1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Implementation of the extensible bitmap type.
4  *
5  * Author : Stephen Smalley, <sds@tycho.nsa.gov>
6  */
7 /*
8  * Updated: Hewlett-Packard <paul@paul-moore.com>
9  *
10  *      Added support to import/export the NetLabel category bitmap
11  *
12  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
13  */
14 /*
15  * Updated: KaiGai Kohei <kaigai@ak.jp.nec.com>
16  *      Applied standard bit operations to improve bitmap scanning.
17  */
18 
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
21 #include <linux/errno.h>
22 #include <linux/jhash.h>
23 #include <net/netlabel.h>
24 #include "ebitmap.h"
25 #include "policydb.h"
26 
27 #define BITS_PER_U64	(sizeof(u64) * 8)
28 
29 static struct kmem_cache *ebitmap_node_cachep __ro_after_init;
30 
ebitmap_cmp(const struct ebitmap * e1,const struct ebitmap * e2)31 int ebitmap_cmp(const struct ebitmap *e1, const struct ebitmap *e2)
32 {
33 	const struct ebitmap_node *n1, *n2;
34 
35 	if (e1->highbit != e2->highbit)
36 		return 0;
37 
38 	n1 = e1->node;
39 	n2 = e2->node;
40 	while (n1 && n2 &&
41 	       (n1->startbit == n2->startbit) &&
42 	       !memcmp(n1->maps, n2->maps, EBITMAP_SIZE / 8)) {
43 		n1 = n1->next;
44 		n2 = n2->next;
45 	}
46 
47 	if (n1 || n2)
48 		return 0;
49 
50 	return 1;
51 }
52 
ebitmap_cpy(struct ebitmap * dst,const struct ebitmap * src)53 int ebitmap_cpy(struct ebitmap *dst, const struct ebitmap *src)
54 {
55 	struct ebitmap_node *new, *prev;
56 	const struct ebitmap_node *n;
57 
58 	ebitmap_init(dst);
59 	n = src->node;
60 	prev = NULL;
61 	while (n) {
62 		new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
63 		if (!new) {
64 			ebitmap_destroy(dst);
65 			return -ENOMEM;
66 		}
67 		new->startbit = n->startbit;
68 		memcpy(new->maps, n->maps, EBITMAP_SIZE / 8);
69 		new->next = NULL;
70 		if (prev)
71 			prev->next = new;
72 		else
73 			dst->node = new;
74 		prev = new;
75 		n = n->next;
76 	}
77 
78 	dst->highbit = src->highbit;
79 	return 0;
80 }
81 
ebitmap_and(struct ebitmap * dst,const struct ebitmap * e1,const struct ebitmap * e2)82 int ebitmap_and(struct ebitmap *dst, const struct ebitmap *e1, const struct ebitmap *e2)
83 {
84 	struct ebitmap_node *n;
85 	int bit, rc;
86 
87 	ebitmap_init(dst);
88 
89 	ebitmap_for_each_positive_bit(e1, n, bit) {
90 		if (ebitmap_get_bit(e2, bit)) {
91 			rc = ebitmap_set_bit(dst, bit, 1);
92 			if (rc < 0)
93 				return rc;
94 		}
95 	}
96 	return 0;
97 }
98 
99 
100 #ifdef CONFIG_NETLABEL
101 /**
102  * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap
103  * @ebmap: the ebitmap to export
104  * @catmap: the NetLabel category bitmap
105  *
106  * Description:
107  * Export a SELinux extensibile bitmap into a NetLabel category bitmap.
108  * Returns zero on success, negative values on error.
109  *
110  */
ebitmap_netlbl_export(struct ebitmap * ebmap,struct netlbl_lsm_catmap ** catmap)111 int ebitmap_netlbl_export(struct ebitmap *ebmap,
112 			  struct netlbl_lsm_catmap **catmap)
113 {
114 	struct ebitmap_node *e_iter = ebmap->node;
115 	unsigned long e_map;
116 	u32 offset;
117 	unsigned int iter;
118 	int rc;
119 
120 	if (e_iter == NULL) {
121 		*catmap = NULL;
122 		return 0;
123 	}
124 
125 	if (*catmap != NULL)
126 		netlbl_catmap_free(*catmap);
127 	*catmap = NULL;
128 
129 	while (e_iter) {
130 		offset = e_iter->startbit;
131 		for (iter = 0; iter < EBITMAP_UNIT_NUMS; iter++) {
132 			e_map = e_iter->maps[iter];
133 			if (e_map != 0) {
134 				rc = netlbl_catmap_setlong(catmap,
135 							   offset,
136 							   e_map,
137 							   GFP_ATOMIC);
138 				if (rc != 0)
139 					goto netlbl_export_failure;
140 			}
141 			offset += EBITMAP_UNIT_SIZE;
142 		}
143 		e_iter = e_iter->next;
144 	}
145 
146 	return 0;
147 
148 netlbl_export_failure:
149 	netlbl_catmap_free(*catmap);
150 	return -ENOMEM;
151 }
152 
153 /**
154  * ebitmap_netlbl_import - Import a NetLabel category bitmap into an ebitmap
155  * @ebmap: the ebitmap to import
156  * @catmap: the NetLabel category bitmap
157  *
158  * Description:
159  * Import a NetLabel category bitmap into a SELinux extensibile bitmap.
160  * Returns zero on success, negative values on error.
161  *
162  */
ebitmap_netlbl_import(struct ebitmap * ebmap,struct netlbl_lsm_catmap * catmap)163 int ebitmap_netlbl_import(struct ebitmap *ebmap,
164 			  struct netlbl_lsm_catmap *catmap)
165 {
166 	int rc;
167 	struct ebitmap_node *e_iter = NULL;
168 	struct ebitmap_node *e_prev = NULL;
169 	u32 offset = 0, idx;
170 	unsigned long bitmap;
171 
172 	for (;;) {
173 		rc = netlbl_catmap_getlong(catmap, &offset, &bitmap);
174 		if (rc < 0)
175 			goto netlbl_import_failure;
176 		if (offset == (u32)-1)
177 			return 0;
178 
179 		/* don't waste ebitmap space if the netlabel bitmap is empty */
180 		if (bitmap == 0) {
181 			offset += EBITMAP_UNIT_SIZE;
182 			continue;
183 		}
184 
185 		if (e_iter == NULL ||
186 		    offset >= e_iter->startbit + EBITMAP_SIZE) {
187 			e_prev = e_iter;
188 			e_iter = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
189 			if (e_iter == NULL)
190 				goto netlbl_import_failure;
191 			e_iter->startbit = offset - (offset % EBITMAP_SIZE);
192 			if (e_prev == NULL)
193 				ebmap->node = e_iter;
194 			else
195 				e_prev->next = e_iter;
196 			ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
197 		}
198 
199 		/* offset will always be aligned to an unsigned long */
200 		idx = EBITMAP_NODE_INDEX(e_iter, offset);
201 		e_iter->maps[idx] = bitmap;
202 
203 		/* next */
204 		offset += EBITMAP_UNIT_SIZE;
205 	}
206 
207 	/* NOTE: we should never reach this return */
208 	return 0;
209 
210 netlbl_import_failure:
211 	ebitmap_destroy(ebmap);
212 	return -ENOMEM;
213 }
214 #endif /* CONFIG_NETLABEL */
215 
216 /*
217  * Check to see if all the bits set in e2 are also set in e1. Optionally,
218  * if last_e2bit is non-zero, the highest set bit in e2 cannot exceed
219  * last_e2bit.
220  */
ebitmap_contains(const struct ebitmap * e1,const struct ebitmap * e2,u32 last_e2bit)221 int ebitmap_contains(const struct ebitmap *e1, const struct ebitmap *e2, u32 last_e2bit)
222 {
223 	const struct ebitmap_node *n1, *n2;
224 	int i;
225 
226 	if (e1->highbit < e2->highbit)
227 		return 0;
228 
229 	n1 = e1->node;
230 	n2 = e2->node;
231 
232 	while (n1 && n2 && (n1->startbit <= n2->startbit)) {
233 		if (n1->startbit < n2->startbit) {
234 			n1 = n1->next;
235 			continue;
236 		}
237 		for (i = EBITMAP_UNIT_NUMS - 1; (i >= 0) && !n2->maps[i]; )
238 			i--;	/* Skip trailing NULL map entries */
239 		if (last_e2bit && (i >= 0)) {
240 			u32 lastsetbit = n2->startbit + i * EBITMAP_UNIT_SIZE +
241 					 __fls(n2->maps[i]);
242 			if (lastsetbit > last_e2bit)
243 				return 0;
244 		}
245 
246 		while (i >= 0) {
247 			if ((n1->maps[i] & n2->maps[i]) != n2->maps[i])
248 				return 0;
249 			i--;
250 		}
251 
252 		n1 = n1->next;
253 		n2 = n2->next;
254 	}
255 
256 	if (n2)
257 		return 0;
258 
259 	return 1;
260 }
261 
ebitmap_get_bit(const struct ebitmap * e,unsigned long bit)262 int ebitmap_get_bit(const struct ebitmap *e, unsigned long bit)
263 {
264 	const struct ebitmap_node *n;
265 
266 	if (e->highbit < bit)
267 		return 0;
268 
269 	n = e->node;
270 	while (n && (n->startbit <= bit)) {
271 		if ((n->startbit + EBITMAP_SIZE) > bit)
272 			return ebitmap_node_get_bit(n, bit);
273 		n = n->next;
274 	}
275 
276 	return 0;
277 }
278 
ebitmap_set_bit(struct ebitmap * e,unsigned long bit,int value)279 int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
280 {
281 	struct ebitmap_node *n, *prev, *new;
282 
283 	prev = NULL;
284 	n = e->node;
285 	while (n && n->startbit <= bit) {
286 		if ((n->startbit + EBITMAP_SIZE) > bit) {
287 			if (value) {
288 				ebitmap_node_set_bit(n, bit);
289 			} else {
290 				unsigned int s;
291 
292 				ebitmap_node_clr_bit(n, bit);
293 
294 				s = find_first_bit(n->maps, EBITMAP_SIZE);
295 				if (s < EBITMAP_SIZE)
296 					return 0;
297 
298 				/* drop this node from the bitmap */
299 				if (!n->next) {
300 					/*
301 					 * this was the highest map
302 					 * within the bitmap
303 					 */
304 					if (prev)
305 						e->highbit = prev->startbit
306 							     + EBITMAP_SIZE;
307 					else
308 						e->highbit = 0;
309 				}
310 				if (prev)
311 					prev->next = n->next;
312 				else
313 					e->node = n->next;
314 				kmem_cache_free(ebitmap_node_cachep, n);
315 			}
316 			return 0;
317 		}
318 		prev = n;
319 		n = n->next;
320 	}
321 
322 	if (!value)
323 		return 0;
324 
325 	new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
326 	if (!new)
327 		return -ENOMEM;
328 
329 	new->startbit = bit - (bit % EBITMAP_SIZE);
330 	ebitmap_node_set_bit(new, bit);
331 
332 	if (!n)
333 		/* this node will be the highest map within the bitmap */
334 		e->highbit = new->startbit + EBITMAP_SIZE;
335 
336 	if (prev) {
337 		new->next = prev->next;
338 		prev->next = new;
339 	} else {
340 		new->next = e->node;
341 		e->node = new;
342 	}
343 
344 	return 0;
345 }
346 
ebitmap_destroy(struct ebitmap * e)347 void ebitmap_destroy(struct ebitmap *e)
348 {
349 	struct ebitmap_node *n, *temp;
350 
351 	if (!e)
352 		return;
353 
354 	n = e->node;
355 	while (n) {
356 		temp = n;
357 		n = n->next;
358 		kmem_cache_free(ebitmap_node_cachep, temp);
359 	}
360 
361 	e->highbit = 0;
362 	e->node = NULL;
363 }
364 
ebitmap_read(struct ebitmap * e,void * fp)365 int ebitmap_read(struct ebitmap *e, void *fp)
366 {
367 	struct ebitmap_node *n = NULL;
368 	u32 mapunit, count, startbit, index;
369 	__le32 ebitmap_start;
370 	u64 map;
371 	__le64 mapbits;
372 	__le32 buf[3];
373 	int rc, i;
374 
375 	ebitmap_init(e);
376 
377 	rc = next_entry(buf, fp, sizeof buf);
378 	if (rc < 0)
379 		goto out;
380 
381 	mapunit = le32_to_cpu(buf[0]);
382 	e->highbit = le32_to_cpu(buf[1]);
383 	count = le32_to_cpu(buf[2]);
384 
385 	if (mapunit != BITS_PER_U64) {
386 		pr_err("SELinux: ebitmap: map size %u does not "
387 		       "match my size %zd (high bit was %d)\n",
388 		       mapunit, BITS_PER_U64, e->highbit);
389 		goto bad;
390 	}
391 
392 	/* round up e->highbit */
393 	e->highbit += EBITMAP_SIZE - 1;
394 	e->highbit -= (e->highbit % EBITMAP_SIZE);
395 
396 	if (!e->highbit) {
397 		e->node = NULL;
398 		goto ok;
399 	}
400 
401 	if (e->highbit && !count)
402 		goto bad;
403 
404 	for (i = 0; i < count; i++) {
405 		rc = next_entry(&ebitmap_start, fp, sizeof(u32));
406 		if (rc < 0) {
407 			pr_err("SELinux: ebitmap: truncated map\n");
408 			goto bad;
409 		}
410 		startbit = le32_to_cpu(ebitmap_start);
411 
412 		if (startbit & (mapunit - 1)) {
413 			pr_err("SELinux: ebitmap start bit (%d) is "
414 			       "not a multiple of the map unit size (%u)\n",
415 			       startbit, mapunit);
416 			goto bad;
417 		}
418 		if (startbit > e->highbit - mapunit) {
419 			pr_err("SELinux: ebitmap start bit (%d) is "
420 			       "beyond the end of the bitmap (%u)\n",
421 			       startbit, (e->highbit - mapunit));
422 			goto bad;
423 		}
424 
425 		if (!n || startbit >= n->startbit + EBITMAP_SIZE) {
426 			struct ebitmap_node *tmp;
427 			tmp = kmem_cache_zalloc(ebitmap_node_cachep, GFP_KERNEL);
428 			if (!tmp) {
429 				pr_err("SELinux: ebitmap: out of memory\n");
430 				rc = -ENOMEM;
431 				goto bad;
432 			}
433 			/* round down */
434 			tmp->startbit = startbit - (startbit % EBITMAP_SIZE);
435 			if (n)
436 				n->next = tmp;
437 			else
438 				e->node = tmp;
439 			n = tmp;
440 		} else if (startbit <= n->startbit) {
441 			pr_err("SELinux: ebitmap: start bit %d"
442 			       " comes after start bit %d\n",
443 			       startbit, n->startbit);
444 			goto bad;
445 		}
446 
447 		rc = next_entry(&mapbits, fp, sizeof(u64));
448 		if (rc < 0) {
449 			pr_err("SELinux: ebitmap: truncated map\n");
450 			goto bad;
451 		}
452 		map = le64_to_cpu(mapbits);
453 
454 		index = (startbit - n->startbit) / EBITMAP_UNIT_SIZE;
455 		while (map) {
456 			n->maps[index++] = map & (-1UL);
457 			map = EBITMAP_SHIFT_UNIT_SIZE(map);
458 		}
459 	}
460 ok:
461 	rc = 0;
462 out:
463 	return rc;
464 bad:
465 	if (!rc)
466 		rc = -EINVAL;
467 	ebitmap_destroy(e);
468 	goto out;
469 }
470 
ebitmap_write(const struct ebitmap * e,void * fp)471 int ebitmap_write(const struct ebitmap *e, void *fp)
472 {
473 	struct ebitmap_node *n;
474 	u32 count;
475 	__le32 buf[3];
476 	u64 map;
477 	int bit, last_bit, last_startbit, rc;
478 
479 	buf[0] = cpu_to_le32(BITS_PER_U64);
480 
481 	count = 0;
482 	last_bit = 0;
483 	last_startbit = -1;
484 	ebitmap_for_each_positive_bit(e, n, bit) {
485 		if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
486 			count++;
487 			last_startbit = rounddown(bit, BITS_PER_U64);
488 		}
489 		last_bit = roundup(bit + 1, BITS_PER_U64);
490 	}
491 	buf[1] = cpu_to_le32(last_bit);
492 	buf[2] = cpu_to_le32(count);
493 
494 	rc = put_entry(buf, sizeof(u32), 3, fp);
495 	if (rc)
496 		return rc;
497 
498 	map = 0;
499 	last_startbit = INT_MIN;
500 	ebitmap_for_each_positive_bit(e, n, bit) {
501 		if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
502 			__le64 buf64[1];
503 
504 			/* this is the very first bit */
505 			if (!map) {
506 				last_startbit = rounddown(bit, BITS_PER_U64);
507 				map = (u64)1 << (bit - last_startbit);
508 				continue;
509 			}
510 
511 			/* write the last node */
512 			buf[0] = cpu_to_le32(last_startbit);
513 			rc = put_entry(buf, sizeof(u32), 1, fp);
514 			if (rc)
515 				return rc;
516 
517 			buf64[0] = cpu_to_le64(map);
518 			rc = put_entry(buf64, sizeof(u64), 1, fp);
519 			if (rc)
520 				return rc;
521 
522 			/* set up for the next node */
523 			map = 0;
524 			last_startbit = rounddown(bit, BITS_PER_U64);
525 		}
526 		map |= (u64)1 << (bit - last_startbit);
527 	}
528 	/* write the last node */
529 	if (map) {
530 		__le64 buf64[1];
531 
532 		/* write the last node */
533 		buf[0] = cpu_to_le32(last_startbit);
534 		rc = put_entry(buf, sizeof(u32), 1, fp);
535 		if (rc)
536 			return rc;
537 
538 		buf64[0] = cpu_to_le64(map);
539 		rc = put_entry(buf64, sizeof(u64), 1, fp);
540 		if (rc)
541 			return rc;
542 	}
543 	return 0;
544 }
545 
ebitmap_hash(const struct ebitmap * e,u32 hash)546 u32 ebitmap_hash(const struct ebitmap *e, u32 hash)
547 {
548 	struct ebitmap_node *node;
549 
550 	/* need to change hash even if ebitmap is empty */
551 	hash = jhash_1word(e->highbit, hash);
552 	for (node = e->node; node; node = node->next) {
553 		hash = jhash_1word(node->startbit, hash);
554 		hash = jhash(node->maps, sizeof(node->maps), hash);
555 	}
556 	return hash;
557 }
558 
ebitmap_cache_init(void)559 void __init ebitmap_cache_init(void)
560 {
561 	ebitmap_node_cachep = kmem_cache_create("ebitmap_node",
562 							sizeof(struct ebitmap_node),
563 							0, SLAB_PANIC, NULL);
564 }
565