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/*
 * Copyright (c) 1997 - 2003 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 "gsskrb5_locl.h"

#ifdef HEIM_WEAK_CRYPTO

static OM_uint32
mic_des
           (OM_uint32 * minor_status,
            const gsskrb5_ctx ctx,
	    krb5_context context,
            gss_qop_t qop_req,
            const gss_buffer_t message_buffer,
            gss_buffer_t message_token,
	    krb5_keyblock *key
           )
{
  u_char *p;
  EVP_MD_CTX *md5;
  u_char hash[16];
  DES_key_schedule schedule;
  EVP_CIPHER_CTX des_ctx;
  DES_cblock deskey;
  DES_cblock zero;
  int32_t seq_number;
  size_t len, total_len;

  _gsskrb5_encap_length (22, &len, &total_len, GSS_KRB5_MECHANISM);

  message_token->length = total_len;
  message_token->value  = malloc (total_len);
  if (message_token->value == NULL) {
    message_token->length = 0;
    *minor_status = ENOMEM;
    return GSS_S_FAILURE;
  }

  p = _gsskrb5_make_header(message_token->value,
			      len,
			      "\x01\x01", /* TOK_ID */
			      GSS_KRB5_MECHANISM);

  memcpy (p, "\x00\x00", 2);	/* SGN_ALG = DES MAC MD5 */
  p += 2;

  memcpy (p, "\xff\xff\xff\xff", 4); /* Filler */
  p += 4;

  /* Fill in later (SND-SEQ) */
  memset (p, 0, 16);
  p += 16;

  /* checksum */
  md5 = EVP_MD_CTX_create();
  EVP_DigestInit_ex(md5, EVP_md5(), NULL);
  EVP_DigestUpdate(md5, p - 24, 8);
  EVP_DigestUpdate(md5, message_buffer->value, message_buffer->length);
  EVP_DigestFinal_ex(md5, hash, NULL);
  EVP_MD_CTX_destroy(md5);

  memset (&zero, 0, sizeof(zero));
  memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
  DES_set_key_unchecked (&deskey, &schedule);
  DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
		 &schedule, &zero);
  memcpy (p - 8, hash, 8);	/* SGN_CKSUM */

  HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
  /* sequence number */
  krb5_auth_con_getlocalseqnumber (context,
				   ctx->auth_context,
				   &seq_number);

  p -= 16;			/* SND_SEQ */
  p[0] = (seq_number >> 0)  & 0xFF;
  p[1] = (seq_number >> 8)  & 0xFF;
  p[2] = (seq_number >> 16) & 0xFF;
  p[3] = (seq_number >> 24) & 0xFF;
  memset (p + 4,
	  (ctx->more_flags & LOCAL) ? 0 : 0xFF,
	  4);

  EVP_CIPHER_CTX_init(&des_ctx);
  EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, p + 8, 1);
  EVP_Cipher(&des_ctx, p, p, 8);
  EVP_CIPHER_CTX_cleanup(&des_ctx);

  krb5_auth_con_setlocalseqnumber (context,
			       ctx->auth_context,
			       ++seq_number);
  HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);

  memset (deskey, 0, sizeof(deskey));
  memset (&schedule, 0, sizeof(schedule));

  *minor_status = 0;
  return GSS_S_COMPLETE;
}
#endif

static OM_uint32
mic_des3
           (OM_uint32 * minor_status,
            const gsskrb5_ctx ctx,
	    krb5_context context,
            gss_qop_t qop_req,
            const gss_buffer_t message_buffer,
            gss_buffer_t message_token,
	    krb5_keyblock *key
           )
{
  u_char *p;
  Checksum cksum;
  u_char seq[8];

  int32_t seq_number;
  size_t len, total_len;

  krb5_crypto crypto;
  krb5_error_code kret;
  krb5_data encdata;
  char *tmp;
  char ivec[8];

  _gsskrb5_encap_length (36, &len, &total_len, GSS_KRB5_MECHANISM);

  message_token->length = total_len;
  message_token->value  = malloc (total_len);
  if (message_token->value == NULL) {
      message_token->length = 0;
      *minor_status = ENOMEM;
      return GSS_S_FAILURE;
  }

  p = _gsskrb5_make_header(message_token->value,
			      len,
			      "\x01\x01", /* TOK-ID */
			      GSS_KRB5_MECHANISM);

  memcpy (p, "\x04\x00", 2);	/* SGN_ALG = HMAC SHA1 DES3-KD */
  p += 2;

  memcpy (p, "\xff\xff\xff\xff", 4); /* filler */
  p += 4;

  /* this should be done in parts */

  tmp = malloc (message_buffer->length + 8);
  if (tmp == NULL) {
      free (message_token->value);
      message_token->value = NULL;
      message_token->length = 0;
      *minor_status = ENOMEM;
      return GSS_S_FAILURE;
  }
  memcpy (tmp, p - 8, 8);
  memcpy (tmp + 8, message_buffer->value, message_buffer->length);

  kret = krb5_crypto_init(context, key, 0, &crypto);
  if (kret) {
      free (message_token->value);
      message_token->value = NULL;
      message_token->length = 0;
      free (tmp);
      *minor_status = kret;
      return GSS_S_FAILURE;
  }

  kret = krb5_create_checksum (context,
			       crypto,
			       KRB5_KU_USAGE_SIGN,
			       0,
			       tmp,
			       message_buffer->length + 8,
			       &cksum);
  free (tmp);
  krb5_crypto_destroy (context, crypto);
  if (kret) {
      free (message_token->value);
      message_token->value = NULL;
      message_token->length = 0;
      *minor_status = kret;
      return GSS_S_FAILURE;
  }

  memcpy (p + 8, cksum.checksum.data, cksum.checksum.length);

  HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
  /* sequence number */
  krb5_auth_con_getlocalseqnumber (context,
			       ctx->auth_context,
			       &seq_number);

  seq[0] = (seq_number >> 0)  & 0xFF;
  seq[1] = (seq_number >> 8)  & 0xFF;
  seq[2] = (seq_number >> 16) & 0xFF;
  seq[3] = (seq_number >> 24) & 0xFF;
  memset (seq + 4,
	  (ctx->more_flags & LOCAL) ? 0 : 0xFF,
	  4);

  kret = krb5_crypto_init(context, key,
			  ETYPE_DES3_CBC_NONE, &crypto);
  if (kret) {
      free (message_token->value);
      message_token->value = NULL;
      message_token->length = 0;
      *minor_status = kret;
      return GSS_S_FAILURE;
  }

  if (ctx->more_flags & COMPAT_OLD_DES3)
      memset(ivec, 0, 8);
  else
      memcpy(ivec, p + 8, 8);

  kret = krb5_encrypt_ivec (context,
			    crypto,
			    KRB5_KU_USAGE_SEQ,
			    seq, 8, &encdata, ivec);
  krb5_crypto_destroy (context, crypto);
  if (kret) {
      free (message_token->value);
      message_token->value = NULL;
      message_token->length = 0;
      *minor_status = kret;
      return GSS_S_FAILURE;
  }

  assert (encdata.length == 8);

  memcpy (p, encdata.data, encdata.length);
  krb5_data_free (&encdata);

  krb5_auth_con_setlocalseqnumber (context,
			       ctx->auth_context,
			       ++seq_number);
  HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);

  free_Checksum (&cksum);
  *minor_status = 0;
  return GSS_S_COMPLETE;
}

OM_uint32 GSSAPI_CALLCONV _gsskrb5_get_mic
           (OM_uint32 * minor_status,
            gss_const_ctx_id_t context_handle,
            gss_qop_t qop_req,
            const gss_buffer_t message_buffer,
            gss_buffer_t message_token
           )
{
  krb5_context context;
  const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
  krb5_keyblock *key;
  OM_uint32 ret;

  GSSAPI_KRB5_INIT (&context);

  if (ctx->more_flags & IS_CFX)
      return _gssapi_mic_cfx (minor_status, ctx, context, qop_req,
			      message_buffer, message_token);

  HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
  ret = _gsskrb5i_get_token_key(ctx, context, &key);
  HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
  if (ret) {
      *minor_status = ret;
      return GSS_S_FAILURE;
  }

  switch (key->keytype) {
  case KRB5_ENCTYPE_DES_CBC_CRC :
  case KRB5_ENCTYPE_DES_CBC_MD4 :
  case KRB5_ENCTYPE_DES_CBC_MD5 :
#ifdef HEIM_WEAK_CRYPTO
      ret = mic_des (minor_status, ctx, context, qop_req,
		     message_buffer, message_token, key);
#else
      ret = GSS_S_FAILURE;
#endif
      break;
  case KRB5_ENCTYPE_DES3_CBC_MD5 :
  case KRB5_ENCTYPE_DES3_CBC_SHA1 :
      ret = mic_des3 (minor_status, ctx, context, qop_req,
		      message_buffer, message_token, key);
      break;
  case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
  case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
      ret = _gssapi_get_mic_arcfour (minor_status, ctx, context, qop_req,
				     message_buffer, message_token, key);
      break;
  default :
      abort();
      break;
  }
  krb5_free_keyblock (context, key);
  return ret;
}