lib/uuid.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Unified UUID/GUID definition
 *
 * Copyright (C) 2009, 2016 Intel Corp.
 *	Huang Ying <ying.huang@intel.com>
 */

#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/uuid.h>
#include <linux/random.h>

const guid_t guid_null;
EXPORT_SYMBOL(guid_null);
const uuid_t uuid_null;
EXPORT_SYMBOL(uuid_null);

const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};

/**
 * generate_random_uuid - generate a random UUID
 * @uuid: where to put the generated UUID
 *
 * Random UUID interface
 *
 * Used to create a Boot ID or a filesystem UUID/GUID, but can be
 * useful for other kernel drivers.
 */
void generate_random_uuid(unsigned char uuid[16])
{
	get_random_bytes(uuid, 16);
	/* Set UUID version to 4 --- truly random generation */
	uuid[6] = (uuid[6] & 0x0F) | 0x40;
	/* Set the UUID variant to DCE */
	uuid[8] = (uuid[8] & 0x3F) | 0x80;
}
EXPORT_SYMBOL(generate_random_uuid);

static void __uuid_gen_common(__u8 b[16])
{
	prandom_bytes(b, 16);
	/* reversion 0b10 */
	b[8] = (b[8] & 0x3F) | 0x80;
}

void guid_gen(guid_t *lu)
{
	__uuid_gen_common(lu->b);
	/* version 4 : random generation */
	lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
}
EXPORT_SYMBOL_GPL(guid_gen);

void uuid_gen(uuid_t *bu)
{
	__uuid_gen_common(bu->b);
	/* version 4 : random generation */
	bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
}
EXPORT_SYMBOL_GPL(uuid_gen);

/**
 * uuid_is_valid - checks if a UUID string is valid
 * @uuid:	UUID string to check
 *
 * Description:
 * It checks if the UUID string is following the format:
 *	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
 *
 * where x is a hex digit.
 *
 * Return: true if input is valid UUID string.
 */
bool uuid_is_valid(const char *uuid)
{
	unsigned int i;

	for (i = 0; i < UUID_STRING_LEN; i++) {
		if (i == 8 || i == 13 || i == 18 || i == 23) {
			if (uuid[i] != '-')
				return false;
		} else if (!isxdigit(uuid[i])) {
			return false;
		}
	}

	return true;
}
EXPORT_SYMBOL(uuid_is_valid);

static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
{
	static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
	unsigned int i;

	if (!uuid_is_valid(uuid))
		return -EINVAL;

	for (i = 0; i < 16; i++) {
		int hi = hex_to_bin(uuid[si[i] + 0]);
		int lo = hex_to_bin(uuid[si[i] + 1]);

		b[ei[i]] = (hi << 4) | lo;
	}

	return 0;
}

int guid_parse(const char *uuid, guid_t *u)
{
	return __uuid_parse(uuid, u->b, guid_index);
}
EXPORT_SYMBOL(guid_parse);

int uuid_parse(const char *uuid, uuid_t *u)
{
	return __uuid_parse(uuid, u->b, uuid_index);
}
EXPORT_SYMBOL(uuid_parse);