Improve shared status verification (#2525)

* Instead of parsing shared status contents verbatim, make roundtrip
to purported original URL. Confirm that the "original" URL is from the
same domain as the author it claims to be from.

* Fix obvious typo, add comment

* Use URI look-up first

* Add test, update Goldfinger dependency to make less useless HTTP requests per Webfinger lookup
This commit is contained in:
Eugen Rochko 2017-04-27 17:06:47 +02:00 committed by GitHub
parent b8e7eee837
commit 2af4f3c4e2
5 changed files with 127 additions and 42 deletions

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@ -165,7 +165,7 @@ GEM
ruby-progressbar (~> 1.4)
globalid (0.3.7)
activesupport (>= 4.1.0)
goldfinger (1.1.2)
goldfinger (1.2.0)
addressable (~> 2.4)
http (~> 2.0)
nokogiri (~> 1.6)
@ -459,7 +459,7 @@ GEM
execjs (>= 0.3.0, < 3)
unf (0.1.4)
unf_ext
unf_ext (0.0.7.3)
unf_ext (0.0.7.4)
unicode-display_width (1.1.3)
uniform_notifier (1.10.0)
warden (1.2.7)

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@ -39,9 +39,19 @@ class FetchRemoteStatusService < BaseService
Rails.logger.debug "Going to webfinger #{username}@#{domain}"
return FollowRemoteAccountService.new.call("#{username}@#{domain}")
account = FollowRemoteAccountService.new.call("#{username}@#{domain}")
# If the author's confirmed URLs do not match the domain of the URL
# we are reading this from, abort
return nil unless confirmed_domain?(domain, account)
account
rescue Nokogiri::XML::XPath::SyntaxError
Rails.logger.debug 'Invalid XML or missing namespace'
nil
end
def confirmed_domain?(domain, account)
domain.casecmp(account.domain).zero? || domain.casecmp(Addressable::URI.parse(account.remote_url).normalize.host).zero?
end
end

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@ -47,7 +47,7 @@ class ProcessFeedService < BaseService
return status unless just_created
if verb == :share
original_status, = status_from_xml(@xml.at_xpath('.//activity:object', activity: TagManager::AS_XMLNS))
original_status = shared_status_from_xml(@xml.at_xpath('.//activity:object', activity: TagManager::AS_XMLNS))
status.reblog = original_status
if original_status.nil?
@ -90,6 +90,14 @@ class ProcessFeedService < BaseService
!([:post, :share, :delete].include?(verb) && [:activity, :note, :comment].include?(type))
end
def shared_status_from_xml(entry)
status = find_status(id(entry))
return status unless status.nil?
FetchRemoteStatusService.new.call(url(entry))
end
def status_from_xml(entry)
# Return early if status already exists in db
status = find_status(id(entry))

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@ -5,6 +5,7 @@ RSpec.describe FollowRemoteAccountService do
before do
stub_request(:get, "https://quitter.no/.well-known/host-meta").to_return(request_fixture('.host-meta.txt'))
stub_request(:get, "https://example.com/.well-known/webfinger?resource=acct:catsrgr8@example.com").to_return(status: 404)
stub_request(:get, "https://example.com/.well-known/host-meta").to_return(status: 404)
stub_request(:get, "https://quitter.no/.well-known/webfinger?resource=acct:gargron@quitter.no").to_return(request_fixture('webfinger.txt'))
stub_request(:get, "https://quitter.no/.well-known/webfinger?resource=acct:catsrgr8@quitter.no").to_return(status: 404)

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@ -1,11 +1,12 @@
require 'rails_helper'
RSpec.describe ProcessFeedService do
subject { ProcessFeedService.new }
describe 'processing a feed' do
let(:body) { File.read(File.join(Rails.root, 'spec', 'fixtures', 'xml', 'mastodon.atom')) }
let(:account) { Fabricate(:account, username: 'localhost', domain: 'kickass.zone') }
subject { ProcessFeedService.new }
before do
stub_request(:post, "https://pubsubhubbub.superfeedr.com/").to_return(:status => 200, :body => "", :headers => {})
stub_request(:get, "http://kickass.zone/system/accounts/avatars/000/000/001/large/eris.png").to_return(request_fixture('avatar.txt'))
@ -50,3 +51,68 @@ RSpec.describe ProcessFeedService do
expect(status.media_attachments.first).to have_attached_file(:file)
end
end
it 'does not accept tampered reblogs' do
good_actor = Fabricate(:account, username: 'tracer', domain: 'overwatch.com')
real_body = <<XML
<?xml version="1.0"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:thr="http://purl.org/syndication/thread/1.0" xmlns:activity="http://activitystrea.ms/spec/1.0/" xmlns:poco="http://portablecontacts.net/spec/1.0" xmlns:media="http://purl.org/syndication/atommedia" xmlns:ostatus="http://ostatus.org/schema/1.0" xmlns:mastodon="http://mastodon.social/schema/1.0">
<id>tag:overwatch.com,2017-04-27:objectId=4467137:objectType=Status</id>
<published>2017-04-27T13:49:25Z</published>
<updated>2017-04-27T13:49:25Z</updated>
<activity:object-type>http://activitystrea.ms/schema/1.0/note</activity:object-type>
<activity:verb>http://activitystrea.ms/schema/1.0/post</activity:verb>
<author>
<id>https://overwatch.com/users/tracer</id>
<activity:object-type>http://activitystrea.ms/schema/1.0/person</activity:object-type>
<uri>https://overwatch.com/users/tracer</uri>
<name>tracer</name>
</author>
<content type="html">Overwatch rocks</content>
</entry>
XML
stub_request(:head, 'https://overwatch.com/users/tracer/updates/1').to_return(status: 200, headers: { 'Content-Type' => 'application/atom+xml' })
stub_request(:get, 'https://overwatch.com/users/tracer/updates/1').to_return(status: 200, body: real_body)
bad_actor = Fabricate(:account, username: 'sombra', domain: 'talon.xyz')
body = <<XML
<?xml version="1.0"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:thr="http://purl.org/syndication/thread/1.0" xmlns:activity="http://activitystrea.ms/spec/1.0/" xmlns:poco="http://portablecontacts.net/spec/1.0" xmlns:media="http://purl.org/syndication/atommedia" xmlns:ostatus="http://ostatus.org/schema/1.0" xmlns:mastodon="http://mastodon.social/schema/1.0">
<id>tag:talon.xyz,2017-04-27:objectId=4467137:objectType=Status</id>
<published>2017-04-27T13:49:25Z</published>
<updated>2017-04-27T13:49:25Z</updated>
<author>
<id>https://talon.xyz/users/sombra</id>
<activity:object-type>http://activitystrea.ms/schema/1.0/person</activity:object-type>
<uri>https://talon.xyz/users/sombra</uri>
<name>sombra</name>
</author>
<activity:object-type>http://activitystrea.ms/schema/1.0/activity</activity:object-type>
<activity:verb>http://activitystrea.ms/schema/1.0/share</activity:verb>
<content type="html">Overwatch SUCKS AHAHA</content>
<activity:object>
<id>tag:overwatch.com,2017-04-27:objectId=4467137:objectType=Status</id>
<activity:object-type>http://activitystrea.ms/schema/1.0/note</activity:object-type>
<activity:verb>http://activitystrea.ms/schema/1.0/post</activity:verb>
<author>
<id>https://overwatch.com/users/tracer</id>
<activity:object-type>http://activitystrea.ms/schema/1.0/person</activity:object-type>
<uri>https://overwatch.com/users/tracer</uri>
<name>tracer</name>
</author>
<content type="html">Overwatch SUCKS AHAHA</content>
<link rel="alternate" type="text/html" href="https://overwatch.com/users/tracer/updates/1" />
</activity:object>
</entry>
XML
created_statuses = subject.call(body, bad_actor)
expect(created_statuses.first.reblog?).to be true
expect(created_statuses.first.account_id).to eq bad_actor.id
expect(created_statuses.first.reblog.account_id).to eq good_actor.id
expect(created_statuses.first.reblog.text).to eq 'Overwatch rocks'
end
end