/*

   Unix SMB/CIFS implementation.

   Create and parse the krb5 PAC

   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005,2008

   Copyright (C) Andrew Tridgell 2001

   Copyright (C) Luke Howard 2002-2003

   Copyright (C) Stefan Metzmacher 2004-2005

   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 "system/kerberos.h"

#include "auth/auth.h"

#include "auth/kerberos/kerberos.h"

#include "librpc/gen_ndr/ndr_krb5pac.h"

#include <ldb.h>

#include "auth/auth_sam_reply.h"

#include "auth/credentials/credentials.h"

#include "auth/kerberos/kerberos_util.h"

#include "auth/kerberos/pac_utils.h"

 krb5_error_code kerberos_encode_pac(TALLOC_CTX *mem_ctx,

            struct PAC_DATA *pac_data,

            krb5_context context,

            const krb5_keyblock *krbtgt_keyblock,

            const krb5_keyblock *service_keyblock,

            DATA_BLOB *pac)

{

  NTSTATUS nt_status;

  krb5_error_code ret;

  enum ndr_err_code ndr_err;

  DATA_BLOB zero_blob = data_blob(NULL, 0);

  DATA_BLOB tmp_blob = data_blob(NULL, 0);

  struct PAC_SIGNATURE_DATA *kdc_checksum = NULL;

  struct PAC_SIGNATURE_DATA *srv_checksum = NULL;

  uint32_t i;

  /* First, just get the keytypes filled in (and lengths right, eventually) */

  for (i=0; i < pac_data->num_buffers; i++) {

    if (pac_data->buffers[i].type != PAC_TYPE_KDC_CHECKSUM) {

      continue;

    }

    kdc_checksum = &pac_data->buffers[i].info->kdc_cksum,

    ret = smb_krb5_make_pac_checksum(mem_ctx,

             &zero_blob,

             context,

             krbtgt_keyblock,

             &kdc_checksum->type,

             &kdc_checksum->signature);

    if (ret) {

      DEBUG(2, ("making krbtgt PAC checksum failed: %s\n",

          smb_get_krb5_error_message(context, ret, mem_ctx)));

      talloc_free(pac_data);

      return ret;

    }

  }

  for (i=0; i < pac_data->num_buffers; i++) {

    if (pac_data->buffers[i].type != PAC_TYPE_SRV_CHECKSUM) {

      continue;

    }

    srv_checksum = &pac_data->buffers[i].info->srv_cksum;

    ret = smb_krb5_make_pac_checksum(mem_ctx,

             &zero_blob,

             context,

             service_keyblock,

             &srv_checksum->type,

             &srv_checksum->signature);

    if (ret) {

      DEBUG(2, ("making service PAC checksum failed: %s\n",

          smb_get_krb5_error_message(context, ret, mem_ctx)));

      talloc_free(pac_data);

      return ret;

    }

  }

  if (!kdc_checksum) {

    DEBUG(2, ("Invalid PAC constructed for signing, no KDC checksum present!\n"));

    return EINVAL;

  }

  if (!srv_checksum) {

    DEBUG(2, ("Invalid PAC constructed for signing, no SRV checksum present!\n"));

    return EINVAL;

  }

  /* But wipe out the actual signatures */

  memset(kdc_checksum->signature.data, '\0', kdc_checksum->signature.length);

  memset(srv_checksum->signature.data, '\0', srv_checksum->signature.length);

  ndr_err = ndr_push_struct_blob(&tmp_blob, mem_ctx,

               pac_data,

               (ndr_push_flags_fn_t)ndr_push_PAC_DATA);

  if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

    nt_status = ndr_map_error2ntstatus(ndr_err);

    DEBUG(1, ("PAC (presig) push failed: %s\n", nt_errstr(nt_status)));

    talloc_free(pac_data);

    return EINVAL;

  }

  /* Then sign the result of the previous push, where the sig was zero'ed out */

  ret = smb_krb5_make_pac_checksum(mem_ctx,

           &tmp_blob,

           context,

           service_keyblock,

           &srv_checksum->type,

           &srv_checksum->signature);

  if (ret) {

    DBG_WARNING("making krbtgt PAC srv_checksum failed: %s\n",

          smb_get_krb5_error_message(context, ret, mem_ctx));

    talloc_free(pac_data);

    return ret;

  }

  /* Then sign Server checksum */

  ret = smb_krb5_make_pac_checksum(mem_ctx,

           &srv_checksum->signature,

           context,

           krbtgt_keyblock,

           &kdc_checksum->type,

           &kdc_checksum->signature);

  if (ret) {

    DBG_WARNING("making krbtgt PAC kdc_checksum failed: %s\n",

          smb_get_krb5_error_message(context, ret, mem_ctx));

    talloc_free(pac_data);

    return ret;

  }

  /* And push it out again, this time to the world.  This relies on deterministic pointer values */

  ndr_err = ndr_push_struct_blob(&tmp_blob, mem_ctx,

               pac_data,

               (ndr_push_flags_fn_t)ndr_push_PAC_DATA);

  if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

    nt_status = ndr_map_error2ntstatus(ndr_err);

    DEBUG(1, ("PAC (final) push failed: %s\n", nt_errstr(nt_status)));

    talloc_free(pac_data);

    return EINVAL;

  }

  *pac = tmp_blob;

  return ret;

}

 krb5_error_code kerberos_create_pac(TALLOC_CTX *mem_ctx,

             struct auth_user_info_dc *user_info_dc,

             krb5_context context,

             const krb5_keyblock *krbtgt_keyblock,

             const krb5_keyblock *service_keyblock,

             krb5_principal client_principal,

             time_t tgs_authtime,

             DATA_BLOB *pac)

{

  NTSTATUS nt_status;

  krb5_error_code ret;

  struct PAC_DATA *pac_data = talloc(mem_ctx, struct PAC_DATA);

  struct netr_SamInfo3 *sam3;

  union PAC_INFO *u_LOGON_INFO;

  struct PAC_LOGON_INFO *LOGON_INFO;

  union PAC_INFO *u_LOGON_NAME;

  struct PAC_LOGON_NAME *LOGON_NAME;

  union PAC_INFO *u_KDC_CHECKSUM;

  union PAC_INFO *u_SRV_CHECKSUM;

  char *name;

  enum {

    PAC_BUF_LOGON_INFO = 0,

    PAC_BUF_LOGON_NAME = 1,

    PAC_BUF_SRV_CHECKSUM = 2,

    PAC_BUF_KDC_CHECKSUM = 3,

    PAC_BUF_NUM_BUFFERS = 4

  };

  if (!pac_data) {

    return ENOMEM;

  }

  pac_data->num_buffers = PAC_BUF_NUM_BUFFERS;

  pac_data->version = 0;

  pac_data->buffers = talloc_array(pac_data,

           struct PAC_BUFFER,

           pac_data->num_buffers);

  if (!pac_data->buffers) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  /* LOGON_INFO */

  u_LOGON_INFO = talloc_zero(pac_data->buffers, union PAC_INFO);

  if (!u_LOGON_INFO) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  pac_data->buffers[PAC_BUF_LOGON_INFO].type = PAC_TYPE_LOGON_INFO;

  pac_data->buffers[PAC_BUF_LOGON_INFO].info = u_LOGON_INFO;

  /* LOGON_NAME */

  u_LOGON_NAME = talloc_zero(pac_data->buffers, union PAC_INFO);

  if (!u_LOGON_NAME) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  pac_data->buffers[PAC_BUF_LOGON_NAME].type = PAC_TYPE_LOGON_NAME;

  pac_data->buffers[PAC_BUF_LOGON_NAME].info = u_LOGON_NAME;

  LOGON_NAME = &u_LOGON_NAME->logon_name;

  /* SRV_CHECKSUM */

  u_SRV_CHECKSUM = talloc_zero(pac_data->buffers, union PAC_INFO);

  if (!u_SRV_CHECKSUM) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  pac_data->buffers[PAC_BUF_SRV_CHECKSUM].type = PAC_TYPE_SRV_CHECKSUM;

  pac_data->buffers[PAC_BUF_SRV_CHECKSUM].info = u_SRV_CHECKSUM;

  /* KDC_CHECKSUM */

  u_KDC_CHECKSUM = talloc_zero(pac_data->buffers, union PAC_INFO);

  if (!u_KDC_CHECKSUM) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  pac_data->buffers[PAC_BUF_KDC_CHECKSUM].type = PAC_TYPE_KDC_CHECKSUM;

  pac_data->buffers[PAC_BUF_KDC_CHECKSUM].info = u_KDC_CHECKSUM;

  /* now the real work begins... */

  LOGON_INFO = talloc_zero(u_LOGON_INFO, struct PAC_LOGON_INFO);

  if (!LOGON_INFO) {

    talloc_free(pac_data);

    return ENOMEM;

  }

  nt_status = auth_convert_user_info_dc_saminfo3(LOGON_INFO, user_info_dc,

                   AUTH_INCLUDE_RESOURCE_GROUPS,

                   &sam3, NULL);

  if (!NT_STATUS_IS_OK(nt_status)) {

    DEBUG(1, ("Getting Samba info failed: %s\n", nt_errstr(nt_status)));

    talloc_free(pac_data);

    return EINVAL;

  }

  u_LOGON_INFO->logon_info.info   = LOGON_INFO;

  LOGON_INFO->info3 = *sam3;

  ret = krb5_unparse_name_flags(context, client_principal,

              KRB5_PRINCIPAL_UNPARSE_NO_REALM |

              KRB5_PRINCIPAL_UNPARSE_DISPLAY,

              &name);

  if (ret) {

    return ret;

  }

  LOGON_NAME->account_name  = talloc_strdup(LOGON_NAME, name);

  free(name);

  /*

    this logon_time field is absolutely critical. This is what

    caused all our PAC troubles :-)

  */

  unix_to_nt_time(&LOGON_NAME->logon_time, tgs_authtime);

  ret = kerberos_encode_pac(mem_ctx,

          pac_data,

          context,

          krbtgt_keyblock,

          service_keyblock,

          pac);

  talloc_free(pac_data);

  return ret;

}

static krb5_error_code kerberos_pac_buffer_present(krb5_context context,

               const krb5_const_pac pac,

               uint32_t type)

{

#ifdef SAMBA4_USES_HEIMDAL

  return krb5_pac_get_buffer(context, pac, type, NULL);

#else /* MIT */

  krb5_error_code ret;

  krb5_data data;

  /*

   * MIT won't let us pass NULL for the data parameter, so we are forced

   * to allocate a new buffer and then immediately free it.

   */

  ret = krb5_pac_get_buffer(context, pac, type, &data);

  if (ret == 0) {

    krb5_free_data_contents(context, &data);

  }

  return ret;

#endif /* SAMBA4_USES_HEIMDAL */

}

krb5_error_code kerberos_pac_to_user_info_dc(TALLOC_CTX *mem_ctx,

               krb5_const_pac pac,

               krb5_context context,

               struct auth_user_info_dc **user_info_dc,

               const enum auth_group_inclusion group_inclusion,

               struct PAC_SIGNATURE_DATA *pac_srv_sig,

               struct PAC_SIGNATURE_DATA *pac_kdc_sig,

               struct PAC_DOMAIN_GROUP_MEMBERSHIP **resource_groups)

{

  NTSTATUS nt_status;

  enum ndr_err_code ndr_err;

  krb5_error_code ret;

  DATA_BLOB pac_logon_info_in, pac_srv_checksum_in, pac_kdc_checksum_in;

  krb5_data k5pac_logon_info_in, k5pac_srv_checksum_in, k5pac_kdc_checksum_in;

  DATA_BLOB pac_upn_dns_info_in;

  krb5_data k5pac_upn_dns_info_in;

  union PAC_INFO info;

  union PAC_INFO _upn_dns_info;

  struct PAC_UPN_DNS_INFO *upn_dns_info = NULL;

  struct auth_user_info_dc *user_info_dc_out;

  const struct PAC_DOMAIN_GROUP_MEMBERSHIP *resource_groups_in = NULL;

  struct PAC_DOMAIN_GROUP_MEMBERSHIP *resource_groups_out = NULL;

  TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);

  if (!tmp_ctx) {

    return ENOMEM;

  }

  if (pac == NULL) {

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  ret = krb5_pac_get_buffer(context, pac, PAC_TYPE_LOGON_INFO, &k5pac_logon_info_in);

  if (ret != 0) {

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  pac_logon_info_in = data_blob_const(k5pac_logon_info_in.data, k5pac_logon_info_in.length);

  ndr_err = ndr_pull_union_blob(&pac_logon_info_in, tmp_ctx, &info,

              PAC_TYPE_LOGON_INFO,

              (ndr_pull_flags_fn_t)ndr_pull_PAC_INFO);

  smb_krb5_free_data_contents(context, &k5pac_logon_info_in);

  if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

    nt_status = ndr_map_error2ntstatus(ndr_err);

    DEBUG(0,("can't parse the PAC LOGON_INFO: %s\n", nt_errstr(nt_status)));

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  if (info.logon_info.info == NULL) {

    DEBUG(0,("can't parse the PAC LOGON_INFO: missing info pointer\n"));

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  ret = krb5_pac_get_buffer(context, pac, PAC_TYPE_UPN_DNS_INFO,

          &k5pac_upn_dns_info_in);

  if (ret == ENOENT) {

    ZERO_STRUCT(k5pac_upn_dns_info_in);

    ret = 0;

  }

  if (ret != 0) {

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  pac_upn_dns_info_in = data_blob_const(k5pac_upn_dns_info_in.data,

                k5pac_upn_dns_info_in.length);

  if (pac_upn_dns_info_in.length != 0) {

    ndr_err = ndr_pull_union_blob(&pac_upn_dns_info_in, tmp_ctx,

                &_upn_dns_info,

                PAC_TYPE_UPN_DNS_INFO,

                (ndr_pull_flags_fn_t)ndr_pull_PAC_INFO);

    smb_krb5_free_data_contents(context, &k5pac_upn_dns_info_in);

    if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

      nt_status = ndr_map_error2ntstatus(ndr_err);

      DEBUG(0,("can't parse the PAC UPN_DNS_INFO: %s\n",

         nt_errstr(nt_status)));

      talloc_free(tmp_ctx);

      return EINVAL;

    }

    upn_dns_info = &_upn_dns_info.upn_dns_info;

  }

  /* Pull this right into the normal auth system structures */

  nt_status = make_user_info_dc_pac(tmp_ctx,

           info.logon_info.info,

           upn_dns_info,

           group_inclusion,

           &user_info_dc_out);

  if (!NT_STATUS_IS_OK(nt_status)) {

    DBG_ERR("make_user_info_dc_pac() failed - %s\n",

      nt_errstr(nt_status));

    NDR_PRINT_DEBUG(PAC_LOGON_INFO, info.logon_info.info);

    if (upn_dns_info != NULL) {

      NDR_PRINT_DEBUG(PAC_UPN_DNS_INFO, upn_dns_info);

    }

    talloc_free(tmp_ctx);

    return EINVAL;

  }

  if (pac_srv_sig) {

    ret = krb5_pac_get_buffer(context, pac, PAC_TYPE_SRV_CHECKSUM, &k5pac_srv_checksum_in);

    if (ret != 0) {

      talloc_free(tmp_ctx);

      return ret;

    }

    pac_srv_checksum_in = data_blob_const(k5pac_srv_checksum_in.data, k5pac_srv_checksum_in.length);

    ndr_err = ndr_pull_struct_blob(&pac_srv_checksum_in, pac_srv_sig,

                 pac_srv_sig,

                 (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);

    smb_krb5_free_data_contents(context, &k5pac_srv_checksum_in);

    if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

      nt_status = ndr_map_error2ntstatus(ndr_err);

      DEBUG(0,("can't parse the server signature: %s\n",

         nt_errstr(nt_status)));

      return EINVAL;

    }

  }

  if (pac_kdc_sig) {

    ret = krb5_pac_get_buffer(context, pac, PAC_TYPE_KDC_CHECKSUM, &k5pac_kdc_checksum_in);

    if (ret != 0) {

      talloc_free(tmp_ctx);

      return ret;

    }

    pac_kdc_checksum_in = data_blob_const(k5pac_kdc_checksum_in.data, k5pac_kdc_checksum_in.length);

    ndr_err = ndr_pull_struct_blob(&pac_kdc_checksum_in, pac_kdc_sig,

                 pac_kdc_sig,

                 (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);

    smb_krb5_free_data_contents(context, &k5pac_kdc_checksum_in);

    if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {

      nt_status = ndr_map_error2ntstatus(ndr_err);

      DEBUG(0,("can't parse the KDC signature: %s\n",

         nt_errstr(nt_status)));

      return EINVAL;

    }

  }

  /*

   * Based on the presence of a REQUESTER_SID PAC buffer, ascertain

   * whether the ticket is a TGT. This helps the KDC and kpasswd service

   * ensure they do not accept tickets meant for the other.

   *

   * This heuristic will fail for older Samba versions and Windows prior

   * to Nov. 2021 updates, which lack support for the REQUESTER_SID PAC

   * buffer.

   */

  ret = kerberos_pac_buffer_present(context, pac, PAC_TYPE_REQUESTER_SID);

  if (ret == ENOENT) {

    /* This probably isn't a TGT. */

    user_info_dc_out->ticket_type = TICKET_TYPE_NON_TGT;

  } else if (ret != 0) {

    talloc_free(tmp_ctx);

    return ret;

  } else {

    /* This probably is a TGT. */

    user_info_dc_out->ticket_type = TICKET_TYPE_TGT;

  }

  /*

   * If we have resource groups and the caller wants them returned, we

   * oblige.

   */

  resource_groups_in = &info.logon_info.info->resource_groups;

  if (resource_groups != NULL && resource_groups_in->groups.count != 0) {

    resource_groups_out = talloc(tmp_ctx, struct PAC_DOMAIN_GROUP_MEMBERSHIP);

    if (resource_groups_out == NULL) {

      talloc_free(tmp_ctx);

      return ENOMEM;

    }

    *resource_groups_out = (struct PAC_DOMAIN_GROUP_MEMBERSHIP) {

      .domain_sid = talloc_steal(resource_groups_out, resource_groups_in->domain_sid),

      .groups = {

        .count = resource_groups_in->groups.count,

        .rids = talloc_steal(resource_groups_out, resource_groups_in->groups.rids),

      },

    };

  }

  *user_info_dc = talloc_steal(mem_ctx, user_info_dc_out);

  if (resource_groups_out != NULL) {

    *resource_groups = talloc_steal(mem_ctx, resource_groups_out);

  }

  return 0;

}

NTSTATUS kerberos_pac_blob_to_user_info_dc(TALLOC_CTX *mem_ctx,

             DATA_BLOB pac_blob,

             krb5_context context,

             struct auth_user_info_dc **user_info_dc,

             struct PAC_SIGNATURE_DATA *pac_srv_sig,

             struct PAC_SIGNATURE_DATA *pac_kdc_sig)

{

  krb5_error_code ret;

  krb5_pac pac;

  ret = krb5_pac_parse(context,

           pac_blob.data, pac_blob.length,

           &pac);

  if (ret) {

    return map_nt_error_from_unix_common(ret);

  }

  ret = kerberos_pac_to_user_info_dc(mem_ctx,

             pac,

             context,

             user_info_dc,

             AUTH_INCLUDE_RESOURCE_GROUPS,

             pac_srv_sig,

             pac_kdc_sig,

             NULL);

  krb5_pac_free(context, pac);

  if (ret) {

    return map_nt_error_from_unix_common(ret);

  }

  return NT_STATUS_OK;

}