security/selinux/ss/ebitmap.c - arm/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Implementation of the extensible bitmap type.
  *
  * Author : Stephen Smalley, <sds@tycho.nsa.gov>
  */
 /*
  * Updated: Hewlett-Packard <paul@paul-moore.com>
  *
  *      Added support to import/export the NetLabel category bitmap
  *
  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
  */
 /*
  * Updated: KaiGai Kohei <kaigai@ak.jp.nec.com>
  *      Applied standard bit operations to improve bitmap scanning.
  */

 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <net/netlabel.h>
 #include "ebitmap.h"
 #include "policydb.h"

 #define BITS_PER_U64	(sizeof(u64) * 8)

 static struct kmem_cache *ebitmap_node_cachep;

 int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2)
 {
 	struct ebitmap_node *n1, *n2;

 	if (e1->highbit != e2->highbit)
 		return 0;

 	n1 = e1->node;
 	n2 = e2->node;
 	while (n1 && n2 &&
 	       (n1->startbit == n2->startbit) &&
 	       !memcmp(n1->maps, n2->maps, EBITMAP_SIZE / 8)) {
 		n1 = n1->next;
 		n2 = n2->next;
 	}

 	if (n1 || n2)
 		return 0;

 	return 1;
 }

 int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
 {
 	struct ebitmap_node *n, *new, *prev;

 	ebitmap_init(dst);
 	n = src->node;
 	prev = NULL;
 	while (n) {
 		new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 		if (!new) {
 			ebitmap_destroy(dst);
 			return -ENOMEM;
 		}
 		new->startbit = n->startbit;
 		memcpy(new->maps, n->maps, EBITMAP_SIZE / 8);
 		new->next = NULL;
 		if (prev)
 			prev->next = new;
 		else
 			dst->node = new;
 		prev = new;
 		n = n->next;
 	}

 	dst->highbit = src->highbit;
 	return 0;
 }

 #ifdef CONFIG_NETLABEL
 /**
  * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap
  * @ebmap: the ebitmap to export
  * @catmap: the NetLabel category bitmap
  *
  * Description:
  * Export a SELinux extensibile bitmap into a NetLabel category bitmap.
  * Returns zero on success, negative values on error.
  *
  */
 int ebitmap_netlbl_export(struct ebitmap *ebmap,
 			  struct netlbl_lsm_catmap **catmap)
 {
 	struct ebitmap_node *e_iter = ebmap->node;
 	unsigned long e_map;
 	u32 offset;
 	unsigned int iter;
 	int rc;

 	if (e_iter == NULL) {
 		*catmap = NULL;
 		return 0;
 	}

 	if (*catmap != NULL)
 		netlbl_catmap_free(*catmap);
 	*catmap = NULL;

 	while (e_iter) {
 		offset = e_iter->startbit;
 		for (iter = 0; iter < EBITMAP_UNIT_NUMS; iter++) {
 			e_map = e_iter->maps[iter];
 			if (e_map != 0) {
 				rc = netlbl_catmap_setlong(catmap,
 							   offset,
 							   e_map,
 							   GFP_ATOMIC);
 				if (rc != 0)
 					goto netlbl_export_failure;
 			}
 			offset += EBITMAP_UNIT_SIZE;
 		}
 		e_iter = e_iter->next;
 	}

 	return 0;

 netlbl_export_failure:
 	netlbl_catmap_free(*catmap);
 	return -ENOMEM;
 }

 /**
  * ebitmap_netlbl_import - Import a NetLabel category bitmap into an ebitmap
  * @ebmap: the ebitmap to import
  * @catmap: the NetLabel category bitmap
  *
  * Description:
  * Import a NetLabel category bitmap into a SELinux extensibile bitmap.
  * Returns zero on success, negative values on error.
  *
  */
 int ebitmap_netlbl_import(struct ebitmap *ebmap,
 			  struct netlbl_lsm_catmap *catmap)
 {
 	int rc;
 	struct ebitmap_node *e_iter = NULL;
 	struct ebitmap_node *e_prev = NULL;
 	u32 offset = 0, idx;
 	unsigned long bitmap;

 	for (;;) {
 		rc = netlbl_catmap_getlong(catmap, &offset, &bitmap);
 		if (rc < 0)
 			goto netlbl_import_failure;
 		if (offset == (u32)-1)
 			return 0;

 		/* don't waste ebitmap space if the netlabel bitmap is empty */
 		if (bitmap == 0) {
 			offset += EBITMAP_UNIT_SIZE;
 			continue;
 		}

 		if (e_iter == NULL ||
 		    offset >= e_iter->startbit + EBITMAP_SIZE) {
 			e_prev = e_iter;
 			e_iter = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 			if (e_iter == NULL)
 				goto netlbl_import_failure;
 			e_iter->startbit = offset - (offset % EBITMAP_SIZE);
 			if (e_prev == NULL)
 				ebmap->node = e_iter;
 			else
 				e_prev->next = e_iter;
 			ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
 		}

 		/* offset will always be aligned to an unsigned long */
 		idx = EBITMAP_NODE_INDEX(e_iter, offset);
 		e_iter->maps[idx] = bitmap;

 		/* next */
 		offset += EBITMAP_UNIT_SIZE;
 	}

 	/* NOTE: we should never reach this return */
 	return 0;

 netlbl_import_failure:
 	ebitmap_destroy(ebmap);
 	return -ENOMEM;
 }
 #endif /* CONFIG_NETLABEL */

 /*
  * Check to see if all the bits set in e2 are also set in e1. Optionally,
  * if last_e2bit is non-zero, the highest set bit in e2 cannot exceed
  * last_e2bit.
  */
 int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit)
 {
 	struct ebitmap_node *n1, *n2;
 	int i;

 	if (e1->highbit < e2->highbit)
 		return 0;

 	n1 = e1->node;
 	n2 = e2->node;

 	while (n1 && n2 && (n1->startbit <= n2->startbit)) {
 		if (n1->startbit < n2->startbit) {
 			n1 = n1->next;
 			continue;
 		}
 		for (i = EBITMAP_UNIT_NUMS - 1; (i >= 0) && !n2->maps[i]; )
 			i--;	/* Skip trailing NULL map entries */
 		if (last_e2bit && (i >= 0)) {
 			u32 lastsetbit = n2->startbit + i * EBITMAP_UNIT_SIZE +
 					 __fls(n2->maps[i]);
 			if (lastsetbit > last_e2bit)
 				return 0;
 		}

 		while (i >= 0) {
 			if ((n1->maps[i] & n2->maps[i]) != n2->maps[i])
 				return 0;
 			i--;
 		}

 		n1 = n1->next;
 		n2 = n2->next;
 	}

 	if (n2)
 		return 0;

 	return 1;
 }

 int ebitmap_get_bit(struct ebitmap *e, unsigned long bit)
 {
 	struct ebitmap_node *n;

 	if (e->highbit < bit)
 		return 0;

 	n = e->node;
 	while (n && (n->startbit <= bit)) {
 		if ((n->startbit + EBITMAP_SIZE) > bit)
 			return ebitmap_node_get_bit(n, bit);
 		n = n->next;
 	}

 	return 0;
 }

 int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
 {
 	struct ebitmap_node *n, *prev, *new;

 	prev = NULL;
 	n = e->node;
 	while (n && n->startbit <= bit) {
 		if ((n->startbit + EBITMAP_SIZE) > bit) {
 			if (value) {
 				ebitmap_node_set_bit(n, bit);
 			} else {
 				unsigned int s;

 				ebitmap_node_clr_bit(n, bit);

 				s = find_first_bit(n->maps, EBITMAP_SIZE);
 				if (s < EBITMAP_SIZE)
 					return 0;

 				/* drop this node from the bitmap */
 				if (!n->next) {
 					/*
 					 * this was the highest map
 					 * within the bitmap
 					 */
 					if (prev)
 						e->highbit = prev->startbit
 							     + EBITMAP_SIZE;
 					else
 						e->highbit = 0;
 				}
 				if (prev)
 					prev->next = n->next;
 				else
 					e->node = n->next;
 				kmem_cache_free(ebitmap_node_cachep, n);
 			}
 			return 0;
 		}
 		prev = n;
 		n = n->next;
 	}

 	if (!value)
 		return 0;

 	new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
 	if (!new)
 		return -ENOMEM;

 	new->startbit = bit - (bit % EBITMAP_SIZE);
 	ebitmap_node_set_bit(new, bit);

 	if (!n)
 		/* this node will be the highest map within the bitmap */
 		e->highbit = new->startbit + EBITMAP_SIZE;

 	if (prev) {
 		new->next = prev->next;
 		prev->next = new;
 	} else {
 		new->next = e->node;
 		e->node = new;
 	}

 	return 0;
 }

 void ebitmap_destroy(struct ebitmap *e)
 {
 	struct ebitmap_node *n, *temp;

 	if (!e)
 		return;

 	n = e->node;
 	while (n) {
 		temp = n;
 		n = n->next;
 		kmem_cache_free(ebitmap_node_cachep, temp);
 	}

 	e->highbit = 0;
 	e->node = NULL;
 	return;
 }

 int ebitmap_read(struct ebitmap *e, void *fp)
 {
 	struct ebitmap_node *n = NULL;
 	u32 mapunit, count, startbit, index;
 	u64 map;
 	__le32 buf[3];
 	int rc, i;

 	ebitmap_init(e);

 	rc = next_entry(buf, fp, sizeof buf);
 	if (rc < 0)
 		goto out;

 	mapunit = le32_to_cpu(buf[0]);
 	e->highbit = le32_to_cpu(buf[1]);
 	count = le32_to_cpu(buf[2]);

 	if (mapunit != BITS_PER_U64) {
 		printk(KERN_ERR "SELinux: ebitmap: map size %u does not "
 		       "match my size %zd (high bit was %d)\n",
 		       mapunit, BITS_PER_U64, e->highbit);
 		goto bad;
 	}

 	/* round up e->highbit */
 	e->highbit += EBITMAP_SIZE - 1;
 	e->highbit -= (e->highbit % EBITMAP_SIZE);

 	if (!e->highbit) {
 		e->node = NULL;
 		goto ok;
 	}

 	if (e->highbit && !count)
 		goto bad;

 	for (i = 0; i < count; i++) {
 		rc = next_entry(&startbit, fp, sizeof(u32));
 		if (rc < 0) {
 			printk(KERN_ERR "SELinux: ebitmap: truncated map\n");
 			goto bad;
 		}
 		startbit = le32_to_cpu(startbit);

 		if (startbit & (mapunit - 1)) {
 			printk(KERN_ERR "SELinux: ebitmap start bit (%d) is "
 			       "not a multiple of the map unit size (%u)\n",
 			       startbit, mapunit);
 			goto bad;
 		}
 		if (startbit > e->highbit - mapunit) {
 			printk(KERN_ERR "SELinux: ebitmap start bit (%d) is "
 			       "beyond the end of the bitmap (%u)\n",
 			       startbit, (e->highbit - mapunit));
 			goto bad;
 		}

 		if (!n || startbit >= n->startbit + EBITMAP_SIZE) {
 			struct ebitmap_node *tmp;
 			tmp = kmem_cache_zalloc(ebitmap_node_cachep, GFP_KERNEL);
 			if (!tmp) {
 				printk(KERN_ERR
 				       "SELinux: ebitmap: out of memory\n");
 				rc = -ENOMEM;
 				goto bad;
 			}
 			/* round down */
 			tmp->startbit = startbit - (startbit % EBITMAP_SIZE);
 			if (n)
 				n->next = tmp;
 			else
 				e->node = tmp;
 			n = tmp;
 		} else if (startbit <= n->startbit) {
 			printk(KERN_ERR "SELinux: ebitmap: start bit %d"
 			       " comes after start bit %d\n",
 			       startbit, n->startbit);
 			goto bad;
 		}

 		rc = next_entry(&map, fp, sizeof(u64));
 		if (rc < 0) {
 			printk(KERN_ERR "SELinux: ebitmap: truncated map\n");
 			goto bad;
 		}
 		map = le64_to_cpu(map);

 		index = (startbit - n->startbit) / EBITMAP_UNIT_SIZE;
 		while (map) {
 			n->maps[index++] = map & (-1UL);
 			map = EBITMAP_SHIFT_UNIT_SIZE(map);
 		}
 	}
 ok:
 	rc = 0;
 out:
 	return rc;
 bad:
 	if (!rc)
 		rc = -EINVAL;
 	ebitmap_destroy(e);
 	goto out;
 }

 int ebitmap_write(struct ebitmap *e, void *fp)
 {
 	struct ebitmap_node *n;
 	u32 count;
 	__le32 buf[3];
 	u64 map;
 	int bit, last_bit, last_startbit, rc;

 	buf[0] = cpu_to_le32(BITS_PER_U64);

 	count = 0;
 	last_bit = 0;
 	last_startbit = -1;
 	ebitmap_for_each_positive_bit(e, n, bit) {
 		if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
 			count++;
 			last_startbit = rounddown(bit, BITS_PER_U64);
 		}
 		last_bit = roundup(bit + 1, BITS_PER_U64);
 	}
 	buf[1] = cpu_to_le32(last_bit);
 	buf[2] = cpu_to_le32(count);

 	rc = put_entry(buf, sizeof(u32), 3, fp);
 	if (rc)
 		return rc;

 	map = 0;
 	last_startbit = INT_MIN;
 	ebitmap_for_each_positive_bit(e, n, bit) {
 		if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
 			__le64 buf64[1];

 			/* this is the very first bit */
 			if (!map) {
 				last_startbit = rounddown(bit, BITS_PER_U64);
 				map = (u64)1 << (bit - last_startbit);
 				continue;
 			}

 			/* write the last node */
 			buf[0] = cpu_to_le32(last_startbit);
 			rc = put_entry(buf, sizeof(u32), 1, fp);
 			if (rc)
 				return rc;

 			buf64[0] = cpu_to_le64(map);
 			rc = put_entry(buf64, sizeof(u64), 1, fp);
 			if (rc)
 				return rc;

 			/* set up for the next node */
 			map = 0;
 			last_startbit = rounddown(bit, BITS_PER_U64);
 		}
 		map |= (u64)1 << (bit - last_startbit);
 	}
 	/* write the last node */
 	if (map) {
 		__le64 buf64[1];

 		/* write the last node */
 		buf[0] = cpu_to_le32(last_startbit);
 		rc = put_entry(buf, sizeof(u32), 1, fp);
 		if (rc)
 			return rc;

 		buf64[0] = cpu_to_le64(map);
 		rc = put_entry(buf64, sizeof(u64), 1, fp);
 		if (rc)
 			return rc;
 	}
 	return 0;
 }

 void ebitmap_cache_init(void)
 {
 	ebitmap_node_cachep = kmem_cache_create("ebitmap_node",
 							sizeof(struct ebitmap_node),
 							0, SLAB_PANIC, NULL);
 }

 void ebitmap_cache_destroy(void)
 {
 	kmem_cache_destroy(ebitmap_node_cachep);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Implementation of the extensible bitmap type.
	*
	* Author : Stephen Smalley, <sds@tycho.nsa.gov>
	*/
	/*
	* Updated: Hewlett-Packard <paul@paul-moore.com>
	*
	* Added support to import/export the NetLabel category bitmap
	*
	* (c) Copyright Hewlett-Packard Development Company, L.P., 2006
	*/
	/*
	* Updated: KaiGai Kohei <kaigai@ak.jp.nec.com>
	* Applied standard bit operations to improve bitmap scanning.
	*/

	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/errno.h>
	#include <net/netlabel.h>
	#include "ebitmap.h"
	#include "policydb.h"

	#define BITS_PER_U64 (sizeof(u64) * 8)

	static struct kmem_cache *ebitmap_node_cachep;

	int ebitmap_cmp(struct ebitmap e1, struct ebitmap e2)
	{
	struct ebitmap_node n1, n2;

	if (e1->highbit != e2->highbit)
	return 0;

	n1 = e1->node;
	n2 = e2->node;
	while (n1 && n2 &&
	(n1->startbit == n2->startbit) &&
	!memcmp(n1->maps, n2->maps, EBITMAP_SIZE / 8)) {
	n1 = n1->next;
	n2 = n2->next;
	}

	if (n1 \|\| n2)
	return 0;

	return 1;
	}

	int ebitmap_cpy(struct ebitmap dst, struct ebitmap src)
	{
	struct ebitmap_node n, new, *prev;

	ebitmap_init(dst);
	n = src->node;
	prev = NULL;
	while (n) {
	new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
	if (!new) {
	ebitmap_destroy(dst);
	return -ENOMEM;
	}
	new->startbit = n->startbit;
	memcpy(new->maps, n->maps, EBITMAP_SIZE / 8);
	new->next = NULL;
	if (prev)
	prev->next = new;
	else
	dst->node = new;
	prev = new;
	n = n->next;
	}

	dst->highbit = src->highbit;
	return 0;
	}

	#ifdef CONFIG_NETLABEL
	/**
	* ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap
	* @ebmap: the ebitmap to export
	* @catmap: the NetLabel category bitmap
	*
	* Description:
	* Export a SELinux extensibile bitmap into a NetLabel category bitmap.
	* Returns zero on success, negative values on error.
	*
	*/
	int ebitmap_netlbl_export(struct ebitmap *ebmap,
	struct netlbl_lsm_catmap **catmap)
	{
	struct ebitmap_node *e_iter = ebmap->node;
	unsigned long e_map;
	u32 offset;
	unsigned int iter;
	int rc;

	if (e_iter == NULL) {
	*catmap = NULL;
	return 0;
	}

	if (*catmap != NULL)
	netlbl_catmap_free(*catmap);
	*catmap = NULL;

	while (e_iter) {
	offset = e_iter->startbit;
	for (iter = 0; iter < EBITMAP_UNIT_NUMS; iter++) {
	e_map = e_iter->maps[iter];
	if (e_map != 0) {
	rc = netlbl_catmap_setlong(catmap,
	offset,
	e_map,
	GFP_ATOMIC);
	if (rc != 0)
	goto netlbl_export_failure;
	}
	offset += EBITMAP_UNIT_SIZE;
	}
	e_iter = e_iter->next;
	}

	return 0;

	netlbl_export_failure:
	netlbl_catmap_free(*catmap);
	return -ENOMEM;
	}

	/**
	* ebitmap_netlbl_import - Import a NetLabel category bitmap into an ebitmap
	* @ebmap: the ebitmap to import
	* @catmap: the NetLabel category bitmap
	*
	* Description:
	* Import a NetLabel category bitmap into a SELinux extensibile bitmap.
	* Returns zero on success, negative values on error.
	*
	*/
	int ebitmap_netlbl_import(struct ebitmap *ebmap,
	struct netlbl_lsm_catmap *catmap)
	{
	int rc;
	struct ebitmap_node *e_iter = NULL;
	struct ebitmap_node *e_prev = NULL;
	u32 offset = 0, idx;
	unsigned long bitmap;

	for (;;) {
	rc = netlbl_catmap_getlong(catmap, &offset, &bitmap);
	if (rc < 0)
	goto netlbl_import_failure;
	if (offset == (u32)-1)
	return 0;

	/* don't waste ebitmap space if the netlabel bitmap is empty */
	if (bitmap == 0) {
	offset += EBITMAP_UNIT_SIZE;
	continue;
	}

	if (e_iter == NULL \|\|
	offset >= e_iter->startbit + EBITMAP_SIZE) {
	e_prev = e_iter;
	e_iter = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
	if (e_iter == NULL)
	goto netlbl_import_failure;
	e_iter->startbit = offset - (offset % EBITMAP_SIZE);
	if (e_prev == NULL)
	ebmap->node = e_iter;
	else
	e_prev->next = e_iter;
	ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
	}

	/* offset will always be aligned to an unsigned long */
	idx = EBITMAP_NODE_INDEX(e_iter, offset);
	e_iter->maps[idx] = bitmap;

	/* next */
	offset += EBITMAP_UNIT_SIZE;
	}

	/* NOTE: we should never reach this return */
	return 0;

	netlbl_import_failure:
	ebitmap_destroy(ebmap);
	return -ENOMEM;
	}
	#endif /* CONFIG_NETLABEL */

	/*
	* Check to see if all the bits set in e2 are also set in e1. Optionally,
	* if last_e2bit is non-zero, the highest set bit in e2 cannot exceed
	* last_e2bit.
	*/
	int ebitmap_contains(struct ebitmap e1, struct ebitmap e2, u32 last_e2bit)
	{
	struct ebitmap_node n1, n2;
	int i;

	if (e1->highbit < e2->highbit)
	return 0;

	n1 = e1->node;
	n2 = e2->node;

	while (n1 && n2 && (n1->startbit <= n2->startbit)) {
	if (n1->startbit < n2->startbit) {
	n1 = n1->next;
	continue;
	}
	for (i = EBITMAP_UNIT_NUMS - 1; (i >= 0) && !n2->maps[i]; )
	i--; /* Skip trailing NULL map entries */
	if (last_e2bit && (i >= 0)) {
	u32 lastsetbit = n2->startbit + i * EBITMAP_UNIT_SIZE +
	__fls(n2->maps[i]);
	if (lastsetbit > last_e2bit)
	return 0;
	}

	while (i >= 0) {
	if ((n1->maps[i] & n2->maps[i]) != n2->maps[i])
	return 0;
	i--;
	}

	n1 = n1->next;
	n2 = n2->next;
	}

	if (n2)
	return 0;

	return 1;
	}

	int ebitmap_get_bit(struct ebitmap *e, unsigned long bit)
	{
	struct ebitmap_node *n;

	if (e->highbit < bit)
	return 0;

	n = e->node;
	while (n && (n->startbit <= bit)) {
	if ((n->startbit + EBITMAP_SIZE) > bit)
	return ebitmap_node_get_bit(n, bit);
	n = n->next;
	}

	return 0;
	}

	int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
	{
	struct ebitmap_node n, prev, *new;

	prev = NULL;
	n = e->node;
	while (n && n->startbit <= bit) {
	if ((n->startbit + EBITMAP_SIZE) > bit) {
	if (value) {
	ebitmap_node_set_bit(n, bit);
	} else {
	unsigned int s;

	ebitmap_node_clr_bit(n, bit);

	s = find_first_bit(n->maps, EBITMAP_SIZE);
	if (s < EBITMAP_SIZE)
	return 0;

	/* drop this node from the bitmap */
	if (!n->next) {
	/*
	* this was the highest map
	* within the bitmap
	*/
	if (prev)
	e->highbit = prev->startbit
	+ EBITMAP_SIZE;
	else
	e->highbit = 0;
	}
	if (prev)
	prev->next = n->next;
	else
	e->node = n->next;
	kmem_cache_free(ebitmap_node_cachep, n);
	}
	return 0;
	}
	prev = n;
	n = n->next;
	}

	if (!value)
	return 0;

	new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
	if (!new)
	return -ENOMEM;

	new->startbit = bit - (bit % EBITMAP_SIZE);
	ebitmap_node_set_bit(new, bit);

	if (!n)
	/* this node will be the highest map within the bitmap */
	e->highbit = new->startbit + EBITMAP_SIZE;

	if (prev) {
	new->next = prev->next;
	prev->next = new;
	} else {
	new->next = e->node;
	e->node = new;
	}

	return 0;
	}

	void ebitmap_destroy(struct ebitmap *e)
	{
	struct ebitmap_node n, temp;

	if (!e)
	return;

	n = e->node;
	while (n) {
	temp = n;
	n = n->next;
	kmem_cache_free(ebitmap_node_cachep, temp);
	}

	e->highbit = 0;
	e->node = NULL;
	return;
	}

	int ebitmap_read(struct ebitmap e, void fp)
	{
	struct ebitmap_node *n = NULL;
	u32 mapunit, count, startbit, index;
	u64 map;
	__le32 buf[3];
	int rc, i;

	ebitmap_init(e);

	rc = next_entry(buf, fp, sizeof buf);
	if (rc < 0)
	goto out;

	mapunit = le32_to_cpu(buf[0]);
	e->highbit = le32_to_cpu(buf[1]);
	count = le32_to_cpu(buf[2]);

	if (mapunit != BITS_PER_U64) {
	printk(KERN_ERR "SELinux: ebitmap: map size %u does not "
	"match my size %zd (high bit was %d)\n",
	mapunit, BITS_PER_U64, e->highbit);
	goto bad;
	}

	/* round up e->highbit */
	e->highbit += EBITMAP_SIZE - 1;
	e->highbit -= (e->highbit % EBITMAP_SIZE);

	if (!e->highbit) {
	e->node = NULL;
	goto ok;
	}

	if (e->highbit && !count)
	goto bad;

	for (i = 0; i < count; i++) {
	rc = next_entry(&startbit, fp, sizeof(u32));
	if (rc < 0) {
	printk(KERN_ERR "SELinux: ebitmap: truncated map\n");
	goto bad;
	}
	startbit = le32_to_cpu(startbit);

	if (startbit & (mapunit - 1)) {
	printk(KERN_ERR "SELinux: ebitmap start bit (%d) is "
	"not a multiple of the map unit size (%u)\n",
	startbit, mapunit);
	goto bad;
	}
	if (startbit > e->highbit - mapunit) {
	printk(KERN_ERR "SELinux: ebitmap start bit (%d) is "
	"beyond the end of the bitmap (%u)\n",
	startbit, (e->highbit - mapunit));
	goto bad;
	}

	if (!n \|\| startbit >= n->startbit + EBITMAP_SIZE) {
	struct ebitmap_node *tmp;
	tmp = kmem_cache_zalloc(ebitmap_node_cachep, GFP_KERNEL);
	if (!tmp) {
	printk(KERN_ERR
	"SELinux: ebitmap: out of memory\n");
	rc = -ENOMEM;
	goto bad;
	}
	/* round down */
	tmp->startbit = startbit - (startbit % EBITMAP_SIZE);
	if (n)
	n->next = tmp;
	else
	e->node = tmp;
	n = tmp;
	} else if (startbit <= n->startbit) {
	printk(KERN_ERR "SELinux: ebitmap: start bit %d"
	" comes after start bit %d\n",
	startbit, n->startbit);
	goto bad;
	}

	rc = next_entry(&map, fp, sizeof(u64));
	if (rc < 0) {
	printk(KERN_ERR "SELinux: ebitmap: truncated map\n");
	goto bad;
	}
	map = le64_to_cpu(map);

	index = (startbit - n->startbit) / EBITMAP_UNIT_SIZE;
	while (map) {
	n->maps[index++] = map & (-1UL);
	map = EBITMAP_SHIFT_UNIT_SIZE(map);
	}
	}
	ok:
	rc = 0;
	out:
	return rc;
	bad:
	if (!rc)
	rc = -EINVAL;
	ebitmap_destroy(e);
	goto out;
	}

	int ebitmap_write(struct ebitmap e, void fp)
	{
	struct ebitmap_node *n;
	u32 count;
	__le32 buf[3];
	u64 map;
	int bit, last_bit, last_startbit, rc;

	buf[0] = cpu_to_le32(BITS_PER_U64);

	count = 0;
	last_bit = 0;
	last_startbit = -1;
	ebitmap_for_each_positive_bit(e, n, bit) {
	if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
	count++;
	last_startbit = rounddown(bit, BITS_PER_U64);
	}
	last_bit = roundup(bit + 1, BITS_PER_U64);
	}
	buf[1] = cpu_to_le32(last_bit);
	buf[2] = cpu_to_le32(count);

	rc = put_entry(buf, sizeof(u32), 3, fp);
	if (rc)
	return rc;

	map = 0;
	last_startbit = INT_MIN;
	ebitmap_for_each_positive_bit(e, n, bit) {
	if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
	__le64 buf64[1];

	/* this is the very first bit */
	if (!map) {
	last_startbit = rounddown(bit, BITS_PER_U64);
	map = (u64)1 << (bit - last_startbit);
	continue;
	}

	/* write the last node */
	buf[0] = cpu_to_le32(last_startbit);
	rc = put_entry(buf, sizeof(u32), 1, fp);
	if (rc)
	return rc;

	buf64[0] = cpu_to_le64(map);
	rc = put_entry(buf64, sizeof(u64), 1, fp);
	if (rc)
	return rc;

	/* set up for the next node */
	map = 0;
	last_startbit = rounddown(bit, BITS_PER_U64);
	}
	map \|= (u64)1 << (bit - last_startbit);
	}
	/* write the last node */
	if (map) {
	__le64 buf64[1];

	/* write the last node */
	buf[0] = cpu_to_le32(last_startbit);
	rc = put_entry(buf, sizeof(u32), 1, fp);
	if (rc)
	return rc;

	buf64[0] = cpu_to_le64(map);
	rc = put_entry(buf64, sizeof(u64), 1, fp);
	if (rc)
	return rc;
	}
	return 0;
	}

	void ebitmap_cache_init(void)
	{
	ebitmap_node_cachep = kmem_cache_create("ebitmap_node",
	sizeof(struct ebitmap_node),
	0, SLAB_PANIC, NULL);
	}

	void ebitmap_cache_destroy(void)
	{
	kmem_cache_destroy(ebitmap_node_cachep);
	}