Commit 54f1944e authored by Paolo Abeni's avatar Paolo Abeni Committed by Jakub Kicinski
Browse files

mptcp: factor out mptcp_connect() 



The current MPTCP connect implementation duplicates a bit of inet
code and does not use nor provide a struct proto->connect callback,
which in turn will not fit the upcoming fastopen implementation.

Refactor such implementation to use the common helper, moving the
MPTCP-specific bits into mptcp_connect(). Additionally, avoid an
indirect call to the subflow connect callback.

Note that the fastopen call-path invokes mptcp_connect() while already
holding the subflow socket lock. Explicitly keep track of such path
via a new MPTCP-level flag and handle the locking accordingly.

Additionally, track the connect flags in a new msk field to allow
propagating them to the subflow inet_stream_connect call.

Fixes: d98a82a6 ("mptcp: handle defer connect in mptcp_sendmsg")
Reviewed-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e72e4032

net/mptcp/protocol.c

+70 −66
Original line number Diff line number Diff line
@@ -1698,7 +1698,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 


		lock_sock(ssk);



		msk->connect_flags = (msg->msg_flags & MSG_DONTWAIT) ? O_NONBLOCK : 0;

		msk->is_sendmsg = 1;

		ret = tcp_sendmsg_fastopen(ssk, msg, &copied_syn, len, NULL);

		msk->is_sendmsg = 0;

		copied += copied_syn;

		if (ret == -EINPROGRESS && copied_syn > 0) {

			/* reflect the new state on the MPTCP socket */
@@ -3507,10 +3510,73 @@ static int mptcp_ioctl(struct sock *sk, int cmd, unsigned long arg) 
	return put_user(answ, (int __user *)arg);

}



static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,

					 struct mptcp_subflow_context *subflow)

{

	subflow->request_mptcp = 0;

	__mptcp_do_fallback(msk);

}



static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)

{

	struct mptcp_subflow_context *subflow;

	struct mptcp_sock *msk = mptcp_sk(sk);

	struct socket *ssock;

	int err = -EINVAL;



	ssock = __mptcp_nmpc_socket(msk);

	if (!ssock)

		return -EINVAL;



	mptcp_token_destroy(msk);

	inet_sk_state_store(sk, TCP_SYN_SENT);

	subflow = mptcp_subflow_ctx(ssock->sk);

#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(ssock->sk)->md5sig_info))

		mptcp_subflow_early_fallback(msk, subflow);

#endif

	if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {

		MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);

		mptcp_subflow_early_fallback(msk, subflow);

	}

	if (likely(!__mptcp_check_fallback(msk)))

		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);



	/* if reaching here via the fastopen/sendmsg path, the caller already

	 * acquired the subflow socket lock, too.

	 */

	if (msk->is_sendmsg)

		err = __inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags, 1);

	else

		err = inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags);

	inet_sk(sk)->defer_connect = inet_sk(ssock->sk)->defer_connect;



	/* on successful connect, the msk state will be moved to established by

	 * subflow_finish_connect()

	 */

	if (unlikely(err && err != -EINPROGRESS)) {

		inet_sk_state_store(sk, inet_sk_state_load(ssock->sk));

		return err;

	}



	mptcp_copy_inaddrs(sk, ssock->sk);



	/* unblocking connect, mptcp-level inet_stream_connect will error out

	 * without changing the socket state, update it here.

	 */

	if (err == -EINPROGRESS)

		sk->sk_socket->state = ssock->state;

	return err;

}



static struct proto mptcp_prot = {

	.name		= "MPTCP",

	.owner		= THIS_MODULE,

	.init		= mptcp_init_sock,

	.connect	= mptcp_connect,

	.disconnect	= mptcp_disconnect,

	.close		= mptcp_close,

	.accept		= mptcp_accept,
@@ -3562,78 +3628,16 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) 
	return err;

}



static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,

					 struct mptcp_subflow_context *subflow)

{

	subflow->request_mptcp = 0;

	__mptcp_do_fallback(msk);

}



static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,

				int addr_len, int flags)

{

	struct mptcp_sock *msk = mptcp_sk(sock->sk);

	struct mptcp_subflow_context *subflow;

	struct socket *ssock;

	int err = -EINVAL;

	int ret;



	lock_sock(sock->sk);

	if (uaddr) {

		if (addr_len < sizeof(uaddr->sa_family))

			goto unlock;



		if (uaddr->sa_family == AF_UNSPEC) {

			err = mptcp_disconnect(sock->sk, flags);

			sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;

			goto unlock;

		}

	}



	if (sock->state != SS_UNCONNECTED && msk->subflow) {

		/* pending connection or invalid state, let existing subflow

		 * cope with that

		 */

		ssock = msk->subflow;

		goto do_connect;

	}



	ssock = __mptcp_nmpc_socket(msk);

	if (!ssock)

		goto unlock;



	mptcp_token_destroy(msk);

	inet_sk_state_store(sock->sk, TCP_SYN_SENT);

	subflow = mptcp_subflow_ctx(ssock->sk);

#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(ssock->sk)->md5sig_info))

		mptcp_subflow_early_fallback(msk, subflow);

#endif

	if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {

		MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);

		mptcp_subflow_early_fallback(msk, subflow);

	}

	if (likely(!__mptcp_check_fallback(msk)))

		MPTCP_INC_STATS(sock_net(sock->sk), MPTCP_MIB_MPCAPABLEACTIVE);



do_connect:

	err = ssock->ops->connect(ssock, uaddr, addr_len, flags);

	inet_sk(sock->sk)->defer_connect = inet_sk(ssock->sk)->defer_connect;

	sock->state = ssock->state;



	/* on successful connect, the msk state will be moved to established by

	 * subflow_finish_connect()

	 */

	if (!err || err == -EINPROGRESS)

		mptcp_copy_inaddrs(sock->sk, ssock->sk);

	else

		inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));



unlock:

	mptcp_sk(sock->sk)->connect_flags = flags;

	ret = __inet_stream_connect(sock, uaddr, addr_len, flags, 0);

	release_sock(sock->sk);

	return err;

	return ret;

}



static int mptcp_listen(struct socket *sock, int backlog)

net/mptcp/protocol.h

+3 −1
Original line number Diff line number Diff line
@@ -285,7 +285,9 @@ struct mptcp_sock { 
	u8		mpc_endpoint_id;

	u8		recvmsg_inq:1,

			cork:1,

			nodelay:1;

			nodelay:1,

			is_sendmsg:1;

	int		connect_flags;

	struct work_struct work;

	struct sk_buff  *ooo_last_skb;

	struct rb_root  out_of_order_queue;