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Steffen Klassert
355f808d8a
Antony Antony says: ==================== The current XFRM_MSG_MIGRATE interface is tightly coupled to policy and SA migration, and it lacks the information required to reliably migrate individual SAs. This makes it unsuitable for IKEv2 deployments, dual-stack setups (IPv4/IPv6), and scenarios where policies are managed externally (e.g., by daemons other than the IKE daemon). Mandatory SA selector list The current API requires a non-empty SA selector list, which does not reflect the IKEv2 use case. A single Child SA may correspond to multiple policies, and SA discovery already occurs via address and reqid matching. With dual-stack Child SAs this leads to excessive churn: the current method would have to be called up to six times (in/out/fwd × v4/v6) on SA, while the new method only requires two calls. Selectors lack SPI (and marks) XFRM_MSG_MIGRATE cannot uniquely identify an SA when multiple SAs share the same policies (per-CPU SAs, SELinux label-based SAs, etc.). Without the SPI, the kernel may update the wrong SA instance. Reqid cannot be changed Some implementations allocate reqids based on traffic selectors. In host-to-host or selector-changing scenarios, the reqid must change, which the current API cannot express. Because strongSwan and other implementations manage policies independently of the kernel, an interface that updates only a specific SA - with complete and unambiguous identification - is required. SA Selector, x->sel, can't be changed, especially Transport mode. XFRM_MSG_MIGRATE_STATE provides that interface. It supports migration of a single SA via xfrm_usersa_id (including SPI) and we fix encap removal in this patch set, reqid updates, address changes, and other SA-specific parameters. It avoids the structural limitations of XFRM_MSG_MIGRATE and provides a simpler, extensible mechanism for precise per-SA migration without involving policies. This method also allows migtrating SA selectors typically used with host-to-host in Transport mode. New migration steps: first install block policy, remove the old policy, call XFRM_MSG_MIGRATE_STATE for each state, then re-install the policies and remove the block policy. If the target SA tuple (daddr, SPI, proto, family) is already occupied, the operation returns -EEXIST. In this case the original SA is not preserved. Userspace must handle -EEXIST by re-establishing the SA at the IKE level and manage policies. ==================== Signed-off-by: Steffen Klassert <steffen.klassert@secunet.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! 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