Refactor LDAP authentication

* ldap uri can be specified in /etc/certidude/server.conf now
* /etc/ldap/ldap.conf is ignored

certidude/api/__init__.py

@@ -44,7 +44,6 @@ class SessionResource(object):
     @login_required
     @event_source
     def on_get(self, req, resp):
-
         return dict(
             user = dict(
                 name=req.context.get("user").name,

certidude/auth.py

@@ -122,9 +122,9 @@ def authenticate(optional=False):
             import ldap
 
             if not req.auth:
-                resp.append_header("WWW-Authenticate", "Basic")
-                raise falcon.HTTPUnauthorized("Forbidden",
-                    "Please authenticate with %s domain account or supply UPN" % const.DOMAIN)
+                raise falcon.HTTPUnauthorized("Unauthorized",
+                    "No authentication header provided",
+                    ("Basic",))
 
             if not req.auth.startswith("Basic "):
                 raise falcon.HTTPForbidden("Forbidden", "Bad header: %s" % req.auth)
@@ -133,26 +133,35 @@ def authenticate(optional=False):
             basic, token = req.auth.split(" ", 1)
             user, passwd = b64decode(token).split(":", 1)
 
-            for server in config.LDAP_SERVERS:
-                click.echo("Connecting to %s as %s" % (server, user))
-                conn = ldap.initialize(server)
-                conn.set_option(ldap.OPT_REFERRALS, 0)
-                try:
-                    conn.simple_bind_s(user if "@" in user else "%s@%s" % (user, const.DOMAIN), passwd)
-                except ldap.LDAPError, e:
-                    resp.append_header("WWW-Authenticate", "Basic")
-                    logger.critical(u"LDAP bind authentication failed for user %s from  %s",
-                        repr(user), req.context.get("remote_addr"))
-                    raise falcon.HTTPUnauthorized("Forbidden",
-                        "Please authenticate with %s domain account or supply UPN" % const.DOMAIN)
+            click.echo("Connecting to %s as %s" % (config.LDAP_AUTHENTICATION_URI, user))
+            conn = ldap.initialize(config.LDAP_AUTHENTICATION_URI)
+            conn.set_option(ldap.OPT_REFERRALS, 0)
 
-                req.context["ldap_conn"] = conn
-                break
-            else:
-                raise ValueError("No LDAP servers!")
+            if "@" not in user:
+                user = "%s@%s" % (user, const.DOMAIN)
+                logger.debug("Expanded username to %s", user)
 
+            try:
+                conn.simple_bind_s(user, passwd)
+            except ldap.STRONG_AUTH_REQUIRED:
+                logger.critical("LDAP server demands encryption, use ldaps:// instead of ldaps://")
+                raise
+            except ldap.SERVER_DOWN:
+                logger.critical("Failed to connect LDAP server at %s, are you sure LDAP server's CA certificate has been copied to this machine?",
+                    config.LDAP_AUTHENTICATION_URI)
+                raise
+            except ldap.INVALID_CREDENTIALS:
+                logger.critical(u"LDAP bind authentication failed for user %s from  %s",
+                    repr(user), req.context.get("remote_addr"))
+                raise falcon.HTTPUnauthorized("Forbidden",
+                    "Please authenticate with %s domain account or supply UPN" % const.DOMAIN,
+		("Basic",))
+
+            req.context["ldap_conn"] = conn
             req.context["user"] = User.objects.get(user)
-            return func(resource, req, resp, *args, **kwargs)
+            retval = func(resource, req, resp, *args, **kwargs)
+            conn.unbind_s()
+            return retval
 
 
         def pam_authenticate(resource, req, resp, *args, **kwargs):

certidude/config.py

@@ -18,8 +18,10 @@ AUTHENTICATION_BACKENDS = set([j for j in
 AUTHORIZATION_BACKEND = cp.get("authorization", "backend")  # whitelist, ldap, posix
 ACCOUNTS_BACKEND = cp.get("accounts", "backend")             # posix, ldap
 
-if ACCOUNTS_BACKEND == "ldap":
-    LDAP_GSSAPI_CRED_CACHE = cp.get("accounts", "ldap gssapi credential cache")
+LDAP_AUTHENTICATION_URI = cp.get("authentication", "ldap uri")
+LDAP_GSSAPI_CRED_CACHE = cp.get("accounts", "ldap gssapi credential cache")
+LDAP_ACCOUNTS_URI = cp.get("accounts", "ldap uri")
+LDAP_BASE = cp.get("accounts", "ldap base")
 
 USER_SUBNETS = set([ipaddress.ip_network(j) for j in
     cp.get("authorization", "user subnets").split(" ") if j])
@@ -78,17 +80,4 @@ elif "ldap" == AUTHORIZATION_BACKEND:
 else:
     raise NotImplementedError("Unknown authorization backend '%s'" % AUTHORIZATION_BACKEND)
 
-for line in open("/etc/ldap/ldap.conf"):
-    line = line.strip().lower()
-    if "#" in line:
-        line, _ = line.split("#", 1)
-    if not " " in line:
-        continue
-    key, value = line.split(" ", 1)
-    if key == "uri":
-        LDAP_SERVERS = set([j for j in value.split(" ") if j])
-        click.echo("LDAP servers: %s" % " ".join(LDAP_SERVERS))
-    elif key == "base":
-        LDAP_BASE = value
-
 # TODO: Check if we don't have base or servers

certidude/templates/certidude-server.conf

@@ -9,11 +9,12 @@ backends = pam
 ;backends = ldap
 ;backends = kerberos ldap
 ;backends = kerberos pam
+ldap uri = ldaps://dc1.example.com
 
 [accounts]
 # The accounts backend specifies how the user's given name, surname and e-mail
 # address are looked up. In case of 'posix' basically 'getent passwd' is performed,
-# in case of 'ldap' a search is performed on LDAP server specified in /etc/ldap/ldap.conf
+# in case of 'ldap' a search is performed on LDAP server specified by ldap uri
 # with Kerberos credential cache initialized at path specified by environment variable KRB5CCNAME
 # If certidude setup authority was performed correctly the credential cache should be
 # updated automatically by /etc/cron.hourly/certidude
@@ -21,6 +22,8 @@ backends = pam
 backend = posix
 ;backend = ldap
 ldap gssapi credential cache = /run/certidude/krb5cc
+ldap uri = ldap://dc1.example.com
+ldap base = {% if base %}{{ base }}{% else %}dc=example,dc=com{% endif %}
 
 [authorization]
 # The authorization backend specifies how the users are authorized.

certidude/user.py

@@ -70,17 +70,15 @@ class DirectoryConnection(object):
             raise ValueError("Ticket cache at %s not initialized, unable to "
                 "authenticate with computer account against LDAP server!" % config.LDAP_GSSAPI_CRED_CACHE)
         os.environ["KRB5CCNAME"] = config.LDAP_GSSAPI_CRED_CACHE
-        for server in config.LDAP_SERVERS:
-            self.conn = ldap.initialize(server)
-            self.conn.set_option(ldap.OPT_REFERRALS, 0)
-            click.echo("Connecing to %s using Kerberos ticket cache from %s" %
-                (server, config.LDAP_GSSAPI_CRED_CACHE))
-            self.conn.sasl_interactive_bind_s('', ldap.sasl.gssapi())
-            return self.conn
-        raise ValueError("No LDAP servers specified!")
+        self.conn = ldap.initialize(config.LDAP_ACCOUNTS_URI)
+        self.conn.set_option(ldap.OPT_REFERRALS, 0)
+        click.echo("Connecing to %s using Kerberos ticket cache from %s" %
+            (config.LDAP_ACCOUNTS_URI, config.LDAP_GSSAPI_CRED_CACHE))
+        self.conn.sasl_interactive_bind_s('', ldap.sasl.gssapi())
+        return self.conn
 
     def __exit__(self, type, value, traceback):
-        self.conn.unbind_s
+        self.conn.unbind_s()
 
 
 class ActiveDirectoryUserManager(object):