sctp: make ecn flag per netns and endpoint

This patch is to add ecn flag for both netns_sctp and sctp_endpoint,
net->sctp.ecn_enable is set 1 by default, and ep->ecn_enable will
be initialized with net->sctp.ecn_enable.

asoc->peer.ecn_capable will be set during negotiation only when
ep->ecn_enable is set on both sides.

Signed-off-by: Xin Long <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/netns/sctp.h

···
 	/* Flag to indicate if stream interleave is enabled */
 	int intl_enable;
 
+	/* Flag to indicate if ecn is enabled */
+	int ecn_enable;
+
 	/*
 	 * Policy to control SCTP IPv4 address scoping
 	 * 0   - Disable IPv4 address scoping

include/net/sctp/structs.h

···
 	/* SCTP-AUTH: endpoint shared keys */
 	struct list_head endpoint_shared_keys;
 	__u16 active_key_id;
-	__u8  auth_enable:1,
+	__u8  ecn_enable:1,
+	      auth_enable:1,
 	      intl_enable:1,
 	      prsctp_enable:1,
 	      asconf_enable:1,

net/sctp/endpointola.c

···
 	 */
 	ep->prsctp_enable = net->sctp.prsctp_enable;
 	ep->reconf_enable = net->sctp.reconf_enable;
+	ep->ecn_enable = net->sctp.ecn_enable;
 
 	/* Remember who we are attached to.  */
 	ep->base.sk = sk;

net/sctp/protocol.c

···
 	/* Disable AUTH by default. */
 	net->sctp.auth_enable = 0;
 
+	/* Enable ECN by default. */
+	net->sctp.ecn_enable = 1;
+
 	/* Set SCOPE policy to enabled */
 	net->sctp.scope_policy = SCTP_SCOPE_POLICY_ENABLE;
 

net/sctp/sm_make_chunk.c

···
 
 	chunksize = sizeof(init) + addrs_len;
 	chunksize += SCTP_PAD4(SCTP_SAT_LEN(num_types));
-	chunksize += sizeof(ecap_param);
+
+	if (asoc->ep->ecn_enable)
+		chunksize += sizeof(ecap_param);
 
 	if (asoc->ep->prsctp_enable)
 		chunksize += sizeof(prsctp_param);
···
 	sctp_addto_chunk(retval, sizeof(sat), &sat);
 	sctp_addto_chunk(retval, num_types * sizeof(__u16), &types);
 
-	sctp_addto_chunk(retval, sizeof(ecap_param), &ecap_param);
+	if (asoc->ep->ecn_enable)
+		sctp_addto_chunk(retval, sizeof(ecap_param), &ecap_param);
 
 	/* Add the supported extensions parameter.  Be nice and add this
 	 * fist before addiding the parameters for the extensions themselves
···
 		break;
 
 	case SCTP_PARAM_ECN_CAPABLE:
-		asoc->peer.ecn_capable = 1;
-		break;
+		if (asoc->ep->ecn_enable) {
+			asoc->peer.ecn_capable = 1;
+			break;
+		}
+		/* Fall Through */
+		goto fall_through;
+
 
 	case SCTP_PARAM_ADAPTATION_LAYER_IND:
 		asoc->peer.adaptation_ind = ntohl(param.aind->adaptation_ind);