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
  16 const guid_t guid_null;
  17 EXPORT_SYMBOL(guid_null);
  18 const uuid_t uuid_null;
  19 EXPORT_SYMBOL(uuid_null);
  20
  21 const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
  22 const 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  */
  33 void 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 }
  41 EXPORT_SYMBOL(generate_random_uuid);
  42
  43 void 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 }
  51 EXPORT_SYMBOL(generate_random_guid);
  52
  53 static 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
  60 void 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 }
  66 EXPORT_SYMBOL_GPL(guid_gen);
  67
  68 void 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 }
  74 EXPORT_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  */
  88 bool 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 }
 103 EXPORT_SYMBOL(uuid_is_valid);
 104
 105 static 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
 123 int guid_parse(const char *uuid, guid_t *u)
 124 {
 125         return __uuid_parse(uuid, u->b, guid_index);
 126 }
 127 EXPORT_SYMBOL(guid_parse);
 128
 129 int uuid_parse(const char *uuid, uuid_t *u)
 130 {
 131         return __uuid_parse(uuid, u->b, uuid_index);
 132 }
 133 EXPORT_SYMBOL(uuid_parse);