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require 'socket'
require 'openssl'
module CryptCheck
module Tls
module Engine
SLOW_DOWN = ENV.fetch('SLOW_DOWN', '0').to_i
TCP_TIMEOUT = 10
TLS_TIMEOUT = 2 * TCP_TIMEOUT
class TLSException < ::StandardError
end
class TLSNotAvailableException < TLSException
def to_s
'TLS seems not supported on this server'
end
end
class MethodNotAvailable < TLSException
end
class CipherNotAvailable < TLSException
end
class InappropriateFallback < TLSException
end
class Timeout < ::StandardError
def initialize(ip, port)
@message = "Timeout when connecting to #{ip}:#{port} (max #{TCP_TIMEOUT.humanize})"
end
def to_s
@message
end
end
class TLSTimeout < Timeout
def initialize(ip, port)
@message = "Timeout when TLS connecting to #{ip}:#{port} (max #{TLS_TIMEOUT.humanize})"
end
end
class ConnectionError < ::StandardError
end
attr_reader :hostname, :ip, :family, :port, :certs, :keys, :dh,
:supported_methods, :supported_ciphers,
:supported_curves, :curves_preference
def initialize(hostname, ip, family, port)
@hostname, @ip, @family, @port = hostname, ip, family, port
@dh = []
@name = "#@ip:#@port"
@name += " [#@hostname]" if @hostname
Logger.info { @name.colorize :blue }
fetch_supported_methods
fetch_supported_ciphers
fetch_dh
fetch_ciphers_preferences
fetch_ecdsa_certs
fetch_supported_curves
fetch_curves_preference
check_fallback_scsv
verify_certs
end
def supported_method?(method)
ssl_client method
Logger.info { " Method #{method}" }
true
rescue TLSException
Logger.debug { " Method #{method} : not supported" }
false
rescue TLSTimeout
raise if ENV['BUG_METHOD_UNSUPPORTED_TIMEOUT'].nil?
end
def fetch_supported_methods
Logger.info { '' }
Logger.info { 'Supported methods' }
@supported_methods = Method.select { |m| supported_method? m }
raise TLSNotAvailableException if @supported_methods.empty?
end
def supported_cipher?(method, cipher)
connection = ssl_client method, cipher
Logger.info { " Cipher #{cipher}" }
dh = connection.tmp_key
if dh
Logger.info { " PFS : #{dh}" }
end
connection
rescue TLSException
Logger.debug { " Cipher #{cipher} : not supported" }
nil
end
def fetch_supported_ciphers
Logger.info { '' }
Logger.info { 'Supported ciphers' }
@supported_ciphers = @supported_methods.collect do |method|
ciphers = Cipher[method].collect do |cipher|
connection = supported_cipher? method, cipher
next nil unless connection
[cipher, connection]
end.compact.to_h
[method, ciphers]
end.to_h
end
def fetch_ciphers_preferences
Logger.info { '' }
Logger.info { 'Cipher suite preferences' }
@preferences = @supported_ciphers.collect do |method, ciphers|
ciphers = ciphers.keys
preferences = if ciphers.size < 2
Logger.info { " #{method} : " + 'not applicable'.colorize(:unknown) }
nil
else
a, b, _ = ciphers
ab = ssl_client(method, [a, b]).cipher.first
ba = ssl_client(method, [b, a]).cipher.first
if ab != ba
Logger.info { " #{method} : " + 'client preference'.colorize(:warning) }
:client
else
sort = -> (a, b) do
connection = ssl_client method, [a, b]
cipher = connection.cipher.first
cipher == a.name ? -1 : 1
end
preferences = ciphers.sort &sort
Logger.info { " #{method} : " + preferences.collect { |c| c.to_s :short }.join(', ') }
preferences
end
end
[method, preferences]
end.to_h
end
def fetch_dh
@dh = @supported_ciphers.collect do |_, ciphers|
ciphers.values.collect(&:tmp_key).select { |d| d.is_a? OpenSSL::PKey::DH }
end.flatten.uniq &:fingerprint
end
def fetch_ecdsa_certs
@ecdsa_certs = {}
@supported_ciphers.each do |method, ciphers|
ecdsa = ciphers.keys.detect &:ecdsa?
next unless ecdsa
ecdsa_curve = Curve.new ciphers[ecdsa].tmp_key.curve
@ecdsa_certs = Curve.collect do |curve|
begin
connection = ssl_client method, ecdsa, curves: [curve, ecdsa_curve]
[curve, connection]
rescue TLSException
nil
end
end.compact.to_h
break
end
end
def fetch_supported_curves
Logger.info { '' }
Logger.info { 'Supported elliptic curves' }
@supported_curves = []
ecdsa_curve = @ecdsa_certs.keys.first
if ecdsa_curve
# If we have an ECDSA cipher, we need at least the certificate curve to do handshake,
# but with lowest priority to check for ECHDE and not just ECDSA
@supported_ciphers.each do |method, ciphers|
ecdsa = ciphers.keys.detect &:ecdsa?
next unless ecdsa
@supported_curves = Curve.select do |curve|
if curve == ecdsa_curve
# ECDSA curve is always supported
Logger.info { " ECC curve #{curve.name}" }
next true
end
begin
connection = ssl_client method, ecdsa, curves: [curve, ecdsa_curve]
# Not too fast !!!
# Handshake will **always** succeed, because ECDSA
# curve is always supported.
# So, we need to test for the real curve!
# Treaky case : if server preference is enforced,
# ECDSA curve can be prefered over ECDHE one and so
# really supported curve can be detected as not supported :(
dh = connection.tmp_key
negociated_curve = dh.curve
supported = ecdsa_curve != negociated_curve
if supported
Logger.info { " ECC curve #{curve.name}" }
else
Logger.debug { " ECC curve #{curve.name} : not supported" }
end
supported
rescue TLSException
false
end
end
break
end
else
# If we have no ECDSA ciphers, ECC supported are only ECDH ones
# So peak an ECDH cipher and test all curves
@supported_ciphers.each do |method, ciphers|
ecdh = ciphers.keys.detect { |c| c.ecdh? or c.ecdhe? }
next unless ecdh
@supported_curves = Curve.select do |curve|
begin
ssl_client method, ecdh, curves: curve
Logger.info { " ECC curve #{curve.name}" }
true
rescue TLSException
Logger.debug { " ECC curve #{curve.name} : not supported" }
false
end
end
break
end
end
end
def fetch_curves_preference
@curves_preference = if @supported_curves.size < 2
Logger.info { 'Curves preference : ' + 'not applicable'.colorize(:unknown) }
nil
else
method, cipher = @supported_ciphers.collect do |method, ciphers|
cipher = ciphers.keys.detect { |c| c.ecdh? or c.ecdhe? }
[method, cipher]
end.detect { |n| !n.nil? }
a, b, _ = @supported_curves
ab, ba = [a, b], [b, a]
if cipher.ecdsa?
# In case of ECDSA, add the cert key at the end
# Or no negociation possible
ecdsa_curve = @ecdsa_certs.keys.first
ab << ecdsa_curve
ba << ecdsa_curve
end
ab = ssl_client(method, cipher, curves: ab).tmp_key.curve
ba = ssl_client(method, cipher, curves: ba).tmp_key.curve
if ab != ba
Logger.info { 'Curves preference : ' + 'client preference'.colorize(:warning) }
:client
else
sort = lambda do |a, b|
curves = [a, b]
if cipher.ecdsa?
# In case of ECDSA, add the cert key at the end
# Or no negociation possible
curves << ecdsa_curve
end
connection = ssl_client method, cipher, curves: curves
curve = connection.tmp_key.curve
a == curve ? -1 : 1
end
preferences = @supported_curves.sort &sort
Logger.info { 'Curves preference : ' + preferences.collect { |c| c.name }.join(', ') }
preferences
end
end
end
def check_fallback_scsv
Logger.info { '' }
@fallback_scsv = false
if @supported_methods.size > 1
# We will try to connect to the not better supported method
method = @supported_methods[1]
begin
ssl_client method, fallback: true
rescue InappropriateFallback,
CipherNotAvailable, # Seems some servers reply with "sslv3 alert handshake failure"…
MethodNotAvailable, # Seems some servers reply with "wrong version number"…
@fallback_scsv = true
end
else
@fallback_scsv = nil
end
text, color = case @fallback_scsv
when true
['supported', :good]
when false
['not supported', :error]
when nil
['not applicable', :unknown]
end
Logger.info { 'Fallback SCSV : ' + text.colorize(color) }
end
Method.each do |method|
class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{method.to_sym.downcase}?
@supported_methods.detect { |m| m == :#{method.to_sym} }
end
RUBY_EVAL
end
Cipher::TYPES.each do |type, _|
class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{type}?
uniq_supported_ciphers.any? { |c| c.#{type}? }
end
RUBY_EVAL
end
private
def connect(&block)
socket = ::Socket.new @family, sock_type
sockaddr = ::Socket.sockaddr_in @port, @ip
#Logger.trace { "Connecting to #{@ip}:#{@port}" }
begin
status = socket.connect_nonblock sockaddr
#Logger.trace { "Connecting to #{@ip}:#{@port} status : #{status}" }
raise ConnectionError, status unless status == 0
#Logger.trace { "Connected to #{@ip}:#{@port}" }
block_given? ? block.call(socket) : nil
rescue ::IO::WaitReadable
#Logger.trace { "Waiting for read to #{@ip}:#{@port}" }
raise Timeout.new(@ip, @port) unless IO.select [socket], nil, nil, TCP_TIMEOUT
retry
rescue ::IO::WaitWritable
#Logger.trace { "Waiting for write to #{@ip}:#{@port}" }
raise Timeout.new(@ip, @port) unless IO.select nil, [socket], nil, TCP_TIMEOUT
retry
rescue Errno::ECONNREFUSED => e
raise ConnectionError, e
ensure
socket.close
end
end
def ssl_connect(socket, context, method, &block)
ssl_socket = ::OpenSSL::SSL::SSLSocket.new socket, context
ssl_socket.hostname = @hostname if @hostname and method != :SSLv2
#Logger.trace { "SSL connecting to #{name}" }
begin
ssl_socket.connect_nonblock
#Logger.trace { "SSL connected to #{name}" }
return block_given? ? block.call(ssl_socket) : nil
rescue ::OpenSSL::SSL::SSLErrorWaitReadable
#Logger.trace { "Waiting for SSL read to #{name}" }
raise TLSTimeout.new(@ip, @port) unless IO.select [ssl_socket], nil, nil, TLS_TIMEOUT
retry
rescue ::OpenSSL::SSL::SSLErrorWaitWritable
#Logger.trace { "Waiting for SSL write to #{name}" }
raise TLSTimeout.new(@ip, @port) unless IO.select nil, [ssl_socket], nil, TLS_TIMEOUT
retry
rescue ::OpenSSL::SSL::SSLError => e
case e.message
when /state=SSLv2 read server hello A$/,
/state=SSLv3 read server hello A$/,
/state=SSLv3 read server hello A: wrong version number$/,
/state=SSLv3 read server hello A: tlsv1 alert protocol version$/,
/state=SSLv3 read server key exchange A: sslv3 alert handshake failure$/
raise MethodNotAvailable, e
when /state=SSLv2 read server hello A: peer error no cipher$/,
/state=error: no ciphers available$/,
/state=SSLv3 read server hello A: sslv3 alert handshake failure$/,
/state=error: missing export tmp dh key$/,
/state=error: wrong curve$/
raise CipherNotAvailable, e
when /state=SSLv3 read server hello A: tlsv1 alert inappropriate fallback$/
raise InappropriateFallback, e
end
raise
rescue ::SystemCallError => e
case e.message
when /^Connection reset by peer - SSL_connect$/
raise TLSNotAvailableException, e
end
raise
ensure
ssl_socket.close
end
end
def ssl_client(method, ciphers = nil, curves: nil, fallback: false, &block)
sleep SLOW_DOWN if SLOW_DOWN > 0
ssl_context = ::OpenSSL::SSL::SSLContext.new method.to_sym
ssl_context.enable_fallback_scsv if fallback
if ciphers
ciphers = [ciphers] unless ciphers.is_a? Enumerable
ciphers = ciphers.collect(&:name).join ':'
else
ciphers = Cipher::ALL
end
ssl_context.ciphers = ciphers
if curves
curves = [curves] unless curves.is_a? Enumerable
# OpenSSL fails if the same curve is selected multiple times
# So because Array#uniq preserves order, remove the less prefered ones
curves = curves.collect(&:name).uniq.join ':'
ssl_context.ecdh_curves = curves
end
Logger.trace { "Try method=#{method} / ciphers=#{ciphers} / curves=#{curves} / scsv=#{fallback}" }
begin
connect do |socket|
ssl_connect socket, ssl_context, method do |ssl_socket|
return block_given? ? block.call(ssl_socket) : ssl_socket
end
end
rescue => e
Logger.trace { "Error occurs : #{e}" }
raise
end
end
def verify_certs
Logger.info { '' }
Logger.info { 'Certificates' }
# Let's begin the fun
# First, collect "standard" connections
# { method => { cipher => connection, ... }, ... }
certs = @supported_ciphers.values.collect(&:values).flatten 1
# Then, collect "ecdsa" connections
# { curve => connection, ... }
certs += @ecdsa_certs.values
# For anonymous cipher, there is no certificate at all
certs = certs.reject { |c| c.peer_cert.nil? }
# Then, fetch cert
certs = certs.collect { |c| Cert.new c }
# Then, filter cert to keep uniq fingerprint
@certs = certs.uniq { |c| c.fingerprint }
@trusted = @valid = true
@certs.each do |cert|
key = cert.key
identity = cert.valid?(@hostname || @ip)
trust = cert.trusted?
Logger.info { " Certificate #{cert.subject} [#{cert.serial}] issued by #{cert.issuer}" }
Logger.info { ' Key : ' + Tls.key_to_s(key) }
if identity
Logger.info { ' Identity : ' + 'valid'.colorize(:good) }
else
Logger.info { ' Identity : ' + 'invalid'.colorize(:error) }
@valid = false
end
if trust == :trusted
Logger.info { ' Trust : ' + 'trusted'.colorize(:good) }
else
Logger.info { ' Trust : ' + 'untrusted'.colorize(:error) + ' - ' + trust }
@trusted = false
end
end
@keys = @certs.collect &:key
end
private
def uniq_supported_ciphers
@uniq_supported_ciphers ||= @supported_ciphers.values.collect(&:keys).flatten.uniq
end
end
end
end