/* 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 }