docs: rdr-to verified; porting notes on checksum strategy across translation paths (GSO regression)

docs/en/feature-matrix.md

@@ -49,8 +49,8 @@ As of 2026-11-11; source of per-row evidence: `out/test-logs/`,
 | Feature | Upstream syntax | Milestone | Status |
 |---|---|---|---|
 | `nat-to` (port pools, sticky-port, static-port) | `pass out … nat-to (eth1:0)` | M3 | **VERIFIED in lab** — source NAT works end to end: the packet leaves with the pool address (tcpdump proof), the reply is de-NATed and re-routed to the client, and the state shows both tuples (`10.0.2.1:59335 (10.0.1.10:4380) -> 10.0.2.20:8`). Gate: `tests/vm/05-nat.sh`. |
-| `rdr-to` | `rdr pass on wan proto tcp from any to any port 8080 -> srv port 80` | M3 | PENDING-M3 |
+| `rdr-to` | `pass in … to <fw> port 8080 rdr-to <srv> port 80 keep state` | M3 | **VERIFIED in lab** — port redirect works end to end (gate `06-rdr.sh`): the client talks to the firewall's address, pf rewrites the destination, re-routes the packet, and the reply is un-redirected. The gate also pulls 2 MB through the redirect and checks byte-for-byte integrity (GSO/TSO regression guard). |
-| `binat-to` | `binat-to …` | M3 | PENDING-M3 |
+| `binat-to` | `binat-to <net>` (no direction) | M3 | PENDING-M3 — parser accepts the 8.0 form (`binat-to` is a rule option, not a standalone rule); VM gate not written yet. |
 | Scrub/normalize: reassembly, `fragment drop-overlap`, `min-ttl`, `max-mss`, `df`/`no-df`, `random-id`, `set reassemble yes` | `match on all scrub (max-mss 1380 …)` | M3 | COMPILES-untested (`pf_norm.c` compiled into pf.ko and reached from `pf_test`; scapy gate 08 pending) |
 | OS fingerprinting in states | `pass … set os A` + `/etc/pf.os` | bonus | COMPILES-untested (`pf_osfp.c` compiled; no fingerprint packaging yet — missing `/etc/pf.os` is tolerated) |
 

docs/porting-notes.md

@@ -904,3 +904,20 @@ demonstrates the BSD "receive -> rewrite -> reinject" cycle.
 
 Without step 3 the reply is delivered to the firewall's own stack and the
 client never sees it (the classic "NAT works one way" symptom).
+
+## Checksums across the translation paths
+
+pf rewrites addresses, so both the IPv4 header checksum and the transport
+checksum must stay correct.  Three cases matter in the lab:
+
+| Case | What Linux gives us | What the port does |
+|---|---|---|
+| transit packet, no translation | `CHECKSUM_UNNECESSARY` (vhost-net did not materialize the field) | leave it alone — the peer's stack trusts the marker |
+| translated packet, plain skb | same | recompute the transport checksum in software over the new pseudo-header, then the IP header checksum |
+| translated packet, GSO/TSO skb (bulk, locally generated) | `CHECKSUM_PARTIAL` | **do not** compute in software: one computation covers only the first segment. Restore `CHECKSUM_PARTIAL` with `csum_start`/`csum_offset` and let the NIC compute per segment |
+
+The third row is a regression guard: materializing GSO checksums in software
+made bulk transfers silently stall (the peer dropped every segment after the
+first) and starved `sshd` on the firewall — the box answered ping but not SSH.
+`tests/vm/06-rdr.sh` pulls 2 MB through a redirect and compares the size to
+catch it.

docs/pt-BR/feature-matrix.md

@@ -49,8 +49,8 @@ Estado em 2026-11-11; evidência por linha: `out/test-logs/`,
 | Feature | Sintaxe de upstream | Milestone | Status |
 |---|---|---|---|
 | `nat-to` (pools de portas, sticky-port, static-port) | `pass out … nat-to (eth1:0)` | M3 | **VERIFICADO em lab** — NAT de origem funciona ponta a ponta: o pacote sai com o endereço do pool (prova via tcpdump), a resposta é des-NATeada e roteada de novo para o cliente, e o estado mostra as duas tuplas (`10.0.2.1:59335 (10.0.1.10:4380) -> 10.0.2.20:8`). Gate: `tests/vm/05-nat.sh`. |
-| `rdr-to` | `rdr pass on wan proto tcp from any to any port 8080 -> srv port 80` | M3 | PENDING-M3 |
+| `rdr-to` | `pass in … to <fw> port 8080 rdr-to <srv> port 80 keep state` | M3 | **VERIFICADO em lab** — o redirect de portas funciona ponta a ponta (gate `06-rdr.sh`): o cliente fala com o endereço do firewall, o pf reescreve o destino, re-rotea o pacote e a resposta é des-redirectuada. O gate também baixa 2 MB pelo redirect e confere a integridade byte a byte (guarda de regressão GSO/TSO). |
-| `binat-to` | `binat-to …` | M3 | PENDING-M3 |
+| `binat-to` | `binat-to <rede>` (sem direção) | M3 | PENDING-M3 — o parser aceita a forma 8.0 (`binat-to` é opção de regra, não regra própria); gate em VM ainda não escrito. |
 | Scrub/normalize: remontagem, `fragment drop-overlap`, `min-ttl`, `max-mss`, `df`/`no-df`, `random-id`, `set reassemble yes` | `match on all scrub (max-mss 1380 …)` | M3 | COMPILES-untested (`pf_norm.c` compilado no pf.ko e alcançado pelo `pf_test`; gate scapy 08 pendente) |
 | Fingerprint de SO em estados | `pass … set os A` + `/etc/pf.os` | bônus | COMPILES-untested (`pf_osfp.c` compilado; sem empacotamento de fingerprints ainda — ausência de `/etc/pf.os` é tolerada) |