1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Steve Holme, <steve_holme@hotmail.com>.
9 * Copyright (C) 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 * SPDX-License-Identifier: curl
23 *
24 * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
25 *
26 ***************************************************************************/
27
28 #include "curl_setup.h"
29
30 #if defined(HAVE_GSSAPI) && defined(USE_KERBEROS5)
31
32 #include <curl/curl.h>
33
34 #include "vauth/vauth.h"
35 #include "curl_sasl.h"
36 #include "urldata.h"
37 #include "curl_gssapi.h"
38 #include "sendf.h"
39 #include "curl_printf.h"
40
41 /* The last #include files should be: */
42 #include "curl_memory.h"
43 #include "memdebug.h"
44
45 #if defined(__GNUC__) && defined(__APPLE__)
46 #pragma GCC diagnostic push
47 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
48 #endif
49
50 /*
51 * Curl_auth_is_gssapi_supported()
52 *
53 * This is used to evaluate if GSSAPI (Kerberos V5) is supported.
54 *
55 * Parameters: None
56 *
57 * Returns TRUE if Kerberos V5 is supported by the GSS-API library.
58 */
Curl_auth_is_gssapi_supported(void)59 bool Curl_auth_is_gssapi_supported(void)
60 {
61 return TRUE;
62 }
63
64 /*
65 * Curl_auth_create_gssapi_user_message()
66 *
67 * This is used to generate an already encoded GSSAPI (Kerberos V5) user token
68 * message ready for sending to the recipient.
69 *
70 * Parameters:
71 *
72 * data [in] - The session handle.
73 * userp [in] - The username.
74 * passwdp [in] - The user's password.
75 * service [in] - The service type such as http, smtp, pop or imap.
76 * host [in[ - The hostname.
77 * mutual_auth [in] - Flag specifying whether or not mutual authentication
78 * is enabled.
79 * chlg [in] - Optional challenge message.
80 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
81 * out [out] - The result storage.
82 *
83 * Returns CURLE_OK on success.
84 */
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)85 CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
86 const char *userp,
87 const char *passwdp,
88 const char *service,
89 const char *host,
90 const bool mutual_auth,
91 const struct bufref *chlg,
92 struct kerberos5data *krb5,
93 struct bufref *out)
94 {
95 CURLcode result = CURLE_OK;
96 OM_uint32 major_status;
97 OM_uint32 minor_status;
98 OM_uint32 unused_status;
99 gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
100 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
101 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
102
103 (void) userp;
104 (void) passwdp;
105
106 if(!krb5->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, &krb5->spn);
119 if(GSS_ERROR(major_status)) {
120 Curl_gss_log_error(data, "gss_import_name() failed: ",
121 major_status, minor_status);
122
123 free(spn);
124
125 return CURLE_AUTH_ERROR;
126 }
127
128 free(spn);
129 }
130
131 if(chlg) {
132 if(!Curl_bufref_len(chlg)) {
133 infof(data, "GSSAPI handshake failure (empty challenge message)");
134 return CURLE_BAD_CONTENT_ENCODING;
135 }
136 input_token.value = (void *) Curl_bufref_ptr(chlg);
137 input_token.length = Curl_bufref_len(chlg);
138 }
139
140 major_status = Curl_gss_init_sec_context(data,
141 &minor_status,
142 &krb5->context,
143 krb5->spn,
144 &Curl_krb5_mech_oid,
145 GSS_C_NO_CHANNEL_BINDINGS,
146 &input_token,
147 &output_token,
148 mutual_auth,
149 NULL);
150
151 if(GSS_ERROR(major_status)) {
152 if(output_token.value)
153 gss_release_buffer(&unused_status, &output_token);
154
155 Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
156 major_status, minor_status);
157
158 return CURLE_AUTH_ERROR;
159 }
160
161 if(output_token.value && output_token.length) {
162 result = Curl_bufref_memdup(out, output_token.value, output_token.length);
163 gss_release_buffer(&unused_status, &output_token);
164 }
165 else
166 Curl_bufref_set(out, mutual_auth ? "": NULL, 0, NULL);
167
168 return result;
169 }
170
171 /*
172 * Curl_auth_create_gssapi_security_message()
173 *
174 * This is used to generate an already encoded GSSAPI (Kerberos V5) security
175 * token message ready for sending to the recipient.
176 *
177 * Parameters:
178 *
179 * data [in] - The session handle.
180 * authzid [in] - The authorization identity if some.
181 * chlg [in] - Optional challenge message.
182 * krb5 [in/out] - The Kerberos 5 data struct being used and modified.
183 * out [out] - The result storage.
184 *
185 * Returns CURLE_OK on success.
186 */
Curl_auth_create_gssapi_security_message(struct Curl_easy * data,const char * authzid,const struct bufref * chlg,struct kerberos5data * krb5,struct bufref * out)187 CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data,
188 const char *authzid,
189 const struct bufref *chlg,
190 struct kerberos5data *krb5,
191 struct bufref *out)
192 {
193 CURLcode result = CURLE_OK;
194 size_t messagelen = 0;
195 unsigned char *message = NULL;
196 OM_uint32 major_status;
197 OM_uint32 minor_status;
198 OM_uint32 unused_status;
199 gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
200 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
201 unsigned char *indata;
202 gss_qop_t qop = GSS_C_QOP_DEFAULT;
203 unsigned int sec_layer = 0;
204 unsigned int max_size = 0;
205
206 /* Ensure we have a valid challenge message */
207 if(!Curl_bufref_len(chlg)) {
208 infof(data, "GSSAPI handshake failure (empty security message)");
209 return CURLE_BAD_CONTENT_ENCODING;
210 }
211
212 /* Setup the challenge "input" security buffer */
213 input_token.value = (void *) Curl_bufref_ptr(chlg);
214 input_token.length = Curl_bufref_len(chlg);
215
216 /* Decrypt the inbound challenge and obtain the qop */
217 major_status = gss_unwrap(&minor_status, krb5->context, &input_token,
218 &output_token, NULL, &qop);
219 if(GSS_ERROR(major_status)) {
220 Curl_gss_log_error(data, "gss_unwrap() failed: ",
221 major_status, minor_status);
222 return CURLE_BAD_CONTENT_ENCODING;
223 }
224
225 /* Not 4 octets long so fail as per RFC4752 Section 3.1 */
226 if(output_token.length != 4) {
227 infof(data, "GSSAPI handshake failure (invalid security data)");
228 return CURLE_BAD_CONTENT_ENCODING;
229 }
230
231 /* Extract the security layer and the maximum message size */
232 indata = output_token.value;
233 sec_layer = indata[0];
234 max_size = ((unsigned int)indata[1] << 16) |
235 ((unsigned int)indata[2] << 8) | indata[3];
236
237 /* Free the challenge as it is not required anymore */
238 gss_release_buffer(&unused_status, &output_token);
239
240 /* Process the security layer */
241 if(!(sec_layer & GSSAUTH_P_NONE)) {
242 infof(data, "GSSAPI handshake failure (invalid security layer)");
243
244 return CURLE_BAD_CONTENT_ENCODING;
245 }
246 sec_layer &= GSSAUTH_P_NONE; /* We do not support a security layer */
247
248 /* Process the maximum message size the server can receive */
249 if(max_size > 0) {
250 /* The server has told us it supports a maximum receive buffer, however, as
251 we do not require one unless we are encrypting data, we tell the server
252 our receive buffer is zero. */
253 max_size = 0;
254 }
255
256 /* Allocate our message */
257 messagelen = 4;
258 if(authzid)
259 messagelen += strlen(authzid);
260 message = malloc(messagelen);
261 if(!message)
262 return CURLE_OUT_OF_MEMORY;
263
264 /* Populate the message with the security layer and client supported receive
265 message size. */
266 message[0] = sec_layer & 0xFF;
267 message[1] = (max_size >> 16) & 0xFF;
268 message[2] = (max_size >> 8) & 0xFF;
269 message[3] = max_size & 0xFF;
270
271 /* If given, append the authorization identity. */
272
273 if(authzid && *authzid)
274 memcpy(message + 4, authzid, messagelen - 4);
275
276 /* Setup the "authentication data" security buffer */
277 input_token.value = message;
278 input_token.length = messagelen;
279
280 /* Encrypt the data */
281 major_status = gss_wrap(&minor_status, krb5->context, 0,
282 GSS_C_QOP_DEFAULT, &input_token, NULL,
283 &output_token);
284 if(GSS_ERROR(major_status)) {
285 Curl_gss_log_error(data, "gss_wrap() failed: ",
286 major_status, minor_status);
287 free(message);
288 return CURLE_AUTH_ERROR;
289 }
290
291 /* Return the response. */
292 result = Curl_bufref_memdup(out, output_token.value, output_token.length);
293 /* Free the output buffer */
294 gss_release_buffer(&unused_status, &output_token);
295
296 /* Free the message buffer */
297 free(message);
298
299 return result;
300 }
301
302 /*
303 * Curl_auth_cleanup_gssapi()
304 *
305 * This is used to clean up the GSSAPI (Kerberos V5) specific data.
306 *
307 * Parameters:
308 *
309 * krb5 [in/out] - The Kerberos 5 data struct being cleaned up.
310 *
311 */
Curl_auth_cleanup_gssapi(struct kerberos5data * krb5)312 void Curl_auth_cleanup_gssapi(struct kerberos5data *krb5)
313 {
314 OM_uint32 minor_status;
315
316 /* Free our security context */
317 if(krb5->context != GSS_C_NO_CONTEXT) {
318 gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
319 krb5->context = GSS_C_NO_CONTEXT;
320 }
321
322 /* Free the SPN */
323 if(krb5->spn != GSS_C_NO_NAME) {
324 gss_release_name(&minor_status, &krb5->spn);
325 krb5->spn = GSS_C_NO_NAME;
326 }
327 }
328
329 #if defined(__GNUC__) && defined(__APPLE__)
330 #pragma GCC diagnostic pop
331 #endif
332
333 #endif /* HAVE_GSSAPI && USE_KERBEROS5 */
334