Commit a6574302 authored by Mat Martineau's avatar Mat Martineau Committed by David S. Miller
Browse files

mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags 



When setting up a subflow's flags for sending MP_PRIO MPTCP options, the
subflow socket lock was not held while reading and modifying several
struct members that are also read and modified in mptcp_write_options().

Acquire the subflow socket lock earlier and send the MP_PRIO ACK with
that lock already acquired. Add a new variant of the
mptcp_subflow_send_ack() helper to use with the subflow lock held.

Fixes: 06706542 ("mptcp: add the outgoing MP_PRIO support")
Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c21b50d5

net/mptcp/pm_netlink.c

+4 −1
Original line number Diff line number Diff line
@@ -728,11 +728,13 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk, 
	mptcp_for_each_subflow(msk, subflow) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);

		struct mptcp_addr_info local;

		bool slow;



		local_address((struct sock_common *)ssk, &local);

		if (!mptcp_addresses_equal(&local, addr, addr->port))

			continue;



		slow = lock_sock_fast(ssk);

		if (subflow->backup != bkup)

			msk->last_snd = NULL;

		subflow->backup = bkup;
@@ -740,7 +742,8 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk, 
		subflow->request_bkup = bkup;



		pr_debug("send ack for mp_prio");

		mptcp_subflow_send_ack(ssk);

		__mptcp_subflow_send_ack(ssk);

		unlock_sock_fast(ssk, slow);



		return 0;

	}

net/mptcp/protocol.c

+7 −2
Original line number Diff line number Diff line
@@ -506,13 +506,18 @@ static inline bool tcp_can_send_ack(const struct sock *ssk) 
	       (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN));

}



void __mptcp_subflow_send_ack(struct sock *ssk)

{

	if (tcp_can_send_ack(ssk))

		tcp_send_ack(ssk);

}



void mptcp_subflow_send_ack(struct sock *ssk)

{

	bool slow;



	slow = lock_sock_fast(ssk);

	if (tcp_can_send_ack(ssk))

		tcp_send_ack(ssk);

	__mptcp_subflow_send_ack(ssk);

	unlock_sock_fast(ssk, slow);

}

net/mptcp/protocol.h

+1 −0
Original line number Diff line number Diff line
@@ -607,6 +607,7 @@ void __init mptcp_subflow_init(void); 
void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how);

void mptcp_close_ssk(struct sock *sk, struct sock *ssk,

		     struct mptcp_subflow_context *subflow);

void __mptcp_subflow_send_ack(struct sock *ssk);

void mptcp_subflow_send_ack(struct sock *ssk);

void mptcp_subflow_reset(struct sock *ssk);

void mptcp_subflow_queue_clean(struct sock *ssk);