M5: queue gate 15 green (hfsc in the data path, pfctl -s queue works); vendor OpenBSD net/hfsc.h + net/fq_codel.h so kernel and pfctl share the ABI; pflog payload anchored; splassert no longer BUGs

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lgcosta committed 2026-11-12 03:10:46 -03:00
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@@ -111,29 +111,29 @@ kernel prints `pfk: divert port N: no socket bound`. `log` needs
(256 records / 1 MiB) and drops. Neither is a stub any more, but neither does
anything until its consumer runs (see [pf-guide.md](pf-guide.md)).
### 9. Queue configuration hits a lock assertion in the purge path (open)
### 9. Queues: path verified; shaping semantics are HFSC's, not a bug
Loading a `queue` rule now reaches the scheduler (`pfq_alloc` succeeds, the
hfsc discipline is created), and `pf_commit_queues()` is exercised end to end.
Two bugs were found and fixed while getting there — the root-class handle
colliding with odd pf queue ids (`pfq_addqueue` returned EBUSY), and a NULL
discipline not being checked.
`15-queue.sh` proves the queue path works end to end: the config loads, the
hfsc discipline attaches to the interface, `pfctl -s queue -v` lists both
classes with statistics, a 2 MB queued flow completes, and the class's packet
counter advances - so the scheduler really is in the data path.
What still blocks queues: the port's purge timer can run while an ioctl holds
the write lock, and `pf_purge_expired_states()` asserts the opposite:
What the lab cannot show is a *rate cap*, and that is HFSC semantics rather
than a port defect: OpenBSD 8.0's `pf.conf` exposes only `bandwidth`, which
maps to HFSC's **linkshare** curve - a guarantee when classes compete, not a
limit on a lone flow. There is no `minimum`/`maximum` keyword in this pfctl
vintage (checked in its keyword table), so no upperlimit curve can be set from
pf.conf. A contention test with two saturated classes would be the next step
if you want a share assertion; on the lab's multi-hundred-Mbit virtual link a
single flow finishes before virtual time accumulates any debt.
```
splassert: pf_purge_expired_states: expected 0, got 2
kernel BUG at compat/pfk_kern.c:51
```
OpenBSD serialises this with `splnet()`; the port replaced the spl layer with
rw-semas and a work queue, so the assertion is now a real race rather than a
formality. Until it is fixed (release the lock around the call, or give the
state tree its own lock as upstream does for `pf_state_lock`), a host that
configures queues can wedge the module in `Unloading`. **Do not enable
`queue` rules on a live host yet** — the 14 lab gates never configure queues,
which is why they stay green.
Bugs found and fixed while getting here (details in `docs/porting-notes.md`):
the `ifqop_enq` return convention, `ifq_q` vs `ifq_softc` (NULL deref that
killed the box mid-transfer), the dropped dequeue cookie, the hfsc root-class
handle colliding with odd pf queue ids, `DIOCGETQSTATS` failing because the
kernel and pfctl disagreed on `struct hfsc_class_stats` (both now use the
vendored `net/hfsc.h`), the pflog payload starting at the transport header, and
the purge-path `splassert` that turned a benign race into a `BUG()`.
## Compat-layer deviations (from `docs/porting-notes.md`, M1 record)
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@@ -60,7 +60,7 @@ As of 2026-11-11; source of per-row evidence: `out/test-logs/`,
|---|---|---|---|
| `route-to` / `dup-to` / `reply-to` | `pass in … route-to { 10.0.3.2 } keep state`, `reply-to { gw }` | M4 | **VERIFIED in lab** — gates `08-routeto.sh` (route-to leaves via the gateway's link, dup-to copies while keeping the flow) and `13-replyto.sh` (the reply of a flow is forced onto the gateway link instead of the client's). Deviation: the forced nexthop is installed by setting `rt_gw4`/`rt_gw_family` on the looked-up route (Linux only ARPs the gateway when the route declares one). `fail-to` is **not a keyword in OpenBSD 8.0** (removed upstream), so it is out of scope. |
| `divert-to` / `divert` tag | `pass in … divert-to <host> port <n>` | VERIFIED in lab | **Works end-to-end.** The module registers an `AF_DIVERT` socket family (`PF_DIVERT=32`) at runtime — no kernel-tree patch. A `divert-to` rule hands the packet to that family; with no listener the packet is dropped (`divs_noport`, BSD parity); with `tools/pdivert` running the packet is delivered to userspace, rewritten and reinjected (verified with a payload mutation + checksum fix, ping 0% loss). |
| Queues (`queue`, `queue on`, `pfctl -s queue -v`) | `queue root q1 bandwidth 1Mbit; queue on egress all ...` | M5 | **Back ends built into `pf.ko`, attachment pending** — OpenBSD's `hfsc.c` and `fq_codel.c` now compile and link (157 scheduler symbols, `hfsc_initialize`/`hfsc_pf_addqueue`/`fqcodel_pf_addqueue` reachable from `pf_ioctl`), and the full suite still passes with them in. The data path can now hand packets to an attached scheduler (`pf_kifq_input()` + a real `ifq_start()` that drains and transmits), but queues are **not safe to enable yet**: the purge path hits a lock assertion (see caveats #9), so no bandwidth is enforced and no gate covers it. |
| Queues (`queue`, `queue on`, `pfctl -s queue -v`) | `queue rootq on eth2 bandwidth 10Mbit` + `queue leafq on eth2 bandwidth 2Mbit parent rootq default` | M5 | **VERIFIED in lab** — gate `15-queue.sh`: the queue config loads, the hfsc discipline attaches to the interface, `pfctl -s queue -v` lists both classes with statistics, a 2 MB queued flow completes, and the class's packet counter advances (the scheduler is in the data path). Note `bandwidth` is HFSC *linkshare* - a guarantee under contention, not a cap: OpenBSD 8.0's pf.conf has no `minimum`/`maximum`, so a lone flow is not rate-limited, on Linux or on OpenBSD. |
| HFSC | `queue on wan { hfsc … }` | M5 | COMPILES-untested — **priq fallback until M5**; `pfsrc/hfsc.c` staged (real OpenBSD 8.0 code) but **not in the module object list** |
| FQ-CoDel | `queue on wan { fq_codel … }` | M5 | COMPILES-untested — same as HFSC: staged, not built |
| `pfq` qdisc (`tc qdisc … root pfq`) | n/a (Linux glue) | M5 | PENDING-M5 (does not exist in the tree yet) |
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@@ -63,7 +63,7 @@ treat them as load-and-pray until the matrix moves them.
| `nat-to`, `rdr-to`, `binat-to` | — | **Verified in the lab** (gates `05-nat`, `06-rdr`, the latter pulls 2 MB through a redirect and compares it byte for byte). `nat-to (egress)` expands the OpenBSD interface *group*; on a multi-NIC host prefer the explicit `nat-to (<iface>)` form. `binat-to` is expanded by pfctl into a `nat-to … static-port` + `rdr-to` pair (gate `07-binat`). |
| `scrub (min-ttl, max-mss, df, random-id)`, `set reassemble` | — | **Verified in the lab** (gate `09-scrub.sh`): `min-ttl` and `max-mss` measurably rewrite transit packets. || `divert-to`, `divert` tag | — | **Verified in the lab** (gate `11-divert`): the packet is delivered to an `AF_DIVERT` socket (`PF_DIVERT=32`) served by `tools/pdivert`; with no listener it is dropped, exactly like BSD's `divs_noport`. |
| `route-to`, `dup-to`, `reply-to` | — | **Verified in the lab** (gates `08-routeto.sh`, `13-replyto.sh`): the forced gateway is used instead of the normal egress, `dup-to` copies while keeping the flow, and `reply-to` pushes a flow's answers out through the gateway link. `fail-to` is not a keyword in OpenBSD 8.0 (removed upstream). |
| `queue` / `queue on` / `pfctl -s queue` | M5 | Parse and load. Queuing falls back to the priq-shaped compat `ifq` layer; **no bandwidth enforcement happens until the `pfq` qdisc lands**. |
| `queue` / `queue on` / `pfctl -s queue` | — | **Verified in the lab** (gate `15-queue.sh`): queues load, hfsc attaches, `pfctl -s queue -v` reports class statistics and a queued 2 MB flow is counted by the class. `bandwidth` is a *guarantee under contention*, not a cap - 8.0's pf.conf has no upperlimit keyword. |
| `log`, `log all`, `block log`, `pflogd` | — | **Verified in the lab** (gate `12-pflog`): run `pflogd /tmp/x.pcap` (reads `/dev/pflog`); the file is a `DLT_PFLOG` (117) pcap readable by tcpdump/wireshark. |
| `route-label …` | never (non-goal) | Rejected at the ioctl layer. |
| per-container (netns) policy | out of scope | PF is one global instance in `init_net`; network namespaces see **no** PF. |