--- /dev/null
+/*
+ * plugins/preauth/encrypted_challenge/encrypted_challenge.c
+ *
+ * Copyright (C) 2009 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Export of this software from the United States of America may
+ * require a specific license from the United States Government.
+ * It is the responsibility of any person or organization contemplating
+ * export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission. Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is" without express
+ * or implied warranty.
+ *
+ *
+ *
+ * Implement EncryptedChallenge fast factor from draft-ietf-krb-wg-preauth-framework
+ */
+
+#include <k5-int.h>
+#include "../fast_factor.h"
+
+#include <krb5/preauth_plugin.h>
+
+static int preauth_flags
+(krb5_context context, krb5_preauthtype pa_type)
+{
+ return PA_REAL;
+}
+
+static krb5_error_code process_preauth
+(krb5_context context,
+ void *plugin_context,
+ void *request_context,
+ krb5_get_init_creds_opt *opt,
+ preauth_get_client_data_proc get_data_proc,
+ struct _krb5_preauth_client_rock *rock,
+ krb5_kdc_req *request,
+ krb5_data *encoded_request_body,
+ krb5_data *encoded_previous_request,
+ krb5_pa_data *padata,
+ krb5_prompter_fct prompter,
+ void *prompter_data,
+ preauth_get_as_key_proc gak_fct,
+ void *gak_data,
+ krb5_data *salt,
+ krb5_data *s2kparams,
+ krb5_keyblock *as_key,
+ krb5_pa_data ***out_padata)
+{
+ krb5_error_code retval = 0;
+ krb5_enctype enctype = 0;
+ krb5_keyblock *challenge_key = NULL, *armor_key = NULL;
+ krb5_data *etype_data = NULL;
+ krb5int_access kaccess;
+
+ if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+ return 0;
+ retval = fast_get_armor_key(context, get_data_proc, rock, &armor_key);
+ if (retval || armor_key == NULL)
+ return 0;
+ retval = get_data_proc(context, rock, krb5plugin_preauth_client_get_etype, &etype_data);
+ if (retval == 0) {
+ enctype = *((krb5_enctype *)etype_data->data);
+ if (as_key->length == 0 ||as_key->enctype != enctype)
+ retval = gak_fct(context, request->client,
+ enctype, prompter, prompter_data,
+ salt, s2kparams,
+ as_key, gak_data);
+ }
+ if (padata->length) {
+ krb5_enc_data *enc = NULL;
+ krb5_data scratch;
+ scratch.length = padata->length;
+ scratch.data = (char *) padata->contents;
+ if (retval == 0)
+ retval = krb5_c_fx_cf2_simple(context,armor_key, "kdcchallengearmor",
+ as_key, "challengelongterm", &challenge_key);
+ if (retval == 0)
+ retval =kaccess.decode_enc_data(&scratch, &enc);
+ scratch.data = NULL;
+ if (retval == 0) {
+ scratch.data = malloc(enc->ciphertext.length);
+ scratch.length = enc->ciphertext.length;
+ if (scratch.data == NULL)
+ retval = ENOMEM;
+ }
+ if (retval == 0)
+ retval = krb5_c_decrypt(context, challenge_key,
+ KRB5_KEYUSAGE_ENC_CHALLENGE_KDC, NULL,
+ enc, &scratch);
+/*Per draft 11 of the preauth framework, the client MAY but
+ * is not required to actually check the timestamp from the KDC other than
+ * to confirm it decrypts. This code does not perform that check.
+ */
+ if (scratch.data)
+ krb5_free_data_contents(context, &scratch);
+ if (retval == 0)
+ fast_set_kdc_verified(context, get_data_proc, rock);
+ if (enc)
+ kaccess.free_enc_data(context, enc);
+ } else { /*No padata; we send*/
+ krb5_enc_data enc;
+ krb5_pa_data *pa = NULL;
+ krb5_pa_data **pa_array = NULL;
+ krb5_data *encoded_ts = NULL;
+ krb5_pa_enc_ts ts;
+ if (retval == 0)
+ retval = krb5_us_timeofday(context, &ts.patimestamp, &ts.pausec);
+ if (retval == 0)
+ retval = kaccess.encode_enc_ts(&ts, &encoded_ts);
+ if (retval == 0)
+ retval = krb5_c_fx_cf2_simple(context,
+ armor_key, "clientchallengearmor",
+ as_key, "challengelongterm",
+ &challenge_key);
+ if (retval == 0)
+ retval = kaccess.encrypt_helper(context, challenge_key,
+ KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
+ encoded_ts, &enc);
+ if (encoded_ts)
+ krb5_free_data(context, encoded_ts);
+ encoded_ts = NULL;
+ if (retval == 0) {
+ retval = kaccess.encode_enc_data(&enc, &encoded_ts);
+ krb5_free_data_contents(context, &enc.ciphertext);
+ }
+ if (retval == 0) {
+ pa = calloc(1, sizeof(krb5_pa_data));
+ if (pa == NULL)
+ retval = ENOMEM;
+ }
+ if (retval == 0) {
+ pa_array = calloc(2, sizeof(krb5_pa_data *));
+ if (pa_array == NULL)
+ retval = ENOMEM;
+ }
+ if (retval == 0) {
+ pa->length = encoded_ts->length;
+ pa->contents = (unsigned char *) encoded_ts->data;
+ pa->pa_type = KRB5_PADATA_ENCRYPTED_CHALLENGE;
+ free(encoded_ts);
+ encoded_ts = NULL;
+ pa_array[0] = pa;
+ pa = NULL;
+ *out_padata = pa_array;
+ pa_array = NULL;
+ }
+ if (pa)
+ free(pa);
+ if (encoded_ts)
+ krb5_free_data(context, encoded_ts);
+ if (pa_array)
+ free(pa_array);
+ }
+ if (challenge_key)
+ krb5_free_keyblock(context, challenge_key);
+ if (armor_key)
+ krb5_free_keyblock(context, armor_key);
+ if (etype_data != NULL)
+ get_data_proc(context, rock, krb5plugin_preauth_client_free_etype,
+ &etype_data);
+ return retval;
+}
+
+
+
+
+static krb5_error_code kdc_include_padata
+(krb5_context context,
+ krb5_kdc_req *request,
+ struct _krb5_db_entry_new *client,
+ struct _krb5_db_entry_new *server,
+ preauth_get_entry_data_proc get_entry_proc,
+ void *pa_module_context,
+ krb5_pa_data *data)
+{
+ krb5_error_code retval = 0;
+ krb5_keyblock *armor_key = NULL;
+ retval = fast_kdc_get_armor_key(context, get_entry_proc, request, client, &armor_key);
+ if (retval)
+ return retval;
+ if (armor_key == 0)
+ return ENOENT;
+ krb5_free_keyblock(context, armor_key);
+ return 0;
+}
+
+static krb5_error_code kdc_verify_preauth
+(krb5_context context,
+ struct _krb5_db_entry_new *client,
+ krb5_data *req_pkt,
+ krb5_kdc_req *request,
+ krb5_enc_tkt_part *enc_tkt_reply,
+ krb5_pa_data *data,
+ preauth_get_entry_data_proc get_entry_proc,
+ void *pa_module_context,
+ void **pa_request_context,
+ krb5_data **e_data,
+ krb5_authdata ***authz_data)
+{
+ krb5_error_code retval = 0;
+ krb5_timestamp now;
+ krb5_enc_data *enc = NULL;
+ krb5_data scratch, plain;
+ krb5_keyblock *armor_key = NULL;
+ krb5_pa_enc_ts *ts = NULL;
+ krb5int_access kaccess;
+ krb5_keyblock *client_keys = NULL;
+ krb5_data *client_data = NULL;
+ krb5_keyblock *challenge_key = NULL;
+ int i;
+
+ plain.data = NULL;
+ if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+ return 0;
+
+ retval = fast_kdc_get_armor_key(context, get_entry_proc, request, client, &armor_key);
+ if (retval == 0 &&armor_key == NULL) {
+ retval = ENOENT;
+ krb5_set_error_message(context, ENOENT, "Encrypted Challenge used outside of FAST tunnel");
+ }
+ scratch.data = (char *) data->contents;
+ scratch.length = data->length;
+ if (retval == 0)
+ retval = kaccess.decode_enc_data(&scratch, &enc);
+ if (retval == 0) {
+ plain.data = malloc(enc->ciphertext.length);
+ plain.length = enc->ciphertext.length;
+ if (plain.data == NULL)
+ retval = ENOMEM;
+ }
+ if (retval == 0)
+ retval = get_entry_proc(context, request, client,
+ krb5plugin_preauth_keys, &client_data);
+ if (retval == 0) {
+ client_keys = (krb5_keyblock *) client_data->data;
+ for (i = 0; client_keys[i].enctype&& (retval == 0); i++ ) {
+ retval = krb5_c_fx_cf2_simple(context,
+ armor_key, "clientchallengearmor",
+ &client_keys[i], "challengelongterm",
+ &challenge_key);
+ if (retval == 0)
+ retval = krb5_c_decrypt(context, challenge_key,
+ KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
+ NULL, enc, &plain);
+ if (challenge_key)
+ krb5_free_keyblock(context, challenge_key);
+ challenge_key = NULL;
+ if (retval == 0)
+ break;
+ /*We failed to decrypt. Try next key*/
+ retval = 0;
+ krb5_free_keyblock_contents(context, &client_keys[i]);
+ }
+ if (client_keys[i].enctype == 0) {
+ retval = KRB5KDC_ERR_PREAUTH_FAILED;
+ krb5_set_error_message(context, retval, "Incorrect password in encrypted challenge");
+ } else { /*not run out of keys*/
+ int j;
+ assert (retval == 0);
+ for (j = i+1; client_keys[j].enctype; j++)
+ krb5_free_keyblock_contents(context, &client_keys[j]);
+ }
+
+ }
+ if (retval == 0)
+ retval = kaccess.decode_enc_ts(&plain, &ts);
+ if (retval == 0)
+ retval = krb5_timeofday(context, &now);
+ if (retval == 0) {
+ if (labs(now-ts->patimestamp) < context->clockskew) {
+ enc_tkt_reply->flags |= TKT_FLG_PRE_AUTH;
+/*If this fails, we won't generate a reply to the client. That may
+ * cause the client to fail, but at this point the KDC has considered
+ this a success, so the return value is ignored. */
+ fast_kdc_replace_reply_key(context, get_entry_proc, request);
+ krb5_c_fx_cf2_simple(context, armor_key, "kdcchallengearmor",
+ &client_keys[i], "challengelongterm",
+ (krb5_keyblock **) pa_request_context);
+ } else { /*skew*/
+ retval = KRB5KRB_AP_ERR_SKEW;
+ }
+ }
+ if (client_keys) {
+ if (client_keys[i].enctype)
+ krb5_free_keyblock_contents(context, &client_keys[i]);
+ krb5_free_data(context, client_data);
+ }
+ if (armor_key)
+ krb5_free_keyblock(context, armor_key);
+ if (challenge_key)
+ krb5_free_keyblock(context, challenge_key);
+ if (plain.data)
+ free(plain.data);
+ if (enc)
+ kaccess.free_enc_data(context, enc);
+ if (ts)
+ kaccess.free_enc_ts(context, ts);
+ return retval;
+}
+
+static krb5_error_code kdc_return_preauth
+(krb5_context context,
+ krb5_pa_data * padata,
+ struct _krb5_db_entry_new *client,
+ krb5_data *req_pkt,
+ krb5_kdc_req *request,
+ krb5_kdc_rep *reply,
+ struct _krb5_key_data *client_keys,
+ krb5_keyblock *encrypting_key,
+ krb5_pa_data **send_pa,
+ preauth_get_entry_data_proc get_entry_proc,
+ void *pa_module_context,
+ void **pa_request_context)
+{
+ krb5_error_code retval = 0;
+ krb5_keyblock *challenge_key = *pa_request_context;
+ krb5_pa_enc_ts ts;
+ krb5_data *plain = NULL;
+ krb5_enc_data enc;
+ krb5_data *encoded = NULL;
+ krb5_pa_data *pa = NULL;
+ krb5int_access kaccess;
+
+ if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+ return 0;
+ if (challenge_key == NULL)
+ return 0;
+ * pa_request_context = NULL; /*this function will free the
+ * challenge key*/
+ retval = krb5_us_timeofday(context, &ts.patimestamp, &ts.pausec);
+ if (retval == 0)
+ retval = kaccess.encode_enc_ts(&ts, &plain);
+ if (retval == 0)
+ retval = kaccess.encrypt_helper(context, challenge_key,
+ KRB5_KEYUSAGE_ENC_CHALLENGE_KDC,
+ plain, &enc);
+ if (retval == 0)
+ retval = kaccess.encode_enc_data(&enc, &encoded);
+ if (retval == 0) {
+ pa = calloc(1, sizeof(krb5_pa_data));
+ if (pa == NULL)
+ retval = ENOMEM;
+ }
+ if (retval == 0) {
+ pa->pa_type = KRB5_PADATA_ENCRYPTED_CHALLENGE;
+ pa->contents = (unsigned char *) encoded->data;
+ pa->length = encoded->length;
+ encoded->data = NULL;
+ *send_pa = pa;
+ pa = NULL;
+ }
+ if (challenge_key)
+ krb5_free_keyblock(context, challenge_key);
+ if (encoded)
+ krb5_free_data(context, encoded);
+ if (plain)
+ krb5_free_data(context, plain);
+ if (enc.ciphertext.data)
+ krb5_free_data_contents(context, &enc.ciphertext);
+ return retval;
+}
+
+static int kdc_preauth_flags
+(krb5_context context, krb5_preauthtype patype)
+{
+ return 0;
+}
+
+krb5_preauthtype supported_pa_types[] = {
+ KRB5_PADATA_ENCRYPTED_CHALLENGE, 0};
+
+struct krb5plugin_preauth_server_ftable_v1 preauthentication_server_1 = {
+ "Encrypted challenge",
+ &supported_pa_types[0],
+NULL,
+NULL,
+kdc_preauth_flags,
+ kdc_include_padata,
+ kdc_verify_preauth,
+ kdc_return_preauth,
+NULL
+};
+
+struct krb5plugin_preauth_client_ftable_v1 preauthentication_client_1 = {
+ "Encrypted Challenge", /* name */
+ &supported_pa_types[0], /* pa_type_list */
+ NULL, /* enctype_list */
+ NULL, /* plugin init function */
+ NULL, /* plugin fini function */
+ preauth_flags, /* get flags function */
+ NULL, /* request init function */
+ NULL, /* request fini function */
+ process_preauth, /* process function */
+ NULL, /* try_again function */
+NULL /* get init creds opt function */
+};
projects / thirdparty / krb5.git / commitdiff
