1 | /**
|
---|
2 | * @file
|
---|
3 | * SNMPv3 crypto/auth functions implemented for ARM mbedtls.
|
---|
4 | */
|
---|
5 |
|
---|
6 | /*
|
---|
7 | * Copyright (c) 2016 Elias Oenal and Dirk Ziegelmeier.
|
---|
8 | * All rights reserved.
|
---|
9 | *
|
---|
10 | * Redistribution and use in source and binary forms, with or without modification,
|
---|
11 | * are permitted provided that the following conditions are met:
|
---|
12 | *
|
---|
13 | * 1. Redistributions of source code must retain the above copyright notice,
|
---|
14 | * this list of conditions and the following disclaimer.
|
---|
15 | * 2. Redistributions in binary form must reproduce the above copyright notice,
|
---|
16 | * this list of conditions and the following disclaimer in the documentation
|
---|
17 | * and/or other materials provided with the distribution.
|
---|
18 | * 3. The name of the author may not be used to endorse or promote products
|
---|
19 | * derived from this software without specific prior written permission.
|
---|
20 | *
|
---|
21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
|
---|
22 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
---|
23 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
|
---|
24 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
---|
25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
|
---|
26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
---|
27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
---|
28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
---|
29 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
|
---|
30 | * OF SUCH DAMAGE.
|
---|
31 | *
|
---|
32 | * Author: Elias Oenal <lwip@eliasoenal.com>
|
---|
33 | * Dirk Ziegelmeier <dirk@ziegelmeier.net>
|
---|
34 | */
|
---|
35 |
|
---|
36 | #include "lwip/apps/snmpv3.h"
|
---|
37 | #include "snmpv3_priv.h"
|
---|
38 | #include "lwip/arch.h"
|
---|
39 | #include "snmp_msg.h"
|
---|
40 | #include "lwip/sys.h"
|
---|
41 | #include <string.h>
|
---|
42 |
|
---|
43 | #if LWIP_SNMP && LWIP_SNMP_V3 && LWIP_SNMP_V3_MBEDTLS
|
---|
44 |
|
---|
45 | #include "mbedtls/md.h"
|
---|
46 | #include "mbedtls/cipher.h"
|
---|
47 |
|
---|
48 | #include "mbedtls/md5.h"
|
---|
49 | #include "mbedtls/sha1.h"
|
---|
50 |
|
---|
51 | err_t
|
---|
52 | snmpv3_auth(struct snmp_pbuf_stream *stream, u16_t length,
|
---|
53 | const u8_t *key, snmpv3_auth_algo_t algo, u8_t *hmac_out)
|
---|
54 | {
|
---|
55 | u32_t i;
|
---|
56 | u8_t key_len;
|
---|
57 | const mbedtls_md_info_t *md_info;
|
---|
58 | mbedtls_md_context_t ctx;
|
---|
59 | struct snmp_pbuf_stream read_stream;
|
---|
60 | snmp_pbuf_stream_init(&read_stream, stream->pbuf, stream->offset, stream->length);
|
---|
61 |
|
---|
62 | if (algo == SNMP_V3_AUTH_ALGO_MD5) {
|
---|
63 | md_info = mbedtls_md_info_from_type(MBEDTLS_MD_MD5);
|
---|
64 | key_len = SNMP_V3_MD5_LEN;
|
---|
65 | } else if (algo == SNMP_V3_AUTH_ALGO_SHA) {
|
---|
66 | md_info = mbedtls_md_info_from_type(MBEDTLS_MD_SHA1);
|
---|
67 | key_len = SNMP_V3_SHA_LEN;
|
---|
68 | } else {
|
---|
69 | return ERR_ARG;
|
---|
70 | }
|
---|
71 |
|
---|
72 | mbedtls_md_init(&ctx);
|
---|
73 | if (mbedtls_md_setup(&ctx, md_info, 1) != 0) {
|
---|
74 | return ERR_ARG;
|
---|
75 | }
|
---|
76 |
|
---|
77 | if (mbedtls_md_hmac_starts(&ctx, key, key_len) != 0) {
|
---|
78 | goto free_md;
|
---|
79 | }
|
---|
80 |
|
---|
81 | for (i = 0; i < length; i++) {
|
---|
82 | u8_t byte;
|
---|
83 |
|
---|
84 | if (snmp_pbuf_stream_read(&read_stream, &byte)) {
|
---|
85 | goto free_md;
|
---|
86 | }
|
---|
87 |
|
---|
88 | if (mbedtls_md_hmac_update(&ctx, &byte, 1) != 0) {
|
---|
89 | goto free_md;
|
---|
90 | }
|
---|
91 | }
|
---|
92 |
|
---|
93 | if (mbedtls_md_hmac_finish(&ctx, hmac_out) != 0) {
|
---|
94 | goto free_md;
|
---|
95 | }
|
---|
96 |
|
---|
97 | mbedtls_md_free(&ctx);
|
---|
98 | return ERR_OK;
|
---|
99 |
|
---|
100 | free_md:
|
---|
101 | mbedtls_md_free(&ctx);
|
---|
102 | return ERR_ARG;
|
---|
103 | }
|
---|
104 |
|
---|
105 | #if LWIP_SNMP_V3_CRYPTO
|
---|
106 |
|
---|
107 | err_t
|
---|
108 | snmpv3_crypt(struct snmp_pbuf_stream *stream, u16_t length,
|
---|
109 | const u8_t *key, const u8_t *priv_param, const u32_t engine_boots,
|
---|
110 | const u32_t engine_time, snmpv3_priv_algo_t algo, snmpv3_priv_mode_t mode)
|
---|
111 | {
|
---|
112 | size_t i;
|
---|
113 | mbedtls_cipher_context_t ctx;
|
---|
114 | const mbedtls_cipher_info_t *cipher_info;
|
---|
115 |
|
---|
116 | struct snmp_pbuf_stream read_stream;
|
---|
117 | struct snmp_pbuf_stream write_stream;
|
---|
118 | snmp_pbuf_stream_init(&read_stream, stream->pbuf, stream->offset, stream->length);
|
---|
119 | snmp_pbuf_stream_init(&write_stream, stream->pbuf, stream->offset, stream->length);
|
---|
120 | mbedtls_cipher_init(&ctx);
|
---|
121 |
|
---|
122 | if (algo == SNMP_V3_PRIV_ALGO_DES) {
|
---|
123 | u8_t iv_local[8];
|
---|
124 | u8_t out_bytes[8];
|
---|
125 | size_t out_len;
|
---|
126 |
|
---|
127 | /* RFC 3414 mandates padding for DES */
|
---|
128 | if ((length & 0x07) != 0) {
|
---|
129 | return ERR_ARG;
|
---|
130 | }
|
---|
131 |
|
---|
132 | cipher_info = mbedtls_cipher_info_from_type(MBEDTLS_CIPHER_DES_CBC);
|
---|
133 | if (mbedtls_cipher_setup(&ctx, cipher_info) != 0) {
|
---|
134 | return ERR_ARG;
|
---|
135 | }
|
---|
136 | if (mbedtls_cipher_set_padding_mode(&ctx, MBEDTLS_PADDING_NONE) != 0) {
|
---|
137 | return ERR_ARG;
|
---|
138 | }
|
---|
139 | if (mbedtls_cipher_setkey(&ctx, key, 8 * 8, (mode == SNMP_V3_PRIV_MODE_ENCRYPT) ? MBEDTLS_ENCRYPT : MBEDTLS_DECRYPT) != 0) {
|
---|
140 | goto error;
|
---|
141 | }
|
---|
142 |
|
---|
143 | /* Prepare IV */
|
---|
144 | for (i = 0; i < LWIP_ARRAYSIZE(iv_local); i++) {
|
---|
145 | iv_local[i] = priv_param[i] ^ key[i + 8];
|
---|
146 | }
|
---|
147 | if (mbedtls_cipher_set_iv(&ctx, iv_local, LWIP_ARRAYSIZE(iv_local)) != 0) {
|
---|
148 | goto error;
|
---|
149 | }
|
---|
150 |
|
---|
151 | for (i = 0; i < length; i += 8) {
|
---|
152 | size_t j;
|
---|
153 | u8_t in_bytes[8];
|
---|
154 | out_len = LWIP_ARRAYSIZE(out_bytes) ;
|
---|
155 |
|
---|
156 | for (j = 0; j < LWIP_ARRAYSIZE(in_bytes); j++) {
|
---|
157 | if (snmp_pbuf_stream_read(&read_stream, &in_bytes[j]) != ERR_OK) {
|
---|
158 | goto error;
|
---|
159 | }
|
---|
160 | }
|
---|
161 |
|
---|
162 | if (mbedtls_cipher_update(&ctx, in_bytes, LWIP_ARRAYSIZE(in_bytes), out_bytes, &out_len) != 0) {
|
---|
163 | goto error;
|
---|
164 | }
|
---|
165 |
|
---|
166 | if (snmp_pbuf_stream_writebuf(&write_stream, out_bytes, (u16_t)out_len) != ERR_OK) {
|
---|
167 | goto error;
|
---|
168 | }
|
---|
169 | }
|
---|
170 |
|
---|
171 | out_len = LWIP_ARRAYSIZE(out_bytes);
|
---|
172 | if (mbedtls_cipher_finish(&ctx, out_bytes, &out_len) != 0) {
|
---|
173 | goto error;
|
---|
174 | }
|
---|
175 |
|
---|
176 | if (snmp_pbuf_stream_writebuf(&write_stream, out_bytes, (u16_t)out_len) != ERR_OK) {
|
---|
177 | goto error;
|
---|
178 | }
|
---|
179 | } else if (algo == SNMP_V3_PRIV_ALGO_AES) {
|
---|
180 | u8_t iv_local[16];
|
---|
181 |
|
---|
182 | cipher_info = mbedtls_cipher_info_from_type(MBEDTLS_CIPHER_AES_128_CFB128);
|
---|
183 | if (mbedtls_cipher_setup(&ctx, cipher_info) != 0) {
|
---|
184 | return ERR_ARG;
|
---|
185 | }
|
---|
186 | if (mbedtls_cipher_setkey(&ctx, key, 16 * 8, (mode == SNMP_V3_PRIV_MODE_ENCRYPT) ? MBEDTLS_ENCRYPT : MBEDTLS_DECRYPT) != 0) {
|
---|
187 | goto error;
|
---|
188 | }
|
---|
189 |
|
---|
190 | /*
|
---|
191 | * IV is the big endian concatenation of boots,
|
---|
192 | * uptime and priv param - see RFC3826.
|
---|
193 | */
|
---|
194 | iv_local[0 + 0] = (engine_boots >> 24) & 0xFF;
|
---|
195 | iv_local[0 + 1] = (engine_boots >> 16) & 0xFF;
|
---|
196 | iv_local[0 + 2] = (engine_boots >> 8) & 0xFF;
|
---|
197 | iv_local[0 + 3] = (engine_boots >> 0) & 0xFF;
|
---|
198 | iv_local[4 + 0] = (engine_time >> 24) & 0xFF;
|
---|
199 | iv_local[4 + 1] = (engine_time >> 16) & 0xFF;
|
---|
200 | iv_local[4 + 2] = (engine_time >> 8) & 0xFF;
|
---|
201 | iv_local[4 + 3] = (engine_time >> 0) & 0xFF;
|
---|
202 | SMEMCPY(iv_local + 8, priv_param, 8);
|
---|
203 | if (mbedtls_cipher_set_iv(&ctx, iv_local, LWIP_ARRAYSIZE(iv_local)) != 0) {
|
---|
204 | goto error;
|
---|
205 | }
|
---|
206 |
|
---|
207 | for (i = 0; i < length; i++) {
|
---|
208 | u8_t in_byte;
|
---|
209 | u8_t out_byte;
|
---|
210 | size_t out_len = sizeof(out_byte);
|
---|
211 |
|
---|
212 | if (snmp_pbuf_stream_read(&read_stream, &in_byte) != ERR_OK) {
|
---|
213 | goto error;
|
---|
214 | }
|
---|
215 | if (mbedtls_cipher_update(&ctx, &in_byte, sizeof(in_byte), &out_byte, &out_len) != 0) {
|
---|
216 | goto error;
|
---|
217 | }
|
---|
218 | if (snmp_pbuf_stream_write(&write_stream, out_byte) != ERR_OK) {
|
---|
219 | goto error;
|
---|
220 | }
|
---|
221 | }
|
---|
222 | } else {
|
---|
223 | return ERR_ARG;
|
---|
224 | }
|
---|
225 |
|
---|
226 | mbedtls_cipher_free(&ctx);
|
---|
227 | return ERR_OK;
|
---|
228 |
|
---|
229 | error:
|
---|
230 | mbedtls_cipher_free(&ctx);
|
---|
231 | return ERR_OK;
|
---|
232 | }
|
---|
233 |
|
---|
234 | #endif /* LWIP_SNMP_V3_CRYPTO */
|
---|
235 |
|
---|
236 | /* A.2.1. Password to Key Sample Code for MD5 */
|
---|
237 | void
|
---|
238 | snmpv3_password_to_key_md5(
|
---|
239 | const u8_t *password, /* IN */
|
---|
240 | size_t passwordlen, /* IN */
|
---|
241 | const u8_t *engineID, /* IN - pointer to snmpEngineID */
|
---|
242 | u8_t engineLength,/* IN - length of snmpEngineID */
|
---|
243 | u8_t *key) /* OUT - pointer to caller 16-octet buffer */
|
---|
244 | {
|
---|
245 | mbedtls_md5_context MD;
|
---|
246 | u8_t *cp, password_buf[64];
|
---|
247 | u32_t password_index = 0;
|
---|
248 | u8_t i;
|
---|
249 | u32_t count = 0;
|
---|
250 |
|
---|
251 | mbedtls_md5_init(&MD); /* initialize MD5 */
|
---|
252 | mbedtls_md5_starts(&MD);
|
---|
253 |
|
---|
254 | /**********************************************/
|
---|
255 | /* Use while loop until we've done 1 Megabyte */
|
---|
256 | /**********************************************/
|
---|
257 | while (count < 1048576) {
|
---|
258 | cp = password_buf;
|
---|
259 | for (i = 0; i < 64; i++) {
|
---|
260 | /*************************************************/
|
---|
261 | /* Take the next octet of the password, wrapping */
|
---|
262 | /* to the beginning of the password as necessary.*/
|
---|
263 | /*************************************************/
|
---|
264 | *cp++ = password[password_index++ % passwordlen];
|
---|
265 | }
|
---|
266 | mbedtls_md5_update(&MD, password_buf, 64);
|
---|
267 | count += 64;
|
---|
268 | }
|
---|
269 | mbedtls_md5_finish(&MD, key); /* tell MD5 we're done */
|
---|
270 |
|
---|
271 | /*****************************************************/
|
---|
272 | /* Now localize the key with the engineID and pass */
|
---|
273 | /* through MD5 to produce final key */
|
---|
274 | /* May want to ensure that engineLength <= 32, */
|
---|
275 | /* otherwise need to use a buffer larger than 64 */
|
---|
276 | /*****************************************************/
|
---|
277 | SMEMCPY(password_buf, key, 16);
|
---|
278 | MEMCPY(password_buf + 16, engineID, engineLength);
|
---|
279 | SMEMCPY(password_buf + 16 + engineLength, key, 16);
|
---|
280 |
|
---|
281 | mbedtls_md5_starts(&MD);
|
---|
282 | mbedtls_md5_update(&MD, password_buf, 32 + engineLength);
|
---|
283 | mbedtls_md5_finish(&MD, key);
|
---|
284 |
|
---|
285 | mbedtls_md5_free(&MD);
|
---|
286 | return;
|
---|
287 | }
|
---|
288 |
|
---|
289 | /* A.2.2. Password to Key Sample Code for SHA */
|
---|
290 | void
|
---|
291 | snmpv3_password_to_key_sha(
|
---|
292 | const u8_t *password, /* IN */
|
---|
293 | size_t passwordlen, /* IN */
|
---|
294 | const u8_t *engineID, /* IN - pointer to snmpEngineID */
|
---|
295 | u8_t engineLength,/* IN - length of snmpEngineID */
|
---|
296 | u8_t *key) /* OUT - pointer to caller 20-octet buffer */
|
---|
297 | {
|
---|
298 | mbedtls_sha1_context SH;
|
---|
299 | u8_t *cp, password_buf[72];
|
---|
300 | u32_t password_index = 0;
|
---|
301 | u8_t i;
|
---|
302 | u32_t count = 0;
|
---|
303 |
|
---|
304 | mbedtls_sha1_init(&SH); /* initialize SHA */
|
---|
305 | mbedtls_sha1_starts(&SH);
|
---|
306 |
|
---|
307 | /**********************************************/
|
---|
308 | /* Use while loop until we've done 1 Megabyte */
|
---|
309 | /**********************************************/
|
---|
310 | while (count < 1048576) {
|
---|
311 | cp = password_buf;
|
---|
312 | for (i = 0; i < 64; i++) {
|
---|
313 | /*************************************************/
|
---|
314 | /* Take the next octet of the password, wrapping */
|
---|
315 | /* to the beginning of the password as necessary.*/
|
---|
316 | /*************************************************/
|
---|
317 | *cp++ = password[password_index++ % passwordlen];
|
---|
318 | }
|
---|
319 | mbedtls_sha1_update(&SH, password_buf, 64);
|
---|
320 | count += 64;
|
---|
321 | }
|
---|
322 | mbedtls_sha1_finish(&SH, key); /* tell SHA we're done */
|
---|
323 |
|
---|
324 | /*****************************************************/
|
---|
325 | /* Now localize the key with the engineID and pass */
|
---|
326 | /* through SHA to produce final key */
|
---|
327 | /* May want to ensure that engineLength <= 32, */
|
---|
328 | /* otherwise need to use a buffer larger than 72 */
|
---|
329 | /*****************************************************/
|
---|
330 | SMEMCPY(password_buf, key, 20);
|
---|
331 | MEMCPY(password_buf + 20, engineID, engineLength);
|
---|
332 | SMEMCPY(password_buf + 20 + engineLength, key, 20);
|
---|
333 |
|
---|
334 | mbedtls_sha1_starts(&SH);
|
---|
335 | mbedtls_sha1_update(&SH, password_buf, 40 + engineLength);
|
---|
336 | mbedtls_sha1_finish(&SH, key);
|
---|
337 |
|
---|
338 | mbedtls_sha1_free(&SH);
|
---|
339 | return;
|
---|
340 | }
|
---|
341 |
|
---|
342 | #endif /* LWIP_SNMP && LWIP_SNMP_V3 && LWIP_SNMP_V3_MBEDTLS */
|
---|