# frozen_string_literal: true require 'resolv' require 'ipaddress' module Gitlab class UrlBlocker BlockedUrlError = Class.new(StandardError) class << self # Validates the given url according to the constraints specified by arguments. # # ports - Raises error if the given URL port does is not between given ports. # allow_localhost - Raises error if URL resolves to a localhost IP address and argument is false. # allow_local_network - Raises error if URL resolves to a link-local address and argument is false. # ascii_only - Raises error if URL has unicode characters and argument is true. # enforce_user - Raises error if URL user doesn't start with alphanumeric characters and argument is true. # enforce_sanitization - Raises error if URL includes any HTML/CSS/JS tags and argument is true. # # Returns an array with [, ]. # rubocop:disable Metrics/ParameterLists def validate!( url, ports: [], schemes: [], allow_localhost: false, allow_local_network: true, ascii_only: false, enforce_user: false, enforce_sanitization: false, dns_rebind_protection: true) # rubocop:enable Metrics/ParameterLists return [nil, nil] if url.nil? # Param url can be a string, URI or Addressable::URI uri = parse_url(url) validate_uri( uri: uri, schemes: schemes, ports: ports, enforce_sanitization: enforce_sanitization, enforce_user: enforce_user, ascii_only: ascii_only ) address_info = get_address_info(uri, dns_rebind_protection) return [uri, nil] unless address_info ip_address = ip_address(address_info) return [uri, nil] if domain_whitelisted?(uri) || ip_whitelisted?(ip_address, port: get_port(uri)) protected_uri_with_hostname = enforce_uri_hostname(ip_address, uri, dns_rebind_protection) # Allow url from the GitLab instance itself but only for the configured hostname and ports return protected_uri_with_hostname if internal?(uri) validate_local_request( address_info: address_info, allow_localhost: allow_localhost, allow_local_network: allow_local_network ) protected_uri_with_hostname end def blocked_url?(*args) validate!(*args) false rescue BlockedUrlError true end private # Returns the given URI with IP address as hostname and the original hostname respectively # in an Array. # # It checks whether the resolved IP address matches with the hostname. If not, it changes # the hostname to the resolved IP address. # # The original hostname is used to validate the SSL, given in that scenario # we'll be making the request to the IP address, instead of using the hostname. def enforce_uri_hostname(ip_address, uri, dns_rebind_protection) return [uri, nil] unless dns_rebind_protection && ip_address && ip_address != uri.hostname new_uri = uri.dup new_uri.hostname = ip_address [new_uri, uri.hostname] end def ip_address(address_info) address_info.first&.ip_address end def validate_uri(uri:, schemes:, ports:, enforce_sanitization:, enforce_user:, ascii_only:) validate_html_tags(uri) if enforce_sanitization return if internal?(uri) validate_scheme(uri.scheme, schemes) validate_port(get_port(uri), ports) if ports.any? validate_user(uri.user) if enforce_user validate_hostname(uri.hostname) validate_unicode_restriction(uri) if ascii_only end def get_address_info(uri, dns_rebind_protection) Addrinfo.getaddrinfo(uri.hostname, get_port(uri), nil, :STREAM).map do |addr| addr.ipv6_v4mapped? ? addr.ipv6_to_ipv4 : addr end rescue SocketError # If the dns rebinding protection is not enabled or the domain # is whitelisted we avoid the dns rebinding checks return if domain_whitelisted?(uri) || !dns_rebind_protection # In the test suite we use a lot of mocked urls that are either invalid or # don't exist. In order to avoid modifying a ton of tests and factories # we allow invalid urls unless the environment variable RSPEC_ALLOW_INVALID_URLS # is not true return if Rails.env.test? && ENV['RSPEC_ALLOW_INVALID_URLS'] == 'true' # If the addr can't be resolved or the url is invalid (i.e http://1.1.1.1.1) # we block the url raise BlockedUrlError, "Host cannot be resolved or invalid" rescue ArgumentError => error # Addrinfo.getaddrinfo errors if the domain exceeds 1024 characters. raise unless error.message.include?('hostname too long') raise BlockedUrlError, "Host is too long (maximum is 1024 characters)" end def validate_local_request( address_info:, allow_localhost:, allow_local_network:) return if allow_local_network && allow_localhost unless allow_localhost validate_localhost(address_info) validate_loopback(address_info) end unless allow_local_network validate_local_network(address_info) validate_link_local(address_info) end end 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_scheme(scheme, schemes) if scheme.blank? || (schemes.any? && !schemes.include?(scheme)) raise BlockedUrlError, "Only allowed schemes are #{schemes.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 domain_whitelisted?(uri) Gitlab::UrlBlockers::UrlWhitelist.domain_whitelisted?(uri.normalized_host, port: get_port(uri)) end def ip_whitelisted?(ip_address, port: nil) Gitlab::UrlBlockers::UrlWhitelist.ip_whitelisted?(ip_address, port: port) end def config Gitlab.config end end end end