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Linux/init/do_mounts.c

  1 /*
  2  * Many of the syscalls used in this file expect some of the arguments
  3  * to be __user pointers not __kernel pointers.  To limit the sparse
  4  * noise, turn off sparse checking for this file.
  5  */
  6 #ifdef __CHECKER__
  7 #undef __CHECKER__
  8 #warning "Sparse checking disabled for this file"
  9 #endif
 10 
 11 #include <linux/module.h>
 12 #include <linux/sched.h>
 13 #include <linux/ctype.h>
 14 #include <linux/fd.h>
 15 #include <linux/tty.h>
 16 #include <linux/suspend.h>
 17 #include <linux/root_dev.h>
 18 #include <linux/security.h>
 19 #include <linux/delay.h>
 20 #include <linux/genhd.h>
 21 #include <linux/mount.h>
 22 #include <linux/device.h>
 23 #include <linux/init.h>
 24 #include <linux/fs.h>
 25 #include <linux/initrd.h>
 26 #include <linux/async.h>
 27 #include <linux/fs_struct.h>
 28 #include <linux/slab.h>
 29 #include <linux/ramfs.h>
 30 #include <linux/shmem_fs.h>
 31 
 32 #include <linux/nfs_fs.h>
 33 #include <linux/nfs_fs_sb.h>
 34 #include <linux/nfs_mount.h>
 35 
 36 #include "do_mounts.h"
 37 
 38 int __initdata rd_doload;       /* 1 = load RAM disk, 0 = don't load */
 39 
 40 int root_mountflags = MS_RDONLY | MS_SILENT;
 41 static char * __initdata root_device_name;
 42 static char __initdata saved_root_name[64];
 43 static int root_wait;
 44 
 45 dev_t ROOT_DEV;
 46 
 47 static int __init load_ramdisk(char *str)
 48 {
 49         rd_doload = simple_strtol(str,NULL,0) & 3;
 50         return 1;
 51 }
 52 __setup("load_ramdisk=", load_ramdisk);
 53 
 54 static int __init readonly(char *str)
 55 {
 56         if (*str)
 57                 return 0;
 58         root_mountflags |= MS_RDONLY;
 59         return 1;
 60 }
 61 
 62 static int __init readwrite(char *str)
 63 {
 64         if (*str)
 65                 return 0;
 66         root_mountflags &= ~MS_RDONLY;
 67         return 1;
 68 }
 69 
 70 __setup("ro", readonly);
 71 __setup("rw", readwrite);
 72 
 73 #ifdef CONFIG_BLOCK
 74 struct uuidcmp {
 75         const char *uuid;
 76         int len;
 77 };
 78 
 79 /**
 80  * match_dev_by_uuid - callback for finding a partition using its uuid
 81  * @dev:        device passed in by the caller
 82  * @data:       opaque pointer to the desired struct uuidcmp to match
 83  *
 84  * Returns 1 if the device matches, and 0 otherwise.
 85  */
 86 static int match_dev_by_uuid(struct device *dev, const void *data)
 87 {
 88         const struct uuidcmp *cmp = data;
 89         struct hd_struct *part = dev_to_part(dev);
 90 
 91         if (!part->info)
 92                 goto no_match;
 93 
 94         if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
 95                 goto no_match;
 96 
 97         return 1;
 98 no_match:
 99         return 0;
100 }
101 
102 
103 /**
104  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
105  * @uuid_str:   char array containing ascii UUID
106  *
107  * The function will return the first partition which contains a matching
108  * UUID value in its partition_meta_info struct.  This does not search
109  * by filesystem UUIDs.
110  *
111  * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
112  * extracted and used as an offset from the partition identified by the UUID.
113  *
114  * Returns the matching dev_t on success or 0 on failure.
115  */
116 static dev_t devt_from_partuuid(const char *uuid_str)
117 {
118         dev_t res = 0;
119         struct uuidcmp cmp;
120         struct device *dev = NULL;
121         struct gendisk *disk;
122         struct hd_struct *part;
123         int offset = 0;
124         bool clear_root_wait = false;
125         char *slash;
126 
127         cmp.uuid = uuid_str;
128 
129         slash = strchr(uuid_str, '/');
130         /* Check for optional partition number offset attributes. */
131         if (slash) {
132                 char c = 0;
133                 /* Explicitly fail on poor PARTUUID syntax. */
134                 if (sscanf(slash + 1,
135                            "PARTNROFF=%d%c", &offset, &c) != 1) {
136                         clear_root_wait = true;
137                         goto done;
138                 }
139                 cmp.len = slash - uuid_str;
140         } else {
141                 cmp.len = strlen(uuid_str);
142         }
143 
144         if (!cmp.len) {
145                 clear_root_wait = true;
146                 goto done;
147         }
148 
149         dev = class_find_device(&block_class, NULL, &cmp,
150                                 &match_dev_by_uuid);
151         if (!dev)
152                 goto done;
153 
154         res = dev->devt;
155 
156         /* Attempt to find the partition by offset. */
157         if (!offset)
158                 goto no_offset;
159 
160         res = 0;
161         disk = part_to_disk(dev_to_part(dev));
162         part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
163         if (part) {
164                 res = part_devt(part);
165                 put_device(part_to_dev(part));
166         }
167 
168 no_offset:
169         put_device(dev);
170 done:
171         if (clear_root_wait) {
172                 pr_err("VFS: PARTUUID= is invalid.\n"
173                        "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
174                 if (root_wait)
175                         pr_err("Disabling rootwait; root= is invalid.\n");
176                 root_wait = 0;
177         }
178         return res;
179 }
180 #endif
181 
182 /*
183  *      Convert a name into device number.  We accept the following variants:
184  *
185  *      1) <hex_major><hex_minor> device number in hexadecimal represents itself
186  *         no leading 0x, for example b302.
187  *      2) /dev/nfs represents Root_NFS (0xff)
188  *      3) /dev/<disk_name> represents the device number of disk
189  *      4) /dev/<disk_name><decimal> represents the device number
190  *         of partition - device number of disk plus the partition number
191  *      5) /dev/<disk_name>p<decimal> - same as the above, that form is
192  *         used when disk name of partitioned disk ends on a digit.
193  *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
194  *         unique id of a partition if the partition table provides it.
195  *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
196  *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
197  *         filled hex representation of the 32-bit "NT disk signature", and PP
198  *         is a zero-filled hex representation of the 1-based partition number.
199  *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
200  *         a partition with a known unique id.
201  *      8) <major>:<minor> major and minor number of the device separated by
202  *         a colon.
203  *
204  *      If name doesn't have fall into the categories above, we return (0,0).
205  *      block_class is used to check if something is a disk name. If the disk
206  *      name contains slashes, the device name has them replaced with
207  *      bangs.
208  */
209 
210 dev_t name_to_dev_t(const char *name)
211 {
212         char s[32];
213         char *p;
214         dev_t res = 0;
215         int part;
216 
217 #ifdef CONFIG_BLOCK
218         if (strncmp(name, "PARTUUID=", 9) == 0) {
219                 name += 9;
220                 res = devt_from_partuuid(name);
221                 if (!res)
222                         goto fail;
223                 goto done;
224         }
225 #endif
226 
227         if (strncmp(name, "/dev/", 5) != 0) {
228                 unsigned maj, min, offset;
229                 char dummy;
230 
231                 if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
232                     (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
233                         res = MKDEV(maj, min);
234                         if (maj != MAJOR(res) || min != MINOR(res))
235                                 goto fail;
236                 } else {
237                         res = new_decode_dev(simple_strtoul(name, &p, 16));
238                         if (*p)
239                                 goto fail;
240                 }
241                 goto done;
242         }
243 
244         name += 5;
245         res = Root_NFS;
246         if (strcmp(name, "nfs") == 0)
247                 goto done;
248         res = Root_RAM0;
249         if (strcmp(name, "ram") == 0)
250                 goto done;
251 
252         if (strlen(name) > 31)
253                 goto fail;
254         strcpy(s, name);
255         for (p = s; *p; p++)
256                 if (*p == '/')
257                         *p = '!';
258         res = blk_lookup_devt(s, 0);
259         if (res)
260                 goto done;
261 
262         /*
263          * try non-existent, but valid partition, which may only exist
264          * after revalidating the disk, like partitioned md devices
265          */
266         while (p > s && isdigit(p[-1]))
267                 p--;
268         if (p == s || !*p || *p == '')
269                 goto fail;
270 
271         /* try disk name without <part number> */
272         part = simple_strtoul(p, NULL, 10);
273         *p = '\0';
274         res = blk_lookup_devt(s, part);
275         if (res)
276                 goto done;
277 
278         /* try disk name without p<part number> */
279         if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
280                 goto fail;
281         p[-1] = '\0';
282         res = blk_lookup_devt(s, part);
283         if (res)
284                 goto done;
285 
286 fail:
287         return 0;
288 done:
289         return res;
290 }
291 EXPORT_SYMBOL_GPL(name_to_dev_t);
292 
293 static int __init root_dev_setup(char *line)
294 {
295         strlcpy(saved_root_name, line, sizeof(saved_root_name));
296         return 1;
297 }
298 
299 __setup("root=", root_dev_setup);
300 
301 static int __init rootwait_setup(char *str)
302 {
303         if (*str)
304                 return 0;
305         root_wait = 1;
306         return 1;
307 }
308 
309 __setup("rootwait", rootwait_setup);
310 
311 static char * __initdata root_mount_data;
312 static int __init root_data_setup(char *str)
313 {
314         root_mount_data = str;
315         return 1;
316 }
317 
318 static char * __initdata root_fs_names;
319 static int __init fs_names_setup(char *str)
320 {
321         root_fs_names = str;
322         return 1;
323 }
324 
325 static unsigned int __initdata root_delay;
326 static int __init root_delay_setup(char *str)
327 {
328         root_delay = simple_strtoul(str, NULL, 0);
329         return 1;
330 }
331 
332 __setup("rootflags=", root_data_setup);
333 __setup("rootfstype=", fs_names_setup);
334 __setup("rootdelay=", root_delay_setup);
335 
336 static void __init get_fs_names(char *page)
337 {
338         char *s = page;
339 
340         if (root_fs_names) {
341                 strcpy(page, root_fs_names);
342                 while (*s++) {
343                         if (s[-1] == ',')
344                                 s[-1] = '\0';
345                 }
346         } else {
347                 int len = get_filesystem_list(page);
348                 char *p, *next;
349 
350                 page[len] = '\0';
351                 for (p = page-1; p; p = next) {
352                         next = strchr(++p, '\n');
353                         if (*p++ != '\t')
354                                 continue;
355                         while ((*s++ = *p++) != '\n')
356                                 ;
357                         s[-1] = '\0';
358                 }
359         }
360         *s = '\0';
361 }
362 
363 static int __init do_mount_root(char *name, char *fs, int flags, void *data)
364 {
365         struct super_block *s;
366         int err = sys_mount(name, "/root", fs, flags, data);
367         if (err)
368                 return err;
369 
370         sys_chdir("/root");
371         s = current->fs->pwd.dentry->d_sb;
372         ROOT_DEV = s->s_dev;
373         printk(KERN_INFO
374                "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
375                s->s_type->name,
376                s->s_flags & MS_RDONLY ?  " readonly" : "",
377                MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
378         return 0;
379 }
380 
381 void __init mount_block_root(char *name, int flags)
382 {
383         struct page *page = alloc_page(GFP_KERNEL |
384                                         __GFP_NOTRACK_FALSE_POSITIVE);
385         char *fs_names = page_address(page);
386         char *p;
387 #ifdef CONFIG_BLOCK
388         char b[BDEVNAME_SIZE];
389 #else
390         const char *b = name;
391 #endif
392 
393         get_fs_names(fs_names);
394 retry:
395         for (p = fs_names; *p; p += strlen(p)+1) {
396                 int err = do_mount_root(name, p, flags, root_mount_data);
397                 switch (err) {
398                         case 0:
399                                 goto out;
400                         case -EACCES:
401                         case -EINVAL:
402                                 continue;
403                 }
404                 /*
405                  * Allow the user to distinguish between failed sys_open
406                  * and bad superblock on root device.
407                  * and give them a list of the available devices
408                  */
409 #ifdef CONFIG_BLOCK
410                 __bdevname(ROOT_DEV, b);
411 #endif
412                 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
413                                 root_device_name, b, err);
414                 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
415 
416                 printk_all_partitions();
417 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
418                 printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
419                        "explicit textual name for \"root=\" boot option.\n");
420 #endif
421                 panic("VFS: Unable to mount root fs on %s", b);
422         }
423         if (!(flags & MS_RDONLY)) {
424                 flags |= MS_RDONLY;
425                 goto retry;
426         }
427 
428         printk("List of all partitions:\n");
429         printk_all_partitions();
430         printk("No filesystem could mount root, tried: ");
431         for (p = fs_names; *p; p += strlen(p)+1)
432                 printk(" %s", p);
433         printk("\n");
434 #ifdef CONFIG_BLOCK
435         __bdevname(ROOT_DEV, b);
436 #endif
437         panic("VFS: Unable to mount root fs on %s", b);
438 out:
439         put_page(page);
440 }
441  
442 #ifdef CONFIG_ROOT_NFS
443 
444 #define NFSROOT_TIMEOUT_MIN     5
445 #define NFSROOT_TIMEOUT_MAX     30
446 #define NFSROOT_RETRY_MAX       5
447 
448 static int __init mount_nfs_root(void)
449 {
450         char *root_dev, *root_data;
451         unsigned int timeout;
452         int try, err;
453 
454         err = nfs_root_data(&root_dev, &root_data);
455         if (err != 0)
456                 return 0;
457 
458         /*
459          * The server or network may not be ready, so try several
460          * times.  Stop after a few tries in case the client wants
461          * to fall back to other boot methods.
462          */
463         timeout = NFSROOT_TIMEOUT_MIN;
464         for (try = 1; ; try++) {
465                 err = do_mount_root(root_dev, "nfs",
466                                         root_mountflags, root_data);
467                 if (err == 0)
468                         return 1;
469                 if (try > NFSROOT_RETRY_MAX)
470                         break;
471 
472                 /* Wait, in case the server refused us immediately */
473                 ssleep(timeout);
474                 timeout <<= 1;
475                 if (timeout > NFSROOT_TIMEOUT_MAX)
476                         timeout = NFSROOT_TIMEOUT_MAX;
477         }
478         return 0;
479 }
480 #endif
481 
482 #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
483 void __init change_floppy(char *fmt, ...)
484 {
485         struct termios termios;
486         char buf[80];
487         char c;
488         int fd;
489         va_list args;
490         va_start(args, fmt);
491         vsprintf(buf, fmt, args);
492         va_end(args);
493         fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
494         if (fd >= 0) {
495                 sys_ioctl(fd, FDEJECT, 0);
496                 sys_close(fd);
497         }
498         printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
499         fd = sys_open("/dev/console", O_RDWR, 0);
500         if (fd >= 0) {
501                 sys_ioctl(fd, TCGETS, (long)&termios);
502                 termios.c_lflag &= ~ICANON;
503                 sys_ioctl(fd, TCSETSF, (long)&termios);
504                 sys_read(fd, &c, 1);
505                 termios.c_lflag |= ICANON;
506                 sys_ioctl(fd, TCSETSF, (long)&termios);
507                 sys_close(fd);
508         }
509 }
510 #endif
511 
512 void __init mount_root(void)
513 {
514 #ifdef CONFIG_ROOT_NFS
515         if (ROOT_DEV == Root_NFS) {
516                 if (mount_nfs_root())
517                         return;
518 
519                 printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
520                 ROOT_DEV = Root_FD0;
521         }
522 #endif
523 #ifdef CONFIG_BLK_DEV_FD
524         if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
525                 /* rd_doload is 2 for a dual initrd/ramload setup */
526                 if (rd_doload==2) {
527                         if (rd_load_disk(1)) {
528                                 ROOT_DEV = Root_RAM1;
529                                 root_device_name = NULL;
530                         }
531                 } else
532                         change_floppy("root floppy");
533         }
534 #endif
535 #ifdef CONFIG_BLOCK
536         {
537                 int err = create_dev("/dev/root", ROOT_DEV);
538 
539                 if (err < 0)
540                         pr_emerg("Failed to create /dev/root: %d\n", err);
541                 mount_block_root("/dev/root", root_mountflags);
542         }
543 #endif
544 }
545 
546 /*
547  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
548  */
549 void __init prepare_namespace(void)
550 {
551         int is_floppy;
552 
553         if (root_delay) {
554                 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
555                        root_delay);
556                 ssleep(root_delay);
557         }
558 
559         /*
560          * wait for the known devices to complete their probing
561          *
562          * Note: this is a potential source of long boot delays.
563          * For example, it is not atypical to wait 5 seconds here
564          * for the touchpad of a laptop to initialize.
565          */
566         wait_for_device_probe();
567 
568         md_run_setup();
569 
570         if (saved_root_name[0]) {
571                 root_device_name = saved_root_name;
572                 if (!strncmp(root_device_name, "mtd", 3) ||
573                     !strncmp(root_device_name, "ubi", 3)) {
574                         mount_block_root(root_device_name, root_mountflags);
575                         goto out;
576                 }
577                 ROOT_DEV = name_to_dev_t(root_device_name);
578                 if (strncmp(root_device_name, "/dev/", 5) == 0)
579                         root_device_name += 5;
580         }
581 
582         if (initrd_load())
583                 goto out;
584 
585         /* wait for any asynchronous scanning to complete */
586         if ((ROOT_DEV == 0) && root_wait) {
587                 printk(KERN_INFO "Waiting for root device %s...\n",
588                         saved_root_name);
589                 while (driver_probe_done() != 0 ||
590                         (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
591                         msleep(5);
592                 async_synchronize_full();
593         }
594 
595         is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
596 
597         if (is_floppy && rd_doload && rd_load_disk(0))
598                 ROOT_DEV = Root_RAM0;
599 
600         mount_root();
601 out:
602         devtmpfs_mount("dev");
603         sys_mount(".", "/", NULL, MS_MOVE, NULL);
604         sys_chroot(".");
605 }
606 
607 static bool is_tmpfs;
608 static struct dentry *rootfs_mount(struct file_system_type *fs_type,
609         int flags, const char *dev_name, void *data)
610 {
611         static unsigned long once;
612         void *fill = ramfs_fill_super;
613 
614         if (test_and_set_bit(0, &once))
615                 return ERR_PTR(-ENODEV);
616 
617         if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
618                 fill = shmem_fill_super;
619 
620         return mount_nodev(fs_type, flags, data, fill);
621 }
622 
623 static struct file_system_type rootfs_fs_type = {
624         .name           = "rootfs",
625         .mount          = rootfs_mount,
626         .kill_sb        = kill_litter_super,
627 };
628 
629 int __init init_rootfs(void)
630 {
631         int err = register_filesystem(&rootfs_fs_type);
632 
633         if (err)
634                 return err;
635 
636         if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
637                 (!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
638                 err = shmem_init();
639                 is_tmpfs = true;
640         } else {
641                 err = init_ramfs_fs();
642         }
643 
644         if (err)
645                 unregister_filesystem(&rootfs_fs_type);
646 
647         return err;
648 }
649 

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