ipvs: Add boundary check on ioctl arguments

The ipvs code has a nifty system for doing the size of ioctl command
copies; it defines an array with values into which it indexes the cmd
to find the right length.

Unfortunately, the ipvs code forgot to check if the cmd was in the
range that the array provides, allowing for an index outside of the
array, which then gives a "garbage" result into the length, which
then gets used for copying into a stack buffer.

Fix this by adding sanity checks on these as well as the copy size.

[ horms@verge.net.au: adjusted limit to IP_VS_SO_GET_MAX ]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
{
	struct ip_vs_scheduler *sched, *old_sched;
	int ret = 0;

	/*
	 * Lookup the scheduler, by 'u->sched_name'
	 */
	sched = ip_vs_scheduler_get(u->sched_name);
	if (sched == NULL) {
		pr_info("Scheduler module ip_vs_%s not found\n", u->sched_name);
		return -ENOENT;
	}
	old_sched = sched;

#ifdef CONFIG_IP_VS_IPV6
	if (u->af == AF_INET6 && (u->netmask < 1 || u->netmask > 128)) {
		ret = -EINVAL;
		goto out;
	}
#endif

	write_lock_bh(&__ip_vs_svc_lock);

	/*
	 * Wait until all other svc users go away.
	 */
	IP_VS_WAIT_WHILE(atomic_read(&svc->usecnt) > 1);

	/*
	 * Set the flags and timeout value
	 */
	svc->flags = u->flags | IP_VS_SVC_F_HASHED;
	svc->timeout = u->timeout * HZ;
	svc->netmask = u->netmask;

	old_sched = svc->scheduler;
	if (sched != old_sched) {
		/*
		 * Unbind the old scheduler
		 */
		if ((ret = ip_vs_unbind_scheduler(svc))) {
			old_sched = sched;
			goto out_unlock;
		}

		/*
		 * Bind the new scheduler
		 */
		if ((ret = ip_vs_bind_scheduler(svc, sched))) {
			/*
			 * If ip_vs_bind_scheduler fails, restore the old
			 * scheduler.
			 * The main reason of failure is out of memory.
			 *
			 * The question is if the old scheduler can be
			 * restored all the time. TODO: if it cannot be
			 * restored some time, we must delete the service,
			 * otherwise the system may crash.
			 */
			ip_vs_bind_scheduler(svc, old_sched);
			old_sched = sched;
			goto out_unlock;
		}
	}

  out_unlock:
	write_unlock_bh(&__ip_vs_svc_lock);
#ifdef CONFIG_IP_VS_IPV6
  out:
#endif

	if (old_sched)
		ip_vs_scheduler_put(old_sched);

	return ret;
}

ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
{
	struct ip_vs_scheduler *sched, *old_sched;
	int ret = 0;

	/*
	 * Lookup the scheduler, by 'u->sched_name'
	 */
	sched = ip_vs_scheduler_get(u->sched_name);
	if (sched == NULL) {
		pr_info("Scheduler module ip_vs_%s not found\n", u->sched_name);
		return -ENOENT;
	}
	old_sched = sched;

#ifdef CONFIG_IP_VS_IPV6
	if (u->af == AF_INET6 && (u->netmask < 1 || u->netmask > 128)) {
		ret = -EINVAL;
		goto out;
	}
#endif

	write_lock_bh(&__ip_vs_svc_lock);

	/*
	 * Wait until all other svc users go away.
	 */
	IP_VS_WAIT_WHILE(atomic_read(&svc->usecnt) > 1);

	/*
	 * Set the flags and timeout value
	 */
	svc->flags = u->flags | IP_VS_SVC_F_HASHED;
	svc->timeout = u->timeout * HZ;
	svc->netmask = u->netmask;

	old_sched = svc->scheduler;
	if (sched != old_sched) {
		/*
		 * Unbind the old scheduler
		 */
		if ((ret = ip_vs_unbind_scheduler(svc))) {
			old_sched = sched;
			goto out_unlock;
		}

		/*
		 * Bind the new scheduler
		 */
		if ((ret = ip_vs_bind_scheduler(svc, sched))) {
			/*
			 * If ip_vs_bind_scheduler fails, restore the old
			 * scheduler.
			 * The main reason of failure is out of memory.
			 *
			 * The question is if the old scheduler can be
			 * restored all the time. TODO: if it cannot be
			 * restored some time, we must delete the service,
			 * otherwise the system may crash.
			 */
			ip_vs_bind_scheduler(svc, old_sched);
			old_sched = sched;
			goto out_unlock;
		}
	}

  out_unlock:
	write_unlock_bh(&__ip_vs_svc_lock);
#ifdef CONFIG_IP_VS_IPV6
  out:
#endif

	if (old_sched)
		ip_vs_scheduler_put(old_sched);

	return ret;
}
