(Mis)managed: A Novel TLB-based Covert Channel on GPUs

Ajay Nayak, B. Pratheek, Vinod Ganapathy, Arkaprava Basu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

GPUs are now commonly available in most modern computing platforms. They are increasingly being adopted in cloud platforms and data centers due to their immense computing capability. In response to this growth in usage, manufacturers continuously try to improve GPU hardware by adding new features. However, this increase in usage and the addition of utility-improving features can create new, unexpected attack channels. In this paper, we show that two such features-unified virtual memory (UVM) and multi-process service (MPS)-primarily introduced to improve the programmability and efficiency of GPU kernels have an unexpected consequence-that of creating a novel covert-timing channel via the GPU's translation lookaside buffer (TLB) hierarchy. To enable this covert channel, we first perform experiments to understand the characteristics of TLBs present on a GPU. The use of UVM allows fine-grained management of translations, and helps us discover several idiosyncrasies of the TLB hierarchy, such as three-levels of TLB, coalesced entries. We use this newly-acquired understanding to demonstrate a novel covert channel via the shared TLB. We then leverage MPS to increase the bandwidth of this channel by 40×. Finally, we demonstrate the channel's utility by leaking data from a GPU-accelerated database application.

Original languageEnglish (US)
Title of host publicationASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery, Inc
Pages872-885
Number of pages14
ISBN (Electronic)9781450382878
DOIs
StatePublished - May 24 2021
Event16th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2021 - Virtual, Online, Hong Kong
Duration: Jun 7 2021Jun 11 2021

Publication series

NameASIA CCS 2021 - Proceedings of the 2021 ACM Asia Conference on Computer and Communications Security

Conference

Conference16th ACM Asia Conference on Computer and Communications Security, ASIA CCS 2021
Country/TerritoryHong Kong
CityVirtual, Online
Period6/7/216/11/21

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Computer Science Applications
  • Information Systems
  • Software

Keywords

  • covert-timing channel
  • GPU
  • multi-process service
  • reverse-engineering
  • TLB
  • unified memory

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