Since we now remember the final location redirects lead to
and use it for all further checks since
3e134b07fa, these redirects
can no longer be exploited to serve counterfeit objects.
This fixes:
- display URLs from independent webapp clients
redirecting to the canonical domain
- Peertube display URLs for remote content
(acting like the above)
As hinted at in the commit message when strict checking
was added in 8684964c5d,
refetching is more robust than display URL comparison
but in exchange is harder to implement correctly.
A similar refetch approach is also employed by
e.g. Mastodon, IceShrimp and FireFish.
To make sure no checks can be bypassed by forcing
a refetch, id checking is placed at the very end.
This will fix:
- Peertube display URL arrays our transmogrifier fails to normalise
- non-canonical display URLs from alternative frontends
(theoretical; we didnt’t get any actual reports about this)
It will also be helpful in the planned key handling overhaul.
The modified user collision test was introduced in
https://git.pleroma.social/pleroma/pleroma/-/merge_requests/461
and unfortunately the issues this fixes aren’t public.
Afaict it was just meant to guard against someone serving
faked data belonging to an unrelated domain. Since we now
refetch and the id actually is mocked, lookup now succeeds
but will use the real data from the authorative server
making it unproblematic. Instead modify the fake data further
and make sure we don’t end up using the spoofed version.
Usually an id should point to another AP object
and the image file isn’t an AP object. We currently
do not provide standalone AP objects for emoji and
don't keep track of remote emoji at all.
Thus just federate them as anonymous objects,
i.e. objects only existing within a parent context
and using an explicit null id.
IceShrimp.NET previously adopted anonymous objects
for remote emoji without any apparent issues. See:
333611f65e
Fixes: AkkomaGang/akkoma#694
We’ve received reports of some specific instances slowly accumulating
more and more binary data over time up to OOMs and globally setting
ERL_FULLSWEEP_AFTER=0 has proven to be an effective countermeasure.
However, this incurs increased cpu perf costs everywhere and is
thus not suitable to apply out of the box.
Apparently long-lived Phoenix websocket processes are known to
often cause exactly this by getting into a state unfavourable
for the garbage collector.
Therefore it seems likely affected instances are using timeline
streaming and do so in just the right way to trigger this. We
can tune the garbage collector just for websocket processes
and use a more lenient value of 20 to keep the added perf cost
in check.
Testing on one affected instance appears to confirm this theory
Ref.:
https://www.erlang.org/doc/man/erlang#ghlink-process_flag-2-idp226https://blog.guzman.codes/using-phoenix-channels-high-memory-usage-save-money-with-erlfullsweepafterhttps://git.pleroma.social/pleroma/pleroma/-/merge_requests/4060
Tested-by: bjo
Ever since 364b6969eb
this setting wasn't used by the backend and a noop.
The stated usecase is better served by setting the base_url
to a local subdomain and using proxying in nginx/Caddy/...
