7c26675713802bd093fca4b53cb14816cb6856b3
[kamenim/samba.git] / source4 / kdc / kpasswdd.c
1 /* 
2    Unix SMB/CIFS implementation.
3
4    kpasswd Server implementation
5
6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
7    Copyright (C) Andrew Tridgell        2005
8
9    This program is free software; you can redistribute it and/or modify
10    it under the terms of the GNU General Public License as published by
11    the Free Software Foundation; either version 3 of the License, or
12    (at your option) any later version.
13    
14    This program is distributed in the hope that it will be useful,
15    but WITHOUT ANY WARRANTY; without even the implied warranty of
16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17    GNU General Public License for more details.
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 "smbd/service_task.h"
25 #include "lib/events/events.h"
26 #include "lib/socket/socket.h"
27 #include "kdc/kdc.h"
28 #include "system/network.h"
29 #include "lib/util/dlinklist.h"
30 #include "lib/ldb/include/ldb.h"
31 #include "heimdal/lib/krb5/krb5_locl.h"
32 #include "heimdal/lib/krb5/krb5-private.h"
33 #include "auth/gensec/gensec.h"
34 #include "auth/credentials/credentials.h"
35 #include "auth/credentials/credentials_krb5.h"
36 #include "auth/auth.h"
37 #include "dsdb/samdb/samdb.h"
38 #include "rpc_server/dcerpc_server.h"
39 #include "rpc_server/samr/proto.h"
40 #include "libcli/security/security.h"
41
42 /* hold information about one kdc socket */
43 struct kpasswd_socket {
44         struct socket_context *sock;
45         struct kdc_server *kdc;
46         struct fd_event *fde;
47
48         /* a queue of outgoing replies that have been deferred */
49         struct kdc_reply *send_queue;
50 };
51
52 /* Return true if there is a valid error packet formed in the error_blob */
53 static BOOL kpasswdd_make_error_reply(struct kdc_server *kdc, 
54                                      TALLOC_CTX *mem_ctx, 
55                                      uint16_t result_code, 
56                                      const char *error_string, 
57                                      DATA_BLOB *error_blob) 
58 {
59         char *error_string_utf8;
60         ssize_t len;
61         
62         DEBUG(result_code ? 3 : 10, ("kpasswdd: %s\n", error_string));
63
64         len = push_utf8_talloc(mem_ctx, &error_string_utf8, error_string);
65         if (len == -1) {
66                 return False;
67         }
68
69         *error_blob = data_blob_talloc(mem_ctx, NULL, 2 + len + 1);
70         if (!error_blob->data) {
71                 return False;
72         }
73         RSSVAL(error_blob->data, 0, result_code);
74         memcpy(error_blob->data + 2, error_string_utf8, len + 1);
75         return True;
76 }
77
78 /* Return true if there is a valid error packet formed in the error_blob */
79 static BOOL kpasswdd_make_unauth_error_reply(struct kdc_server *kdc, 
80                                             TALLOC_CTX *mem_ctx, 
81                                             uint16_t result_code, 
82                                             const char *error_string, 
83                                             DATA_BLOB *error_blob) 
84 {
85         BOOL ret;
86         int kret;
87         DATA_BLOB error_bytes;
88         krb5_data k5_error_bytes, k5_error_blob;
89         ret = kpasswdd_make_error_reply(kdc, mem_ctx, result_code, error_string, 
90                                        &error_bytes);
91         if (!ret) {
92                 return False;
93         }
94         k5_error_bytes.data = error_bytes.data;
95         k5_error_bytes.length = error_bytes.length;
96         kret = krb5_mk_error(kdc->smb_krb5_context->krb5_context,
97                              result_code, NULL, &k5_error_bytes, 
98                              NULL, NULL, NULL, NULL, &k5_error_blob);
99         if (kret) {
100                 return False;
101         }
102         *error_blob = data_blob_talloc(mem_ctx, k5_error_blob.data, k5_error_blob.length);
103         krb5_data_free(&k5_error_blob);
104         if (!error_blob->data) {
105                 return False;
106         }
107         return True;
108 }
109
110 static BOOL kpasswd_make_pwchange_reply(struct kdc_server *kdc, 
111                                         TALLOC_CTX *mem_ctx, 
112                                         NTSTATUS status, 
113                                         enum samr_RejectReason reject_reason,
114                                         struct samr_DomInfo1 *dominfo,
115                                         DATA_BLOB *error_blob) 
116 {
117         if (NT_STATUS_EQUAL(status, NT_STATUS_NO_SUCH_USER)) {
118                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
119                                                 KRB5_KPASSWD_ACCESSDENIED,
120                                                 "No such user when changing password",
121                                                 error_blob);
122         }
123         if (NT_STATUS_EQUAL(status, NT_STATUS_ACCESS_DENIED)) {
124                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
125                                                 KRB5_KPASSWD_ACCESSDENIED,
126                                                 "Not permitted to change password",
127                                                 error_blob);
128         }
129         if (dominfo && NT_STATUS_EQUAL(status, NT_STATUS_PASSWORD_RESTRICTION)) {
130                 const char *reject_string;
131                 switch (reject_reason) {
132                 case SAMR_REJECT_TOO_SHORT:
133                         reject_string = talloc_asprintf(mem_ctx, "Password too short, password must be at least %d characters long",
134                                                         dominfo->min_password_length);
135                         break;
136                 case SAMR_REJECT_COMPLEXITY:
137                         reject_string = "Password does not meet complexity requirements";
138                         break;
139                 case SAMR_REJECT_IN_HISTORY:
140                         reject_string = "Password is already in password history";
141                         break;
142                 case SAMR_REJECT_OTHER:
143                 default:
144                         reject_string = talloc_asprintf(mem_ctx, "Password must be at least %d characters long, and cannot match any of your %d previous passwords",
145                                                         dominfo->min_password_length, dominfo->password_history_length);
146                         break;
147                 }
148                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
149                                                 KRB5_KPASSWD_SOFTERROR,
150                                                 reject_string,
151                                                 error_blob);
152         }
153         if (!NT_STATUS_IS_OK(status)) {
154                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
155                                                  KRB5_KPASSWD_HARDERROR,
156                                                  talloc_asprintf(mem_ctx, "failed to set password: %s", nt_errstr(status)),
157                                                  error_blob);
158                 
159         }
160         return kpasswdd_make_error_reply(kdc, mem_ctx, KRB5_KPASSWD_SUCCESS,
161                                         "Password changed",
162                                         error_blob);
163 }
164
165 /* 
166    A user password change
167    
168    Return true if there is a valid error packet (or sucess) formed in
169    the error_blob
170 */
171 static BOOL kpasswdd_change_password(struct kdc_server *kdc,
172                                      TALLOC_CTX *mem_ctx, 
173                                      struct auth_session_info *session_info,
174                                      const char *password,
175                                      DATA_BLOB *reply)
176 {
177         NTSTATUS status;
178         enum samr_RejectReason reject_reason;
179         struct samr_DomInfo1 *dominfo;
180         struct ldb_context *samdb;
181
182         samdb = samdb_connect(mem_ctx, system_session(mem_ctx));
183         if (!samdb) {
184                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
185                                                 KRB5_KPASSWD_HARDERROR,
186                                                 "Failed to open samdb",
187                                                 reply);
188         }
189         
190         DEBUG(3, ("Changing password of %s\\%s (%s)\n", 
191                   session_info->server_info->domain_name,
192                   session_info->server_info->account_name,
193                   dom_sid_string(mem_ctx, session_info->security_token->user_sid)));
194
195         /* User password change */
196         status = samdb_set_password_sid(samdb, mem_ctx, 
197                                         session_info->security_token->user_sid,
198                                         password, NULL, NULL, 
199                                         True, /* this is a user password change */
200                                         &reject_reason,
201                                         &dominfo);
202         return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
203                                            status, 
204                                            reject_reason,
205                                            dominfo, 
206                                            reply);
207
208 }
209
210 static BOOL kpasswd_process_request(struct kdc_server *kdc,
211                                     TALLOC_CTX *mem_ctx, 
212                                     struct gensec_security *gensec_security,
213                                     uint16_t version,
214                                     DATA_BLOB *input, 
215                                     DATA_BLOB *reply)
216 {
217         struct auth_session_info *session_info;
218         if (!NT_STATUS_IS_OK(gensec_session_info(gensec_security, 
219                                                  &session_info))) {
220                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
221                                                 KRB5_KPASSWD_HARDERROR,
222                                                 "gensec_session_info failed!",
223                                                 reply);
224         }
225
226         switch (version) {
227         case KRB5_KPASSWD_VERS_CHANGEPW:
228         {
229                 char *password = talloc_strndup(mem_ctx, (const char *)input->data, input->length);
230                 if (!password) {
231                         return False;
232                 }
233                 return kpasswdd_change_password(kdc, mem_ctx, session_info, 
234                                                 password, reply);
235                 break;
236         }
237         case KRB5_KPASSWD_VERS_SETPW:
238         {
239                 NTSTATUS status;
240                 enum samr_RejectReason reject_reason = SAMR_REJECT_OTHER;
241                 struct samr_DomInfo1 *dominfo = NULL;
242                 struct ldb_context *samdb;
243                 struct ldb_message *msg;
244                 krb5_context context = kdc->smb_krb5_context->krb5_context;
245
246                 ChangePasswdDataMS chpw;
247                 char *password;
248
249                 krb5_principal principal;
250                 char *set_password_on_princ;
251                 struct ldb_dn *set_password_on_dn;
252
253                 size_t len;
254                 int ret;
255
256                 msg = ldb_msg_new(mem_ctx);
257                 if (!msg) {
258                         return False;
259                 }
260
261                 ret = decode_ChangePasswdDataMS(input->data, input->length,
262                                                 &chpw, &len);
263                 if (ret) {
264                         return kpasswdd_make_error_reply(kdc, mem_ctx, 
265                                                         KRB5_KPASSWD_MALFORMED,
266                                                         "failed to decode password change structure",
267                                                         reply);
268                 }
269                 
270                 password = talloc_strndup(mem_ctx, 
271                                           (const char *)chpw.newpasswd.data, 
272                                           chpw.newpasswd.length);
273                 if (!password) {
274                         free_ChangePasswdDataMS(&chpw);
275                         return False;
276                 }
277                 if ((chpw.targname && !chpw.targrealm) 
278                     || (!chpw.targname && chpw.targrealm)) {
279                         return kpasswdd_make_error_reply(kdc, mem_ctx, 
280                                                         KRB5_KPASSWD_MALFORMED,
281                                                         "Realm and principal must be both present, or neither present",
282                                                         reply);
283                 }
284                 if (chpw.targname && chpw.targrealm) {
285                         if (_krb5_principalname2krb5_principal(kdc->smb_krb5_context->krb5_context,
286                                                                &principal, *chpw.targname, 
287                                                                *chpw.targrealm) != 0) {
288                                 free_ChangePasswdDataMS(&chpw);
289                                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
290                                                                 KRB5_KPASSWD_MALFORMED,
291                                                                 "failed to extract principal to set",
292                                                                 reply);
293                                 
294                         }
295                 } else {
296                         free_ChangePasswdDataMS(&chpw);
297                         return kpasswdd_change_password(kdc, mem_ctx, session_info, 
298                                                         password, reply);
299                 }
300                 free_ChangePasswdDataMS(&chpw);
301
302                 if (krb5_unparse_name(context, principal, &set_password_on_princ) != 0) {
303                         krb5_free_principal(context, principal);
304                         return kpasswdd_make_error_reply(kdc, mem_ctx, 
305                                                         KRB5_KPASSWD_MALFORMED,
306                                                         "krb5_unparse_name failed!",
307                                                         reply);
308                 }
309                 
310                 krb5_free_principal(context, principal);
311                 
312                 samdb = samdb_connect(mem_ctx, session_info);
313                 if (!samdb) {
314                         return kpasswdd_make_error_reply(kdc, mem_ctx, 
315                                                          KRB5_KPASSWD_HARDERROR,
316                                                          "Unable to open database!",
317                                                          reply);
318                 }
319
320                 DEBUG(3, ("%s\\%s (%s) is changing password of %s\n", 
321                           session_info->server_info->domain_name,
322                           session_info->server_info->account_name,
323                           dom_sid_string(mem_ctx, session_info->security_token->user_sid), 
324                           set_password_on_princ));
325                 ret = ldb_transaction_start(samdb);
326                 if (ret) {
327                         status = NT_STATUS_TRANSACTION_ABORTED;
328                         return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
329                                                            status,
330                                                            SAMR_REJECT_OTHER, 
331                                                            NULL, 
332                                                            reply);
333                 }
334
335                 status = crack_user_principal_name(samdb, mem_ctx, 
336                                                    set_password_on_princ, 
337                                                    &set_password_on_dn, NULL);
338                 free(set_password_on_princ);
339                 if (!NT_STATUS_IS_OK(status)) {
340                         ldb_transaction_cancel(samdb);
341                         return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
342                                                            status,
343                                                            SAMR_REJECT_OTHER, 
344                                                            NULL, 
345                                                            reply);
346                 }
347
348                 msg = ldb_msg_new(mem_ctx);
349                 if (msg == NULL) {
350                         ldb_transaction_cancel(samdb);
351                         status = NT_STATUS_NO_MEMORY;
352                 } else {
353                         msg->dn = ldb_dn_copy(msg, set_password_on_dn);
354                         if (!msg->dn) {
355                                 status = NT_STATUS_NO_MEMORY;
356                         }
357                 }
358
359                 if (NT_STATUS_IS_OK(status)) {
360                         /* Admin password set */
361                         status = samdb_set_password(samdb, mem_ctx,
362                                                     set_password_on_dn, NULL,
363                                                     msg, password, NULL, NULL, 
364                                                     False, /* this is not a user password change */
365                                                     &reject_reason, &dominfo);
366                 }
367
368                 if (NT_STATUS_IS_OK(status)) {
369                         /* modify the samdb record */
370                         ret = samdb_replace(samdb, mem_ctx, msg);
371                         if (ret != 0) {
372                                 DEBUG(2,("Failed to modify record to set password on %s: %s\n",
373                                          ldb_dn_get_linearized(msg->dn),
374                                          ldb_errstring(samdb)));
375                                 status = NT_STATUS_ACCESS_DENIED;
376                         }
377                 }
378                 if (NT_STATUS_IS_OK(status)) {
379                         ret = ldb_transaction_commit(samdb);
380                         if (ret != 0) {
381                                 DEBUG(1,("Failed to commit transaction to set password on %s: %s\n",
382                                          ldb_dn_get_linearized(msg->dn),
383                                          ldb_errstring(samdb)));
384                                 status = NT_STATUS_TRANSACTION_ABORTED;
385                         }
386                 } else {
387                         ldb_transaction_cancel(samdb);
388                 }
389                 return kpasswd_make_pwchange_reply(kdc, mem_ctx, 
390                                                    status,
391                                                    reject_reason, 
392                                                    dominfo, 
393                                                    reply);
394         }
395         default:
396                 return kpasswdd_make_error_reply(kdc, mem_ctx, 
397                                                  KRB5_KPASSWD_BAD_VERSION,
398                                                  talloc_asprintf(mem_ctx, 
399                                                                  "Protocol version %u not supported", 
400                                                                  version),
401                                                  reply);
402         }
403         return True;
404 }
405
406 BOOL kpasswdd_process(struct kdc_server *kdc,
407                       TALLOC_CTX *mem_ctx, 
408                       DATA_BLOB *input, 
409                       DATA_BLOB *reply,
410                       struct socket_address *peer_addr,
411                       struct socket_address *my_addr,
412                       int datagram_reply)
413 {
414         BOOL ret;
415         const uint16_t header_len = 6;
416         uint16_t len;
417         uint16_t ap_req_len;
418         uint16_t krb_priv_len;
419         uint16_t version;
420         NTSTATUS nt_status;
421         DATA_BLOB ap_req, krb_priv_req;
422         DATA_BLOB krb_priv_rep = data_blob(NULL, 0);
423         DATA_BLOB ap_rep = data_blob(NULL, 0);
424         DATA_BLOB kpasswd_req, kpasswd_rep;
425         struct cli_credentials *server_credentials;
426         struct gensec_security *gensec_security;
427         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
428         
429         if (!tmp_ctx) {
430                 return False;
431         }
432
433         /* Be parinoid.  We need to ensure we don't just let the
434          * caller lead us into a buffer overflow */
435         if (input->length <= header_len) {
436                 talloc_free(tmp_ctx);
437                 return False;
438         }
439
440         len = RSVAL(input->data, 0);
441         if (input->length != len) {
442                 talloc_free(tmp_ctx);
443                 return False;
444         }
445
446         /* There are two different versions of this protocol so far,
447          * plus others in the standards pipe.  Fortunetly they all
448          * take a very similar framing */
449         version = RSVAL(input->data, 2);
450         ap_req_len = RSVAL(input->data, 4);
451         if ((ap_req_len >= len) || (ap_req_len + header_len) >= len) {
452                 talloc_free(tmp_ctx);
453                 return False;
454         }
455         
456         krb_priv_len = len - ap_req_len;
457         ap_req = data_blob_const(&input->data[header_len], ap_req_len);
458         krb_priv_req = data_blob_const(&input->data[header_len + ap_req_len], krb_priv_len);
459         
460         nt_status = gensec_server_start(tmp_ctx, kdc->task->event_ctx, kdc->task->msg_ctx, &gensec_security);
461         if (!NT_STATUS_IS_OK(nt_status)) {
462                 talloc_free(tmp_ctx);
463                 return False;
464         }
465
466         server_credentials = cli_credentials_init(tmp_ctx);
467         if (!server_credentials) {
468                 DEBUG(1, ("Failed to init server credentials\n"));
469                 return False;
470         }
471
472         /* We want the credentials subsystem to use the krb5 context
473          * we already have, rather than a new context */        
474         cli_credentials_set_krb5_context(server_credentials, kdc->smb_krb5_context);
475         cli_credentials_set_conf(server_credentials);
476         nt_status = cli_credentials_set_stored_principal(server_credentials, "kadmin/changepw");
477         if (!NT_STATUS_IS_OK(nt_status)) {
478                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
479                                                        KRB5_KPASSWD_HARDERROR,
480                                                        talloc_asprintf(mem_ctx, 
481                                                                        "Failed to obtain server credentials for kadmin/changepw: %s\n", 
482                                                                        nt_errstr(nt_status)),
483                                                        &krb_priv_rep);
484                 ap_rep.length = 0;
485                 if (ret) {
486                         goto reply;
487                 }
488                 talloc_free(tmp_ctx);
489                 return ret;
490         }
491         
492         nt_status = gensec_set_credentials(gensec_security, server_credentials);
493         if (!NT_STATUS_IS_OK(nt_status)) {
494                 talloc_free(tmp_ctx);
495                 return False;
496         }
497
498         /* The kerberos PRIV packets include these addresses.  MIT
499          * clients check that they are present */
500         nt_status = gensec_set_peer_addr(gensec_security, peer_addr);
501         if (!NT_STATUS_IS_OK(nt_status)) {
502                 talloc_free(tmp_ctx);
503                 return False;
504         }
505         nt_status = gensec_set_my_addr(gensec_security, my_addr);
506         if (!NT_STATUS_IS_OK(nt_status)) {
507                 talloc_free(tmp_ctx);
508                 return False;
509         }
510
511         /* We want the GENSEC wrap calls to generate PRIV tokens */
512         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
513
514         nt_status = gensec_start_mech_by_name(gensec_security, "krb5");
515         if (!NT_STATUS_IS_OK(nt_status)) {
516                 talloc_free(tmp_ctx);
517                 return False;
518         }
519
520         /* Accept the AP-REQ and generate teh AP-REP we need for the reply */
521         nt_status = gensec_update(gensec_security, tmp_ctx, ap_req, &ap_rep);
522         if (!NT_STATUS_IS_OK(nt_status) && !NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
523                 
524                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
525                                                        KRB5_KPASSWD_HARDERROR,
526                                                        talloc_asprintf(mem_ctx, 
527                                                                        "gensec_update failed: %s", 
528                                                                        nt_errstr(nt_status)),
529                                                        &krb_priv_rep);
530                 ap_rep.length = 0;
531                 if (ret) {
532                         goto reply;
533                 }
534                 talloc_free(tmp_ctx);
535                 return ret;
536         }
537
538         /* Extract the data from the KRB-PRIV half of the message */
539         nt_status = gensec_unwrap(gensec_security, tmp_ctx, &krb_priv_req, &kpasswd_req);
540         if (!NT_STATUS_IS_OK(nt_status)) {
541                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
542                                                        KRB5_KPASSWD_HARDERROR,
543                                                        talloc_asprintf(mem_ctx, 
544                                                                        "gensec_unwrap failed: %s", 
545                                                                        nt_errstr(nt_status)),
546                                                        &krb_priv_rep);
547                 ap_rep.length = 0;
548                 if (ret) {
549                         goto reply;
550                 }
551                 talloc_free(tmp_ctx);
552                 return ret;
553         }
554
555         /* Figure out something to do with it (probably changing a password...) */
556         ret = kpasswd_process_request(kdc, tmp_ctx, 
557                                       gensec_security, 
558                                       version, 
559                                       &kpasswd_req, &kpasswd_rep); 
560         if (!ret) {
561                 /* Argh! */
562                 return False;
563         }
564
565         /* And wrap up the reply: This ensures that the error message
566          * or success can be verified by the client */
567         nt_status = gensec_wrap(gensec_security, tmp_ctx, 
568                                 &kpasswd_rep, &krb_priv_rep);
569         if (!NT_STATUS_IS_OK(nt_status)) {
570                 ret = kpasswdd_make_unauth_error_reply(kdc, mem_ctx, 
571                                                        KRB5_KPASSWD_HARDERROR,
572                                                        talloc_asprintf(mem_ctx, 
573                                                                        "gensec_wrap failed: %s", 
574                                                                        nt_errstr(nt_status)),
575                                                        &krb_priv_rep);
576                 ap_rep.length = 0;
577                 if (ret) {
578                         goto reply;
579                 }
580                 talloc_free(tmp_ctx);
581                 return ret;
582         }
583         
584 reply:
585         *reply = data_blob_talloc(mem_ctx, NULL, krb_priv_rep.length + ap_rep.length + header_len);
586         if (!reply->data) {
587                 return False;
588         }
589
590         RSSVAL(reply->data, 0, reply->length);
591         RSSVAL(reply->data, 2, 1); /* This is a version 1 reply, MS change/set or otherwise */
592         RSSVAL(reply->data, 4, ap_rep.length);
593         memcpy(reply->data + header_len, 
594                ap_rep.data, 
595                ap_rep.length);
596         memcpy(reply->data + header_len + ap_rep.length, 
597                krb_priv_rep.data, 
598                krb_priv_rep.length);
599
600         talloc_free(tmp_ctx);
601         return ret;
602 }
603