# frozen_string_literal: true require 'resolv' require 'ipaddress' module Gitlab class UrlBlocker BlockedUrlError = Class.new(StandardError) class << self def validate!(url, ports: [], protocols: [], allow_localhost: false, allow_local_network: true, ascii_only: false, enforce_user: false, enforce_sanitization: false) return true if url.nil? # Param url can be a string, URI or Addressable::URI uri = parse_url(url) validate_html_tags!(uri) if enforce_sanitization # Allow imports from the GitLab instance itself but only from the configured ports return true if internal?(uri) port = get_port(uri) validate_protocol!(uri.scheme, protocols) validate_port!(port, ports) if ports.any? validate_user!(uri.user) if enforce_user validate_hostname!(uri.hostname) validate_unicode_restriction!(uri) if ascii_only begin addrs_info = Addrinfo.getaddrinfo(uri.hostname, port, nil, :STREAM).map do |addr| addr.ipv6_v4mapped? ? addr.ipv6_to_ipv4 : addr end rescue SocketError return true end validate_localhost!(addrs_info) unless allow_localhost validate_loopback!(addrs_info) unless allow_localhost validate_local_network!(addrs_info) unless allow_local_network validate_link_local!(addrs_info) unless allow_local_network true end def blocked_url?(*args) validate!(*args) false rescue BlockedUrlError true end private def get_port(uri) uri.port || uri.default_port end def validate_html_tags!(uri) uri_str = uri.to_s sanitized_uri = ActionController::Base.helpers.sanitize(uri_str, tags: []) if sanitized_uri != uri_str raise BlockedUrlError, 'HTML/CSS/JS tags are not allowed' end end def parse_url(url) raise Addressable::URI::InvalidURIError if multiline?(url) Addressable::URI.parse(url) rescue Addressable::URI::InvalidURIError, URI::InvalidURIError raise BlockedUrlError, 'URI is invalid' end def multiline?(url) CGI.unescape(url.to_s) =~ /\n|\r/ end def validate_port!(port, ports) return if port.blank? # Only ports under 1024 are restricted return if port >= 1024 return if ports.include?(port) raise BlockedUrlError, "Only allowed ports are #{ports.join(', ')}, and any over 1024" end def validate_protocol!(protocol, protocols) if protocol.blank? || (protocols.any? && !protocols.include?(protocol)) raise BlockedUrlError, "Only allowed protocols are #{protocols.join(', ')}" end end def validate_user!(value) return if value.blank? return if value =~ /\A\p{Alnum}/ raise BlockedUrlError, "Username needs to start with an alphanumeric character" end def validate_hostname!(value) return if value.blank? return if IPAddress.valid?(value) return if value =~ /\A\p{Alnum}/ raise BlockedUrlError, "Hostname or IP address invalid" end def validate_unicode_restriction!(uri) return if uri.to_s.ascii_only? raise BlockedUrlError, "URI must be ascii only #{uri.to_s.dump}" end def validate_localhost!(addrs_info) local_ips = ["::", "0.0.0.0"] local_ips.concat(Socket.ip_address_list.map(&:ip_address)) return if (local_ips & addrs_info.map(&:ip_address)).empty? raise BlockedUrlError, "Requests to localhost are not allowed" end def validate_loopback!(addrs_info) return unless addrs_info.any? { |addr| addr.ipv4_loopback? || addr.ipv6_loopback? } raise BlockedUrlError, "Requests to loopback addresses are not allowed" end def validate_local_network!(addrs_info) return unless addrs_info.any? { |addr| addr.ipv4_private? || addr.ipv6_sitelocal? || addr.ipv6_unique_local? } raise BlockedUrlError, "Requests to the local network are not allowed" end def validate_link_local!(addrs_info) netmask = IPAddr.new('169.254.0.0/16') return unless addrs_info.any? { |addr| addr.ipv6_linklocal? || netmask.include?(addr.ip_address) } raise BlockedUrlError, "Requests to the link local network are not allowed" end def internal?(uri) internal_web?(uri) || internal_shell?(uri) end def internal_web?(uri) uri.scheme == config.gitlab.protocol && uri.hostname == config.gitlab.host && (uri.port.blank? || uri.port == config.gitlab.port) end def internal_shell?(uri) uri.scheme == 'ssh' && uri.hostname == config.gitlab_shell.ssh_host && (uri.port.blank? || uri.port == config.gitlab_shell.ssh_port) end def config Gitlab.config end end end end