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