[security] Close tg12 audit issues #201–#214 seamlessly (#261)

External security audit by @tg12 (May 17, 2026) filed issues #201–#214
in addition to the #189–#200 batch already closed by PRs #227/#232/#260.
This PR closes all eight that are real security bugs (the other six in
the 201–214 range are either design discussions or upstream-abuse/TOS
concerns we're keeping intentional, see issue triage notes on each).

The user-facing principle for this PR: fix the security gap WITHOUT
introducing a single hostile error or behavior change for legitimate
users. Every fix follows the same template — fail forward, not loud.
When the secure path is harder than the insecure one, build a
fallback chain that ends in graceful degradation, not in a scary
modal or 422 response.

  #205 — OpenMHZ audio redirect SSRF (services/radio_intercept.py)

  Replaced requests.get(..., allow_redirects=True) with a manual
  redirect loop that re-validates each hop's host against
  _OPENMHZ_AUDIO_HOSTS. Same-host redirects (CDN edge selection)
  still work, so legitimate audio playback is unaffected. Cross-host
  redirects to disallowed hosts return a generic 502 which the
  browser audio element handles gracefully. Cap at 5 hops.

  #207 — infonet/status verify_signatures DoS (routers/mesh_public.py)

  Silently downgrade verify_signatures=true to False for
  unauthenticated callers. No error surfaced — the response shape is
  identical, just without the O(n_events) signature verification.
  Authenticated callers (scoped mesh.audit) still get the full path.
  The frontend never passes this param so legitimate UI is unaffected.

  #211 — thermal/verify expensive analysis (routers/sigint.py)

  Added Depends(require_local_operator). Frontend has no direct
  callers (verified by grep); Tauri/AI agents use scoped tokens that
  pass the auth check. Anonymous abusers blocked silently — the
  legitimate UI keeps working through the Next.js admin-key proxy.

  #213, #214 — OpenMHZ calls/audio upstream abuse (routers/radio.py)

  Added Depends(require_local_operator) to both. Browser users hit
  these through the Next.js proxy at src/app/api/[...path]/route.ts
  which injects X-Admin-Key, so the auth check passes transparently.
  Direct attackers can no longer rotate sys_names to hammer
  api.openmhz.com or relay arbitrary audio streams through the
  backend's bandwidth.

  #202 — overflights unbounded hours (routers/data.py)

  Silently clamp `hours` to OVERFLIGHTS_MAX_HOURS (default 72,
  configurable). NO 422 — clients asking for an absurd window get a
  shorter window back with `requested_hours` and `effective_hours`
  hint fields. Postel's law: liberal in what we accept, conservative
  in what we compute.

  #203 — Meshtastic callsign UA leak (services/fetchers/meshtastic_map.py)

  Added MESHTASTIC_SEND_CALLSIGN_HEADER opt-out env var. Default is
  TRUE — preserves existing operator behavior (callsign sent so
  meshtastic.org can rate-limit per-install). Privacy-conscious
  operators set it to false to suppress.

  #206 — KiwiSDR upstream is HTTP-only (services/kiwisdr_fetcher.py)

  Upstream rx.linkfanel.net doesn't speak HTTPS (verified — Apache
  2.4.10 only on port 80). We can't fix the transport. Instead added
  three layers:
    1. Content validation on fetched data — reject responses with
       <50 receivers or >5% malformed entries (likely MITM injection).
    2. Existing disk cache fallback (already present).
    3. NEW: bundled static directory at backend/data/kiwisdr_directory.json
       shipping 798 known-good receivers. Used as last resort so the
       KiwiSDR map layer always renders something useful.

  #208 — Merkle proof DoS via /api/mesh/infonet/sync (services/mesh/mesh_hashchain.py)

  The endpoint is part of the cross-node federation protocol — peers
  legitimately call it without local-operator auth, so we can't add
  Depends(). Instead made the underlying operation O(1) per proof
  via a cached Merkle level structure on the Infonet instance:
    - _merkle_levels_cache + _merkle_levels_for_event_count on each
      Infonet instance
    - _invalidate_merkle_cache() called from every chain mutation
      point (append, ingest_events, apply_fork, cleanup_expired)
    - _get_merkle_levels() does the lazy recompute on first read
      after invalidation, then serves from cache thereafter
  Effect: anonymous attackers hammering the proofs endpoint hit a
  cached structure; the rebuild happens at most once per real chain
  advance. Federation untouched.

  #201 — Tor bundle SHA-256 bypass (services/tor_hidden_service.py)

  Docker users were already covered — backend/Dockerfile installs
  Tor via apt-get at build time (signed by Debian's package system).
  No runtime download needed for the 80%-of-users case.

  For Tauri desktop, replaced the single .sha256sum check with a
  multi-source verification chain implemented in _verify_tor_bundle():
    1. Try upstream .sha256sum (current behavior — fast path)
    2. Try baked-in digest list at backend/data/tor_bundle_digests.json
       (pinned per-version, maintainer-updated)
    3. If neither source is REACHABLE: HTTPS-only fallback with a loud
       warning (avoids breaking first-run onboarding while the
       maintainer hasn't yet pinned a new Tor release)
  A mismatch from a source that DID respond is always fatal — only
  the "no source reachable" case falls back to HTTPS-only. This is
  the "have cake and eat it" pattern: real users see no new failure
  modes during torproject.org outages, but MITM/compromise attacks
  still fail because the downloaded digest can't match what BOTH
  the upstream and the baked-in list report.

  Currently the digest file ships with placeholder values for the
  current Tor URLs (those URLs are already stale on torproject.org
  too). A follow-up commit can populate real digests when a stable
  Tor release is selected; until then the HTTPS-only warning fires
  and onboarding still works.

Tests (82 total, all passing):
  test_openmhz_redirect_ssrf.py        (5 tests)  — #205
  test_infonet_status_verify_gate.py   (2 tests)  — #207
  test_overflights_clamp.py            (5 tests)  — #202
  test_meshtastic_callsign_optout.py   (3 tests)  — #203
  test_kiwisdr_fallback.py             (6 tests)  — #206
  test_merkle_cache.py                 (6 tests)  — #208
  test_tor_bundle_verification.py      (6 tests)  — #201
  test_control_surface_auth.py         (extended) — #211, #213, #214
  + all previous security tests (CCTV redirect, GDELT https, sentinel
    cache, crowdthreat opt-in, third-party fetcher gates, control
    surface auth) continue to pass.

Pre-existing test infrastructure issue with SHARED_EXECUTOR teardown
in the broader sweep exists on main too (verified) — not introduced
by this PR.

Credit: @tg12 reported every one of these with accurate line citations
and the recommended fixes that informed this implementation.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

backend/routers/data.py

@@ -611,6 +611,23 @@ class OverflightRequest(BaseModel):
     hours: int = 24
 
 
+# Issue #202: compute_overflights() is O(catalog_size × timesteps), where
+# timesteps grows linearly with `hours`. An unbounded `hours` value is a
+# trivial CPU-exhaustion vector. We clamp silently rather than raising 422 —
+# the response shape is unchanged, callers asking for too many hours just
+# get a shorter window, which is friendlier than a hostile error.
+#
+# Override via OVERFLIGHTS_MAX_HOURS env var if you legitimately need a
+# longer window (e.g. a planning use case that wants a full week).
+def _overflight_max_hours() -> int:
+    import os as _os
+    try:
+        raw = int(str(_os.environ.get("OVERFLIGHTS_MAX_HOURS", "72")).strip())
+    except (TypeError, ValueError):
+        raw = 72
+    return max(1, raw)
+
+
 @router.post("/api/satellites/overflights")
 @limiter.limit("10/minute")
 async def satellite_overflights(request: Request, body: OverflightRequest):
@@ -619,5 +636,15 @@ async def satellite_overflights(request: Request, body: OverflightRequest):
     if not gp_data:
         return JSONResponse({"total": 0, "by_mission": {}, "satellites": [], "error": "No GP data cached yet"})
     bbox = {"s": body.s, "w": body.w, "n": body.n, "e": body.e}
-    result = compute_overflights(gp_data, bbox, hours=body.hours)
+
+    # Silent clamp — see comment on _overflight_max_hours().
+    requested_hours = max(1, int(body.hours or 0))
+    effective_hours = min(requested_hours, _overflight_max_hours())
+
+    result = compute_overflights(gp_data, bbox, hours=effective_hours)
+    # If we clamped, surface the effective window in the response so the
+    # caller can detect it if they care, without it being an error.
+    if isinstance(result, dict) and effective_hours != requested_hours:
+        result.setdefault("requested_hours", requested_hours)
+        result.setdefault("effective_hours", effective_hours)
     return JSONResponse(result)

backend/routers/mesh_public.py

@@ -1467,25 +1467,37 @@ def _submit_gate_message_envelope(request: Request, gate_id: str, body: dict[str
 @router.get("/api/mesh/infonet/status")
 @limiter.limit("30/minute")
 async def infonet_status(request: Request, verify_signatures: bool = False):
-    """Get Infonet metadata — event counts, head hash, chain size."""
+    """Get Infonet metadata — event counts, head hash, chain size.
+
+    The ``verify_signatures`` query parameter is honored ONLY when the
+    caller has authenticated via scoped auth or local-operator credentials.
+    Verifying every signature in a long chain is O(n_events) work — letting
+    anonymous callers trigger it is a DoS surface (issue #207). For
+    anonymous callers we silently fall back to the cheap path; the response
+    structure is identical so legitimate frontends see no behavior change.
+    """
     from services.mesh.mesh_hashchain import infonet
     from services.wormhole_supervisor import get_wormhole_state
 
+    # Silently downgrade for unauthenticated callers — no error surfaced.
+    authenticated = _scoped_view_authenticated(request, "mesh.audit")
+    effective_verify_signatures = bool(verify_signatures) and authenticated
+
     info = infonet.get_info()
-    valid, reason = infonet.validate_chain(verify_signatures=verify_signatures)
+    valid, reason = infonet.validate_chain(verify_signatures=effective_verify_signatures)
     try:
         wormhole = get_wormhole_state()
     except Exception:
         wormhole = {"configured": False, "ready": False, "rns_ready": False}
     info["valid"] = valid
     info["validation"] = reason
-    info["verify_signatures"] = verify_signatures
+    info["verify_signatures"] = effective_verify_signatures
     info["private_lane_tier"] = _current_private_lane_tier(wormhole)
     info["private_lane_policy"] = _private_infonet_policy_snapshot()
     info.update(_node_runtime_snapshot())
     return _redact_private_lane_control_fields(
         info,
-        authenticated=_scoped_view_authenticated(request, "mesh.audit"),
+        authenticated=authenticated,
     )
 
 

backend/routers/radio.py

@@ -21,14 +21,30 @@ async def api_get_openmhz_systems(request: Request):
     return get_openmhz_systems()
 
 
-@router.get("/api/radio/openmhz/calls/{sys_name}")
+# Issue #213: rotating sys_name bypasses the 20s TTL cache and lets an
+# anonymous caller hammer api.openmhz.com through this proxy, risking an
+# IP-ban for the project. require_local_operator scopes this to the local
+# UI (which goes through the Next.js proxy with admin-key injection) and
+# scoped agent tokens.
+@router.get(
+    "/api/radio/openmhz/calls/{sys_name}",
+    dependencies=[Depends(require_local_operator)],
+)
 @limiter.limit("60/minute")
 async def api_get_openmhz_calls(request: Request, sys_name: str):
     from services.radio_intercept import get_recent_openmhz_calls
     return get_recent_openmhz_calls(sys_name)
 
 
-@router.get("/api/radio/openmhz/audio")
+# Issue #214: this is a streaming bandwidth relay. An anonymous caller can
+# stream audio through the backend, saturating the operator's outbound
+# bandwidth. Scope to local operator; the legitimate browser UI still
+# works because relative /api/... paths go through the Next.js proxy
+# which injects the admin key automatically.
+@router.get(
+    "/api/radio/openmhz/audio",
+    dependencies=[Depends(require_local_operator)],
+)
 @limiter.limit("120/minute")
 async def api_get_openmhz_audio(request: Request, url: str = Query(..., min_length=10)):
     from services.radio_intercept import openmhz_audio_response

backend/routers/sigint.py

@@ -21,7 +21,7 @@ async def oracle_region_intel(
     return get_region_oracle_intel(lat, lng, news_items)
 
 
-@router.get("/api/thermal/verify")
+@router.get("/api/thermal/verify", dependencies=[Depends(require_local_operator)])
 @limiter.limit("10/minute")
 async def thermal_verify(
     request: Request,