lib/uuid.c

   1 /*
   2  * Unified UUID/GUID definition
   3  *
   4  * Copyright (C) 2009, 2016 Intel Corp.
   5  *      Huang Ying <ying.huang@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License version
   9  * 2 as published by the Free Software Foundation;
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/ctype.h>
  19 #include <linux/errno.h>
  20 #include <linux/export.h>
  21 #include <linux/uuid.h>
  22 #include <linux/random.h>
  23
  24 const guid_t guid_null;
  25 EXPORT_SYMBOL(guid_null);
  26 const uuid_t uuid_null;
  27 EXPORT_SYMBOL(uuid_null);
  28
  29 const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
  30 const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
  31
  32 /**
  33  * generate_random_uuid - generate a random UUID
  34  * @uuid: where to put the generated UUID
  35  *
  36  * Random UUID interface
  37  *
  38  * Used to create a Boot ID or a filesystem UUID/GUID, but can be
  39  * useful for other kernel drivers.
  40  */
  41 void generate_random_uuid(unsigned char uuid[16])
  42 {
  43         get_random_bytes(uuid, 16);
  44         /* Set UUID version to 4 --- truly random generation */
  45         uuid[6] = (uuid[6] & 0x0F) | 0x40;
  46         /* Set the UUID variant to DCE */
  47         uuid[8] = (uuid[8] & 0x3F) | 0x80;
  48 }
  49 EXPORT_SYMBOL(generate_random_uuid);
  50
  51 static void __uuid_gen_common(__u8 b[16])
  52 {
  53         prandom_bytes(b, 16);
  54         /* reversion 0b10 */
  55         b[8] = (b[8] & 0x3F) | 0x80;
  56 }
  57
  58 void guid_gen(guid_t *lu)
  59 {
  60         __uuid_gen_common(lu->b);
  61         /* version 4 : random generation */
  62         lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
  63 }
  64 EXPORT_SYMBOL_GPL(guid_gen);
  65
  66 void uuid_gen(uuid_t *bu)
  67 {
  68         __uuid_gen_common(bu->b);
  69         /* version 4 : random generation */
  70         bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
  71 }
  72 EXPORT_SYMBOL_GPL(uuid_gen);
  73
  74 /**
  75  * uuid_is_valid - checks if a UUID string is valid
  76  * @uuid:       UUID string to check
  77  *
  78  * Description:
  79  * It checks if the UUID string is following the format:
  80  *      xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  81  *
  82  * where x is a hex digit.
  83  *
  84  * Return: true if input is valid UUID string.
  85  */
  86 bool uuid_is_valid(const char *uuid)
  87 {
  88         unsigned int i;
  89
  90         for (i = 0; i < UUID_STRING_LEN; i++) {
  91                 if (i == 8 || i == 13 || i == 18 || i == 23) {
  92                         if (uuid[i] != '-')
  93                                 return false;
  94                 } else if (!isxdigit(uuid[i])) {
  95                         return false;
  96                 }
  97         }
  98
  99         return true;
 100 }
 101 EXPORT_SYMBOL(uuid_is_valid);
 102
 103 static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
 104 {
 105         static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
 106         unsigned int i;
 107
 108         if (!uuid_is_valid(uuid))
 109                 return -EINVAL;
 110
 111         for (i = 0; i < 16; i++) {
 112                 int hi = hex_to_bin(uuid[si[i] + 0]);
 113                 int lo = hex_to_bin(uuid[si[i] + 1]);
 114
 115                 b[ei[i]] = (hi << 4) | lo;
 116         }
 117
 118         return 0;
 119 }
 120
 121 int guid_parse(const char *uuid, guid_t *u)
 122 {
 123         return __uuid_parse(uuid, u->b, guid_index);
 124 }
 125 EXPORT_SYMBOL(guid_parse);
 126
 127 int uuid_parse(const char *uuid, uuid_t *u)
 128 {
 129         return __uuid_parse(uuid, u->b, uuid_index);
 130 }
 131 EXPORT_SYMBOL(uuid_parse);