rpc_bind.c

 
#include <freerdp/config.h>
 
#include "../settings.h"
 
#include <winpr/crt.h>
#include <winpr/assert.h>
#include <winpr/cast.h>
 
#include <freerdp/log.h>
 
#include "rpc_client.h"
 
#include "rts.h"
 
#include "rpc_bind.h"
#include "../utils.h"
 
#define TAG FREERDP_TAG("core.gateway.rpc")
 
#define AUTH_PKG NTLM_SSP_NAME
 
/* Syntax UUIDs */
 
const p_uuid_t TSGU_UUID = {
  0x44E265DD,                            /* time_low */
  0x7DAF,                                /* time_mid */
  0x42CD,                                /* time_hi_and_version */
  0x85,                                  /* clock_seq_hi_and_reserved */
  0x60,                                  /* clock_seq_low */
  { 0x3C, 0xDB, 0x6E, 0x7A, 0x27, 0x29 } /* node[6] */
};
 
const p_uuid_t NDR_UUID = {
  0x8A885D04,                            /* time_low */
  0x1CEB,                                /* time_mid */
  0x11C9,                                /* time_hi_and_version */
  0x9F,                                  /* clock_seq_hi_and_reserved */
  0xE8,                                  /* clock_seq_low */
  { 0x08, 0x00, 0x2B, 0x10, 0x48, 0x60 } /* node[6] */
};
 
const p_uuid_t BTFN_UUID = {
  0x6CB71C2C,                            /* time_low */
  0x9812,                                /* time_mid */
  0x4540,                                /* time_hi_and_version */
  0x03,                                  /* clock_seq_hi_and_reserved */
  0x00,                                  /* clock_seq_low */
  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 } /* node[6] */
};
 
static int rpc_bind_setup(rdpRpc* rpc)
{
  SEC_WINNT_AUTH_IDENTITY identity = WINPR_C_ARRAY_INIT;
 
  WINPR_ASSERT(rpc);
 
  rdpContext* context = transport_get_context(rpc->transport);
  WINPR_ASSERT(context);
 
  rdpSettings* settings = context->settings;
  WINPR_ASSERT(settings);
 
  freerdp* instance = context->instance;
  WINPR_ASSERT(instance);
 
  credssp_auth_free(rpc->auth);
  rpc->auth = credssp_auth_new(context);
  if (!rpc->auth)
    return -1;
 
  auth_status rc = utils_authenticate_gateway(instance, GW_AUTH_RPC);
  switch (rc)
  {
    case AUTH_SUCCESS:
    case AUTH_SKIP:
      break;
    case AUTH_CANCELLED:
      freerdp_set_last_error_log(instance->context, FREERDP_ERROR_CONNECT_CANCELLED);
      return -1;
    case AUTH_NO_CREDENTIALS:
      WLog_INFO(TAG, "No credentials provided - using nullptr identity");
      break;
    case AUTH_FAILED:
    default:
      return -1;
  }
 
  if (!credssp_auth_init(rpc->auth, AUTH_PKG, nullptr))
    return -1;
 
  if (!identity_set_from_settings(&identity, settings, FreeRDP_GatewayUsername,
                                  FreeRDP_GatewayDomain, FreeRDP_GatewayPassword))
    return -1;
 
  const char* GatewayHostname = freerdp_settings_get_string(settings, FreeRDP_GatewayHostname);
  const char* GatewayUsername = freerdp_settings_get_string(settings, FreeRDP_GatewayUsername);
 
  SEC_WINNT_AUTH_IDENTITY* identityArg = (GatewayUsername ? &identity : nullptr);
  if (!credssp_auth_setup_client(rpc->auth, nullptr, GatewayHostname, identityArg, nullptr))
  {
    sspi_FreeAuthIdentity(&identity);
    return -1;
  }
  sspi_FreeAuthIdentity(&identity);
 
  credssp_auth_set_flags(rpc->auth, ISC_REQ_USE_DCE_STYLE | ISC_REQ_DELEGATE |
                                        ISC_REQ_REPLAY_DETECT | ISC_REQ_SEQUENCE_DETECT);
 
  if (credssp_auth_authenticate(rpc->auth) < 0)
    return -1;
 
  return 1;
}
 
int rpc_send_bind_pdu(rdpRpc* rpc, BOOL initial)
{
  int status = -1;
  wStream* buffer = nullptr;
  UINT32 offset = 0;
  RpcClientCall* clientCall = nullptr;
  rpcconn_bind_hdr_t bind_pdu = WINPR_C_ARRAY_INIT;
  RpcVirtualConnection* connection = nullptr;
  RpcInChannel* inChannel = nullptr;
  const SecBuffer* sbuffer = nullptr;
 
  WINPR_ASSERT(rpc);
 
  connection = rpc->VirtualConnection;
 
  WINPR_ASSERT(connection);
 
  inChannel = connection->DefaultInChannel;
 
  if (initial && rpc_bind_setup(rpc) < 0)
    return -1;
 
  WLog_DBG(TAG, initial ? "Sending Bind PDU" : "Sending Alter Context PDU");
 
  sbuffer = credssp_auth_get_output_buffer(rpc->auth);
 
  if (!sbuffer)
    goto fail;
 
  bind_pdu.header = rpc_pdu_header_init(rpc);
  bind_pdu.header.auth_length = (UINT16)sbuffer->cbBuffer;
  bind_pdu.auth_verifier.auth_value = sbuffer->pvBuffer;
  bind_pdu.header.ptype = initial ? PTYPE_BIND : PTYPE_ALTER_CONTEXT;
  bind_pdu.header.pfc_flags =
      PFC_FIRST_FRAG | PFC_LAST_FRAG | PFC_SUPPORT_HEADER_SIGN | PFC_CONC_MPX;
  bind_pdu.header.call_id = rpc->CallId++;
  bind_pdu.max_xmit_frag = rpc->max_xmit_frag;
  bind_pdu.max_recv_frag = rpc->max_recv_frag;
  bind_pdu.assoc_group_id = 0;
  bind_pdu.p_context_elem.n_context_elem = 2;
  bind_pdu.p_context_elem.reserved = 0;
  bind_pdu.p_context_elem.reserved2 = 0;
  bind_pdu.p_context_elem.p_cont_elem =
      calloc(bind_pdu.p_context_elem.n_context_elem, sizeof(p_cont_elem_t));
 
  if (!bind_pdu.p_context_elem.p_cont_elem)
    goto fail;
 
  {
    p_cont_elem_t* p_cont_elem = &bind_pdu.p_context_elem.p_cont_elem[0];
    p_cont_elem->p_cont_id = 0;
    p_cont_elem->n_transfer_syn = 1;
    p_cont_elem->reserved = 0;
    CopyMemory(&(p_cont_elem->abstract_syntax.if_uuid), &TSGU_UUID, sizeof(p_uuid_t));
    p_cont_elem->abstract_syntax.if_version = TSGU_SYNTAX_IF_VERSION;
    rts_syntax_id_free(p_cont_elem->transfer_syntaxes);
    p_cont_elem->transfer_syntaxes = rts_syntax_id_new(1);
 
    if (!p_cont_elem->transfer_syntaxes)
      goto fail;
 
    CopyMemory(&(p_cont_elem->transfer_syntaxes[0].if_uuid), &NDR_UUID, sizeof(p_uuid_t));
    p_cont_elem->transfer_syntaxes[0].if_version = NDR_SYNTAX_IF_VERSION;
  }
  {
    p_cont_elem_t* p_cont_elem = &bind_pdu.p_context_elem.p_cont_elem[1];
    p_cont_elem->p_cont_id = 1;
    p_cont_elem->n_transfer_syn = 1;
    p_cont_elem->reserved = 0;
    CopyMemory(&(p_cont_elem->abstract_syntax.if_uuid), &TSGU_UUID, sizeof(p_uuid_t));
    p_cont_elem->abstract_syntax.if_version = TSGU_SYNTAX_IF_VERSION;
 
    rts_syntax_id_free(p_cont_elem->transfer_syntaxes);
    p_cont_elem->transfer_syntaxes = rts_syntax_id_new(1);
 
    if (!p_cont_elem->transfer_syntaxes)
      goto fail;
 
    CopyMemory(&(p_cont_elem->transfer_syntaxes[0].if_uuid), &BTFN_UUID, sizeof(p_uuid_t));
    p_cont_elem->transfer_syntaxes[0].if_version = BTFN_SYNTAX_IF_VERSION;
    offset = 116;
  }
 
  bind_pdu.auth_verifier.auth_type =
      rpc_auth_pkg_to_security_provider(credssp_auth_pkg_name(rpc->auth));
  bind_pdu.auth_verifier.auth_level = RPC_C_AUTHN_LEVEL_PKT_INTEGRITY;
  bind_pdu.auth_verifier.auth_reserved = 0x00;
  bind_pdu.auth_verifier.auth_context_id = 0x00000000;
  offset += (8 + bind_pdu.header.auth_length);
 
  WINPR_ASSERT(offset <= UINT16_MAX);
  bind_pdu.header.frag_length = (UINT16)offset;
 
  buffer = Stream_New(nullptr, bind_pdu.header.frag_length);
 
  if (!buffer)
    goto fail;
 
  if (!rts_write_pdu_bind(buffer, &bind_pdu))
    goto fail;
 
  clientCall = rpc_client_call_new(bind_pdu.header.call_id, 0);
 
  if (!clientCall)
    goto fail;
 
  if (!rpc_client_call_add(rpc->log, rpc->client, clientCall))
  {
    rpc_client_call_free(clientCall);
    goto fail;
  }
 
  Stream_SealLength(buffer);
  status = rpc_in_channel_send_pdu(inChannel, Stream_Buffer(buffer), Stream_Length(buffer));
fail:
  if (status <= 0)
    rpc_client_call_discard(rpc->log, rpc->client, bind_pdu.header.call_id);
 
  if (bind_pdu.p_context_elem.p_cont_elem)
  {
    rts_syntax_id_free(bind_pdu.p_context_elem.p_cont_elem[0].transfer_syntaxes);
    rts_syntax_id_free(bind_pdu.p_context_elem.p_cont_elem[1].transfer_syntaxes);
  }
 
  free(bind_pdu.p_context_elem.p_cont_elem);
  bind_pdu.p_context_elem.p_cont_elem = nullptr;
 
  Stream_Free(buffer, TRUE);
  return (status > 0) ? 1 : -1;
}
 
BOOL rpc_recv_bind_ack_pdu(rdpRpc* rpc, wStream* s)
{
  BOOL rc = FALSE;
  const BYTE* auth_data = nullptr;
  size_t pos = 0;
  size_t end = 0;
  rpcconn_hdr_t header = WINPR_C_ARRAY_INIT;
  SecBuffer buffer = WINPR_C_ARRAY_INIT;
 
  WINPR_ASSERT(rpc);
  WINPR_ASSERT(rpc->auth);
  WINPR_ASSERT(s);
 
  pos = Stream_GetPosition(s);
  if (!rts_read_pdu_header(s, &header))
    goto fail;
 
  WLog_DBG(TAG, header.common.ptype == PTYPE_BIND_ACK ? "Receiving BindAck PDU"
                                                      : "Receiving AlterContextResp PDU");
 
  const UINT16 MAX_VALID_FRAG = 0x0FF8;
  if ((header.bind_ack.max_xmit_frag > MAX_VALID_FRAG) ||
      (header.bind_ack.max_recv_frag > MAX_VALID_FRAG))
  {
    WLog_ERR(TAG,
             "bind_ack: invalid fragment size: max_xmit_frag=%" PRIu16
             ", max_recv_frag=%" PRIu16 ", maximum=%" PRIu16,
             header.bind_ack.max_xmit_frag, header.bind_ack.max_recv_frag, MAX_VALID_FRAG);
    goto fail;
  }
 
  rpc->max_recv_frag = header.bind_ack.max_xmit_frag;
  rpc->max_xmit_frag = header.bind_ack.max_recv_frag;
 
  /* Get the correct offset in the input data and pass that on as input buffer.
   * rts_read_pdu_header did already do consistency checks */
  end = Stream_GetPosition(s);
  if (!Stream_SetPosition(s, pos + header.common.frag_length - header.common.auth_length))
    goto fail;
  auth_data = Stream_ConstPointer(s);
  if (!Stream_SetPosition(s, end))
    goto fail;
 
  buffer.cbBuffer = header.common.auth_length;
  buffer.pvBuffer = malloc(buffer.cbBuffer);
  if (!buffer.pvBuffer)
    goto fail;
  memcpy(buffer.pvBuffer, auth_data, buffer.cbBuffer);
  credssp_auth_take_input_buffer(rpc->auth, &buffer);
 
  if (credssp_auth_authenticate(rpc->auth) < 0)
    goto fail;
 
  rc = TRUE;
fail:
  rts_free_pdu_header(&header, FALSE);
  return rc;
}
 
int rpc_send_rpc_auth_3_pdu(rdpRpc* rpc)
{
  int status = -1;
  wStream* buffer = nullptr;
  size_t offset = 0;
  const SecBuffer* sbuffer = nullptr;
  RpcClientCall* clientCall = nullptr;
  rpcconn_rpc_auth_3_hdr_t auth_3_pdu = WINPR_C_ARRAY_INIT;
  RpcVirtualConnection* connection = nullptr;
  RpcInChannel* inChannel = nullptr;
 
  WINPR_ASSERT(rpc);
 
  connection = rpc->VirtualConnection;
  WINPR_ASSERT(connection);
 
  inChannel = connection->DefaultInChannel;
  WINPR_ASSERT(inChannel);
 
  WLog_DBG(TAG, "Sending RpcAuth3 PDU");
 
  sbuffer = credssp_auth_get_output_buffer(rpc->auth);
 
  if (!sbuffer)
    goto fail;
 
  auth_3_pdu.header = rpc_pdu_header_init(rpc);
  auth_3_pdu.header.auth_length = (UINT16)sbuffer->cbBuffer;
  auth_3_pdu.auth_verifier.auth_value = sbuffer->pvBuffer;
  auth_3_pdu.header.ptype = PTYPE_RPC_AUTH_3;
  auth_3_pdu.header.pfc_flags = PFC_FIRST_FRAG | PFC_LAST_FRAG | PFC_CONC_MPX;
  auth_3_pdu.header.call_id = rpc->CallId++;
  auth_3_pdu.max_xmit_frag = rpc->max_xmit_frag;
  auth_3_pdu.max_recv_frag = rpc->max_recv_frag;
  offset = 20;
 
  const size_t align = rpc_offset_align(&offset, 4);
  WINPR_ASSERT(align <= UINT8_MAX);
  auth_3_pdu.auth_verifier.auth_pad_length = (BYTE)align;
  auth_3_pdu.auth_verifier.auth_type =
      rpc_auth_pkg_to_security_provider(credssp_auth_pkg_name(rpc->auth));
  auth_3_pdu.auth_verifier.auth_level = RPC_C_AUTHN_LEVEL_PKT_INTEGRITY;
  auth_3_pdu.auth_verifier.auth_reserved = 0x00;
  auth_3_pdu.auth_verifier.auth_context_id = 0x00000000;
  offset += (8 + auth_3_pdu.header.auth_length);
 
  WINPR_ASSERT(offset <= UINT16_MAX);
  auth_3_pdu.header.frag_length = (UINT16)offset;
 
  buffer = Stream_New(nullptr, auth_3_pdu.header.frag_length);
 
  if (!buffer)
    goto fail;
 
  if (!rts_write_pdu_auth3(buffer, &auth_3_pdu))
    goto fail;
 
  clientCall = rpc_client_call_new(auth_3_pdu.header.call_id, 0);
 
  if (rpc_client_call_add(rpc->log, rpc->client, clientCall))
  {
    Stream_SealLength(buffer);
    status = rpc_in_channel_send_pdu(inChannel, Stream_Buffer(buffer), Stream_Length(buffer));
  }
  else
    rpc_client_call_free(clientCall);
 
fail:
  if (status <= 0)
    rpc_client_call_discard(rpc->log, rpc->client, auth_3_pdu.header.call_id);
  Stream_Free(buffer, TRUE);
  return (status > 0) ? 1 : -1;
}
 
enum RPC_BIND_STATE rpc_bind_state(rdpRpc* rpc)
{
  BOOL complete = 0;
  BOOL have_token = 0;
  WINPR_ASSERT(rpc);
 
  complete = credssp_auth_is_complete(rpc->auth);
  have_token = credssp_auth_have_output_token(rpc->auth);
 
  return complete ? (have_token ? RPC_BIND_STATE_LAST_LEG : RPC_BIND_STATE_COMPLETE)
                  : RPC_BIND_STATE_INCOMPLETE;
}
 
BYTE rpc_auth_pkg_to_security_provider(const char* name)
{
  if (strcmp(name, CREDSSP_AUTH_PKG_SPNEGO) == 0)
    return RPC_C_AUTHN_GSS_NEGOTIATE;
  else if (strcmp(name, CREDSSP_AUTH_PKG_NTLM) == 0)
    return RPC_C_AUTHN_WINNT;
  else if (strcmp(name, CREDSSP_AUTH_PKG_KERBEROS) == 0)
    return RPC_C_AUTHN_GSS_KERBEROS;
  else if (strcmp(name, CREDSSP_AUTH_PKG_SCHANNEL) == 0)
    return RPC_C_AUTHN_GSS_SCHANNEL;
  else
    return RPC_C_AUTHN_NONE;
}