| /* |
| Copyright 2016 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 options |
| |
| import ( |
| "fmt" |
| "time" |
| |
| "github.com/spf13/pflag" |
| "k8s.io/klog" |
| |
| "k8s.io/apiserver/pkg/authorization/authorizer" |
| "k8s.io/apiserver/pkg/authorization/authorizerfactory" |
| "k8s.io/apiserver/pkg/authorization/path" |
| "k8s.io/apiserver/pkg/authorization/union" |
| "k8s.io/apiserver/pkg/server" |
| "k8s.io/client-go/kubernetes" |
| "k8s.io/client-go/rest" |
| "k8s.io/client-go/tools/clientcmd" |
| ) |
| |
| // DelegatingAuthorizationOptions provides an easy way for composing API servers to delegate their authorization to |
| // the root kube API server. |
| // WARNING: never assume that every authenticated incoming request already does authorization. |
| // The aggregator in the kube API server does this today, but this behaviour is not |
| // guaranteed in the future. |
| type DelegatingAuthorizationOptions struct { |
| // RemoteKubeConfigFile is the file to use to connect to a "normal" kube API server which hosts the |
| // SubjectAccessReview.authorization.k8s.io endpoint for checking tokens. |
| RemoteKubeConfigFile string |
| // RemoteKubeConfigFileOptional is specifying whether not specifying the kubeconfig or |
| // a missing in-cluster config will be fatal. |
| RemoteKubeConfigFileOptional bool |
| |
| // AllowCacheTTL is the length of time that a successful authorization response will be cached |
| AllowCacheTTL time.Duration |
| |
| // DenyCacheTTL is the length of time that an unsuccessful authorization response will be cached. |
| // You generally want more responsive, "deny, try again" flows. |
| DenyCacheTTL time.Duration |
| |
| // AlwaysAllowPaths are HTTP paths which are excluded from authorization. They can be plain |
| // paths or end in * in which case prefix-match is applied. A leading / is optional. |
| AlwaysAllowPaths []string |
| |
| // AlwaysAllowGroups are groups which are allowed to take any actions. In kube, this is system:masters. |
| AlwaysAllowGroups []string |
| } |
| |
| func NewDelegatingAuthorizationOptions() *DelegatingAuthorizationOptions { |
| return &DelegatingAuthorizationOptions{ |
| // very low for responsiveness, but high enough to handle storms |
| AllowCacheTTL: 10 * time.Second, |
| DenyCacheTTL: 10 * time.Second, |
| } |
| } |
| |
| // WithAlwaysAllowGroups appends the list of paths to AlwaysAllowGroups |
| func (s *DelegatingAuthorizationOptions) WithAlwaysAllowGroups(groups ...string) *DelegatingAuthorizationOptions { |
| s.AlwaysAllowGroups = append(s.AlwaysAllowGroups, groups...) |
| return s |
| } |
| |
| // WithAlwaysAllowPaths appends the list of paths to AlwaysAllowPaths |
| func (s *DelegatingAuthorizationOptions) WithAlwaysAllowPaths(paths ...string) *DelegatingAuthorizationOptions { |
| s.AlwaysAllowPaths = append(s.AlwaysAllowPaths, paths...) |
| return s |
| } |
| |
| func (s *DelegatingAuthorizationOptions) Validate() []error { |
| allErrors := []error{} |
| return allErrors |
| } |
| |
| func (s *DelegatingAuthorizationOptions) AddFlags(fs *pflag.FlagSet) { |
| if s == nil { |
| return |
| } |
| |
| var optionalKubeConfigSentence string |
| if s.RemoteKubeConfigFileOptional { |
| optionalKubeConfigSentence = " This is optional. If empty, all requests not skipped by authorization are forbidden." |
| } |
| fs.StringVar(&s.RemoteKubeConfigFile, "authorization-kubeconfig", s.RemoteKubeConfigFile, |
| "kubeconfig file pointing at the 'core' kubernetes server with enough rights to create "+ |
| "subjectaccessreviews.authorization.k8s.io."+optionalKubeConfigSentence) |
| |
| fs.DurationVar(&s.AllowCacheTTL, "authorization-webhook-cache-authorized-ttl", |
| s.AllowCacheTTL, |
| "The duration to cache 'authorized' responses from the webhook authorizer.") |
| |
| fs.DurationVar(&s.DenyCacheTTL, |
| "authorization-webhook-cache-unauthorized-ttl", s.DenyCacheTTL, |
| "The duration to cache 'unauthorized' responses from the webhook authorizer.") |
| |
| fs.StringSliceVar(&s.AlwaysAllowPaths, "authorization-always-allow-paths", s.AlwaysAllowPaths, |
| "A list of HTTP paths to skip during authorization, i.e. these are authorized without "+ |
| "contacting the 'core' kubernetes server.") |
| } |
| |
| func (s *DelegatingAuthorizationOptions) ApplyTo(c *server.AuthorizationInfo) error { |
| if s == nil { |
| c.Authorizer = authorizerfactory.NewAlwaysAllowAuthorizer() |
| return nil |
| } |
| |
| client, err := s.getClient() |
| if err != nil { |
| return err |
| } |
| |
| c.Authorizer, err = s.toAuthorizer(client) |
| return err |
| } |
| |
| func (s *DelegatingAuthorizationOptions) toAuthorizer(client kubernetes.Interface) (authorizer.Authorizer, error) { |
| var authorizers []authorizer.Authorizer |
| |
| if len(s.AlwaysAllowGroups) > 0 { |
| authorizers = append(authorizers, authorizerfactory.NewPrivilegedGroups(s.AlwaysAllowGroups...)) |
| } |
| |
| if len(s.AlwaysAllowPaths) > 0 { |
| a, err := path.NewAuthorizer(s.AlwaysAllowPaths) |
| if err != nil { |
| return nil, err |
| } |
| authorizers = append(authorizers, a) |
| } |
| |
| if client == nil { |
| klog.Warningf("No authorization-kubeconfig provided, so SubjectAccessReview of authorization tokens won't work.") |
| } else { |
| cfg := authorizerfactory.DelegatingAuthorizerConfig{ |
| SubjectAccessReviewClient: client.AuthorizationV1beta1().SubjectAccessReviews(), |
| AllowCacheTTL: s.AllowCacheTTL, |
| DenyCacheTTL: s.DenyCacheTTL, |
| } |
| delegatedAuthorizer, err := cfg.New() |
| if err != nil { |
| return nil, err |
| } |
| authorizers = append(authorizers, delegatedAuthorizer) |
| } |
| |
| return union.New(authorizers...), nil |
| } |
| |
| func (s *DelegatingAuthorizationOptions) getClient() (kubernetes.Interface, error) { |
| var clientConfig *rest.Config |
| var err error |
| if len(s.RemoteKubeConfigFile) > 0 { |
| loadingRules := &clientcmd.ClientConfigLoadingRules{ExplicitPath: s.RemoteKubeConfigFile} |
| loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, &clientcmd.ConfigOverrides{}) |
| |
| clientConfig, err = loader.ClientConfig() |
| } else { |
| // without the remote kubeconfig file, try to use the in-cluster config. Most addon API servers will |
| // use this path. If it is optional, ignore errors. |
| clientConfig, err = rest.InClusterConfig() |
| if err != nil && s.RemoteKubeConfigFileOptional { |
| if err != rest.ErrNotInCluster { |
| klog.Warningf("failed to read in-cluster kubeconfig for delegated authorization: %v", err) |
| } |
| return nil, nil |
| } |
| } |
| if err != nil { |
| return nil, fmt.Errorf("failed to get delegated authorization kubeconfig: %v", err) |
| } |
| |
| // set high qps/burst limits since this will effectively limit API server responsiveness |
| clientConfig.QPS = 200 |
| clientConfig.Burst = 400 |
| |
| return kubernetes.NewForConfig(clientConfig) |
| } |