Subject: Re: [PATCHv4 net-next 3/5] sctp: implement sender-side procedures for SSN/TSN Reset Request Parameter

From: Marcelo Ricardo Leitner <[email-masked]>
Date: Fri, 20 Jan 2017 16:25:22 -0200

On Sat, Jan 21, 2017 at 02:00:37AM +0800, Xin Long wrote:
> This patch is to implement Sender-Side Procedures for the SSN/TSN
> Reset Request Parameter descibed in rfc6525 section 5.1.4.
> 
> It is also to add sockopt SCTP_RESET_ASSOC in rfc6525 section 6.3.3
> for users.
> 
> Signed-off-by: Xin Long <[email-masked]>
> ---
>  include/net/sctp/sctp.h   |  1 +
>  include/uapi/linux/sctp.h |  1 +
>  net/sctp/socket.c         | 29 +++++++++++++++++++++++++++++
>  net/sctp/stream.c         | 37 +++++++++++++++++++++++++++++++++++++
>  4 files changed, 68 insertions(+)
> 
> diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
> index 3cfd365b..b93820f 100644
> --- a/include/net/sctp/sctp.h
> +++ b/include/net/sctp/sctp.h
> @@ -198,6 +198,7 @@ int sctp_offload_init(void);
>   */
>  int sctp_send_reset_streams(struct sctp_association *asoc,
>  			    struct sctp_reset_streams *params);
> +int sctp_send_reset_assoc(struct sctp_association *asoc);
>  
>  /*
>   * Module global variables
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index 03c27ce..c0bd8c3 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -117,6 +117,7 @@ typedef __s32 sctp_assoc_t;
>  #define SCTP_PR_ASSOC_STATUS	115
>  #define SCTP_ENABLE_STREAM_RESET	118
>  #define SCTP_RESET_STREAMS	119
> +#define SCTP_RESET_ASSOC	120
>  
>  /* PR-SCTP policies */
>  #define SCTP_PR_SCTP_NONE	0x0000
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index bee4dd3..2c5c9ca 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -3812,6 +3812,32 @@ static int sctp_setsockopt_reset_streams(struct sock *sk,
>  	return retval;
>  }
>  
> +static int sctp_setsockopt_reset_assoc(struct sock *sk,
> +				       char __user *optval,
> +				       unsigned int optlen)
> +{
> +	struct sctp_association *asoc;
> +	sctp_assoc_t associd;
> +	int retval = -EINVAL;
> +
> +	if (optlen != sizeof(associd))
> +		goto out;
> +
> +	if (copy_from_user(&associd, optval, optlen)) {
> +		retval = -EFAULT;
> +		goto out;
> +	}
> +
> +	asoc = sctp_id2assoc(sk, associd);
> +	if (!asoc)
> +		goto out;
> +
> +	retval = sctp_send_reset_assoc(asoc);
> +
> +out:
> +	return retval;
> +}
> +
>  /* API 6.2 setsockopt(), getsockopt()
>   *
>   * Applications use setsockopt() and getsockopt() to set or retrieve
> @@ -3984,6 +4010,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
>  	case SCTP_RESET_STREAMS:
>  		retval = sctp_setsockopt_reset_streams(sk, optval, optlen);
>  		break;
> +	case SCTP_RESET_ASSOC:
> +		retval = sctp_setsockopt_reset_assoc(sk, optval, optlen);
> +		break;
>  	default:
>  		retval = -ENOPROTOOPT;
>  		break;
> diff --git a/net/sctp/stream.c b/net/sctp/stream.c
> index 53c67d6..3b872a8 100644
> --- a/net/sctp/stream.c
> +++ b/net/sctp/stream.c
> @@ -166,3 +166,40 @@ int sctp_send_reset_streams(struct sctp_association *asoc,
>  out:
>  	return retval;
>  }
> +
> +int sctp_send_reset_assoc(struct sctp_association *asoc)
> +{
> +	struct sctp_chunk *chunk = NULL;
> +	int retval;
> +	__u16 i;
> +
> +	if (!asoc->peer.reconf_capable ||
> +	    !(asoc->strreset_enable & SCTP_ENABLE_RESET_ASSOC_REQ))
> +		return -ENOPROTOOPT;
> +
> +	if (asoc->strreset_outstanding)
> +		return -EINPROGRESS;
> +
> +	chunk = sctp_make_strreset_tsnreq(asoc);
> +	if (!chunk)
> +		return -ENOMEM;
> +
> +	asoc->strreset_chunk = chunk;
> +	sctp_chunk_hold(asoc->strreset_chunk);
> +
> +	retval = sctp_send_reconf(asoc, chunk);
> +	if (retval) {
> +		sctp_chunk_put(asoc->strreset_chunk);
> +		asoc->strreset_chunk = NULL;
> +
> +		return retval;
> +	}
> +
> +	/* Block further xmit of data until this request is completed */
> +	for (i = 0; i < asoc->stream->outcnt; i++)
> +		asoc->stream->out[i].state = SCTP_STREAM_CLOSED;

I talked offline with Xin about this and we cannot do it this way.
Unfortunatelly we will have to take the long road here, because then we
may send data while sending the request, as the streams are not closed
yet.
We really need to close team, send the request, and re-open if the send
fails.

  Marcelo

> +
> +	asoc->strreset_outstanding = 1;
> +
> +	return 0;
> +}
> -- 
> 2.1.0
> 
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