class Brakeman::CheckFileAccess

Checks for user input in methods which open or manipulate files

Public Instance Methods

called_on_tempfile?(file_name) click to toggle source

When using Tempfile, there is no risk of unauthorized file access, since Tempfile adds a unique string onto the end of every provided filename, and ensures that the filename does not already exist in the system.

# File lib/brakeman/checks/check_file_access.rb, line 70
def called_on_tempfile? file_name
  call?(file_name) && file_name.target == s(:const, :Tempfile)
end
process_result(result) click to toggle source
# File lib/brakeman/checks/check_file_access.rb, line 29
def process_result result
  return unless original? result
  call = result[:call]

  file_name = call.first_arg

  return if called_on_tempfile?(file_name) || sanitized?(file_name)

  if match = has_immediate_user_input?(file_name)
    confidence = :high
  elsif match = has_immediate_model?(file_name)
    match = Match.new(:model, match)
    confidence = :medium
  elsif tracker.options[:check_arguments] and
    match = include_user_input?(file_name)

    #Check for string building in file name
    if call?(file_name) and (file_name.method == :+ or file_name.method == :<<)
      confidence = :high
    else
      confidence = :weak
    end
  end

  if match and not temp_file_method? match.match

    message = msg(msg_input(match), " used in file name")

    warn :result => result,
      :warning_type => "File Access",
      :warning_code => :file_access,
      :message => message,
      :confidence => confidence,
      :code => call,
      :user_input => match
  end
end
run_check() click to toggle source
# File lib/brakeman/checks/check_file_access.rb, line 10
def run_check
  Brakeman.debug "Finding possible file access"
  methods = tracker.find_call :targets => [:Dir, :File, :IO, :Kernel, :"Net::FTP", :"Net::HTTP", :PStore, :Pathname, :Shell], :methods => [:[], :chdir, :chroot, :delete, :entries, :foreach, :glob, :install, :lchmod, :lchown, :link, :load, :load_file, :makedirs, :move, :new, :open, :read, :readlines, :rename, :rmdir, :safe_unlink, :symlink, :syscopy, :sysopen, :truncate, :unlink]

  methods.concat tracker.find_call :target => :YAML, :methods => [:load_file, :parse_file]
  methods.concat tracker.find_call :target => nil, :method => [:open]

  Brakeman.debug "Finding calls to load()"
  methods.concat tracker.find_call :target => false, :method => :load

  Brakeman.debug "Finding calls using FileUtils"
  methods.concat tracker.find_call :target => :FileUtils

  Brakeman.debug "Processing found calls"
  methods.each do |call|
    process_result call
  end
end
sanitized?(file) click to toggle source
# File lib/brakeman/checks/check_file_access.rb, line 74
def sanitized? file
  call?(file) &&
    call?(file.target) &&
    class_name(file.target.target) == :"ActiveStorage::Filename"
end
temp_file_method?(exp) click to toggle source
# File lib/brakeman/checks/check_file_access.rb, line 80
def temp_file_method? exp
  if call? exp
    return true if exp.call_chain.include? :tempfile

    params? exp.target and exp.method == :path
  end
end