mirror of
https://github.com/volatilityfoundation/volatility
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iMHLv2
224 lines
8.1 KiB
Python
224 lines
8.1 KiB
Python
# Volatility
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#
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# Authors:
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# Mike Auty <mike.auty@gmail.com>
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#
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# This file is part of Volatility.
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#
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# Volatility is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# Volatility is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Volatility. If not, see <http://www.gnu.org/licenses/>.
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#
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import sys
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import timeit
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import binascii
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import xml.etree.cElementTree as etree
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import volatility.commands as commands
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import volatility.debug as debug
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import volatility.utils as utils
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PAGESIZE = 4096
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#XML Example file format
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#
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#<patchfile>
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# <patchinfo method="pagescan">
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# <constraints>
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# <match offset="[offset within page]">DEADBEEFC0FFEE</match>
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# ...
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# </constraints>
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# <patches>
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# <patch offset="[offset within page]">BEEFF00DEE</match>
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# </patches>
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# ...
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# </patchinfo>
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#</patchfile>
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class MultiPageScanner(object):
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"""Scans a page at a time through the address space
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Designed to minimize reads/writes to the address space
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"""
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def __init__(self, patchers, full = False):
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self.patchers = list(patchers)
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self.maxlen = 0
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self.remove_patchers = not full
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def use_fullpage(self, address_space):
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"""Calibrate the scanner to ensure fastest speed"""
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# Define the calibration functions
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timeit_fullpage = lambda: list(self.scan_page(address_space, 0, True))
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timeit_nonfullpage = lambda: list(self.scan_page(address_space, 0, False))
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with_fullpage = timeit.repeat(timeit_fullpage, number = 100)
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without_fullpage = timeit.repeat(timeit_nonfullpage, number = 100)
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return min(with_fullpage) < min(without_fullpage)
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def scan(self, address_space, outfd):
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"""Scans through the pages"""
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page_offset = 0
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sys.stdout.write("Calibrating for speed: ")
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sys.stdout.flush()
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fullpage = self.use_fullpage(address_space)
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if fullpage:
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sys.stdout.write("Reading full pages\n")
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else:
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sys.stdout.write("Reading patch locations per page\n")
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sys.stdout.flush()
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done = False
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while address_space.is_valid_address(page_offset + PAGESIZE) and not done:
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sys.stdout.write("\rScanning: {0:08X}".format(page_offset))
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sys.stdout.flush()
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# Run through any patchers that didn't fail
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for patcher in self.scan_page(address_space, page_offset, fullpage):
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outfd.write("\rPatching {0} at page {1:x}\n".format(patcher.get_name(), page_offset))
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patcher.patch(address_space, page_offset)
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if self.remove_patchers:
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self.patchers.remove(patcher)
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# Stop if we've got nothing left to look for
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if not len(self.patchers):
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done = True
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# Jump to the next page
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page_offset += PAGESIZE
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sys.stdout.write("\n")
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def scan_page(self, address_space, page_offset, fullpage = False):
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"""Runs through patchers for a single page"""
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if fullpage:
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pagedata = address_space.read(page_offset, PAGESIZE)
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for patcher in self.patchers:
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for offset, data in patcher.get_constraints():
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if fullpage:
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testdata = pagedata[offset:offset + len(data)]
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else:
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testdata = address_space.read(page_offset + offset, len(data))
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if data != testdata:
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break
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else:
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yield patcher
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class PatcherObject(object):
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"""Simple object to hold patching data"""
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def __init__(self, name):
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self.name = name
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self.patches = set()
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self.constraints = set()
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def add_constraint(self, offset, data):
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"""Adds a constraint to the constraintlist"""
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# Ensure that all offsets are within PAGESIZE
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self.constraints.add((offset % PAGESIZE, data))
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def add_patch(self, offset, patch):
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"""Adds a patch to the patchlist"""
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# Ensure that all offsets are within PAGESIZE
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self.patches.add((offset % PAGESIZE, patch))
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def patch(self, addr_space, page_offset):
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"""Writes to the address space"""
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result = True
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for offset, patch, in self.patches:
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result = result and addr_space.write(page_offset + offset, patch)
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return result
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def get_patches(self):
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"""Returns the list of patches for this patcher"""
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return self.patches
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def get_constraints(self):
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return self.constraints
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def get_name(self):
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"""Returns the name of the patcher"""
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return self.name
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class Patcher(commands.Command):
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"""Patches memory based on page scans"""
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def __init__(self, config, *args, **kwargs):
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commands.Command.__init__(self, config, *args, **kwargs)
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config.add_option('XML-INPUT', short_option = 'x',
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help = 'Input XML file for patching binaries')
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def calculate(self):
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"""Calculates the patchers"""
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addr_space = utils.load_as(self._config, astype = 'physical')
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scanner = MultiPageScanner(self.parse_patchfile())
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return scanner, addr_space
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def render_text(self, outfd, data):
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"""Renders the text and carries out the patching"""
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scanner, addr_space = data
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scanner.scan(addr_space, outfd)
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def get_offset(self, tag):
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"""Returns the offset from a tag"""
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offset = tag.get('offset', None)
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if not offset:
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return None
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base = 10
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if offset.startswith('0x'):
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offset = offset[2:]
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base = 16
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return int(offset, base)
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def parse_patchfile(self):
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"""Parses the patch XML data"""
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if not self._config.WRITE:
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print "Warning: WRITE support not enabled, no patching will occur"
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if self._config.XML_INPUT is None:
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debug.error("No XML input file was specified")
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try:
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root = etree.parse(self._config.XML_INPUT).getroot()
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except SyntaxError, e:
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debug.error("XML input file was improperly formed: " + str(e))
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for element in root:
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if element.tag == 'patchinfo':
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if element.get('method', 'nomethod') == 'pagescan':
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patcher = PatcherObject(element.get('name', 'Unlabelled'))
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constraints = None
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for tag in element:
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if tag.tag == 'constraints':
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constraints = tag
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if tag.tag == 'patches':
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patches = tag
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if constraints is None:
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debug.error("Patch input file does not contain any valid constraints")
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# Parse the patches section
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for tag in patches:
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if tag.tag == 'setbytes':
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offset = self.get_offset(tag)
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data = binascii.a2b_hex(tag.text)
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if offset is not None and len(data):
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patcher.add_patch(offset, data)
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if not len(patcher.get_patches()):
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# No patches, no point adding this
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break
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# Parse the constraints section
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for c in constraints:
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if c.tag == 'match':
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offset = self.get_offset(c)
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data = binascii.a2b_hex(c.text)
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if offset is not None and len(data):
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patcher.add_constraint(offset, data)
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yield patcher
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else:
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debug.error("Unsupported patchinfo method " + element.method)
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