Commit 93d43e58 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'mptcp-fix-MP_JOIN-failure-handling' 



Paolo Abeni says:

====================
mptcp: fix MP_JOIN failure handling

Currently if we hit an MP_JOIN failure on the third ack, the child socket is
closed with reset, but the request socket is not deleted, causing weird
behaviors.

The main problem is that MPTCP's MP_JOIN code needs to plug it's own
'valid 3rd ack' checks and the current TCP callbacks do not allow that.

This series tries to address the above shortcoming introducing a new MPTCP
specific bit in a 'struct tcp_request_sock' hole, and leveraging that to allow
tcp_check_req releasing the request socket when needed.

The above allows cleaning-up a bit current MPTCP hooking in tcp_check_req().

An alternative solution, possibly cleaner but more invasive, would be
changing the 'bool *own_req' syn_recv_sock() argument into 'int *req_status'
and let MPTCP set it to 'REQ_DROP'.

v1 -> v2:
 - be more conservative about drop_req initialization

RFC -> v1:
 - move the drop_req bit inside tcp_request_sock (Eric)
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents ca1c933b 729cd643

include/linux/tcp.h

+3 −0
Original line number Diff line number Diff line
@@ -120,6 +120,9 @@ struct tcp_request_sock { 
	u64				snt_synack; /* first SYNACK sent time */

	bool				tfo_listener;

	bool				is_mptcp;

#if IS_ENABLED(CONFIG_MPTCP)

	bool				drop_req;

#endif

	u32				txhash;

	u32				rcv_isn;

	u32				snt_isn;

include/net/inet_connection_sock.h

+8 −0
Original line number Diff line number Diff line
@@ -287,6 +287,14 @@ static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk) 
void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);

void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req);



static inline void inet_csk_prepare_for_destroy_sock(struct sock *sk)

{

	/* The below has to be done to allow calling inet_csk_destroy_sock */

	sock_set_flag(sk, SOCK_DEAD);

	percpu_counter_inc(sk->sk_prot->orphan_count);

	inet_sk(sk)->inet_num = 0;

}



void inet_csk_destroy_sock(struct sock *sk);

void inet_csk_prepare_forced_close(struct sock *sk);

include/net/mptcp.h

+10 −7
Original line number Diff line number Diff line
@@ -68,6 +68,11 @@ static inline bool rsk_is_mptcp(const struct request_sock *req) 
	return tcp_rsk(req)->is_mptcp;

}



static inline bool rsk_drop_req(const struct request_sock *req)

{

	return tcp_rsk(req)->is_mptcp && tcp_rsk(req)->drop_req;

}



void mptcp_space(const struct sock *ssk, int *space, int *full_space);

bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,

		       unsigned int *size, struct mptcp_out_options *opts);
@@ -121,8 +126,6 @@ static inline bool mptcp_skb_can_collapse(const struct sk_buff *to, 
				 skb_ext_find(from, SKB_EXT_MPTCP));

}



bool mptcp_sk_is_subflow(const struct sock *sk);



void mptcp_seq_show(struct seq_file *seq);

#else
@@ -140,6 +143,11 @@ static inline bool rsk_is_mptcp(const struct request_sock *req) 
	return false;

}



static inline bool rsk_drop_req(const struct request_sock *req)

{

	return false;

}



static inline void mptcp_parse_option(const struct sk_buff *skb,

				      const unsigned char *ptr, int opsize,

				      struct tcp_options_received *opt_rx)
@@ -190,11 +198,6 @@ static inline bool mptcp_skb_can_collapse(const struct sk_buff *to, 
	return true;

}



static inline bool mptcp_sk_is_subflow(const struct sock *sk)

{

	return false;

}



static inline void mptcp_space(const struct sock *ssk, int *s, int *fs) { }

static inline void mptcp_seq_show(struct seq_file *seq) { }

#endif /* CONFIG_MPTCP */

net/ipv4/inet_connection_sock.c

+1 −5
Original line number Diff line number Diff line
@@ -896,11 +896,7 @@ void inet_csk_prepare_forced_close(struct sock *sk) 
	/* sk_clone_lock locked the socket and set refcnt to 2 */

	bh_unlock_sock(sk);

	sock_put(sk);



	/* The below has to be done to allow calling inet_csk_destroy_sock */

	sock_set_flag(sk, SOCK_DEAD);

	percpu_counter_inc(sk->sk_prot->orphan_count);

	inet_sk(sk)->inet_num = 0;

	inet_csk_prepare_for_destroy_sock(sk);

}

EXPORT_SYMBOL(inet_csk_prepare_forced_close);

net/ipv4/tcp_minisocks.c

+1 −1
Original line number Diff line number Diff line
@@ -774,7 +774,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 
	if (!child)

		goto listen_overflow;



	if (own_req && sk_is_mptcp(child) && mptcp_sk_is_subflow(child)) {

	if (own_req && rsk_drop_req(req)) {

		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);

		inet_csk_reqsk_queue_drop_and_put(sk, req);

		return child;

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