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	mptcp: Create SUBFLOW socket for incoming connections
Add subflow_request_sock type that extends tcp_request_sock and add an is_mptcp flag to tcp_request_sock distinguish them. Override the listen() and accept() methods of the MPTCP socket proto_ops so they may act on the subflow socket. Override the conn_request() and syn_recv_sock() handlers in the inet_connection_sock to handle incoming MPTCP SYNs and the ACK to the response SYN. Add handling in tcp_output.c to add MP_CAPABLE to an outgoing SYN-ACK response for a subflow_request_sock. Co-developed-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Co-developed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Florian Westphal <fw@strlen.de> Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net> Co-developed-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com> Signed-off-by: Christoph Paasch <cpaasch@apple.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
		
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						cf7da0d66c
					
				
					 1 changed files with 231 additions and 5 deletions
				
			
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			@ -14,6 +14,9 @@
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#include <net/inet_hashtables.h>
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#include <net/protocol.h>
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#include <net/tcp.h>
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#if IS_ENABLED(CONFIG_MPTCP_IPV6)
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#include <net/transp_v6.h>
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#endif
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#include <net/mptcp.h>
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#include "protocol.h"
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			@ -212,6 +215,90 @@ static void mptcp_close(struct sock *sk, long timeout)
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	sk_common_release(sk);
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}
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static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
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{
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#if IS_ENABLED(CONFIG_MPTCP_IPV6)
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	const struct ipv6_pinfo *ssk6 = inet6_sk(ssk);
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	struct ipv6_pinfo *msk6 = inet6_sk(msk);
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	msk->sk_v6_daddr = ssk->sk_v6_daddr;
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	msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr;
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	if (msk6 && ssk6) {
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		msk6->saddr = ssk6->saddr;
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		msk6->flow_label = ssk6->flow_label;
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	}
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#endif
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	inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num;
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	inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport;
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	inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport;
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	inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr;
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	inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr;
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	inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
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}
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static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
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				 bool kern)
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{
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	struct mptcp_sock *msk = mptcp_sk(sk);
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	struct socket *listener;
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	struct sock *newsk;
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	listener = __mptcp_nmpc_socket(msk);
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	if (WARN_ON_ONCE(!listener)) {
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		*err = -EINVAL;
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		return NULL;
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	}
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	pr_debug("msk=%p, listener=%p", msk, mptcp_subflow_ctx(listener->sk));
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	newsk = inet_csk_accept(listener->sk, flags, err, kern);
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	if (!newsk)
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		return NULL;
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	pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk));
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	if (sk_is_mptcp(newsk)) {
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		struct mptcp_subflow_context *subflow;
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		struct sock *new_mptcp_sock;
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		struct sock *ssk = newsk;
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		subflow = mptcp_subflow_ctx(newsk);
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		lock_sock(sk);
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		local_bh_disable();
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		new_mptcp_sock = sk_clone_lock(sk, GFP_ATOMIC);
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		if (!new_mptcp_sock) {
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			*err = -ENOBUFS;
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			local_bh_enable();
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			release_sock(sk);
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			tcp_close(newsk, 0);
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			return NULL;
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		}
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		mptcp_init_sock(new_mptcp_sock);
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		msk = mptcp_sk(new_mptcp_sock);
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		msk->remote_key = subflow->remote_key;
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		msk->local_key = subflow->local_key;
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		msk->subflow = NULL;
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		newsk = new_mptcp_sock;
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		mptcp_copy_inaddrs(newsk, ssk);
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		list_add(&subflow->node, &msk->conn_list);
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		/* will be fully established at mptcp_stream_accept()
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		 * completion.
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		 */
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		inet_sk_state_store(new_mptcp_sock, TCP_SYN_RECV);
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		bh_unlock_sock(new_mptcp_sock);
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		local_bh_enable();
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		release_sock(sk);
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	}
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	return newsk;
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}
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static int mptcp_get_port(struct sock *sk, unsigned short snum)
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{
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	struct mptcp_sock *msk = mptcp_sk(sk);
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			@ -246,12 +333,21 @@ void mptcp_finish_connect(struct sock *ssk)
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	WRITE_ONCE(msk->local_key, subflow->local_key);
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}
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static void mptcp_sock_graft(struct sock *sk, struct socket *parent)
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{
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	write_lock_bh(&sk->sk_callback_lock);
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	rcu_assign_pointer(sk->sk_wq, &parent->wq);
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	sk_set_socket(sk, parent);
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	sk->sk_uid = SOCK_INODE(parent)->i_uid;
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	write_unlock_bh(&sk->sk_callback_lock);
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}
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static struct proto mptcp_prot = {
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	.name		= "MPTCP",
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	.owner		= THIS_MODULE,
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	.init		= mptcp_init_sock,
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	.close		= mptcp_close,
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	.accept		= inet_csk_accept,
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	.accept		= mptcp_accept,
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	.shutdown	= tcp_shutdown,
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	.sendmsg	= mptcp_sendmsg,
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	.recvmsg	= mptcp_recvmsg,
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			@ -266,10 +362,7 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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{
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	struct mptcp_sock *msk = mptcp_sk(sock->sk);
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	struct socket *ssock;
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	int err = -ENOTSUPP;
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	if (uaddr->sa_family != AF_INET) // @@ allow only IPv4 for now
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		return err;
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	int err;
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	lock_sock(sock->sk);
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	ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE);
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			@ -279,6 +372,8 @@ static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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	}
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	err = ssock->ops->bind(ssock, uaddr, addr_len);
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	if (!err)
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		mptcp_copy_inaddrs(sock->sk, ssock->sk);
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unlock:
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	release_sock(sock->sk);
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			@ -299,14 +394,139 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
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		goto unlock;
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	}
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#ifdef CONFIG_TCP_MD5SIG
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	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
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	 * TCP option space.
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	 */
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	if (rcu_access_pointer(tcp_sk(ssock->sk)->md5sig_info))
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		mptcp_subflow_ctx(ssock->sk)->request_mptcp = 0;
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#endif
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	err = ssock->ops->connect(ssock, uaddr, addr_len, flags);
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	inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
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	mptcp_copy_inaddrs(sock->sk, ssock->sk);
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unlock:
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	release_sock(sock->sk);
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	return err;
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}
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static int mptcp_v4_getname(struct socket *sock, struct sockaddr *uaddr,
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			    int peer)
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{
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	if (sock->sk->sk_prot == &tcp_prot) {
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		/* we are being invoked from __sys_accept4, after
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		 * mptcp_accept() has just accepted a non-mp-capable
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		 * flow: sk is a tcp_sk, not an mptcp one.
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		 *
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		 * Hand the socket over to tcp so all further socket ops
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		 * bypass mptcp.
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		 */
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		sock->ops = &inet_stream_ops;
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	}
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	return inet_getname(sock, uaddr, peer);
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}
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#if IS_ENABLED(CONFIG_MPTCP_IPV6)
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static int mptcp_v6_getname(struct socket *sock, struct sockaddr *uaddr,
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			    int peer)
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{
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	if (sock->sk->sk_prot == &tcpv6_prot) {
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		/* we are being invoked from __sys_accept4 after
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		 * mptcp_accept() has accepted a non-mp-capable
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		 * subflow: sk is a tcp_sk, not mptcp.
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		 *
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		 * Hand the socket over to tcp so all further
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		 * socket ops bypass mptcp.
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		 */
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		sock->ops = &inet6_stream_ops;
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	}
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	return inet6_getname(sock, uaddr, peer);
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}
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#endif
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static int mptcp_listen(struct socket *sock, int backlog)
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{
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	struct mptcp_sock *msk = mptcp_sk(sock->sk);
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	struct socket *ssock;
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	int err;
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	pr_debug("msk=%p", msk);
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	lock_sock(sock->sk);
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	ssock = __mptcp_socket_create(msk, TCP_LISTEN);
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	if (IS_ERR(ssock)) {
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		err = PTR_ERR(ssock);
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		goto unlock;
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	}
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	err = ssock->ops->listen(ssock, backlog);
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	inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk));
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	if (!err)
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		mptcp_copy_inaddrs(sock->sk, ssock->sk);
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unlock:
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	release_sock(sock->sk);
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	return err;
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}
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static bool is_tcp_proto(const struct proto *p)
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{
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#if IS_ENABLED(CONFIG_MPTCP_IPV6)
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	return p == &tcp_prot || p == &tcpv6_prot;
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#else
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	return p == &tcp_prot;
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#endif
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}
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static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
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			       int flags, bool kern)
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{
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	struct mptcp_sock *msk = mptcp_sk(sock->sk);
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	struct socket *ssock;
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	int err;
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	pr_debug("msk=%p", msk);
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	lock_sock(sock->sk);
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	if (sock->sk->sk_state != TCP_LISTEN)
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		goto unlock_fail;
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	ssock = __mptcp_nmpc_socket(msk);
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	if (!ssock)
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		goto unlock_fail;
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	sock_hold(ssock->sk);
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	release_sock(sock->sk);
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	err = ssock->ops->accept(sock, newsock, flags, kern);
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	if (err == 0 && !is_tcp_proto(newsock->sk->sk_prot)) {
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		struct mptcp_sock *msk = mptcp_sk(newsock->sk);
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		struct mptcp_subflow_context *subflow;
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		/* set ssk->sk_socket of accept()ed flows to mptcp socket.
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		 * This is needed so NOSPACE flag can be set from tcp stack.
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		 */
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		list_for_each_entry(subflow, &msk->conn_list, node) {
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			struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
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			if (!ssk->sk_socket)
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				mptcp_sock_graft(ssk, newsock);
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		}
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		inet_sk_state_store(newsock->sk, TCP_ESTABLISHED);
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	}
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	sock_put(ssock->sk);
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	return err;
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unlock_fail:
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	release_sock(sock->sk);
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	return -EINVAL;
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}
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static __poll_t mptcp_poll(struct file *file, struct socket *sock,
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			   struct poll_table_struct *wait)
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{
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			@ -332,6 +552,9 @@ void __init mptcp_init(void)
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	mptcp_stream_ops.bind = mptcp_bind;
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	mptcp_stream_ops.connect = mptcp_stream_connect;
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	mptcp_stream_ops.poll = mptcp_poll;
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	mptcp_stream_ops.accept = mptcp_stream_accept;
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	mptcp_stream_ops.getname = mptcp_v4_getname;
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	mptcp_stream_ops.listen = mptcp_listen;
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	mptcp_subflow_init();
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			@ -371,6 +594,9 @@ int mptcpv6_init(void)
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	mptcp_v6_stream_ops.bind = mptcp_bind;
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	mptcp_v6_stream_ops.connect = mptcp_stream_connect;
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	mptcp_v6_stream_ops.poll = mptcp_poll;
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	mptcp_v6_stream_ops.accept = mptcp_stream_accept;
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	mptcp_v6_stream_ops.getname = mptcp_v6_getname;
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	mptcp_v6_stream_ops.listen = mptcp_listen;
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	err = inet6_register_protosw(&mptcp_v6_protosw);
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	if (err)
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