From 8b8004a9626442ae31e4dffd79e874e9cde050c6 Mon Sep 17 00:00:00 2001 From: ThibG Date: Thu, 19 Nov 2020 19:52:06 +0100 Subject: [PATCH] Fix webfinger redirect handling in ResolveAccountService (#15187) * Fix webfinger redirect handling in ResolveAccountService ResolveAccountService#process_webfinger! handled a one-step webfinger redirection, but only accepting the result if it matched the exact URI passed as input, defeating the point of a redirection check. Instead, use the same logic as in `ActivityPub::FetchRemoteAccountService`, updating the resulting `acct:` URI with the result of the first webfinger query. * Add tests --- app/services/resolve_account_service.rb | 23 +++++--- spec/services/resolve_account_service_spec.rb | 52 ++++++++++++++++--- 2 files changed, 60 insertions(+), 15 deletions(-) diff --git a/app/services/resolve_account_service.rb b/app/services/resolve_account_service.rb index c5291fa67..74b0b82d0 100644 --- a/app/services/resolve_account_service.rb +++ b/app/services/resolve_account_service.rb @@ -29,6 +29,7 @@ class ResolveAccountService < BaseService # At this point we are in need of a Webfinger query, which may # yield us a different username/domain through a redirect process_webfinger!(@uri) + @domain = nil if TagManager.instance.local_domain?(@domain) # Because the username/domain pair may be different than what # we already checked, we need to check if we've already got @@ -78,25 +79,31 @@ class ResolveAccountService < BaseService @uri = [@username, @domain].compact.join('@') end - def process_webfinger!(uri, redirected = false) + def process_webfinger!(uri) @webfinger = webfinger!("acct:#{uri}") - confirmed_username, confirmed_domain = @webfinger.subject.gsub(/\Aacct:/, '').split('@') + confirmed_username, confirmed_domain = split_acct(@webfinger.subject) if confirmed_username.casecmp(@username).zero? && confirmed_domain.casecmp(@domain).zero? @username = confirmed_username @domain = confirmed_domain - @uri = uri - elsif !redirected - return process_webfinger!("#{confirmed_username}@#{confirmed_domain}", true) - else - raise Webfinger::RedirectError, "The URI #{uri} tries to hijack #{@username}@#{@domain}" + return end - @domain = nil if TagManager.instance.local_domain?(@domain) + # Account doesn't match, so it may have been redirected + @webfinger = webfinger!("acct:#{confirmed_username}@#{confirmed_domain}") + @username, @domain = split_acct(@webfinger.subject) + + unless confirmed_username.casecmp(@username).zero? && confirmed_domain.casecmp(@domain).zero? + raise Webfinger::RedirectError, "The URI #{uri} tries to hijack #{@username}@#{@domain}" + end rescue Webfinger::GoneError @gone = true end + def split_acct(acct) + acct.gsub(/\Aacct:/, '').split('@') + end + def process_account! return unless activitypub_ready? diff --git a/spec/services/resolve_account_service_spec.rb b/spec/services/resolve_account_service_spec.rb index 76cb9ed8d..5bd0ec264 100644 --- a/spec/services/resolve_account_service_spec.rb +++ b/spec/services/resolve_account_service_spec.rb @@ -4,11 +4,8 @@ RSpec.describe ResolveAccountService, type: :service do subject { described_class.new } 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/avatar/7477-300-20160211190340.png").to_return(request_fixture('avatar.txt')) - stub_request(:get, "https://quitter.no/.well-known/webfinger?resource=acct:catsrgr8@quitter.no").to_return(status: 404) stub_request(:get, "https://ap.example.com/.well-known/webfinger?resource=acct:foo@ap.example.com").to_return(request_fixture('activitypub-webfinger.txt')) stub_request(:get, "https://ap.example.com/users/foo").to_return(request_fixture('activitypub-actor.txt')) stub_request(:get, "https://ap.example.com/users/foo.atom").to_return(request_fixture('activitypub-feed.txt')) @@ -16,12 +13,25 @@ RSpec.describe ResolveAccountService, type: :service do stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:hoge@example.com').to_return(status: 410) end - it 'returns nil if no such user can be resolved via webfinger' do - expect(subject.call('catsrgr8@quitter.no')).to be_nil + context 'when there is an LRDD endpoint but no resolvable account' do + before do + stub_request(:get, "https://quitter.no/.well-known/host-meta").to_return(request_fixture('.host-meta.txt')) + stub_request(:get, "https://quitter.no/.well-known/webfinger?resource=acct:catsrgr8@quitter.no").to_return(status: 404) + end + + it 'returns nil' do + expect(subject.call('catsrgr8@quitter.no')).to be_nil + end end - it 'returns nil if the domain does not have webfinger' do - expect(subject.call('catsrgr8@example.com')).to be_nil + context 'when there is no LRDD endpoint nor resolvable account' do + before do + stub_request(:get, "https://example.com/.well-known/webfinger?resource=acct:catsrgr8@example.com").to_return(status: 404) + end + + it 'returns nil' do + expect(subject.call('catsrgr8@example.com')).to be_nil + end end context 'when webfinger returns http gone' do @@ -48,6 +58,34 @@ RSpec.describe ResolveAccountService, type: :service do end end + context 'with a legitimate webfinger redirection' do + before do + webfinger = { subject: 'acct:foo@ap.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo' }] } + stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' }) + end + + it 'returns new remote account' do + account = subject.call('Foo@redirected.example.com') + + expect(account.activitypub?).to eq true + expect(account.acct).to eq 'foo@ap.example.com' + expect(account.inbox_url).to eq 'https://ap.example.com/users/foo/inbox' + end + end + + context 'with too many webfinger redirections' do + before do + webfinger = { subject: 'acct:foo@evil.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo' }] } + stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' }) + webfinger2 = { subject: 'acct:foo@ap.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo' }] } + stub_request(:get, 'https://evil.example.com/.well-known/webfinger?resource=acct:foo@evil.example.com').to_return(body: Oj.dump(webfinger2), headers: { 'Content-Type': 'application/jrd+json' }) + end + + it 'returns new remote account' do + expect { subject.call('Foo@redirected.example.com') }.to raise_error Webfinger::RedirectError + end + end + context 'with an ActivityPub account' do it 'returns new remote account' do account = subject.call('foo@ap.example.com')