Convert paths safely to file system paths

With the old implementation on Windows a path like
"/c:/file/ignore" got converted to "c:\file" and
allowed access to files outside of FOLDER
This commit is contained in:
Unrud 2015-12-24 12:37:11 +01:00
parent 6b7e79a368
commit b4b3d51f33
3 changed files with 77 additions and 33 deletions

View File

@ -20,8 +20,11 @@ Helper functions for working with paths
"""
import os
import posixpath
from . import log
def sanitize_path(path):
"""Make absolute (with leading slash) to prevent access to other data.
@ -34,4 +37,36 @@ def sanitize_path(path):
continue
new_path = posixpath.join(new_path, part)
trailing_slash = "" if new_path.endswith("/") else trailing_slash
return new_path + trailing_slash
return new_path + trailing_slash
def is_safe_filesystem_path_component(path):
"""Checks if path is a single component of a local filesystem path
and is safe to join"""
if not path:
return False
drive, _ = os.path.splitdrive(path)
if drive:
return False
head, _ = os.path.split(path)
if head:
return False
if path in (os.curdir, os.pardir):
return False
return True
def path_to_filesystem(path, base_folder):
"""Converts path to a local filesystem path relative to base_folder
in a secure manner or raises ValueError."""
sane_path = sanitize_path(path).strip("/")
safe_path = base_folder
if not sane_path:
return safe_path
for part in sane_path.split("/"):
if not is_safe_filesystem_path_component(part):
log.LOGGER.debug("Can't translate path safely to filesystem: %s",
path)
raise ValueError("Unsafe path")
safe_path = os.path.join(safe_path, part)
return safe_path

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@ -28,7 +28,8 @@ import json
import time
import sys
from contextlib import contextmanager
from .. import config, ical
from .. import config, ical, pathutils
FOLDER = os.path.expanduser(config.get("storage", "filesystem_folder"))
@ -63,41 +64,41 @@ def open(path, mode="r"):
class Collection(ical.Collection):
"""Collection stored in a flat ical file."""
@property
def _path(self):
def _filesystem_path(self):
"""Absolute path of the file at local ``path``."""
return os.path.join(FOLDER, self.path.replace("/", os.sep))
return pathutils.path_to_filesystem(self.path, FOLDER)
@property
def _props_path(self):
"""Absolute path of the file storing the collection properties."""
return self._path + ".props"
return self._filesystem_path + ".props"
def _create_dirs(self):
"""Create folder storing the collection if absent."""
if not os.path.exists(os.path.dirname(self._path)):
os.makedirs(os.path.dirname(self._path))
if not os.path.exists(os.path.dirname(self._filesystem_path)):
os.makedirs(os.path.dirname(self._filesystem_path))
def save(self, text):
self._create_dirs()
with open(self._path, "w") as fd:
with open(self._filesystem_path, "w") as fd:
fd.write(text)
def delete(self):
os.remove(self._path)
os.remove(self._filesystem_path)
os.remove(self._props_path)
@property
def text(self):
try:
with open(self._path) as fd:
with open(self._filesystem_path) as fd:
return fd.read()
except IOError:
return ""
@classmethod
def children(cls, path):
abs_path = os.path.join(FOLDER, path.replace("/", os.sep))
_, directories, files = next(os.walk(abs_path))
filesystem_path = pathutils.path_to_filesystem(path, FOLDER)
_, directories, files = next(os.walk(filesystem_path))
for filename in directories + files:
rel_filename = posixpath.join(path, filename)
if cls.is_node(rel_filename) or cls.is_leaf(rel_filename):
@ -105,17 +106,19 @@ class Collection(ical.Collection):
@classmethod
def is_node(cls, path):
abs_path = os.path.join(FOLDER, path.replace("/", os.sep))
return os.path.isdir(abs_path)
filesystem_path = pathutils.path_to_filesystem(path, FOLDER)
return os.path.isdir(filesystem_path)
@classmethod
def is_leaf(cls, path):
abs_path = os.path.join(FOLDER, path.replace("/", os.sep))
return os.path.isfile(abs_path) and not abs_path.endswith(".props")
filesystem_path = pathutils.path_to_filesystem(path, FOLDER)
return (os.path.isfile(filesystem_path) and not
filesystem_path.endswith(".props"))
@property
def last_modified(self):
modification_time = time.gmtime(os.path.getmtime(self._path))
modification_time = \
time.gmtime(os.path.getmtime(self._filesystem_path))
return time.strftime("%a, %d %b %Y %H:%M:%S +0000", modification_time)
@property

View File

@ -30,13 +30,14 @@ import sys
from . import filesystem
from .. import ical
from .. import log
from .. import pathutils
class Collection(filesystem.Collection):
"""Collection stored in several files per calendar."""
def _create_dirs(self):
if not os.path.exists(self._path):
os.makedirs(self._path)
if not os.path.exists(self._filesystem_path):
os.makedirs(self._filesystem_path)
@property
def headers(self):
@ -52,17 +53,18 @@ class Collection(filesystem.Collection):
name = (
component.name if sys.version_info[0] >= 3 else
component.name.encode(filesystem.FILESYSTEM_ENCODING))
path = os.path.join(self._path, name)
with filesystem.open(path, "w") as fd:
filesystem_path = os.path.join(self._filesystem_path, name)
with filesystem.open(filesystem_path, "w") as fd:
fd.write(text)
def delete(self):
shutil.rmtree(self._path)
shutil.rmtree(self._filesystem_path)
os.remove(self._props_path)
def remove(self, name):
if os.path.exists(os.path.join(self._path, name)):
os.remove(os.path.join(self._path, name))
filesystem_path = os.path.join(self._filesystem_path, name)
if os.path.exists(filesystem_path):
os.remove(filesystem_path)
@property
def text(self):
@ -70,14 +72,14 @@ class Collection(filesystem.Collection):
ical.Timezone, ical.Event, ical.Todo, ical.Journal, ical.Card)
items = set()
try:
filenames = os.listdir(self._path)
filenames = os.listdir(self._filesystem_path)
except (OSError, IOError) as e:
log.LOGGER.info('Error while reading collection %r: %r'
% (self._path, e))
% (self._filesystem_path, e))
return ""
for filename in filenames:
path = os.path.join(self._path, filename)
path = os.path.join(self._filesystem_path, filename)
try:
with filesystem.open(path) as fd:
items.update(self._parse(fd.read(), components))
@ -90,17 +92,21 @@ class Collection(filesystem.Collection):
@classmethod
def is_node(cls, path):
path = os.path.join(filesystem.FOLDER, path.replace("/", os.sep))
return os.path.isdir(path) and not os.path.exists(path + ".props")
filesystem_path = pathutils.path_to_filesystem(path,
filesystem.FOLDER)
return (os.path.isdir(filesystem_path) and
not os.path.exists(filesystem_path + ".props"))
@classmethod
def is_leaf(cls, path):
path = os.path.join(filesystem.FOLDER, path.replace("/", os.sep))
return os.path.isdir(path) and os.path.exists(path + ".props")
filesystem_path = pathutils.path_to_filesystem(path,
filesystem.FOLDER)
return (os.path.isdir(filesystem_path) and
os.path.exists(path + ".props"))
@property
def last_modified(self):
last = max([
os.path.getmtime(os.path.join(self._path, filename))
for filename in os.listdir(self._path)] or [0])
os.path.getmtime(os.path.join(self._filesystem_path, filename))
for filename in os.listdir(self._filesystem_path)] or [0])
return time.strftime("%a, %d %b %Y %H:%M:%S +0000", time.gmtime(last))