distribution/registry/auth/token/accesscontroller.go

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package token
import (
"crypto"
"crypto/x509"
"encoding/pem"
"errors"
"fmt"
"io/ioutil"
"net/http"
"os"
"strings"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/registry/auth"
"github.com/docker/libtrust"
"golang.org/x/net/context"
)
// accessSet maps a typed, named resource to
// a set of actions requested or authorized.
type accessSet map[auth.Resource]actionSet
// newAccessSet constructs an accessSet from
// a variable number of auth.Access items.
func newAccessSet(accessItems ...auth.Access) accessSet {
accessSet := make(accessSet, len(accessItems))
for _, access := range accessItems {
resource := auth.Resource{
Type: access.Type,
Name: access.Name,
}
set, exists := accessSet[resource]
if !exists {
set = newActionSet()
accessSet[resource] = set
}
set.add(access.Action)
}
return accessSet
}
// contains returns whether or not the given access is in this accessSet.
func (s accessSet) contains(access auth.Access) bool {
actionSet, ok := s[access.Resource]
if ok {
return actionSet.contains(access.Action)
}
return false
}
// scopeParam returns a collection of scopes which can
// be used for a WWW-Authenticate challenge parameter.
// See https://tools.ietf.org/html/rfc6750#section-3
func (s accessSet) scopeParam() string {
scopes := make([]string, 0, len(s))
for resource, actionSet := range s {
actions := strings.Join(actionSet.keys(), ",")
scopes = append(scopes, fmt.Sprintf("%s:%s:%s", resource.Type, resource.Name, actions))
}
return strings.Join(scopes, " ")
}
// Errors used and exported by this package.
var (
ErrInsufficientScope = errors.New("insufficient scope")
ErrTokenRequired = errors.New("authorization token required")
)
// authChallenge implements the auth.Challenge interface.
type authChallenge struct {
err error
realm string
service string
accessSet accessSet
}
// Error returns the internal error string for this authChallenge.
func (ac *authChallenge) Error() string {
return ac.err.Error()
}
// Status returns the HTTP Response Status Code for this authChallenge.
func (ac *authChallenge) Status() int {
return http.StatusUnauthorized
}
// challengeParams constructs the value to be used in
// the WWW-Authenticate response challenge header.
// See https://tools.ietf.org/html/rfc6750#section-3
func (ac *authChallenge) challengeParams() string {
str := fmt.Sprintf("Bearer realm=%q,service=%q", ac.realm, ac.service)
if scope := ac.accessSet.scopeParam(); scope != "" {
str = fmt.Sprintf("%s,scope=%q", str, scope)
}
if ac.err == ErrInvalidToken || ac.err == ErrMalformedToken {
str = fmt.Sprintf("%s,error=%q", str, "invalid_token")
} else if ac.err == ErrInsufficientScope {
str = fmt.Sprintf("%s,error=%q", str, "insufficient_scope")
}
return str
}
// SetHeader sets the WWW-Authenticate value for the given header.
func (ac *authChallenge) SetHeader(header http.Header) {
header.Add("WWW-Authenticate", ac.challengeParams())
}
// ServeHttp handles writing the challenge response
// by setting the challenge header and status code.
func (ac *authChallenge) ServeHTTP(w http.ResponseWriter, r *http.Request) {
ac.SetHeader(w.Header())
w.WriteHeader(ac.Status())
}
// accessController implements the auth.AccessController interface.
type accessController struct {
realm string
issuer string
service string
rootCerts *x509.CertPool
trustedKeys map[string]libtrust.PublicKey
}
// tokenAccessOptions is a convenience type for handling
// options to the contstructor of an accessController.
type tokenAccessOptions struct {
realm string
issuer string
service string
rootCertBundle string
}
// checkOptions gathers the necessary options
// for an accessController from the given map.
func checkOptions(options map[string]interface{}) (tokenAccessOptions, error) {
var opts tokenAccessOptions
keys := []string{"realm", "issuer", "service", "rootcertbundle"}
vals := make([]string, 0, len(keys))
for _, key := range keys {
val, ok := options[key].(string)
if !ok {
return opts, fmt.Errorf("token auth requires a valid option string: %q", key)
}
vals = append(vals, val)
}
opts.realm, opts.issuer, opts.service, opts.rootCertBundle = vals[0], vals[1], vals[2], vals[3]
return opts, nil
}
// newAccessController creates an accessController using the given options.
func newAccessController(options map[string]interface{}) (auth.AccessController, error) {
config, err := checkOptions(options)
if err != nil {
return nil, err
}
fp, err := os.Open(config.rootCertBundle)
if err != nil {
return nil, fmt.Errorf("unable to open token auth root certificate bundle file %q: %s", config.rootCertBundle, err)
}
defer fp.Close()
rawCertBundle, err := ioutil.ReadAll(fp)
if err != nil {
return nil, fmt.Errorf("unable to read token auth root certificate bundle file %q: %s", config.rootCertBundle, err)
}
var rootCerts []*x509.Certificate
pemBlock, rawCertBundle := pem.Decode(rawCertBundle)
for pemBlock != nil {
cert, err := x509.ParseCertificate(pemBlock.Bytes)
if err != nil {
return nil, fmt.Errorf("unable to parse token auth root certificate: %s", err)
}
rootCerts = append(rootCerts, cert)
pemBlock, rawCertBundle = pem.Decode(rawCertBundle)
}
if len(rootCerts) == 0 {
return nil, errors.New("token auth requires at least one token signing root certificate")
}
rootPool := x509.NewCertPool()
trustedKeys := make(map[string]libtrust.PublicKey, len(rootCerts))
for _, rootCert := range rootCerts {
rootPool.AddCert(rootCert)
pubKey, err := libtrust.FromCryptoPublicKey(crypto.PublicKey(rootCert.PublicKey))
if err != nil {
return nil, fmt.Errorf("unable to get public key from token auth root certificate: %s", err)
}
trustedKeys[pubKey.KeyID()] = pubKey
}
return &accessController{
realm: config.realm,
issuer: config.issuer,
service: config.service,
rootCerts: rootPool,
trustedKeys: trustedKeys,
}, nil
}
// Authorized handles checking whether the given request is authorized
// for actions on resources described by the given access items.
func (ac *accessController) Authorized(ctx context.Context, accessItems ...auth.Access) (context.Context, error) {
challenge := &authChallenge{
realm: ac.realm,
service: ac.service,
accessSet: newAccessSet(accessItems...),
}
req, err := ctxu.GetRequest(ctx)
if err != nil {
return nil, err
}
parts := strings.Split(req.Header.Get("Authorization"), " ")
if len(parts) != 2 || strings.ToLower(parts[0]) != "bearer" {
challenge.err = ErrTokenRequired
return nil, challenge
}
rawToken := parts[1]
token, err := NewToken(rawToken)
if err != nil {
challenge.err = err
return nil, challenge
}
verifyOpts := VerifyOptions{
TrustedIssuers: []string{ac.issuer},
AcceptedAudiences: []string{ac.service},
Roots: ac.rootCerts,
TrustedKeys: ac.trustedKeys,
}
if err = token.Verify(verifyOpts); err != nil {
challenge.err = err
return nil, challenge
}
accessSet := token.accessSet()
for _, access := range accessItems {
if !accessSet.contains(access) {
challenge.err = ErrInsufficientScope
return nil, challenge
}
}
return auth.WithUser(ctx, auth.UserInfo{Name: token.Claims.Subject}), nil
}
// init handles registering the token auth backend.
func init() {
auth.Register("token", auth.InitFunc(newAccessController))
}