1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* ASN.1 Object identifier (OID) registry
3 *
4 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/module.h>
9 #include <linux/export.h>
10 #include <linux/oid_registry.h>
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/bug.h>
14 #include <linux/asn1.h>
15 #include "oid_registry_data.c"
16
17 MODULE_DESCRIPTION("OID Registry");
18 MODULE_AUTHOR("Red Hat, Inc.");
19 MODULE_LICENSE("GPL");
20
21 /**
22 * look_up_OID - Find an OID registration for the specified data
23 * @data: Binary representation of the OID
24 * @datasize: Size of the binary representation
25 */
look_up_OID(const void * data,size_t datasize)26 enum OID look_up_OID(const void *data, size_t datasize)
27 {
28 const unsigned char *octets = data;
29 enum OID oid;
30 unsigned char xhash;
31 unsigned i, j, k, hash;
32 size_t len;
33
34 /* Hash the OID data */
35 hash = datasize - 1;
36
37 for (i = 0; i < datasize; i++)
38 hash += octets[i] * 33;
39 hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash;
40 hash &= 0xff;
41
42 /* Binary search the OID registry. OIDs are stored in ascending order
43 * of hash value then ascending order of size and then in ascending
44 * order of reverse value.
45 */
46 i = 0;
47 k = OID__NR;
48 while (i < k) {
49 j = (i + k) / 2;
50
51 xhash = oid_search_table[j].hash;
52 if (xhash > hash) {
53 k = j;
54 continue;
55 }
56 if (xhash < hash) {
57 i = j + 1;
58 continue;
59 }
60
61 oid = oid_search_table[j].oid;
62 len = oid_index[oid + 1] - oid_index[oid];
63 if (len > datasize) {
64 k = j;
65 continue;
66 }
67 if (len < datasize) {
68 i = j + 1;
69 continue;
70 }
71
72 /* Variation is most likely to be at the tail end of the
73 * OID, so do the comparison in reverse.
74 */
75 while (len > 0) {
76 unsigned char a = oid_data[oid_index[oid] + --len];
77 unsigned char b = octets[len];
78 if (a > b) {
79 k = j;
80 goto next;
81 }
82 if (a < b) {
83 i = j + 1;
84 goto next;
85 }
86 }
87 return oid;
88 next:
89 ;
90 }
91
92 return OID__NR;
93 }
94 EXPORT_SYMBOL_GPL(look_up_OID);
95
96 /**
97 * parse_OID - Parse an OID from a bytestream
98 * @data: Binary representation of the header + OID
99 * @datasize: Size of the binary representation
100 * @oid: Pointer to oid to return result
101 *
102 * Parse an OID from a bytestream that holds the OID in the format
103 * ASN1_OID | length | oid. The length indicator must equal to datasize - 2.
104 * -EBADMSG is returned if the bytestream is too short.
105 */
parse_OID(const void * data,size_t datasize,enum OID * oid)106 int parse_OID(const void *data, size_t datasize, enum OID *oid)
107 {
108 const unsigned char *v = data;
109
110 /* we need 2 bytes of header and at least 1 byte for oid */
111 if (datasize < 3 || v[0] != ASN1_OID || v[1] != datasize - 2)
112 return -EBADMSG;
113
114 *oid = look_up_OID(data + 2, datasize - 2);
115 return 0;
116 }
117 EXPORT_SYMBOL_GPL(parse_OID);
118
119 /*
120 * sprint_oid - Print an Object Identifier into a buffer
121 * @data: The encoded OID to print
122 * @datasize: The size of the encoded OID
123 * @buffer: The buffer to render into
124 * @bufsize: The size of the buffer
125 *
126 * The OID is rendered into the buffer in "a.b.c.d" format and the number of
127 * bytes is returned. -EBADMSG is returned if the data could not be interpreted
128 * and -ENOBUFS if the buffer was too small.
129 */
sprint_oid(const void * data,size_t datasize,char * buffer,size_t bufsize)130 int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
131 {
132 const unsigned char *v = data, *end = v + datasize;
133 unsigned long num;
134 unsigned char n;
135 size_t ret;
136 int count;
137
138 if (v >= end)
139 goto bad;
140
141 n = *v++;
142 ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
143 if (count >= bufsize)
144 return -ENOBUFS;
145 buffer += count;
146 bufsize -= count;
147
148 while (v < end) {
149 n = *v++;
150 if (!(n & 0x80)) {
151 num = n;
152 } else {
153 num = n & 0x7f;
154 do {
155 if (v >= end)
156 goto bad;
157 n = *v++;
158 num <<= 7;
159 num |= n & 0x7f;
160 } while (n & 0x80);
161 }
162 ret += count = snprintf(buffer, bufsize, ".%lu", num);
163 if (count >= bufsize)
164 return -ENOBUFS;
165 buffer += count;
166 bufsize -= count;
167 }
168
169 return ret;
170
171 bad:
172 snprintf(buffer, bufsize, "(bad)");
173 return -EBADMSG;
174 }
175 EXPORT_SYMBOL_GPL(sprint_oid);
176