krb5/0001-downstream-Revert-Don-t-issue-session-keys-with-depr.patch

From 6f7fd964539dfe4a885068f43a91db9738661870 Mon Sep 17 00:00:00 2001
From: Julien Rische <jrische@redhat.com>
Date: Tue, 9 Jul 2024 11:15:33 +0200
Subject: [PATCH] [downstream] Revert "Don't issue session keys with
 deprecated enctypes"

This reverts commit 1b57a4d134bbd0e7c52d5885a92eccc815726463.
---
 doc/admin/conf_files/krb5_conf.rst | 12 ------------
 doc/admin/enctypes.rst             | 23 +++-------------------
 src/include/k5-int.h               |  4 ----
 src/kdc/kdc_util.c                 | 10 ----------
 src/lib/krb5/krb/get_in_tkt.c      | 31 +++++++++++-------------------
 src/lib/krb5/krb/init_ctx.c        | 10 ----------
 src/tests/gssapi/t_enctypes.py     |  3 +--
 src/tests/t_etype_info.py          |  2 +-
 src/tests/t_sesskeynego.py         | 28 ++-------------------------
 src/util/k5test.py                 |  4 ++--
 10 files changed, 20 insertions(+), 107 deletions(-)

diff --git a/doc/admin/conf_files/krb5_conf.rst b/doc/admin/conf_files/krb5_conf.rst
index ecdf917501..f22d5db11b 100644
--- a/doc/admin/conf_files/krb5_conf.rst
+++ b/doc/admin/conf_files/krb5_conf.rst
@@ -95,18 +95,6 @@ Additionally, krb5.conf may include any of the relations described in
 
 The libdefaults section may contain any of the following relations:
 
-**allow_des3**
-    Permit the KDC to issue tickets with des3-cbc-sha1 session keys.
-    In future releases, this flag will allow des3-cbc-sha1 to be used
-    at all.  The default value for this tag is false.  (Added in
-    release 1.21.)
-
-**allow_rc4**
-    Permit the KDC to issue tickets with arcfour-hmac session keys.
-    In future releases, this flag will allow arcfour-hmac to be used
-    at all.  The default value for this tag is false.  (Added in
-    release 1.21.)
-
 **allow_weak_crypto**
     If this flag is set to false, then weak encryption types (as noted
     in :ref:`Encryption_types` in :ref:`kdc.conf(5)`) will be filtered
diff --git a/doc/admin/enctypes.rst b/doc/admin/enctypes.rst
index dce19ad43e..694922c0d9 100644
--- a/doc/admin/enctypes.rst
+++ b/doc/admin/enctypes.rst
@@ -48,15 +48,12 @@ Session key selection
 The KDC chooses the session key enctype by taking the intersection of
 its **permitted_enctypes** list, the list of long-term keys for the
 most recent kvno of the service, and the client's requested list of
-enctypes.  Starting in krb5-1.21, all services are assumed to support
-aes256-cts-hmac-sha1-96; also, des3-cbc-sha1 and arcfour-hmac session
-keys will not be issued by default.
+enctypes.
 
 Starting in krb5-1.11, it is possible to set a string attribute on a
 service principal to control what session key enctypes the KDC may
-issue for service tickets for that principal, overriding the service's
-long-term keys and the assumption of aes256-cts-hmac-sha1-96 support.
-See :ref:`set_string` in :ref:`kadmin(1)` for details.
+issue for service tickets for that principal.  See :ref:`set_string`
+in :ref:`kadmin(1)` for details.
 
 
 Choosing enctypes for a service
@@ -90,20 +87,6 @@ affect how enctypes are chosen.
     acceptable risk for your environment and the weak enctypes are
     required for backward compatibility.
 
-**allow_des3**
-    was added in release 1.21 and defaults to *false*.  Unless this
-    flag is set to *true*, the KDC will not issue tickets with
-    des3-cbc-sha1 session keys.  In a future release, this flag will
-    control whether des3-cbc-sha1 is permitted in similar fashion to
-    weak enctypes.
-
-**allow_rc4**
-    was added in release 1.21 and defaults to *false*.  Unless this
-    flag is set to *true*, the KDC will not issue tickets with
-    arcfour-hmac session keys.  In a future release, this flag will
-    control whether arcfour-hmac is permitted in similar fashion to
-    weak enctypes.
-
 **permitted_enctypes**
     controls the set of enctypes that a service will permit for
     session keys and for ticket and authenticator encryption.  The KDC
diff --git a/src/include/k5-int.h b/src/include/k5-int.h
index 2f7791b775..1d1c8293f4 100644
--- a/src/include/k5-int.h
+++ b/src/include/k5-int.h
@@ -180,8 +180,6 @@ typedef unsigned char   u_char;
  * matches the variable name.  Keep these alphabetized. */
 #define KRB5_CONF_ACL_FILE                     "acl_file"
 #define KRB5_CONF_ADMIN_SERVER                 "admin_server"
-#define KRB5_CONF_ALLOW_DES3                   "allow_des3"
-#define KRB5_CONF_ALLOW_RC4                    "allow_rc4"
 #define KRB5_CONF_ALLOW_WEAK_CRYPTO            "allow_weak_crypto"
 #define KRB5_CONF_AUTH_TO_LOCAL                "auth_to_local"
 #define KRB5_CONF_AUTH_TO_LOCAL_NAMES          "auth_to_local_names"
@@ -1240,8 +1238,6 @@ struct _krb5_context {
     struct _kdb_log_context *kdblog_context;
 
     krb5_boolean allow_weak_crypto;
-    krb5_boolean allow_des3;
-    krb5_boolean allow_rc4;
     krb5_boolean ignore_acceptor_hostname;
     krb5_boolean enforce_ok_as_delegate;
     enum dns_canonhost dns_canonicalize_hostname;
diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
index e54cc751f9..75e04b73db 100644
--- a/src/kdc/kdc_util.c
+++ b/src/kdc/kdc_util.c
@@ -1088,16 +1088,6 @@ select_session_keytype(krb5_context context, krb5_db_entry *server,
         if (!krb5_is_permitted_enctype(context, ktype[i]))
             continue;
 
-        /*
-         * Prevent these deprecated enctypes from being used as session keys
-         * unless they are explicitly allowed.  In the future they will be more
-         * comprehensively disabled and eventually removed.
-         */
-        if (ktype[i] == ENCTYPE_DES3_CBC_SHA1 && !context->allow_des3)
-            continue;
-        if (ktype[i] == ENCTYPE_ARCFOUR_HMAC && !context->allow_rc4)
-            continue;
-
         if (dbentry_supports_enctype(context, server, ktype[i]))
             return ktype[i];
     }
diff --git a/src/lib/krb5/krb/get_in_tkt.c b/src/lib/krb5/krb/get_in_tkt.c
index ea089f0fcc..1b420a3ac2 100644
--- a/src/lib/krb5/krb/get_in_tkt.c
+++ b/src/lib/krb5/krb/get_in_tkt.c
@@ -1582,31 +1582,22 @@ warn_pw_expiry(krb5_context context, krb5_get_init_creds_opt *options,
     (*prompter)(context, data, 0, banner, 0, 0);
 }
 
-/* Display a warning via the prompter if a deprecated enctype was used for
- * either the reply key or the session key. */
+/* Display a warning via the prompter if des3-cbc-sha1 was used for either the
+ * reply key or the session key. */
 static void
-warn_deprecated(krb5_context context, krb5_init_creds_context ctx,
-                krb5_enctype as_key_enctype)
+warn_des3(krb5_context context, krb5_init_creds_context ctx,
+          krb5_enctype as_key_enctype)
 {
-    krb5_enctype etype;
-    char encbuf[128], banner[256];
+    const char *banner;
 
-    if (ctx->prompter == NULL)
-        return;
-
-    if (krb5int_c_deprecated_enctype(as_key_enctype))
-        etype = as_key_enctype;
-    else if (krb5int_c_deprecated_enctype(ctx->cred.keyblock.enctype))
-        etype = ctx->cred.keyblock.enctype;
-    else
+    if (as_key_enctype != ENCTYPE_DES3_CBC_SHA1 &&
+        ctx->cred.keyblock.enctype != ENCTYPE_DES3_CBC_SHA1)
         return;
-
-    if (krb5_enctype_to_name(etype, FALSE, encbuf, sizeof(encbuf)) != 0)
+    if (ctx->prompter == NULL)
         return;
-    snprintf(banner, sizeof(banner),
-             _("Warning: encryption type %s used for authentication is "
-               "deprecated and will be disabled"), encbuf);
 
+    banner = _("Warning: encryption type des3-cbc-sha1 used for "
+               "authentication is weak and will be disabled");
     /* PROMPTER_INVOCATION */
     (*ctx->prompter)(context, ctx->prompter_data, NULL, banner, 0, NULL);
 }
@@ -1857,7 +1848,7 @@ init_creds_step_reply(krb5_context context,
     ctx->complete = TRUE;
     warn_pw_expiry(context, ctx->opt, ctx->prompter, ctx->prompter_data,
                    ctx->in_tkt_service, ctx->reply);
-    warn_deprecated(context, ctx, encrypting_key.enctype);
+    warn_des3(context, ctx, encrypting_key.enctype);
 
 cleanup:
     krb5_free_pa_data(context, kdc_padata);
diff --git a/src/lib/krb5/krb/init_ctx.c b/src/lib/krb5/krb/init_ctx.c
index a6c2bbeb54..87b486c53f 100644
--- a/src/lib/krb5/krb/init_ctx.c
+++ b/src/lib/krb5/krb/init_ctx.c
@@ -221,16 +221,6 @@ krb5_init_context_profile(profile_t profile, krb5_flags flags,
         goto cleanup;
     ctx->allow_weak_crypto = tmp;
 
-    retval = get_boolean(ctx, KRB5_CONF_ALLOW_DES3, 0, &tmp);
-    if (retval)
-        goto cleanup;
-    ctx->allow_des3 = tmp;
-
-    retval = get_boolean(ctx, KRB5_CONF_ALLOW_RC4, 0, &tmp);
-    if (retval)
-        goto cleanup;
-    ctx->allow_rc4 = tmp;
-
     retval = get_boolean(ctx, KRB5_CONF_IGNORE_ACCEPTOR_HOSTNAME, 0, &tmp);
     if (retval)
         goto cleanup;
diff --git a/src/tests/gssapi/t_enctypes.py b/src/tests/gssapi/t_enctypes.py
index f5f11842e2..7494d7fcdb 100755
--- a/src/tests/gssapi/t_enctypes.py
+++ b/src/tests/gssapi/t_enctypes.py
@@ -18,8 +18,7 @@ d_rc4 = 'DEPRECATED:arcfour-hmac'
 # These tests make assumptions about the default enctype lists, so set
 # them explicitly rather than relying on the library defaults.
 supp='aes256-cts:normal aes128-cts:normal des3-cbc-sha1:normal rc4-hmac:normal'
-conf = {'libdefaults': {'permitted_enctypes': 'aes des3 rc4',
-                        'allow_des3': 'true', 'allow_rc4': 'true'},
+conf = {'libdefaults': {'permitted_enctypes': 'aes des3 rc4'},
         'realms': {'$realm': {'supported_enctypes': supp}}}
 realm = K5Realm(krb5_conf=conf)
 shutil.copyfile(realm.ccache, os.path.join(realm.testdir, 'save'))
diff --git a/src/tests/t_etype_info.py b/src/tests/t_etype_info.py
index 38cf96ca8f..c982508d8b 100644
--- a/src/tests/t_etype_info.py
+++ b/src/tests/t_etype_info.py
@@ -1,7 +1,7 @@
 from k5test import *
 
 supported_enctypes = 'aes128-cts des3-cbc-sha1 rc4-hmac'
-conf = {'libdefaults': {'allow_des3': 'true', 'allow_rc4': 'true'},
+conf = {'libdefaults': {'allow_weak_crypto': 'true'},
         'realms': {'$realm': {'supported_enctypes': supported_enctypes}}}
 realm = K5Realm(create_host=False, get_creds=False, krb5_conf=conf)
 
diff --git a/src/tests/t_sesskeynego.py b/src/tests/t_sesskeynego.py
index 5a213617b5..9024aee838 100755
--- a/src/tests/t_sesskeynego.py
+++ b/src/tests/t_sesskeynego.py
@@ -25,8 +25,6 @@ conf3 = {'libdefaults': {
         'default_tkt_enctypes': 'aes128-cts',
         'default_tgs_enctypes': 'rc4-hmac,aes128-cts'}}
 conf4 = {'libdefaults': {'permitted_enctypes': 'aes256-cts'}}
-conf5 = {'libdefaults': {'allow_rc4': 'true'}}
-conf6 = {'libdefaults': {'allow_des3': 'true'}}
 # Test with client request and session_enctypes preferring aes128, but
 # aes256 long-term key.
 realm = K5Realm(krb5_conf=conf1, create_host=False, get_creds=False)
@@ -56,12 +54,10 @@ realm.run([kadminl, 'setstr', 'server', 'session_enctypes',
            'aes128-cts,aes256-cts'])
 test_kvno(realm, 'aes128-cts-hmac-sha1-96', 'aes256-cts-hmac-sha1-96')
 
-# 3b: Skip RC4 (as the KDC does not allow it for session keys by
-# default) and negotiate aes128-cts session key, with only an aes256
-# long-term service key.
+# 3b: Negotiate rc4-hmac session key when principal only has aes256 long-term.
 realm.run([kadminl, 'setstr', 'server', 'session_enctypes',
            'rc4-hmac,aes128-cts,aes256-cts'])
-test_kvno(realm, 'aes128-cts-hmac-sha1-96', 'aes256-cts-hmac-sha1-96')
+test_kvno(realm, 'DEPRECATED:arcfour-hmac', 'aes256-cts-hmac-sha1-96')
 realm.stop()
 
 # 4: Check that permitted_enctypes is a default for session key enctypes.
@@ -71,24 +67,4 @@ realm.run([kvno, 'user'],
           expected_trace=('etypes requested in TGS request: aes256-cts',))
 realm.stop()
 
-# 5: allow_rc4 permits negotiation of rc4-hmac session key.
-realm = K5Realm(krb5_conf=conf5, create_host=False, get_creds=False)
-realm.run([kadminl, 'addprinc', '-randkey', '-e', 'aes256-cts', 'server'])
-realm.run([kadminl, 'setstr', 'server', 'session_enctypes', 'rc4-hmac'])
-test_kvno(realm, 'DEPRECATED:arcfour-hmac', 'aes256-cts-hmac-sha1-96')
-realm.stop()
-
-# 6: allow_des3 permits negotiation of des3-cbc-sha1 session key.
-realm = K5Realm(krb5_conf=conf6, create_host=False, get_creds=False)
-realm.run([kadminl, 'addprinc', '-randkey', '-e', 'aes256-cts', 'server'])
-realm.run([kadminl, 'setstr', 'server', 'session_enctypes', 'des3-cbc-sha1'])
-test_kvno(realm, 'DEPRECATED:des3-cbc-sha1', 'aes256-cts-hmac-sha1-96')
-realm.stop()
-
-# 7: default config negotiates aes256-sha1 session key for RC4-only service.
-realm = K5Realm(create_host=False, get_creds=False)
-realm.run([kadminl, 'addprinc', '-randkey', '-e', 'rc4-hmac', 'server'])
-test_kvno(realm, 'aes256-cts-hmac-sha1-96', 'DEPRECATED:arcfour-hmac')
-realm.stop()
-
 success('sesskeynego')
diff --git a/src/util/k5test.py b/src/util/k5test.py
index 8e5f5ba8e9..2a86c5cdfc 100644
--- a/src/util/k5test.py
+++ b/src/util/k5test.py
@@ -1340,14 +1340,14 @@ _passes = [
 
     # Exercise the DES3 enctype.
     ('des3', None,
-     {'libdefaults': {'permitted_enctypes': 'des3 aes256-sha1'}},
+     {'libdefaults': {'permitted_enctypes': 'des3'}},
      {'realms': {'$realm': {
                     'supported_enctypes': 'des3-cbc-sha1:normal',
                     'master_key_type': 'des3-cbc-sha1'}}}),
 
     # Exercise the arcfour enctype.
     ('arcfour', None,
-     {'libdefaults': {'permitted_enctypes': 'rc4 aes256-sha1'}},
+     {'libdefaults': {'permitted_enctypes': 'rc4'}},
      {'realms': {'$realm': {
                     'supported_enctypes': 'arcfour-hmac:normal',
                     'master_key_type': 'arcfour-hmac'}}}),
-- 
2.45.1