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/
handle_secrets_rotate.go
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/
handle_secrets_rotate.go
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// Copyright 2021 the Exposure Notifications Verification Server authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rotation
import (
"context"
"fmt"
"net/http"
"path"
"time"
"github.com/google/exposure-notifications-server/pkg/logging"
"github.com/google/exposure-notifications-verification-server/internal/project"
"github.com/google/exposure-notifications-verification-server/pkg/database"
"github.com/hashicorp/go-multierror"
"go.opencensus.io/stats"
)
// HandleRotateSecrets handles secrets rotation.
func (c *Controller) HandleRotateSecrets() http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
logger := logging.FromContext(ctx).Named("rotation.HandleRotateSecrets")
logger.Debugw("starting")
defer logger.Debugw("finishing")
ok, err := c.db.TryLock(ctx, secretsRotationLock, c.config.MinTTL)
if err != nil {
logger.Errorw("failed to acquire lock", "error", err)
c.h.RenderJSON(w, http.StatusInternalServerError, err)
return
}
if !ok {
logger.Debugw("skipping (too early)")
c.h.RenderJSON(w, http.StatusOK, fmt.Errorf("too early"))
return
}
// If there are any errors, return them
if err := c.RotateSecrets(ctx); err != nil {
logger.Errorw("failed to rotate secrets", "error", err)
c.h.RenderJSON(w, http.StatusInternalServerError, err)
return
}
stats.Record(ctx, mSecretsSuccess.M(1))
c.h.RenderJSON(w, http.StatusOK, nil)
})
}
// RotateSecrets triggers a secret rotation. It does not take out a lock nor
// does it return an HTTP response. This is primarily used so other functions
// can perform initials ecrets bootstrapping.
func (c *Controller) RotateSecrets(ctx context.Context) error {
logger := logging.FromContext(ctx).Named("rotation.RotateSecrets")
var merr *multierror.Error
// API key database HMAC keys
func() {
logger.Debugw("rotating API key database HMAC keys")
defer logger.Debugw("finished rotating API key database HMAC keys")
typ := database.SecretTypeAPIKeyDatabaseHMAC
parent := "db-apikey-db-hmac"
minTTL := c.config.APIKeyDatabaseHMACKeyMinAge
maxTTL := time.Duration(0)
if err := c.rotateSecret(ctx, typ, parent, 128, minTTL, maxTTL); err != nil {
merr = multierror.Append(merr, fmt.Errorf("failed to rotate api key database hmac key: %w", err))
return
}
}()
// API key signature HMAC keys
func() {
logger.Debugw("rotating API key signature HMAC keys")
defer logger.Debugw("finished rotating API key signature HMAC keys")
typ := database.SecretTypeAPIKeySignatureHMAC
parent := "db-apikey-sig-hmac"
minTTL := c.config.APIKeySignatureHMACKeyMinAge
maxTTL := time.Duration(0)
if err := c.rotateSecret(ctx, typ, parent, 128, minTTL, maxTTL); err != nil {
merr = multierror.Append(merr, fmt.Errorf("failed to rotate api key signature hmac key: %w", err))
return
}
}()
// Cookie key rotation
func() {
logger.Debugw("rotating cookie keys")
defer logger.Debugw("finished rotating cookie keys")
typ := database.SecretTypeCookieKeys
parent := "cookie-keys"
minTTL := c.config.CookieKeyMinAge
maxTTL := c.config.CookieKeyMaxAge
if err := c.rotateSecret(ctx, typ, parent, 32+64, minTTL, maxTTL); err != nil {
merr = multierror.Append(merr, fmt.Errorf("failed to rotate cookie key: %w", err))
return
}
}()
// Phone number database HMAC
func() {
logger.Debugw("rotating phone number database HMAC keys")
defer logger.Debugw("finished rotating phone number database HMAC keys")
typ := database.SecretTypePhoneNumberDatabaseHMAC
parent := "db-phone-number-hmac"
minTTL := c.config.PhoneNumberDatabaseHMACKeyMinAge
maxTTL := c.config.PhoneNumberDatabaseHMACKeyMaxAge
if err := c.rotateSecret(ctx, typ, parent, 128, minTTL, maxTTL); err != nil {
merr = multierror.Append(merr, fmt.Errorf("failed to rotate phone number database hmac key: %w", err))
return
}
}()
// Verification code database HMAC
func() {
logger.Debugw("rotating verification code database HMAC keys")
defer logger.Debugw("finished rotating verification code database HMAC keys")
typ := database.SecretTypeVerificationCodeDatabaseHMAC
parent := "db-verification-code-hmac"
minTTL := c.config.VerificationCodeDatabaseHMACKeyMinAge
maxTTL := c.config.VerificationCodeDatabaseHMACKeyMaxAge
if err := c.rotateSecret(ctx, typ, parent, 128, minTTL, maxTTL); err != nil {
merr = multierror.Append(merr, fmt.Errorf("failed to rotate verification code database hmac key: %w", err))
return
}
}()
return merr.ErrorOrNil()
}
// rotateAPIKeyHMAC rotates the key used to HMAC API keys stored in the
// database.
func (c *Controller) rotateSecret(ctx context.Context, typ database.SecretType, parent string, numBytes int, minTTL, maxTTL time.Duration) error {
now := time.Now().UTC()
logger := logging.FromContext(ctx).Named("rotateSecret").
With("type", typ).
With("parent", parent).
With("num_bytes", numBytes).
With("min_ttl", minTTL).
With("max_ttl", maxTTL)
existing, err := c.db.ListSecretsForType(typ)
if err != nil {
return fmt.Errorf("failed to lookup existing secrets: %w", err)
}
// Find the "newest" secret that has been created. Since ListSecretsForType
// sorts by usable, it's possible that a new secret exists but is not yet
// active. That would be at the end of the list.
latestSecretCreatedAt := time.Time{}
for _, secret := range existing {
if secret.CreatedAt.UTC().After(latestSecretCreatedAt) {
latestSecretCreatedAt = secret.CreatedAt.UTC()
}
}
logger.Debugw("calculated latest secret created time",
"created_at", latestSecretCreatedAt,
"ttl", now.Sub(latestSecretCreatedAt),
"secrets", existing)
// If there is no latest secret, or if the latest secret has existed for
// longer than the minimum age, create a new one.
if minTTL > 0 && now.Sub(latestSecretCreatedAt) > minTTL {
logger.Infow("latest secret does not exist or is older than min_ttl, creating new secret",
"secret", existing)
ref, err := c.createUpstreamSecretVersion(ctx, parent, numBytes)
if err != nil {
return fmt.Errorf("failed to create new secret version: %w", err)
}
secret := &database.Secret{
Type: typ,
Reference: ref,
Active: len(existing) == 0,
}
if err := c.db.SaveSecret(secret, RotationActor); err != nil {
return fmt.Errorf("failed to save new secret %s: %w", ref, err)
}
existing = append(existing, secret)
}
logger.Debugw("activating existing secrets")
for _, secret := range existing {
modified := secret.CreatedAt.UTC() != secret.UpdatedAt.UTC()
createdTTL := now.Sub(secret.CreatedAt.UTC())
updatedTTL := now.Sub(secret.UpdatedAt.UTC())
logger = logger.With(
"secret", secret,
"modified", modified,
"created_ttl", createdTTL,
"updated_ttl", updatedTTL)
logger.Debugw("checking if secret is ready to be activated")
// Activate any secrets that are ready to be activated. Please don't try to
// optimize this. Yes, this could be reduced into a single SQL statement,
// but we want to ensure the logging and AuditLog exist for debugging.
if !secret.Active && !modified && createdTTL >= c.config.SecretActivationTTL {
logger.Infow("activating secret", "secret", secret)
secret.Active = true
if err := c.db.SaveSecret(secret, RotationActor); err != nil {
return fmt.Errorf("failed to activate secret %d: %w", secret.ID, err)
}
}
// If a maximum TTL was given, check for expirations.
if maxTTL > 0 {
logger.Debugw("checking secret is expired")
// If the secret has existed for longer than the maximum TTL, deactivate
// it. This will move it to the end of the list. For HMAC-style secrets,
// this means it will still be available to validate values as the cache
// updates, but will not be used to HMAC new values.
if secret.Active && createdTTL >= maxTTL {
logger.Infow("deactivating expired secret", "secret", secret)
secret.Active = false
if err := c.db.SaveSecret(secret, RotationActor); err != nil {
return fmt.Errorf("failed to deactivate secret %d: %w", secret.ID, err)
}
}
// If the secret is inactive, experienced an update, and the time since
// that update has exceeded the activation TTL, mark the secret for
// deletion.
//
// The only mutable field is "Active", so if CreatedAt and UpdatedAt have
// diverged, it means the secret was previously activated and is now
// deactivated.
//
// Without this check, a secret with a low TTL could be marked for
// deletion before activation.
if !secret.Active && modified && updatedTTL >= c.config.SecretActivationTTL {
logger.Infow("marking secret for deletion", "secret", secret)
if err := c.db.DeleteSecret(secret, RotationActor); err != nil {
return fmt.Errorf("failed to mark secret %d for deletion: %w", secret.ID, err)
}
}
}
}
logger.Debugw("checking for secrets to purge")
// Hard delete any secrets that are marked for deletion and have exceeded
// the destroy TTL.
toDelete, err := c.db.ListSecretsForType(typ, database.Unscoped())
if err != nil {
return fmt.Errorf("failed to list unscoped secrets for type %s: %w", typ, err)
}
for _, secret := range toDelete {
deletedAt := secret.DeletedAt
if deletedAt != nil {
t := deletedAt.UTC()
deletedAt = &t
}
if deletedAt != nil && now.Sub(*deletedAt) > c.config.SecretDestroyTTL {
logger.Infow("purging expired secret", "secret", secret)
if err := c.destroyUpstreamSecretVersion(ctx, secret.Reference); err != nil {
return fmt.Errorf("failed to destroy %s: %w", secret.Reference, err)
}
if err := c.db.PurgeSecret(secret, RotationActor); err != nil {
return fmt.Errorf("failed to purge secret %d: %w", secret.ID, err)
}
}
}
return nil
}
// createUpstreamSecretVersion creates an upstream secret version in the secret
// manager.
func (c *Controller) createUpstreamSecretVersion(ctx context.Context, name string, numBytes int) (string, error) {
b, err := project.RandomBytes(numBytes)
if err != nil {
return "", fmt.Errorf("failed to generate %d, bytes for secret: %w", numBytes, err)
}
pth := path.Join(c.config.SecretsParent, name)
version, err := c.secretManager.CreateSecretVersion(ctx, pth, b)
if err != nil {
return "", fmt.Errorf("failed to add secret version: %w", err)
}
return version, nil
}
func (c *Controller) destroyUpstreamSecretVersion(ctx context.Context, name string) error {
if err := c.secretManager.DestroySecretVersion(ctx, name); err != nil {
return fmt.Errorf("failed to destroy upstream secret version: %w", err)
}
return nil
}