/*-
 * Copyright (c) 2001 Networks Associates Technologies, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by NAI Labs, the
 * Security Research Division of Network Associates, Inc. under
 * DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA
 * CHATS research program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#ifndef LOMAC_H_
#define LOMAC_H_

typedef enum {
	LOMAC_LOWEST_LEVEL = 1,
	LOMAC_HIGHEST_LEVEL = 2
} level_t;


typedef struct {
	level_t level;		/* level (an integer range) */
	unsigned int flags;	/* category flags */
} lattr_t;			/* lomac attribute structure type */


/* lomac_must_demote()
 *
 * in:     actor  - attributes of a subject that has or will perform an
 *                  operation that may require LOMAC to demote it.
 *         target - attributes of the object that is or was the operand.
 * out:    nothing
 * return: value   condition
 *         -----   ---------
 *           0     LOMAC should not demote the subject
 *           1     LOMAC should demote the subject
 *
 * This function is a predicate which decides whether or not LOMAC should
 * demote the subject with attributes `actor' after it performs an operation
 * (probably some kind of a read operation) on the object with attributes 
 * `target'.
 *
 */

static __inline int
lomac_must_demote(const lattr_t *actor, const lattr_t *target) {
	return (actor->level > target->level);
}


/* lomac_must_deny()
 *
 * in:     actor  - attributes of a subject that wants to perform some
 *                  operation that requires LOMAC to make an allow/deny
 *                  decision.
 *         target - attributes of the subject or object the above subject
 *                  will operate upon.
 * out:    nothing
 * return: value     condition
 *         -----     ---------
 *           0       LOMAC should allow the operation
 *           1       LOMAC should deny the operation
 *
 * This function is a predicate which decides whether or not LOMAC should
 * allow the subject with attributes `actor' to perform some operation
 * (probably some kind of write or kill operation) on the subject or object
 * with attributes `target'.
 *
 * The flags are two words: the low word is to be used for categories,
 * and the high word is meant to hold implementation-dependent flags that
 * are not category-related.
 *
 */

static __inline int
lomac_must_deny(const lattr_t *actor, const lattr_t *target) {

	if (actor->level >= target->level)
		return 0;            /* allow */
	if (target->flags & 0xffff) {
		if ((actor->flags & target->flags & 0xffff) ==
		    (target->flags & 0xffff)) {
			return 0;    /* allow */
		}
	}
	return 1;                    /* deny */
}

#endif /* LOMAC_H */