1 | /***************************************************************************
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2 | * _ _ ____ _
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3 | * Project ___| | | | _ \| |
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4 | * / __| | | | |_) | |
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5 | * | (__| |_| | _ <| |___
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6 | * \___|\___/|_| \_\_____|
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7 | *
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8 | * Copyright (C) 2014 - 2015, Steve Holme, <steve_holme@hotmail.com>.
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9 | * Copyright (C) 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
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10 | *
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11 | * This software is licensed as described in the file COPYING, which
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12 | * you should have received as part of this distribution. The terms
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13 | * are also available at https://curl.haxx.se/docs/copyright.html.
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14 | *
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15 | * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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16 | * copies of the Software, and permit persons to whom the Software is
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17 | * furnished to do so, under the terms of the COPYING file.
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18 | *
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19 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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20 | * KIND, either express or implied.
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21 | *
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22 | * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
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23 | *
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24 | ***************************************************************************/
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25 |
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26 | #include "curl_setup.h"
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27 |
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28 | #if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
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29 |
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30 | #include <curl/curl.h>
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31 |
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32 | #include "curl_sasl.h"
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33 | #include "urldata.h"
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34 | #include "curl_base64.h"
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35 | #include "curl_gssapi.h"
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36 | #include "sendf.h"
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37 | #include "curl_printf.h"
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38 |
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39 | /* The last #include files should be: */
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40 | #include "curl_memory.h"
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41 | #include "memdebug.h"
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42 |
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43 | /*
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44 | * Curl_sasl_build_gssapi_spn()
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45 | *
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46 | * This is used to build a SPN string in the format service@instance.
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47 | *
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48 | * Parameters:
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49 | *
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50 | * service [in] - The service type such as www, smtp, pop or imap.
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51 | * instance [in] - The host name or realm.
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52 | *
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53 | * Returns a pointer to the newly allocated SPN.
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54 | */
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55 | char *Curl_sasl_build_gssapi_spn(const char *service, const char *instance)
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56 | {
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57 | /* Generate and return our SPN */
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58 | return aprintf("%s@%s", service, instance);
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59 | }
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60 |
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61 | /*
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62 | * Curl_sasl_create_gssapi_user_message()
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63 | *
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64 | * This is used to generate an already encoded GSSAPI (Kerberos V5) user token
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65 | * message ready for sending to the recipient.
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66 | *
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67 | * Parameters:
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68 | *
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69 | * data [in] - The session handle.
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70 | * userp [in] - The user name.
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71 | * passdwp [in] - The user's password.
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72 | * service [in] - The service type such as www, smtp, pop or imap.
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73 | * mutual_auth [in] - Flag specifing whether or not mutual authentication
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74 | * is enabled.
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75 | * chlg64 [in] - Pointer to the optional base64 encoded challenge
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76 | * message.
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77 | * krb5 [in/out] - The gssapi data struct being used and modified.
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78 | * outptr [in/out] - The address where a pointer to newly allocated memory
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79 | * holding the result will be stored upon completion.
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80 | * outlen [out] - The length of the output message.
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81 | *
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82 | * Returns CURLE_OK on success.
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83 | */
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84 | CURLcode Curl_sasl_create_gssapi_user_message(struct SessionHandle *data,
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85 | const char *userp,
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86 | const char *passwdp,
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87 | const char *service,
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88 | const bool mutual_auth,
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89 | const char *chlg64,
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90 | struct kerberos5data *krb5,
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91 | char **outptr, size_t *outlen)
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92 | {
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93 | CURLcode result = CURLE_OK;
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94 | size_t chlglen = 0;
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95 | unsigned char *chlg = NULL;
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96 | OM_uint32 gss_status;
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97 | OM_uint32 gss_major_status;
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98 | OM_uint32 gss_minor_status;
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99 | gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
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100 | gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
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101 | gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
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102 |
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103 | (void) userp;
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104 | (void) passwdp;
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105 |
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106 | if(krb5->context == GSS_C_NO_CONTEXT) {
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107 | /* Generate our SPN */
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108 | char *spn = Curl_sasl_build_gssapi_spn(service,
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109 | data->easy_conn->host.name);
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110 | if(!spn)
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111 | return CURLE_OUT_OF_MEMORY;
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112 |
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113 | /* Populate the SPN structure */
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114 | spn_token.value = spn;
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115 | spn_token.length = strlen(spn);
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116 |
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117 | /* Import the SPN */
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118 | gss_major_status = gss_import_name(&gss_minor_status, &spn_token,
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119 | GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
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120 | if(GSS_ERROR(gss_major_status)) {
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121 | Curl_gss_log_error(data, gss_minor_status, "gss_import_name() failed: ");
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122 |
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123 | free(spn);
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124 |
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125 | return CURLE_OUT_OF_MEMORY;
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126 | }
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127 |
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128 | free(spn);
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129 | }
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130 | else {
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131 | /* Decode the base-64 encoded challenge message */
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132 | if(strlen(chlg64) && *chlg64 != '=') {
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133 | result = Curl_base64_decode(chlg64, &chlg, &chlglen);
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134 | if(result)
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135 | return result;
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136 | }
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137 |
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138 | /* Ensure we have a valid challenge message */
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139 | if(!chlg) {
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140 | infof(data, "GSSAPI handshake failure (empty challenge message)\n");
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141 |
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142 | return CURLE_BAD_CONTENT_ENCODING;
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143 | }
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144 |
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145 | /* Setup the challenge "input" security buffer */
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146 | input_token.value = chlg;
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147 | input_token.length = chlglen;
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148 | }
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149 |
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150 | gss_major_status = Curl_gss_init_sec_context(data,
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151 | &gss_minor_status,
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152 | &krb5->context,
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153 | krb5->spn,
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154 | &Curl_krb5_mech_oid,
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155 | GSS_C_NO_CHANNEL_BINDINGS,
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156 | &input_token,
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157 | &output_token,
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158 | mutual_auth,
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159 | NULL);
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160 |
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161 | free(input_token.value);
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162 |
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163 | if(GSS_ERROR(gss_major_status)) {
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164 | if(output_token.value)
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165 | gss_release_buffer(&gss_status, &output_token);
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166 |
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167 | Curl_gss_log_error(data, gss_minor_status,
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168 | "gss_init_sec_context() failed: ");
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169 |
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170 | return CURLE_RECV_ERROR;
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171 | }
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172 |
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173 | if(output_token.value && output_token.length) {
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174 | /* Base64 encode the response */
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175 | result = Curl_base64_encode(data, (char *) output_token.value,
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176 | output_token.length, outptr, outlen);
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177 |
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178 | gss_release_buffer(&gss_status, &output_token);
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179 | }
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180 |
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181 | return result;
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182 | }
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183 |
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184 | /*
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185 | * Curl_sasl_create_gssapi_security_message()
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186 | *
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187 | * This is used to generate an already encoded GSSAPI (Kerberos V5) security
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188 | * token message ready for sending to the recipient.
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189 | *
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190 | * Parameters:
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191 | *
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192 | * data [in] - The session handle.
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193 | * chlg64 [in] - Pointer to the optional base64 encoded challenge message.
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194 | * krb5 [in/out] - The gssapi data struct being used and modified.
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195 | * outptr [in/out] - The address where a pointer to newly allocated memory
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196 | * holding the result will be stored upon completion.
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197 | * outlen [out] - The length of the output message.
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198 | *
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199 | * Returns CURLE_OK on success.
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200 | */
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201 | CURLcode Curl_sasl_create_gssapi_security_message(struct SessionHandle *data,
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202 | const char *chlg64,
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203 | struct kerberos5data *krb5,
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204 | char **outptr,
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205 | size_t *outlen)
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206 | {
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207 | CURLcode result = CURLE_OK;
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208 | size_t chlglen = 0;
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209 | size_t messagelen = 0;
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210 | unsigned char *chlg = NULL;
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211 | unsigned char *message = NULL;
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212 | OM_uint32 gss_status;
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213 | OM_uint32 gss_major_status;
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214 | OM_uint32 gss_minor_status;
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215 | gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
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216 | gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
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217 | unsigned int indata = 0;
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218 | unsigned int outdata = 0;
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219 | gss_qop_t qop = GSS_C_QOP_DEFAULT;
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220 | unsigned int sec_layer = 0;
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221 | unsigned int max_size = 0;
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222 | gss_name_t username = GSS_C_NO_NAME;
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223 | gss_buffer_desc username_token;
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224 |
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225 | /* Decode the base-64 encoded input message */
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226 | if(strlen(chlg64) && *chlg64 != '=') {
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227 | result = Curl_base64_decode(chlg64, &chlg, &chlglen);
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228 | if(result)
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229 | return result;
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230 | }
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231 |
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232 | /* Ensure we have a valid challenge message */
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233 | if(!chlg) {
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234 | infof(data, "GSSAPI handshake failure (empty security message)\n");
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235 |
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236 | return CURLE_BAD_CONTENT_ENCODING;
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237 | }
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238 |
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239 | /* Get the fully qualified username back from the context */
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240 | gss_major_status = gss_inquire_context(&gss_minor_status, krb5->context,
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241 | &username, NULL, NULL, NULL, NULL,
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242 | NULL, NULL);
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243 | if(GSS_ERROR(gss_major_status)) {
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244 | Curl_gss_log_error(data, gss_minor_status,
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245 | "gss_inquire_context() failed: ");
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246 |
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247 | free(chlg);
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248 |
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249 | return CURLE_OUT_OF_MEMORY;
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250 | }
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251 |
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252 | /* Convert the username from internal format to a displayable token */
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253 | gss_major_status = gss_display_name(&gss_minor_status, username,
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254 | &username_token, NULL);
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255 | if(GSS_ERROR(gss_major_status)) {
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256 | Curl_gss_log_error(data, gss_minor_status, "gss_display_name() failed: ");
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257 |
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258 | free(chlg);
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259 |
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260 | return CURLE_OUT_OF_MEMORY;
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261 | }
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262 |
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263 | /* Setup the challenge "input" security buffer */
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264 | input_token.value = chlg;
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265 | input_token.length = chlglen;
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266 |
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267 | /* Decrypt the inbound challenge and obtain the qop */
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268 | gss_major_status = gss_unwrap(&gss_minor_status, krb5->context, &input_token,
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269 | &output_token, NULL, &qop);
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270 | if(GSS_ERROR(gss_major_status)) {
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271 | Curl_gss_log_error(data, gss_minor_status, "gss_unwrap() failed: ");
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272 |
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273 | gss_release_buffer(&gss_status, &username_token);
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274 | free(chlg);
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275 |
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276 | return CURLE_BAD_CONTENT_ENCODING;
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277 | }
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278 |
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279 | /* Not 4 octets long so fail as per RFC4752 Section 3.1 */
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280 | if(output_token.length != 4) {
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281 | infof(data, "GSSAPI handshake failure (invalid security data)\n");
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282 |
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283 | gss_release_buffer(&gss_status, &username_token);
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284 | free(chlg);
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285 |
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286 | return CURLE_BAD_CONTENT_ENCODING;
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287 | }
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288 |
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289 | /* Copy the data out and free the challenge as it is not required anymore */
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290 | memcpy(&indata, output_token.value, 4);
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291 | gss_release_buffer(&gss_status, &output_token);
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292 | free(chlg);
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293 |
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294 | /* Extract the security layer */
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295 | sec_layer = indata & 0x000000FF;
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296 | if(!(sec_layer & GSSAUTH_P_NONE)) {
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297 | infof(data, "GSSAPI handshake failure (invalid security layer)\n");
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298 |
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299 | gss_release_buffer(&gss_status, &username_token);
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300 |
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301 | return CURLE_BAD_CONTENT_ENCODING;
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302 | }
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303 |
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304 | /* Extract the maximum message size the server can receive */
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305 | max_size = ntohl(indata & 0xFFFFFF00);
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306 | if(max_size > 0) {
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307 | /* The server has told us it supports a maximum receive buffer, however, as
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308 | we don't require one unless we are encrypting data, we tell the server
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309 | our receive buffer is zero. */
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310 | max_size = 0;
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311 | }
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312 |
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313 | /* Allocate our message */
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314 | messagelen = sizeof(outdata) + username_token.length + 1;
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315 | message = malloc(messagelen);
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316 | if(!message) {
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317 | gss_release_buffer(&gss_status, &username_token);
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318 |
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319 | return CURLE_OUT_OF_MEMORY;
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320 | }
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321 |
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322 | /* Populate the message with the security layer, client supported receive
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323 | message size and authorization identity including the 0x00 based
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324 | terminator. Note: Dispite RFC4752 Section 3.1 stating "The authorization
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325 | identity is not terminated with the zero-valued (%x00) octet." it seems
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326 | necessary to include it. */
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327 | outdata = htonl(max_size) | sec_layer;
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328 | memcpy(message, &outdata, sizeof(outdata));
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329 | memcpy(message + sizeof(outdata), username_token.value,
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330 | username_token.length);
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331 | message[messagelen - 1] = '\0';
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332 |
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333 | /* Free the username token as it is not required anymore */
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334 | gss_release_buffer(&gss_status, &username_token);
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335 |
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336 | /* Setup the "authentication data" security buffer */
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337 | input_token.value = message;
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338 | input_token.length = messagelen;
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339 |
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340 | /* Encrypt the data */
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341 | gss_major_status = gss_wrap(&gss_minor_status, krb5->context, 0,
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342 | GSS_C_QOP_DEFAULT, &input_token, NULL,
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343 | &output_token);
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344 | if(GSS_ERROR(gss_major_status)) {
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345 | Curl_gss_log_error(data, gss_minor_status, "gss_wrap() failed: ");
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346 |
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347 | free(message);
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348 |
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349 | return CURLE_OUT_OF_MEMORY;
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350 | }
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351 |
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352 | /* Base64 encode the response */
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353 | result = Curl_base64_encode(data, (char *) output_token.value,
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354 | output_token.length, outptr, outlen);
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355 |
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356 | /* Free the output buffer */
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357 | gss_release_buffer(&gss_status, &output_token);
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358 |
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359 | /* Free the message buffer */
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360 | free(message);
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361 |
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362 | return result;
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363 | }
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364 |
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365 | /*
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366 | * Curl_sasl_gssapi_cleanup()
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367 | *
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368 | * This is used to clean up the gssapi specific data.
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369 | *
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370 | * Parameters:
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371 | *
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372 | * krb5 [in/out] - The kerberos 5 data struct being cleaned up.
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373 | *
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374 | */
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375 | void Curl_sasl_gssapi_cleanup(struct kerberos5data *krb5)
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376 | {
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377 | OM_uint32 minor_status;
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378 |
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379 | /* Free our security context */
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380 | if(krb5->context != GSS_C_NO_CONTEXT) {
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381 | gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
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382 | krb5->context = GSS_C_NO_CONTEXT;
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383 | }
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384 |
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385 | /* Free the SPN */
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386 | if(krb5->spn != GSS_C_NO_NAME) {
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387 | gss_release_name(&minor_status, &krb5->spn);
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388 | krb5->spn = GSS_C_NO_NAME;
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389 | }
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390 | }
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391 |
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392 | #endif /* HAVE_GSSAPI && USE_KERBEROS5 */
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