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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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Jumanji: The Case for Dynamic NUCA in the Datacenter
The datacenter introduces new challenges for computer systems around tail latency and security. This paper argues that dynamic NUCA techniques are a better solution to these challenges than prior cache designs. We show that dynamic NUCA designs can meet tail-latency deadlines with much less cache space than prior work, and that they also provide a natural defense against cache attacks. Unfortunately, prior dynamic NUCAs have missed these opportunities because they focus exclusively on reducing data movement.We present Jumanji, a dynamic NUCA technique designed for tail latency and security. We show that prior last-level cache designs are vulnerable to new attacks and offer imperfect performance isolation. Jumanji solves these problems while significantly improving performance of co-running batch applications. Moreover, Jumanji only requires lightweight hardware and a few simple changes to system software, similar to prior D-NUCAs. At 20 cores, Jumanji improves batch weighted speedup by 14% on average, vs. just 2% for a non-NUCA design with weaker security, and is within 2% of an idealized design.
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- Award ID(s):
- 1845986
- PAR ID:
- 10281096
- Date Published:
- Journal Name:
- MICRO
- Page Range / eLocation ID:
- 665 to 680
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/MICRO50266.2020.00061
