Permalink
Switch branches/tags
Find file Copy path
397 lines (341 sloc) 12.3 KB
package tlsutil
import (
"crypto/tls"
"crypto/x509"
"fmt"
"io/ioutil"
"net"
"strings"
"time"
"github.com/hashicorp/go-rootcerts"
)
// DCWrapper is a function that is used to wrap a non-TLS connection
// and returns an appropriate TLS connection or error. This takes
// a datacenter as an argument.
type DCWrapper func(dc string, conn net.Conn) (net.Conn, error)
// Wrapper is a variant of DCWrapper, where the DC is provided as
// a constant value. This is usually done by currying DCWrapper.
type Wrapper func(conn net.Conn) (net.Conn, error)
// TLSLookup maps the tls_min_version configuration to the internal value
var TLSLookup = map[string]uint16{
"tls10": tls.VersionTLS10,
"tls11": tls.VersionTLS11,
"tls12": tls.VersionTLS12,
}
// Config used to create tls.Config
type Config struct {
// VerifyIncoming is used to verify the authenticity of incoming connections.
// This means that TCP requests are forbidden, only allowing for TLS. TLS connections
// must match a provided certificate authority. This can be used to force client auth.
VerifyIncoming bool
// VerifyOutgoing is used to verify the authenticity of outgoing connections.
// This means that TLS requests are used, and TCP requests are not made. TLS connections
// must match a provided certificate authority. This is used to verify authenticity of
// server nodes.
VerifyOutgoing bool
// VerifyServerHostname is used to enable hostname verification of servers. This
// ensures that the certificate presented is valid for server.<datacenter>.<domain>.
// This prevents a compromised client from being restarted as a server, and then
// intercepting request traffic as well as being added as a raft peer. This should be
// enabled by default with VerifyOutgoing, but for legacy reasons we cannot break
// existing clients.
VerifyServerHostname bool
// UseTLS is used to enable outgoing TLS connections to Consul servers.
UseTLS bool
// CAFile is a path to a certificate authority file. This is used with VerifyIncoming
// or VerifyOutgoing to verify the TLS connection.
CAFile string
// CAPath is a path to a directory containing certificate authority files. This is used
// with VerifyIncoming or VerifyOutgoing to verify the TLS connection.
CAPath string
// CertFile is used to provide a TLS certificate that is used for serving TLS connections.
// Must be provided to serve TLS connections.
CertFile string
// KeyFile is used to provide a TLS key that is used for serving TLS connections.
// Must be provided to serve TLS connections.
KeyFile string
// Node name is the name we use to advertise. Defaults to hostname.
NodeName string
// ServerName is used with the TLS certificate to ensure the name we
// provide matches the certificate
ServerName string
// Domain is the Consul TLD being used. Defaults to "consul."
Domain string
// TLSMinVersion is the minimum accepted TLS version that can be used.
TLSMinVersion string
// CipherSuites is the list of TLS cipher suites to use.
CipherSuites []uint16
// PreferServerCipherSuites specifies whether to prefer the server's ciphersuite
// over the client ciphersuites.
PreferServerCipherSuites bool
}
// AppendCA opens and parses the CA file and adds the certificates to
// the provided CertPool.
func (c *Config) AppendCA(pool *x509.CertPool) error {
if c.CAFile == "" {
return nil
}
// Read the file
data, err := ioutil.ReadFile(c.CAFile)
if err != nil {
return fmt.Errorf("Failed to read CA file: %v", err)
}
if !pool.AppendCertsFromPEM(data) {
return fmt.Errorf("Failed to parse any CA certificates")
}
return nil
}
// KeyPair is used to open and parse a certificate and key file
func (c *Config) KeyPair() (*tls.Certificate, error) {
if c.CertFile == "" || c.KeyFile == "" {
return nil, nil
}
cert, err := tls.LoadX509KeyPair(c.CertFile, c.KeyFile)
if err != nil {
return nil, fmt.Errorf("Failed to load cert/key pair: %v", err)
}
return &cert, err
}
// OutgoingTLSConfig generates a TLS configuration for outgoing
// requests. It will return a nil config if this configuration should
// not use TLS for outgoing connections.
func (c *Config) OutgoingTLSConfig() (*tls.Config, error) {
// If VerifyServerHostname is true, that implies VerifyOutgoing
if c.VerifyServerHostname {
c.VerifyOutgoing = true
}
if !c.UseTLS && !c.VerifyOutgoing {
return nil, nil
}
// Create the tlsConfig
tlsConfig := &tls.Config{
RootCAs: x509.NewCertPool(),
InsecureSkipVerify: true,
}
if c.ServerName != "" {
tlsConfig.ServerName = c.ServerName
tlsConfig.InsecureSkipVerify = false
}
if c.VerifyServerHostname {
// ServerName is filled in dynamically based on the target DC
tlsConfig.ServerName = "VerifyServerHostname"
tlsConfig.InsecureSkipVerify = false
}
if len(c.CipherSuites) != 0 {
tlsConfig.CipherSuites = c.CipherSuites
}
if c.PreferServerCipherSuites {
tlsConfig.PreferServerCipherSuites = true
}
// Ensure we have a CA if VerifyOutgoing is set
if c.VerifyOutgoing && c.CAFile == "" && c.CAPath == "" {
return nil, fmt.Errorf("VerifyOutgoing set, and no CA certificate provided!")
}
// Parse the CA certs if any
rootConfig := &rootcerts.Config{
CAFile: c.CAFile,
CAPath: c.CAPath,
}
if err := rootcerts.ConfigureTLS(tlsConfig, rootConfig); err != nil {
return nil, err
}
// Add cert/key
cert, err := c.KeyPair()
if err != nil {
return nil, err
} else if cert != nil {
tlsConfig.Certificates = []tls.Certificate{*cert}
}
// Check if a minimum TLS version was set
if c.TLSMinVersion != "" {
tlsvers, ok := TLSLookup[c.TLSMinVersion]
if !ok {
return nil, fmt.Errorf("TLSMinVersion: value %s not supported, please specify one of [tls10,tls11,tls12]", c.TLSMinVersion)
}
tlsConfig.MinVersion = tlsvers
}
return tlsConfig, nil
}
// OutgoingTLSWrapper returns a a DCWrapper based on the OutgoingTLS
// configuration. If hostname verification is on, the wrapper
// will properly generate the dynamic server name for verification.
func (c *Config) OutgoingTLSWrapper() (DCWrapper, error) {
// Get the TLS config
tlsConfig, err := c.OutgoingTLSConfig()
if err != nil {
return nil, err
}
// Check if TLS is not enabled
if tlsConfig == nil {
return nil, nil
}
// Strip the trailing '.' from the domain if any
domain := strings.TrimSuffix(c.Domain, ".")
wrapper := func(dc string, c net.Conn) (net.Conn, error) {
return WrapTLSClient(c, tlsConfig)
}
// Generate the wrapper based on hostname verification
if c.VerifyServerHostname {
wrapper = func(dc string, conn net.Conn) (net.Conn, error) {
conf := tlsConfig.Clone()
conf.ServerName = "server." + dc + "." + domain
return WrapTLSClient(conn, conf)
}
}
return wrapper, nil
}
// SpecificDC is used to invoke a static datacenter
// and turns a DCWrapper into a Wrapper type.
func SpecificDC(dc string, tlsWrap DCWrapper) Wrapper {
if tlsWrap == nil {
return nil
}
return func(conn net.Conn) (net.Conn, error) {
return tlsWrap(dc, conn)
}
}
// Wrap a net.Conn into a client tls connection, performing any
// additional verification as needed.
//
// As of go 1.3, crypto/tls only supports either doing no certificate
// verification, or doing full verification including of the peer's
// DNS name. For consul, we want to validate that the certificate is
// signed by a known CA, but because consul doesn't use DNS names for
// node names, we don't verify the certificate DNS names. Since go 1.3
// no longer supports this mode of operation, we have to do it
// manually.
func WrapTLSClient(conn net.Conn, tlsConfig *tls.Config) (net.Conn, error) {
var err error
var tlsConn *tls.Conn
tlsConn = tls.Client(conn, tlsConfig)
// If crypto/tls is doing verification, there's no need to do
// our own.
if tlsConfig.InsecureSkipVerify == false {
return tlsConn, nil
}
if err = tlsConn.Handshake(); err != nil {
tlsConn.Close()
return nil, err
}
// The following is lightly-modified from the doFullHandshake
// method in crypto/tls's handshake_client.go.
opts := x509.VerifyOptions{
Roots: tlsConfig.RootCAs,
CurrentTime: time.Now(),
DNSName: "",
Intermediates: x509.NewCertPool(),
}
certs := tlsConn.ConnectionState().PeerCertificates
for i, cert := range certs {
if i == 0 {
continue
}
opts.Intermediates.AddCert(cert)
}
_, err = certs[0].Verify(opts)
if err != nil {
tlsConn.Close()
return nil, err
}
return tlsConn, err
}
// IncomingTLSConfig generates a TLS configuration for incoming requests
func (c *Config) IncomingTLSConfig() (*tls.Config, error) {
// Create the tlsConfig
tlsConfig := &tls.Config{
ServerName: c.ServerName,
ClientCAs: x509.NewCertPool(),
ClientAuth: tls.NoClientCert,
}
if tlsConfig.ServerName == "" {
tlsConfig.ServerName = c.NodeName
}
// Set the cipher suites
if len(c.CipherSuites) != 0 {
tlsConfig.CipherSuites = c.CipherSuites
}
if c.PreferServerCipherSuites {
tlsConfig.PreferServerCipherSuites = true
}
// Parse the CA certs if any
if c.CAFile != "" {
pool, err := rootcerts.LoadCAFile(c.CAFile)
if err != nil {
return nil, err
}
tlsConfig.ClientCAs = pool
} else if c.CAPath != "" {
pool, err := rootcerts.LoadCAPath(c.CAPath)
if err != nil {
return nil, err
}
tlsConfig.ClientCAs = pool
}
// Add cert/key
cert, err := c.KeyPair()
if err != nil {
return nil, err
} else if cert != nil {
tlsConfig.Certificates = []tls.Certificate{*cert}
}
// Check if we require verification
if c.VerifyIncoming {
tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
if c.CAFile == "" && c.CAPath == "" {
return nil, fmt.Errorf("VerifyIncoming set, and no CA certificate provided!")
}
if cert == nil {
return nil, fmt.Errorf("VerifyIncoming set, and no Cert/Key pair provided!")
}
}
// Check if a minimum TLS version was set
if c.TLSMinVersion != "" {
tlsvers, ok := TLSLookup[c.TLSMinVersion]
if !ok {
return nil, fmt.Errorf("TLSMinVersion: value %s not supported, please specify one of [tls10,tls11,tls12]", c.TLSMinVersion)
}
tlsConfig.MinVersion = tlsvers
}
return tlsConfig, nil
}
// ParseCiphers parse ciphersuites from the comma-separated string into recognized slice
func ParseCiphers(cipherStr string) ([]uint16, error) {
suites := []uint16{}
cipherStr = strings.TrimSpace(cipherStr)
if cipherStr == "" {
return []uint16{}, nil
}
ciphers := strings.Split(cipherStr, ",")
cipherMap := map[string]uint16{
"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305": tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
"TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305": tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256": tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
"TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384": tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384": tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256": tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA": tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA": tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA": tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA": tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
"TLS_RSA_WITH_AES_128_GCM_SHA256": tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
"TLS_RSA_WITH_AES_256_GCM_SHA384": tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
"TLS_RSA_WITH_AES_128_CBC_SHA256": tls.TLS_RSA_WITH_AES_128_CBC_SHA256,
"TLS_RSA_WITH_AES_128_CBC_SHA": tls.TLS_RSA_WITH_AES_128_CBC_SHA,
"TLS_RSA_WITH_AES_256_CBC_SHA": tls.TLS_RSA_WITH_AES_256_CBC_SHA,
"TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA": tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
"TLS_RSA_WITH_3DES_EDE_CBC_SHA": tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
"TLS_RSA_WITH_RC4_128_SHA": tls.TLS_RSA_WITH_RC4_128_SHA,
"TLS_ECDHE_RSA_WITH_RC4_128_SHA": tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
"TLS_ECDHE_ECDSA_WITH_RC4_128_SHA": tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
}
for _, cipher := range ciphers {
if v, ok := cipherMap[cipher]; ok {
suites = append(suites, v)
} else {
return suites, fmt.Errorf("unsupported cipher %q", cipher)
}
}
return suites, nil
}