1 files changed, 119 insertions, 0 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
new file mode 100644
index 000000000000..bf8139353653
--- /dev/null
+++ b/net/mptcp/subflow.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2017 - 2019, Intel Corporation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <net/sock.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/protocol.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include "protocol.h"
+
+int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
+{
+	struct mptcp_subflow_context *subflow;
+	struct net *net = sock_net(sk);
+	struct socket *sf;
+	int err;
+
+	err = sock_create_kern(net, PF_INET, SOCK_STREAM, IPPROTO_TCP, &sf);
+	if (err)
+		return err;
+
+	lock_sock(sf->sk);
+
+	/* kernel sockets do not by default acquire net ref, but TCP timer
+	 * needs it.
+	 */
+	sf->sk->sk_net_refcnt = 1;
+	get_net(net);
+	this_cpu_add(*net->core.sock_inuse, 1);
+	err = tcp_set_ulp(sf->sk, "mptcp");
+	release_sock(sf->sk);
+
+	if (err)
+		return err;
+
+	subflow = mptcp_subflow_ctx(sf->sk);
+	pr_debug("subflow=%p", subflow);
+
+	*new_sock = sf;
+	subflow->conn = sk;
+
+	return 0;
+}
+
+static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
+							gfp_t priority)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct mptcp_subflow_context *ctx;
+
+	ctx = kzalloc(sizeof(*ctx), priority);
+	if (!ctx)
+		return NULL;
+
+	rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
+
+	pr_debug("subflow=%p", ctx);
+
+	ctx->tcp_sock = sk;
+
+	return ctx;
+}
+
+static int subflow_ulp_init(struct sock *sk)
+{
+	struct mptcp_subflow_context *ctx;
+	struct tcp_sock *tp = tcp_sk(sk);
+	int err = 0;
+
+	/* disallow attaching ULP to a socket unless it has been
+	 * created with sock_create_kern()
+	 */
+	if (!sk->sk_kern_sock) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	ctx = subflow_create_ctx(sk, GFP_KERNEL);
+	if (!ctx) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
+
+	tp->is_mptcp = 1;
+out:
+	return err;
+}
+
+static void subflow_ulp_release(struct sock *sk)
+{
+	struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk);
+
+	if (!ctx)
+		return;
+
+	kfree_rcu(ctx, rcu);
+}
+
+static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
+	.name		= "mptcp",
+	.owner		= THIS_MODULE,
+	.init		= subflow_ulp_init,
+	.release	= subflow_ulp_release,
+};
+
+void mptcp_subflow_init(void)
+{
+	if (tcp_register_ulp(&subflow_ulp_ops) != 0)
+		panic("MPTCP: failed to register subflows to ULP\n");
+}