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Florian Westphal c410cb974f netfilter: conntrack: handle tcp challenge acks during connection reuse
When a connection is re-used, following can happen:
[ connection starts to close, fin sent in either direction ]
 > syn   # initator quickly reuses connection
 < ack   # peer sends a challenge ack
 > rst   # rst, sequence number == ack_seq of previous challenge ack
 > syn   # this syn is expected to pass

Problem is that the rst will fail window validation, so it gets
tagged as invalid.

If ruleset drops such packets, we get repeated syn-retransmits until
initator gives up or peer starts responding with syn/ack.

Before the commit indicated in the "Fixes" tag below this used to work:

The challenge-ack made conntrack re-init state based on the challenge
ack itself, so the following rst would pass window validation.

Add challenge-ack support: If we get ack for syn, record the ack_seq,
and then check if the rst sequence number matches the last ack number
seen in reverse direction.

Fixes: c7aab4f170 ("netfilter: nf_conntrack_tcp: re-init for syn packets only")
Reported-by: Michal Tesar <mtesar@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2023-01-17 23:00:06 +01:00
arch s390 updates for 6.2-rc4 2023-01-12 17:09:20 -06:00
block block-2023-01-06 2023-01-06 13:12:42 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation Including fixes from rxrpc. 2023-01-12 18:20:44 -06:00
drivers net: stmmac: fix invalid call to mdiobus_get_phy() 2023-01-17 13:33:19 +01:00
fs Including fixes from rxrpc. 2023-01-12 18:20:44 -06:00
include net/sched: sch_taprio: fix possible use-after-free 2023-01-16 13:25:34 +00:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-09 17:04:49 -06:00
io_uring io_uring: fix CQ waiting timeout handling 2023-01-05 08:04:47 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel - Fix various DocBook formatting errors in kernel/time/ that 2023-01-12 16:53:39 -06:00
lib v6.2 first rc pull request 2023-01-07 10:06:47 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm memblock: Fix doc for memblock_phys_free 2023-01-04 12:31:22 +02:00
net netfilter: conntrack: handle tcp challenge acks during connection reuse 2023-01-17 23:00:06 +01:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Char/Misc driver changes for 6.2-rc1 2022-12-16 03:49:24 -08:00
scripts kbuild: readd -w option when vmlinux.o or Module.symver is missing 2023-01-05 16:53:48 +09:00
security kernel hardening fixes for v6.2-rc1 2022-12-23 12:00:24 -08:00
sound xen: branch for v6.2-rc4 2023-01-12 17:02:20 -06:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf 2023-01-16 13:10:16 +00:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-late-6.1-fixes' into HEAD 2022-12-28 07:19:14 -05:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap MAINTAINERS: Update email of Tudor Ambarus 2023-01-07 15:18:44 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: zram: zsmalloc: Add an additional co-maintainer 2022-12-15 16:37:49 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MTD changes: 2023-01-12 05:56:06 -06:00
Makefile Linux 6.2-rc3 2023-01-08 11:49:43 -06:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.