Avoid Docker firewall policy bypass - #82
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Unconnected raw ICMP sockets receive every ICMP packet arriving at the host, so any ICMP traffic refreshed the read deadline of every flow and stale flows (with their raw sockets and goroutines) were only reclaimed by LRU eviction while processing all host ICMP traffic in the meantime. Expire flows based on their own activity only, and on Linux attach a classic BPF ident filter to each raw socket so other flows' packets are dropped in the kernel instead of waking every flow.
Support filtering traffic by source MAC address in the prerouting chain, using ether addr payload matching with set lookups for multiple addresses.
Unconnected raw ICMP sockets receive every ICMP packet arriving at the host, so any ICMP traffic refreshed the read deadline of every flow and stale flows (with their raw sockets and goroutines) accumulated forever, making per-ping cost grow linearly with uptime. Expire flows based on their own activity only, and on Linux attach a classic BPF ident filter to each raw socket so other flows' packets are dropped in the kernel instead of waking every flow.
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Motivation
ACCEPTrules into Docker'sDOCKER-USERchain.Description
startDockerFirewallMonitor()/configureDockerFirewall(false)calls insetupNFTables()(redirect_nftables.go).reconcileDockerFirewallRulesno longer insertsACCEPTrules and instead only removes existing sing-tun compatibility rules by delegating tocleanupDockerFirewallRules(redirect_nftables_docker.go).table/chainparameters when not needed to avoid inserting rules intoDOCKER-USER.redirect_nftables_docker_test.gothat verify reconciliation does not queue insertions and that existing compatibility rules are cleaned up.Testing
go test ./...and all tests passed, including the newTestDockerFirewallReconcileDoesNotInsertAcceptRulesandTestDockerFirewallReconcileCleansExistingCompatibilityRuleswhich succeeded.Codex Task