feat(bpf): implement allow_port program#42
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leodido wants to merge 4 commits intofeat/allow-ipfrom
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leodido
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allow_port program
fntlnz
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Apr 30, 2026
| return TC_ACT_OK; | ||
| } | ||
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| if (ip_is_fragment(skb, l3_offset)) |
fntlnz
reviewed
Apr 30, 2026
| } | ||
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| struct iphdr *ip_header = data + l3_offset; | ||
| const int l4_offset = l3_offset + sizeof(*ip_header); |
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I think that we should use the ihl field of the packet here instead of the fixed struct size
| if (data + l4_offset + 4 > data_end) | ||
| { | ||
| bpf_printk("allow_port: [l4] size length check hit: continue"); | ||
| return TC_ACT_OK; |
Allowlist-mode BPF program that drops all TCP/UDP packets except those with destination port equal to the input port number. Non-TCP/UDP protocols (ICMP, etc.) pass through unaffected. Co-authored-by: Ona <no-reply@ona.com>
CLI functional: allows specific port, blocks other ports, does not block ICMP. CLI flags: missing input, invalid port. CNI functional: allow_port via JSON config. CNI flags: missing input rejected. 7 new tests (43 total). Co-authored-by: Ona <no-reply@ona.com>
Co-authored-by: Ona <no-reply@ona.com>
…ary checks - Use IHL field for dynamic IP header length instead of fixed sizeof(iphdr) - Validate IHL >= 5 and bounds-check the full IP header - Drop subsequent fragments (no L4 headers to verify) - Fail-closed (TC_ACT_SHOT) on all boundary check failures - Document passthroughs: non-IPv4 and non-TCP/UDP traffic passes through Co-authored-by: Ona <no-reply@ona.com>
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Description
Allowlist-mode BPF program that drops all TCP/UDP packets except those with destination port equal to the input port number. Non-TCP/UDP protocols (ICMP, etc.) pass through unaffected.
This is the inverse of
block_port: instead of blocking one port, it allows only one port and drops all other TCP/UDP traffic. Intended for agent quarantine scenarios where an agent should only communicate on a specific proxy port.Depends on #41 (
allow_ip).Commits
feat(bpf): implement allow_port program— BPF program,api.luaregistration,input_parse.hwiringtest(bpf): add allow_port tests— 7 new tests (43 total)docs: add allow_port to built-in programs— README.txt, docs/README.mdHow to test
xmake clean -a xmake f --generate-vmlinux=y xmake sudo XMAKE_ROOT=y xmake run testAll 43 tests pass (36 from PR #41 + 7 new).