LXR linux/lib/uuid.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Unified UUID/GUID definition
   4 *
   5 * Copyright (C) 2009, 2016 Intel Corp.
   6 *      Huang Ying <ying.huang@intel.com>
   7 */
   8
   9#include <linux/kernel.h>
  10#include <linux/ctype.h>
  11#include <linux/errno.h>
  12#include <linux/export.h>
  13#include <linux/uuid.h>
  14#include <linux/random.h>
  15
  16const guid_t guid_null;
  17EXPORT_SYMBOL(guid_null);
  18const uuid_t uuid_null;
  19EXPORT_SYMBOL(uuid_null);
  20
  21const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
  22const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
  23
  24/**
  25 * generate_random_uuid - generate a random UUID
  26 * @uuid: where to put the generated UUID
  27 *
  28 * Random UUID interface
  29 *
  30 * Used to create a Boot ID or a filesystem UUID/GUID, but can be
  31 * useful for other kernel drivers.
  32 */
  33void generate_random_uuid(unsigned char uuid[16])
  34{
  35        get_random_bytes(uuid, 16);
  36        /* Set UUID version to 4 --- truly random generation */
  37        uuid[6] = (uuid[6] & 0x0F) | 0x40;
  38        /* Set the UUID variant to DCE */
  39        uuid[8] = (uuid[8] & 0x3F) | 0x80;
  40}
  41EXPORT_SYMBOL(generate_random_uuid);
  42
  43void generate_random_guid(unsigned char guid[16])
  44{
  45        get_random_bytes(guid, 16);
  46        /* Set GUID version to 4 --- truly random generation */
  47        guid[7] = (guid[7] & 0x0F) | 0x40;
  48        /* Set the GUID variant to DCE */
  49        guid[8] = (guid[8] & 0x3F) | 0x80;
  50}
  51EXPORT_SYMBOL(generate_random_guid);
  52
  53static void __uuid_gen_common(__u8 b[16])
  54{
  55        prandom_bytes(b, 16);
  56        /* reversion 0b10 */
  57        b[8] = (b[8] & 0x3F) | 0x80;
  58}
  59
  60void guid_gen(guid_t *lu)
  61{
  62        __uuid_gen_common(lu->b);
  63        /* version 4 : random generation */
  64        lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
  65}
  66EXPORT_SYMBOL_GPL(guid_gen);
  67
  68void uuid_gen(uuid_t *bu)
  69{
  70        __uuid_gen_common(bu->b);
  71        /* version 4 : random generation */
  72        bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
  73}
  74EXPORT_SYMBOL_GPL(uuid_gen);
  75
  76/**
  77 * uuid_is_valid - checks if a UUID string is valid
  78 * @uuid:       UUID string to check
  79 *
  80 * Description:
  81 * It checks if the UUID string is following the format:
  82 *      xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  83 *
  84 * where x is a hex digit.
  85 *
  86 * Return: true if input is valid UUID string.
  87 */
  88bool uuid_is_valid(const char *uuid)
  89{
  90        unsigned int i;
  91
  92        for (i = 0; i < UUID_STRING_LEN; i++) {
  93                if (i == 8 || i == 13 || i == 18 || i == 23) {
  94                        if (uuid[i] != '-')
  95                                return false;
  96                } else if (!isxdigit(uuid[i])) {
  97                        return false;
  98                }
  99        }
 100
 101        return true;
 102}
 103EXPORT_SYMBOL(uuid_is_valid);
 104
 105static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
 106{
 107        static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
 108        unsigned int i;
 109
 110        if (!uuid_is_valid(uuid))
 111                return -EINVAL;
 112
 113        for (i = 0; i < 16; i++) {
 114                int hi = hex_to_bin(uuid[si[i] + 0]);
 115                int lo = hex_to_bin(uuid[si[i] + 1]);
 116
 117                b[ei[i]] = (hi << 4) | lo;
 118        }
 119
 120        return 0;
 121}
 122
 123int guid_parse(const char *uuid, guid_t *u)
 124{
 125        return __uuid_parse(uuid, u->b, guid_index);
 126}
 127EXPORT_SYMBOL(guid_parse);
 128
 129int uuid_parse(const char *uuid, uuid_t *u)
 130{
 131        return __uuid_parse(uuid, u->b, uuid_index);
 132}
 133EXPORT_SYMBOL(uuid_parse);
 134