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Linux/init/do_mounts.c

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  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(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;
229 
230                 if (sscanf(name, "%u:%u", &maj, &min) == 2) {
231                         res = MKDEV(maj, min);
232                         if (maj != MAJOR(res) || min != MINOR(res))
233                                 goto fail;
234                 } else {
235                         res = new_decode_dev(simple_strtoul(name, &p, 16));
236                         if (*p)
237                                 goto fail;
238                 }
239                 goto done;
240         }
241 
242         name += 5;
243         res = Root_NFS;
244         if (strcmp(name, "nfs") == 0)
245                 goto done;
246         res = Root_RAM0;
247         if (strcmp(name, "ram") == 0)
248                 goto done;
249 
250         if (strlen(name) > 31)
251                 goto fail;
252         strcpy(s, name);
253         for (p = s; *p; p++)
254                 if (*p == '/')
255                         *p = '!';
256         res = blk_lookup_devt(s, 0);
257         if (res)
258                 goto done;
259 
260         /*
261          * try non-existent, but valid partition, which may only exist
262          * after revalidating the disk, like partitioned md devices
263          */
264         while (p > s && isdigit(p[-1]))
265                 p--;
266         if (p == s || !*p || *p == '')
267                 goto fail;
268 
269         /* try disk name without <part number> */
270         part = simple_strtoul(p, NULL, 10);
271         *p = '\0';
272         res = blk_lookup_devt(s, part);
273         if (res)
274                 goto done;
275 
276         /* try disk name without p<part number> */
277         if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
278                 goto fail;
279         p[-1] = '\0';
280         res = blk_lookup_devt(s, part);
281         if (res)
282                 goto done;
283 
284 fail:
285         return 0;
286 done:
287         return res;
288 }
289 
290 static int __init root_dev_setup(char *line)
291 {
292         strlcpy(saved_root_name, line, sizeof(saved_root_name));
293         return 1;
294 }
295 
296 __setup("root=", root_dev_setup);
297 
298 static int __init rootwait_setup(char *str)
299 {
300         if (*str)
301                 return 0;
302         root_wait = 1;
303         return 1;
304 }
305 
306 __setup("rootwait", rootwait_setup);
307 
308 static char * __initdata root_mount_data;
309 static int __init root_data_setup(char *str)
310 {
311         root_mount_data = str;
312         return 1;
313 }
314 
315 static char * __initdata root_fs_names;
316 static int __init fs_names_setup(char *str)
317 {
318         root_fs_names = str;
319         return 1;
320 }
321 
322 static unsigned int __initdata root_delay;
323 static int __init root_delay_setup(char *str)
324 {
325         root_delay = simple_strtoul(str, NULL, 0);
326         return 1;
327 }
328 
329 __setup("rootflags=", root_data_setup);
330 __setup("rootfstype=", fs_names_setup);
331 __setup("rootdelay=", root_delay_setup);
332 
333 static void __init get_fs_names(char *page)
334 {
335         char *s = page;
336 
337         if (root_fs_names) {
338                 strcpy(page, root_fs_names);
339                 while (*s++) {
340                         if (s[-1] == ',')
341                                 s[-1] = '\0';
342                 }
343         } else {
344                 int len = get_filesystem_list(page);
345                 char *p, *next;
346 
347                 page[len] = '\0';
348                 for (p = page-1; p; p = next) {
349                         next = strchr(++p, '\n');
350                         if (*p++ != '\t')
351                                 continue;
352                         while ((*s++ = *p++) != '\n')
353                                 ;
354                         s[-1] = '\0';
355                 }
356         }
357         *s = '\0';
358 }
359 
360 static int __init do_mount_root(char *name, char *fs, int flags, void *data)
361 {
362         struct super_block *s;
363         int err = sys_mount(name, "/root", fs, flags, data);
364         if (err)
365                 return err;
366 
367         sys_chdir("/root");
368         s = current->fs->pwd.dentry->d_sb;
369         ROOT_DEV = s->s_dev;
370         printk(KERN_INFO
371                "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
372                s->s_type->name,
373                s->s_flags & MS_RDONLY ?  " readonly" : "",
374                MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
375         return 0;
376 }
377 
378 void __init mount_block_root(char *name, int flags)
379 {
380         struct page *page = alloc_page(GFP_KERNEL |
381                                         __GFP_NOTRACK_FALSE_POSITIVE);
382         char *fs_names = page_address(page);
383         char *p;
384 #ifdef CONFIG_BLOCK
385         char b[BDEVNAME_SIZE];
386 #else
387         const char *b = name;
388 #endif
389 
390         get_fs_names(fs_names);
391 retry:
392         for (p = fs_names; *p; p += strlen(p)+1) {
393                 int err = do_mount_root(name, p, flags, root_mount_data);
394                 switch (err) {
395                         case 0:
396                                 goto out;
397                         case -EACCES:
398                         case -EINVAL:
399                                 continue;
400                 }
401                 /*
402                  * Allow the user to distinguish between failed sys_open
403                  * and bad superblock on root device.
404                  * and give them a list of the available devices
405                  */
406 #ifdef CONFIG_BLOCK
407                 __bdevname(ROOT_DEV, b);
408 #endif
409                 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
410                                 root_device_name, b, err);
411                 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
412 
413                 printk_all_partitions();
414 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
415                 printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
416                        "explicit textual name for \"root=\" boot option.\n");
417 #endif
418                 panic("VFS: Unable to mount root fs on %s", b);
419         }
420         if (!(flags & MS_RDONLY)) {
421                 flags |= MS_RDONLY;
422                 goto retry;
423         }
424 
425         printk("List of all partitions:\n");
426         printk_all_partitions();
427         printk("No filesystem could mount root, tried: ");
428         for (p = fs_names; *p; p += strlen(p)+1)
429                 printk(" %s", p);
430         printk("\n");
431 #ifdef CONFIG_BLOCK
432         __bdevname(ROOT_DEV, b);
433 #endif
434         panic("VFS: Unable to mount root fs on %s", b);
435 out:
436         put_page(page);
437 }
438  
439 #ifdef CONFIG_ROOT_NFS
440 
441 #define NFSROOT_TIMEOUT_MIN     5
442 #define NFSROOT_TIMEOUT_MAX     30
443 #define NFSROOT_RETRY_MAX       5
444 
445 static int __init mount_nfs_root(void)
446 {
447         char *root_dev, *root_data;
448         unsigned int timeout;
449         int try, err;
450 
451         err = nfs_root_data(&root_dev, &root_data);
452         if (err != 0)
453                 return 0;
454 
455         /*
456          * The server or network may not be ready, so try several
457          * times.  Stop after a few tries in case the client wants
458          * to fall back to other boot methods.
459          */
460         timeout = NFSROOT_TIMEOUT_MIN;
461         for (try = 1; ; try++) {
462                 err = do_mount_root(root_dev, "nfs",
463                                         root_mountflags, root_data);
464                 if (err == 0)
465                         return 1;
466                 if (try > NFSROOT_RETRY_MAX)
467                         break;
468 
469                 /* Wait, in case the server refused us immediately */
470                 ssleep(timeout);
471                 timeout <<= 1;
472                 if (timeout > NFSROOT_TIMEOUT_MAX)
473                         timeout = NFSROOT_TIMEOUT_MAX;
474         }
475         return 0;
476 }
477 #endif
478 
479 #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
480 void __init change_floppy(char *fmt, ...)
481 {
482         struct termios termios;
483         char buf[80];
484         char c;
485         int fd;
486         va_list args;
487         va_start(args, fmt);
488         vsprintf(buf, fmt, args);
489         va_end(args);
490         fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
491         if (fd >= 0) {
492                 sys_ioctl(fd, FDEJECT, 0);
493                 sys_close(fd);
494         }
495         printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
496         fd = sys_open("/dev/console", O_RDWR, 0);
497         if (fd >= 0) {
498                 sys_ioctl(fd, TCGETS, (long)&termios);
499                 termios.c_lflag &= ~ICANON;
500                 sys_ioctl(fd, TCSETSF, (long)&termios);
501                 sys_read(fd, &c, 1);
502                 termios.c_lflag |= ICANON;
503                 sys_ioctl(fd, TCSETSF, (long)&termios);
504                 sys_close(fd);
505         }
506 }
507 #endif
508 
509 void __init mount_root(void)
510 {
511 #ifdef CONFIG_ROOT_NFS
512         if (ROOT_DEV == Root_NFS) {
513                 if (mount_nfs_root())
514                         return;
515 
516                 printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
517                 ROOT_DEV = Root_FD0;
518         }
519 #endif
520 #ifdef CONFIG_BLK_DEV_FD
521         if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
522                 /* rd_doload is 2 for a dual initrd/ramload setup */
523                 if (rd_doload==2) {
524                         if (rd_load_disk(1)) {
525                                 ROOT_DEV = Root_RAM1;
526                                 root_device_name = NULL;
527                         }
528                 } else
529                         change_floppy("root floppy");
530         }
531 #endif
532 #ifdef CONFIG_BLOCK
533         create_dev("/dev/root", ROOT_DEV);
534         mount_block_root("/dev/root", root_mountflags);
535 #endif
536 }
537 
538 /*
539  * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
540  */
541 void __init prepare_namespace(void)
542 {
543         int is_floppy;
544 
545         if (root_delay) {
546                 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
547                        root_delay);
548                 ssleep(root_delay);
549         }
550 
551         /*
552          * wait for the known devices to complete their probing
553          *
554          * Note: this is a potential source of long boot delays.
555          * For example, it is not atypical to wait 5 seconds here
556          * for the touchpad of a laptop to initialize.
557          */
558         wait_for_device_probe();
559 
560         md_run_setup();
561 
562         if (saved_root_name[0]) {
563                 root_device_name = saved_root_name;
564                 if (!strncmp(root_device_name, "mtd", 3) ||
565                     !strncmp(root_device_name, "ubi", 3)) {
566                         mount_block_root(root_device_name, root_mountflags);
567                         goto out;
568                 }
569                 ROOT_DEV = name_to_dev_t(root_device_name);
570                 if (strncmp(root_device_name, "/dev/", 5) == 0)
571                         root_device_name += 5;
572         }
573 
574         if (initrd_load())
575                 goto out;
576 
577         /* wait for any asynchronous scanning to complete */
578         if ((ROOT_DEV == 0) && root_wait) {
579                 printk(KERN_INFO "Waiting for root device %s...\n",
580                         saved_root_name);
581                 while (driver_probe_done() != 0 ||
582                         (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
583                         msleep(100);
584                 async_synchronize_full();
585         }
586 
587         is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
588 
589         if (is_floppy && rd_doload && rd_load_disk(0))
590                 ROOT_DEV = Root_RAM0;
591 
592         mount_root();
593 out:
594         devtmpfs_mount("dev");
595         sys_mount(".", "/", NULL, MS_MOVE, NULL);
596         sys_chroot(".");
597 }
598 
599 static bool is_tmpfs;
600 static struct dentry *rootfs_mount(struct file_system_type *fs_type,
601         int flags, const char *dev_name, void *data)
602 {
603         static unsigned long once;
604         void *fill = ramfs_fill_super;
605 
606         if (test_and_set_bit(0, &once))
607                 return ERR_PTR(-ENODEV);
608 
609         if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
610                 fill = shmem_fill_super;
611 
612         return mount_nodev(fs_type, flags, data, fill);
613 }
614 
615 static struct file_system_type rootfs_fs_type = {
616         .name           = "rootfs",
617         .mount          = rootfs_mount,
618         .kill_sb        = kill_litter_super,
619 };
620 
621 int __init init_rootfs(void)
622 {
623         int err = register_filesystem(&rootfs_fs_type);
624 
625         if (err)
626                 return err;
627 
628         if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
629                 (!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
630                 err = shmem_init();
631                 is_tmpfs = true;
632         } else {
633                 err = init_ramfs_fs();
634         }
635 
636         if (err)
637                 unregister_filesystem(&rootfs_fs_type);
638 
639         return err;
640 }
641 

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