Allow verified mod overlay assets through title release gates

tools/package_title_release.py

@@ -831,9 +831,33 @@ def check_diagnostics(ctx, stage):
     log('Playtest Diagnostics default %s (%s)' % ('on' if want else 'off', ctx.channel))
 
 
+def declared_overlay_assets(stage):
+    """Hash-bound mod patches are payloads, not standalone disc/BIOS images."""
+    allowed = set()
+    for manifest in sorted((Path(stage) / 'mods/bundled').glob('*/*/manifest.toml')):
+        for overlay in tomllib.loads(read_text(manifest)).get('overlay', []):
+            rel = PurePosixPath(overlay.get('file', ''))
+            if (rel.is_absolute() or '..' in rel.parts or not rel.parts or
+                    rel.parts[0] != 'assets' or rel.suffix.lower() != '.bin' or
+                    overlay.get('target') != 'disc_user'):
+                continue
+            digest = overlay.get('sha256', '')
+            expected = overlay.get('expected_sha256', '')
+            if not all(re.fullmatch(r'[0-9a-fA-F]{64}', h) for h in (digest, expected)):
+                continue
+            asset = manifest.parent.joinpath(*rel.parts).resolve()
+            if not asset.is_relative_to(manifest.parent.resolve()) or not asset.is_file():
+                fail('declared overlay asset missing or outside package: %s' % rel)
+            if sha256(asset).lower() != digest.lower():
+                fail('declared overlay asset hash mismatch: %s' % rel)
+            allowed.add(asset)
+    return allowed
+
+
 def payload_gates(stage, plat, exe_name):
     """Content that must never ship, whatever the title config says."""
     stage = Path(stage)
+    overlay_assets = declared_overlay_assets(stage)
     present = [name for name in BUILD_KIT if (stage / name).exists()]
     if present:
         fail('package contains build-kit/user content: %s' % ', '.join(present))
@@ -850,7 +874,8 @@ def payload_gates(stage, plat, exe_name):
         suffix = path.suffix.lower()
         if suffix in DISC_SUFFIXES:
             fail('disc/save data in package: %s' % rel)
-        if suffix in ('.bin', '.rom') and lower != 'bios/openbios.bin':
+        if (suffix in ('.bin', '.rom') and lower != 'bios/openbios.bin' and
+                path.resolve() not in overlay_assets):
             fail('binary image in package (only bios/openbios.bin may ship): %s' % rel)
         if re.match(r'scph.*\.(bin|rom)', leaf):
             fail('retail BIOS image in package: %s' % rel)

tools/tests/test_package_title_release.py

@@ -235,6 +235,23 @@ def test_toolchain_sources_are_allowed(self):
         (self.stage / 'overlay_toolchain/tcc/examples/fib.c').write_text('int x;')
         ptr.payload_gates(self.stage, 'windows', 'Fixture.exe')
 
+    def test_hash_bound_disc_overlay_asset(self):
+        package = self.stage / 'mods/bundled/fixture.patch/1.0.0'
+        (package / 'assets').mkdir(parents=True)
+        asset = package / 'assets/warning.bin'
+        asset.write_bytes(b'authored patch fixture')
+        (package / 'manifest.toml').write_text(
+            '[[overlay]]\ntarget="disc_user"\noffset=16\n'
+            'file="assets/warning.bin"\nsha256="%s"\nexpected_sha256="%s"\n'
+            % (hashlib.sha256(asset.read_bytes()).hexdigest(), '0' * 64))
+        ptr.payload_gates(self.stage, 'windows', 'Fixture.exe')
+        asset.write_bytes(b'tampered')
+        with self.assertRaisesRegex(ptr.PackagingError, 'hash mismatch'):
+            ptr.payload_gates(self.stage, 'windows', 'Fixture.exe')
+
+    def test_undeclared_mod_binary_is_refused(self):
+        self.assert_refused('mods/bundled/fixture/1.0.0/assets/disc.bin', message='image')
+
     def test_openbios_required(self):
         (self.stage / 'bios/openbios.bin').write_bytes(b'short')
         with self.assertRaisesRegex(ptr.PackagingError, 'OpenBIOS'):