xref: /openbmc/linux/lib/oid_registry.c (revision 1aae9056)
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 
177 /**
178  * sprint_OID - Print an Object Identifier into a buffer
179  * @oid: The OID to print
180  * @buffer: The buffer to render into
181  * @bufsize: The size of the buffer
182  *
183  * The OID is rendered into the buffer in "a.b.c.d" format and the number of
184  * bytes is returned.
185  */
sprint_OID(enum OID oid,char * buffer,size_t bufsize)186 int sprint_OID(enum OID oid, char *buffer, size_t bufsize)
187 {
188 	int ret;
189 
190 	BUG_ON(oid >= OID__NR);
191 
192 	ret = sprint_oid(oid_data + oid_index[oid],
193 			 oid_index[oid + 1] - oid_index[oid],
194 			 buffer, bufsize);
195 	BUG_ON(ret == -EBADMSG);
196 	return ret;
197 }
198 EXPORT_SYMBOL_GPL(sprint_OID);
199