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Zhiling Zou 112e447d17 netfilter: validate L4 headers after userspace packet writes
NFQUEUE and nft_payload can hand packet data modified by userspace back
to the stack. Recent restrictions keep link and network headers stable,
but transport header fields can still be changed.

A packet can therefore keep the same network header and conntrack entry
while changing the transport header layout. For TCP, increasing doff can
make later helper or NAT code use a different transport-header base than
the parser used, and can make offsets point past skb->tail.

Extend NFQUEUE payload validation to check the final L4 protocol and
known base headers after IPv4 options or IPv6 extension headers. Reject
packets whose L4 protocol no longer matches an attached non-template
conntrack entry, and reject IP fragments that already have such a
conntrack entry before trying to validate transport headers. Unknown L4
protocols are left to their normal protocol handlers.

For nft payload writes, reject transport-header stores that overlap TCP
doff. nft_nh_write_ok() already rejects network-header protocol changes,
so keeping doff stable prevents nft payload writes from changing the TCP
header length underneath conntrack and helper users.

This patch is a follow up to commit df07998dfd ("netfilter: nftables:
restrict linklayer and network header writes") and commit 54f34607d1
("netfilter: nfnetlink_queue: restrict writes to network header").

Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Zhiling Zou <zhilinz@nebusec.ai>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
History 2026-08-18 00:51:40 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
block block: stop the timeout timer when releasing a never added disk 2026-07-29 05:23:20 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push contains the following changes: 2026-08-10 08:36:22 -07:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
drivers net/mlx5: SD, prefer sd_group_size from vport context 2026-08-14 12:27:12 -07:00
fs tracing fixes for 7.2: 2026-08-09 08:47:31 -07:00
include net/mlx5: SD, prefer sd_group_size from vport context 2026-08-14 12:27:12 -07:00
init rust: allow suspicious_runtime_symbol_definitions lint for Rust >= 1.98 2026-06-29 13:02:15 +02:00
io_uring io_uring: preserve task restrictions across exec 2026-07-30 14:40:22 -06:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm 17 hotfixes. 15 are cc:stable. 16 are for MM. 2026-08-06 20:29:38 -07:00
net netfilter: validate L4 headers after userspace packet writes 2026-08-18 00:51:40 +02:00
rust Driver core fixes for 7.2-rc7 2026-08-08 07:13:29 -07:00
samples samples/damon/mtier: error out for zero quota goal target values 2026-08-04 20:02:02 -07:00
scripts kbuild: rpm-pkg: Preserve BTF sections in kernel modules during debuginfo stripping 2026-07-29 16:21:42 -07:00
security selinux/stable-7.2 PR 20260805 2026-08-05 13:40:11 -07:00
sound ALSA: usb-audio: Fix sticky mixer regressions on M-Audio Fast Track Ultra 2026-08-07 10:35:31 +02:00
tools netfilter pull request 26-08-10 2026-08-14 12:23:12 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM/arm64 fixes for 7.2, take #2 2026-07-15 12:13:30 +02:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-04-02 16:48:25 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap There is a known WiFi/mt76 regression, waiting for a complete fix that 2026-08-13 08:37:26 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.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 CREDITS: Add Wolfram Sang 2026-07-14 16:34:04 +02:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-08-13 11:00:14 -07:00
Makefile Linux 7.2-rc7 2026-08-09 14:54:50 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -07:00

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

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst