oid_registry.c

  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
 17MODULE_DESCRIPTION("OID Registry");
 18MODULE_AUTHOR("Red Hat, Inc.");
 19MODULE_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 */
 26enum 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}
 94EXPORT_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 */
106int 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}
117EXPORT_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 */
130int 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
171bad:
172	snprintf(buffer, bufsize, "(bad)");
173	return -EBADMSG;
174}
175EXPORT_SYMBOL_GPL(sprint_oid);