distribution/auth/token/token.go
Josh Hawn 88de2e11fb Refactor auth stringSet into common.StringSet
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
2014-12-17 10:57:05 -08:00

340 lines
9.8 KiB
Go

package token
import (
"crypto"
"crypto/x509"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"strings"
"time"
log "github.com/Sirupsen/logrus"
"github.com/docker/libtrust"
"github.com/docker/docker-registry/auth"
"github.com/docker/docker-registry/common"
)
const (
// TokenSeparator is the value which separates the header, claims, and
// signature in the compact serialization of a JSON Web Token.
TokenSeparator = "."
)
// Errors used by token parsing and verification.
var (
ErrMalformedToken = errors.New("malformed token")
ErrInvalidToken = errors.New("invalid token")
)
// ResourceActions stores allowed actions on a named and typed resource.
type ResourceActions struct {
Type string `json:"type"`
Name string `json:"name"`
Actions []string `json:"actions"`
}
// ClaimSet describes the main section of a JSON Web Token.
type ClaimSet struct {
// Public claims
Issuer string `json:"iss"`
Subject string `json:"sub"`
Audience string `json:"aud"`
Expiration int64 `json:"exp"`
NotBefore int64 `json:"nbf"`
IssuedAt int64 `json:"iat"`
JWTID string `json:"jti"`
// Private claims
Access []*ResourceActions
}
// Header describes the header section of a JSON Web Token.
type Header struct {
Type string `json:"typ"`
SigningAlg string `json:"alg"`
KeyID string `json:"kid,omitempty"`
RawJWK json.RawMessage `json:"jwk"`
SigningKey libtrust.PublicKey `json:"-"`
}
// CheckSigningKey parses the `jwk` field of a JOSE header and sets the
// SigningKey field if it is valid.
func (h *Header) CheckSigningKey() (err error) {
if len(h.RawJWK) == 0 {
// No signing key was specified.
return
}
h.SigningKey, err = libtrust.UnmarshalPublicKeyJWK([]byte(h.RawJWK))
h.RawJWK = nil // Don't need this anymore!
return
}
// Token describes a JSON Web Token.
type Token struct {
Raw string
Header *Header
Claims *ClaimSet
Signature []byte
Valid bool
}
// VerifyOptions is used to specify
// options when verifying a JSON Web Token.
type VerifyOptions struct {
TrustedIssuers common.StringSet
AccpetedAudiences common.StringSet
Roots *x509.CertPool
TrustedKeys map[string]libtrust.PublicKey
}
// NewToken parses the given raw token string
// and constructs an unverified JSON Web Token.
func NewToken(rawToken string) (*Token, error) {
parts := strings.Split(rawToken, TokenSeparator)
if len(parts) != 3 {
return nil, ErrMalformedToken
}
var (
rawHeader, rawClaims = parts[0], parts[1]
headerJSON, claimsJSON []byte
err error
)
defer func() {
if err != nil {
log.Errorf("error while unmarshalling raw token: %s", err)
}
}()
if headerJSON, err = joseBase64UrlDecode(rawHeader); err != nil {
err = fmt.Errorf("unable to decode header: %s", err)
return nil, ErrMalformedToken
}
if claimsJSON, err = joseBase64UrlDecode(rawClaims); err != nil {
err = fmt.Errorf("unable to decode claims: %s", err)
return nil, ErrMalformedToken
}
token := new(Token)
token.Header = new(Header)
token.Claims = new(ClaimSet)
token.Raw = strings.Join(parts[:2], TokenSeparator)
if token.Signature, err = joseBase64UrlDecode(parts[2]); err != nil {
err = fmt.Errorf("unable to decode signature: %s", err)
return nil, ErrMalformedToken
}
if err = json.Unmarshal(headerJSON, token.Header); err != nil {
return nil, ErrMalformedToken
}
if err = token.Header.CheckSigningKey(); err != nil {
return nil, ErrMalformedToken
}
if err = json.Unmarshal(claimsJSON, token.Claims); err != nil {
return nil, ErrMalformedToken
}
return token, nil
}
// Verify attempts to verify this token using the given options.
// Returns a nil error if the token is valid.
func (t *Token) Verify(verifyOpts VerifyOptions) error {
if t.Valid {
// Token was already verified.
return nil
}
// Verify that the Issuer claim is a trusted authority.
if !verifyOpts.TrustedIssuers.Contains(t.Claims.Issuer) {
log.Errorf("token from untrusted issuer: %q", t.Claims.Issuer)
return ErrInvalidToken
}
// Verify that the Audience claim is allowed.
if !verifyOpts.AccpetedAudiences.Contains(t.Claims.Audience) {
log.Errorf("token intended for another audience: %q", t.Claims.Audience)
return ErrInvalidToken
}
// Verify that the token is currently usable and not expired.
currentUnixTime := time.Now().Unix()
if !(t.Claims.NotBefore <= currentUnixTime && currentUnixTime <= t.Claims.Expiration) {
log.Errorf("token not to be used before %d or after %d - currently %d", t.Claims.NotBefore, t.Claims.Expiration, currentUnixTime)
return ErrInvalidToken
}
// Verify the token signature.
if len(t.Signature) == 0 {
log.Error("token has no signature")
return ErrInvalidToken
}
// If the token header has a SigningKey field, verify the signature
// using that key and its included x509 certificate chain if necessary.
// If the Header's SigningKey field is nil, try using the KeyID field.
signingKey := t.Header.SigningKey
if signingKey == nil {
// Find the key in the given collection of trusted keys.
trustedKey, ok := verifyOpts.TrustedKeys[t.Header.KeyID]
if !ok {
log.Errorf("token signed by untrusted key with ID: %q", t.Header.KeyID)
return ErrInvalidToken
}
signingKey = trustedKey
}
// First verify the signature of the token using the key which signed it.
if err := signingKey.Verify(strings.NewReader(t.Raw), t.Header.SigningAlg, t.Signature); err != nil {
log.Errorf("unable to verify token signature: %s", err)
return ErrInvalidToken
}
// Next, check if the signing key is one of the trusted keys.
if _, isTrustedKey := verifyOpts.TrustedKeys[signingKey.KeyID()]; isTrustedKey {
// We're done! The token was signed by a trusted key and has been verified!
t.Valid = true
return nil
}
// Otherwise, we need to check the sigining keys included certificate chain.
return t.verifyCertificateChain(signingKey, verifyOpts.Roots)
}
// verifyCertificateChain attempts to verify the token using the "x5c" field
// of the given leafKey which was used to sign it. Returns a nil error if
// the key's certificate chain is valid and rooted an one of the given roots.
func (t *Token) verifyCertificateChain(leafKey libtrust.PublicKey, roots *x509.CertPool) error {
// In this case, the token signature is valid, but the key that signed it
// is not in our set of trusted keys. So, we'll need to check if the
// token's signing key included an x509 certificate chain that can be
// verified up to one of our trusted roots.
x5cVal, ok := leafKey.GetExtendedField("x5c").([]interface{})
if !ok || x5cVal == nil {
log.Error("unable to verify token signature: signed by untrusted key with no valid certificate chain")
return ErrInvalidToken
}
// Ensure each item is of the correct type.
x5c := make([]string, len(x5cVal))
for i, val := range x5cVal {
certString, ok := val.(string)
if !ok || len(certString) == 0 {
log.Error("unable to verify token signature: signed by untrusted key with malformed certificate chain")
return ErrInvalidToken
}
x5c[i] = certString
}
// Ensure the first element is encoded correctly.
leafCertDer, err := base64.StdEncoding.DecodeString(x5c[0])
if err != nil {
log.Errorf("unable to decode signing key leaf cert: %s", err)
return ErrInvalidToken
}
// And that it is a valid x509 certificate.
leafCert, err := x509.ParseCertificate(leafCertDer)
if err != nil {
log.Errorf("unable to parse signing key leaf cert: %s", err)
return ErrInvalidToken
}
// Verify that the public key in the leaf cert *is* the signing key.
leafCryptoKey, ok := leafCert.PublicKey.(crypto.PublicKey)
if !ok {
log.Error("unable to get signing key leaf cert public key value")
return ErrInvalidToken
}
leafPubKey, err := libtrust.FromCryptoPublicKey(leafCryptoKey)
if err != nil {
log.Errorf("unable to make libtrust public key from signing key leaf cert: %s", err)
return ErrInvalidToken
}
if leafPubKey.KeyID() != leafKey.KeyID() {
log.Error("token signing key ID and leaf certificate public key ID do not match")
return ErrInvalidToken
}
// The rest of the x5c array are intermediate certificates.
intermediates := x509.NewCertPool()
for i := 1; i < len(x5c); i++ {
intermediateCertDer, err := base64.StdEncoding.DecodeString(x5c[i])
if err != nil {
log.Errorf("unable to decode signing key intermediate cert: %s", err)
return ErrInvalidToken
}
intermediateCert, err := x509.ParseCertificate(intermediateCertDer)
if err != nil {
log.Errorf("unable to parse signing key intermediate cert: %s", err)
return ErrInvalidToken
}
intermediates.AddCert(intermediateCert)
}
verifyOpts := x509.VerifyOptions{
Intermediates: intermediates,
Roots: roots,
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
}
// TODO: this call returns certificate chains which we ignore for now, but
// we should check them for revocations if we have the ability later.
if _, err = leafCert.Verify(verifyOpts); err != nil {
log.Errorf("unable to verify signing key certificate: %s", err)
return ErrInvalidToken
}
// The signing key's x509 chain is valid!
t.Valid = true
return nil
}
// accessSet returns a set of actions available for the resource
// actions listed in the `access` section of this token.
func (t *Token) accessSet() accessSet {
if t.Claims == nil {
return nil
}
accessSet := make(accessSet, len(t.Claims.Access))
for _, resourceActions := range t.Claims.Access {
resource := auth.Resource{
Type: resourceActions.Type,
Name: resourceActions.Name,
}
set, exists := accessSet[resource]
if !exists {
set = newActionSet()
accessSet[resource] = set
}
for _, action := range resourceActions.Actions {
set.Add(action)
}
}
return accessSet
}
func (t *Token) compactRaw() string {
return fmt.Sprintf("%s.%s", t.Raw, joseBase64UrlEncode(t.Signature))
}