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