AI 中文总结
针对机密计算中存储面临的回滚等攻击问题，提出无需修改应用的ShieldFS文件系统，扩展ZFS得到ShieldZFS，实现强完整性与新鲜度保障且性能优异。
AI 中文摘要
机密计算通过可信执行环境（TEE）保护应用程序，但会使存储面临风险。即便使用磁盘加密，恶意云提供商仍可回滚、重放、分叉或篡改磁盘状态，破坏有状态应用所需的完整性和新鲜度保障。现有解决方案要么假设存储可信，要么开销过高，要么将完整性逻辑推给应用程序。我们提出ShieldFS，这是一款符合POSIX标准的文件系统，在机密计算威胁模型下为持久存储提供端到端完整性和新鲜度保障，无需修改应用程序。ShieldFS使用简洁的密码承诺表示允许的文件系统状态，这些状态在TEE内部维护并在轻量级可信注册表中复制。包括写前日志和存储池在内的磁盘上数据结构通过哈希链和嵌入的默克尔树进行认证。ShieldFS利用事务和写时复制原子性地更新持久文件系统状态和承诺。读取时会验证承诺，确保即使整个I/O栈不可信，也能检测到回滚、重放和歧义攻击。我们通过扩展ZFS实现该设计，得到ShieldZFS。使用标准文件系统基准和实际工作负载的评估显示，ShieldZFS在提供强完整性和新鲜度保障的同时，性能可与最先进的文件系统相媲美。
英文摘要
Confidential computing protects applications inside Trusted Execution Environments (TEEs), but it leaves storage vulnerable. Even with disk encryption, a malicious cloud provider can roll back, replay, fork, or tamper with disk state, breaking the integrity and freshness guarantees required by stateful applications. Existing solutions either assume trusted storage, incur high overheads, or push integrity logic into applications. We present ShieldFS, a POSIX-compliant filesystem that provides end-to-end integrity and freshness for persistent storage in the confidential-computing threat model without requiring application changes. ShieldFS represents permissible filesystem states using succinct cryptographic commitments, maintained inside TEEs and replicated in a lightweight trusted registry. On-disk data structures, including a write-ahead log and a storage pool, are authenticated using hash chains and an embedded Merkle tree. ShieldFS utilizes transactions and copy-on-write to update persistent filesystem state and commitments atomically. The commitments are verified during reads, ensuring that rollback, replay, and equivocation attacks are detected even when the entire I/O stack is untrusted. We implement the design by extending ZFS, yielding ShieldZFS. Evaluation with standard filesystem benchmarks and real-world workloads shows that ShieldZFS provides strong integrity and freshness guarantees with performance comparable to state-of-the-art filesystems.
