/src/samba/auth/ntlmssp/ntlmssp_sign.c

Source
/*
 *  Unix SMB/CIFS implementation.
 *  Version 3.0
 *  NTLMSSP Signing routines
 *  Copyright (C) Andrew Bartlett 2003-2005
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "includes.h"
#include "../auth/ntlmssp/ntlmssp.h"
#include "../libcli/auth/libcli_auth.h"
#include "zlib.h"
#include "../auth/ntlmssp/ntlmssp_private.h"

#include "lib/crypto/gnutls_helpers.h"
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_AUTH

#define CLI_SIGN "session key to client-to-server signing key magic constant"
#define CLI_SEAL "session key to client-to-server sealing key magic constant"
#define SRV_SIGN "session key to server-to-client signing key magic constant"
#define SRV_SEAL "session key to server-to-client sealing key magic constant"

/**
 * Some notes on the NTLM2 code:
 *
 * NTLM2 is a AEAD system.  This means that the data encrypted is not
 * all the data that is signed.  In DCE-RPC case, the headers of the
 * DCE-RPC packets are also signed.  This prevents some of the
 * fun-and-games one might have by changing them.
 *
 */

static void dump_arc4_state(const char *description,
          gnutls_cipher_hd_t *state)
{
  DBG_DEBUG("%s\n", description);
}

static NTSTATUS calc_ntlmv2_key(uint8_t subkey[16],
        DATA_BLOB session_key,
        const char *constant)
{
  gnutls_hash_hd_t hash_hnd = NULL;
  int rc;

  rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
  if (rc < 0) {
    return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
  }
  rc = gnutls_hash(hash_hnd, session_key.data, session_key.length);
  if (rc < 0) {
    gnutls_hash_deinit(hash_hnd, NULL);
    return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
  }
  rc = gnutls_hash(hash_hnd, constant, strlen(constant) + 1);
  if (rc < 0) {
    gnutls_hash_deinit(hash_hnd, NULL);
    return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
  }
  gnutls_hash_deinit(hash_hnd, subkey);

  return NT_STATUS_OK;
}

enum ntlmssp_direction {
  NTLMSSP_SEND,
  NTLMSSP_RECEIVE
};

static NTSTATUS ntlmssp_make_packet_signature(struct ntlmssp_state *ntlmssp_state,
                TALLOC_CTX *sig_mem_ctx,
                const uint8_t *data, size_t length,
                const uint8_t *whole_pdu, size_t pdu_length,
                enum ntlmssp_direction direction,
                DATA_BLOB *sig, bool encrypt_sig)
{
  NTSTATUS status = NT_STATUS_UNSUCCESSFUL;
  int rc;

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
    gnutls_hmac_hd_t hmac_hnd = NULL;
    uint8_t digest[16];
    uint8_t seq_num[4];

    *sig = data_blob_talloc(sig_mem_ctx, NULL, NTLMSSP_SIG_SIZE);
    if (!sig->data) {
      return NT_STATUS_NO_MEMORY;
    }

    switch (direction) {
    case NTLMSSP_SEND:
      DEBUG(100,("ntlmssp_make_packet_signature: SEND seq = %u, len = %u, pdu_len = %u\n",
        ntlmssp_state->crypt->ntlm2.sending.seq_num,
        (unsigned int)length,
        (unsigned int)pdu_length));

      SIVAL(seq_num, 0, ntlmssp_state->crypt->ntlm2.sending.seq_num);
      ntlmssp_state->crypt->ntlm2.sending.seq_num++;

      rc = gnutls_hmac_init(&hmac_hnd,
                GNUTLS_MAC_MD5,
                ntlmssp_state->crypt->ntlm2.sending.sign_key,
                16);
      if (rc < 0) {
        return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
      }
      break;
    case NTLMSSP_RECEIVE:

      DEBUG(100,("ntlmssp_make_packet_signature: RECV seq = %u, len = %u, pdu_len = %u\n",
        ntlmssp_state->crypt->ntlm2.receiving.seq_num,
        (unsigned int)length,
        (unsigned int)pdu_length));

      SIVAL(seq_num, 0, ntlmssp_state->crypt->ntlm2.receiving.seq_num);
      ntlmssp_state->crypt->ntlm2.receiving.seq_num++;

      rc = gnutls_hmac_init(&hmac_hnd,
                GNUTLS_MAC_MD5,
                ntlmssp_state->crypt->ntlm2.receiving.sign_key,
                16);
      if (rc < 0) {
        return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
      }
      break;
    }

    dump_data_pw("pdu data ", whole_pdu, pdu_length);

    rc = gnutls_hmac(hmac_hnd, seq_num, sizeof(seq_num));
    if (rc < 0) {
      gnutls_hmac_deinit(hmac_hnd, NULL);
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
    rc = gnutls_hmac(hmac_hnd, whole_pdu, pdu_length);
    if (rc < 0) {
      gnutls_hmac_deinit(hmac_hnd, NULL);
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
    gnutls_hmac_deinit(hmac_hnd, digest);

    if (encrypt_sig && (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH)) {
      switch (direction) {
      case NTLMSSP_SEND:
        rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm2.sending.seal_state,
                 digest,
                 8);
        break;
      case NTLMSSP_RECEIVE:
        rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm2.receiving.seal_state,
                 digest,
                 8);
        break;
      }
      if (rc < 0) {
        DBG_ERR("gnutls_cipher_encrypt for NTLMv2 EXCH "
          "%s packet signature failed: %s\n",
          direction == NTLMSSP_SEND ?
            "send" : "receive",
          gnutls_strerror(rc));
        return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
      }
    }

    SIVAL(sig->data, 0, NTLMSSP_SIGN_VERSION);
    memcpy(sig->data + 4, digest, 8);
    ZERO_ARRAY(digest);
    memcpy(sig->data + 12, seq_num, 4);
    ZERO_ARRAY(seq_num);

    dump_data_pw("ntlmssp v2 sig ", sig->data, sig->length);

  } else {
    uint32_t crc;

    crc = crc32(0, Z_NULL, 0);
    crc = crc32(crc, data, length);

    status = msrpc_gen(sig_mem_ctx,
             sig, "dddd",
             NTLMSSP_SIGN_VERSION, 0, crc,
             ntlmssp_state->crypt->ntlm.seq_num);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }

    ntlmssp_state->crypt->ntlm.seq_num++;

    dump_arc4_state("ntlmssp hash: \n",
        &ntlmssp_state->crypt->ntlm.seal_state);
    rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm.seal_state,
             sig->data + 4,
             sig->length - 4);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_encrypt for NTLM packet "
        "signature failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
  }

  return NT_STATUS_OK;
}

NTSTATUS ntlmssp_sign_packet(struct ntlmssp_state *ntlmssp_state,
           TALLOC_CTX *sig_mem_ctx,
           const uint8_t *data, size_t length,
           const uint8_t *whole_pdu, size_t pdu_length,
           DATA_BLOB *sig)
{
  NTSTATUS nt_status;

  if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN)) {
    DEBUG(3, ("NTLMSSP Signing not negotiated - cannot sign packet!\n"));
    return NT_STATUS_INVALID_PARAMETER;
  }

  if (!ntlmssp_state->session_key.length) {
    DEBUG(3, ("NO session key, cannot check sign packet\n"));
    return NT_STATUS_NO_USER_SESSION_KEY;
  }

  nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
              sig_mem_ctx,
              data, length,
              whole_pdu, pdu_length,
              NTLMSSP_SEND, sig, true);

  return nt_status;
}

/**
 * Check the signature of an incoming packet
 * @note caller *must* check that the signature is the size it expects
 *
 */

NTSTATUS ntlmssp_check_packet(struct ntlmssp_state *ntlmssp_state,
            const uint8_t *data, size_t length,
            const uint8_t *whole_pdu, size_t pdu_length,
            const DATA_BLOB *sig)
{
  DATA_BLOB local_sig;
  NTSTATUS nt_status;
  TALLOC_CTX *tmp_ctx;

  if (!ntlmssp_state->session_key.length) {
    DEBUG(3, ("NO session key, cannot check packet signature\n"));
    return NT_STATUS_NO_USER_SESSION_KEY;
  }

  if (sig->length < 8) {
    DEBUG(0, ("NTLMSSP packet check failed due to short signature (%lu bytes)!\n",
        (unsigned long)sig->length));
  }

  tmp_ctx = talloc_new(ntlmssp_state);
  if (!tmp_ctx) {
    return NT_STATUS_NO_MEMORY;
  }

  nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
              tmp_ctx,
              data, length,
              whole_pdu, pdu_length,
              NTLMSSP_RECEIVE,
              &local_sig, true);

  if (!NT_STATUS_IS_OK(nt_status)) {
    DEBUG(0,("NTLMSSP packet sig creation failed with %s\n",
       nt_errstr(nt_status)));
    talloc_free(tmp_ctx);
    return nt_status;
  }

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
    if (local_sig.length != sig->length ||
        !mem_equal_const_time(local_sig.data, sig->data, sig->length)) {
      DEBUG(5, ("BAD SIG NTLM2: wanted signature of\n"));
      dump_data(5, local_sig.data, local_sig.length);

      DEBUG(5, ("BAD SIG: got signature of\n"));
      dump_data(5, sig->data, sig->length);

      DEBUG(0, ("NTLMSSP NTLM2 packet check failed due to invalid signature!\n"));
      talloc_free(tmp_ctx);
      return NT_STATUS_ACCESS_DENIED;
    }
  } else {
    if (local_sig.length != sig->length ||
        !mem_equal_const_time(local_sig.data + 8, sig->data + 8, sig->length - 8)) {
      DEBUG(5, ("BAD SIG NTLM1: wanted signature of\n"));
      dump_data(5, local_sig.data, local_sig.length);

      DEBUG(5, ("BAD SIG: got signature of\n"));
      dump_data(5, sig->data, sig->length);

      DEBUG(0, ("NTLMSSP NTLM1 packet check failed due to invalid signature!\n"));
      talloc_free(tmp_ctx);
      return NT_STATUS_ACCESS_DENIED;
    }
  }
  dump_data_pw("checked ntlmssp signature\n", sig->data, sig->length);
  DEBUG(10,("ntlmssp_check_packet: NTLMSSP signature OK !\n"));

  talloc_free(tmp_ctx);
  return NT_STATUS_OK;
}

/**
 * Seal data with the NTLMSSP algorithm
 *
 */

NTSTATUS ntlmssp_seal_packet(struct ntlmssp_state *ntlmssp_state,
           TALLOC_CTX *sig_mem_ctx,
           uint8_t *data, size_t length,
           const uint8_t *whole_pdu, size_t pdu_length,
           DATA_BLOB *sig)
{
  int rc;

  if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL)) {
    DEBUG(3, ("NTLMSSP Sealing not negotiated - cannot seal packet!\n"));
    return NT_STATUS_INVALID_PARAMETER;
  }

  if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN)) {
    DEBUG(3, ("NTLMSSP Sealing not negotiated - cannot seal packet!\n"));
    return NT_STATUS_INVALID_PARAMETER;
  }

  if (!ntlmssp_state->session_key.length) {
    DEBUG(3, ("NO session key, cannot seal packet\n"));
    return NT_STATUS_NO_USER_SESSION_KEY;
  }

  DEBUG(10,("ntlmssp_seal_data: seal\n"));
  dump_data_pw("ntlmssp clear data\n", data, length);
  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
    NTSTATUS nt_status;
    /*
     * The order of these two operations matters - we
     * must first seal the packet, then seal the
     * sequence number - this is because the
     * send_seal_hash is not constant, but is rather
     * updated with each iteration
     */
    nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
                sig_mem_ctx,
                data, length,
                whole_pdu, pdu_length,
                NTLMSSP_SEND,
                sig, false);
    if (!NT_STATUS_IS_OK(nt_status)) {
      return nt_status;
    }

    rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm2.sending.seal_state,
             data,
             length);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_encrypt ntlmv2 sealing the data "
        "failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
    if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH) {
      rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm2.sending.seal_state,
                sig->data + 4,
                8);
      if (rc < 0) {
        DBG_ERR("gnutls_cipher_encrypt ntlmv2 sealing "
          "the EXCH signature data failed: %s\n",
          gnutls_strerror(rc));
        return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
      }
    }
  } else {
    NTSTATUS status;
    uint32_t crc;

    crc = crc32(0, Z_NULL, 0);
    crc = crc32(crc, data, length);

    status = msrpc_gen(sig_mem_ctx,
             sig, "dddd",
             NTLMSSP_SIGN_VERSION, 0, crc,
             ntlmssp_state->crypt->ntlm.seq_num);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }

    /*
     * The order of these two operations matters - we
     * must first seal the packet, then seal the
     * sequence number - this is because the ntlmv1_arc4_state
     * is not constant, but is rather updated with
     * each iteration
     */
    dump_arc4_state("ntlmv1 arc4 state:\n",
        &ntlmssp_state->crypt->ntlm.seal_state);
    rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm.seal_state,
             data,
             length);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_encrypt ntlmv1 sealing data"
        "failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }

    dump_arc4_state("ntlmv1 arc4 state:\n",
        &ntlmssp_state->crypt->ntlm.seal_state);

    rc = gnutls_cipher_encrypt(ntlmssp_state->crypt->ntlm.seal_state,
              sig->data + 4,
              sig->length - 4);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_encrypt ntlmv1 sealing signing "
        "data failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }

    ntlmssp_state->crypt->ntlm.seq_num++;
  }
  dump_data_pw("ntlmssp signature\n", sig->data, sig->length);
  dump_data_pw("ntlmssp sealed data\n", data, length);

  return NT_STATUS_OK;
}

/**
 * Unseal data with the NTLMSSP algorithm
 *
 */

NTSTATUS ntlmssp_unseal_packet(struct ntlmssp_state *ntlmssp_state,
             uint8_t *data, size_t length,
             const uint8_t *whole_pdu, size_t pdu_length,
             const DATA_BLOB *sig)
{
  NTSTATUS status;
  int rc;

  if (!ntlmssp_state->session_key.length) {
    DEBUG(3, ("NO session key, cannot unseal packet\n"));
    return NT_STATUS_NO_USER_SESSION_KEY;
  }

  DEBUG(10,("ntlmssp_unseal_packet: seal\n"));
  dump_data_pw("ntlmssp sealed data\n", data, length);

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
    /* First unseal the data. */
    rc = gnutls_cipher_decrypt(ntlmssp_state->crypt->ntlm2.receiving.seal_state,
             data,
             length);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_decrypt ntlmv2 unsealing the "
        "data failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
    dump_data_pw("ntlmv2 clear data\n", data, length);
  } else {
    rc = gnutls_cipher_decrypt(ntlmssp_state->crypt->ntlm.seal_state,
             data,
             length);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_decrypt ntlmv1 unsealing the "
        "data failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }
    dump_data_pw("ntlmv1 clear data\n", data, length);
  }

  status = ntlmssp_check_packet(ntlmssp_state,
              data, length,
              whole_pdu, pdu_length,
              sig);

  if (!NT_STATUS_IS_OK(status)) {
    DEBUG(1,("NTLMSSP packet check for unseal failed due to invalid signature on %llu bytes of input:\n",
       (unsigned long long)length));
  }
  return status;
}

NTSTATUS ntlmssp_wrap(struct ntlmssp_state *ntlmssp_state,
          TALLOC_CTX *out_mem_ctx,
          const DATA_BLOB *in,
          DATA_BLOB *out)
{
  NTSTATUS nt_status;
  DATA_BLOB sig;

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL) {
    if (in->length + NTLMSSP_SIG_SIZE < in->length) {
      return NT_STATUS_INVALID_PARAMETER;
    }

    *out = data_blob_talloc(out_mem_ctx, NULL, in->length + NTLMSSP_SIG_SIZE);
    if (!out->data) {
      return NT_STATUS_NO_MEMORY;
    }
    memcpy(out->data + NTLMSSP_SIG_SIZE, in->data, in->length);

          nt_status = ntlmssp_seal_packet(ntlmssp_state, out_mem_ctx,
            out->data + NTLMSSP_SIG_SIZE,
            out->length - NTLMSSP_SIG_SIZE,
            out->data + NTLMSSP_SIG_SIZE,
            out->length - NTLMSSP_SIG_SIZE,
            &sig);

    if (NT_STATUS_IS_OK(nt_status)) {
      memcpy(out->data, sig.data, NTLMSSP_SIG_SIZE);
      talloc_free(sig.data);
    }
    return nt_status;

  } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN) {
    if (in->length + NTLMSSP_SIG_SIZE < in->length) {
      return NT_STATUS_INVALID_PARAMETER;
    }

    *out = data_blob_talloc(out_mem_ctx, NULL, in->length + NTLMSSP_SIG_SIZE);
    if (!out->data) {
      return NT_STATUS_NO_MEMORY;
    }
    memcpy(out->data + NTLMSSP_SIG_SIZE, in->data, in->length);

          nt_status = ntlmssp_sign_packet(ntlmssp_state, out_mem_ctx,
            out->data + NTLMSSP_SIG_SIZE,
            out->length - NTLMSSP_SIG_SIZE,
            out->data + NTLMSSP_SIG_SIZE,
            out->length - NTLMSSP_SIG_SIZE,
            &sig);

    if (NT_STATUS_IS_OK(nt_status)) {
      memcpy(out->data, sig.data, NTLMSSP_SIG_SIZE);
      talloc_free(sig.data);
    }
    return nt_status;
  } else {
    *out = data_blob_talloc(out_mem_ctx, in->data, in->length);
    if (!out->data) {
      return NT_STATUS_NO_MEMORY;
    }
    return NT_STATUS_OK;
  }
}

NTSTATUS ntlmssp_unwrap(struct ntlmssp_state *ntlmssp_state,
      TALLOC_CTX *out_mem_ctx,
      const DATA_BLOB *in,
      DATA_BLOB *out)
{
  DATA_BLOB sig;

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL) {
    if (in->length < NTLMSSP_SIG_SIZE) {
      return NT_STATUS_INVALID_PARAMETER;
    }
    sig.data = in->data;
    sig.length = NTLMSSP_SIG_SIZE;

    *out = data_blob_talloc(out_mem_ctx, in->data + NTLMSSP_SIG_SIZE, in->length - NTLMSSP_SIG_SIZE);

          return ntlmssp_unseal_packet(ntlmssp_state,
               out->data, out->length,
               out->data, out->length,
               &sig);

  } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN) {
    if (in->length < NTLMSSP_SIG_SIZE) {
      return NT_STATUS_INVALID_PARAMETER;
    }
    sig.data = in->data;
    sig.length = NTLMSSP_SIG_SIZE;

    *out = data_blob_talloc(out_mem_ctx, in->data + NTLMSSP_SIG_SIZE, in->length - NTLMSSP_SIG_SIZE);

    return ntlmssp_check_packet(ntlmssp_state,
              out->data, out->length,
              out->data, out->length,
              &sig);
  } else {
    *out = data_blob_talloc(out_mem_ctx, in->data, in->length);
    if (!out->data) {
      return NT_STATUS_NO_MEMORY;
    }
    return NT_STATUS_OK;
  }
}

/**
   Initialise the state for NTLMSSP signing.
*/
NTSTATUS ntlmssp_sign_reset(struct ntlmssp_state *ntlmssp_state,
          bool reset_seqnums)
{
  int rc;

  DEBUG(3, ("NTLMSSP Sign/Seal - Initialising with flags:\n"));
  debug_ntlmssp_flags(ntlmssp_state->neg_flags);

  if (ntlmssp_state->crypt == NULL) {
    return NT_STATUS_INVALID_PARAMETER_MIX;
  }

  if (ntlmssp_state->force_wrap_seal &&
      (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN))
  {
    /*
     * We need to handle NTLMSSP_NEGOTIATE_SIGN as
     * NTLMSSP_NEGOTIATE_SEAL if GENSEC_FEATURE_LDAP_STYLE
     * is requested.
     *
     * The negotiation of flags (and authentication)
     * is completed when ntlmssp_sign_init() is called
     * so we can safely pretent NTLMSSP_NEGOTIATE_SEAL
     * was negotiated.
     */
    ntlmssp_state->neg_flags |= NTLMSSP_NEGOTIATE_SEAL;
  }

  if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
    DATA_BLOB weak_session_key = ntlmssp_state->session_key;
    const char *send_sign_const;
    const char *send_seal_const;
    const char *recv_sign_const;
    const char *recv_seal_const;
    uint8_t send_seal_key[16] = {0};
    gnutls_datum_t send_seal_blob = {
      .data = send_seal_key,
      .size = sizeof(send_seal_key),
    };
    uint8_t recv_seal_key[16] = {0};
    gnutls_datum_t recv_seal_blob = {
      .data = recv_seal_key,
      .size = sizeof(recv_seal_key),
    };
    NTSTATUS status;

    switch (ntlmssp_state->role) {
    case NTLMSSP_CLIENT:
      send_sign_const = CLI_SIGN;
      send_seal_const = CLI_SEAL;
      recv_sign_const = SRV_SIGN;
      recv_seal_const = SRV_SEAL;
      break;
    case NTLMSSP_SERVER:
      send_sign_const = SRV_SIGN;
      send_seal_const = SRV_SEAL;
      recv_sign_const = CLI_SIGN;
      recv_seal_const = CLI_SEAL;
      break;
    default:
      return NT_STATUS_INTERNAL_ERROR;
    }

    /*
     * Weaken NTLMSSP keys to cope with down-level
     * clients, servers and export restrictions.
     *
     * We probably should have some parameters to
     * control this, once we get NTLM2 working.
     *
     * Key weakening was not performed on the master key
     * for NTLM2, but must be done on the encryption subkeys only.
     */

    if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
      /* nothing to do */
    } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
      weak_session_key.length = 7;
    } else { /* forty bits */
      weak_session_key.length = 5;
    }

    dump_data_pw("NTLMSSP weakend master key:\n",
           weak_session_key.data,
           weak_session_key.length);

    /* SEND: sign key */
    status = calc_ntlmv2_key(ntlmssp_state->crypt->ntlm2.sending.sign_key,
           ntlmssp_state->session_key, send_sign_const);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }
    dump_data_pw("NTLMSSP send sign key:\n",
           ntlmssp_state->crypt->ntlm2.sending.sign_key, 16);

    /* SEND: seal ARCFOUR pad */
    status = calc_ntlmv2_key(send_seal_key,
           weak_session_key,
           send_seal_const);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }
    dump_data_pw("NTLMSSP send seal key:\n",
           send_seal_key,
           sizeof(send_seal_key));

    if (ntlmssp_state->crypt->ntlm2.sending.seal_state != NULL) {
      gnutls_cipher_deinit(ntlmssp_state->crypt->ntlm2.sending.seal_state);
    }
    rc = gnutls_cipher_init(&ntlmssp_state->crypt->ntlm2.sending.seal_state,
          GNUTLS_CIPHER_ARCFOUR_128,
          &send_seal_blob,
          NULL);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_init failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }

    dump_arc4_state("NTLMSSP send seal arc4 state:\n",
        &ntlmssp_state->crypt->ntlm2.sending.seal_state);

    /* SEND: seq num */
    if (reset_seqnums) {
      ntlmssp_state->crypt->ntlm2.sending.seq_num = 0;
    }

    /* RECV: sign key */
    status = calc_ntlmv2_key(ntlmssp_state->crypt->ntlm2.receiving.sign_key,
           ntlmssp_state->session_key, recv_sign_const);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }
    dump_data_pw("NTLMSSP recv sign key:\n",
           ntlmssp_state->crypt->ntlm2.receiving.sign_key, 16);

    /* RECV: seal ARCFOUR pad */
    status = calc_ntlmv2_key(recv_seal_key,
           weak_session_key,
           recv_seal_const);
    if (!NT_STATUS_IS_OK(status)) {
      return status;
    }
    dump_data_pw("NTLMSSP recv seal key:\n",
           recv_seal_key,
           sizeof(recv_seal_key));

    if (ntlmssp_state->crypt->ntlm2.receiving.seal_state != NULL) {
      gnutls_cipher_deinit(ntlmssp_state->crypt->ntlm2.receiving.seal_state);
    }
    rc = gnutls_cipher_init(&ntlmssp_state->crypt->ntlm2.receiving.seal_state,
          GNUTLS_CIPHER_ARCFOUR_128,
          &recv_seal_blob,
          NULL);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_init failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }

    dump_arc4_state("NTLMSSP recv seal arc4 state:\n",
        &ntlmssp_state->crypt->ntlm2.receiving.seal_state);

    /* RECV: seq num */
    if (reset_seqnums) {
      ntlmssp_state->crypt->ntlm2.receiving.seq_num = 0;
    }
  } else {
    gnutls_datum_t seal_session_key = {
      .data = ntlmssp_state->session_key.data,
      .size = ntlmssp_state->session_key.length,
    };
    bool do_weak = false;

    DEBUG(5, ("NTLMSSP Sign/Seal - using NTLM1\n"));

    /*
     * Key weakening not performed on the master key for NTLM2
     * and does not occur for NTLM1. Therefore we only need
     * to do this for the LM_KEY.
     */
    if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_LM_KEY) {
      do_weak = true;
    }

    /*
     * Nothing to weaken.
     * We certainly don't want to 'extend' the length...
     */
    if (ntlmssp_state->session_key.length < 16) {
      /* TODO: is this really correct? */
      do_weak = false;
    }

    if (do_weak) {
      uint8_t weak_session_key[8];

      memcpy(weak_session_key, seal_session_key.data, 8);
      seal_session_key = (gnutls_datum_t) {
        .data = weak_session_key,
        .size = sizeof(weak_session_key),
      };

      /*
       * LM key doesn't support 128 bit crypto, so this is
       * the best we can do. If you negotiate 128 bit, but
       * not 56, you end up with 40 bit...
       */
      if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
        weak_session_key[7] = 0xa0;
      } else { /* forty bits */
        weak_session_key[5] = 0xe5;
        weak_session_key[6] = 0x38;
        weak_session_key[7] = 0xb0;
      }
    }

    if (ntlmssp_state->crypt->ntlm.seal_state != NULL) {
      gnutls_cipher_deinit(ntlmssp_state->crypt->ntlm.seal_state);
    }
    rc = gnutls_cipher_init(&ntlmssp_state->crypt->ntlm.seal_state,
          GNUTLS_CIPHER_ARCFOUR_128,
          &seal_session_key,
          NULL);
    if (rc < 0) {
      DBG_ERR("gnutls_cipher_init failed: %s\n",
        gnutls_strerror(rc));
      return gnutls_error_to_ntstatus(rc, NT_STATUS_NTLM_BLOCKED);
    }

    dump_arc4_state("NTLMv1 arc4 state:\n",
        &ntlmssp_state->crypt->ntlm.seal_state);

    if (reset_seqnums) {
      ntlmssp_state->crypt->ntlm.seq_num = 0;
    }
  }

  return NT_STATUS_OK;
}

static int ntlmssp_crypt_free_gnutls_cipher_state(union ntlmssp_crypt_state *c)
{
  if (c->ntlm2.sending.seal_state != NULL) {
    gnutls_cipher_deinit(c->ntlm2.sending.seal_state);
    c->ntlm2.sending.seal_state = NULL;
  }
  if (c->ntlm2.receiving.seal_state != NULL) {
    gnutls_cipher_deinit(c->ntlm2.receiving.seal_state);
    c->ntlm2.receiving.seal_state = NULL;
  }
  if (c->ntlm.seal_state != NULL) {
    gnutls_cipher_deinit(c->ntlm.seal_state);
    c->ntlm.seal_state = NULL;
  }

  return 0;
}

NTSTATUS ntlmssp_sign_init(struct ntlmssp_state *ntlmssp_state)
{
  if (ntlmssp_state->session_key.length < 8) {
    DEBUG(3, ("NO session key, cannot initialise signing\n"));
    return NT_STATUS_NO_USER_SESSION_KEY;
  }

  ntlmssp_state->crypt = talloc_zero(ntlmssp_state,
             union ntlmssp_crypt_state);
  if (ntlmssp_state->crypt == NULL) {
    return NT_STATUS_NO_MEMORY;
  }
  talloc_set_destructor(ntlmssp_state->crypt,
            ntlmssp_crypt_free_gnutls_cipher_state);

  return ntlmssp_sign_reset(ntlmssp_state, true);
}

Coverage Report

Created: 2026-02-14 07:07