Implement restrict_anonymous_to_tgt realm flag

Implement a new realm flag to reject ticket requests from anonymous
principals to any principal other than the local TGT.  Allows FAST to
be deployed using anonymous tickets as armor in realms where the set
of authenticatable users must be constrained.

ticket: 6829
target_version: 1.9
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24547 dc483132-0cff-0310-8789-dd5450dbe970

9 files changed, 71 insertions, 7 deletions

diff --git a/src/include/adm.h b/src/include/adm.h
index 68f3c7a897..c23cd89e34 100644
--- a/src/include/adm.h
+++ b/src/include/adm.h
@@ -210,6 +210,7 @@ typedef struct __krb5_realm_params {
     krb5_flags          realm_flags;
     krb5_key_salt_tuple *realm_keysalts;
     unsigned int        realm_reject_bad_transit:1;
+    unsigned int        realm_restrict_anon:1;
     unsigned int        realm_kadmind_port_valid:1;
     unsigned int        realm_enctype_valid:1;
     unsigned int        realm_max_life_valid:1;
@@ -217,6 +218,7 @@ typedef struct __krb5_realm_params {
     unsigned int        realm_expiration_valid:1;
     unsigned int        realm_flags_valid:1;
     unsigned int        realm_reject_bad_transit_valid:1;
+    unsigned int        realm_restrict_anon_valid:1;
     krb5_int32          realm_num_keysalts;
 } krb5_realm_params;
 #endif  /* KRB5_ADM_H__ */
diff --git a/src/include/k5-int.h b/src/include/k5-int.h
index 9a81d3bbcc..ac46b46006 100644
--- a/src/include/k5-int.h
+++ b/src/include/k5-int.h
@@ -263,6 +263,7 @@ typedef INT64_TYPE krb5_int64;
 #define KRB5_CONF_REALM_TRY_DOMAINS           "realm_try_domains"
 #define KRB5_CONF_REJECT_BAD_TRANSIT          "reject_bad_transit"
 #define KRB5_CONF_RENEW_LIFETIME              "renew_lifetime"
+#define KRB5_CONF_RESTRICT_ANONYMOUS_TO_TGT   "restrict_anonymous_to_tgt"
 #define KRB5_CONF_SAFE_CHECKSUM_TYPE          "safe_checksum_type"
 #define KRB5_CONF_SUPPORTED_ENCTYPES          "supported_enctypes"
 #define KRB5_CONF_TICKET_LIFETIME             "ticket_lifetime"
diff --git a/src/kdc/extern.h b/src/kdc/extern.h
index 24bad20a50..236e5ccd9c 100644
--- a/src/kdc/extern.h
+++ b/src/kdc/extern.h
@@ -74,6 +74,7 @@ typedef struct __kdc_realm_data {
     krb5_deltat         realm_maxlife;  /* Maximum ticket life for realm    */
     krb5_deltat         realm_maxrlife; /* Maximum renewable life for realm */
     krb5_boolean        realm_reject_bad_transit; /* Accept unverifiable transited_realm ? */
+    krb5_boolean        realm_restrict_anon;  /* Anon to local TGT only */
 } kdc_realm_t;
 
 extern kdc_realm_t      **kdc_realmlist;
@@ -95,6 +96,7 @@ kdc_realm_t *find_realm_data (char *, krb5_ui_4);
 #define master_princ                    kdc_active_realm->realm_mprinc
 #define tgs_server                      kdc_active_realm->realm_tgsprinc
 #define reject_bad_transit              kdc_active_realm->realm_reject_bad_transit
+#define restrict_anon                   kdc_active_realm->realm_restrict_anon
 
 /* various externs for KDC */
 extern krb5_data        empty_string;   /* an empty string */
diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
index 691ece06c9..62fea6fdb6 100644
--- a/src/kdc/kdc_util.c
+++ b/src/kdc/kdc_util.c
@@ -838,6 +838,21 @@ errcode_to_protocol(krb5_error_code code)
     return (protcode >= 0 && protcode <= 128) ? protcode : KRB_ERR_GENERIC;
 }
 
+/* Return -1 if the AS or TGS request is disallowed due to KDC policy on
+ * anonymous tickets. */
+static int
+check_anon(krb5_context context, krb5_principal client, krb5_principal server)
+{
+    /* If restrict_anon is set, reject requests from anonymous to principals
+     * other than the local TGT. */
+    if (restrict_anon &&
+        krb5_principal_compare_any_realm(context, client,
+                                         krb5_anonymous_principal()) &&
+        !krb5_principal_compare(context, server, tgs_server))
+        return -1;
+    return 0;
+}
+
 /*
  * Routines that validate a AS request; checks a lot of things.  :-)
  *
@@ -957,6 +972,11 @@ validate_as_request(register krb5_kdc_req *request, krb5_db_entry client,
         return(KDC_ERR_MUST_USE_USER2USER);
     }
 
+    if (check_anon(kdc_context, request->client, request->server) != 0) {
+        *status = "ANONYMOUS NOT ALLOWED";
+        return(KDC_ERR_POLICY);
+    }
+
     /* Perform KDB module policy checks. */
     ret = krb5_db_check_policy_as(kdc_context, request, &client, &server,
                                   kdc_time, status, e_data);
@@ -1379,6 +1399,12 @@ validate_tgs_request(register krb5_kdc_req *request, krb5_db_entry server,
         return KRB_ERR_GENERIC;
     }
 
+    if (check_anon(kdc_context, ticket->enc_part2->client,
+                   request->server) != 0) {
+        *status = "ANONYMOUS NOT ALLOWED";
+        return(KDC_ERR_POLICY);
+    }
+
     /* Perform KDB module policy checks. */
     ret = krb5_db_check_policy_tgs(kdc_context, request, &server,
                                    ticket, status, e_data);
diff --git a/src/kdc/main.c b/src/kdc/main.c
index 5b90bd5926..57cd226fb0 100644
--- a/src/kdc/main.c
+++ b/src/kdc/main.c
@@ -279,8 +279,8 @@ handle_referral_params(krb5_realm_params *rparams,
 static krb5_error_code
 init_realm(kdc_realm_t *rdp, char *realm, char *def_mpname,
            krb5_enctype def_enctype, char *def_udp_ports, char *def_tcp_ports,
-           krb5_boolean def_manual, char **db_args, char *no_refrls,
-           char *host_based_srvcs)
+           krb5_boolean def_manual, krb5_boolean def_restrict_anon,
+           char **db_args, char *no_refrls, char *host_based_srvcs)
 {
     krb5_error_code     kret;
     krb5_boolean        manual;
@@ -356,6 +356,11 @@ init_realm(kdc_realm_t *rdp, char *realm, char *def_mpname,
     } else
         manual = def_manual;
 
+    if (rparams && rparams->realm_restrict_anon_valid)
+        rdp->realm_restrict_anon = rparams->realm_restrict_anon;
+    else
+        rdp->realm_restrict_anon = def_restrict_anon;
+
     /* Handle master key type */
     if (rparams && rparams->realm_enctype_valid)
         rdp->realm_mkey.enctype = (krb5_enctype) rparams->realm_enctype;
@@ -655,6 +660,7 @@ initialize_realms(krb5_context kcontext, int argc, char **argv)
     krb5_enctype        menctype = ENCTYPE_UNKNOWN;
     kdc_realm_t         *rdatap = NULL;
     krb5_boolean        manual = FALSE;
+    krb5_boolean        def_restrict_anon;
     char                *default_udp_ports = 0;
     char                *default_tcp_ports = 0;
     krb5_pointer        aprof;
@@ -678,6 +684,9 @@ initialize_realms(krb5_context kcontext, int argc, char **argv)
         hierarchy[1] = KRB5_CONF_MAX_DGRAM_REPLY_SIZE;
         if (krb5_aprof_get_int32(aprof, hierarchy, TRUE, &max_dgram_reply_size))
             max_dgram_reply_size = MAX_DGRAM_SIZE;
+        hierarchy[1] = KRB5_CONF_RESTRICT_ANONYMOUS_TO_TGT;
+        if (krb5_aprof_get_boolean(aprof, hierarchy, TRUE, &def_restrict_anon))
+            def_restrict_anon = FALSE;
         hierarchy[1] = KRB5_CONF_NO_HOST_REFERRAL;
         if (krb5_aprof_get_string_all(aprof, hierarchy, &no_refrls))
             no_refrls = 0;
@@ -736,7 +745,8 @@ initialize_realms(krb5_context kcontext, int argc, char **argv)
                 if ((rdatap = (kdc_realm_t *) malloc(sizeof(kdc_realm_t)))) {
                     if ((retval = init_realm(rdatap, optarg, mkey_name,
                                              menctype, default_udp_ports,
-                                             default_tcp_ports, manual, db_args,
+                                             default_tcp_ports, manual,
+                                             def_restrict_anon, db_args,
                                              no_refrls, host_based_srvcs))) {
                         fprintf(stderr,
                                 "%s: cannot initialize realm %s - see log file for details\n",
@@ -848,8 +858,8 @@ initialize_realms(krb5_context kcontext, int argc, char **argv)
         if ((rdatap = (kdc_realm_t *) malloc(sizeof(kdc_realm_t)))) {
             if ((retval = init_realm(rdatap, lrealm, mkey_name, menctype,
                                      default_udp_ports, default_tcp_ports,
-                                     manual, db_args, no_refrls,
-                                     host_based_srvcs))) {
+                                     manual, def_restrict_anon, db_args,
+                                     no_refrls, host_based_srvcs))) {
                 fprintf(stderr,"%s: cannot initialize realm %s - see log file for details\n",
                         argv[0], lrealm);
                 exit(1);
diff --git a/src/lib/kadm5/admin.h b/src/lib/kadm5/admin.h
index 99837033be..8b59c6b5bb 100644
--- a/src/lib/kadm5/admin.h
+++ b/src/lib/kadm5/admin.h
@@ -291,6 +291,7 @@ typedef struct __krb5_realm_params {
     krb5_flags          realm_flags;
     krb5_key_salt_tuple *realm_keysalts;
     unsigned int        realm_reject_bad_transit:1;
+    unsigned int        realm_restrict_anon:1;
     unsigned int        realm_kadmind_port_valid:1;
     unsigned int        realm_enctype_valid:1;
     unsigned int        realm_max_life_valid:1;
@@ -298,6 +299,7 @@ typedef struct __krb5_realm_params {
     unsigned int        realm_expiration_valid:1;
     unsigned int        realm_flags_valid:1;
     unsigned int        realm_reject_bad_transit_valid:1;
+    unsigned int        realm_restrict_anon_valid:1;
     krb5_int32          realm_num_keysalts;
 } krb5_realm_params;
 
diff --git a/src/lib/kadm5/alt_prof.c b/src/lib/kadm5/alt_prof.c
index 6a79655126..cdd732113a 100644
--- a/src/lib/kadm5/alt_prof.c
+++ b/src/lib/kadm5/alt_prof.c
@@ -1058,6 +1058,12 @@ krb5_read_realm_params(kcontext, realm, rparamp)
         rparams->realm_reject_bad_transit_valid = 1;
     }
 
+    hierarchy[2] = KRB5_CONF_RESTRICT_ANONYMOUS_TO_TGT;
+    if (!krb5_aprof_get_boolean(aprofile, hierarchy, TRUE, &bvalue)) {
+        rparams->realm_restrict_anon = bvalue;
+        rparams->realm_restrict_anon_valid = 1;
+    }
+
     hierarchy[2] = KRB5_CONF_NO_HOST_REFERRAL;
     if (!krb5_aprof_get_string_all(aprofile, hierarchy, &no_refrls))
         rparams->realm_no_host_referral = no_refrls;
diff --git a/src/tests/t_anonpkinit.py b/src/tests/t_anonpkinit.py
index 0149a671b1..ddb96919b4 100644
--- a/src/tests/t_anonpkinit.py
+++ b/src/tests/t_anonpkinit.py
@@ -25,10 +25,23 @@ pkinit_krb5_conf = {
     }
 }
 
-realm = K5Realm(krb5_conf=pkinit_krb5_conf, create_user=False,
-                create_host=False)
+restrictive_kdc_conf = {
+    'all': { 'realms' : { '$realm' : {
+                'restrict_anonymous_to_tgt' : 'true' } } } }
+
+# In the basic test, anonymous is not restricted, so kvno should succeed.
+realm = K5Realm(krb5_conf=pkinit_krb5_conf, create_user=False)
 realm.addprinc('WELLKNOWN/ANONYMOUS')
 realm.kinit('@%s' % realm.realm, flags=['-n'])
 realm.klist('WELLKNOWN/ANONYMOUS@WELLKNOWN:ANONYMOUS')
+realm.run_as_client([kvno, realm.host_princ])
+realm.stop()
+
+# Now try again with anonymous restricted; kvno should fail.
+realm = K5Realm(krb5_conf=pkinit_krb5_conf, kdc_conf=restrictive_kdc_conf,
+                create_user=False)
+realm.addprinc('WELLKNOWN/ANONYMOUS')
+realm.kinit('@%s' % realm.realm, flags=['-n'])
+realm.run_as_client([kvno, realm.host_princ], expected_code=1)
 
 success('Anonymous PKINIT.')
diff --git a/src/util/k5test.py b/src/util/k5test.py
index a710eee3ae..a032d78b5b 100644
--- a/src/util/k5test.py
+++ b/src/util/k5test.py
@@ -181,6 +181,7 @@ Scripts may use the following functions and variables:
   - ktutil
   - kinit
   - klist
+  - kvno
   - kdestroy
   - kpasswd
   - t_inetd
@@ -1054,6 +1055,7 @@ kdb5_util = os.path.join(buildtop, 'kadmin', 'dbutil', 'kdb5_util')
 ktutil = os.path.join(buildtop, 'kadmin', 'ktutil', 'ktutil')
 kinit = os.path.join(buildtop, 'clients', 'kinit', 'kinit')
 klist = os.path.join(buildtop, 'clients', 'klist', 'klist')
+kvno = os.path.join(buildtop, 'clients', 'kvno', 'kvno')
 kdestroy = os.path.join(buildtop, 'clients', 'kdestroy', 'kdestroy')
 kpasswd = os.path.join(buildtop, 'clients', 'kpasswd', 'kpasswd')
 t_inetd = os.path.join(buildtop, 'tests', 'dejagnu', 't_inetd')