/* * 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 <hex.h> #include <rfc2459_asn1.h> #include <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; } HMAC_CTX_init(&ctx); 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); HMAC_CTX_cleanup(&ctx); 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; HMAC_CTX_init(&ctx); HMAC_Init_ex(&ctx, key->keyvalue.data, key->keyvalue.length, EVP_sha1(), NULL); ret = krb5_data_alloc(rep->hash, HMAC_size(&ctx)); if (ret) { HMAC_CTX_cleanup(&ctx); 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); HMAC_CTX_cleanup(&ctx); 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) { hx509_ca_tbs tbs = NULL; hx509_env env = NULL; hx509_cert cert = NULL; hx509_cert signer = NULL; int ret; if (krb5_principal_get_comp_string(context, principal, 1) != NULL) { kdc_log(context, config, 0, "Principal is not a user"); return EINVAL; } ret = hx509_env_add(context->hx509ctx, &env, "principal-name", krb5_principal_get_comp_string(context, principal, 0)); if (ret) goto out; { 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; } 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; return 0; out: 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_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_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, "HDB:", &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; ret = krb5_unparse_name(context, cprincipal, &cname); if (ret) goto out; /* verify server principal */ ret = krb5_sname_to_principal(context, NULL, "kca_service", KRB5_NT_UNKNOWN, &sprincipal); if (ret) goto out; { krb5_principal principal = NULL; ret = krb5_ticket_get_server(context, ticket, &principal); if (ret) goto out; ret = krb5_principal_compare(context, sprincipal, principal); krb5_free_principal(context, principal); if (ret != TRUE) { char *expected, *used; ret = krb5_unparse_name(context, sprincipal, &expected); if (ret) goto out; ret = krb5_unparse_name(context, principal, &used); if (ret) { krb5_xfree(expected); goto out; } ret = KRB5KDC_ERR_SERVER_NOMATCH; krb5_set_error_message(context, ret, "User %s used wrong Kx509 service " "principal, expected: %s, used %s", cname, expected, used); krb5_xfree(expected); krb5_xfree(used); 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 key; size_t size; ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length, &key, &size); if (ret) goto out; free_RSAPublicKey(&key); if (size != 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 */