net/ipv4/fou.c - kernel/msm-4.9 - Gitiles

 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/socket.h>
 #include <linux/skbuff.h>
 #include <linux/ip.h>
 #include <linux/udp.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <net/genetlink.h>
 #include <net/gue.h>
 #include <net/ip.h>
 #include <net/protocol.h>
 #include <net/udp.h>
 #include <net/udp_tunnel.h>
 #include <net/xfrm.h>
 #include <uapi/linux/fou.h>
 #include <uapi/linux/genetlink.h>

 static DEFINE_SPINLOCK(fou_lock);
 static LIST_HEAD(fou_list);

 struct fou {
 	struct socket *sock;
 	u8 protocol;
 	u16 port;
 	struct udp_offload udp_offloads;
 	struct list_head list;
 };

 struct fou_cfg {
 	u16 type;
 	u8 protocol;
 	struct udp_port_cfg udp_config;
 };

 static inline struct fou *fou_from_sock(struct sock *sk)
 {
 	return sk->sk_user_data;
 }

 static void fou_recv_pull(struct sk_buff *skb, size_t len)
 {
 	struct iphdr *iph = ip_hdr(skb);

 	/* Remove 'len' bytes from the packet (UDP header and
 	 * FOU header if present).
 	 */
 	iph->tot_len = htons(ntohs(iph->tot_len) - len);
 	__skb_pull(skb, len);
 	skb_postpull_rcsum(skb, udp_hdr(skb), len);
 	skb_reset_transport_header(skb);
 }

 static int fou_udp_recv(struct sock *sk, struct sk_buff *skb)
 {
 	struct fou *fou = fou_from_sock(sk);

 	if (!fou)
 		return 1;

 	fou_recv_pull(skb, sizeof(struct udphdr));

 	return -fou->protocol;
 }

 static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
 				  void *data, size_t hdrlen, u8 ipproto)
 {
 	__be16 *pd = data;
 	size_t start = ntohs(pd[0]);
 	size_t offset = ntohs(pd[1]);
 	size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
 	__wsum delta;

 	if (skb->remcsum_offload) {
 		/* Already processed in GRO path */
 		skb->remcsum_offload = 0;
 		return guehdr;
 	}

 	if (!pskb_may_pull(skb, plen))
 		return NULL;
 	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

 	if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
 		__skb_checksum_complete(skb);

 	delta = remcsum_adjust((void *)guehdr + hdrlen,
 			       skb->csum, start, offset);

 	/* Adjust skb->csum since we changed the packet */
 	skb->csum = csum_add(skb->csum, delta);

 	return guehdr;
 }

 static int gue_control_message(struct sk_buff *skb, struct guehdr *guehdr)
 {
 	/* No support yet */
 	kfree_skb(skb);
 	return 0;
 }

 static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
 {
 	struct fou *fou = fou_from_sock(sk);
 	size_t len, optlen, hdrlen;
 	struct guehdr *guehdr;
 	void *data;
 	u16 doffset = 0;

 	if (!fou)
 		return 1;

 	len = sizeof(struct udphdr) + sizeof(struct guehdr);
 	if (!pskb_may_pull(skb, len))
 		goto drop;

 	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

 	optlen = guehdr->hlen << 2;
 	len += optlen;

 	if (!pskb_may_pull(skb, len))
 		goto drop;

 	/* guehdr may change after pull */
 	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

 	hdrlen = sizeof(struct guehdr) + optlen;

 	if (guehdr->version != 0 || validate_gue_flags(guehdr, optlen))
 		goto drop;

 	hdrlen = sizeof(struct guehdr) + optlen;

 	ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(skb)->tot_len) - len);

 	/* Pull csum through the guehdr now . This can be used if
 	 * there is a remote checksum offload.
 	 */
 	skb_postpull_rcsum(skb, udp_hdr(skb), len);

 	data = &guehdr[1];

 	if (guehdr->flags & GUE_FLAG_PRIV) {
 		__be32 flags = *(__be32 *)(data + doffset);

 		doffset += GUE_LEN_PRIV;

 		if (flags & GUE_PFLAG_REMCSUM) {
 			guehdr = gue_remcsum(skb, guehdr, data + doffset,
 					     hdrlen, guehdr->proto_ctype);
 			if (!guehdr)
 				goto drop;

 			data = &guehdr[1];

 			doffset += GUE_PLEN_REMCSUM;
 		}
 	}

 	if (unlikely(guehdr->control))
 		return gue_control_message(skb, guehdr);

 	__skb_pull(skb, sizeof(struct udphdr) + hdrlen);
 	skb_reset_transport_header(skb);

 	return -guehdr->proto_ctype;

 drop:
 	kfree_skb(skb);
 	return 0;
 }

 static struct sk_buff **fou_gro_receive(struct sk_buff **head,
 					struct sk_buff *skb)
 {
 	const struct net_offload *ops;
 	struct sk_buff **pp = NULL;
 	u8 proto = NAPI_GRO_CB(skb)->proto;
 	const struct net_offload **offloads;

 	rcu_read_lock();
 	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
 	ops = rcu_dereference(offloads[proto]);
 	if (!ops || !ops->callbacks.gro_receive)
 		goto out_unlock;

 	pp = ops->callbacks.gro_receive(head, skb);

 out_unlock:
 	rcu_read_unlock();

 	return pp;
 }

 static int fou_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct net_offload *ops;
 	u8 proto = NAPI_GRO_CB(skb)->proto;
 	int err = -ENOSYS;
 	const struct net_offload **offloads;

 	udp_tunnel_gro_complete(skb, nhoff);

 	rcu_read_lock();
 	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
 	ops = rcu_dereference(offloads[proto]);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out_unlock;

 	err = ops->callbacks.gro_complete(skb, nhoff);

 out_unlock:
 	rcu_read_unlock();

 	return err;
 }

 static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
 				      struct guehdr *guehdr, void *data,
 				      size_t hdrlen, u8 ipproto)
 {
 	__be16 *pd = data;
 	size_t start = ntohs(pd[0]);
 	size_t offset = ntohs(pd[1]);
 	size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
 	__wsum delta;

 	if (skb->remcsum_offload)
 		return guehdr;

 	if (!NAPI_GRO_CB(skb)->csum_valid)
 		return NULL;

 	/* Pull checksum that will be written */
 	if (skb_gro_header_hard(skb, off + plen)) {
 		guehdr = skb_gro_header_slow(skb, off + plen, off);
 		if (!guehdr)
 			return NULL;
 	}

 	delta = remcsum_adjust((void *)guehdr + hdrlen,
 			       NAPI_GRO_CB(skb)->csum, start, offset);

 	/* Adjust skb->csum since we changed the packet */
 	skb->csum = csum_add(skb->csum, delta);
 	NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);

 	skb->remcsum_offload = 1;

 	return guehdr;
 }

 static struct sk_buff **gue_gro_receive(struct sk_buff **head,
 					struct sk_buff *skb)
 {
 	const struct net_offload **offloads;
 	const struct net_offload *ops;
 	struct sk_buff **pp = NULL;
 	struct sk_buff *p;
 	struct guehdr *guehdr;
 	size_t len, optlen, hdrlen, off;
 	void *data;
 	u16 doffset = 0;
 	int flush = 1;

 	off = skb_gro_offset(skb);
 	len = off + sizeof(*guehdr);

 	guehdr = skb_gro_header_fast(skb, off);
 	if (skb_gro_header_hard(skb, len)) {
 		guehdr = skb_gro_header_slow(skb, len, off);
 		if (unlikely(!guehdr))
 			goto out;
 	}

 	optlen = guehdr->hlen << 2;
 	len += optlen;

 	if (skb_gro_header_hard(skb, len)) {
 		guehdr = skb_gro_header_slow(skb, len, off);
 		if (unlikely(!guehdr))
 			goto out;
 	}

 	if (unlikely(guehdr->control) || guehdr->version != 0 ||
 	    validate_gue_flags(guehdr, optlen))
 		goto out;

 	hdrlen = sizeof(*guehdr) + optlen;

 	/* Adjust NAPI_GRO_CB(skb)->csum to account for guehdr,
 	 * this is needed if there is a remote checkcsum offload.
 	 */
 	skb_gro_postpull_rcsum(skb, guehdr, hdrlen);

 	data = &guehdr[1];

 	if (guehdr->flags & GUE_FLAG_PRIV) {
 		__be32 flags = *(__be32 *)(data + doffset);

 		doffset += GUE_LEN_PRIV;

 		if (flags & GUE_PFLAG_REMCSUM) {
 			guehdr = gue_gro_remcsum(skb, off, guehdr,
 						 data + doffset, hdrlen,
 						 guehdr->proto_ctype);
 			if (!guehdr)
 				goto out;

 			data = &guehdr[1];

 			doffset += GUE_PLEN_REMCSUM;
 		}
 	}

 	skb_gro_pull(skb, hdrlen);

 	flush = 0;

 	for (p = *head; p; p = p->next) {
 		const struct guehdr *guehdr2;

 		if (!NAPI_GRO_CB(p)->same_flow)
 			continue;

 		guehdr2 = (struct guehdr *)(p->data + off);

 		/* Compare base GUE header to be equal (covers
 		 * hlen, version, proto_ctype, and flags.
 		 */
 		if (guehdr->word != guehdr2->word) {
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 		}

 		/* Compare optional fields are the same. */
 		if (guehdr->hlen && memcmp(&guehdr[1], &guehdr2[1],
 					   guehdr->hlen << 2)) {
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 		}
 	}

 	rcu_read_lock();
 	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
 	ops = rcu_dereference(offloads[guehdr->proto_ctype]);
 	if (WARN_ON(!ops || !ops->callbacks.gro_receive))
 		goto out_unlock;

 	pp = ops->callbacks.gro_receive(head, skb);

 out_unlock:
 	rcu_read_unlock();
 out:
 	NAPI_GRO_CB(skb)->flush |= flush;

 	return pp;
 }

 static int gue_gro_complete(struct sk_buff *skb, int nhoff)
 {
 	const struct net_offload **offloads;
 	struct guehdr *guehdr = (struct guehdr *)(skb->data + nhoff);
 	const struct net_offload *ops;
 	unsigned int guehlen;
 	u8 proto;
 	int err = -ENOENT;

 	proto = guehdr->proto_ctype;

 	guehlen = sizeof(*guehdr) + (guehdr->hlen << 2);

 	rcu_read_lock();
 	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
 	ops = rcu_dereference(offloads[proto]);
 	if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 		goto out_unlock;

 	err = ops->callbacks.gro_complete(skb, nhoff + guehlen);

 out_unlock:
 	rcu_read_unlock();
 	return err;
 }

 static int fou_add_to_port_list(struct fou *fou)
 {
 	struct fou *fout;

 	spin_lock(&fou_lock);
 	list_for_each_entry(fout, &fou_list, list) {
 		if (fou->port == fout->port) {
 			spin_unlock(&fou_lock);
 			return -EALREADY;
 		}
 	}

 	list_add(&fou->list, &fou_list);
 	spin_unlock(&fou_lock);

 	return 0;
 }

 static void fou_release(struct fou *fou)
 {
 	struct socket *sock = fou->sock;
 	struct sock *sk = sock->sk;

 	udp_del_offload(&fou->udp_offloads);

 	list_del(&fou->list);

 	/* Remove hooks into tunnel socket */
 	sk->sk_user_data = NULL;

 	sock_release(sock);

 	kfree(fou);
 }

 static int fou_encap_init(struct sock *sk, struct fou *fou, struct fou_cfg *cfg)
 {
 	udp_sk(sk)->encap_rcv = fou_udp_recv;
 	fou->protocol = cfg->protocol;
 	fou->udp_offloads.callbacks.gro_receive = fou_gro_receive;
 	fou->udp_offloads.callbacks.gro_complete = fou_gro_complete;
 	fou->udp_offloads.port = cfg->udp_config.local_udp_port;
 	fou->udp_offloads.ipproto = cfg->protocol;

 	return 0;
 }

 static int gue_encap_init(struct sock *sk, struct fou *fou, struct fou_cfg *cfg)
 {
 	udp_sk(sk)->encap_rcv = gue_udp_recv;
 	fou->udp_offloads.callbacks.gro_receive = gue_gro_receive;
 	fou->udp_offloads.callbacks.gro_complete = gue_gro_complete;
 	fou->udp_offloads.port = cfg->udp_config.local_udp_port;

 	return 0;
 }

 static int fou_create(struct net *net, struct fou_cfg *cfg,
 		      struct socket **sockp)
 {
 	struct fou *fou = NULL;
 	int err;
 	struct socket *sock = NULL;
 	struct sock *sk;

 	/* Open UDP socket */
 	err = udp_sock_create(net, &cfg->udp_config, &sock);
 	if (err < 0)
 		goto error;

 	/* Allocate FOU port structure */
 	fou = kzalloc(sizeof(*fou), GFP_KERNEL);
 	if (!fou) {
 		err = -ENOMEM;
 		goto error;
 	}

 	sk = sock->sk;

 	fou->port = cfg->udp_config.local_udp_port;

 	/* Initial for fou type */
 	switch (cfg->type) {
 	case FOU_ENCAP_DIRECT:
 		err = fou_encap_init(sk, fou, cfg);
 		if (err)
 			goto error;
 		break;
 	case FOU_ENCAP_GUE:
 		err = gue_encap_init(sk, fou, cfg);
 		if (err)
 			goto error;
 		break;
 	default:
 		err = -EINVAL;
 		goto error;
 	}

 	udp_sk(sk)->encap_type = 1;
 	udp_encap_enable();

 	sk->sk_user_data = fou;
 	fou->sock = sock;

 	udp_set_convert_csum(sk, true);

 	sk->sk_allocation = GFP_ATOMIC;

 	if (cfg->udp_config.family == AF_INET) {
 		err = udp_add_offload(&fou->udp_offloads);
 		if (err)
 			goto error;
 	}

 	err = fou_add_to_port_list(fou);
 	if (err)
 		goto error;

 	if (sockp)
 		*sockp = sock;

 	return 0;

 error:
 	kfree(fou);
 	if (sock)
 		sock_release(sock);

 	return err;
 }

 static int fou_destroy(struct net *net, struct fou_cfg *cfg)
 {
 	struct fou *fou;
 	u16 port = cfg->udp_config.local_udp_port;
 	int err = -EINVAL;

 	spin_lock(&fou_lock);
 	list_for_each_entry(fou, &fou_list, list) {
 		if (fou->port == port) {
 			udp_del_offload(&fou->udp_offloads);
 			fou_release(fou);
 			err = 0;
 			break;
 		}
 	}
 	spin_unlock(&fou_lock);

 	return err;
 }

 static struct genl_family fou_nl_family = {
 	.id		= GENL_ID_GENERATE,
 	.hdrsize	= 0,
 	.name		= FOU_GENL_NAME,
 	.version	= FOU_GENL_VERSION,
 	.maxattr	= FOU_ATTR_MAX,
 	.netnsok	= true,
 };

 static struct nla_policy fou_nl_policy[FOU_ATTR_MAX + 1] = {
 	[FOU_ATTR_PORT] = { .type = NLA_U16, },
 	[FOU_ATTR_AF] = { .type = NLA_U8, },
 	[FOU_ATTR_IPPROTO] = { .type = NLA_U8, },
 	[FOU_ATTR_TYPE] = { .type = NLA_U8, },
 };

 static int parse_nl_config(struct genl_info *info,
 			   struct fou_cfg *cfg)
 {
 	memset(cfg, 0, sizeof(*cfg));

 	cfg->udp_config.family = AF_INET;

 	if (info->attrs[FOU_ATTR_AF]) {
 		u8 family = nla_get_u8(info->attrs[FOU_ATTR_AF]);

 		if (family != AF_INET && family != AF_INET6)
 			return -EINVAL;

 		cfg->udp_config.family = family;
 	}

 	if (info->attrs[FOU_ATTR_PORT]) {
 		u16 port = nla_get_u16(info->attrs[FOU_ATTR_PORT]);

 		cfg->udp_config.local_udp_port = port;
 	}

 	if (info->attrs[FOU_ATTR_IPPROTO])
 		cfg->protocol = nla_get_u8(info->attrs[FOU_ATTR_IPPROTO]);

 	if (info->attrs[FOU_ATTR_TYPE])
 		cfg->type = nla_get_u8(info->attrs[FOU_ATTR_TYPE]);

 	return 0;
 }

 static int fou_nl_cmd_add_port(struct sk_buff *skb, struct genl_info *info)
 {
 	struct fou_cfg cfg;
 	int err;

 	err = parse_nl_config(info, &cfg);
 	if (err)
 		return err;

 	return fou_create(&init_net, &cfg, NULL);
 }

 static int fou_nl_cmd_rm_port(struct sk_buff *skb, struct genl_info *info)
 {
 	struct fou_cfg cfg;

 	parse_nl_config(info, &cfg);

 	return fou_destroy(&init_net, &cfg);
 }

 static const struct genl_ops fou_nl_ops[] = {
 	{
 		.cmd = FOU_CMD_ADD,
 		.doit = fou_nl_cmd_add_port,
 		.policy = fou_nl_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
 	{
 		.cmd = FOU_CMD_DEL,
 		.doit = fou_nl_cmd_rm_port,
 		.policy = fou_nl_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
 };

 size_t fou_encap_hlen(struct ip_tunnel_encap *e)
 {
 	return sizeof(struct udphdr);
 }
 EXPORT_SYMBOL(fou_encap_hlen);

 size_t gue_encap_hlen(struct ip_tunnel_encap *e)
 {
 	size_t len;
 	bool need_priv = false;

 	len = sizeof(struct udphdr) + sizeof(struct guehdr);

 	if (e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) {
 		len += GUE_PLEN_REMCSUM;
 		need_priv = true;
 	}

 	len += need_priv ? GUE_LEN_PRIV : 0;

 	return len;
 }
 EXPORT_SYMBOL(gue_encap_hlen);

 static void fou_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,
 			  struct flowi4 *fl4, u8 *protocol, __be16 sport)
 {
 	struct udphdr *uh;

 	skb_push(skb, sizeof(struct udphdr));
 	skb_reset_transport_header(skb);

 	uh = udp_hdr(skb);

 	uh->dest = e->dport;
 	uh->source = sport;
 	uh->len = htons(skb->len);
 	uh->check = 0;
 	udp_set_csum(!(e->flags & TUNNEL_ENCAP_FLAG_CSUM), skb,
 		     fl4->saddr, fl4->daddr, skb->len);

 	*protocol = IPPROTO_UDP;
 }

 int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 		     u8 *protocol, struct flowi4 *fl4)
 {
 	bool csum = !!(e->flags & TUNNEL_ENCAP_FLAG_CSUM);
 	int type = csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
 	__be16 sport;

 	skb = iptunnel_handle_offloads(skb, csum, type);

 	if (IS_ERR(skb))
 		return PTR_ERR(skb);

 	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
 					       skb, 0, 0, false);
 	fou_build_udp(skb, e, fl4, protocol, sport);

 	return 0;
 }
 EXPORT_SYMBOL(fou_build_header);

 int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 		     u8 *protocol, struct flowi4 *fl4)
 {
 	bool csum = !!(e->flags & TUNNEL_ENCAP_FLAG_CSUM);
 	int type = csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
 	struct guehdr *guehdr;
 	size_t hdrlen, optlen = 0;
 	__be16 sport;
 	void *data;
 	bool need_priv = false;

 	if ((e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) &&
 	    skb->ip_summed == CHECKSUM_PARTIAL) {
 		csum = false;
 		optlen += GUE_PLEN_REMCSUM;
 		type |= SKB_GSO_TUNNEL_REMCSUM;
 		need_priv = true;
 	}

 	optlen += need_priv ? GUE_LEN_PRIV : 0;

 	skb = iptunnel_handle_offloads(skb, csum, type);

 	if (IS_ERR(skb))
 		return PTR_ERR(skb);

 	/* Get source port (based on flow hash) before skb_push */
 	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
 					       skb, 0, 0, false);

 	hdrlen = sizeof(struct guehdr) + optlen;

 	skb_push(skb, hdrlen);

 	guehdr = (struct guehdr *)skb->data;

 	guehdr->control = 0;
 	guehdr->version = 0;
 	guehdr->hlen = optlen >> 2;
 	guehdr->flags = 0;
 	guehdr->proto_ctype = *protocol;

 	data = &guehdr[1];

 	if (need_priv) {
 		__be32 *flags = data;

 		guehdr->flags |= GUE_FLAG_PRIV;
 		*flags = 0;
 		data += GUE_LEN_PRIV;

 		if (type & SKB_GSO_TUNNEL_REMCSUM) {
 			u16 csum_start = skb_checksum_start_offset(skb);
 			__be16 *pd = data;

 			if (csum_start < hdrlen)
 				return -EINVAL;

 			csum_start -= hdrlen;
 			pd[0] = htons(csum_start);
 			pd[1] = htons(csum_start + skb->csum_offset);

 			if (!skb_is_gso(skb)) {
 				skb->ip_summed = CHECKSUM_NONE;
 				skb->encapsulation = 0;
 			}

 			*flags |= GUE_PFLAG_REMCSUM;
 			data += GUE_PLEN_REMCSUM;
 		}

 	}

 	fou_build_udp(skb, e, fl4, protocol, sport);

 	return 0;
 }
 EXPORT_SYMBOL(gue_build_header);

 #ifdef CONFIG_NET_FOU_IP_TUNNELS

 static const struct ip_tunnel_encap_ops __read_mostly fou_iptun_ops = {
 	.encap_hlen = fou_encap_hlen,
 	.build_header = fou_build_header,
 };

 static const struct ip_tunnel_encap_ops __read_mostly gue_iptun_ops = {
 	.encap_hlen = gue_encap_hlen,
 	.build_header = gue_build_header,
 };

 static int ip_tunnel_encap_add_fou_ops(void)
 {
 	int ret;

 	ret = ip_tunnel_encap_add_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
 	if (ret < 0) {
 		pr_err("can't add fou ops\n");
 		return ret;
 	}

 	ret = ip_tunnel_encap_add_ops(&gue_iptun_ops, TUNNEL_ENCAP_GUE);
 	if (ret < 0) {
 		pr_err("can't add gue ops\n");
 		ip_tunnel_encap_del_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
 		return ret;
 	}

 	return 0;
 }

 static void ip_tunnel_encap_del_fou_ops(void)
 {
 	ip_tunnel_encap_del_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
 	ip_tunnel_encap_del_ops(&gue_iptun_ops, TUNNEL_ENCAP_GUE);
 }

 #else

 static int ip_tunnel_encap_add_fou_ops(void)
 {
 	return 0;
 }

 static void ip_tunnel_encap_del_fou_ops(void)
 {
 }

 #endif

 static int __init fou_init(void)
 {
 	int ret;

 	ret = genl_register_family_with_ops(&fou_nl_family,
 					    fou_nl_ops);

 	if (ret < 0)
 		goto exit;

 	ret = ip_tunnel_encap_add_fou_ops();
 	if (ret < 0)
 		genl_unregister_family(&fou_nl_family);

 exit:
 	return ret;
 }

 static void __exit fou_fini(void)
 {
 	struct fou *fou, *next;

 	ip_tunnel_encap_del_fou_ops();

 	genl_unregister_family(&fou_nl_family);

 	/* Close all the FOU sockets */

 	spin_lock(&fou_lock);
 	list_for_each_entry_safe(fou, next, &fou_list, list)
 		fou_release(fou);
 	spin_unlock(&fou_lock);
 }

 module_init(fou_init);
 module_exit(fou_fini);
 MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
 MODULE_LICENSE("GPL");
	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/socket.h>
	#include <linux/skbuff.h>
	#include <linux/ip.h>
	#include <linux/udp.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <net/genetlink.h>
	#include <net/gue.h>
	#include <net/ip.h>
	#include <net/protocol.h>
	#include <net/udp.h>
	#include <net/udp_tunnel.h>
	#include <net/xfrm.h>
	#include <uapi/linux/fou.h>
	#include <uapi/linux/genetlink.h>

	static DEFINE_SPINLOCK(fou_lock);
	static LIST_HEAD(fou_list);

	struct fou {
	struct socket *sock;
	u8 protocol;
	u16 port;
	struct udp_offload udp_offloads;
	struct list_head list;
	};

	struct fou_cfg {
	u16 type;
	u8 protocol;
	struct udp_port_cfg udp_config;
	};

	static inline struct fou fou_from_sock(struct sock sk)
	{
	return sk->sk_user_data;
	}

	static void fou_recv_pull(struct sk_buff *skb, size_t len)
	{
	struct iphdr *iph = ip_hdr(skb);

	/* Remove 'len' bytes from the packet (UDP header and
	* FOU header if present).
	*/
	iph->tot_len = htons(ntohs(iph->tot_len) - len);
	__skb_pull(skb, len);
	skb_postpull_rcsum(skb, udp_hdr(skb), len);
	skb_reset_transport_header(skb);
	}

	static int fou_udp_recv(struct sock sk, struct sk_buff skb)
	{
	struct fou *fou = fou_from_sock(sk);

	if (!fou)
	return 1;

	fou_recv_pull(skb, sizeof(struct udphdr));

	return -fou->protocol;
	}

	static struct guehdr gue_remcsum(struct sk_buff skb, struct guehdr *guehdr,
	void *data, size_t hdrlen, u8 ipproto)
	{
	__be16 *pd = data;
	size_t start = ntohs(pd[0]);
	size_t offset = ntohs(pd[1]);
	size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
	__wsum delta;

	if (skb->remcsum_offload) {
	/* Already processed in GRO path */
	skb->remcsum_offload = 0;
	return guehdr;
	}

	if (!pskb_may_pull(skb, plen))
	return NULL;
	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

	if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
	__skb_checksum_complete(skb);

	delta = remcsum_adjust((void *)guehdr + hdrlen,
	skb->csum, start, offset);

	/* Adjust skb->csum since we changed the packet */
	skb->csum = csum_add(skb->csum, delta);

	return guehdr;
	}

	static int gue_control_message(struct sk_buff skb, struct guehdr guehdr)
	{
	/* No support yet */
	kfree_skb(skb);
	return 0;
	}

	static int gue_udp_recv(struct sock sk, struct sk_buff skb)
	{
	struct fou *fou = fou_from_sock(sk);
	size_t len, optlen, hdrlen;
	struct guehdr *guehdr;
	void *data;
	u16 doffset = 0;

	if (!fou)
	return 1;

	len = sizeof(struct udphdr) + sizeof(struct guehdr);
	if (!pskb_may_pull(skb, len))
	goto drop;

	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

	optlen = guehdr->hlen << 2;
	len += optlen;

	if (!pskb_may_pull(skb, len))
	goto drop;

	/* guehdr may change after pull */
	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

	hdrlen = sizeof(struct guehdr) + optlen;

	if (guehdr->version != 0 \|\| validate_gue_flags(guehdr, optlen))
	goto drop;

	hdrlen = sizeof(struct guehdr) + optlen;

	ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(skb)->tot_len) - len);

	/* Pull csum through the guehdr now . This can be used if
	* there is a remote checksum offload.
	*/
	skb_postpull_rcsum(skb, udp_hdr(skb), len);

	data = &guehdr[1];

	if (guehdr->flags & GUE_FLAG_PRIV) {
	__be32 flags = (__be32 )(data + doffset);

	doffset += GUE_LEN_PRIV;

	if (flags & GUE_PFLAG_REMCSUM) {
	guehdr = gue_remcsum(skb, guehdr, data + doffset,
	hdrlen, guehdr->proto_ctype);
	if (!guehdr)
	goto drop;

	data = &guehdr[1];

	doffset += GUE_PLEN_REMCSUM;
	}
	}

	if (unlikely(guehdr->control))
	return gue_control_message(skb, guehdr);

	__skb_pull(skb, sizeof(struct udphdr) + hdrlen);
	skb_reset_transport_header(skb);

	return -guehdr->proto_ctype;

	drop:
	kfree_skb(skb);
	return 0;
	}

	static struct sk_buff fou_gro_receive(struct sk_buff head,
	struct sk_buff *skb)
	{
	const struct net_offload *ops;
	struct sk_buff **pp = NULL;
	u8 proto = NAPI_GRO_CB(skb)->proto;
	const struct net_offload **offloads;

	rcu_read_lock();
	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
	ops = rcu_dereference(offloads[proto]);
	if (!ops \|\| !ops->callbacks.gro_receive)
	goto out_unlock;

	pp = ops->callbacks.gro_receive(head, skb);

	out_unlock:
	rcu_read_unlock();

	return pp;
	}

	static int fou_gro_complete(struct sk_buff *skb, int nhoff)
	{
	const struct net_offload *ops;
	u8 proto = NAPI_GRO_CB(skb)->proto;
	int err = -ENOSYS;
	const struct net_offload **offloads;

	udp_tunnel_gro_complete(skb, nhoff);

	rcu_read_lock();
	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
	ops = rcu_dereference(offloads[proto]);
	if (WARN_ON(!ops \|\| !ops->callbacks.gro_complete))
	goto out_unlock;

	err = ops->callbacks.gro_complete(skb, nhoff);

	out_unlock:
	rcu_read_unlock();

	return err;
	}

	static struct guehdr gue_gro_remcsum(struct sk_buff skb, unsigned int off,
	struct guehdr guehdr, void data,
	size_t hdrlen, u8 ipproto)
	{
	__be16 *pd = data;
	size_t start = ntohs(pd[0]);
	size_t offset = ntohs(pd[1]);
	size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
	__wsum delta;

	if (skb->remcsum_offload)
	return guehdr;

	if (!NAPI_GRO_CB(skb)->csum_valid)
	return NULL;

	/* Pull checksum that will be written */
	if (skb_gro_header_hard(skb, off + plen)) {
	guehdr = skb_gro_header_slow(skb, off + plen, off);
	if (!guehdr)
	return NULL;
	}

	delta = remcsum_adjust((void *)guehdr + hdrlen,
	NAPI_GRO_CB(skb)->csum, start, offset);

	/* Adjust skb->csum since we changed the packet */
	skb->csum = csum_add(skb->csum, delta);
	NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);

	skb->remcsum_offload = 1;

	return guehdr;
	}

	static struct sk_buff gue_gro_receive(struct sk_buff head,
	struct sk_buff *skb)
	{
	const struct net_offload **offloads;
	const struct net_offload *ops;
	struct sk_buff **pp = NULL;
	struct sk_buff *p;
	struct guehdr *guehdr;
	size_t len, optlen, hdrlen, off;
	void *data;
	u16 doffset = 0;
	int flush = 1;

	off = skb_gro_offset(skb);
	len = off + sizeof(*guehdr);

	guehdr = skb_gro_header_fast(skb, off);
	if (skb_gro_header_hard(skb, len)) {
	guehdr = skb_gro_header_slow(skb, len, off);
	if (unlikely(!guehdr))
	goto out;
	}

	optlen = guehdr->hlen << 2;
	len += optlen;

	if (skb_gro_header_hard(skb, len)) {
	guehdr = skb_gro_header_slow(skb, len, off);
	if (unlikely(!guehdr))
	goto out;
	}

	if (unlikely(guehdr->control) \|\| guehdr->version != 0 \|\|
	validate_gue_flags(guehdr, optlen))
	goto out;

	hdrlen = sizeof(*guehdr) + optlen;

	/* Adjust NAPI_GRO_CB(skb)->csum to account for guehdr,
	* this is needed if there is a remote checkcsum offload.
	*/
	skb_gro_postpull_rcsum(skb, guehdr, hdrlen);

	data = &guehdr[1];

	if (guehdr->flags & GUE_FLAG_PRIV) {
	__be32 flags = (__be32 )(data + doffset);

	doffset += GUE_LEN_PRIV;

	if (flags & GUE_PFLAG_REMCSUM) {
	guehdr = gue_gro_remcsum(skb, off, guehdr,
	data + doffset, hdrlen,
	guehdr->proto_ctype);
	if (!guehdr)
	goto out;

	data = &guehdr[1];

	doffset += GUE_PLEN_REMCSUM;
	}
	}

	skb_gro_pull(skb, hdrlen);

	flush = 0;

	for (p = *head; p; p = p->next) {
	const struct guehdr *guehdr2;

	if (!NAPI_GRO_CB(p)->same_flow)
	continue;

	guehdr2 = (struct guehdr *)(p->data + off);

	/* Compare base GUE header to be equal (covers
	* hlen, version, proto_ctype, and flags.
	*/
	if (guehdr->word != guehdr2->word) {
	NAPI_GRO_CB(p)->same_flow = 0;
	continue;
	}

	/* Compare optional fields are the same. */
	if (guehdr->hlen && memcmp(&guehdr[1], &guehdr2[1],
	guehdr->hlen << 2)) {
	NAPI_GRO_CB(p)->same_flow = 0;
	continue;
	}
	}

	rcu_read_lock();
	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
	ops = rcu_dereference(offloads[guehdr->proto_ctype]);
	if (WARN_ON(!ops \|\| !ops->callbacks.gro_receive))
	goto out_unlock;

	pp = ops->callbacks.gro_receive(head, skb);

	out_unlock:
	rcu_read_unlock();
	out:
	NAPI_GRO_CB(skb)->flush \|= flush;

	return pp;
	}

	static int gue_gro_complete(struct sk_buff *skb, int nhoff)
	{
	const struct net_offload **offloads;
	struct guehdr guehdr = (struct guehdr )(skb->data + nhoff);
	const struct net_offload *ops;
	unsigned int guehlen;
	u8 proto;
	int err = -ENOENT;

	proto = guehdr->proto_ctype;

	guehlen = sizeof(*guehdr) + (guehdr->hlen << 2);

	rcu_read_lock();
	offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
	ops = rcu_dereference(offloads[proto]);
	if (WARN_ON(!ops \|\| !ops->callbacks.gro_complete))
	goto out_unlock;

	err = ops->callbacks.gro_complete(skb, nhoff + guehlen);

	out_unlock:
	rcu_read_unlock();
	return err;
	}

	static int fou_add_to_port_list(struct fou *fou)
	{
	struct fou *fout;

	spin_lock(&fou_lock);
	list_for_each_entry(fout, &fou_list, list) {
	if (fou->port == fout->port) {
	spin_unlock(&fou_lock);
	return -EALREADY;
	}
	}

	list_add(&fou->list, &fou_list);
	spin_unlock(&fou_lock);

	return 0;
	}

	static void fou_release(struct fou *fou)
	{
	struct socket *sock = fou->sock;
	struct sock *sk = sock->sk;

	udp_del_offload(&fou->udp_offloads);

	list_del(&fou->list);

	/* Remove hooks into tunnel socket */
	sk->sk_user_data = NULL;

	sock_release(sock);

	kfree(fou);
	}

	static int fou_encap_init(struct sock sk, struct fou fou, struct fou_cfg *cfg)
	{
	udp_sk(sk)->encap_rcv = fou_udp_recv;
	fou->protocol = cfg->protocol;
	fou->udp_offloads.callbacks.gro_receive = fou_gro_receive;
	fou->udp_offloads.callbacks.gro_complete = fou_gro_complete;
	fou->udp_offloads.port = cfg->udp_config.local_udp_port;
	fou->udp_offloads.ipproto = cfg->protocol;

	return 0;
	}

	static int gue_encap_init(struct sock sk, struct fou fou, struct fou_cfg *cfg)
	{
	udp_sk(sk)->encap_rcv = gue_udp_recv;
	fou->udp_offloads.callbacks.gro_receive = gue_gro_receive;
	fou->udp_offloads.callbacks.gro_complete = gue_gro_complete;
	fou->udp_offloads.port = cfg->udp_config.local_udp_port;

	return 0;
	}

	static int fou_create(struct net net, struct fou_cfg cfg,
	struct socket **sockp)
	{
	struct fou *fou = NULL;
	int err;
	struct socket *sock = NULL;
	struct sock *sk;

	/* Open UDP socket */
	err = udp_sock_create(net, &cfg->udp_config, &sock);
	if (err < 0)
	goto error;

	/* Allocate FOU port structure */
	fou = kzalloc(sizeof(*fou), GFP_KERNEL);
	if (!fou) {
	err = -ENOMEM;
	goto error;
	}

	sk = sock->sk;

	fou->port = cfg->udp_config.local_udp_port;

	/* Initial for fou type */
	switch (cfg->type) {
	case FOU_ENCAP_DIRECT:
	err = fou_encap_init(sk, fou, cfg);
	if (err)
	goto error;
	break;
	case FOU_ENCAP_GUE:
	err = gue_encap_init(sk, fou, cfg);
	if (err)
	goto error;
	break;
	default:
	err = -EINVAL;
	goto error;
	}

	udp_sk(sk)->encap_type = 1;
	udp_encap_enable();

	sk->sk_user_data = fou;
	fou->sock = sock;

	udp_set_convert_csum(sk, true);

	sk->sk_allocation = GFP_ATOMIC;

	if (cfg->udp_config.family == AF_INET) {
	err = udp_add_offload(&fou->udp_offloads);
	if (err)
	goto error;
	}

	err = fou_add_to_port_list(fou);
	if (err)
	goto error;

	if (sockp)
	*sockp = sock;

	return 0;

	error:
	kfree(fou);
	if (sock)
	sock_release(sock);

	return err;
	}

	static int fou_destroy(struct net net, struct fou_cfg cfg)
	{
	struct fou *fou;
	u16 port = cfg->udp_config.local_udp_port;
	int err = -EINVAL;

	spin_lock(&fou_lock);
	list_for_each_entry(fou, &fou_list, list) {
	if (fou->port == port) {
	udp_del_offload(&fou->udp_offloads);
	fou_release(fou);
	err = 0;
	break;
	}
	}
	spin_unlock(&fou_lock);

	return err;
	}

	static struct genl_family fou_nl_family = {
	.id = GENL_ID_GENERATE,
	.hdrsize = 0,
	.name = FOU_GENL_NAME,
	.version = FOU_GENL_VERSION,
	.maxattr = FOU_ATTR_MAX,
	.netnsok = true,
	};

	static struct nla_policy fou_nl_policy[FOU_ATTR_MAX + 1] = {
	[FOU_ATTR_PORT] = { .type = NLA_U16, },
	[FOU_ATTR_AF] = { .type = NLA_U8, },
	[FOU_ATTR_IPPROTO] = { .type = NLA_U8, },
	[FOU_ATTR_TYPE] = { .type = NLA_U8, },
	};

	static int parse_nl_config(struct genl_info *info,
	struct fou_cfg *cfg)
	{
	memset(cfg, 0, sizeof(*cfg));

	cfg->udp_config.family = AF_INET;

	if (info->attrs[FOU_ATTR_AF]) {
	u8 family = nla_get_u8(info->attrs[FOU_ATTR_AF]);

	if (family != AF_INET && family != AF_INET6)
	return -EINVAL;

	cfg->udp_config.family = family;
	}

	if (info->attrs[FOU_ATTR_PORT]) {
	u16 port = nla_get_u16(info->attrs[FOU_ATTR_PORT]);

	cfg->udp_config.local_udp_port = port;
	}

	if (info->attrs[FOU_ATTR_IPPROTO])
	cfg->protocol = nla_get_u8(info->attrs[FOU_ATTR_IPPROTO]);

	if (info->attrs[FOU_ATTR_TYPE])
	cfg->type = nla_get_u8(info->attrs[FOU_ATTR_TYPE]);

	return 0;
	}

	static int fou_nl_cmd_add_port(struct sk_buff skb, struct genl_info info)
	{
	struct fou_cfg cfg;
	int err;

	err = parse_nl_config(info, &cfg);
	if (err)
	return err;

	return fou_create(&init_net, &cfg, NULL);
	}

	static int fou_nl_cmd_rm_port(struct sk_buff skb, struct genl_info info)
	{
	struct fou_cfg cfg;

	parse_nl_config(info, &cfg);

	return fou_destroy(&init_net, &cfg);
	}

	static const struct genl_ops fou_nl_ops[] = {
	{
	.cmd = FOU_CMD_ADD,
	.doit = fou_nl_cmd_add_port,
	.policy = fou_nl_policy,
	.flags = GENL_ADMIN_PERM,
	},
	{
	.cmd = FOU_CMD_DEL,
	.doit = fou_nl_cmd_rm_port,
	.policy = fou_nl_policy,
	.flags = GENL_ADMIN_PERM,
	},
	};

	size_t fou_encap_hlen(struct ip_tunnel_encap *e)
	{
	return sizeof(struct udphdr);
	}
	EXPORT_SYMBOL(fou_encap_hlen);

	size_t gue_encap_hlen(struct ip_tunnel_encap *e)
	{
	size_t len;
	bool need_priv = false;

	len = sizeof(struct udphdr) + sizeof(struct guehdr);

	if (e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) {
	len += GUE_PLEN_REMCSUM;
	need_priv = true;
	}

	len += need_priv ? GUE_LEN_PRIV : 0;

	return len;
	}
	EXPORT_SYMBOL(gue_encap_hlen);

	static void fou_build_udp(struct sk_buff skb, struct ip_tunnel_encap e,
	struct flowi4 fl4, u8 protocol, __be16 sport)
	{
	struct udphdr *uh;

	skb_push(skb, sizeof(struct udphdr));
	skb_reset_transport_header(skb);

	uh = udp_hdr(skb);

	uh->dest = e->dport;
	uh->source = sport;
	uh->len = htons(skb->len);
	uh->check = 0;
	udp_set_csum(!(e->flags & TUNNEL_ENCAP_FLAG_CSUM), skb,
	fl4->saddr, fl4->daddr, skb->len);

	*protocol = IPPROTO_UDP;
	}

	int fou_build_header(struct sk_buff skb, struct ip_tunnel_encap e,
	u8 protocol, struct flowi4 fl4)
	{
	bool csum = !!(e->flags & TUNNEL_ENCAP_FLAG_CSUM);
	int type = csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
	__be16 sport;

	skb = iptunnel_handle_offloads(skb, csum, type);

	if (IS_ERR(skb))
	return PTR_ERR(skb);

	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
	skb, 0, 0, false);
	fou_build_udp(skb, e, fl4, protocol, sport);

	return 0;
	}
	EXPORT_SYMBOL(fou_build_header);

	int gue_build_header(struct sk_buff skb, struct ip_tunnel_encap e,
	u8 protocol, struct flowi4 fl4)
	{
	bool csum = !!(e->flags & TUNNEL_ENCAP_FLAG_CSUM);
	int type = csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
	struct guehdr *guehdr;
	size_t hdrlen, optlen = 0;
	__be16 sport;
	void *data;
	bool need_priv = false;

	if ((e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) &&
	skb->ip_summed == CHECKSUM_PARTIAL) {
	csum = false;
	optlen += GUE_PLEN_REMCSUM;
	type \|= SKB_GSO_TUNNEL_REMCSUM;
	need_priv = true;
	}

	optlen += need_priv ? GUE_LEN_PRIV : 0;

	skb = iptunnel_handle_offloads(skb, csum, type);

	if (IS_ERR(skb))
	return PTR_ERR(skb);

	/* Get source port (based on flow hash) before skb_push */
	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
	skb, 0, 0, false);

	hdrlen = sizeof(struct guehdr) + optlen;

	skb_push(skb, hdrlen);

	guehdr = (struct guehdr *)skb->data;

	guehdr->control = 0;
	guehdr->version = 0;
	guehdr->hlen = optlen >> 2;
	guehdr->flags = 0;
	guehdr->proto_ctype = *protocol;

	data = &guehdr[1];

	if (need_priv) {
	__be32 *flags = data;

	guehdr->flags \|= GUE_FLAG_PRIV;
	*flags = 0;
	data += GUE_LEN_PRIV;

	if (type & SKB_GSO_TUNNEL_REMCSUM) {
	u16 csum_start = skb_checksum_start_offset(skb);
	__be16 *pd = data;

	if (csum_start < hdrlen)
	return -EINVAL;

	csum_start -= hdrlen;
	pd[0] = htons(csum_start);
	pd[1] = htons(csum_start + skb->csum_offset);

	if (!skb_is_gso(skb)) {
	skb->ip_summed = CHECKSUM_NONE;
	skb->encapsulation = 0;
	}

	*flags \|= GUE_PFLAG_REMCSUM;
	data += GUE_PLEN_REMCSUM;
	}

	}

	fou_build_udp(skb, e, fl4, protocol, sport);

	return 0;
	}
	EXPORT_SYMBOL(gue_build_header);

	#ifdef CONFIG_NET_FOU_IP_TUNNELS

	static const struct ip_tunnel_encap_ops __read_mostly fou_iptun_ops = {
	.encap_hlen = fou_encap_hlen,
	.build_header = fou_build_header,
	};

	static const struct ip_tunnel_encap_ops __read_mostly gue_iptun_ops = {
	.encap_hlen = gue_encap_hlen,
	.build_header = gue_build_header,
	};

	static int ip_tunnel_encap_add_fou_ops(void)
	{
	int ret;

	ret = ip_tunnel_encap_add_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
	if (ret < 0) {
	pr_err("can't add fou ops\n");
	return ret;
	}

	ret = ip_tunnel_encap_add_ops(&gue_iptun_ops, TUNNEL_ENCAP_GUE);
	if (ret < 0) {
	pr_err("can't add gue ops\n");
	ip_tunnel_encap_del_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
	return ret;
	}

	return 0;
	}

	static void ip_tunnel_encap_del_fou_ops(void)
	{
	ip_tunnel_encap_del_ops(&fou_iptun_ops, TUNNEL_ENCAP_FOU);
	ip_tunnel_encap_del_ops(&gue_iptun_ops, TUNNEL_ENCAP_GUE);
	}

	#else

	static int ip_tunnel_encap_add_fou_ops(void)
	{
	return 0;
	}

	static void ip_tunnel_encap_del_fou_ops(void)
	{
	}

	#endif

	static int __init fou_init(void)
	{
	int ret;

	ret = genl_register_family_with_ops(&fou_nl_family,
	fou_nl_ops);

	if (ret < 0)
	goto exit;

	ret = ip_tunnel_encap_add_fou_ops();
	if (ret < 0)
	genl_unregister_family(&fou_nl_family);

	exit:
	return ret;
	}

	static void __exit fou_fini(void)
	{
	struct fou fou, next;

	ip_tunnel_encap_del_fou_ops();

	genl_unregister_family(&fou_nl_family);

	/* Close all the FOU sockets */

	spin_lock(&fou_lock);
	list_for_each_entry_safe(fou, next, &fou_list, list)
	fou_release(fou);
	spin_unlock(&fou_lock);
	}

	module_init(fou_init);
	module_exit(fou_fini);
	MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
	MODULE_LICENSE("GPL");