// 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);
}
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