Print Kerberos error names

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Support for storing multiple GMSAs secrets in a single keytab file (#5)
+- Print Kerberos error names (#7)
 
 ## [0.1.0] - 2023-06-05
 

gmsad/salt.py

@@ -23,6 +23,7 @@
 import random
 import socket
 from typing import Any as AnyType
+from enum import IntEnum
 
 from asn1crypto.core import Sequence, SequenceOf, Integer, BitString, OctetString, GeneralString, \
     GeneralizedTime, Any
@@ -52,6 +53,77 @@
 
 KERBEROS_PORT = 88
 
+# From RFC 4120 section 7.5.9
+class KRBErrorCode(IntEnum):
+    KDC_ERR_NONE = 0
+    KDC_ERR_NAME_EXP = 1
+    KDC_ERR_SERVICE_EXP = 2
+    KDC_ERR_BAD_PVNO = 3
+    KDC_ERR_C_OLD_MAST_KVNO = 4
+    KDC_ERR_S_OLD_MAST_KVNO = 5
+    KDC_ERR_C_PRINCIPAL_UNKNOWN = 6
+    KDC_ERR_S_PRINCIPAL_UNKNOWN = 7
+    KDC_ERR_PRINCIPAL_NOT_UNIQUE = 8
+    KDC_ERR_NULL_KEY = 9
+    KDC_ERR_CANNOT_POSTDATE = 10
+    KDC_ERR_NEVER_VALID = 11
+    KDC_ERR_POLICY = 12
+    KDC_ERR_BADOPTION = 13
+    KDC_ERR_ETYPE_NOSUPP = 14
+    KDC_ERR_SUMTYPE_NOSUPP = 15
+    KDC_ERR_PADATA_TYPE_NOSUPP = 16
+    KDC_ERR_TRTYPE_NOSUPP = 17
+    KDC_ERR_CLIENT_REVOKED = 18
+    KDC_ERR_SERVICE_REVOKED = 19
+    KDC_ERR_TGT_REVOKED = 20
+    KDC_ERR_CLIENT_NOTYET = 21
+    KDC_ERR_SERVICE_NOTYET = 22
+    KDC_ERR_KEY_EXPIRED = 23
+    KDC_ERR_PREAUTH_FAILED = 24
+    KDC_ERR_PREAUTH_REQUIRED = 25
+    KDC_ERR_SERVER_NOMATCH = 26
+    KDC_ERR_MUST_USE_USER2USER = 27
+    KDC_ERR_PATH_NOT_ACCEPTED = 28
+    KDC_ERR_SVC_UNAVAILABLE = 29
+    KRB_AP_ERR_BAD_INTEGRITY = 31
+    KRB_AP_ERR_TKT_EXPIRED = 32
+    KRB_AP_ERR_TKT_NYV = 33
+    KRB_AP_ERR_REPEAT = 34
+    KRB_AP_ERR_NOT_US = 35
+    KRB_AP_ERR_BADMATCH = 36
+    KRB_AP_ERR_SKEW = 37
+    KRB_AP_ERR_BADADDR = 38
+    KRB_AP_ERR_BADVERSION = 39
+    KRB_AP_ERR_MSG_TYPE = 40
+    KRB_AP_ERR_MODIFIED = 41
+    KRB_AP_ERR_BADORDER = 42
+    KRB_AP_ERR_BADKEYVER = 44
+    KRB_AP_ERR_NOKEY = 45
+    KRB_AP_ERR_MUT_FAIL = 46
+    KRB_AP_ERR_BADDIRECTION = 47
+    KRB_AP_ERR_METHOD = 48
+    KRB_AP_ERR_BADSEQ = 49
+    KRB_AP_ERR_INAPP_CKSUM = 50
+    KRB_AP_PATH_NOT_ACCEPTED = 51
+    KRB_ERR_RESPONSE_TOO_BIG = 52
+    KRB_ERR_GENERIC = 60
+    KRB_ERR_FIELD_TOOLONG = 61
+    KDC_ERROR_CLIENT_NOT_TRUSTED = 62
+    KDC_ERROR_KDC_NOT_TRUSTED = 63
+    KDC_ERROR_INVALID_SIG = 64
+    KDC_ERR_KEY_TOO_WEAK = 65
+    KDC_ERR_CERTIFICATE_MISMATCH = 66
+    KRB_AP_ERR_NO_TGT = 67
+    KDC_ERR_WRONG_REALM = 68
+    KRB_AP_ERR_USER_TO_USER_REQUIRED = 69
+    KDC_ERR_CANT_VERIFY_CERTIFICATE = 70
+    KDC_ERR_INVALID_CERTIFICATE = 71
+    KDC_ERR_REVOKED_CERTIFICATE = 72
+    KDC_ERR_REVOCATION_STATUS_UNKNOWN = 73
+    KDC_ERR_REVOCATION_STATUS_UNAVAILABLE = 74
+    KDC_ERR_CLIENT_NAME_MISMATCH = 75
+    KDC_ERR_KDC_NAME_MISMATCH = 76
+
 class EncryptedData(Sequence):
     _fields = [
         ('etype', Integer, {'explicit': 0}),
@@ -274,14 +346,16 @@ def get_salt_from_rep(kdc_rep: bytes) -> str:
     if tag == KRB_ERROR_TAG_NUMBER:
         err = KRB_ERROR.load(kdc_rep)
         error_code = err['error-code'].native
-        if error_code == KDC_ERR_PREAUTH_REQUIRED:
+        if error_code == KRBErrorCode.KDC_ERR_PREAUTH_REQUIRED:
             for padata in PA_DATA_SEQUENCE_OF.load(err['e-data'].native):
                 if padata['padata-type'].native == PA_ETYPE_INFO2:
                     etype = ETYPE_INFO2()
                     for pa_etype_info2_value in etype.load(padata['padata-value'].native):
                         if pa_etype_info2_value['etype'].native == AES256_CTS_HMAC_SHA1h96_ENC_TYPE:
                             # XXX: Adding str just for mypy
                             return str(pa_etype_info2_value['salt'].native)
+        else:
+            raise Exception(f"Could not retrieve salt from AS_REP, got Kerberos error {KRBErrorCode(error_code).name} ({error_code})")
     elif tag == AS_REP_TAG_NUMBER:
         # In this case the gMSA has the DONT_REQUIRE_PREAUTH flag in its
         # userAccountControl attribute