etcdserver: verify field 'username' and 'revision' present when decoding a JWT token

Signed-off-by: Benjamin Wang <wachao@vmware.com>

server/auth/jwt.go

@@ -42,7 +42,7 @@ func (t *tokenJWT) info(ctx context.Context, token string, rev uint64) (*AuthInf
 	// rev isn't used in JWT, it is only used in simple token
 	var (
 		username string
-		revision uint64
+		revision float64
 	)
 
 	parsed, err := jwt.Parse(token, func(token *jwt.Token) (interface{}, error) {
@@ -74,10 +74,19 @@ func (t *tokenJWT) info(ctx context.Context, token string, rev uint64) (*AuthInf
 		return nil, false
 	}
 
-	username = claims["username"].(string)
+	username, ok = claims["username"].(string)
-	revision = uint64(claims["revision"].(float64))
+	if !ok {
+		t.lg.Warn("failed to obtain user claims from jwt token")
+		return nil, false
+	}
 
-	return &AuthInfo{Username: username, Revision: revision}, true
+	revision, ok = claims["revision"].(float64)
+	if !ok {
+		t.lg.Warn("failed to obtain revision claims from jwt token")
+		return nil, false
+	}
+
+	return &AuthInfo{Username: username, Revision: uint64(revision)}, true
 }
 
 func (t *tokenJWT) assign(ctx context.Context, username string, revision uint64) (string, error) {

server/auth/jwt_test.go

@@ -18,7 +18,10 @@ import (
 	"context"
 	"fmt"
 	"testing"
+	"time"
 
+	"github.com/golang-jwt/jwt/v4"
+	"github.com/stretchr/testify/require"
 	"go.uber.org/zap"
 )
 
@@ -202,3 +205,75 @@ func TestJWTBad(t *testing.T) {
 func testJWTOpts() string {
 	return fmt.Sprintf("%s,pub-key=%s,priv-key=%s,sign-method=RS256", tokenTypeJWT, jwtRSAPubKey, jwtRSAPrivKey)
 }
+
+func TestJWTTokenWithMissingFields(t *testing.T) {
+	testCases := []struct {
+		name        string
+		username    string // An empty string means not present
+		revision    uint64 // 0 means not present
+		expectValid bool
+	}{
+		{
+			name:        "valid token",
+			username:    "hello",
+			revision:    100,
+			expectValid: true,
+		},
+		{
+			name:        "no username",
+			username:    "",
+			revision:    100,
+			expectValid: false,
+		},
+		{
+			name:        "no revision",
+			username:    "hello",
+			revision:    0,
+			expectValid: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		optsMap := map[string]string{
+			"priv-key":    jwtRSAPrivKey,
+			"sign-method": "RS256",
+			"ttl":         "1h",
+		}
+
+		t.Run(tc.name, func(t *testing.T) {
+			// prepare claims
+			claims := jwt.MapClaims{
+				"exp": time.Now().Add(time.Hour).Unix(),
+			}
+			if tc.username != "" {
+				claims["username"] = tc.username
+			}
+			if tc.revision != 0 {
+				claims["revision"] = tc.revision
+			}
+
+			// generate a JWT token with the given claims
+			var opts jwtOptions
+			err := opts.ParseWithDefaults(optsMap)
+			require.NoError(t, err)
+			key, err := opts.Key()
+			require.NoError(t, err)
+
+			tk := jwt.NewWithClaims(opts.SignMethod, claims)
+			token, err := tk.SignedString(key)
+			require.NoError(t, err)
+
+			// verify the token
+			jwtProvider, err := newTokenProviderJWT(zap.NewNop(), optsMap)
+			require.NoError(t, err)
+			ai, ok := jwtProvider.info(context.TODO(), token, 123)
+
+			require.Equal(t, tc.expectValid, ok)
+			if ok {
+				require.Equal(t, tc.username, ai.Username)
+				require.Equal(t, tc.revision, ai.Revision)
+			}
+		})
+	}
+}