tcp_comp: add sysctl for enable/disable compression

hulk inclusion
category: feature
bugzilla: NA
CVE: NA

-------------------------------------------------

Add sysctl interface for enable/disable tcp compression by ports.

Example:

$ echo 4000 > /proc/sys/net/ipv4/tcp_compression_ports
will enable port 4000 for tcp compression

$ echo 4000,5000 > /proc/sys/net/ipv4/tcp_compression_ports
will enable both port 4000 and 5000 for tcp compression

$ echo > /proc/sys/net/ipv4/tcp_compression_ports
will disable tcp compression.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NWang Yufen <wangyufen@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/net/tcp.h

@@ -2212,6 +2212,9 @@ void clean_acked_data_disable(struct inet_connection_sock *icsk);
 
 #if IS_ENABLED(CONFIG_TCP_COMP)
 extern struct static_key_false tcp_have_comp;
+
+extern unsigned long *sysctl_tcp_compression_ports;
+
 bool tcp_syn_comp_enabled(const struct tcp_sock *tp);
 void tcp_init_compression(struct sock *sk);
 void tcp_cleanup_compression(struct sock *sk);

net/ipv4/sysctl_net_ipv4.c

@@ -438,6 +438,30 @@ static int proc_fib_multipath_hash_policy(struct ctl_table *table, int write,
 }
 #endif
 
+#if IS_ENABLED(CONFIG_TCP_COMP)
+static int proc_tcp_compression_ports(struct ctl_table *table, int write,
+				      void __user *buffer, size_t *lenp,
+				      loff_t *ppos)
+{
+	unsigned long *bitmap = *(unsigned long **)table->data;
+	unsigned long bitmap_len = table->maxlen;
+	int ret;
+
+	ret = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
+	if (write && ret == 0) {
+		if (bitmap_empty(bitmap, bitmap_len)) {
+			if (static_key_enabled(&tcp_have_comp))
+				static_branch_disable(&tcp_have_comp);
+		} else {
+			if (!static_key_enabled(&tcp_have_comp))
+				static_branch_enable(&tcp_have_comp);
+		}
+	}
+
+	return ret;
+}
+#endif
+
 static struct ctl_table ipv4_table[] = {
 	{
 		.procname	= "tcp_max_orphans",
@@ -560,6 +584,15 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
 	},
+#if IS_ENABLED(CONFIG_TCP_COMP)
+	{
+		.procname	= "tcp_compression_ports",
+		.data		= &sysctl_tcp_compression_ports,
+		.maxlen		= 65536,
+		.mode		= 0644,
+		.proc_handler	= proc_tcp_compression_ports,
+	},
+#endif
 	{ }
 };
 

net/ipv4/tcp_comp.c

@@ -7,6 +7,10 @@
 
 #include <net/tcp.h>
 
+static unsigned long tcp_compression_ports[65536 / 8];
+
+unsigned long *sysctl_tcp_compression_ports = tcp_compression_ports;
+
 bool tcp_syn_comp_enabled(const struct tcp_sock *tp)
 {
 	return true;