Help - accessing session data from my model

I have a model that contains data for many users/organizations. I need
to limit the data by organization. I am trying to put this logic in
the model vs the controller since many controllers/actions will be
using that data. When I do that I get the following error:

undefined local variable or method `session' for Itstaff:Class

this is the code for the model:

class Itstaff < ActiveRecord::Base
  belongs_to :location
  has_many :servers
  has_many :consoles
  def self.user
    find(:all, :conditions => ["location_id in
(?)",session[:location_ids]])
  end
end

The same code works fine from the controller.

session[:location_ids] gets initialized by the application controller
during user log in. I tried to add an attr_reader in application
controller but then my application hangs completely. I appreciate your
help.

I have a model that contains data for many users/organizations. I need
to limit the data by organization. I am trying to put this logic in
the model vs the controller since many controllers/actions will be
using that data. When I do that I get the following error:

undefined local variable or method `session' for Itstaff:Class

You can't (session is basically an instance method of your
controller). Models should be completely ignorant of the controller
layer. You should pass down the appropriate value as an argument to
the method defined in the model.

Fred