AppleRecovery.c

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#include <Guid/AppleVariable.h>
 
#include <IndustryStandard/AppleHibernate.h>
 
#include <Library/MemoryAllocationLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DevicePathLib.h>
#include <Library/OcBootManagementLib.h>
#include <Library/OcCryptoLib.h>
#include <Library/OcDevicePathLib.h>
#include <Library/OcDebugLogLib.h>
#include <Library/OcRtcLib.h>
#include <Library/UefiLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>
 
STATIC
EFI_DEVICE_PATH_PROTOCOL *
InternalGetRecoveryInitiator (
  VOID
  )
{
  EFI_STATUS                Status;
  EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
  UINTN                     DevicePathSize;
 
  Status = GetVariable2 (
             APPLE_RECOVERY_BOOT_INITIATOR_VARIABLE_NAME,
             &gAppleVendorVariableGuid,
             (VOID **)&DevicePath,
             &DevicePathSize
             );
  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_INFO, "OCB: No recovery initiator found - %r\n", Status));
    return NULL;
  }
 
  //
  // Also delete recovery initiator just in case.
  //
  gRT->SetVariable (
         APPLE_RECOVERY_BOOT_INITIATOR_VARIABLE_NAME,
         &gAppleVendorVariableGuid,
         EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
         0,
         NULL
         );
 
  if (!IsDevicePathValid (DevicePath, DevicePathSize)) {
    DEBUG ((DEBUG_INFO, "OCB: Recovery initiator (%u) is invalid\n", (UINT32)DevicePathSize));
    FreePool (DevicePath);
    return NULL;
  }
 
  DebugPrintDevicePath (DEBUG_INFO, "OC: Recovery initiator", DevicePath);
  return DevicePath;
}
 
EFI_STATUS
OcHandleRecoveryRequest (
  OUT EFI_DEVICE_PATH_PROTOCOL  **Initiator  OPTIONAL
  )
{
  EFI_STATUS  Status;
  CHAR8       *RecoveryBootMode;
  UINTN       RecoveryBootModeSize;
 
  //
  // Provide basic support for recovery-boot-mode variable, which is meant
  // to perform one-time recovery boot. In general BootOrder and BootNext
  // are set to the recovery path, but this is not the case for secure-boot.
  //
  RecoveryBootModeSize = 0;
  Status               = gRT->GetVariable (
                                APPLE_RECOVERY_BOOT_MODE_VARIABLE_NAME,
                                &gAppleBootVariableGuid,
                                NULL,
                                &RecoveryBootModeSize,
                                NULL
                                );
 
  //
  // Initialise right away.
  //
  if (Initiator != NULL) {
    *Initiator = NULL;
  }
 
  //
  // No need for recovery, this is a normal boot.
  //
  if (Status != EFI_BUFFER_TOO_SMALL) {
    return EFI_NOT_FOUND;
  }
 
  //
  // Debug recovery-boot-mode contents.
  //
  DEBUG_CODE_BEGIN ();
  RecoveryBootMode = AllocatePool (RecoveryBootModeSize + 1);
  if (RecoveryBootMode != NULL) {
    DEBUG ((
      DEBUG_INFO,
      "OCB: Failed to allocate recovery-boot-mode %u\n",
      (UINT32)(RecoveryBootModeSize + 1)
      ));
 
    Status = gRT->GetVariable (
                    APPLE_RECOVERY_BOOT_MODE_VARIABLE_NAME,
                    &gAppleBootVariableGuid,
                    NULL,
                    &RecoveryBootModeSize,
                    RecoveryBootMode
                    );
    if (!EFI_ERROR (Status)) {
      //
      // Ensure null-termination.
      //
      RecoveryBootMode[RecoveryBootModeSize] = '\0';
      DEBUG ((
        DEBUG_INFO,
        "OCB: recovery-boot-mode %u = %a - %r\n",
        (UINT32)RecoveryBootModeSize,
        RecoveryBootMode,
        Status
        ));
    } else {
      DEBUG ((
        DEBUG_INFO,
        "OCB: Failed to obtain recovery-boot-mode %u - %r\n",
        (UINT32)RecoveryBootModeSize,
        Status
        ));
    }
 
    FreePool (RecoveryBootMode);
  } else {
    DEBUG ((
      DEBUG_INFO,
      "OCB: Failed to allocate recovery-boot-mode %u\n",
      (UINT32)(RecoveryBootModeSize + 1)
      ));
  }
 
  DEBUG_CODE_END ();
 
  if (Initiator != NULL) {
    *Initiator = InternalGetRecoveryInitiator ();
  }
 
  //
  // Delete recovery-boot-mode.
  // Failing to do so will result in bootloop at least when SecureBoot is enabled.
  // In other cases EfiBoot may try to chainload into recovery, but it is unreliable.
  //
  gRT->SetVariable (
         APPLE_RECOVERY_BOOT_MODE_VARIABLE_NAME,
         &gAppleBootVariableGuid,
         EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
         0,
         NULL
         );
 
  return EFI_SUCCESS;
}