# Volatility
# Copyright (C) 2007-2013 Volatility Foundation
#
# This file is part of Volatility.
#
# Volatility 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.
#
# Volatility 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 Volatility.  If not, see <http://www.gnu.org/licenses/>.
#

"""
@author:       Andrew Case
@license:      GNU General Public License 2.0
@contact:      atcuno@gmail.com
@organization: 
"""

import volatility.obj as obj
import volatility.plugins.mac.common as common
import volatility.plugins.mac.lsmod as lsmod

class mac_notifiers(lsmod.mac_lsmod):
    """ Detects rootkits that add hooks into I/O Kit (e.g. LogKext) """

    def _struct_or_class(self, type_name):
        """Return the name of a structure or class. 

        More recent versions of OSX define some types as 
        classes instead of structures, so the naming is
        a little different.   
        """
        if self.addr_space.profile.vtypes.has_key(type_name):
            return type_name
        else:
            return type_name + "_class"

    def calculate(self):
        common.set_plugin_members(self)

        (kernel_symbol_addresses, kmods) = common.get_kernel_addrs(self)
        gnotify_addr = common.get_cpp_sym("gNotifications", self.addr_space.profile)
        p = obj.Object("Pointer", offset = gnotify_addr, vm = self.addr_space)
        gnotifications = p.dereference_as(self._struct_or_class("OSDictionary"))

        ents = obj.Object('Array', offset = gnotifications.dictionary, 
                          vm = self.addr_space, 
                          targetType = self._struct_or_class("dictEntry"), 
                          count = gnotifications.count)

        # walk the current set of notifications
        for ent in ents:

            if ent == None:
                continue

            key = str(ent.key.dereference_as(self._struct_or_class("OSString")))

            # get the value
            valset = ent.value.dereference_as(self._struct_or_class("OSOrderedSet"))

            notifiers_ptrs = obj.Object('Array', offset = valset.array, 
                                        vm = self.addr_space, 
                                        targetType = 'Pointer', 
                                        count = valset.count)
            
            for ptr in notifiers_ptrs:
                notifier = ptr.dereference_as(self._struct_or_class("_IOServiceNotifier"))

                if notifier == None:
                    continue

                matches = self.get_matching(notifier)

                # this is the function that handles whatever the notification is for
                # this should be only in the kernel or in one of the known IOKit 
                # drivers for the specific kernel
                handler = notifier.handler

                good = common.is_known_address(handler, kernel_symbol_addresses, kmods)
                yield (good, key, notifier, matches)

    # returns the list of matching notifiers (serviceMatch) for a notifier as a string
    def get_matching(self, notifier):
        matches = []
    
        ents = obj.Object('Array', offset = notifier.matching.dictionary, 
                          vm = self.addr_space, 
                          targetType = self._struct_or_class("dictEntry"), 
                          count = notifier.matching.count)

        for ent in ents:
            if ent == None:
                continue

            match = ent.value.dereference_as(self._struct_or_class("OSString"))        
            matches.append(str(match))

        return ",".join(matches)

    def render_text(self, outfd, data):
        self.table_header(outfd, [("Status", "10"), 
                                  ("Key", "30"), 
                                  ("Handler", "[addrpad]"), 
                                  ("Matches", "")])

        for (good, key, notifier, matches) in data:

            if good == 0:
                status = "UNKNOWN"
            else:
                status = "OK"

            self.table_row(outfd, status, key, notifier.handler, matches)
