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sobelow lib sobelow traversal send_file.ex
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lib/sobelow/traversal/send_file.ex

defmodule Sobelow.Traversal.SendFile do
alias Sobelow.Utils
use Sobelow.Finding
def run(fun, filename) do
severity = if String.ends_with?(filename, "_controller.ex"), do: false, else: :low
# If the file is a controller, check for `send_file` as well as
# `Plug.Conn.send_file`. If it is not a controller, look for
# `Plug.Conn.send_file` only.
if String.ends_with?(filename, "_controller.ex") do
{vars, params, {fun_name, [{_, line_no}]}} = parse_send_file_def(fun)
Enum.each vars, fn var ->
if Enum.member?(params, var) || var === "conn.params" do
print_finding(line_no, filename, fun_name, fun, var, severity || :high)
else
print_finding(line_no, filename, fun_name, fun, var, severity || :medium)
end
end
else
{vars, params, {fun_name, [{_, line_no}]}} = parse_aliased_send_file_def(fun)
Enum.each vars, fn var ->
if Enum.member?(params, var) || var === "conn.params" do
print_finding(line_no, filename, fun_name, fun, var, severity || :high)
else
print_finding(line_no, filename, fun_name, fun, var, severity || :medium)
end
end
end
end
## send_file(conn, status, file, offset \\ 0, length \\ :all)
##
## send_file has optional params, so the parameter we care about
## for traversal won't be at a definite location. This is a
## simple solution to the problem.
defp parse_send_file_def(fun) do
{params, {fun_name, line_no}} = Utils.get_fun_declaration(fun)
pipefuns = Utils.get_pipe_funs(fun)
|> Enum.map(fn {_, _, opts} -> Enum.at(opts, 1) end)
|> Enum.flat_map(&Utils.get_funs_of_type(&1, :send_file))
pipefiles = pipefuns
|> Enum.map(&Utils.extract_opts(&1, 1))
|> List.flatten
files = Utils.get_funs_of_type(fun, :send_file) -- pipefuns
|> Enum.map(&Utils.extract_opts(&1, 2))
|> List.flatten
{aliased_files, _, _} = parse_aliased_send_file_def(fun)
{files ++ pipefiles ++ aliased_files, params, {fun_name, line_no}}
end
defp parse_aliased_send_file_def(fun) do
{params, {fun_name, line_no}} = Utils.get_fun_declaration(fun)
pipefuns = Utils.get_pipe_funs(fun)
|> Enum.map(fn {_, _, opts} -> Enum.at(opts, 1) end)
|> Enum.flat_map(&Utils.get_aliased_funs_of_type(&1, :send_file, [:Plug, :Conn]))
pipefiles = pipefuns
|> Enum.map(&Utils.extract_opts(&1, 1))
|> List.flatten
aliased_files = Utils.get_aliased_funs_of_type(fun, :send_file, [:Plug, :Conn]) -- pipefuns
|> Enum.map(&Utils.extract_opts(&1, 2))
|> List.flatten
{aliased_files ++ pipefiles, params, {fun_name, line_no}}
end
def print_finding(line_no, con, fun_name, fun, var, severity) do
{color, confidence} = case severity do
:high -> {IO.ANSI.red(), "High"}
:medium -> {IO.ANSI.yellow(), "Medium"}
:low -> {IO.ANSI.green(), "Low"}
end
IO.puts color <> "Directory Traversal in `send_file` - #{confidence} Confidence" <> IO.ANSI.reset()
IO.puts "File: #{con} - #{fun_name}:#{line_no}"
IO.puts "Variable: #{var}"
if Sobelow.get_env(:with_code), do: Utils.print_code(fun, var, :send_file)
IO.puts "\n-----------------------------------------------\n"
end
def get_details() do
Sobelow.Traversal.details()
end
end