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From:   "NeilBrown" <neilb@suse.de>
To:     Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH] SUNRPC: prevent port reuse on transports which don't request it.
Date:   Tue, 15 Jun 2021 11:18:38 +1000
Message-id: <162371991856.23575.16102887900102220450@noble.neil.brown.name>
Precedence: bulk


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>
---
 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 316d04945587..3228b7a1836a 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1689,7 +1689,8 @@ static int xs_bind(struct sock_xprt *transport, struct =
socket *sock)
 		err =3D kernel_bind(sock, (struct sockaddr *)&myaddr,
 				transport->xprt.addrlen);
 		if (err =3D=3D 0) {
-			transport->srcport =3D port;
+			if (transport->xprt.reuseport)
+				transport->srcport =3D port;
 			break;
 		}
 		last =3D port;
--=20
2.31.1