 */
218 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
219 pretty_name, b, err);
220 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
221 printk_all_partitions();
222
223 if (root_fs_names)
224 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
225 if (!num_fs)
226 pr_err("Can't find any bdev filesystem to be used for mount!\n");
227 else {
228 pr_err("List of all bdev filesystems:\n");
229 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
230 pr_err(" %s", p);
231 pr_err("\n");
232 }
233
234 panic("VFS: Unable to mount root fs on %s", b);
235 }
236 if (!(flags & SB_RDONLY)) {
237 flags |= SB_RDONLY;
238 goto retry;
239 }
240
241 printk("List of all partitions:\n");
242 printk_all_partitions();
243 printk("No filesystem could mount root, tried: ");
244 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
245 printk(" %s", p);
246 printk("\n");
247 panic("VFS: Unable to mount root fs on %s", b);
248 out:
249 put_page(page);
250 }
251
252 #ifdef CONFIG_ROOT_NFS
253
254 #define NFSROOT_TIMEOUT_MIN 5
255 #define NFSROOT_TIMEOUT_MAX 30
256 #define NFSROOT_RETRY_MAX 5
257
mount_nfs_root(void)258 static void __init mount_nfs_root(void)
259 {
260 char *root_dev, *root_data;
261 unsigned int timeout;
262 int try;
263
264 if (nfs_root_data(&root_dev, &root_data))
265 goto fail;
266
267 /*
268 * The server or network may not be ready, so try several
269 * times. Stop after a few tries in case the client wants
270 * to fall back to other boot methods.
271 */
272 timeout = NFSROOT_TIMEOUT_MIN;
273 for (try = 1; ; try++) {
274 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
275 return;
276 if (try > NFSROOT_RETRY_MAX)
277 break;
278
279 /* Wait, in case the server refused us immediately */
280 ssleep(timeout);
281 timeout <<= 1;
282 if (timeout > NFSROOT_TIMEOUT_MAX)
283 timeout = NFSROOT_TIMEOUT_MAX;
284 }
285 fail:
286 pr_err("VFS: Unable to mount root fs via NFS.\n");
287 }
288 #else
mount_nfs_root(void)289 static inline void mount_nfs_root(void)
290 {
291 }
292 #endif /* CONFIG_ROOT_NFS */
293
294 #ifdef CONFIG_CIFS_ROOT
295
296 #define CIFSROOT_TIMEOUT_MIN 5
297 #define CIFSROOT_TIMEOUT_MAX 30
298 #define CIFSROOT_RETRY_MAX 5
299
mount_cifs_root(void)300 static void __init mount_cifs_root(void)
301 {
302 char *root_dev, *root_data;
303 unsigned int timeout;
304 int try;
305
306 if (cifs_root_data(&root_dev, &root_data))
307 goto fail;
308
309 timeout = CIFSROOT_TIMEOUT_MIN;
310 for (try = 1; ; try++) {
311 if (!do_mount_root(root_dev, "cifs", root_mountflags,
312 root_data))
313 return;
314 if (try > CIFSROOT_RETRY_MAX)
315 break;
316
317 ssleep(timeout);
318 timeout <<= 1;
319 if (timeout > CIFSROOT_TIMEOUT_MAX)
320 timeout = CIFSROOT_TIMEOUT_MAX;
321 }
322 fail:
323 pr_err("VFS: Unable to mount root fs via SMB.\n");
324 }
325 #else
mount_cifs_root(void)326 static inline void mount_cifs_root(void)
327 {
328 }
329 #endif /* CONFIG_CIFS_ROOT */
330
fs_is_nodev(char * fstype)331 static bool __init fs_is_nodev(char *fstype)
332 {
333 struct file_system_type *fs = get_fs_type(fstype);
334 bool ret = false;
335
336 if (fs) {
337 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
338 put_filesystem(fs);
339 }
340
341 return ret;
342 }
343
mount_nodev_root(char * root_device_name)344 static int __init mount_nodev_root(char *root_device_name)
345 {
346 char *fs_names, *fstype;
347 int err = -EINVAL;
348 int num_fs, i;
349
350 fs_names = (void *)__get_free_page(GFP_KERNEL);
351 if (!fs_names)
352 return -EINVAL;
353 num_fs = split_fs_names(fs_names, PAGE_SIZE);
354
355 for (i = 0, fstype = fs_names; i < num_fs;
356 i++, fstype += strlen(fstype) + 1) {
357 if (!*fstype)
358 continue;
359 if (!fs_is_nodev(fstype))
360 continue;
361 err = do_mount_root(root_device_name, fstype, root_mountflags,
362 root_mount_data);
363 if (!err)
364 break;
365 }
366
367 free_page((unsigned long)fs_names);
368 return err;
369 }
370
371 #ifdef CONFIG_BLOCK
mount_block_root(char * root_device_name)372 static void __init mount_block_root(char *root_device_name)
373 {
374 int err = create_dev("/dev/root", ROOT_DEV);
375
376 if (err < 0)
377 pr_emerg("Failed to create /dev/root: %d\n", err);
378 mount_root_generic("/dev/root", root_device_name, root_mountflags);
379 }
380 #else
mount_block_root(char * root_device_name)381 static inline void mount_block_root(char *root_device_name)
382 {
383 }
384 #endif /* CONFIG_BLOCK */
385
mount_root(char * root_device_name)386 void __init mount_root(char *root_device_name)
387 {
388 switch (ROOT_DEV) {
389 case Root_NFS:
390 mount_nfs_root();
391 break;
392 case Root_CIFS:
393 mount_cifs_root();
394 break;
395 case Root_Generic:
396 mount_root_generic(root_device_name, root_device_name,
397 root_mountflags);
398 break;
399 case 0:
400 if (root_device_name && root_fs_names &&
401 mount_nodev_root(root_device_name) == 0)
402 break;
403 fallthrough;
404 default:
405 mount_block_root(root_device_name);
406 break;
407 }
408 }
409
410 /* wait for any asynchronous scanning to complete */
wait_for_root(char * root_device_name)411 static void __init wait_for_root(char *root_device_name)
412 {
413 ktime_t end;
414
415 if (ROOT_DEV != 0)
416 return;
417
418 pr_info("Waiting for root device %s...\n", root_device_name);
419
420 end = ktime_add_ms(ktime_get_raw(), root_wait);
421
422 while (!driver_probe_done() ||
423 early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
424 msleep(5);
425 if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
426 break;
427 }
428
429 async_synchronize_full();
430
431 }
432
parse_root_device(char * root_device_name)433 static dev_t __init parse_root_device(char *root_device_name)
434 {
435 int error;
436 dev_t dev;
437
438 if (!strncmp(root_device_name, "mtd", 3) ||
439 !strncmp(root_device_name, "ubi", 3))
440 return Root_Generic;
441 if (strcmp(root_device_name, "/dev/nfs") == 0)
442 return Root_NFS;
443 if (strcmp(root_device_name, "/dev/cifs") == 0)
444 return Root_CIFS;
445 if (strcmp(root_device_name, "/dev/ram") == 0)
446 return Root_RAM0;
447
448 error = early_lookup_bdev(root_device_name, &dev);
449 if (error) {
450 if (error == -EINVAL && root_wait) {
451 pr_err("Disabling rootwait; root= is invalid.\n");
452 root_wait = 0;
453 }
454 return 0;
455 }
456 return dev;
457 }
458
459 /*
460 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
461 */
prepare_namespace(void)462 void __init prepare_namespace(void)
463 {
464 if (root_delay) {
465 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
466 root_delay);
467 ssleep(root_delay);
468 }
469
470 /*
471 * wait for the known devices to complete their probing
472 *
473 * Note: this is a potential source of long boot delays.
474 * For example, it is not atypical to wait 5 seconds here
475 * for the touchpad of a laptop to initialize.
476 */
477 wait_for_device_probe();
478
479 md_run_setup();
480
481 if (saved_root_name[0])
482 ROOT_DEV = parse_root_device(saved_root_name);
483
484 if (initrd_load(saved_root_name))
485 goto out;
486
487 if (root_wait)
488 wait_for_root(saved_root_name);
489 mount_root(saved_root_name);
490 out:
491 devtmpfs_mount();
492 init_mount(".", "/", NULL, MS_MOVE, NULL);
493 init_chroot(".");
494 }
495
496 static bool is_tmpfs;
rootfs_init_fs_context(struct fs_context * fc)497 static int rootfs_init_fs_context(struct fs_context *fc)
498 {
499 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
500 return shmem_init_fs_context(fc);
501
502 return ramfs_init_fs_context(fc);
503 }
504
505 struct file_system_type rootfs_fs_type = {
506 .name = "rootfs",
507 .init_fs_context = rootfs_init_fs_context,
508 .kill_sb = kill_litter_super,
509 };
510
init_rootfs(void)511 void __init init_rootfs(void)
512 {
513 if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
514 (!root_fs_names || strstr(root_fs_names, "tmpfs")))
515 is_tmpfs = true;
516 }
517
