pykd/snippets/ntobj.py

# 
# Work with NT Object tree manager
# 
# To use:
# 
#   ntobj.getType(p)
#     query object type by object pointer
# 
#   ntobj.getListByHandleTable(pHandleTable, pType=0, bContainHeaders=True)
#     build object list from handle table
# 

from pykd import *

def getTypeWin7(p):
  """
  Get object header by object pointer
  Implementation for Win7+
  """
  pHeader = containingRecord(p, "nt", "_OBJECT_HEADER", "Body")
  pTypeIndexTable = getOffset("nt", "ObTypeIndexTable")
  return ptrPtr(pTypeIndexTable + (ptrSize() * pHeader.TypeIndex))

def getTypeLegacy(p):
  """
  Get object header by object pointer
  Implementation for before Win7
  """
  pHeader = containingRecord(p, "nt", "_OBJECT_HEADER", "Body")
  return pHeader.Type

# Select platform-specific function for getting object header
if (ptrWord(getOffset("nt", "NtBuildNumber")) >= 7600):
  getType = getTypeWin7
else:
  getType = getTypeLegacy

HANDLE_VALUE_INC = 4
HT_PAGE_SIZE = 4096
HT_ENTRY_SIZE = (2 * ptrSize())
HT_LOWLEVEL_COUNT = HT_PAGE_SIZE // HT_ENTRY_SIZE
HT_MIDLEVEL_COUNT = HT_PAGE_SIZE // ptrSize()

def getListByHandleTable(pHandleTable, pType=0, bContainHeaders=True):
  """ 
  Build list of objects from target handle table

  Parameter pType if not 0 used for getting object of specific type,
  otherwise get object of all types

  Parameter bContainHeaders used to interpret table contents: 
  if bContainHeaders=True then table contains pointers to nt!_OBJECT_HEADER, 
  otherwise table contains pointers to objects
  """

  def getByHandleEntry(hEntry, bContainHeader):
    """
    Query object pointer by handle entry from handle table
    """
    if (0 == hEntry):
      return 0
  
    HandleEntry = typedVar("nt", "_HANDLE_TABLE_ENTRY", hEntry)
    if (0xFFFFFFFE == HandleEntry.NextFreeTableEntry):
      return 0

    p = ptrPtr(HandleEntry.getAddress()) & 0xFFFFFFFFFFFFFFF8
    if (0 == p):
      return 0

    if (bContainHeader):
      pHeader = typedVar("nt", "_OBJECT_HEADER", p)
      p = pHeader.Body.getAddress()
    return p

  def getListByHandleTableL0(pTableContent, nMaxHandleIndex, pType, bContainHeaders):
    """
    Build list of objects from target handle table level 0
    """
    lstObjects = list()
    nTableLevel0Count = nMaxHandleIndex // HANDLE_VALUE_INC
    for HandleEntryIndex in range(nTableLevel0Count):

      pHandleEntry = pTableContent + (HT_ENTRY_SIZE * HandleEntryIndex)
      p = getByHandleEntry(pHandleEntry, bContainHeaders)
      if (0 == p):
        continue

      if (0 == pType):
        lstObjects.append(p)
      else:
        pCurrentType = getType(p)
        if (addr64(pType) == addr64(pCurrentType)):
          lstObjects.append(p)

    return lstObjects

  def getListByHandleTableL1(pTableContent, nMaxHandleIndex, pType, bContainHeaders):
    """
    Build list of objects from target handle table level 1
    """
    lstObjects = list()
    nTableLevel1Count = (nMaxHandleIndex // HANDLE_VALUE_INC) // HT_LOWLEVEL_COUNT
    for Index in range(nTableLevel1Count):
      pTableLevel0 = ptrPtr(pTableContent + (Index * ptrSize()))
      lstObjects += getListByHandleTableL0(pTableLevel0, HT_LOWLEVEL_COUNT * HANDLE_VALUE_INC, pType, bContainHeaders)

    return lstObjects

  def getListByHandleTableL2(pTableContent, nMaxHandleIndex, pType, bContainHeaders):
    """
    Build list of objects from target handle table level 2
    """
    lstObjects = list()
    nTableLevel2Count = ((nMaxHandleIndex // HANDLE_VALUE_INC) // HT_LOWLEVEL_COUNT) // HT_MIDLEVEL_COUNT
    for Index in range(nTableLevel2Count):
      pTableLevel1 = ptrPtr(pTableContent + (Index * ptrSize()))
      lstObjects += getListByHandleTableL1(pTableLevel1, HT_MIDLEVEL_COUNT * HT_LOWLEVEL_COUNT * HANDLE_VALUE_INC, pType, bContainHeaders)

    return lstObjects

  pHandleTable = typedVar("nt", "_HANDLE_TABLE", pHandleTable)
  nMaxHandleIndex = pHandleTable.NextHandleNeedingPool & 0xFFFFFFFF
  nTableLevel = (pHandleTable.TableCode & 3)
  pTableContent = pHandleTable.TableCode - nTableLevel

  if (0 == nTableLevel):
    return getListByHandleTableL0(pTableContent, nMaxHandleIndex, pType, bContainHeaders)
  elif (1 == nTableLevel):
    return getListByHandleTableL1(pTableContent, nMaxHandleIndex, pType, bContainHeaders)
  elif (2 == nTableLevel):
    return getListByHandleTableL2(pTableContent, nMaxHandleIndex, pType, bContainHeaders)

  dprintln("ERROR: Unknown handle table level: %u" % nTableLevel)
  return list()

import sys

if __name__ == "__main__":
  # 
  # Print content of object table (handle table)
  # 
  # Usage:
  # 
  # !py ntobj [ObjectTableAddr] [ContainHeaders=<True|False>, by default is True]
  # 
  # Examples:
  # 
  # !py ntobj.py
  # Print object table of current process
  # 
  # !py ntobj.py aabbccee
  # Print object table by address 0xaabbccee. F.e. address object table 
  # contained in field ObjectTable structure nt!_EPROCESS
  # 
  # !py ntobj.py eeccbbaa False
  # When 0xeeccbbaa is poi(nt!PspCidTable)
  # Print all thread and process
  # 

  def printObjectTable(pObejctTable, bHeaders):
    """
    Print content of object table
    """
    lstObejcts = getListByHandleTable(pObejctTable, bContainHeaders=bHeaders)
    dprintln("%u objects:" % len(lstObejcts))
    for obj in lstObejcts:
      dprintln("obj: 0x%X" % obj + " type: 0x%X" % getType(obj))


  if not isSessionStart():
    print "Script is launch out of WinDBG"
    quit(0)

  argc = len(sys.argv)
  if (1 == argc):
    process = typedVar("nt", "_EPROCESS", getCurrentProcess())
    printObjectTable(process.ObjectTable, True)
  elif (2 == argc):
    printObjectTable(int(sys.argv[1], 16), True)
  elif (3 == argc):
    bHeaders = True
    if (sys.argv[2].lower() == "true"):
      printObjectTable(int(sys.argv[1], 16), True)
    elif (sys.argv[2].lower() == "false"):
      printObjectTable(int(sys.argv[1], 16), False)
    else:
      dprintln("Invalid command line, usage: " + sys.argv[0] + " [ObjectTableAddr] [ContainHeaders=True|False, by default is True]")
  else:
    dprintln("Invalid command line, usage: " + sys.argv[0] + " [ObjectTableAddr] [ContainHeaders=<True|False>, by default is True]")