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 u8 uuid_le_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
  25 EXPORT_SYMBOL(uuid_le_index);
  26 const u8 uuid_be_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
  27 EXPORT_SYMBOL(uuid_be_index);
  28
  29 /***************************************************************
  30  * Random UUID interface
  31  *
  32  * Used here for a Boot ID, but can be useful for other kernel
  33  * drivers.
  34  ***************************************************************/
  35
  36 /*
  37  * Generate random UUID
  38  */
  39 void generate_random_uuid(unsigned char uuid[16])
  40 {
  41         get_random_bytes(uuid, 16);
  42         /* Set UUID version to 4 --- truly random generation */
  43         uuid[6] = (uuid[6] & 0x0F) | 0x40;
  44         /* Set the UUID variant to DCE */
  45         uuid[8] = (uuid[8] & 0x3F) | 0x80;
  46 }
  47 EXPORT_SYMBOL(generate_random_uuid);
  48
  49 static void __uuid_gen_common(__u8 b[16])
  50 {
  51         prandom_bytes(b, 16);
  52         /* reversion 0b10 */
  53         b[8] = (b[8] & 0x3F) | 0x80;
  54 }
  55
  56 void uuid_le_gen(uuid_le *lu)
  57 {
  58         __uuid_gen_common(lu->b);
  59         /* version 4 : random generation */
  60         lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
  61 }
  62 EXPORT_SYMBOL_GPL(uuid_le_gen);
  63
  64 void uuid_be_gen(uuid_be *bu)
  65 {
  66         __uuid_gen_common(bu->b);
  67         /* version 4 : random generation */
  68         bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
  69 }
  70 EXPORT_SYMBOL_GPL(uuid_be_gen);
  71
  72 /**
  73   * uuid_is_valid - checks if UUID string valid
  74   * @uuid:      UUID string to check
  75   *
  76   * Description:
  77   * It checks if the UUID string is following the format:
  78   *     xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  79   * where x is a hex digit.
  80   *
  81   * Return: true if input is valid UUID string.
  82   */
  83 bool uuid_is_valid(const char *uuid)
  84 {
  85         unsigned int i;
  86
  87         for (i = 0; i < UUID_STRING_LEN; i++) {
  88                 if (i == 8 || i == 13 || i == 18 || i == 23) {
  89                         if (uuid[i] != '-')
  90                                 return false;
  91                 } else if (!isxdigit(uuid[i])) {
  92                         return false;
  93                 }
  94         }
  95
  96         return true;
  97 }
  98 EXPORT_SYMBOL(uuid_is_valid);
  99
 100 static int __uuid_to_bin(const char *uuid, __u8 b[16], const u8 ei[16])
 101 {
 102         static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
 103         unsigned int i;
 104
 105         if (!uuid_is_valid(uuid))
 106                 return -EINVAL;
 107
 108         for (i = 0; i < 16; i++) {
 109                 int hi = hex_to_bin(uuid[si[i] + 0]);
 110                 int lo = hex_to_bin(uuid[si[i] + 1]);
 111
 112                 b[ei[i]] = (hi << 4) | lo;
 113         }
 114
 115         return 0;
 116 }
 117
 118 int uuid_le_to_bin(const char *uuid, uuid_le *u)
 119 {
 120         return __uuid_to_bin(uuid, u->b, uuid_le_index);
 121 }
 122 EXPORT_SYMBOL(uuid_le_to_bin);
 123
 124 int uuid_be_to_bin(const char *uuid, uuid_be *u)
 125 {
 126         return __uuid_to_bin(uuid, u->b, uuid_be_index);
 127 }
 128 EXPORT_SYMBOL(uuid_be_to_bin);