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config.go
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config.go
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/*
Copyright 2014 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 authenticator
import (
"context"
"errors"
"fmt"
"sync/atomic"
"time"
utilerrors "k8s.io/apimachinery/pkg/util/errors"
utilnet "k8s.io/apimachinery/pkg/util/net"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/apiserver/pkg/apis/apiserver"
"k8s.io/apiserver/pkg/authentication/authenticator"
"k8s.io/apiserver/pkg/authentication/authenticatorfactory"
"k8s.io/apiserver/pkg/authentication/group"
"k8s.io/apiserver/pkg/authentication/request/anonymous"
"k8s.io/apiserver/pkg/authentication/request/bearertoken"
"k8s.io/apiserver/pkg/authentication/request/headerrequest"
"k8s.io/apiserver/pkg/authentication/request/union"
"k8s.io/apiserver/pkg/authentication/request/websocket"
"k8s.io/apiserver/pkg/authentication/request/x509"
tokencache "k8s.io/apiserver/pkg/authentication/token/cache"
"k8s.io/apiserver/pkg/authentication/token/tokenfile"
tokenunion "k8s.io/apiserver/pkg/authentication/token/union"
"k8s.io/apiserver/pkg/server/dynamiccertificates"
webhookutil "k8s.io/apiserver/pkg/util/webhook"
"k8s.io/apiserver/plugin/pkg/authenticator/token/oidc"
"k8s.io/apiserver/plugin/pkg/authenticator/token/webhook"
typedv1core "k8s.io/client-go/kubernetes/typed/core/v1"
"k8s.io/kube-openapi/pkg/spec3"
"k8s.io/kube-openapi/pkg/validation/spec"
// Initialize all known client auth plugins.
_ "k8s.io/client-go/plugin/pkg/client/auth"
"k8s.io/client-go/util/keyutil"
"k8s.io/kubernetes/pkg/serviceaccount"
)
// Config contains the data on how to authenticate a request to the Kube API Server
type Config struct {
Anonymous bool
BootstrapToken bool
TokenAuthFile string
AuthenticationConfig *apiserver.AuthenticationConfiguration
AuthenticationConfigData string
OIDCSigningAlgs []string
ServiceAccountKeyFiles []string
ServiceAccountLookup bool
ServiceAccountIssuers []string
APIAudiences authenticator.Audiences
WebhookTokenAuthnConfigFile string
WebhookTokenAuthnVersion string
WebhookTokenAuthnCacheTTL time.Duration
// WebhookRetryBackoff specifies the backoff parameters for the authentication webhook retry logic.
// This allows us to configure the sleep time at each iteration and the maximum number of retries allowed
// before we fail the webhook call in order to limit the fan out that ensues when the system is degraded.
WebhookRetryBackoff *wait.Backoff
TokenSuccessCacheTTL time.Duration
TokenFailureCacheTTL time.Duration
RequestHeaderConfig *authenticatorfactory.RequestHeaderConfig
// TODO, this is the only non-serializable part of the entire config. Factor it out into a clientconfig
ServiceAccountTokenGetter serviceaccount.ServiceAccountTokenGetter
SecretsWriter typedv1core.SecretsGetter
BootstrapTokenAuthenticator authenticator.Token
// ClientCAContentProvider are the options for verifying incoming connections using mTLS and directly assigning to users.
// Generally this is the CA bundle file used to authenticate client certificates
// If this value is nil, then mutual TLS is disabled.
ClientCAContentProvider dynamiccertificates.CAContentProvider
// Optional field, custom dial function used to connect to webhook
CustomDial utilnet.DialFunc
}
// New returns an authenticator.Request or an error that supports the standard
// Kubernetes authentication mechanisms.
func (config Config) New(serverLifecycle context.Context) (authenticator.Request, func(context.Context, *apiserver.AuthenticationConfiguration) error, *spec.SecurityDefinitions, spec3.SecuritySchemes, error) {
var authenticators []authenticator.Request
var tokenAuthenticators []authenticator.Token
securityDefinitionsV2 := spec.SecurityDefinitions{}
securitySchemesV3 := spec3.SecuritySchemes{}
// front-proxy, BasicAuth methods, local first, then remote
// Add the front proxy authenticator if requested
if config.RequestHeaderConfig != nil {
requestHeaderAuthenticator := headerrequest.NewDynamicVerifyOptionsSecure(
config.RequestHeaderConfig.CAContentProvider.VerifyOptions,
config.RequestHeaderConfig.AllowedClientNames,
config.RequestHeaderConfig.UsernameHeaders,
config.RequestHeaderConfig.GroupHeaders,
config.RequestHeaderConfig.ExtraHeaderPrefixes,
)
authenticators = append(authenticators, authenticator.WrapAudienceAgnosticRequest(config.APIAudiences, requestHeaderAuthenticator))
}
// X509 methods
if config.ClientCAContentProvider != nil {
certAuth := x509.NewDynamic(config.ClientCAContentProvider.VerifyOptions, x509.CommonNameUserConversion)
authenticators = append(authenticators, certAuth)
}
// Bearer token methods, local first, then remote
if len(config.TokenAuthFile) > 0 {
tokenAuth, err := newAuthenticatorFromTokenFile(config.TokenAuthFile)
if err != nil {
return nil, nil, nil, nil, err
}
tokenAuthenticators = append(tokenAuthenticators, authenticator.WrapAudienceAgnosticToken(config.APIAudiences, tokenAuth))
}
if len(config.ServiceAccountKeyFiles) > 0 {
serviceAccountAuth, err := newLegacyServiceAccountAuthenticator(config.ServiceAccountKeyFiles, config.ServiceAccountLookup, config.APIAudiences, config.ServiceAccountTokenGetter, config.SecretsWriter)
if err != nil {
return nil, nil, nil, nil, err
}
tokenAuthenticators = append(tokenAuthenticators, serviceAccountAuth)
}
if len(config.ServiceAccountIssuers) > 0 {
serviceAccountAuth, err := newServiceAccountAuthenticator(config.ServiceAccountIssuers, config.ServiceAccountKeyFiles, config.APIAudiences, config.ServiceAccountTokenGetter)
if err != nil {
return nil, nil, nil, nil, err
}
tokenAuthenticators = append(tokenAuthenticators, serviceAccountAuth)
}
if config.BootstrapToken && config.BootstrapTokenAuthenticator != nil {
tokenAuthenticators = append(tokenAuthenticators, authenticator.WrapAudienceAgnosticToken(config.APIAudiences, config.BootstrapTokenAuthenticator))
}
// NOTE(ericchiang): Keep the OpenID Connect after Service Accounts.
//
// Because both plugins verify JWTs whichever comes first in the union experiences
// cache misses for all requests using the other. While the service account plugin
// simply returns an error, the OpenID Connect plugin may query the provider to
// update the keys, causing performance hits.
var updateAuthenticationConfig func(context.Context, *apiserver.AuthenticationConfiguration) error
if config.AuthenticationConfig != nil {
initialJWTAuthenticator, err := newJWTAuthenticator(serverLifecycle, config.AuthenticationConfig, config.OIDCSigningAlgs, config.APIAudiences, config.ServiceAccountIssuers)
if err != nil {
return nil, nil, nil, nil, err
}
jwtAuthenticatorPtr := &atomic.Pointer[jwtAuthenticatorWithCancel]{}
jwtAuthenticatorPtr.Store(initialJWTAuthenticator)
updateAuthenticationConfig = (&authenticationConfigUpdater{
serverLifecycle: serverLifecycle,
config: config,
jwtAuthenticatorPtr: jwtAuthenticatorPtr,
}).updateAuthenticationConfig
tokenAuthenticators = append(tokenAuthenticators,
authenticator.TokenFunc(func(ctx context.Context, token string) (*authenticator.Response, bool, error) {
return jwtAuthenticatorPtr.Load().jwtAuthenticator.AuthenticateToken(ctx, token)
}),
)
}
if len(config.WebhookTokenAuthnConfigFile) > 0 {
webhookTokenAuth, err := newWebhookTokenAuthenticator(config)
if err != nil {
return nil, nil, nil, nil, err
}
tokenAuthenticators = append(tokenAuthenticators, webhookTokenAuth)
}
if len(tokenAuthenticators) > 0 {
// Union the token authenticators
tokenAuth := tokenunion.New(tokenAuthenticators...)
// Optionally cache authentication results
if config.TokenSuccessCacheTTL > 0 || config.TokenFailureCacheTTL > 0 {
tokenAuth = tokencache.New(tokenAuth, true, config.TokenSuccessCacheTTL, config.TokenFailureCacheTTL)
}
authenticators = append(authenticators, bearertoken.New(tokenAuth), websocket.NewProtocolAuthenticator(tokenAuth))
securityDefinitionsV2["BearerToken"] = &spec.SecurityScheme{
SecuritySchemeProps: spec.SecuritySchemeProps{
Type: "apiKey",
Name: "authorization",
In: "header",
Description: "Bearer Token authentication",
},
}
securitySchemesV3["BearerToken"] = &spec3.SecurityScheme{
SecuritySchemeProps: spec3.SecuritySchemeProps{
Type: "apiKey",
Name: "authorization",
In: "header",
Description: "Bearer Token authentication",
},
}
}
if len(authenticators) == 0 {
if config.Anonymous {
return anonymous.NewAuthenticator(), nil, &securityDefinitionsV2, securitySchemesV3, nil
}
return nil, nil, &securityDefinitionsV2, securitySchemesV3, nil
}
authenticator := union.New(authenticators...)
authenticator = group.NewAuthenticatedGroupAdder(authenticator)
if config.Anonymous {
// If the authenticator chain returns an error, return an error (don't consider a bad bearer token
// or invalid username/password combination anonymous).
authenticator = union.NewFailOnError(authenticator, anonymous.NewAuthenticator())
}
return authenticator, updateAuthenticationConfig, &securityDefinitionsV2, securitySchemesV3, nil
}
type jwtAuthenticatorWithCancel struct {
jwtAuthenticator authenticator.Token
healthCheck func() error
cancel func()
}
func newJWTAuthenticator(serverLifecycle context.Context, config *apiserver.AuthenticationConfiguration, oidcSigningAlgs []string, apiAudiences authenticator.Audiences, disallowedIssuers []string) (_ *jwtAuthenticatorWithCancel, buildErr error) {
ctx, cancel := context.WithCancel(serverLifecycle)
defer func() {
if buildErr != nil {
cancel()
}
}()
var jwtAuthenticators []authenticator.Token
var healthChecks []func() error
for _, jwtAuthenticator := range config.JWT {
// TODO remove this CAContentProvider indirection
var oidcCAContent oidc.CAContentProvider
if len(jwtAuthenticator.Issuer.CertificateAuthority) > 0 {
var oidcCAError error
oidcCAContent, oidcCAError = dynamiccertificates.NewStaticCAContent("oidc-authenticator", []byte(jwtAuthenticator.Issuer.CertificateAuthority))
if oidcCAError != nil {
return nil, oidcCAError
}
}
oidcAuth, err := oidc.New(ctx, oidc.Options{
JWTAuthenticator: jwtAuthenticator,
CAContentProvider: oidcCAContent,
SupportedSigningAlgs: oidcSigningAlgs,
DisallowedIssuers: disallowedIssuers,
})
if err != nil {
return nil, err
}
jwtAuthenticators = append(jwtAuthenticators, oidcAuth)
healthChecks = append(healthChecks, oidcAuth.HealthCheck)
}
return &jwtAuthenticatorWithCancel{
jwtAuthenticator: authenticator.WrapAudienceAgnosticToken(apiAudiences, tokenunion.NewFailOnError(jwtAuthenticators...)), // this handles the empty jwtAuthenticators slice case correctly
healthCheck: func() error {
var errs []error
for _, check := range healthChecks {
if err := check(); err != nil {
errs = append(errs, err)
}
}
return utilerrors.NewAggregate(errs)
},
cancel: cancel,
}, nil
}
type authenticationConfigUpdater struct {
serverLifecycle context.Context
config Config
jwtAuthenticatorPtr *atomic.Pointer[jwtAuthenticatorWithCancel]
}
// the input ctx controls the timeout for updateAuthenticationConfig to return, not the lifetime of the constructed authenticators.
func (c *authenticationConfigUpdater) updateAuthenticationConfig(ctx context.Context, authConfig *apiserver.AuthenticationConfiguration) error {
updatedJWTAuthenticator, err := newJWTAuthenticator(c.serverLifecycle, authConfig, c.config.OIDCSigningAlgs, c.config.APIAudiences, c.config.ServiceAccountIssuers)
if err != nil {
return err
}
var lastErr error
if waitErr := wait.PollUntilContextCancel(ctx, 10*time.Second, true, func(_ context.Context) (done bool, err error) {
lastErr = updatedJWTAuthenticator.healthCheck()
return lastErr == nil, nil
}); lastErr != nil || waitErr != nil {
updatedJWTAuthenticator.cancel()
return utilerrors.NewAggregate([]error{lastErr, waitErr}) // filters out nil errors
}
oldJWTAuthenticator := c.jwtAuthenticatorPtr.Swap(updatedJWTAuthenticator)
go func() {
t := time.NewTimer(time.Minute)
defer t.Stop()
select {
case <-c.serverLifecycle.Done():
case <-t.C:
}
// TODO maybe track requests so we know when this is safe to do
oldJWTAuthenticator.cancel()
}()
return nil
}
// IsValidServiceAccountKeyFile returns true if a valid public RSA key can be read from the given file
func IsValidServiceAccountKeyFile(file string) bool {
_, err := keyutil.PublicKeysFromFile(file)
return err == nil
}
// newAuthenticatorFromTokenFile returns an authenticator.Token or an error
func newAuthenticatorFromTokenFile(tokenAuthFile string) (authenticator.Token, error) {
tokenAuthenticator, err := tokenfile.NewCSV(tokenAuthFile)
if err != nil {
return nil, err
}
return tokenAuthenticator, nil
}
// newLegacyServiceAccountAuthenticator returns an authenticator.Token or an error
func newLegacyServiceAccountAuthenticator(keyfiles []string, lookup bool, apiAudiences authenticator.Audiences, serviceAccountGetter serviceaccount.ServiceAccountTokenGetter, secretsWriter typedv1core.SecretsGetter) (authenticator.Token, error) {
allPublicKeys := []interface{}{}
for _, keyfile := range keyfiles {
publicKeys, err := keyutil.PublicKeysFromFile(keyfile)
if err != nil {
return nil, err
}
allPublicKeys = append(allPublicKeys, publicKeys...)
}
validator, err := serviceaccount.NewLegacyValidator(lookup, serviceAccountGetter, secretsWriter)
if err != nil {
return nil, fmt.Errorf("while creating legacy validator, err: %w", err)
}
tokenAuthenticator := serviceaccount.JWTTokenAuthenticator([]string{serviceaccount.LegacyIssuer}, allPublicKeys, apiAudiences, validator)
return tokenAuthenticator, nil
}
// newServiceAccountAuthenticator returns an authenticator.Token or an error
func newServiceAccountAuthenticator(issuers []string, keyfiles []string, apiAudiences authenticator.Audiences, serviceAccountGetter serviceaccount.ServiceAccountTokenGetter) (authenticator.Token, error) {
allPublicKeys := []interface{}{}
for _, keyfile := range keyfiles {
publicKeys, err := keyutil.PublicKeysFromFile(keyfile)
if err != nil {
return nil, err
}
allPublicKeys = append(allPublicKeys, publicKeys...)
}
tokenAuthenticator := serviceaccount.JWTTokenAuthenticator(issuers, allPublicKeys, apiAudiences, serviceaccount.NewValidator(serviceAccountGetter))
return tokenAuthenticator, nil
}
func newWebhookTokenAuthenticator(config Config) (authenticator.Token, error) {
if config.WebhookRetryBackoff == nil {
return nil, errors.New("retry backoff parameters for authentication webhook has not been specified")
}
clientConfig, err := webhookutil.LoadKubeconfig(config.WebhookTokenAuthnConfigFile, config.CustomDial)
if err != nil {
return nil, err
}
webhookTokenAuthenticator, err := webhook.New(clientConfig, config.WebhookTokenAuthnVersion, config.APIAudiences, *config.WebhookRetryBackoff)
if err != nil {
return nil, err
}
return tokencache.New(webhookTokenAuthenticator, false, config.WebhookTokenAuthnCacheTTL, config.WebhookTokenAuthnCacheTTL), nil
}