Harden wolfSSL and wolfSSH validation

Enable validated ECC imports and X25519 all-zero rejection through
PUBLIC build policy. Tighten wolfSSH parser bounds, overflow handling,
and signature framing with guard-page and crypto vector contracts.

docs/wolf_security_review.md

@@ -4,13 +4,25 @@
 
 **Xtensa small-math mitigation implemented; the broader review and security sign-off remain open.** Root `CMakeLists.txt` defines `CURVE25519_SMALL` and `ED25519_SMALL` before component parsing. `cmake/wolf_crypto_policy.cmake` propagates a forced-include resolved-settings guard PUBLIC from wolfSSL to consumers, including wolfSSH/application code. `cmake/wolf_crypto_policy.h` requires both enabled small implementations, rejects `WOLFSSL_CURVE25519_BLINDING`, and rejects enabling Curve448/Ed448 without review. This follows PR 9275's small-math policy for the enabled Xtensa algorithms, with consistent library/consumer production flags and ABI-sensitive layouts. **Blinding is not enabled with small X25519**: wolfSSL 5.8.2 excludes/rejects this combination; do not force it back on or present the historical blinding observation below as current policy.
 
-The CVE-2025-12888 configuration mitigation is no longer merely proposed. Supplied parent evidence: `pio run` **PASS**, **94,340 B linked RAM / 1,767,217 B flash**, **−64,092 B flash** from 9C with unchanged linked RAM; all four [focused mitigation commands](security_hardening.md#mitigation-hostbuild-evidence--2026-09-15) passed. Independent reviewer reports SDK-override and wolf-crypto-policy tests passed with no blocking implementation defects. These are supplied host/build results, not reruns by this documentation update, device timing measurements, real SSH interoperability/rekey evidence or runtime-headroom evidence.
+**Parser corrections implemented:** `tools/security_overrides.py` extends the existing hash-pinned wolfSSH generated source (still seven overridden files overall). The PR892 subset bounds `DoIgnore`/`GetSkip` and service-string reads, accepts boundary-empty skips, rejects zero-capacity `GetString`, and preserves the old strict service-name length limit. The PR881 subset rejects channel-window addition overflow without changing the window. The PR880 subset changes both ECC/Ed25519 key/signature label comparisons to short-circuit OR. Local framing corrections bound ECC r/s reads to the declared sub-blob and require exact inner/outer consumption; Ed25519 also requires exact outer consumption. Valid framing and crypto/digest/message construction remain unchanged; formerly tolerated malformed labels/trailing bytes reject. Existing password bounds/wiping and async-pending retention remain intact. See the [parser contract and deferred scope](../tests/wolfssh_parser_contract/README.md); these are subsets, not complete PR backports. PR899 has no applied hunks; service semantics, other parsers and standalone ECC key-blob semantics remain open.
 
-**Still pending:** coherent wolfSSH message-order review/correction (CVE-2025-14942), IGNORE/service and other parser review, ECC import/ECDH/raw-signature validation review, remaining advisory applicability, and whole-phase target validation. No dependency upgrades were made; newer release pairs below remain unvalidated candidates. License/source/notice packaging remains unresolved in the [license inventory](dependency_licenses.md). Phase 9 is not complete or production-ready.
+**Crypto validation implemented:** PUBLIC `WOLFSSL_VALIDATE_ECC_IMPORT` and `WOLFSSL_ECDHX_SHARED_NOT_ZERO` enable existing upstream P-256 import validation and X25519 all-zero-result rejection. The guard rejects missing checks and reviewed validator-disabling/hardware-stub configurations. Strict production checks confirm the effective flags without candidate injection. The [key-validation review](ssh_key_validation_review.md) traces the previously missing unauthenticated P-256 KEX point check and low-order X25519 inputs that pass the old precheck. Current raw SSH signature callers supply locally derived full digests; no current short-digest/OID-confusion trigger was found. This does not backport generic PR10131 API hardening or demonstrate an exploit. Import validation adds CPU/allocation cost requiring target measurement.
+
+Supplied parent evidence: `pio run` **PASS**, **94,340 B linked RAM / 1,768,949 B flash**, unchanged RAM / **+1,732 B flash** versus the preceding 1,767,217 B mitigation build. All five [focused commands](security_hardening.md#mitigation-hostbuild-evidence--2026-09-15) passed: strict crypto policy, parser contract (3,124 cases in each of two stack modes plus six rejected guard-removal mutations), auth contract (135 cases), SSH protocol policy, and SDK overrides with actual build-directory registration. Independent review found no blocker in the scoped changes. Parser tests use crypto doubles; crypto tests execute real vendor arithmetic and independently check exact generated-source deltas. Neither establishes an end-to-end SSH exchange. These are supplied results, not build/test reruns by this documentation update or runtime-headroom evidence.
+
+**Still pending:** coherent wolfSSH ordering correction (CVE-2025-14942), deferred parser/API/advisory review, whole-phase target validation and [license/source packaging](dependency_licenses.md). No dependency upgrade or device operation was performed. Phase 9 is not complete or production-ready.
+
+### Ordering blocker and actionable next strategy
+
+The supplied follow-up reports an attempted coherent PR793/819/840/855/921 backport in temporary work only; **no ordering changes were retained**. Manual patch prerequisites remained unresolved, as did nonblocking `SendNewKeys` returning `WS_WANT_WRITE` and skipping the `SendExtInfo` continuation, and `extInfoSent` semantics across rekey. Parser/crypto passes do not close these state-machine issues.
+
+Official registry queries for wolfSSH **1.5.0** and wolfSSL **5.9.2** returned **404 on 2026-09-15**. Upstream tags exist at wolfSSH commit `8643d7be841184f766374e3b0ed68ced6391543c` and wolfSSL commit `ac01707f552c611fbd135cc723b2682b3e7f80f2`; tag existence is not managed-component availability or ESP compatibility. This is supplied query evidence, not a fresh network check by this documentation update.
+
+Next, evaluate those immutable upstream snapshots in an isolated compatibility branch/worktree with an explicit reviewed packaging/provenance plan, rather than assume a registry version bump works. Alternatively, inventory and review every prerequisite of a coherent source/header backport before applying it. In either approach, first add state-machine regression coverage for partial sends/`WS_WANT_WRITE`, exactly-once EXT_INFO continuation, initial KEX versus rekey and `extInfoSent` lifetime, unexpected/pre-auth messages and valid client flows. Rebase source overrides and version/callback contracts explicitly; preserve password wiping and parser/crypto checks, then rerun focused suites and the firmware build. Only after review and whole-phase target interoperability/resource tests may ordering closure be claimed.
 
 ## Historical pre-mitigation research baseline — 2026-09-15
 
-**The remainder retains the original research evidence. “Current” macros, generated hashes and “not applied/tested” statements below refer to the earlier non-small snapshot; the addendum supersedes those implementation-status claims only. The pending ordering/parser/ECC findings are not closed.**
+**The remainder retains the original pre-mitigation research evidence. “Current” macros, generated hashes, priorities and “not applied/tested” statements below describe that historical snapshot, not today's implementation. The addendum and linked key-validation review supersede the scoped small-math, parser and ECC/X25519 status claims. Ordering and explicitly deferred findings remain open.**
 
 Review date: **2026-09-15**. Read-only external research and local applicability inspection; stopped at the user's requested handoff. **Not a completed security review or release clearance.** Only this new report was written. No dependencies, sources, generated inputs, or parent documents were changed; no build, hardware test, network exploit, or public PoC was executed.