Class: Brakeman::CheckSQL

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

Overview

This check tests for find calls which do not use Rails' auto SQL escaping

For example: Project.find(:all, :conditions => “name = '” + params + “'”)

Project.find(:all, :conditions => “name = '#:name'”)

User.find_by_sql(“SELECT * FROM projects WHERE name = '#:name'”)

Constant Summary collapse

STRING_METHODS =
Set[:<<, :+, :concat, :prepend]
IGNORE_METHODS_IN_SQL =
Set[:id, :merge_conditions, :table_name, :to_i, :to_f,
:sanitize_sql, :sanitize_sql_array, :sanitize_sql_for_assignment,
:sanitize_sql_for_conditions, :sanitize_sql_hash,
:sanitize_sql_hash_for_assignment, :sanitize_sql_hash_for_conditions,
:to_sql, :sanitize, :exists]
QUOTE_METHODS =
[:quote, :quote_column_name, :quoted_date, :quote_string, :quote_table_name]
SELF_CLASS =
s(:call, s(:self), :class)

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

#ar_scope_calls(symbol_name = :named_scope, &block) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 84

def ar_scope_calls(symbol_name = :named_scope, &block)
  return_array = []
  active_record_models.each do |name, model|
    model_args = model[:options][symbol_name]
    if model_args
      model_args.each do |args|
        yield name, args
        return_array << [name, args]
      end
    end
  end
  return_array
end

#check_by_sql_arguments(arg) ⇒ Object

find_by_sql and count_by_sql can take either a straight SQL string or an array with values to bind.


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# File 'lib/brakeman/checks/check_sql.rb', line 297

def check_by_sql_arguments arg
  return unless sexp? arg

  #This is kind of unnecessary, because unsafe_sql? will handle an array
  #correctly, but might be better to be explicit.
  array?(arg) ? unsafe_sql?(arg[1]) : unsafe_sql?(arg)
end

#check_call(exp) ⇒ Object

Check call for string building


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# File 'lib/brakeman/checks/check_sql.rb', line 590

def check_call exp
  return unless call? exp
  unsafe = check_for_string_building exp

  if unsafe
    unsafe
  elsif call? exp.target
    check_call exp.target
  else
    nil
  end
end

#check_find_arguments(arg) ⇒ Object

The 'find' methods accept a number of different types of parameters:

  • The first argument might be :all, :first, or :last

  • The first argument might be an integer ID or an array of IDs

  • The second argument might be a hash of options, some of which are dangerous and some of which are not

  • The second argument might contain SQL fragments as values

  • The second argument might contain properly parameterized SQL fragments in arrays

  • The second argument might contain improperly parameterized SQL fragments in arrays

This method should only be passed the second argument.


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# File 'lib/brakeman/checks/check_sql.rb', line 243

def check_find_arguments arg
  return nil if not sexp? arg or node_type? arg, :lit, :string, :str, :true, :false, :nil

  unsafe_sql? arg
end

#check_for_limit_or_offset_vulnerability(options) ⇒ Object

Prior to Rails 2.1.1, the :offset and :limit parameters were not escaping input properly.

www.rorsecurity.info/2008/09/08/sql-injection-issue-in-limit-and-offset-parameter/


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# File 'lib/brakeman/checks/check_sql.rb', line 607

def check_for_limit_or_offset_vulnerability options
  return false if @rails_version.nil? or @rails_version >= "2.1.1" or not hash?(options)

  return true if hash_access(options, :limit) or hash_access(options, :offset)

  false
end

#check_for_string_building(exp) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 491

def check_for_string_building exp
  return unless call? exp

  target = exp.target
  method = exp.method
  arg = exp.first_arg

  if STRING_METHODS.include? method
    check_str_target_or_arg(target, arg) or
    check_interp_target_or_arg(target, arg) or
    check_for_string_building(target) or
    check_for_string_building(arg)
  else
    nil
  end
end

#check_hash_keys(exp) ⇒ Object

Check hash keys for user input. (Seems unlikely, but if a user can control the column names queried, that could be bad)


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# File 'lib/brakeman/checks/check_sql.rb', line 344

def check_hash_keys exp
  hash_iterate(exp) do |key, value|
    unless symbol?(key)
      unsafe_key = unsafe_sql? value
      return unsafe_key if unsafe_key
    end
  end

  false
end

#check_hash_values(exp) ⇒ Object

Checks hash values associated with these keys:

  • conditions

  • order

  • having

  • joins

  • select

  • from

  • lock


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# File 'lib/brakeman/checks/check_sql.rb', line 464

def check_hash_values exp
  hash_iterate(exp) do |key, value|
    if symbol? key
      unsafe = case key.value
               when :conditions, :having, :select
                 check_query_arguments value
               when :order, :group
                 check_order_arguments value
               when :joins
                 check_joins_arguments value
               when :lock
                 check_lock_arguments value
               when :from
                 unsafe_sql? value
               else
                 nil
               end

      return unsafe if unsafe
    end
  end

  false
end

#check_interp_target_or_arg(target, arg) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 516

def check_interp_target_or_arg target, arg
  if node_type? target, :string_interp, :dstr or
    node_type? arg, :string_interp, :dstr

    check_string_arg target and
    check_string_arg arg
  end
end

#check_joins_arguments(arg) ⇒ Object

joins can take a string, hash of associations, or an array of both(?) We only care about the possible string values.


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# File 'lib/brakeman/checks/check_sql.rb', line 307

def check_joins_arguments arg
  return unless sexp? arg and not node_type? arg, :hash, :string, :str

  if array? arg
    arg.each do |a|
      unsafe_arg = check_joins_arguments a
      return unsafe_arg if unsafe_arg
    end

    nil
  else
    unsafe_sql? arg
  end
end

#check_lock_arguments(arg) ⇒ Object

Model#lock essentially only cares about strings. But those strings can be any SQL fragment. This does not apply to all databases. (For those who do not support it, the lock method does nothing).


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# File 'lib/brakeman/checks/check_sql.rb', line 334

def check_lock_arguments arg
  return unless sexp? arg and not node_type? arg, :hash, :array, :string, :str

  unsafe_sql?(arg, :ignore_hash)
end

#check_order_arguments(args) ⇒ Object

Checks each argument to order/reorder/group for possible SQL. Anything used with these methods is passed in verbatim.


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# File 'lib/brakeman/checks/check_sql.rb', line 285

def check_order_arguments args
  return unless sexp? args

  if node_type? args, :arglist
    check_update_all_arguments(args)
  else
    unsafe_sql? args
  end
end

#check_query_arguments(arg) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 255

def check_query_arguments arg
  return unless sexp? arg
  first_arg = arg[1]

  if node_type? arg, :arglist
    if arg.length > 2 and node_type? first_arg, :string_interp, :dstr
      # Model.where("blah = ?", blah)
      return check_string_interp first_arg
    else
      arg = first_arg
    end
  end

  if request_value? arg
    # Model.where(params[:where])
    arg
  elsif hash? arg
    #This is generally going to be a hash of column names and values, which
    #would escape the values. But the keys _could_ be user input.
    check_hash_keys arg
  elsif node_type? arg, :lit, :str
    nil
  else
    #Hashes are safe...but we check above for hash, so...?
    unsafe_sql? arg, :ignore_hash
  end
end

#check_scope_arguments(call) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 249

def check_scope_arguments call
  scope_arg = call.second_arg #first arg is name of scope

  node_type?(scope_arg, :iter) ? unsafe_sql?(scope_arg.block) : unsafe_sql?(scope_arg)
end

#check_str_target_or_arg(target, arg) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 508

def check_str_target_or_arg target, arg
  if string? target
    check_string_arg arg
  elsif string? arg
    check_string_arg target
  end
end

#check_string_arg(exp) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 525

def check_string_arg exp
  if safe_value? exp
    nil
  elsif string_building? exp
    check_for_string_building exp
  elsif node_type? exp, :string_interp, :dstr
    check_string_interp exp
  elsif call? exp and exp.method == :to_s
    check_string_arg exp.target
  else
    exp
  end
end

#check_string_interp(arg) ⇒ Object

Check an interpolated string for dangerous values.

This method assumes values interpolated into strings are unsafe by default, unless safe_value? explicitly returns true.


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# File 'lib/brakeman/checks/check_sql.rb', line 359

def check_string_interp arg
  arg.each do |exp|
    if dangerous = unsafe_string_interp?(exp)
      return dangerous
    end
  end

  nil
end

#check_update_all_arguments(args) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 322

def check_update_all_arguments args
  args.each do |arg|
    unsafe_arg = unsafe_sql? arg
    return unsafe_arg if unsafe_arg
  end

  nil
end

#connect_call?(result) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 636

def connect_call? result
  call = result[:call]
  target = call.target

  if call? target and target.method == :connection
    target = target.target
    klass = class_name(target)

    target.nil? or
    target == SELF_CLASS or
    node_type? target, :self or
    klass == :"ActiveRecord::Base" or
    active_record_models.include? klass
  end
end

#constantize_call?(result) ⇒ Boolean

Look for something like this:

params.constantize.find('something')

s(:call,

s(:call,
  s(:call,
    s(:call, nil, :params, s(:arglist)),
    :[],
    s(:arglist, s(:lit, :x))),
  :constantize,
  s(:arglist)),
:find,
s(:arglist, s(:str, "something")))

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 629

def constantize_call? result
  call = result[:call]
  call? call.target and call.target.method == :constantize
end

#find_dangerous_value(exp, ignore_hash) ⇒ Object

Check exp for dangerous values. Used by unsafe_sql?


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# File 'lib/brakeman/checks/check_sql.rb', line 413

def find_dangerous_value exp, ignore_hash
  case exp.node_type
  when :lit, :str, :const, :colon2, :true, :false, :nil
    nil
  when :array
    #Assume this is an array like
    #
    #  ["blah = ? AND thing = ?", ...]
    #
    #and check first value
    unsafe_sql? exp[1]
  when :string_interp, :dstr
    check_string_interp exp
  when :hash
    check_hash_values exp unless ignore_hash
  when :if
    unsafe_sql? exp.then_clause or unsafe_sql? exp.else_clause
  when :call
    unless IGNORE_METHODS_IN_SQL.include? exp.method
      if has_immediate_user_input? exp or has_immediate_model? exp
        exp
      else
        check_call exp
      end
    end
  when :or
    if unsafe = (unsafe_sql?(exp.lhs) || unsafe_sql?(exp.rhs))
      unsafe
    else
      nil
    end
  when :block, :rlist
    unsafe_sql? exp.last
  else
    if has_immediate_user_input? exp or has_immediate_model? exp
      exp
    else
      nil
    end
  end
end

#find_scope_callsObject

Find calls to named_scope() or scope() in models RP 3 TODO


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# File 'lib/brakeman/checks/check_sql.rb', line 56

def find_scope_calls
  scope_calls = []

  if version_between?("2.1.0", "3.0.9")
    ar_scope_calls(:named_scope) do |name, args|
      call = make_call(nil, :named_scope, args).line(args.line)
      scope_calls << scope_call_hash(call, name, :named_scope)
    end
  elsif version_between?("3.1.0", "4.9.9")
    ar_scope_calls(:scope) do |name, args|
      second_arg = args[2]
      next unless sexp? second_arg

      if second_arg.node_type == :iter and node_type? second_arg.block, :block, :call
        process_scope_with_block(name, args)
      elsif second_arg.node_type == :call
        call = second_arg
        scope_calls << scope_call_hash(call, name, call.method)
      else
        call = make_call(nil, :scope, args).line(args.line)
        scope_calls << scope_call_hash(call, name, :scope)
      end
    end
  end

  scope_calls
end

#process_result(result) ⇒ Object

Process possible SQL injection sites:

Model#find

Model#(named_)scope

Model#(find|count)_by_sql

Model#all

Rails 3

Model#(where|having) Model#(order|group)

Find Options Hash

Dangerous keys that accept SQL:

  • conditions

  • order

  • having

  • joins

  • select

  • from

  • lock


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# File 'lib/brakeman/checks/check_sql.rb', line 149

def process_result result
  return if duplicate?(result) or result[:call].original_line
  return if result[:target].nil? && !active_record_models.include?(result[:location][:class])


  call = result[:call]
  method = call.method

  dangerous_value = case method
                    when :find
                      check_find_arguments call.second_arg
                    when :exists?, :delete_all, :destroy_all
                      check_find_arguments call.first_arg
                    when :named_scope, :scope
                      check_scope_arguments call
                    when :find_by_sql, :count_by_sql
                      check_by_sql_arguments call.first_arg
                    when :calculate
                      check_find_arguments call.third_arg
                    when :last, :first, :all
                      check_find_arguments call.first_arg
                    when :average, :count, :maximum, :minimum, :sum
                      if call.length > 5
                        unsafe_sql?(call.first_arg) or check_find_arguments(call.last_arg)
                      else
                        check_find_arguments call.last_arg
                      end
                    when :where, :having, :find_by, :find_by!
                      check_query_arguments call.arglist
                    when :order, :group, :reorder
                      check_order_arguments call.arglist
                    when :joins
                      check_joins_arguments call.first_arg
                    when :from
                      unsafe_sql? call.first_arg
                    when :lock
                      check_lock_arguments call.first_arg
                    when :pluck
                      unsafe_sql? call.first_arg
                    when :update_all, :select
                      check_update_all_arguments call.args
                    when *@connection_calls
                      check_by_sql_arguments call.first_arg
                    else
                      Brakeman.debug "Unhandled SQL method: #{method}"
                    end

  if dangerous_value
    add_result result

    input = include_user_input? dangerous_value
    if input
      confidence = CONFIDENCE[:high]
      user_input = input.match
    else
      confidence = CONFIDENCE[:med]
      user_input = dangerous_value
    end

    warn :result => result,
      :warning_type => "SQL Injection",
      :warning_code => :sql_injection,
      :message => "Possible SQL injection",
      :user_input => user_input,
      :confidence => confidence
  end

  if check_for_limit_or_offset_vulnerability call.last_arg
    if include_user_input? call.last_arg
      confidence = CONFIDENCE[:high]
    else
      confidence = CONFIDENCE[:low]
    end

    warn :result => result,
      :warning_type => "SQL Injection",
      :warning_code => :sql_injection_limit_offset,
      :message => "Upgrade to Rails >= 2.1.2 to escape :limit and :offset. Possible SQL injection",
      :confidence => confidence
  end
end

#process_scope_with_block(model_name, args) ⇒ Object


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

def process_scope_with_block model_name, args
  scope_name = args[1][1]
  block = args[-1][-1]

  # Search lambda for calls to query methods
  if block.node_type == :block
    find_calls = Brakeman::FindAllCalls.new(tracker)
    find_calls.process_source(block, :class => model_name, :method => scope_name)
    find_calls.calls.each { |call| process_result(call) if @sql_targets.include?(call[:method]) }
  elsif block.node_type == :call
    while call? block
      process_result :target => block.target, :method => block.method, :call => block,
       :location => { :type => :class, :class => model_name, :method => scope_name }

      block = block.target
    end
  end
end

#quote_call?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 581

def quote_call? exp
  if call? exp.target
    exp.target.method == :connection and QUOTE_METHODS.include? exp.method
  elsif exp.target.nil?
    exp.method == :quote_value
  end
end

#run_checkObject


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# File 'lib/brakeman/checks/check_sql.rb', line 16

def run_check
  @rails_version = tracker.config[:rails_version]

  @sql_targets = [:all, :average, :calculate, :count, :count_by_sql, :exists?, :delete_all, :destroy_all,
    :find, :find_by_sql, :first, :last, :maximum, :minimum, :pluck, :sum, :update_all]
  @sql_targets.concat [:from, :group, :having, :joins, :lock, :order, :reorder, :select, :where] if tracker.options[:rails3]
  @sql_targets << :find_by << :find_by! if tracker.options[:rails4]

  @connection_calls = [:delete, :execute, :insert, :select_all, :select_one,
    :select_rows, :select_value, :select_values]

  if tracker.options[:rails3]
    @connection_calls.concat [:exec_delete, :exec_insert, :exec_query, :exec_update]
  else
    @connection_calls.concat [:add_limit!, :add_offset_limit!, :add_lock!]
  end

  Brakeman.debug "Finding possible SQL calls on models"
  calls = tracker.find_call :targets => active_record_models.keys,
    :methods => @sql_targets,
    :chained => true

  Brakeman.debug "Finding possible SQL calls with no target"
  calls.concat tracker.find_call(:target => nil, :methods => @sql_targets)

  Brakeman.debug "Finding possible SQL calls using constantized()"
  calls.concat tracker.find_call(:methods => @sql_targets).select { |result| constantize_call? result }

  connect_targets = active_record_models.keys + [nil, :"ActiveRecord::Base"]
  calls.concat tracker.find_call(:targets => connect_targets, :methods => @connection_calls, :chained => true).select { |result| connect_call? result }

  Brakeman.debug "Finding calls to named_scope or scope"
  calls.concat find_scope_calls

  Brakeman.debug "Processing possible SQL calls"
  calls.each { |call| process_result call }
end

#safe_value?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 554

def safe_value? exp
  return true unless sexp? exp

  case exp.node_type
  when :str, :lit, :const, :colon2, :nil, :true, :false
    true
  when :call
    if exp.method == :to_s
      safe_value? exp.target
    else
      IGNORE_METHODS_IN_SQL.include? exp.method or
      quote_call? exp or
      exp.method.to_s.end_with? "_id"
    end
  when :if
    safe_value? exp.then_clause and safe_value? exp.else_clause
  when :block, :rlist
    safe_value? exp.last
  when :or
    safe_value? exp.lhs and safe_value? exp.rhs
  else
    false
  end
end

#scope_call_hash(call, name, method) ⇒ Object


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# File 'lib/brakeman/checks/check_sql.rb', line 98

def scope_call_hash(call, name, method)
  { :call => call, :location => { :type => :class, :class => name }, :method => :named_scope }
end

#string_building?(exp) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 539

def string_building? exp
  return false unless call? exp and STRING_METHODS.include? exp.method

  node_type? exp.target, :str, :dstr, :string_interp or
  node_type? exp.first_arg, :str, :dstr, :string_interp or
  string_building? exp.target or
  string_building? exp.first_arg
end

#unsafe_sql?(exp, ignore_hash = false) ⇒ Boolean

Checks the given expression for unsafe SQL values. If an unsafe value is found, returns that value (may be the given exp or a subexpression).

Otherwise, returns false/nil.

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 405

def unsafe_sql? exp, ignore_hash = false
  return unless sexp?(exp)

  dangerous_value = find_dangerous_value exp, ignore_hash
  safe_value?(dangerous_value) ? false : dangerous_value
end

#unsafe_string_interp?(exp) ⇒ Boolean

Returns value if interpolated value is not something safe

Returns:

  • (Boolean)

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# File 'lib/brakeman/checks/check_sql.rb', line 370

def unsafe_string_interp? exp
  if node_type? exp, :string_eval, :evstr
    value = exp.value
  else
    value = exp
  end

  if not sexp? value
    nil
  elsif call? value and value.method == :to_s
    unsafe_string_interp? value.target
  else
    case value.node_type
    when :or
      unsafe_string_interp?(value.lhs) || unsafe_string_interp?(value.rhs)
    when :string_interp, :dstr
      if dangerous = check_string_interp(value)
        return dangerous
      end
    else
      if safe_value? value
        nil
      elsif string_building? value
        check_for_string_building value
      else
        value
      end
    end
  end
end