package tlsutil import ( "crypto/tls" "crypto/x509" "fmt" "log" "net" "strings" "sync" "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{ "": tls.VersionTLS10, // default in golang "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 // VerifyIncomingRPC is used to verify the authenticity of incoming RPC // 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. VerifyIncomingRPC bool // VerifyIncomingHTTPS is used to verify the authenticity of incoming // HTTPS 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. VerifyIncomingHTTPS 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 // EnableAgentTLSForChecks is used to apply the agent's TLS settings in // order to configure the HTTP client used for health checks. Enabling // this allows HTTP checks to present a client certificate and verify // the server using the same TLS configuration as the agent (CA, cert, // and key). EnableAgentTLSForChecks bool } // KeyPair is used to open and parse a certificate and key file func (c *Config) KeyPair() (*tls.Certificate, error) { return loadKeyPair(c.CertFile, c.KeyFile) } // 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) } } // Configurator holds a Config and is responsible for generating all the // *tls.Config necessary for Consul. Except the one in the api package. type Configurator struct { sync.RWMutex base *Config cert *tls.Certificate cas *x509.CertPool logger *log.Logger version int } // NewConfigurator creates a new Configurator and sets the provided // configuration. func NewConfigurator(config Config, logger *log.Logger) (*Configurator, error) { c := &Configurator{logger: logger} err := c.Update(config) if err != nil { return nil, err } return c, nil } // Update updates the internal configuration which is used to generate // *tls.Config. // This function acquires a write lock because it writes the new config. func (c *Configurator) Update(config Config) error { cert, err := loadKeyPair(config.CertFile, config.KeyFile) if err != nil { return err } cas, err := loadCAs(config.CAFile, config.CAPath) if err != nil { return err } if err = c.check(config, cas, cert); err != nil { return err } c.Lock() c.base = &config c.cert = cert c.cas = cas c.version++ c.Unlock() c.log("Update") return nil } func (c *Configurator) check(config Config, cas *x509.CertPool, cert *tls.Certificate) error { // Check if a minimum TLS version was set if config.TLSMinVersion != "" { if _, ok := TLSLookup[config.TLSMinVersion]; !ok { return fmt.Errorf("TLSMinVersion: value %s not supported, please specify one of [tls10,tls11,tls12]", config.TLSMinVersion) } } // Ensure we have a CA if VerifyOutgoing is set if config.VerifyOutgoing && cas == nil { return fmt.Errorf("VerifyOutgoing set, and no CA certificate provided!") } // Ensure we have a CA and cert if VerifyIncoming is set if config.VerifyIncoming || config.VerifyIncomingRPC || config.VerifyIncomingHTTPS { if cas == nil { return fmt.Errorf("VerifyIncoming set, and no CA certificate provided!") } if cert == nil { return fmt.Errorf("VerifyIncoming set, and no Cert/Key pair provided!") } } return nil } func loadKeyPair(certFile, keyFile string) (*tls.Certificate, error) { if certFile == "" || keyFile == "" { return nil, nil } cert, err := tls.LoadX509KeyPair(certFile, keyFile) if err != nil { return nil, fmt.Errorf("Failed to load cert/key pair: %v", err) } return &cert, nil } func loadCAs(caFile, caPath string) (*x509.CertPool, error) { if caFile != "" { return rootcerts.LoadCAFile(caFile) } else if caPath != "" { pool, err := rootcerts.LoadCAPath(caPath) if err != nil { return nil, err } // make sure to not return an empty pool because this is not // the users intention when providing a path for CAs. if len(pool.Subjects()) == 0 { return nil, fmt.Errorf("Error loading CA: path %q has no CAs", caPath) } return pool, nil } return nil, nil } // commonTLSConfig generates a *tls.Config from the base configuration the // Configurator has. It accepts an additional flag in case a config is needed // for incoming TLS connections. // This function acquires a read lock because it reads from the config. func (c *Configurator) commonTLSConfig(additionalVerifyIncomingFlag bool) *tls.Config { c.RLock() defer c.RUnlock() tlsConfig := &tls.Config{ InsecureSkipVerify: !c.base.VerifyServerHostname, } // Set the cipher suites if len(c.base.CipherSuites) != 0 { tlsConfig.CipherSuites = c.base.CipherSuites } tlsConfig.PreferServerCipherSuites = c.base.PreferServerCipherSuites tlsConfig.GetCertificate = func(*tls.ClientHelloInfo) (*tls.Certificate, error) { return c.cert, nil } tlsConfig.GetClientCertificate = func(*tls.CertificateRequestInfo) (*tls.Certificate, error) { return c.cert, nil } tlsConfig.ClientCAs = c.cas tlsConfig.RootCAs = c.cas // This is possible because TLSLookup also contains "" with golang's // default (tls10). And because the initial check makes sure the // version correctly matches. tlsConfig.MinVersion = TLSLookup[c.base.TLSMinVersion] // Set ClientAuth if necessary if c.base.VerifyIncoming || additionalVerifyIncomingFlag { tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert } return tlsConfig } // This function acquires a read lock because it reads from the config. func (c *Configurator) outgoingRPCTLSDisabled() bool { c.RLock() defer c.RUnlock() return c.cas == nil && !c.base.VerifyOutgoing } // This function acquires a read lock because it reads from the config. func (c *Configurator) someValuesFromConfig() (bool, bool, string) { c.RLock() defer c.RUnlock() return c.base.VerifyServerHostname, c.base.VerifyOutgoing, c.base.Domain } // This function acquires a read lock because it reads from the config. func (c *Configurator) verifyIncomingRPC() bool { c.RLock() defer c.RUnlock() return c.base.VerifyIncomingRPC } // This function acquires a read lock because it reads from the config. func (c *Configurator) verifyIncomingHTTPS() bool { c.RLock() defer c.RUnlock() return c.base.VerifyIncomingHTTPS } // This function acquires a read lock because it reads from the config. func (c *Configurator) enableAgentTLSForChecks() bool { c.RLock() defer c.RUnlock() return c.base.EnableAgentTLSForChecks } // This function acquires a read lock because it reads from the config. func (c *Configurator) serverNameOrNodeName() string { c.RLock() defer c.RUnlock() if c.base.ServerName != "" { return c.base.ServerName } return c.base.NodeName } // IncomingRPCConfig generates a *tls.Config for incoming RPC connections. func (c *Configurator) IncomingRPCConfig() *tls.Config { c.log("IncomingRPCConfig") config := c.commonTLSConfig(c.verifyIncomingRPC()) config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingRPCConfig(), nil } return config } // IncomingHTTPSConfig generates a *tls.Config for incoming HTTPS connections. func (c *Configurator) IncomingHTTPSConfig() *tls.Config { c.log("IncomingHTTPSConfig") config := c.commonTLSConfig(c.verifyIncomingHTTPS()) config.NextProtos = []string{"h2", "http/1.1"} config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingHTTPSConfig(), nil } return config } // IncomingTLSConfig generates a *tls.Config for outgoing TLS connections for // checks. This function is separated because there is an extra flag to // consider for checks. EnableAgentTLSForChecks and InsecureSkipVerify has to // be checked for checks. func (c *Configurator) OutgoingTLSConfigForCheck(skipVerify bool) *tls.Config { c.log("OutgoingTLSConfigForCheck") if !c.enableAgentTLSForChecks() { return &tls.Config{ InsecureSkipVerify: skipVerify, } } config := c.commonTLSConfig(false) config.InsecureSkipVerify = skipVerify config.ServerName = c.serverNameOrNodeName() return config } // OutgoingRPCConfig generates a *tls.Config for outgoing RPC connections. If // there is a CA or VerifyOutgoing is set, a *tls.Config will be provided, // otherwise we assume that no TLS should be used. func (c *Configurator) OutgoingRPCConfig() *tls.Config { c.log("OutgoingRPCConfig") if c.outgoingRPCTLSDisabled() { return nil } return c.commonTLSConfig(false) } // OutgoingRPCWrapper wraps the result of OutgoingRPCConfig in a DCWrapper. It // decides if verify server hostname should be used. func (c *Configurator) OutgoingRPCWrapper() DCWrapper { c.log("OutgoingRPCWrapper") if c.outgoingRPCTLSDisabled() { return nil } // Generate the wrapper based on dc return func(dc string, conn net.Conn) (net.Conn, error) { return c.wrapTLSClient(dc, conn) } } // This function acquires a read lock because it reads from the config. func (c *Configurator) log(name string) { if c.logger != nil { c.RLock() defer c.RUnlock() c.logger.Printf("[DEBUG] tlsutil: %s with version %d", name, c.version) } } // 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 *Configurator) wrapTLSClient(dc string, conn net.Conn) (net.Conn, error) { var err error var tlsConn *tls.Conn config := c.OutgoingRPCConfig() verifyServerHostname, verifyOutgoing, domain := c.someValuesFromConfig() if verifyServerHostname { // Strip the trailing '.' from the domain if any domain = strings.TrimSuffix(domain, ".") config.ServerName = "server." + dc + "." + domain } tlsConn = tls.Client(conn, config) // If crypto/tls is doing verification, there's no need to do // our own. if !config.InsecureSkipVerify { return tlsConn, nil } // If verification is not turned on, don't do it. if !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: config.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 } // 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 }