Begin work to support complex PAM conversations

For example, TOTP setups need
more prompts, this will pass
the info to the client for the client to adjust.

confluent_server/confluent/auth.py

@@ -283,9 +283,14 @@ def check_user_passphrase(name, passphrase, operation=None, element=None, tenant
                     # pam_unix uses unix_chkpwd which reque
                     os.setuid(pwe.pw_uid)
                     usergood = pam.authenticate(user, passphrase, service=_pamservice)
+                except pam.PromptsNeeded:
+                    os._exit(2)
                 finally:
                     os._exit(0 if usergood else 1)
-            usergood = os.waitpid(pid, 0)[1] == 0
+            usergood = os.waitpid(pid, 0)[1]
+            if (usergood >> 8) == 2:
+                pam.authenticate(user, passphrase, service=_pamservice)
+            usergood = usergood == 0
         else:
             # We are running as root, we don't need to fork in order to authenticate the
             # user

confluent_server/confluent/httpapi.py

@@ -307,7 +307,12 @@ def _authorize_request(env, operation):
             return ('logout',)
         name, passphrase = base64.b64decode(
             env['HTTP_AUTHORIZATION'].replace('Basic ', '')).split(b':', 1)
-        authdata = auth.check_user_passphrase(name, passphrase, operation=operation, element=element)
+        try:
+            authdata = auth.check_user_passphrase(name, passphrase, operation=operation, element=element)
+        except Exception as e:
+            if hasattr(e, 'prompts'):
+                return {'code': 403, 'prompts': e.prompts}
+            raise
         if authdata is False:
             return {'code': 403}
         elif not authdata:
@@ -519,7 +524,14 @@ def resourcehandler_backend(env, start_response):
         return
     if authorized['code'] == 403:
         start_response('403 Forbidden', badauth)
-        yield 'Forbidden'
+        response = {'result': 'Forbidden'}
+        if 'prompts' in authorized:
+            response['prompts'] = []
+            for prompt in authorized['prompts']:
+                if not isinstance(prompt, str):
+                    prompt = prompt.decode('utf8')
+                response['prompts'].append(prompt)
+        yield json.dumps(response)
         return
     if authorized['code'] != 200:
         raise Exception("Unrecognized code from auth engine")

confluent_server/confluent/pam.py

@@ -103,6 +103,12 @@ pam_authenticate          = libpam.pam_authenticate
 pam_authenticate.restype  = c_int
 pam_authenticate.argtypes = [PamHandle, c_int]
 
+
+class PromptsNeeded(Exception):
+    def __init__(self, prompts):
+        self.prompts = prompts
+
+
 class pam():
     code   = 0
     reason = None
@@ -110,7 +116,7 @@ class pam():
     def __init__(self):
         pass
 
-    def authenticate(self, username, password, service='login', encoding='utf-8', resetcreds=True):
+    def authenticate(self, username, password, service='login', encoding='utf-8', resetcreds=True, answers=None):
         """username and password authentication for the given service.
 
            Returns True for success, or False for failure.
@@ -142,8 +148,15 @@ class pam():
             p_response[0] = response
             for i in range(n_messages):
                 if messages[i].contents.msg_style == PAM_PROMPT_ECHO_OFF:
-                    dst = calloc(len(password)+1, sizeof(c_char))
-                    memmove(dst, cpassword, len(password))
+                    prompts.add(messages[i].contents.msg)
+                    if answers and messages[i].contents.msg in answers:
+                        currpassword = answers[messages[i].contents.msg]
+                        currcpassword = c_char_p(currpassword)
+                    else:
+                        currpassword = password
+                        currcpassword = cpassword
+                    dst = calloc(len(currpassword)+1, sizeof(c_char))
+                    memmove(dst, currcpassword, len(currpassword))
                     response[i].resp = dst
                     response[i].resp_retcode = 0
             return 0
@@ -169,6 +182,7 @@ class pam():
         # do this up front so we can safely throw an exception if there's
         # anything wrong with it
         cpassword = c_char_p(password)
+        prompts = set([])
 
         handle = PamHandle()
         conv   = PamConv(my_conv, 0)
@@ -198,7 +212,8 @@ class pam():
 
         if hasattr(libpam, 'pam_end'):
             pam_end(handle, retval)
-
+        if answers is None and len(prompts) > 1 and not auth_success:
+            raise PromptsNeeded(prompts)
         return auth_success