1 | #include <assert.h> |
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2 | #include <err.h> |
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3 | #include <termios.h> |
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4 | #include <time.h> |
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5 | |
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6 | // include the GNU extension of asprintf |
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7 | #define _GNU_SOURCE |
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8 | #include <stdio.h> |
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9 | |
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10 | #include "libcreddy_common.h" |
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11 | |
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12 | #define KEY_SUFFIX "_private.pem" |
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13 | #define CERT_SUFFIX "_ID.pem" |
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14 | /* Size of password memory allocation */ |
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15 | #define PWLEN 128 |
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16 | |
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17 | // |
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18 | // ID object |
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19 | // |
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20 | struct _creddy_id_t { |
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21 | char *keyid; |
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22 | char *cn; |
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23 | certificate_t *cert; |
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24 | private_key_t *key; |
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25 | |
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26 | int refcount; |
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27 | }; |
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28 | |
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29 | /* Callback configuration */ |
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30 | struct cb_opts { |
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31 | bool use_prompt; /* Print a prompt to stderr */ |
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32 | bool use_echo; /* If true, turn off input echo on stdin */ |
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33 | unsigned int tries; /* Number of attempts allowed */ |
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34 | char prompt[20]; /* The prompt to display if use_echo is true */ |
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35 | }; |
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36 | |
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37 | static char *_get_keyid(certificate_t *cert); |
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38 | static chunk_t _passphrase_callback(void *user, int try); |
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39 | static private_key_t *_generate_key(void); |
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40 | static certificate_t *_generate_cert(private_key_t *private, char *cn, int validity); |
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41 | static void _encode_base64(FILE *out, chunk_t encoding); |
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42 | |
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43 | /** |
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44 | * Load an ID cert from a file. |
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45 | */ |
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46 | creddy_id_t *creddy_id_from_file(char *filename) { |
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47 | libabac_init(); |
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48 | |
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49 | certificate_t *cert = lib->creds->create(lib->creds, |
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50 | CRED_CERTIFICATE, CERT_X509, |
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51 | BUILD_FROM_FILE, filename, |
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52 | BUILD_X509_FLAG, X509_AA, |
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53 | BUILD_END |
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54 | ); |
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55 | |
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56 | if (cert == NULL) |
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57 | return NULL; |
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58 | |
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59 | creddy_id_t *id = creddy_xmalloc(sizeof(creddy_id_t)); |
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60 | id->keyid = NULL; |
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61 | id->cn = NULL; |
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62 | id->cert = cert; |
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63 | id->key = NULL; |
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64 | |
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65 | id->keyid = _get_keyid(id->cert); |
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66 | |
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67 | // get the CN from the cert |
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68 | id_part_t type; |
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69 | chunk_t data; |
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70 | |
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71 | identification_t *cert_id = id->cert->get_subject(id->cert); |
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72 | enumerator_t *id_enum = cert_id->create_part_enumerator(cert_id); |
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73 | while (id_enum->enumerate(id_enum, &type, &data)) |
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74 | if (type == ID_PART_RDN_CN) { |
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75 | id->cn = creddy_xmalloc(data.len + 1); |
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76 | memcpy(id->cn, data.ptr, data.len); |
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77 | id->cn[data.len] = 0; |
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78 | } |
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79 | id_enum->destroy(id_enum); |
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80 | |
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81 | id->refcount = 1; |
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82 | |
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83 | return id; |
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84 | } |
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85 | |
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86 | |
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87 | /** |
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88 | * Load private key for a cert. |
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89 | */ |
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90 | int creddy_id_load_privkey(creddy_id_t *id, char *filename) { |
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91 | struct cb_opts c_opts = { 1, 0, 3, "Key password:" }; |
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92 | |
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93 | assert(id != NULL); |
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94 | |
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95 | libabac_init(); |
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96 | |
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97 | // load signer key |
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98 | private_key_t *key = lib->creds->create(lib->creds, |
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99 | CRED_PRIVATE_KEY, KEY_RSA, |
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100 | BUILD_FROM_FILE, filename, |
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101 | /* Ask for password if the key's encrypted */ |
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102 | BUILD_PASSPHRASE_CALLBACK, _passphrase_callback, &c_opts, |
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103 | BUILD_END |
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104 | ); |
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105 | if (key == NULL) |
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106 | return 0; |
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107 | |
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108 | id->key = key; |
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109 | return 1; |
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110 | } |
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111 | |
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112 | /** |
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113 | * Generate an ID with the specified CN and validity. |
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114 | */ |
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115 | int creddy_id_generate(creddy_id_t **ret, char *cn, int validity) { |
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116 | if (cn == NULL || !creddy_clean_name(cn)) |
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117 | return CREDDY_GENERATE_INVALID_CN; |
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118 | |
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119 | if (validity < 0) |
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120 | return CREDDY_GENERATE_INVALID_VALIDITY; |
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121 | |
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122 | creddy_id_t *id = creddy_xmalloc(sizeof(creddy_id_t)); |
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123 | |
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124 | id->cn = creddy_xstrdup(cn); |
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125 | id->key = _generate_key(); |
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126 | id->cert = _generate_cert(id->key, cn, validity); |
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127 | id->keyid = _get_keyid(id->cert); |
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128 | |
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129 | id->refcount = 1; |
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130 | |
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131 | *ret = id; |
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132 | return CREDDY_SUCCESS; |
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133 | } |
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134 | |
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135 | char *creddy_id_keyid(creddy_id_t *id) { |
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136 | assert(id != NULL); |
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137 | |
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138 | return id->keyid; |
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139 | } |
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140 | |
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141 | /** |
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142 | * Get the issuer of an ID cert. |
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143 | * Returns a malloc'd string that must be free'd. |
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144 | */ |
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145 | char *creddy_id_issuer(creddy_id_t *id) { |
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146 | char *ret; |
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147 | int rv = asprintf(&ret, "%Y", id->cert->get_issuer(id->cert)); |
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148 | |
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149 | if (rv < 0) |
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150 | err(1, "couldn't malloc string for issuer\n"); |
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151 | |
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152 | return ret; |
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153 | } |
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154 | |
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155 | /** |
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156 | * Gets the subject DN of an ID cert. |
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157 | * Returns a malloc'd string that must be free'd. |
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158 | */ |
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159 | char *creddy_id_subject(creddy_id_t *id) { |
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160 | char *ret; |
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161 | int rv = asprintf(&ret, "%Y", id->cert->get_subject(id->cert)); |
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162 | |
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163 | if (rv < 0) |
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164 | err(1, "couldn't malloc string for subject\n"); |
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165 | |
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166 | return ret; |
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167 | } |
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168 | |
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169 | /** |
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170 | * Get the validity period. |
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171 | */ |
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172 | void creddy_id_validity(creddy_id_t *id, time_t *not_before, time_t *not_after) { |
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173 | id->cert->get_validity(id->cert, NULL, not_before, not_after); |
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174 | } |
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175 | |
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176 | certificate_t *creddy_id_cert(creddy_id_t *id) { |
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177 | assert(id != NULL); |
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178 | |
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179 | return id->cert; |
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180 | } |
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181 | |
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182 | private_key_t *creddy_id_privkey(creddy_id_t *id) { |
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183 | assert(id != NULL); |
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184 | |
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185 | return id->key; |
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186 | } |
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187 | |
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188 | /** |
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189 | * Get the default filename for the cert. Value must be freed by caller. |
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190 | */ |
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191 | char *creddy_id_cert_filename(creddy_id_t *id) { |
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192 | assert(id != NULL); |
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193 | assert(id->cn != NULL); |
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194 | |
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195 | // malloc the filename |
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196 | int len = strlen(id->cn) + strlen(CERT_SUFFIX) + 1; |
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197 | char *filename = creddy_xmalloc(len); |
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198 | sprintf(filename, "%s" CERT_SUFFIX, id->cn); |
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199 | |
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200 | return filename; |
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201 | } |
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202 | |
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203 | /** |
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204 | * Write the ID cert to an open file pointer. |
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205 | */ |
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206 | void creddy_id_write_cert(creddy_id_t *id, FILE *out) { |
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207 | assert(id != NULL); |
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208 | |
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209 | chunk_t encoding = id->cert->get_encoding(id->cert); |
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210 | _encode_base64(out, encoding); |
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211 | free(encoding.ptr); |
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212 | } |
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213 | |
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214 | /** |
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215 | * Default private key filename. Value must be freed by caller. |
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216 | */ |
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217 | char *creddy_id_privkey_filename(creddy_id_t *id) { |
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218 | assert(id != NULL); |
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219 | assert(id->cn != NULL); |
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220 | |
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221 | // malloc the filename |
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222 | int len = strlen(id->cn) + strlen(KEY_SUFFIX) + 1; |
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223 | char *filename = creddy_xmalloc(len); |
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224 | sprintf(filename, "%s" KEY_SUFFIX, id->cn); |
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225 | |
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226 | return filename; |
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227 | } |
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228 | |
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229 | /** |
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230 | * Write the private key to a file. |
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231 | * Returns false if there's no private key loaded |
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232 | */ |
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233 | int creddy_id_write_privkey(creddy_id_t *id, FILE *out) { |
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234 | int ret; |
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235 | chunk_t encoding; |
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236 | |
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237 | assert(id != NULL); |
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238 | |
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239 | if (id->key == NULL) |
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240 | return 0; |
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241 | |
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242 | ret = id->key->get_encoding(id->key, KEY_PRIV_PEM, &encoding); |
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243 | if (!ret) |
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244 | errx(1, "Couldn't encode private key"); |
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245 | |
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246 | fwrite(encoding.ptr, encoding.len, 1, out); |
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247 | |
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248 | free(encoding.ptr); |
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249 | return 1; |
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250 | } |
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251 | |
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252 | /** |
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253 | * Get a DER-encoded chunk representing the cert. |
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254 | */ |
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255 | abac_chunk_t creddy_id_cert_chunk(creddy_id_t *id) { |
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256 | chunk_t encoding = id->cert->get_encoding(id->cert); |
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257 | abac_chunk_t ret = { encoding.ptr, encoding.len }; |
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258 | return ret; |
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259 | } |
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260 | |
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261 | /** |
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262 | * Copy a creddy ID. Actually just increases its reference count. |
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263 | */ |
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264 | creddy_id_t *creddy_id_dup(creddy_id_t *id) { |
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265 | ++id->refcount; |
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266 | } |
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267 | |
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268 | void creddy_id_free(creddy_id_t *id) { |
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269 | if (id == NULL) |
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270 | return; |
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271 | |
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272 | --id->refcount; |
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273 | if (id->refcount > 0) |
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274 | return; |
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275 | |
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276 | // free once the reference count reaches 0 |
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277 | DESTROY_IF(id->cert); |
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278 | DESTROY_IF(id->key); |
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279 | |
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280 | free(id->keyid); |
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281 | free(id); |
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282 | } |
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283 | |
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284 | // |
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285 | // Helper functions below |
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286 | // |
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287 | |
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288 | static char *_get_keyid(certificate_t *cert) { |
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289 | // get the keyid |
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290 | x509_t *x509 = (x509_t *)cert; |
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291 | chunk_t keyid = x509->get_subjectKeyIdentifier(x509); |
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292 | chunk_t string = chunk_to_hex(keyid, NULL, 0); |
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293 | return (char *)string.ptr; |
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294 | } |
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295 | |
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296 | static chunk_t _passphrase_callback(void *user, int try) { |
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297 | /* Get a password from stdin and return it as a chunk_t. If too many tries |
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298 | * have occurred or there is any other problem, return an empty chunk_t, |
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299 | * which libstrongswan takes as giving up. The chunk is alloated here |
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300 | * (inside getline), and presumably freed by libstrongswan. User points to |
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301 | * a cb_opts struct, which affects this routine in the obvious ways. |
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302 | */ |
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303 | /* Configuration options */ |
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304 | struct cb_opts *opts = (struct cb_opts *) user; |
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305 | chunk_t rv = chunk_empty; /* Return value, starts empty */ |
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306 | |
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307 | if (try -1 < opts->tries ) { |
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308 | struct termios t; /* Terminal settings */ |
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309 | size_t len = 0; /* Length of string from getline */ |
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310 | tcflag_t orig = 0; /* Holds the original local flags (echo in here) */ |
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311 | |
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312 | if (!opts->use_echo) { |
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313 | /* Use tc{get,set}attr to turn echo off and restore the intial |
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314 | * echo settings */ |
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315 | if (!tcgetattr(0, &t)) { |
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316 | orig = t.c_lflag; |
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317 | |
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318 | t.c_lflag &= ~ECHO; |
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319 | if ( tcsetattr(0, TCSANOW, &t) ) { |
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320 | perror("Cannot turn off echo"); |
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321 | return rv; |
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322 | } |
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323 | } |
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324 | else { |
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325 | perror("Cannot turn get attributes to off echo"); |
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326 | return rv; |
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327 | } |
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328 | } |
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329 | if (opts->use_prompt) printf("%s", opts->prompt); |
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330 | |
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331 | /* Because rv.ptr starts as NULL, getline allocates memory. The size |
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332 | * of the allocation returns in rv.len and the size of the string |
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333 | * (including newline and NUL) is in len. */ |
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334 | if ((rv.ptr = (u_char *) malloc(rv.len = PWLEN))) { |
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335 | if ( fgets(rv.ptr, rv.len, stdin) ) { |
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336 | /* Readjust the chunk_t's len field to the size of the string |
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337 | * w/o the newline or NUL */ |
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338 | /* would prefer strnlen, but no such luck in FBSD7 or earlier*/ |
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339 | size_t len = strlen(rv.ptr); |
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340 | |
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341 | if (rv.ptr[len-2] == '\n') rv.len = len-2; |
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342 | else rv.len = len -1; |
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343 | } |
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344 | else { |
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345 | /* Read failed. Deallocate and clear rv */ |
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346 | free(rv.ptr); |
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347 | rv = chunk_empty; |
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348 | } |
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349 | } |
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350 | else { |
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351 | /* Failed malloc. Restore rv to empty and return it */ |
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352 | perror("malloc"); |
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353 | rv = chunk_empty; |
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354 | return rv; |
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355 | } |
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356 | |
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357 | if (!opts->use_echo ) { |
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358 | /* Pop echo beck to its original setting. */ |
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359 | t.c_lflag = orig; |
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360 | |
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361 | if ( tcsetattr(0, TCSANOW, &t) ) |
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362 | perror("Cannot restore echo setting?"); |
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363 | |
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364 | if (opts->use_prompt) printf("\n"); |
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365 | } |
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366 | } |
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367 | else fprintf(stderr, "Too many tries (%d)", try-1); |
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368 | return rv; |
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369 | } |
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370 | |
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371 | /** |
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372 | * Generate a private key. |
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373 | */ |
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374 | static private_key_t *_generate_key(void) { |
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375 | private_key_t *key; |
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376 | libabac_init(); |
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377 | |
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378 | // generate the key |
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379 | key = lib->creds->create( |
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380 | lib->creds, |
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381 | CRED_PRIVATE_KEY, KEY_RSA, |
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382 | BUILD_KEY_SIZE, 2048, |
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383 | BUILD_END |
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384 | ); |
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385 | if (key == NULL) |
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386 | errx(1, "Key generation failed"); |
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387 | |
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388 | return key; |
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389 | } |
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390 | |
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391 | static char *_create_dn(char *cn) { |
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392 | |
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393 | #define DN "cn=" |
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394 | |
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395 | char *dn = creddy_xmalloc(sizeof(DN) + strlen(cn)); |
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396 | memcpy(dn, DN, sizeof(DN)); |
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397 | strcat(dn, cn); |
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398 | |
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399 | return dn; |
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400 | } |
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401 | |
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402 | /** |
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403 | * Generate certificate. |
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404 | */ |
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405 | static certificate_t *_generate_cert(private_key_t *private, char *cn, int validity) { |
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406 | // build the DN |
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407 | char *dn_string = _create_dn(cn); |
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408 | libabac_init(); |
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409 | |
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410 | identification_t *id = identification_create_from_string(dn_string); |
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411 | if (id == NULL) |
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412 | errx(1, "couldn't create ID from DN %s", dn_string); |
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413 | free(dn_string); |
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414 | |
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415 | // get the public key |
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416 | public_key_t *public = private->get_public_key(private); |
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417 | if (public == NULL) |
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418 | errx(1, "couldn't get public key from private key"); |
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419 | |
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420 | // create a serial (stolen from strongswan pki) |
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421 | rng_t *rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); |
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422 | if (!rng) |
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423 | errx(1, "no random number generator"); |
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424 | |
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425 | // random serial |
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426 | chunk_t serial = creddy_generate_serial(); |
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427 | |
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428 | // validity period |
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429 | time_t not_before = time(NULL); |
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430 | time_t not_after = not_before + validity * 24 * 60 * 60; |
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431 | |
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432 | // create! |
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433 | certificate_t *cert = lib->creds->create(lib->creds, |
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434 | CRED_CERTIFICATE, CERT_X509, |
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435 | BUILD_SIGNING_KEY, private, |
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436 | BUILD_PUBLIC_KEY, public, |
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437 | BUILD_SUBJECT, id, |
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438 | BUILD_NOT_BEFORE_TIME, not_before, |
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439 | BUILD_NOT_AFTER_TIME, not_after, |
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440 | BUILD_SERIAL, serial, |
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441 | BUILD_DIGEST_ALG, HASH_SHA1, |
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442 | BUILD_X509_FLAG, X509_CA, |
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443 | BUILD_PATHLEN, X509_NO_PATH_LEN_CONSTRAINT, |
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444 | BUILD_END |
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445 | ); |
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446 | if (cert == NULL) |
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447 | errx(1, "couldn't build cert :("); |
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448 | |
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449 | DESTROY_IF(id); |
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450 | DESTROY_IF(public); |
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451 | free(serial.ptr); |
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452 | |
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453 | return cert; |
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454 | } |
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455 | |
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456 | #define BYTES_PER_LINE 64 |
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457 | |
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458 | // thx libstrongswan |
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459 | static void _encode_base64(FILE *out, chunk_t encoding) { |
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460 | int start; |
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461 | |
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462 | chunk_t b64 = chunk_to_base64(encoding, NULL); |
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463 | |
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464 | fprintf(out, "-----BEGIN CERTIFICATE-----\n"); |
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465 | |
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466 | for (start = 0; start < b64.len; start += BYTES_PER_LINE) { |
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467 | int left = b64.len - start; |
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468 | int len = left < BYTES_PER_LINE ? left : BYTES_PER_LINE; |
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469 | fwrite(b64.ptr + start, len, 1, out); |
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470 | fprintf(out, "\n"); |
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471 | } |
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472 | |
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473 | fprintf(out, "-----END CERTIFICATE-----\n"); |
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474 | |
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475 | free(b64.ptr); |
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476 | } |
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