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
|
/*
Unix SMB/CIFS implementation.
security access checking routines
Copyright (C) Andrew Tridgell 2004
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/>.
*/
#include "includes.h"
#include "libcli/security/security.h"
/*
perform a SEC_FLAG_MAXIMUM_ALLOWED access check
*/
static uint32_t access_check_max_allowed(const struct security_descriptor *sd,
const struct security_token *token)
{
uint32_t denied = 0, granted = 0;
unsigned i;
if (security_token_has_sid(token, sd->owner_sid)) {
granted |= SEC_STD_WRITE_DAC | SEC_STD_READ_CONTROL | SEC_STD_DELETE;
} else if (security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
granted |= SEC_STD_DELETE;
}
if (sd->dacl == NULL) {
return granted & ~denied;
}
for (i = 0;i<sd->dacl->num_aces; i++) {
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (!security_token_has_sid(token, &ace->trustee)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
granted |= ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
denied |= ace->access_mask;
break;
default: /* Other ACE types not handled/supported */
break;
}
}
return granted & ~denied;
}
static const struct GUID *get_ace_object_type(struct security_ace *ace)
{
struct GUID *type;
if (ace->object.object.flags & SEC_ACE_OBJECT_TYPE_PRESENT)
type = &ace->object.object.type.type;
else if (ace->object.object.flags & SEC_ACE_INHERITED_OBJECT_TYPE_PRESENT)
type = &ace->object.object.inherited_type.inherited_type; /* This doesn't look right. Is something wrong with the IDL? */
else
type = NULL;
return type;
}
/*
the main entry point for access checking.
*/
NTSTATUS sec_access_check(const struct security_descriptor *sd,
const struct security_token *token,
uint32_t access_desired,
uint32_t *access_granted)
{
int i;
uint32_t bits_remaining;
*access_granted = access_desired;
bits_remaining = access_desired;
/* handle the maximum allowed flag */
if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
access_desired |= access_check_max_allowed(sd, token);
access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
*access_granted = access_desired;
bits_remaining = access_desired & ~SEC_STD_DELETE;
}
if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
if (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
return NT_STATUS_PRIVILEGE_NOT_HELD;
}
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
/* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
}
if ((bits_remaining & SEC_RIGHTS_PRIV_RESTORE) &&
security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
bits_remaining &= ~(SEC_RIGHTS_PRIV_RESTORE);
}
if ((bits_remaining & SEC_RIGHTS_PRIV_BACKUP) &&
security_token_has_privilege(token, SEC_PRIV_BACKUP)) {
bits_remaining &= ~(SEC_RIGHTS_PRIV_BACKUP);
}
if (sd->dacl == NULL) {
goto done;
}
/* check each ace in turn. */
for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (!security_token_has_sid(token, &ace->trustee)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
bits_remaining &= ~ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
if (bits_remaining & ace->access_mask) {
return NT_STATUS_ACCESS_DENIED;
}
break;
default: /* Other ACE types not handled/supported */
break;
}
}
done:
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
/* modified access check for the purposes of DS security
* Lots of code duplication, it will ve united in just one
* function eventually */
NTSTATUS sec_access_check_ds(const struct security_descriptor *sd,
const struct security_token *token,
uint32_t access_desired,
uint32_t *access_granted,
struct object_tree *tree)
{
int i;
uint32_t bits_remaining;
struct object_tree *node;
const struct GUID *type;
*access_granted = access_desired;
bits_remaining = access_desired;
/* handle the maximum allowed flag */
if (access_desired & SEC_FLAG_MAXIMUM_ALLOWED) {
access_desired |= access_check_max_allowed(sd, token);
access_desired &= ~SEC_FLAG_MAXIMUM_ALLOWED;
*access_granted = access_desired;
bits_remaining = access_desired & ~SEC_STD_DELETE;
}
if (access_desired & SEC_FLAG_SYSTEM_SECURITY) {
if (security_token_has_privilege(token, SEC_PRIV_SECURITY)) {
bits_remaining &= ~SEC_FLAG_SYSTEM_SECURITY;
} else {
return NT_STATUS_PRIVILEGE_NOT_HELD;
}
}
/* a NULL dacl allows access */
if ((sd->type & SEC_DESC_DACL_PRESENT) && sd->dacl == NULL) {
*access_granted = access_desired;
return NT_STATUS_OK;
}
/* the owner always gets SEC_STD_WRITE_DAC, SEC_STD_READ_CONTROL and SEC_STD_DELETE */
if ((bits_remaining & (SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE)) &&
security_token_has_sid(token, sd->owner_sid)) {
bits_remaining &= ~(SEC_STD_WRITE_DAC|SEC_STD_READ_CONTROL|SEC_STD_DELETE);
}
if ((bits_remaining & SEC_STD_DELETE) &&
security_token_has_privilege(token, SEC_PRIV_RESTORE)) {
bits_remaining &= ~SEC_STD_DELETE;
}
if (sd->dacl == NULL) {
goto done;
}
/* check each ace in turn. */
for (i=0; bits_remaining && i < sd->dacl->num_aces; i++) {
struct security_ace *ace = &sd->dacl->aces[i];
if (ace->flags & SEC_ACE_FLAG_INHERIT_ONLY) {
continue;
}
if (!security_token_has_sid(token, &ace->trustee)) {
continue;
}
switch (ace->type) {
case SEC_ACE_TYPE_ACCESS_ALLOWED:
if (tree)
object_tree_modify_access(tree, ace->access_mask);
bits_remaining &= ~ace->access_mask;
break;
case SEC_ACE_TYPE_ACCESS_DENIED:
if (bits_remaining & ace->access_mask) {
return NT_STATUS_ACCESS_DENIED;
}
break;
case SEC_ACE_TYPE_ACCESS_DENIED_OBJECT:
case SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT:
/* check only in case we have provided a tree,
* the ACE has an object type and that type
* is in the tree */
type = get_ace_object_type(ace);
if (!tree)
continue;
if (!type)
node = tree;
else
if (!(node = get_object_tree_by_GUID(tree, type)))
continue;
if (ace->type == SEC_ACE_TYPE_ACCESS_ALLOWED_OBJECT){
object_tree_modify_access(node, ace->access_mask);
}
else {
if (node->remaining_access & ace->access_mask){
return NT_STATUS_ACCESS_DENIED;
}
}
break;
default: /* Other ACE types not handled/supported */
break;
}
}
done:
if (bits_remaining != 0) {
return NT_STATUS_ACCESS_DENIED;
}
return NT_STATUS_OK;
}
|
