Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from David Miller:

 1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan.

 2) Support UDP segmentation in code TSO code, from Eric Dumazet.

 3) Allow flashing different flash images in cxgb4 driver, from Vishal
    Kulkarni.

 4) Add drop frames counter and flow status to tc flower offloading,
    from Po Liu.

 5) Support n-tuple filters in cxgb4, from Vishal Kulkarni.

 6) Various new indirect call avoidance, from Eric Dumazet and Brian
    Vazquez.

 7) Fix BPF verifier failures on 32-bit pointer arithmetic, from
    Yonghong Song.

 8) Support querying and setting hardware address of a port function via
    devlink, use this in mlx5, from Parav Pandit.

 9) Support hw ipsec offload on bonding slaves, from Jarod Wilson.

10) Switch qca8k driver over to phylink, from Jonathan McDowell.

11) In bpftool, show list of processes holding BPF FD references to
    maps, programs, links, and btf objects. From Andrii Nakryiko.

12) Several conversions over to generic power management, from Vaibhav
    Gupta.

13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry
    Yakunin.

14) Various https url conversions, from Alexander A. Klimov.

15) Timestamping and PHC support for mscc PHY driver, from Antoine
    Tenart.

16) Support bpf iterating over tcp and udp sockets, from Yonghong Song.

17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov.

18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan.

19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several
    drivers. From Luc Van Oostenryck.

20) XDP support for xen-netfront, from Denis Kirjanov.

21) Support receive buffer autotuning in MPTCP, from Florian Westphal.

22) Support EF100 chip in sfc driver, from Edward Cree.

23) Add XDP support to mvpp2 driver, from Matteo Croce.

24) Support MPTCP in sock_diag, from Paolo Abeni.

25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic
    infrastructure, from Jakub Kicinski.

26) Several pci_ --> dma_ API conversions, from Christophe JAILLET.

27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel.

28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki.

29) Refactor a lot of networking socket option handling code in order to
    avoid set_fs() calls, from Christoph Hellwig.

30) Add rfc4884 support to icmp code, from Willem de Bruijn.

31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei.

32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin.

33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin.

34) Support TCP syncookies in MPTCP, from Flowian Westphal.

35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano
    Brivio.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits)
  net: thunderx: initialize VF's mailbox mutex before first usage
  usb: hso: remove bogus check for EINPROGRESS
  usb: hso: no complaint about kmalloc failure
  hso: fix bailout in error case of probe
  ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM
  selftests/net: relax cpu affinity requirement in msg_zerocopy test
  mptcp: be careful on subflow creation
  selftests: rtnetlink: make kci_test_encap() return sub-test result
  selftests: rtnetlink: correct the final return value for the test
  net: dsa: sja1105: use detected device id instead of DT one on mismatch
  tipc: set ub->ifindex for local ipv6 address
  ipv6: add ipv6_dev_find()
  net: openvswitch: silence suspicious RCU usage warning
  Revert "vxlan: fix tos value before xmit"
  ptp: only allow phase values lower than 1 period
  farsync: switch from 'pci_' to 'dma_' API
  wan: wanxl: switch from 'pci_' to 'dma_' API
  hv_netvsc: do not use VF device if link is down
  dpaa2-eth: Fix passing zero to 'PTR_ERR' warning
  net: macb: Properly handle phylink on at91sam9x
  ...

1 files changed, 231 insertions, 110 deletions

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 3838a0b3a21f..96f4f2fe50ad 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -29,40 +29,6 @@ static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
 	MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
 }
 
-static int subflow_rebuild_header(struct sock *sk)
-{
-	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
-	int local_id, err = 0;
-
-	if (subflow->request_mptcp && !subflow->token) {
-		pr_debug("subflow=%p", sk);
-		err = mptcp_token_new_connect(sk);
-	} else if (subflow->request_join && !subflow->local_nonce) {
-		struct mptcp_sock *msk = (struct mptcp_sock *)subflow->conn;
-
-		pr_debug("subflow=%p", sk);
-
-		do {
-			get_random_bytes(&subflow->local_nonce, sizeof(u32));
-		} while (!subflow->local_nonce);
-
-		if (subflow->local_id)
-			goto out;
-
-		local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
-		if (local_id < 0)
-			return -EINVAL;
-
-		subflow->local_id = local_id;
-	}
-
-out:
-	if (err)
-		return err;
-
-	return subflow->icsk_af_ops->rebuild_header(sk);
-}
-
 static void subflow_req_destructor(struct request_sock *req)
 {
 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
@@ -72,8 +38,7 @@ static void subflow_req_destructor(struct request_sock *req)
 	if (subflow_req->msk)
 		sock_put((struct sock *)subflow_req->msk);
 
-	if (subflow_req->mp_capable)
-		mptcp_token_destroy_request(subflow_req->token);
+	mptcp_token_destroy_request(req);
 	tcp_request_sock_ops.destructor(req);
 }
 
@@ -88,6 +53,12 @@ static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
 	mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
 }
 
+static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
+{
+	return mptcp_is_fully_established((void *)msk) &&
+	       READ_ONCE(msk->pm.accept_subflow);
+}
+
 /* validate received token and create truncated hmac and nonce for SYN-ACK */
 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req,
 						     const struct sk_buff *skb)
@@ -120,30 +91,43 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req,
 	return msk;
 }
 
-static void subflow_init_req(struct request_sock *req,
-			     const struct sock *sk_listener,
-			     struct sk_buff *skb)
+static int __subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
 {
-	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
-	struct mptcp_options_received mp_opt;
-
-	pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
-
-	mptcp_get_options(skb, &mp_opt);
 
 	subflow_req->mp_capable = 0;
 	subflow_req->mp_join = 0;
 	subflow_req->msk = NULL;
+	mptcp_token_init_request(req);
 
 #ifdef CONFIG_TCP_MD5SIG
 	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 	 * TCP option space.
 	 */
 	if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
-		return;
+		return -EINVAL;
 #endif
 
+	return 0;
+}
+
+static void subflow_init_req(struct request_sock *req,
+			     const struct sock *sk_listener,
+			     struct sk_buff *skb)
+{
+	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
+	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+	struct mptcp_options_received mp_opt;
+	int ret;
+
+	pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
+
+	ret = __subflow_init_req(req, sk_listener);
+	if (ret)
+		return;
+
+	mptcp_get_options(skb, &mp_opt);
+
 	if (mp_opt.mp_capable) {
 		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 
@@ -154,13 +138,33 @@ static void subflow_init_req(struct request_sock *req,
 	}
 
 	if (mp_opt.mp_capable && listener->request_mptcp) {
-		int err;
+		int err, retries = 4;
+
+		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
+again:
+		do {
+			get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
+		} while (subflow_req->local_key == 0);
+
+		if (unlikely(req->syncookie)) {
+			mptcp_crypto_key_sha(subflow_req->local_key,
+					     &subflow_req->token,
+					     &subflow_req->idsn);
+			if (mptcp_token_exists(subflow_req->token)) {
+				if (retries-- > 0)
+					goto again;
+			} else {
+				subflow_req->mp_capable = 1;
+			}
+			return;
+		}
 
 		err = mptcp_token_new_request(req);
 		if (err == 0)
 			subflow_req->mp_capable = 1;
+		else if (retries-- > 0)
+			goto again;
 
-		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 	} else if (mp_opt.mp_join && listener->request_mptcp) {
 		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 		subflow_req->mp_join = 1;
@@ -169,11 +173,60 @@ static void subflow_init_req(struct request_sock *req,
 		subflow_req->token = mp_opt.token;
 		subflow_req->remote_nonce = mp_opt.nonce;
 		subflow_req->msk = subflow_token_join_request(req, skb);
+
+		if (unlikely(req->syncookie) && subflow_req->msk) {
+			if (mptcp_can_accept_new_subflow(subflow_req->msk))
+				subflow_init_req_cookie_join_save(subflow_req, skb);
+		}
+
 		pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
 			 subflow_req->remote_nonce, subflow_req->msk);
 	}
 }
 
+int mptcp_subflow_init_cookie_req(struct request_sock *req,
+				  const struct sock *sk_listener,
+				  struct sk_buff *skb)
+{
+	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
+	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+	struct mptcp_options_received mp_opt;
+	int err;
+
+	err = __subflow_init_req(req, sk_listener);
+	if (err)
+		return err;
+
+	mptcp_get_options(skb, &mp_opt);
+
+	if (mp_opt.mp_capable && mp_opt.mp_join)
+		return -EINVAL;
+
+	if (mp_opt.mp_capable && listener->request_mptcp) {
+		if (mp_opt.sndr_key == 0)
+			return -EINVAL;
+
+		subflow_req->local_key = mp_opt.rcvr_key;
+		err = mptcp_token_new_request(req);
+		if (err)
+			return err;
+
+		subflow_req->mp_capable = 1;
+		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
+	} else if (mp_opt.mp_join && listener->request_mptcp) {
+		if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
+			return -EINVAL;
+
+		if (mptcp_can_accept_new_subflow(subflow_req->msk))
+			subflow_req->mp_join = 1;
+
+		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
+
 static void subflow_v4_init_req(struct request_sock *req,
 				const struct sock *sk_listener,
 				struct sk_buff *skb)
@@ -222,7 +275,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct mptcp_options_received mp_opt;
 	struct sock *parent = subflow->conn;
-	struct tcp_sock *tp = tcp_sk(sk);
 
 	subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 
@@ -235,46 +287,40 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 	if (subflow->conn_finished)
 		return;
 
+	subflow->rel_write_seq = 1;
 	subflow->conn_finished = 1;
+	subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
+	pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
 
 	mptcp_get_options(skb, &mp_opt);
-	if (subflow->request_mptcp && mp_opt.mp_capable) {
+	if (subflow->request_mptcp) {
+		if (!mp_opt.mp_capable) {
+			MPTCP_INC_STATS(sock_net(sk),
+					MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
+			mptcp_do_fallback(sk);
+			pr_fallback(mptcp_sk(subflow->conn));
+			goto fallback;
+		}
+
 		subflow->mp_capable = 1;
 		subflow->can_ack = 1;
 		subflow->remote_key = mp_opt.sndr_key;
 		pr_debug("subflow=%p, remote_key=%llu", subflow,
 			 subflow->remote_key);
-	} else if (subflow->request_join && mp_opt.mp_join) {
-		subflow->mp_join = 1;
+		mptcp_finish_connect(sk);
+	} else if (subflow->request_join) {
+		u8 hmac[SHA256_DIGEST_SIZE];
+
+		if (!mp_opt.mp_join)
+			goto do_reset;
+
 		subflow->thmac = mp_opt.thmac;
 		subflow->remote_nonce = mp_opt.nonce;
 		pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
 			 subflow->thmac, subflow->remote_nonce);
-	} else if (subflow->request_mptcp) {
-		tp->is_mptcp = 0;
-	}
 
-	if (!tp->is_mptcp)
-		return;
-
-	if (subflow->mp_capable) {
-		pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk),
-			 subflow->remote_key);
-		mptcp_finish_connect(sk);
-
-		if (skb) {
-			pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq);
-			subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
-		}
-	} else if (subflow->mp_join) {
-		u8 hmac[SHA256_DIGEST_SIZE];
-
-		pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u",
-			 subflow, subflow->thmac,
-			 subflow->remote_nonce);
 		if (!subflow_thmac_valid(subflow)) {
 			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
-			subflow->mp_join = 0;
 			goto do_reset;
 		}
 
@@ -282,24 +328,26 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 				      subflow->local_nonce,
 				      subflow->remote_nonce,
 				      hmac);
-
 		memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 
-		if (skb)
-			subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
-
 		if (!mptcp_finish_join(sk))
 			goto do_reset;
 
+		subflow->mp_join = 1;
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
-	} else {
-do_reset:
-		tcp_send_active_reset(sk, GFP_ATOMIC);
-		tcp_done(sk);
+	} else if (mptcp_check_fallback(sk)) {
+fallback:
+		mptcp_rcv_space_init(mptcp_sk(parent), sk);
 	}
+	return;
+
+do_reset:
+	tcp_send_active_reset(sk, GFP_ATOMIC);
+	tcp_done(sk);
 }
 
-static struct request_sock_ops subflow_request_sock_ops;
+struct request_sock_ops mptcp_subflow_request_sock_ops;
+EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
 static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
 
 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
@@ -312,7 +360,7 @@ static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 		goto drop;
 
-	return tcp_conn_request(&subflow_request_sock_ops,
+	return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 				&subflow_request_sock_ipv4_ops,
 				sk, skb);
 drop:
@@ -337,7 +385,7 @@ static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 	if (!ipv6_unicast_destination(skb))
 		goto drop;
 
-	return tcp_conn_request(&subflow_request_sock_ops,
+	return tcp_conn_request(&mptcp_subflow_request_sock_ops,
 				&subflow_request_sock_ipv6_ops, sk, skb);
 
 drop:
@@ -386,7 +434,7 @@ static void mptcp_sock_destruct(struct sock *sk)
 		sock_orphan(sk);
 	}
 
-	mptcp_token_destroy(mptcp_sk(sk)->token);
+	mptcp_token_destroy(mptcp_sk(sk));
 	inet_sock_destruct(sk);
 }
 
@@ -421,6 +469,17 @@ static void subflow_drop_ctx(struct sock *ssk)
 	kfree_rcu(ctx, rcu);
 }
 
+void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
+				     struct mptcp_options_received *mp_opt)
+{
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
+	subflow->remote_key = mp_opt->sndr_key;
+	subflow->fully_established = 1;
+	subflow->can_ack = 1;
+	WRITE_ONCE(msk->fully_established, true);
+}
+
 static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 					  struct sk_buff *skb,
 					  struct request_sock *req,
@@ -444,7 +503,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 
 	/* hopefully temporary handling for MP_JOIN+syncookie */
 	subflow_req = mptcp_subflow_rsk(req);
-	fallback_is_fatal = subflow_req->mp_join;
+	fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
 	fallback = !tcp_rsk(req)->is_mptcp;
 	if (fallback)
 		goto create_child;
@@ -472,6 +531,7 @@ create_msk:
 	} else if (subflow_req->mp_join) {
 		mptcp_get_options(skb, &mp_opt);
 		if (!mp_opt.mp_join ||
+		    !mptcp_can_accept_new_subflow(subflow_req->msk) ||
 		    !subflow_hmac_valid(req, &mp_opt)) {
 			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
 			fallback = true;
@@ -500,20 +560,25 @@ create_child:
 		}
 
 		if (ctx->mp_capable) {
+			/* this can't race with mptcp_close(), as the msk is
+			 * not yet exposted to user-space
+			 */
+			inet_sk_state_store((void *)new_msk, TCP_ESTABLISHED);
+
 			/* new mpc subflow takes ownership of the newly
 			 * created mptcp socket
 			 */
 			new_msk->sk_destruct = mptcp_sock_destruct;
 			mptcp_pm_new_connection(mptcp_sk(new_msk), 1);
+			mptcp_token_accept(subflow_req, mptcp_sk(new_msk));
 			ctx->conn = new_msk;
 			new_msk = NULL;
 
 			/* with OoO packets we can reach here without ingress
 			 * mpc option
 			 */
-			ctx->remote_key = mp_opt.sndr_key;
-			ctx->fully_established = mp_opt.mp_capable;
-			ctx->can_ack = mp_opt.mp_capable;
+			if (mp_opt.mp_capable)
+				mptcp_subflow_fully_established(ctx, &mp_opt);
 		} else if (ctx->mp_join) {
 			struct mptcp_sock *owner;
 
@@ -548,9 +613,9 @@ out:
 dispose_child:
 	subflow_drop_ctx(child);
 	tcp_rsk(req)->drop_req = true;
-	tcp_send_active_reset(child, GFP_ATOMIC);
 	inet_csk_prepare_for_destroy_sock(child);
 	tcp_done(child);
+	req->rsk_ops->send_reset(sk, skb);
 
 	/* The last child reference will be released by the caller */
 	return child;
@@ -562,7 +627,8 @@ enum mapping_status {
 	MAPPING_OK,
 	MAPPING_INVALID,
 	MAPPING_EMPTY,
-	MAPPING_DATA_FIN
+	MAPPING_DATA_FIN,
+	MAPPING_DUMMY
 };
 
 static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq)
@@ -614,7 +680,8 @@ static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
 	return true;
 }
 
-static enum mapping_status get_mapping_status(struct sock *ssk)
+static enum mapping_status get_mapping_status(struct sock *ssk,
+					      struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 	struct mptcp_ext *mpext;
@@ -626,6 +693,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
 	if (!skb)
 		return MAPPING_EMPTY;
 
+	if (mptcp_check_fallback(ssk))
+		return MAPPING_DUMMY;
+
 	mpext = mptcp_get_ext(skb);
 	if (!mpext || !mpext->use_map) {
 		if (!subflow->map_valid && !skb->len) {
@@ -661,7 +731,8 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
 
 	if (mpext->data_fin == 1) {
 		if (data_len == 1) {
-			pr_debug("DATA_FIN with no payload");
+			mptcp_update_rcv_data_fin(msk, mpext->data_seq);
+			pr_debug("DATA_FIN with no payload seq=%llu", mpext->data_seq);
 			if (subflow->map_valid) {
 				/* A DATA_FIN might arrive in a DSS
 				 * option before the previous mapping
@@ -673,6 +744,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk)
 			} else {
 				return MAPPING_DATA_FIN;
 			}
+		} else {
+			mptcp_update_rcv_data_fin(msk, mpext->data_seq + data_len);
+			pr_debug("DATA_FIN with mapping seq=%llu", mpext->data_seq + data_len);
 		}
 
 		/* Adjust for DATA_FIN using 1 byte of sequence space */
@@ -761,12 +835,22 @@ static bool subflow_check_data_avail(struct sock *ssk)
 		u64 ack_seq;
 		u64 old_ack;
 
-		status = get_mapping_status(ssk);
+		status = get_mapping_status(ssk, msk);
 		pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
 		if (status == MAPPING_INVALID) {
 			ssk->sk_err = EBADMSG;
 			goto fatal;
 		}
+		if (status == MAPPING_DUMMY) {
+			__mptcp_do_fallback(msk);
+			skb = skb_peek(&ssk->sk_receive_queue);
+			subflow->map_valid = 1;
+			subflow->map_seq = READ_ONCE(msk->ack_seq);
+			subflow->map_data_len = skb->len;
+			subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq -
+						   subflow->ssn_offset;
+			return true;
+		}
 
 		if (status != MAPPING_OK)
 			return false;
@@ -889,15 +973,20 @@ void mptcp_space(const struct sock *ssk, int *space, int *full_space)
 static void subflow_data_ready(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	u16 state = 1 << inet_sk_state_load(sk);
 	struct sock *parent = subflow->conn;
+	struct mptcp_sock *msk;
 
-	if (!subflow->mp_capable && !subflow->mp_join) {
-		subflow->tcp_data_ready(sk);
-
+	msk = mptcp_sk(parent);
+	if (state & TCPF_LISTEN) {
+		set_bit(MPTCP_DATA_READY, &msk->flags);
 		parent->sk_data_ready(parent);
 		return;
 	}
 
+	WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
+		     !subflow->mp_join && !(state & TCPF_CLOSE));
+
 	if (mptcp_subflow_data_available(sk))
 		mptcp_data_ready(parent, sk);
 }
@@ -974,19 +1063,34 @@ int __mptcp_subflow_connect(struct sock *sk, int ifindex,
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	struct mptcp_subflow_context *subflow;
 	struct sockaddr_storage addr;
+	int local_id = loc->id;
 	struct socket *sf;
+	struct sock *ssk;
 	u32 remote_token;
 	int addrlen;
 	int err;
 
-	if (sk->sk_state != TCP_ESTABLISHED)
+	if (!mptcp_is_fully_established(sk))
 		return -ENOTCONN;
 
 	err = mptcp_subflow_create_socket(sk, &sf);
 	if (err)
 		return err;
 
-	subflow = mptcp_subflow_ctx(sf->sk);
+	ssk = sf->sk;
+	subflow = mptcp_subflow_ctx(ssk);
+	do {
+		get_random_bytes(&subflow->local_nonce, sizeof(u32));
+	} while (!subflow->local_nonce);
+
+	if (!local_id) {
+		err = mptcp_pm_get_local_id(msk, (struct sock_common *)ssk);
+		if (err < 0)
+			goto failed;
+
+		local_id = err;
+	}
+
 	subflow->remote_key = msk->remote_key;
 	subflow->local_key = msk->local_key;
 	subflow->token = msk->token;
@@ -997,15 +1101,16 @@ int __mptcp_subflow_connect(struct sock *sk, int ifindex,
 	if (loc->family == AF_INET6)
 		addrlen = sizeof(struct sockaddr_in6);
 #endif
-	sf->sk->sk_bound_dev_if = ifindex;
+	ssk->sk_bound_dev_if = ifindex;
 	err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
 	if (err)
 		goto failed;
 
 	mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
-	pr_debug("msk=%p remote_token=%u", msk, remote_token);
+	pr_debug("msk=%p remote_token=%u local_id=%d", msk, remote_token,
+		 local_id);
 	subflow->remote_token = remote_token;
-	subflow->local_id = loc->id;
+	subflow->local_id = local_id;
 	subflow->request_join = 1;
 	subflow->request_bkup = 1;
 	mptcp_info2sockaddr(remote, &addr);
@@ -1032,6 +1137,12 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
 	struct socket *sf;
 	int err;
 
+	/* un-accepted server sockets can reach here - on bad configuration
+	 * bail early to avoid greater trouble later
+	 */
+	if (unlikely(!sk->sk_socket))
+		return -EINVAL;
+
 	err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
 			       &sf);
 	if (err)
@@ -1118,14 +1229,26 @@ static void subflow_state_change(struct sock *sk)
 
 	__subflow_state_change(sk);
 
+	if (subflow_simultaneous_connect(sk)) {
+		mptcp_do_fallback(sk);
+		mptcp_rcv_space_init(mptcp_sk(parent), sk);
+		pr_fallback(mptcp_sk(parent));
+		subflow->conn_finished = 1;
+		if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
+			inet_sk_state_store(parent, TCP_ESTABLISHED);
+			parent->sk_state_change(parent);
+		}
+	}
+
 	/* as recvmsg() does not acquire the subflow socket for ssk selection
 	 * a fin packet carrying a DSS can be unnoticed if we don't trigger
 	 * the data available machinery here.
 	 */
-	if (subflow->mp_capable && mptcp_subflow_data_available(sk))
+	if (mptcp_subflow_data_available(sk))
 		mptcp_data_ready(parent, sk);
 
-	if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
+	if (__mptcp_check_fallback(mptcp_sk(parent)) &&
+	    !(parent->sk_shutdown & RCV_SHUTDOWN) &&
 	    !subflow->rx_eof && subflow_is_done(sk)) {
 		subflow->rx_eof = 1;
 		mptcp_subflow_eof(parent);
@@ -1255,10 +1378,10 @@ static int subflow_ops_init(struct request_sock_ops *subflow_ops)
 	return 0;
 }
 
-void mptcp_subflow_init(void)
+void __init mptcp_subflow_init(void)
 {
-	subflow_request_sock_ops = tcp_request_sock_ops;
-	if (subflow_ops_init(&subflow_request_sock_ops) != 0)
+	mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
+	if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
 		panic("MPTCP: failed to init subflow request sock ops\n");
 
 	subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
@@ -1268,7 +1391,6 @@ void mptcp_subflow_init(void)
 	subflow_specific.conn_request = subflow_v4_conn_request;
 	subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
 	subflow_specific.sk_rx_dst_set = subflow_finish_connect;
-	subflow_specific.rebuild_header = subflow_rebuild_header;
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 	subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
@@ -1278,7 +1400,6 @@ void mptcp_subflow_init(void)
 	subflow_v6_specific.conn_request = subflow_v6_conn_request;
 	subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
 	subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
-	subflow_v6_specific.rebuild_header = subflow_rebuild_header;
 
 	subflow_v6m_specific = subflow_v6_specific;
 	subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;