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azure.go
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azure.go
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/*
Copyright 2017 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 azure
import (
"encoding/json"
"errors"
"fmt"
"net/http"
"os"
"strconv"
"sync"
"github.com/Azure/go-autorest/autorest"
"github.com/Azure/go-autorest/autorest/adal"
"github.com/Azure/go-autorest/autorest/azure"
"k8s.io/klog/v2"
"k8s.io/apimachinery/pkg/util/net"
restclient "k8s.io/client-go/rest"
)
type configMode int
const (
azureTokenKey = "azureTokenKey"
tokenType = "Bearer"
authHeader = "Authorization"
cfgClientID = "client-id"
cfgTenantID = "tenant-id"
cfgAccessToken = "access-token"
cfgRefreshToken = "refresh-token"
cfgExpiresIn = "expires-in"
cfgExpiresOn = "expires-on"
cfgEnvironment = "environment"
cfgApiserverID = "apiserver-id"
cfgConfigMode = "config-mode"
configModeDefault configMode = 0
configModeOmitSPNPrefix configMode = 1
)
func init() {
if err := restclient.RegisterAuthProviderPlugin("azure", newAzureAuthProvider); err != nil {
klog.Fatalf("Failed to register azure auth plugin: %v", err)
}
}
var cache = newAzureTokenCache()
type azureTokenCache struct {
lock sync.Mutex
cache map[string]*azureToken
}
func newAzureTokenCache() *azureTokenCache {
return &azureTokenCache{cache: make(map[string]*azureToken)}
}
func (c *azureTokenCache) getToken(tokenKey string) *azureToken {
c.lock.Lock()
defer c.lock.Unlock()
return c.cache[tokenKey]
}
func (c *azureTokenCache) setToken(tokenKey string, token *azureToken) {
c.lock.Lock()
defer c.lock.Unlock()
c.cache[tokenKey] = token
}
var warnOnce sync.Once
func newAzureAuthProvider(_ string, cfg map[string]string, persister restclient.AuthProviderConfigPersister) (restclient.AuthProvider, error) {
// deprecated in v1.22, remove in v1.25
// this should be updated to use klog.Warningf in v1.24 to more actively warn consumers
warnOnce.Do(func() {
klog.V(1).Infof(`WARNING: the azure auth plugin is deprecated in v1.22+, unavailable in v1.25+; use https://github.com/Azure/kubelogin instead.
To learn more, consult https://kubernetes.io/docs/reference/access-authn-authz/authentication/#client-go-credential-plugins`)
})
var (
ts tokenSource
environment azure.Environment
err error
mode configMode
)
environment, err = azure.EnvironmentFromName(cfg[cfgEnvironment])
if err != nil {
environment = azure.PublicCloud
}
mode = configModeDefault
if cfg[cfgConfigMode] != "" {
configModeInt, err := strconv.Atoi(cfg[cfgConfigMode])
if err != nil {
return nil, fmt.Errorf("failed to parse %s, error: %s", cfgConfigMode, err)
}
mode = configMode(configModeInt)
switch mode {
case configModeOmitSPNPrefix:
case configModeDefault:
default:
return nil, fmt.Errorf("%s:%s is not a valid mode", cfgConfigMode, cfg[cfgConfigMode])
}
}
ts, err = newAzureTokenSourceDeviceCode(environment, cfg[cfgClientID], cfg[cfgTenantID], cfg[cfgApiserverID], mode)
if err != nil {
return nil, fmt.Errorf("creating a new azure token source for device code authentication: %v", err)
}
cacheSource := newAzureTokenSource(ts, cache, cfg, mode, persister)
return &azureAuthProvider{
tokenSource: cacheSource,
}, nil
}
type azureAuthProvider struct {
tokenSource tokenSource
}
func (p *azureAuthProvider) Login() error {
return errors.New("not yet implemented")
}
func (p *azureAuthProvider) WrapTransport(rt http.RoundTripper) http.RoundTripper {
return &azureRoundTripper{
tokenSource: p.tokenSource,
roundTripper: rt,
}
}
type azureRoundTripper struct {
tokenSource tokenSource
roundTripper http.RoundTripper
}
var _ net.RoundTripperWrapper = &azureRoundTripper{}
func (r *azureRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
if len(req.Header.Get(authHeader)) != 0 {
return r.roundTripper.RoundTrip(req)
}
token, err := r.tokenSource.Token()
if err != nil {
klog.Errorf("Failed to acquire a token: %v", err)
return nil, fmt.Errorf("acquiring a token for authorization header: %v", err)
}
// clone the request in order to avoid modifying the headers of the original request
req2 := new(http.Request)
*req2 = *req
req2.Header = make(http.Header, len(req.Header))
for k, s := range req.Header {
req2.Header[k] = append([]string(nil), s...)
}
req2.Header.Set(authHeader, fmt.Sprintf("%s %s", tokenType, token.token.AccessToken))
return r.roundTripper.RoundTrip(req2)
}
func (r *azureRoundTripper) WrappedRoundTripper() http.RoundTripper { return r.roundTripper }
type azureToken struct {
token adal.Token
environment string
clientID string
tenantID string
apiserverID string
}
type tokenSource interface {
Token() (*azureToken, error)
Refresh(*azureToken) (*azureToken, error)
}
type azureTokenSource struct {
source tokenSource
cache *azureTokenCache
lock sync.Mutex
configMode configMode
cfg map[string]string
persister restclient.AuthProviderConfigPersister
}
func newAzureTokenSource(source tokenSource, cache *azureTokenCache, cfg map[string]string, configMode configMode, persister restclient.AuthProviderConfigPersister) tokenSource {
return &azureTokenSource{
source: source,
cache: cache,
cfg: cfg,
persister: persister,
configMode: configMode,
}
}
// Token fetches a token from the cache of configuration if present otherwise
// acquires a new token from the configured source. Automatically refreshes
// the token if expired.
func (ts *azureTokenSource) Token() (*azureToken, error) {
ts.lock.Lock()
defer ts.lock.Unlock()
var err error
token := ts.cache.getToken(azureTokenKey)
if token != nil && !token.token.IsExpired() {
return token, nil
}
// retrieve from config if no cache
if token == nil {
tokenFromCfg, err := ts.retrieveTokenFromCfg()
if err == nil {
token = tokenFromCfg
}
}
if token != nil {
// cache and return if the token is as good
// avoids frequent persistor calls
if !token.token.IsExpired() {
ts.cache.setToken(azureTokenKey, token)
return token, nil
}
klog.V(4).Info("Refreshing token.")
tokenFromRefresh, err := ts.Refresh(token)
switch {
case err == nil:
token = tokenFromRefresh
case autorest.IsTokenRefreshError(err):
klog.V(4).Infof("Failed to refresh expired token, proceed to auth: %v", err)
// reset token to nil so that the token source will be used to acquire new
token = nil
default:
return nil, fmt.Errorf("unexpected error when refreshing token: %v", err)
}
}
if token == nil {
tokenFromSource, err := ts.source.Token()
if err != nil {
return nil, fmt.Errorf("failed acquiring new token: %v", err)
}
token = tokenFromSource
}
// sanity check
if token == nil {
return nil, fmt.Errorf("unable to acquire token")
}
// corner condition, newly got token is valid but expired
if token.token.IsExpired() {
return nil, fmt.Errorf("newly acquired token is expired")
}
err = ts.storeTokenInCfg(token)
if err != nil {
return nil, fmt.Errorf("storing the refreshed token in configuration: %v", err)
}
ts.cache.setToken(azureTokenKey, token)
return token, nil
}
func (ts *azureTokenSource) retrieveTokenFromCfg() (*azureToken, error) {
accessToken := ts.cfg[cfgAccessToken]
if accessToken == "" {
return nil, fmt.Errorf("no access token in cfg: %s", cfgAccessToken)
}
refreshToken := ts.cfg[cfgRefreshToken]
if refreshToken == "" {
return nil, fmt.Errorf("no refresh token in cfg: %s", cfgRefreshToken)
}
environment := ts.cfg[cfgEnvironment]
if environment == "" {
return nil, fmt.Errorf("no environment in cfg: %s", cfgEnvironment)
}
clientID := ts.cfg[cfgClientID]
if clientID == "" {
return nil, fmt.Errorf("no client ID in cfg: %s", cfgClientID)
}
tenantID := ts.cfg[cfgTenantID]
if tenantID == "" {
return nil, fmt.Errorf("no tenant ID in cfg: %s", cfgTenantID)
}
resourceID := ts.cfg[cfgApiserverID]
if resourceID == "" {
return nil, fmt.Errorf("no apiserver ID in cfg: %s", cfgApiserverID)
}
expiresIn := ts.cfg[cfgExpiresIn]
if expiresIn == "" {
return nil, fmt.Errorf("no expiresIn in cfg: %s", cfgExpiresIn)
}
expiresOn := ts.cfg[cfgExpiresOn]
if expiresOn == "" {
return nil, fmt.Errorf("no expiresOn in cfg: %s", cfgExpiresOn)
}
tokenAudience := resourceID
if ts.configMode == configModeDefault {
tokenAudience = fmt.Sprintf("spn:%s", resourceID)
}
return &azureToken{
token: adal.Token{
AccessToken: accessToken,
RefreshToken: refreshToken,
ExpiresIn: json.Number(expiresIn),
ExpiresOn: json.Number(expiresOn),
NotBefore: json.Number(expiresOn),
Resource: tokenAudience,
Type: tokenType,
},
environment: environment,
clientID: clientID,
tenantID: tenantID,
apiserverID: resourceID,
}, nil
}
func (ts *azureTokenSource) storeTokenInCfg(token *azureToken) error {
newCfg := make(map[string]string)
newCfg[cfgAccessToken] = token.token.AccessToken
newCfg[cfgRefreshToken] = token.token.RefreshToken
newCfg[cfgEnvironment] = token.environment
newCfg[cfgClientID] = token.clientID
newCfg[cfgTenantID] = token.tenantID
newCfg[cfgApiserverID] = token.apiserverID
newCfg[cfgExpiresIn] = string(token.token.ExpiresIn)
newCfg[cfgExpiresOn] = string(token.token.ExpiresOn)
newCfg[cfgConfigMode] = strconv.Itoa(int(ts.configMode))
err := ts.persister.Persist(newCfg)
if err != nil {
return fmt.Errorf("persisting the configuration: %v", err)
}
ts.cfg = newCfg
return nil
}
func (ts *azureTokenSource) Refresh(token *azureToken) (*azureToken, error) {
return ts.source.Refresh(token)
}
// refresh outdated token with adal.
func (ts *azureTokenSourceDeviceCode) Refresh(token *azureToken) (*azureToken, error) {
env, err := azure.EnvironmentFromName(token.environment)
if err != nil {
return nil, err
}
var oauthConfig *adal.OAuthConfig
if ts.configMode == configModeOmitSPNPrefix {
oauthConfig, err = adal.NewOAuthConfigWithAPIVersion(env.ActiveDirectoryEndpoint, token.tenantID, nil)
if err != nil {
return nil, fmt.Errorf("building the OAuth configuration without api-version for token refresh: %v", err)
}
} else {
oauthConfig, err = adal.NewOAuthConfig(env.ActiveDirectoryEndpoint, token.tenantID)
if err != nil {
return nil, fmt.Errorf("building the OAuth configuration for token refresh: %v", err)
}
}
callback := func(t adal.Token) error {
return nil
}
spt, err := adal.NewServicePrincipalTokenFromManualToken(
*oauthConfig,
token.clientID,
token.apiserverID,
token.token,
callback)
if err != nil {
return nil, fmt.Errorf("creating new service principal for token refresh: %v", err)
}
if err := spt.Refresh(); err != nil {
// Caller expects IsTokenRefreshError(err) to trigger prompt.
return nil, fmt.Errorf("refreshing token: %w", err)
}
return &azureToken{
token: spt.Token(),
environment: token.environment,
clientID: token.clientID,
tenantID: token.tenantID,
apiserverID: token.apiserverID,
}, nil
}
type azureTokenSourceDeviceCode struct {
environment azure.Environment
clientID string
tenantID string
apiserverID string
configMode configMode
}
func newAzureTokenSourceDeviceCode(environment azure.Environment, clientID string, tenantID string, apiserverID string, configMode configMode) (tokenSource, error) {
if clientID == "" {
return nil, errors.New("client-id is empty")
}
if tenantID == "" {
return nil, errors.New("tenant-id is empty")
}
if apiserverID == "" {
return nil, errors.New("apiserver-id is empty")
}
return &azureTokenSourceDeviceCode{
environment: environment,
clientID: clientID,
tenantID: tenantID,
apiserverID: apiserverID,
configMode: configMode,
}, nil
}
func (ts *azureTokenSourceDeviceCode) Token() (*azureToken, error) {
var (
oauthConfig *adal.OAuthConfig
err error
)
if ts.configMode == configModeOmitSPNPrefix {
oauthConfig, err = adal.NewOAuthConfigWithAPIVersion(ts.environment.ActiveDirectoryEndpoint, ts.tenantID, nil)
if err != nil {
return nil, fmt.Errorf("building the OAuth configuration without api-version for device code authentication: %v", err)
}
} else {
oauthConfig, err = adal.NewOAuthConfig(ts.environment.ActiveDirectoryEndpoint, ts.tenantID)
if err != nil {
return nil, fmt.Errorf("building the OAuth configuration for device code authentication: %v", err)
}
}
client := &autorest.Client{}
deviceCode, err := adal.InitiateDeviceAuth(client, *oauthConfig, ts.clientID, ts.apiserverID)
if err != nil {
return nil, fmt.Errorf("initialing the device code authentication: %v", err)
}
_, err = fmt.Fprintln(os.Stderr, *deviceCode.Message)
if err != nil {
return nil, fmt.Errorf("prompting the device code message: %v", err)
}
token, err := adal.WaitForUserCompletion(client, deviceCode)
if err != nil {
return nil, fmt.Errorf("waiting for device code authentication to complete: %v", err)
}
return &azureToken{
token: *token,
environment: ts.environment.Name,
clientID: ts.clientID,
tenantID: ts.tenantID,
apiserverID: ts.apiserverID,
}, nil
}