From 03318a766cac9f8b053db2214d9c332a977d226c Mon Sep 17 00:00:00 2001 From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com> Date: Tue, 11 May 2021 10:47:23 +0100 Subject: Merge pull request from GHSA-x345-32rc-8h85 * tests for push rule pattern matching * tests for acl pattern matching * factor out common `re.escape` * Factor out common re.compile * Factor out common anchoring code * add word_boundary support to `glob_to_regex` * Use `glob_to_regex` in push rule evaluator NB that this drops support for character classes. I don't think anyone ever used them. * Improve efficiency of globs with multiple wildcards The idea here is that we compress multiple `*` globs into a single `.*`. We also need to consider `?`, since `*?*` is as hard to implement efficiently as `**`. * add assertion on regex pattern * Fix mypy * Simplify glob_to_regex * Inline the glob_to_regex helper function Signed-off-by: Dan Callahan * Moar comments Signed-off-by: Dan Callahan Co-authored-by: Dan Callahan --- synapse/config/tls.py | 4 +-- synapse/push/push_rule_evaluator.py | 55 ++------------------------------- synapse/util/__init__.py | 61 ++++++++++++++++++++++++++++--------- 3 files changed, 52 insertions(+), 68 deletions(-) (limited to 'synapse') diff --git a/synapse/config/tls.py b/synapse/config/tls.py index b041869758..7df4e4c3e6 100644 --- a/synapse/config/tls.py +++ b/synapse/config/tls.py @@ -17,7 +17,7 @@ import os import warnings from datetime import datetime from hashlib import sha256 -from typing import List, Optional +from typing import List, Optional, Pattern from unpaddedbase64 import encode_base64 @@ -124,7 +124,7 @@ class TlsConfig(Config): fed_whitelist_entries = [] # Support globs (*) in whitelist values - self.federation_certificate_verification_whitelist = [] # type: List[str] + self.federation_certificate_verification_whitelist = [] # type: List[Pattern] for entry in fed_whitelist_entries: try: entry_regex = glob_to_regex(entry.encode("ascii").decode("ascii")) diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py index 49ecb38522..98b90a4f51 100644 --- a/synapse/push/push_rule_evaluator.py +++ b/synapse/push/push_rule_evaluator.py @@ -19,6 +19,7 @@ from typing import Any, Dict, List, Optional, Pattern, Tuple, Union from synapse.events import EventBase from synapse.types import UserID +from synapse.util import glob_to_regex, re_word_boundary from synapse.util.caches.lrucache import LruCache logger = logging.getLogger(__name__) @@ -183,7 +184,7 @@ class PushRuleEvaluatorForEvent: r = regex_cache.get((display_name, False, True), None) if not r: r1 = re.escape(display_name) - r1 = _re_word_boundary(r1) + r1 = re_word_boundary(r1) r = re.compile(r1, flags=re.IGNORECASE) regex_cache[(display_name, False, True)] = r @@ -212,7 +213,7 @@ def _glob_matches(glob: str, value: str, word_boundary: bool = False) -> bool: try: r = regex_cache.get((glob, True, word_boundary), None) if not r: - r = _glob_to_re(glob, word_boundary) + r = glob_to_regex(glob, word_boundary) regex_cache[(glob, True, word_boundary)] = r return bool(r.search(value)) except re.error: @@ -220,56 +221,6 @@ def _glob_matches(glob: str, value: str, word_boundary: bool = False) -> bool: return False -def _glob_to_re(glob: str, word_boundary: bool) -> Pattern: - """Generates regex for a given glob. - - Args: - glob - word_boundary: Whether to match against word boundaries or entire string. - """ - if IS_GLOB.search(glob): - r = re.escape(glob) - - r = r.replace(r"\*", ".*?") - r = r.replace(r"\?", ".") - - # handle [abc], [a-z] and [!a-z] style ranges. - r = GLOB_REGEX.sub( - lambda x: ( - "[%s%s]" % (x.group(1) and "^" or "", x.group(2).replace(r"\\\-", "-")) - ), - r, - ) - if word_boundary: - r = _re_word_boundary(r) - - return re.compile(r, flags=re.IGNORECASE) - else: - r = "^" + r + "$" - - return re.compile(r, flags=re.IGNORECASE) - elif word_boundary: - r = re.escape(glob) - r = _re_word_boundary(r) - - return re.compile(r, flags=re.IGNORECASE) - else: - r = "^" + re.escape(glob) + "$" - return re.compile(r, flags=re.IGNORECASE) - - -def _re_word_boundary(r: str) -> str: - """ - Adds word boundary characters to the start and end of an - expression to require that the match occur as a whole word, - but do so respecting the fact that strings starting or ending - with non-word characters will change word boundaries. - """ - # we can't use \b as it chokes on unicode. however \W seems to be okay - # as shorthand for [^0-9A-Za-z_]. - return r"(^|\W)%s(\W|$)" % (r,) - - def _flatten_dict( d: Union[EventBase, dict], prefix: Optional[List[str]] = None, diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py index 0f84fa3f4e..b69f562ca5 100644 --- a/synapse/util/__init__.py +++ b/synapse/util/__init__.py @@ -15,6 +15,7 @@ import json import logging import re +from typing import Pattern import attr from frozendict import frozendict @@ -26,6 +27,9 @@ from synapse.logging import context logger = logging.getLogger(__name__) +_WILDCARD_RUN = re.compile(r"([\?\*]+)") + + def _reject_invalid_json(val): """Do not allow Infinity, -Infinity, or NaN values in JSON.""" raise ValueError("Invalid JSON value: '%s'" % val) @@ -158,25 +162,54 @@ def log_failure(failure, msg, consumeErrors=True): return failure -def glob_to_regex(glob): +def glob_to_regex(glob: str, word_boundary: bool = False) -> Pattern: """Converts a glob to a compiled regex object. - The regex is anchored at the beginning and end of the string. - Args: - glob (str) + glob: pattern to match + word_boundary: If True, the pattern will be allowed to match at word boundaries + anywhere in the string. Otherwise, the pattern is anchored at the start and + end of the string. Returns: - re.RegexObject + compiled regex pattern """ - res = "" - for c in glob: - if c == "*": - res = res + ".*" - elif c == "?": - res = res + "." + + # Patterns with wildcards must be simplified to avoid performance cliffs + # - The glob `?**?**?` is equivalent to the glob `???*` + # - The glob `???*` is equivalent to the regex `.{3,}` + chunks = [] + for chunk in _WILDCARD_RUN.split(glob): + # No wildcards? re.escape() + if not _WILDCARD_RUN.match(chunk): + chunks.append(re.escape(chunk)) + continue + + # Wildcards? Simplify. + qmarks = chunk.count("?") + if "*" in chunk: + chunks.append(".{%d,}" % qmarks) else: - res = res + re.escape(c) + chunks.append(".{%d}" % qmarks) + + res = "".join(chunks) - # \A anchors at start of string, \Z at end of string - return re.compile(r"\A" + res + r"\Z", re.IGNORECASE) + if word_boundary: + res = re_word_boundary(res) + else: + # \A anchors at start of string, \Z at end of string + res = r"\A" + res + r"\Z" + + return re.compile(res, re.IGNORECASE) + + +def re_word_boundary(r: str) -> str: + """ + Adds word boundary characters to the start and end of an + expression to require that the match occur as a whole word, + but do so respecting the fact that strings starting or ending + with non-word characters will change word boundaries. + """ + # we can't use \b as it chokes on unicode. however \W seems to be okay + # as shorthand for [^0-9A-Za-z_]. + return r"(^|\W)%s(\W|$)" % (r,) -- cgit 1.4.1