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1da177e4 LT |
1 | /* Authors: Karl MacMillan <kmacmillan@tresys.com> |
2 | * Frank Mayer <mayerf@tresys.com> | |
3 | * | |
4 | * Copyright (C) 2003 - 2004 Tresys Technology, LLC | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation, version 2. | |
8 | */ | |
9 | ||
10 | #include <linux/kernel.h> | |
11 | #include <linux/errno.h> | |
12 | #include <linux/string.h> | |
13 | #include <linux/spinlock.h> | |
14 | #include <asm/semaphore.h> | |
15 | #include <linux/slab.h> | |
16 | ||
17 | #include "security.h" | |
18 | #include "conditional.h" | |
19 | ||
20 | /* | |
21 | * cond_evaluate_expr evaluates a conditional expr | |
22 | * in reverse polish notation. It returns true (1), false (0), | |
23 | * or undefined (-1). Undefined occurs when the expression | |
24 | * exceeds the stack depth of COND_EXPR_MAXDEPTH. | |
25 | */ | |
26 | static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr) | |
27 | { | |
28 | ||
29 | struct cond_expr *cur; | |
30 | int s[COND_EXPR_MAXDEPTH]; | |
31 | int sp = -1; | |
32 | ||
33 | for (cur = expr; cur != NULL; cur = cur->next) { | |
34 | switch (cur->expr_type) { | |
35 | case COND_BOOL: | |
36 | if (sp == (COND_EXPR_MAXDEPTH - 1)) | |
37 | return -1; | |
38 | sp++; | |
39 | s[sp] = p->bool_val_to_struct[cur->bool - 1]->state; | |
40 | break; | |
41 | case COND_NOT: | |
42 | if (sp < 0) | |
43 | return -1; | |
44 | s[sp] = !s[sp]; | |
45 | break; | |
46 | case COND_OR: | |
47 | if (sp < 1) | |
48 | return -1; | |
49 | sp--; | |
50 | s[sp] |= s[sp + 1]; | |
51 | break; | |
52 | case COND_AND: | |
53 | if (sp < 1) | |
54 | return -1; | |
55 | sp--; | |
56 | s[sp] &= s[sp + 1]; | |
57 | break; | |
58 | case COND_XOR: | |
59 | if (sp < 1) | |
60 | return -1; | |
61 | sp--; | |
62 | s[sp] ^= s[sp + 1]; | |
63 | break; | |
64 | case COND_EQ: | |
65 | if (sp < 1) | |
66 | return -1; | |
67 | sp--; | |
68 | s[sp] = (s[sp] == s[sp + 1]); | |
69 | break; | |
70 | case COND_NEQ: | |
71 | if (sp < 1) | |
72 | return -1; | |
73 | sp--; | |
74 | s[sp] = (s[sp] != s[sp + 1]); | |
75 | break; | |
76 | default: | |
77 | return -1; | |
78 | } | |
79 | } | |
80 | return s[0]; | |
81 | } | |
82 | ||
83 | /* | |
84 | * evaluate_cond_node evaluates the conditional stored in | |
85 | * a struct cond_node and if the result is different than the | |
86 | * current state of the node it sets the rules in the true/false | |
87 | * list appropriately. If the result of the expression is undefined | |
88 | * all of the rules are disabled for safety. | |
89 | */ | |
90 | int evaluate_cond_node(struct policydb *p, struct cond_node *node) | |
91 | { | |
92 | int new_state; | |
93 | struct cond_av_list* cur; | |
94 | ||
95 | new_state = cond_evaluate_expr(p, node->expr); | |
96 | if (new_state != node->cur_state) { | |
97 | node->cur_state = new_state; | |
98 | if (new_state == -1) | |
99 | printk(KERN_ERR "security: expression result was undefined - disabling all rules.\n"); | |
100 | /* turn the rules on or off */ | |
101 | for (cur = node->true_list; cur != NULL; cur = cur->next) { | |
102 | if (new_state <= 0) { | |
103 | cur->node->datum.specified &= ~AVTAB_ENABLED; | |
104 | } else { | |
105 | cur->node->datum.specified |= AVTAB_ENABLED; | |
106 | } | |
107 | } | |
108 | ||
109 | for (cur = node->false_list; cur != NULL; cur = cur->next) { | |
110 | /* -1 or 1 */ | |
111 | if (new_state) { | |
112 | cur->node->datum.specified &= ~AVTAB_ENABLED; | |
113 | } else { | |
114 | cur->node->datum.specified |= AVTAB_ENABLED; | |
115 | } | |
116 | } | |
117 | } | |
118 | return 0; | |
119 | } | |
120 | ||
121 | int cond_policydb_init(struct policydb *p) | |
122 | { | |
123 | p->bool_val_to_struct = NULL; | |
124 | p->cond_list = NULL; | |
125 | if (avtab_init(&p->te_cond_avtab)) | |
126 | return -1; | |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
131 | static void cond_av_list_destroy(struct cond_av_list *list) | |
132 | { | |
133 | struct cond_av_list *cur, *next; | |
134 | for (cur = list; cur != NULL; cur = next) { | |
135 | next = cur->next; | |
136 | /* the avtab_ptr_t node is destroy by the avtab */ | |
137 | kfree(cur); | |
138 | } | |
139 | } | |
140 | ||
141 | static void cond_node_destroy(struct cond_node *node) | |
142 | { | |
143 | struct cond_expr *cur_expr, *next_expr; | |
144 | ||
145 | for (cur_expr = node->expr; cur_expr != NULL; cur_expr = next_expr) { | |
146 | next_expr = cur_expr->next; | |
147 | kfree(cur_expr); | |
148 | } | |
149 | cond_av_list_destroy(node->true_list); | |
150 | cond_av_list_destroy(node->false_list); | |
151 | kfree(node); | |
152 | } | |
153 | ||
154 | static void cond_list_destroy(struct cond_node *list) | |
155 | { | |
156 | struct cond_node *next, *cur; | |
157 | ||
158 | if (list == NULL) | |
159 | return; | |
160 | ||
161 | for (cur = list; cur != NULL; cur = next) { | |
162 | next = cur->next; | |
163 | cond_node_destroy(cur); | |
164 | } | |
165 | } | |
166 | ||
167 | void cond_policydb_destroy(struct policydb *p) | |
168 | { | |
9a5f04bf | 169 | kfree(p->bool_val_to_struct); |
1da177e4 LT |
170 | avtab_destroy(&p->te_cond_avtab); |
171 | cond_list_destroy(p->cond_list); | |
172 | } | |
173 | ||
174 | int cond_init_bool_indexes(struct policydb *p) | |
175 | { | |
9a5f04bf | 176 | kfree(p->bool_val_to_struct); |
1da177e4 LT |
177 | p->bool_val_to_struct = (struct cond_bool_datum**) |
178 | kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum*), GFP_KERNEL); | |
179 | if (!p->bool_val_to_struct) | |
180 | return -1; | |
181 | return 0; | |
182 | } | |
183 | ||
184 | int cond_destroy_bool(void *key, void *datum, void *p) | |
185 | { | |
9a5f04bf | 186 | kfree(key); |
1da177e4 LT |
187 | kfree(datum); |
188 | return 0; | |
189 | } | |
190 | ||
191 | int cond_index_bool(void *key, void *datum, void *datap) | |
192 | { | |
193 | struct policydb *p; | |
194 | struct cond_bool_datum *booldatum; | |
195 | ||
196 | booldatum = datum; | |
197 | p = datap; | |
198 | ||
199 | if (!booldatum->value || booldatum->value > p->p_bools.nprim) | |
200 | return -EINVAL; | |
201 | ||
202 | p->p_bool_val_to_name[booldatum->value - 1] = key; | |
203 | p->bool_val_to_struct[booldatum->value -1] = booldatum; | |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
208 | static int bool_isvalid(struct cond_bool_datum *b) | |
209 | { | |
210 | if (!(b->state == 0 || b->state == 1)) | |
211 | return 0; | |
212 | return 1; | |
213 | } | |
214 | ||
215 | int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp) | |
216 | { | |
217 | char *key = NULL; | |
218 | struct cond_bool_datum *booldatum; | |
219 | u32 buf[3], len; | |
220 | int rc; | |
221 | ||
222 | booldatum = kmalloc(sizeof(struct cond_bool_datum), GFP_KERNEL); | |
223 | if (!booldatum) | |
224 | return -1; | |
225 | memset(booldatum, 0, sizeof(struct cond_bool_datum)); | |
226 | ||
227 | rc = next_entry(buf, fp, sizeof buf); | |
228 | if (rc < 0) | |
229 | goto err; | |
230 | ||
231 | booldatum->value = le32_to_cpu(buf[0]); | |
232 | booldatum->state = le32_to_cpu(buf[1]); | |
233 | ||
234 | if (!bool_isvalid(booldatum)) | |
235 | goto err; | |
236 | ||
237 | len = le32_to_cpu(buf[2]); | |
238 | ||
239 | key = kmalloc(len + 1, GFP_KERNEL); | |
240 | if (!key) | |
241 | goto err; | |
242 | rc = next_entry(key, fp, len); | |
243 | if (rc < 0) | |
244 | goto err; | |
245 | key[len] = 0; | |
246 | if (hashtab_insert(h, key, booldatum)) | |
247 | goto err; | |
248 | ||
249 | return 0; | |
250 | err: | |
251 | cond_destroy_bool(key, booldatum, NULL); | |
252 | return -1; | |
253 | } | |
254 | ||
255 | static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list, | |
256 | struct cond_av_list *other) | |
257 | { | |
258 | struct cond_av_list *list, *last = NULL, *cur; | |
259 | struct avtab_key key; | |
260 | struct avtab_datum datum; | |
261 | struct avtab_node *node_ptr; | |
262 | int rc; | |
263 | u32 buf[1], i, len; | |
264 | u8 found; | |
265 | ||
266 | *ret_list = NULL; | |
267 | ||
268 | len = 0; | |
269 | rc = next_entry(buf, fp, sizeof buf); | |
270 | if (rc < 0) | |
271 | return -1; | |
272 | ||
273 | len = le32_to_cpu(buf[0]); | |
274 | if (len == 0) { | |
275 | return 0; | |
276 | } | |
277 | ||
278 | for (i = 0; i < len; i++) { | |
279 | if (avtab_read_item(fp, &datum, &key)) | |
280 | goto err; | |
281 | ||
282 | /* | |
283 | * For type rules we have to make certain there aren't any | |
284 | * conflicting rules by searching the te_avtab and the | |
285 | * cond_te_avtab. | |
286 | */ | |
287 | if (datum.specified & AVTAB_TYPE) { | |
288 | if (avtab_search(&p->te_avtab, &key, AVTAB_TYPE)) { | |
289 | printk("security: type rule already exists outside of a conditional."); | |
290 | goto err; | |
291 | } | |
292 | /* | |
293 | * If we are reading the false list other will be a pointer to | |
294 | * the true list. We can have duplicate entries if there is only | |
295 | * 1 other entry and it is in our true list. | |
296 | * | |
297 | * If we are reading the true list (other == NULL) there shouldn't | |
298 | * be any other entries. | |
299 | */ | |
300 | if (other) { | |
301 | node_ptr = avtab_search_node(&p->te_cond_avtab, &key, AVTAB_TYPE); | |
302 | if (node_ptr) { | |
303 | if (avtab_search_node_next(node_ptr, AVTAB_TYPE)) { | |
304 | printk("security: too many conflicting type rules."); | |
305 | goto err; | |
306 | } | |
307 | found = 0; | |
308 | for (cur = other; cur != NULL; cur = cur->next) { | |
309 | if (cur->node == node_ptr) { | |
310 | found = 1; | |
311 | break; | |
312 | } | |
313 | } | |
314 | if (!found) { | |
315 | printk("security: conflicting type rules."); | |
316 | goto err; | |
317 | } | |
318 | } | |
319 | } else { | |
320 | if (avtab_search(&p->te_cond_avtab, &key, AVTAB_TYPE)) { | |
321 | printk("security: conflicting type rules when adding type rule for true."); | |
322 | goto err; | |
323 | } | |
324 | } | |
325 | } | |
326 | node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, &key, &datum); | |
327 | if (!node_ptr) { | |
328 | printk("security: could not insert rule."); | |
329 | goto err; | |
330 | } | |
331 | ||
332 | list = kmalloc(sizeof(struct cond_av_list), GFP_KERNEL); | |
333 | if (!list) | |
334 | goto err; | |
335 | memset(list, 0, sizeof(struct cond_av_list)); | |
336 | ||
337 | list->node = node_ptr; | |
338 | if (i == 0) | |
339 | *ret_list = list; | |
340 | else | |
341 | last->next = list; | |
342 | last = list; | |
343 | ||
344 | } | |
345 | ||
346 | return 0; | |
347 | err: | |
348 | cond_av_list_destroy(*ret_list); | |
349 | *ret_list = NULL; | |
350 | return -1; | |
351 | } | |
352 | ||
353 | static int expr_isvalid(struct policydb *p, struct cond_expr *expr) | |
354 | { | |
355 | if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { | |
356 | printk("security: conditional expressions uses unknown operator.\n"); | |
357 | return 0; | |
358 | } | |
359 | ||
360 | if (expr->bool > p->p_bools.nprim) { | |
361 | printk("security: conditional expressions uses unknown bool.\n"); | |
362 | return 0; | |
363 | } | |
364 | return 1; | |
365 | } | |
366 | ||
367 | static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp) | |
368 | { | |
369 | u32 buf[2], len, i; | |
370 | int rc; | |
371 | struct cond_expr *expr = NULL, *last = NULL; | |
372 | ||
373 | rc = next_entry(buf, fp, sizeof(u32)); | |
374 | if (rc < 0) | |
375 | return -1; | |
376 | ||
377 | node->cur_state = le32_to_cpu(buf[0]); | |
378 | ||
379 | len = 0; | |
380 | rc = next_entry(buf, fp, sizeof(u32)); | |
381 | if (rc < 0) | |
382 | return -1; | |
383 | ||
384 | /* expr */ | |
385 | len = le32_to_cpu(buf[0]); | |
386 | ||
387 | for (i = 0; i < len; i++ ) { | |
388 | rc = next_entry(buf, fp, sizeof(u32) * 2); | |
389 | if (rc < 0) | |
390 | goto err; | |
391 | ||
392 | expr = kmalloc(sizeof(struct cond_expr), GFP_KERNEL); | |
393 | if (!expr) { | |
394 | goto err; | |
395 | } | |
396 | memset(expr, 0, sizeof(struct cond_expr)); | |
397 | ||
398 | expr->expr_type = le32_to_cpu(buf[0]); | |
399 | expr->bool = le32_to_cpu(buf[1]); | |
400 | ||
401 | if (!expr_isvalid(p, expr)) { | |
402 | kfree(expr); | |
403 | goto err; | |
404 | } | |
405 | ||
406 | if (i == 0) { | |
407 | node->expr = expr; | |
408 | } else { | |
409 | last->next = expr; | |
410 | } | |
411 | last = expr; | |
412 | } | |
413 | ||
414 | if (cond_read_av_list(p, fp, &node->true_list, NULL) != 0) | |
415 | goto err; | |
416 | if (cond_read_av_list(p, fp, &node->false_list, node->true_list) != 0) | |
417 | goto err; | |
418 | return 0; | |
419 | err: | |
420 | cond_node_destroy(node); | |
421 | return -1; | |
422 | } | |
423 | ||
424 | int cond_read_list(struct policydb *p, void *fp) | |
425 | { | |
426 | struct cond_node *node, *last = NULL; | |
427 | u32 buf[1], i, len; | |
428 | int rc; | |
429 | ||
430 | rc = next_entry(buf, fp, sizeof buf); | |
431 | if (rc < 0) | |
432 | return -1; | |
433 | ||
434 | len = le32_to_cpu(buf[0]); | |
435 | ||
436 | for (i = 0; i < len; i++) { | |
437 | node = kmalloc(sizeof(struct cond_node), GFP_KERNEL); | |
438 | if (!node) | |
439 | goto err; | |
440 | memset(node, 0, sizeof(struct cond_node)); | |
441 | ||
442 | if (cond_read_node(p, node, fp) != 0) | |
443 | goto err; | |
444 | ||
445 | if (i == 0) { | |
446 | p->cond_list = node; | |
447 | } else { | |
448 | last->next = node; | |
449 | } | |
450 | last = node; | |
451 | } | |
452 | return 0; | |
453 | err: | |
454 | cond_list_destroy(p->cond_list); | |
455 | return -1; | |
456 | } | |
457 | ||
458 | /* Determine whether additional permissions are granted by the conditional | |
459 | * av table, and if so, add them to the result | |
460 | */ | |
461 | void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd) | |
462 | { | |
463 | struct avtab_node *node; | |
464 | ||
465 | if(!ctab || !key || !avd) | |
466 | return; | |
467 | ||
468 | for(node = avtab_search_node(ctab, key, AVTAB_AV); node != NULL; | |
469 | node = avtab_search_node_next(node, AVTAB_AV)) { | |
470 | if ( (__u32) (AVTAB_ALLOWED|AVTAB_ENABLED) == | |
471 | (node->datum.specified & (AVTAB_ALLOWED|AVTAB_ENABLED))) | |
472 | avd->allowed |= avtab_allowed(&node->datum); | |
473 | if ( (__u32) (AVTAB_AUDITDENY|AVTAB_ENABLED) == | |
474 | (node->datum.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED))) | |
475 | /* Since a '0' in an auditdeny mask represents a | |
476 | * permission we do NOT want to audit (dontaudit), we use | |
477 | * the '&' operand to ensure that all '0's in the mask | |
478 | * are retained (much unlike the allow and auditallow cases). | |
479 | */ | |
480 | avd->auditdeny &= avtab_auditdeny(&node->datum); | |
481 | if ( (__u32) (AVTAB_AUDITALLOW|AVTAB_ENABLED) == | |
482 | (node->datum.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED))) | |
483 | avd->auditallow |= avtab_auditallow(&node->datum); | |
484 | } | |
485 | return; | |
486 | } |