Fix Clerk SSO auto-admin: fail closed + explicit admin allowlist (BLO-287)

clerk_email_allowed? failed OPEN on an empty CLERK_ALLOWED_EMAIL_DOMAINS
(empty env = anyone could sign in), and both SSO entrypoints
(from_clerk_oidc and the apex-cookie ClerkDeviseBridge) auto-provisioned
every first-time user as ADMIN_ROLE.

- Fail closed: an unset/empty allowlist now matches no one.
- New CLERK_ADMIN_EMAIL_DOMAINS allowlist gates admin provisioning; SSO
  never silently mints an admin.
- Single chokepoint User.provision_clerk_admin used by both SSO paths.
- Add RSpec coverage (none existed).

app/controllers/concerns/clerk_devise_bridge.rb

@@ -47,20 +47,10 @@ module ClerkDeviseBridge
   end
 
   def provision_user_for_clerk(email, clerk_user)
-    account = Account.first
-    return nil unless account
-
     first_name = clerk_user.respond_to?(:first_name) ? clerk_user.first_name : nil
     last_name = clerk_user.respond_to?(:last_name) ? clerk_user.last_name : nil
 
-    User.create!(
-      account: account,
-      email: email,
-      first_name: first_name.presence,
-      last_name: last_name.presence,
-      role: User::ADMIN_ROLE,
-      password: Devise.friendly_token(40)
-    )
+    User.provision_clerk_admin(email: email, first_name: first_name, last_name: last_name)
   rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotUnique => e
     Rails.logger.warn("[clerk-bridge] provision failed for #{email}: #{e.message}")
     User.active.find_by(email: email)

app/models/user.rb

@@ -132,19 +132,37 @@ class User < ApplicationRecord
     return nil if email.blank?
     return nil unless Docuseal.clerk_email_allowed?(email)
 
-    account = Account.first
-    return nil if account.blank?
-
     user = active.find_by(email:)
     return user if user
 
     first, *rest = auth.info.name.to_s.split(' ', 2)
 
+    provision_clerk_admin(
+      email:,
+      first_name: auth.info.first_name.presence || first,
+      last_name: auth.info.last_name.presence || rest.join(' ')
+    )
+  end
+
+  # The single chokepoint for auto-provisioning a Devise user from Clerk SSO,
+  # used by every SSO entrypoint (the OIDC callback and the apex-cookie bridge).
+  # Fails closed: it refuses to create anyone unless their domain is on the
+  # explicit admin allowlist, so SSO can never silently mint an admin. docuseal
+  # has no non-admin console role, so an allowed-but-not-admin email gets no
+  # account rather than an elevated one.
+  def self.provision_clerk_admin(email:, first_name:, last_name:)
+    email = email.to_s.downcase
+    return nil if email.blank?
+    return nil unless Docuseal.clerk_email_admin?(email)
+
+    account = Account.first
+    return nil if account.blank?
+
     create!(
       account:,
       email:,
-      first_name: auth.info.first_name.presence || first,
-      last_name: auth.info.last_name.presence || rest.join(' '),
+      first_name: first_name.presence,
+      last_name: last_name.presence,
       role: ADMIN_ROLE,
       password: Devise.friendly_token(40)
     )

lib/docuseal.rb

@@ -38,11 +38,15 @@ module Docuseal
   CERTS = JSON.parse(ENV.fetch('CERTS', '{}'))
   TIMESERVER_URL = ENV.fetch('TIMESERVER_URL', nil)
 
+  def self.parse_email_domains(env_key)
+    ENV.fetch(env_key, '').split(',').map { |d| d.strip.downcase }.compact_blank.freeze
+  end
+
   CLERK_DISCOVERY_URL = ENV.fetch('CLERK_DISCOVERY_URL', nil)
   CLERK_CLIENT_ID = ENV.fetch('CLERK_CLIENT_ID', nil)
   CLERK_CLIENT_SECRET = ENV.fetch('CLERK_CLIENT_SECRET', nil)
-  CLERK_ALLOWED_EMAIL_DOMAINS = ENV.fetch('CLERK_ALLOWED_EMAIL_DOMAINS', '')
-                                   .split(',').map { |d| d.strip.downcase }.compact_blank.freeze
+  CLERK_ALLOWED_EMAIL_DOMAINS = parse_email_domains('CLERK_ALLOWED_EMAIL_DOMAINS')
+  CLERK_ADMIN_EMAIL_DOMAINS = parse_email_domains('CLERK_ADMIN_EMAIL_DOMAINS')
 
   VERSION_FILE_PATH = Rails.root.join('.version')
   VERSION_FILE2_PATH = Rails.public_path.join('version')
@@ -71,11 +75,24 @@ module Docuseal
     CLERK_DISCOVERY_URL.present? && CLERK_CLIENT_ID.present? && CLERK_CLIENT_SECRET.present?
   end
 
-  def clerk_email_allowed?(email)
-    return true if CLERK_ALLOWED_EMAIL_DOMAINS.empty?
+  # Fail closed: an unset/empty allowlist matches no one rather than everyone.
+  def email_in_domains?(email, allowed_domains)
+    return false if allowed_domains.empty?
 
     domain = email.to_s.split('@').last.to_s.downcase
-    CLERK_ALLOWED_EMAIL_DOMAINS.include?(domain)
+    return false if domain.blank?
+
+    allowed_domains.include?(domain)
+  end
+
+  def clerk_email_allowed?(email)
+    email_in_domains?(email, CLERK_ALLOWED_EMAIL_DOMAINS)
+  end
+
+  # Admin must be granted explicitly via its own allowlist; never inferred from
+  # mere sign-in eligibility.
+  def clerk_email_admin?(email)
+    email_in_domains?(email, CLERK_ADMIN_EMAIL_DOMAINS)
   end
 
   def advanced_formats?

spec/models/user_spec.rb

@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe User do
+  describe '.from_clerk_oidc' do
+    let!(:account) { create(:account) }
+
+    def auth_for(email, name: 'Jane Doe')
+      OmniAuth::AuthHash.new(
+        provider: 'clerk_oidc',
+        info: { email:, name:, first_name: nil, last_name: nil }
+      )
+    end
+
+    before do
+      stub_const('Docuseal::CLERK_ALLOWED_EMAIL_DOMAINS', ['bloombilt.com'])
+      stub_const('Docuseal::CLERK_ADMIN_EMAIL_DOMAINS', ['bloombilt.com'])
+    end
+
+    it 'returns nil for a blank email' do
+      expect(described_class.from_clerk_oidc(auth_for(''))).to be_nil
+    end
+
+    it 'rejects an email whose domain is not on the allowlist' do
+      expect { described_class.from_clerk_oidc(auth_for('intruder@evil.com')) }
+        .not_to change(described_class, :count)
+      expect(described_class.from_clerk_oidc(auth_for('intruder@evil.com'))).to be_nil
+    end
+
+    it 'provisions a first-time admin-allowlisted user as admin' do
+      user = described_class.from_clerk_oidc(auth_for('founder@bloombilt.com'))
+
+      expect(user).to be_persisted
+      expect(user.role).to eq(User::ADMIN_ROLE)
+      expect(user.email).to eq('founder@bloombilt.com')
+    end
+
+    it 'refuses to provision an allowed-but-not-admin user instead of minting an admin' do
+      stub_const('Docuseal::CLERK_ADMIN_EMAIL_DOMAINS', ['admins.bloombilt.com'])
+
+      expect { described_class.from_clerk_oidc(auth_for('staff@bloombilt.com')) }
+        .not_to change(described_class, :count)
+      expect(described_class.from_clerk_oidc(auth_for('staff@bloombilt.com'))).to be_nil
+    end
+
+    it 'returns an existing active user without creating a new one' do
+      existing = create(:user, account:, email: 'founder@bloombilt.com', role: User::ADMIN_ROLE)
+
+      expect { described_class.from_clerk_oidc(auth_for('FOUNDER@bloombilt.com')) }
+        .not_to change(described_class, :count)
+      expect(described_class.from_clerk_oidc(auth_for('FOUNDER@bloombilt.com'))).to eq(existing)
+    end
+  end
+
+  describe '.provision_clerk_admin' do
+    before { stub_const('Docuseal::CLERK_ADMIN_EMAIL_DOMAINS', ['bloombilt.com']) }
+
+    it 'creates an admin for an admin-allowlisted email' do
+      account = create(:account)
+      user = described_class.provision_clerk_admin(
+        email: 'Founder@Bloombilt.com', first_name: 'Founder', last_name: 'One'
+      )
+
+      expect(user).to be_persisted
+      expect(user.role).to eq(User::ADMIN_ROLE)
+      expect(user.email).to eq('founder@bloombilt.com')
+      expect(user.account).to eq(account)
+    end
+
+    it 'refuses to provision an email that is not admin-allowlisted' do
+      create(:account)
+      expect { described_class.provision_clerk_admin(email: 'rando@evil.com', first_name: 'R', last_name: 'O') }
+        .not_to change(described_class, :count)
+    end
+
+    it 'returns nil when no account exists' do
+      expect(described_class.provision_clerk_admin(email: 'founder@bloombilt.com', first_name: 'F', last_name: 'O'))
+        .to be_nil
+    end
+  end
+
+  describe '.clerk_email_allowed? (via Docuseal)' do
+    it 'fails closed when the allowlist is empty' do
+      stub_const('Docuseal::CLERK_ALLOWED_EMAIL_DOMAINS', [])
+      expect(Docuseal.clerk_email_allowed?('anyone@anywhere.com')).to be(false)
+    end
+
+    it 'allows a listed domain and rejects an unlisted one' do
+      stub_const('Docuseal::CLERK_ALLOWED_EMAIL_DOMAINS', ['bloombilt.com'])
+      expect(Docuseal.clerk_email_allowed?('a@bloombilt.com')).to be(true)
+      expect(Docuseal.clerk_email_allowed?('a@evil.com')).to be(false)
+    end
+  end
+
+  describe '.clerk_email_admin? (via Docuseal)' do
+    it 'grants no one when the admin allowlist is empty' do
+      stub_const('Docuseal::CLERK_ADMIN_EMAIL_DOMAINS', [])
+      expect(Docuseal.clerk_email_admin?('founder@bloombilt.com')).to be(false)
+    end
+
+    it 'grants only listed domains' do
+      stub_const('Docuseal::CLERK_ADMIN_EMAIL_DOMAINS', ['bloombilt.com'])
+      expect(Docuseal.clerk_email_admin?('founder@bloombilt.com')).to be(true)
+      expect(Docuseal.clerk_email_admin?('founder@other.com')).to be(false)
+    end
+  end
+end