469 lines
12 KiB
C
469 lines
12 KiB
C
/*
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* Copyright (c) 2006 - 2007 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "kdc_locl.h"
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#include <hex.h>
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#include <rfc2459_asn1.h>
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#include <hx509.h>
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#ifdef KX509
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/*
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*
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*/
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krb5_error_code
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_kdc_try_kx509_request(void *ptr, size_t len, struct Kx509Request *req, size_t *size)
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{
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if (len < 4)
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return -1;
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if (memcmp("\x00\x00\x02\x00", ptr, 4) != 0)
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return -1;
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return decode_Kx509Request(((unsigned char *)ptr) + 4, len - 4, req, size);
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}
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/*
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*
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*/
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static const unsigned char version_2_0[4] = {0 , 0, 2, 0};
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static krb5_error_code
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verify_req_hash(krb5_context context,
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const Kx509Request *req,
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krb5_keyblock *key)
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{
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unsigned char digest[SHA_DIGEST_LENGTH];
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HMAC_CTX ctx;
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if (req->pk_hash.length != sizeof(digest)) {
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krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
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"pk-hash have wrong length: %lu",
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(unsigned long)req->pk_hash.length);
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return KRB5KDC_ERR_PREAUTH_FAILED;
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}
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HMAC_CTX_init(&ctx);
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HMAC_Init_ex(&ctx,
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key->keyvalue.data, key->keyvalue.length,
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EVP_sha1(), NULL);
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if (sizeof(digest) != HMAC_size(&ctx))
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krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509");
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HMAC_Update(&ctx, version_2_0, sizeof(version_2_0));
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HMAC_Update(&ctx, req->pk_key.data, req->pk_key.length);
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HMAC_Final(&ctx, digest, 0);
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HMAC_CTX_cleanup(&ctx);
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if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) {
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krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
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"pk-hash is not correct");
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return KRB5KDC_ERR_PREAUTH_FAILED;
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}
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return 0;
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}
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static krb5_error_code
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calculate_reply_hash(krb5_context context,
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krb5_keyblock *key,
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Kx509Response *rep)
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{
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krb5_error_code ret;
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HMAC_CTX ctx;
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HMAC_CTX_init(&ctx);
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HMAC_Init_ex(&ctx, key->keyvalue.data, key->keyvalue.length,
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EVP_sha1(), NULL);
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ret = krb5_data_alloc(rep->hash, HMAC_size(&ctx));
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if (ret) {
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HMAC_CTX_cleanup(&ctx);
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krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
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return ENOMEM;
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}
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HMAC_Update(&ctx, version_2_0, sizeof(version_2_0));
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if (rep->error_code) {
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int32_t t = *rep->error_code;
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do {
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unsigned char p = (t & 0xff);
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HMAC_Update(&ctx, &p, 1);
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t >>= 8;
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} while (t);
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}
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if (rep->certificate)
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HMAC_Update(&ctx, rep->certificate->data, rep->certificate->length);
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if (rep->e_text)
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HMAC_Update(&ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text));
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HMAC_Final(&ctx, rep->hash->data, 0);
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HMAC_CTX_cleanup(&ctx);
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return 0;
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}
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/*
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* Build a certifate for `principal´ that will expire at `endtime´.
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*/
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static krb5_error_code
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build_certificate(krb5_context context,
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krb5_kdc_configuration *config,
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const krb5_data *key,
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time_t endtime,
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krb5_principal principal,
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krb5_data *certificate)
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{
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hx509_ca_tbs tbs = NULL;
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hx509_env env = NULL;
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hx509_cert cert = NULL;
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hx509_cert signer = NULL;
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int ret;
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if (krb5_principal_get_comp_string(context, principal, 1) != NULL) {
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kdc_log(context, config, 0, "Principal is not a user");
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return EINVAL;
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}
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ret = hx509_env_add(context->hx509ctx, &env, "principal-name",
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krb5_principal_get_comp_string(context, principal, 0));
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if (ret)
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goto out;
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{
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hx509_certs certs;
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hx509_query *q;
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ret = hx509_certs_init(context->hx509ctx, config->kx509_ca, 0,
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NULL, &certs);
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if (ret) {
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kdc_log(context, config, 0, "Failed to load CA %s",
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config->kx509_ca);
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goto out;
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}
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ret = hx509_query_alloc(context->hx509ctx, &q);
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if (ret) {
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hx509_certs_free(&certs);
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goto out;
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}
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hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY);
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hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN);
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ret = hx509_certs_find(context->hx509ctx, certs, q, &signer);
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hx509_query_free(context->hx509ctx, q);
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hx509_certs_free(&certs);
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if (ret) {
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kdc_log(context, config, 0, "Failed to find a CA in %s",
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config->kx509_ca);
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goto out;
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}
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}
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ret = hx509_ca_tbs_init(context->hx509ctx, &tbs);
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if (ret)
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goto out;
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{
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SubjectPublicKeyInfo spki;
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heim_any any;
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memset(&spki, 0, sizeof(spki));
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spki.subjectPublicKey.data = key->data;
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spki.subjectPublicKey.length = key->length * 8;
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ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption,
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&spki.algorithm.algorithm);
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any.data = "\x05\x00";
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any.length = 2;
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spki.algorithm.parameters = &any;
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ret = hx509_ca_tbs_set_spki(context->hx509ctx, tbs, &spki);
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der_free_oid(&spki.algorithm.algorithm);
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if (ret)
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goto out;
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}
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{
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hx509_certs certs;
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hx509_cert template;
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ret = hx509_certs_init(context->hx509ctx, config->kx509_template, 0,
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NULL, &certs);
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if (ret) {
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kdc_log(context, config, 0, "Failed to load template %s",
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config->kx509_template);
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goto out;
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}
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ret = hx509_get_one_cert(context->hx509ctx, certs, &template);
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hx509_certs_free(&certs);
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if (ret) {
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kdc_log(context, config, 0, "Failed to find template in %s",
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config->kx509_template);
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goto out;
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}
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ret = hx509_ca_tbs_set_template(context->hx509ctx, tbs,
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HX509_CA_TEMPLATE_SUBJECT|
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HX509_CA_TEMPLATE_KU|
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HX509_CA_TEMPLATE_EKU,
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template);
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hx509_cert_free(template);
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if (ret)
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goto out;
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}
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hx509_ca_tbs_set_notAfter(context->hx509ctx, tbs, endtime);
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hx509_ca_tbs_subject_expand(context->hx509ctx, tbs, env);
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hx509_env_free(&env);
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ret = hx509_ca_sign(context->hx509ctx, tbs, signer, &cert);
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hx509_cert_free(signer);
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if (ret)
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goto out;
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hx509_ca_tbs_free(&tbs);
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ret = hx509_cert_binary(context->hx509ctx, cert, certificate);
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hx509_cert_free(cert);
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if (ret)
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goto out;
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return 0;
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out:
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if (env)
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hx509_env_free(&env);
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if (tbs)
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hx509_ca_tbs_free(&tbs);
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if (signer)
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hx509_cert_free(signer);
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krb5_set_error_message(context, ret, "cert creation failed");
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return ret;
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}
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/*
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*
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*/
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krb5_error_code
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_kdc_do_kx509(krb5_context context,
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krb5_kdc_configuration *config,
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const struct Kx509Request *req, krb5_data *reply,
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const char *from, struct sockaddr *addr)
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{
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krb5_error_code ret;
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krb5_ticket *ticket = NULL;
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krb5_flags ap_req_options;
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krb5_auth_context ac = NULL;
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krb5_keytab id = NULL;
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krb5_principal sprincipal = NULL, cprincipal = NULL;
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char *cname = NULL;
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Kx509Response rep;
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size_t size;
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krb5_keyblock *key = NULL;
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krb5_data_zero(reply);
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memset(&rep, 0, sizeof(rep));
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if(!config->enable_kx509) {
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kdc_log(context, config, 0,
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"Rejected kx509 request (disabled) from %s", from);
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return KRB5KDC_ERR_POLICY;
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}
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kdc_log(context, config, 0, "Kx509 request from %s", from);
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ret = krb5_kt_resolve(context, "HDB:", &id);
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if (ret) {
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kdc_log(context, config, 0, "Can't open database for digest");
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goto out;
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}
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ret = krb5_rd_req(context,
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&ac,
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&req->authenticator,
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NULL,
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id,
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&ap_req_options,
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&ticket);
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if (ret)
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goto out;
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ret = krb5_ticket_get_client(context, ticket, &cprincipal);
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if (ret)
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goto out;
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ret = krb5_unparse_name(context, cprincipal, &cname);
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if (ret)
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goto out;
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/* verify server principal */
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ret = krb5_sname_to_principal(context, NULL, "kca_service",
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KRB5_NT_UNKNOWN, &sprincipal);
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if (ret)
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goto out;
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{
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krb5_principal principal = NULL;
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ret = krb5_ticket_get_server(context, ticket, &principal);
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if (ret)
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goto out;
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ret = krb5_principal_compare(context, sprincipal, principal);
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krb5_free_principal(context, principal);
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if (ret != TRUE) {
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char *expected, *used;
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ret = krb5_unparse_name(context, sprincipal, &expected);
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if (ret)
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goto out;
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ret = krb5_unparse_name(context, principal, &used);
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if (ret) {
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krb5_xfree(expected);
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goto out;
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}
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ret = KRB5KDC_ERR_SERVER_NOMATCH;
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krb5_set_error_message(context, ret,
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"User %s used wrong Kx509 service "
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"principal, expected: %s, used %s",
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cname, expected, used);
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krb5_xfree(expected);
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krb5_xfree(used);
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goto out;
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}
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}
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ret = krb5_auth_con_getkey(context, ac, &key);
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if (ret == 0 && key == NULL)
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ret = KRB5KDC_ERR_NULL_KEY;
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if (ret) {
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krb5_set_error_message(context, ret, "Kx509 can't get session key");
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goto out;
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}
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ret = verify_req_hash(context, req, key);
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if (ret)
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goto out;
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/* Verify that the key is encoded RSA key */
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{
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RSAPublicKey key;
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size_t size;
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ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length,
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&key, &size);
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if (ret)
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goto out;
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free_RSAPublicKey(&key);
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if (size != req->pk_key.length) {
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ret = ASN1_EXTRA_DATA;
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goto out;
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}
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}
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ALLOC(rep.certificate);
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if (rep.certificate == NULL)
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goto out;
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krb5_data_zero(rep.certificate);
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ALLOC(rep.hash);
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if (rep.hash == NULL)
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goto out;
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krb5_data_zero(rep.hash);
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ret = build_certificate(context, config, &req->pk_key,
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krb5_ticket_get_endtime(context, ticket),
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cprincipal, rep.certificate);
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if (ret)
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goto out;
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ret = calculate_reply_hash(context, key, &rep);
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if (ret)
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goto out;
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/*
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* Encode reply, [ version | Kx509Response ]
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*/
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{
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krb5_data data;
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ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep,
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&size, ret);
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if (ret) {
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krb5_set_error_message(context, ret, "Failed to encode kx509 reply");
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goto out;
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}
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if (size != data.length)
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krb5_abortx(context, "ASN1 internal error");
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ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0));
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if (ret) {
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free(data.data);
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goto out;
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}
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memcpy(reply->data, version_2_0, sizeof(version_2_0));
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memcpy(((unsigned char *)reply->data) + sizeof(version_2_0),
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data.data, data.length);
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free(data.data);
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}
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kdc_log(context, config, 0, "Successful Kx509 request for %s", cname);
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out:
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if (ac)
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krb5_auth_con_free(context, ac);
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if (ret)
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krb5_warn(context, ret, "Kx509 request from %s failed", from);
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if (ticket)
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krb5_free_ticket(context, ticket);
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if (id)
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krb5_kt_close(context, id);
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if (sprincipal)
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krb5_free_principal(context, sprincipal);
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if (cprincipal)
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krb5_free_principal(context, cprincipal);
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if (key)
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krb5_free_keyblock (context, key);
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if (cname)
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free(cname);
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free_Kx509Response(&rep);
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return 0;
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}
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#endif /* KX509 */
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