2 files changed, 115 insertions, 0 deletions

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 2e770f45d82..dfcf47f10f8 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -146,6 +146,50 @@ static int proc_tcp_available_congestion_control(ctl_table *ctl,
 	return ret;
 }
 
+static int proc_allowed_congestion_control(ctl_table *ctl,
+					   int write, struct file * filp,
+					   void __user *buffer, size_t *lenp,
+					   loff_t *ppos)
+{
+	ctl_table tbl = { .maxlen = TCP_CA_BUF_MAX };
+	int ret;
+
+	tbl.data = kmalloc(tbl.maxlen, GFP_USER);
+	if (!tbl.data)
+		return -ENOMEM;
+
+	tcp_get_allowed_congestion_control(tbl.data, tbl.maxlen);
+	ret = proc_dostring(&tbl, write, filp, buffer, lenp, ppos);
+	if (write && ret == 0)
+		ret = tcp_set_allowed_congestion_control(tbl.data);
+	kfree(tbl.data);
+	return ret;
+}
+
+static int strategy_allowed_congestion_control(ctl_table *table, int __user *name,
+					       int nlen, void __user *oldval,
+					       size_t __user *oldlenp,
+					       void __user *newval, size_t newlen,
+					       void **context)
+{
+	ctl_table tbl = { .maxlen = TCP_CA_BUF_MAX };
+	int ret;
+
+	tbl.data = kmalloc(tbl.maxlen, GFP_USER);
+	if (!tbl.data)
+		return -ENOMEM;
+
+	tcp_get_available_congestion_control(tbl.data, tbl.maxlen);
+	ret = sysctl_string(&tbl, name, nlen, oldval, oldlenp, newval, newlen,
+			    context);
+	if (ret == 0 && newval && newlen)
+		ret = tcp_set_allowed_congestion_control(tbl.data);
+	kfree(tbl.data);
+
+	return ret;
+
+}
+
 ctl_table ipv4_table[] = {
         {
 		.ctl_name	= NET_IPV4_TCP_TIMESTAMPS,
@@ -755,6 +799,14 @@ ctl_table ipv4_table[] = {
 		.mode		= 0444,
 		.proc_handler   = &proc_tcp_available_congestion_control,
 	},
+	{
+		.ctl_name	= NET_TCP_ALLOWED_CONG_CONTROL,
+		.procname	= "tcp_allowed_congestion_control",
+		.maxlen		= TCP_CA_BUF_MAX,
+		.mode		= 0644,
+		.proc_handler   = &proc_allowed_congestion_control,
+		.strategy	= &strategy_allowed_congestion_control,
+	},
 	{ .ctl_name = 0 }
 };
 
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index d846d7b95e1..343d6197c92 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -123,6 +123,7 @@ int tcp_set_default_congestion_control(const char *name)
 #endif
 
 	if (ca) {
+		ca->non_restricted = 1;	/* default is always allowed */
 		list_move(&ca->list, &tcp_cong_list);
 		ret = 0;
 	}
@@ -168,6 +169,64 @@ void tcp_get_default_congestion_control(char *name)
 	rcu_read_unlock();
 }
 
+/* Built list of non-restricted congestion control values */
+void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
+{
+	struct tcp_congestion_ops *ca;
+	size_t offs = 0;
+
+	*buf = '\0';
+	rcu_read_lock();
+	list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
+		if (!ca->non_restricted)
+			continue;
+		offs += snprintf(buf + offs, maxlen - offs,
+				 "%s%s",
+				 offs == 0 ? "" : " ", ca->name);
+
+	}
+	rcu_read_unlock();
+}
+
+/* Change list of non-restricted congestion control */
+int tcp_set_allowed_congestion_control(char *val)
+{
+	struct tcp_congestion_ops *ca;
+	char *clone, *name;
+	int ret = 0;
+
+	clone = kstrdup(val, GFP_USER);
+	if (!clone)
+		return -ENOMEM;
+
+	spin_lock(&tcp_cong_list_lock);
+	/* pass 1 check for bad entries */
+	while ((name = strsep(&clone, " ")) && *name) {
+		ca = tcp_ca_find(name);
+		if (!ca) {
+			ret = -ENOENT;
+			goto out;
+		}
+	}
+
+	/* pass 2 clear */
+	list_for_each_entry_rcu(ca, &tcp_cong_list, list)
+		ca->non_restricted = 0;
+
+	/* pass 3 mark as allowed */
+	while ((name = strsep(&val, " ")) && *name) {
+		ca = tcp_ca_find(name);
+		WARN_ON(!ca);
+		if (ca)
+			ca->non_restricted = 1;
+	}
+out:
+	spin_unlock(&tcp_cong_list_lock);
+
+	return ret;
+}
+
+
 /* Change congestion control for socket */
 int tcp_set_congestion_control(struct sock *sk, const char *name)
 {
@@ -183,6 +242,9 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
 	if (!ca)
 		err = -ENOENT;
 
+	else if (!(ca->non_restricted || capable(CAP_NET_ADMIN)))
+		err = -EPERM;
+
 	else if (!try_module_get(ca->owner))
 		err = -EBUSY;
 
@@ -284,6 +346,7 @@ EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
 
 struct tcp_congestion_ops tcp_reno = {
 	.name		= "reno",
+	.non_restricted = 1,
 	.owner		= THIS_MODULE,
 	.ssthresh	= tcp_reno_ssthresh,
 	.cong_avoid	= tcp_reno_cong_avoid,