Class: Brakeman::CheckMassAssignment

Inherits:
BaseCheck show all
Defined in:
lib/brakeman/checks/check_mass_assignment.rb

Overview

Checks for mass assignments to models.

See guides.rubyonrails.org/security.html#mass-assignment for details

Constant Summary collapse

LITERALS =
Set[:lit, :true, :false, :nil, :string]

Constants inherited from BaseCheck

BaseCheck::CONFIDENCE

Constants included from Util

Util::ALL_PARAMETERS, Util::COOKIES, Util::COOKIES_SEXP, Util::PARAMETERS, Util::PARAMS_SEXP, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, Util::SESSION, Util::SESSION_SEXP

Constants inherited from SexpProcessor

SexpProcessor::VERSION

Instance Attribute Summary

Attributes inherited from BaseCheck

#tracker, #warnings

Attributes inherited from SexpProcessor

#context, #env, #expected

Instance Method Summary collapse

Methods inherited from BaseCheck

#add_result, inherited, #initialize, #process_call, #process_cookies, #process_default, #process_if, #process_params, #process_string_interp

Methods included from Util

#array?, #block?, #call?, #camelize, #contains_class?, #context_for, #cookies?, #false?, #file_by_name, #file_for, #github_url, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #make_call, #node_type?, #number?, #params?, #pluralize, #regexp?, #relative_path, #request_env?, #request_value?, #result?, #set_env_defaults, #sexp?, #string?, #symbol?, #table_to_csv, #template_path_to_name, #true?, #truncate_table, #underscore

Methods included from ProcessorHelper

#class_name, #process_all, #process_all!, #process_call_args, #process_class, #process_module

Methods inherited from SexpProcessor

#error_handler, #in_context, #initialize, #process, #process_dummy, #scope

Constructor Details

This class inherits a constructor from Brakeman::BaseCheck

Instance Method Details

#all_literal_args?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 125

def all_literal_args? exp
  if call? exp
    exp.each_arg do |arg|
      return false unless literal? arg
    end

    true
  else
    exp.all? do |arg|
      literal? arg
    end
  end

end

#check_call(call) ⇒ Object

Want to ignore calls to Model.new that have no arguments


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 103

def check_call call
  process_call_args call

  if call.method == :update
    arg = call.second_arg
  else
    arg = call.first_arg
  end

  if arg.nil? #empty new()
    false
  elsif hash? arg and not include_user_input? arg
    false
  elsif all_literal_args? call
    false
  else
    true
  end
end

#check_mass_assignmentObject


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 45

def check_mass_assignment
  return if mass_assign_disabled?

  Brakeman.debug "Processing possible mass assignment calls"
  find_mass_assign_calls.each do |result|
    process_result result
  end
end

#check_permit!Object

Look for and warn about uses of Parameters#permit! for mass assignment


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 153

def check_permit!
  tracker.find_call(:method => :permit!).each do |result|
    if params? result[:target]
      warn_on_permit! result
    end
  end
end

#find_mass_assign_callsObject


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 17

def find_mass_assign_calls
  return @mass_assign_calls if @mass_assign_calls

  models = []
  tracker.models.each do |name, m|
    if unprotected_model? m
      models << name
    end
  end

  return [] if models.empty?

  Brakeman.debug "Finding possible mass assignment calls on #{models.length} models"
  @mass_assign_calls = tracker.find_call :chained => true, :targets => models, :methods => [:new,
    :attributes=,
    :update_attributes,
    :update_attributes!,
    :create,
    :create!,
    :build,
    :first_or_create,
    :first_or_create!,
    :first_or_initialize!,
    :assign_attributes,
    :update
  ]
end

#literal?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 140

def literal? exp
  if sexp? exp
    if exp.node_type == :hash
      all_literal_args? exp
    else
      LITERALS.include? exp.node_type
    end
  else
    true
  end
end

#process_result(res) ⇒ Object

All results should be Model.new(…) or Model.attributes=() calls


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 55

def process_result res
  call = res[:call]

  check = check_call call

  if check and not call.original_line and not duplicate? res
    add_result res

    model = tracker.models[res[:chain].first]

    attr_protected = (model and model[:options][:attr_protected])

    if attr_protected and tracker.options[:ignore_attr_protected]
      return
    elsif input = include_user_input?(call.arglist)
      first_arg = call.first_arg

      if call? first_arg and (first_arg.method == :slice or first_arg.method == :only)
        return
      elsif not node_type? first_arg, :hash
        if attr_protected
          confidence = CONFIDENCE[:med]
        else
          confidence = CONFIDENCE[:high]
        end
        user_input = input.match
      else
        confidence = CONFIDENCE[:low]
        user_input = input.match
      end
    else
      confidence = CONFIDENCE[:low]
      user_input = nil
    end

    warn :result => res,
      :warning_type => "Mass Assignment",
      :warning_code => :mass_assign_call,
      :message => "Unprotected mass assignment",
      :code => call,
      :user_input => user_input,
      :confidence => confidence
  end

  res
end

#run_checkObject


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 12

def run_check
  check_mass_assignment
  check_permit!
end

#subsequent_mass_assignment?(result) ⇒ Boolean

Look for actual use of params in mass assignment to avoid warning about uses of Parameters#permit! without any mass assignment or when mass assignment is restricted by model instead.

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 164

def subsequent_mass_assignment? result
  location = result[:location]
  line = result[:call].line
  find_mass_assign_calls.any? do |call|
    call[:location] == location and
    params? call[:call].first_arg and
    call[:call].line >= line
  end
end

#warn_on_permit!(result) ⇒ Object


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# File 'lib/brakeman/checks/check_mass_assignment.rb', line 174

def warn_on_permit! result
  return if duplicate? result or result[:call].original_line
  add_result result

  confidence = if subsequent_mass_assignment? result
                 CONFIDENCE[:high]
               else
                 CONFIDENCE[:med]
               end

  warn :result => result,
    :warning_type => "Mass Assignment",
    :warning_code => :mass_assign_permit!,
    :message => "Parameters should be whitelisted for mass assignment",
    :confidence => confidence
end