Commit message: 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>
CVE: CVE-2013-4588
CWE: CWE-119
Vulnerability description: Multiple stack-based buffer overflows in net/netfilter/ipvs/ip_vs_ctl.c in the Linux kernel before 2.6.33, when CONFIG_IP_VS is used, allow local users to gain privileges by leveraging the CAP_NET_ADMIN capability for (1) a getsockopt system call, related to the do_ip_vs_get_ctl function, or (2) a setsockopt system call, related to the do_ip_vs_set_ctl function.

Project: linux
File: ip_vs_ctl.c

do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
{
	int ret;
	unsigned char arg[MAX_ARG_LEN];
	struct ip_vs_service_user *usvc_compat;
	struct ip_vs_service_user_kern usvc;
	struct ip_vs_service *svc;
	struct ip_vs_dest_user *udest_compat;
	struct ip_vs_dest_user_kern udest;

 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
 	if (len != set_arglen[SET_CMDID(cmd)]) {
 		pr_err("set_ctl: len %u != %u\n",
 		       len, set_arglen[SET_CMDID(cmd)]);
		return -EINVAL;
	}

	if (copy_from_user(arg, user, len) != 0)
		return -EFAULT;

	/* increase the module use count */
	ip_vs_use_count_inc();

	if (mutex_lock_interruptible(&__ip_vs_mutex)) {
		ret = -ERESTARTSYS;
		goto out_dec;
	}

	if (cmd == IP_VS_SO_SET_FLUSH) {
		/* Flush the virtual service */
		ret = ip_vs_flush();
		goto out_unlock;
	} else if (cmd == IP_VS_SO_SET_TIMEOUT) {
		/* Set timeout values for (tcp tcpfin udp) */
		ret = ip_vs_set_timeout((struct ip_vs_timeout_user *)arg);
		goto out_unlock;
	} else if (cmd == IP_VS_SO_SET_STARTDAEMON) {
		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
		ret = start_sync_thread(dm->state, dm->mcast_ifn, dm->syncid);
		goto out_unlock;
	} else if (cmd == IP_VS_SO_SET_STOPDAEMON) {
		struct ip_vs_daemon_user *dm = (struct ip_vs_daemon_user *)arg;
		ret = stop_sync_thread(dm->state);
		goto out_unlock;
	}

	usvc_compat = (struct ip_vs_service_user *)arg;
	udest_compat = (struct ip_vs_dest_user *)(usvc_compat + 1);

	/* We only use the new structs internally, so copy userspace compat
	 * structs to extended internal versions */
	ip_vs_copy_usvc_compat(&usvc, usvc_compat);
	ip_vs_copy_udest_compat(&udest, udest_compat);

	if (cmd == IP_VS_SO_SET_ZERO) {
		/* if no service address is set, zero counters in all */
		if (!usvc.fwmark && !usvc.addr.ip && !usvc.port) {
			ret = ip_vs_zero_all();
			goto out_unlock;
		}
	}

	/* Check for valid protocol: TCP or UDP, even for fwmark!=0 */
	if (usvc.protocol != IPPROTO_TCP && usvc.protocol != IPPROTO_UDP) {
		pr_err("set_ctl: invalid protocol: %d %pI4:%d %s\n",
		       usvc.protocol, &usvc.addr.ip,
		       ntohs(usvc.port), usvc.sched_name);
		ret = -EFAULT;
		goto out_unlock;
	}

	/* Lookup the exact service by <protocol, addr, port> or fwmark */
	if (usvc.fwmark == 0)
		svc = __ip_vs_service_get(usvc.af, usvc.protocol,
					  &usvc.addr, usvc.port);
	else
		svc = __ip_vs_svc_fwm_get(usvc.af, usvc.fwmark);

	if (cmd != IP_VS_SO_SET_ADD
	    && (svc == NULL || svc->protocol != usvc.protocol)) {
		ret = -ESRCH;
		goto out_unlock;
	}

	switch (cmd) {
	case IP_VS_SO_SET_ADD:
		if (svc != NULL)
			ret = -EEXIST;
		else
			ret = ip_vs_add_service(&usvc, &svc);
		break;
	case IP_VS_SO_SET_EDIT:
		ret = ip_vs_edit_service(svc, &usvc);
		break;
	case IP_VS_SO_SET_DEL:
		ret = ip_vs_del_service(svc);
		if (!ret)
			goto out_unlock;
		break;
	case IP_VS_SO_SET_ZERO:
		ret = ip_vs_zero_service(svc);
		break;
	case IP_VS_SO_SET_ADDDEST:
		ret = ip_vs_add_dest(svc, &udest);
		break;
	case IP_VS_SO_SET_EDITDEST:
		ret = ip_vs_edit_dest(svc, &udest);
		break;
	case IP_VS_SO_SET_DELDEST:
		ret = ip_vs_del_dest(svc, &udest);
		break;
	default:
		ret = -EINVAL;
	}

	if (svc)
		ip_vs_service_put(svc);

  out_unlock:
	mutex_unlock(&__ip_vs_mutex);
  out_dec:
	/* decrease the module use count */
	ip_vs_use_count_dec();

	return ret;
}