mptcp: userspace pm send RM_ADDR for ID 0

mptcp: userspace pm send RM_ADDR for ID 0

commit 84c531f54ad9a124a924c9505d74e33d16965146 upstream.

This patch adds the ability to send RM_ADDR for local ID 0. Check
whether id 0 address is removed, if not, put id 0 into a removing
list, pass it to mptcp_pm_remove_addr() to remove id 0 address.

There is no reason not to allow the userspace to remove the initial
address (ID 0). This special case was not taken into account not
letting the userspace to delete all addresses as announced.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/379
Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231025-send-net-next-20231025-v1-3-db8f25f798eb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Fixes: d9a4594edabf ("mptcp: netlink: Add MPTCP_PM_CMD_REMOVE")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>