mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-08-31 08:15:07 -04:00
217828aad8
BPF_FIB_LOOKUP_VLAN resolves a VLAN egress. The reverse is also useful: an XDP program receiving a VLAN-tagged frame on a physical device wants the lookup to behave as if the packet had arrived on the corresponding VLAN subinterface, so iif-based policy routing and VRF table selection use the right ingress. Add BPF_FIB_LOOKUP_VLAN_INPUT. When set, params->h_vlan_proto and params->h_vlan_TCI are read as an input VLAN tag and the matching VLAN device of params->ifindex is resolved with __vlan_find_dev_deep_rcu(). The device must be up and in the same network namespace as params->ifindex (a VLAN device can be moved to another netns while registered on its parent; receive would deliver into that other namespace, which a lookup here cannot represent). If params->ifindex is itself a VLAN device, its inner (QinQ) subinterface is matched. For a bond or team, a tag on a port matches no device and returns NOT_FWDED; pass the master's ifindex. The lookup then runs with the resolved device as the ingress; params->ifindex itself is not modified on the input side. When the resolved device is enslaved to a VRF, both the full lookup (via the l3mdev rule) and BPF_FIB_LOOKUP_DIRECT (via l3mdev_fib_table_rcu()) select the VRF's table from the resolved ingress. That follows from feeding the resolved device to the flow as the ingress (fl4.flowi4_iif = dev->ifindex), which is what makes l3mdev resolve the VRF master from the subinterface rather than from params->ifindex. The two failure classes get different treatment on purpose. A h_vlan_proto other than 802.1Q/802.1ad is API misuse and returns -EINVAL, since it would otherwise reach the WARN in vlan_proto_idx() with a program-controlled value. An unmatched VID, a device that is down, or one in another namespace is a data outcome and returns BPF_FIB_LKUP_RET_NOT_FWDED, matching the DIRECT path when fib_get_table() finds no table and mirroring real ingress, where the receive path drops such frames. A VID of 0 (a priority tag) is looked up literally and normally fails the same way; receive instead processes such frames untagged, so callers should not set the flag for priority tags. Proceeding on the physical device for any of these would be fail-open for the policy-routing cases above. The h_vlan fields share a union with tbid, so the flag cannot be combined with BPF_FIB_LOOKUP_TBID. It describes ingress, so it also cannot be combined with BPF_FIB_LOOKUP_OUTPUT. Both combinations return -EINVAL; restricting now keeps a later relaxation backward compatible. Combining with BPF_FIB_LOOKUP_VLAN is allowed: the tag is consumed on the ingress side and the egress tag is written on success. Under !CONFIG_VLAN_8021Q the __vlan_find_dev_deep_rcu() stub returns NULL, so every lookup with a valid proto returns NOT_FWDED, which is correct since no VLAN device can exist. Suggested-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Avinash Duduskar <avinash.duduskar@gmail.com> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/bpf/20260713162305.1237211-3-avinash.duduskar@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
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