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
  43static void __uuid_gen_common(__u8 b[16])
  44{
  45        prandom_bytes(b, 16);
  46        /* reversion 0b10 */
  47        b[8] = (b[8] & 0x3F) | 0x80;
  48}
  49
  50void guid_gen(guid_t *lu)
  51{
  52        __uuid_gen_common(lu->b);
  53        /* version 4 : random generation */
  54        lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
  55}
  56EXPORT_SYMBOL_GPL(guid_gen);
  57
  58void uuid_gen(uuid_t *bu)
  59{
  60        __uuid_gen_common(bu->b);
  61        /* version 4 : random generation */
  62        bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
  63}
  64EXPORT_SYMBOL_GPL(uuid_gen);
  65
  66/**
  67 * uuid_is_valid - checks if a UUID string is valid
  68 * @uuid:       UUID string to check
  69 *
  70 * Description:
  71 * It checks if the UUID string is following the format:
  72 *      xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  73 *
  74 * where x is a hex digit.
  75 *
  76 * Return: true if input is valid UUID string.
  77 */
  78bool uuid_is_valid(const char *uuid)
  79{
  80        unsigned int i;
  81
  82        for (i = 0; i < UUID_STRING_LEN; i++) {
  83                if (i == 8 || i == 13 || i == 18 || i == 23) {
  84                        if (uuid[i] != '-')
  85                                return false;
  86                } else if (!isxdigit(uuid[i])) {
  87                        return false;
  88                }
  89        }
  90
  91        return true;
  92}
  93EXPORT_SYMBOL(uuid_is_valid);
  94
  95static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
  96{
  97        static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
  98        unsigned int i;
  99
 100        if (!uuid_is_valid(uuid))
 101                return -EINVAL;
 102
 103        for (i = 0; i < 16; i++) {
 104                int hi = hex_to_bin(uuid[si[i] + 0]);
 105                int lo = hex_to_bin(uuid[si[i] + 1]);
 106
 107                b[ei[i]] = (hi << 4) | lo;
 108        }
 109
 110        return 0;
 111}
 112
 113int guid_parse(const char *uuid, guid_t *u)
 114{
 115        return __uuid_parse(uuid, u->b, guid_index);
 116}
 117EXPORT_SYMBOL(guid_parse);
 118
 119int uuid_parse(const char *uuid, uuid_t *u)
 120{
 121        return __uuid_parse(uuid, u->b, uuid_index);
 122}
 123EXPORT_SYMBOL(uuid_parse);
 124