On Mon, 2021-01-25 at 17:02 +0100, Paolo Abeni wrote:
> Prior to this commit, running 'ss' on a kernel older than v5.9
> bumps an error message:
>
> RTNETLINK answers: Invalid argument
Thanks, works perfectly for me.
-Tommi
> When asked to dump protocol number > 255 - that is: MPTCP - 'ss'
> adds an INET_DIAG_REQ_PROTOCOL attribute, unsupported by the older
> kernel.
>
> Avoid the warning ignoring filter issues when INET_DIAG_REQ_PROTOCOL
> is used.
>
> Additionally older kernel end-up invoking tcpdiag_send(), which
> in turn will try to dump DCCP socks. Bail early in such function,
> as the kernel does not implement an MPTCPDIAG_GET request.
>
> Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" <
> tommi.t.rant...@nokia.com>
> Fixes: 9c3be2c0eee0 ("ss: mptcp: add msk diag interface support")
> Signed-off-by: Paolo Abeni <pab...@redhat.com>
> ---
> misc/ss.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/misc/ss.c b/misc/ss.c
> index 0593627b..ad46f9db 100644
> --- a/misc/ss.c
> +++ b/misc/ss.c
> @@ -3404,7 +3404,7 @@ static int tcpdiag_send(int fd, int protocol, struct
> filter *f)
> struct iovec iov[3];
> int iovlen = 1;
>
> - if (protocol == IPPROTO_UDP)
> + if (protocol == IPPROTO_UDP || protocol == IPPROTO_MPTCP)
> return -1;
>
> if (protocol == IPPROTO_TCP)
> @@ -3623,6 +3623,14 @@ static int inet_show_netlink(struct filter *f, FILE
> *dump_fp, int protocol)
> if (preferred_family == PF_INET6)
> family = PF_INET6;
>
> + /* extended protocol will use INET_DIAG_REQ_PROTOCOL,
> + * not supported by older kernels. On such kernel
> + * rtnl_dump will bail with rtnl_dump_error().
> + * Suppress the error to avoid confusing the user
> + */
> + if (protocol > 255)
> + rth.flags |= RTNL_HANDLE_F_SUPPRESS_NLERR;
> +
> again:
> if ((err = sockdiag_send(family, rth.fd, protocol, f)))
> goto Exit;
