decouple service accounts from root credentials (#14534)

changing root credentials makes service accounts
in-operable, this PR changes the way sessionToken
is generated for service accounts.

It changes service account behavior to generate
sessionToken claims from its own secret instead
of using global root credential.

Existing credentials will be supported by
falling back to verify using root credential.

fixes #14530

cmd/auth-handler.go

@@ -197,13 +197,7 @@ func mustGetClaimsFromToken(r *http.Request) map[string]interface{} {
 	return claims
 }
 
-// Fetch claims in the security token returned by the client.
-func getClaimsFromToken(token string) (map[string]interface{}, error) {
-	if token == "" {
-		claims := xjwt.NewMapClaims()
-		return claims.Map(), nil
-	}
-
+func getClaimsFromTokenWithSecret(token, secret string) (map[string]interface{}, error) {
 	// JWT token for x-amz-security-token is signed with admin
 	// secret key, temporary credentials become invalid if
 	// server admin credentials change. This is done to ensure
@@ -212,10 +206,16 @@ func getClaimsFromToken(token string) (map[string]interface{}, error) {
 	// hijacking the policies. We need to make sure that this is
 	// based an admin credential such that token cannot be decoded
 	// on the client side and is treated like an opaque value.
-	claims, err := auth.ExtractClaims(token, globalActiveCred.SecretKey)
+	claims, err := auth.ExtractClaims(token, secret)
+	if err != nil {
+		if subtle.ConstantTimeCompare([]byte(secret), []byte(globalActiveCred.SecretKey)) == 1 {
+			return nil, errAuthentication
+		}
+		claims, err = auth.ExtractClaims(token, globalActiveCred.SecretKey)
 		if err != nil {
 			return nil, errAuthentication
 		}
+	}
 
 	// If OPA is set, return without any further checks.
 	if globalPolicyOPA != nil {
@@ -241,23 +241,50 @@ func getClaimsFromToken(token string) (map[string]interface{}, error) {
 	return claims.Map(), nil
 }
 
+// Fetch claims in the security token returned by the client.
+func getClaimsFromToken(token string) (map[string]interface{}, error) {
+	return getClaimsFromTokenWithSecret(token, globalActiveCred.SecretKey)
+}
+
 // Fetch claims in the security token returned by the client and validate the token.
 func checkClaimsFromToken(r *http.Request, cred auth.Credentials) (map[string]interface{}, APIErrorCode) {
 	token := getSessionToken(r)
 	if token != "" && cred.AccessKey == "" {
+		// x-amz-security-token is not allowed for anonymous access.
 		return nil, ErrNoAccessKey
 	}
-	if cred.IsServiceAccount() && token == "" {
-		token = cred.SessionToken
-	}
-	if subtle.ConstantTimeCompare([]byte(token), []byte(cred.SessionToken)) != 1 {
+
+	if token == "" && cred.IsTemp() {
+		// Temporary credentials should always have x-amz-security-token
 		return nil, ErrInvalidToken
 	}
-	claims, err := getClaimsFromToken(token)
+
+	if token != "" && !cred.IsTemp() {
+		// x-amz-security-token should not present for static credentials.
+		return nil, ErrInvalidToken
+	}
+
+	if cred.IsTemp() && subtle.ConstantTimeCompare([]byte(token), []byte(cred.SessionToken)) != 1 {
+		// validate token for temporary credentials only.
+		return nil, ErrInvalidToken
+	}
+
+	secret := globalActiveCred.SecretKey
+	if cred.IsServiceAccount() {
+		token = cred.SessionToken
+		secret = cred.SecretKey
+	}
+
+	if token != "" {
+		claims, err := getClaimsFromTokenWithSecret(token, secret)
 		if err != nil {
 			return nil, toAPIErrorCode(r.Context(), err)
 		}
 		return claims, ErrNone
+	}
+
+	claims := xjwt.NewMapClaims()
+	return claims.Map(), ErrNone
 }
 
 // Check request auth type verifies the incoming http request

cmd/iam-store.go

@@ -1456,13 +1456,28 @@ func (store *IAMStoreSys) GetAllParentUsers() map[string]string {
 
 	res := map[string]string{}
 	for _, cred := range cache.iamUsersMap {
-		if cred.IsServiceAccount() || cred.IsTemp() {
+		if (cred.IsServiceAccount() || cred.IsTemp()) && cred.SessionToken != "" {
 			parentUser := cred.ParentUser
-			if cred.SessionToken != "" {
-				claims, err := getClaimsFromToken(cred.SessionToken)
+
+			var (
+				err    error
+				claims map[string]interface{}
+			)
+
+			if cred.IsServiceAccount() {
+				claims, err = getClaimsFromTokenWithSecret(cred.SessionToken, cred.SecretKey)
+				if err != nil {
+					claims, err = getClaimsFromTokenWithSecret(cred.SessionToken, globalActiveCred.SecretKey)
+				}
+			} else if cred.IsTemp() {
+				claims, err = getClaimsFromTokenWithSecret(cred.SessionToken, globalActiveCred.SecretKey)
+			}
+
 			if err != nil {
 				continue
 			}
+
+			if len(claims) > 0 {
 				if v, ok := claims[subClaim]; ok {
 					subFromToken, ok := v.(string)
 					if ok {
@@ -1470,6 +1485,11 @@ func (store *IAMStoreSys) GetAllParentUsers() map[string]string {
 					}
 				}
 			}
+
+			if parentUser == "" {
+				continue
+			}
+
 			if _, ok := res[parentUser]; !ok {
 				res[parentUser] = cred.ParentUser
 			}
@@ -1561,6 +1581,7 @@ func (store *IAMStoreSys) UpdateServiceAccount(ctx context.Context, accessKey st
 		return errNoSuchServiceAccount
 	}
 
+	currentSecretKey := cr.SecretKey
 	if opts.secretKey != "" {
 		if !auth.IsSecretKeyValid(opts.secretKey) {
 			return auth.ErrInvalidSecretKeyLength
@@ -1582,20 +1603,21 @@ func (store *IAMStoreSys) UpdateServiceAccount(ctx context.Context, accessKey st
 		return errors.New("unknown account status value")
 	}
 
-	if opts.sessionPolicy != nil {
-		m, err := getClaimsFromToken(cr.SessionToken)
+	m, err := getClaimsFromTokenWithSecret(cr.SessionToken, currentSecretKey)
 	if err != nil {
 		return fmt.Errorf("unable to get svc acc claims: %v", err)
 	}
 
-		err = opts.sessionPolicy.Validate()
-		if err != nil {
+	if opts.sessionPolicy != nil {
+		if err := opts.sessionPolicy.Validate(); err != nil {
 			return err
 		}
+
 		policyBuf, err := json.Marshal(opts.sessionPolicy)
 		if err != nil {
 			return err
 		}
+
 		if len(policyBuf) > 16*humanize.KiByte {
 			return fmt.Errorf("Session policy should not exceed 16 KiB characters")
 		}
@@ -1603,11 +1625,12 @@ func (store *IAMStoreSys) UpdateServiceAccount(ctx context.Context, accessKey st
 		// Overwrite session policy claims.
 		m[iampolicy.SessionPolicyName] = base64.StdEncoding.EncodeToString(policyBuf)
 		m[iamPolicyClaimNameSA()] = "embedded-policy"
-		cr.SessionToken, err = auth.JWTSignWithAccessKey(accessKey, m, globalActiveCred.SecretKey)
+	}
+
+	cr.SessionToken, err = auth.JWTSignWithAccessKey(accessKey, m, cr.SecretKey)
 	if err != nil {
 		return err
 	}
-	}
 
 	u := newUserIdentity(cr)
 	if err := store.saveUserIdentity(ctx, u.Credentials.AccessKey, svcUser, u); err != nil {

cmd/iam.go

@@ -37,6 +37,7 @@ import (
 	"github.com/minio/minio/internal/arn"
 	"github.com/minio/minio/internal/auth"
 	"github.com/minio/minio/internal/color"
+	"github.com/minio/minio/internal/jwt"
 	"github.com/minio/minio/internal/logger"
 	iampolicy "github.com/minio/pkg/iam/policy"
 	etcd "go.etcd.io/etcd/client/v3"
@@ -799,14 +800,17 @@ func (sys *IAMSys) NewServiceAccount(ctx context.Context, parentUser string, gro
 		}
 	}
 
-	var cred auth.Credentials
-
+	var accessKey, secretKey string
 	var err error
 	if len(opts.accessKey) > 0 {
-		cred, err = auth.CreateNewCredentialsWithMetadata(opts.accessKey, opts.secretKey, m, globalActiveCred.SecretKey)
+		accessKey, secretKey = opts.accessKey, opts.secretKey
 	} else {
-		cred, err = auth.GetNewCredentialsWithMetadata(m, globalActiveCred.SecretKey)
+		accessKey, secretKey, err = auth.GenerateCredentials()
+		if err != nil {
+			return auth.Credentials{}, err
 		}
+	}
+	cred, err := auth.CreateNewCredentialsWithMetadata(accessKey, secretKey, m, secretKey)
 	if err != nil {
 		return auth.Credentials{}, err
 	}
@@ -880,10 +884,13 @@ func (sys *IAMSys) getServiceAccount(ctx context.Context, accessKey string) (aut
 
 	var embeddedPolicy *iampolicy.Policy
 
-	jwtClaims, err := auth.ExtractClaims(sa.SessionToken, globalActiveCred.SecretKey)
+	jwtClaims, err := auth.ExtractClaims(sa.SessionToken, sa.SecretKey)
+	if err != nil {
+		jwtClaims, err = auth.ExtractClaims(sa.SessionToken, globalActiveCred.SecretKey)
 		if err != nil {
 			return auth.Credentials{}, nil, err
 		}
+	}
 	pt, ptok := jwtClaims.Lookup(iamPolicyClaimNameSA())
 	sp, spok := jwtClaims.Lookup(iampolicy.SessionPolicyName)
 	if ptok && spok && pt == "embedded-policy" {
@@ -915,10 +922,13 @@ func (sys *IAMSys) GetClaimsForSvcAcc(ctx context.Context, accessKey string) (ma
 		return nil, errNoSuchServiceAccount
 	}
 
-	jwtClaims, err := auth.ExtractClaims(sa.SessionToken, globalActiveCred.SecretKey)
+	jwtClaims, err := auth.ExtractClaims(sa.SessionToken, sa.SecretKey)
+	if err != nil {
+		jwtClaims, err = auth.ExtractClaims(sa.SessionToken, globalActiveCred.SecretKey)
 		if err != nil {
 			return nil, err
 		}
+	}
 	return jwtClaims.Map(), nil
 }
 
@@ -1063,12 +1073,28 @@ func (sys *IAMSys) updateGroupMembershipsForLDAP(ctx context.Context) {
 		if _, ok := parentUserToCredsMap[cred.ParentUser]; !ok {
 			// Try to find the ldapUsername for this
 			// parentUser by extracting JWT claims
-			jwtClaims, err := auth.ExtractClaims(cred.SessionToken, globalActiveCred.SecretKey)
-			if err != nil {
-				// skip this cred - session token seems
-				// invalid
+			var (
+				jwtClaims *jwt.MapClaims
+				err       error
+			)
+
+			if cred.SessionToken == "" {
 				continue
 			}
+
+			if cred.IsServiceAccount() {
+				jwtClaims, err = auth.ExtractClaims(cred.SessionToken, cred.SecretKey)
+				if err != nil {
+					jwtClaims, err = auth.ExtractClaims(cred.SessionToken, globalActiveCred.SecretKey)
+				}
+			} else {
+				jwtClaims, err = auth.ExtractClaims(cred.SessionToken, globalActiveCred.SecretKey)
+			}
+			if err != nil {
+				// skip this cred - session token seems invalid
+				continue
+			}
+
 			ldapUsername, ok := jwtClaims.Lookup(ldapUserN)
 			if !ok {
 				// skip this cred - we dont have the

cmd/jwt.go

@@ -132,7 +132,7 @@ func authenticateURL(accessKey, secretKey string) (string, error) {
 // Check if the request is authenticated.
 // Returns nil if the request is authenticated. errNoAuthToken if token missing.
 // Returns errAuthentication for all other errors.
-func webRequestAuthenticate(req *http.Request) (*xjwt.MapClaims, []string, bool, error) {
+func metricsRequestAuthenticate(req *http.Request) (*xjwt.MapClaims, []string, bool, error) {
 	token, err := jwtreq.AuthorizationHeaderExtractor.ExtractToken(req)
 	if err != nil {
 		if err == jwtreq.ErrNoTokenInRequest {

cmd/jwt_test.go

@@ -149,7 +149,7 @@ func TestWebRequestAuthenticate(t *testing.T) {
 	}
 
 	for i, testCase := range testCases {
-		_, _, _, gotErr := webRequestAuthenticate(testCase.req)
+		_, _, _, gotErr := metricsRequestAuthenticate(testCase.req)
 		if testCase.expectedErr != gotErr {
 			t.Errorf("Test %d, expected err %s, got %s", i+1, testCase.expectedErr, gotErr)
 		}

cmd/metrics.go

@@ -674,7 +674,7 @@ func metricsHandler() http.Handler {
 // AuthMiddleware checks if the bearer token is valid and authorized.
 func AuthMiddleware(h http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		claims, groups, owner, authErr := webRequestAuthenticate(r)
+		claims, groups, owner, authErr := metricsRequestAuthenticate(r)
 		if authErr != nil || !claims.VerifyIssuer("prometheus", true) {
 			w.WriteHeader(http.StatusForbidden)
 			return