docker api

vendor/github.com/docker/go-connections/tlsconfig/config.go

@@ -0,0 +1,254 @@
+// Package tlsconfig provides primitives to retrieve secure-enough TLS configurations for both clients and servers.
+//
+// As a reminder from https://golang.org/pkg/crypto/tls/#Config:
+//	A Config structure is used to configure a TLS client or server. After one has been passed to a TLS function it must not be modified.
+//	A Config may be reused; the tls package will also not modify it.
+package tlsconfig
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/pkg/errors"
+)
+
+// Options represents the information needed to create client and server TLS configurations.
+type Options struct {
+	CAFile string
+
+	// If either CertFile or KeyFile is empty, Client() will not load them
+	// preventing the client from authenticating to the server.
+	// However, Server() requires them and will error out if they are empty.
+	CertFile string
+	KeyFile  string
+
+	// client-only option
+	InsecureSkipVerify bool
+	// server-only option
+	ClientAuth tls.ClientAuthType
+	// If ExclusiveRootPools is set, then if a CA file is provided, the root pool used for TLS
+	// creds will include exclusively the roots in that CA file.  If no CA file is provided,
+	// the system pool will be used.
+	ExclusiveRootPools bool
+	MinVersion         uint16
+	// If Passphrase is set, it will be used to decrypt a TLS private key
+	// if the key is encrypted
+	Passphrase string
+}
+
+// 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,
+}
+
+// DefaultServerAcceptedCiphers should be uses 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...)
+
+// allTLSVersions lists all the TLS versions and is used by the code that validates
+// a uint16 value as a TLS version.
+var allTLSVersions = map[uint16]struct{}{
+	tls.VersionSSL30: {},
+	tls.VersionTLS10: {},
+	tls.VersionTLS11: {},
+	tls.VersionTLS12: {},
+}
+
+// ServerDefault returns a secure-enough TLS configuration for the server TLS configuration.
+func ServerDefault(ops ...func(*tls.Config)) *tls.Config {
+	tlsconfig := &tls.Config{
+		// Avoid fallback by default to SSL protocols < TLS1.2
+		MinVersion:               tls.VersionTLS12,
+		PreferServerCipherSuites: true,
+		CipherSuites:             DefaultServerAcceptedCiphers,
+	}
+
+	for _, op := range ops {
+		op(tlsconfig)
+	}
+
+	return tlsconfig
+}
+
+// ClientDefault returns a secure-enough TLS configuration for the client TLS configuration.
+func ClientDefault(ops ...func(*tls.Config)) *tls.Config {
+	tlsconfig := &tls.Config{
+		// Prefer TLS1.2 as the client minimum
+		MinVersion:   tls.VersionTLS12,
+		CipherSuites: clientCipherSuites,
+	}
+
+	for _, op := range ops {
+		op(tlsconfig)
+	}
+
+	return tlsconfig
+}
+
+// certPool returns an X.509 certificate pool from `caFile`, the certificate file.
+func certPool(caFile string, exclusivePool bool) (*x509.CertPool, error) {
+	// If we should verify the server, we need to load a trusted ca
+	var (
+		certPool *x509.CertPool
+		err      error
+	)
+	if exclusivePool {
+		certPool = x509.NewCertPool()
+	} else {
+		certPool, err = SystemCertPool()
+		if err != nil {
+			return nil, fmt.Errorf("failed to read system certificates: %v", err)
+		}
+	}
+	pem, err := ioutil.ReadFile(caFile)
+	if err != nil {
+		return nil, fmt.Errorf("could not read CA certificate %q: %v", caFile, err)
+	}
+	if !certPool.AppendCertsFromPEM(pem) {
+		return nil, fmt.Errorf("failed to append certificates from PEM file: %q", caFile)
+	}
+	return certPool, nil
+}
+
+// isValidMinVersion checks that the input value is a valid tls minimum version
+func isValidMinVersion(version uint16) bool {
+	_, ok := allTLSVersions[version]
+	return ok
+}
+
+// adjustMinVersion sets the MinVersion on `config`, the input configuration.
+// It assumes the current MinVersion on the `config` is the lowest allowed.
+func adjustMinVersion(options Options, config *tls.Config) error {
+	if options.MinVersion > 0 {
+		if !isValidMinVersion(options.MinVersion) {
+			return fmt.Errorf("Invalid minimum TLS version: %x", options.MinVersion)
+		}
+		if options.MinVersion < config.MinVersion {
+			return fmt.Errorf("Requested minimum TLS version is too low. Should be at-least: %x", config.MinVersion)
+		}
+		config.MinVersion = options.MinVersion
+	}
+
+	return nil
+}
+
+// IsErrEncryptedKey returns true if the 'err' is an error of incorrect
+// password when tryin to decrypt a TLS private key
+func IsErrEncryptedKey(err error) bool {
+	return errors.Cause(err) == x509.IncorrectPasswordError
+}
+
+// getPrivateKey returns the private key in 'keyBytes', in PEM-encoded format.
+// If the private key is encrypted, 'passphrase' is used to decrypted the
+// private key.
+func getPrivateKey(keyBytes []byte, passphrase string) ([]byte, error) {
+	// this section makes some small changes to code from notary/tuf/utils/x509.go
+	pemBlock, _ := pem.Decode(keyBytes)
+	if pemBlock == nil {
+		return nil, fmt.Errorf("no valid private key found")
+	}
+
+	var err error
+	if x509.IsEncryptedPEMBlock(pemBlock) {
+		keyBytes, err = x509.DecryptPEMBlock(pemBlock, []byte(passphrase))
+		if err != nil {
+			return nil, errors.Wrap(err, "private key is encrypted, but could not decrypt it")
+		}
+		keyBytes = pem.EncodeToMemory(&pem.Block{Type: pemBlock.Type, Bytes: keyBytes})
+	}
+
+	return keyBytes, nil
+}
+
+// getCert returns a Certificate from the CertFile and KeyFile in 'options',
+// if the key is encrypted, the Passphrase in 'options' will be used to
+// decrypt it.
+func getCert(options Options) ([]tls.Certificate, error) {
+	if options.CertFile == "" && options.KeyFile == "" {
+		return nil, nil
+	}
+
+	errMessage := "Could not load X509 key pair"
+
+	cert, err := ioutil.ReadFile(options.CertFile)
+	if err != nil {
+		return nil, errors.Wrap(err, errMessage)
+	}
+
+	prKeyBytes, err := ioutil.ReadFile(options.KeyFile)
+	if err != nil {
+		return nil, errors.Wrap(err, errMessage)
+	}
+
+	prKeyBytes, err = getPrivateKey(prKeyBytes, options.Passphrase)
+	if err != nil {
+		return nil, errors.Wrap(err, errMessage)
+	}
+
+	tlsCert, err := tls.X509KeyPair(cert, prKeyBytes)
+	if err != nil {
+		return nil, errors.Wrap(err, errMessage)
+	}
+
+	return []tls.Certificate{tlsCert}, nil
+}
+
+// Client returns a TLS configuration meant to be used by a client.
+func Client(options Options) (*tls.Config, error) {
+	tlsConfig := ClientDefault()
+	tlsConfig.InsecureSkipVerify = options.InsecureSkipVerify
+	if !options.InsecureSkipVerify && options.CAFile != "" {
+		CAs, err := certPool(options.CAFile, options.ExclusiveRootPools)
+		if err != nil {
+			return nil, err
+		}
+		tlsConfig.RootCAs = CAs
+	}
+
+	tlsCerts, err := getCert(options)
+	if err != nil {
+		return nil, err
+	}
+	tlsConfig.Certificates = tlsCerts
+
+	if err := adjustMinVersion(options, tlsConfig); err != nil {
+		return nil, err
+	}
+
+	return tlsConfig, nil
+}
+
+// Server returns a TLS configuration meant to be used by a server.
+func Server(options Options) (*tls.Config, error) {
+	tlsConfig := ServerDefault()
+	tlsConfig.ClientAuth = options.ClientAuth
+	tlsCert, err := tls.LoadX509KeyPair(options.CertFile, options.KeyFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, fmt.Errorf("Could not load X509 key pair (cert: %q, key: %q): %v", options.CertFile, options.KeyFile, err)
+		}
+		return nil, fmt.Errorf("Error reading X509 key pair (cert: %q, key: %q): %v. Make sure the key is not encrypted.", options.CertFile, options.KeyFile, err)
+	}
+	tlsConfig.Certificates = []tls.Certificate{tlsCert}
+	if options.ClientAuth >= tls.VerifyClientCertIfGiven && options.CAFile != "" {
+		CAs, err := certPool(options.CAFile, options.ExclusiveRootPools)
+		if err != nil {
+			return nil, err
+		}
+		tlsConfig.ClientCAs = CAs
+	}
+
+	if err := adjustMinVersion(options, tlsConfig); err != nil {
+		return nil, err
+	}
+
+	return tlsConfig, nil
+}