package tlsutil import ( "crypto/tls" "crypto/x509" "fmt" "io/ioutil" "net" "os" "path/filepath" "sort" "strings" "sync" "sync/atomic" "time" "github.com/hashicorp/go-hclog" "github.com/hashicorp/go-multierror" "github.com/hashicorp/consul/logging" ) // ALPNWrapper is a function that is used to wrap a non-TLS connection and // returns an appropriate TLS connection or error. This taks a datacenter and // node name as argument to configure the desired SNI value and the desired // next proto for configuring ALPN. type ALPNWrapper func(dc, nodeName, alpnProto string, conn net.Conn) (net.Conn, error) // 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, "tls13": tls.VersionTLS13, } // 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 // 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 // AutoTLS opts the agent into provisioning agent // TLS certificates. AutoTLS bool } func tlsVersions() []string { versions := []string{} for v := range tlsLookup { if v != "" { versions = append(versions, v) } } sort.Strings(versions) return versions } // 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) } } // autoTLS stores configuration that is received from the auto-encrypt or // auto-config features. type autoTLS struct { extraCAPems []string connectCAPems []string cert *tls.Certificate verifyServerHostname bool } // manual stores the TLS CA and cert received from Configurator.Update which // generally comes from the agent configuration. type manual struct { caPems []string cert *tls.Certificate // caPool containing only the caPems. This CertPool should be used instead of // the Configurator.caPool when only the Agent TLS CA is allowed. caPool *x509.CertPool } // Configurator provides tls.Config and net.Dial wrappers to enable TLS for // clients and servers, for both HTTPS and RPC requests. // Configurator receives an initial TLS configuration from agent configuration, // and receives updates from config reloads, auto-encrypt, and auto-config. type Configurator struct { // version is increased each time the Configurator is updated. Must be accessed // using sync/atomic. Also MUST be the first field in this struct to ensure // 64-bit alignment. See https://golang.org/pkg/sync/atomic/#pkg-note-BUG. version uint64 // lock synchronizes access to all fields on this struct except for logger and version. lock sync.RWMutex base *Config autoTLS autoTLS manual manual caPool *x509.CertPool // peerDatacenterUseTLS is a map of DC name to a bool indicating if the DC // uses TLS for RPC requests. peerDatacenterUseTLS map[string]bool // logger is not protected by a lock. It must never be changed after // Configurator is created. logger hclog.Logger } // NewConfigurator creates a new Configurator and sets the provided // configuration. func NewConfigurator(config Config, logger hclog.Logger) (*Configurator, error) { if logger == nil { logger = hclog.New(&hclog.LoggerOptions{ Level: hclog.Debug, }) } c := &Configurator{ logger: logger.Named(logging.TLSUtil), peerDatacenterUseTLS: map[string]bool{}, } err := c.Update(config) if err != nil { return nil, err } return c, nil } // ManualCAPems returns the currently loaded CAs in PEM format. func (c *Configurator) ManualCAPems() []string { c.lock.RLock() defer c.lock.RUnlock() return c.manual.caPems } // 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 { c.lock.Lock() defer c.lock.Unlock() cert, err := loadKeyPair(config.CertFile, config.KeyFile) if err != nil { return err } pems, err := LoadCAs(config.CAFile, config.CAPath) if err != nil { return err } caPool, err := newX509CertPool(pems, c.autoTLS.extraCAPems, c.autoTLS.connectCAPems) if err != nil { return err } if err = validateConfig(config, caPool, cert); err != nil { return err } manualCAPool, err := newX509CertPool(pems) if err != nil { return err } c.base = &config c.manual.cert = cert c.manual.caPems = pems c.manual.caPool = manualCAPool c.caPool = caPool atomic.AddUint64(&c.version, 1) c.log("Update") return nil } // UpdateAutoTLSCA updates the autoEncrypt.caPems. This is supposed to be called // from the server in order to be able to accept TLS connections with TLS // certificates. // Or it is being called on the client side when CA changes are detected. func (c *Configurator) UpdateAutoTLSCA(connectCAPems []string) error { c.lock.Lock() defer c.lock.Unlock() pool, err := newX509CertPool(c.manual.caPems, c.autoTLS.extraCAPems, connectCAPems) if err != nil { return err } if err = validateConfig(*c.base, pool, c.manual.cert); err != nil { return err } c.autoTLS.connectCAPems = connectCAPems c.caPool = pool atomic.AddUint64(&c.version, 1) c.log("UpdateAutoTLSCA") return nil } // UpdateAutoTLSCert receives the updated Auto-Encrypt certificate. func (c *Configurator) UpdateAutoTLSCert(pub, priv string) error { cert, err := tls.X509KeyPair([]byte(pub), []byte(priv)) if err != nil { return fmt.Errorf("Failed to load cert/key pair: %v", err) } c.lock.Lock() defer c.lock.Unlock() c.autoTLS.cert = &cert atomic.AddUint64(&c.version, 1) c.log("UpdateAutoTLSCert") return nil } // UpdateAutoTLS receives updates from Auto-Config, only expected to be called on // client agents. func (c *Configurator) UpdateAutoTLS(manualCAPems, connectCAPems []string, pub, priv string, verifyServerHostname bool) error { cert, err := tls.X509KeyPair([]byte(pub), []byte(priv)) if err != nil { return fmt.Errorf("Failed to load cert/key pair: %v", err) } c.lock.Lock() defer c.lock.Unlock() pool, err := newX509CertPool(c.manual.caPems, manualCAPems, connectCAPems) if err != nil { return err } c.autoTLS.extraCAPems = manualCAPems c.autoTLS.connectCAPems = connectCAPems c.autoTLS.cert = &cert c.caPool = pool c.autoTLS.verifyServerHostname = verifyServerHostname atomic.AddUint64(&c.version, 1) c.log("UpdateAutoTLS") return nil } func (c *Configurator) UpdateAreaPeerDatacenterUseTLS(peerDatacenter string, useTLS bool) { c.lock.Lock() defer c.lock.Unlock() atomic.AddUint64(&c.version, 1) c.log("UpdateAreaPeerDatacenterUseTLS") c.peerDatacenterUseTLS[peerDatacenter] = useTLS } func (c *Configurator) getAreaForPeerDatacenterUseTLS(peerDatacenter string) bool { c.lock.RLock() defer c.lock.RUnlock() if v, ok := c.peerDatacenterUseTLS[peerDatacenter]; ok { return v } return true } func (c *Configurator) Base() Config { c.lock.RLock() defer c.lock.RUnlock() return *c.base } // newX509CertPool loads all the groups of PEM encoded certificates into a // single x509.CertPool. // // The groups argument is a varargs of slices so that callers do not need to // append slices together. In some cases append can modify the backing array // of the first slice passed to append, which will often result in hard to // find bugs. By accepting a varargs of slices we remove the need for the // caller to append the groups, which should prevent any such bugs. func newX509CertPool(groups ...[]string) (*x509.CertPool, error) { pool := x509.NewCertPool() for _, group := range groups { for _, pem := range group { if !pool.AppendCertsFromPEM([]byte(pem)) { return nil, fmt.Errorf("failed to parse PEM %s", pem) } } } if len(pool.Subjects()) == 0 { return nil, nil } return pool, nil } // validateConfig checks that config is valid and does not conflict with the pool // or cert. func validateConfig(config Config, pool *x509.CertPool, cert *tls.Certificate) error { // Check if a minimum TLS version was set if config.TLSMinVersion != "" { if _, ok := tlsLookup[config.TLSMinVersion]; !ok { versions := strings.Join(tlsVersions(), ", ") return fmt.Errorf("TLSMinVersion: value %s not supported, please specify one of [%s]", config.TLSMinVersion, versions) } } // Ensure we have a CA if VerifyOutgoing is set if config.VerifyOutgoing && pool == nil { return fmt.Errorf("VerifyOutgoing set, and no CA certificate provided!") } // Ensure we have a CA and cert if VerifyIncoming is set if config.anyVerifyIncoming() { if pool == nil { // both auto-config and auto-encrypt require verifying the connection from the client to the server for secure // operation. In order to be able to verify the servers certificate we must have some CA certs already provided. // Therefore, even though both of those features can push down extra CA certificates which could be used to // verify incoming connections, we still must consider it an error if none are provided in the initial configuration // as those features cannot be successfully enabled without providing CA certificates to use those features. return fmt.Errorf("VerifyIncoming set but no CA certificates were provided") } // We will use the auto_encrypt/auto_config cert for TLS in the incoming APIs when available. Therefore the check // here will ensure that either we enabled one of those two features or a certificate and key were provided manually if cert == nil && !config.AutoTLS { return fmt.Errorf("VerifyIncoming requires either a Cert and Key pair in the configuration file, or auto_encrypt/auto_config be enabled") } } return nil } func (c Config) anyVerifyIncoming() bool { return c.VerifyIncoming || c.VerifyIncomingRPC || c.VerifyIncomingHTTPS } 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) ([]string, error) { if caFile == "" && caPath == "" { return nil, nil } pems := []string{} readFn := func(path string) error { pem, err := ioutil.ReadFile(path) if err != nil { return fmt.Errorf("Error loading from %s: %s", path, err) } pems = append(pems, string(pem)) return nil } walkFn := func(path string, info os.FileInfo, err error) error { if err != nil { return err } if !info.IsDir() { if err := readFn(path); err != nil { return err } } return nil } if caFile != "" { err := readFn(caFile) if err != nil { return pems, err } } else if caPath != "" { err := filepath.Walk(caPath, walkFn) if err != nil { return pems, err } if len(pems) == 0 { return pems, fmt.Errorf("Error loading from CAPath: no CAs found") } } return pems, 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(verifyIncoming bool) *tls.Config { // this needs to be outside of RLock because it acquires an RLock itself verifyServerHostname := c.VerifyServerHostname() c.lock.RLock() defer c.lock.RUnlock() tlsConfig := &tls.Config{ InsecureSkipVerify: !verifyServerHostname, } // Set the cipher suites if len(c.base.CipherSuites) != 0 { tlsConfig.CipherSuites = c.base.CipherSuites } tlsConfig.PreferServerCipherSuites = c.base.PreferServerCipherSuites // GetCertificate is used when acting as a server and responding to // client requests. Default to the manually configured cert, but allow // autoEncrypt cert too so that a client can encrypt incoming // connections without having a manual cert configured. tlsConfig.GetCertificate = func(*tls.ClientHelloInfo) (*tls.Certificate, error) { return c.Cert(), nil } // GetClientCertificate is used when acting as a client and responding // to a server requesting a certificate. Return the autoEncrypt certificate // if possible, otherwise default to the manually provisioned one. tlsConfig.GetClientCertificate = func(*tls.CertificateRequestInfo) (*tls.Certificate, error) { cert := c.autoTLS.cert if cert == nil { cert = c.manual.cert } if cert == nil { // the return value MUST not be nil but an empty certificate will be // treated the same as having no client certificate cert = &tls.Certificate{} } return cert, nil } tlsConfig.ClientCAs = c.caPool tlsConfig.RootCAs = c.caPool // 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 verifyIncoming { tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert } return tlsConfig } // This function acquires a read lock because it reads from the config. func (c *Configurator) Cert() *tls.Certificate { c.lock.RLock() defer c.lock.RUnlock() cert := c.manual.cert if cert == nil { cert = c.autoTLS.cert } return cert } // VerifyIncomingRPC returns true if the configuration has enabled either // VerifyIncoming, or VerifyIncomingRPC func (c *Configurator) VerifyIncomingRPC() bool { c.lock.RLock() defer c.lock.RUnlock() return c.base.VerifyIncoming || c.base.VerifyIncomingRPC } // This function acquires a read lock because it reads from the config. func (c *Configurator) outgoingRPCTLSEnabled() bool { c.lock.RLock() defer c.lock.RUnlock() // use TLS if AutoEncrypt or VerifyOutgoing are enabled. return c.base.AutoTLS || c.base.VerifyOutgoing } // MutualTLSCapable returns true if Configurator has a CA and a local TLS // certificate configured. func (c *Configurator) MutualTLSCapable() bool { c.lock.RLock() defer c.lock.RUnlock() return c.caPool != nil && (c.autoTLS.cert != nil || c.manual.cert != nil) } // This function acquires a read lock because it reads from the config. func (c *Configurator) verifyOutgoing() bool { c.lock.RLock() defer c.lock.RUnlock() // If AutoEncryptTLS is enabled and there is a CA, then verify // outgoing. if c.base.AutoTLS && c.caPool != nil { return true } return c.base.VerifyOutgoing } func (c *Configurator) ServerSNI(dc, nodeName string) string { // Strip the trailing '.' from the domain if any domain := strings.TrimSuffix(c.domain(), ".") if nodeName == "" || nodeName == "*" { return "server." + dc + "." + domain } return nodeName + ".server." + dc + "." + domain } // This function acquires a read lock because it reads from the config. func (c *Configurator) domain() string { c.lock.RLock() defer c.lock.RUnlock() return c.base.Domain } // This function acquires a read lock because it reads from the config. func (c *Configurator) serverNameOrNodeName() string { c.lock.RLock() defer c.lock.RUnlock() if c.base.ServerName != "" { return c.base.ServerName } return c.base.NodeName } // This function acquires a read lock because it reads from the config. func (c *Configurator) VerifyServerHostname() bool { c.lock.RLock() defer c.lock.RUnlock() return c.base.VerifyServerHostname || c.autoTLS.verifyServerHostname } // IncomingXDSConfig generates a *tls.Config for incoming xDS connections. func (c *Configurator) IncomingXDSConfig() *tls.Config { c.log("IncomingXDSConfig") // false has the effect that this config doesn't require a client cert // verification. This is because there is no verify_incoming_grpc // configuration option. And using verify_incoming would be backwards // incompatible, because even if it was set before, it didn't have an // effect on the grpc server. config := c.commonTLSConfig(false) config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingXDSConfig(), nil } return config } // 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 } // IncomingALPNRPCConfig generates a *tls.Config for incoming RPC connections // directly using TLS with ALPN instead of the older byte-prefixed protocol. func (c *Configurator) IncomingALPNRPCConfig(alpnProtos []string) *tls.Config { c.log("IncomingALPNRPCConfig") // Since the ALPN-RPC variation is indirectly exposed to the internet via // mesh gateways we force mTLS and full server name verification. config := c.commonTLSConfig(true) config.InsecureSkipVerify = false config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingALPNRPCConfig(alpnProtos), nil } config.NextProtos = alpnProtos return config } // IncomingInsecureRPCConfig means that it doesn't verify incoming even thought // it might have been configured. This is only supposed to be used by the // servers for the insecure RPC server. At the time of writing only the // AutoEncrypt.Sign call is supported on that server. And it might be the only // usecase ever. func (c *Configurator) IncomingInsecureRPCConfig() *tls.Config { c.log("IncomingInsecureRPCConfig") config := c.commonTLSConfig(false) config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingInsecureRPCConfig(), nil } return config } // IncomingHTTPSConfig generates a *tls.Config for incoming HTTPS connections. func (c *Configurator) IncomingHTTPSConfig() *tls.Config { c.log("IncomingHTTPSConfig") c.lock.RLock() verifyIncoming := c.base.VerifyIncoming || c.base.VerifyIncomingHTTPS c.lock.RUnlock() config := c.commonTLSConfig(verifyIncoming) config.NextProtos = []string{"h2", "http/1.1"} config.GetConfigForClient = func(*tls.ClientHelloInfo) (*tls.Config, error) { return c.IncomingHTTPSConfig(), nil } return config } // OutgoingTLSConfigForCheck 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, serverName string) *tls.Config { c.log("OutgoingTLSConfigForCheck") c.lock.RLock() useAgentTLS := c.base.EnableAgentTLSForChecks c.lock.RUnlock() if !useAgentTLS { return &tls.Config{ InsecureSkipVerify: skipVerify, ServerName: serverName, } } if serverName == "" { serverName = c.serverNameOrNodeName() } config := c.commonTLSConfig(false) config.InsecureSkipVerify = skipVerify config.ServerName = serverName 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.outgoingRPCTLSEnabled() { return nil } return c.commonTLSConfig(false) } // outgoingALPNRPCConfig generates a *tls.Config for outgoing RPC connections // directly using TLS with ALPN instead of the older byte-prefixed protocol. // If there is a CA or VerifyOutgoing is set, a *tls.Config will be provided, // otherwise we assume that no TLS should be used which completely disables the // ALPN variation. func (c *Configurator) outgoingALPNRPCConfig() *tls.Config { c.log("outgoingALPNRPCConfig") if !c.MutualTLSCapable() { return nil // ultimately this will hard-fail as TLS is required } // Since the ALPN-RPC variation is indirectly exposed to the internet via // mesh gateways we force mTLS and full server name verification. config := c.commonTLSConfig(true) config.InsecureSkipVerify = false return config } // 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") // Generate the wrapper based on dc return func(dc string, conn net.Conn) (net.Conn, error) { if c.UseTLS(dc) { return c.wrapTLSClient(dc, conn) } return conn, nil } } // UseTLS returns true if the outgoing RPC requests have been explicitly configured // to use TLS (via VerifyOutgoing or AutoTLS, and the target DC supports TLS. func (c *Configurator) UseTLS(dc string) bool { return c.outgoingRPCTLSEnabled() && c.getAreaForPeerDatacenterUseTLS(dc) } // OutgoingALPNRPCWrapper wraps the result of outgoingALPNRPCConfig in an // ALPNWrapper. It configures all of the negotiation plumbing. func (c *Configurator) OutgoingALPNRPCWrapper() ALPNWrapper { c.log("OutgoingALPNRPCWrapper") if !c.MutualTLSCapable() { return nil } return c.wrapALPNTLSClient } // AutoEncryptCert returns the TLS certificate received from auto-encrypt. func (c *Configurator) AutoEncryptCert() *x509.Certificate { c.lock.RLock() defer c.lock.RUnlock() tlsCert := c.autoTLS.cert if tlsCert == nil || tlsCert.Certificate == nil { return nil } cert, err := x509.ParseCertificate(tlsCert.Certificate[0]) if err != nil { return nil } return cert } func (c *Configurator) log(name string) { if c.logger != nil && c.logger.IsTrace() { c.logger.Trace(name, "version", atomic.LoadUint64(&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) { config := c.OutgoingRPCConfig() verifyServerHostname := c.VerifyServerHostname() verifyOutgoing := c.verifyOutgoing() domain := c.domain() 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 } err := tlsConn.Handshake() if 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(), } cs := tlsConn.ConnectionState() for _, cert := range cs.PeerCertificates[1:] { opts.Intermediates.AddCert(cert) } _, err = cs.PeerCertificates[0].Verify(opts) if err != nil { tlsConn.Close() return nil, err } return tlsConn, err } // Wrap a net.Conn into a client tls connection suitable for secure ALPN-RPC, // performing any additional verification as needed. func (c *Configurator) wrapALPNTLSClient(dc, nodeName, alpnProto string, conn net.Conn) (net.Conn, error) { if dc == "" { return nil, fmt.Errorf("cannot dial using ALPN-RPC without a target datacenter") } else if nodeName == "" { return nil, fmt.Errorf("cannot dial using ALPN-RPC without a target node") } else if alpnProto == "" { return nil, fmt.Errorf("cannot dial using ALPN-RPC without a target alpn protocol") } config := c.outgoingALPNRPCConfig() if config == nil { return nil, fmt.Errorf("cannot dial via a mesh gateway when outgoing TLS is disabled") } // Since the ALPN-RPC variation is indirectly exposed to the internet via // mesh gateways we force mTLS and full hostname validation (forcing // verify_server_hostname and verify_outgoing to be effectively true). config.ServerName = c.ServerSNI(dc, nodeName) config.NextProtos = []string{alpnProto} tlsConn := tls.Client(conn, config) // NOTE: For this handshake to succeed the server must have key material // for either ".server.." or // "*.server.." in addition to the // "server.." required for standard TLS'd RPC. if err := tlsConn.Handshake(); err != nil { tlsConn.Close() return nil, err } return tlsConn, nil } // AuthorizeServerConn is used to validate that the connection is being established // by a Consul server in the same datacenter. // // The identity of the connection is checked by verifying that the certificate // presented is signed by the Agent TLS CA, and has a DNSName that matches the // local ServerSNI name. // // Note this check is only performed if VerifyServerHostname is enabled, otherwise // it does no authorization. func (c *Configurator) AuthorizeServerConn(dc string, conn *tls.Conn) error { if !c.VerifyServerHostname() { return nil } c.lock.RLock() caPool := c.manual.caPool c.lock.RUnlock() expected := c.ServerSNI(dc, "") cs := conn.ConnectionState() var errs error for _, chain := range cs.VerifiedChains { if len(chain) == 0 { continue } opts := x509.VerifyOptions{ DNSName: expected, Intermediates: x509.NewCertPool(), Roots: caPool, KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth}, } for _, cert := range cs.PeerCertificates[1:] { opts.Intermediates.AddCert(cert) } _, err := cs.PeerCertificates[0].Verify(opts) if err == nil { return nil } multierror.Append(errs, err) } return fmt.Errorf("AuthorizeServerConn failed certificate validation for certificate with a SAN.DNSName of %v: %w", expected, errs) } // 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, ",") // Note: this needs to be kept up to date with the cipherMap in CipherString cipherMap := map[string]uint16{ "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA": tls.TLS_ECDHE_ECDSA_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_GCM_SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA": tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384": tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA": tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256": tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256": tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA": tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384": tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, } 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 } // CipherString performs the inverse operation of ParseCiphers func CipherString(ciphers []uint16) (string, error) { // Note: this needs to be kept up to date with the cipherMap in ParseCiphers cipherMap := map[uint16]string{ tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA", tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256", tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA", tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA", tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256: "TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256", tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA: "TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA", tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", } cipherStrings := make([]string, len(ciphers)) for i, cipher := range ciphers { if v, ok := cipherMap[cipher]; ok { cipherStrings[i] = v } else { return "", fmt.Errorf("unsupported cipher %d", cipher) } } return strings.Join(cipherStrings, ","), nil }