1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 2014 - 2019, Steve Holme, <steve_holme@hotmail.com>.
9 * Copyright (C) 2015 - 2021, 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.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_gssapi.h"
36 #include "sendf.h"
37 #include "curl_printf.h"
38
39 /* The last #include files should be: */
40 #include "curl_memory.h"
41 #include "memdebug.h"
42
43 /*
44 * Curl_auth_is_gssapi_supported()
45 *
46 * This is used to evaluate if GSSAPI (Kerberos V5) is supported.
47 *
48 * Parameters: None
49 *
50 * Returns TRUE if Kerberos V5 is supported by the GSS-API library.
51 */
Curl_auth_is_gssapi_supported(void)52 bool Curl_auth_is_gssapi_supported(void)
53 {
54 return TRUE;
55 }
56
57 /*
58 * Curl_auth_create_gssapi_user_message()
59 *
60 * This is used to generate an already encoded GSSAPI (Kerberos V5) user token
61 * message ready for sending to the recipient.
62 *
63 * Parameters:
64 *
65 * data [in] - The session handle.
66 * userp [in] - The user name.
67 * passwdp [in] - The user's password.
68 * service [in] - The service type such as http, smtp, pop or imap.
69 * host [in[ - The host name.
70 * mutual_auth [in] - Flag specifying whether or not mutual authentication
71 * is enabled.
72 * chlg [in] - Optional challenge message.
73 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
74 * out [out] - The result storage.
75 *
76 * Returns CURLE_OK on success.
77 */
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 struct bufref * chlg,struct kerberos5data * krb5,struct bufref * out)78 CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
79 const char *userp,
80 const char *passwdp,
81 const char *service,
82 const char *host,
83 const bool mutual_auth,
84 const struct bufref *chlg,
85 struct kerberos5data *krb5,
86 struct bufref *out)
87 {
88 CURLcode result = CURLE_OK;
89 OM_uint32 major_status;
90 OM_uint32 minor_status;
91 OM_uint32 unused_status;
92 gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
93 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
94 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
95
96 (void) userp;
97 (void) passwdp;
98
99 if(!krb5->spn) {
100 /* Generate our SPN */
101 char *spn = Curl_auth_build_spn(service, NULL, host);
102 if(!spn)
103 return CURLE_OUT_OF_MEMORY;
104
105 /* Populate the SPN structure */
106 spn_token.value = spn;
107 spn_token.length = strlen(spn);
108
109 /* Import the SPN */
110 major_status = gss_import_name(&minor_status, &spn_token,
111 GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
112 if(GSS_ERROR(major_status)) {
113 Curl_gss_log_error(data, "gss_import_name() failed: ",
114 major_status, minor_status);
115
116 free(spn);
117
118 return CURLE_AUTH_ERROR;
119 }
120
121 free(spn);
122 }
123
124 if(chlg) {
125 if(!Curl_bufref_len(chlg)) {
126 infof(data, "GSSAPI handshake failure (empty challenge message)");
127 return CURLE_BAD_CONTENT_ENCODING;
128 }
129 input_token.value = (void *) Curl_bufref_ptr(chlg);
130 input_token.length = Curl_bufref_len(chlg);
131 }
132
133 major_status = Curl_gss_init_sec_context(data,
134 &minor_status,
135 &krb5->context,
136 krb5->spn,
137 &Curl_krb5_mech_oid,
138 GSS_C_NO_CHANNEL_BINDINGS,
139 &input_token,
140 &output_token,
141 mutual_auth,
142 NULL);
143
144 if(GSS_ERROR(major_status)) {
145 if(output_token.value)
146 gss_release_buffer(&unused_status, &output_token);
147
148 Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
149 major_status, minor_status);
150
151 return CURLE_AUTH_ERROR;
152 }
153
154 if(output_token.value && output_token.length) {
155 result = Curl_bufref_memdup(out, output_token.value, output_token.length);
156 gss_release_buffer(&unused_status, &output_token);
157 }
158 else
159 Curl_bufref_set(out, mutual_auth? "": NULL, 0, NULL);
160
161 return result;
162 }
163
164 /*
165 * Curl_auth_create_gssapi_security_message()
166 *
167 * This is used to generate an already encoded GSSAPI (Kerberos V5) security
168 * token message ready for sending to the recipient.
169 *
170 * Parameters:
171 *
172 * data [in] - The session handle.
173 * chlg [in] - Optional challenge message.
174 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
175 * out [out] - The result storage.
176 *
177 * Returns CURLE_OK on success.
178 */
Curl_auth_create_gssapi_security_message(struct Curl_easy * data,const struct bufref * chlg,struct kerberos5data * krb5,struct bufref * out)179 CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data,
180 const struct bufref *chlg,
181 struct kerberos5data *krb5,
182 struct bufref *out)
183 {
184 CURLcode result = CURLE_OK;
185 size_t messagelen = 0;
186 unsigned char *message = NULL;
187 OM_uint32 major_status;
188 OM_uint32 minor_status;
189 OM_uint32 unused_status;
190 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
191 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
192 unsigned int indata = 0;
193 unsigned int outdata = 0;
194 gss_qop_t qop = GSS_C_QOP_DEFAULT;
195 unsigned int sec_layer = 0;
196 unsigned int max_size = 0;
197 gss_name_t username = GSS_C_NO_NAME;
198 gss_buffer_desc username_token;
199
200 /* Ensure we have a valid challenge message */
201 if(!Curl_bufref_len(chlg)) {
202 infof(data, "GSSAPI handshake failure (empty security message)");
203 return CURLE_BAD_CONTENT_ENCODING;
204 }
205
206 /* Get the fully qualified username back from the context */
207 major_status = gss_inquire_context(&minor_status, krb5->context,
208 &username, NULL, NULL, NULL, NULL,
209 NULL, NULL);
210 if(GSS_ERROR(major_status)) {
211 Curl_gss_log_error(data, "gss_inquire_context() failed: ",
212 major_status, minor_status);
213 return CURLE_AUTH_ERROR;
214 }
215
216 /* Convert the username from internal format to a displayable token */
217 major_status = gss_display_name(&minor_status, username,
218 &username_token, NULL);
219 if(GSS_ERROR(major_status)) {
220 Curl_gss_log_error(data, "gss_display_name() failed: ",
221 major_status, minor_status);
222 return CURLE_AUTH_ERROR;
223 }
224
225 /* Setup the challenge "input" security buffer */
226 input_token.value = (void *) Curl_bufref_ptr(chlg);
227 input_token.length = Curl_bufref_len(chlg);
228
229 /* Decrypt the inbound challenge and obtain the qop */
230 major_status = gss_unwrap(&minor_status, krb5->context, &input_token,
231 &output_token, NULL, &qop);
232 if(GSS_ERROR(major_status)) {
233 Curl_gss_log_error(data, "gss_unwrap() failed: ",
234 major_status, minor_status);
235 gss_release_buffer(&unused_status, &username_token);
236 return CURLE_BAD_CONTENT_ENCODING;
237 }
238
239 /* Not 4 octets long so fail as per RFC4752 Section 3.1 */
240 if(output_token.length != 4) {
241 infof(data, "GSSAPI handshake failure (invalid security data)");
242 gss_release_buffer(&unused_status, &username_token);
243 return CURLE_BAD_CONTENT_ENCODING;
244 }
245
246 /* Copy the data out and free the challenge as it is not required anymore */
247 memcpy(&indata, output_token.value, 4);
248 gss_release_buffer(&unused_status, &output_token);
249
250 /* Extract the security layer */
251 sec_layer = indata & 0x000000FF;
252 if(!(sec_layer & GSSAUTH_P_NONE)) {
253 infof(data, "GSSAPI handshake failure (invalid security layer)");
254
255 gss_release_buffer(&unused_status, &username_token);
256 return CURLE_BAD_CONTENT_ENCODING;
257 }
258
259 /* Extract the maximum message size the server can receive */
260 max_size = ntohl(indata & 0xFFFFFF00);
261 if(max_size > 0) {
262 /* The server has told us it supports a maximum receive buffer, however, as
263 we don't require one unless we are encrypting data, we tell the server
264 our receive buffer is zero. */
265 max_size = 0;
266 }
267
268 /* Allocate our message */
269 messagelen = sizeof(outdata) + username_token.length + 1;
270 message = malloc(messagelen);
271 if(!message) {
272 gss_release_buffer(&unused_status, &username_token);
273 return CURLE_OUT_OF_MEMORY;
274 }
275
276 /* Populate the message with the security layer, client supported receive
277 message size and authorization identity including the 0x00 based
278 terminator. Note: Despite RFC4752 Section 3.1 stating "The authorization
279 identity is not terminated with the zero-valued (%x00) octet." it seems
280 necessary to include it. */
281 outdata = htonl(max_size) | sec_layer;
282 memcpy(message, &outdata, sizeof(outdata));
283 memcpy(message + sizeof(outdata), username_token.value,
284 username_token.length);
285 message[messagelen - 1] = '\0';
286
287 /* Free the username token as it is not required anymore */
288 gss_release_buffer(&unused_status, &username_token);
289
290 /* Setup the "authentication data" security buffer */
291 input_token.value = message;
292 input_token.length = messagelen;
293
294 /* Encrypt the data */
295 major_status = gss_wrap(&minor_status, krb5->context, 0,
296 GSS_C_QOP_DEFAULT, &input_token, NULL,
297 &output_token);
298 if(GSS_ERROR(major_status)) {
299 Curl_gss_log_error(data, "gss_wrap() failed: ",
300 major_status, minor_status);
301 free(message);
302 return CURLE_AUTH_ERROR;
303 }
304
305 /* Return the response. */
306 result = Curl_bufref_memdup(out, output_token.value, output_token.length);
307 /* Free the output buffer */
308 gss_release_buffer(&unused_status, &output_token);
309
310 /* Free the message buffer */
311 free(message);
312
313 return result;
314 }
315
316 /*
317 * Curl_auth_cleanup_gssapi()
318 *
319 * This is used to clean up the GSSAPI (Kerberos V5) specific data.
320 *
321 * Parameters:
322 *
323 * krb5 [in/out] - The Kerberos 5 data struct being cleaned up.
324 *
325 */
Curl_auth_cleanup_gssapi(struct kerberos5data * krb5)326 void Curl_auth_cleanup_gssapi(struct kerberos5data *krb5)
327 {
328 OM_uint32 minor_status;
329
330 /* Free our security context */
331 if(krb5->context != GSS_C_NO_CONTEXT) {
332 gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
333 krb5->context = GSS_C_NO_CONTEXT;
334 }
335
336 /* Free the SPN */
337 if(krb5->spn != GSS_C_NO_NAME) {
338 gss_release_name(&minor_status, &krb5->spn);
339 krb5->spn = GSS_C_NO_NAME;
340 }
341 }
342
343 #endif /* HAVE_GSSAPI && USE_KERBEROS5 */
344