Commit graph

22 commits

Author SHA1 Message Date
61ec592d66 Drop obsolete pixelfed workaround
This pixelfed issue was fixed in 2022-12 in
https://github.com/pixelfed/pixelfed/pull/3932

Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk>
2024-03-26 15:11:06 -01:00
8684964c5d Only allow exact id matches
This protects us from falling for obvious spoofs as from the current
upload exploit (unfortunately we can’t reasonably do anything about
spoofs with exact matches as was possible via emoji and proxy).

Such objects being invalid is supported by the spec, sepcifically
sections 3.1 and 3.2: https://www.w3.org/TR/activitypub/#obj-id

Anonymous objects are not relevant here (they can only exists within
parent objects iiuc) and neither is client-to-server or transient objects
(as those cannot be fetched in the first place).
This leaves us with the requirement for `id` to (a) exist and
(b) be a publicly dereferencable URI from the originating server.
This alone does not yet demand strict equivalence, but the spec then
further explains objects ought to be fetchable _via their ID_.
Meaning an object not retrievable via its ID, is invalid.

This reading is supported by the fact, e.g. GoToSocial (recently) and
Mastodon (for 6+ years) do already implement such strict ID checks,
additionally proving this doesn’t cause federation issues in practice.

However, apart from canonical IDs there can also be additional display
URLs. *omas first redirect those to their canonical location, but *keys
and Mastodon directly serve the AP representation without redirects.

Mastodon and GTS deal with this in two different ways,
but both constitute an effective countermeasure:
 - Mastodon:
   Unless it already is a known AP id, two fetches occur.
   The first fetch just reads the `id` property and then refetches from
   the id. The last fetch requires the returned id to exactly match the
   URL the content was fetched from. (This can be optimised by skipping
   the second fetch if it already matches)
   05eda8d193/app/helpers/jsonld_helper.rb (L168)
   63f0979799

 - GTS:
   Only does a single fetch and then checks if _either_ the id
   _or_ url property (which can be an object) match the original fetch
   URL. This relies on implementations always including their display URL
   as "url" if differing from the id. For actors this is true for all
   investigated implementations, for posts only Mastodon includes an
   "url", but it is also the only one with a differing display URL.
   2bafd7daf5 (diff-943bbb02c8ac74ac5dc5d20807e561dcdfaebdc3b62b10730f643a20ac23c24fR222)

Albeit Mastodon’s refetch offers higher compatibility with theoretical
implmentations using either multiple different display URL or not
denoting any of them as "url" at all, for now we chose to adopt a
GTS-like refetch-free approach to avoid additional implementation
concerns wrt to whether redirects should be allowed when fetching a
canonical AP id and potential for accidentally loosening some checks
(e.g. cross-domain refetches) for one of the fetches.
This may be reconsidered in the future.
2024-03-25 14:05:05 -01:00
3e134b07fa fetcher: return final URL after redirects from get_object
Since we reject cross-domain redirects, this doesn’t yet
make a difference, but it’s requried for stricter checking
subsequent commits will introduce.

To make sure (and in case we ever decide to reallow
cross-domain redirects) also use the final location
for containment and reachability checks.
2024-03-25 14:05:05 -01:00
59a142e0b0 Never fetch resource from ourselves
If it’s not already in the database,
it must be counterfeit (or just not exists at all)

Changed test URLs were only ever used from "local: false" users anyway.
2024-03-25 14:05:05 -01:00
fee57eb376 Move actor check into fetch_and_contain_remote_object_from_id
This brings it in line with its name and closes an,
in practice harmless, verification hole.

This was/is the only user of contain_origin making it
safe to change the behaviour on actor-less objects.

Until now refetched objects did not ensure the new actor matches the
domain of the object. We refetch polls occasionally to retrieve
up-to-date vote counts. A malicious AP server could have switched out
the poll after initial posting with a completely different post
attribute to an actor from another server.
While we indeed fell for this spoof before the commit,
it fortunately seems to have had no ill effect in practice,
since the asociated Create activity is not changed. When exposing the
actor via our REST API, we read this info from the activity not the
object.

This at first thought still keeps one avenue for exploit open though:
the updated actor can be from our own domain and a third server be
instructed to fetch the object from us. However this is foiled by an
id mismatch. By necessity of being fetchable and our longstanding
same-domain check, the id must still be from the attacker’s server.
Even the most barebone authenticity check is able to sus this out.
2024-03-25 14:05:05 -01:00
c4cf4d7f0b Reject cross-domain redirects when fetching AP objects
Such redirects on AP queries seem most likely to be a spoofing attempt.
If the object is legit, the id should match the final domain anyway and
users can directly use the canonical URL.

The lack of such a check (and use of the initially queried domain’s
authority instead of the final domain) was enabling the current exploit
to even affect instances which already migrated away from a same-domain
upload/proxy setup in the past, but retained a redirect to not break old
attachments.

(In theory this redirect could, with some effort, have been limited to
 only old files, but common guides employed a catch-all redirect, which
 allows even future uploads to be reachable via an initial query to the
 main domain)

Same-domain redirects are valid and also used by ourselves,
e.g. for redirecting /notice/XXX to /objects/YYY.
2024-03-25 14:05:05 -01:00
baaeffdebc Update spoofed activity test
Turns out we already had a test for activities spoofed via upload due
to an exploit several years. Back then *oma did not verify content-type
at all and doing so was the only adopted countermeasure.
Even the added test sample though suffered from a mismatching id, yet
nobody seems to have thought it a good idea to tighten id checks, huh

Since we will add stricter id checks later, make id and URL match
and also add a testcase for no content type at all. The new section
will be expanded in subsequent commits.
2024-03-25 14:05:05 -01:00
64e233ca20 Tag Mock-tests as "mocked" and run them seperately 2023-08-04 12:50:50 +01:00
98cb255d12 Support elixir1.15
OTP builds to 1.15

Changelog entry

Ensure policies are fully loaded

Fix :warn

use main branch for linkify

Fix warn in tests

Migrations for phoenix 1.17

Revert "Migrations for phoenix 1.17"

This reverts commit 6a3b2f15b74ea5e33150529385215b7a531f3999.

Oban upgrade

Add default empty whitelist

mix format

limit test to amd64

OTP 26 tests for 1.15

use OTP_VERSION tag

baka

just 1.15

Massive deps update

Update locale, deps

Mix format

shell????

multiline???

?

max cases 1

use assert_recieve

don't put_env in async tests

don't async conn/fs tests

mix format

FIx some uploader issues

Fix tests
2023-08-03 17:44:09 +01:00
77e9a52450 allow http AS profile in ld+json header 2022-12-12 19:06:04 +00:00
68894089e8 Do not fetch anything from blocked instances 2022-12-10 00:09:45 +00:00
f5a315f04c Add URL and code to :not_found errors
Ref #355
2022-12-09 20:13:31 +00:00
db60640c5b Fixing up deletes a bit (#327)
Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk>
Reviewed-on: AkkomaGang/akkoma#327
2022-12-01 15:00:53 +00:00
e1e0d5d759 microblogpub federation fixes (#288)
Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk>
Reviewed-on: AkkomaGang/akkoma#288
2022-11-18 11:14:35 +00:00
Haelwenn (lanodan) Monnier
3e0a5851e5 Set instance reachable on fetch 2022-11-15 17:23:47 +00:00
2641dcdd15 Post editing (#202)
Rebased from #103

Co-authored-by: Tusooa Zhu <tusooa@kazv.moe>
Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk>
Reviewed-on: AkkomaGang/akkoma#202
2022-09-06 19:24:02 +00:00
Haelwenn (lanodan) Monnier
6d6bef64bf
fetcher_test: Remove assert on fake Create having an ap_id 2021-04-05 19:19:12 +02:00
Haelwenn (lanodan) Monnier
0b88accae6
fetcher_test: Fix missing mock function 2021-04-05 19:19:12 +02:00
e854c35e65 Convert tests to all use clear_config instead of Pleroma.Config.put 2021-01-26 11:58:43 -06:00
Haelwenn (lanodan) Monnier
c4439c630f
Bump Copyright to 2021
grep -rl '# Copyright © .* Pleroma' * | xargs sed -i 's;Copyright © .* Pleroma .*;Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>;'
2021-01-13 07:49:50 +01:00
rinpatch
6ca709816f Fix object spoofing vulnerability in attachments
Validate the content-type of the response when fetching an object,
according to https://www.w3.org/TR/activitypub/#x3-2-retrieving-objects.

content-type headers had to be added to many mocks in order to support
this, some of this was done with a regex. While I did go over the
resulting files to check I didn't modify anything unrelated, there is a
 possibility I missed something.

Closes pleroma#1948
2020-11-12 15:25:33 +03:00
Alexander Strizhakov
7dffaef479
tests consistency 2020-10-13 16:35:09 +03:00