sctp: add get and set sockopt for reconf_enable

This patchset is to add SCTP_RECONFIG_SUPPORTED sockopt, it would
set and get asoc reconf_enable value when asoc_id is set, or it
would set and get ep reconf_enalbe value if asoc_id is 0.

It is also to add sysctl interface for users to set the default
value for reconf_enable.

After this patch, stream reconf will work.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/sctp.h

@@ -115,6 +115,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_PR_SUPPORTED	113
 #define SCTP_DEFAULT_PRINFO	114
 #define SCTP_PR_ASSOC_STATUS	115
+#define SCTP_RECONFIG_SUPPORTED	117
 #define SCTP_ENABLE_STREAM_RESET	118
 #define SCTP_RESET_STREAMS	119
 #define SCTP_RESET_ASSOC	120

net/sctp/socket.c

@@ -3758,6 +3758,39 @@ static int sctp_setsockopt_default_prinfo(struct sock *sk,
 	return retval;
 }
 
+static int sctp_setsockopt_reconfig_supported(struct sock *sk,
+					      char __user *optval,
+					      unsigned int optlen)
+{
+	struct sctp_assoc_value params;
+	struct sctp_association *asoc;
+	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.assoc_id);
+	if (asoc) {
+		asoc->reconf_enable = !!params.assoc_value;
+	} else if (!params.assoc_id) {
+		struct sctp_sock *sp = sctp_sk(sk);
+
+		sp->ep->reconf_enable = !!params.assoc_value;
+	} else {
+		goto out;
+	}
+
+	retval = 0;
+
+out:
+	return retval;
+}
+
 static int sctp_setsockopt_enable_strreset(struct sock *sk,
 					   char __user *optval,
 					   unsigned int optlen)
@@ -4038,6 +4071,9 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 	case SCTP_DEFAULT_PRINFO:
 		retval = sctp_setsockopt_default_prinfo(sk, optval, optlen);
 		break;
+	case SCTP_RECONFIG_SUPPORTED:
+		retval = sctp_setsockopt_reconfig_supported(sk, optval, optlen);
+		break;
 	case SCTP_ENABLE_STREAM_RESET:
 		retval = sctp_setsockopt_enable_strreset(sk, optval, optlen);
 		break;
@@ -6540,6 +6576,47 @@ static int sctp_getsockopt_pr_assocstatus(struct sock *sk, int len,
 	return retval;
 }
 
+static int sctp_getsockopt_reconfig_supported(struct sock *sk, int len,
+					      char __user *optval,
+					      int __user *optlen)
+{
+	struct sctp_assoc_value params;
+	struct sctp_association *asoc;
+	int retval = -EFAULT;
+
+	if (len < sizeof(params)) {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	len = sizeof(params);
+	if (copy_from_user(&params, optval, len))
+		goto out;
+
+	asoc = sctp_id2assoc(sk, params.assoc_id);
+	if (asoc) {
+		params.assoc_value = asoc->reconf_enable;
+	} else if (!params.assoc_id) {
+		struct sctp_sock *sp = sctp_sk(sk);
+
+		params.assoc_value = sp->ep->reconf_enable;
+	} else {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	if (put_user(len, optlen))
+		goto out;
+
+	if (copy_to_user(optval, &params, len))
+		goto out;
+
+	retval = 0;
+
+out:
+	return retval;
+}
+
 static int sctp_getsockopt_enable_strreset(struct sock *sk, int len,
 					   char __user *optval,
 					   int __user *optlen)
@@ -6748,6 +6825,10 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
 		retval = sctp_getsockopt_pr_assocstatus(sk, len, optval,
 							optlen);
 		break;
+	case SCTP_RECONFIG_SUPPORTED:
+		retval = sctp_getsockopt_reconfig_supported(sk, len, optval,
+							    optlen);
+		break;
 	case SCTP_ENABLE_STREAM_RESET:
 		retval = sctp_getsockopt_enable_strreset(sk, len, optval,
 							 optlen);

net/sctp/sysctl.c

@@ -274,6 +274,13 @@ static struct ctl_table sctp_net_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
+	{
+		.procname	= "reconf_enable",
+		.data		= &init_net.sctp.reconf_enable,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 	{
 		.procname	= "auth_enable",
 		.data		= &init_net.sctp.auth_enable,