anonymousland-synapse/synapse/media/filepath.py

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# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2020-2021 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
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import functools
import os
import re
import string
from typing import Any, Callable, List, TypeVar, Union, cast
NEW_FORMAT_ID_RE = re.compile(r"^\d\d\d\d-\d\d-\d\d")
F = TypeVar("F", bound=Callable[..., str])
def _wrap_in_base_path(func: F) -> F:
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"""Takes a function that returns a relative path and turns it into an
absolute path based on the location of the primary media store
"""
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@functools.wraps(func)
def _wrapped(self: "MediaFilePaths", *args: Any, **kwargs: Any) -> str:
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path = func(self, *args, **kwargs)
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return os.path.join(self.base_path, path)
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return cast(F, _wrapped)
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GetPathMethod = TypeVar(
"GetPathMethod", bound=Union[Callable[..., str], Callable[..., List[str]]]
)
def _wrap_with_jail_check(relative: bool) -> Callable[[GetPathMethod], GetPathMethod]:
"""Wraps a path-returning method to check that the returned path(s) do not escape
the media store directory.
The path-returning method may return either a single path, or a list of paths.
The check is not expected to ever fail, unless `func` is missing a call to
`_validate_path_component`, or `_validate_path_component` is buggy.
Args:
relative: A boolean indicating whether the wrapped method returns paths relative
to the media store directory.
Returns:
A method which will wrap a path-returning method, adding a check to ensure that
the returned path(s) lie within the media store directory. The check will raise
a `ValueError` if it fails.
"""
def _wrap_with_jail_check_inner(func: GetPathMethod) -> GetPathMethod:
@functools.wraps(func)
def _wrapped(
self: "MediaFilePaths", *args: Any, **kwargs: Any
) -> Union[str, List[str]]:
path_or_paths = func(self, *args, **kwargs)
if isinstance(path_or_paths, list):
paths_to_check = path_or_paths
else:
paths_to_check = [path_or_paths]
for path in paths_to_check:
# Construct the path that will ultimately be used.
# We cannot guess whether `path` is relative to the media store
# directory, since the media store directory may itself be a relative
# path.
if relative:
path = os.path.join(self.base_path, path)
normalized_path = os.path.normpath(path)
# Now that `normpath` has eliminated `../`s and `./`s from the path,
# `os.path.commonpath` can be used to check whether it lies within the
# media store directory.
if (
os.path.commonpath([normalized_path, self.normalized_base_path])
!= self.normalized_base_path
):
# The path resolves to outside the media store directory,
# or `self.base_path` is `.`, which is an unlikely configuration.
raise ValueError(f"Invalid media store path: {path!r}")
# Note that `os.path.normpath`/`abspath` has a subtle caveat:
# `a/b/c/../c` will normalize to `a/b/c`, but the former refers to a
# different path if `a/b/c` is a symlink. That is, the check above is
# not perfect and may allow a certain restricted subset of untrustworthy
# paths through. Since the check above is secondary to the main
# `_validate_path_component` checks, it's less important for it to be
# perfect.
#
# As an alternative, `os.path.realpath` will resolve symlinks, but
# proves problematic if there are symlinks inside the media store.
# eg. if `url_store/` is symlinked to elsewhere, its canonical path
# won't match that of the main media store directory.
return path_or_paths
return cast(GetPathMethod, _wrapped)
return _wrap_with_jail_check_inner
ALLOWED_CHARACTERS = set(
string.ascii_letters
+ string.digits
+ "_-"
+ ".[]:" # Domain names, IPv6 addresses and ports in server names
)
FORBIDDEN_NAMES = {
"",
os.path.curdir, # "." for the current platform
os.path.pardir, # ".." for the current platform
}
def _validate_path_component(name: str) -> str:
"""Checks that the given string can be safely used as a path component
Args:
name: The path component to check.
Returns:
The path component if valid.
Raises:
ValueError: If `name` cannot be safely used as a path component.
"""
if not ALLOWED_CHARACTERS.issuperset(name) or name in FORBIDDEN_NAMES:
raise ValueError(f"Invalid path component: {name!r}")
return name
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class MediaFilePaths:
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"""Describes where files are stored on disk.
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Most of the functions have a `*_rel` variant which returns a file path that
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is relative to the base media store path. This is mainly used when we want
to write to the backup media store (when one is configured)
"""
def __init__(self, primary_base_path: str):
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self.base_path = primary_base_path
self.normalized_base_path = os.path.normpath(self.base_path)
# Refuse to initialize if paths cannot be validated correctly for the current
# platform.
assert os.path.sep not in ALLOWED_CHARACTERS
assert os.path.altsep not in ALLOWED_CHARACTERS
# On Windows, paths have all sorts of weirdness which `_validate_path_component`
# does not consider. In any case, the remote media store can't work correctly
# for certain homeservers there, since ":"s aren't allowed in paths.
assert os.name == "posix"
@_wrap_with_jail_check(relative=True)
def local_media_filepath_rel(self, media_id: str) -> str:
return os.path.join(
"local_content",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
)
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local_media_filepath = _wrap_in_base_path(local_media_filepath_rel)
@_wrap_with_jail_check(relative=True)
def local_media_thumbnail_rel(
self, media_id: str, width: int, height: int, content_type: str, method: str
) -> str:
top_level_type, sub_type = content_type.split("/")
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file_name = "%i-%i-%s-%s-%s" % (width, height, top_level_type, sub_type, method)
return os.path.join(
"local_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
_validate_path_component(file_name),
)
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local_media_thumbnail = _wrap_in_base_path(local_media_thumbnail_rel)
@_wrap_with_jail_check(relative=False)
def local_media_thumbnail_dir(self, media_id: str) -> str:
"""
Retrieve the local store path of thumbnails of a given media_id
Args:
media_id: The media ID to query.
Returns:
Path of local_thumbnails from media_id
"""
return os.path.join(
self.base_path,
"local_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
)
@_wrap_with_jail_check(relative=True)
def remote_media_filepath_rel(self, server_name: str, file_id: str) -> str:
return os.path.join(
"remote_content",
_validate_path_component(server_name),
_validate_path_component(file_id[0:2]),
_validate_path_component(file_id[2:4]),
_validate_path_component(file_id[4:]),
)
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remote_media_filepath = _wrap_in_base_path(remote_media_filepath_rel)
@_wrap_with_jail_check(relative=True)
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def remote_media_thumbnail_rel(
self,
server_name: str,
file_id: str,
width: int,
height: int,
content_type: str,
method: str,
) -> str:
top_level_type, sub_type = content_type.split("/")
file_name = "%i-%i-%s-%s-%s" % (width, height, top_level_type, sub_type, method)
return os.path.join(
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"remote_thumbnail",
_validate_path_component(server_name),
_validate_path_component(file_id[0:2]),
_validate_path_component(file_id[2:4]),
_validate_path_component(file_id[4:]),
_validate_path_component(file_name),
)
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remote_media_thumbnail = _wrap_in_base_path(remote_media_thumbnail_rel)
# Legacy path that was used to store thumbnails previously.
# Should be removed after some time, when most of the thumbnails are stored
# using the new path.
@_wrap_with_jail_check(relative=True)
def remote_media_thumbnail_rel_legacy(
self, server_name: str, file_id: str, width: int, height: int, content_type: str
) -> str:
top_level_type, sub_type = content_type.split("/")
file_name = "%i-%i-%s-%s" % (width, height, top_level_type, sub_type)
return os.path.join(
"remote_thumbnail",
_validate_path_component(server_name),
_validate_path_component(file_id[0:2]),
_validate_path_component(file_id[2:4]),
_validate_path_component(file_id[4:]),
_validate_path_component(file_name),
)
@_wrap_with_jail_check(relative=False)
def remote_media_thumbnail_dir(self, server_name: str, file_id: str) -> str:
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return os.path.join(
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self.base_path,
"remote_thumbnail",
_validate_path_component(server_name),
_validate_path_component(file_id[0:2]),
_validate_path_component(file_id[2:4]),
_validate_path_component(file_id[4:]),
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)
@_wrap_with_jail_check(relative=True)
def url_cache_filepath_rel(self, media_id: str) -> str:
if NEW_FORMAT_ID_RE.match(media_id):
# Media id is of the form <DATE><RANDOM_STRING>
# E.g.: 2017-09-28-fsdRDt24DS234dsf
return os.path.join(
"url_cache",
_validate_path_component(media_id[:10]),
_validate_path_component(media_id[11:]),
)
else:
return os.path.join(
"url_cache",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
)
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url_cache_filepath = _wrap_in_base_path(url_cache_filepath_rel)
@_wrap_with_jail_check(relative=False)
def url_cache_filepath_dirs_to_delete(self, media_id: str) -> List[str]:
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"The dirs to try and remove if we delete the media_id file"
if NEW_FORMAT_ID_RE.match(media_id):
return [
os.path.join(
self.base_path, "url_cache", _validate_path_component(media_id[:10])
)
]
else:
return [
os.path.join(
self.base_path,
"url_cache",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
),
os.path.join(
self.base_path, "url_cache", _validate_path_component(media_id[0:2])
),
]
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@_wrap_with_jail_check(relative=True)
def url_cache_thumbnail_rel(
self, media_id: str, width: int, height: int, content_type: str, method: str
) -> str:
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# Media id is of the form <DATE><RANDOM_STRING>
# E.g.: 2017-09-28-fsdRDt24DS234dsf
top_level_type, sub_type = content_type.split("/")
file_name = "%i-%i-%s-%s-%s" % (width, height, top_level_type, sub_type, method)
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if NEW_FORMAT_ID_RE.match(media_id):
return os.path.join(
"url_cache_thumbnails",
_validate_path_component(media_id[:10]),
_validate_path_component(media_id[11:]),
_validate_path_component(file_name),
)
else:
return os.path.join(
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"url_cache_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
_validate_path_component(file_name),
)
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url_cache_thumbnail = _wrap_in_base_path(url_cache_thumbnail_rel)
@_wrap_with_jail_check(relative=True)
def url_cache_thumbnail_directory_rel(self, media_id: str) -> str:
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# Media id is of the form <DATE><RANDOM_STRING>
# E.g.: 2017-09-28-fsdRDt24DS234dsf
if NEW_FORMAT_ID_RE.match(media_id):
return os.path.join(
"url_cache_thumbnails",
_validate_path_component(media_id[:10]),
_validate_path_component(media_id[11:]),
)
else:
return os.path.join(
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"url_cache_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
)
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url_cache_thumbnail_directory = _wrap_in_base_path(
url_cache_thumbnail_directory_rel
)
@_wrap_with_jail_check(relative=False)
def url_cache_thumbnail_dirs_to_delete(self, media_id: str) -> List[str]:
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"The dirs to try and remove if we delete the media_id thumbnails"
# Media id is of the form <DATE><RANDOM_STRING>
# E.g.: 2017-09-28-fsdRDt24DS234dsf
if NEW_FORMAT_ID_RE.match(media_id):
return [
os.path.join(
self.base_path,
"url_cache_thumbnails",
_validate_path_component(media_id[:10]),
_validate_path_component(media_id[11:]),
),
os.path.join(
self.base_path,
"url_cache_thumbnails",
_validate_path_component(media_id[:10]),
),
]
else:
return [
os.path.join(
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self.base_path,
"url_cache_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
_validate_path_component(media_id[4:]),
),
os.path.join(
self.base_path,
"url_cache_thumbnails",
_validate_path_component(media_id[0:2]),
_validate_path_component(media_id[2:4]),
),
os.path.join(
self.base_path,
"url_cache_thumbnails",
_validate_path_component(media_id[0:2]),
),
]