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4b01a96742
linux/net/ipv4
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Kuniyuki Iwashima 4b01a96742 tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted. 
Commit aacd9289af ("tcp: bind() use stronger
condition for bind_conflict") introduced a restriction to forbid to bind
SO_REUSEADDR enabled sockets to the same (addr, port) tuple in order to
assign ports dispersedly so that we can connect to the same remote host.

The change results in accelerating port depletion so that we fail to bind
sockets to the same local port even if we want to connect to the different
remote hosts.

You can reproduce this issue by following instructions below.

  1. # sysctl -w net.ipv4.ip_local_port_range="32768 32768"
  2. set SO_REUSEADDR to two sockets.
  3. bind two sockets to (localhost, 0) and the latter fails.

Therefore, when ephemeral ports are exhausted, bind(0) should fallback to
the legacy behaviour to enable the SO_REUSEADDR option and make it possible
to connect to different remote (addr, port) tuples.

This patch allows us to bind SO_REUSEADDR enabled sockets to the same
(addr, port) only when net.ipv4.ip_autobind_reuse is set 1 and all
ephemeral ports are exhausted. This also allows connect() and listen() to
share ports in the following way and may break some applications. So the
ip_autobind_reuse is 0 by default and disables the feature.

  1. setsockopt(sk1, SO_REUSEADDR)
  2. setsockopt(sk2, SO_REUSEADDR)
  3. bind(sk1, saddr, 0)
  4. bind(sk2, saddr, 0)
  5. connect(sk1, daddr)
  6. listen(sk2)

If it is set 1, we can fully utilize the 4-tuples, but we should use
IP_BIND_ADDRESS_NO_PORT for bind()+connect() as possible.

The notable thing is that if all sockets bound to the same port have
both SO_REUSEADDR and SO_REUSEPORT enabled, we can bind sockets to an
ephemeral port and also do listen().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-12 12:08:09 -07:00
..
bpfilter SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
netfilter proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
af_inet.c net: port < inet_prot_sock(net) --> inet_port_requires_bind_service(net, port) 2019-11-26 13:20:46 -08:00
ah4.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
arp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
bpf_tcp_ca.c bpf: Add BPF_FUNC_tcp_send_ack helper 2020-01-09 08:46:18 -08:00
cipso_ipv4.c ipv4: ensure rcu_read_lock() in cipso_v4_error() 2020-02-22 21:45:55 -08:00
datagram.c inet: stop leaking jiffies on the wire 2019-11-01 14:57:52 -07:00
devinet.c inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
esp4_offload.c xfrm: support output_mark for offload ESP packets 2020-01-15 12:18:35 +01:00
esp4.c xfrm: add espintcp (RFC 8229) 2019-12-09 09:59:07 +01:00
fib_frontend.c ipv4: move fib4_has_custom_rules() helper to public header 2019-11-21 14:45:55 -08:00
fib_lookup.h ipv4: Add "offload" and "trap" indications to routes 2020-01-14 18:53:35 -08:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_semantics.c ipv4: Add "offload" and "trap" indications to routes 2020-01-14 18:53:35 -08:00
fib_trie.c net: remove unused macro from fib_trie.c 2020-02-20 10:02:23 -08:00
fou.c fou: Fix IPv6 netlink policy 2020-01-23 14:32:52 +01:00
gre_demux.c gre: refetch erspan header from skb->data after pskb_may_pull() 2019-12-07 11:53:27 -08:00
gre_offload.c net: remove the check argument from __skb_gro_checksum_convert 2020-01-03 12:24:34 -08:00
icmp.c icmp: introduce helper for nat'd source address in network device context 2020-02-13 14:19:00 -08:00
igmp.c igmp: remove unused macro IGMP_Vx_UNSOLICITED_REPORT_INTERVAL 2020-02-23 21:15:36 -08:00
inet_connection_sock.c tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted. 2020-03-12 12:08:09 -07:00
inet_diag.c bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump() 2020-02-27 18:50:19 -08:00
inet_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
inet_hashtables.c tcp/dccp: fix possible race __inet_lookup_established() 2019-12-13 21:40:49 -08:00
inet_timewait_sock.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
inetpeer.c inetpeer: fix data-race in inet_putpeer / inet_putpeer 2019-11-07 16:15:56 -08:00
ip_forward.c ipv4: Revert removal of rt_uses_gateway 2019-09-20 18:23:33 -07:00
ip_fragment.c inet: frags: re-introduce skb coalescing for local delivery 2019-08-08 15:55:10 -07:00
ip_gre.c treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
ip_input.c ipv4: use dst hint for ipv4 list receive 2019-11-21 14:45:55 -08:00
ip_options.c netfilter: nf_tables: add support for matching IPv4 options 2019-06-21 18:35:51 +02:00
ip_output.c net: ipv4: use skb_list_walk_safe helper for gso segments 2020-01-14 11:48:41 -08:00
ip_sockglue.c ip_sockglue: Fix missing-check bug in ip_ra_control() 2019-05-25 11:00:50 -07:00
ip_tunnel_core.c lwtunnel: check erspan options before allocating tun_info 2019-11-21 11:47:39 -08:00
ip_tunnel.c net, ip_tunnel: fix namespaces move 2020-01-21 16:05:21 +01:00
ip_vti.c vti[6]: fix packet tx through bpf_redirect() 2020-01-14 08:55:38 +01:00
ipcomp.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2019-07-05 15:01:15 -07:00
ipconfig.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
ipip.c ipip: validate header length in ipip_tunnel_xmit 2019-07-25 17:23:40 -07:00
ipmr_base.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
ipmr.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-16 21:51:42 -08:00
Kconfig xfrm: add espintcp (RFC 8229) 2019-12-09 09:59:07 +01:00
Makefile bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
metrics.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
netfilter.c netfilter: ipv4: remove useless export_symbol 2019-01-28 11:32:58 +01:00
netlink.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
nexthop.c net: include struct nhmsg size in nh nlmsg size 2020-01-27 10:54:08 +01:00
ping.c ip: support SO_MARK cmsg 2019-09-13 21:44:19 +02:00
proc.c tcp: export count for rehash attempts 2020-01-26 15:28:47 +01:00
protocol.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
raw_diag.c inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data 2020-02-27 18:50:19 -08:00
raw.c raw: Add missing annotations to raw_seq_start() and raw_seq_stop() 2020-03-11 23:19:40 -07:00
route.c net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc. 2020-02-24 13:31:42 -08:00
syncookies.c mptcp: handle tcp fallback when using syn cookies 2020-01-29 17:45:20 +01:00
sysctl_net_ipv4.c tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted. 2020-03-12 12:08:09 -07:00
tcp_bbr.c tcp_bbr: improve arithmetic division in bbr_update_bw() 2020-01-21 10:45:49 +01:00
tcp_bic.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_bpf.c tcp_bpf: Don't let child socket inherit parent protocol ops on copy 2020-02-21 22:29:45 +01:00
tcp_cdg.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_cong.c bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
tcp_cubic.c tcp_cubic: refactor code to perform a divide only when needed 2019-12-30 14:44:27 -08:00
tcp_dctcp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_dctcp.h tcp: refactor DCTCP ECN ACK handling 2018-10-10 22:26:00 -07:00
tcp_diag.c inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data 2020-02-27 18:50:19 -08:00
tcp_fastopen.c tcp: add TCP_INFO status for failed client TFO 2019-10-25 19:25:37 -07:00
tcp_highspeed.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_htcp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_hybla.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_illinois.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_input.c tcp: fix TFO SYNACK undo to avoid double-timestamp-undo 2020-02-23 17:23:35 -08:00
tcp_ipv4.c tcp: ipv4: Pass lockdep expression to RCU lists 2020-02-24 13:07:03 -08:00
tcp_lp.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_metrics.c net-tcp: Disable TCP ssthresh metrics cache by default 2019-12-09 20:17:48 -08:00
tcp_minisocks.c tcp: Add missing annotation for tcp_child_process() 2020-03-11 23:19:41 -07:00
tcp_nv.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_offload.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
tcp_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-01-26 10:40:21 +01:00
tcp_rate.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
tcp_recovery.c tcp: introduce tcp_skb_timestamp_us() helper 2018-09-21 19:37:59 -07:00
tcp_scalable.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_timer.c tcp: export count for rehash attempts 2020-01-26 15:28:47 +01:00
tcp_ulp.c tcp, ulp: Pass lockdep expression to RCU lists 2020-02-24 13:01:54 -08:00
tcp_vegas.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_vegas.h
tcp_veno.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_westwood.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp_yeah.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
tcp.c tcp: add bytes not sent to SCM_TIMESTAMPING_OPT_STATS 2020-03-09 17:56:33 -07:00
tunnel4.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udp_diag.c inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data 2020-02-27 18:50:19 -08:00
udp_impl.h udp: add missing rehash callback to udplite 2019-01-17 15:01:08 -08:00
udp_offload.c udp: Support UDP fraglist GRO/GSO. 2020-01-27 11:00:21 +01:00
udp_tunnel.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
udp.c net: datagram: drop 'destructor' argument from several helpers 2020-02-28 12:12:53 -08:00
udplite.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xfrm4_input.c
xfrm4_output.c netfilter: Support iif matches in POSTROUTING 2019-11-15 23:44:48 +01:00
xfrm4_policy.c net: add bool confirm_neigh parameter for dst_ops.update_pmtu 2019-12-24 22:28:54 -08:00
xfrm4_protocol.c xfrm: add route lookup to xfrm4_rcv_encap 2019-12-09 09:59:07 +01:00
xfrm4_state.c xfrm: remove eth_proto value from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00
xfrm4_tunnel.c xfrm: remove type and offload_type map from xfrm_state_afinfo 2019-06-06 08:34:50 +02:00