linux/include
Eric Dumazet 7c85af8810 tcp: avoid reorders for TFO passive connections
We found that a TCP Fast Open passive connection was vulnerable
to reorders, as the exchange might look like

[1] C -> S S <FO ...> <request>
[2] S -> C S. ack request <options>
[3] S -> C . <answer>

packets [2] and [3] can be generated at almost the same time.

If C receives the 3rd packet before the 2nd, it will drop it as
the socket is in SYN_SENT state and expects a SYNACK.

S will have to retransmit the answer.

Current OOO avoidance in linux is defeated because SYNACK
packets are attached to the LISTEN socket, while DATA packets
are attached to the children. They might be sent by different cpus,
and different TX queues might be selected.

It turns out that for TFO, we created a child, which is a
full blown socket in TCP_SYN_RECV state, and we simply can attach
the SYNACK packet to this socket.

This means that at the time tcp_sendmsg() pushes DATA packet,
skb->ooo_okay will be set iff the SYNACK packet had been sent
and TX completed.

This removes the reorder source at the host level.

We also removed the export of tcp_try_fastopen(), as it is no
longer called from IPv6.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-28 22:11:19 -07:00
..
acpi ACPI: Eliminate CONFIG_.*{, _MODULE} #ifdef in favor of IS_ENABLED() 2015-09-15 03:05:45 +02:00
asm-generic Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2015-09-19 19:13:03 -07:00
clocksource
crypto Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2015-09-08 12:41:25 -07:00
drm Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-09-04 15:49:32 -07:00
dt-bindings Merge branch 'drivers/reset' into next/late 2015-09-09 15:42:45 -07:00
keys
kvm arm/arm64: KVM: Remove 'config KVM_ARM_MAX_VCPUS' 2015-09-17 13:13:27 +01:00
linux Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-09-26 16:08:27 -07:00
math-emu
media media updates for v4.3-rc1 2015-09-11 16:42:39 -07:00
memory
misc
net tcp: avoid reorders for TFO passive connections 2015-09-28 22:11:19 -07:00
pcmcia
ras
rdma Changes for 4.3-rc1 2015-09-19 20:04:11 -07:00
rxrpc
scsi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-09-11 19:00:42 -07:00
soc IOMMU Updates for Linux v4.3 2015-09-08 17:22:35 -07:00
sound ALSA: hda - Fix missing inline for dummy snd_hdac_set_codec_wakeup() 2015-09-02 12:24:55 +02:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2015-09-11 19:00:42 -07:00
trace Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2015-09-11 16:13:47 -07:00
uapi Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-09-26 16:08:27 -07:00
video libnvdimm for 4.3: 2015-09-08 14:35:59 -07:00
xen xen: MFN/GFN/BFN terminology changes for 4.3-rc0 2015-09-10 16:21:11 -07:00
Kbuild