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Randomization has proven to be a good defense against conflictbased side-channel attacks in a shared cache. It improves security by assigning a unique randomization scheme to each security domain, e.g., though a different hashing function. However, if two domains have shared data, the domains must be fused in order to guarantee correctness (i.e., data coherence). Such domain fusion significantly reduces the effectiveness of randomization and weakens its security protection. We propose randomization with sharing (RAWS), which enables secure cross-domain accesses while enforcing cache coherence (and thus data coherence). Based on RAWS, we design a non-fusion based inter-domain coherence protocol (NF-IDCP). NF-IDCP enables cache coherence by looking up and flushing multiple cache lines associated with shared-writable data during their cross-domain accesses. Furthermore, NF-IDCP uses constant-delay banking to securely reduce the latency of the cache line flushes. We also use a secure tag-based filter (STF) to reduce flush costs, for example, by explicitly storing the exact cache locations to be flushed. The security evaluation shows that conflict attacks on the optimized NF-IDCP structures cannot leak conflict observations at a meaningful rate. Attack simulations using CacheFX demonstrate that domain fusion significantly retards the protection provided by randomization schemes. Performance overhead of SPECrate 2017 and PARSEC 3.0 benchmarks is evaluated on ZSim, a microarchitectural simulator. To study the performance impact on realistic workloads, such as Firefox, Chromium and X Server, we use a cache simulator built on top of PANDA, a full-system emulator. Across all configurations, the average performance overhead is less than 5%, and the hardware overhead is less than 3% compared to a domainfused randomization.
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Horus: Persistent Security for Extended Persistence-Domain Memory Systems
Persistent memory presents a great opportunity for crash-consistent computing in large-scale computing systems. The ability to recover data upon power outage or crash events can significantly improve the availability of large-scale systems, while improving the performance of persistent data applications (e.g., database applications). However, persistent memory suffers from high write latency and requires specific programming model (e.g., Intel’s PMDK) to guarantee crash consistency, which results in long latency to persist data. To mitigate these problems, recent standards advocate for sufficient back-up power that can flush the whole cache hierarchy to the persistent memory upon detection of an outage, i.e., extending the persistence domain to include the cache hierarchy. In the secure NVM with extended persistent domain(EPD), in addition to flushing the cache hierarchy, extra actions need to be taken to protect the flushed cache data. These extra actions of secure operation could cause significant burden on energy costs and battery size. We demonstrate that naive implementations could lead to significantly expanding the required power holdup budget (e.g., 10.3x more operations than EPD system without secure memory support). The significant overhead is caused by memory accesses of secure metadata. In this paper, we present Horus, a novel EPD-aware secure memory implementation. Horus reduces the overhead during draining period of EPD system by reducing memory accesses of secure metadata. Experiment result shows that Horus reduces the draining time by 5x, compared with the naive baseline design.
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- PAR ID:
- 10396093
- Publisher / Repository:
- IEEE/ACM
- Date Published:
- Journal Name:
- 2022 55th IEEE/ACM International Symposium on Microarchitecture (MICRO)
- Page Range / eLocation ID:
- 1255 to 1269
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/MICRO56248.2022.00087
