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