[MPTCP] [PATCH v2 6/6] mptcp: Add IPv6 support

[MPTCP] [PATCH v2 6/6] mptcp: Add IPv6 support

[Peter Krystad]

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Add hooks for IPv6 as needed and initialize MPTCP
IPv6 support.

Signed-off-by: Peter Krystad <peter.krystad(a)linux.intel.com>
---
 include/net/mptcp.h  | 10 +++++++
 net/ipv6/tcp_ipv6.c  |  7 +++++
 net/mptcp/ctrl.c     | 11 ++++++++
 net/mptcp/protocol.c | 67 ++++++++++++++++++++++++++++++++++++++------
 net/mptcp/protocol.h |  3 ++
 net/mptcp/subflow.c  | 61 ++++++++++++++++++++++++++++++++++++++--
 6 files changed, 149 insertions(+), 10 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 1196a5588ce1..d19bc31a6250 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -152,4 +152,14 @@ static inline bool mptcp_sk_is_subflow(const struct sock *sk)
 
 static inline void mptcp_seq_show(struct seq_file *seq) { }
 #endif /* CONFIG_MPTCP */
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+int mptcpv6_init(void);
+#elif IS_ENABLED(CONFIG_IPV6)
+static inline int mptcpv6_init(void)
+{
+	return 0;
+}
+#endif
+
 #endif /* __NET_MPTCP_H */
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 50f6f21bbdb1..10d1c033d458 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2109,9 +2109,16 @@ int __init tcpv6_init(void)
 	ret = register_pernet_subsys(&tcpv6_net_ops);
 	if (ret)
 		goto out_tcpv6_protosw;
+
+	ret = mptcpv6_init();
+	if (ret)
+		goto out_tcpv6_pernet_subsys;
+
 out:
 	return ret;
 
+out_tcpv6_pernet_subsys:
+	unregister_pernet_subsys(&tcpv6_net_ops);
 out_tcpv6_protosw:
 	inet6_unregister_protosw(&tcpv6_protosw);
 out_tcpv6_protocol:
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 6023c9f722ea..8e39585d37f3 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -117,3 +117,14 @@ void __init mptcp_init(void)
 	if (register_pernet_subsys(&mptcp_pernet_ops) < 0)
 		panic("Failed to register MPTCP pernet subsystem.\n");
 }
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+int __init mptcpv6_init(void)
+{
+	int err;
+
+	err = mptcp_proto_v6_init();
+
+	return err;
+}
+#endif
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 323b3e65dba2..0bb9af3bef02 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -16,6 +16,9 @@
 #include <net/inet_hashtables.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+#include <net/transp_v6.h>
+#endif
 #include <net/mptcp.h>
 #include "protocol.h"
 #include "mib.h"
@@ -1106,10 +1109,7 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 {
 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
 	struct socket *ssock;
-	int err = -ENOTSUPP;
-
-	if (uaddr->sa_family != AF_INET) // @@ allow only IPv4 for now
-		return err;
+	int err;
 
 	ssock = mptcp_socket_create_get(msk);
 	if (IS_ERR(ssock))
@@ -1125,10 +1125,7 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 {
 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
 	struct socket *ssock;
-	int err = -ENOTSUPP;
-
-	if (uaddr->sa_family != AF_INET) // @@ allow only IPv4 for now
-		return err;
+	int err;
 
 	ssock = mptcp_socket_create_get(msk);
 	if (IS_ERR(ssock))
@@ -1194,6 +1191,30 @@ static int mptcp_v4_getname(struct socket *sock, struct sockaddr *uaddr,
 	return ret;
 }
 
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static int mptcp_v6_getname(struct socket *sock, struct sockaddr *uaddr,
+			    int peer)
+{
+	int ret;
+
+	if (sock->sk->sk_prot == &tcpv6_prot) {
+		/* we are being invoked from __sys_accept4 after
+		 * mptcp_accept() has accepted a non-mp-capable
+		 * subflow: sk is a tcp_sk, not mptcp.
+		 *
+		 * Hand the socket over to tcp so all further
+		 * socket ops bypass mptcp.
+		 */
+		sock->ops = &inet6_stream_ops;
+		return sock->ops->getname(sock, uaddr, peer);
+	}
+
+	ret = mptcp_getname(sock, uaddr, peer);
+
+	return ret;
+}
+#endif
+
 static int mptcp_listen(struct socket *sock, int backlog)
 {
 	struct mptcp_sock *msk = mptcp_sk(sock->sk);
@@ -1325,3 +1346,33 @@ void mptcp_proto_init(void)
 
 	inet_register_protosw(&mptcp_protosw);
 }
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static struct proto_ops mptcp_v6_stream_ops;
+
+static struct inet_protosw mptcp_v6_protosw = {
+	.type		= SOCK_STREAM,
+	.protocol	= IPPROTO_MPTCP,
+	.prot		= &mptcp_prot,
+	.ops		= &mptcp_v6_stream_ops,
+	.flags		= INET_PROTOSW_ICSK,
+};
+
+int mptcp_proto_v6_init(void)
+{
+	int err;
+
+	mptcp_v6_stream_ops = inet6_stream_ops;
+	mptcp_v6_stream_ops.bind = mptcp_bind;
+	mptcp_v6_stream_ops.connect = mptcp_stream_connect;
+	mptcp_v6_stream_ops.poll = mptcp_poll;
+	mptcp_v6_stream_ops.accept = mptcp_stream_accept;
+	mptcp_v6_stream_ops.getname = mptcp_v6_getname;
+	mptcp_v6_stream_ops.listen = mptcp_listen;
+	mptcp_v6_stream_ops.shutdown = mptcp_shutdown;
+
+	err = inet6_register_protosw(&mptcp_v6_protosw);
+
+	return err;
+}
+#endif
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index c6102ca3c79e..90942e0c3112 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -274,6 +274,9 @@ extern const struct inet_connection_sock_af_ops ipv6_specific;
 #endif
 
 void mptcp_proto_init(void);
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+int mptcp_proto_v6_init(void);
+#endif
 
 struct mptcp_read_arg {
 	struct msghdr *msg;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 586713537124..b945460456b4 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -15,6 +15,9 @@
 #include <net/inet_hashtables.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+#include <net/ip6_route.h>
+#endif
 #include <net/mptcp.h>
 #include "protocol.h"
 #include "mib.h"
@@ -154,6 +157,19 @@ static void subflow_v4_init_req(struct request_sock *req,
 	subflow_init_req(req, sk_listener, skb);
 }
 
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static void subflow_v6_init_req(struct request_sock *req,
+				const struct sock *sk_listener,
+				struct sk_buff *skb)
+{
+	tcp_rsk(req)->is_mptcp = 1;
+
+	tcp_request_sock_ipv6_ops.init_req(req, sk_listener, skb);
+
+	subflow_init_req(req, sk_listener, skb);
+}
+#endif
+
 /* validate received truncated hmac and create hmac for third ACK */
 static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
 {
@@ -234,6 +250,31 @@ static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
+static struct inet_connection_sock_af_ops subflow_v6_specific;
+
+static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+	pr_debug("subflow=%p", subflow);
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return tcp_v4_conn_request(sk, skb);
+
+	if (!ipv6_unicast_destination(skb))
+		goto drop;
+
+	return tcp_conn_request(&subflow_request_sock_ops,
+				&subflow_request_sock_ipv6_ops, sk, skb);
+
+drop:
+	tcp_listendrop(sk);
+	return 0; /* don't send reset */
+}
+#endif
+
 /* validate hmac received in third ACK */
 static bool subflow_hmac_valid(const struct request_sock *req,
 			       const struct tcp_options_received *rx_opt)
@@ -690,7 +731,8 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
 	struct socket *sf;
 	int err;
 
-	err = sock_create_kern(net, PF_INET, SOCK_STREAM, IPPROTO_TCP, &sf);
+	err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
+			       &sf);
 	if (err)
 		return err;
 
@@ -774,11 +816,15 @@ static int subflow_ulp_init(struct sock *sk)
 		goto out;
 	}
 
-	pr_debug("subflow=%p", ctx);
+	pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
 
 	tp->is_mptcp = 1;
 	ctx->icsk_af_ops = icsk->icsk_af_ops;
 	icsk->icsk_af_ops = &subflow_specific;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	if (sk->sk_family == AF_INET6)
+		icsk->icsk_af_ops = &subflow_v6_specific;
+#endif
 	ctx->tcp_sk_data_ready = sk->sk_data_ready;
 	sk->sk_data_ready = subflow_data_ready;
 	sk->sk_write_space = subflow_write_space;
@@ -877,6 +923,17 @@ void mptcp_subflow_init(void)
 	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;
+	subflow_request_sock_ipv6_ops.init_req = subflow_v6_init_req;
+
+	subflow_v6_specific = ipv6_specific;
+	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;
+#endif
+
 	mptcp_diag_subflow_init(&subflow_ulp_ops);
 
 	if (tcp_register_ulp(&subflow_ulp_ops) != 0)
-- 
2.17.2