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# frozen_string_literal: true
module RuboCop
module Cop
# Check for symlinks when extracting files to avoid arbitrary file reading.
class FileDecompression < RuboCop::Cop::Cop
MSG = <<~EOF
While extracting files check for symlink to avoid arbitrary file reading.
https://gitlab.com/gitlab-com/gl-infra/production/-/issues/6132
EOF
def_node_matcher :system?, <<~PATTERN
(send {nil? | const} {:system | :exec | :spawn | :popen}
(str $_))
PATTERN
def_node_matcher :subshell?, <<~PATTERN
(xstr
(str $_))
PATTERN
FORBIDDEN_COMMANDS = %w[gunzip gzip zip tar].freeze
def on_xstr(node)
subshell?(node) do |match|
add_offense(node, message: MSG) if forbidden_command?(match)
end
end
def on_send(node)
system?(node) do |match|
add_offense(node, location: :expression, message: MSG) if forbidden_command?(match)
end
end
private
def forbidden_command?(cmd)
FORBIDDEN_COMMANDS.any? do |forbidden|
cmd.match?(forbidden)
end
end
end
end
end
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