1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 2014 - 2019, Steve Holme, <steve_holme@hotmail.com>.
9 * Copyright (C) 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
10 *
11 * This software is licensed as described in the file COPYING, which
12 * you should have received as part of this distribution. The terms
13 * are also available at https://curl.haxx.se/docs/copyright.html.
14 *
15 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
16 * copies of the Software, and permit persons to whom the Software is
17 * furnished to do so, under the terms of the COPYING file.
18 *
19 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
20 * KIND, either express or implied.
21 *
22 * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
23 *
24 ***************************************************************************/
25
26 #include "curl_setup.h"
27
28 #if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
29
30 #include <curl/curl.h>
31
32 #include "vauth/vauth.h"
33 #include "curl_sasl.h"
34 #include "urldata.h"
35 #include "curl_base64.h"
36 #include "curl_gssapi.h"
37 #include "sendf.h"
38 #include "curl_printf.h"
39
40 /* The last #include files should be: */
41 #include "curl_memory.h"
42 #include "memdebug.h"
43
44 /*
45 * Curl_auth_is_gssapi_supported()
46 *
47 * This is used to evaluate if GSSAPI (Kerberos V5) is supported.
48 *
49 * Parameters: None
50 *
51 * Returns TRUE if Kerberos V5 is supported by the GSS-API library.
52 */
Curl_auth_is_gssapi_supported(void)53 bool Curl_auth_is_gssapi_supported(void)
54 {
55 return TRUE;
56 }
57
58 /*
59 * Curl_auth_create_gssapi_user_message()
60 *
61 * This is used to generate an already encoded GSSAPI (Kerberos V5) user token
62 * message ready for sending to the recipient.
63 *
64 * Parameters:
65 *
66 * data [in] - The session handle.
67 * userp [in] - The user name.
68 * passwdp [in] - The user's password.
69 * service [in] - The service type such as http, smtp, pop or imap.
70 * host [in[ - The host name.
71 * mutual_auth [in] - Flag specifying whether or not mutual authentication
72 * is enabled.
73 * chlg64 [in] - Pointer to the optional base64 encoded challenge
74 * message.
75 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
76 * outptr [in/out] - The address where a pointer to newly allocated memory
77 * holding the result will be stored upon completion.
78 * outlen [out] - The length of the output message.
79 *
80 * Returns CURLE_OK on success.
81 */
Curl_auth_create_gssapi_user_message(struct Curl_easy * data,const char * userp,const char * passwdp,const char * service,const char * host,const bool mutual_auth,const char * chlg64,struct kerberos5data * krb5,char ** outptr,size_t * outlen)82 CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
83 const char *userp,
84 const char *passwdp,
85 const char *service,
86 const char *host,
87 const bool mutual_auth,
88 const char *chlg64,
89 struct kerberos5data *krb5,
90 char **outptr, size_t *outlen)
91 {
92 CURLcode result = CURLE_OK;
93 size_t chlglen = 0;
94 unsigned char *chlg = NULL;
95 OM_uint32 major_status;
96 OM_uint32 minor_status;
97 OM_uint32 unused_status;
98 gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
99 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
100 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
101
102 (void) userp;
103 (void) passwdp;
104
105 if(!krb5->spn) {
106 /* Generate our SPN */
107 char *spn = Curl_auth_build_spn(service, NULL, host);
108 if(!spn)
109 return CURLE_OUT_OF_MEMORY;
110
111 /* Populate the SPN structure */
112 spn_token.value = spn;
113 spn_token.length = strlen(spn);
114
115 /* Import the SPN */
116 major_status = gss_import_name(&minor_status, &spn_token,
117 GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
118 if(GSS_ERROR(major_status)) {
119 Curl_gss_log_error(data, "gss_import_name() failed: ",
120 major_status, minor_status);
121
122 free(spn);
123
124 return CURLE_AUTH_ERROR;
125 }
126
127 free(spn);
128 }
129
130 if(chlg64 && *chlg64) {
131 /* Decode the base-64 encoded challenge message */
132 if(*chlg64 != '=') {
133 result = Curl_base64_decode(chlg64, &chlg, &chlglen);
134 if(result)
135 return result;
136 }
137
138 /* Ensure we have a valid challenge message */
139 if(!chlg) {
140 infof(data, "GSSAPI handshake failure (empty challenge message)\n");
141
142 return CURLE_BAD_CONTENT_ENCODING;
143 }
144
145 /* Setup the challenge "input" security buffer */
146 input_token.value = chlg;
147 input_token.length = chlglen;
148 }
149
150 major_status = Curl_gss_init_sec_context(data,
151 &minor_status,
152 &krb5->context,
153 krb5->spn,
154 &Curl_krb5_mech_oid,
155 GSS_C_NO_CHANNEL_BINDINGS,
156 &input_token,
157 &output_token,
158 mutual_auth,
159 NULL);
160
161 /* Free the decoded challenge as it is not required anymore */
162 free(input_token.value);
163
164 if(GSS_ERROR(major_status)) {
165 if(output_token.value)
166 gss_release_buffer(&unused_status, &output_token);
167
168 Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
169 major_status, minor_status);
170
171 return CURLE_AUTH_ERROR;
172 }
173
174 if(output_token.value && output_token.length) {
175 /* Base64 encode the response */
176 result = Curl_base64_encode(data, (char *) output_token.value,
177 output_token.length, outptr, outlen);
178
179 gss_release_buffer(&unused_status, &output_token);
180 }
181 else if(mutual_auth) {
182 *outptr = strdup("");
183 if(!*outptr)
184 result = CURLE_OUT_OF_MEMORY;
185 }
186
187 return result;
188 }
189
190 /*
191 * Curl_auth_create_gssapi_security_message()
192 *
193 * This is used to generate an already encoded GSSAPI (Kerberos V5) security
194 * token message ready for sending to the recipient.
195 *
196 * Parameters:
197 *
198 * data [in] - The session handle.
199 * chlg64 [in] - Pointer to the optional base64 encoded challenge message.
200 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
201 * outptr [in/out] - The address where a pointer to newly allocated memory
202 * holding the result will be stored upon completion.
203 * outlen [out] - The length of the output message.
204 *
205 * Returns CURLE_OK on success.
206 */
Curl_auth_create_gssapi_security_message(struct Curl_easy * data,const char * chlg64,struct kerberos5data * krb5,char ** outptr,size_t * outlen)207 CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data,
208 const char *chlg64,
209 struct kerberos5data *krb5,
210 char **outptr,
211 size_t *outlen)
212 {
213 CURLcode result = CURLE_OK;
214 size_t chlglen = 0;
215 size_t messagelen = 0;
216 unsigned char *chlg = NULL;
217 unsigned char *message = NULL;
218 OM_uint32 major_status;
219 OM_uint32 minor_status;
220 OM_uint32 unused_status;
221 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
222 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
223 unsigned int indata = 0;
224 unsigned int outdata = 0;
225 gss_qop_t qop = GSS_C_QOP_DEFAULT;
226 unsigned int sec_layer = 0;
227 unsigned int max_size = 0;
228 gss_name_t username = GSS_C_NO_NAME;
229 gss_buffer_desc username_token;
230
231 /* Decode the base-64 encoded input message */
232 if(strlen(chlg64) && *chlg64 != '=') {
233 result = Curl_base64_decode(chlg64, &chlg, &chlglen);
234 if(result)
235 return result;
236 }
237
238 /* Ensure we have a valid challenge message */
239 if(!chlg) {
240 infof(data, "GSSAPI handshake failure (empty security message)\n");
241
242 return CURLE_BAD_CONTENT_ENCODING;
243 }
244
245 /* Get the fully qualified username back from the context */
246 major_status = gss_inquire_context(&minor_status, krb5->context,
247 &username, NULL, NULL, NULL, NULL,
248 NULL, NULL);
249 if(GSS_ERROR(major_status)) {
250 Curl_gss_log_error(data, "gss_inquire_context() failed: ",
251 major_status, minor_status);
252
253 free(chlg);
254
255 return CURLE_AUTH_ERROR;
256 }
257
258 /* Convert the username from internal format to a displayable token */
259 major_status = gss_display_name(&minor_status, username,
260 &username_token, NULL);
261 if(GSS_ERROR(major_status)) {
262 Curl_gss_log_error(data, "gss_display_name() failed: ",
263 major_status, minor_status);
264
265 free(chlg);
266
267 return CURLE_AUTH_ERROR;
268 }
269
270 /* Setup the challenge "input" security buffer */
271 input_token.value = chlg;
272 input_token.length = chlglen;
273
274 /* Decrypt the inbound challenge and obtain the qop */
275 major_status = gss_unwrap(&minor_status, krb5->context, &input_token,
276 &output_token, NULL, &qop);
277 if(GSS_ERROR(major_status)) {
278 Curl_gss_log_error(data, "gss_unwrap() failed: ",
279 major_status, minor_status);
280
281 gss_release_buffer(&unused_status, &username_token);
282 free(chlg);
283
284 return CURLE_BAD_CONTENT_ENCODING;
285 }
286
287 /* Not 4 octets long so fail as per RFC4752 Section 3.1 */
288 if(output_token.length != 4) {
289 infof(data, "GSSAPI handshake failure (invalid security data)\n");
290
291 gss_release_buffer(&unused_status, &username_token);
292 free(chlg);
293
294 return CURLE_BAD_CONTENT_ENCODING;
295 }
296
297 /* Copy the data out and free the challenge as it is not required anymore */
298 memcpy(&indata, output_token.value, 4);
299 gss_release_buffer(&unused_status, &output_token);
300 free(chlg);
301
302 /* Extract the security layer */
303 sec_layer = indata & 0x000000FF;
304 if(!(sec_layer & GSSAUTH_P_NONE)) {
305 infof(data, "GSSAPI handshake failure (invalid security layer)\n");
306
307 gss_release_buffer(&unused_status, &username_token);
308
309 return CURLE_BAD_CONTENT_ENCODING;
310 }
311
312 /* Extract the maximum message size the server can receive */
313 max_size = ntohl(indata & 0xFFFFFF00);
314 if(max_size > 0) {
315 /* The server has told us it supports a maximum receive buffer, however, as
316 we don't require one unless we are encrypting data, we tell the server
317 our receive buffer is zero. */
318 max_size = 0;
319 }
320
321 /* Allocate our message */
322 messagelen = sizeof(outdata) + username_token.length + 1;
323 message = malloc(messagelen);
324 if(!message) {
325 gss_release_buffer(&unused_status, &username_token);
326
327 return CURLE_OUT_OF_MEMORY;
328 }
329
330 /* Populate the message with the security layer, client supported receive
331 message size and authorization identity including the 0x00 based
332 terminator. Note: Despite RFC4752 Section 3.1 stating "The authorization
333 identity is not terminated with the zero-valued (%x00) octet." it seems
334 necessary to include it. */
335 outdata = htonl(max_size) | sec_layer;
336 memcpy(message, &outdata, sizeof(outdata));
337 memcpy(message + sizeof(outdata), username_token.value,
338 username_token.length);
339 message[messagelen - 1] = '\0';
340
341 /* Free the username token as it is not required anymore */
342 gss_release_buffer(&unused_status, &username_token);
343
344 /* Setup the "authentication data" security buffer */
345 input_token.value = message;
346 input_token.length = messagelen;
347
348 /* Encrypt the data */
349 major_status = gss_wrap(&minor_status, krb5->context, 0,
350 GSS_C_QOP_DEFAULT, &input_token, NULL,
351 &output_token);
352 if(GSS_ERROR(major_status)) {
353 Curl_gss_log_error(data, "gss_wrap() failed: ",
354 major_status, minor_status);
355
356 free(message);
357
358 return CURLE_AUTH_ERROR;
359 }
360
361 /* Base64 encode the response */
362 result = Curl_base64_encode(data, (char *) output_token.value,
363 output_token.length, outptr, outlen);
364
365 /* Free the output buffer */
366 gss_release_buffer(&unused_status, &output_token);
367
368 /* Free the message buffer */
369 free(message);
370
371 return result;
372 }
373
374 /*
375 * Curl_auth_cleanup_gssapi()
376 *
377 * This is used to clean up the GSSAPI (Kerberos V5) specific data.
378 *
379 * Parameters:
380 *
381 * krb5 [in/out] - The Kerberos 5 data struct being cleaned up.
382 *
383 */
Curl_auth_cleanup_gssapi(struct kerberos5data * krb5)384 void Curl_auth_cleanup_gssapi(struct kerberos5data *krb5)
385 {
386 OM_uint32 minor_status;
387
388 /* Free our security context */
389 if(krb5->context != GSS_C_NO_CONTEXT) {
390 gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
391 krb5->context = GSS_C_NO_CONTEXT;
392 }
393
394 /* Free the SPN */
395 if(krb5->spn != GSS_C_NO_NAME) {
396 gss_release_name(&minor_status, &krb5->spn);
397 krb5->spn = GSS_C_NO_NAME;
398 }
399 }
400
401 #endif /* HAVE_GSSAPI && USE_KERBEROS5 */
402