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 static 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
  50 void 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 }
  56 EXPORT_SYMBOL_GPL(guid_gen);
  57
  58 void 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 }
  64 EXPORT_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  */
  78 bool 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 }
  93 EXPORT_SYMBOL(uuid_is_valid);
  94
  95 static 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
 113 int guid_parse(const char *uuid, guid_t *u)
 114 {
 115         return __uuid_parse(uuid, u->b, guid_index);
 116 }
 117 EXPORT_SYMBOL(guid_parse);
 118
 119 int uuid_parse(const char *uuid, uuid_t *u)
 120 {
 121         return __uuid_parse(uuid, u->b, uuid_index);
 122 }
 123 EXPORT_SYMBOL(uuid_parse);