Fixes #3186 - Endpoint api/v1/ticket_articles/by_ticket ignores X-On-Behalf-Of

app/controllers/application_controller/authorizes.rb

@@ -22,39 +22,6 @@ module ApplicationController::Authorizes
     [:controllers, self]
   end
 
-  # We need a special UserContext when authorizing in controller context
-  # because of Token authentication which has it's own permissions
-  # See: https://github.com/varvet/pundit#additional-context
-  # We use a Delegator here to have transparent / DuckType access
-  # to the underlying User instance in the Policy
-  class UserContext < Delegator
-
-    def initialize(user, token)
-      @user  = user
-      @token = token
-    end
-
-    def __getobj__
-      @user
-    end
-
-    def permissions!(permissions)
-      raise Exceptions::NotAuthorized, 'authentication failed' if !@user
-      raise Exceptions::NotAuthorized, 'Not authorized (user)!' if !@user.permissions?(permissions)
-      return if !@token
-      return if @token.permissions?(permissions)
-
-      raise Exceptions::NotAuthorized, 'Not authorized (token)!'
-    end
-
-    def permissions?(permissions)
-      permissions!(permissions)
-      true
-    rescue Exceptions::NotAuthorized
-      false
-    end
-  end
-
   def pundit_user
     @pundit_user ||= UserContext.new(current_user, @_token)
   end

app/models/token.rb

@@ -109,11 +109,22 @@ cleanup old token
   end
 
   def permissions?(names)
-    return false if !user.permissions?(names)
+    return false if !effective_user.permissions?(names)
 
     super(names)
   end
 
+  # allows to evaluate token permissions in context of given user instead of owner
+  # @param [User] user to use as context for the given block
+  # @param block to evaluate in given context
+  def with_context(user:, &block)
+    @effective_user = user
+
+    instance_eval(&block) if block_given?
+  ensure
+    @effective_user = nil
+  end
+
   private
 
   def generate_token
@@ -123,4 +134,9 @@ cleanup old token
     end
     true
   end
+
+  # token owner or user set by #with_context
+  def effective_user
+    @effective_user || user
+  end
 end

lib/user_context.rb

@@ -0,0 +1,32 @@
+# We need a special UserContext when authorizing in controller context
+# because of Token authentication which has it's own permissions
+# See: https://github.com/varvet/pundit#additional-context
+# We use a Delegator here to have transparent / DuckType access
+# to the underlying User instance in the Policy
+class UserContext < Delegator
+
+  def initialize(user, token)
+    @user  = user
+    @token = token
+  end
+
+  def __getobj__
+    @user
+  end
+
+  def permissions!(permissions)
+    raise Exceptions::NotAuthorized, 'authentication failed' if !@user
+    raise Exceptions::NotAuthorized, 'Not authorized (user)!' if !@user.permissions?(permissions)
+    return if !@token
+    return if @token.with_context(user: @user) { permissions?(permissions) }
+
+    raise Exceptions::NotAuthorized, 'Not authorized (token)!'
+  end
+
+  def permissions?(permissions)
+    permissions!(permissions)
+    true
+  rescue Exceptions::NotAuthorized
+    false
+  end
+end

spec/factories/role.rb

@@ -7,5 +7,9 @@ FactoryBot.define do
     factory :agent_role do
       permissions { Permission.where(name: 'ticket.agent') }
     end
+
+    trait :admin do
+      permissions { Permission.where(name: 'admin') }
+    end
   end
 end

spec/lib/user_context_spec.rb

@@ -0,0 +1,25 @@
+require 'rails_helper'
+
+RSpec.describe UserContext do
+  subject(:user_context) { described_class.new(user, token) }
+
+  describe '#permissions?' do
+    context 'when user with ticket.agent permission' do
+      let(:user)  { create(:user, roles: [create(:agent_role)]) }
+      let(:token) { nil }
+
+      it { is_expected.to be_permissions('ticket.agent') }
+      it { is_expected.not_to be_permissions('admin') }
+    end
+
+    # https://github.com/zammad/zammad/issues/3186
+    context 'when user with ticket.agent permission and token created by user who doesn\'t' do
+      let(:user)        { create(:user, roles: [create(:agent_role)]) }
+      let(:token_owner) { create(:user, roles: [create(:role, :admin)]) }
+      let(:token)       { create(:token, user: token_owner, preferences: { permission: %w[ticket.agent] }) }
+
+      it { is_expected.to be_permissions('ticket.agent') }
+      it { is_expected.not_to be_permissions('admin') }
+    end
+  end
+end