CAS + SAML authentication feature (#6425)

* Cas authentication feature

* Config

* Remove class_eval + Omniauth initializer

* Codeclimate review

* Codeclimate review 2

* Codeclimate review 3

* Remove uid/email reconciliation

* SAML authentication

* Clean up code

* Improve login form

* Fix code style issues

* Add locales

20 files changed, 365 insertions, 3 deletions

diff --git a/.env.production.sample b/.env.production.sample
index 3f0edd72f..777336de1 100644
--- a/.env.production.sample
+++ b/.env.production.sample
@@ -13,7 +13,7 @@ DB_PORT=5432
 # Federation
 # Note: Changing LOCAL_DOMAIN at a later time will cause unwanted side effects, including breaking all existing federation.
 # LOCAL_DOMAIN should *NOT* contain the protocol part of the domain e.g https://example.com.
-LOCAL_DOMAIN=example.com 
+LOCAL_DOMAIN=example.com
 
 # Changing LOCAL_HTTPS in production is no longer supported. (Mastodon will always serve https:// links)
 
@@ -58,7 +58,7 @@ VAPID_PUBLIC_KEY=
 # E-mail configuration
 # Note: Mailgun and SparkPost (https://sparkpo.st/smtp) each have good free tiers
 # If you want to use an SMTP server without authentication (e.g local Postfix relay)
-# then set SMTP_AUTH_METHOD and SMTP_OPENSSL_VERIFY_MODE to 'none' and 
+# then set SMTP_AUTH_METHOD and SMTP_OPENSSL_VERIFY_MODE to 'none' and
 # *comment* SMTP_LOGIN and SMTP_PASSWORD (leaving them blank is not enough).
 SMTP_SERVER=smtp.mailgun.org
 SMTP_PORT=587
@@ -135,3 +135,43 @@ STREAMING_CLUSTER_NUM=1
 # If you use Docker, you may want to assign UID/GID manually.
 # UID=1000
 # GID=1000
+
+# Optional CAS authentication (cf. omniauth-cas) :
+# CAS_ENABLED=true
+# CAS_URL=https://sso.myserver.com/
+# CAS_HOST=sso.myserver.com/
+# CAS_PORT=443
+# CAS_SSL=true
+# CAS_VALIDATE_URL=
+# CAS_CALLBACK_URL=
+# CAS_LOGOUT_URL=
+# CAS_LOGIN_URL=
+# CAS_UID_FIELD='user'
+# CAS_CA_PATH=
+# CAS_DISABLE_SSL_VERIFICATION=false
+# CAS_UID_KEY='user'
+# CAS_NAME_KEY='name'
+# CAS_EMAIL_KEY='email'
+# CAS_NICKNAME_KEY='nickname'
+# CAS_FIRST_NAME_KEY='firstname'
+# CAS_LAST_NAME_KEY='lastname'
+# CAS_LOCATION_KEY='location'
+# CAS_IMAGE_KEY='image'
+# CAS_PHONE_KEY='phone'
+
+# Optional SAML authentication (cf. omniauth-saml)
+# SAML_ENABLED=true
+# SAML_ACS_URL=
+# SAML_ISSUER=http://localhost:3000/auth/auth/saml/metadata
+# SAML_IDP_SSO_TARGET_URL=https://idp.testshib.org/idp/profile/SAML2/Redirect/SSO
+# SAML_IDP_CERT=
+# SAML_IDP_CERT_FINGERPRINT=
+# SAML_NAME_IDENTIFIER_FORMAT=
+# SAML_CERT=
+# SAML_PRIVATE_KEY=
+# SAML_SECURITY_WANT_ASSERTION_SIGNED=true
+# SAML_SECURITY_WANT_ASSERTION_ENCRYPTED=true
+# SAML_ATTRIBUTES_STATEMENTS_UID="urn:oid:0.9.2342.19200300.100.1.1"
+# SAML_ATTRIBUTES_STATEMENTS_EMAIL="urn:oid:1.3.6.1.4.1.5923.1.1.1.6"
+# SAML_ATTRIBUTES_STATEMENTS_FULL_NAME="urn:oid:2.5.4.42"
+# SAML_UID_ATTRIBUTE="urn:oid:0.9.2342.19200300.100.1.1"
diff --git a/Gemfile b/Gemfile
index f3844aca6..5b6ae707d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -32,6 +32,9 @@ gem 'devise', '~> 4.4'
 gem 'devise-two-factor', '~> 3.0'
 
 gem 'devise_pam_authenticatable2', '~> 8.0'
+gem 'omniauth-cas', '~> 1.1', install_if: -> { ENV['CAS_ENABLED'] == 'true' }
+gem 'omniauth-saml', '~> 1.8', install_if: -> { ENV['SAML_ENABLED'] == 'true' }
+gem 'omniauth', '~> 1.2'
 
 gem 'doorkeeper', '~> 4.2'
 gem 'fast_blank', '~> 1.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7da9bfe39..c357bfbd1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -201,6 +201,7 @@ GEM
     hamster (3.0.0)
       concurrent-ruby (~> 1.0)
     hashdiff (0.3.7)
+    hashie (3.5.7)
     highline (1.7.10)
     hiredis (0.6.1)
     hkdf (0.3.0)
@@ -304,6 +305,16 @@ GEM
       sidekiq (>= 3.5.0)
       statsd-ruby (~> 1.2.0)
     oj (3.3.10)
+    omniauth (1.8.1)
+      hashie (>= 3.4.6, < 3.6.0)
+      rack (>= 1.6.2, < 3)
+    omniauth-cas (1.1.1)
+      addressable (~> 2.3)
+      nokogiri (~> 1.5)
+      omniauth (~> 1.2)
+    omniauth-saml (1.9.0)
+      omniauth (~> 1.3, >= 1.3.2)
+      ruby-saml (~> 1.4, >= 1.4.3)
     orm_adapter (0.5.0)
     ostatus2 (2.0.3)
       addressable (~> 2.5)
@@ -455,6 +466,8 @@ GEM
       unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-oembed (0.12.0)
     ruby-progressbar (1.9.0)
+    ruby-saml (1.6.1)
+      nokogiri (>= 1.5.10)
     rufus-scheduler (3.4.2)
       et-orbi (~> 1.0)
     safe_yaml (1.0.4)
@@ -606,6 +619,9 @@ DEPENDENCIES
   nokogiri (~> 1.8)
   nsa (~> 0.2)
   oj (~> 3.3)
+  omniauth (~> 1.2)
+  omniauth-cas (~> 1.1)
+  omniauth-saml (~> 1.8)
   ostatus2 (~> 2.0)
   ox (~> 2.8)
   paperclip (~> 5.1)
diff --git a/app/controllers/auth/confirmations_controller.rb b/app/controllers/auth/confirmations_controller.rb
index 2fdb281f4..a240425cd 100644
--- a/app/controllers/auth/confirmations_controller.rb
+++ b/app/controllers/auth/confirmations_controller.rb
@@ -2,4 +2,28 @@
 
 class Auth::ConfirmationsController < Devise::ConfirmationsController
   layout 'auth'
+
+  before_action :set_user, only: [:finish_signup]
+
+  # GET/PATCH /users/:id/finish_signup
+  def finish_signup
+    return unless request.patch? && params[:user]
+    if @user.update(user_params)
+      @user.skip_reconfirmation!
+      sign_in(@user, bypass: true)
+      redirect_to root_path, notice: I18n.t('devise.confirmations.send_instructions')
+    else
+      @show_errors = true
+    end
+  end
+
+  private
+
+  def set_user
+    @user = current_user
+  end
+
+  def user_params
+    params.require(:user).permit(:email)
+  end
 end
diff --git a/app/controllers/auth/omniauth_callbacks_controller.rb b/app/controllers/auth/omniauth_callbacks_controller.rb
new file mode 100644
index 000000000..bbf63bed3
--- /dev/null
+++ b/app/controllers/auth/omniauth_callbacks_controller.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+class Auth::OmniauthCallbacksController < Devise::OmniauthCallbacksController
+  skip_before_action :verify_authenticity_token
+
+  def self.provides_callback_for(provider)
+    provider_id = provider.to_s.chomp '_oauth2'
+
+    define_method provider do
+      @user = User.find_for_oauth(request.env['omniauth.auth'], current_user)
+
+      if @user.persisted?
+        sign_in_and_redirect @user, event: :authentication
+        set_flash_message(:notice, :success, kind: provider_id.capitalize) if is_navigational_format?
+      else
+        session["devise.#{provider}_data"] = request.env['omniauth.auth']
+        redirect_to new_user_registration_url
+      end
+    end
+  end
+
+  Devise.omniauth_configs.each_key do |provider|
+    provides_callback_for provider
+  end
+
+  def after_sign_in_path_for(resource)
+    if resource.email_verified?
+      root_path
+    else
+      finish_signup_path
+    end
+  end
+end
diff --git a/app/javascript/styles/mastodon/forms.scss b/app/javascript/styles/mastodon/forms.scss
index 2bef53cff..dec7d2284 100644
--- a/app/javascript/styles/mastodon/forms.scss
+++ b/app/javascript/styles/mastodon/forms.scss
@@ -568,3 +568,21 @@ code {
     margin-bottom: 4px;
   }
 }
+
+.alternative-login {
+  margin-top: 20px;
+  margin-bottom: 20px;
+
+  h4 {
+    font-size: 16px;
+    color: $ui-base-lighter-color;
+    text-align: center;
+    margin-bottom: 20px;
+    border: 0;
+    padding: 0;
+  }
+
+  .button {
+    display: block;
+  }
+}
diff --git a/app/models/concerns/omniauthable.rb b/app/models/concerns/omniauthable.rb
new file mode 100644
index 000000000..a3d55108d
--- /dev/null
+++ b/app/models/concerns/omniauthable.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module Omniauthable
+  extend ActiveSupport::Concern
+
+  TEMP_EMAIL_PREFIX = 'change@me'
+  TEMP_EMAIL_REGEX = /\Achange@me/
+
+  included do
+    def omniauth_providers
+      Devise.omniauth_configs.keys
+    end
+
+    def email_verified?
+      email && email !~ TEMP_EMAIL_REGEX
+    end
+  end
+
+  class_methods do
+    def find_for_oauth(auth, signed_in_resource = nil)
+      # EOLE-SSO Patch
+      auth.uid = (auth.uid[0][:uid] || auth.uid[0][:user]) if auth.uid.is_a? Hashie::Array
+      identity = Identity.find_for_oauth(auth)
+
+      # If a signed_in_resource is provided it always overrides the existing user
+      # to prevent the identity being locked with accidentally created accounts.
+      # Note that this may leave zombie accounts (with no associated identity) which
+      # can be cleaned up at a later date.
+      user = signed_in_resource ? signed_in_resource : identity.user
+      user = create_for_oauth(auth) if user.nil?
+
+      if identity.user.nil?
+        identity.user = user
+        identity.save!
+      end
+
+      user
+    end
+
+    def create_for_oauth(auth)
+      # Check if the user exists with provided email if the provider gives us a
+      # verified email.  If no verified email was provided or the user already
+      # exists, we assign a temporary email and ask the user to verify it on
+      # the next step via Auth::ConfirmationsController.finish_signup
+
+      user = User.new(user_params_from_auth(auth))
+      user.account.avatar_remote_url = auth.info.image if auth.info.image =~ /\A#{URI.regexp(%w(http https))}\z/
+      user.skip_confirmation!
+      user.save!
+      user
+    end
+
+    private
+
+    def user_params_from_auth(auth)
+      email_is_verified = auth.info.email && (auth.info.verified || auth.info.verified_email)
+      email             = auth.info.email if email_is_verified && !User.exists?(email: auth.info.email)
+
+      {
+        email: email ? email : "#{TEMP_EMAIL_PREFIX}-#{auth.uid}-#{auth.provider}.com",
+        password: Devise.friendly_token[0, 20],
+        account_attributes: {
+          username: ensure_unique_username(auth.uid),
+          display_name: [auth.info.first_name, auth.info.last_name].join(' '),
+        },
+      }
+    end
+
+    def ensure_unique_username(starting_username)
+      username = starting_username
+      i        = 0
+
+      while Account.exists?(username: username)
+        i       += 1
+        username = "#{starting_username}_#{i}"
+      end
+
+      username
+    end
+  end
+end
diff --git a/app/models/identity.rb b/app/models/identity.rb
new file mode 100644
index 000000000..a5e0c09ec
--- /dev/null
+++ b/app/models/identity.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: identities
+#
+#  id         :integer          not null, primary key
+#  user_id    :integer
+#  provider   :string           default(""), not null
+#  uid        :string           default(""), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+
+class Identity < ApplicationRecord
+  belongs_to :user, dependent: :destroy
+  validates :uid, presence: true, uniqueness: { scope: :provider }
+  validates :provider, presence: true
+
+  def self.find_for_oauth(auth)
+    find_or_create_by(uid: auth.uid, provider: auth.provider)
+  end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index fa4ebfc71..fba478453 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -39,6 +39,7 @@
 
 class User < ApplicationRecord
   include Settings::Extend
+  include Omniauthable
 
   ACTIVE_DURATION = 14.days
 
@@ -52,6 +53,7 @@ class User < ApplicationRecord
          :confirmable
 
   devise :pam_authenticatable
+  devise :omniauthable
 
   belongs_to :account, inverse_of: :user
   belongs_to :invite, counter_cache: :uses, optional: true
diff --git a/app/views/auth/confirmations/finish_signup.html.haml b/app/views/auth/confirmations/finish_signup.html.haml
new file mode 100644
index 000000000..4b5161d6b
--- /dev/null
+++ b/app/views/auth/confirmations/finish_signup.html.haml
@@ -0,0 +1,14 @@
+- content_for :page_title do
+  = t('auth.confirm_email')
+
+= simple_form_for(current_user, as: 'user', url: finish_signup_path, html: { role: 'form'}) do |f|
+  - if @show_errors && current_user.errors.any?
+    #error_explanation
+      - current_user.errors.full_messages.each do |msg|
+        = msg
+        %br
+
+  = f.input :email
+
+  .actions
+    = f.submit t('auth.confirm_email'), class: 'button'
diff --git a/app/views/auth/sessions/new.html.haml b/app/views/auth/sessions/new.html.haml
index 3edb0d2d4..1c3a0b6b4 100644
--- a/app/views/auth/sessions/new.html.haml
+++ b/app/views/auth/sessions/new.html.haml
@@ -14,4 +14,13 @@
   .actions
     = f.button :button, t('auth.login'), type: :submit
 
+- if devise_mapping.omniauthable? and resource_class.omniauth_providers.any?
+  .simple_form.alternative-login
+    %h4= t('auth.or_log_in_with')
+
+    .actions
+      - resource_class.omniauth_providers.each do |provider|
+        = link_to omniauth_authorize_path(resource_name, provider), class: "button button-#{provider}" do
+          = t("auth.providers.#{provider}", default: provider.to_s.chomp("_oauth2").capitalize)
+
 .form-footer= render 'auth/shared/links'
diff --git a/config/i18n-tasks.yml b/config/i18n-tasks.yml
index 014055804..bcd816d30 100644
--- a/config/i18n-tasks.yml
+++ b/config/i18n-tasks.yml
@@ -46,6 +46,7 @@ ignore_missing:
   - 'terms.body_html'
   - 'application_mailer.salutation'
   - 'errors.500'
+  - 'auth.providers.*'
 
 ignore_unused:
   - 'activemodel.errors.*'
diff --git a/config/initializers/omniauth.rb b/config/initializers/omniauth.rb
new file mode 100644
index 000000000..97f32c0a4
--- /dev/null
+++ b/config/initializers/omniauth.rb
@@ -0,0 +1,59 @@
+Rails.application.config.middleware.use OmniAuth::Builder do
+  # Vanilla omniauth stategies
+end
+
+Devise.setup do |config|
+  # Devise omniauth strategies
+
+  # CAS strategy
+  if ENV['CAS_ENABLED'] == 'true'
+    cas_options = {}
+    cas_options[:url] = ENV['CAS_URL'] if ENV['CAS_URL']
+    cas_options[:host] = ENV['CAS_HOST'] if ENV['CAS_HOST']
+    cas_options[:port] = ENV['CAS_PORT'] if ENV['CAS_PORT']
+    cas_options[:ssl] = ENV['CAS_SSL'] == 'true' if ENV['CAS_SSL']
+    cas_options[:validate_url] = ENV['CAS_VALIDATE_URL'] if ENV['CAS_VALIDATE_URL']
+    cas_options[:callback_url] = ENV['CAS_CALLBACK_URL'] if ENV['CAS_CALLBACK_URL']
+    cas_options[:logout_url] = ENV['CAS_LOGOUT_URL'] if ENV['CAS_LOGOUT_URL']
+    cas_options[:login_url] = ENV['CAS_LOGIN_URL'] if ENV['CAS_LOGIN_URL']
+    cas_options[:uid_field] = ENV['CAS_UID_FIELD'] || 'user' if ENV['CAS_UID_FIELD']
+    cas_options[:ca_path] = ENV['CAS_CA_PATH'] if ENV['CAS_CA_PATH']
+    cas_options[:disable_ssl_verification] = ENV['CAS_DISABLE_SSL_VERIFICATION'] == 'true' if ENV['CAS_DISABLE_SSL_VERIFICATION']
+    cas_options[:uid_key] = ENV['CAS_UID_KEY'] || 'user'
+    cas_options[:name_key] = ENV['CAS_NAME_KEY'] || 'name'
+    cas_options[:email_key] = ENV['CAS_EMAIL_KEY'] || 'email'
+    cas_options[:nickname_key] = ENV['CAS_NICKNAME_KEY'] || 'nickname'
+    cas_options[:first_name_key] = ENV['CAS_FIRST_NAME_KEY'] || 'firstname'
+    cas_options[:last_name_key] = ENV['CAS_LAST_NAME_KEY'] || 'lastname'
+    cas_options[:location_key] = ENV['CAS_LOCATION_KEY'] || 'location'
+    cas_options[:image_key] = ENV['CAS_IMAGE_KEY'] || 'image'
+    cas_options[:phone_key] = ENV['CAS_PHONE_KEY'] || 'phone'
+    config.omniauth :cas, cas_options
+  end
+
+  # SAML strategy
+  if ENV['SAML_ENABLED'] == 'true'
+    saml_options = {}
+    saml_options[:assertion_consumer_service_url] = ENV['SAML_ACS_URL'] if ENV['SAML_ACS_URL']
+    saml_options[:issuer] = ENV['SAML_ISSUER'] if ENV['SAML_ISSUER']
+    saml_options[:idp_sso_target_url] = ENV['SAML_IDP_SSO_TARGET_URL']  if ENV['SAML_IDP_SSO_TARGET_URL']
+    saml_options[:idp_sso_target_url_runtime_params] = ENV['SAML_IDP_SSO_TARGET_PARAMS'] if ENV['SAML_IDP_SSO_TARGET_PARAMS'] # FIXME: Should be parsable Hash
+    saml_options[:idp_cert] = ENV['SAML_IDP_CERT'] if ENV['SAML_IDP_CERT']
+    saml_options[:idp_cert_fingerprint] = ENV['SAML_IDP_CERT_FINGERPRINT'] if ENV['SAML_IDP_CERT_FINGERPRINT']
+    saml_options[:idp_cert_fingerprint_validator] = ENV['SAML_IDP_CERT_FINGERPRINT_VALIDATOR'] if ENV['SAML_IDP_CERT_FINGERPRINT_VALIDATOR'] # FIXME: Should be Lambda { |fingerprint| }
+    saml_options[:name_identifier_format] = ENV['SAML_NAME_IDENTIFIER_FORMAT'] if ENV['SAML_NAME_IDENTIFIER_FORMAT']
+    saml_options[:request_attributes] = {}
+    saml_options[:certificate] = ENV['SAML_CERT'] if ENV['SAML_CERT']
+    saml_options[:private_key] = ENV['SAML_PRIVATE_KEY'] if ENV['SAML_PRIVATE_KEY']
+    saml_options[:security] = {}
+    saml_options[:security][:want_assertions_signed] = ENV['SAML_SECURITY_WANT_ASSERTION_SIGNED'] == 'true'
+    saml_options[:security][:want_assertions_encrypted] = ENV['SAML_SECURITY_WANT_ASSERTION_ENCRYPTED'] == 'true'
+    saml_options[:attribute_statements] = {}
+    saml_options[:attribute_statements][:uid] = [ENV['SAML_ATTRIBUTES_STATEMENTS_UID']] if ENV['SAML_ATTRIBUTES_STATEMENTS_UID']
+    saml_options[:attribute_statements][:email] = [ENV['SAML_ATTRIBUTES_STATEMENTS_EMAIL']] if ENV['SAML_ATTRIBUTES_STATEMENTS_EMAIL']
+    saml_options[:attribute_statements][:full_name] = [ENV['SAML_ATTRIBUTES_STATEMENTS_FULL_NAME']] if ENV['SAML_ATTRIBUTES_STATEMENTS_FULL_NAME']
+    saml_options[:uid_attribute] = ENV['SAML_UID_ATTRIBUTE'] if ENV['SAML_UID_ATTRIBUTE']
+    config.omniauth :saml, saml_options
+  end
+
+end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index cd6138ff2..6805a6e87 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -355,6 +355,7 @@ en:
   auth:
     agreement_html: By signing up you agree to follow <a href="%{rules_path}">the rules of the instance</a> and <a href="%{terms_path}">our terms of service</a>.
     change_password: Security
+    confirm_email: Confirm email
     delete_account: Delete account
     delete_account_html: If you wish to delete your account, you can <a href="%{path}">proceed here</a>. You will be asked for confirmation.
     didnt_get_confirmation: Didn't receive confirmation instructions?
@@ -364,6 +365,10 @@ en:
     logout: Logout
     migrate_account: Move to a different account
     migrate_account_html: If you wish to redirect this account to a different one, you can <a href="%{path}">configure it here</a>.
+    or_log_in_with: Or log in with
+    providers:
+      cas: CAS
+      saml: SAML
     register: Sign up
     resend_confirmation: Resend confirmation instructions
     reset_password: Reset password
diff --git a/config/locales/fr.yml b/config/locales/fr.yml
index 3ad535f28..f0fc07f7a 100644
--- a/config/locales/fr.yml
+++ b/config/locales/fr.yml
@@ -355,6 +355,7 @@ fr:
   auth:
     agreement_html: En vous inscrivant, vous souscrivez <a href="%{rules_path}">aux règles de l’instance</a> et à <a href="%{terms_path}">nos conditions d’utilisation</a>.
     change_password: Sécurité
+    confirm_email: Confirmer mon adresse mail
     delete_account: Supprimer le compte
     delete_account_html: Si vous désirez supprimer votre compte, vous pouvez <a href="%{path}">cliquer ici</a>. Il vous sera demandé de confirmer cette action.
     didnt_get_confirmation: Vous n’avez pas reçu les consignes de confirmation ?
@@ -364,6 +365,7 @@ fr:
     logout: Se déconnecter
     migrate_account: Déplacer vers un compte différent
     migrate_account_html: Si vous voulez rediriger ce compte vers un autre, vous pouvez le <a href="%{path}">configurer ici</a>.
+    or_log_in_with: Ou authentifiez-vous avec
     register: S’inscrire
     resend_confirmation: Envoyer à nouveau les consignes de confirmation
     reset_password: Réinitialiser le mot de passe
diff --git a/config/routes.rb b/config/routes.rb
index 80a2c6d13..34f33fa95 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -24,9 +24,11 @@ Rails.application.routes.draw do
 
   devise_scope :user do
     get '/invite/:invite_code', to: 'auth/registrations#new', as: :public_invite
+    match '/auth/finish_signup' => 'auth/confirmations#finish_signup', via: [:get, :patch], as: :finish_signup
   end
 
   devise_for :users, path: 'auth', controllers: {
+    omniauth_callbacks: 'auth/omniauth_callbacks',
     sessions:           'auth/sessions',
     registrations:      'auth/registrations',
     passwords:          'auth/passwords',
diff --git a/db/migrate/20180204034416_create_identities.rb b/db/migrate/20180204034416_create_identities.rb
new file mode 100644
index 000000000..f6f5da910
--- /dev/null
+++ b/db/migrate/20180204034416_create_identities.rb
@@ -0,0 +1,11 @@
+class CreateIdentities < ActiveRecord::Migration[5.0]
+  def change
+    create_table :identities do |t|
+      t.references :user, foreign_key: { on_delete: :cascade }
+      t.string :provider, null: false, default: ''
+      t.string :uid, null: false, default: ''
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index a411de20f..02e84cbd1 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180109143959) do
+ActiveRecord::Schema.define(version: 20180204034416) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -173,6 +173,15 @@ ActiveRecord::Schema.define(version: 20180109143959) do
     t.index ["account_id", "target_account_id"], name: "index_follows_on_account_id_and_target_account_id", unique: true
   end
 
+  create_table "identities", id: :serial, force: :cascade do |t|
+    t.integer "user_id"
+    t.string "provider", default: "", null: false
+    t.string "uid", default: "", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["user_id"], name: "index_identities_on_user_id"
+  end
+
   create_table "imports", force: :cascade do |t|
     t.integer "type", null: false
     t.boolean "approved", default: false, null: false
@@ -526,6 +535,7 @@ ActiveRecord::Schema.define(version: 20180109143959) do
   add_foreign_key "follow_requests", "accounts", name: "fk_76d644b0e7", on_delete: :cascade
   add_foreign_key "follows", "accounts", column: "target_account_id", name: "fk_745ca29eac", on_delete: :cascade
   add_foreign_key "follows", "accounts", name: "fk_32ed1b5560", on_delete: :cascade
+  add_foreign_key "identities", "users", on_delete: :cascade
   add_foreign_key "imports", "accounts", name: "fk_6db1b6e408", on_delete: :cascade
   add_foreign_key "invites", "users", on_delete: :cascade
   add_foreign_key "list_accounts", "accounts", on_delete: :cascade
diff --git a/spec/fabricators/identity_fabricator.rb b/spec/fabricators/identity_fabricator.rb
new file mode 100644
index 000000000..bc832df9f
--- /dev/null
+++ b/spec/fabricators/identity_fabricator.rb
@@ -0,0 +1,5 @@
+Fabricator(:identity) do
+  user     nil
+  provider "MyString"
+  uid      "MyString"
+end
diff --git a/spec/models/identity_spec.rb b/spec/models/identity_spec.rb
new file mode 100644
index 000000000..53f355410
--- /dev/null
+++ b/spec/models/identity_spec.rb
@@ -0,0 +1,5 @@
+require 'rails_helper'
+
+RSpec.describe Identity, type: :model do
+  pending "add some examples to (or delete) #{__FILE__}"
+end