Initial support for ActiveRecord enums (and other things, too)

lib/brakeman/processors/alias_processor.rb

@@ -208,6 +208,15 @@ def process_call exp
       return Sexp.new(:false).line(exp.line)
     end
 
+    # For the simplest case of `Foo.thing`
+    if node_type? target, :const and first_arg.nil?
+      if tracker and (klass = tracker.find_class(class_name(target.value)))
+        if return_value = klass.get_simple_method_return_value(:class, method)
+          return return_value.deep_clone(exp.line)
+        end
+      end
+    end
+
     #See if it is possible to simplify some basic cases
     #of addition/concatenation.
     case method
@@ -794,6 +803,18 @@ def process_cdecl exp
     exp
   end
 
+  def hash_or_array_include_all_literals? exp
+    return unless call? exp and sexp? exp.target
+    target = exp.target
+
+    case target.node_type
+    when :hash
+      hash_include_all_literals? exp
+    else
+      array_include_all_literals? exp
+    end
+  end
+
   # Check if exp is a call to Array#include? on an array literal
   # that contains all literal values. For example:
   #
@@ -812,6 +833,16 @@ def array_detect_all_literals? exp
     (all_literals? exp.target or dir_glob? exp.target)
   end
 
+  # Check if exp is a call to Hash#include? on a hash literal
+  # that contains all literal values. For example:
+  #
+  #    {x: 1}.include? x
+  def hash_include_all_literals? exp
+    call? exp and
+    exp.method == :include? and
+    all_literals? exp.target, :hash
+  end
+
   #Sets @inside_if = true
   def process_if exp
     if @ignore_ifs.nil?
@@ -852,15 +883,15 @@ def process_if exp
         scope do
           @branch_env = env.current
           branch_index = 2 + i # s(:if, condition, then_branch, else_branch)
-          if i == 0 and array_include_all_literals? condition
+          if i == 0 and hash_or_array_include_all_literals? condition
             # If the condition is ["a", "b"].include? x
             # set x to "a" inside the true branch
             var = condition.first_arg
             previous_value = env.current[var]
             env.current[var] = safe_literal(var.line)
             exp[branch_index] = process_if_branch branch
             env.current[var] = previous_value
-          elsif i == 1 and array_include_all_literals? condition and early_return? branch
+          elsif i == 1 and hash_or_array_include_all_literals? condition and early_return? branch
             var = condition.first_arg
             env.current[var] = safe_literal(var.line)
             exp[branch_index] = process_if_branch branch

lib/brakeman/processors/lib/call_conversion_helper.rb

@@ -1,11 +1,5 @@
 module Brakeman
   module CallConversionHelper
-    def all_literals? exp, expected_type = :array
-      node_type? exp, expected_type and
-        exp.length > 1 and
-        exp.all? { |e| e.is_a? Symbol or node_type? e, :lit, :str }
-    end
-
     # Join two array literals into one.
     def join_arrays lhs, rhs, original_exp = nil
       if array? lhs and array? rhs

lib/brakeman/processors/model_processor.rb

@@ -73,6 +73,8 @@ def process_call exp
           @current_class.set_attr_accessible exp
         when :attr_protected
           @current_class.set_attr_protected exp
+        when :enum
+          add_enum_method exp
         else
           if @current_class
             @current_class.add_option method, exp
@@ -87,4 +89,33 @@ def process_call exp
       call
     end
   end
+
+  def add_enum_method call
+    arg = call.first_arg
+    return unless hash? arg
+
+    enum_name = arg[1].value # first key
+    enums = arg[2] # first value
+    enums_name = pluralize(enum_name.to_s).to_sym
+
+    call_line = call.line
+
+    if hash? enums
+      enum_values = enums
+    elsif array? enums
+      # Build hash for enum values like Rails does
+      enum_values = s(:hash).line(call_line)
+
+      enums.each_sexp.with_index do |v, index|
+        enum_values << v
+        enum_values << s(:lit, index).line(call_line)
+      end
+    end
+
+    enum_method = s(:defn, enum_name, s(:args), safe_literal(call_line))
+    enums_method = s(:defs, s(:self), enums_name, s(:args), enum_values)
+
+    @current_class.add_method :public, enum_name, enum_method, @current_file
+    @current_class.add_method :public, enums_name, enums_method, @current_file
+  end
 end

lib/brakeman/tracker/collection.rb

@@ -15,6 +15,7 @@ def initialize name, parent, file_name, src, tracker
       @includes = []
       @methods = { :public => {}, :private => {}, :protected => {} }
       @class_methods = {}
+      @simple_methods = { :class => {}, instance: {} }
       @options = {}
       @tracker = tracker
 
@@ -49,6 +50,7 @@ def add_option name, exp
 
     def add_method visibility, name, src, file_name
       meth_info = Brakeman::MethodInfo.new(name, src, self, file_name)
+      add_simple_method_maybe meth_info
 
       if src.node_type == :defs
         @class_methods[name] = meth_info
@@ -112,5 +114,31 @@ def top_line
     def methods_public
       @methods[:public]
     end
+
+    def get_simple_method_return_value type, name
+      @simple_methods[type][name]
+    end
+
+    private
+
+    def add_simple_method_maybe meth_info
+      if meth_info.very_simple_method?
+        add_simple_method meth_info
+      end
+    end
+
+    def add_simple_method meth_info
+      name = meth_info.name
+      value = meth_info.return_value
+
+      case meth_info.src.node_type
+      when :defn
+        @simple_methods[:instance][name] = value
+      when :defs
+        @simple_methods[:class][name] = value
+      else
+        raise "Expected sexp type: #{src.node_type}"
+      end
+    end
   end
 end

lib/brakeman/tracker/method_info.rb

@@ -19,11 +19,52 @@ def initialize name, src, owner, file
               else
                 raise "Expected sexp type: #{src.node_type}"
               end
+
+      @simple_method = nil
     end
 
     # To support legacy code that expected a Hash
     def [] attr
       self.send(attr)
     end
+
+    def very_simple_method?
+      return @simple_method == :very unless @simple_method.nil?
+
+      # Very simple methods have one (simple) expression in the body and
+      # no arguments
+      if src.formal_args.length == 1 # no args
+        if src.method_length == 1 # Single expression in body
+          value = first_body # First expression in body
+
+          if simple_literal? value or
+              (array? value and all_literals? value) or
+              (hash? value and all_literals? value, :hash)
+
+            @return_value = value
+            @simple_method = :very
+          end
+        end
+      end
+
+      @simple_method ||= false
+    end
+
+    def return_value env = nil
+      if very_simple_method?
+        return @return_value
+      else
+        nil
+      end
+    end
+
+    def first_body
+      case @type
+      when :class
+        src[4]
+      when :instance
+        src[3]
+      end
+    end
   end
 end

lib/brakeman/util.rb

@@ -50,7 +50,11 @@ def underscore camel_cased_word
 
   # stupid simple, used to delegate to ActiveSupport
   def pluralize word
-    word + "s"
+    if word.end_with? 's'
+      word + 'es'
+    else
+      word + 's'
+    end
   end
 
   #Returns a class name as a Symbol.
@@ -293,12 +297,24 @@ def node_type? exp, *types
     exp.is_a? Sexp and types.include? exp.node_type
   end
 
-  LITERALS = [:lit, :false, :str, :true, :array, :hash]
+  SIMPLE_LITERALS = [:lit, :false, :str, :true]
+
+  def simple_literal? exp
+    exp.is_a? Sexp and SIMPLE_LITERALS.include? exp.node_type
+  end
+
+  LITERALS = [*SIMPLE_LITERALS, :array, :hash]
 
   def literal? exp
     exp.is_a? Sexp and LITERALS.include? exp.node_type
   end
 
+  def all_literals? exp, expected_type = :array
+    node_type? exp, expected_type and
+      exp.length > 1 and
+      exp.all? { |e| e.is_a? Symbol or node_type? e, :lit, :str }
+  end
+
   DIR_CONST = s(:const, :Dir)
 
   # Dir.glob(...).whatever

lib/ruby_parser/bm_sexp.rb

@@ -543,6 +543,20 @@ def body_list
     self.body.unshift :rlist
   end
 
+  # Number of "statements" in a method.
+  # This is more effecient than `Sexp#body.length`
+  # because `Sexp#body` creates a new Sexp.
+  def method_length
+    expect :defn, :defs
+
+    case self.node_type
+    when :defn
+      self.length - 3
+    when :defs
+      self.length - 4
+    end
+  end
+
   def render_type
     expect :render
     self[1]

test/apps/rails6/app/controllers/groups_controller.rb

@@ -69,4 +69,15 @@ def test_rails6_sqli
     User.order("name #{params[:direction]}") # Warn in 6.0, not in 6.1
     User.order(:name).reorder(params[:column]) # Warn in 6.0, not in 6.1
   end
+
+  # From https://github.com/presidentbeef/brakeman/issues/1492
+  def enum_include_check
+    status = "#{params[:status]}"
+    if Group.statuses.include? status
+      @status = status.to_sym
+      @countries = Group.send(@status) # Should not warn
+    else
+      redirect_to root_path, notice: 'Invalid status'
+    end
+  end
 end

test/apps/rails6/app/models/group.rb

@@ -18,4 +18,20 @@ def fetch_constant_hash_value(role_name)
     role = roles.fetch(role_name)
     Arel.sql("role = '#{role}'")
   end
+
+  def use_simple_method
+    # No warning
+    self.where("thing = #{Group.simple_method}")
+  end
+
+  def self.simple_method
+    "Hello"
+  end
+
+  enum status: { start: 0, stop: 2, in_process: 3 }
+
+  def use_enum
+    # No warning
+    self.where("thing IN #{Group.statuses.values_at(*[:start, :stop]).join(',')}")
+  end
 end

test/apps/rails6/app/models/user.rb

@@ -24,4 +24,10 @@ def self.more_heredocs
   def recent_stuff
     where("date > #{Date.today - 1}")
   end
+
+  enum state: ["pending", "active", "archived"]
+
+  def check_enum
+    where("state = #{User.states["pending"]}")
+  end
 end

test/tests/rails6.rb

@@ -254,6 +254,32 @@ def test_sql_injection_reorder
       :user_input => s(:call, s(:params), :[], s(:lit, :column))
   end
 
+  def test_sql_injection_enum
+    assert_no_warning :type => :warning,
+      :warning_code => 0,
+      :fingerprint => "b2071137eba7ef6ecbcc1c6381a428e5c576a5fadf73dc04b2e155c41043e1d2",
+      :warning_type => "SQL Injection",
+      :line => 31,
+      :message => /^Possible\ SQL\ injection/,
+      :confidence => 0,
+      :relative_path => "app/models/user.rb",
+      :code => s(:call, nil, :where, s(:dstr, "state = ", s(:evstr, s(:call, s(:call, s(:const, :User), :states), :[], s(:str, "pending"))))),
+      :user_input => s(:call, s(:call, s(:const, :User), :states), :[], s(:str, "pending"))
+  end
+
+  def test_dangerous_send_enum
+    assert_no_warning :type => :warning,
+      :warning_code => 23,
+      :fingerprint => "483fa36e41f5791e86f345a19b517a61859886d685ce40ef852871bb7a935f2d",
+      :warning_type => "Dangerous Send",
+      :line => 78,
+      :message => /^User\ controlled\ method\ execution/,
+      :confidence => 0,
+      :relative_path => "app/controllers/groups_controller.rb",
+      :code => s(:call, s(:const, :Group), :send, s(:call, s(:dstr, "", s(:evstr, s(:call, s(:params), :[], s(:lit, :status)))), :to_sym)),
+      :user_input => s(:call, s(:params), :[], s(:lit, :status))
+  end
+
   def test_cross_site_scripting_sanity
     assert_warning :type => :template,
       :warning_code => 2,