Subject: Re: [PATCHv3 net-next 16/16] sctp: enable udp tunneling socks

From: Marcelo Ricardo Leitner <[email-masked]>
Date: Thu, 15 Oct 2020 14:42:52 -0300

Actually..

On Tue, Oct 13, 2020 at 03:27:41PM +0800, Xin Long wrote:
...
> Also add sysctl udp_port to allow changing the listening
> sock's port by users.
...
> ---
>  net/sctp/protocol.c |  5 +++++
>  net/sctp/sysctl.c   | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 55 insertions(+)

Xin, sorry for not noticing this earlier, but we need a documentation
update here for this new sysctl. This is important. Please add its
entry in ip-sysctl.rst.

> 
> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
> index be002b7..79fb4b5 100644
> --- a/net/sctp/protocol.c
> +++ b/net/sctp/protocol.c
> @@ -1469,6 +1469,10 @@ static int __net_init sctp_ctrlsock_init(struct net *net)
>  	if (status)
>  		pr_err("Failed to initialize the SCTP control sock\n");
>  
> +	status = sctp_udp_sock_start(net);
> +	if (status)
> +		pr_err("Failed to initialize the SCTP udp tunneling sock\n");
                                                      ^^^ upper case please.
Nit. There are other occurrences of this.

> +
>  	return status;
...
> +	ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
> +	if (write && ret == 0) {
> +		struct sock *sk = net->sctp.ctl_sock;
> +
> +		if (new_value > max || new_value < min)
> +			return -EINVAL;
> +
> +		net->sctp.udp_port = new_value;
> +		sctp_udp_sock_stop(net);

So, if it would be disabling the encapsulation, it shouldn't be
calling _start() then, right? Like

		if (new_value)
			ret = sctp_udp_sock_start(net);
		
Otherwise _start() here will call ..._bind() with port 0, which then
will be a random one.

> +		ret = sctp_udp_sock_start(net);
> +		if (ret)
> +			net->sctp.udp_port = 0;
> +
> +		/* Update the value in the control socket */
> +		lock_sock(sk);
> +		sctp_sk(sk)->udp_port = htons(net->sctp.udp_port);
> +		release_sock(sk);
> +	}
> +
> +	return ret;
> +}
> +
>  int sctp_sysctl_net_register(struct net *net)
>  {
>  	struct ctl_table *table;
> -- 
> 2.1.0
>