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Luke Hsiao 4b1b4d3f45 tcp: enable data-less, empty-cookie SYN with TFO_SERVER_COOKIE_NOT_REQD
[ Upstream commit e3faa49bce ]

Since the original TFO server code was implemented in commit
168a8f5805 ("tcp: TCP Fast Open Server -
main code path") the TFO server code has supported the sysctl bit flag
TFO_SERVER_COOKIE_NOT_REQD. Currently, when the TFO_SERVER_ENABLE and
TFO_SERVER_COOKIE_NOT_REQD sysctl bit flags are set, a server connection
will accept a SYN with N bytes of data (N > 0) that has no TFO cookie,
create a new fast open connection, process the incoming data in the SYN,
and make the connection ready for accepting. After accepting, the
connection is ready for read()/recvmsg() to read the N bytes of data in
the SYN, ready for write()/sendmsg() calls and data transmissions to
transmit data.

This commit changes an edge case in this feature by changing this
behavior to apply to (N >= 0) bytes of data in the SYN rather than only
(N > 0) bytes of data in the SYN. Now, a server will accept a data-less
SYN without a TFO cookie if TFO_SERVER_COOKIE_NOT_REQD is set.

Caveat! While this enables a new kind of TFO (data-less empty-cookie
SYN), some firewall rules setup may not work if they assume such packets
are not legit TFOs and will filter them.

Signed-off-by: Luke Hsiao <lukehsiao@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210816205105.2533289-1-luke.w.hsiao@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-09-18 13:40:29 +02:00
arch arm64: dts: ls1046a: fix eeprom entries 2021-09-18 13:40:28 +02:00
block scsi: bsg: Remove support for SCSI_IOCTL_SEND_COMMAND 2021-09-18 13:40:11 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: sm2 - fix a memory leak in sm2 2021-07-14 16:56:06 +02:00
Documentation docs: Fix infiniband uverbs minor number 2021-09-18 13:40:11 +02:00
drivers serial: sh-sci: fix break handling for sysrq 2021-09-18 13:40:29 +02:00
fs iomap: pass writeback errors to the mapping 2021-09-18 13:40:29 +02:00
include serial: 8250: Define RX trigger levels for OxSemi 950 devices 2021-09-18 13:40:22 +02:00
init sched/core: Initialize the idle task with preemption disabled 2021-07-14 16:55:50 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel workqueue: Fix possible memory leaks in wq_numa_init() 2021-09-18 13:40:23 +02:00
lib bpf/tests: Do not PASS tests without actually testing the result 2021-09-18 13:40:21 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/page_alloc: speed up the iteration of max_order 2021-09-12 08:58:26 +02:00
net tcp: enable data-less, empty-cookie SYN with TFO_SERVER_COOKIE_NOT_REQD 2021-09-18 13:40:29 +02:00
samples samples: bpf: Fix tracex7 error raised on the missing argument 2021-09-18 13:40:23 +02:00
scripts kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y 2021-09-18 13:40:16 +02:00
security Smack: Fix wrong semantics in smk_access_entry() 2021-09-18 13:40:18 +02:00
sound ASoC: Intel: update sof_pcm512x quirks 2021-09-18 13:40:24 +02:00
tools selftests/bpf: Fix xdp_tx.c prog section name 2021-09-18 13:40:27 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:22:17 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.66 2021-09-16 12:51:23 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.