[PATCH ipsec-next v7 0/6] ipsec: add TCP encapsulation support (RFC 8229)

[PATCH ipsec-next v7 0/6] ipsec: add TCP encapsulation support (RFC 8229)

[Sabrina Dubroca]

This patchset introduces support for TCP encapsulation of IKE and ESP
messages, as defined by RFC 8229 [0]. It is an evolution of what
Herbert Xu proposed in January 2018 [1] that addresses the main
criticism against it, by not interfering with the TCP implementation
at all. The networking stack now has infrastructure for this: TCP ULPs
and Stream Parsers.

The first patches are preparation and refactoring, and the final patch
adds the feature.

The main omission in this submission is IPv6 support. ESP
encapsulation over UDP with IPv6 is currently not supported in the
kernel either, as UDP encapsulation is aimed at NAT traversal, and NAT
is not frequently used with IPv6.

Some of the code is taken directly, or slightly modified, from Herbert
Xu's original submission [1]. The ULP and strparser pieces are
new. This work was presented and discussed at the IPsec workshop and
netdev 0x13 conference [2] in Prague, last March.

[0] https://tools.ietf.org/html/rfc8229
[1] https://patchwork.ozlabs.org/patch/859107/
[2] https://netdevconf.org/0x13/session.html?talk-ipsec-encap

Changes since v6:
 - fix sparse warning in patch 6/6

Changes since v5:
 - rebase patch 1/6 on top of ipsec-next (conflict with commits
   7c422d0ce975 ("net: add READ_ONCE() annotation in
   __skb_wait_for_more_packets()") and 3f926af3f4d6 ("net: use
   skb_queue_empty_lockless() in busy poll contexts"))

Changes since v4:
 - prevent combining sockmap with espintcp, as this does not work
   properly and I can't see a use case for it

Changes since v3:
 - fix sparse warning related to RCU tag on icsk_ulp_data

Changes since v2:
 - rename config option to INET_ESPINTCP and move it to
   net/ipv4/Kconfig (patch 6/6)

Changes since v1:
 - drop patch 1, already present in the tree as commit bd95e678e0f6
   ("bpf: sockmap, fix use after free from sleep in psock backlog
   workqueue")
 - patch 1/6: fix doc error reported by kbuild test robot <lkp@intel.com>
 - patch 6/6, fix things reported by Steffen Klassert:
   - remove unneeded goto and improve error handling in
     esp_output_tcp_finish
   - clean up the ifdefs by providing dummy implementations of those
     functions
   - fix Kconfig select, missing NET_SOCK_MSG

Sabrina Dubroca (6):
  net: add queue argument to __skb_wait_for_more_packets and
    __skb_{,try_}recv_datagram
  xfrm: introduce xfrm_trans_queue_net
  xfrm: add route lookup to xfrm4_rcv_encap
  esp4: prepare esp_input_done2 for non-UDP encapsulation
  esp4: split esp_output_udp_encap and introduce esp_output_encap
  xfrm: add espintcp (RFC 8229)

 include/linux/skbuff.h    |  11 +-
 include/net/espintcp.h    |  39 +++
 include/net/xfrm.h        |   4 +
 include/uapi/linux/udp.h  |   1 +
 net/core/datagram.c       |  27 +-
 net/ipv4/Kconfig          |  11 +
 net/ipv4/esp4.c           | 264 ++++++++++++++++++--
 net/ipv4/udp.c            |   3 +-
 net/ipv4/xfrm4_protocol.c |   9 +
 net/unix/af_unix.c        |   7 +-
 net/xfrm/Makefile         |   1 +
 net/xfrm/espintcp.c       | 509 ++++++++++++++++++++++++++++++++++++++
 net/xfrm/xfrm_input.c     |  21 +-
 net/xfrm/xfrm_policy.c    |   7 +
 net/xfrm/xfrm_state.c     |   3 +
 15 files changed, 871 insertions(+), 46 deletions(-)
 create mode 100644 include/net/espintcp.h
 create mode 100644 net/xfrm/espintcp.c

-- 
2.23.0

[PATCH ipsec-next v7 1/6] net: add queue argument to __skb_wait_for_more_packets and __skb_{,try_}recv_datagram

[Sabrina Dubroca]

This will be used by ESP over TCP to handle the queue of IKE messages.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
v6: rebase on top of commits 7c422d0ce975 and 3f926af3f4d6
v2: document the new argument to __skb_try_recv_datagram

 include/linux/skbuff.h | 11 ++++++++---
 net/core/datagram.c    | 27 +++++++++++++++++----------
 net/ipv4/udp.c         |  3 ++-
 net/unix/af_unix.c     |  7 ++++---
 4 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index dfe02b658829..81aeb2ff1ca6 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3459,7 +3459,8 @@ static inline void skb_frag_list_init(struct sk_buff *skb)
 	for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
 
 
-int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
+int __skb_wait_for_more_packets(struct sock *sk, struct sk_buff_head *queue,
+				int *err, long *timeo_p,
 				const struct sk_buff *skb);
 struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
 					  struct sk_buff_head *queue,
@@ -3468,12 +3469,16 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
 							   struct sk_buff *skb),
 					  int *off, int *err,
 					  struct sk_buff **last);
-struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
+struct sk_buff *__skb_try_recv_datagram(struct sock *sk,
+					struct sk_buff_head *queue,
+					unsigned int flags,
 					void (*destructor)(struct sock *sk,
 							   struct sk_buff *skb),
 					int *off, int *err,
 					struct sk_buff **last);
-struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
+struct sk_buff *__skb_recv_datagram(struct sock *sk,
+				    struct sk_buff_head *sk_queue,
+				    unsigned int flags,
 				    void (*destructor)(struct sock *sk,
 						       struct sk_buff *skb),
 				    int *off, int *err);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index da3c24ed129c..a78e7f864c1e 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -84,7 +84,8 @@ static int receiver_wake_function(wait_queue_entry_t *wait, unsigned int mode, i
 /*
  * Wait for the last received packet to be different from skb
  */
-int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
+int __skb_wait_for_more_packets(struct sock *sk, struct sk_buff_head *queue,
+				int *err, long *timeo_p,
 				const struct sk_buff *skb)
 {
 	int error;
@@ -97,7 +98,7 @@ int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
 	if (error)
 		goto out_err;
 
-	if (READ_ONCE(sk->sk_receive_queue.prev) != skb)
+	if (READ_ONCE(queue->prev) != skb)
 		goto out;
 
 	/* Socket shut down? */
@@ -209,6 +210,7 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
 /**
  *	__skb_try_recv_datagram - Receive a datagram skbuff
  *	@sk: socket
+ *	@queue: socket queue from which to receive
  *	@flags: MSG\_ flags
  *	@destructor: invoked under the receive lock on successful dequeue
  *	@off: an offset in bytes to peek skb from. Returns an offset
@@ -241,13 +243,14 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
  *	quite explicitly by POSIX 1003.1g, don't change them without having
  *	the standard around please.
  */
-struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned int flags,
+struct sk_buff *__skb_try_recv_datagram(struct sock *sk,
+					struct sk_buff_head *queue,
+					unsigned int flags,
 					void (*destructor)(struct sock *sk,
 							   struct sk_buff *skb),
 					int *off, int *err,
 					struct sk_buff **last)
 {
-	struct sk_buff_head *queue = &sk->sk_receive_queue;
 	struct sk_buff *skb;
 	unsigned long cpu_flags;
 	/*
@@ -278,7 +281,7 @@ struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned int flags,
 			break;
 
 		sk_busy_loop(sk, flags & MSG_DONTWAIT);
-	} while (READ_ONCE(sk->sk_receive_queue.prev) != *last);
+	} while (READ_ONCE(queue->prev) != *last);
 
 	error = -EAGAIN;
 
@@ -288,7 +291,9 @@ struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned int flags,
 }
 EXPORT_SYMBOL(__skb_try_recv_datagram);
 
-struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
+struct sk_buff *__skb_recv_datagram(struct sock *sk,
+				    struct sk_buff_head *sk_queue,
+				    unsigned int flags,
 				    void (*destructor)(struct sock *sk,
 						       struct sk_buff *skb),
 				    int *off, int *err)
@@ -299,15 +304,16 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 
 	do {
-		skb = __skb_try_recv_datagram(sk, flags, destructor, off, err,
-					      &last);
+		skb = __skb_try_recv_datagram(sk, sk_queue, flags, destructor,
+					      off, err, &last);
 		if (skb)
 			return skb;
 
 		if (*err != -EAGAIN)
 			break;
 	} while (timeo &&
-		!__skb_wait_for_more_packets(sk, err, &timeo, last));
+		 !__skb_wait_for_more_packets(sk, sk_queue, err,
+					      &timeo, last));
 
 	return NULL;
 }
@@ -318,7 +324,8 @@ struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
 {
 	int off = 0;
 
-	return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
+	return __skb_recv_datagram(sk, &sk->sk_receive_queue,
+				   flags | (noblock ? MSG_DONTWAIT : 0),
 				   NULL, &off, err);
 }
 EXPORT_SYMBOL(skb_recv_datagram);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index da805ee7558b..fbf88bab10aa 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1691,7 +1691,8 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
 
 		/* sk_queue is empty, reader_queue may contain peeked packets */
 	} while (timeo &&
-		 !__skb_wait_for_more_packets(sk, &error, &timeo,
+		 !__skb_wait_for_more_packets(sk, &sk->sk_receive_queue,
+					      &error, &timeo,
 					      (struct sk_buff *)sk_queue));
 
 	*err = error;
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 193cba2d777b..f1a2944115d5 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2046,8 +2046,8 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 		mutex_lock(&u->iolock);
 
 		skip = sk_peek_offset(sk, flags);
-		skb = __skb_try_recv_datagram(sk, flags, NULL, &skip, &err,
-					      &last);
+		skb = __skb_try_recv_datagram(sk, &sk->sk_receive_queue, flags,
+					      NULL, &skip, &err, &last);
 		if (skb)
 			break;
 
@@ -2056,7 +2056,8 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 		if (err != -EAGAIN)
 			break;
 	} while (timeo &&
-		 !__skb_wait_for_more_packets(sk, &err, &timeo, last));
+		 !__skb_wait_for_more_packets(sk, &sk->sk_receive_queue,
+					      &err, &timeo, last));
 
 	if (!skb) { /* implies iolock unlocked */
 		unix_state_lock(sk);
-- 
2.23.0

[PATCH ipsec-next v7 2/6] xfrm: introduce xfrm_trans_queue_net

[Sabrina Dubroca]

This will be used by TCP encapsulation to write packets to the encap
socket without holding the user socket's lock. Without this reinjection,
we're already holding the lock of the user socket, and then try to lock
the encap socket as well when we enqueue the encrypted packet.

While at it, add a BUILD_BUG_ON like we usually do for skb->cb, since
it's missing for struct xfrm_trans_cb.

Co-developed-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
 include/net/xfrm.h    |  3 +++
 net/xfrm/xfrm_input.c | 21 +++++++++++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index dda3c025452e..56ff86621bb4 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1547,6 +1547,9 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload);
 int xfrm_init_state(struct xfrm_state *x);
 int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type);
 int xfrm_input_resume(struct sk_buff *skb, int nexthdr);
+int xfrm_trans_queue_net(struct net *net, struct sk_buff *skb,
+			 int (*finish)(struct net *, struct sock *,
+				       struct sk_buff *));
 int xfrm_trans_queue(struct sk_buff *skb,
 		     int (*finish)(struct net *, struct sock *,
 				   struct sk_buff *));
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 9b599ed66d97..7a6c2731839d 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -36,6 +36,7 @@ struct xfrm_trans_cb {
 #endif
 	} header;
 	int (*finish)(struct net *net, struct sock *sk, struct sk_buff *skb);
+	struct net *net;
 };
 
 #define XFRM_TRANS_SKB_CB(__skb) ((struct xfrm_trans_cb *)&((__skb)->cb[0]))
@@ -763,12 +764,13 @@ static void xfrm_trans_reinject(unsigned long data)
 	skb_queue_splice_init(&trans->queue, &queue);
 
 	while ((skb = __skb_dequeue(&queue)))
-		XFRM_TRANS_SKB_CB(skb)->finish(dev_net(skb->dev), NULL, skb);
+		XFRM_TRANS_SKB_CB(skb)->finish(XFRM_TRANS_SKB_CB(skb)->net,
+					       NULL, skb);
 }
 
-int xfrm_trans_queue(struct sk_buff *skb,
-		     int (*finish)(struct net *, struct sock *,
-				   struct sk_buff *))
+int xfrm_trans_queue_net(struct net *net, struct sk_buff *skb,
+			 int (*finish)(struct net *, struct sock *,
+				       struct sk_buff *))
 {
 	struct xfrm_trans_tasklet *trans;
 
@@ -777,11 +779,22 @@ int xfrm_trans_queue(struct sk_buff *skb,
 	if (skb_queue_len(&trans->queue) >= netdev_max_backlog)
 		return -ENOBUFS;
 
+	BUILD_BUG_ON(sizeof(struct xfrm_trans_cb) > sizeof(skb->cb));
+
 	XFRM_TRANS_SKB_CB(skb)->finish = finish;
+	XFRM_TRANS_SKB_CB(skb)->net = net;
 	__skb_queue_tail(&trans->queue, skb);
 	tasklet_schedule(&trans->tasklet);
 	return 0;
 }
+EXPORT_SYMBOL(xfrm_trans_queue_net);
+
+int xfrm_trans_queue(struct sk_buff *skb,
+		     int (*finish)(struct net *, struct sock *,
+				   struct sk_buff *))
+{
+	return xfrm_trans_queue_net(dev_net(skb->dev), skb, finish);
+}
 EXPORT_SYMBOL(xfrm_trans_queue);
 
 void __init xfrm_input_init(void)
-- 
2.23.0

[PATCH ipsec-next v7 3/6] xfrm: add route lookup to xfrm4_rcv_encap

[Sabrina Dubroca]

At this point, with TCP encapsulation, the dst may be gone, but
xfrm_input needs one.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/xfrm4_protocol.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv4/xfrm4_protocol.c b/net/ipv4/xfrm4_protocol.c
index 8a4285712808..ea595c8549c7 100644
--- a/net/ipv4/xfrm4_protocol.c
+++ b/net/ipv4/xfrm4_protocol.c
@@ -72,6 +72,14 @@ int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
 	if (!head)
 		goto out;
 
+	if (!skb_dst(skb)) {
+		const struct iphdr *iph = ip_hdr(skb);
+
+		if (ip_route_input_noref(skb, iph->daddr, iph->saddr,
+					 iph->tos, skb->dev))
+			goto drop;
+	}
+
 	for_each_protocol_rcu(*head, handler)
 		if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
 			return ret;
@@ -79,6 +87,7 @@ int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
 out:
 	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
+drop:
 	kfree_skb(skb);
 	return 0;
 }
-- 
2.23.0

[PATCH ipsec-next v7 4/6] esp4: prepare esp_input_done2 for non-UDP encapsulation

[Sabrina Dubroca]

For espintcp encapsulation, we will need to get the source port from the
TCP header instead of UDP. Introduce a variable to hold the port.

Co-developed-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/esp4.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 5c967764041f..c5d826642229 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -601,6 +601,18 @@ int esp_input_done2(struct sk_buff *skb, int err)
 	if (x->encap) {
 		struct xfrm_encap_tmpl *encap = x->encap;
 		struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
+		__be16 source;
+
+		switch (x->encap->encap_type) {
+		case UDP_ENCAP_ESPINUDP:
+		case UDP_ENCAP_ESPINUDP_NON_IKE:
+			source = uh->source;
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			err = -EINVAL;
+			goto out;
+		}
 
 		/*
 		 * 1) if the NAT-T peer's IP or port changed then
@@ -609,11 +621,11 @@ int esp_input_done2(struct sk_buff *skb, int err)
 		 *    SRC ports.
 		 */
 		if (iph->saddr != x->props.saddr.a4 ||
-		    uh->source != encap->encap_sport) {
+		    source != encap->encap_sport) {
 			xfrm_address_t ipaddr;
 
 			ipaddr.a4 = iph->saddr;
-			km_new_mapping(x, &ipaddr, uh->source);
+			km_new_mapping(x, &ipaddr, source);
 
 			/* XXX: perhaps add an extra
 			 * policy check here, to see
-- 
2.23.0

[PATCH ipsec-next v7 5/6] esp4: split esp_output_udp_encap and introduce esp_output_encap

[Sabrina Dubroca]

Co-developed-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/esp4.c | 57 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index c5d826642229..033c61d27148 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -225,45 +225,62 @@ static void esp_output_fill_trailer(u8 *tail, int tfclen, int plen, __u8 proto)
 	tail[plen - 1] = proto;
 }
 
-static int esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
+static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
+					       int encap_type,
+					       struct esp_info *esp,
+					       __be16 sport,
+					       __be16 dport)
 {
-	int encap_type;
 	struct udphdr *uh;
 	__be32 *udpdata32;
-	__be16 sport, dport;
-	struct xfrm_encap_tmpl *encap = x->encap;
-	struct ip_esp_hdr *esph = esp->esph;
 	unsigned int len;
 
-	spin_lock_bh(&x->lock);
-	sport = encap->encap_sport;
-	dport = encap->encap_dport;
-	encap_type = encap->encap_type;
-	spin_unlock_bh(&x->lock);
-
 	len = skb->len + esp->tailen - skb_transport_offset(skb);
 	if (len + sizeof(struct iphdr) >= IP_MAX_MTU)
-		return -EMSGSIZE;
+		return ERR_PTR(-EMSGSIZE);
 
-	uh = (struct udphdr *)esph;
+	uh = (struct udphdr *)esp->esph;
 	uh->source = sport;
 	uh->dest = dport;
 	uh->len = htons(len);
 	uh->check = 0;
 
+	*skb_mac_header(skb) = IPPROTO_UDP;
+
+	if (encap_type == UDP_ENCAP_ESPINUDP_NON_IKE) {
+		udpdata32 = (__be32 *)(uh + 1);
+		udpdata32[0] = udpdata32[1] = 0;
+		return (struct ip_esp_hdr *)(udpdata32 + 2);
+	}
+
+	return (struct ip_esp_hdr *)(uh + 1);
+}
+
+static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
+			    struct esp_info *esp)
+{
+	struct xfrm_encap_tmpl *encap = x->encap;
+	struct ip_esp_hdr *esph;
+	__be16 sport, dport;
+	int encap_type;
+
+	spin_lock_bh(&x->lock);
+	sport = encap->encap_sport;
+	dport = encap->encap_dport;
+	encap_type = encap->encap_type;
+	spin_unlock_bh(&x->lock);
+
 	switch (encap_type) {
 	default:
 	case UDP_ENCAP_ESPINUDP:
-		esph = (struct ip_esp_hdr *)(uh + 1);
-		break;
 	case UDP_ENCAP_ESPINUDP_NON_IKE:
-		udpdata32 = (__be32 *)(uh + 1);
-		udpdata32[0] = udpdata32[1] = 0;
-		esph = (struct ip_esp_hdr *)(udpdata32 + 2);
+		esph = esp_output_udp_encap(skb, encap_type, esp, sport, dport);
 		break;
 	}
 
-	*skb_mac_header(skb) = IPPROTO_UDP;
+	if (IS_ERR(esph))
+		return PTR_ERR(esph);
+
 	esp->esph = esph;
 
 	return 0;
@@ -281,7 +298,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
 
 	/* this is non-NULL only with UDP Encapsulation */
 	if (x->encap) {
-		int err = esp_output_udp_encap(x, skb, esp);
+		int err = esp_output_encap(x, skb, esp);
 
 		if (err < 0)
 			return err;
-- 
2.23.0

[PATCH ipsec-next v7 6/6] xfrm: add espintcp (RFC 8229)

[Sabrina Dubroca]

TCP encapsulation of IKE and IPsec messages (RFC 8229) is implemented
as a TCP ULP, overriding in particular the sendmsg and recvmsg
operations. A Stream Parser is used to extract messages out of the TCP
stream using the first 2 bytes as length marker. Received IKE messages
are put on "ike_queue", waiting to be dequeued by the custom recvmsg
implementation. Received ESP messages are sent to XFRM, like with UDP
encapsulation.

Some of this code is taken from the original submission by Herbert
Xu. Currently, only IPv4 is supported, like for UDP encapsulation.

Co-developed-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: David S. Miller <davem@davemloft.net>
---
v7: fix sparse warning with sk_user_data
v5: prevent enabling espintcp if the socket is already part of a
    sockmap
v4: fix sparse warnings related to RCU with icsk_ulp_data
  - use rcu_assign_pointer in espintcp_init_sk
  - use __force cast in espintcp_getctx
v3: rename config option to INET_ESPINTCP and move it to net/ipv4/Kconfig
v2:
  - remove unneeded goto and improve error handling in
    esp_output_tcp_finish
  - clean up the ifdefs by providing dummy implementations of those
    functions
  - fix Kconfig select, missing NET_SOCK_MSG

 include/net/espintcp.h   |  39 +++
 include/net/xfrm.h       |   1 +
 include/uapi/linux/udp.h |   1 +
 net/ipv4/Kconfig         |  11 +
 net/ipv4/esp4.c          | 191 ++++++++++++++-
 net/xfrm/Makefile        |   1 +
 net/xfrm/espintcp.c      | 509 +++++++++++++++++++++++++++++++++++++++
 net/xfrm/xfrm_policy.c   |   7 +
 net/xfrm/xfrm_state.c    |   3 +
 9 files changed, 760 insertions(+), 3 deletions(-)
 create mode 100644 include/net/espintcp.h
 create mode 100644 net/xfrm/espintcp.c

diff --git a/include/net/espintcp.h b/include/net/espintcp.h
new file mode 100644
index 000000000000..dd7026a00066
--- /dev/null
+++ b/include/net/espintcp.h
@@ -0,0 +1,39 @@
+/* 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);
+
+	/* RCU is only needed for diag */
+	return (__force void *)icsk->icsk_ulp_data;
+}
+#endif
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 56ff86621bb4..8f71c111e65a 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 03381f3e12ba..93bf717de8fa 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..f15d6a564b0e
--- /dev/null
+++ b/net/xfrm/espintcp.c
@@ -0,0 +1,509 @@
+// 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;
+
+	/* sockmap is not compatible with espintcp */
+	if (sk->sk_user_data)
+		return -EBUSY;
+
+	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;
+	rcu_assign_pointer(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 f2d1e573ea55..297d1eb79e5c 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.
-- 
2.23.0

Re: [PATCH ipsec-next v7 0/6] ipsec: add TCP encapsulation support (RFC 8229)

[Steffen Klassert]

On Mon, Nov 25, 2019 at 02:48:56PM +0100, Sabrina Dubroca wrote:
> This patchset introduces support for TCP encapsulation of IKE and ESP
> messages, as defined by RFC 8229 [0]. It is an evolution of what
> Herbert Xu proposed in January 2018 [1] that addresses the main
> criticism against it, by not interfering with the TCP implementation
> at all. The networking stack now has infrastructure for this: TCP ULPs
> and Stream Parsers.
> 
> The first patches are preparation and refactoring, and the final patch
> adds the feature.
> 
> The main omission in this submission is IPv6 support. ESP
> encapsulation over UDP with IPv6 is currently not supported in the
> kernel either, as UDP encapsulation is aimed at NAT traversal, and NAT
> is not frequently used with IPv6.
> 
> Some of the code is taken directly, or slightly modified, from Herbert
> Xu's original submission [1]. The ULP and strparser pieces are
> new. This work was presented and discussed at the IPsec workshop and
> netdev 0x13 conference [2] in Prague, last March.
> 
> [0] https://tools.ietf.org/html/rfc8229
> [1] https://patchwork.ozlabs.org/patch/859107/
> [2] https://netdevconf.org/0x13/session.html?talk-ipsec-encap
> 
> Changes since v6:
>  - fix sparse warning in patch 6/6
> 
> Changes since v5:
>  - rebase patch 1/6 on top of ipsec-next (conflict with commits
>    7c422d0ce975 ("net: add READ_ONCE() annotation in
>    __skb_wait_for_more_packets()") and 3f926af3f4d6 ("net: use
>    skb_queue_empty_lockless() in busy poll contexts"))
> 
> Changes since v4:
>  - prevent combining sockmap with espintcp, as this does not work
>    properly and I can't see a use case for it
> 
> Changes since v3:
>  - fix sparse warning related to RCU tag on icsk_ulp_data
> 
> Changes since v2:
>  - rename config option to INET_ESPINTCP and move it to
>    net/ipv4/Kconfig (patch 6/6)
> 
> Changes since v1:
>  - drop patch 1, already present in the tree as commit bd95e678e0f6
>    ("bpf: sockmap, fix use after free from sleep in psock backlog
>    workqueue")
>  - patch 1/6: fix doc error reported by kbuild test robot <lkp@intel.com>
>  - patch 6/6, fix things reported by Steffen Klassert:
>    - remove unneeded goto and improve error handling in
>      esp_output_tcp_finish
>    - clean up the ifdefs by providing dummy implementations of those
>      functions
>    - fix Kconfig select, missing NET_SOCK_MSG
> 
> Sabrina Dubroca (6):
>   net: add queue argument to __skb_wait_for_more_packets and
>     __skb_{,try_}recv_datagram
>   xfrm: introduce xfrm_trans_queue_net
>   xfrm: add route lookup to xfrm4_rcv_encap
>   esp4: prepare esp_input_done2 for non-UDP encapsulation
>   esp4: split esp_output_udp_encap and introduce esp_output_encap
>   xfrm: add espintcp (RFC 8229)

All applied to ipsec-next, thanks a lot Sabrina!