summaryrefslogtreecommitdiff
path: root/source4/dsdb/samdb/ldb_modules/acl_read.c
blob: cde6d11c75bd07d4f6dd032e9f01d2b8e78eb2a9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
/*
  ldb database library

  Copyright (C) Simo Sorce 2006-2008
  Copyright (C) Nadezhda Ivanova 2010

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
 *  Name: ldb
 *
 *  Component: ldb ACL Read module
 *
 *  Description: Module that performs authorisation access checks on read requests
 *               Only DACL checks implemented at this point
 *
 *  Author: Nadezhda Ivanova
 */

#include "includes.h"
#include "ldb_module.h"
#include "auth/auth.h"
#include "libcli/security/security.h"
#include "dsdb/samdb/samdb.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "param/param.h"
#include "dsdb/samdb/ldb_modules/util.h"


struct aclread_context {
	struct ldb_module *module;
	struct ldb_request *req;
	const char * const *attrs;
	const struct dsdb_schema *schema;
	bool sd;
	bool instance_type;
	bool object_sid;
};

struct aclread_private {
	bool enabled;
};

static void aclread_mark_inaccesslible(struct ldb_message_element *el) {
	 el->flags |= LDB_FLAG_INTERNAL_INACCESSIBLE_ATTRIBUTE;
}

static bool aclread_is_inaccessible(struct ldb_message_element *el) {
	return el->flags & LDB_FLAG_INTERNAL_INACCESSIBLE_ATTRIBUTE;
}

static int aclread_callback(struct ldb_request *req, struct ldb_reply *ares)
{
	 struct ldb_context *ldb;
	 struct aclread_context *ac;
	 struct ldb_message *ret_msg;
	 struct ldb_message *msg;
	 int ret, num_of_attrs = 0;
	 unsigned int i, k = 0;
	 struct security_descriptor *sd;
	 struct dom_sid *sid = NULL;
	 TALLOC_CTX *tmp_ctx;
	 uint32_t instanceType;

	 ac = talloc_get_type(req->context, struct aclread_context);
	 ldb = ldb_module_get_ctx(ac->module);
	 if (!ares) {
		 return ldb_module_done(ac->req, NULL, NULL, LDB_ERR_OPERATIONS_ERROR );
	 }
	 if (ares->error != LDB_SUCCESS) {
		 return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	 }
	 tmp_ctx = talloc_new(ac);
	 switch (ares->type) {
	 case LDB_REPLY_ENTRY:
		 msg = ares->message;
		 ret = dsdb_get_sd_from_ldb_message(ldb, tmp_ctx, msg, &sd);
		 if (ret != LDB_SUCCESS || sd == NULL ) {
			 DEBUG(10, ("acl_read: cannot get descriptor\n"));
			 ret = LDB_ERR_OPERATIONS_ERROR;
			 goto fail;
		 }
		 sid = samdb_result_dom_sid(tmp_ctx, msg, "objectSid");
		 /* get the object instance type */
		 instanceType = ldb_msg_find_attr_as_uint(msg,
							 "instanceType", 0);
		 if (!ldb_dn_is_null(msg->dn) && !(instanceType & INSTANCE_TYPE_IS_NC_HEAD))
		 {
			/* the object has a parent, so we have to check for visibility */
			struct ldb_dn *parent_dn = ldb_dn_get_parent(tmp_ctx, msg->dn);
			ret = dsdb_module_check_access_on_dn(ac->module,
							     tmp_ctx,
							     parent_dn,
							     SEC_ADS_LIST,
							     NULL, req);
			if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
				talloc_free(tmp_ctx);
				return LDB_SUCCESS;
			} else if (ret != LDB_SUCCESS) {
				goto fail;
			}
		 }
		 /* for every element in the message check RP */
		 for (i=0; i < msg->num_elements; i++) {
			 const struct dsdb_attribute *attr;
			 bool is_sd, is_objectsid, is_instancetype;
			 uint32_t access_mask;
			 attr =  dsdb_attribute_by_lDAPDisplayName(ac->schema,
								   msg->elements[i].name);
			 if (!attr) {
				 DEBUG(2, ("acl_read: cannot find attribute %s in schema\n",
					   msg->elements[i].name));
				 ret = LDB_ERR_OPERATIONS_ERROR;
				 goto fail;
			 }
			 is_sd = ldb_attr_cmp("nTSecurityDescriptor",
					      msg->elements[i].name) == 0;
			 is_objectsid = ldb_attr_cmp("objectSid",
						     msg->elements[i].name) == 0;
			 is_instancetype = ldb_attr_cmp("instanceType",
							msg->elements[i].name) == 0;
			 /* these attributes were added to perform access checks and must be removed */
			 if (is_objectsid && ac->object_sid) {
				 aclread_mark_inaccesslible(&msg->elements[i]);
				 continue;
			 }
			 if (is_instancetype && ac->instance_type) {
				 aclread_mark_inaccesslible(&msg->elements[i]);
				 continue;
			 }
			 if (is_sd && ac->sd) {
				 aclread_mark_inaccesslible(&msg->elements[i]);
				 continue;
			 }
			 /* nTSecurityDescriptor is a special case */
			 if (is_sd) {
				 access_mask = SEC_FLAG_SYSTEM_SECURITY|SEC_STD_READ_CONTROL;
			 } else {
				 access_mask = SEC_ADS_READ_PROP;
			 }
			 ret = acl_check_access_on_attribute(ac->module,
							     tmp_ctx,
							     sd,
							     sid,
							     access_mask,
							     attr);

			 if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
				 /* do not return this entry if attribute is
				    part of the search filter */
				 if (dsdb_attr_in_parse_tree(ac->req->op.search.tree,
							     msg->elements[i].name)) {
					 talloc_free(tmp_ctx);
					 return LDB_SUCCESS;
				 }
				 aclread_mark_inaccesslible(&msg->elements[i]);
			 } else if (ret != LDB_SUCCESS) {
				 goto fail;
			 }
		 }
		 for (i=0; i < msg->num_elements; i++) {
			 if (!aclread_is_inaccessible(&msg->elements[i])) {
				 num_of_attrs++;
			 }
		 }
		 /*create a new message to return*/
		 ret_msg = ldb_msg_new(ac->req);
		 ret_msg->dn = msg->dn;
		 talloc_steal(ret_msg, msg->dn);
		 ret_msg->num_elements = num_of_attrs;
		 if (num_of_attrs > 0) {
			 ret_msg->elements = talloc_array(ret_msg,
							  struct ldb_message_element,
							  num_of_attrs);
			 if (ret_msg->elements == NULL) {
				 return ldb_oom(ldb);
			 }
			 for (i=0; i < msg->num_elements; i++) {
				 bool to_remove = aclread_is_inaccessible(&msg->elements[i]);
				 if (!to_remove) {
					 ret_msg->elements[k] = msg->elements[i];
					 talloc_steal(ret_msg->elements, msg->elements[i].name);
					 talloc_steal(ret_msg->elements, msg->elements[i].values);
					 k++;
				 }
			 }
		 } else {
			 ret_msg->elements = NULL;
		 }
		 talloc_free(tmp_ctx);

		 return ldb_module_send_entry(ac->req, ret_msg, ares->controls);
	 case LDB_REPLY_REFERRAL:
		 return ldb_module_send_referral(ac->req, ares->referral);
	 case LDB_REPLY_DONE:
		 return ldb_module_done(ac->req, ares->controls,
					ares->response, LDB_SUCCESS);

	 }
	 return LDB_SUCCESS;
fail:
	 talloc_free(tmp_ctx);
	 return ldb_module_done(ac->req, NULL, NULL, ret);
}


static int aclread_search(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;
	int ret;
	struct aclread_context *ac;
	struct ldb_request *down_req;
	struct ldb_control *as_system = ldb_request_get_control(req, LDB_CONTROL_AS_SYSTEM_OID);
	struct ldb_result *res;
	struct aclread_private *p;
	bool is_untrusted = ldb_req_is_untrusted(req);
	const char * const *attrs = NULL;
	uint32_t instanceType;
	static const char *acl_attrs[] = {
		 "instanceType",
		 NULL
	};

	ldb = ldb_module_get_ctx(module);
	p = talloc_get_type(ldb_module_get_private(module), struct aclread_private);

	/* skip access checks if we are system or system control is supplied
	 * or this is not LDAP server request */
	if (!p || !p->enabled ||
	    dsdb_module_am_system(module)
	    || as_system || !is_untrusted) {
		return ldb_next_request(module, req);
	}
	/* no checks on special dn */
	if (ldb_dn_is_special(req->op.search.base)) {
		return ldb_next_request(module, req);
	}

	/* check accessibility of base */
	if (!ldb_dn_is_null(req->op.search.base)) {
		ret = dsdb_module_search_dn(module, req, &res, req->op.search.base,
					    acl_attrs,
					    DSDB_FLAG_NEXT_MODULE |
					    DSDB_SEARCH_SHOW_DELETED, req);
		if (ret != LDB_SUCCESS) {
			return ldb_error(ldb, ret,
					 "acl_read: Error retrieving instanceType for base.");
		}
		instanceType = ldb_msg_find_attr_as_uint(res->msgs[0],
							 "instanceType", 0);
		if (instanceType != 0 && !(instanceType & INSTANCE_TYPE_IS_NC_HEAD))
		{
			/* the object has a parent, so we have to check for visibility */
			struct ldb_dn *parent_dn = ldb_dn_get_parent(req, req->op.search.base);
			ret = dsdb_module_check_access_on_dn(module,
							     req,
							     parent_dn,
							     SEC_ADS_LIST,
							     NULL, req);
			if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
				return ldb_module_done(req, NULL, NULL, LDB_ERR_NO_SUCH_OBJECT);
			} else if (ret != LDB_SUCCESS) {
				return ldb_module_done(req, NULL, NULL, ret);
			}
		}
	}
	ac = talloc_zero(req, struct aclread_context);
	if (ac == NULL) {
		return ldb_oom(ldb);
	}
	ac->module = module;
	ac->req = req;
	ac->schema = dsdb_get_schema(ldb, req);
	if (!ac->schema) {
		return ldb_operr(ldb);
	}
	ac->sd = !(ldb_attr_in_list(req->op.search.attrs, "nTSecurityDescriptor"));
	if (req->op.search.attrs && !ldb_attr_in_list(req->op.search.attrs, "*")) {
		if (!ldb_attr_in_list(req->op.search.attrs, "instanceType")) {
			ac->instance_type = true;
			attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "instanceType");
		} else {
			attrs = req->op.search.attrs;
		}
		if (!ldb_attr_in_list(req->op.search.attrs, "objectSid")) {
			ac->object_sid = true;
			attrs = ldb_attr_list_copy_add(ac, attrs, "objectSid");
		}
	}

	if (ac->sd) {
		/* avoid replacing all attributes with nTSecurityDescriptor
		 * if attribute list is empty */
		if (!attrs) {
			attrs = ldb_attr_list_copy_add(ac, attrs, "*");
		}
		attrs = ldb_attr_list_copy_add(ac, attrs, "nTSecurityDescriptor");
	}
	ac->attrs = req->op.search.attrs;
	ret = ldb_build_search_req_ex(&down_req,
				      ldb, ac,
				      req->op.search.base,
				      req->op.search.scope,
				      req->op.search.tree,
				      attrs,
				      req->controls,
				      ac, aclread_callback,
				      req);

	if (ret != LDB_SUCCESS) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	return ldb_next_request(module, down_req);
}

static int aclread_init(struct ldb_module *module)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct aclread_private *p = talloc_zero(module, struct aclread_private);
	if (p == NULL) {
		return ldb_module_oom(module);
	}
	p->enabled = lpcfg_parm_bool(ldb_get_opaque(ldb, "loadparm"), NULL, "acl", "search", false);
	ldb_module_set_private(module, p);
	return ldb_next_init(module);
}

static const struct ldb_module_ops ldb_aclread_module_ops = {
	.name		   = "aclread",
	.search            = aclread_search,
	.init_context      = aclread_init
};

int ldb_aclread_module_init(const char *version)
{
	LDB_MODULE_CHECK_VERSION(version);
	return ldb_register_module(&ldb_aclread_module_ops);
}