30b3c64379f9d4b26ef1c8931dd8b507f591f128
[samba.git] / libcli / drsuapi / repl_decrypt.c
1 /* 
2    Unix SMB/CIFS implementation.
3    Helper functions for applying replicated objects
4    
5    Copyright (C) Stefan Metzmacher <metze@samba.org> 2007
6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2009
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    You should have received a copy of the GNU General Public License
19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
20    
21 */
22
23 #include "includes.h"
24 #include "../lib/util/dlinklist.h"
25 #include "librpc/gen_ndr/ndr_misc.h"
26 #include "librpc/gen_ndr/ndr_drsuapi.h"
27 #include "librpc/gen_ndr/ndr_drsblobs.h"
28 #include "zlib.h"
29 #include "../libcli/drsuapi/drsuapi.h"
30 #include "libcli/auth/libcli_auth.h"
31 #include "dsdb/samdb/samdb.h"
32
33 #include "lib/crypto/gnutls_helpers.h"
34 #include <gnutls/gnutls.h>
35 #include <gnutls/crypto.h>
36
37 static WERROR drsuapi_decrypt_attribute_value(TALLOC_CTX *mem_ctx,
38                                               const DATA_BLOB *gensec_skey,
39                                               bool rid_crypt,
40                                               uint32_t rid,
41                                               const DATA_BLOB *in,
42                                               DATA_BLOB *out)
43 {
44         DATA_BLOB confounder;
45         DATA_BLOB enc_buffer;
46
47         DATA_BLOB dec_buffer;
48
49         uint32_t crc32_given;
50         uint32_t crc32_calc;
51         DATA_BLOB checked_buffer;
52
53         DATA_BLOB plain_buffer;
54         WERROR result;
55         int rc;
56
57         /*
58          * users with rid == 0 should not exist
59          */
60         if (rid_crypt && rid == 0) {
61                 return WERR_DS_DRA_INVALID_PARAMETER;
62         }
63
64         /* 
65          * the first 16 bytes at the beginning are the confounder
66          * followed by the 4 byte crc32 checksum
67          */
68         if (in->length < 20) {
69                 return WERR_DS_DRA_INVALID_PARAMETER;
70         }
71         confounder = data_blob_const(in->data, 16);
72         enc_buffer = data_blob_const(in->data + 16, in->length - 16);
73
74         /* 
75          * decrypt with the encryption key, being md5 over the session
76          * key followed by the confounder.  The parameter order to
77          * samba_gnutls_arcfour_confounded_md5() matters for this!
78          * 
79          * here the gensec session key is used and
80          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
81          */
82
83         /*
84          * reference the encrypted buffer part and
85          * decrypt it using the created encryption key using arcfour
86          */
87         dec_buffer = data_blob_const(enc_buffer.data, enc_buffer.length);
88
89         rc = samba_gnutls_arcfour_confounded_md5(gensec_skey,
90                                                  &confounder,
91                                                  &dec_buffer,
92                                                  SAMBA_GNUTLS_DECRYPT);
93         if (rc < 0) {
94                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
95                 goto out;
96         }
97
98         /* 
99          * the first 4 byte are the crc32 checksum
100          * of the remaining bytes
101          */
102         crc32_given = IVAL(dec_buffer.data, 0);
103         crc32_calc = crc32(0, Z_NULL, 0);
104         crc32_calc = crc32(crc32_calc,
105                            dec_buffer.data + 4 ,
106                            dec_buffer.length - 4);
107         checked_buffer = data_blob_const(dec_buffer.data + 4, dec_buffer.length - 4);
108
109         plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length);
110         W_ERROR_HAVE_NO_MEMORY(plain_buffer.data);
111
112         if (crc32_given != crc32_calc) {
113                 result = W_ERROR(HRES_ERROR_V(HRES_SEC_E_DECRYPT_FAILURE));
114                 goto out;
115         }
116         /*
117          * The following rid_crypt obfuscation isn't session specific
118          * and not really needed here, because we allways know the rid of the
119          * user account.
120          *
121          * some attributes with this 'additional encryption' include
122          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
123          *
124          * But for the rest of samba it's easier when we remove this static
125          * obfuscation here
126          */
127         if (rid_crypt) {
128                 uint32_t i, num_hashes;
129
130                 if ((checked_buffer.length % 16) != 0) {
131                         result = WERR_DS_DRA_INVALID_PARAMETER;
132                         goto out;
133                 }
134
135                 num_hashes = plain_buffer.length / 16;
136                 for (i = 0; i < num_hashes; i++) {
137                         uint32_t offset = i * 16;
138                         rc = sam_rid_crypt(rid, checked_buffer.data + offset,
139                                            plain_buffer.data + offset,
140                                            SAMBA_GNUTLS_DECRYPT);
141                         if (rc != 0) {
142                                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
143                                 goto out;
144                         }
145                 }
146         }
147
148         *out = plain_buffer;
149         result = WERR_OK;
150 out:
151         return result;
152 }
153
154 WERROR drsuapi_decrypt_attribute(TALLOC_CTX *mem_ctx, 
155                                  const DATA_BLOB *gensec_skey,
156                                  uint32_t rid,
157                                  uint32_t dsdb_repl_flags,
158                                  struct drsuapi_DsReplicaAttribute *attr)
159 {
160         WERROR status;
161         DATA_BLOB *enc_data;
162         DATA_BLOB plain_data;
163         bool rid_crypt = false;
164
165         if (attr->value_ctr.num_values == 0) {
166                 return WERR_OK;
167         }
168
169         switch (attr->attid) {
170         case DRSUAPI_ATTID_dBCSPwd:
171         case DRSUAPI_ATTID_unicodePwd:
172         case DRSUAPI_ATTID_ntPwdHistory:
173         case DRSUAPI_ATTID_lmPwdHistory:
174                 rid_crypt = true;
175                 break;
176         case DRSUAPI_ATTID_supplementalCredentials:
177         case DRSUAPI_ATTID_priorValue:
178         case DRSUAPI_ATTID_currentValue:
179         case DRSUAPI_ATTID_trustAuthOutgoing:
180         case DRSUAPI_ATTID_trustAuthIncoming:
181         case DRSUAPI_ATTID_initialAuthOutgoing:
182         case DRSUAPI_ATTID_initialAuthIncoming:
183                 break;
184         default:
185                 return WERR_OK;
186         }
187
188         if (dsdb_repl_flags & DSDB_REPL_FLAG_EXPECT_NO_SECRETS) {
189                 return WERR_TOO_MANY_SECRETS;
190         }
191
192         if (attr->value_ctr.num_values > 1) {
193                 return WERR_DS_DRA_INVALID_PARAMETER;
194         }
195
196         if (!attr->value_ctr.values[0].blob) {
197                 return WERR_DS_DRA_INVALID_PARAMETER;
198         }
199
200         enc_data        = attr->value_ctr.values[0].blob;
201
202         status = drsuapi_decrypt_attribute_value(mem_ctx,
203                                                  gensec_skey,
204                                                  rid_crypt,
205                                                  rid,
206                                                  enc_data,
207                                                  &plain_data);
208         W_ERROR_NOT_OK_RETURN(status);
209
210         talloc_free(attr->value_ctr.values[0].blob->data);
211         *attr->value_ctr.values[0].blob = plain_data;
212
213         return WERR_OK;
214 }
215
216 static WERROR drsuapi_encrypt_attribute_value(TALLOC_CTX *mem_ctx,
217                                               const DATA_BLOB *gensec_skey,
218                                               bool rid_crypt,
219                                               uint32_t rid,
220                                               const DATA_BLOB *in,
221                                               DATA_BLOB *out)
222 {
223         DATA_BLOB rid_crypt_out = data_blob(NULL, 0);
224         DATA_BLOB confounder;
225
226         DATA_BLOB enc_buffer;
227
228         DATA_BLOB to_encrypt;
229
230         uint32_t crc32_calc;
231         WERROR result;
232         int rc;
233
234         /*
235          * users with rid == 0 should not exist
236          */
237         if (rid_crypt && rid == 0) {
238                 return WERR_DS_DRA_INVALID_PARAMETER;
239         }
240
241         /*
242          * The following rid_crypt obfuscation isn't session specific
243          * and not really needed here, because we allways know the rid of the
244          * user account.
245          *
246          * some attributes with this 'additional encryption' include
247          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
248          *
249          * But for the rest of samba it's easier when we remove this static
250          * obfuscation here
251          */
252         if (rid_crypt) {
253                 uint32_t i, num_hashes;
254                 rid_crypt_out = data_blob_talloc(mem_ctx, in->data, in->length);
255                 W_ERROR_HAVE_NO_MEMORY(rid_crypt_out.data);
256
257                 if ((rid_crypt_out.length % 16) != 0) {
258                         return WERR_DS_DRA_INVALID_PARAMETER;
259                 }
260
261                 num_hashes = rid_crypt_out.length / 16;
262                 for (i = 0; i < num_hashes; i++) {
263                         uint32_t offset = i * 16;
264                         rc = sam_rid_crypt(rid, in->data + offset,
265                                            rid_crypt_out.data + offset,
266                                            SAMBA_GNUTLS_ENCRYPT);
267                         if (rc != 0) {
268                                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
269                                 goto out;
270                         }
271                 }
272                 in = &rid_crypt_out;
273         }
274
275         /* 
276          * the first 16 bytes at the beginning are the confounder
277          * followed by the 4 byte crc32 checksum
278          */
279
280         enc_buffer = data_blob_talloc(mem_ctx, NULL, in->length+20);
281         if (!enc_buffer.data) {
282                 talloc_free(rid_crypt_out.data);
283                 return WERR_NOT_ENOUGH_MEMORY;
284         };
285         
286         confounder = data_blob_const(enc_buffer.data, 16);
287         generate_random_buffer(confounder.data, confounder.length);
288
289         /* 
290          * the first 4 byte are the crc32 checksum
291          * of the remaining bytes
292          */
293         crc32_calc = crc32(0, Z_NULL, 0);
294         crc32_calc = crc32(crc32_calc, in->data, in->length);
295         SIVAL(enc_buffer.data, 16, crc32_calc);
296
297         /*
298          * copy the plain buffer part and 
299          * encrypt it using the created encryption key using arcfour
300          */
301         memcpy(enc_buffer.data+20, in->data, in->length); 
302         talloc_free(rid_crypt_out.data);
303
304         to_encrypt = data_blob_const(enc_buffer.data+16,
305                                      enc_buffer.length-16);
306
307         /*
308          * encrypt with the encryption key, being md5 over the session
309          * key followed by the confounder.  The parameter order to
310          * samba_gnutls_arcfour_confounded_md5() matters for this!
311          *
312          * here the gensec session key is used and
313          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
314          */
315
316         rc = samba_gnutls_arcfour_confounded_md5(gensec_skey,
317                                                  &confounder,
318                                                  &to_encrypt,
319                                                  SAMBA_GNUTLS_ENCRYPT);
320         if (rc < 0) {
321                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
322                 goto out;
323         }
324
325         *out = enc_buffer;
326         result =  WERR_OK;
327 out:
328         return result;
329 }
330
331 /*
332   encrypt a DRSUAPI attribute ready for sending over the wire
333   Only some attribute types are encrypted
334  */
335 WERROR drsuapi_encrypt_attribute(TALLOC_CTX *mem_ctx, 
336                                  const DATA_BLOB *gensec_skey,
337                                  uint32_t rid,
338                                  struct drsuapi_DsReplicaAttribute *attr)
339 {
340         WERROR status;
341         DATA_BLOB *plain_data;
342         DATA_BLOB enc_data;
343         bool rid_crypt = false;
344
345         if (attr->value_ctr.num_values == 0) {
346                 return WERR_OK;
347         }
348
349         switch (attr->attid) {
350         case DRSUAPI_ATTID_dBCSPwd:
351         case DRSUAPI_ATTID_unicodePwd:
352         case DRSUAPI_ATTID_ntPwdHistory:
353         case DRSUAPI_ATTID_lmPwdHistory:
354                 rid_crypt = true;
355                 break;
356         case DRSUAPI_ATTID_supplementalCredentials:
357         case DRSUAPI_ATTID_priorValue:
358         case DRSUAPI_ATTID_currentValue:
359         case DRSUAPI_ATTID_trustAuthOutgoing:
360         case DRSUAPI_ATTID_trustAuthIncoming:
361         case DRSUAPI_ATTID_initialAuthOutgoing:
362         case DRSUAPI_ATTID_initialAuthIncoming:
363                 break;
364         default:
365                 return WERR_OK;
366         }
367
368         if (attr->value_ctr.num_values > 1) {
369                 return WERR_DS_DRA_INVALID_PARAMETER;
370         }
371
372         if (!attr->value_ctr.values[0].blob) {
373                 return WERR_DS_DRA_INVALID_PARAMETER;
374         }
375
376         plain_data      = attr->value_ctr.values[0].blob;
377
378         status = drsuapi_encrypt_attribute_value(mem_ctx,
379                                                  gensec_skey,
380                                                  rid_crypt,
381                                                  rid,
382                                                  plain_data,
383                                                  &enc_data);
384         W_ERROR_NOT_OK_RETURN(status);
385
386         talloc_free(attr->value_ctr.values[0].blob->data);
387         *attr->value_ctr.values[0].blob = enc_data;
388
389         return WERR_OK;
390 }
391