RDMA/rtrs: Only allow addition of path to an already established session

stable inclusion
from stable-5.10.20
commit c6f81f3a9c40b01e2b2a566ca8f4eccabdfbcbe3
bugzilla: 50608

--------------------------------

[ Upstream commit 03e9b33a ]

While adding a path from the client side to an already established
session, it was possible to provide the destination IP to a different
server. This is dangerous.

This commit adds an extra member to the rtrs_msg_conn_req structure, named
first_conn; which is supposed to notify if the connection request is the
first for that session or not.

On the server side, if a session does not exist but the first_conn
received inside the rtrs_msg_conn_req structure is 1, the connection
request is failed. This signifies that the connection request is for an
already existing session, and since the server did not find one, it is an
wrong connection request.

Fixes: 6a98d71d ("RDMA/rtrs: client: main functionality")
Fixes: 9cb83748 ("RDMA/rtrs: server: main functionality")
Link: https://lore.kernel.org/r/20210212134525.103456-3-jinpu.wang@cloud.ionos.com


Signed-off-by: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
Reviewed-by: Lutz Pogrell <lutz.pogrell@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>