1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /* Authors: Karl MacMillan <kmacmillan@tresys.com>
3 * Frank Mayer <mayerf@tresys.com>
4 * Copyright (C) 2003 - 2004 Tresys Technology, LLC
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/errno.h>
9 #include <linux/string.h>
10 #include <linux/spinlock.h>
11 #include <linux/slab.h>
12
13 #include "security.h"
14 #include "conditional.h"
15 #include "services.h"
16
17 /*
18 * cond_evaluate_expr evaluates a conditional expr
19 * in reverse polish notation. It returns true (1), false (0),
20 * or undefined (-1). Undefined occurs when the expression
21 * exceeds the stack depth of COND_EXPR_MAXDEPTH.
22 */
23 static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
24 {
25 u32 i;
26 int s[COND_EXPR_MAXDEPTH];
27 int sp = -1;
28
29 if (expr->len == 0)
30 return -1;
31
32 for (i = 0; i < expr->len; i++) {
33 struct cond_expr_node *node = &expr->nodes[i];
34
35 switch (node->expr_type) {
36 case COND_BOOL:
37 if (sp == (COND_EXPR_MAXDEPTH - 1))
38 return -1;
39 sp++;
40 s[sp] = p->bool_val_to_struct[node->boolean - 1]->state;
41 break;
42 case COND_NOT:
43 if (sp < 0)
44 return -1;
45 s[sp] = !s[sp];
46 break;
47 case COND_OR:
48 if (sp < 1)
49 return -1;
50 sp--;
51 s[sp] |= s[sp + 1];
52 break;
53 case COND_AND:
54 if (sp < 1)
55 return -1;
56 sp--;
57 s[sp] &= s[sp + 1];
58 break;
59 case COND_XOR:
60 if (sp < 1)
61 return -1;
62 sp--;
63 s[sp] ^= s[sp + 1];
64 break;
65 case COND_EQ:
66 if (sp < 1)
67 return -1;
68 sp--;
69 s[sp] = (s[sp] == s[sp + 1]);
70 break;
71 case COND_NEQ:
72 if (sp < 1)
73 return -1;
74 sp--;
75 s[sp] = (s[sp] != s[sp + 1]);
76 break;
77 default:
78 return -1;
79 }
80 }
81 return s[0];
82 }
83
84 /*
85 * evaluate_cond_node evaluates the conditional stored in
86 * a struct cond_node and if the result is different than the
87 * current state of the node it sets the rules in the true/false
88 * list appropriately. If the result of the expression is undefined
89 * all of the rules are disabled for safety.
90 */
91 static void evaluate_cond_node(struct policydb *p, struct cond_node *node)
92 {
93 struct avtab_node *avnode;
94 int new_state;
95 u32 i;
96
97 new_state = cond_evaluate_expr(p, &node->expr);
98 if (new_state != node->cur_state) {
99 node->cur_state = new_state;
100 if (new_state == -1)
101 pr_err("SELinux: expression result was undefined - disabling all rules.\n");
102 /* turn the rules on or off */
103 for (i = 0; i < node->true_list.len; i++) {
104 avnode = node->true_list.nodes[i];
105 if (new_state <= 0)
106 avnode->key.specified &= ~AVTAB_ENABLED;
107 else
108 avnode->key.specified |= AVTAB_ENABLED;
109 }
110
111 for (i = 0; i < node->false_list.len; i++) {
112 avnode = node->false_list.nodes[i];
113 /* -1 or 1 */
114 if (new_state)
115 avnode->key.specified &= ~AVTAB_ENABLED;
116 else
117 avnode->key.specified |= AVTAB_ENABLED;
118 }
119 }
120 }
121
122 void evaluate_cond_nodes(struct policydb *p)
123 {
124 u32 i;
125
126 for (i = 0; i < p->cond_list_len; i++)
127 evaluate_cond_node(p, &p->cond_list[i]);
128 }
129
130 void cond_policydb_init(struct policydb *p)
131 {
132 p->bool_val_to_struct = NULL;
133 p->cond_list = NULL;
134 p->cond_list_len = 0;
135
136 avtab_init(&p->te_cond_avtab);
137 }
138
139 static void cond_node_destroy(struct cond_node *node)
140 {
141 kfree(node->expr.nodes);
142 /* the avtab_ptr_t nodes are destroyed by the avtab */
143 kfree(node->true_list.nodes);
144 kfree(node->false_list.nodes);
145 }
146
147 static void cond_list_destroy(struct policydb *p)
148 {
149 u32 i;
150
151 for (i = 0; i < p->cond_list_len; i++)
152 cond_node_destroy(&p->cond_list[i]);
153 kfree(p->cond_list);
154 p->cond_list = NULL;
155 p->cond_list_len = 0;
156 }
157
158 void cond_policydb_destroy(struct policydb *p)
159 {
160 kfree(p->bool_val_to_struct);
161 avtab_destroy(&p->te_cond_avtab);
162 cond_list_destroy(p);
163 }
164
165 int cond_init_bool_indexes(struct policydb *p)
166 {
167 kfree(p->bool_val_to_struct);
168 p->bool_val_to_struct = kmalloc_array(
169 p->p_bools.nprim, sizeof(*p->bool_val_to_struct), GFP_KERNEL);
170 if (!p->bool_val_to_struct)
171 return -ENOMEM;
172
173 avtab_hash_eval(&p->te_cond_avtab, "conditional_rules");
174
175 return 0;
176 }
177
178 int cond_destroy_bool(void *key, void *datum, void *p)
179 {
180 kfree(key);
181 kfree(datum);
182 return 0;
183 }
184
185 int cond_index_bool(void *key, void *datum, void *datap)
186 {
187 struct policydb *p;
188 struct cond_bool_datum *booldatum;
189
190 booldatum = datum;
191 p = datap;
192
193 if (!booldatum->value || booldatum->value > p->p_bools.nprim)
194 return -EINVAL;
195
196 p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key;
197 p->bool_val_to_struct[booldatum->value - 1] = booldatum;
198
199 return 0;
200 }
201
202 static int bool_isvalid(struct cond_bool_datum *b)
203 {
204 if (!(b->state == 0 || b->state == 1))
205 return 0;
206 return 1;
207 }
208
209 int cond_read_bool(struct policydb *p, struct symtab *s, void *fp)
210 {
211 char *key = NULL;
212 struct cond_bool_datum *booldatum;
213 __le32 buf[3];
214 u32 len;
215 int rc;
216
217 booldatum = kzalloc(sizeof(*booldatum), GFP_KERNEL);
218 if (!booldatum)
219 return -ENOMEM;
220
221 rc = next_entry(buf, fp, sizeof(buf));
222 if (rc)
223 goto err;
224
225 booldatum->value = le32_to_cpu(buf[0]);
226 booldatum->state = le32_to_cpu(buf[1]);
227
228 rc = -EINVAL;
229 if (!bool_isvalid(booldatum))
230 goto err;
231
232 len = le32_to_cpu(buf[2]);
233 if (((len == 0) || (len == (u32)-1)))
234 goto err;
235
236 rc = -ENOMEM;
237 key = kmalloc(len + 1, GFP_KERNEL);
238 if (!key)
239 goto err;
240 rc = next_entry(key, fp, len);
241 if (rc)
242 goto err;
243 key[len] = '\0';
244 rc = symtab_insert(s, key, booldatum);
245 if (rc)
246 goto err;
247
248 return 0;
249 err:
250 cond_destroy_bool(key, booldatum, NULL);
251 return rc;
252 }
253
254 struct cond_insertf_data {
255 struct policydb *p;
256 struct avtab_node **dst;
257 struct cond_av_list *other;
258 };
259
260 static int cond_insertf(struct avtab *a, const struct avtab_key *k,
261 const struct avtab_datum *d, void *ptr)
262 {
263 struct cond_insertf_data *data = ptr;
264 struct policydb *p = data->p;
265 struct cond_av_list *other = data->other;
266 struct avtab_node *node_ptr;
267 u32 i;
268 bool found;
269
270 /*
271 * For type rules we have to make certain there aren't any
272 * conflicting rules by searching the te_avtab and the
273 * cond_te_avtab.
274 */
275 if (k->specified & AVTAB_TYPE) {
276 if (avtab_search_node(&p->te_avtab, k)) {
277 pr_err("SELinux: type rule already exists outside of a conditional.\n");
278 return -EINVAL;
279 }
280 /*
281 * If we are reading the false list other will be a pointer to
282 * the true list. We can have duplicate entries if there is only
283 * 1 other entry and it is in our true list.
284 *
285 * If we are reading the true list (other == NULL) there shouldn't
286 * be any other entries.
287 */
288 if (other) {
289 node_ptr = avtab_search_node(&p->te_cond_avtab, k);
290 if (node_ptr) {
291 if (avtab_search_node_next(node_ptr,
292 k->specified)) {
293 pr_err("SELinux: too many conflicting type rules.\n");
294 return -EINVAL;
295 }
296 found = false;
297 for (i = 0; i < other->len; i++) {
298 if (other->nodes[i] == node_ptr) {
299 found = true;
300 break;
301 }
302 }
303 if (!found) {
304 pr_err("SELinux: conflicting type rules.\n");
305 return -EINVAL;
306 }
307 }
308 } else {
309 if (avtab_search_node(&p->te_cond_avtab, k)) {
310 pr_err("SELinux: conflicting type rules when adding type rule for true.\n");
311 return -EINVAL;
312 }
313 }
314 }
315
316 node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d);
317 if (!node_ptr) {
318 pr_err("SELinux: could not insert rule.\n");
319 return -ENOMEM;
320 }
321
322 *data->dst = node_ptr;
323 return 0;
324 }
325
326 static int cond_read_av_list(struct policydb *p, void *fp,
327 struct cond_av_list *list,
328 struct cond_av_list *other)
329 {
330 int rc;
331 __le32 buf[1];
332 u32 i, len;
333 struct cond_insertf_data data;
334
335 rc = next_entry(buf, fp, sizeof(u32));
336 if (rc)
337 return rc;
338
339 len = le32_to_cpu(buf[0]);
340 if (len == 0)
341 return 0;
342
343 list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL);
344 if (!list->nodes)
345 return -ENOMEM;
346
347 data.p = p;
348 data.other = other;
349 for (i = 0; i < len; i++) {
350 data.dst = &list->nodes[i];
351 rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
352 &data);
353 if (rc) {
354 kfree(list->nodes);
355 list->nodes = NULL;
356 return rc;
357 }
358 }
359
360 list->len = len;
361 return 0;
362 }
363
364 static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr)
365 {
366 if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
367 pr_err("SELinux: conditional expressions uses unknown operator.\n");
368 return 0;
369 }
370
371 if (expr->boolean > p->p_bools.nprim) {
372 pr_err("SELinux: conditional expressions uses unknown bool.\n");
373 return 0;
374 }
375 return 1;
376 }
377
378 static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
379 {
380 __le32 buf[2];
381 u32 i, len;
382 int rc;
383
384 rc = next_entry(buf, fp, sizeof(u32) * 2);
385 if (rc)
386 return rc;
387
388 node->cur_state = le32_to_cpu(buf[0]);
389
390 /* expr */
391 len = le32_to_cpu(buf[1]);
392 node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL);
393 if (!node->expr.nodes)
394 return -ENOMEM;
395
396 node->expr.len = len;
397
398 for (i = 0; i < len; i++) {
399 struct cond_expr_node *expr = &node->expr.nodes[i];
400
401 rc = next_entry(buf, fp, sizeof(u32) * 2);
402 if (rc)
403 return rc;
404
405 expr->expr_type = le32_to_cpu(buf[0]);
406 expr->boolean = le32_to_cpu(buf[1]);
407
408 if (!expr_node_isvalid(p, expr))
409 return -EINVAL;
410 }
411
412 rc = cond_read_av_list(p, fp, &node->true_list, NULL);
413 if (rc)
414 return rc;
415 return cond_read_av_list(p, fp, &node->false_list, &node->true_list);
416 }
417
418 int cond_read_list(struct policydb *p, void *fp)
419 {
420 __le32 buf[1];
421 u32 i, len;
422 int rc;
423
424 rc = next_entry(buf, fp, sizeof(buf));
425 if (rc)
426 return rc;
427
428 len = le32_to_cpu(buf[0]);
429
430 p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL);
431 if (!p->cond_list)
432 return -ENOMEM;
433
434 rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel);
435 if (rc)
436 goto err;
437
438 p->cond_list_len = len;
439
440 for (i = 0; i < len; i++) {
441 rc = cond_read_node(p, &p->cond_list[i], fp);
442 if (rc)
443 goto err;
444 }
445 return 0;
446 err:
447 cond_list_destroy(p);
448 return rc;
449 }
450
451 int cond_write_bool(void *vkey, void *datum, void *ptr)
452 {
453 char *key = vkey;
454 struct cond_bool_datum *booldatum = datum;
455 struct policy_data *pd = ptr;
456 void *fp = pd->fp;
457 __le32 buf[3];
458 u32 len;
459 int rc;
460
461 len = strlen(key);
462 buf[0] = cpu_to_le32(booldatum->value);
463 buf[1] = cpu_to_le32(booldatum->state);
464 buf[2] = cpu_to_le32(len);
465 rc = put_entry(buf, sizeof(u32), 3, fp);
466 if (rc)
467 return rc;
468 rc = put_entry(key, 1, len, fp);
469 if (rc)
470 return rc;
471 return 0;
472 }
473
474 /*
475 * cond_write_cond_av_list doesn't write out the av_list nodes.
476 * Instead it writes out the key/value pairs from the avtab. This
477 * is necessary because there is no way to uniquely identifying rules
478 * in the avtab so it is not possible to associate individual rules
479 * in the avtab with a conditional without saving them as part of
480 * the conditional. This means that the avtab with the conditional
481 * rules will not be saved but will be rebuilt on policy load.
482 */
483 static int cond_write_av_list(struct policydb *p, struct cond_av_list *list,
484 struct policy_file *fp)
485 {
486 __le32 buf[1];
487 u32 i;
488 int rc;
489
490 buf[0] = cpu_to_le32(list->len);
491 rc = put_entry(buf, sizeof(u32), 1, fp);
492 if (rc)
493 return rc;
494
495 for (i = 0; i < list->len; i++) {
496 rc = avtab_write_item(p, list->nodes[i], fp);
497 if (rc)
498 return rc;
499 }
500
501 return 0;
502 }
503
504 static int cond_write_node(struct policydb *p, struct cond_node *node,
505 struct policy_file *fp)
506 {
507 __le32 buf[2];
508 int rc;
509 u32 i;
510
511 buf[0] = cpu_to_le32(node->cur_state);
512 rc = put_entry(buf, sizeof(u32), 1, fp);
513 if (rc)
514 return rc;
515
516 buf[0] = cpu_to_le32(node->expr.len);
517 rc = put_entry(buf, sizeof(u32), 1, fp);
518 if (rc)
519 return rc;
520
521 for (i = 0; i < node->expr.len; i++) {
522 buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type);
523 buf[1] = cpu_to_le32(node->expr.nodes[i].boolean);
524 rc = put_entry(buf, sizeof(u32), 2, fp);
525 if (rc)
526 return rc;
527 }
528
529 rc = cond_write_av_list(p, &node->true_list, fp);
530 if (rc)
531 return rc;
532 rc = cond_write_av_list(p, &node->false_list, fp);
533 if (rc)
534 return rc;
535
536 return 0;
537 }
538
539 int cond_write_list(struct policydb *p, void *fp)
540 {
541 u32 i;
542 __le32 buf[1];
543 int rc;
544
545 buf[0] = cpu_to_le32(p->cond_list_len);
546 rc = put_entry(buf, sizeof(u32), 1, fp);
547 if (rc)
548 return rc;
549
550 for (i = 0; i < p->cond_list_len; i++) {
551 rc = cond_write_node(p, &p->cond_list[i], fp);
552 if (rc)
553 return rc;
554 }
555
556 return 0;
557 }
558
559 void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key,
560 struct extended_perms_decision *xpermd)
561 {
562 struct avtab_node *node;
563
564 if (!ctab || !key || !xpermd)
565 return;
566
567 for (node = avtab_search_node(ctab, key); node;
568 node = avtab_search_node_next(node, key->specified)) {
569 if (node->key.specified & AVTAB_ENABLED)
570 services_compute_xperms_decision(xpermd, node);
571 }
572 }
573 /* Determine whether additional permissions are granted by the conditional
574 * av table, and if so, add them to the result
575 */
576 void cond_compute_av(struct avtab *ctab, struct avtab_key *key,
577 struct av_decision *avd, struct extended_perms *xperms)
578 {
579 struct avtab_node *node;
580
581 if (!ctab || !key || !avd)
582 return;
583
584 for (node = avtab_search_node(ctab, key); node;
585 node = avtab_search_node_next(node, key->specified)) {
586 if ((u16)(AVTAB_ALLOWED | AVTAB_ENABLED) ==
587 (node->key.specified & (AVTAB_ALLOWED | AVTAB_ENABLED)))
588 avd->allowed |= node->datum.u.data;
589 if ((u16)(AVTAB_AUDITDENY | AVTAB_ENABLED) ==
590 (node->key.specified & (AVTAB_AUDITDENY | AVTAB_ENABLED)))
591 /* Since a '' in an auditdeny mask represents a
592 * permission we do NOT want to audit (dontaudit), we use
593 * the '&' operand to ensure that all ''s in the mask
594 * are retained (much unlike the allow and auditallow cases).
595 */
596 avd->auditdeny &= node->datum.u.data;
597 if ((u16)(AVTAB_AUDITALLOW | AVTAB_ENABLED) ==
598 (node->key.specified & (AVTAB_AUDITALLOW | AVTAB_ENABLED)))
599 avd->auditallow |= node->datum.u.data;
600 if (xperms && (node->key.specified & AVTAB_ENABLED) &&
601 (node->key.specified & AVTAB_XPERMS))
602 services_compute_xperms_drivers(xperms, node);
603 }
604 }
605
606 static int cond_dup_av_list(struct cond_av_list *new,
607 const struct cond_av_list *orig,
608 struct avtab *avtab)
609 {
610 u32 i;
611
612 memset(new, 0, sizeof(*new));
613
614 new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL);
615 if (!new->nodes)
616 return -ENOMEM;
617
618 for (i = 0; i < orig->len; i++) {
619 new->nodes[i] = avtab_insert_nonunique(
620 avtab, &orig->nodes[i]->key, &orig->nodes[i]->datum);
621 if (!new->nodes[i])
622 return -ENOMEM;
623 new->len++;
624 }
625
626 return 0;
627 }
628
629 static int duplicate_policydb_cond_list(struct policydb *newp,
630 const struct policydb *origp)
631 {
632 int rc;
633 u32 i;
634
635 rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab);
636 if (rc)
637 return rc;
638
639 newp->cond_list_len = 0;
640 newp->cond_list = kcalloc(origp->cond_list_len,
641 sizeof(*newp->cond_list), GFP_KERNEL);
642 if (!newp->cond_list)
643 goto error;
644
645 for (i = 0; i < origp->cond_list_len; i++) {
646 struct cond_node *newn = &newp->cond_list[i];
647 const struct cond_node *orign = &origp->cond_list[i];
648
649 newp->cond_list_len++;
650
651 newn->cur_state = orign->cur_state;
652 newn->expr.nodes =
653 kmemdup(orign->expr.nodes,
654 orign->expr.len * sizeof(*orign->expr.nodes),
655 GFP_KERNEL);
656 if (!newn->expr.nodes)
657 goto error;
658
659 newn->expr.len = orign->expr.len;
660
661 rc = cond_dup_av_list(&newn->true_list, &orign->true_list,
662 &newp->te_cond_avtab);
663 if (rc)
664 goto error;
665
666 rc = cond_dup_av_list(&newn->false_list, &orign->false_list,
667 &newp->te_cond_avtab);
668 if (rc)
669 goto error;
670 }
671
672 return 0;
673
674 error:
675 avtab_destroy(&newp->te_cond_avtab);
676 cond_list_destroy(newp);
677 return -ENOMEM;
678 }
679
680 static int cond_bools_destroy(void *key, void *datum, void *args)
681 {
682 /* key was not copied so no need to free here */
683 kfree(datum);
684 return 0;
685 }
686
687 static int cond_bools_copy(struct hashtab_node *new,
688 const struct hashtab_node *orig, void *args)
689 {
690 struct cond_bool_datum *datum;
691
692 datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum),
693 GFP_KERNEL);
694 if (!datum)
695 return -ENOMEM;
696
697 new->key = orig->key; /* No need to copy, never modified */
698 new->datum = datum;
699 return 0;
700 }
701
702 static int cond_bools_index(void *key, void *datum, void *args)
703 {
704 struct cond_bool_datum *booldatum, **cond_bool_array;
705
706 booldatum = datum;
707 cond_bool_array = args;
708 cond_bool_array[booldatum->value - 1] = booldatum;
709
710 return 0;
711 }
712
713 static int duplicate_policydb_bools(struct policydb *newdb,
714 const struct policydb *orig)
715 {
716 struct cond_bool_datum **cond_bool_array;
717 int rc;
718
719 cond_bool_array = kmalloc_array(orig->p_bools.nprim,
720 sizeof(*orig->bool_val_to_struct),
721 GFP_KERNEL);
722 if (!cond_bool_array)
723 return -ENOMEM;
724
725 rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table,
726 cond_bools_copy, cond_bools_destroy, NULL);
727 if (rc) {
728 kfree(cond_bool_array);
729 return -ENOMEM;
730 }
731
732 hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array);
733 newdb->bool_val_to_struct = cond_bool_array;
734
735 newdb->p_bools.nprim = orig->p_bools.nprim;
736
737 return 0;
738 }
739
740 void cond_policydb_destroy_dup(struct policydb *p)
741 {
742 hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL);
743 hashtab_destroy(&p->p_bools.table);
744 cond_policydb_destroy(p);
745 }
746
747 int cond_policydb_dup(struct policydb *new, const struct policydb *orig)
748 {
749 cond_policydb_init(new);
750
751 if (duplicate_policydb_bools(new, orig))
752 return -ENOMEM;
753
754 if (duplicate_policydb_cond_list(new, orig)) {
755 cond_policydb_destroy_dup(new);
756 return -ENOMEM;
757 }
758
759 return 0;
760 }
761
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