Harden SSH Admission And Credential Input

docs/agent/current-state.md

@@ -2,6 +2,17 @@
 
 Working memory, not an implementation timeline. Source is authoritative; begin with [code map](code-map.md), then [architecture](architecture.md) and [decisions](design-decisions.md).
 
+## Phase 9B — SSH admission / credential handling — 2026-09-15
+
+- User requested continued Phase 9 work and will validate **the phase as a whole**. Do not pause between slices for target approval; all target gates remain unrun and collected in `docs/security_hardening.md`. Secure boot/encrypted NVS remain excluded; Phase 8 sign-off stays closed. Initial Git status for this slice was clean.
+- `ssh_auth_policy.{c,h}`: 72-byte owner-only boot-lifetime state, independent handshake and password/signed-key buckets (capacity6, refill1/10s), unsigned-probe bucket(capacity12, refill1/5s). No waits, allocations, per-peer maps or NVS writes. Reconnect, stop/start/rotation/counter clear do not replenish; no refunds, idle saturation/no excess credit, clock regression fails closed. Global starvation is a deliberate documented tradeoff; natural refill only after hostile traffic subsides, not fairness/zeroCPU protection.
+- `ssh_transport` gates handshake before wolfSSH allocation and credentials before database/ordinary signature work; keeps existing per-slot three-counted-attempt closure and 15s deadline. Explicit pending-result marker fences duplicate/unexpected completion. wolfSSH1.4.20 and certificates/none-disabled guard; keyboard prompt rejection callback/context prevents unregistered callback dispatch while keeping password/publickey advertisement. New aggregate admission/probe/throttle/limit/backend/method counters via `ssh counters`; `add_counter` saturates (do not generalize to unrelated direct lifecycle increments).
+- Admin RX consumed spans / TX positively accepted spans are securely wiped; pending retry and serial hot-path bytes unchanged. Whole retired slot securely wiped before generation/fd restoration. `console_input` and shared remote hidden prompts reject overflow/unsupported bytes on submit, sticky across editing; visible CLI behavior preserved; existing callers prevent prefix persistence. Input errors wipe output and return zero length.
+- Source audit verified actual pinned wolfSSH auth callback order and `SendChannelData` positive copied/consumed behavior. Tests pin `internal.c` SHA256 and execute extracted vendor parser/send functions with crypto/IO doubles plus actual compiler-feature preprocessing. Followup resolved reviewer concern about keyboard error-path one-byte write: inline buffer initialized, framed packets retain padding reserve, exact-sized protocol-identification pending state cannot reach auth, rejection purges without advancing length. This is a narrow invariant audit, not library security certification.
+- Validation: parent `pio run` PASS **94,340 B linked RAM / 1,829,925 B flash** (+144RAM/+1,360flash vs9A; not runtime reserve). Parent and independent review PASS all four new suites `ssh_auth_policy`, `ssh_auth_transport`, `wolfssh_auth_contract` (35 vendor cases+resolved feature profile), `hidden_input`; token policy UB-sanitizer trap mode passed, standard UBSan runtime absent. Related 11 command suite PASS: SSH management/security/runtime, console boundary/accounts/lifecycle, admin SSH policy, web cookie SSH/accounts, web admin transport+tickets, security build policy18. `git diff --check` PASS. No blocking review findings; no upload/erase/device operations/deps/generated assets/commit.
+- **Next:** complete remaining secret-lifetime and protocol review; inspect pinned library private-key/password-packet/buffer-growth/destruction before claiming comprehensive zeroization. Focused application audit found and fixed admin staging retention and hidden-input truncation; other checked key/candidate handoffs already wipe. TLS/SSH algorithm/certificate/header/password/KDF policy and web receive-before-throttle/challenge fairness remain review items. Dependency advisory/license review and lifecycle runbooks still planned, not performed. No need to await 9B hardware sign-off to continue.
+- Final target checklist includes real SSH clients offering several keys, bad signatures/passwords, keyboard decline, each pool/refill/restart-clear persistence, established mixed transport/USB/UART0 responsiveness and reserve measurements, hidden-input errors/CRLF timing and crash recovery. UART0 paired/delayed LF relies on next-prompt flush; host UART fake does not model timing. No real-crypto/live packet-network or target claims from extracted-function tests.
+
 ## Phase 9A — crash/debug baseline — 2026-09-15
 
 - User requested Phase 9 and explicitly excluded secure boot and encrypted NVS. Roadmap now marks Phase 9 in progress; Phase 8 acceptance remains closed. Physical extraction/firmware replacement stay outside the threat model even after hardening; no encryption/eFuse/partition changes.
@@ -9,7 +20,7 @@ Working memory, not an implementation timeline. Source is authoritative; begin w
 - `docs/security_hardening.md` defines shared operational profiles, secret-bearing artifact handling, evidence limits and target gates. Reserved partitions unchanged; old dump/credential copies are not erased. No generated assets/dependency changes.
 - Validation: `pio run` PASS **94,196 B linked RAM / 1,828,565 B flash**. Host policy matrix PASS17; actual generated SDK header PASS as eighteenth case. Initial host test hit read-only ccache storage; `CCACHE_DISABLE=1` rerun passed. Independent review found no actionable issues and repeated both host modes and diff check. No upload, erase, hardware validation or commit.
 - **9A target gate remains open:** synthetic-secret controlled panic, no register/UART/flash dump, reboot rather than halt, UART0/USB/network recovery and broker behavior. No test-only panic command was added to production.
-- **Next implementation: SSH cross-connection authentication throttling.** Read-only audit verified three counted attempts per slot reset on reconnect, with unsigned key probes uncounted; web already gates five verifications per fixed global 60-second window. Choose bounded monotonic admission and explicit counters without sleeping the SSH owner, preserve currentness/slot ownership and test real wolfSSH callback ordering. No auth behavior changed in 9A. Remaining zeroization/crypto/dependency/license/lifecycle audits are planned, not completed.
+- 9A changed no authentication behavior; its planned SSH follow-up is now implemented in 9B above. Whole-phase target validation remains deferred.
 
 ## Web popup cosmetics — 2026-09-14