libbsm/common/au_preselect.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * au_preselect.c
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <bsm/audit.h>
#include <bsm/libbsm.h>
#include <synch.h>

#define ALLOC_INIT (600)    /* initially allocate ALLOC_INIT map entries */
#define ALLOC_INCR (100)    /* if more map entries are needed, realloc */
                /* in ALLOC_INCR increments */

static int alloc_map();
static int load_map();
static int realloc_map();

typedef struct event_map {
    au_event_t event;   /* audit event number */
    au_class_t class;   /* audit event class mask */
} event_map_t;

static event_map_t *event_map;  /* the map */
static uint_t alloc_count;  /* number of entries currently allocated */
static uint_t event_count;  /* number of entries in map */
static mutex_t mutex_au_preselect = DEFAULTMUTEX;

/*
 * au_preselect:
 *
 * Keep a dynamic array of event<-->class mappings.
 * Refresh the map when the value of flag is AU_PRS_REREAD.
 * Return:
 *  1: The event is preselected.
 *  0: The event is not preselected.
 *  -1: There was an error:
 *      Couldn't allocate memory.
 *      Couldn't find event.
 */
int
au_preselect(au_event_t au_event, au_mask_t *au_mask_p, int sorf, int flag)
{
    static char been_here_before;  /* we cache the map */
    register int i;
    register au_class_t comp_class;

    (void) mutex_lock(&mutex_au_preselect);
    if (!been_here_before) {
        if (alloc_map() == -1) {
            (void) mutex_unlock(&mutex_au_preselect);
            return (-1);
        }

        if (load_map() == -1) {
            (void) mutex_unlock(&mutex_au_preselect);
            return (-1);
        }

        been_here_before = 1;
    }

    /*
     * Don't use the cache. Re-read the audit_event(5) db every time
     */
    if (flag == AU_PRS_REREAD) {
        if (load_map() == -1) {
            (void) mutex_unlock(&mutex_au_preselect);
            return (-1);
        }
    }

    /* Determine what portion of the preselection mask to check. */
    if (sorf == AU_PRS_SUCCESS)
        comp_class = au_mask_p->am_success;
    else if (sorf == AU_PRS_FAILURE)
        comp_class = au_mask_p->am_failure;
    else
        comp_class = au_mask_p->am_success | au_mask_p->am_failure;

    for (i = 0; i < event_count; i++) {
        if (event_map[i].event == au_event) {
            if (event_map[i].class & comp_class) {
                (void) mutex_unlock(&mutex_au_preselect);
                return (1);
            } else {
                (void) mutex_unlock(&mutex_au_preselect);
                return (0);
            }
        }
    }

    (void) mutex_unlock(&mutex_au_preselect);
    return (-1);    /* could not find event in the table */
}

/*
 * Initially allocate about as many map entries as are there
 * are audit events shipped with the system. For sites
 * that don't add audit events, this should be enough.
 */
static int
alloc_map()
{
    if ((event_map = (event_map_t *)
        calloc(ALLOC_INIT, (size_t)sizeof (event_map_t))) ==
        (event_map_t *)NULL)
        return (-1);
    else
        alloc_count = ALLOC_INIT;

    return (0);
}

/*
 * load the event<->class map into memory
 */
static int
load_map()
{
    register au_event_ent_t *evp;

    event_count = 0;
    setauevent();
    while ((evp = getauevent()) != (au_event_ent_t *)NULL) {
        if (event_count > alloc_count)
            if (realloc_map() == -1) {
                endauevent();
                return (-1);
            }
        event_map[event_count].event = evp->ae_number;
        event_map[event_count].class = evp->ae_class;
        ++event_count;
    }
    endauevent();

    return (0);
}

/*
 * realloc the event map in ALLOC_INCR increments
 */
static int
realloc_map()
{
    register size_t rsize;
    rsize = sizeof (event_map_t) * (alloc_count + ALLOC_INCR);

    if ((event_map = (event_map_t *)
        realloc(event_map, rsize)) == (event_map_t *)NULL)
        return (-1);

    return (0);
}