contents: double check that os_path is always within root

check based on tornado `StaticFileHandler.validate_absolute_path`

I haven't been able to actually escape root, but we should have this check anyway.

IPython/html/services/contents/fileio.py

@@ -1,166 +1,174 b''
 """
 Utilities for file-based Contents/Checkpoints managers.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import base64
 from contextlib import contextmanager
 import errno
 import io
 import os
 import shutil
 
 from tornado.web import HTTPError
 
 from IPython.html.utils import (
     to_api_path,
     to_os_path,
 )
 from IPython import nbformat
 from IPython.utils.io import atomic_writing
 from IPython.utils.py3compat import str_to_unicode
 
 
 class FileManagerMixin(object):
     """
     Mixin for ContentsAPI classes that interact with the filesystem.
 
     Provides facilities for reading, writing, and copying both notebooks and
     generic files.
 
     Shared by FileContentsManager and FileCheckpoints.
 
     Note
     ----
     Classes using this mixin must provide the following attributes:
 
     root_dir : unicode
         A directory against against which API-style paths are to be resolved.
 
     log : logging.Logger
     """
 
     @contextmanager
     def open(self, os_path, *args, **kwargs):
         """wrapper around io.open that turns permission errors into 403"""
         with self.perm_to_403(os_path):
             with io.open(os_path, *args, **kwargs) as f:
                 yield f
 
     @contextmanager
     def atomic_writing(self, os_path, *args, **kwargs):
         """wrapper around atomic_writing that turns permission errors to 403"""
         with self.perm_to_403(os_path):
             with atomic_writing(os_path, *args, **kwargs) as f:
                 yield f
 
     @contextmanager
     def perm_to_403(self, os_path=''):
         """context manager for turning permission errors into 403."""
         try:
             yield
         except (OSError, IOError) as e:
             if e.errno in {errno.EPERM, errno.EACCES}:
                 # make 403 error message without root prefix
                 # this may not work perfectly on unicode paths on Python 2,
                 # but nobody should be doing that anyway.
                 if not os_path:
                     os_path = str_to_unicode(e.filename or 'unknown file')
                 path = to_api_path(os_path, root=self.root_dir)
                 raise HTTPError(403, u'Permission denied: %s' % path)
             else:
                 raise
 
     def _copy(self, src, dest):
         """copy src to dest
 
         like shutil.copy2, but log errors in copystat
         """
         shutil.copyfile(src, dest)
         try:
             shutil.copystat(src, dest)
         except OSError:
             self.log.debug("copystat on %s failed", dest, exc_info=True)
 
     def _get_os_path(self, path):
         """Given an API path, return its file system path.
 
         Parameters
         ----------
         path : string
             The relative API path to the named file.
 
         Returns
         -------
         path : string
             Native, absolute OS path to for a file.
+
+        Raises
+        ------
+        404: if path is outside root
         """
-        return to_os_path(path, self.root_dir)
+        root = os.path.abspath(self.root_dir)
+        os_path = to_os_path(path, root)
+        if not (os.path.abspath(os_path) + os.path.sep).startswith(root):
+            raise HTTPError(404, "%s is outside root contents directory" % path)
+        return os_path
 
     def _read_notebook(self, os_path, as_version=4):
         """Read a notebook from an os path."""
         with self.open(os_path, 'r', encoding='utf-8') as f:
             try:
                 return nbformat.read(f, as_version=as_version)
             except Exception as e:
                 raise HTTPError(
                     400,
                     u"Unreadable Notebook: %s %r" % (os_path, e),
                 )
 
     def _save_notebook(self, os_path, nb):
         """Save a notebook to an os_path."""
         with self.atomic_writing(os_path, encoding='utf-8') as f:
             nbformat.write(nb, f, version=nbformat.NO_CONVERT)
 
     def _read_file(self, os_path, format):
         """Read a non-notebook file.
 
         os_path: The path to be read.
         format:
           If 'text', the contents will be decoded as UTF-8.
           If 'base64', the raw bytes contents will be encoded as base64.
           If not specified, try to decode as UTF-8, and fall back to base64
         """
         if not os.path.isfile(os_path):
             raise HTTPError(400, "Cannot read non-file %s" % os_path)
 
         with self.open(os_path, 'rb') as f:
             bcontent = f.read()
 
         if format is None or format == 'text':
             # Try to interpret as unicode if format is unknown or if unicode
             # was explicitly requested.
             try:
                 return bcontent.decode('utf8'), 'text'
             except UnicodeError:
                 if format == 'text':
                     raise HTTPError(
                         400,
                         "%s is not UTF-8 encoded" % os_path,
                         reason='bad format',
                     )
         return base64.encodestring(bcontent).decode('ascii'), 'base64'
 
     def _save_file(self, os_path, content, format):
         """Save content of a generic file."""
         if format not in {'text', 'base64'}:
             raise HTTPError(
                 400,
                 "Must specify format of file contents as 'text' or 'base64'",
             )
         try:
             if format == 'text':
                 bcontent = content.encode('utf8')
             else:
                 b64_bytes = content.encode('ascii')
                 bcontent = base64.decodestring(b64_bytes)
         except Exception as e:
             raise HTTPError(
                 400, u'Encoding error saving %s: %s' % (os_path, e)
             )
 
         with self.atomic_writing(os_path, text=False) as f:
             f.write(bcontent)

IPython/html/services/contents/filemanager.py

@@ -1,472 +1,473 b''
 """A contents manager that uses the local file system for storage."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 
 import io
 import os
 import shutil
 import mimetypes
 
 from tornado import web
 
 from .filecheckpoints import FileCheckpoints
 from .fileio import FileManagerMixin
 from .manager import ContentsManager
 
 from IPython import nbformat
 from IPython.utils.importstring import import_item
 from IPython.utils.traitlets import Any, Unicode, Bool, TraitError
 from IPython.utils.py3compat import getcwd, string_types
 from IPython.utils import tz
 from IPython.html.utils import (
     is_hidden,
     to_api_path,
 )
 
 _script_exporter = None
 
 
 def _post_save_script(model, os_path, contents_manager, **kwargs):
     """convert notebooks to Python script after save with nbconvert
 
     replaces `ipython notebook --script`
     """
     from IPython.nbconvert.exporters.script import ScriptExporter
 
     if model['type'] != 'notebook':
         return
 
     global _script_exporter
     if _script_exporter is None:
         _script_exporter = ScriptExporter(parent=contents_manager)
     log = contents_manager.log
 
     base, ext = os.path.splitext(os_path)
     py_fname = base + '.py'
     script, resources = _script_exporter.from_filename(os_path)
     script_fname = base + resources.get('output_extension', '.txt')
     log.info("Saving script /%s", to_api_path(script_fname, contents_manager.root_dir))
     with io.open(script_fname, 'w', encoding='utf-8') as f:
         f.write(script)
 
 
 class FileContentsManager(FileManagerMixin, ContentsManager):
 
     root_dir = Unicode(config=True)
 
     def _root_dir_default(self):
         try:
             return self.parent.notebook_dir
         except AttributeError:
             return getcwd()
 
     save_script = Bool(False, config=True, help='DEPRECATED, use post_save_hook')
     def _save_script_changed(self):
         self.log.warn("""
         `--script` is deprecated. You can trigger nbconvert via pre- or post-save hooks:
 
             ContentsManager.pre_save_hook
             FileContentsManager.post_save_hook
 
         A post-save hook has been registered that calls:
 
             ipython nbconvert --to script [notebook]
 
         which behaves similarly to `--script`.
         """)
 
         self.post_save_hook = _post_save_script
 
     post_save_hook = Any(None, config=True,
         help="""Python callable or importstring thereof
 
         to be called on the path of a file just saved.
 
         This can be used to process the file on disk,
         such as converting the notebook to a script or HTML via nbconvert.
 
         It will be called as (all arguments passed by keyword)::
 
             hook(os_path=os_path, model=model, contents_manager=instance)
 
         - path: the filesystem path to the file just written
         - model: the model representing the file
         - contents_manager: this ContentsManager instance
         """
     )
     def _post_save_hook_changed(self, name, old, new):
         if new and isinstance(new, string_types):
             self.post_save_hook = import_item(self.post_save_hook)
         elif new:
             if not callable(new):
                 raise TraitError("post_save_hook must be callable")
 
     def run_post_save_hook(self, model, os_path):
         """Run the post-save hook if defined, and log errors"""
         if self.post_save_hook:
             try:
                 self.log.debug("Running post-save hook on %s", os_path)
                 self.post_save_hook(os_path=os_path, model=model, contents_manager=self)
             except Exception:
                 self.log.error("Post-save hook failed on %s", os_path, exc_info=True)
 
     def _root_dir_changed(self, name, old, new):
         """Do a bit of validation of the root_dir."""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             self.root_dir = os.path.abspath(new)
             return
         if not os.path.isdir(new):
             raise TraitError("%r is not a directory" % new)
 
     def _checkpoints_class_default(self):
         return FileCheckpoints
 
     def is_hidden(self, path):
         """Does the API style path correspond to a hidden directory or file?
 
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to root_dir).
 
         Returns
         -------
         hidden : bool
             Whether the path exists and is hidden.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return is_hidden(os_path, self.root_dir)
 
     def file_exists(self, path):
         """Returns True if the file exists, else returns False.
 
         API-style wrapper for os.path.isfile
 
         Parameters
         ----------
         path : string
             The relative path to the file (with '/' as separator)
 
         Returns
         -------
         exists : bool
             Whether the file exists.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path)
         return os.path.isfile(os_path)
 
     def dir_exists(self, path):
         """Does the API-style path refer to an extant directory?
 
         API-style wrapper for os.path.isdir
 
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to root_dir).
 
         Returns
         -------
         exists : bool
             Whether the path is indeed a directory.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return os.path.isdir(os_path)
 
     def exists(self, path):
         """Returns True if the path exists, else returns False.
 
         API-style wrapper for os.path.exists
 
         Parameters
         ----------
         path : string
             The API path to the file (with '/' as separator)
 
         Returns
         -------
         exists : bool
             Whether the target exists.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return os.path.exists(os_path)
 
     def _base_model(self, path):
         """Build the common base of a contents model"""
         os_path = self._get_os_path(path)
         info = os.stat(os_path)
         last_modified = tz.utcfromtimestamp(info.st_mtime)
         created = tz.utcfromtimestamp(info.st_ctime)
         # Create the base model.
         model = {}
         model['name'] = path.rsplit('/', 1)[-1]
         model['path'] = path
         model['last_modified'] = last_modified
         model['created'] = created
         model['content'] = None
         model['format'] = None
         model['mimetype'] = None
         try:
             model['writable'] = os.access(os_path, os.W_OK)
         except OSError:
             self.log.error("Failed to check write permissions on %s", os_path)
             model['writable'] = False
         return model
 
     def _dir_model(self, path, content=True):
         """Build a model for a directory
 
         if content is requested, will include a listing of the directory
         """
         os_path = self._get_os_path(path)
 
         four_o_four = u'directory does not exist: %r' % path
 
         if not os.path.isdir(os_path):
             raise web.HTTPError(404, four_o_four)
         elif is_hidden(os_path, self.root_dir):
             self.log.info("Refusing to serve hidden directory %r, via 404 Error",
                 os_path
             )
             raise web.HTTPError(404, four_o_four)
 
         model = self._base_model(path)
         model['type'] = 'directory'
         if content:
             model['content'] = contents = []
             os_dir = self._get_os_path(path)
             for name in os.listdir(os_dir):
                 os_path = os.path.join(os_dir, name)
                 # skip over broken symlinks in listing
                 if not os.path.exists(os_path):
                     self.log.warn("%s doesn't exist", os_path)
                     continue
                 elif not os.path.isfile(os_path) and not os.path.isdir(os_path):
                     self.log.debug("%s not a regular file", os_path)
                     continue
                 if self.should_list(name) and not is_hidden(os_path, self.root_dir):
                     contents.append(self.get(
                         path='%s/%s' % (path, name),
                         content=False)
                     )
 
             model['format'] = 'json'
 
         return model
 
     def _file_model(self, path, content=True, format=None):
         """Build a model for a file
 
         if content is requested, include the file contents.
 
         format:
           If 'text', the contents will be decoded as UTF-8.
           If 'base64', the raw bytes contents will be encoded as base64.
           If not specified, try to decode as UTF-8, and fall back to base64
         """
         model = self._base_model(path)
         model['type'] = 'file'
 
         os_path = self._get_os_path(path)
 
         if content:
             content, format = self._read_file(os_path, format)
             default_mime = {
                 'text': 'text/plain',
                 'base64': 'application/octet-stream'
             }[format]
 
             model.update(
                 content=content,
                 format=format,
                 mimetype=mimetypes.guess_type(os_path)[0] or default_mime,
             )
 
         return model
 
     def _notebook_model(self, path, content=True):
         """Build a notebook model
 
         if content is requested, the notebook content will be populated
         as a JSON structure (not double-serialized)
         """
         model = self._base_model(path)
         model['type'] = 'notebook'
         if content:
             os_path = self._get_os_path(path)
             nb = self._read_notebook(os_path, as_version=4)
             self.mark_trusted_cells(nb, path)
             model['content'] = nb
             model['format'] = 'json'
             self.validate_notebook_model(model)
         return model
 
     def get(self, path, content=True, type=None, format=None):
         """ Takes a path for an entity and returns its model
 
         Parameters
         ----------
         path : str
             the API path that describes the relative path for the target
         content : bool
             Whether to include the contents in the reply
         type : str, optional
             The requested type - 'file', 'notebook', or 'directory'.
             Will raise HTTPError 400 if the content doesn't match.
         format : str, optional
             The requested format for file contents. 'text' or 'base64'.
             Ignored if this returns a notebook or directory model.
 
         Returns
         -------
         model : dict
             the contents model. If content=True, returns the contents
             of the file or directory as well.
         """
         path = path.strip('/')
 
         if not self.exists(path):
             raise web.HTTPError(404, u'No such file or directory: %s' % path)
 
         os_path = self._get_os_path(path)
         if os.path.isdir(os_path):
             if type not in (None, 'directory'):
                 raise web.HTTPError(400,
                                 u'%s is a directory, not a %s' % (path, type), reason='bad type')
             model = self._dir_model(path, content=content)
         elif type == 'notebook' or (type is None and path.endswith('.ipynb')):
             model = self._notebook_model(path, content=content)
         else:
             if type == 'directory':
                 raise web.HTTPError(400,
                                 u'%s is not a directory' % path, reason='bad type')
             model = self._file_model(path, content=content, format=format)
         return model
 
     def _save_directory(self, os_path, model, path=''):
         """create a directory"""
         if is_hidden(os_path, self.root_dir):
             raise web.HTTPError(400, u'Cannot create hidden directory %r' % os_path)
         if not os.path.exists(os_path):
             with self.perm_to_403():
                 os.mkdir(os_path)
         elif not os.path.isdir(os_path):
             raise web.HTTPError(400, u'Not a directory: %s' % (os_path))
         else:
             self.log.debug("Directory %r already exists", os_path)
 
     def save(self, model, path=''):
         """Save the file model and return the model with no content."""
         path = path.strip('/')
 
         if 'type' not in model:
             raise web.HTTPError(400, u'No file type provided')
         if 'content' not in model and model['type'] != 'directory':
             raise web.HTTPError(400, u'No file content provided')
 
-        self.run_pre_save_hook(model=model, path=path)
-
         os_path = self._get_os_path(path)
         self.log.debug("Saving %s", os_path)
+
+        self.run_pre_save_hook(model=model, path=path)
+
         try:
             if model['type'] == 'notebook':
                 nb = nbformat.from_dict(model['content'])
                 self.check_and_sign(nb, path)
                 self._save_notebook(os_path, nb)
                 # One checkpoint should always exist for notebooks.
                 if not self.checkpoints.list_checkpoints(path):
                     self.create_checkpoint(path)
             elif model['type'] == 'file':
                 # Missing format will be handled internally by _save_file.
                 self._save_file(os_path, model['content'], model.get('format'))
             elif model['type'] == 'directory':
                 self._save_directory(os_path, model, path)
             else:
                 raise web.HTTPError(400, "Unhandled contents type: %s" % model['type'])
         except web.HTTPError:
             raise
         except Exception as e:
             self.log.error(u'Error while saving file: %s %s', path, e, exc_info=True)
             raise web.HTTPError(500, u'Unexpected error while saving file: %s %s' % (path, e))
 
         validation_message = None
         if model['type'] == 'notebook':
             self.validate_notebook_model(model)
             validation_message = model.get('message', None)
 
         model = self.get(path, content=False)
         if validation_message:
             model['message'] = validation_message
 
         self.run_post_save_hook(model=model, os_path=os_path)
 
         return model
 
     def delete_file(self, path):
         """Delete file at path."""
         path = path.strip('/')
         os_path = self._get_os_path(path)
         rm = os.unlink
         if os.path.isdir(os_path):
             listing = os.listdir(os_path)
             # Don't delete non-empty directories.
             # A directory containing only leftover checkpoints is
             # considered empty.
             cp_dir = getattr(self.checkpoints, 'checkpoint_dir', None)
             for entry in listing:
                 if entry != cp_dir:
                     raise web.HTTPError(400, u'Directory %s not empty' % os_path)
         elif not os.path.isfile(os_path):
             raise web.HTTPError(404, u'File does not exist: %s' % os_path)
 
         if os.path.isdir(os_path):
             self.log.debug("Removing directory %s", os_path)
             with self.perm_to_403():
                 shutil.rmtree(os_path)
         else:
             self.log.debug("Unlinking file %s", os_path)
             with self.perm_to_403():
                 rm(os_path)
 
     def rename_file(self, old_path, new_path):
         """Rename a file."""
         old_path = old_path.strip('/')
         new_path = new_path.strip('/')
         if new_path == old_path:
             return
 
         new_os_path = self._get_os_path(new_path)
         old_os_path = self._get_os_path(old_path)
 
         # Should we proceed with the move?
         if os.path.exists(new_os_path):
             raise web.HTTPError(409, u'File already exists: %s' % new_path)
 
         # Move the file
         try:
             with self.perm_to_403():
                 shutil.move(old_os_path, new_os_path)
         except web.HTTPError:
             raise
         except Exception as e:
             raise web.HTTPError(500, u'Unknown error renaming file: %s %s' % (old_path, e))
 
     def info_string(self):
         return "Serving notebooks from local directory: %s" % self.root_dir
 
     def get_kernel_path(self, path, model=None):
         """Return the initial API path of  a kernel associated with a given notebook"""
         if '/' in path:
             parent_dir = path.rsplit('/', 1)[0]
         else:
             parent_dir = ''
         return parent_dir

IPython/html/services/contents/tests/test_manager.py

@@ -1,464 +1,500 b''
 # coding: utf-8
 """Tests for the notebook manager."""
 from __future__ import print_function
 
 import os
 import sys
 import time
+from contextlib import contextmanager
 
 from nose import SkipTest
 from tornado.web import HTTPError
 from unittest import TestCase
 from tempfile import NamedTemporaryFile
 
 from IPython.nbformat import v4 as nbformat
 
 from IPython.utils.tempdir import TemporaryDirectory
 from IPython.utils.traitlets import TraitError
 from IPython.html.utils import url_path_join
 from IPython.testing import decorators as dec
 
 from ..filemanager import FileContentsManager
 
 
 def _make_dir(contents_manager, api_path):
     """
     Make a directory.
     """
     os_path = contents_manager._get_os_path(api_path)
     try:
         os.makedirs(os_path)
     except OSError:
         print("Directory already exists: %r" % os_path)
 
 
 class TestFileContentsManager(TestCase):
 
     def symlink(self, contents_manager, src, dst):
         """Make a symlink to src from dst
         
         src and dst are api_paths
         """
         src_os_path = contents_manager._get_os_path(src)
         dst_os_path = contents_manager._get_os_path(dst)
         print(src_os_path, dst_os_path, os.path.isfile(src_os_path))
         os.symlink(src_os_path, dst_os_path)
 
     def test_root_dir(self):
         with TemporaryDirectory() as td:
             fm = FileContentsManager(root_dir=td)
             self.assertEqual(fm.root_dir, td)
 
     def test_missing_root_dir(self):
         with TemporaryDirectory() as td:
             root = os.path.join(td, 'notebook', 'dir', 'is', 'missing')
             self.assertRaises(TraitError, FileContentsManager, root_dir=root)
 
     def test_invalid_root_dir(self):
         with NamedTemporaryFile() as tf:
             self.assertRaises(TraitError, FileContentsManager, root_dir=tf.name)
 
     def test_get_os_path(self):
         # full filesystem path should be returned with correct operating system
         # separators.
         with TemporaryDirectory() as td:
             root = td
             fm = FileContentsManager(root_dir=root)
             path = fm._get_os_path('/path/to/notebook/test.ipynb')
             rel_path_list =  '/path/to/notebook/test.ipynb'.split('/')
             fs_path = os.path.join(fm.root_dir, *rel_path_list)
             self.assertEqual(path, fs_path)
 
             fm = FileContentsManager(root_dir=root)
             path = fm._get_os_path('test.ipynb')
             fs_path = os.path.join(fm.root_dir, 'test.ipynb')
             self.assertEqual(path, fs_path)
 
             fm = FileContentsManager(root_dir=root)
             path = fm._get_os_path('////test.ipynb')
             fs_path = os.path.join(fm.root_dir, 'test.ipynb')
             self.assertEqual(path, fs_path)
 
     def test_checkpoint_subdir(self):
         subd = u'sub ∂ir'
         cp_name = 'test-cp.ipynb'
         with TemporaryDirectory() as td:
             root = td
             os.mkdir(os.path.join(td, subd))
             fm = FileContentsManager(root_dir=root)
             cpm = fm.checkpoints
             cp_dir = cpm.checkpoint_path(
                 'cp', 'test.ipynb'
             )
             cp_subdir = cpm.checkpoint_path(
                 'cp', '/%s/test.ipynb' % subd
             )
         self.assertNotEqual(cp_dir, cp_subdir)
         self.assertEqual(cp_dir, os.path.join(root, cpm.checkpoint_dir, cp_name))
         self.assertEqual(cp_subdir, os.path.join(root, subd, cpm.checkpoint_dir, cp_name))
     
     @dec.skip_win32
     def test_bad_symlink(self):
         with TemporaryDirectory() as td:
             cm = FileContentsManager(root_dir=td)
             path = 'test bad symlink'
             _make_dir(cm, path)
 
             file_model = cm.new_untitled(path=path, ext='.txt')
 
             # create a broken symlink
             self.symlink(cm, "target", '%s/%s' % (path, 'bad symlink'))
             model = cm.get(path)
             self.assertEqual(model['content'], [file_model])
     
     @dec.skip_win32
     def test_good_symlink(self):
         with TemporaryDirectory() as td:
             cm = FileContentsManager(root_dir=td)
             parent = 'test good symlink'
             name = 'good symlink'
             path = '{0}/{1}'.format(parent, name)
             _make_dir(cm, parent)
 
             file_model = cm.new(path=parent + '/zfoo.txt')
 
             # create a good symlink
             self.symlink(cm, file_model['path'], path)
             symlink_model = cm.get(path, content=False)
             dir_model = cm.get(parent)
             self.assertEqual(
                 sorted(dir_model['content'], key=lambda x: x['name']),
                 [symlink_model, file_model],
             )
     
     def test_403(self):
         if hasattr(os, 'getuid'):
             if os.getuid() == 0:
                 raise SkipTest("Can't test permissions as root")
         if sys.platform.startswith('win'):
             raise SkipTest("Can't test permissions on Windows")
         
         with TemporaryDirectory() as td:
             cm = FileContentsManager(root_dir=td)
             model = cm.new_untitled(type='file')
             os_path = cm._get_os_path(model['path'])
         
             os.chmod(os_path, 0o400)
             try:
                 with cm.open(os_path, 'w') as f:
                     f.write(u"don't care")
             except HTTPError as e:
                 self.assertEqual(e.status_code, 403)
             else:
                 self.fail("Should have raised HTTPError(403)")
 
 
 class TestContentsManager(TestCase):
     
     def setUp(self):
         self._temp_dir = TemporaryDirectory()
         self.td = self._temp_dir.name
         self.contents_manager = FileContentsManager(
             root_dir=self.td,
         )
 
     def tearDown(self):
         self._temp_dir.cleanup()
-
+    
+    @contextmanager
+    def assertRaisesHTTPError(self, status, msg=None):
+        msg = msg or "Should have raised HTTPError(%i)" % status
+        try:
+            yield
+        except HTTPError as e:
+            self.assertEqual(e.status_code, status)
+        else:
+            self.fail(msg)
+    
     def make_dir(self, api_path):
         """make a subdirectory at api_path
         
         override in subclasses if contents are not on the filesystem.
         """
         _make_dir(self.contents_manager, api_path)
 
     def add_code_cell(self, nb):
         output = nbformat.new_output("display_data", {'application/javascript': "alert('hi');"})
         cell = nbformat.new_code_cell("print('hi')", outputs=[output])
         nb.cells.append(cell)
 
     def new_notebook(self):
         cm = self.contents_manager
         model = cm.new_untitled(type='notebook')
         name = model['name']
         path = model['path']
 
         full_model = cm.get(path)
         nb = full_model['content']
         nb['metadata']['counter'] = int(1e6 * time.time())
         self.add_code_cell(nb)
 
         cm.save(full_model, path)
         return nb, name, path
 
     def test_new_untitled(self):
         cm = self.contents_manager
         # Test in root directory
         model = cm.new_untitled(type='notebook')
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertIn('type', model)
         self.assertEqual(model['type'], 'notebook')
         self.assertEqual(model['name'], 'Untitled.ipynb')
         self.assertEqual(model['path'], 'Untitled.ipynb')
 
         # Test in sub-directory
         model = cm.new_untitled(type='directory')
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertIn('type', model)
         self.assertEqual(model['type'], 'directory')
         self.assertEqual(model['name'], 'Untitled Folder')
         self.assertEqual(model['path'], 'Untitled Folder')
         sub_dir = model['path']
         
         model = cm.new_untitled(path=sub_dir)
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertIn('type', model)
         self.assertEqual(model['type'], 'file')
         self.assertEqual(model['name'], 'untitled')
         self.assertEqual(model['path'], '%s/untitled' % sub_dir)
 
     def test_get(self):
         cm = self.contents_manager
         # Create a notebook
         model = cm.new_untitled(type='notebook')
         name = model['name']
         path = model['path']
 
         # Check that we 'get' on the notebook we just created
         model2 = cm.get(path)
         assert isinstance(model2, dict)
         self.assertIn('name', model2)
         self.assertIn('path', model2)
         self.assertEqual(model['name'], name)
         self.assertEqual(model['path'], path)
 
         nb_as_file = cm.get(path, content=True, type='file')
         self.assertEqual(nb_as_file['path'], path)
         self.assertEqual(nb_as_file['type'], 'file')
         self.assertEqual(nb_as_file['format'], 'text')
         self.assertNotIsInstance(nb_as_file['content'], dict)
 
         nb_as_bin_file = cm.get(path, content=True, type='file', format='base64')
         self.assertEqual(nb_as_bin_file['format'], 'base64')
 
         # Test in sub-directory
         sub_dir = '/foo/'
         self.make_dir('foo')
         model = cm.new_untitled(path=sub_dir, ext='.ipynb')
         model2 = cm.get(sub_dir + name)
         assert isinstance(model2, dict)
         self.assertIn('name', model2)
         self.assertIn('path', model2)
         self.assertIn('content', model2)
         self.assertEqual(model2['name'], 'Untitled.ipynb')
         self.assertEqual(model2['path'], '{0}/{1}'.format(sub_dir.strip('/'), name))
 
         # Test with a regular file.
         file_model_path = cm.new_untitled(path=sub_dir, ext='.txt')['path']
         file_model = cm.get(file_model_path)
         self.assertDictContainsSubset(
             {
                 'content': u'',
                 'format': u'text',
                 'mimetype': u'text/plain',
                 'name': u'untitled.txt',
                 'path': u'foo/untitled.txt',
                 'type': u'file',
                 'writable': True,
             },
             file_model,
         )
         self.assertIn('created', file_model)
         self.assertIn('last_modified', file_model)
 
         # Test getting directory model
 
         # Create a sub-sub directory to test getting directory contents with a
         # subdir.
         self.make_dir('foo/bar')
         dirmodel = cm.get('foo')
         self.assertEqual(dirmodel['type'], 'directory')
         self.assertIsInstance(dirmodel['content'], list)
         self.assertEqual(len(dirmodel['content']), 3)
         self.assertEqual(dirmodel['path'], 'foo')
         self.assertEqual(dirmodel['name'], 'foo')
 
         # Directory contents should match the contents of each individual entry
         # when requested with content=False.
         model2_no_content = cm.get(sub_dir + name, content=False)
         file_model_no_content = cm.get(u'foo/untitled.txt', content=False)
         sub_sub_dir_no_content = cm.get('foo/bar', content=False)
         self.assertEqual(sub_sub_dir_no_content['path'], 'foo/bar')
         self.assertEqual(sub_sub_dir_no_content['name'], 'bar')
 
         for entry in dirmodel['content']:
             # Order isn't guaranteed by the spec, so this is a hacky way of
             # verifying that all entries are matched.
             if entry['path'] == sub_sub_dir_no_content['path']:
                 self.assertEqual(entry, sub_sub_dir_no_content)
             elif entry['path'] == model2_no_content['path']:
                 self.assertEqual(entry, model2_no_content)
             elif entry['path'] == file_model_no_content['path']:
                 self.assertEqual(entry, file_model_no_content)
             else:
                 self.fail("Unexpected directory entry: %s" % entry())
 
         with self.assertRaises(HTTPError):
             cm.get('foo', type='file')
 
     def test_update(self):
         cm = self.contents_manager
         # Create a notebook
         model = cm.new_untitled(type='notebook')
         name = model['name']
         path = model['path']
 
         # Change the name in the model for rename
         model['path'] = 'test.ipynb'
         model = cm.update(model, path)
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertEqual(model['name'], 'test.ipynb')
 
         # Make sure the old name is gone
         self.assertRaises(HTTPError, cm.get, path)
 
         # Test in sub-directory
         # Create a directory and notebook in that directory
         sub_dir = '/foo/'
         self.make_dir('foo')
         model = cm.new_untitled(path=sub_dir, type='notebook')
         path = model['path']
 
         # Change the name in the model for rename
         d = path.rsplit('/', 1)[0]
         new_path = model['path'] = d + '/test_in_sub.ipynb'
         model = cm.update(model, path)
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertEqual(model['name'], 'test_in_sub.ipynb')
         self.assertEqual(model['path'], new_path)
 
         # Make sure the old name is gone
         self.assertRaises(HTTPError, cm.get, path)
 
     def test_save(self):
         cm = self.contents_manager
         # Create a notebook
         model = cm.new_untitled(type='notebook')
         name = model['name']
         path = model['path']
 
         # Get the model with 'content'
         full_model = cm.get(path)
 
         # Save the notebook
         model = cm.save(full_model, path)
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertEqual(model['name'], name)
         self.assertEqual(model['path'], path)
 
         # Test in sub-directory
         # Create a directory and notebook in that directory
         sub_dir = '/foo/'
         self.make_dir('foo')
         model = cm.new_untitled(path=sub_dir, type='notebook')
         name = model['name']
         path = model['path']
         model = cm.get(path)
 
         # Change the name in the model for rename
         model = cm.save(model, path)
         assert isinstance(model, dict)
         self.assertIn('name', model)
         self.assertIn('path', model)
         self.assertEqual(model['name'], 'Untitled.ipynb')
         self.assertEqual(model['path'], 'foo/Untitled.ipynb')
 
     def test_delete(self):
         cm = self.contents_manager
         # Create a notebook
         nb, name, path = self.new_notebook()
 
         # Delete the notebook
         cm.delete(path)
 
         # Check that deleting a non-existent path raises an error.
         self.assertRaises(HTTPError, cm.delete, path)
 
         # Check that a 'get' on the deleted notebook raises and error
         self.assertRaises(HTTPError, cm.get, path)
 
     def test_copy(self):
         cm = self.contents_manager
         parent = u'å b'
         name = u'nb √.ipynb'
         path = u'{0}/{1}'.format(parent, name)
         self.make_dir(parent)
 
         orig = cm.new(path=path)
         # copy with unspecified name
         copy = cm.copy(path)
         self.assertEqual(copy['name'], orig['name'].replace('.ipynb', '-Copy1.ipynb'))
 
         # copy with specified name
         copy2 = cm.copy(path, u'å b/copy 2.ipynb')
         self.assertEqual(copy2['name'], u'copy 2.ipynb')
         self.assertEqual(copy2['path'], u'å b/copy 2.ipynb')
         # copy with specified path
         copy2 = cm.copy(path, u'/')
         self.assertEqual(copy2['name'], name)
         self.assertEqual(copy2['path'], name)
 
     def test_trust_notebook(self):
         cm = self.contents_manager
         nb, name, path = self.new_notebook()
 
         untrusted = cm.get(path)['content']
         assert not cm.notary.check_cells(untrusted)
 
         # print(untrusted)
         cm.trust_notebook(path)
         trusted = cm.get(path)['content']
         # print(trusted)
         assert cm.notary.check_cells(trusted)
 
     def test_mark_trusted_cells(self):
         cm = self.contents_manager
         nb, name, path = self.new_notebook()
 
         cm.mark_trusted_cells(nb, path)
         for cell in nb.cells:
             if cell.cell_type == 'code':
                 assert not cell.metadata.trusted
 
         cm.trust_notebook(path)
         nb = cm.get(path)['content']
         for cell in nb.cells:
             if cell.cell_type == 'code':
                 assert cell.metadata.trusted
 
     def test_check_and_sign(self):
         cm = self.contents_manager
         nb, name, path = self.new_notebook()
 
         cm.mark_trusted_cells(nb, path)
         cm.check_and_sign(nb, path)
         assert not cm.notary.check_signature(nb)
 
         cm.trust_notebook(path)
         nb = cm.get(path)['content']
         cm.mark_trusted_cells(nb, path)
         cm.check_and_sign(nb, path)
         assert cm.notary.check_signature(nb)
+    
+    def test_escape_root(self):
+        cm = self.contents_manager
+        # make foo, bar next to root
+        with open(os.path.join(cm.root_dir, '..', 'foo'), 'w') as f:
+            f.write('foo')
+        with open(os.path.join(cm.root_dir, '..', 'bar'), 'w') as f:
+            f.write('bar')
+        
+        with self.assertRaisesHTTPError(404):
+            cm.get('..')
+        with self.assertRaisesHTTPError(404):
+            cm.get('foo/../../../bar')
+        with self.assertRaisesHTTPError(404):
+            cm.delete('../foo')
+        with self.assertRaisesHTTPError(404):
+            cm.rename('../foo', '../bar')
+        with self.assertRaisesHTTPError(404):
+            cm.save(model={
+                'type': 'file',
+                'content': u'',
+                'format': 'text',
+            }, path='../foo')
+        
+