# Rekall Memory Forensics
# Copyright (c) 2012 Michael Cohen <scudette@gmail.com>
# Copyright (c) 2008 Brendan Dolan-Gavitt <bdolangavitt@wesleyan.edu>
# Copyright 2013 Google Inc. All Rights Reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or (at
# your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#

"""This is the registry parser.

We parse registry structures from files or memory.
"""
__author__ = ("Michael Cohen <scudette@gmail.com> based on original code "
              "by Brendan Dolan-Gavitt")

# pylint: disable=protected-access

import logging
import ntpath
import re
import struct

from rekall import addrspace
from rekall import config
from rekall import obj
from rekall import utils

from rekall.plugins.windows import common


registry_overlays = {
    '_CM_KEY_NODE': [None, {
        'Parent': [None, ['Pointer32', dict(
            target='_CM_KEY_NODE'
            )]],
        'Flags': [None, ['Flags', dict(bitmap={
            "KEY_IS_VOLATILE": 0,
            "KEY_HIVE_EXIT": 1,
            "KEY_HIVE_ENTRY": 2,
            "KEY_NO_DELETE": 3,
            "KEY_SYM_LINK": 4,
            "KEY_COMP_NAME": 5,
            "KEY_PREFEF_HANDLE": 6,
            "KEY_VIRT_MIRRORED": 7,
            "KEY_VIRT_TARGET": 8,
            "KEY_VIRTUAL_STORE": 9,
            })]],

        'Signature' : [None, ['String', dict(length=2)]],
        'LastWriteTime' : [None, ['WinFileTime', {}]],
        'Name' : [None, ['String', dict(length=lambda x: x.NameLength)]],
        }],

    '_CM_KEY_VALUE': [None, {
        'Signature' : [None, ['String', dict(length=2)]],
        'Name' : [None, ['String', dict(length=lambda x: x.NameLength)]],

        'Type': [None, ['Enumeration', dict(choices={
            0: "REG_NONE",
            1: "REG_SZ",
            2: "REG_EXPAND_SZ",
            3: "REG_BINARY",
            4: "REG_DWORD",
            5: "REG_DWORD_BIG_ENDIAN",
            6: "REG_LINK",
            7: "REG_MULTI_SZ",
            8: "REG_RESOURCE_LIST",
            9: "REG_FULL_RESOURCE_DESCRIPTOR",
            10: "REG_RESOURCE_REQUIREMENTS_LIST",
            11: "REG_QWORD",
            })]]
        }],

    '_CM_NAME_CONTROL_BLOCK' : [None, {
        'Name' : [None, ['String', dict(length=lambda x: x.NameLength)]],
        }],

    '_CHILD_LIST' : [None, {
        'List' : [None, ['Pointer32', dict(
            target="Array",
            target_args=dict(
                count=lambda x: x.Count,
                target="Pointer32",
                target_args=dict(
                    target="_CM_KEY_VALUE"
                    )
                )
            )
                         ]],
        }],

    '_CM_KEY_INDEX' : [None, {
        'Signature' : [None, ['String', dict(length=2)]],
        'List' : [None, ["Array", dict(
            count=lambda x: x.Count.v() * 2,
            target="Pointer32",
            target_args=dict(
                target='_CM_KEY_NODE'
                )
            )]],
        }],
    }


class Pointer32(obj.Pointer):
    """A 32 bit pointer (Even in 64 bit arch).

    These kinds of pointers are used most commonly in the Registry code which
    always treats the hives as 32 bit address spaces.
    """
    def __init__(self, **kwargs):
        super(Pointer32, self).__init__(**kwargs)
        self._proxy = self._proxy.cast("unsigned int")


class HiveBaseAddressSpace(addrspace.PagedReader):
    __abstract = True
    BLOCK_SIZE = PAGE_SIZE = 0x1000


class HiveFileAddressSpace(HiveBaseAddressSpace):
    """Translate between hive addresses and a flat file address space.

    This is suitable for reading regular registry files. It should be
    stacked over the FileAddressSpace.
    """
    def __init__(self, **kwargs):
        super(HiveFileAddressSpace, self).__init__(**kwargs)
        self.as_assert(self.base, "Must stack on top of a file.")
        self.as_assert(self.base.read(0, 4) == "regf", "File does not look "
                       "like a registry file.")

    def vtop(self, vaddr):
        return vaddr + self.PAGE_SIZE + 4

    @property
    def Name(self):
        return self.base


class HiveAddressSpace(HiveBaseAddressSpace):
    CI_TYPE_MASK = 0x80000000
    CI_TYPE_SHIFT = 0x1F
    CI_TABLE_MASK = 0x7FE00000
    CI_TABLE_SHIFT = 0x15
    CI_BLOCK_MASK = 0x1FF000
    CI_BLOCK_SHIFT = 0x0C
    CI_OFF_MASK = 0x0FFF
    CI_OFF_SHIFT = 0x0

    def __init__(self, hive_addr=None, profile=None, **kwargs):
        """Translate between hive addresses and virtual memory addresses.

        This must be constructed over the kernel virtual memory.
        Args:
           hive_addr: The virtual address of the _CMHIVE object.
           profile: A profile which holds registry symbols.
        """
        super(HiveAddressSpace, self).__init__(**kwargs)

        self.as_assert(hive_addr, "Hive offset not provided.")
        self.as_assert(self.base, "Must be layered on kernel address space.")
        self.profile = RekallRegisteryImplementation(
            profile or self.session.profile)

        self.hive = self.profile._CMHIVE(offset=hive_addr, vm=self.base)
        self.baseblock = self.hive.Hive.BaseBlock.v()
        self.flat = self.hive.Hive.Flat.v() > 0
        self.storage = self.hive.Hive.Storage

        # This is a quick lookup for blocks.
        self.block_cache = utils.FastStore(max_size=1000)

    def vtop(self, vaddr):
        # If the hive is listed as "flat", it is all contiguous in memory
        # so we can just calculate it relative to the base block.
        if self.flat:
            return self.baseblock + vaddr + self.BLOCK_SIZE + 4

        ci_type = (vaddr & self.CI_TYPE_MASK) >> self.CI_TYPE_SHIFT
        ci_table = (vaddr & self.CI_TABLE_MASK) >> self.CI_TABLE_SHIFT
        ci_block = (vaddr & self.CI_BLOCK_MASK) >> self.CI_BLOCK_SHIFT
        ci_off = (vaddr & self.CI_OFF_MASK) >> self.CI_OFF_SHIFT

        try:
            block = self.block_cache.Get((ci_type, ci_table, ci_block))
        except KeyError:
            block = self.storage[ci_type].Map.Directory[ci_table].Table[
                ci_block].BlockAddress

            self.block_cache.Put((ci_type, ci_table, ci_block), block)

        return block + ci_off + 4

    def save(self):
        """A generator of registry data in linear form.

        This can be used to write a registry file.

        Yields:
           blocks of data in order.
        """
        baseblock = self.base.read(self.baseblock, self.BLOCK_SIZE)
        if baseblock:
            yield baseblock
        else:
            yield "\0" * self.BLOCK_SIZE

        length = self.hive.Hive.Storage[0].Length.v()
        for i in xrange(0, length, self.BLOCK_SIZE):
            paddr = self.vtop(i)
            if not paddr:
                logging.warn("No mapping found for index {0:x}, "
                             "filling with NULLs".format(i))
                data = '\0' * self.BLOCK_SIZE
            else:
                paddr = paddr - 4
                data = self.base.read(paddr, self.BLOCK_SIZE)
                if not data:
                    logging.warn("Physical layer returned None for index "
                                 "{0:x}, filling with NULL".format(i))
                    data = '\0' * self.BLOCK_SIZE

            yield data

    def stats(self, stable=True):
        if stable:
            stor = 0
            ci = lambda x: x
        else:
            stor = 1
            ci = lambda x: x | 0x80000000

        length = self.hive.Hive.Storage[stor].Length.v()
        total_blocks = length / self.BLOCK_SIZE
        bad_blocks_reg = 0
        bad_blocks_mem = 0
        for i in xrange(0, length, self.BLOCK_SIZE):
            i = ci(i)
            data = None
            paddr = self.vtop(i) - 4

            if paddr:
                data = self.base.read(paddr, self.BLOCK_SIZE)
            else:
                bad_blocks_reg += 1
                continue

            if not data:
                bad_blocks_mem += 1

        print "{0} bytes in hive.".format(length)
        print ("{0} blocks not loaded by CM, {1} blocks "
               "paged out, {2} total blocks.".format(
                bad_blocks_reg, bad_blocks_mem, total_blocks))

        if total_blocks:
            print "Total of {0:.2f}% of hive unreadable.".format(
                ((bad_blocks_reg + bad_blocks_mem) / float(total_blocks)
                 ) * 100)

        return (bad_blocks_reg, bad_blocks_mem, total_blocks)

    @property
    def Name(self):
        return self.hive.Name


class _CMHIVE(obj.Struct):
    @property
    def Name(self):
        name = "[no name]"
        try:
            name = (self.FileFullPath.v() or self.FileUserName.v() or
                    self.HiveRootPath.v())
        except AttributeError:
            pass

        return u"{0} @ {1:#010x}".format(name, self.obj_offset)


class _CM_KEY_NODE(obj.Struct):
    """A registry key."""
    NK_SIG = "nk"
    VK_SIG = "vk"

    def open_subkey(self, subkey_name):
        """Opens our direct child."""
        for subkey in self.subkeys():
            if unicode(subkey.Name).lower() == subkey_name.lower():
                return subkey

        return obj.NoneObject("Couldn't find subkey {0} of {1}".format(
            subkey_name, self.Name))

    def open_value(self, value_name):
        """Opens our direct child."""
        for value in self.values():
            if value.Name == value_name:
                return value

        return obj.NoneObject("Couldn't find subkey {0} of {1}".format(
            value_name, self.Name))

    def subkeys(self):
        """Enumeate all subkeys of this key.

        How are subkeys stored in each key record?

        There are usually two subkey lists - these are pointers to _CM_KEY_INDEX
        which are just a list of pointers to other subkeys.
        """
        # There are multiple lists of subkeys:
        sk_lists = self.SubKeyLists
        for list_index, count in enumerate(self.SubKeyCounts):
            if count > 0:
                sk_offset = sk_lists[list_index]
                for subkey in self.obj_profile._CM_KEY_INDEX(
                    offset=sk_offset, vm=self.obj_vm, parent=self):
                    yield subkey

    def values(self):
        """Enumerate all the values of the key."""
        for value_ptr in self.ValueList.List.dereference():
            value = value_ptr.dereference()
            if value.Signature == self.VK_SIG:
                yield value

    @property
    def Path(self):
        """Traverse our parent objects to print the full path of this key."""
        path = []
        key = self
        while key:
            try:
                path.append(unicode(key.Name))
            except AttributeError:
                pass
            key = key.obj_parent

        return "/".join(reversed(path))

    @property
    def Name(self):
        """The name of the key is actually a unicode object.
        This is encoded either in ascii or utf16 according to the Flags.
        """
        if self.Flags.KEY_COMP_NAME:
            return self.obj_profile.String(
                vm=self.obj_vm, offset=self.obj_profile.get_obj_offset(
                    self.obj_type, "Name") + self.obj_offset,
                length=self.NameLength)
        else:
            return self.obj_profile.UnicodeString(
                vm=self.obj_vm, offset=self.obj_profile.get_obj_offset(
                    self.obj_type, "Name") + self.obj_offset,
                length=self.NameLength, encoding="utf-16")



class _CM_KEY_INDEX(obj.Struct):
    """This is a list of pointers to key nodes.

    This work different depending on the Signature.
    """
    LH_SIG = "lh"
    LF_SIG = "lf"
    RI_SIG = "ri"
    LI_SIG = "li"
    NK_SIG = "nk"

    def __iter__(self):
        """Iterate over all the keys in the index.

        Depending on our type (from the Signature) we use different methods."""
        if self.Signature == self.LH_SIG or self.Signature == self.LF_SIG:
            # The List contains alternating pointers/hash elements here. We do
            # not care about the hash at all, so we skip every other entry. See
            # http://www.sentinelchicken.com/data/TheWindowsNTRegistryFileFormat.pdf
            key_list = self.List
            for i in xrange(self.Count * 2):
                nk = key_list[i]
                if nk.Signature == self.NK_SIG:
                    yield nk

        elif self.Signature == self.RI_SIG:
            for i in xrange(self.Count):
                # This is a pointer to another _CM_KEY_INDEX
                for subkey in self.obj_profile.Object(
                    "Pointer32", offset=self.List[i].v(),
                    vm=self.obj_vm, parent=self.obj_parent,
                    target="_CM_KEY_INDEX"):
                    if subkey.Signature == self.NK_SIG:
                        yield subkey

        elif self.Signature == self.LI_SIG:
            key_list = self.List
            for i in xrange(self.Count):
                nk = key_list[i]
                if nk.Signature == self.NK_SIG:
                    yield nk


class _CM_KEY_VALUE(obj.Struct):
    """A registry value."""

    value_formats = {"REG_DWORD": "<L",
                     "REG_DWORD_BIG_ENDIAN": ">L",
                     "REG_QWORD": "<Q"}

    @property
    def DecodedData(self):
        """Returns the data for this key decoded according to the type."""
        # When the data length is 0x80000000, the value is stored in the type
        # (as a REG_DWORD).
        if self.DataLength == 0x80000000:
            return self.Type.v()

        # If the high bit is set, the data is stored inline
        elif self.DataLength & 0x80000000:
            return self._decode_data(self.obj_vm.read(
                    self.m("Data").obj_offset, self.DataLength & 0x7FFFFFFF))

        elif self.DataLength > 0x4000:
            return obj.NoneObject("Big data not supported.")

            big_data = self.obj_profile._CM_BIG_DATA(
                self.Data, vm=self.obj_vm)

            return self._decode_data(big_data.Data)

        else:
            return self._decode_data(self.obj_vm.read(
                    int(self.m("Data")), self.DataLength))

    def _decode_data(self, data):
        """Decode the data according to our type."""
        valtype = str(self.Type)

        if valtype in ["REG_DWORD", "REG_DWORD_BIG_ENDIAN", "REG_QWORD"]:
            if len(data) != struct.calcsize(self.value_formats[valtype]):
                return obj.NoneObject(
                    "Value data did not match the expected data "
                    "size for a {0}".format(valtype))

        if valtype in ["REG_SZ", "REG_EXPAND_SZ", "REG_LINK"]:
            data = data.decode('utf-16-le', "ignore")

        elif valtype == "REG_MULTI_SZ":
            data = data.decode('utf-16-le', "ignore").split('\0')

        elif valtype in ["REG_DWORD", "REG_DWORD_BIG_ENDIAN", "REG_QWORD"]:
            data = struct.unpack(self.value_formats[valtype], data)[0]

        return data


def RekallRegisteryImplementation(profile):
    """The standard rekall registry parsing subsystem."""
    profile.add_classes(dict(
        _CM_KEY_NODE=_CM_KEY_NODE, _CM_KEY_INDEX=_CM_KEY_INDEX,
        _CM_KEY_VALUE=_CM_KEY_VALUE, _CMHIVE=_CMHIVE,
        Pointer32=Pointer32
        ))

    profile.add_overlay(registry_overlays)
    return profile


class Registry(object):
    """A High level class to abstract access to the registry hive."""
    ROOT_INDEX = 0x20
    VK_SIG = "vk"

    BIG_DATA_MAGIC = 0x3fd8

    def __init__(self, session=None, profile=None, address_space=None,
                 filename=None, stable=True):
        """Abstract a registry hive.

        Args:
           session: An optional session object.
           profile: A profile to operate on. If not provided we use
             session.profile.
           address_space: An instance of the HiveBaseAddressSpace.
           filename: If the registry exists in a file, specify the filename to
             save instantiating the address_space.
           stable: Should we try to open the unstable registry area?
        """
        self.session = session
        self.profile = RekallRegisteryImplementation(
            profile or session.profile)

        if filename is not None:
            base_as = HiveFileAddressSpace.classes['FileAddressSpace'](
                filename=filename, session=session)
            address_space = HiveFileAddressSpace(base=base_as)

        self.address_space = address_space

        root_index = self.ROOT_INDEX
        if not stable:
            root_index = self.ROOT_INDEX | 0x80000000

        self.root = self.profile.Object(
            "_CM_KEY_NODE", offset=root_index, vm=address_space)

    @property
    def Name(self):
        """Return the name of the registry."""
        return self.address_space.Name

    def open_key(self, key=""):
        """Opens a key.

        Args:
           key: A string path to the key (separated with / or \\) or a list of
              path components (useful if the keyname contains /).
        """
        if isinstance(key, basestring):
            # / can be part of the key name...
            key = filter(None, re.split(r"[\\/]", key))

        result = self.root
        for component in key:
            result = result.open_subkey(component)

        return result

    def open_value(self, path):
        key = self.open_key(ntpath.dirname(path))

        return key.open_value(ntpath.basename(path))

    def CurrentControlSet(self):
        """Return the key for the CurrentControlSet."""
        current = self.open_value("Select/Current").DecodedData
        if not current:
            current = 1

        return self.open_key("ControlSet00%s" % current)


class RegistryHive(Registry):
    def __init__(self, hive_offset=None, kernel_address_space=None,
                 profile=None,
                 session=None, **kwargs):
        """A Registry hive instantiated from the hive offsets.

        Args:
          hive_offset: The virtual offset of the hive.
          kernel_address_space: The kernel address space.
        """
        if session:
            profile = profile or session.profile
            kernel_address_space = (kernel_address_space or
                                    session.kernel_address_space)

        hive_address_space = HiveAddressSpace(base=kernel_address_space,
                                              hive_addr=hive_offset,
                                              profile=profile,
                                              session=session)

        super(RegistryHive, self).__init__(
            session=session, profile=profile, address_space=hive_address_space,
            **kwargs)


class RegistryPlugin(common.WindowsCommandPlugin):
    """A generic registry plugin."""

    __abstract = True

    @classmethod
    def args(cls, parser):
        super(RegistryPlugin, cls).args(parser)

        parser.add_argument(
            "-o", "--hive-offsets", default=None, type="ArrayIntParser",
            help="A list of hive offsets as found by hivelist. "
            "If not provided we call hivescan ourselves and list "
            "the keys on all hives.")

        parser.add_argument("--hive_regex", default=None,
                            help="A regex to filter hive names."
                            "If not provided we use all hives.")


    def __init__(self, hive_offsets=None, hive_regex=None, **kwargs):
        """Operate on in memory registry hives.

        Args:
          hive_offset: A list of hive offsets as found by hivelist (virtual
            address). If not provided we call hivescan ourselves and list the
            key on all hives.
        """
        super(RegistryPlugin, self).__init__(**kwargs)

        # Install our specific implementation of registry support.
        RekallRegisteryImplementation(self.profile)

        self.hive_offsets = hive_offsets
        if not self.hive_offsets:
            self.hive_offsets = list(self.list_hives())

        if hive_regex is not None:
            hive_offsets = []
            for hive in self.hive_offsets:
                m = re.search(hive_regex, utils.SmartUnicode(hive.Name))
                if m:
                    hive_offsets.append(hive)

            self.hive_offsets = hive_offsets

    def list_hives(self):
        hive_list = self.profile.get_constant_object(
            "CmpHiveListHead", "_LIST_ENTRY")

        return hive_list.list_of_type("_CMHIVE", "HiveList")


class Hives(RegistryPlugin):
    """List all the registry hives on the system."""

    name = "hives"

    def render(self, renderer):
        renderer.table_header([("Offset", "offset", "[addrpad]"),
                               ("Name", "name", "")])

        for hive in self.list_hives():
            renderer.table_row(hive, hive.Name)
