Commit 49fb2f33 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'mptcp-some-fallback-fixes' 



Paolo Abeni says:

====================
mptcp: some fallback fixes

pktdrill pointed-out we currently don't handle properly some
fallback scenario for MP_JOIN subflows

The first patch addresses such issue.

Patch 2/2 fixes a related pre-existing issue that is more
evident after 1/2: we could keep using for MPTCP signaling
closed subflows.
====================

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 16cb3653 0e4f35d7

net/mptcp/options.c

+25 −7
Original line number Diff line number Diff line
@@ -626,6 +626,12 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, 
	if (unlikely(mptcp_check_fallback(sk)))

		return false;



	/* prevent adding of any MPTCP related options on reset packet

	 * until we support MP_TCPRST/MP_FASTCLOSE

	 */

	if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))

		return false;



	if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))

		ret = true;

	else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
@@ -676,7 +682,7 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, 
	return false;

}



static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk,

static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,

				    struct mptcp_subflow_context *subflow,

				    struct sk_buff *skb,

				    struct mptcp_options_received *mp_opt)
@@ -693,15 +699,20 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, 
		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&

		    subflow->mp_join && mp_opt->mp_join &&

		    READ_ONCE(msk->pm.server_side))

			tcp_send_ack(sk);

			tcp_send_ack(ssk);

		goto fully_established;

	}



	/* we should process OoO packets before the first subflow is fully

	 * established, but not expected for MP_JOIN subflows

	/* we must process OoO packets before the first subflow is fully

	 * established. OoO packets are instead a protocol violation

	 * for MP_JOIN subflows as the peer must not send any data

	 * before receiving the forth ack - cfr. RFC 8684 section 3.2.

	 */

	if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1)

	if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {

		if (subflow->mp_join)

			goto reset;

		return subflow->mp_capable;

	}



	if (mp_opt->dss && mp_opt->use_ack) {

		/* subflows are fully established as soon as we get any
@@ -713,9 +724,12 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, 
	}



	/* If the first established packet does not contain MP_CAPABLE + data

	 * then fallback to TCP

	 * then fallback to TCP. Fallback scenarios requires a reset for

	 * MP_JOIN subflows.

	 */

	if (!mp_opt->mp_capable) {

		if (subflow->mp_join)

			goto reset;

		subflow->mp_capable = 0;

		pr_fallback(msk);

		__mptcp_do_fallback(msk);
@@ -732,12 +746,16 @@ fully_established: 


	subflow->pm_notified = 1;

	if (subflow->mp_join) {

		clear_3rdack_retransmission(sk);

		clear_3rdack_retransmission(ssk);

		mptcp_pm_subflow_established(msk, subflow);

	} else {

		mptcp_pm_fully_established(msk);

	}

	return true;



reset:

	mptcp_subflow_reset(ssk);

	return false;

}



static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)

net/mptcp/protocol.c

+17 −0
Original line number Diff line number Diff line
@@ -1383,6 +1383,20 @@ static void pm_work(struct mptcp_sock *msk) 
	spin_unlock_bh(&msk->pm.lock);

}



static void __mptcp_close_subflow(struct mptcp_sock *msk)

{

	struct mptcp_subflow_context *subflow, *tmp;



	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);



		if (inet_sk_state_load(ssk) != TCP_CLOSE)

			continue;



		__mptcp_close_ssk((struct sock *)msk, ssk, subflow, 0);

	}

}



static void mptcp_worker(struct work_struct *work)

{

	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
@@ -1400,6 +1414,9 @@ static void mptcp_worker(struct work_struct *work) 
	mptcp_clean_una(sk);

	mptcp_check_data_fin_ack(sk);

	__mptcp_flush_join_list(msk);

	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))

		__mptcp_close_subflow(msk);



	__mptcp_move_skbs(msk);



	if (msk->pm.status)

net/mptcp/protocol.h

+2 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ 
#define MPTCP_WORK_RTX		2

#define MPTCP_WORK_EOF		3

#define MPTCP_FALLBACK_DONE	4

#define MPTCP_WORK_CLOSE_SUBFLOW 5



struct mptcp_options_received {

	u64	sndr_key;
@@ -348,6 +349,7 @@ void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow, 
				     struct mptcp_options_received *mp_opt);

bool mptcp_subflow_data_available(struct sock *sk);

void __init mptcp_subflow_init(void);

void mptcp_subflow_reset(struct sock *ssk);



/* called with sk socket lock held */

int __mptcp_subflow_connect(struct sock *sk, int ifindex,

net/mptcp/subflow.c

+14 −2
Original line number Diff line number Diff line
@@ -270,6 +270,19 @@ static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow) 
	return thmac == subflow->thmac;

}



void mptcp_subflow_reset(struct sock *ssk)

{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);

	struct sock *sk = subflow->conn;



	tcp_set_state(ssk, TCP_CLOSE);

	tcp_send_active_reset(ssk, GFP_ATOMIC);

	tcp_done(ssk);

	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&

	    schedule_work(&mptcp_sk(sk)->work))

		sock_hold(sk);

}



static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)

{

	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
@@ -342,8 +355,7 @@ fallback: 
	return;



do_reset:

	tcp_send_active_reset(sk, GFP_ATOMIC);

	tcp_done(sk);

	mptcp_subflow_reset(sk);

}



struct request_sock_ops mptcp_subflow_request_sock_ops;

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