/**
 * @file syscall-sysret.cpp
 * @author Sina Karvandi (sina@rayanfam.com)
 * @brief !syscall and !sysret commands
 * @details
 * @version 0.1
 * @date 2020-05-27
 *
 * @copyright This project is released under the GNU Public License v3.
 *
 */
#include "pch.h"

/**
 * @brief help of !syscall command
 *
 * @return VOID
 */
VOID CommandSyscallHelp() {
  ShowMessages("!syscall : Monitors and hooks all execution of syscall "
               "instructions.\n\n");
  ShowMessages("syntax : \t!syscall [syscall num (hex)] core [core index "
               "(hex value)] pid [process id (hex value)] condition {[assembly "
               "in hex]} code {[assembly in hex]} buffer [pre-require buffer - "
               "(hex value)] \n");

  ShowMessages("\t\te.g : !syscall\n");
  ShowMessages("\t\te.g : !syscall 0x55\n");
  ShowMessages("\t\te.g : !syscall 0x55 pid 400\n");
  ShowMessages("\t\te.g : !syscall 0x55 core 2 pid 400\n");
}

/**
 * @brief help of !sysret command
 *
 * @return VOID
 */
VOID CommandSysretHelp() {
  ShowMessages("!sysret : Monitors and hooks all execution of sysret "
               "instructions.\n\n");
  ShowMessages("syntax : \t!sysret core [core index "
               "(hex value)] pid [process id (hex value)] condition {[assembly "
               "in hex]} code {[assembly in hex]} buffer [pre-require buffer - "
               "(hex value)] \n");

  ShowMessages("\t\te.g : !sysret\n");
  ShowMessages("\t\te.g : !sysret pid 400\n");
  ShowMessages("\t\te.g : !sysret core 2 pid 400\n");
}

/**
 * @brief !syscall and !sysret commands handler
 *
 * @param SplittedCommand
 */
void CommandSyscallAndSysret(vector<string> SplittedCommand) {

  PDEBUGGER_GENERAL_EVENT_DETAIL Event = NULL;
  PDEBUGGER_GENERAL_ACTION ActionBreakToDebugger = NULL;
  PDEBUGGER_GENERAL_ACTION ActionCustomCode = NULL;
  PDEBUGGER_GENERAL_ACTION ActionScript = NULL;
  UINT32 EventLength;
  UINT32 ActionBreakToDebuggerLength = 0;
  UINT32 ActionCustomCodeLength = 0;
  UINT32 ActionScriptLength = 0;
  UINT64 SpecialTarget = DEBUGGER_EVENT_SYSCALL_ALL_SYSRET_OR_SYSCALLS;
  BOOLEAN GetSyscallNumber = FALSE;

  //
  // Interpret and fill the general event and action fields
  //
  //
  if (!SplittedCommand.at(0).compare("!syscall")) {
    if (!InterpretGeneralEventAndActionsFields(
            &SplittedCommand, SYSCALL_HOOK_EFER_SYSCALL, &Event, &EventLength,
            &ActionBreakToDebugger, &ActionBreakToDebuggerLength,
            &ActionCustomCode, &ActionCustomCodeLength, &ActionScript,
            &ActionScriptLength)) {
      CommandSyscallHelp();
      return;
    }
  } else {
    if (!InterpretGeneralEventAndActionsFields(
            &SplittedCommand, SYSCALL_HOOK_EFER_SYSRET, &Event, &EventLength,
            &ActionBreakToDebugger, &ActionBreakToDebuggerLength,
            &ActionCustomCode, &ActionCustomCodeLength, &ActionScript,
            &ActionScriptLength)) {
      CommandSysretHelp();
      return;
    }
  }

  //
  // Interpret command specific details (if any)
  //

  //
  // Currently we do not support any extra argument for !sysret command
  // it is because we don't know how to find syscall number in sysret
  // and we don't wanna deal with dynamic mapping of rcx (user stack)
  // in vmx-root
  //
  if (!SplittedCommand.at(0).compare("!syscall")) {

    for (auto Section : SplittedCommand) {
      if (!Section.compare("!syscall") || !Section.compare("!sysret")) {
        continue;
      } else if (!GetSyscallNumber) {

        //
        // It's probably a syscall address
        //
        if (!ConvertStringToUInt64(Section, &SpecialTarget)) {

          //
          // Unkonwn parameter
          //
          ShowMessages("Unknown parameter '%s'\n\n", Section.c_str());
          if (!SplittedCommand.at(0).compare("!syscall")) {
            CommandSyscallHelp();

          } else {
            CommandSysretHelp();
          }
          return;
        } else {
          GetSyscallNumber = TRUE;
        }
      } else {

        //
        // Unkonwn parameter
        //
        ShowMessages("Unknown parameter '%s'\n\n", Section.c_str());
        if (!SplittedCommand.at(0).compare("!syscall")) {
          CommandSyscallHelp();

        } else {
          CommandSysretHelp();
        }
        return;
      }
    }

    //
    // Set the target syscall
    //
    Event->OptionalParam1 = SpecialTarget;
  }

  //
  // Send the ioctl to the kernel for event registeration
  //
  if (!SendEventToKernel(Event, EventLength)) {

    //
    // There was an error, probably the handle was not initialized
    // we have to free the Action before exit, it is because, we
    // already freed the Event and string buffers
    //
    if (ActionBreakToDebugger != NULL) {
      free(ActionBreakToDebugger);
    }
    if (ActionCustomCode != NULL) {
      free(ActionCustomCode);
    }
    if (ActionScript != NULL) {
      free(ActionScript);
    }
    return;
  }

  //
  // Add the event to the kernel
  //
  if (!RegisterActionToEvent(ActionBreakToDebugger, ActionBreakToDebuggerLength,
                             ActionCustomCode, ActionCustomCodeLength,
                             ActionScript, ActionScriptLength)) {
    //
    // There was an error
    //
    return;
  }
}