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