system76-edk2/MdeModulePkg/Core/Dxe/Misc/InstallConfigurationTable.c

/** @file
  UEFI Miscellaneous boot Services InstallConfigurationTable service

Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "DxeMain.h"

#define CONFIG_TABLE_SIZE_INCREASED 0x10

UINTN mSystemTableAllocateSize = 0;

/**
  Boot Service called to add, modify, or remove a system configuration table from
  the EFI System Table.

  @param  Guid           Pointer to the GUID for the entry to add, update, or
                         remove
  @param  Table          Pointer to the configuration table for the entry to add,
                         update, or remove, may be NULL.

  @return EFI_SUCCESS               Guid, Table pair added, updated, or removed.
  @return EFI_INVALID_PARAMETER     Input GUID is NULL.
  @return EFI_NOT_FOUND             Attempted to delete non-existant entry
  @return EFI_OUT_OF_RESOURCES      Not enough memory available

**/
EFI_STATUS
EFIAPI
CoreInstallConfigurationTable (
  IN EFI_GUID *Guid,
  IN VOID     *Table
  )
{
  UINTN                   Index;
  EFI_CONFIGURATION_TABLE *EfiConfigurationTable;
  EFI_CONFIGURATION_TABLE *OldTable;

  //
  // If Guid is NULL, then this operation cannot be performed
  //
  if (Guid == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  EfiConfigurationTable = gDxeCoreST->ConfigurationTable;

  //
  // Search all the table for an entry that matches Guid
  //
  for (Index = 0; Index < gDxeCoreST->NumberOfTableEntries; Index++) {
    if (CompareGuid (Guid, &(gDxeCoreST->ConfigurationTable[Index].VendorGuid))) {
      break;
    }
  }

  if (Index < gDxeCoreST->NumberOfTableEntries) {
    //
    // A match was found, so this is either a modify or a delete operation
    //
    if (Table != NULL) {
      //
      // If Table is not NULL, then this is a modify operation.
      // Modify the table entry and return.
      //
      gDxeCoreST->ConfigurationTable[Index].VendorTable = Table;

      //
      // Signal Configuration Table change
      //
      CoreNotifySignalList (Guid);

      return EFI_SUCCESS;
    }

    //
    // A match was found and Table is NULL, so this is a delete operation.
    //
    gDxeCoreST->NumberOfTableEntries--;

    //
    // Copy over deleted entry
    //
    CopyMem (
      &(EfiConfigurationTable[Index]),
      &(gDxeCoreST->ConfigurationTable[Index + 1]),
      (gDxeCoreST->NumberOfTableEntries - Index) * sizeof (EFI_CONFIGURATION_TABLE)
      );

  } else {

    //
    // No matching GUIDs were found, so this is an add operation.
    //

    if (Table == NULL) {
      //
      // If Table is NULL on an add operation, then return an error.
      //
      return EFI_NOT_FOUND;
    }

    //
    // Assume that Index == gDxeCoreST->NumberOfTableEntries
    //
    if ((Index * sizeof (EFI_CONFIGURATION_TABLE)) >= mSystemTableAllocateSize) {
      //
      // Allocate a table with one additional entry.
      //
      mSystemTableAllocateSize += (CONFIG_TABLE_SIZE_INCREASED * sizeof (EFI_CONFIGURATION_TABLE));
      EfiConfigurationTable = AllocateRuntimePool (mSystemTableAllocateSize);
      if (EfiConfigurationTable == NULL) {
        //
        // If a new table could not be allocated, then return an error.
        //
        return EFI_OUT_OF_RESOURCES;
      }

      if (gDxeCoreST->ConfigurationTable != NULL) {
        //
        // Copy the old table to the new table.
        //
        CopyMem (
          EfiConfigurationTable,
          gDxeCoreST->ConfigurationTable,
          Index * sizeof (EFI_CONFIGURATION_TABLE)
          );

        //
        // Record the old table pointer.
        //
        OldTable = gDxeCoreST->ConfigurationTable;

        //
        // As the CoreInstallConfigurationTable() may be re-entered by CoreFreePool()
        // in its calling stack, updating System table to the new table pointer must
        // be done before calling CoreFreePool() to free the old table.
        // It can make sure the gDxeCoreST->ConfigurationTable point to the new table
        // and avoid the errors of use-after-free to the old table by the reenter of
        // CoreInstallConfigurationTable() in CoreFreePool()'s calling stack.
        //
        gDxeCoreST->ConfigurationTable = EfiConfigurationTable;

        //
        // Free the old table after updating System Table to the new table pointer.
        //
        CoreFreePool (OldTable);
      } else {
        //
        // Update System Table
        //
        gDxeCoreST->ConfigurationTable = EfiConfigurationTable;
      }
    }

    //
    // Fill in the new entry
    //
    CopyGuid ((VOID *)&EfiConfigurationTable[Index].VendorGuid, Guid);
    EfiConfigurationTable[Index].VendorTable  = Table;

    //
    // This is an add operation, so increment the number of table entries
    //
    gDxeCoreST->NumberOfTableEntries++;
  }

  //
  // Fix up the CRC-32 in the EFI System Table
  //
  CalculateEfiHdrCrc (&gDxeCoreST->Hdr);

  //
  // Signal Configuration Table change
  //
  CoreNotifySignalList (Guid);

  return EFI_SUCCESS;
}