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Split client and server cipher suite list in TLS defaults

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Per @ewindisch, removing the CBC ciphers from the client preferred TLS
cipher suites.  This will allow a future version of the server to also
remove the CBC ciphers from the accepted list.

This changes the server default to client + additional CBC cipher list,
and client default to the non-CBC ciphers.

Also, cipher order preference is modified so that best and highest-bit count
ciphers are most preferred.

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
This commit is contained in:
Phil Estes 2015-06-10 12:23:43 -04:00
parent 6c2626b90e
commit 0c0578b01b
1 changed files with 32 additions and 14 deletions
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46
tlsconfig/config.go
View file

@ -24,21 +24,39 @@ type Options struct {
KeyFile string
}
// Default is a secure-enough TLS configuration.
var Default = tls.Config{
// Extra (server-side) accepted CBC cipher suites - will phase out in the future
var acceptedCBCCiphers = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_RSA_WITH_AES_128_CBC_SHA,
}
// Client TLS cipher suites (dropping CBC ciphers for client preferred suite set)
var clientCipherSuites = []uint16{
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
}
// For use by code which already has a crypto/tls options struct but wants to
// use a commonly accepted set of TLS cipher suites, with known weak algorithms removed
var DefaultServerAcceptedCiphers = append(clientCipherSuites, acceptedCBCCiphers...)
// ServerDefault is a secure-enough TLS configuration for the server TLS configuration.
var ServerDefault = tls.Config{
// Avoid fallback to SSL protocols < TLS1.0
MinVersion: tls.VersionTLS10,
PreferServerCipherSuites: true,
CipherSuites: []uint16{
tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
tls.TLS_RSA_WITH_AES_128_CBC_SHA,
tls.TLS_RSA_WITH_AES_256_CBC_SHA,
},
CipherSuites: DefaultServerAcceptedCiphers,
}
// ClientDefault is a secure-enough TLS configuration for the client TLS configuration.
var ClientDefault = tls.Config{
// Prefer TLS1.2 as the client minimum
MinVersion: tls.VersionTLS12,
CipherSuites: clientCipherSuites,
}
// certPool returns an X.509 certificate pool from `caFile`, the certificate file.
@ -63,7 +81,7 @@ func certPool(caFile string) (*x509.CertPool, error) {
// Client returns a TLS configuration meant to be used by a client.
func Client(options Options) (*tls.Config, error) {
tlsConfig := Default
tlsConfig := ClientDefault
tlsConfig.InsecureSkipVerify = options.InsecureSkipVerify
if !options.InsecureSkipVerify {
CAs, err := certPool(options.CAFile)
@ -86,7 +104,7 @@ func Client(options Options) (*tls.Config, error) {
// Server returns a TLS configuration meant to be used by a server.
func Server(options Options) (*tls.Config, error) {
tlsConfig := Default
tlsConfig := ServerDefault
tlsConfig.ClientAuth = options.ClientAuth
tlsCert, err := tls.LoadX509KeyPair(options.CertFile, options.KeyFile)
if err != nil {