indexed_db.md

IndexedDB

This page analyzes the Chromium IndexedDB component and potential security vulnerabilities.

Component Focus:

The focus of this page is on the Chromium IndexedDB component, specifically how it handles data storage and retrieval. The primary file of interest is content/browser/indexed_db/indexed_db_context_impl.cc.

Potential Logic Flaws:

• Insecure Data Storage: Vulnerabilities in how data is stored could lead to unauthorized access or data corruption.
• Man-in-the-Middle Attacks: Vulnerabilities in the communication protocol could allow an attacker to intercept and modify IndexedDB data.
• Incorrect Origin Handling: Incorrectly handled origins could allow a malicious website to access IndexedDB data from another website.
• Resource Leaks: Improper resource management could lead to memory leaks or other resource exhaustion issues.
• Bypassing Permissions: Logic flaws could allow an attacker to bypass permission checks for accessing IndexedDB data.
• Incorrect Data Validation: Improper validation of data could lead to vulnerabilities.
• Data Corruption: Vulnerabilities could lead to data corruption or loss.

Further Analysis and Potential Issues:

The IndexedDB implementation in Chromium is complex, involving multiple layers of checks and balances. It is important to analyze how IndexedDB databases are created, managed, and used. The indexed_db_context_impl.cc file is a key area to investigate. This file manages the core logic for IndexedDB and interacts with the quota manager.

• File: content/browser/indexed_db/indexed_db_context_impl.cc
  • This file implements the IndexedDBContextImpl class, which is used to manage IndexedDB.
  • Key functions to analyze include: BindIndexedDB, DeleteBucketData, ForceClose, StartMetadataRecording, StopMetadataRecording, DownloadBucketData, GetAllBucketsDetails, ApplyPolicyUpdates, GetBaseDataPathForTesting, GetFilePathForTesting, ResetCachesForTesting, WriteToIndexedDBForTesting, GetPathForBlobForTesting, CompactBackingStoreForTesting, GetUsageForTesting, GetSchedulingPriorityForTesting, InitializeFromFilesIfNeeded, ShutdownOnIDBSequence, GetBucketDiskUsage, NotifyOfBucketModification.
  • The IndexedDBContextImpl uses QuotaManagerProxy to manage storage quotas.
  • The BucketContext class is used to manage individual IndexedDB buckets.

Code Analysis:

// Example code snippet from indexed_db_context_impl.cc
void IndexedDBContextImpl::BindIndexedDB(
    const BucketLocator& bucket_locator,
    const storage::BucketClientInfo& client_info,
    mojo::PendingRemote<storage::mojom::IndexedDBClientStateChecker>
        client_state_checker_remote,
    mojo::PendingReceiver<blink::mojom::IDBFactory> receiver) {
  auto on_got_bucket = base::BindOnce(
      &IndexedDBContextImpl::BindIndexedDBImpl, weak_factory_.GetWeakPtr(),
      client_info, std::move(client_state_checker_remote), std::move(receiver));

  if (bucket_locator.is_default) {
    // If it's for a default bucket, `bucket_locator` will be a placeholder
    // without an ID, meaning the bucket still needs to be created.
    quota_manager_proxy_->UpdateOrCreateBucket(
        storage::BucketInitParams::ForDefaultBucket(bucket_locator.storage_key),
        idb_task_runner_, std::move(on_got_bucket));
  } else {
    // Query the database to make sure the bucket still exists.
    quota_manager_proxy_->GetBucketById(bucket_locator.id, idb_task_runner_,
                                        std::move(on_got_bucket));
  }
}

Areas Requiring Further Investigation:

• How are IndexedDB databases created and destroyed?
• How is data stored and retrieved by the LevelDB backend?
• How are permissions for IndexedDB access handled?
• How are different types of IndexedDB operations (e.g., open, delete, transaction) handled?
• How are errors handled during IndexedDB operations?
• How are resources (e.g., memory, disk) managed?
• How are IndexedDB databases handled in different contexts (e.g., incognito mode, extensions)?
• How are IndexedDB databases handled across different processes?
• How are IndexedDB databases handled for cross-origin requests?
• How does the QuotaManagerProxy work and how are storage quotas managed?
• How does the BucketContext class work and how are individual buckets managed?
• How are database migrations handled?

Secure Contexts and IndexedDB:

Secure contexts are important for IndexedDB. The IndexedDB API should only be accessible from secure contexts to prevent unauthorized access to stored data.

Privacy Implications:

The IndexedDB API has significant privacy implications. Incorrectly handled IndexedDB data could allow websites to access sensitive user data without proper consent. It is important to ensure that the IndexedDB API is implemented in a way that protects user privacy.

Additional Notes:

• The IndexedDB implementation is constantly evolving, so it is important to stay up-to-date with the latest changes.
• The IndexedDB implementation is closely tied to the security model of Chromium, so it is important to understand the overall security architecture.
• The IndexedDBContextImpl relies on a QuotaManagerProxy to manage storage quotas. The implementation of this proxy is important to understand.