ipv4: Namespaceify tcp_keepalive_time sysctl knob

Different net namespaces might have different requirements as to
the keepalive time of tcp sockets. This might be required in cases
where different firewall rules are in place which require tcp
timeout sockets to be increased/decreased independently of the host.
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv4.h

@@ -94,6 +94,8 @@ struct netns_ipv4 {
 	int sysctl_tcp_probe_threshold;
 	u32 sysctl_tcp_probe_interval;
 
+	int sysctl_tcp_keepalive_time;
+
 	struct ping_group_range ping_group_range;
 
 	atomic_t dev_addr_genid;

include/net/tcp.h

@@ -240,7 +240,6 @@ extern int sysctl_tcp_timestamps;
 extern int sysctl_tcp_window_scaling;
 extern int sysctl_tcp_sack;
 extern int sysctl_tcp_fin_timeout;
-extern int sysctl_tcp_keepalive_time;
 extern int sysctl_tcp_keepalive_probes;
 extern int sysctl_tcp_keepalive_intvl;
 extern int sysctl_tcp_syn_retries;
@@ -1230,7 +1229,9 @@ static inline int keepalive_intvl_when(const struct tcp_sock *tp)
 
 static inline int keepalive_time_when(const struct tcp_sock *tp)
 {
-	return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
+	struct net *net = sock_net((struct sock *)tp);
+
+	return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
 }
 
 static inline int keepalive_probes(const struct tcp_sock *tp)

net/ipv4/sysctl_net_ipv4.c

@@ -336,13 +336,6 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{
-		.procname	= "tcp_keepalive_time",
-		.data		= &sysctl_tcp_keepalive_time,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_jiffies,
-	},
 	{
 		.procname	= "tcp_keepalive_probes",
 		.data		= &sysctl_tcp_keepalive_probes,
@@ -961,6 +954,13 @@ static struct ctl_table ipv4_net_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "tcp_keepalive_time",
+		.data		= &init_net.ipv4.sysctl_tcp_keepalive_time,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
 	{ }
 };
 

net/ipv4/tcp_ipv4.c

@@ -2385,6 +2385,8 @@ static int __net_init tcp_sk_init(struct net *net)
 	net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
 	net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;
 
+	net->ipv4.sysctl_tcp_keepalive_time = TCP_KEEPALIVE_TIME;
+
 	return 0;
 fail:
 	tcp_sk_exit(net);

net/ipv4/tcp_timer.c

@@ -24,7 +24,6 @@
 
 int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES;
 int sysctl_tcp_synack_retries __read_mostly = TCP_SYNACK_RETRIES;
-int sysctl_tcp_keepalive_time __read_mostly = TCP_KEEPALIVE_TIME;
 int sysctl_tcp_keepalive_probes __read_mostly = TCP_KEEPALIVE_PROBES;
 int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL;
 int sysctl_tcp_retries1 __read_mostly = TCP_RETR1;