forked from hashicorp/consul
/
config.go
505 lines (435 loc) · 16.3 KB
/
config.go
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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.<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
// 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
}