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1 /***************************************************************************
2  *                                  _   _ ____  _
3  *  Project                     ___| | | |  _ \| |
4  *                             / __| | | | |_) | |
5  *                            | (__| |_| |  _ <| |___
6  *                             \___|\___/|_| \_\_____|
7  *
8  * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9  *
10  * This software is licensed as described in the file COPYING, which
11  * you should have received as part of this distribution. The terms
12  * are also available at https://curl.se/docs/copyright.html.
13  *
14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15  * copies of the Software, and permit persons to whom the Software is
16  * furnished to do so, under the terms of the COPYING file.
17  *
18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19  * KIND, either express or implied.
20  *
21  * SPDX-License-Identifier: curl
22  *
23  * RFC4178 Simple and Protected GSS-API Negotiation Mechanism
24  *
25  ***************************************************************************/
26 
27 #include "curl_setup.h"
28 
29 #if defined(HAVE_GSSAPI) && defined(USE_SPNEGO)
30 
31 #include <curl/curl.h>
32 
33 #include "vauth/vauth.h"
34 #include "urldata.h"
35 #include "curl_base64.h"
36 #include "curl_gssapi.h"
37 #include "warnless.h"
38 #include "curl_multibyte.h"
39 #include "sendf.h"
40 
41 /* The last #include files should be: */
42 #include "curl_memory.h"
43 #include "memdebug.h"
44 
45 /*
46  * Curl_auth_is_spnego_supported()
47  *
48  * This is used to evaluate if SPNEGO (Negotiate) is supported.
49  *
50  * Parameters: None
51  *
52  * Returns TRUE if Negotiate supported by the GSS-API library.
53  */
Curl_auth_is_spnego_supported(void)54 bool Curl_auth_is_spnego_supported(void)
55 {
56   return TRUE;
57 }
58 
59 /*
60  * Curl_auth_decode_spnego_message()
61  *
62  * This is used to decode an already encoded SPNEGO (Negotiate) challenge
63  * message.
64  *
65  * Parameters:
66  *
67  * data        [in]     - The session handle.
68  * userp       [in]     - The user name in the format User or Domain\User.
69  * passwdp     [in]     - The user's password.
70  * service     [in]     - The service type such as http, smtp, pop or imap.
71  * host        [in]     - The host name.
72  * chlg64      [in]     - The optional base64 encoded challenge message.
73  * nego        [in/out] - The Negotiate data struct being used and modified.
74  *
75  * Returns CURLE_OK on success.
76  */
Curl_auth_decode_spnego_message(struct Curl_easy * data,const char * user,const char * password,const char * service,const char * host,const char * chlg64,struct negotiatedata * nego)77 CURLcode Curl_auth_decode_spnego_message(struct Curl_easy *data,
78                                          const char *user,
79                                          const char *password,
80                                          const char *service,
81                                          const char *host,
82                                          const char *chlg64,
83                                          struct negotiatedata *nego)
84 {
85   CURLcode result = CURLE_OK;
86   size_t chlglen = 0;
87   unsigned char *chlg = NULL;
88   OM_uint32 major_status;
89   OM_uint32 minor_status;
90   OM_uint32 unused_status;
91   gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
92   gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
93   gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
94 
95   (void) user;
96   (void) password;
97 
98   if(nego->context && nego->status == GSS_S_COMPLETE) {
99     /* We finished successfully our part of authentication, but server
100      * rejected it (since we're again here). Exit with an error since we
101      * can't invent anything better */
102     Curl_auth_cleanup_spnego(nego);
103     return CURLE_LOGIN_DENIED;
104   }
105 
106   if(!nego->spn) {
107     /* Generate our SPN */
108     char *spn = Curl_auth_build_spn(service, NULL, host);
109     if(!spn)
110       return CURLE_OUT_OF_MEMORY;
111 
112     /* Populate the SPN structure */
113     spn_token.value = spn;
114     spn_token.length = strlen(spn);
115 
116     /* Import the SPN */
117     major_status = gss_import_name(&minor_status, &spn_token,
118                                    GSS_C_NT_HOSTBASED_SERVICE,
119                                    &nego->spn);
120     if(GSS_ERROR(major_status)) {
121       Curl_gss_log_error(data, "gss_import_name() failed: ",
122                          major_status, minor_status);
123 
124       free(spn);
125 
126       return CURLE_AUTH_ERROR;
127     }
128 
129     free(spn);
130   }
131 
132   if(chlg64 && *chlg64) {
133     /* Decode the base-64 encoded challenge message */
134     if(*chlg64 != '=') {
135       result = Curl_base64_decode(chlg64, &chlg, &chlglen);
136       if(result)
137         return result;
138     }
139 
140     /* Ensure we have a valid challenge message */
141     if(!chlg) {
142       infof(data, "SPNEGO handshake failure (empty challenge message)");
143       return CURLE_BAD_CONTENT_ENCODING;
144     }
145 
146     /* Setup the challenge "input" security buffer */
147     input_token.value = chlg;
148     input_token.length = chlglen;
149   }
150 
151   /* Generate our challenge-response message */
152   major_status = Curl_gss_init_sec_context(data,
153                                            &minor_status,
154                                            &nego->context,
155                                            nego->spn,
156                                            &Curl_spnego_mech_oid,
157                                            GSS_C_NO_CHANNEL_BINDINGS,
158                                            &input_token,
159                                            &output_token,
160                                            TRUE,
161                                            NULL);
162 
163   /* Free the decoded challenge as it is not required anymore */
164   Curl_safefree(input_token.value);
165 
166   nego->status = major_status;
167   if(GSS_ERROR(major_status)) {
168     if(output_token.value)
169       gss_release_buffer(&unused_status, &output_token);
170 
171     Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
172                        major_status, minor_status);
173 
174     return CURLE_AUTH_ERROR;
175   }
176 
177   if(!output_token.value || !output_token.length) {
178     if(output_token.value)
179       gss_release_buffer(&unused_status, &output_token);
180 
181     return CURLE_AUTH_ERROR;
182   }
183 
184   /* Free previous token */
185   if(nego->output_token.length && nego->output_token.value)
186     gss_release_buffer(&unused_status, &nego->output_token);
187 
188   nego->output_token = output_token;
189 
190   return CURLE_OK;
191 }
192 
193 /*
194  * Curl_auth_create_spnego_message()
195  *
196  * This is used to generate an already encoded SPNEGO (Negotiate) response
197  * message ready for sending to the recipient.
198  *
199  * Parameters:
200  *
201  * data        [in]     - The session handle.
202  * nego        [in/out] - The Negotiate data struct being used and modified.
203  * outptr      [in/out] - The address where a pointer to newly allocated memory
204  *                        holding the result will be stored upon completion.
205  * outlen      [out]    - The length of the output message.
206  *
207  * Returns CURLE_OK on success.
208  */
Curl_auth_create_spnego_message(struct negotiatedata * nego,char ** outptr,size_t * outlen)209 CURLcode Curl_auth_create_spnego_message(struct negotiatedata *nego,
210                                          char **outptr, size_t *outlen)
211 {
212   CURLcode result;
213   OM_uint32 minor_status;
214 
215   /* Base64 encode the already generated response */
216   result = Curl_base64_encode(nego->output_token.value,
217                               nego->output_token.length,
218                               outptr, outlen);
219 
220   if(result) {
221     gss_release_buffer(&minor_status, &nego->output_token);
222     nego->output_token.value = NULL;
223     nego->output_token.length = 0;
224 
225     return result;
226   }
227 
228   if(!*outptr || !*outlen) {
229     gss_release_buffer(&minor_status, &nego->output_token);
230     nego->output_token.value = NULL;
231     nego->output_token.length = 0;
232 
233     return CURLE_REMOTE_ACCESS_DENIED;
234   }
235 
236   return CURLE_OK;
237 }
238 
239 /*
240  * Curl_auth_cleanup_spnego()
241  *
242  * This is used to clean up the SPNEGO (Negotiate) specific data.
243  *
244  * Parameters:
245  *
246  * nego     [in/out] - The Negotiate data struct being cleaned up.
247  *
248  */
Curl_auth_cleanup_spnego(struct negotiatedata * nego)249 void Curl_auth_cleanup_spnego(struct negotiatedata *nego)
250 {
251   OM_uint32 minor_status;
252 
253   /* Free our security context */
254   if(nego->context != GSS_C_NO_CONTEXT) {
255     gss_delete_sec_context(&minor_status, &nego->context, GSS_C_NO_BUFFER);
256     nego->context = GSS_C_NO_CONTEXT;
257   }
258 
259   /* Free the output token */
260   if(nego->output_token.value) {
261     gss_release_buffer(&minor_status, &nego->output_token);
262     nego->output_token.value = NULL;
263     nego->output_token.length = 0;
264 
265   }
266 
267   /* Free the SPN */
268   if(nego->spn != GSS_C_NO_NAME) {
269     gss_release_name(&minor_status, &nego->spn);
270     nego->spn = GSS_C_NO_NAME;
271   }
272 
273   /* Reset any variables */
274   nego->status = 0;
275   nego->noauthpersist = FALSE;
276   nego->havenoauthpersist = FALSE;
277   nego->havenegdata = FALSE;
278   nego->havemultiplerequests = FALSE;
279 }
280 
281 #endif /* HAVE_GSSAPI && USE_SPNEGO */
282