SystemSupportforCustom SpeculationPolicies - - PowerPoint PPT Presentation

system support for custom speculation policies
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SystemSupportforCustom SpeculationPolicies - - PowerPoint PPT Presentation

SystemSupportforCustom SpeculationPolicies BenjaminWester,PeterM.Chen UniversityofMichigan SOSP2009 Overview App App Policy App Policy Speculation Infrastructure Mechanism


slide-1
SLIDE 1

System
Support
for
Custom Speculation
Policies

Benjamin
Wester,
Peter
M.
Chen University
of
Michigan SOSP
2009

slide-2
SLIDE 2




App

Overview

Benjamin
Wester
‐
University
of
Michigan 2

Speculation Infrastructure

Mechanism App App Policy Policy

slide-3
SLIDE 3

Speculation
Policy

Default

  • Predict
system
calls
  • Allow
no

uncommitted
output

  • Commit
identical
results
  • Roll
back
after
any
change

Custom

  • Predict
arbitrary
operations
  • Allow
harmless

uncommitted
output

  • Commit
equivalent
results
  • Correction
appropriate
to

error

3 Benjamin
Wester
‐
University
of
Michigan

slide-4
SLIDE 4

Interface

Process

spec_fork()

Controlling
process Speculative
process try
to
establish
x

if (x) commit()

[else
rollback()]

4 Benjamin
Wester
‐
University
of
Michigan

allow_fd_output()

assume
x

Arbitrary operations Set output policy {allow, taint, defer, block} Define equivalence Error correction

slide-5
SLIDE 5

Uses

  • Predicting
user
actions

– Bash
shell

  • Authentication
  • User‐level
network
services

More?

5 Benjamin
Wester
‐
University
of
Michigan