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Maoyi Xie c96a5209dd rds: filter RDS_INFO_* getsockopt by caller's netns
The RDS_INFO_* family of getsockopt(2) options reads several
file-scope global lists that are not per-netns:

  rds_sock_info / rds6_sock_info,
  rds_sock_inc_info / rds6_sock_inc_info        -> rds_sock_list
  rds_tcp_tc_info / rds6_tcp_tc_info            -> rds_tcp_tc_list
  rds_conn_info / rds6_conn_info,
  rds_conn_message_info_cmn (for the *_SEND_MESSAGES and
  *_RETRANS_MESSAGES variants),
  rds_for_each_conn_info (for RDS_INFO_IB_CONNECTIONS)
                                                -> rds_conn_hash[]

The handlers do not filter by the caller's network namespace.
rds_info_getsockopt() has no netns or capable() check, and
rds_create() has no capable() check, so AF_RDS is reachable from
an unprivileged user namespace. As a result, an unprivileged
caller in a fresh user_ns plus netns can read the bound address
and sock inode of every RDS socket on the host, the peer address
of incoming messages on every RDS socket on the host, the peer
address and TCP sequence numbers of every rds-tcp connection on
the host, and the peer address and RDS sequence numbers of every
RDS connection on the host.

The rds-tcp transport is reachable from a non-initial netns (see
rds_set_transport()), so a one-shot init_net gate at
rds_info_getsockopt() would deny legitimate per-netns visibility
to rds-tcp callers. Instead, filter at each handler by comparing
the netns of the caller's socket to the netns of the list entry,
or to rds_conn_net(conn) for connection paths. Only copy entries
whose netns matches the caller. Counters (RDS_INFO_COUNTERS) are
aggregate statistics and remain global.

Reproducer (KASAN VM, rds and rds_tcp loaded): an AF_RDS socket
binds 127.0.0.1:4242 in init_net as root. A child process enters
a fresh user_ns plus netns and opens AF_RDS there, then calls
getsockopt(SOL_RDS, RDS_INFO_SOCKETS). Before this change, the
child sees the init_net socket. After this change, the child
sees zero entries.

Drop the rds_sock_count, rds_tcp_tc_count, and rds6_tcp_tc_count
globals. v2 used them for the size precheck and lens->nr; v3
replaced the precheck with a per-ns count from a first pass over
the list, so the globals have no remaining readers. The matching
increments and decrements in rds_create()/rds_destroy_sock() and
rds_tcp_set_callbacks()/rds_tcp_restore_callbacks() go away with
them. Reported by the kernel test robot under clang W=1.

Suggested-by: Allison Henderson <achender@kernel.org>
Suggested-by: Simon Horman <horms@kernel.org>
Reviewed-by: Allison Henderson <achender@kernel.org>
Co-developed-by: Praveen Kakkolangara <praveen.kakkolangara@aumovio.com>
Signed-off-by: Praveen Kakkolangara <praveen.kakkolangara@aumovio.com>
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Link: https://patch.msgid.link/20260520084236.2724349-1-maoyixie.tju@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-25 12:18:42 -07:00
arch net: arcnet: remove ISA and PCMCIA support; modernize documentation 2026-05-22 17:20:56 -07:00
block block: align down bounces bios 2026-05-13 13:55:18 -06:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto crypto/krb5, rxrpc: Fix lack of pre-decrypt/pre-verify length checks 2026-05-20 16:36:45 -07:00
Documentation docs: net: arcnet: remove outdated/irrelevant information; improve style 2026-05-22 17:20:57 -07:00
drivers net: dsa: microchip: bypass dev_ops for phy_read()/phy_write() 2026-05-22 18:40:49 -07:00
fs Changes since last update: 2026-05-20 13:19:58 -05:00
include dpll: change dpll_netdev_pin_handle_size() to assume DPLL_A_PIN_ID will be used 2026-05-22 17:33:22 -07:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring-7.1-20260515 2026-05-15 12:34:02 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel ring-buffer fixes for 7.1: 2026-05-21 14:05:09 -07:00
lib 14 hotfixes. 9 are for MM. 10 are cc:stable and the remainder are for 2026-05-19 07:49:33 -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 14 hotfixes. 9 are for MM. 10 are cc:stable and the remainder are for 2026-05-19 07:49:33 -07:00
net rds: filter RDS_INFO_* getsockopt by caller's netns 2026-05-25 12:18:42 -07:00
rust Rust fixes for v7.1 2026-05-09 11:24:02 -07:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts Second round of Kbuild fixes for 7.1 2026-05-19 09:43:24 -07:00
security lsm/stable-7.1 PR 20260519 2026-05-19 15:31:35 -05:00
sound ALSA: hda/ca0132: Disable auto-detect on manual output select 2026-05-15 11:19:48 +02:00
tools selftests: tls: use ASSERT_GE in test_mutliproc 2026-05-22 15:36:51 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM: Reject wrapped offset in kvm_reset_dirty_gfn() 2026-05-12 22:16:16 +02:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.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 kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap Including fixes from Bluetooth, wireless and netfilter. 2026-05-21 14:39:12 -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 Delete some obsolete networking code 2026-04-24 09:41:58 -07:00
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 Not much going on here right now: 2026-05-21 16:00:06 -07:00
Makefile Linux 7.1-rc4 2026-05-17 13:59:58 -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