krb5 commit: Restrict test KDB to local principals

[Greg Hudson]

https://github.com/krb5/krb5/commit/8c4bbfa21fe539fc8644e77814bf05ad00574750
commit 8c4bbfa21fe539fc8644e77814bf05ad00574750
Author: Isaac Boukris <iboukris at gmail.com>
Date:   Sun Jan 12 18:57:10 2020 +0100

    Restrict test KDB to local principals
    
    Ignoring the lookup realm for principal matching could cause the test
    KDB module to successfully look up entries (with the correct key data)
    for principals that a real KDB wouldn't have, such as krbtgt/B at A
    within realm C.  Add a realm check to test_get_principal(), allowing
    only local principal names or incoming cross-TGS names.
    
    [ghudson at mit.edu: changed error code; rewrote commit message]

 src/plugins/kdb/test/kdb_test.c |   27 ++++++++++++++++++++++++++-
 src/tests/gssapi/t_s4u.py       |    4 +++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/plugins/kdb/test/kdb_test.c b/src/plugins/kdb/test/kdb_test.c
index 69a4663..76974df 100644
--- a/src/plugins/kdb/test/kdb_test.c
+++ b/src/plugins/kdb/test/kdb_test.c
@@ -332,6 +332,27 @@ tgtname(krb5_context context, const krb5_data *tgs_realm,
     return princ;
 }
 
+/* Return true if search_for is within context's default realm or is an
+ * incoming cross-realm TGS name. */
+static krb5_boolean
+request_for_us(krb5_context context, krb5_const_principal search_for)
+{
+    char *defrealm;
+    krb5_data realm;
+    krb5_boolean for_us;
+    krb5_principal local_tgs;
+
+    check(krb5_get_default_realm(context, &defrealm));
+    realm = string2data(defrealm);
+    local_tgs = tgtname(context, &realm, &realm);
+    krb5_free_default_realm(context, defrealm);
+
+    for_us = krb5_realm_compare(context, local_tgs, search_for) ||
+        krb5_principal_compare_any_realm(context, local_tgs, search_for);
+    krb5_free_principal(context, local_tgs);
+    return for_us;
+}
+
 static krb5_error_code
 test_get_principal(krb5_context context, krb5_const_principal search_for,
                    unsigned int flags, krb5_db_entry **entry)
@@ -346,6 +367,9 @@ test_get_principal(krb5_context context, krb5_const_principal search_for,
 
     *entry = NULL;
 
+    if (!request_for_us(context, search_for))
+        return KRB5_KDB_NOENTRY;
+
     check(krb5_unparse_name_flags(context, search_for,
                                   KRB5_PRINCIPAL_UNPARSE_NO_REALM,
                                   &search_name));
@@ -449,7 +473,8 @@ lookup_princ_by_cert(krb5_context context, const krb5_data *client_cert,
     cert_princ_name = k5memdup0(client_cert->data, client_cert->length, &ret);
     check(ret);
 
-    check(krb5_parse_name(context, cert_princ_name, princ));
+    check(krb5_parse_name_flags(context, cert_princ_name,
+                                KRB5_PRINCIPAL_PARSE_ENTERPRISE, princ));
     free(cert_princ_name);
 }
 
diff --git a/src/tests/gssapi/t_s4u.py b/src/tests/gssapi/t_s4u.py
index 1a395c3..e174727 100755
--- a/src/tests/gssapi/t_s4u.py
+++ b/src/tests/gssapi/t_s4u.py
@@ -163,11 +163,13 @@ testprincs = {'krbtgt/SREALM': {'keys': 'aes128-cts'},
 kdcconf1 = {'realms': {'$realm': {'database_module': 'test'}},
             'dbmodules': {'test': {'db_library': 'test',
                                    'princs': testprincs,
-                                   'alias': {'enterprise at abc': '@UREALM'}}}}
+                                   'alias': {'enterprise at abc': '@UREALM',
+                                             'user at UREALM': '@UREALM'}}}}
 kdcconf2 = {'realms': {'$realm': {'database_module': 'test'}},
             'dbmodules': {'test': {'db_library': 'test',
                                    'princs': testprincs,
                                    'alias': {'user at SREALM': '@SREALM',
+                                             'user at UREALM': 'user',
                                              'enterprise at abc': 'user'}}}}
 r1, r2 = cross_realms(2, xtgts=(),
                       args=({'realm': 'SREALM', 'kdc_conf': kdcconf1},