xref: /openbmc/linux/lib/uuid.c (revision fce96cf0443083e37455eff8f78fd240c621dae3)
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);
134