diff options
Diffstat (limited to 'synapse/rest/media/v1/filepath.py')
| -rw-r--r-- | synapse/rest/media/v1/filepath.py | 241 |
1 files changed, 199 insertions, 42 deletions
diff --git a/synapse/rest/media/v1/filepath.py b/synapse/rest/media/v1/filepath.py index bec77088ee..c0e15c6513 100644 --- a/synapse/rest/media/v1/filepath.py +++ b/synapse/rest/media/v1/filepath.py @@ -16,7 +16,8 @@ import functools import os import re -from typing import Any, Callable, List, TypeVar, cast +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") @@ -37,6 +38,85 @@ def _wrap_in_base_path(func: F) -> F: return cast(F, _wrapped) +GetPathMethod = TypeVar( + "GetPathMethod", bound=Union[Callable[..., str], Callable[..., List[str]]] +) + + +def _wrap_with_jail_check(func: GetPathMethod) -> GetPathMethod: + """Wraps a path-returning method to check that the returned path(s) do not escape + the media store directory. + + 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: + func: The `MediaFilePaths` method to wrap. The method may return either a single + path, or a list of paths. Returned paths may be either absolute or relative. + + Returns: + The method, wrapped with a check to ensure that the returned path(s) lie within + the media store directory. Raises a `ValueError` if the check fails. + """ + + @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: + # path may be an absolute or relative path, depending on the method being + # wrapped. When "appending" an absolute path, `os.path.join` discards the + # previous path, which is desired here. + normalized_path = os.path.normpath(os.path.join(self.real_base_path, path)) + if ( + os.path.commonpath([normalized_path, self.real_base_path]) + != self.real_base_path + ): + raise ValueError(f"Invalid media store path: {path!r}") + + return path_or_paths + + return cast(GetPathMethod, _wrapped) + + +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 + + class MediaFilePaths: """Describes where files are stored on disk. @@ -48,22 +128,46 @@ class MediaFilePaths: def __init__(self, primary_base_path: str): self.base_path = primary_base_path + # The media store directory, with all symlinks resolved. + self.real_base_path = os.path.realpath(primary_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 def local_media_filepath_rel(self, media_id: str) -> str: - return os.path.join("local_content", media_id[0:2], media_id[2:4], media_id[4:]) + 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:]), + ) local_media_filepath = _wrap_in_base_path(local_media_filepath_rel) + @_wrap_with_jail_check 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("/") file_name = "%i-%i-%s-%s-%s" % (width, height, top_level_type, sub_type, method) return os.path.join( - "local_thumbnails", media_id[0:2], media_id[2:4], media_id[4:], file_name + "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), ) local_media_thumbnail = _wrap_in_base_path(local_media_thumbnail_rel) + @_wrap_with_jail_check def local_media_thumbnail_dir(self, media_id: str) -> str: """ Retrieve the local store path of thumbnails of a given media_id @@ -76,18 +180,24 @@ class MediaFilePaths: return os.path.join( self.base_path, "local_thumbnails", - media_id[0:2], - media_id[2:4], - media_id[4:], + _validate_path_component(media_id[0:2]), + _validate_path_component(media_id[2:4]), + _validate_path_component(media_id[4:]), ) + @_wrap_with_jail_check def remote_media_filepath_rel(self, server_name: str, file_id: str) -> str: return os.path.join( - "remote_content", server_name, file_id[0:2], file_id[2:4], file_id[4:] + "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:]), ) remote_media_filepath = _wrap_in_base_path(remote_media_filepath_rel) + @_wrap_with_jail_check def remote_media_thumbnail_rel( self, server_name: str, @@ -101,11 +211,11 @@ class MediaFilePaths: file_name = "%i-%i-%s-%s-%s" % (width, height, top_level_type, sub_type, method) return os.path.join( "remote_thumbnail", - server_name, - file_id[0:2], - file_id[2:4], - file_id[4:], - file_name, + _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), ) remote_media_thumbnail = _wrap_in_base_path(remote_media_thumbnail_rel) @@ -113,6 +223,7 @@ class MediaFilePaths: # 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 def remote_media_thumbnail_rel_legacy( self, server_name: str, file_id: str, width: int, height: int, content_type: str ) -> str: @@ -120,43 +231,66 @@ class MediaFilePaths: file_name = "%i-%i-%s-%s" % (width, height, top_level_type, sub_type) return os.path.join( "remote_thumbnail", - server_name, - file_id[0:2], - file_id[2:4], - file_id[4:], - file_name, + _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), ) def remote_media_thumbnail_dir(self, server_name: str, file_id: str) -> str: return os.path.join( self.base_path, "remote_thumbnail", - server_name, - file_id[0:2], - file_id[2:4], - file_id[4:], + _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:]), ) + @_wrap_with_jail_check 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", media_id[:10], media_id[11:]) + 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", media_id[0:2], media_id[2:4], media_id[4:]) + 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:]), + ) url_cache_filepath = _wrap_in_base_path(url_cache_filepath_rel) + @_wrap_with_jail_check def url_cache_filepath_dirs_to_delete(self, media_id: str) -> List[str]: "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", media_id[:10])] + 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", media_id[0:2], media_id[2:4]), - os.path.join(self.base_path, "url_cache", media_id[0:2]), + 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]) + ), ] + @_wrap_with_jail_check def url_cache_thumbnail_rel( self, media_id: str, width: int, height: int, content_type: str, method: str ) -> str: @@ -168,37 +302,46 @@ class MediaFilePaths: if NEW_FORMAT_ID_RE.match(media_id): return os.path.join( - "url_cache_thumbnails", media_id[:10], media_id[11:], file_name + "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( "url_cache_thumbnails", - media_id[0:2], - media_id[2:4], - media_id[4:], - file_name, + _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), ) url_cache_thumbnail = _wrap_in_base_path(url_cache_thumbnail_rel) + @_wrap_with_jail_check def url_cache_thumbnail_directory_rel(self, media_id: str) -> str: # 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", media_id[:10], media_id[11:]) + return os.path.join( + "url_cache_thumbnails", + _validate_path_component(media_id[:10]), + _validate_path_component(media_id[11:]), + ) else: return os.path.join( "url_cache_thumbnails", - media_id[0:2], - media_id[2:4], - media_id[4:], + _validate_path_component(media_id[0:2]), + _validate_path_component(media_id[2:4]), + _validate_path_component(media_id[4:]), ) url_cache_thumbnail_directory = _wrap_in_base_path( url_cache_thumbnail_directory_rel ) + @_wrap_with_jail_check def url_cache_thumbnail_dirs_to_delete(self, media_id: str) -> List[str]: "The dirs to try and remove if we delete the media_id thumbnails" # Media id is of the form <DATE><RANDOM_STRING> @@ -206,21 +349,35 @@ class MediaFilePaths: if NEW_FORMAT_ID_RE.match(media_id): return [ os.path.join( - self.base_path, "url_cache_thumbnails", media_id[:10], media_id[11:] + 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]), ), - os.path.join(self.base_path, "url_cache_thumbnails", media_id[:10]), ] else: return [ os.path.join( self.base_path, "url_cache_thumbnails", - media_id[0:2], - media_id[2:4], - media_id[4:], + _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", media_id[0:2], media_id[2:4] + 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]), ), - os.path.join(self.base_path, "url_cache_thumbnails", media_id[0:2]), ] |