net: reserve ports for applications using fixed port numbers (e3826f1e) · Commits · 戴 / test

Documentation/networking/ip-sysctl.txt

+31 −0

Original line number	Diff line number	Diff line
		@@ -588,6 +588,37 @@ ip_local_port_range - 2 INTEGERS
		(i.e. by default) range 1024-4999 is enough to issue up to
		2000 connections per second to systems supporting timestamps.

		ip_local_reserved_ports - list of comma separated ranges
		Specify the ports which are reserved for known third-party
		applications. These ports will not be used by automatic port
		assignments (e.g. when calling connect() or bind() with port
		number 0). Explicit port allocation behavior is unchanged.

		The format used for both input and output is a comma separated
		list of ranges (e.g. "1,2-4,10-10" for ports 1, 2, 3, 4 and
		10). Writing to the file will clear all previously reserved
		ports and update the current list with the one given in the
		input.

		Note that ip_local_port_range and ip_local_reserved_ports
		settings are independent and both are considered by the kernel
		when determining which ports are available for automatic port
		assignments.

		You can reserve ports which are not in the current
		ip_local_port_range, e.g.:

		$ cat /proc/sys/net/ipv4/ip_local_port_range
		32000 61000
		$ cat /proc/sys/net/ipv4/ip_local_reserved_ports
		8080,9148

		although this is redundant. However such a setting is useful
		if later the port range is changed to a value that will
		include the reserved ports.

		Default: Empty

		ip_nonlocal_bind - BOOLEAN
		If set, allows processes to bind() to non-local IP addresses,
		which can be quite useful - but may break some applications.

+6 −0

Original line number	Diff line number	Diff line
		@@ -184,6 +184,12 @@ extern struct local_ports {
		} sysctl_local_ports;
		extern void inet_get_local_port_range(int low, int high);

		extern unsigned long *sysctl_local_reserved_ports;
		static inline int inet_is_reserved_local_port(int port)
		{
		return test_bit(port, sysctl_local_reserved_ports);
		}

		extern int sysctl_ip_default_ttl;
		extern int sysctl_ip_nonlocal_bind;

+7 −1

Original line number	Diff line number	Diff line
		@@ -1573,9 +1573,13 @@ static int __init inet_init(void)

		BUILD_BUG_ON(sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb));

		sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL);
		if (!sysctl_local_reserved_ports)
		goto out;

		rc = proto_register(&tcp_prot, 1);
		if (rc)
		goto out;
		goto out_free_reserved_ports;

		rc = proto_register(&udp_prot, 1);
		if (rc)
		@@ -1674,6 +1678,8 @@ out_unregister_udp_proto:
		proto_unregister(&udp_prot);
		out_unregister_tcp_proto:
		proto_unregister(&tcp_prot);
		out_free_reserved_ports:
		kfree(sysctl_local_reserved_ports);
		goto out;
		}

+6 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,9 @@ struct local_ports sysctl_local_ports __read_mostly = {
		.range = { 32768, 61000 },
		};

		unsigned long *sysctl_local_reserved_ports;
		EXPORT_SYMBOL(sysctl_local_reserved_ports);

		void inet_get_local_port_range(int low, int high)
		{
		unsigned seq;
		@@ -108,6 +111,8 @@ again:

		smallest_size = -1;
		do {
		if (inet_is_reserved_local_port(rover))
		goto next_nolock;
		head = &hashinfo->bhash[inet_bhashfn(net, rover,
		hashinfo->bhash_size)];
		spin_lock(&head->lock);
		@@ -130,6 +135,7 @@ again:
		break;
		next:
		spin_unlock(&head->lock);
		next_nolock:
		if (++rover > high)
		rover = low;
		} while (--remaining > 0);

+2 −0

Original line number	Diff line number	Diff line
		@@ -456,6 +456,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
		local_bh_disable();
		for (i = 1; i <= remaining; i++) {
		port = low + (i + offset) % remaining;
		if (inet_is_reserved_local_port(port))
		continue;
		head = &hinfo->bhash[inet_bhashfn(net, port,
		hinfo->bhash_size)];
		spin_lock(&head->lock);