Prototype of default deny modes, refs #2540

datasette/app.py

@@ -296,6 +296,8 @@ class Datasette:
         crossdb=False,
         nolock=False,
         internal=None,
+        private=False,
+        require_auth=False,
     ):
         self._startup_invoked = False
         assert config_dir is None or isinstance(
@@ -340,6 +342,8 @@ class Datasette:
                 raise
         self.crossdb = crossdb
         self.nolock = nolock
+        self.private = private
+        self.require_auth = require_auth
         if memory or crossdb or not self.files:
             self.add_database(
                 Database(self, is_mutable=False, is_memory=True), name="_memory"

datasette/cli.py

@@ -490,6 +490,16 @@ def uninstall(packages, yes):
     type=click.Path(),
     help="Path to a persistent Datasette internal SQLite database",
 )
+@click.option(
+    "--private",
+    is_flag=True,
+    help="Default deny mode - all access blocked unless explicitly allowed",
+)
+@click.option(
+    "--require-auth",
+    is_flag=True,
+    help="Require authentication - only actors with an id can access",
+)
 def serve(
     files,
     immutable,
@@ -522,6 +532,8 @@ def serve(
     ssl_keyfile,
     ssl_certfile,
     internal,
+    private,
+    require_auth,
     return_instance=False,
 ):
     """Serve up specified SQLite database files with a web UI"""
@@ -536,6 +548,8 @@ def serve(
             )
         click.echo(formatter.getvalue())
         sys.exit(0)
+    if private and require_auth:
+        raise click.UsageError("Cannot use both --private and --require-auth")
     if reload:
         import hupper
 
@@ -588,6 +602,8 @@ def serve(
         crossdb=crossdb,
         nolock=nolock,
         internal=internal,
+        private=private,
+        require_auth=require_auth,
     )
 
     # if files is a single directory, use that as config_dir=

datasette/default_permissions.py

@@ -60,9 +60,6 @@ async def permission_resources_sql(datasette, actor, action):
         return rules
 
     # 5. Default allow actions (ONLY if no restrictions)
-    # If actor has restrictions, they've already added their own deny/allow rules
-    has_restrictions = actor and "_r" in actor
-    if not has_restrictions:
     default_allow_actions = {
         "view-instance",
         "view-database",
@@ -71,6 +68,34 @@ async def permission_resources_sql(datasette, actor, action):
         "view-query",
         "execute-sql",
     }
+    # If actor has restrictions, they've already added their own deny/allow rules
+    has_restrictions = actor and "_r" in actor
+    if not has_restrictions:
+        # Check for --private flag (complete default-deny mode)
+        if datasette.private:
+            # In private mode, don't grant any default allow permissions
+            pass
+        # Check for --require-auth flag (authenticated-only mode)
+        elif datasette.require_auth:
+            # Only grant default allow if actor has an id (is authenticated)
+            if actor and actor.get("id"):
+                if action in default_allow_actions:
+                    reason = f"default allow for {action} (authenticated)".replace(
+                        "'", "''"
+                    )
+                    sql = (
+                        "SELECT NULL AS parent, NULL AS child, 1 AS allow, "
+                        f"'{reason}' AS reason"
+                    )
+                    rules.append(
+                        PermissionSQL(
+                            source="default_permissions",
+                            sql=sql,
+                            params={},
+                        )
+                    )
+        else:
+            # Normal mode - grant default allow to everyone
             if action in default_allow_actions:
                 reason = f"default allow for {action}".replace("'", "''")
                 sql = (

tests/test_config_permission_rules.py

@@ -161,3 +161,130 @@ async def test_view_instance_allow_block():
 
     assert await ds.allowed(action="view-instance", actor={"id": "alice"})
     assert not await ds.allowed(action="view-instance", actor={"id": "bob"})
+
+
+@pytest.mark.asyncio
+async def test_private_mode_denies_all_by_default():
+    """Test --private flag blocks all access unless explicitly allowed"""
+    ds = Datasette(memory=True, private=True)
+    ds.add_database(Database(ds, memory_name="test_memory"), name="test")
+    await ds.invoke_startup()
+    await ds.refresh_schemas()
+
+    # Unauthenticated access should be denied for all default actions
+    assert not await ds.allowed(action="view-instance", actor=None)
+    assert not await ds.allowed(
+        action="view-database", resource=DatabaseResource(database="test"), actor=None
+    )
+    assert not await ds.allowed(
+        action="view-table",
+        resource=TableResource(database="test", table="test"),
+        actor=None,
+    )
+
+    # Even authenticated users should be denied in private mode
+    assert not await ds.allowed(action="view-instance", actor={"id": "alice"})
+    assert not await ds.allowed(
+        action="view-database",
+        resource=DatabaseResource(database="test"),
+        actor={"id": "alice"},
+    )
+
+
+@pytest.mark.asyncio
+async def test_private_mode_with_explicit_allow():
+    """Test --private flag allows explicitly configured permissions"""
+    config = {"permissions": {"view-instance": {"id": "alice"}}}
+    ds = Datasette(memory=True, private=True, config=config)
+    ds.add_database(Database(ds, memory_name="test_memory"), name="test")
+    await ds.invoke_startup()
+    await ds.refresh_schemas()
+
+    # Alice should be allowed due to explicit config
+    assert await ds.allowed(action="view-instance", actor={"id": "alice"})
+
+    # Bob should still be denied
+    assert not await ds.allowed(action="view-instance", actor={"id": "bob"})
+
+    # Unauthenticated should be denied
+    assert not await ds.allowed(action="view-instance", actor=None)
+
+
+@pytest.mark.asyncio
+async def test_require_auth_mode_allows_authenticated():
+    """Test --require-auth flag allows actors with id"""
+    ds = Datasette(memory=True, require_auth=True)
+    ds.add_database(Database(ds, memory_name="test_memory"), name="test")
+    await ds.invoke_startup()
+    await ds.refresh_schemas()
+
+    # Authenticated users should be allowed
+    assert await ds.allowed(action="view-instance", actor={"id": "alice"})
+    assert await ds.allowed(
+        action="view-database",
+        resource=DatabaseResource(database="test"),
+        actor={"id": "bob"},
+    )
+    assert await ds.allowed(
+        action="view-table",
+        resource=TableResource(database="test", table="test"),
+        actor={"id": "charlie"},
+    )
+
+    # Unauthenticated access should be denied
+    assert not await ds.allowed(action="view-instance", actor=None)
+    assert not await ds.allowed(
+        action="view-database", resource=DatabaseResource(database="test"), actor=None
+    )
+
+    # Actor without id should be denied
+    assert not await ds.allowed(action="view-instance", actor={"name": "anonymous"})
+
+
+@pytest.mark.asyncio
+async def test_require_auth_mode_with_restrictions():
+    """Test --require-auth mode works with actor restrictions"""
+    # Test with actor that has restrictions
+    ds = Datasette(memory=True, require_auth=True)
+    ds.add_database(Database(ds, memory_name="test_memory"), name="test")
+    await ds.invoke_startup()
+    await ds.refresh_schemas()
+
+    # Actor with restrictions should have those restrictions applied
+    restricted_actor = {"id": "alice", "_r": {"a": ["view-table"]}}
+    # This actor has restrictions, so default allow won't apply
+    # Instead their restrictions define what they can do
+    assert await ds.allowed(
+        action="view-table",
+        resource=TableResource(database="test", table="test"),
+        actor=restricted_actor,
+    )
+
+    # Regular authenticated actor without restrictions should get default allow
+    normal_actor = {"id": "bob"}
+    assert await ds.allowed(
+        action="view-database",
+        resource=DatabaseResource(database="test"),
+        actor=normal_actor,
+    )
+
+
+@pytest.mark.asyncio
+async def test_normal_mode_allows_all():
+    """Test default behavior without --private or --require-auth"""
+    ds = Datasette(memory=True, private=False, require_auth=False)
+    ds.add_database(Database(ds, memory_name="test_memory"), name="test")
+    await ds.invoke_startup()
+    await ds.refresh_schemas()
+
+    # Everyone should be allowed in normal mode
+    assert await ds.allowed(action="view-instance", actor=None)
+    assert await ds.allowed(
+        action="view-database", resource=DatabaseResource(database="test"), actor=None
+    )
+    assert await ds.allowed(action="view-instance", actor={"id": "alice"})
+    assert await ds.allowed(
+        action="view-database",
+        resource=DatabaseResource(database="test"),
+        actor={"id": "bob"},
+    )