Re: [MPTCP] [RFC PATCH v3 03/16] mptcp: Add MPTCP socket stubs

[Krystad, Peter <peter.krystad at intel.com>]

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On Mon, 2018-10-08 at 11:11 -0700, Christoph Paasch wrote:
> On 05/10/18 - 15:59:05, Mat Martineau wrote:
> > From: Peter Krystad <peter.krystad(a)intel.com>
> > 
> > Implements the infrastructure for MPTCP sockets.
> > 
> > MPTCP sockets open one in-kernel TCP socket per subflow. These subflow
> > sockets are only managed by the MPTCP socket that owns them and are not
> > visible from userspace. This commit allows a userspace program to open
> > an MPTCP socket with:
> > 
> >   sock = socket(AF_INET, SOCK_STREAM, IPPROTO_MPTCP);
> 
> Have you considered AF_MULTIPATH instead?

No. But that is a good suggestion.

Peter.


> Because, MPTCP does not really care about IP-address family. Thus, it might
> make sense here.
> 
> 
> Christoph
> 
> > 
> > The resulting socket is simply a wrapper around a single regular TCP
> > socket, without any of the MPTCP protocol implemented over the wire.
> > 
> > Signed-off-by: Mat Martineau <mathew.j.martineau(a)linux.intel.com>
> > ---
> >  include/net/mptcp.h  |  33 ++++++++++
> >  net/Kconfig          |   1 +
> >  net/Makefile         |   1 +
> >  net/mptcp/Kconfig    |  10 ++++
> >  net/mptcp/Makefile   |   3 +
> >  net/mptcp/protocol.c | 139 +++++++++++++++++++++++++++++++++++++++++++
> >  6 files changed, 187 insertions(+)
> >  create mode 100644 include/net/mptcp.h
> >  create mode 100644 net/mptcp/Kconfig
> >  create mode 100644 net/mptcp/Makefile
> >  create mode 100644 net/mptcp/protocol.c
> > 
> > diff --git a/include/net/mptcp.h b/include/net/mptcp.h
> > new file mode 100644
> > index 000000000000..7f7b18b000fe
> > --- /dev/null
> > +++ b/include/net/mptcp.h
> > @@ -0,0 +1,33 @@
> > +/*
> > + * Multipath TCP
> > + *
> > + * Copyright (c) 2017, Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> > + * more details.
> > + */
> > +
> > +#ifndef __NET_MPTCP_H
> > +#define __NET_MPTCP_H
> > +
> > +#include <linux/tcp.h>
> > +
> > +/* MPTCP connection sock */
> > +struct mptcp_sock {
> > +	/* inet_connection_sock must be the first member */
> > +	struct	inet_connection_sock sk;
> > +	struct	socket *subflow;
> > +};
> > +
> > +static inline struct mptcp_sock *mptcp_sk(const struct sock *sk)
> > +{
> > +	return (struct mptcp_sock *)sk;
> > +}
> > +
> > +#endif /* __NET_MPTCP_H */
> > diff --git a/net/Kconfig b/net/Kconfig
> > index 228dfa382eec..274282e9b742 100644
> > --- a/net/Kconfig
> > +++ b/net/Kconfig
> > @@ -89,6 +89,7 @@ if INET
> >  source "net/ipv4/Kconfig"
> >  source "net/ipv6/Kconfig"
> >  source "net/netlabel/Kconfig"
> > +source "net/mptcp/Kconfig"
> >  
> >  endif # if INET
> >  
> > diff --git a/net/Makefile b/net/Makefile
> > index bdaf53925acd..1673aab222d8 100644
> > --- a/net/Makefile
> > +++ b/net/Makefile
> > @@ -87,3 +87,4 @@ endif
> >  obj-$(CONFIG_QRTR)		+= qrtr/
> >  obj-$(CONFIG_NET_NCSI)		+= ncsi/
> >  obj-$(CONFIG_XDP_SOCKETS)	+= xdp/
> > +obj-$(CONFIG_MPTCP)		+= mptcp/
> > diff --git a/net/mptcp/Kconfig b/net/mptcp/Kconfig
> > new file mode 100644
> > index 000000000000..8e48190e5fed
> > --- /dev/null
> > +++ b/net/mptcp/Kconfig
> > @@ -0,0 +1,10 @@
> > +
> > +config MPTCP
> > +	bool "Multipath TCP"
> > +	depends on INET
> > +	---help---
> > +	  Multipath TCP (MPTCP) connections send and receive data over multiple
> > +	  subflows in order to utilize multiple network paths. Each subflow
> > +	  uses the TCP protocol, and TCP options carry header information for
> > +	  MPTCP.
> > +
> > diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
> > new file mode 100644
> > index 000000000000..5624e7d51d48
> > --- /dev/null
> > +++ b/net/mptcp/Makefile
> > @@ -0,0 +1,3 @@
> > +obj-$(CONFIG_MPTCP) += mptcp.o
> > +
> > +mptcp-y := protocol.o
> > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> > new file mode 100644
> > index 000000000000..c1eb4afc3ca4
> > --- /dev/null
> > +++ b/net/mptcp/protocol.c
> > @@ -0,0 +1,139 @@
> > +/*
> > + * Multipath TCP
> > + *
> > + * Copyright (c) 2017, Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> > + * more details.
> > + */
> > +
> > +#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>
> > +
> > +static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> > +{
> > +	struct mptcp_sock *msk = mptcp_sk(sk);
> > +	struct socket *subflow = msk->subflow;
> > +
> > +	pr_debug("subflow=%p", subflow->sk);
> > +
> > +	return sock_sendmsg(subflow, msg);
> > +}
> > +
> > +static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
> > +			 int nonblock, int flags, int *addr_len)
> > +{
> > +	struct mptcp_sock *msk = mptcp_sk(sk);
> > +	struct socket *subflow = msk->subflow;
> > +
> > +	pr_debug("subflow=%p", subflow->sk);
> > +
> > +	return sock_recvmsg(subflow, msg, flags);
> > +}
> > +
> > +static int mptcp_init_sock(struct sock *sk)
> > +{
> > +	struct mptcp_sock *msk = mptcp_sk(sk);
> > +	struct socket *sf;
> > +	int err;
> > +
> > +	pr_debug("msk=%p", msk);
> > +
> > +	err = sock_create_kern(&init_net, PF_INET, SOCK_STREAM, IPPROTO_TCP,
> > +			       &sf);
> > +	if (!err) {
> > +		pr_debug("subflow=%p", sf->sk);
> > +		msk->subflow = sf;
> > +	}
> > +
> > +	return err;
> > +}
> > +
> > +static void mptcp_close(struct sock *sk, long timeout)
> > +{
> > +	struct mptcp_sock *msk = mptcp_sk(sk);
> > +
> > +	if (msk->subflow) {
> > +		pr_debug("subflow=%p", msk->subflow->sk);
> > +		sock_release(msk->subflow);
> > +	}
> > +}
> > +
> > +static int mptcp_connect(struct sock *sk, struct sockaddr *saddr, int len)
> > +{
> > +	struct mptcp_sock *msk = mptcp_sk(sk);
> > +	int err;
> > +
> > +	saddr->sa_family = AF_INET;
> > +
> > +	pr_debug("msk=%p, subflow=%p", msk, msk->subflow->sk);
> > +
> > +	err = kernel_connect(msk->subflow, saddr, len, 0);
> > +
> > +	sk->sk_state = TCP_ESTABLISHED;
> > +
> > +	return err;
> > +}
> > +
> > +static struct proto mptcp_prot = {
> > +	.name		= "MPTCP",
> > +	.owner		= THIS_MODULE,
> > +	.init		= mptcp_init_sock,
> > +	.close		= mptcp_close,
> > +	.accept		= inet_csk_accept,
> > +	.connect	= mptcp_connect,
> > +	.shutdown	= tcp_shutdown,
> > +	.sendmsg	= mptcp_sendmsg,
> > +	.recvmsg	= mptcp_recvmsg,
> > +	.hash		= inet_hash,
> > +	.unhash		= inet_unhash,
> > +	.get_port	= inet_csk_get_port,
> > +	.obj_size	= sizeof(struct mptcp_sock),
> > +	.no_autobind	= 1,
> > +};
> > +
> > +static struct inet_protosw mptcp_protosw = {
> > +	.type		= SOCK_STREAM,
> > +	.protocol	= IPPROTO_MPTCP,
> > +	.prot		= &mptcp_prot,
> > +	.ops		= &inet_stream_ops,
> > +};
> > +
> > +static int __init mptcp_init(void)
> > +{
> > +	int err;
> > +
> > +	err = proto_register(&mptcp_prot, 1);
> > +	if (err)
> > +		return err;
> > +
> > +	inet_register_protosw(&mptcp_protosw);
> > +
> > +	return 0;
> > +}
> > +
> > +static void __exit mptcp_exit(void)
> > +{
> > +	inet_unregister_protosw(&mptcp_protosw);
> > +	proto_unregister(&mptcp_prot);
> > +}
> > +
> > +module_init(mptcp_init);
> > +module_exit(mptcp_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_MPTCP);
> > +MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_MPTCP);
> > -- 
> > 2.19.1
> > 
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> > https://lists.01.org/mailman/listinfo/mptcp
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