Commit 322ea377 authored by Matthieu Baerts (NGI0)'s avatar Matthieu Baerts (NGI0) Committed by Jakub Kicinski
Browse files

mptcp: pm: only mark 'subflow' endp as available 



Adding the following warning ...

  WARN_ON_ONCE(msk->pm.local_addr_used == 0)

... before decrementing the local_addr_used counter helped to find a bug
when running the "remove single address" subtest from the mptcp_join.sh
selftests.

Removing a 'signal' endpoint will trigger the removal of all subflows
linked to this endpoint via mptcp_pm_nl_rm_addr_or_subflow() with
rm_type == MPTCP_MIB_RMSUBFLOW. This will decrement the local_addr_used
counter, which is wrong in this case because this counter is linked to
'subflow' endpoints, and here it is a 'signal' endpoint that is being
removed.

Now, the counter is decremented, only if the ID is being used outside
of mptcp_pm_nl_rm_addr_or_subflow(), only for 'subflow' endpoints, and
if the ID is not 0 -- local_addr_used is not taking into account these
ones. This marking of the ID as being available, and the decrement is
done no matter if a subflow using this ID is currently available,
because the subflow could have been closed before.

Fixes: 06faa227 ("mptcp: remove multi addresses and subflows in PM")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarMat Martineau <martineau@kernel.org>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-8-38035d40de5b@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent f448451a

net/mptcp/pm_netlink.c

+17 −9
Original line number Diff line number Diff line
@@ -833,10 +833,10 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk, 
			if (rm_type == MPTCP_MIB_RMSUBFLOW)

				__MPTCP_INC_STATS(sock_net(sk), rm_type);

		}

		if (rm_type == MPTCP_MIB_RMSUBFLOW)

			__set_bit(rm_id ? rm_id : msk->mpc_endpoint_id, msk->pm.id_avail_bitmap);

		else if (rm_type == MPTCP_MIB_RMADDR)



		if (rm_type == MPTCP_MIB_RMADDR)

			__MPTCP_INC_STATS(sock_net(sk), rm_type);



		if (!removed)

			continue;
@@ -846,8 +846,6 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk, 
		if (rm_type == MPTCP_MIB_RMADDR) {

			msk->pm.add_addr_accepted--;

			WRITE_ONCE(msk->pm.accept_addr, true);

		} else if (rm_type == MPTCP_MIB_RMSUBFLOW) {

			msk->pm.local_addr_used--;

		}

	}

}
@@ -1441,6 +1439,14 @@ static bool mptcp_pm_remove_anno_addr(struct mptcp_sock *msk, 
	return ret;

}



static void __mark_subflow_endp_available(struct mptcp_sock *msk, u8 id)

{

	/* If it was marked as used, and not ID 0, decrement local_addr_used */

	if (!__test_and_set_bit(id ? : msk->mpc_endpoint_id, msk->pm.id_avail_bitmap) &&

	    id && !WARN_ON_ONCE(msk->pm.local_addr_used == 0))

		msk->pm.local_addr_used--;

}



static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net,

						   const struct mptcp_pm_addr_entry *entry)

{
@@ -1474,11 +1480,11 @@ static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net, 
			spin_lock_bh(&msk->pm.lock);

			mptcp_pm_nl_rm_subflow_received(msk, &list);

			spin_unlock_bh(&msk->pm.lock);

		} else if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {

			/* If the subflow has been used, but now closed */

		}



		if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {

			spin_lock_bh(&msk->pm.lock);

			if (!__test_and_set_bit(entry->addr.id, msk->pm.id_avail_bitmap))

				msk->pm.local_addr_used--;

			__mark_subflow_endp_available(msk, list.ids[0]);

			spin_unlock_bh(&msk->pm.lock);

		}
@@ -1516,6 +1522,7 @@ static int mptcp_nl_remove_id_zero_address(struct net *net, 
		spin_lock_bh(&msk->pm.lock);

		mptcp_pm_remove_addr(msk, &list);

		mptcp_pm_nl_rm_subflow_received(msk, &list);

		__mark_subflow_endp_available(msk, 0);

		spin_unlock_bh(&msk->pm.lock);

		release_sock(sk);
@@ -1917,6 +1924,7 @@ static void mptcp_pm_nl_fullmesh(struct mptcp_sock *msk, 


	spin_lock_bh(&msk->pm.lock);

	mptcp_pm_nl_rm_subflow_received(msk, &list);

	__mark_subflow_endp_available(msk, list.ids[0]);

	mptcp_pm_create_subflow_or_signal_addr(msk);

	spin_unlock_bh(&msk->pm.lock);

}