fix(srv6): fail closed in DSR eligibility for nil IPAM and dual-stack#26
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Two fail-open gaps in dsrEligible: - the pod-backed backend check (the guard that keeps host-network backed services like the apiserver off DSR) was wrapped in 'if s.felixServerIpam != nil', so a nil IPAM view skipped it entirely. Treat nil as fail-closed: without the IPAM view we cannot verify backends are pod-backed, so keep the service on cnat. - dual-stack services were accepted: buildDSRServices programs only the IPv6 ClusterIP while GetLocalService suppresses cnat for ALL ClusterIPs of a DSR service, so the IPv4 ClusterIP got neither path (blackhole). Reject any service with an IPv4 ClusterIP.
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What
Two fail-open gaps in
dsrEligible:if s.felixServerIpam != nil, so a nil IPAM view skipped the whole guard. A security guard must not depend on a nilable field.buildDSRServicesprograms only the IPv6 ClusterIP whileGetLocalServicesuppresses cnat for all ClusterIPs of a DSR service, so the IPv4 ClusterIP got neither path.Fix
felixServerIpam == nil→ fail closed (keep on cnat)Review finding
Info I4 (nil-guard fail-open) + Low L5 (dual-stack blackhole). Both harden the same eligibility gate.
Test
GOOS=linux go vet ./calico-vpp-agent/services/...green (services package can't run natively on darwin: config→netlink).