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sts: limit session duration to incoming token's exp claim (#7670)

* sts: limit session duration to incoming token's exp claim

This fixes the issue where AssumeRoleWithWebIdentity would issue sessions
that outlive the source identity token's expiration.

For use cases like GitLab CI Jobs where the ID Token has an exp claim
limited to the CI job's timeout, the STS session should not exceed that
expiration.

Changes:
- Add TokenExpiration field to ExternalIdentity struct
- Extract exp/iat/nbf claims in OIDC provider's ValidateToken
- Pass token expiration from Authenticate to ExternalIdentity
- Modify calculateSessionDuration to cap at source token's exp
- Add comprehensive tests for the new behavior

Fixes: https://github.com/seaweedfs/seaweedfs/discussions/7653

* refactor: reduce duplication in time claim extraction

Use a loop over claim names instead of repeating the same
extraction logic three times for exp, iat, and nbf claims.

* address review: add defense-in-depth for expired tokens

- Handle already-expired tokens defensively with 1 minute minimum duration
- Enforce MaxSessionLength from config as additional cap
- Fix potential nil dereference in test mock
- Add test case for expired token scenario

* remove issue reference from test

* fix: remove early return to ensure MaxSessionLength is always checked
pull/7674/head
Chris Lu 1 day ago
committed by GitHub
parent
commit
ff4855dcbe
No known key found for this signature in database GPG Key ID: B5690EEEBB952194
  1. 30
      weed/iam/oidc/oidc_provider.go
  2. 4
      weed/iam/providers/provider.go
  3. 46
      weed/iam/sts/sts_service.go
  4. 209
      weed/iam/sts/sts_service_test.go

30
weed/iam/oidc/oidc_provider.go

@ -186,14 +186,22 @@ func (p *OIDCProvider) Authenticate(ctx context.Context, token string) (*provide
attributes["roles"] = strings.Join(roles, ",")
}
return &providers.ExternalIdentity{
identity := &providers.ExternalIdentity{
UserID: claims.Subject,
Email: email,
DisplayName: displayName,
Groups: groups,
Attributes: attributes,
Provider: p.name,
}, nil
}
// Pass the token expiration to limit session duration
// This ensures the STS session doesn't exceed the source token's validity
if !claims.ExpiresAt.IsZero() {
identity.TokenExpiration = &claims.ExpiresAt
}
return identity, nil
}
// GetUserInfo retrieves user information from the UserInfo endpoint
@ -372,6 +380,24 @@ func (p *OIDCProvider) ValidateToken(ctx context.Context, token string) (*provid
Claims: make(map[string]interface{}),
}
// Extract time-based claims (exp, iat, nbf)
for key, target := range map[string]*time.Time{
"exp": &tokenClaims.ExpiresAt,
"iat": &tokenClaims.IssuedAt,
"nbf": &tokenClaims.NotBefore,
} {
if val, ok := claims[key]; ok {
switch v := val.(type) {
case float64:
*target = time.Unix(int64(v), 0)
case json.Number:
if intVal, err := v.Int64(); err == nil {
*target = time.Unix(intVal, 0)
}
}
}
}
// Copy all claims
for key, value := range claims {
tokenClaims.Claims[key] = value

4
weed/iam/providers/provider.go

@ -47,6 +47,10 @@ type ExternalIdentity struct {
// Provider is the name of the identity provider
Provider string `json:"provider"`
// TokenExpiration is the expiration time of the source identity token
// This is used to limit session duration to not exceed the token's exp claim
TokenExpiration *time.Time `json:"tokenExpiration,omitempty"`
}
// Validate validates the external identity structure

46
weed/iam/sts/sts_service.go

@ -422,8 +422,9 @@ func (s *STSService) AssumeRoleWithWebIdentity(ctx context.Context, request *Ass
return nil, fmt.Errorf("role assumption denied: %w", err)
}
// 3. Calculate session duration
sessionDuration := s.calculateSessionDuration(request.DurationSeconds)
// 3. Calculate session duration, capping at the source token's expiration
// This ensures sessions from short-lived tokens (e.g., GitLab CI job tokens) don't outlive their source
sessionDuration := s.calculateSessionDuration(request.DurationSeconds, externalIdentity.TokenExpiration)
expiresAt := time.Now().Add(sessionDuration)
// 4. Generate session ID and credentials
@ -502,7 +503,8 @@ func (s *STSService) AssumeRoleWithCredentials(ctx context.Context, request *Ass
}
// 4. Calculate session duration
sessionDuration := s.calculateSessionDuration(request.DurationSeconds)
// For credential-based auth, there's no source token with expiration to cap against
sessionDuration := s.calculateSessionDuration(request.DurationSeconds, nil)
expiresAt := time.Now().Add(sessionDuration)
// 5. Generate session ID and temporary credentials
@ -745,14 +747,42 @@ func (s *STSService) validateRoleAssumptionForCredentials(ctx context.Context, r
return nil
}
// calculateSessionDuration calculates the session duration
func (s *STSService) calculateSessionDuration(durationSeconds *int64) time.Duration {
// calculateSessionDuration calculates the session duration, respecting the source token's expiration
// If the incoming web identity token has an exp claim, the session duration is capped to not exceed it
// This ensures that sessions from short-lived tokens (e.g., GitLab CI job tokens) don't outlive their source
func (s *STSService) calculateSessionDuration(durationSeconds *int64, tokenExpiration *time.Time) time.Duration {
var duration time.Duration
if durationSeconds != nil {
return time.Duration(*durationSeconds) * time.Second
duration = time.Duration(*durationSeconds) * time.Second
} else {
// Use default from config
duration = s.Config.TokenDuration.Duration
}
// If the source token has an expiration, cap the session duration to not exceed it
// This follows the principle: "if calculated exp > incoming exp claim, then limit outgoing exp to incoming exp"
if tokenExpiration != nil && !tokenExpiration.IsZero() {
timeUntilTokenExpiry := time.Until(*tokenExpiration)
if timeUntilTokenExpiry <= 0 {
// Token already expired - use minimal duration as defense-in-depth
// The token should have been rejected during validation, but we handle this defensively
glog.V(2).Infof("Source token already expired, using minimal session duration")
duration = time.Minute
} else if timeUntilTokenExpiry < duration {
glog.V(2).Infof("Limiting session duration from %v to %v based on source token expiration",
duration, timeUntilTokenExpiry)
duration = timeUntilTokenExpiry
}
}
// Cap at MaxSessionLength if configured
if s.Config.MaxSessionLength.Duration > 0 && duration > s.Config.MaxSessionLength.Duration {
glog.V(2).Infof("Limiting session duration from %v to %v based on MaxSessionLength config",
duration, s.Config.MaxSessionLength.Duration)
duration = s.Config.MaxSessionLength.Duration
}
// Use default from config
return s.Config.TokenDuration.Duration
return duration
}
// extractSessionIdFromToken extracts session ID from JWT session token

209
weed/iam/sts/sts_service_test.go

@ -451,3 +451,212 @@ func (m *MockIdentityProvider) ValidateToken(ctx context.Context, token string)
}
return nil, fmt.Errorf("invalid token")
}
// TestSessionDurationCappedByTokenExpiration tests that session duration is capped by the source token's exp claim
func TestSessionDurationCappedByTokenExpiration(t *testing.T) {
service := NewSTSService()
config := &STSConfig{
TokenDuration: FlexibleDuration{time.Hour}, // Default: 1 hour
MaxSessionLength: FlexibleDuration{time.Hour * 12},
Issuer: "test-sts",
SigningKey: []byte("test-signing-key-32-characters-long"),
}
err := service.Initialize(config)
require.NoError(t, err)
tests := []struct {
name string
durationSeconds *int64
tokenExpiration *time.Time
expectedMaxSeconds int64
description string
}{
{
name: "no token expiration - use default duration",
durationSeconds: nil,
tokenExpiration: nil,
expectedMaxSeconds: 3600, // 1 hour default
description: "When no token expiration is set, use the configured default duration",
},
{
name: "token expires before default duration",
durationSeconds: nil,
tokenExpiration: timePtr(time.Now().Add(30 * time.Minute)),
expectedMaxSeconds: 30 * 60, // 30 minutes
description: "When token expires in 30 min, session should be capped at 30 min",
},
{
name: "token expires after default duration - use default",
durationSeconds: nil,
tokenExpiration: timePtr(time.Now().Add(2 * time.Hour)),
expectedMaxSeconds: 3600, // 1 hour default, since it's less than 2 hour token expiry
description: "When token expires after default duration, use the default duration",
},
{
name: "requested duration shorter than token expiry",
durationSeconds: int64Ptr(1800), // 30 min requested
tokenExpiration: timePtr(time.Now().Add(time.Hour)),
expectedMaxSeconds: 1800, // 30 minutes as requested
description: "When requested duration is shorter than token expiry, use requested duration",
},
{
name: "requested duration longer than token expiry - cap at token expiry",
durationSeconds: int64Ptr(3600), // 1 hour requested
tokenExpiration: timePtr(time.Now().Add(15 * time.Minute)),
expectedMaxSeconds: 15 * 60, // Capped at 15 minutes
description: "When requested duration exceeds token expiry, cap at token expiry",
},
{
name: "GitLab CI short-lived token scenario",
durationSeconds: nil,
tokenExpiration: timePtr(time.Now().Add(5 * time.Minute)),
expectedMaxSeconds: 5 * 60, // 5 minutes
description: "GitLab CI job with 5 minute timeout should result in 5 minute session",
},
{
name: "already expired token - defense in depth",
durationSeconds: nil,
tokenExpiration: timePtr(time.Now().Add(-5 * time.Minute)), // Expired 5 minutes ago
expectedMaxSeconds: 60, // 1 minute minimum
description: "Already expired token should result in minimal 1 minute session",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
duration := service.calculateSessionDuration(tt.durationSeconds, tt.tokenExpiration)
// Allow 5 second tolerance for time calculations
maxExpected := time.Duration(tt.expectedMaxSeconds+5) * time.Second
minExpected := time.Duration(tt.expectedMaxSeconds-5) * time.Second
assert.GreaterOrEqual(t, duration, minExpected,
"%s: duration %v should be >= %v", tt.description, duration, minExpected)
assert.LessOrEqual(t, duration, maxExpected,
"%s: duration %v should be <= %v", tt.description, duration, maxExpected)
})
}
}
// TestAssumeRoleWithWebIdentityRespectsTokenExpiration tests end-to-end that session duration is capped
func TestAssumeRoleWithWebIdentityRespectsTokenExpiration(t *testing.T) {
service := NewSTSService()
config := &STSConfig{
TokenDuration: FlexibleDuration{time.Hour},
MaxSessionLength: FlexibleDuration{time.Hour * 12},
Issuer: "test-sts",
SigningKey: []byte("test-signing-key-32-characters-long"),
}
err := service.Initialize(config)
require.NoError(t, err)
// Set up mock trust policy validator
mockValidator := &MockTrustPolicyValidator{}
service.SetTrustPolicyValidator(mockValidator)
// Create a mock provider that returns tokens with short expiration
shortLivedTokenExpiration := time.Now().Add(10 * time.Minute)
mockProvider := &MockIdentityProviderWithExpiration{
name: "short-lived-issuer",
tokenExpiration: &shortLivedTokenExpiration,
}
service.RegisterProvider(mockProvider)
ctx := context.Background()
// Create a JWT token with short expiration
token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
"iss": "short-lived-issuer",
"sub": "test-user",
"aud": "test-client",
"exp": shortLivedTokenExpiration.Unix(),
"iat": time.Now().Unix(),
})
tokenString, err := token.SignedString([]byte("test-signing-key"))
require.NoError(t, err)
request := &AssumeRoleWithWebIdentityRequest{
RoleArn: "arn:aws:iam::role/TestRole",
WebIdentityToken: tokenString,
RoleSessionName: "test-session",
}
response, err := service.AssumeRoleWithWebIdentity(ctx, request)
require.NoError(t, err)
require.NotNil(t, response)
// Verify the session expires at or before the token expiration
// Allow 5 second tolerance
assert.True(t, response.Credentials.Expiration.Before(shortLivedTokenExpiration.Add(5*time.Second)),
"Session expiration (%v) should not exceed token expiration (%v)",
response.Credentials.Expiration, shortLivedTokenExpiration)
}
// MockIdentityProviderWithExpiration is a mock provider that returns tokens with configurable expiration
type MockIdentityProviderWithExpiration struct {
name string
tokenExpiration *time.Time
}
func (m *MockIdentityProviderWithExpiration) Name() string {
return m.name
}
func (m *MockIdentityProviderWithExpiration) GetIssuer() string {
return m.name
}
func (m *MockIdentityProviderWithExpiration) Initialize(config interface{}) error {
return nil
}
func (m *MockIdentityProviderWithExpiration) Authenticate(ctx context.Context, token string) (*providers.ExternalIdentity, error) {
// Parse the token to get subject
parsedToken, _, err := new(jwt.Parser).ParseUnverified(token, jwt.MapClaims{})
if err != nil {
return nil, fmt.Errorf("failed to parse token: %w", err)
}
claims, ok := parsedToken.Claims.(jwt.MapClaims)
if !ok {
return nil, fmt.Errorf("invalid claims")
}
subject, _ := claims["sub"].(string)
identity := &providers.ExternalIdentity{
UserID: subject,
Email: subject + "@example.com",
DisplayName: "Test User",
Provider: m.name,
TokenExpiration: m.tokenExpiration,
}
return identity, nil
}
func (m *MockIdentityProviderWithExpiration) GetUserInfo(ctx context.Context, userID string) (*providers.ExternalIdentity, error) {
return &providers.ExternalIdentity{
UserID: userID,
Provider: m.name,
}, nil
}
func (m *MockIdentityProviderWithExpiration) ValidateToken(ctx context.Context, token string) (*providers.TokenClaims, error) {
claims := &providers.TokenClaims{
Subject: "test-user",
Issuer: m.name,
}
if m.tokenExpiration != nil {
claims.ExpiresAt = *m.tokenExpiration
}
return claims, nil
}
func timePtr(t time.Time) *time.Time {
return &t
}
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