0013: Permissive proto/sdk; dual-licensed eBPF (D-013)

ADR-0013: Permissive proto/sdk; dual-licensed eBPF (D-013)

• Status: Accepted (legal review pending, P-10)
• Date: 2026-11-01
• Related: ADR-0012

Context

Third parties (including the proprietary managed plugin) need to link the contract types and the plugin SDK. Linking GPL code from a closed plugin would create a derivative work and block that path. eBPF programs loaded into the kernel interact with GPL-only kernel helpers, which constrains licensing of that code specifically.

Options considered

• Everything GPL: simplest tree; kills third-party plugin licensing freedom and the managed-plugin architecture.
• Everything permissive: loses copyleft on the client itself.
• Split by boundary (chosen): contracts and SDK permissive; client GPL; eBPF dual.

Decision

• ibexwall-proto and ibexwall-sdk: Apache-2.0 OR MIT, and they must never depend on GPL-only crates (enforced in review and by cargo-deny configuration when they gain dependencies).
• ibexwall-ebpf: GPL-2.0-only OR MIT (dual), satisfying kernel helper licensing while keeping the option of permissive reuse of that code.

Consequences

• Speaking varlink to the GPL daemon over IPC does not create derivative works; linking the crates would. The boundary is crate-level and documented in LICENSE and REUSE.toml.
• Requires contributors to keep the boundary clean; CI lint for dependency direction is a follow-up task.
• Flagged for legal validation together with ADR-0012 (P-10).