Hide gak_fct interface and arguments in clpreauth

Remove the gak_fct, gak_data, salt, s2kparams, and as_key arguments
of krb5_clpreauth_process_fn and krb5_clpreauth_tryagain_fn.  To
replace them, add two callbacks: one which gets the AS key using the
previously selected etype-info2 information, and a second which lets
the module replace the AS key with one it has computed.

This changes limits module flexibility in a few ways.  Modules cannot
check whether the AS key was already obtained before asking for it,
and they cannot use the etype-info2 salt and s2kparams for purposes
other than getting the password-based AS key.  It is believed that
of existing preauth mechanisms, only SAM-2 preauth needs more
flexibility than the new interfaces provide, and as an internal legacy
mechanism it can cheat.  Future mechanisms should be okay since the
current IETF philosophy is that etype-info2 information should not be
used for other purposes.

ticket: 6976

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25351 dc483132-0cff-0310-8789-dd5450dbe970

1 files changed, 54 insertions, 42 deletions

diff --git a/src/lib/krb5/krb/preauth2.c b/src/lib/krb5/krb/preauth2.c
index f2ead9361..fd5c63536 100644
--- a/src/lib/krb5/krb/preauth2.c
+++ b/src/lib/krb5/krb/preauth2.c
@@ -387,10 +387,37 @@ fast_armor(krb5_context context, krb5_clpreauth_rock rock)
     return rock->fast_state->armor_key;
 }
 
+static krb5_error_code
+get_as_key(krb5_context context, krb5_clpreauth_rock rock,
+           krb5_keyblock **keyblock)
+{
+    krb5_error_code ret;
+
+    if (rock->as_key->length == 0) {
+        ret = (*rock->gak_fct)(context, rock->client, *rock->etype,
+                               rock->prompter, rock->prompter_data, rock->salt,
+                               rock->s2kparams, rock->as_key, *rock->gak_data);
+        if (ret)
+            return ret;
+    }
+    *keyblock = rock->as_key;
+    return 0;
+}
+
+static krb5_error_code
+set_as_key(krb5_context context, krb5_clpreauth_rock rock,
+           const krb5_keyblock *keyblock)
+{
+    krb5_free_keyblock_contents(context, rock->as_key);
+    return krb5_copy_keyblock_contents(context, keyblock, rock->as_key);
+}
+
 static struct krb5_clpreauth_callbacks_st callbacks = {
     1,
     get_etype,
-    fast_armor
+    fast_armor,
+    get_as_key,
+    set_as_key
 };
 
 /* Tweak the request body, for now adding any enctypes which the module claims
@@ -432,12 +459,7 @@ run_preauth_plugins(krb5_context kcontext,
                     krb5_pa_data *in_padata,
                     krb5_prompter_fct prompter,
                     void *prompter_data,
-                    krb5_clpreauth_get_as_key_fn gak_fct,
-                    krb5_data *salt,
-                    krb5_data *s2kparams,
-                    void *gak_data,
                     krb5_clpreauth_rock preauth_rock,
-                    krb5_keyblock *as_key,
                     krb5_pa_data ***out_pa_list,
                     int *out_pa_list_size,
                     int *module_ret,
@@ -481,9 +503,7 @@ run_preauth_plugins(krb5_context kcontext,
                                      &callbacks, preauth_rock,
                                      request, encoded_request_body,
                                      encoded_previous_request, in_padata,
-                                     prompter, prompter_data, gak_fct,
-                                     gak_data, salt, s2kparams, as_key,
-                                     &out_pa_data);
+                                     prompter, prompter_data, &out_pa_data);
         TRACE_PREAUTH_PROCESS(kcontext, module->name, module->pa_type,
                               module->flags, ret);
         /* Make note of the module's flags and status. */
@@ -1350,11 +1370,7 @@ krb5_do_preauth_tryagain(krb5_context kcontext,
                          krb5_pa_data **padata,
                          krb5_pa_data ***return_padata,
                          krb5_error *err_reply,
-                         krb5_data *salt, krb5_data *s2kparams,
-                         krb5_enctype *etype,
-                         krb5_keyblock *as_key,
                          krb5_prompter_fct prompter, void *prompter_data,
-                         krb5_gic_get_as_key_fct gak_fct, void *gak_data,
                          krb5_clpreauth_rock preauth_rock,
                          krb5_gic_opt_ext *opte)
 {
@@ -1396,8 +1412,6 @@ krb5_do_preauth_tryagain(krb5_context kcontext,
                                            padata[i],
                                            err_reply,
                                            prompter, prompter_data,
-                                           gak_fct, gak_data, salt, s2kparams,
-                                           as_key,
                                            &out_padata) == 0) {
                 if (out_padata != NULL) {
                     int k;
@@ -1415,17 +1429,12 @@ krb5_do_preauth_tryagain(krb5_context kcontext,
 }
 
 krb5_error_code KRB5_CALLCONV
-krb5_do_preauth(krb5_context context,
-                krb5_kdc_req *request,
+krb5_do_preauth(krb5_context context, krb5_kdc_req *request,
                 krb5_data *encoded_request_body,
                 krb5_data *encoded_previous_request,
                 krb5_pa_data **in_padata, krb5_pa_data ***out_padata,
-                krb5_data *salt, krb5_data *s2kparams,
-                krb5_enctype *etype,
-                krb5_keyblock *as_key,
                 krb5_prompter_fct prompter, void *prompter_data,
-                krb5_gic_get_as_key_fct gak_fct, void *gak_data,
-                krb5_clpreauth_rock preauth_rock, krb5_gic_opt_ext *opte)
+                krb5_clpreauth_rock rock, krb5_gic_opt_ext *opte)
 {
     unsigned int h;
     int i, j, out_pa_list_size;
@@ -1525,19 +1534,24 @@ krb5_do_preauth(krb5_context context,
                 }
                 scratch.data = (char *) etype_info[l]->salt;
                 scratch.length = etype_info[l]->length;
-                krb5_free_data_contents(context, salt);
+                krb5_free_data_contents(context, rock->salt);
                 if (scratch.length == KRB5_ETYPE_NO_SALT)
-                    salt->data = NULL;
-                else
-                    if ((ret = krb5int_copy_data_contents( context, &scratch, salt)) != 0)
+                    rock->salt->data = NULL;
+                else {
+                    ret = krb5int_copy_data_contents(context, &scratch,
+                                                     rock->salt);
+                    if (ret)
                         goto cleanup;
-                *etype = etype_info[l]->etype;
-                krb5_free_data_contents(context, s2kparams);
-                if ((ret = krb5int_copy_data_contents(context,
-                                                      &etype_info[l]->s2kparams,
-                                                      s2kparams)) != 0)
+                }
+                *rock->etype = etype_info[l]->etype;
+                krb5_free_data_contents(context, rock->s2kparams);
+                ret = krb5int_copy_data_contents(context,
+                                                 &etype_info[l]->s2kparams,
+                                                 rock->s2kparams);
+                if (ret)
                     goto cleanup;
-                TRACE_PREAUTH_ETYPE_INFO(context, *etype, salt, s2kparams);
+                TRACE_PREAUTH_ETYPE_INFO(context, *rock->etype, rock->salt,
+                                         rock->s2kparams);
                 break;
             }
             case KRB5_PADATA_PW_SALT:
@@ -1558,11 +1572,13 @@ krb5_do_preauth(krb5_context context,
 #endif
                         out_pa = NULL;
 
-                        if ((ret = ((*pa_types[j].fct)(context, request,
-                                                       in_padata[i], &out_pa,
-                                                       salt, s2kparams, etype, as_key,
-                                                       prompter, prompter_data,
-                                                       gak_fct, gak_data)))) {
+                        ret = pa_types[j].fct(context, request, in_padata[i],
+                                              &out_pa, rock->salt,
+                                              rock->s2kparams, rock->etype,
+                                              rock->as_key, prompter,
+                                              prompter_data, *rock->gak_fct,
+                                              *rock->gak_data);
+                        if (ret) {
                             if (paorder[h] == PA_INFO) {
                                 TRACE_PREAUTH_INFO_FAIL(context,
                                                         in_padata[i]->pa_type,
@@ -1601,11 +1617,7 @@ krb5_do_preauth(krb5_context context,
                                               in_padata[i],
                                               prompter,
                                               prompter_data,
-                                              gak_fct,
-                                              salt, s2kparams,
-                                              gak_data,
-                                              preauth_rock,
-                                              as_key,
+                                              rock,
                                               &out_pa_list,
                                               &out_pa_list_size,
                                               &module_ret,