Function sysctl_root

freebsd/kern/kern_sysctl.c:2157–2257

 */

static int
sysctl_root(SYSCTL_HANDLER_ARGS)
{
	struct sysctl_oid *oid;
	struct rm_priotracker tracker;
	int error, indx, lvl;

	SYSCTL_RLOCK(&tracker);

	error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
	if (error)
		goto out;

	if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
		/*
		 * You can't call a sysctl when it's a node, but has
		 * no handler.  Inform the user that it's a node.
		 * The indx may or may not be the same as namelen.
		 */
		if (oid->oid_handler == NULL) {
			error = EISDIR;
			goto out;
		}
	}

	/* Is this sysctl writable? */
	if (req->newptr && !(oid->oid_kind & CTLFLAG_WR)) {
		error = EPERM;
		goto out;
	}

	KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));

#ifdef CAPABILITY_MODE
	/*
	 * If the process is in capability mode, then don't permit reading or
	 * writing unless specifically granted for the node.
	 */
	if (IN_CAPABILITY_MODE(req->td)) {
		if ((req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD)) ||
		    (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))) {
			error = EPERM;
			goto out;
		}
	}
#endif

	/* Is this sysctl sensitive to securelevels? */
	if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
		lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
		error = securelevel_gt(req->td->td_ucred, lvl);
		if (error)
			goto out;
	}

	/* Is this sysctl writable by only privileged users? */
	if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
		int priv;