/*
 * kern.msgbuf and machdep.msgbuf sysctls protection for FreeBSD 4.x.
 *
 * (c) 2003 Pawel Jakub Dawidek <nick@garage.freebsd.pl>
 *
 * $Id: msgbuf.c,v 1.1.1.1 2003/02/11 12:42:09 jules Exp $
 */

#include <sys/param.h>

#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/libkern.h>
#include <sys/kernel.h>
#include <sys/syslog.h>


extern int	name2oid(char *, int *, int *, struct sysctl_oid **);
extern int	sysctl_kern_msgbuf(SYSCTL_HANDLER_ARGS);
extern int	sysctl_machdep_msgbuf(SYSCTL_HANDLER_ARGS);

static int	(*vmb_sysctl_kern_msgbuf)(SYSCTL_HANDLER_ARGS);
static int	(*vmb_sysctl_machdep_msgbuf)(SYSCTL_HANDLER_ARGS);

static struct sysctl_oid	*kern_msgbuf_oid;
static struct sysctl_oid	*machdep_msgbuf_oid;

static int
fmb_sysctl_kern_msgbuf(SYSCTL_HANDLER_ARGS)
{
	int	error;

	if ((error = suser(curproc)) != 0)
		return (error);

	return (vmb_sysctl_kern_msgbuf(oidp, arg1, arg2, req));
}

static int
fmb_sysctl_machdep_msgbuf(SYSCTL_HANDLER_ARGS)
{
	int	error;

	if ((error = suser(curproc)) != 0)
		return (error);

	return (vmb_sysctl_machdep_msgbuf(oidp, arg1, arg2, req));
}

static int
fmb_sysctls_switch(void)
{
	struct sysctl_oid	*oidp;
	int	oid[CTL_MAXNAME], len, error;

	/* kern.msgbuf */
	error = name2oid("kern.msgbuf", oid, &len, &oidp);
	if (error != 0) {
		printf("msgbuf: Unexpected error while looking for kern.msgbuf "
		    "sysctl.\n");
		return (error);
	}
	vmb_sysctl_kern_msgbuf = oidp->oid_handler;
	oidp->oid_handler = fmb_sysctl_kern_msgbuf;
	kern_msgbuf_oid = oidp;

	/* machdep.msgbuf */
	error = name2oid("machdep.msgbuf", oid, &len, &oidp);
	if (error != 0) {
		printf("msgbuf: Unexpected error while looking for "
		    "machdep.msgbuf sysctl.\n");
		return (error);
	}
	vmb_sysctl_machdep_msgbuf = oidp->oid_handler;
	oidp->oid_handler = fmb_sysctl_machdep_msgbuf;
	machdep_msgbuf_oid = oidp;

	return (0);
}

static void
fmb_sysctls_backswitch(void)
{

	/* kern.msgbuf */
	kern_msgbuf_oid->oid_handler = vmb_sysctl_kern_msgbuf;

	/* machdep.msgbuf */
	machdep_msgbuf_oid->oid_handler = vmb_sysctl_machdep_msgbuf;
}

static int
mod(struct module *module, int cmd, void *arg)
{
	int error;

	error = 0;

	switch (cmd) {
	case MOD_LOAD:
		error = fmb_sysctls_switch();
		if (error != 0)
			break;
		log(LOG_INFO, "msgbuf protection loaded.\n");
		break;
	case MOD_UNLOAD:
		fmb_sysctls_backswitch();
		log(LOG_INFO, "msgbuf protection unloaded.\n");
		break;
	default:
		error = EINVAL;
		break;
	}

	return (error);
}

static moduledata_t msgbuf_mod = {
	"msgbuf",
	mod,
	NULL
};

DECLARE_MODULE(msgbuf, msgbuf_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);