使用 declarative_authorization 保护敏感属性

Question

使用 declarative_authorization 按角色保护属性的好方法是什么？例如，用户可以编辑他的联系信息，但不能编辑他的角色。

我的第一个倾向是为不同的场景创建多个控制器操作。我很快意识到，随着受保护属性数量的增加，这会变得多么笨拙。为用户角色执行此操作是一回事，但我可以想象多个受保护的属性。添加大量控制器操作和路线感觉不太对。

我的第二个倾向是围绕特定的敏感属性创建权限，然后使用 declarative_authorizations 提供的 View hepers 包装表单元素。然而，模型和控制器方面在我看来有点模糊。建议会很棒。

请建议使用 declarative_authorizations 按角色保护属性的最佳方法。

Answer 1

编辑2011-05-22
从 3.1RC 开始，Rails 中现在也有类似的东西 https:/ /github.com/rails/rails/blob/master/activerecord/test/cases/mass_assignment_security_test.rb 所以我建议现在就走这条路。

原始答案
我只需将之前使用的内容移植到 Rails 3 中。我从未专门使用过声明性授权，但这非常简单明了，您应该能够适应它。

Rails 3 添加了 mass_assignment_authorizer，这使得这一切真正实现简单的。我使用该链接的教程作为基础，并通过类继承并将属性分组为角色，使其更好地适合我的域模型。

在模型中

acts_as_accessible :admin => :all, :moderator => [:is_spam, :is_featured]
attr_accessible :title, :body # :admin, :moderator, and anyone else can set these

在控制器中

post.accessed_by(current_user.roles.collect(&:code)) # or however yours works
post.attributes = params[:post]

lib/active_record/acts_as_accessible.rb

# A way to have different attr_accessible attributes based on a Role
# @see ActsAsAccessible::ActMethods#acts_as_accessible
module ActiveRecord
  module ActsAsAccessible
    module ActMethods
      # In model
      # acts_as_accessible :admin => :all, :moderator => [:is_spam]
      # attr_accessible :title, :body
      #
      # In controller
      # post.accessed_by(current_user.roles.collect(&:code))
      # post.attributes = params[:post]
      #
      # Warning: This frequently wouldn't be the concern of the model where this is declared in,
      # but it is so much more useful to have it in there with the attr_accessible declaration.
      # OHWELL.
      #
      # @param [Hash] roles Hash of { :role => [:attr, :attr] }
      # @see acts_as_accessible_attributes
      def acts_as_accessible(*roles)
        roles_attributes_hash = Hash.new {|h,k| h[k] ||= [] }
        roles_attributes_hash = roles_attributes_hash.merge(roles.extract_options!).symbolize_keys

        if !self.respond_to? :acts_as_accessible_attributes
          attr_accessible
          write_inheritable_attribute :acts_as_accessible_attributes, roles_attributes_hash.symbolize_keys
          class_inheritable_reader    :acts_as_accessible_attributes

          # extend ClassMethods unless (class << self; included_modules; end).include?(ClassMethods)
          include InstanceMethods unless included_modules.include?(InstanceMethods)
        else # subclass
          new_acts_as_accessible_attributes = self.acts_as_accessible_attributes.dup
          roles_attributes_hash.each do |role,attrs|
            new_acts_as_accessible_attributes[role] += attrs
          end
          write_inheritable_attribute :acts_as_accessible_attributes, new_acts_as_accessible_attributes.symbolize_keys
        end
      end
    end

    module InstanceMethods
      # @param [Array, NilClass] roles Array of Roles or nil to reset
      # @return [Array, NilClass]
      def accessed_by(*roles)
        if roles.any?
          case roles.first
          when NilClass
            @accessed_by = nil
          when Array
            @accessed_by = roles.first.flatten.collect(&:to_sym)
          else
            @accessed_by = roles.flatten.flatten.collect(&:to_sym)
          end
        end
        @accessed_by
      end

      private
      # This is what really does the work in attr_accessible/attr_protected.
      # This override adds the acts_as_accessible_attributes for the current accessed_by roles.
      # @see http://asciicasts.com/episodes/237-dynamic-attr-accessible
      def mass_assignment_authorizer
        attrs = []
        if self.accessed_by
          self.accessed_by.each do |role|
            if self.acts_as_accessible_attributes.include? role
              if self.acts_as_accessible_attributes[role] == :all
                return self.class.protected_attributes
              else
                attrs += self.acts_as_accessible_attributes[role]
              end
            end
          end
        end
        super + attrs
      end
    end
  end
end

ActiveRecord::Base.send(:extend, ActiveRecord::ActsAsAccessible::ActMethods)

spec/lib/active_record/acts_as_accessible.rb

require 'spec_helper'

class TestActsAsAccessible
  include ActiveModel::MassAssignmentSecurity
  extend ActiveRecord::ActsAsAccessible::ActMethods
  attr_accessor :foo, :bar, :baz, :qux
  acts_as_accessible :dude => [:bar], :bra => [:baz, :qux], :admin => :all
  attr_accessible :foo
  def attributes=(values)
    sanitize_for_mass_assignment(values).each do |k, v|
      send("#{k}=", v)
    end
  end
end

describe TestActsAsAccessible do
  it "should still allow mass assignment to accessible attributes by default" do
    subject.attributes = {:foo => 'fooo'}
    subject.foo.should == 'fooo'
  end
  it "should not allow mass assignment to non-accessible attributes by default" do
    subject.attributes = {:bar => 'baaar'}
    subject.bar.should be_nil
  end
  it "should allow mass assignment to acts_as_accessible attributes when passed appropriate accessed_by" do
    subject.accessed_by :dude
    subject.attributes = {:bar => 'baaar'}
    subject.bar.should == 'baaar'
  end
  it "should allow mass assignment to multiple acts_as_accessible attributes when passed appropriate accessed_by" do
    subject.accessed_by :bra
    subject.attributes = {:baz => 'baaaz', :qux => 'quuux'}
    subject.baz.should == 'baaaz'
    subject.qux.should == 'quuux'
  end
  it "should allow multiple accessed_by to be specified" do
    subject.accessed_by :dude, :bra
    subject.attributes = {:bar => 'baaar', :baz => 'baaaz', :qux => 'quuux'}
    subject.bar.should == 'baaar'
    subject.baz.should == 'baaaz'
    subject.qux.should == 'quuux'
  end
  it "should allow :all access" do
    subject.accessed_by :admin
    subject.attributes = {:bar => 'baaar', :baz => 'baaaz', :qux => 'quuux'}
    subject.bar.should == 'baaar'
    subject.baz.should == 'baaaz'
    subject.qux.should == 'quuux'
  end
end

Answer 2

对我来说，这个过滤问题应该在控制器级别应用。

您需要在某个地方定义如何决定哪些属性对于给定用户是可写的。

# On the user model
class User < ActiveRecord::Base
  # ...

  # Return a list of symbols representing the accessible attributes
  def self.allowed_params(user)
    if user.admin?
      [:name, :email, :role]
    else
      [:name, email]
    end
  end
end

然后，在应用程序控制器中，您可以定义一个方法来过滤参数。

class ApplicationController < ActionController::Base
  # ...
  protected

  def restrict_params(param, model, user)
    params[param].reject! do |k,v|
      !model.allowed_params(user).include?(k)
    end
  end
  # ...
end

最后，在控制器操作中，您可以使用此过滤器：

class UserController < ActionController::Base
  # ...
  def update
    restrict_params(:user, User, @current_user)
    # and continue as normal
  end
  # ...
end

想法是，您可以在每个模型上定义 allowed_pa​​rams，并让每个模型的控制器使用相同的过滤器方法。您可以通过在应用程序控制器中使用一个方法来保存一些样板文件，该方法可以发出前置过滤器，如下所示：

def self.param_restrictions(param, model)
  before_filter do
    restrict_params(param, model, @current_user) if params[param]
  end
end

# in UserController
param_restrictions :user, User

这些示例旨在说明性而非确定性，我希望它们有助于实现此目的。

Answer 3

我会使用 scoped_attr_accessible ，它看起来正是您正在寻找的。只需在所有模型的请求开始时设置范围即可。

为此，请在 application_controller.rb 中使用 before_filter：

before_filter do |controller|
  ScopedAttrAccessible.current_sanitizer_scope = controller.current_user.role
end

Answer 4

我会避免基于模型中用户访问的每个解决方案，因为它似乎存在潜在危险。我会尝试这种方法：

class User < ActiveRecord::Base

  def update_attributes_as_user(values, user)
    values.each do |attribute, value|
      # Update the attribute if the user is allowed to
      @user.send("#{attribute}=", value) if user.modifiable_attributes.include?(attribute)
    end
    save
  end

  def modifiable_attributes
    admin? ? [:name, :email, :role] : [:name, :email]
  end
end

然后在您的控制器中将更新操作从：

@user.update_attributes(params[:user])

更改为

@user.update_attributes_as_user(params[:user], current_user)

Answer 5

Rails 3.1+ 为此目的提供了一个 +assign_attributes+ 方法 - http://apidock.com/rails/ ActiveRecord/AttributeAssignment/assign_attributes。