linux/net
Florian Westphal 63cc357f7b tcp: do not restart timewait timer on rst reception
RFC 1337 says:
 ''Ignore RST segments in TIME-WAIT state.
   If the 2 minute MSL is enforced, this fix avoids all three hazards.''

So with net.ipv4.tcp_rfc1337=1, expected behaviour is to have TIME-WAIT sk
expire rather than removing it instantly when a reset is received.

However, Linux will also re-start the TIME-WAIT timer.

This causes connect to fail when tying to re-use ports or very long
delays (until syn retry interval exceeds MSL).

packetdrill test case:
// Demonstrate bogus rearming of TIME-WAIT timer in rfc1337 mode.
`sysctl net.ipv4.tcp_rfc1337=1`

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 29200 <mss 1460,nop,nop,sackOK,nop,wscale 7>
0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>
0.200 < . 1:1(0) ack 1 win 257
0.200 accept(3, ..., ...) = 4

// Receive first segment
0.310 < P. 1:1001(1000) ack 1 win 46

// Send one ACK
0.310 > . 1:1(0) ack 1001

// read 1000 byte
0.310 read(4, ..., 1000) = 1000

// Application writes 100 bytes
0.350 write(4, ..., 100) = 100
0.350 > P. 1:101(100) ack 1001

// ACK
0.500 < . 1001:1001(0) ack 101 win 257

// close the connection
0.600 close(4) = 0
0.600 > F. 101:101(0) ack 1001 win 244

// Our side is in FIN_WAIT_1 & waits for ack to fin
0.7 < . 1001:1001(0) ack 102 win 244

// Our side is in FIN_WAIT_2 with no outstanding data.
0.8 < F. 1001:1001(0) ack 102 win 244
0.8 > . 102:102(0) ack 1002 win 244

// Our side is now in TIME_WAIT state, send ack for fin.
0.9 < F. 1002:1002(0) ack 102 win 244
0.9 > . 102:102(0) ack 1002 win 244

// Peer reopens with in-window SYN:
1.000 < S 1000:1000(0) win 9200 <mss 1460,nop,nop,sackOK,nop,wscale 7>

// Therefore, reply with ACK.
1.000 > . 102:102(0) ack 1002 win 244

// Peer sends RST for this ACK.  Normally this RST results
// in tw socket removal, but rfc1337=1 setting prevents this.
1.100 < R 1002:1002(0) win 244

// second syn. Due to rfc1337=1 expect another pure ACK.
31.0 < S 1000:1000(0) win 9200 <mss 1460,nop,nop,sackOK,nop,wscale 7>
31.0 > . 102:102(0) ack 1002 win 244

// .. and another RST from peer.
31.1 < R 1002:1002(0) win 244
31.2 `echo no timer restart;ss -m -e -a -i -n -t -o state TIME-WAIT`

// third syn after one minute.  Time-Wait socket should have expired by now.
63.0 < S 1000:1000(0) win 9200 <mss 1460,nop,nop,sackOK,nop,wscale 7>

// so we expect a syn-ack & 3whs to proceed from here on.
63.0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>

Without this patch, 'ss' shows restarts of tw timer and last packet is
thus just another pure ack, more than one minute later.

This restores the original code from commit 283fd6cf0be690a83
("Merge in ANK networking jumbo patch") in netdev-vger-cvs.git .

For some reason the else branch was removed/lost in 1f28b683339f7
("Merge in TCP/UDP optimizations and [..]") and timer restart became
unconditional.

Reported-by: Michal Tesar <mtesar@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-31 23:10:35 -07:00
..
6lowpan 6lowpan: iphc: reset mac_header after decompress to fix panic 2018-07-06 12:32:12 +02:00
9p Pull request for inclusion in 4.19, take two 2018-08-17 17:27:58 -07:00
802
8021q net: remove blank lines at end of file 2018-07-24 14:10:43 -07:00
appletalk Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
ax25 ax25: remove blank line at EOF 2018-07-24 14:10:42 -07:00
batman-adv Merge ra.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux 2018-07-20 21:17:12 -07:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
bpf bpf/test_run: support cgroup local storage 2018-08-03 00:47:32 +02:00
bpfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
bridge net/bridge/br_multicast: remove redundant variable "err" 2018-08-06 10:33:44 -07:00
caif net: simplify sock_poll_wait 2018-07-30 09:10:25 -07:00
can Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
ceph crush: fix using plain integer as NULL warning 2018-08-13 17:55:44 +02:00
core net: rtnl: return early from rtnl_unregister_all when protocol isn't registered 2018-08-29 19:28:55 -07:00
dcb net: dcb: Add priority-to-DSCP map getters 2018-07-27 13:17:50 -07:00
dccp Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-08-09 11:52:36 -07:00
decnet decnet: fix using plain integer as NULL warning 2018-08-09 14:11:24 -07:00
dns_resolver net: remove blank lines at end of file 2018-07-24 14:10:43 -07:00
dsa net: dsa: Drop GPIO includes 2018-08-27 15:24:33 -07:00
ethernet net: Convert GRO SKB handling to list_head. 2018-06-26 11:33:04 +09:00
hsr
ieee802154 net: ieee802154: 6lowpan: remove redundant pointers 'fq' and 'net' 2018-08-06 11:21:15 +02:00
ife
ipv4 tcp: do not restart timewait timer on rst reception 2018-08-31 23:10:35 -07:00
ipv6 ipv6: fix cleanup ordering for pingv6 registration 2018-08-29 19:28:55 -07:00
iucv net:af_iucv: get rid of the unneeded variable 'err' in afiucv_pm_freeze 2018-08-08 09:39:36 -07:00
kcm net: remove blank lines at end of file 2018-07-24 14:10:43 -07:00
key Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2018-07-27 09:33:37 -07:00
l2tp l2tp: fix unused function warning 2018-08-13 20:45:49 -07:00
l3mdev
lapb
llc Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-08-09 11:52:36 -07:00
mac80211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
mac802154 net: mac802154: tx: expand tailroom if necessary 2018-08-06 11:21:37 +02:00
mpls mpls: remove trailing whitepace 2018-07-24 14:10:42 -07:00
ncsi net/ncsi: Fixup .dumpit message flags and ID check in Netlink handler 2018-08-22 21:39:08 -07:00
netfilter treewide: convert ISO_8859-1 text comments to utf-8 2018-08-23 18:48:43 -07:00
netlabel audit: eliminate audit_enabled magic number comparison 2018-06-19 10:43:55 -04:00
netlink Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-08-05 13:04:31 -07:00
netrom Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
nfc net: simplify sock_poll_wait 2018-07-30 09:10:25 -07:00
nsh nsh: set mac len based on inner packet 2018-07-12 16:55:29 -07:00
openvswitch Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-08-02 10:55:32 -07:00
packet Revert "packet: switch kvzalloc to allocate memory" 2018-08-31 23:00:28 -07:00
phonet Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
psample
qrtr net: qrtr: Reset the node and port ID of broadcast messages 2018-07-05 20:20:03 +09:00
rds net/rds: RDS is not Radio Data System 2018-08-31 23:09:53 -07:00
rfkill leds: triggers: let struct led_trigger::activate() return an error code 2018-07-05 23:21:10 +02:00
rose Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
sched net_sched: reject unknown tcfa_action values 2018-08-29 22:10:59 -07:00
sctp sctp: remove useless start_fail from sctp_ht_iter in proc 2018-08-27 15:13:17 -07:00
smc RDMA/smc: Replace ib_query_gid with rdma_get_gid_attr 2018-08-17 16:45:51 -06:00
strparser strparser: remove redundant variable 'rd_desc' 2018-08-01 10:00:06 -07:00
sunrpc NFS client updates for Linux 4.19 2018-08-23 16:03:58 -07:00
switchdev
tipc tipc: switch to rhashtable iterator 2018-08-29 18:04:54 -07:00
tls tls: possible hang when do_tcp_sendpages hits sndbuf is full case 2018-08-22 21:57:14 +02:00
unix af_unix: ensure POLLOUT on remote close() for connected dgram socket 2018-08-03 16:44:19 -07:00
vmw_vsock vsock: split dwork to avoid reinitializations 2018-08-07 12:39:13 -07:00
wimax wimax: remove blank lines at EOF 2018-07-24 14:10:42 -07:00
wireless Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-07-24 19:21:58 -07:00
x25 x25: remove blank lines at EOF 2018-07-24 14:10:42 -07:00
xdp xsk: fix return value of xdp_umem_assign_dev() 2018-08-21 22:06:53 +02:00
xfrm Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-08-02 10:55:32 -07:00
compat.c net: avoid unnecessary sock_flag() check when enable timestamp 2018-08-06 10:42:48 -07:00
Kconfig net: remove blank lines at end of file 2018-07-24 14:10:43 -07:00
Makefile bpfilter: check compiler capability in Kconfig 2018-06-28 13:36:39 +09:00
socket.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
sysctl_net.c