From 16f5abcdf5de5dc32a9d52139936cfaa4e8c3c09 Mon Sep 17 00:00:00 2001 From: Mike Auty Date: Sun, 26 Sep 2021 01:40:38 +0100 Subject: [PATCH] Layers: Improve response if snappy not installed --- volatility3/framework/layers/avml.py | 156 +-------------------------- 1 file changed, 4 insertions(+), 152 deletions(-) diff --git a/volatility3/framework/layers/avml.py b/volatility3/framework/layers/avml.py index aca3b037f..5c1bfe1bb 100644 --- a/volatility3/framework/layers/avml.py +++ b/volatility3/framework/layers/avml.py @@ -2,13 +2,14 @@ The user of the file doesn't have to worry about the compression, but random access is not allowed.""" -import io import struct from typing import Tuple, List, Optional from volatility3.framework import exceptions, interfaces, constants from volatility3.framework.layers import segmented +vollog = logging.getLogger(__name__) + try: import snappy @@ -17,147 +18,6 @@ except ImportError: HAS_SNAPPY = False -class SnappyFraming: - def __init__(self): - pass - - # crc32-c (Castagnoli) (crc32c_poly=0x1EDC6F41) - crc32c_table = [ - 0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4, - 0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB, - 0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B, - 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24, - 0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B, - 0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384, - 0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54, - 0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B, - 0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A, - 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35, - 0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5, - 0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA, - 0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45, - 0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A, - 0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A, - 0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595, - 0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48, - 0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957, - 0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687, - 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198, - 0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927, - 0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38, - 0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8, - 0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7, - 0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096, - 0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789, - 0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859, - 0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46, - 0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9, - 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6, - 0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36, - 0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829, - 0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C, - 0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93, - 0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043, - 0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C, - 0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3, - 0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC, - 0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C, - 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033, - 0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652, - 0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D, - 0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D, - 0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982, - 0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D, - 0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622, - 0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2, - 0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED, - 0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530, - 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F, - 0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF, - 0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0, - 0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F, - 0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540, - 0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90, - 0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F, - 0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE, - 0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1, - 0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321, - 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E, - 0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81, - 0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E, - 0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E, - 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351, - ] - - def masked_crc32c(self, buf: bytes) -> int: - crc = 0xffffffff - for c in buf: - crc = (crc >> 8) ^ self.crc32c_table[(crc ^ c) & 0xFF] - crc = (~crc) & 0xffffffff - # reverse endianness - crc = struct.unpack(">I", struct.pack("> 15) | (crc << 17)) + 0xa282ead8) & 0xffffffff - - def decompress(self, source_data: bytes) -> io.BytesIO: - offset = 0 - data = io.BytesIO() - while offset < len(source_data): - header_structure = " Tuple[bytes, int]: - """Decompresses data up to the size limit provided - - Args: - data: Input data - limit: The maximum size of decompressed data - - Returns: - Tuple of decompressed data, and number of compressed bytes consumed - """ - decompressed = bytearray() - offset = 0 - crc_len = 4 - chunk_header_struct = '> 8 - if chunk_type == 0xff: - if data[offset + chunk_header_len:offset + chunk_header_len + chunk_size] != b'sNaPpY': - raise ValueError(f"Snappy header missing at offset: {offset}") - elif chunk_type in [0x00, 0x01]: - # CRC + (Un)compressed data - start = offset + chunk_header_len - chunk_crc = data[start: start + crc_len] - chunk_data = data[start + crc_len: start + chunk_size] - if chunk_type == 0x00: - # Compressed data - chunk_data = snappy.decompress(chunk_data) - # TODO: Verify CRC - decompressed.extend(chunk_data) - elif chunk_type in range(0x2, 0x80): - # Unskippable - raise ValueError(f"Unskippable chunk of type {chunk_type} found: {offset}") - offset += chunk_header_len + chunk_size - return decompressed, offset - - class AVMLLayer(segmented.NonLinearlySegmentedLayer): """A Lime format TranslationLayer. @@ -176,6 +36,8 @@ class AVMLLayer(segmented.NonLinearlySegmentedLayer): layer.read(layer.minimum_address, struct.calcsize(header_structure))) if magic not in [0x4c4d5641] or version != 2: raise exceptions.LayerException("File not completely in AVML format") + if not HAS_SNAPPY: + vollog.warning('AVML file detected, but snappy python library not installed') def _load_segments(self) -> None: base_layer = self.context.layers[self._base_layer] @@ -270,13 +132,3 @@ class AVMLStacker(interfaces.automagic.StackerLayerInterface): new_name = context.layers.free_layer_name("AVMLLayer") context.config[interfaces.configuration.path_join(new_name, "base_layer")] = layer_name return AVMLLayer(context, new_name, new_name) - - -if __name__ == '__main__': - import sys - - source_data = open(sys.argv[1], 'br').read() - - sf = SnappyFraming() - with open('outputfile', 'wb') as fp: - fp.write(sf.decompress(source_data).read())