// SPDX-License-Identifier: GPL-2.0-only

/*

* Code for looking up block devices in the early boot code before mounting the

* root file system.

*/

#include <linux/blkdev.h>

#include <linux/ctype.h>

struct uuidcmp {

const char *uuid;

int len;

};

/**

* match_dev_by_uuid - callback for finding a partition using its uuid

* @dev: device passed in by the caller

* @data: opaque pointer to the desired struct uuidcmp to match

*

* Returns 1 if the device matches, and 0 otherwise.

*/

static int __init match_dev_by_uuid(struct device *dev, const void *data)

{

struct block_device *bdev = dev_to_bdev(dev);

const struct uuidcmp *cmp = data;

if (!bdev->bd_meta_info ||

strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))

return 0;

return 1;

}

/**

* devt_from_partuuid - looks up the dev_t of a partition by its UUID

* @uuid_str: char array containing ascii UUID

* @devt: dev_t result

*

* The function will return the first partition which contains a matching

* UUID value in its partition_meta_info struct. This does not search

* by filesystem UUIDs.

*

* If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be

* extracted and used as an offset from the partition identified by the UUID.

*

* Returns 0 on success or a negative error code on failure.

*/

static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt)

{

struct uuidcmp cmp;

struct device *dev = NULL;

int offset = 0;

char *slash;

cmp.uuid = uuid_str;

slash = strchr(uuid_str, '/');

/* Check for optional partition number offset attributes. */

if (slash) {

char c = 0;

/* Explicitly fail on poor PARTUUID syntax. */

if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)

goto out_invalid;

cmp.len = slash - uuid_str;

} else {

cmp.len = strlen(uuid_str);

}

if (!cmp.len)

goto out_invalid;

dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);

if (!dev)

return -ENODEV;

if (offset) {

/*

* Attempt to find the requested partition by adding an offset

* to the partition number found by UUID.

*/

*devt = part_devt(dev_to_disk(dev),

bdev_partno(dev_to_bdev(dev)) + offset);

} else {

*devt = dev->devt;

}

put_device(dev);

return 0;

out_invalid:

pr_err("VFS: PARTUUID= is invalid.\n"

"Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");

return -EINVAL;

}

/**

* match_dev_by_label - callback for finding a partition using its label

* @dev: device passed in by the caller

* @data: opaque pointer to the label to match

*

* Returns 1 if the device matches, and 0 otherwise.

*/

static int __init match_dev_by_label(struct device *dev, const void *data)

{

struct block_device *bdev = dev_to_bdev(dev);

const char *label = data;

if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))

return 0;

return 1;

}

static int __init devt_from_partlabel(const char *label, dev_t *devt)

{

struct device *dev;

dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);

if (!dev)

return -ENODEV;

*devt = dev->devt;

put_device(dev);

return 0;

}

static dev_t __init blk_lookup_devt(const char *name, int partno)

{

dev_t devt = MKDEV(0, 0);

struct class_dev_iter iter;

struct device *dev;

class_dev_iter_init(&iter, &block_class, NULL, &disk_type);

while ((dev = class_dev_iter_next(&iter))) {

struct gendisk *disk = dev_to_disk(dev);

if (strcmp(dev_name(dev), name))

continue;

if (partno < disk->minors) {

/* We need to return the right devno, even

* if the partition doesn't exist yet.

*/

devt = MKDEV(MAJOR(dev->devt),

MINOR(dev->devt) + partno);

} else {

devt = part_devt(disk, partno);

if (devt)

break;

}

}

class_dev_iter_exit(&iter);

return devt;

}

static int __init devt_from_devname(const char *name, dev_t *devt)

{

int part;

char s[32];

char *p;

if (strlen(name) > 31)

return -EINVAL;

strcpy(s, name);

for (p = s; *p; p++) {

if (*p == '/')

*p = '!';

}

*devt = blk_lookup_devt(s, 0);

if (*devt)

return 0;

/*

* Try non-existent, but valid partition, which may only exist after

* opening the device, like partitioned md devices.

*/

while (p > s && isdigit(p[-1]))

p--;

if (p == s || !*p || *p == '0')

return -ENODEV;

/* try disk name without <part number> */

part = simple_strtoul(p, NULL, 10);

*p = '\0';

*devt = blk_lookup_devt(s, part);

if (*devt)

return 0;

/* try disk name without p<part number> */

if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')

return -ENODEV;

p[-1] = '\0';

*devt = blk_lookup_devt(s, part);

if (*devt)

return 0;

return -ENODEV;

}

static int __init devt_from_devnum(const char *name, dev_t *devt)

{

unsigned maj, min, offset;

char *p, dummy;

if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||

sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {

*devt = MKDEV(maj, min);

if (maj != MAJOR(*devt) || min != MINOR(*devt))

return -EINVAL;

} else {

*devt = new_decode_dev(simple_strtoul(name, &p, 16));

if (*p)

return -EINVAL;

}

return 0;

}

/*

* Convert a name into device number. We accept the following variants:

*

* 1) <hex_major><hex_minor> device number in hexadecimal represents itself

* no leading 0x, for example b302.

* 3) /dev/<disk_name> represents the device number of disk

* 4) /dev/<disk_name><decimal> represents the device number

* of partition - device number of disk plus the partition number

* 5) /dev/<disk_name>p<decimal> - same as the above, that form is

* used when disk name of partitioned disk ends on a digit.

* 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the

* unique id of a partition if the partition table provides it.

* The UUID may be either an EFI/GPT UUID, or refer to an MSDOS

* partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-

* filled hex representation of the 32-bit "NT disk signature", and PP

* is a zero-filled hex representation of the 1-based partition number.

* 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to

* a partition with a known unique id.

* 8) <major>:<minor> major and minor number of the device separated by

* a colon.

* 9) PARTLABEL=<name> with name being the GPT partition label.

* MSDOS partitions do not support labels!

*

* If name doesn't have fall into the categories above, we return (0,0).

* block_class is used to check if something is a disk name. If the disk

* name contains slashes, the device name has them replaced with

* bangs.

*/

int __init early_lookup_bdev(const char *name, dev_t *devt)

{

if (strncmp(name, "PARTUUID=", 9) == 0)

return devt_from_partuuid(name + 9, devt);

if (strncmp(name, "PARTLABEL=", 10) == 0)

return devt_from_partlabel(name + 10, devt);

if (strncmp(name, "/dev/", 5) == 0)

return devt_from_devname(name + 5, devt);

return devt_from_devnum(name, devt);

}

static char __init *bdevt_str(dev_t devt, char *buf)

{

if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {

char tbuf[BDEVT_SIZE];

snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));

snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);

} else

snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));

return buf;

}

/*

* print a full list of all partitions - intended for places where the root

* filesystem can't be mounted and thus to give the victim some idea of what

* went wrong

*/

void __init printk_all_partitions(void)

{

struct class_dev_iter iter;

struct device *dev;

class_dev_iter_init(&iter, &block_class, NULL, &disk_type);

while ((dev = class_dev_iter_next(&iter))) {

struct gendisk *disk = dev_to_disk(dev);

struct block_device *part;

char devt_buf[BDEVT_SIZE];

unsigned long idx;

/*

* Don't show empty devices or things that have been

* suppressed

*/

if (get_capacity(disk) == 0 || (disk->flags & GENHD_FL_HIDDEN))

continue;

/*

* Note, unlike /proc/partitions, I am showing the numbers in

* hex - the same format as the root= option takes.

*/

rcu_read_lock();

xa_for_each(&disk->part_tbl, idx, part) {

if (!bdev_nr_sectors(part))

continue;

printk("%s%s %10llu %pg %s",

bdev_is_partition(part) ? " " : "",

bdevt_str(part->bd_dev, devt_buf),

bdev_nr_sectors(part) >> 1, part,

part->bd_meta_info ?

part->bd_meta_info->uuid : "");

if (bdev_is_partition(part))

printk("\n");

else if (dev->parent && dev->parent->driver)

printk(" driver: %s\n",

dev->parent->driver->name);

else

printk(" (driver?)\n");

}

rcu_read_unlock();

}

class_dev_iter_exit(&iter);

}