common.c

/* common.c --
 * Copyright 2023 Red Hat Inc.
 * All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Authors:
 *      Steve Grubb <sgrubb@redhat.com>
 */

#include "libaudit.h"
#include "common.h"
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <utmpx.h>
#include <fcntl.h>

/*
 * This function returns 1 if it is the last record in an event.
 * It returns 0 otherwise.
 *
 * When processing an event stream we define the end of an event via
 *   record type = AUDIT_EOE (audit end of event type record), or
 *   record type = AUDIT_PROCTITLE   (we note the AUDIT_PROCTITLE is always
 *                                    the last record), or
 *   record type = AUDIT_KERNEL (kernel events are one record events), or
 *   record type < AUDIT_FIRST_EVENT (only single record events appear
 *                                    before this type), or
 *   record type >= AUDIT_FIRST_ANOM_MSG (only single record events appear
 *                                      after this type), or
 *   record type >= AUDIT_MAC_UNLBL_ALLOW && record type <= AUDIT_MAC_CALIPSO_DEL
 *                                       (these are also one record events)
 */
int audit_is_last_record(int type)
{
	if (type == AUDIT_PROCTITLE ||
	    type == AUDIT_EOE ||
	    (type > AUDIT_LOGIN &&
	     type < AUDIT_FIRST_EVENT) ||
	    type == AUDIT_USER ||
	    type >= AUDIT_FIRST_ANOM_MSG ||
	    type == AUDIT_KERNEL ||
	    (type >= AUDIT_MAC_UNLBL_ALLOW &&
	     type <= AUDIT_MAC_CALIPSO_DEL)) {
		return 1;
	}
	return 0;
}

int write_to_console(const char *fmt, ...)
{
	int fd;
	int res = 1;
	va_list args;

	if ((fd = open("/dev/console", O_WRONLY)) < 0)
		return 0;

	va_start(args, fmt);
	if (vdprintf(fd, fmt, args) < 0) {
		res = 0;
	}
	va_end(args);
	close(fd);

	return res;
}

void wall_message(const char* format, ...)
{
	struct utmpx* entry;
	char message[512];
	va_list args;
	int fd;

	// Format the message
	va_start(args, format);
	vsnprintf(message, sizeof(message), format, args);
	va_end(args);

	setutxent();

	// Send the message to all active users
	while ((entry = getutxent())) {
		// Only active users have a valid terminal
		if (entry->ut_type == USER_PROCESS) {
			char tty_path[128];
			snprintf(tty_path, sizeof(tty_path), "/dev/%s", entry->ut_line);

			fd = open(tty_path, O_WRONLY | O_NOCTTY);
			if (fd != -1) {
				dprintf(fd, "\nBroadcast message from audit daemon:\n%s\n", message);
				close(fd);
			}
		}
	}

	endutxent();
}