diff --git a/include/net/espintcp.h b/include/net/espintcp.h
new file mode 100644
index 000000000000..02fc28c82d30
--- /dev/null
+++ b/include/net/espintcp.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NET_ESPINTCP_H
+#define _NET_ESPINTCP_H
+
+#include <net/strparser.h>
+#include <linux/skmsg.h>
+
+void __init espintcp_init(void);
+
+int espintcp_push_skb(struct sock *sk, struct sk_buff *skb);
+int espintcp_queue_out(struct sock *sk, struct sk_buff *skb);
+bool tcp_is_ulp_esp(struct sock *sk);
+
+struct espintcp_msg {
+	struct sk_buff *skb;
+	struct sk_msg skmsg;
+	int offset;
+	int len;
+};
+
+struct espintcp_ctx {
+	struct strparser strp;
+	struct sk_buff_head ike_queue;
+	struct sk_buff_head out_queue;
+	struct espintcp_msg partial;
+	void (*saved_data_ready)(struct sock *sk);
+	void (*saved_write_space)(struct sock *sk);
+	struct work_struct work;
+	bool tx_running;
+};
+
+static inline struct espintcp_ctx *espintcp_getctx(const struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	return icsk->icsk_ulp_data;
+}
+#endif
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index a0199f8251ec..e49b5fe8a66b 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -193,6 +193,7 @@ struct xfrm_state {
 
 	/* Data for encapsulator */
 	struct xfrm_encap_tmpl	*encap;
+	struct sock __rcu	*encap_sk;
 
 	/* Data for care-of address */
 	xfrm_address_t	*coaddr;
diff --git a/include/uapi/linux/udp.h b/include/uapi/linux/udp.h
index 30baccb6c9c4..4828794efcf8 100644
--- a/include/uapi/linux/udp.h
+++ b/include/uapi/linux/udp.h
@@ -42,5 +42,6 @@ struct udphdr {
 #define UDP_ENCAP_GTP0		4 /* GSM TS 09.60 */
 #define UDP_ENCAP_GTP1U		5 /* 3GPP TS 29.060 */
 #define UDP_ENCAP_RXRPC		6
+#define TCP_ENCAP_ESPINTCP	7 /* Yikes, this is really xfrm encap types. */
 
 #endif /* _UAPI_LINUX_UDP_H */
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 974de4d20f25..40bbeef4c62c 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -378,6 +378,17 @@ config INET_ESP_OFFLOAD
 
 	  If unsure, say N.
 
+config INET_ESPINTCP
+	bool "IP: ESP in TCP encapsulation (RFC 8229)"
+	depends on XFRM && INET_ESP
+	select STREAM_PARSER
+	select NET_SOCK_MSG
+	help
+	  Support for RFC 8229 encapsulation of ESP and IKE over
+	  TCP/IPv4 sockets.
+
+	  If unsure, say N.
+
 config INET_IPCOMP
 	tristate "IP: IPComp transformation"
 	select INET_XFRM_TUNNEL
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 033c61d27148..103c7d599a3c 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -18,6 +18,8 @@
 #include <net/icmp.h>
 #include <net/protocol.h>
 #include <net/udp.h>
+#include <net/tcp.h>
+#include <net/espintcp.h>
 
 #include <linux/highmem.h>
 
@@ -117,6 +119,132 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
 			put_page(sg_page(sg));
 }
 
+#ifdef CONFIG_INET_ESPINTCP
+struct esp_tcp_sk {
+	struct sock *sk;
+	struct rcu_head rcu;
+};
+
+static void esp_free_tcp_sk(struct rcu_head *head)
+{
+	struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
+
+	sock_put(esk->sk);
+	kfree(esk);
+}
+
+static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
+{
+	struct xfrm_encap_tmpl *encap = x->encap;
+	struct esp_tcp_sk *esk;
+	__be16 sport, dport;
+	struct sock *nsk;
+	struct sock *sk;
+
+	sk = rcu_dereference(x->encap_sk);
+	if (sk && sk->sk_state == TCP_ESTABLISHED)
+		return sk;
+
+	spin_lock_bh(&x->lock);
+	sport = encap->encap_sport;
+	dport = encap->encap_dport;
+	nsk = rcu_dereference_protected(x->encap_sk,
+					lockdep_is_held(&x->lock));
+	if (sk && sk == nsk) {
+		esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
+		if (!esk) {
+			spin_unlock_bh(&x->lock);
+			return ERR_PTR(-ENOMEM);
+		}
+		RCU_INIT_POINTER(x->encap_sk, NULL);
+		esk->sk = sk;
+		call_rcu(&esk->rcu, esp_free_tcp_sk);
+	}
+	spin_unlock_bh(&x->lock);
+
+	sk = inet_lookup_established(xs_net(x), &tcp_hashinfo, x->id.daddr.a4,
+				     dport, x->props.saddr.a4, sport, 0);
+	if (!sk)
+		return ERR_PTR(-ENOENT);
+
+	if (!tcp_is_ulp_esp(sk)) {
+		sock_put(sk);
+		return ERR_PTR(-EINVAL);
+	}
+
+	spin_lock_bh(&x->lock);
+	nsk = rcu_dereference_protected(x->encap_sk,
+					lockdep_is_held(&x->lock));
+	if (encap->encap_sport != sport ||
+	    encap->encap_dport != dport) {
+		sock_put(sk);
+		sk = nsk ?: ERR_PTR(-EREMCHG);
+	} else if (sk == nsk) {
+		sock_put(sk);
+	} else {
+		rcu_assign_pointer(x->encap_sk, sk);
+	}
+	spin_unlock_bh(&x->lock);
+
+	return sk;
+}
+
+static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct sock *sk;
+	int err;
+
+	rcu_read_lock();
+
+	sk = esp_find_tcp_sk(x);
+	err = PTR_ERR_OR_ZERO(sk);
+	if (err)
+		goto out;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk))
+		err = espintcp_queue_out(sk, skb);
+	else
+		err = espintcp_push_skb(sk, skb);
+	bh_unlock_sock(sk);
+
+out:
+	rcu_read_unlock();
+	return err;
+}
+
+static int esp_output_tcp_encap_cb(struct net *net, struct sock *sk,
+				   struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct xfrm_state *x = dst->xfrm;
+
+	return esp_output_tcp_finish(x, skb);
+}
+
+static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err;
+
+	local_bh_disable();
+	err = xfrm_trans_queue_net(xs_net(x), skb, esp_output_tcp_encap_cb);
+	local_bh_enable();
+
+	/* EINPROGRESS just happens to do the right thing.  It
+	 * actually means that the skb has been consumed and
+	 * isn't coming back.
+	 */
+	return err ?: -EINPROGRESS;
+}
+#else
+static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
+{
+	kfree_skb(skb);
+
+	return -EOPNOTSUPP;
+}
+#endif
+
 static void esp_output_done(struct crypto_async_request *base, int err)
 {
 	struct sk_buff *skb = base->data;
@@ -147,7 +275,11 @@ static void esp_output_done(struct crypto_async_request *base, int err)
 		secpath_reset(skb);
 		xfrm_dev_resume(skb);
 	} else {
-		xfrm_output_resume(skb, err);
+		if (!err &&
+		    x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
+			esp_output_tail_tcp(x, skb);
+		else
+			xfrm_output_resume(skb, err);
 	}
 }
 
@@ -236,7 +368,7 @@ static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
 	unsigned int len;
 
 	len = skb->len + esp->tailen - skb_transport_offset(skb);
-	if (len + sizeof(struct iphdr) >= IP_MAX_MTU)
+	if (len + sizeof(struct iphdr) > IP_MAX_MTU)
 		return ERR_PTR(-EMSGSIZE);
 
 	uh = (struct udphdr *)esp->esph;
@@ -256,6 +388,41 @@ static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
 	return (struct ip_esp_hdr *)(uh + 1);
 }
 
+#ifdef CONFIG_INET_ESPINTCP
+static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
+						    struct sk_buff *skb,
+						    struct esp_info *esp)
+{
+	__be16 *lenp = (void *)esp->esph;
+	struct ip_esp_hdr *esph;
+	unsigned int len;
+	struct sock *sk;
+
+	len = skb->len + esp->tailen - skb_transport_offset(skb);
+	if (len > IP_MAX_MTU)
+		return ERR_PTR(-EMSGSIZE);
+
+	rcu_read_lock();
+	sk = esp_find_tcp_sk(x);
+	rcu_read_unlock();
+
+	if (IS_ERR(sk))
+		return ERR_CAST(sk);
+
+	*lenp = htons(len);
+	esph = (struct ip_esp_hdr *)(lenp + 1);
+
+	return esph;
+}
+#else
+static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
+						    struct sk_buff *skb,
+						    struct esp_info *esp)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+#endif
+
 static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
 			    struct esp_info *esp)
 {
@@ -276,6 +443,9 @@ static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
 	case UDP_ENCAP_ESPINUDP_NON_IKE:
 		esph = esp_output_udp_encap(skb, encap_type, esp, sport, dport);
 		break;
+	case TCP_ENCAP_ESPINTCP:
+		esph = esp_output_tcp_encap(x, skb, esp);
+		break;
 	}
 
 	if (IS_ERR(esph))
@@ -296,7 +466,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
 	struct sk_buff *trailer;
 	int tailen = esp->tailen;
 
-	/* this is non-NULL only with UDP Encapsulation */
+	/* this is non-NULL only with TCP/UDP Encapsulation */
 	if (x->encap) {
 		int err = esp_output_encap(x, skb, esp);
 
@@ -491,6 +661,9 @@ int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
 	if (sg != dsg)
 		esp_ssg_unref(x, tmp);
 
+	if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
+		err = esp_output_tail_tcp(x, skb);
+
 error_free:
 	kfree(tmp);
 error:
@@ -617,10 +790,14 @@ int esp_input_done2(struct sk_buff *skb, int err)
 
 	if (x->encap) {
 		struct xfrm_encap_tmpl *encap = x->encap;
+		struct tcphdr *th = (void *)(skb_network_header(skb) + ihl);
 		struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
 		__be16 source;
 
 		switch (x->encap->encap_type) {
+		case TCP_ENCAP_ESPINTCP:
+			source = th->source;
+			break;
 		case UDP_ENCAP_ESPINUDP:
 		case UDP_ENCAP_ESPINUDP_NON_IKE:
 			source = uh->source;
@@ -1017,6 +1194,14 @@ static int esp_init_state(struct xfrm_state *x)
 		case UDP_ENCAP_ESPINUDP_NON_IKE:
 			x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
 			break;
+#ifdef CONFIG_INET_ESPINTCP
+		case TCP_ENCAP_ESPINTCP:
+			/* only the length field, TCP encap is done by
+			 * the socket
+			 */
+			x->props.header_len += 2;
+			break;
+#endif
 		}
 	}
 
diff --git a/net/xfrm/Makefile b/net/xfrm/Makefile
index fbc4552d17b8..212a4fcb4a88 100644
--- a/net/xfrm/Makefile
+++ b/net/xfrm/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_XFRM_ALGO) += xfrm_algo.o
 obj-$(CONFIG_XFRM_USER) += xfrm_user.o
 obj-$(CONFIG_XFRM_IPCOMP) += xfrm_ipcomp.o
 obj-$(CONFIG_XFRM_INTERFACE) += xfrm_interface.o
+obj-$(CONFIG_INET_ESPINTCP) += espintcp.o
diff --git a/net/xfrm/espintcp.c b/net/xfrm/espintcp.c
new file mode 100644
index 000000000000..1d561a00c4b0
--- /dev/null
+++ b/net/xfrm/espintcp.c
@@ -0,0 +1,505 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <net/tcp.h>
+#include <net/strparser.h>
+#include <net/xfrm.h>
+#include <net/esp.h>
+#include <net/espintcp.h>
+#include <linux/skmsg.h>
+#include <net/inet_common.h>
+
+static void handle_nonesp(struct espintcp_ctx *ctx, struct sk_buff *skb,
+			  struct sock *sk)
+{
+	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf ||
+	    !sk_rmem_schedule(sk, skb, skb->truesize)) {
+		kfree_skb(skb);
+		return;
+	}
+
+	skb_set_owner_r(skb, sk);
+
+	memset(skb->cb, 0, sizeof(skb->cb));
+	skb_queue_tail(&ctx->ike_queue, skb);
+	ctx->saved_data_ready(sk);
+}
+
+static void handle_esp(struct sk_buff *skb, struct sock *sk)
+{
+	skb_reset_transport_header(skb);
+	memset(skb->cb, 0, sizeof(skb->cb));
+
+	rcu_read_lock();
+	skb->dev = dev_get_by_index_rcu(sock_net(sk), skb->skb_iif);
+	local_bh_disable();
+	xfrm4_rcv_encap(skb, IPPROTO_ESP, 0, TCP_ENCAP_ESPINTCP);
+	local_bh_enable();
+	rcu_read_unlock();
+}
+
+static void espintcp_rcv(struct strparser *strp, struct sk_buff *skb)
+{
+	struct espintcp_ctx *ctx = container_of(strp, struct espintcp_ctx,
+						strp);
+	struct strp_msg *rxm = strp_msg(skb);
+	u32 nonesp_marker;
+	int err;
+
+	err = skb_copy_bits(skb, rxm->offset + 2, &nonesp_marker,
+			    sizeof(nonesp_marker));
+	if (err < 0) {
+		kfree_skb(skb);
+		return;
+	}
+
+	/* remove header, leave non-ESP marker/SPI */
+	if (!__pskb_pull(skb, rxm->offset + 2)) {
+		kfree_skb(skb);
+		return;
+	}
+
+	if (pskb_trim(skb, rxm->full_len - 2) != 0) {
+		kfree_skb(skb);
+		return;
+	}
+
+	if (nonesp_marker == 0)
+		handle_nonesp(ctx, skb, strp->sk);
+	else
+		handle_esp(skb, strp->sk);
+}
+
+static int espintcp_parse(struct strparser *strp, struct sk_buff *skb)
+{
+	struct strp_msg *rxm = strp_msg(skb);
+	__be16 blen;
+	u16 len;
+	int err;
+
+	if (skb->len < rxm->offset + 2)
+		return 0;
+
+	err = skb_copy_bits(skb, rxm->offset, &blen, sizeof(blen));
+	if (err < 0)
+		return err;
+
+	len = be16_to_cpu(blen);
+	if (len < 6)
+		return -EINVAL;
+
+	return len;
+}
+
+static int espintcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
+			    int nonblock, int flags, int *addr_len)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct sk_buff *skb;
+	int err = 0;
+	int copied;
+	int off = 0;
+
+	flags |= nonblock ? MSG_DONTWAIT : 0;
+
+	skb = __skb_recv_datagram(sk, &ctx->ike_queue, flags, NULL, &off, &err);
+	if (!skb)
+		return err;
+
+	copied = len;
+	if (copied > skb->len)
+		copied = skb->len;
+	else if (copied < skb->len)
+		msg->msg_flags |= MSG_TRUNC;
+
+	err = skb_copy_datagram_msg(skb, 0, msg, copied);
+	if (unlikely(err)) {
+		kfree_skb(skb);
+		return err;
+	}
+
+	if (flags & MSG_TRUNC)
+		copied = skb->len;
+	kfree_skb(skb);
+	return copied;
+}
+
+int espintcp_queue_out(struct sock *sk, struct sk_buff *skb)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+
+	if (skb_queue_len(&ctx->out_queue) >= netdev_max_backlog)
+		return -ENOBUFS;
+
+	__skb_queue_tail(&ctx->out_queue, skb);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(espintcp_queue_out);
+
+/* espintcp length field is 2B and length includes the length field's size */
+#define MAX_ESPINTCP_MSG (((1 << 16) - 1) - 2)
+
+static int espintcp_sendskb_locked(struct sock *sk, struct espintcp_msg *emsg,
+				   int flags)
+{
+	do {
+		int ret;
+
+		ret = skb_send_sock_locked(sk, emsg->skb,
+					   emsg->offset, emsg->len);
+		if (ret < 0)
+			return ret;
+
+		emsg->len -= ret;
+		emsg->offset += ret;
+	} while (emsg->len > 0);
+
+	kfree_skb(emsg->skb);
+	memset(emsg, 0, sizeof(*emsg));
+
+	return 0;
+}
+
+static int espintcp_sendskmsg_locked(struct sock *sk,
+				     struct espintcp_msg *emsg, int flags)
+{
+	struct sk_msg *skmsg = &emsg->skmsg;
+	struct scatterlist *sg;
+	int done = 0;
+	int ret;
+
+	flags |= MSG_SENDPAGE_NOTLAST;
+	sg = &skmsg->sg.data[skmsg->sg.start];
+	do {
+		size_t size = sg->length - emsg->offset;
+		int offset = sg->offset + emsg->offset;
+		struct page *p;
+
+		emsg->offset = 0;
+
+		if (sg_is_last(sg))
+			flags &= ~MSG_SENDPAGE_NOTLAST;
+
+		p = sg_page(sg);
+retry:
+		ret = do_tcp_sendpages(sk, p, offset, size, flags);
+		if (ret < 0) {
+			emsg->offset = offset - sg->offset;
+			skmsg->sg.start += done;
+			return ret;
+		}
+
+		if (ret != size) {
+			offset += ret;
+			size -= ret;
+			goto retry;
+		}
+
+		done++;
+		put_page(p);
+		sk_mem_uncharge(sk, sg->length);
+		sg = sg_next(sg);
+	} while (sg);
+
+	memset(emsg, 0, sizeof(*emsg));
+
+	return 0;
+}
+
+static int espintcp_push_msgs(struct sock *sk)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct espintcp_msg *emsg = &ctx->partial;
+	int err;
+
+	if (!emsg->len)
+		return 0;
+
+	if (ctx->tx_running)
+		return -EAGAIN;
+	ctx->tx_running = 1;
+
+	if (emsg->skb)
+		err = espintcp_sendskb_locked(sk, emsg, 0);
+	else
+		err = espintcp_sendskmsg_locked(sk, emsg, 0);
+	if (err == -EAGAIN) {
+		ctx->tx_running = 0;
+		return 0;
+	}
+	if (!err)
+		memset(emsg, 0, sizeof(*emsg));
+
+	ctx->tx_running = 0;
+
+	return err;
+}
+
+int espintcp_push_skb(struct sock *sk, struct sk_buff *skb)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct espintcp_msg *emsg = &ctx->partial;
+	unsigned int len;
+	int offset;
+
+	if (sk->sk_state != TCP_ESTABLISHED) {
+		kfree_skb(skb);
+		return -ECONNRESET;
+	}
+
+	offset = skb_transport_offset(skb);
+	len = skb->len - offset;
+
+	espintcp_push_msgs(sk);
+
+	if (emsg->len) {
+		kfree_skb(skb);
+		return -ENOBUFS;
+	}
+
+	skb_set_owner_w(skb, sk);
+
+	emsg->offset = offset;
+	emsg->len = len;
+	emsg->skb = skb;
+
+	espintcp_push_msgs(sk);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(espintcp_push_skb);
+
+static int espintcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
+{
+	long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct espintcp_msg *emsg = &ctx->partial;
+	struct iov_iter pfx_iter;
+	struct kvec pfx_iov = {};
+	size_t msglen = size + 2;
+	char buf[2] = {0};
+	int err, end;
+
+	if (msg->msg_flags)
+		return -EOPNOTSUPP;
+
+	if (size > MAX_ESPINTCP_MSG)
+		return -EMSGSIZE;
+
+	if (msg->msg_controllen)
+		return -EOPNOTSUPP;
+
+	lock_sock(sk);
+
+	err = espintcp_push_msgs(sk);
+	if (err < 0) {
+		err = -ENOBUFS;
+		goto unlock;
+	}
+
+	sk_msg_init(&emsg->skmsg);
+	while (1) {
+		/* only -ENOMEM is possible since we don't coalesce */
+		err = sk_msg_alloc(sk, &emsg->skmsg, msglen, 0);
+		if (!err)
+			break;
+
+		err = sk_stream_wait_memory(sk, &timeo);
+		if (err)
+			goto fail;
+	}
+
+	*((__be16 *)buf) = cpu_to_be16(msglen);
+	pfx_iov.iov_base = buf;
+	pfx_iov.iov_len = sizeof(buf);
+	iov_iter_kvec(&pfx_iter, WRITE, &pfx_iov, 1, pfx_iov.iov_len);
+
+	err = sk_msg_memcopy_from_iter(sk, &pfx_iter, &emsg->skmsg,
+				       pfx_iov.iov_len);
+	if (err < 0)
+		goto fail;
+
+	err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, &emsg->skmsg, size);
+	if (err < 0)
+		goto fail;
+
+	end = emsg->skmsg.sg.end;
+	emsg->len = size;
+	sk_msg_iter_var_prev(end);
+	sg_mark_end(sk_msg_elem(&emsg->skmsg, end));
+
+	tcp_rate_check_app_limited(sk);
+
+	err = espintcp_push_msgs(sk);
+	/* this message could be partially sent, keep it */
+	if (err < 0)
+		goto unlock;
+	release_sock(sk);
+
+	return size;
+
+fail:
+	sk_msg_free(sk, &emsg->skmsg);
+	memset(emsg, 0, sizeof(*emsg));
+unlock:
+	release_sock(sk);
+	return err;
+}
+
+static struct proto espintcp_prot __ro_after_init;
+static struct proto_ops espintcp_ops __ro_after_init;
+
+static void espintcp_data_ready(struct sock *sk)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+
+	strp_data_ready(&ctx->strp);
+}
+
+static void espintcp_tx_work(struct work_struct *work)
+{
+	struct espintcp_ctx *ctx = container_of(work,
+						struct espintcp_ctx, work);
+	struct sock *sk = ctx->strp.sk;
+
+	lock_sock(sk);
+	if (!ctx->tx_running)
+		espintcp_push_msgs(sk);
+	release_sock(sk);
+}
+
+static void espintcp_write_space(struct sock *sk)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+
+	schedule_work(&ctx->work);
+	ctx->saved_write_space(sk);
+}
+
+static void espintcp_destruct(struct sock *sk)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+
+	kfree(ctx);
+}
+
+bool tcp_is_ulp_esp(struct sock *sk)
+{
+	return sk->sk_prot == &espintcp_prot;
+}
+EXPORT_SYMBOL_GPL(tcp_is_ulp_esp);
+
+static int espintcp_init_sk(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct strp_callbacks cb = {
+		.rcv_msg = espintcp_rcv,
+		.parse_msg = espintcp_parse,
+	};
+	struct espintcp_ctx *ctx;
+	int err;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	err = strp_init(&ctx->strp, sk, &cb);
+	if (err)
+		goto free;
+
+	__sk_dst_reset(sk);
+
+	strp_check_rcv(&ctx->strp);
+	skb_queue_head_init(&ctx->ike_queue);
+	skb_queue_head_init(&ctx->out_queue);
+	sk->sk_prot = &espintcp_prot;
+	sk->sk_socket->ops = &espintcp_ops;
+	ctx->saved_data_ready = sk->sk_data_ready;
+	ctx->saved_write_space = sk->sk_write_space;
+	sk->sk_data_ready = espintcp_data_ready;
+	sk->sk_write_space = espintcp_write_space;
+	sk->sk_destruct = espintcp_destruct;
+	icsk->icsk_ulp_data = ctx;
+	INIT_WORK(&ctx->work, espintcp_tx_work);
+
+	/* avoid using task_frag */
+	sk->sk_allocation = GFP_ATOMIC;
+
+	return 0;
+
+free:
+	kfree(ctx);
+	return err;
+}
+
+static void espintcp_release(struct sock *sk)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct sk_buff_head queue;
+	struct sk_buff *skb;
+
+	__skb_queue_head_init(&queue);
+	skb_queue_splice_init(&ctx->out_queue, &queue);
+
+	while ((skb = __skb_dequeue(&queue)))
+		espintcp_push_skb(sk, skb);
+
+	tcp_release_cb(sk);
+}
+
+static void espintcp_close(struct sock *sk, long timeout)
+{
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+	struct espintcp_msg *emsg = &ctx->partial;
+
+	strp_stop(&ctx->strp);
+
+	sk->sk_prot = &tcp_prot;
+	barrier();
+
+	cancel_work_sync(&ctx->work);
+	strp_done(&ctx->strp);
+
+	skb_queue_purge(&ctx->out_queue);
+	skb_queue_purge(&ctx->ike_queue);
+
+	if (emsg->len) {
+		if (emsg->skb)
+			kfree_skb(emsg->skb);
+		else
+			sk_msg_free(sk, &emsg->skmsg);
+	}
+
+	tcp_close(sk, timeout);
+}
+
+static __poll_t espintcp_poll(struct file *file, struct socket *sock,
+			      poll_table *wait)
+{
+	__poll_t mask = datagram_poll(file, sock, wait);
+	struct sock *sk = sock->sk;
+	struct espintcp_ctx *ctx = espintcp_getctx(sk);
+
+	if (!skb_queue_empty(&ctx->ike_queue))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+
+static struct tcp_ulp_ops espintcp_ulp __read_mostly = {
+	.name = "espintcp",
+	.owner = THIS_MODULE,
+	.init = espintcp_init_sk,
+};
+
+void __init espintcp_init(void)
+{
+	memcpy(&espintcp_prot, &tcp_prot, sizeof(tcp_prot));
+	memcpy(&espintcp_ops, &inet_stream_ops, sizeof(inet_stream_ops));
+	espintcp_prot.sendmsg = espintcp_sendmsg;
+	espintcp_prot.recvmsg = espintcp_recvmsg;
+	espintcp_prot.close = espintcp_close;
+	espintcp_prot.release_cb = espintcp_release;
+	espintcp_ops.poll = espintcp_poll;
+
+	tcp_register_ulp(&espintcp_ulp);
+}
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 21e939235b39..4af04f74bf30 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -39,6 +39,9 @@
 #ifdef CONFIG_XFRM_STATISTICS
 #include <net/snmp.h>
 #endif
+#ifdef CONFIG_INET_ESPINTCP
+#include <net/espintcp.h>
+#endif
 
 #include "xfrm_hash.h"
 
@@ -4157,6 +4160,10 @@ void __init xfrm_init(void)
 	seqcount_init(&xfrm_policy_hash_generation);
 	xfrm_input_init();
 
+#ifdef CONFIG_INET_ESPINTCP
+	espintcp_init();
+#endif
+
 	RCU_INIT_POINTER(xfrm_if_cb, NULL);
 	synchronize_rcu();
 }
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index c6f3c4a1bd99..acef2d54f869 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -668,6 +668,9 @@ int __xfrm_state_delete(struct xfrm_state *x)
 		net->xfrm.state_num--;
 		spin_unlock(&net->xfrm.xfrm_state_lock);
 
+		if (x->encap_sk)
+			sock_put(rcu_dereference_raw(x->encap_sk));
+
 		xfrm_dev_state_delete(x);
 
 		/* All xfrm_state objects are created by xfrm_state_alloc.
