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... // 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 } func (c *Config) skipBuiltinVerify() bool { return c.VerifyServerHostname == false && c.ServerName == "" } // 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 !c.UseTLS && !c.VerifyOutgoing { return nil, nil } // Create the tlsConfig tlsConfig := &tls.Config{ RootCAs: x509.NewCertPool(), InsecureSkipVerify: c.skipBuiltinVerify(), ServerName: c.ServerName, } 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 } // Generate the wrapper based on hostname verification wrapper := func(dc string, conn net.Conn) (net.Conn, error) { if c.VerifyServerHostname { // Strip the trailing '.' from the domain if any domain := strings.TrimSuffix(c.Domain, ".") tlsConfig = tlsConfig.Clone() tlsConfig.ServerName = "server." + dc + "." + domain } return c.wrapTLSClient(conn, tlsConfig) } 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 (c *Config) 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 verification is not turned on, don't do it. if !c.VerifyOutgoing { 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 }