lib/krb5/pkinit-ec.c

   1 /*
   2  * Copyright (c) 2016 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Portions Copyright (c) 2009 Apple Inc. All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * 3. Neither the name of the Institute nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <config.h>
  37 #include <roken.h>
  38
  39 #ifdef PKINIT
  40
  41 /*
  42  * As with the other *-ec.c files in Heimdal, this is a bit of a hack.
  43  *
  44  * The idea is to use OpenSSL for EC because hcrypto doesn't have the
  45  * required functionality at this time.  To do this we segregate
  46  * EC-using code into separate source files and then we arrange for them
  47  * to get the OpenSSL headers and not the conflicting hcrypto ones.
  48  *
  49  * Because of auto-generated *-private.h headers, we end up needing to
  50  * make sure various types are defined before we include them, thus the
  51  * strange header include order here.
  52  */
  53
  54 #ifdef HAVE_HCRYPTO_W_OPENSSL
  55 #include <openssl/ec.h>
  56 #include <openssl/ecdh.h>
  57 #include <openssl/evp.h>
  58 #include <openssl/bn.h>
  59 #define HEIM_NO_CRYPTO_HDRS
  60 #endif
  61
  62 /*
  63  * NO_HCRYPTO_POLLUTION -> don't refer to hcrypto type/function names
  64  * that we don't need in this file and which would clash with OpenSSL's
  65  * in ways that are difficult to address in cleaner ways.
  66  *
  67  * In the medium- to long-term what we should do is move all PK in
  68  * Heimdal to the newer EVP interfaces for PK and then nothing outside
  69  * lib/hcrypto should ever have to include OpenSSL headers, and -more
  70  * specifically- the only thing that should ever have to include OpenSSL
  71  * headers is the OpenSSL backend to hcrypto.
  72  */
  73 #define NO_HCRYPTO_POLLUTION
  74
  75 #include "krb5_locl.h"
  76 #include <hcrypto/des.h>
  77 #include <cms_asn1.h>
  78 #include <pkcs8_asn1.h>
  79 #include <pkcs9_asn1.h>
  80 #include <pkcs12_asn1.h>
  81 #include <pkinit_asn1.h>
  82 #include <asn1_err.h>
  83
  84 #include <der.h>
  85
  86 krb5_error_code
  87 _krb5_build_authpack_subjectPK_EC(krb5_context context,
  88                                   krb5_pk_init_ctx ctx,
  89                                   AuthPack *a)
  90 {
  91 #ifdef HAVE_HCRYPTO_W_OPENSSL
  92     krb5_error_code ret;
  93     ECParameters ecp;
  94     unsigned char *p;
  95     size_t size;
  96     int xlen;
  97
  98     /* copy in public key, XXX find the best curve that the server support or use the clients curve if possible */
  99
 100     ecp.element = choice_ECParameters_namedCurve;
 101     ret = der_copy_oid(&asn1_oid_id_ec_group_secp256r1,
 102                        &ecp.u.namedCurve);
 103     if (ret)
 104         return ret;
 105
 106     ALLOC(a->clientPublicValue->algorithm.parameters, 1);
 107     if (a->clientPublicValue->algorithm.parameters == NULL) {
 108         free_ECParameters(&ecp);
 109         return krb5_enomem(context);
 110     }
 111     ASN1_MALLOC_ENCODE(ECParameters, p, xlen, &ecp, &size, ret);
 112     free_ECParameters(&ecp);
 113     if (ret)
 114         return ret;
 115     if ((int)size != xlen)
 116         krb5_abortx(context, "asn1 internal error");
 117
 118     a->clientPublicValue->algorithm.parameters->data = p;
 119     a->clientPublicValue->algorithm.parameters->length = size;
 120
 121     /* copy in public key */
 122
 123     ret = der_copy_oid(&asn1_oid_id_ecPublicKey,
 124                        &a->clientPublicValue->algorithm.algorithm);
 125     if (ret)
 126         return ret;
 127
 128     ctx->u.eckey = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
 129     if (ctx->u.eckey == NULL)
 130         return krb5_enomem(context);
 131
 132     ret = EC_KEY_generate_key(ctx->u.eckey);
 133     if (ret != 1)
 134         return EINVAL;
 135
 136     xlen = i2o_ECPublicKey(ctx->u.eckey, NULL);
 137     if (xlen <= 0)
 138         return EINVAL;
 139
 140     p = malloc(xlen);
 141     if (p == NULL)
 142         return krb5_enomem(context);
 143
 144     a->clientPublicValue->subjectPublicKey.data = p;
 145
 146     xlen = i2o_ECPublicKey(ctx->u.eckey, &p);
 147     if (xlen <= 0) {
 148         a->clientPublicValue->subjectPublicKey.data = NULL;
 149         free(p);
 150         return EINVAL;
 151     }
 152
 153     a->clientPublicValue->subjectPublicKey.length = xlen * 8;
 154
 155     return 0;
 156
 157     /* XXX verify that this is right with RFC3279 */
 158 #else
 159     krb5_set_error_message(context, ENOTSUP,
 160                            N_("PKINIT: ECDH not supported", ""));
 161     return ENOTSUP;
 162 #endif
 163 }
 164
 165 krb5_error_code
 166 _krb5_pk_rd_pa_reply_ecdh_compute_key(krb5_context context,
 167                                       krb5_pk_init_ctx ctx,
 168                                       const unsigned char *in,
 169                                       size_t in_sz,
 170                                       unsigned char **out,
 171                                       int *out_sz)
 172 {
 173 #ifdef HAVE_HCRYPTO_W_OPENSSL
 174     krb5_error_code ret = 0;
 175     int dh_gen_keylen;
 176
 177     const EC_GROUP *group;
 178     EC_KEY *public = NULL;
 179
 180     group = EC_KEY_get0_group(ctx->u.eckey);
 181
 182     public = EC_KEY_new();
 183     if (public == NULL)
 184         return krb5_enomem(context);
 185     if (EC_KEY_set_group(public, group) != 1) {
 186         EC_KEY_free(public);
 187         return krb5_enomem(context);
 188     }
 189
 190     if (o2i_ECPublicKey(&public, &in, in_sz) == NULL) {
 191         EC_KEY_free(public);
 192         ret = KRB5KRB_ERR_GENERIC;
 193         krb5_set_error_message(context, ret,
 194                                N_("PKINIT: Can't parse ECDH public key", ""));
 195         return ret;
 196     }
 197
 198     *out_sz = (EC_GROUP_get_degree(group) + 7) / 8;
 199     if (*out_sz < 0)
 200         return EOVERFLOW;
 201     *out = malloc(*out_sz);
 202     if (*out == NULL) {
 203         EC_KEY_free(public);
 204         return krb5_enomem(context);
 205     }
 206     dh_gen_keylen = ECDH_compute_key(*out, *out_sz,
 207                                      EC_KEY_get0_public_key(public),
 208                                      ctx->u.eckey, NULL);
 209     EC_KEY_free(public);
 210     if (dh_gen_keylen <= 0) {
 211         ret = KRB5KRB_ERR_GENERIC;
 212         dh_gen_keylen = 0;
 213         krb5_set_error_message(context, ret,
 214                                N_("PKINIT: Can't compute ECDH public key", ""));
 215         free(*out);
 216         *out = NULL;
 217         *out_sz = 0;
 218     }
 219     *out_sz = dh_gen_keylen;
 220
 221     return ret;
 222 #else
 223     krb5_set_error_message(context, ENOTSUP,
 224                            N_("PKINIT: ECDH not supported", ""));
 225     return ENOTSUP;
 226 #endif
 227 }
 228
 229 void
 230 _krb5_pk_eckey_free(void *eckey)
 231 {
 232 #ifdef HAVE_HCRYPTO_W_OPENSSL
 233     EC_KEY_free(eckey);
 234 #endif
 235 }
 236
 237 #else
 238
 239 static char lib_krb5_pkinit_ec_c = '\0';
 240
 241 #endif