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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
# Sobelow.log_finding("Directory Traversal", severity || :high)
print_finding(line_no, filename, fun_name, fun, var, severity || :high)
else
# Sobelow.log_finding("Directory Traversal", severity || :medium)
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
{files, params, {fun_name, line_no}} = Utils.get_fun_vars_and_meta(fun, 2, :send_file)
{aliased_files,_,_} = Utils.get_fun_vars_and_meta(fun, 2, :send_file, [:Plug, :Conn])
{files ++ aliased_files, params, {fun_name, line_no}}
end
defp parse_aliased_send_file_def(fun) do
Utils.get_fun_vars_and_meta(fun, 2, :send_file, [:Plug, :Conn])
end
def print_finding(line_no, filename, fun_name, fun, var, severity) do
Utils.add_finding(line_no, filename, fun,
fun_name, var, severity,
"Directory Traversal in `send_file`", :send_file, [:Plug, :Conn])
end
def get_details() do
Sobelow.Traversal.details()
end
end