no op version of CRL cache for disabling crl check

atst/app.py

@@ -18,7 +18,7 @@ from atst.routes.task_orders import task_orders_bp
 from atst.routes.dev import bp as dev_routes
 from atst.routes.users import bp as user_routes
 from atst.routes.errors import make_error_pages
-from atst.domain.authnid.crl import CRLCache
+from atst.domain.authnid.crl import CRLCache, NoOpCRLCache
 from atst.domain.auth import apply_authentication
 from atst.domain.authz import Authorization
 from atst.domain.csp import make_csp_provider
@@ -48,6 +48,8 @@ def make_app(config):
     app.config.update({"SESSION_REDIS": app.redis})
 
     make_flask_callbacks(app)
+    # TODO: deprecate the REQUIRE_CRLs setting in favor of the
+    # DISABLE_CRL_CHECK; both have the effect of never loading CRLs
     if app.config.get("REQUIRE_CRLS"):
         make_crl_validator(app)
     register_filters(app)
@@ -133,6 +135,7 @@ def map_config(config):
         "REQUIRE_CRLS": config.getboolean("default", "REQUIRE_CRLS"),
         "RQ_REDIS_URL": config["default"]["REDIS_URI"],
         "RQ_QUEUES": [config["default"]["RQ_QUEUES"]],
+        "DISABLE_CRL_CHECK": config.getboolean("default", "DISABLE_CRL_CHECK"),
     }
 
 
@@ -183,10 +186,15 @@ def make_redis(app, config):
 
 
 def make_crl_validator(app):
-    crl_locations = []
-    for filename in pathlib.Path(app.config["CRL_DIRECTORY"]).glob("*.crl"):
-        crl_locations.append(filename.absolute())
-    app.crl_cache = CRLCache(app.config["CA_CHAIN"], crl_locations, logger=app.logger)
+    if app.config.get("DISABLE_CRL_CHECK"):
+        app.crl_cache = NoOpCRLCache(logger=app.logger)
+    else:
+        crl_locations = []
+        for filename in pathlib.Path(app.config["CRL_DIRECTORY"]).glob("*.crl"):
+            crl_locations.append(filename.absolute())
+        app.crl_cache = CRLCache(
+            app.config["CA_CHAIN"], crl_locations, logger=app.logger
+        )
 
 
 def make_eda_client(app):

atst/domain/authnid/crl/__init__.py

@@ -9,7 +9,42 @@ class CRLRevocationException(Exception):
     pass
 
 
-class CRLCache:
+class CRLInterface:
+    def __init__(self, *args, logger=None, **kwargs):
+        self.logger = logger
+
+    def _log_info(self, message):
+        if self.logger:
+            self.logger.info(message)
+
+    def crl_check(self, cert):
+        raise NotImplementedError()
+
+
+class NoOpCRLCache(CRLInterface):
+    def _get_cn(self, cert):
+        try:
+            parsed = crypto.load_certificate(crypto.FILETYPE_PEM, cert)
+            for comp in parsed.get_subject().get_components():
+                if comp[0] == b"CN":
+                    return comp[1].decode()
+        except crypto.Error:
+            pass
+
+        return "unknown"
+
+    def crl_check(self, cert):
+        cn = self._get_cn(cert)
+        self._log_info(
+            "Did not perform CRL validation for certificate with Common Name '{}'".format(
+                cn
+            )
+        )
+
+        return True
+
+
+class CRLCache(CRLInterface):
 
     _PEM_RE = re.compile(
         b"-----BEGIN CERTIFICATE-----\r?.+?\r?-----END CERTIFICATE-----\r?\n?",
@@ -25,10 +60,6 @@ class CRLCache:
         self._build_crl_cache(crl_locations)
         self.logger = logger
 
-    def log_info(self, message):
-        if self.logger:
-            self.logger.info(message)
-
     def _get_store(self, cert):
         return self._build_store(cert.get_issuer().der())
 
@@ -53,13 +84,13 @@ class CRLCache:
 
     def _build_store(self, issuer):
         store = self.store_class()
-        self.log_info("STORE ID: {}. Building store.".format(id(store)))
+        self._log_info("STORE ID: {}. Building store.".format(id(store)))
         store.set_flags(crypto.X509StoreFlags.CRL_CHECK)
         crl_location = self._get_crl_location(issuer)
         with open(crl_location, "rb") as crl_file:
             crl = crypto.load_crl(crypto.FILETYPE_ASN1, crl_file.read())
             store.add_crl(crl)
-            self.log_info(
+            self._log_info(
                 "STORE ID: {}. Adding CRL with issuer {}".format(
                     id(store), crl.get_issuer()
                 )
@@ -81,7 +112,7 @@ class CRLCache:
     def _add_certificate_chain_to_store(self, store, issuer):
         ca = self.certificate_authorities.get(issuer.der())
         store.add_cert(ca)
-        self.log_info(
+        self._log_info(
             "STORE ID: {}. Adding CA with subject {}".format(
                 id(store), ca.get_subject()
             )