1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Implementation of the access vector table type.
4 *
5 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
6 */
7
8/* Updated: Frank Mayer <mayerf@tresys.com> and
9 *          Karl MacMillan <kmacmillan@tresys.com>
10 *          Added conditional policy language extensions
11 *          Copyright (C) 2003 Tresys Technology, LLC
12 *
13 * Updated: Yuichi Nakamura <ynakam@hitachisoft.jp>
14 *          Tuned number of hash slots for avtab to reduce memory usage
15 */
16
17#include <linux/bitops.h>
18#include <linux/kernel.h>
19#include <linux/slab.h>
20#include <linux/errno.h>
21#include "avtab.h"
22#include "policydb.h"
23
24static struct kmem_cache *avtab_node_cachep __ro_after_init;
25static struct kmem_cache *avtab_xperms_cachep __ro_after_init;
26
27/* Based on MurmurHash3, written by Austin Appleby and placed in the
28 * public domain.
29 */
30static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
31{
32	static const u32 c1 = 0xcc9e2d51;
33	static const u32 c2 = 0x1b873593;
34	static const u32 r1 = 15;
35	static const u32 r2 = 13;
36	static const u32 m = 5;
37	static const u32 n = 0xe6546b64;
38
39	u32 hash = 0;
40
41#define mix(input)                                         \
42	do {                                               \
43		u32 v = input;                             \
44		v *= c1;                                   \
45		v = (v << r1) | (v >> (32 - r1));          \
46		v *= c2;                                   \
47		hash ^= v;                                 \
48		hash = (hash << r2) | (hash >> (32 - r2)); \
49		hash = hash * m + n;                       \
50	} while (0)
51
52	mix(keyp->target_class);
53	mix(keyp->target_type);
54	mix(keyp->source_type);
55
56#undef mix
57
58	hash ^= hash >> 16;
59	hash *= 0x85ebca6b;
60	hash ^= hash >> 13;
61	hash *= 0xc2b2ae35;
62	hash ^= hash >> 16;
63
64	return hash & mask;
65}
66
67static struct avtab_node *avtab_insert_node(struct avtab *h,
68					    struct avtab_node **dst,
69					    const struct avtab_key *key,
70					    const struct avtab_datum *datum)
71{
72	struct avtab_node *newnode;
73	struct avtab_extended_perms *xperms;
74	newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
75	if (newnode == NULL)
76		return NULL;
77	newnode->key = *key;
78
79	if (key->specified & AVTAB_XPERMS) {
80		xperms = kmem_cache_zalloc(avtab_xperms_cachep, GFP_KERNEL);
81		if (xperms == NULL) {
82			kmem_cache_free(avtab_node_cachep, newnode);
83			return NULL;
84		}
85		*xperms = *(datum->u.xperms);
86		newnode->datum.u.xperms = xperms;
87	} else {
88		newnode->datum.u.data = datum->u.data;
89	}
90
91	newnode->next = *dst;
92	*dst = newnode;
93
94	h->nel++;
95	return newnode;
96}
97
98static int avtab_node_cmp(const struct avtab_key *key1,
99			  const struct avtab_key *key2)
100{
101	u16 specified = key1->specified & ~(AVTAB_ENABLED | AVTAB_ENABLED_OLD);
102
103	if (key1->source_type == key2->source_type &&
104	    key1->target_type == key2->target_type &&
105	    key1->target_class == key2->target_class &&
106	    (specified & key2->specified))
107		return 0;
108	if (key1->source_type < key2->source_type)
109		return -1;
110	if (key1->source_type == key2->source_type &&
111	    key1->target_type < key2->target_type)
112		return -1;
113	if (key1->source_type == key2->source_type &&
114	    key1->target_type == key2->target_type &&
115	    key1->target_class < key2->target_class)
116		return -1;
117	return 1;
118}
119
120static int avtab_insert(struct avtab *h, const struct avtab_key *key,
121			const struct avtab_datum *datum)
122{
123	u32 hvalue;
124	struct avtab_node *prev, *cur, *newnode;
125	int cmp;
126
127	if (!h || !h->nslot || h->nel == U32_MAX)
128		return -EINVAL;
129
130	hvalue = avtab_hash(key, h->mask);
131	for (prev = NULL, cur = h->htable[hvalue]; cur;
132	     prev = cur, cur = cur->next) {
133		cmp = avtab_node_cmp(key, &cur->key);
134		/* extended perms may not be unique */
135		if (cmp == 0 && !(key->specified & AVTAB_XPERMS))
136			return -EEXIST;
137		if (cmp <= 0)
138			break;
139	}
140
141	newnode = avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
142				    key, datum);
143	if (!newnode)
144		return -ENOMEM;
145
146	return 0;
147}
148
149/* Unlike avtab_insert(), this function allow multiple insertions of the same
150 * key/specified mask into the table, as needed by the conditional avtab.
151 * It also returns a pointer to the node inserted.
152 */
153struct avtab_node *avtab_insert_nonunique(struct avtab *h,
154					  const struct avtab_key *key,
155					  const struct avtab_datum *datum)
156{
157	u32 hvalue;
158	struct avtab_node *prev, *cur;
159	int cmp;
160
161	if (!h || !h->nslot || h->nel == U32_MAX)
162		return NULL;
163	hvalue = avtab_hash(key, h->mask);
164	for (prev = NULL, cur = h->htable[hvalue]; cur;
165	     prev = cur, cur = cur->next) {
166		cmp = avtab_node_cmp(key, &cur->key);
167		if (cmp <= 0)
168			break;
169	}
170	return avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
171				 key, datum);
172}
173
174/* This search function returns a node pointer, and can be used in
175 * conjunction with avtab_search_next_node()
176 */
177struct avtab_node *avtab_search_node(struct avtab *h,
178				     const struct avtab_key *key)
179{
180	u32 hvalue;
181	struct avtab_node *cur;
182	int cmp;
183
184	if (!h || !h->nslot)
185		return NULL;
186
187	hvalue = avtab_hash(key, h->mask);
188	for (cur = h->htable[hvalue]; cur; cur = cur->next) {
189		cmp = avtab_node_cmp(key, &cur->key);
190		if (cmp == 0)
191			return cur;
192		if (cmp < 0)
193			break;
194	}
195	return NULL;
196}
197
198struct avtab_node *avtab_search_node_next(struct avtab_node *node,
199					  u16 specified)
200{
201	struct avtab_key tmp_key;
202	struct avtab_node *cur;
203	int cmp;
204
205	if (!node)
206		return NULL;
207	tmp_key = node->key;
208	tmp_key.specified = specified;
209	for (cur = node->next; cur; cur = cur->next) {
210		cmp = avtab_node_cmp(&tmp_key, &cur->key);
211		if (cmp == 0)
212			return cur;
213		if (cmp < 0)
214			break;
215	}
216	return NULL;
217}
218
219void avtab_destroy(struct avtab *h)
220{
221	u32 i;
222	struct avtab_node *cur, *temp;
223
224	if (!h)
225		return;
226
227	for (i = 0; i < h->nslot; i++) {
228		cur = h->htable[i];
229		while (cur) {
230			temp = cur;
231			cur = cur->next;
232			if (temp->key.specified & AVTAB_XPERMS)
233				kmem_cache_free(avtab_xperms_cachep,
234						temp->datum.u.xperms);
235			kmem_cache_free(avtab_node_cachep, temp);
236		}
237	}
238	kvfree(h->htable);
239	h->htable = NULL;
240	h->nel = 0;
241	h->nslot = 0;
242	h->mask = 0;
243}
244
245void avtab_init(struct avtab *h)
246{
247	h->htable = NULL;
248	h->nel = 0;
249	h->nslot = 0;
250	h->mask = 0;
251}
252
253static int avtab_alloc_common(struct avtab *h, u32 nslot)
254{
255	if (!nslot)
256		return 0;
257
258	h->htable = kvcalloc(nslot, sizeof(void *), GFP_KERNEL);
259	if (!h->htable)
260		return -ENOMEM;
261
262	h->nslot = nslot;
263	h->mask = nslot - 1;
264	return 0;
265}
266
267int avtab_alloc(struct avtab *h, u32 nrules)
268{
269	int rc;
270	u32 nslot = 0;
271
272	if (nrules != 0) {
273		nslot = nrules > 3 ? rounddown_pow_of_two(nrules / 2) : 2;
274		if (nslot > MAX_AVTAB_HASH_BUCKETS)
275			nslot = MAX_AVTAB_HASH_BUCKETS;
276
277		rc = avtab_alloc_common(h, nslot);
278		if (rc)
279			return rc;
280	}
281
282	pr_debug("SELinux: %d avtab hash slots, %d rules.\n", nslot, nrules);
283	return 0;
284}
285
286int avtab_alloc_dup(struct avtab *new, const struct avtab *orig)
287{
288	return avtab_alloc_common(new, orig->nslot);
289}
290
291#ifdef CONFIG_SECURITY_SELINUX_DEBUG
292void avtab_hash_eval(struct avtab *h, const char *tag)
293{
294	u32 i, chain_len, slots_used, max_chain_len;
295	unsigned long long chain2_len_sum;
296	struct avtab_node *cur;
297
298	slots_used = 0;
299	max_chain_len = 0;
300	chain2_len_sum = 0;
301	for (i = 0; i < h->nslot; i++) {
302		cur = h->htable[i];
303		if (cur) {
304			slots_used++;
305			chain_len = 0;
306			while (cur) {
307				chain_len++;
308				cur = cur->next;
309			}
310
311			if (chain_len > max_chain_len)
312				max_chain_len = chain_len;
313			chain2_len_sum +=
314				(unsigned long long)chain_len * chain_len;
315		}
316	}
317
318	pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, "
319		 "longest chain length %d, sum of chain length^2 %llu\n",
320		 tag, h->nel, slots_used, h->nslot, max_chain_len,
321		 chain2_len_sum);
322}
323#endif /* CONFIG_SECURITY_SELINUX_DEBUG */
324
325/* clang-format off */
326static const uint16_t spec_order[] = {
327	AVTAB_ALLOWED,
328	AVTAB_AUDITDENY,
329	AVTAB_AUDITALLOW,
330	AVTAB_TRANSITION,
331	AVTAB_CHANGE,
332	AVTAB_MEMBER,
333	AVTAB_XPERMS_ALLOWED,
334	AVTAB_XPERMS_AUDITALLOW,
335	AVTAB_XPERMS_DONTAUDIT
336};
337/* clang-format on */
338
339int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
340		    int (*insertf)(struct avtab *a, const struct avtab_key *k,
341				   const struct avtab_datum *d, void *p),
342		    void *p)
343{
344	__le16 buf16[4];
345	u16 enabled;
346	u32 items, items2, val, i;
347	struct avtab_key key;
348	struct avtab_datum datum;
349	struct avtab_extended_perms xperms;
350	__le32 buf32[ARRAY_SIZE(xperms.perms.p)];
351	int rc;
352	unsigned int set, vers = pol->policyvers;
353
354	memset(&key, 0, sizeof(struct avtab_key));
355	memset(&datum, 0, sizeof(struct avtab_datum));
356
357	if (vers < POLICYDB_VERSION_AVTAB) {
358		rc = next_entry(buf32, fp, sizeof(u32));
359		if (rc) {
360			pr_err("SELinux: avtab: truncated entry\n");
361			return rc;
362		}
363		items2 = le32_to_cpu(buf32[0]);
364		if (items2 > ARRAY_SIZE(buf32)) {
365			pr_err("SELinux: avtab: entry overflow\n");
366			return -EINVAL;
367		}
368		rc = next_entry(buf32, fp, sizeof(u32) * items2);
369		if (rc) {
370			pr_err("SELinux: avtab: truncated entry\n");
371			return rc;
372		}
373		items = 0;
374
375		val = le32_to_cpu(buf32[items++]);
376		key.source_type = (u16)val;
377		if (key.source_type != val) {
378			pr_err("SELinux: avtab: truncated source type\n");
379			return -EINVAL;
380		}
381		val = le32_to_cpu(buf32[items++]);
382		key.target_type = (u16)val;
383		if (key.target_type != val) {
384			pr_err("SELinux: avtab: truncated target type\n");
385			return -EINVAL;
386		}
387		val = le32_to_cpu(buf32[items++]);
388		key.target_class = (u16)val;
389		if (key.target_class != val) {
390			pr_err("SELinux: avtab: truncated target class\n");
391			return -EINVAL;
392		}
393
394		val = le32_to_cpu(buf32[items++]);
395		enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
396
397		if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
398			pr_err("SELinux: avtab: null entry\n");
399			return -EINVAL;
400		}
401		if ((val & AVTAB_AV) && (val & AVTAB_TYPE)) {
402			pr_err("SELinux: avtab: entry has both access vectors and types\n");
403			return -EINVAL;
404		}
405		if (val & AVTAB_XPERMS) {
406			pr_err("SELinux: avtab: entry has extended permissions\n");
407			return -EINVAL;
408		}
409
410		for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
411			if (val & spec_order[i]) {
412				key.specified = spec_order[i] | enabled;
413				datum.u.data = le32_to_cpu(buf32[items++]);
414				rc = insertf(a, &key, &datum, p);
415				if (rc)
416					return rc;
417			}
418		}
419
420		if (items != items2) {
421			pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
422			       items2, items);
423			return -EINVAL;
424		}
425		return 0;
426	}
427
428	rc = next_entry(buf16, fp, sizeof(u16) * 4);
429	if (rc) {
430		pr_err("SELinux: avtab: truncated entry\n");
431		return rc;
432	}
433
434	items = 0;
435	key.source_type = le16_to_cpu(buf16[items++]);
436	key.target_type = le16_to_cpu(buf16[items++]);
437	key.target_class = le16_to_cpu(buf16[items++]);
438	key.specified = le16_to_cpu(buf16[items++]);
439
440	if (!policydb_type_isvalid(pol, key.source_type) ||
441	    !policydb_type_isvalid(pol, key.target_type) ||
442	    !policydb_class_isvalid(pol, key.target_class)) {
443		pr_err("SELinux: avtab: invalid type or class\n");
444		return -EINVAL;
445	}
446
447	set = hweight16(key.specified & (AVTAB_XPERMS | AVTAB_TYPE | AVTAB_AV));
448	if (!set || set > 1) {
449		pr_err("SELinux:  avtab:  more than one specifier\n");
450		return -EINVAL;
451	}
452
453	if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
454	    (key.specified & AVTAB_XPERMS)) {
455		pr_err("SELinux:  avtab:  policy version %u does not "
456		       "support extended permissions rules and one "
457		       "was specified\n",
458		       vers);
459		return -EINVAL;
460	} else if (key.specified & AVTAB_XPERMS) {
461		memset(&xperms, 0, sizeof(struct avtab_extended_perms));
462		rc = next_entry(&xperms.specified, fp, sizeof(u8));
463		if (rc) {
464			pr_err("SELinux: avtab: truncated entry\n");
465			return rc;
466		}
467		rc = next_entry(&xperms.driver, fp, sizeof(u8));
468		if (rc) {
469			pr_err("SELinux: avtab: truncated entry\n");
470			return rc;
471		}
472		rc = next_entry(buf32, fp,
473				sizeof(u32) * ARRAY_SIZE(xperms.perms.p));
474		if (rc) {
475			pr_err("SELinux: avtab: truncated entry\n");
476			return rc;
477		}
478		for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
479			xperms.perms.p[i] = le32_to_cpu(buf32[i]);
480		datum.u.xperms = &xperms;
481	} else {
482		rc = next_entry(buf32, fp, sizeof(u32));
483		if (rc) {
484			pr_err("SELinux: avtab: truncated entry\n");
485			return rc;
486		}
487		datum.u.data = le32_to_cpu(*buf32);
488	}
489	if ((key.specified & AVTAB_TYPE) &&
490	    !policydb_type_isvalid(pol, datum.u.data)) {
491		pr_err("SELinux: avtab: invalid type\n");
492		return -EINVAL;
493	}
494	return insertf(a, &key, &datum, p);
495}
496
497static int avtab_insertf(struct avtab *a, const struct avtab_key *k,
498			 const struct avtab_datum *d, void *p)
499{
500	return avtab_insert(a, k, d);
501}
502
503int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
504{
505	int rc;
506	__le32 buf[1];
507	u32 nel, i;
508
509	rc = next_entry(buf, fp, sizeof(u32));
510	if (rc < 0) {
511		pr_err("SELinux: avtab: truncated table\n");
512		goto bad;
513	}
514	nel = le32_to_cpu(buf[0]);
515	if (!nel) {
516		pr_err("SELinux: avtab: table is empty\n");
517		rc = -EINVAL;
518		goto bad;
519	}
520
521	rc = avtab_alloc(a, nel);
522	if (rc)
523		goto bad;
524
525	for (i = 0; i < nel; i++) {
526		rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
527		if (rc) {
528			if (rc == -ENOMEM)
529				pr_err("SELinux: avtab: out of memory\n");
530			else if (rc == -EEXIST)
531				pr_err("SELinux: avtab: duplicate entry\n");
532
533			goto bad;
534		}
535	}
536
537	rc = 0;
538out:
539	return rc;
540
541bad:
542	avtab_destroy(a);
543	goto out;
544}
545
546int avtab_write_item(struct policydb *p, const struct avtab_node *cur, void *fp)
547{
548	__le16 buf16[4];
549	__le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
550	int rc;
551	unsigned int i;
552
553	buf16[0] = cpu_to_le16(cur->key.source_type);
554	buf16[1] = cpu_to_le16(cur->key.target_type);
555	buf16[2] = cpu_to_le16(cur->key.target_class);
556	buf16[3] = cpu_to_le16(cur->key.specified);
557	rc = put_entry(buf16, sizeof(u16), 4, fp);
558	if (rc)
559		return rc;
560
561	if (cur->key.specified & AVTAB_XPERMS) {
562		rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1,
563			       fp);
564		if (rc)
565			return rc;
566		rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
567		if (rc)
568			return rc;
569		for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
570			buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
571		rc = put_entry(buf32, sizeof(u32),
572			       ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
573	} else {
574		buf32[0] = cpu_to_le32(cur->datum.u.data);
575		rc = put_entry(buf32, sizeof(u32), 1, fp);
576	}
577	if (rc)
578		return rc;
579	return 0;
580}
581
582int avtab_write(struct policydb *p, struct avtab *a, void *fp)
583{
584	u32 i;
585	int rc = 0;
586	struct avtab_node *cur;
587	__le32 buf[1];
588
589	buf[0] = cpu_to_le32(a->nel);
590	rc = put_entry(buf, sizeof(u32), 1, fp);
591	if (rc)
592		return rc;
593
594	for (i = 0; i < a->nslot; i++) {
595		for (cur = a->htable[i]; cur; cur = cur->next) {
596			rc = avtab_write_item(p, cur, fp);
597			if (rc)
598				return rc;
599		}
600	}
601
602	return rc;
603}
604
605void __init avtab_cache_init(void)
606{
607	avtab_node_cachep = kmem_cache_create(
608		"avtab_node", sizeof(struct avtab_node), 0, SLAB_PANIC, NULL);
609	avtab_xperms_cachep = kmem_cache_create(
610		"avtab_extended_perms", sizeof(struct avtab_extended_perms), 0,
611		SLAB_PANIC, NULL);
612}
613