certificates/ca/tls.go
2022-12-21 16:02:26 +01:00

392 lines
13 KiB
Go

package ca
import (
"context"
"crypto"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"encoding/pem"
"net"
"net/http"
"os"
"runtime"
"time"
"github.com/pkg/errors"
"github.com/smallstep/certificates/api"
"github.com/smallstep/certificates/ca/identity"
)
// mTLSDialContext will hold the dial context function to use in
// getDefaultTransport.
var mTLSDialContext func() func(ctx context.Context, network, address string) (net.Conn, error)
// localAddr is the local address to use when dialing an address. This address
// is defined by the environment variable STEP_CLIENT_ADDR.
var localAddr net.Addr
func init() {
// STEP_TLS_TUNNEL is an environment variable that can be set to do an TLS
// over (m)TLS tunnel to step-ca using identity-like credentials. The value
// is a path to a json file with the tunnel host, certificate, key and root
// used to create the (m)TLS tunnel.
//
// The configuration should look like:
// {
// "type": "tTLS",
// "host": "tunnel.example.com:443"
// "crt": "/path/to/tunnel.crt",
// "key": "/path/to/tunnel.key",
// "root": "/path/to/tunnel-root.crt"
// }
//
// This feature is EXPERIMENTAL and might change at any time.
if path := os.Getenv("STEP_TLS_TUNNEL"); path != "" {
id, err := identity.LoadIdentity(path)
if err != nil {
panic(err)
}
if err := id.Validate(); err != nil {
panic(err)
}
host, port, err := net.SplitHostPort(id.Host)
if err != nil {
panic(err)
}
pool, err := id.GetCertPool()
if err != nil {
panic(err)
}
mTLSDialContext = func() func(ctx context.Context, network, address string) (net.Conn, error) {
d := &tls.Dialer{
NetDialer: getDefaultDialer(),
Config: &tls.Config{
MinVersion: tls.VersionTLS12,
RootCAs: pool,
GetClientCertificate: id.GetClientCertificateFunc(),
},
}
return func(ctx context.Context, network, address string) (net.Conn, error) {
return d.DialContext(ctx, "tcp", net.JoinHostPort(host, port))
}
}
}
// STEP_CLIENT_ADDR is an environment variable that can be set to define the
// local address to use when dialing an address. This can be useful when
// step is run behind a CIDR-based ACL.
//
// STEP_CLIENT_ADDR can be set to an IP ("127.0.0.1", "[::1]"), a hostname
// ("localhost"), or a host:port ("[::1]:0"). If the port is set to
// something other than ":0" and the dialer is created multiple times it
// will fail with an "address already in use" error.
//
// See https://github.com/smallstep/cli/issues/730
if v := os.Getenv("STEP_CLIENT_ADDR"); v != "" {
_, _, err := net.SplitHostPort(v)
if err != nil {
// assuming that the error is a missing port, if it's not it will
// panic below.
v += ":0"
}
localAddr, err = net.ResolveTCPAddr("tcp", v)
if err != nil {
panic(err)
}
}
}
// GetClientTLSConfig returns a tls.Config for client use configured with the
// sign certificate, and a new certificate pool with the sign root certificate.
// The client certificate will automatically rotate before expiring.
func (c *Client) GetClientTLSConfig(ctx context.Context, sign *api.SignResponse, pk crypto.PrivateKey, options ...TLSOption) (*tls.Config, error) {
tlsConfig, _, err := c.getClientTLSConfig(ctx, sign, pk, options)
if err != nil {
return nil, err
}
return tlsConfig, nil
}
func (c *Client) getClientTLSConfig(ctx context.Context, sign *api.SignResponse, pk crypto.PrivateKey, options []TLSOption) (*tls.Config, *http.Transport, error) {
cert, err := TLSCertificate(sign, pk)
if err != nil {
return nil, nil, err
}
renewer, err := NewTLSRenewer(cert, nil)
if err != nil {
return nil, nil, err
}
tlsConfig := getDefaultTLSConfig(sign)
// Note that with GetClientCertificate tlsConfig.Certificates is not used.
// Without tlsConfig.Certificates there's not need to use tlsConfig.BuildNameToCertificate()
tlsConfig.GetClientCertificate = renewer.GetClientCertificate
// Apply options and initialize mutable tls.Config
tlsCtx := newTLSOptionCtx(c, tlsConfig, sign)
if err := tlsCtx.apply(options); err != nil {
return nil, nil, err
}
tr := getDefaultTransport(tlsConfig)
//nolint:staticcheck // Use mutable tls.Config on renew
tr.DialTLS = c.buildDialTLS(tlsCtx)
// tr.DialTLSContext = c.buildDialTLSContext(tlsCtx)
renewer.RenewCertificate = getRenewFunc(tlsCtx, c, tr, pk) //nolint:contextcheck // deeply nested context
// Update client transport
c.SetTransport(tr)
// Start renewer
renewer.RunContext(ctx)
return tlsConfig, tr, nil
}
// GetServerTLSConfig returns a tls.Config for server use configured with the
// sign certificate, and a new certificate pool with the sign root certificate.
// The returned tls.Config will only verify the client certificate if provided.
// The server certificate will automatically rotate before expiring.
func (c *Client) GetServerTLSConfig(ctx context.Context, sign *api.SignResponse, pk crypto.PrivateKey, options ...TLSOption) (*tls.Config, error) {
cert, err := TLSCertificate(sign, pk)
if err != nil {
return nil, err
}
renewer, err := NewTLSRenewer(cert, nil)
if err != nil {
return nil, err
}
tlsConfig := getDefaultTLSConfig(sign)
// Note that GetCertificate will only be called if the client supplies SNI
// information or if tlsConfig.Certificates is empty.
// Without tlsConfig.Certificates there's not need to use tlsConfig.BuildNameToCertificate()
tlsConfig.GetCertificate = renewer.GetCertificate
tlsConfig.GetClientCertificate = renewer.GetClientCertificate
tlsConfig.ClientAuth = tls.RequireAndVerifyClientCert
// Apply options and initialize mutable tls.Config
tlsCtx := newTLSOptionCtx(c, tlsConfig, sign)
if err := tlsCtx.apply(options); err != nil {
return nil, err
}
// GetConfigForClient allows seamless root and federated roots rotation.
// If the return of the callback is not-nil, it will use the returned
// tls.Config instead of the default one.
tlsConfig.GetConfigForClient = c.buildGetConfigForClient(tlsCtx)
// Update renew function with transport
tr := getDefaultTransport(tlsConfig)
//nolint:staticcheck // Use mutable tls.Config on renew
tr.DialTLS = c.buildDialTLS(tlsCtx)
// tr.DialTLSContext = c.buildDialTLSContext(tlsCtx)
renewer.RenewCertificate = getRenewFunc(tlsCtx, c, tr, pk) //nolint:contextcheck // deeply nested context
// Update client transport
c.SetTransport(tr)
// Start renewer
renewer.RunContext(ctx)
return tlsConfig, nil
}
// Transport returns an http.Transport configured to use the client certificate from the sign response.
func (c *Client) Transport(ctx context.Context, sign *api.SignResponse, pk crypto.PrivateKey, options ...TLSOption) (*http.Transport, error) {
_, tr, err := c.getClientTLSConfig(ctx, sign, pk, options)
if err != nil {
return nil, err
}
return tr, nil
}
// buildGetConfigForClient returns an implementation of GetConfigForClient
// callback in tls.Config.
//
// If the implementation returns a nil tls.Config, the original Config will be
// used, but if it's non-nil, the returned Config will be used to handle this
// connection.
func (c *Client) buildGetConfigForClient(ctx *TLSOptionCtx) func(*tls.ClientHelloInfo) (*tls.Config, error) {
return func(*tls.ClientHelloInfo) (*tls.Config, error) {
return ctx.mutableConfig.TLSConfig(), nil
}
}
// buildDialTLS returns an implementation of DialTLS callback in http.Transport.
func (c *Client) buildDialTLS(ctx *TLSOptionCtx) func(network, addr string) (net.Conn, error) {
return func(network, addr string) (net.Conn, error) {
return tls.DialWithDialer(getDefaultDialer(), network, addr, ctx.mutableConfig.TLSConfig())
}
}
//nolint:unused // buildDialTLSContext returns an implementation of DialTLSContext callback in http.Transport.
func (c *Client) buildDialTLSContext(tlsCtx *TLSOptionCtx) func(ctx context.Context, network, addr string) (net.Conn, error) {
return func(ctx context.Context, network, addr string) (net.Conn, error) {
d := getDefaultDialer()
// TLS dialers do not support context, but we can use the context
// deadline if it is set.
if t, ok := ctx.Deadline(); ok {
d.Deadline = t
}
return tls.DialWithDialer(d, network, addr, tlsCtx.mutableConfig.TLSConfig())
}
}
// Certificate returns the server or client certificate from the sign response.
func Certificate(sign *api.SignResponse) (*x509.Certificate, error) {
if sign.ServerPEM.Certificate == nil {
return nil, errors.New("ca: certificate does not exist")
}
return sign.ServerPEM.Certificate, nil
}
// IntermediateCertificate returns the CA intermediate certificate from the sign
// response.
func IntermediateCertificate(sign *api.SignResponse) (*x509.Certificate, error) {
if sign.CaPEM.Certificate == nil {
return nil, errors.New("ca: certificate does not exist")
}
return sign.CaPEM.Certificate, nil
}
// RootCertificate returns the root certificate from the sign response.
func RootCertificate(sign *api.SignResponse) (*x509.Certificate, error) {
if sign == nil || sign.TLS == nil || len(sign.TLS.VerifiedChains) == 0 {
return nil, errors.New("ca: certificate does not exist")
}
lastChain := sign.TLS.VerifiedChains[len(sign.TLS.VerifiedChains)-1]
if len(lastChain) == 0 {
return nil, errors.New("ca: certificate does not exist")
}
return lastChain[len(lastChain)-1], nil
}
// TLSCertificate creates a new TLS certificate from the sign response and the
// private key used.
func TLSCertificate(sign *api.SignResponse, pk crypto.PrivateKey) (*tls.Certificate, error) {
certPEM, err := getPEM(sign.ServerPEM)
if err != nil {
return nil, err
}
caPEM, err := getPEM(sign.CaPEM)
if err != nil {
return nil, err
}
keyPEM, err := getPEM(pk)
if err != nil {
return nil, err
}
//nolint:gocritic // using a new variable for clarity
chain := append(certPEM, caPEM...)
cert, err := tls.X509KeyPair(chain, keyPEM)
if err != nil {
return nil, errors.Wrap(err, "error creating tls certificate")
}
leaf, err := x509.ParseCertificate(cert.Certificate[0])
if err != nil {
return nil, errors.Wrap(err, "error parsing tls certificate")
}
cert.Leaf = leaf
return &cert, nil
}
func getDefaultTLSConfig(sign *api.SignResponse) *tls.Config {
if sign.TLSOptions != nil {
return sign.TLSOptions.TLSConfig()
}
return &tls.Config{
MinVersion: tls.VersionTLS12,
}
}
// getDefaultDialer returns a new dialer with the default configuration.
func getDefaultDialer() *net.Dialer {
// With the KeepAlive parameter set to 0, it will be use Golang's default.
return &net.Dialer{
Timeout: 30 * time.Second,
LocalAddr: localAddr,
}
}
// getDefaultTransport returns an http.Transport with the same parameters than
// http.DefaultTransport, but adds the given tls.Config and configures the
// transport for HTTP/2.
func getDefaultTransport(tlsConfig *tls.Config) *http.Transport {
var dialContext func(ctx context.Context, network string, addr string) (net.Conn, error)
switch {
case runtime.GOOS == "js" && runtime.GOARCH == "wasm":
// when running in js/wasm and using the default dialer context all requests
// performed by the CA client resulted in a "protocol not supported" error.
// By setting the dial context to nil requests will be handled by the browser
// fetch API instead. Currently this will always set the dial context to nil,
// but we could implement some additional logic similar to what's found in
// https://github.com/golang/go/pull/46923/files to support a different dial
// context if it is available, required and expected to work.
dialContext = nil
case mTLSDialContext == nil:
d := getDefaultDialer()
dialContext = d.DialContext
default:
dialContext = mTLSDialContext()
}
return &http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: dialContext,
ForceAttemptHTTP2: true,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
TLSClientConfig: tlsConfig,
}
}
func getPEM(i interface{}) ([]byte, error) {
block := new(pem.Block)
switch i := i.(type) {
case api.Certificate:
block.Type = "CERTIFICATE"
block.Bytes = i.Raw
case *x509.Certificate:
block.Type = "CERTIFICATE"
block.Bytes = i.Raw
case *rsa.PrivateKey:
block.Type = "RSA PRIVATE KEY"
block.Bytes = x509.MarshalPKCS1PrivateKey(i)
case *ecdsa.PrivateKey:
var err error
block.Type = "EC PRIVATE KEY"
block.Bytes, err = x509.MarshalECPrivateKey(i)
if err != nil {
return nil, errors.Wrap(err, "error marshaling private key")
}
case ed25519.PrivateKey:
var err error
block.Type = "PRIVATE KEY"
block.Bytes, err = x509.MarshalPKCS8PrivateKey(i)
if err != nil {
return nil, errors.Wrap(err, "error marshaling private key")
}
default:
return nil, errors.Errorf("unsupported key type %T", i)
}
return pem.EncodeToMemory(block), nil
}
func getRenewFunc(ctx *TLSOptionCtx, client *Client, tr *http.Transport, pk crypto.PrivateKey) RenewFunc {
return func() (*tls.Certificate, error) {
// Get updated list of roots
if err := ctx.applyRenew(); err != nil {
return nil, err
}
// Get new certificate
sign, err := client.Renew(tr)
if err != nil {
return nil, err
}
return TLSCertificate(sign, pk)
}
}