Commit 93e61613 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'bind_addr_zero' 

Kuniyuki Iwashima says:

====================
Improve bind(addr, 0) behaviour.

Currently we fail to bind sockets to ephemeral ports when all of the ports
are exhausted even if all sockets have SO_REUSEADDR enabled. In this case,
we still have a chance to connect to the different remote hosts.

These patches add net.ipv4.ip_autobind_reuse option and fix the behaviour
to fully utilize all space of the local (addr, port) tuples.

Changes in v5:
  - Add more description to documents.
  - Fix sysctl option to use proc_dointvec_minmax.
  - Remove the Fixes: tag and squash two commits.

Changes in v4:
  - Add net.ipv4.ip_autobind_reuse option to not change the current behaviour.
  - Modify .gitignore for test.
  https://lore.kernel.org/netdev/20200308181615.90135-1-kuniyu@amazon.co.jp/

Changes in v3:
  - Change the title and write more specific description of the 3rd patch.
  - Add a test in tools/testing/selftests/net/ as the 4th patch.
  https://lore.kernel.org/netdev/20200229113554.78338-1-kuniyu@amazon.co.jp/

Changes in v2:
  - Change the description of the 2nd patch ('localhost' -> 'address').
  - Correct the description and the if statement of the 3rd patch.
  https://lore.kernel.org/netdev/20200226074631.67688-1-kuniyu@amazon.co.jp/

v1 with tests:
  https://lore.kernel.org/netdev/20200220152020.13056-1-kuniyu@amazon.co.jp/


====================

Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents af91fd7e 7f204a7d

Documentation/networking/ip-sysctl.txt

+9 −0
Original line number Diff line number Diff line
@@ -958,6 +958,15 @@ ip_nonlocal_bind - BOOLEAN 
	which can be quite useful - but may break some applications.

	Default: 0



ip_autobind_reuse - BOOLEAN

	By default, bind() does not select the ports automatically even if

	the new socket and all sockets bound to the port have SO_REUSEADDR.

	ip_autobind_reuse allows bind() to reuse the port and this is useful

	when you use bind()+connect(), but may break some applications.

	The preferred solution is to use IP_BIND_ADDRESS_NO_PORT and this

	option should only be set by experts.

	Default: 0



ip_dynaddr - BOOLEAN

	If set non-zero, enables support for dynamic addresses.

	If set to a non-zero value larger than 1, a kernel log

include/net/netns/ipv4.h

+1 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ struct netns_ipv4 { 
	int sysctl_ip_fwd_use_pmtu;

	int sysctl_ip_fwd_update_priority;

	int sysctl_ip_nonlocal_bind;

	int sysctl_ip_autobind_reuse;

	/* Shall we try to damage output packets if routing dev changes? */

	int sysctl_ip_dynaddr;

	int sysctl_ip_early_demux;

net/ipv4/inet_connection_sock.c

+24 −12
Original line number Diff line number Diff line
@@ -131,7 +131,7 @@ static int inet_csk_bind_conflict(const struct sock *sk, 
{

	struct sock *sk2;

	bool reuse = sk->sk_reuse;

	bool reuseport = !!sk->sk_reuseport && reuseport_ok;

	bool reuseport = !!sk->sk_reuseport;

	kuid_t uid = sock_i_uid((struct sock *)sk);



	/*
@@ -146,17 +146,21 @@ static int inet_csk_bind_conflict(const struct sock *sk, 
		    (!sk->sk_bound_dev_if ||

		     !sk2->sk_bound_dev_if ||

		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {

			if ((!reuse || !sk2->sk_reuse ||

			    sk2->sk_state == TCP_LISTEN) &&

			    (!reuseport || !sk2->sk_reuseport ||

			if (reuse && sk2->sk_reuse &&

			    sk2->sk_state != TCP_LISTEN) {

				if ((!relax ||

				     (!reuseport_ok &&

				      reuseport && sk2->sk_reuseport &&

				      !rcu_access_pointer(sk->sk_reuseport_cb) &&

				      (sk2->sk_state == TCP_TIME_WAIT ||

				       uid_eq(uid, sock_i_uid(sk2))))) &&

				    inet_rcv_saddr_equal(sk, sk2, true))

					break;

			} else if (!reuseport_ok ||

				   !reuseport || !sk2->sk_reuseport ||

				   rcu_access_pointer(sk->sk_reuseport_cb) ||

				   (sk2->sk_state != TCP_TIME_WAIT &&

			     !uid_eq(uid, sock_i_uid(sk2))))) {

				if (inet_rcv_saddr_equal(sk, sk2, true))

					break;

			}

			if (!relax && reuse && sk2->sk_reuse &&

			    sk2->sk_state != TCP_LISTEN) {

				    !uid_eq(uid, sock_i_uid(sk2)))) {

				if (inet_rcv_saddr_equal(sk, sk2, true))

					break;

			}
@@ -176,12 +180,14 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int * 
	int port = 0;

	struct inet_bind_hashbucket *head;

	struct net *net = sock_net(sk);

	bool relax = false;

	int i, low, high, attempt_half;

	struct inet_bind_bucket *tb;

	u32 remaining, offset;

	int l3mdev;



	l3mdev = inet_sk_bound_l3mdev(sk);

ports_exhausted:

	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;

other_half_scan:

	inet_get_local_port_range(net, &low, &high);
@@ -219,7 +225,7 @@ other_parity_scan: 
		inet_bind_bucket_for_each(tb, &head->chain)

			if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&

			    tb->port == port) {

				if (!inet_csk_bind_conflict(sk, tb, false, false))

				if (!inet_csk_bind_conflict(sk, tb, relax, false))

					goto success;

				goto next_port;

			}
@@ -239,6 +245,12 @@ next_port: 
		attempt_half = 2;

		goto other_half_scan;

	}



	if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {

		/* We still have a chance to connect to different destinations */

		relax = true;

		goto ports_exhausted;

	}

	return NULL;

success:

	*port_ret = port;

net/ipv4/sysctl_net_ipv4.c

+9 −0
Original line number Diff line number Diff line
@@ -763,6 +763,15 @@ static struct ctl_table ipv4_net_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec

	},

	{

		.procname	= "ip_autobind_reuse",

		.data		= &init_net.ipv4.sysctl_ip_autobind_reuse,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1         = SYSCTL_ZERO,

		.extra2         = SYSCTL_ONE,

	},

	{

		.procname	= "fwmark_reflect",

		.data		= &init_net.ipv4.sysctl_fwmark_reflect,

tools/testing/selftests/net/.gitignore

+1 −0
Original line number Diff line number Diff line
@@ -23,3 +23,4 @@ so_txtime 
tcp_fastopen_backup_key

nettest

fin_ack_lat

reuseaddr_ports_exhausted
 
 No newline at end of file

CRA Git | Maintained and supported by SUSTech CRA and CCSE