9933ca84c798da4a30a2e521c26ea8c9a3fae33d
[idra/samba.git] / source4 / auth / kerberos / kerberos_util.c
1 /* 
2    Unix SMB/CIFS implementation.
3
4    Kerberos utility functions for GENSEC
5    
6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
7
8    This program is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 3 of the License, or
11    (at your option) any later version.
12    
13    This program is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17
18    
19    You should have received a copy of the GNU General Public License
20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
21 */
22
23 #include "includes.h"
24 #include "system/kerberos.h"
25 #include "auth/kerberos/kerberos.h"
26 #include "auth/credentials/credentials.h"
27 #include "auth/credentials/credentials_proto.h"
28 #include "auth/credentials/credentials_krb5.h"
29 #include "auth/kerberos/kerberos_credentials.h"
30 #include "auth/kerberos/kerberos_util.h"
31
32 struct principal_container {
33         struct smb_krb5_context *smb_krb5_context;
34         krb5_principal principal;
35         const char *string_form; /* Optional */
36 };
37
38 static krb5_error_code free_principal(struct principal_container *pc)
39 {
40         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
41         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
42
43         return 0;
44 }
45
46
47 static krb5_error_code parse_principal(TALLOC_CTX *parent_ctx,
48                                        const char *princ_string,
49                                        struct smb_krb5_context *smb_krb5_context,
50                                        krb5_principal *princ,
51                                        const char **error_string)
52 {
53         int ret;
54         struct principal_container *mem_ctx;
55         if (princ_string == NULL) {
56                  *princ = NULL;
57                  return 0;
58         }
59
60         ret = krb5_parse_name(smb_krb5_context->krb5_context,
61                               princ_string, princ);
62
63         if (ret) {
64                 (*error_string) = smb_get_krb5_error_message(
65                                                 smb_krb5_context->krb5_context,
66                                                 ret, parent_ctx);
67                 return ret;
68         }
69
70         mem_ctx = talloc(parent_ctx, struct principal_container);
71         if (!mem_ctx) {
72                 (*error_string) = error_message(ENOMEM);
73                 return ENOMEM;
74         }
75
76         /* This song-and-dance effectivly puts the principal
77          * into talloc, so we can't loose it. */
78         mem_ctx->smb_krb5_context = talloc_reference(mem_ctx,
79                                                      smb_krb5_context);
80         mem_ctx->principal = *princ;
81         talloc_set_destructor(mem_ctx, free_principal);
82         return 0;
83 }
84
85 /* Obtain the principal set on this context.  Requires a
86  * smb_krb5_context because we are doing krb5 principal parsing with
87  * the library routines.  The returned princ is placed in the talloc
88  * system by means of a destructor (do *not* free). */
89
90 krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
91                                 struct cli_credentials *credentials,
92                                 struct smb_krb5_context *smb_krb5_context,
93                                 krb5_principal *princ,
94                                 enum credentials_obtained *obtained,
95                                 const char **error_string)
96 {
97         krb5_error_code ret;
98         const char *princ_string;
99         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
100         *obtained = CRED_UNINITIALISED;
101
102         if (!mem_ctx) {
103                 (*error_string) = error_message(ENOMEM);
104                 return ENOMEM;
105         }
106         princ_string = cli_credentials_get_principal_and_obtained(credentials,
107                                                                   mem_ctx,
108                                                                   obtained);
109         if (!princ_string) {
110                 *princ = NULL;
111                 return 0;
112         }
113
114         ret = parse_principal(parent_ctx, princ_string,
115                               smb_krb5_context, princ, error_string);
116         talloc_free(mem_ctx);
117         return ret;
118 }
119
120 /* Obtain the principal set on this context.  Requires a
121  * smb_krb5_context because we are doing krb5 principal parsing with
122  * the library routines.  The returned princ is placed in the talloc
123  * system by means of a destructor (do *not* free). */
124
125 static krb5_error_code impersonate_principal_from_credentials(
126                                 TALLOC_CTX *parent_ctx,
127                                 struct cli_credentials *credentials,
128                                 struct smb_krb5_context *smb_krb5_context,
129                                 krb5_principal *princ,
130                                 const char **error_string)
131 {
132         return parse_principal(parent_ctx,
133                         cli_credentials_get_impersonate_principal(credentials),
134                         smb_krb5_context, princ, error_string);
135 }
136
137 /**
138  * Return a freshly allocated ccache (destroyed by destructor on child
139  * of parent_ctx), for a given set of client credentials 
140  */
141
142  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
143                                  struct cli_credentials *credentials,
144                                  struct smb_krb5_context *smb_krb5_context,
145                                  struct tevent_context *event_ctx,
146                                  krb5_ccache ccache,
147                                  enum credentials_obtained *obtained,
148                                  const char **error_string)
149 {
150         krb5_error_code ret;
151         const char *password;
152         const char *self_service;
153         const char *target_service;
154         time_t kdc_time = 0;
155         krb5_principal princ;
156         krb5_principal impersonate_principal;
157         int tries;
158         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
159         krb5_get_init_creds_opt *krb_options;
160
161         if (!mem_ctx) {
162                 (*error_string) = strerror(ENOMEM);
163                 return ENOMEM;
164         }
165
166         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ, obtained, error_string);
167         if (ret) {
168                 talloc_free(mem_ctx);
169                 return ret;
170         }
171
172         if (princ == NULL) {
173                 (*error_string) = talloc_asprintf(credentials, "principal, username or realm was not specified in the credentials");
174                 talloc_free(mem_ctx);
175                 return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
176         }
177
178         ret = impersonate_principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &impersonate_principal, error_string);
179         if (ret) {
180                 talloc_free(mem_ctx);
181                 return ret;
182         }
183
184         self_service = cli_credentials_get_self_service(credentials);
185         target_service = cli_credentials_get_target_service(credentials);
186
187         password = cli_credentials_get_password(credentials);
188
189         /* setup the krb5 options we want */
190         if ((ret = krb5_get_init_creds_opt_alloc(smb_krb5_context->krb5_context, &krb_options))) {
191                 (*error_string) = talloc_asprintf(credentials, "krb5_get_init_creds_opt_alloc failed (%s)\n",
192                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
193                                                                              ret, mem_ctx));
194                 talloc_free(mem_ctx);
195                 return ret;
196         }
197
198         /* get the defaults */
199         krb5_get_init_creds_opt_set_default_flags(smb_krb5_context->krb5_context, NULL, NULL, krb_options);
200
201         /* set if we want a forwardable ticket */
202         switch (cli_credentials_get_krb_forwardable(credentials)) {
203         case CRED_AUTO_KRB_FORWARDABLE:
204                 break;
205         case CRED_NO_KRB_FORWARDABLE:
206                 krb5_get_init_creds_opt_set_forwardable(krb_options, FALSE);
207                 break;
208         case CRED_FORCE_KRB_FORWARDABLE:
209                 krb5_get_init_creds_opt_set_forwardable(krb_options, TRUE);
210                 break;
211         }
212
213         /*
214          * In order to work against windows KDCs even if we use
215          * the netbios domain name as realm, we need to add the following
216          * flags:
217          * KRB5_INIT_CREDS_NO_C_CANON_CHECK;
218          * KRB5_INIT_CREDS_NO_C_NO_EKU_CHECK;
219          */
220         krb5_get_init_creds_opt_set_win2k(smb_krb5_context->krb5_context,
221                                           krb_options, true);
222
223         tries = 2;
224         while (tries--) {
225                 struct tevent_context *previous_ev;
226                 /* Do this every time, in case we have weird recursive issues here */
227 #ifdef SAMBA4_USES_HEIMDAL
228                 ret = smb_krb5_context_set_event_ctx(smb_krb5_context, event_ctx, &previous_ev);
229                 if (ret) {
230                         talloc_free(mem_ctx);
231                         return ret;
232                 }
233 #endif
234                 if (password) {
235                         ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache, 
236                                                          princ, password,
237                                                          impersonate_principal,
238                                                          self_service,
239                                                          target_service,
240                                                          krb_options,
241                                                          NULL, &kdc_time);
242                 } else if (impersonate_principal) {
243                         talloc_free(mem_ctx);
244                         (*error_string) = "INTERNAL error: Cannot impersonate principal with just a keyblock.  A password must be specified in the credentials";
245                         return EINVAL;
246                 } else {
247                         /* No password available, try to use a keyblock instead */
248                         
249                         krb5_keyblock keyblock;
250                         const struct samr_Password *mach_pwd;
251                         mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
252                         if (!mach_pwd) {
253                                 talloc_free(mem_ctx);
254                                 (*error_string) = "kinit_to_ccache: No password available for kinit\n";
255                                 krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
256 #ifdef SAMBA4_USES_HEIMDAL
257                                 smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
258 #endif
259                                 return EINVAL;
260                         }
261                         ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
262                                                  ENCTYPE_ARCFOUR_HMAC,
263                                                  mach_pwd->hash, sizeof(mach_pwd->hash), 
264                                                  &keyblock);
265                         
266                         if (ret == 0) {
267                                 ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache, 
268                                                                  princ, &keyblock,
269                                                                  target_service, krb_options,
270                                                                  NULL, &kdc_time);
271                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
272                         }
273                 }
274
275 #ifdef SAMBA4_USES_HEIMDAL
276                 smb_krb5_context_remove_event_ctx(smb_krb5_context, previous_ev, event_ctx);
277 #endif
278
279                 if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
280                         /* Perhaps we have been given an invalid skew, so try again without it */
281                         time_t t = time(NULL);
282                         krb5_set_real_time(smb_krb5_context->krb5_context, t, 0);
283                 } else {
284                         /* not a skew problem */
285                         break;
286                 }
287         }
288
289         krb5_get_init_creds_opt_free(smb_krb5_context->krb5_context, krb_options);
290
291         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
292                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
293                                                   cli_credentials_get_principal(credentials, mem_ctx),
294                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
295                                                                              ret, mem_ctx));
296                 talloc_free(mem_ctx);
297                 return ret;
298         }
299
300         /* cope with ticket being in the future due to clock skew */
301         if ((unsigned)kdc_time > time(NULL)) {
302                 time_t t = time(NULL);
303                 int time_offset =(unsigned)kdc_time-t;
304                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
305                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
306         }
307         
308         if (ret == KRB5KDC_ERR_PREAUTH_FAILED && cli_credentials_wrong_password(credentials)) {
309                 ret = kinit_to_ccache(parent_ctx,
310                                       credentials,
311                                       smb_krb5_context,
312                                       event_ctx,
313                                       ccache, obtained,
314                                       error_string);
315         }
316
317         if (ret) {
318                 (*error_string) = talloc_asprintf(credentials, "kinit for %s failed (%s)\n",
319                                                   cli_credentials_get_principal(credentials, mem_ctx),
320                                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
321                                                                              ret, mem_ctx));
322                 talloc_free(mem_ctx);
323                 return ret;
324         } 
325         talloc_free(mem_ctx);
326         return 0;
327 }
328
329 static krb5_error_code free_keytab_container(struct keytab_container *ktc)
330 {
331         return krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
332 }
333
334 krb5_error_code smb_krb5_get_keytab_container(TALLOC_CTX *mem_ctx,
335                                 struct smb_krb5_context *smb_krb5_context,
336                                 krb5_keytab opt_keytab,
337                                 const char *keytab_name,
338                                 struct keytab_container **ktc)
339 {
340         krb5_keytab keytab;
341         krb5_error_code ret;
342
343         if (opt_keytab) {
344                 keytab = opt_keytab;
345         } else {
346                 ret = krb5_kt_resolve(smb_krb5_context->krb5_context,
347                                                 keytab_name, &keytab);
348                 if (ret) {
349                         DEBUG(1,("failed to open krb5 keytab: %s\n",
350                                  smb_get_krb5_error_message(
351                                         smb_krb5_context->krb5_context,
352                                         ret, mem_ctx)));
353                         return ret;
354                 }
355         }
356
357         *ktc = talloc(mem_ctx, struct keytab_container);
358         if (!*ktc) {
359                 return ENOMEM;
360         }
361
362         (*ktc)->smb_krb5_context = talloc_reference(*ktc, smb_krb5_context);
363         (*ktc)->keytab = keytab;
364         talloc_set_destructor(*ktc, free_keytab_container);
365
366         return 0;
367 }