#!/usr/bin/python2 -O '''Qubes Image Converter Toolkit for secure transfer and conversion of images between Qubes VMs.''' # The Qubes OS Project, http://www.qubes-os.org # # Copyright (C) 2013 Wojciech Porczyk # # 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. import colorsys import math import os import re try: from io import BytesIO except ImportError: from cStringIO import StringIO as BytesIO import subprocess import sys import unittest import cairo # those are for "zOMG UlTRa HD! WalLLpapPer 8K!!1!" to work seamlessly; # 8192 * 5120 * 4 B = 160 MiB, so DoS by memory exhaustion is unlikely MAX_WIDTH = 8192 MAX_HEIGHT = 5120 # current max raster icon size in hicolor theme is 256 as of 2013/fedora-18 # beyond that one probably shall use scalable icons # (SVG is currently unsupported) ICON_MAXSIZE = 512 # header consists of two decimal numbers, SPC and LF re_imghdr = re.compile(br'^\d+ \d+\n$') def imghdrlen(w, h): # width & height are inclusive max vals, and +2 for ' ' and '\n' return len(str(w)) + len(str(h)) + 2 class Image(object): def __init__(self, rgba, size): '''This class is not meant to be instantiated directly. Use one of: get_from_stream(), get_from_vm(), get_xdg_icon_from_vm(), get_through_dvm()''' self._rgba = rgba self._size = size def save(self, dst): 'Save image to disk. dst may specify format, like png:aqq.gif' p = subprocess.Popen(['convert', '-depth', '8', '-size', '{0[0]}x{0[1]}'.format(self._size), 'rgba:-', dst], stdin=subprocess.PIPE) p.stdin.write(self._rgba) p.stdin.close() if p.wait(): raise Exception('Conversion failed') @property def data(self): return self._rgba @property def width(self): return self._size[0] @property def height(self): return self._size[1] def tint(self, colour): '''Return new tinted image''' r, g, b = hex_to_float(colour) h, _, s = colorsys.rgb_to_hls(r, g, b) result = BytesIO() # duplicate the whole loop for performance reasons if sys.version_info[0] < 3: for i in range(0, self._size[0] * self._size[1] * 4, 4): r, g, b, a = tuple(ord(c) / 255. for c in self._rgba[i:i+4]) _, l, _ = colorsys.rgb_to_hls(r, g, b) r, g, b = colorsys.hls_to_rgb(h, l, s) result.write(b''.join(chr(int(i * 255)) for i in [r, g, b, a])) else: for i in range(0, self._size[0] * self._size[1] * 4, 4): r, g, b, a = tuple(c / 255. for c in self._rgba[i:i + 4]) _, l, _ = colorsys.rgb_to_hls(r, g, b) r, g, b = colorsys.hls_to_rgb(h, l, s) result.write(bytes(int(i * 255) for i in [r, g, b, a])) return self.__class__(rgba=result.getvalue(), size=self._size) @classmethod def load_from_file(cls, filename): '''Loads image from local file. WARNING: always load trusted images.''' p = subprocess.Popen(['identify', '-format', '%w %h', filename], stdout=subprocess.PIPE) size = tuple(int(i) for i in p.stdout.read().strip().split()) p.stdout.close() p.wait() p = subprocess.Popen(['convert', filename, '-depth', '8', 'rgba:-'], stdout=subprocess.PIPE) rgba = p.stdout.read() p.stdout.close() p.wait() return cls(rgba=rgba, size=size) @classmethod def get_from_stream(cls, stream, max_width=MAX_WIDTH, max_height=MAX_HEIGHT): '''Carefully parse image data from stream. THIS METHOD IS SECURITY-SENSITIVE''' maxhdrlen = imghdrlen(max_width, max_height) untrusted_header = stream.readline(maxhdrlen) if len(untrusted_header) == 0: raise ValueError('No icon received') if not re_imghdr.match(untrusted_header): raise ValueError('Image format violation') header = untrusted_header del untrusted_header untrusted_width, untrusted_height = (int(i) for i in header.rstrip().split()) if not (0 < untrusted_width <= max_width \ and 0 < untrusted_height <= max_height): raise ValueError('Image size constraint violation:' ' width={width} height={height}' ' max_width={max_width} max_height={max_height}'.format( width=untrusted_width, height=untrusted_height, max_width=max_width, max_height=max_height)) width, height = untrusted_width, untrusted_height del untrusted_width, untrusted_height expected_data_len = width * height * 4 # RGBA untrusted_data = stream.read(expected_data_len) if len(untrusted_data) != expected_data_len: raise ValueError( \ 'Image data length violation (is {0}, should be {1})'.format( \ len(untrusted_data), expected_data_len)) data = untrusted_data del untrusted_data return cls(rgba=data, size=(width, height)) @classmethod def get_from_vm(cls, vm, src, **kwargs): 'Get image from VM by QUBESRPC (qubes.GetImageRGBA).' p = vm.run_service('qubes.GetImageRGBA') p.stdin.write('{0}\n'.format(src).encode()) p.stdin.close() try: img = cls.get_from_stream(p.stdout, **kwargs) finally: p.stdout.close() if p.wait(): raise Exception('Something went wrong with receiver') return img @classmethod def get_xdg_icon_from_vm(cls, vm, icon, **kwargs): 'Get image from VM. If path is not absolute, get it from hicolor theme.' if not os.path.isabs(icon): icon = 'xdgicon:' + icon return cls.get_from_vm(vm, icon, max_width=ICON_MAXSIZE, max_height=ICON_MAXSIZE, **kwargs) @classmethod def get_through_dvm(cls, filename, **kwargs): '''Master end of image filter: writes untrusted image to stdout and expects header+RGBA on stdin. This method is invoked from qvm-imgconverter-client.''' filetype = None if ':' in filename: filetype, filename = filename.split(':', 1)[0] sys.stdout.write('{0}:-\n'.format(filetype)) else: sys.stdout.write('-\n') try: sys.stdout.write(open(filename).read()) except Exception as e: raise Exception('Something went wrong: {0!s}'.format(e)) finally: sys.stdout.close() # sys.stdout.close() is not enough and documentation is silent about this os.close(1) return cls.get_from_stream(sys.stdin, **kwargs) def __eq__(self, other): return self._size == other._size and self._rgba == other._rgba def __ne__(self, other): return not self.__eq__(other) def hex_to_float(colour, channels=3, depth=8): '''Convert hex colour definition to tuple of floats.''' if depth % 4 != 0: raise NotImplementedError('depths not divisible by 4 are unsupported') length = channels * depth // 4 step = depth // 4 # get rid of '#' or '0x' in front of hex values colour = colour[-length:] return tuple(int(colour[i:i+step], 0x10) / float(2**depth - 1) for i in range(0, length, step)) def tint(src, dst, colour): '''Tint image to reflect vm label. src and dst may specify format, like png:aqq.gif''' Image.load_from_file(src).tint(colour).save(dst) # vim: ft=python sw=4 ts=4 et