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0e40f4c959
linux/net/ipv4
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Jason Baron 0e40f4c959 tcp: accept RST for rcv_nxt - 1 after receiving a FIN 
Using a Mac OSX box as a client connecting to a Linux server, we have found
that when certain applications (such as 'ab'), are abruptly terminated
(via ^C), a FIN is sent followed by a RST packet on tcp connections. The
FIN is accepted by the Linux stack but the RST is sent with the same
sequence number as the FIN, and Linux responds with a challenge ACK per
RFC 5961. The OSX client then sometimes (they are rate-limited) does not
reply with any RST as would be expected on a closed socket.

This results in sockets accumulating on the Linux server left mostly in
the CLOSE_WAIT state, although LAST_ACK and CLOSING are also possible.
This sequence of events can tie up a lot of resources on the Linux server
since there may be a lot of data in write buffers at the time of the RST.
Accepting a RST equal to rcv_nxt - 1, after we have already successfully
processed a FIN, has made a significant difference for us in practice, by
freeing up unneeded resources in a more expedient fashion.

A packetdrill test demonstrating the behavior:

// testing mac osx rst behavior

// Establish a connection
0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
0.000 bind(3, ..., ...) = 0
0.000 listen(3, 1) = 0

0.100 < S 0:0(0) win 32768 <mss 1460,nop,wscale 10>
0.100 > S. 0:0(0) ack 1 <mss 1460,nop,wscale 5>
0.200 < . 1:1(0) ack 1 win 32768
0.200 accept(3, ..., ...) = 4

// Client closes the connection
0.300 < F. 1:1(0) ack 1 win 32768

// now send rst with same sequence
0.300 < R. 1:1(0) ack 1 win 32768

// make sure we are in TCP_CLOSE
0.400 %{
assert tcpi_state == 7
}%

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: Eric Dumazet <edumazet@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-17 15:51:55 -05:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2017-01-05 11:49:57 -05:00
af_inet.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
ah4.c
arp.c net: rename NET_{ADD|INC}_STATS_BH() 2016-04-27 22:48:24 -04:00
cipso_ipv4.c Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/selinux into next 2016-07-07 10:15:34 +10:00
datagram.c
devinet.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
esp4.c esp4: Fix integrity verification when ESN are used 2016-11-30 11:09:39 +01:00
fib_frontend.c ipv4: Do not allow MAIN to be alias for new LOCAL w/ custom rules 2017-01-03 09:38:34 -05:00
fib_lookup.h
fib_rules.c switchdev: remove FIB offload infrastructure 2016-09-28 04:48:00 -04:00
fib_semantics.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-17 15:19:37 -05:00
fib_trie.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
fou.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
gre_demux.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-06-30 05:03:36 -04:00
gre_offload.c net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
icmp.c net: for rate-limited ICMP replies save one atomic operation 2017-01-09 15:49:12 -05:00
igmp.c igmp: Make igmp group member RFC 3376 compliant 2017-01-02 13:01:03 -05:00
inet_connection_sock.c inet: Fix get port to handle zero port number with soreuseport set 2016-12-17 11:13:19 -05:00
inet_diag.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
inet_fragment.c net: disable fragment reassembly if high_thresh is zero 2016-06-05 22:56:42 -04:00
inet_hashtables.c net: Require exact match for TCP socket lookups if dif is l3mdev 2016-10-17 10:17:05 -04:00
inet_timewait_sock.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
inetpeer.c
ip_forward.c ipv4: allow local fragmentation in ip_finish_output_gso() 2016-11-03 16:10:26 -04:00
ip_fragment.c net: rename IP_INC_STATS_BH() 2016-04-27 22:48:23 -04:00
ip_gre.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_input.c net: VRF: Pass original iif to ip_route_input() 2016-09-16 04:24:07 -04:00
ip_options.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_output.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ip_sockglue.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-05 11:03:07 -05:00
ip_tunnel_core.c net: make ndo_get_stats64 a void function 2017-01-08 17:51:44 -05:00
ip_tunnel.c netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ip_vti.c netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ipcomp.c
ipconfig.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ipip.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
ipmr.c ipmr: improve hash scalability 2017-01-12 16:48:26 -05:00
Kconfig Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-12-03 12:29:53 -05:00
Makefile net: ip, diag -- Add diag interface for raw sockets 2016-10-23 19:35:24 -04:00
netfilter.c netfilter: Update ip_route_me_harder to consider L3 domain 2016-11-24 12:44:36 +01:00
ping.c net: ping: Use right format specifier to avoid type casting 2017-01-17 15:25:55 -05:00
proc.c ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob 2016-12-29 11:38:31 -05:00
protocol.c
raw_diag.c net: ip, raw_diag -- Use jump for exiting from nested loop 2016-11-03 15:25:26 -04:00
raw.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
route.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-01-17 15:19:37 -05:00
syncookies.c syncookies: use SipHash in place of SHA1 2017-01-09 13:58:57 -05:00
sysctl_net_ipv4.c tcp: remove thin_dupack feature 2017-01-13 22:37:16 -05:00
tcp_bbr.c tcp_bbr: add a state transition diagram and accompanying comment 2016-10-29 17:12:43 -04:00
tcp_bic.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_cdg.c tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict 2016-09-21 00:22:59 -04:00
tcp_cong.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-22 13:27:16 -05:00
tcp_cubic.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_dctcp.c Revert "dctcp: update cwnd on congestion event" 2016-12-06 11:34:24 -05:00
tcp_diag.c net: diag: Fix refcnt leak in error path destroying socket 2016-08-23 23:11:36 -07:00
tcp_fastopen.c tcp: fix tcp_fastopen unaligned access complaints on sparc 2017-01-13 12:31:24 -05:00
tcp_highspeed.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_htcp.c tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_hybla.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_illinois.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_input.c tcp: accept RST for rcv_nxt - 1 after receiving a FIN 2017-01-17 15:51:55 -05:00
tcp_ipv4.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_lp.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_metrics.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_minisocks.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_nv.c tcp: add NV congestion control 2016-06-10 23:07:49 -07:00
tcp_offload.c gso: Support partial splitting at the frag_list pointer 2016-09-19 20:59:34 -04:00
tcp_output.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_probe.c net: ipv4: tcp_probe: Replace timespec with timespec64 2016-03-01 17:18:44 -05:00
tcp_rate.c tcp: export data delivery rate 2016-09-21 00:23:00 -04:00
tcp_recovery.c tcp: enable RACK loss detection to trigger recovery 2017-01-13 22:37:16 -05:00
tcp_scalable.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_timer.c tcp: remove early retransmit 2017-01-13 22:37:16 -05:00
tcp_vegas.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_vegas.h tcp: replace cnt & rtt with struct in pkts_acked() 2016-05-11 14:43:19 -04:00
tcp_veno.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp_westwood.c tcp: make undo_cwnd mandatory for congestion modules 2016-11-21 13:20:17 -05:00
tcp_yeah.c tcp: add cwnd_undo functions to various tcp cc algorithms 2016-11-21 13:20:17 -05:00
tcp.c tcp: remove thin_dupack feature 2017-01-13 22:37:16 -05:00
tunnel4.c tunnels: correct conditional build of MPLS and IPv6 2016-07-11 13:27:06 -07:00
udp_diag.c net: inet: diag: expose the socket mark to privileged processes. 2016-09-08 16:13:09 -07:00
udp_impl.h udplite: call proper backlog handlers 2016-11-24 15:32:14 -05:00
udp_offload.c net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
udp_tunnel.c net: Remove deprecated tunnel specific UDP offload functions 2016-06-17 20:23:32 -07:00
udp.c udp: inuse checks can quit early for reuseport 2017-01-06 20:56:48 -05:00
udplite.c udplite: call proper backlog handlers 2016-11-24 15:32:14 -05:00
xfrm4_input.c
xfrm4_mode_beet.c
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c
xfrm4_output.c
xfrm4_policy.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-12 15:52:44 -07:00
xfrm4_protocol.c
xfrm4_state.c
xfrm4_tunnel.c