[PATCH 5.12 197/292] SUNRPC: prevent port reuse on transports which dont request it.

Greg Kroah-Hartman
2021-07-19T18:09:26Z

From: NeilBrown <neilb@suse.de>

[ Upstream commit bc1c56e9bbe92766d017efb5f0a0c71f80da5570 ]

If an RPC client is created without RPC_CLNT_CREATE_REUSEPORT, it should
not reuse the source port when a TCP connection is re-established.
This is currently implemented by preventing the source port being
recorded after a successful connection (the call to xs_set_srcport()).

However the source port is also recorded after a successful bind in xs_bind().
This may not be needed at all and certainly is not wanted when
RPC_CLNT_CREATE_REUSEPORT wasn't requested.

So avoid that assignment when xprt.reuseport is not set.

With this change, NFSv4.1 and later mounts use a different port number on
each connection. This is helpful with some firewalls which don't cope
well with port reuse.

Signed-off-by: NeilBrown <neilb@suse.de>
Fixes: e6237b6feb37 ("NFSv4.1: Don't rebind to the same source port when reconnecting to the server")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/xprtsock.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index e35760f238a4..87cb0e36eade 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1680,7 +1680,8 @@ static int xs_bind(struct sock_xprt *transport, struct socket *sock)
err = kernel_bind(sock, (struct sockaddr *)&myaddr,
transport->xprt.addrlen);
if (err == 0) {
- transport->srcport = port;
+ if (transport->xprt.reuseport)
+ transport->srcport = port;
break;
}
last = port;
--
2.30.2