1/***************************************************************************
2 *                                  _   _ ____  _
3 *  Project                     ___| | | |  _ \| |
4 *                             / __| | | | |_) | |
5 *                            | (__| |_| |  _ <| |___
6 *                             \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 2014 - 2016, 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_create_gssapi_user_message()
46 *
47 * This is used to generate an already encoded GSSAPI (Kerberos V5) user token
48 * message ready for sending to the recipient.
49 *
50 * Parameters:
51 *
52 * data        [in]     - The session handle.
53 * userp       [in]     - The user name.
54 * passdwp     [in]     - The user's password.
55 * service     [in]     - The service type such as http, smtp, pop or imap.
56 * host        [in[     - The host name.
57 * mutual_auth [in]     - Flag specifing whether or not mutual authentication
58 *                        is enabled.
59 * chlg64      [in]     - Pointer to the optional base64 encoded challenge
60 *                        message.
61 * krb5        [in/out] - The Kerberos 5 data struct being used and modified.
62 * outptr      [in/out] - The address where a pointer to newly allocated memory
63 *                        holding the result will be stored upon completion.
64 * outlen      [out]    - The length of the output message.
65 *
66 * Returns CURLE_OK on success.
67 */
68CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
69                                              const char *userp,
70                                              const char *passwdp,
71                                              const char *service,
72                                              const char *host,
73                                              const bool mutual_auth,
74                                              const char *chlg64,
75                                              struct kerberos5data *krb5,
76                                              char **outptr, size_t *outlen)
77{
78  CURLcode result = CURLE_OK;
79  size_t chlglen = 0;
80  unsigned char *chlg = NULL;
81  OM_uint32 major_status;
82  OM_uint32 minor_status;
83  OM_uint32 unused_status;
84  gss_buffer_desc spn_token = GSS_C_EMPTY_BUFFER;
85  gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
86  gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
87
88  (void) userp;
89  (void) passwdp;
90
91  if(!krb5->spn) {
92    /* Generate our SPN */
93    char *spn = Curl_auth_build_spn(service, NULL, host);
94    if(!spn)
95      return CURLE_OUT_OF_MEMORY;
96
97    /* Populate the SPN structure */
98    spn_token.value = spn;
99    spn_token.length = strlen(spn);
100
101    /* Import the SPN */
102    major_status = gss_import_name(&minor_status, &spn_token,
103                                   GSS_C_NT_HOSTBASED_SERVICE, &krb5->spn);
104    if(GSS_ERROR(major_status)) {
105      Curl_gss_log_error(data, "gss_import_name() failed: ",
106                         major_status, minor_status);
107
108      free(spn);
109
110      return CURLE_OUT_OF_MEMORY;
111    }
112
113    free(spn);
114  }
115
116  if(chlg64 && *chlg64) {
117    /* Decode the base-64 encoded challenge message */
118    if(*chlg64 != '=') {
119      result = Curl_base64_decode(chlg64, &chlg, &chlglen);
120      if(result)
121        return result;
122    }
123
124    /* Ensure we have a valid challenge message */
125    if(!chlg) {
126      infof(data, "GSSAPI handshake failure (empty challenge message)\n");
127
128      return CURLE_BAD_CONTENT_ENCODING;
129    }
130
131    /* Setup the challenge "input" security buffer */
132    input_token.value = chlg;
133    input_token.length = chlglen;
134  }
135
136  major_status = Curl_gss_init_sec_context(data,
137                                           &minor_status,
138                                           &krb5->context,
139                                           krb5->spn,
140                                           &Curl_krb5_mech_oid,
141                                           GSS_C_NO_CHANNEL_BINDINGS,
142                                           &input_token,
143                                           &output_token,
144                                           mutual_auth,
145                                           NULL);
146
147  /* Free the decoded challenge as it is not required anymore */
148  free(input_token.value);
149
150  if(GSS_ERROR(major_status)) {
151    if(output_token.value)
152      gss_release_buffer(&unused_status, &output_token);
153
154    Curl_gss_log_error(data, "gss_init_sec_context() failed: ",
155                       major_status, minor_status);
156
157    return CURLE_RECV_ERROR;
158  }
159
160  if(output_token.value && output_token.length) {
161    /* Base64 encode the response */
162    result = Curl_base64_encode(data, (char *) output_token.value,
163                                output_token.length, outptr, outlen);
164
165    gss_release_buffer(&unused_status, &output_token);
166  }
167  else if(mutual_auth) {
168    *outptr = strdup("");
169    if(!*outptr)
170      result = CURLE_OUT_OF_MEMORY;
171  }
172
173  return result;
174}
175
176/*
177 * Curl_auth_create_gssapi_security_message()
178 *
179 * This is used to generate an already encoded GSSAPI (Kerberos V5) security
180 * token message ready for sending to the recipient.
181 *
182 * Parameters:
183 *
184 * data    [in]     - The session handle.
185 * chlg64  [in]     - Pointer to the optional base64 encoded challenge message.
186 * krb5    [in/out] - The Kerberos 5 data struct being used and modified.
187 * outptr  [in/out] - The address where a pointer to newly allocated memory
188 *                    holding the result will be stored upon completion.
189 * outlen  [out]    - The length of the output message.
190 *
191 * Returns CURLE_OK on success.
192 */
193CURLcode Curl_auth_create_gssapi_security_message(struct Curl_easy *data,
194                                                  const char *chlg64,
195                                                  struct kerberos5data *krb5,
196                                                  char **outptr,
197                                                  size_t *outlen)
198{
199  CURLcode result = CURLE_OK;
200  size_t chlglen = 0;
201  size_t messagelen = 0;
202  unsigned char *chlg = NULL;
203  unsigned char *message = NULL;
204  OM_uint32 major_status;
205  OM_uint32 minor_status;
206  OM_uint32 unused_status;
207  gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
208  gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
209  unsigned int indata = 0;
210  unsigned int outdata = 0;
211  gss_qop_t qop = GSS_C_QOP_DEFAULT;
212  unsigned int sec_layer = 0;
213  unsigned int max_size = 0;
214  gss_name_t username = GSS_C_NO_NAME;
215  gss_buffer_desc username_token;
216
217  /* Decode the base-64 encoded input message */
218  if(strlen(chlg64) && *chlg64 != '=') {
219    result = Curl_base64_decode(chlg64, &chlg, &chlglen);
220    if(result)
221      return result;
222  }
223
224  /* Ensure we have a valid challenge message */
225  if(!chlg) {
226    infof(data, "GSSAPI handshake failure (empty security message)\n");
227
228    return CURLE_BAD_CONTENT_ENCODING;
229  }
230
231  /* Get the fully qualified username back from the context */
232  major_status = gss_inquire_context(&minor_status, krb5->context,
233                                     &username, NULL, NULL, NULL, NULL,
234                                     NULL, NULL);
235  if(GSS_ERROR(major_status)) {
236    Curl_gss_log_error(data, "gss_inquire_context() failed: ",
237                       major_status, minor_status);
238
239    free(chlg);
240
241    return CURLE_OUT_OF_MEMORY;
242  }
243
244  /* Convert the username from internal format to a displayable token */
245  major_status = gss_display_name(&minor_status, username,
246                                  &username_token, NULL);
247  if(GSS_ERROR(major_status)) {
248    Curl_gss_log_error(data, "gss_display_name() failed: ",
249                       major_status, minor_status);
250
251    free(chlg);
252
253    return CURLE_OUT_OF_MEMORY;
254  }
255
256  /* Setup the challenge "input" security buffer */
257  input_token.value = chlg;
258  input_token.length = chlglen;
259
260  /* Decrypt the inbound challenge and obtain the qop */
261  major_status = gss_unwrap(&minor_status, krb5->context, &input_token,
262                            &output_token, NULL, &qop);
263  if(GSS_ERROR(major_status)) {
264    Curl_gss_log_error(data, "gss_unwrap() failed: ",
265                       major_status, minor_status);
266
267    gss_release_buffer(&unused_status, &username_token);
268    free(chlg);
269
270    return CURLE_BAD_CONTENT_ENCODING;
271  }
272
273  /* Not 4 octets long so fail as per RFC4752 Section 3.1 */
274  if(output_token.length != 4) {
275    infof(data, "GSSAPI handshake failure (invalid security data)\n");
276
277    gss_release_buffer(&unused_status, &username_token);
278    free(chlg);
279
280    return CURLE_BAD_CONTENT_ENCODING;
281  }
282
283  /* Copy the data out and free the challenge as it is not required anymore */
284  memcpy(&indata, output_token.value, 4);
285  gss_release_buffer(&unused_status, &output_token);
286  free(chlg);
287
288  /* Extract the security layer */
289  sec_layer = indata & 0x000000FF;
290  if(!(sec_layer & GSSAUTH_P_NONE)) {
291    infof(data, "GSSAPI handshake failure (invalid security layer)\n");
292
293    gss_release_buffer(&unused_status, &username_token);
294
295    return CURLE_BAD_CONTENT_ENCODING;
296  }
297
298  /* Extract the maximum message size the server can receive */
299  max_size = ntohl(indata & 0xFFFFFF00);
300  if(max_size > 0) {
301    /* The server has told us it supports a maximum receive buffer, however, as
302       we don't require one unless we are encrypting data, we tell the server
303       our receive buffer is zero. */
304    max_size = 0;
305  }
306
307  /* Allocate our message */
308  messagelen = sizeof(outdata) + username_token.length + 1;
309  message = malloc(messagelen);
310  if(!message) {
311    gss_release_buffer(&unused_status, &username_token);
312
313    return CURLE_OUT_OF_MEMORY;
314  }
315
316  /* Populate the message with the security layer, client supported receive
317     message size and authorization identity including the 0x00 based
318     terminator. Note: Despite RFC4752 Section 3.1 stating "The authorization
319     identity is not terminated with the zero-valued (%x00) octet." it seems
320     necessary to include it. */
321  outdata = htonl(max_size) | sec_layer;
322  memcpy(message, &outdata, sizeof(outdata));
323  memcpy(message + sizeof(outdata), username_token.value,
324         username_token.length);
325  message[messagelen - 1] = '\0';
326
327  /* Free the username token as it is not required anymore */
328  gss_release_buffer(&unused_status, &username_token);
329
330  /* Setup the "authentication data" security buffer */
331  input_token.value = message;
332  input_token.length = messagelen;
333
334  /* Encrypt the data */
335  major_status = gss_wrap(&minor_status, krb5->context, 0,
336                          GSS_C_QOP_DEFAULT, &input_token, NULL,
337                          &output_token);
338  if(GSS_ERROR(major_status)) {
339    Curl_gss_log_error(data, "gss_wrap() failed: ",
340                       major_status, minor_status);
341
342    free(message);
343
344    return CURLE_OUT_OF_MEMORY;
345  }
346
347  /* Base64 encode the response */
348  result = Curl_base64_encode(data, (char *) output_token.value,
349                              output_token.length, outptr, outlen);
350
351  /* Free the output buffer */
352  gss_release_buffer(&unused_status, &output_token);
353
354  /* Free the message buffer */
355  free(message);
356
357  return result;
358}
359
360/*
361 * Curl_auth_gssapi_cleanup()
362 *
363 * This is used to clean up the GSSAPI (Kerberos V5) specific data.
364 *
365 * Parameters:
366 *
367 * krb5     [in/out] - The Kerberos 5 data struct being cleaned up.
368 *
369 */
370void Curl_auth_gssapi_cleanup(struct kerberos5data *krb5)
371{
372  OM_uint32 minor_status;
373
374  /* Free our security context */
375  if(krb5->context != GSS_C_NO_CONTEXT) {
376    gss_delete_sec_context(&minor_status, &krb5->context, GSS_C_NO_BUFFER);
377    krb5->context = GSS_C_NO_CONTEXT;
378  }
379
380  /* Free the SPN */
381  if(krb5->spn != GSS_C_NO_NAME) {
382    gss_release_name(&minor_status, &krb5->spn);
383    krb5->spn = GSS_C_NO_NAME;
384  }
385}
386
387#endif /* HAVE_GSSAPI && USE_KERBEROS5 */
388