mirror of
https://git.anonymousland.org/anonymousland/synapse.git
synced 2024-10-01 11:49:51 -04:00
Fix redaction authentication (#5700)
Ensures that redactions are correctly authenticated for recent room versions. There are a few things going on here: * `_fetch_event_rows` is updated to return a dict rather than a list of rows. * Rather than returning multiple copies of an event which was redacted multiple times, it returns the redactions as a list within the dict. * It also returns the actual rejection reason, rather than merely the fact that it was rejected, so that we don't have to query the table again in `_get_event_from_row`. * The redaction handling is factored out of `_get_event_from_row`, and now checks if any of the redactions are valid.
This commit is contained in:
Richard van der Hoff
GitHub
parent
65c5592b8e
commit
375162b3c3
2
changelog.d/5700.bugfix
Normal file
2
changelog.d/5700.bugfix
Normal file
@ -0,0 +1,2 @@
|
||||
Fix some problems with authenticating redactions in recent room versions.
|
||||
|
||||
@ -37,6 +37,7 @@ from synapse.logging.context import (
|
||||
)
|
||||
from synapse.metrics.background_process_metrics import run_as_background_process
|
||||
from synapse.types import get_domain_from_id
|
||||
from synapse.util import batch_iter
|
||||
from synapse.util.metrics import Measure
|
||||
|
||||
from ._base import SQLBaseStore
|
||||
@ -240,27 +241,8 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
# instead.
|
||||
if not allow_rejected and entry.event.type == EventTypes.Redaction:
|
||||
if entry.event.internal_metadata.need_to_check_redaction():
|
||||
# XXX: we need to avoid calling get_event here.
|
||||
#
|
||||
# The problem is that we end up at this point when an event
|
||||
# which has been redacted is pulled out of the database by
|
||||
# _enqueue_events, because _enqueue_events needs to check
|
||||
# the redaction before it can cache the redacted event. So
|
||||
# obviously, calling get_event to get the redacted event out
|
||||
# of the database gives us an infinite loop.
|
||||
#
|
||||
# For now (quick hack to fix during 0.99 release cycle), we
|
||||
# just go and fetch the relevant row from the db, but it
|
||||
# would be nice to think about how we can cache this rather
|
||||
# than hit the db every time we access a redaction event.
|
||||
#
|
||||
# One thought on how to do this:
|
||||
# 1. split get_events_as_list up so that it is divided into
|
||||
# (a) get the rawish event from the db/cache, (b) do the
|
||||
# redaction/rejection filtering
|
||||
# 2. have _get_event_from_row just call the first half of
|
||||
# that
|
||||
|
||||
# XXX: we should probably use _get_events_from_cache_or_db here,
|
||||
# so that we can benefit from caching.
|
||||
orig_sender = yield self._simple_select_one_onecol(
|
||||
table="events",
|
||||
keyvalues={"event_id": entry.event.redacts},
|
||||
@ -410,19 +392,16 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
The fetch requests. Each entry consists of a list of event
|
||||
ids to be fetched, and a deferred to be completed once the
|
||||
events have been fetched.
|
||||
|
||||
"""
|
||||
with Measure(self._clock, "_fetch_event_list"):
|
||||
try:
|
||||
event_id_lists = list(zip(*event_list))[0]
|
||||
event_ids = [item for sublist in event_id_lists for item in sublist]
|
||||
|
||||
rows = self._new_transaction(
|
||||
row_dict = self._new_transaction(
|
||||
conn, "do_fetch", [], [], self._fetch_event_rows, event_ids
|
||||
)
|
||||
|
||||
row_dict = {r["event_id"]: r for r in rows}
|
||||
|
||||
# We only want to resolve deferreds from the main thread
|
||||
def fire(lst, res):
|
||||
for ids, d in lst:
|
||||
@ -480,7 +459,7 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
logger.debug("Loaded %d events (%d rows)", len(events), len(rows))
|
||||
|
||||
if not allow_rejected:
|
||||
rows[:] = [r for r in rows if not r["rejects"]]
|
||||
rows[:] = [r for r in rows if r["rejected_reason"] is None]
|
||||
|
||||
res = yield make_deferred_yieldable(
|
||||
defer.gatherResults(
|
||||
@ -489,8 +468,8 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
self._get_event_from_row,
|
||||
row["internal_metadata"],
|
||||
row["json"],
|
||||
row["redacts"],
|
||||
rejected_reason=row["rejects"],
|
||||
row["redactions"],
|
||||
rejected_reason=row["rejected_reason"],
|
||||
format_version=row["format_version"],
|
||||
)
|
||||
for row in rows
|
||||
@ -501,49 +480,98 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
|
||||
defer.returnValue({e.event.event_id: e for e in res if e})
|
||||
|
||||
def _fetch_event_rows(self, txn, events):
|
||||
rows = []
|
||||
N = 200
|
||||
for i in range(1 + len(events) // N):
|
||||
evs = events[i * N : (i + 1) * N]
|
||||
if not evs:
|
||||
break
|
||||
def _fetch_event_rows(self, txn, event_ids):
|
||||
"""Fetch event rows from the database
|
||||
|
||||
Events which are not found are omitted from the result.
|
||||
|
||||
The returned per-event dicts contain the following keys:
|
||||
|
||||
* event_id (str)
|
||||
|
||||
* json (str): json-encoded event structure
|
||||
|
||||
* internal_metadata (str): json-encoded internal metadata dict
|
||||
|
||||
* format_version (int|None): The format of the event. Hopefully one
|
||||
of EventFormatVersions. 'None' means the event predates
|
||||
EventFormatVersions (so the event is format V1).
|
||||
|
||||
* rejected_reason (str|None): if the event was rejected, the reason
|
||||
why.
|
||||
|
||||
* redactions (List[str]): a list of event-ids which (claim to) redact
|
||||
this event.
|
||||
|
||||
Args:
|
||||
txn (twisted.enterprise.adbapi.Connection):
|
||||
event_ids (Iterable[str]): event IDs to fetch
|
||||
|
||||
Returns:
|
||||
Dict[str, Dict]: a map from event id to event info.
|
||||
"""
|
||||
event_dict = {}
|
||||
for evs in batch_iter(event_ids, 200):
|
||||
sql = (
|
||||
"SELECT "
|
||||
" e.event_id as event_id, "
|
||||
" e.event_id, "
|
||||
" e.internal_metadata,"
|
||||
" e.json,"
|
||||
" e.format_version, "
|
||||
" r.redacts as redacts,"
|
||||
" rej.event_id as rejects "
|
||||
" rej.reason "
|
||||
" FROM event_json as e"
|
||||
" LEFT JOIN rejections as rej USING (event_id)"
|
||||
" LEFT JOIN redactions as r ON e.event_id = r.redacts"
|
||||
" WHERE e.event_id IN (%s)"
|
||||
) % (",".join(["?"] * len(evs)),)
|
||||
|
||||
txn.execute(sql, evs)
|
||||
rows.extend(self.cursor_to_dict(txn))
|
||||
|
||||
return rows
|
||||
for row in txn:
|
||||
event_id = row[0]
|
||||
event_dict[event_id] = {
|
||||
"event_id": event_id,
|
||||
"internal_metadata": row[1],
|
||||
"json": row[2],
|
||||
"format_version": row[3],
|
||||
"rejected_reason": row[4],
|
||||
"redactions": [],
|
||||
}
|
||||
|
||||
# check for redactions
|
||||
redactions_sql = (
|
||||
"SELECT event_id, redacts FROM redactions WHERE redacts IN (%s)"
|
||||
) % (",".join(["?"] * len(evs)),)
|
||||
|
||||
txn.execute(redactions_sql, evs)
|
||||
|
||||
for (redacter, redacted) in txn:
|
||||
d = event_dict.get(redacted)
|
||||
if d:
|
||||
d["redactions"].append(redacter)
|
||||
|
||||
return event_dict
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def _get_event_from_row(
|
||||
self, internal_metadata, js, redacted, format_version, rejected_reason=None
|
||||
self, internal_metadata, js, redactions, format_version, rejected_reason=None
|
||||
):
|
||||
"""Parse an event row which has been read from the database
|
||||
|
||||
Args:
|
||||
internal_metadata (str): json-encoded internal_metadata column
|
||||
js (str): json-encoded event body from event_json
|
||||
redactions (list[str]): a list of the events which claim to have redacted
|
||||
this event, from the redactions table
|
||||
format_version: (str): the 'format_version' column
|
||||
rejected_reason (str|None): the reason this event was rejected, if any
|
||||
|
||||
Returns:
|
||||
_EventCacheEntry
|
||||
"""
|
||||
with Measure(self._clock, "_get_event_from_row"):
|
||||
d = json.loads(js)
|
||||
internal_metadata = json.loads(internal_metadata)
|
||||
|
||||
if rejected_reason:
|
||||
rejected_reason = yield self._simple_select_one_onecol(
|
||||
table="rejections",
|
||||
keyvalues={"event_id": rejected_reason},
|
||||
retcol="reason",
|
||||
desc="_get_event_from_row_rejected_reason",
|
||||
)
|
||||
|
||||
if format_version is None:
|
||||
# This means that we stored the event before we had the concept
|
||||
# of a event format version, so it must be a V1 event.
|
||||
@ -555,41 +583,7 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
rejected_reason=rejected_reason,
|
||||
)
|
||||
|
||||
redacted_event = None
|
||||
if redacted:
|
||||
redacted_event = prune_event(original_ev)
|
||||
|
||||
redaction_id = yield self._simple_select_one_onecol(
|
||||
table="redactions",
|
||||
keyvalues={"redacts": redacted_event.event_id},
|
||||
retcol="event_id",
|
||||
desc="_get_event_from_row_redactions",
|
||||
)
|
||||
|
||||
redacted_event.unsigned["redacted_by"] = redaction_id
|
||||
# Get the redaction event.
|
||||
|
||||
because = yield self.get_event(
|
||||
redaction_id, check_redacted=False, allow_none=True
|
||||
)
|
||||
|
||||
if because:
|
||||
# It's fine to do add the event directly, since get_pdu_json
|
||||
# will serialise this field correctly
|
||||
redacted_event.unsigned["redacted_because"] = because
|
||||
|
||||
# Starting in room version v3, some redactions need to be
|
||||
# rechecked if we didn't have the redacted event at the
|
||||
# time, so we recheck on read instead.
|
||||
if because.internal_metadata.need_to_check_redaction():
|
||||
expected_domain = get_domain_from_id(original_ev.sender)
|
||||
if get_domain_from_id(because.sender) == expected_domain:
|
||||
# This redaction event is allowed. Mark as not needing a
|
||||
# recheck.
|
||||
because.internal_metadata.recheck_redaction = False
|
||||
else:
|
||||
# Senders don't match, so the event isn't actually redacted
|
||||
redacted_event = None
|
||||
redacted_event = yield self._maybe_redact_event_row(original_ev, redactions)
|
||||
|
||||
cache_entry = _EventCacheEntry(
|
||||
event=original_ev, redacted_event=redacted_event
|
||||
@ -599,6 +593,56 @@ class EventsWorkerStore(SQLBaseStore):
|
||||
|
||||
defer.returnValue(cache_entry)
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def _maybe_redact_event_row(self, original_ev, redactions):
|
||||
"""Given an event object and a list of possible redacting event ids,
|
||||
determine whether to honour any of those redactions and if so return a redacted
|
||||
event.
|
||||
|
||||
Args:
|
||||
original_ev (EventBase):
|
||||
redactions (iterable[str]): list of event ids of potential redaction events
|
||||
|
||||
Returns:
|
||||
Deferred[EventBase|None]: if the event should be redacted, a pruned
|
||||
event object. Otherwise, None.
|
||||
"""
|
||||
redaction_map = yield self._get_events_from_cache_or_db(redactions)
|
||||
|
||||
for redaction_id in redactions:
|
||||
redaction_entry = redaction_map.get(redaction_id)
|
||||
if not redaction_entry:
|
||||
# we don't have the redaction event, or the redaction event was not
|
||||
# authorized.
|
||||
continue
|
||||
|
||||
redaction_event = redaction_entry.event
|
||||
|
||||
# Starting in room version v3, some redactions need to be
|
||||
# rechecked if we didn't have the redacted event at the
|
||||
# time, so we recheck on read instead.
|
||||
if redaction_event.internal_metadata.need_to_check_redaction():
|
||||
expected_domain = get_domain_from_id(original_ev.sender)
|
||||
if get_domain_from_id(redaction_event.sender) == expected_domain:
|
||||
# This redaction event is allowed. Mark as not needing a recheck.
|
||||
redaction_event.internal_metadata.recheck_redaction = False
|
||||
else:
|
||||
# Senders don't match, so the event isn't actually redacted
|
||||
continue
|
||||
|
||||
# we found a good redaction event. Redact!
|
||||
redacted_event = prune_event(original_ev)
|
||||
redacted_event.unsigned["redacted_by"] = redaction_id
|
||||
|
||||
# It's fine to add the event directly, since get_pdu_json
|
||||
# will serialise this field correctly
|
||||
redacted_event.unsigned["redacted_because"] = redaction_event
|
||||
|
||||
return redacted_event
|
||||
|
||||
# no valid redaction found for this event
|
||||
return None
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def have_events_in_timeline(self, event_ids):
|
||||
"""Given a list of event ids, check if we have already processed and
|
||||
|
||||
Loading…
Reference in New Issue
Block a user