sctp: implement sender-side procedures for Add Incoming/Outgoing Streams Request Parameter

This patch is to implement Sender-Side Procedures for the Add
Outgoing and Incoming Streams Request Parameter described in
rfc6525 section 5.1.5-5.1.6.

It is also to add sockopt SCTP_ADD_STREAMS in rfc6525 section
6.3.4 for users.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -199,6 +199,8 @@ 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);
+int sctp_send_add_streams(struct sctp_association *asoc,
+			  struct sctp_add_streams *params);
 
 /*
  * Module global variables

include/uapi/linux/sctp.h

@@ -118,6 +118,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_ENABLE_STREAM_RESET	118
 #define SCTP_RESET_STREAMS	119
 #define SCTP_RESET_ASSOC	120
+#define SCTP_ADD_STREAMS	121
 
 /* PR-SCTP policies */
 #define SCTP_PR_SCTP_NONE	0x0000
@@ -1027,4 +1028,10 @@ struct sctp_reset_streams {
 	uint16_t srs_stream_list[];	/* list if srs_num_streams is not 0 */
 };
 
+struct sctp_add_streams {
+	sctp_assoc_t sas_assoc_id;
+	uint16_t sas_instrms;
+	uint16_t sas_outstrms;
+};
+
 #endif /* _UAPI_SCTP_H */

net/sctp/socket.c

@@ -3844,6 +3844,32 @@ static int sctp_setsockopt_reset_assoc(struct sock *sk,
 	return retval;
 }
 
+static int sctp_setsockopt_add_streams(struct sock *sk,
+				       char __user *optval,
+				       unsigned int optlen)
+{
+	struct sctp_association *asoc;
+	struct sctp_add_streams params;
+	int retval = -EINVAL;
+
+	if (optlen != sizeof(params))
+		goto out;
+
+	if (copy_from_user(&params, optval, optlen)) {
+		retval = -EFAULT;
+		goto out;
+	}
+
+	asoc = sctp_id2assoc(sk, params.sas_assoc_id);
+	if (!asoc)
+		goto out;
+
+	retval = sctp_send_add_streams(asoc, &params);
+
+out:
+	return retval;
+}
+
 /* API 6.2 setsockopt(), getsockopt()
  *
  * Applications use setsockopt() and getsockopt() to set or retrieve
@@ -4019,6 +4045,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 	case SCTP_RESET_ASSOC:
 		retval = sctp_setsockopt_reset_assoc(sk, optval, optlen);
 		break;
+	case SCTP_ADD_STREAMS:
+		retval = sctp_setsockopt_add_streams(sk, optval, optlen);
+		break;
 	default:
 		retval = -ENOPROTOOPT;
 		break;

net/sctp/stream.c

@@ -217,3 +217,80 @@ int sctp_send_reset_assoc(struct sctp_association *asoc)
 
 	return 0;
 }
+
+int sctp_send_add_streams(struct sctp_association *asoc,
+			  struct sctp_add_streams *params)
+{
+	struct sctp_stream *stream = asoc->stream;
+	struct sctp_chunk *chunk = NULL;
+	int retval = -ENOMEM;
+	__u32 outcnt, incnt;
+	__u16 out, in;
+
+	if (!asoc->peer.reconf_capable ||
+	    !(asoc->strreset_enable & SCTP_ENABLE_CHANGE_ASSOC_REQ)) {
+		retval = -ENOPROTOOPT;
+		goto out;
+	}
+
+	if (asoc->strreset_outstanding) {
+		retval = -EINPROGRESS;
+		goto out;
+	}
+
+	out = params->sas_outstrms;
+	in  = params->sas_instrms;
+	outcnt = stream->outcnt + out;
+	incnt = stream->incnt + in;
+	if (outcnt > SCTP_MAX_STREAM || incnt > SCTP_MAX_STREAM ||
+	    (!out && !in)) {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	if (out) {
+		struct sctp_stream_out *streamout;
+
+		streamout = krealloc(stream->out, outcnt * sizeof(*streamout),
+				     GFP_KERNEL);
+		if (!streamout)
+			goto out;
+
+		memset(streamout + stream->outcnt, 0, out * sizeof(*streamout));
+		stream->out = streamout;
+	}
+
+	if (in) {
+		struct sctp_stream_in *streamin;
+
+		streamin = krealloc(stream->in, incnt * sizeof(*streamin),
+				    GFP_KERNEL);
+		if (!streamin)
+			goto out;
+
+		memset(streamin + stream->incnt, 0, in * sizeof(*streamin));
+		stream->in = streamin;
+	}
+
+	chunk = sctp_make_strreset_addstrm(asoc, out, in);
+	if (!chunk)
+		goto out;
+
+	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;
+		goto out;
+	}
+
+	stream->incnt = incnt;
+	stream->outcnt = outcnt;
+
+	asoc->strreset_outstanding = !!out + !!in;
+
+out:
+	return retval;
+}