sctp: implement sender-side procedures for SSN/TSN Reset Request Parameter

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 <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

@@ -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

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

net/sctp/socket.c

@@ -3818,6 +3818,32 @@ out:
 	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
@@ -3990,6 +4016,9 @@ 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;

net/sctp/stream.c

@@ -177,3 +177,43 @@ 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;
+
+	/* 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;
+
+	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;
+
+		for (i = 0; i < asoc->stream->outcnt; i++)
+			asoc->stream->out[i].state = SCTP_STREAM_OPEN;
+
+		return retval;
+	}
+
+	asoc->strreset_outstanding = 1;
+
+	return 0;
+}