Prevent Soledad server from creating or deleting couch databases (#3502).

4 files changed, 55 insertions, 25 deletions

diff --git a/common/changes/feature_5302_prevent-couch-server-state-from-creating-or-deleting-dbs b/common/changes/feature_5302_prevent-couch-server-state-from-creating-or-deleting-dbs
new file mode 100644
index 00000000..acd74529
--- /dev/null
+++ b/common/changes/feature_5302_prevent-couch-server-state-from-creating-or-deleting-dbs
@@ -0,0 +1,3 @@
+  o Prevent CouchServerState from creating or deleting databases. This way,
+    Soledad remote clients won't ever be able to do these operations when
+    syncing. Part of #5302.
diff --git a/common/src/leap/soledad/common/couch.py b/common/src/leap/soledad/common/couch.py
index 456d4fdf..11b77938 100644
--- a/common/src/leap/soledad/common/couch.py
+++ b/common/src/leap/soledad/common/couch.py
@@ -35,7 +35,6 @@ from couchdb.client import Server
 from couchdb.http import (
     ResourceConflict,
     ResourceNotFound,
-    Unauthorized,
     ServerError,
     Session,
 )
@@ -48,6 +47,7 @@ from u1db.errors import (
     ConflictedDoc,
     DocumentDoesNotExist,
     DocumentAlreadyDeleted,
+    Unauthorized,
 )
 from u1db.backends import CommonBackend, CommonSyncTarget
 from u1db.remote import http_app
@@ -1451,7 +1451,6 @@ class CouchServerState(ServerState):
         :return: The CouchDatabase object.
         :rtype: CouchDatabase
         """
-        # TODO: open couch
         return CouchDatabase.open_database(
             self._couch_url + '/' + dbname,
             create=False)
@@ -1460,16 +1459,20 @@ class CouchServerState(ServerState):
         """
         Ensure couch database exists.
 
+        Usually, this method is used by the server to ensure the existence of
+        a database. In our setup, the Soledad user that accesses the underlying
+        couch server should never have permission to create (or delete)
+        databases. But, in case it ever does, by raising an exception here we
+        have one more guarantee that no modified client will be able to
+        enforce creation of a database when syncing.
+
         :param dbname: The name of the database to ensure.
         :type dbname: str
 
         :return: The CouchDatabase object and the replica uid.
         :rtype: (CouchDatabase, str)
         """
-        db = CouchDatabase.open_database(
-            self._couch_url + '/' + dbname,
-            create=True)
-        return db, db._replica_uid
+        raise Unauthorized()
 
     def delete_database(self, dbname):
         """
@@ -1478,7 +1481,7 @@ class CouchServerState(ServerState):
         :param dbname: The name of the database to delete.
         :type dbname: str
         """
-        CouchDatabase.delete_database(self._couch_url + '/' + dbname)
+        raise Unauthorized()
 
     def _set_couch_url(self, url):
         """
diff --git a/common/src/leap/soledad/common/tests/test_couch_operations_atomicity.py b/common/src/leap/soledad/common/tests/test_couch_operations_atomicity.py
index 5384d465..3c457cc5 100644
--- a/common/src/leap/soledad/common/tests/test_couch_operations_atomicity.py
+++ b/common/src/leap/soledad/common/tests/test_couch_operations_atomicity.py
@@ -33,11 +33,17 @@ from leap.soledad.common.tests.test_target import (
     make_leap_document_for_test,
     token_leap_sync_target,
 )
+from leap.soledad.common.tests.test_server import _couch_ensure_database
 
 
 REPEAT_TIMES = 20
 
 
+# monkey path CouchServerState so it can ensure databases.
+
+CouchServerState.ensure_database = _couch_ensure_database
+
+
 class CouchAtomicityTestCase(CouchDBTestCase, TestCaseWithServer):
 
     @staticmethod
diff --git a/common/src/leap/soledad/common/tests/test_server.py b/common/src/leap/soledad/common/tests/test_server.py
index 06595ed2..f8d2a64f 100644
--- a/common/src/leap/soledad/common/tests/test_server.py
+++ b/common/src/leap/soledad/common/tests/test_server.py
@@ -51,6 +51,17 @@ from leap.soledad.server import SoledadApp, LockResource
 from leap.soledad.server.auth import URLToAuthorization
 
 
+# monkey path CouchServerState so it can ensure databases.
+
+def _couch_ensure_database(self, dbname):
+    db = CouchDatabase.open_database(
+        self._couch_url + '/' + dbname,
+        create=True)
+    return db, db._replica_uid
+
+CouchServerState.ensure_database = _couch_ensure_database
+
+
 class ServerAuthorizationTestCase(BaseLeapTest):
     """
     Tests related to Soledad server authorization.
@@ -340,15 +351,16 @@ class EncryptedSyncTestCase(
         _, doclist = sol1.get_all_docs()
         self.assertEqual([], doclist)
         doc1 = sol1.create_doc(json.loads(simple_doc))
-        # sync with server
-        sol1._server_url = self.getURL()
-        sol1.sync()
-        # assert doc was sent to couch db
+        # ensure remote db exists before syncing
         db = CouchDatabase(
             self._couch_url,
             # the name of the user database is "user-<uuid>".
             'user-user-uuid',
         )
+        # sync with server
+        sol1._server_url = self.getURL()
+        sol1.sync()
+        # assert doc was sent to couch db
         _, doclist = db.get_all_docs()
         self.assertEqual(1, len(doclist))
         couchdoc = doclist[0]
@@ -395,15 +407,16 @@ class EncryptedSyncTestCase(
         _, doclist = sol1.get_all_docs()
         self.assertEqual([], doclist)
         doc1 = sol1.create_doc(json.loads(simple_doc))
-        # sync with server
-        sol1._server_url = self.getURL()
-        sol1.sync()
-        # assert doc was sent to couch db
+        # ensure remote db exists before syncing
         db = CouchDatabase(
             self._couch_url,
             # the name of the user database is "user-<uuid>".
             'user-user-uuid',
         )
+        # sync with server
+        sol1._server_url = self.getURL()
+        sol1.sync()
+        # assert doc was sent to couch db
         _, doclist = db.get_all_docs()
         self.assertEqual(1, len(doclist))
         couchdoc = doclist[0]
@@ -454,6 +467,12 @@ class EncryptedSyncTestCase(
         self.assertEqual([], doclist)
         content = binascii.hexlify(os.urandom(length/2))  # len() == length
         doc1 = sol1.create_doc({'data': content})
+        # ensure remote db exists before syncing
+        db = CouchDatabase(
+            self._couch_url,
+            # the name of the user database is "user-<uuid>".
+            'user-user-uuid',
+        )
         # sync with server
         sol1._server_url = self.getURL()
         sol1.sync()
@@ -473,11 +492,6 @@ class EncryptedSyncTestCase(
         # assert incoming doc is equal to the first sent doc
         self.assertEqual(doc1, doc2)
         # delete remote database
-        db = CouchDatabase(
-            self._couch_url,
-            # the name of the user database is "user-<uuid>".
-            'user-user-uuid',
-        )
         db.delete_database()
 
 
@@ -497,6 +511,12 @@ class EncryptedSyncTestCase(
         # create many small files
         for i in range(0, number_of_docs):
             sol1.create_doc(json.loads(simple_doc))
+        # ensure remote db exists before syncing
+        db = CouchDatabase(
+            self._couch_url,
+            # the name of the user database is "user-<uuid>".
+            'user-user-uuid',
+        )
         # sync with server
         sol1._server_url = self.getURL()
         sol1.sync()
@@ -516,11 +536,6 @@ class EncryptedSyncTestCase(
         for doc in doclist:
             self.assertEqual(sol1.get_doc(doc.doc_id), doc)
         # delete remote database
-        db = CouchDatabase(
-            self._couch_url,
-            # the name of the user database is "user-<uuid>".
-            'user-user-uuid',
-        )
         db.delete_database()
 
 class LockResourceTestCase(
@@ -542,6 +557,9 @@ class LockResourceTestCase(
         CouchDBTestCase.setUp(self)
         self.tempdir = tempfile.mkdtemp(prefix="leap_tests-")
         self._couch_url = 'http://localhost:' + str(self.wrapper.port)
+        # create the databases
+        CouchDatabase(self._couch_url, 'shared')
+        CouchDatabase(self._couch_url, 'tokens')
         self._state = CouchServerState(
             self._couch_url, 'shared', 'tokens')