2021-06-15 02:43:36

by NeilBrown

Subject: [PATCH] SUNRPC: prevent port reuse on transports which don't request it.

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 <[email protected]>
---
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 = 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;
--
2.31.1

2021-06-17 03:27:03

by NeilBrown

Subject: Re: [PATCH] SUNRPC: prevent port reuse on transports which don't request it.

On Tue, 15 Jun 2021, someone wrote:
> 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 <[email protected]>

I guess this should have

Fixes: e6237b6feb37 ("NFSv4.1: Don't rebind to the same source port when reconnecting to the server")

NeilBrown

> ---
> 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 = 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;
> --
> 2.31.1
>
>