Files
volatility3/volatility3/framework/plugins/linux/pagecache.py
T
2025-01-19 17:33:47 +01:00

580 lines
20 KiB
Python

# This file is Copyright 2024 Volatility Foundation and licensed under the Volatility Software License 1.0
# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
#
import math
import logging
import datetime
from dataclasses import dataclass, astuple
from typing import List, Set, Type, Iterable, IO
from volatility3.framework.constants import architectures
from volatility3.framework import renderers, interfaces
from volatility3.framework.renderers import format_hints
from volatility3.framework.interfaces import plugins
from volatility3.framework.configuration import requirements
from volatility3.plugins import timeliner
from volatility3.plugins.linux import mountinfo
vollog = logging.getLogger(__name__)
@dataclass
class InodeUser:
"""Inode user representation, featuring augmented information and formatted fields.
This is the data the plugin will eventually display.
"""
superblock_addr: int
mountpoint: str
device: str
inode_num: int
inode_addr: int
type: str
inode_pages: int
cached_pages: int
file_mode: str
access_time: str
modification_time: str
change_time: str
path: str
inode_size: int
@staticmethod
def format_symlink(symlink_source: str, symlink_dest: str) -> str:
return f"{symlink_source} -> {symlink_dest}"
@dataclass
class InodeInternal:
"""Inode internal representation containing only the core objects
Fields:
superblock: 'super_block' struct
mountpoint: Superblock mountpoint path
inode: 'inode' struct
path: Dentry full path
"""
superblock: interfaces.objects.ObjectInterface
mountpoint: str
inode: interfaces.objects.ObjectInterface
path: str
def to_user(
self, kernel_layer: interfaces.layers.TranslationLayerInterface
) -> InodeUser:
"""Augment the inode information to be presented to the user
Args:
kernel_layer: The kernel layer to obtain the page size
Returns:
An InodeUser dataclass
"""
# Ensure all types are atomic immutable. Otherwise, astuple() will take a long
# time doing a deepcopy of the Volatility objects.
superblock_addr = self.superblock.vol.offset
device = f"{self.superblock.major}:{self.superblock.minor}"
inode_num = int(self.inode.i_ino)
inode_addr = self.inode.vol.offset
inode_type = self.inode.get_inode_type() or renderers.UnparsableValue()
# Round up the number of pages to fit the inode's size
inode_pages = int(math.ceil(self.inode.i_size / float(kernel_layer.page_size)))
cached_pages = int(self.inode.i_mapping.nrpages)
file_mode = self.inode.get_file_mode()
access_time_dt = self.inode.get_access_time()
modification_time_dt = self.inode.get_modification_time()
change_time_dt = self.inode.get_change_time()
inode_size = int(self.inode.i_size)
inode_user = InodeUser(
superblock_addr=superblock_addr,
mountpoint=self.mountpoint,
device=device,
inode_num=inode_num,
inode_addr=inode_addr,
type=inode_type,
inode_pages=inode_pages,
cached_pages=cached_pages,
file_mode=file_mode,
access_time=access_time_dt,
modification_time=modification_time_dt,
change_time=change_time_dt,
path=self.path,
inode_size=inode_size,
)
return inode_user
class Files(plugins.PluginInterface, timeliner.TimeLinerInterface):
"""Lists files from memory"""
_required_framework_version = (2, 0, 0)
_version = (1, 1, 0)
@classmethod
def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
return [
requirements.ModuleRequirement(
name="kernel",
description="Linux kernel",
architectures=architectures.LINUX_ARCHS,
),
requirements.PluginRequirement(
name="mountinfo", plugin=mountinfo.MountInfo, version=(1, 2, 0)
),
requirements.ListRequirement(
name="type",
description="List of space-separated file type filters i.e. --type REG DIR",
element_type=str,
optional=True,
),
requirements.StringRequirement(
name="find",
description="Filename (full path) to find",
optional=True,
),
]
@staticmethod
def _follow_symlink(
inode: interfaces.objects.ObjectInterface,
symlink_path: str,
) -> str:
"""Follows (fast) symlinks (kernels >= 4.2.x).
Fast symlinks are filesystem agnostic.
Args:
inode: The inode (or pointer) to dump
symlink_path: The symlink name
Returns:
If it can resolve the symlink, it returns a string "symlink_path -> target_path"
Otherwise, it returns the same symlink_path
"""
# i_link (fast symlinks) were introduced in 4.2
if inode and inode.is_link and inode.has_member("i_link") and inode.i_link:
symlink_dest = inode.i_link.dereference().cast(
"string", max_length=255, encoding="utf-8", errors="replace"
)
symlink_path = InodeUser.format_symlink(symlink_path, symlink_dest)
return symlink_path
@classmethod
def _walk_dentry(
cls,
seen_dentries: Set[int],
root_dentry: interfaces.objects.ObjectInterface,
parent_dir: str,
):
"""Walks dentries recursively
Args:
seen_dentries: A set to ensure each dentry is processed only once
root_dentry: Root dentry object
parent_dir: Parent directory path
Yields:
file_path: Filename including path
dentry: Dentry object
"""
for dentry in root_dentry.get_subdirs():
dentry_addr = dentry.vol.offset
# corruption
if dentry_addr == root_dentry.vol.offset:
continue
if dentry_addr in seen_dentries:
continue
seen_dentries.add(dentry_addr)
inode_ptr = dentry.d_inode
if not (inode_ptr and inode_ptr.is_readable()):
continue
inode = inode_ptr.dereference()
if not inode.is_valid():
continue
# This allows us to have consistent paths
if dentry.d_name.name:
basename = dentry.d_name.name_as_str()
# Do NOT use os.path.join() below
file_path = parent_dir + "/" + basename
else:
continue
yield file_path, dentry
if inode.is_dir:
yield from cls._walk_dentry(seen_dentries, dentry, parent_dir=file_path)
@classmethod
def get_inodes(
cls,
context: interfaces.context.ContextInterface,
vmlinux_module_name: str,
follow_symlinks: bool = True,
) -> Iterable[InodeInternal]:
"""Retrieves the inodes from the superblocks
Args:
context: The context that the plugin will operate within
vmlinux_module_name: The name of the kernel module on which to operate
follow_symlinks: Whether to follow symlinks or not
Yields:
An InodeInternal object
"""
superblocks_iter = mountinfo.MountInfo.get_superblocks(
context=context,
vmlinux_module_name=vmlinux_module_name,
)
seen_inodes = set()
seen_dentries = set()
for superblock, mountpoint in superblocks_iter:
parent_dir = "" if mountpoint == "/" else mountpoint
# Superblock root dentry
root_dentry_ptr = superblock.s_root
if not root_dentry_ptr:
continue
root_dentry = root_dentry_ptr.dereference()
# Dentry sanity check
if not root_dentry.is_root():
continue
# More dentry/inode sanity checks
root_inode_ptr = root_dentry.d_inode
if not (root_inode_ptr and root_inode_ptr.is_readable()):
continue
root_inode = root_inode_ptr.dereference()
if not root_inode.is_valid():
continue
# Inode already processed?
if root_inode_ptr in seen_inodes:
continue
seen_inodes.add(root_inode_ptr)
root_path = mountpoint
inode_in = InodeInternal(
superblock=superblock,
mountpoint=mountpoint,
inode=root_inode,
path=root_path,
)
yield inode_in
# Children
for file_path, file_dentry in cls._walk_dentry(
seen_dentries, root_dentry, parent_dir
):
if not file_dentry:
continue
# Dentry/inode sanity checks
file_inode_ptr = file_dentry.d_inode
if not (file_inode_ptr and file_inode_ptr.is_readable()):
continue
file_inode = file_inode_ptr.dereference()
if not file_inode.is_valid():
continue
# Inode already processed?
if file_inode_ptr in seen_inodes:
continue
seen_inodes.add(file_inode_ptr)
if follow_symlinks:
file_path = cls._follow_symlink(file_inode_ptr, file_path)
inode_in = InodeInternal(
superblock=superblock,
mountpoint=mountpoint,
inode=file_inode,
path=file_path,
)
yield inode_in
def _generator(self):
vmlinux_module_name = self.config["kernel"]
vmlinux = self.context.modules[vmlinux_module_name]
vmlinux_layer = self.context.layers[vmlinux.layer_name]
inodes_iter = self.get_inodes(
context=self.context,
vmlinux_module_name=vmlinux_module_name,
)
types_filter = self.config["type"]
for inode_in in inodes_iter:
if types_filter and inode_in.inode.get_inode_type() not in types_filter:
continue
if self.config["find"]:
if inode_in.path == self.config["find"]:
inode_out = inode_in.to_user(vmlinux_layer)
yield (0, astuple(inode_out))
break # Only the first match
else:
inode_out = inode_in.to_user(vmlinux_layer)
yield (0, astuple(inode_out))
def generate_timeline(self):
"""Generates tuples of (description, timestamp_type, timestamp)
These need not be generated in any particular order, sorting
will be done later
"""
vmlinux_module_name = self.config["kernel"]
vmlinux = self.context.modules[vmlinux_module_name]
vmlinux_layer = self.context.layers[vmlinux.layer_name]
inodes_iter = self.get_inodes(
context=self.context,
vmlinux_module_name=vmlinux_module_name,
)
for inode_in in inodes_iter:
inode_out = inode_in.to_user(vmlinux_layer)
description = f"Cached Inode for {inode_out.path}"
yield description, timeliner.TimeLinerType.ACCESSED, inode_out.access_time
yield description, timeliner.TimeLinerType.MODIFIED, inode_out.modification_time
yield description, timeliner.TimeLinerType.CHANGED, inode_out.change_time
@staticmethod
def format_fields_with_headers(headers, generator):
"""Uses the headers type to cast the fields obtained from the generator"""
for level, fields in generator:
formatted_fields = []
for header, field in zip(headers, fields):
header_type = header[1]
if isinstance(
field, (header_type, interfaces.renderers.BaseAbsentValue)
):
formatted_field = field
else:
formatted_field = header_type(field)
formatted_fields.append(formatted_field)
yield level, formatted_fields
def run(self):
headers = [
("SuperblockAddr", format_hints.Hex),
("MountPoint", str),
("Device", str),
("InodeNum", int),
("InodeAddr", format_hints.Hex),
("FileType", str),
("InodePages", int),
("CachedPages", int),
("FileMode", str),
("AccessTime", datetime.datetime),
("ModificationTime", datetime.datetime),
("ChangeTime", datetime.datetime),
("FilePath", str),
("InodeSize", int),
]
return renderers.TreeGrid(
headers, self.format_fields_with_headers(headers, self._generator())
)
class InodePages(plugins.PluginInterface):
"""Lists and recovers cached inode pages"""
_required_framework_version = (2, 0, 0)
_version = (3, 0, 0)
@classmethod
def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
return [
requirements.ModuleRequirement(
name="kernel",
description="Linux kernel",
architectures=architectures.LINUX_ARCHS,
),
requirements.PluginRequirement(
name="files", plugin=Files, version=(1, 0, 0)
),
requirements.StringRequirement(
name="find",
description="Filename (full path) to find ",
optional=True,
),
requirements.IntRequirement(
name="inode",
description="Inode address",
optional=True,
),
requirements.BooleanRequirement(
name="dump",
description="Extract inode content",
default=False,
optional=True,
),
]
@staticmethod
def write_inode_content_to_file(
context: interfaces.context.ContextInterface,
layer_name: str,
inode: interfaces.objects.ObjectInterface,
filename: str,
open_method: Type[interfaces.plugins.FileHandlerInterface],
) -> None:
"""Extracts the inode's contents from the page cache and saves them to a file
Args:
context: The context on which to operate
layer_name: The name of the layer on which to operate
inode: The inode to dump
filename: Filename for writing the inode content
open_method: class for constructing output files
"""
if not inode.is_reg:
vollog.error("The inode is not a regular file")
return None
try:
with open_method(filename) as f:
InodePages.write_inode_content_to_stream(context, layer_name, inode, f)
except OSError as e:
vollog.error("Unable to write to file (%s): %s", filename, e)
@staticmethod
def write_inode_content_to_stream(
context: interfaces.context.ContextInterface,
layer_name: str,
inode: interfaces.objects.ObjectInterface,
stream: IO,
) -> None:
"""Extracts the inode's contents from the page cache and saves them to a stream
Args:
context: The context on which to operate
layer_name: The name of the layer on which to operate
inode: The inode to dump
stream: An IO stream to write to, typically FileHandlerInterface or BytesIO
"""
layer = context.layers[layer_name]
# By using truncate/seek, provided the filesystem supports it, and the
# stream is a File interface, a sparse file will be
# created, saving both disk space and I/O time.
# Additionally, using the page index will guarantee that each page is written at the
# appropriate file position.
inode_size = inode.i_size
stream.truncate(inode_size)
for page_idx, page_content in inode.get_contents():
current_fp = page_idx * layer.page_size
max_length = inode_size - current_fp
page_bytes = page_content[:max_length]
if current_fp + len(page_bytes) > inode_size:
vollog.error(
"Page out of file bounds: inode 0x%x, inode size %d, page index %d",
inode.vol.offset,
inode_size,
page_idx,
)
stream.seek(current_fp)
stream.write(page_bytes)
def _generator(self):
vmlinux_module_name = self.config["kernel"]
vmlinux = self.context.modules[vmlinux_module_name]
vmlinux_layer = self.context.layers[vmlinux.layer_name]
if self.config["inode"] and self.config["find"]:
vollog.error("Cannot use --inode and --find simultaneously")
return None
if self.config["find"]:
inodes_iter = Files.get_inodes(
context=self.context,
vmlinux_module_name=vmlinux_module_name,
)
for inode_in in inodes_iter:
if inode_in.path == self.config["find"]:
inode = inode_in.inode
break # Only the first match
else:
vollog.error("Unable to find inode with path %s", self.config["find"])
return None
elif self.config["inode"]:
inode = vmlinux.object("inode", self.config["inode"], absolute=True)
else:
vollog.error("You must use either --inode or --find")
return None
if not inode.is_valid():
vollog.error("Invalid inode at 0x%x", inode.vol.offset)
return None
if not inode.is_reg:
vollog.error("The inode is not a regular file")
return None
inode_size = inode.i_size
for page_obj in inode.get_pages():
page_vaddr = page_obj.vol.offset
page_paddr = page_obj.to_paddr()
page_mapping_addr = page_obj.mapping
page_index = int(page_obj.index)
page_file_offset = page_index * vmlinux_layer.page_size
dump_safe = page_file_offset < inode_size
page_flags_list = page_obj.get_flags_list()
page_flags = ",".join([x.replace("PG_", "") for x in page_flags_list])
fields = (
page_vaddr,
page_paddr,
page_mapping_addr,
page_index,
dump_safe,
page_flags,
)
yield 0, fields
if self.config["dump"]:
open_method = self.open
inode_address = inode.vol.offset
filename = open_method.sanitize_filename(f"inode_0x{inode_address:x}.dmp")
vollog.info("[*] Writing inode at 0x%x to '%s'", inode_address, filename)
self.write_inode_content_to_file(
self.context, vmlinux_layer.name, inode, filename, open_method
)
def run(self):
headers = [
("PageVAddr", format_hints.Hex),
("PagePAddr", format_hints.Hex),
("MappingAddr", format_hints.Hex),
("Index", int),
("DumpSafe", bool),
("Flags", str),
]
return renderers.TreeGrid(
headers, Files.format_fields_with_headers(headers, self._generator())
)