Function mac_policy_register

freebsd/security/mac/mac_framework.c:510–592

#undef FPO

static int
mac_policy_register(struct mac_policy_conf *mpc)
{
	struct mac_policy_conf *tmpc;
	int error, slot, static_entry;

	error = 0;

	/*
	 * We don't technically need exclusive access while !mac_late, but
	 * hold it for assertion consistency.
	 */
	mac_policy_xlock();

	/*
	 * If the module can potentially be unloaded, or we're loading late,
	 * we have to stick it in the non-static list and pay an extra
	 * performance overhead.  Otherwise, we can pay a light locking cost
	 * and stick it in the static list.
	 */
	static_entry = (!mac_late &&
	    !(mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK));

	if (static_entry) {
		LIST_FOREACH(tmpc, &mac_static_policy_list, mpc_list) {
			if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
				error = EEXIST;
				goto out;
			}
		}
	} else {
		LIST_FOREACH(tmpc, &mac_policy_list, mpc_list) {
			if (strcmp(tmpc->mpc_name, mpc->mpc_name) == 0) {
				error = EEXIST;
				goto out;
			}
		}
	}
	if (mpc->mpc_field_off != NULL) {
		slot = ffs(mac_slot_offsets_free);
		if (slot == 0) {
			error = ENOMEM;
			goto out;
		}
		slot--;
		mac_slot_offsets_free &= ~(1 << slot);
		*mpc->mpc_field_off = slot;
	}
	mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED;

	/*
	 * If we're loading a MAC module after the framework has initialized,
	 * it has to go into the dynamic list.  If we're loading it before
	 * we've finished initializing, it can go into the static list with
	 * weaker locker requirements.
	 */
	if (static_entry)
		LIST_INSERT_HEAD(&mac_static_policy_list, mpc, mpc_list);