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

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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: 06faa22710 ("mptcp: remove multi addresses and subflows in PM")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-8-38035d40de5b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Matthieu Baerts (NGI0) 2024-08-19 21:45:26 +02:00 committed by Jakub Kicinski
parent f448451aa6
commit 322ea37789
1 changed files with 17 additions and 9 deletions
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26
net/mptcp/pm_netlink.c
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@ -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);
}