362 lines
9.6 KiB
Go
362 lines
9.6 KiB
Go
/*
|
|
Copyright 2018 The Kubernetes Authors.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package exec
|
|
|
|
import (
|
|
"bytes"
|
|
"context"
|
|
"crypto/tls"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"net"
|
|
"net/http"
|
|
"os"
|
|
"os/exec"
|
|
"reflect"
|
|
"sync"
|
|
"time"
|
|
|
|
"golang.org/x/crypto/ssh/terminal"
|
|
"k8s.io/apimachinery/pkg/apis/meta/v1"
|
|
"k8s.io/apimachinery/pkg/runtime"
|
|
"k8s.io/apimachinery/pkg/runtime/schema"
|
|
"k8s.io/apimachinery/pkg/runtime/serializer"
|
|
utilruntime "k8s.io/apimachinery/pkg/util/runtime"
|
|
"k8s.io/client-go/pkg/apis/clientauthentication"
|
|
"k8s.io/client-go/pkg/apis/clientauthentication/v1alpha1"
|
|
"k8s.io/client-go/pkg/apis/clientauthentication/v1beta1"
|
|
"k8s.io/client-go/tools/clientcmd/api"
|
|
"k8s.io/client-go/transport"
|
|
"k8s.io/client-go/util/connrotation"
|
|
"k8s.io/klog"
|
|
)
|
|
|
|
const execInfoEnv = "KUBERNETES_EXEC_INFO"
|
|
|
|
var scheme = runtime.NewScheme()
|
|
var codecs = serializer.NewCodecFactory(scheme)
|
|
|
|
func init() {
|
|
v1.AddToGroupVersion(scheme, schema.GroupVersion{Version: "v1"})
|
|
utilruntime.Must(v1alpha1.AddToScheme(scheme))
|
|
utilruntime.Must(v1beta1.AddToScheme(scheme))
|
|
utilruntime.Must(clientauthentication.AddToScheme(scheme))
|
|
}
|
|
|
|
var (
|
|
// Since transports can be constantly re-initialized by programs like kubectl,
|
|
// keep a cache of initialized authenticators keyed by a hash of their config.
|
|
globalCache = newCache()
|
|
// The list of API versions we accept.
|
|
apiVersions = map[string]schema.GroupVersion{
|
|
v1alpha1.SchemeGroupVersion.String(): v1alpha1.SchemeGroupVersion,
|
|
v1beta1.SchemeGroupVersion.String(): v1beta1.SchemeGroupVersion,
|
|
}
|
|
)
|
|
|
|
func newCache() *cache {
|
|
return &cache{m: make(map[string]*Authenticator)}
|
|
}
|
|
|
|
func cacheKey(c *api.ExecConfig) string {
|
|
return fmt.Sprintf("%#v", c)
|
|
}
|
|
|
|
type cache struct {
|
|
mu sync.Mutex
|
|
m map[string]*Authenticator
|
|
}
|
|
|
|
func (c *cache) get(s string) (*Authenticator, bool) {
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
a, ok := c.m[s]
|
|
return a, ok
|
|
}
|
|
|
|
// put inserts an authenticator into the cache. If an authenticator is already
|
|
// associated with the key, the first one is returned instead.
|
|
func (c *cache) put(s string, a *Authenticator) *Authenticator {
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
existing, ok := c.m[s]
|
|
if ok {
|
|
return existing
|
|
}
|
|
c.m[s] = a
|
|
return a
|
|
}
|
|
|
|
// GetAuthenticator returns an exec-based plugin for providing client credentials.
|
|
func GetAuthenticator(config *api.ExecConfig) (*Authenticator, error) {
|
|
return newAuthenticator(globalCache, config)
|
|
}
|
|
|
|
func newAuthenticator(c *cache, config *api.ExecConfig) (*Authenticator, error) {
|
|
key := cacheKey(config)
|
|
if a, ok := c.get(key); ok {
|
|
return a, nil
|
|
}
|
|
|
|
gv, ok := apiVersions[config.APIVersion]
|
|
if !ok {
|
|
return nil, fmt.Errorf("exec plugin: invalid apiVersion %q", config.APIVersion)
|
|
}
|
|
|
|
a := &Authenticator{
|
|
cmd: config.Command,
|
|
args: config.Args,
|
|
group: gv,
|
|
|
|
stdin: os.Stdin,
|
|
stderr: os.Stderr,
|
|
interactive: terminal.IsTerminal(int(os.Stdout.Fd())),
|
|
now: time.Now,
|
|
environ: os.Environ,
|
|
}
|
|
|
|
for _, env := range config.Env {
|
|
a.env = append(a.env, env.Name+"="+env.Value)
|
|
}
|
|
|
|
return c.put(key, a), nil
|
|
}
|
|
|
|
// Authenticator is a client credential provider that rotates credentials by executing a plugin.
|
|
// The plugin input and output are defined by the API group client.authentication.k8s.io.
|
|
type Authenticator struct {
|
|
// Set by the config
|
|
cmd string
|
|
args []string
|
|
group schema.GroupVersion
|
|
env []string
|
|
|
|
// Stubbable for testing
|
|
stdin io.Reader
|
|
stderr io.Writer
|
|
interactive bool
|
|
now func() time.Time
|
|
environ func() []string
|
|
|
|
// Cached results.
|
|
//
|
|
// The mutex also guards calling the plugin. Since the plugin could be
|
|
// interactive we want to make sure it's only called once.
|
|
mu sync.Mutex
|
|
cachedCreds *credentials
|
|
exp time.Time
|
|
|
|
onRotate func()
|
|
}
|
|
|
|
type credentials struct {
|
|
token string
|
|
cert *tls.Certificate
|
|
}
|
|
|
|
// UpdateTransportConfig updates the transport.Config to use credentials
|
|
// returned by the plugin.
|
|
func (a *Authenticator) UpdateTransportConfig(c *transport.Config) error {
|
|
wt := c.WrapTransport
|
|
c.WrapTransport = func(rt http.RoundTripper) http.RoundTripper {
|
|
if wt != nil {
|
|
rt = wt(rt)
|
|
}
|
|
return &roundTripper{a, rt}
|
|
}
|
|
|
|
if c.TLS.GetCert != nil {
|
|
return errors.New("can't add TLS certificate callback: transport.Config.TLS.GetCert already set")
|
|
}
|
|
c.TLS.GetCert = a.cert
|
|
|
|
var dial func(ctx context.Context, network, addr string) (net.Conn, error)
|
|
if c.Dial != nil {
|
|
dial = c.Dial
|
|
} else {
|
|
dial = (&net.Dialer{Timeout: 30 * time.Second, KeepAlive: 30 * time.Second}).DialContext
|
|
}
|
|
d := connrotation.NewDialer(dial)
|
|
a.onRotate = d.CloseAll
|
|
c.Dial = d.DialContext
|
|
|
|
return nil
|
|
}
|
|
|
|
type roundTripper struct {
|
|
a *Authenticator
|
|
base http.RoundTripper
|
|
}
|
|
|
|
func (r *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
|
|
// If a user has already set credentials, use that. This makes commands like
|
|
// "kubectl get --token (token) pods" work.
|
|
if req.Header.Get("Authorization") != "" {
|
|
return r.base.RoundTrip(req)
|
|
}
|
|
|
|
creds, err := r.a.getCreds()
|
|
if err != nil {
|
|
return nil, fmt.Errorf("getting credentials: %v", err)
|
|
}
|
|
if creds.token != "" {
|
|
req.Header.Set("Authorization", "Bearer "+creds.token)
|
|
}
|
|
|
|
res, err := r.base.RoundTrip(req)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if res.StatusCode == http.StatusUnauthorized {
|
|
resp := &clientauthentication.Response{
|
|
Header: res.Header,
|
|
Code: int32(res.StatusCode),
|
|
}
|
|
if err := r.a.maybeRefreshCreds(creds, resp); err != nil {
|
|
klog.Errorf("refreshing credentials: %v", err)
|
|
}
|
|
}
|
|
return res, nil
|
|
}
|
|
|
|
func (a *Authenticator) credsExpired() bool {
|
|
if a.exp.IsZero() {
|
|
return false
|
|
}
|
|
return a.now().After(a.exp)
|
|
}
|
|
|
|
func (a *Authenticator) cert() (*tls.Certificate, error) {
|
|
creds, err := a.getCreds()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return creds.cert, nil
|
|
}
|
|
|
|
func (a *Authenticator) getCreds() (*credentials, error) {
|
|
a.mu.Lock()
|
|
defer a.mu.Unlock()
|
|
if a.cachedCreds != nil && !a.credsExpired() {
|
|
return a.cachedCreds, nil
|
|
}
|
|
|
|
if err := a.refreshCredsLocked(nil); err != nil {
|
|
return nil, err
|
|
}
|
|
return a.cachedCreds, nil
|
|
}
|
|
|
|
// maybeRefreshCreds executes the plugin to force a rotation of the
|
|
// credentials, unless they were rotated already.
|
|
func (a *Authenticator) maybeRefreshCreds(creds *credentials, r *clientauthentication.Response) error {
|
|
a.mu.Lock()
|
|
defer a.mu.Unlock()
|
|
|
|
// Since we're not making a new pointer to a.cachedCreds in getCreds, no
|
|
// need to do deep comparison.
|
|
if creds != a.cachedCreds {
|
|
// Credentials already rotated.
|
|
return nil
|
|
}
|
|
|
|
return a.refreshCredsLocked(r)
|
|
}
|
|
|
|
// refreshCredsLocked executes the plugin and reads the credentials from
|
|
// stdout. It must be called while holding the Authenticator's mutex.
|
|
func (a *Authenticator) refreshCredsLocked(r *clientauthentication.Response) error {
|
|
cred := &clientauthentication.ExecCredential{
|
|
Spec: clientauthentication.ExecCredentialSpec{
|
|
Response: r,
|
|
Interactive: a.interactive,
|
|
},
|
|
}
|
|
|
|
env := append(a.environ(), a.env...)
|
|
if a.group == v1alpha1.SchemeGroupVersion {
|
|
// Input spec disabled for beta due to lack of use. Possibly re-enable this later if
|
|
// someone wants it back.
|
|
//
|
|
// See: https://github.com/kubernetes/kubernetes/issues/61796
|
|
data, err := runtime.Encode(codecs.LegacyCodec(a.group), cred)
|
|
if err != nil {
|
|
return fmt.Errorf("encode ExecCredentials: %v", err)
|
|
}
|
|
env = append(env, fmt.Sprintf("%s=%s", execInfoEnv, data))
|
|
}
|
|
|
|
stdout := &bytes.Buffer{}
|
|
cmd := exec.Command(a.cmd, a.args...)
|
|
cmd.Env = env
|
|
cmd.Stderr = a.stderr
|
|
cmd.Stdout = stdout
|
|
if a.interactive {
|
|
cmd.Stdin = a.stdin
|
|
}
|
|
|
|
if err := cmd.Run(); err != nil {
|
|
return fmt.Errorf("exec: %v", err)
|
|
}
|
|
|
|
_, gvk, err := codecs.UniversalDecoder(a.group).Decode(stdout.Bytes(), nil, cred)
|
|
if err != nil {
|
|
return fmt.Errorf("decoding stdout: %v", err)
|
|
}
|
|
if gvk.Group != a.group.Group || gvk.Version != a.group.Version {
|
|
return fmt.Errorf("exec plugin is configured to use API version %s, plugin returned version %s",
|
|
a.group, schema.GroupVersion{Group: gvk.Group, Version: gvk.Version})
|
|
}
|
|
|
|
if cred.Status == nil {
|
|
return fmt.Errorf("exec plugin didn't return a status field")
|
|
}
|
|
if cred.Status.Token == "" && cred.Status.ClientCertificateData == "" && cred.Status.ClientKeyData == "" {
|
|
return fmt.Errorf("exec plugin didn't return a token or cert/key pair")
|
|
}
|
|
if (cred.Status.ClientCertificateData == "") != (cred.Status.ClientKeyData == "") {
|
|
return fmt.Errorf("exec plugin returned only certificate or key, not both")
|
|
}
|
|
|
|
if cred.Status.ExpirationTimestamp != nil {
|
|
a.exp = cred.Status.ExpirationTimestamp.Time
|
|
} else {
|
|
a.exp = time.Time{}
|
|
}
|
|
|
|
newCreds := &credentials{
|
|
token: cred.Status.Token,
|
|
}
|
|
if cred.Status.ClientKeyData != "" && cred.Status.ClientCertificateData != "" {
|
|
cert, err := tls.X509KeyPair([]byte(cred.Status.ClientCertificateData), []byte(cred.Status.ClientKeyData))
|
|
if err != nil {
|
|
return fmt.Errorf("failed parsing client key/certificate: %v", err)
|
|
}
|
|
newCreds.cert = &cert
|
|
}
|
|
|
|
oldCreds := a.cachedCreds
|
|
a.cachedCreds = newCreds
|
|
// Only close all connections when TLS cert rotates. Token rotation doesn't
|
|
// need the extra noise.
|
|
if a.onRotate != nil && oldCreds != nil && !reflect.DeepEqual(oldCreds.cert, a.cachedCreds.cert) {
|
|
a.onRotate()
|
|
}
|
|
return nil
|
|
}
|