/* $NetBSD: kx509.c,v 1.3 2018/02/05 16:00:52 christos Exp $ */
/*
* Copyright (c) 2006 - 2007 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "kdc_locl.h"
#include <krb5/hex.h>
#include <krb5/rfc2459_asn1.h>
#include <krb5/hx509.h>
#ifdef KX509
/*
*
*/
krb5_error_code
_kdc_try_kx509_request(void *ptr, size_t len, struct Kx509Request *req, size_t *size)
{
if (len < 4)
return -1;
if (memcmp("\x00\x00\x02\x00", ptr, 4) != 0)
return -1;
return decode_Kx509Request(((unsigned char *)ptr) + 4, len - 4, req, size);
}
/*
*
*/
static const unsigned char version_2_0[4] = {0 , 0, 2, 0};
static krb5_error_code
verify_req_hash(krb5_context context,
const Kx509Request *req,
krb5_keyblock *key)
{
unsigned char digest[SHA_DIGEST_LENGTH];
HMAC_CTX *ctx;
if (req->pk_hash.length != sizeof(digest)) {
krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
"pk-hash have wrong length: %lu",
(unsigned long)req->pk_hash.length);
return KRB5KDC_ERR_PREAUTH_FAILED;
}
#if OPENSSL_VERSION_NUMBER < 0x10100000UL
HMAC_CTX ctxs;
ctx = &ctxs;
HMAC_CTX_init(ctx);
#else
ctx = HMAC_CTX_new();
#endif
HMAC_Init_ex(ctx,
key->keyvalue.data, key->keyvalue.length,
EVP_sha1(), NULL);
if (sizeof(digest) != HMAC_size(ctx))
krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509");
HMAC_Update(ctx, version_2_0, sizeof(version_2_0));
HMAC_Update(ctx, req->pk_key.data, req->pk_key.length);
HMAC_Final(ctx, digest, 0);
#if OPENSSL_VERSION_NUMBER < 0x10100000UL
HMAC_CTX_cleanup(ctx);
#else
HMAC_CTX_free(ctx);
#endif
if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) {
krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
"pk-hash is not correct");
return KRB5KDC_ERR_PREAUTH_FAILED;
}
return 0;
}
static krb5_error_code
calculate_reply_hash(krb5_context context,
krb5_keyblock *key,
Kx509Response *rep)
{
krb5_error_code ret;
HMAC_CTX *ctx;
#if OPENSSL_VERSION_NUMBER < 0x10100000UL
HMAC_CTX ctxs;
ctx = &ctxs;
HMAC_CTX_init(ctx);
#else
ctx = HMAC_CTX_new();
#endif
HMAC_Init_ex(ctx, key->keyvalue.data, key->keyvalue.length,
EVP_sha1(), NULL);
ret = krb5_data_alloc(rep->hash, HMAC_size(ctx));
if (ret) {
#if OPENSSL_VERSION_NUMBER < 0x10100000UL
HMAC_CTX_cleanup(ctx);
#else
HMAC_CTX_free(ctx);
#endif
krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
return ENOMEM;
}
HMAC_Update(ctx, version_2_0, sizeof(version_2_0));
if (rep->error_code) {
int32_t t = *rep->error_code;
do {
unsigned char p = (t & 0xff);
HMAC_Update(ctx, &p, 1);
t >>= 8;
} while (t);
}
if (rep->certificate)
HMAC_Update(ctx, rep->certificate->data, rep->certificate->length);
if (rep->e_text)
HMAC_Update(ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text));
HMAC_Final(ctx, rep->hash->data, 0);
#if OPENSSL_VERSION_NUMBER < 0x10100000UL
HMAC_CTX_cleanup(ctx);
#else
HMAC_CTX_free(ctx);
#endif
return 0;
}
/*
* Build a certifate for `principal´ that will expire at `endtime´.
*/
static krb5_error_code
build_certificate(krb5_context context,
krb5_kdc_configuration *config,
const krb5_data *key,
time_t endtime,
krb5_principal principal,
krb5_data *certificate)
{
char *name = NULL;
const char *kx509_ca;
hx509_ca_tbs tbs = NULL;
hx509_env env = NULL;
hx509_cert cert = NULL;
hx509_cert signer = NULL;
krb5_boolean def_bool;
int ret;
ret = krb5_unparse_name_flags(context, principal,
KRB5_PRINCIPAL_UNPARSE_NO_REALM,
&name);
if (ret)
goto out;
ret = hx509_env_add(context->hx509ctx, &env, "principal-name-without-realm",
name);
krb5_xfree(name);
name = NULL;
if (ret)
goto out;
/*
* Include the realm in the principal-name env var; the template
* might not use $principal-name-realm after all.
*/
ret = krb5_unparse_name(context, principal, &name);
if (ret)
goto out;
ret = hx509_env_add(context->hx509ctx, &env, "principal-name",
name);
if (ret)
goto out;
ret = hx509_env_add(context->hx509ctx, &env, "principal-name-realm",
krb5_principal_get_realm(context, principal));
if (ret)
goto out;
/* Pick an issuer based on the crealm if we can */
kx509_ca = krb5_config_get_string(context, NULL, "kdc",
krb5_principal_get_realm(context,
principal),
"kx509_ca", NULL);
if (kx509_ca == NULL)
kx509_ca = config->kx509_ca;
{
hx509_certs certs;
hx509_query *q;
ret = hx509_certs_init(context->hx509ctx, config->kx509_ca, 0,
NULL, &certs);
if (ret) {
kdc_log(context, config, 0, "Failed to load CA %s",
config->kx509_ca);
goto out;
}
ret = hx509_query_alloc(context->hx509ctx, &q);
if (ret) {
hx509_certs_free(&certs);
goto out;
}
hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY);
hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN);
ret = hx509_certs_find(context->hx509ctx, certs, q, &signer);
hx509_query_free(context->hx509ctx, q);
hx509_certs_free(&certs);
if (ret) {
kdc_log(context, config, 0, "Failed to find a CA in %s",
config->kx509_ca);
goto out;
}
}
ret = hx509_ca_tbs_init(context->hx509ctx, &tbs);
if (ret)
goto out;
{
SubjectPublicKeyInfo spki;
heim_any any;
memset(&spki, 0, sizeof(spki));
spki.subjectPublicKey.data = key->data;
spki.subjectPublicKey.length = key->length * 8;
ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption,
&spki.algorithm.algorithm);
any.data = "\x05\x00";
any.length = 2;
spki.algorithm.parameters = &any;
ret = hx509_ca_tbs_set_spki(context->hx509ctx, tbs, &spki);
der_free_oid(&spki.algorithm.algorithm);
if (ret)
goto out;
}
{
hx509_certs certs;
hx509_cert template;
ret = hx509_certs_init(context->hx509ctx, config->kx509_template, 0,
NULL, &certs);
if (ret) {
kdc_log(context, config, 0, "Failed to load template %s",
config->kx509_template);
goto out;
}
ret = hx509_get_one_cert(context->hx509ctx, certs, &template);
hx509_certs_free(&certs);
if (ret) {
kdc_log(context, config, 0, "Failed to find template in %s",
config->kx509_template);
goto out;
}
ret = hx509_ca_tbs_set_template(context->hx509ctx, tbs,
HX509_CA_TEMPLATE_SUBJECT|
HX509_CA_TEMPLATE_KU|
HX509_CA_TEMPLATE_EKU,
template);
hx509_cert_free(template);
if (ret)
goto out;
}
def_bool = krb5_config_get_bool_default(context, NULL, TRUE, "kdc",
"kx509_include_pkinit_san",
NULL);
if (krb5_config_get_bool_default(context, NULL, def_bool, "kdc",
krb5_principal_get_realm(context,
principal),
"kx509_include_pkinit_san",
NULL)) {
ret = hx509_ca_tbs_add_san_pkinit(context->hx509ctx, tbs, name);
if (ret)
goto out;
}
hx509_ca_tbs_set_notAfter(context->hx509ctx, tbs, endtime);
hx509_ca_tbs_subject_expand(context->hx509ctx, tbs, env);
hx509_env_free(&env);
ret = hx509_ca_sign(context->hx509ctx, tbs, signer, &cert);
hx509_cert_free(signer);
if (ret)
goto out;
hx509_ca_tbs_free(&tbs);
ret = hx509_cert_binary(context->hx509ctx, cert, certificate);
hx509_cert_free(cert);
if (ret)
goto out;
/* cleanup on success */
krb5_xfree(name);
return 0;
out:
if (name)
krb5_xfree(name);
if (env)
hx509_env_free(&env);
if (tbs)
hx509_ca_tbs_free(&tbs);
if (signer)
hx509_cert_free(signer);
krb5_set_error_message(context, ret, "cert creation failed");
return ret;
}
krb5_error_code
kdc_kx509_verify_service_principal(krb5_context context,
const char *cname,
krb5_principal sprincipal)
{
krb5_error_code ret, aret;
krb5_boolean bret;
krb5_principal principal = NULL;
char *expected = NULL;
char localhost[MAXHOSTNAMELEN];
ret = gethostname(localhost, sizeof(localhost) - 1);
if (ret != 0) {
ret = errno;
krb5_set_error_message(context, ret,
N_("Failed to get local hostname", ""));
return ret;
}
localhost[sizeof(localhost) - 1] = '\0';
ret = krb5_make_principal(context, &principal, "", "kca_service",
localhost, NULL);
if (ret)
goto out;
bret = krb5_principal_compare_any_realm(context, sprincipal, principal);
if (bret == TRUE)
goto out; /* found a match */
ret = KRB5KDC_ERR_SERVER_NOMATCH;
aret = krb5_unparse_name(context, sprincipal, &expected);
if (aret)
goto out;
krb5_set_error_message(context, ret,
"User %s used wrong Kx509 service "
"principal, expected: %s",
cname, expected);
out:
krb5_xfree(expected);
krb5_free_principal(context, principal);
return ret;
}
/*
*
*/
krb5_error_code
_kdc_do_kx509(krb5_context context,
krb5_kdc_configuration *config,
const struct Kx509Request *req, krb5_data *reply,
const char *from, struct sockaddr *addr)
{
krb5_error_code ret;
krb5_ticket *ticket = NULL;
krb5_flags ap_req_options;
krb5_auth_context ac = NULL;
krb5_keytab id = NULL;
krb5_principal sprincipal = NULL, cprincipal = NULL;
char *cname = NULL;
Kx509Response rep;
size_t size;
krb5_keyblock *key = NULL;
krb5_boolean def_bool;
krb5_data_zero(reply);
memset(&rep, 0, sizeof(rep));
if(!config->enable_kx509) {
kdc_log(context, config, 0,
"Rejected kx509 request (disabled) from %s", from);
return KRB5KDC_ERR_POLICY;
}
kdc_log(context, config, 0, "Kx509 request from %s", from);
ret = krb5_kt_resolve(context, "HDBGET:", &id);
if (ret) {
kdc_log(context, config, 0, "Can't open database for digest");
goto out;
}
ret = krb5_rd_req(context,
&ac,
&req->authenticator,
NULL,
id,
&ap_req_options,
&ticket);
if (ret)
goto out;
ret = krb5_ticket_get_client(context, ticket, &cprincipal);
if (ret)
goto out;
def_bool = krb5_config_get_bool_default(context, NULL, TRUE, "kdc",
"require_initial_kca_tickets",
NULL);
if (!ticket->ticket.flags.initial &&
krb5_config_get_bool_default(context, NULL, def_bool, "kdc",
krb5_principal_get_realm(context,
cprincipal),
"require_initial_kca_tickets", NULL)) {
ret = KRB5KDC_ERR_POLICY;
goto out;
}
ret = krb5_unparse_name(context, cprincipal, &cname);
if (ret)
goto out;
ret = krb5_ticket_get_server(context, ticket, &sprincipal);
if (ret)
goto out;
ret = kdc_kx509_verify_service_principal(context, cname, sprincipal);
if (ret)
goto out;
ret = krb5_auth_con_getkey(context, ac, &key);
if (ret == 0 && key == NULL)
ret = KRB5KDC_ERR_NULL_KEY;
if (ret) {
krb5_set_error_message(context, ret, "Kx509 can't get session key");
goto out;
}
ret = verify_req_hash(context, req, key);
if (ret)
goto out;
/* Verify that the key is encoded RSA key */
{
RSAPublicKey rsapkey;
size_t rsapkeysize;
ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length,
&rsapkey, &rsapkeysize);
if (ret)
goto out;
free_RSAPublicKey(&rsapkey);
if (rsapkeysize != req->pk_key.length) {
ret = ASN1_EXTRA_DATA;
goto out;
}
}
ALLOC(rep.certificate);
if (rep.certificate == NULL)
goto out;
krb5_data_zero(rep.certificate);
ALLOC(rep.hash);
if (rep.hash == NULL)
goto out;
krb5_data_zero(rep.hash);
ret = build_certificate(context, config, &req->pk_key,
krb5_ticket_get_endtime(context, ticket),
cprincipal, rep.certificate);
if (ret)
goto out;
ret = calculate_reply_hash(context, key, &rep);
if (ret)
goto out;
/*
* Encode reply, [ version | Kx509Response ]
*/
{
krb5_data data;
ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep,
&size, ret);
if (ret) {
krb5_set_error_message(context, ret, "Failed to encode kx509 reply");
goto out;
}
if (size != data.length)
krb5_abortx(context, "ASN1 internal error");
ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0));
if (ret) {
free(data.data);
goto out;
}
memcpy(reply->data, version_2_0, sizeof(version_2_0));
memcpy(((unsigned char *)reply->data) + sizeof(version_2_0),
data.data, data.length);
free(data.data);
}
kdc_log(context, config, 0, "Successful Kx509 request for %s", cname);
out:
if (ac)
krb5_auth_con_free(context, ac);
if (ret)
krb5_warn(context, ret, "Kx509 request from %s failed", from);
if (ticket)
krb5_free_ticket(context, ticket);
if (id)
krb5_kt_close(context, id);
if (sprincipal)
krb5_free_principal(context, sprincipal);
if (cprincipal)
krb5_free_principal(context, cprincipal);
if (key)
krb5_free_keyblock (context, key);
if (cname)
free(cname);
free_Kx509Response(&rep);
return 0;
}
#endif /* KX509 */