Implemented TLS encrypted connections

Implemented TLS encrypted connections. Added command line argument and
configuration file option to accept invalid (self-signed) certificates.
Fixed a couple of unrelated issues.

1 files changed, 23 insertions, 7 deletions

diff --git a/pam/pam_mfa.py b/pam/pam_mfa.py
index 85d0a82..5a5a112 100755
--- a/pam/pam_mfa.py
+++ b/pam/pam_mfa.py
@@ -1,5 +1,6 @@
 #!/usr/bin/python3
 import socket
+import ssl
 import argparse
 import time
 import sys
@@ -33,9 +34,11 @@ def parse_arguments():
                         default="/etc/mfa/mfa.conf")
     parser.add_argument("--server",type=str,help="MFA server address")
     parser.add_argument("--port",type=str,help="MFA server PAM connection port")
+    parser.add_argument("--insecure",action="store_true",
+                        help="Accept invalid TLS certificates")
     return parser.parse_args()
 
-def init_connection(mfa_server, pam_port):
+def init_connection(mfa_server, pam_port, insecure):
     # Attempts to connect to MFA server with provided address and port
     # Repeats connection attempts once per second until timeout is reached
     # Returns the socket if connection was successful or None otherwise
@@ -43,13 +46,22 @@ def init_connection(mfa_server, pam_port):
     timeout = 0
     timeout_length = 5
     sleep_length = 1
+    context = ssl.create_default_context()
+    if insecure:
+        context.check_hostname = False
+        context.verify_mode = 0
     while connection == None and timeout < timeout_length:
         try:
-            connection = socket.create_connection((mfa_server,pam_port))
+            #connection = socket.create_connection((mfa_server,client_port))
+            connection = context.wrap_socket(socket.socket(socket.AF_INET),
+                                             server_hostname=mfa_server)
+            connection.connect((mfa_server,int(pam_port)))
             return connection
         except (ConnectionError,ConnectionRefusedError):
             time.sleep(sleep_length)
             timeout += sleep_length
+        except ssl.SSLCertVerificationError:
+            die("error: server presented invalid certificate")
     return None
 
 
@@ -82,24 +94,28 @@ def get_vars(args,confparser):
 
     server = None
     port = None
+    insecure = None
 
     # Set values from config file first
     if confparser.has_section("pam"):
         server = confparser.get("pam","server",fallback=None) 
         port = confparser.get("pam","port",fallback=None) 
+        insecure = bool(confparser.get("pam","insecure",fallback=False))
         
     # Let command line args overwrite any values
-    if args.server:
+    if args.server != None:
         server = args.server
-    if args.port:
+    if args.port != None:
         port = args.port
+    if args.insecure:
+        insecure = args.insecure
 
     # Exit if any value is null
     if None in [server,port]:
         print("error: one or more items unspecified")
         sys.exit(1)
 
-    return server,port
+    return server,port,insecure
 
 
 def main():
@@ -109,7 +125,7 @@ def main():
     # Get arguments
     args = parse_arguments()
     confparser = read_config(args.config)
-    mfa_server,pam_port = get_vars(args,confparser)
+    mfa_server,pam_port,insecure = get_vars(args,confparser)
     user = args.user
     service = args.service
 
@@ -130,7 +146,7 @@ def main():
     
 
     # Initalize connection to MFA server.  Quit if unable to connect.
-    connection = init_connection(mfa_server,pam_port)
+    connection = init_connection(mfa_server,pam_port,insecure)
     if connection == None:
         print(failed)
         sys.exit(1)