Workload Sandboxing

How Fabric isolates workloads for security

Overview

Every workload on Fabric runs in a sandboxed environment. This protects:

  • Device owners from malicious code
  • Job submitters from data leaks
  • The network from compromised nodes

Sandbox Technology

Fabric uses OS-native sandboxing mechanisms for each platform:

macOS:

  • Uses Apple built-in sandboxing
  • Same technology used by App Store apps
  • No additional software required

Linux:

  • Uses kernel namespaces
  • Provides process, network, and filesystem isolation

Windows:

  • Uses restricted process tokens
  • Process group isolation
  • Limited system call access

What is Restricted

Network access:

  • Outbound network connections are blocked
  • Workloads cannot access the internet
  • Cannot communicate with other processes

Filesystem access:

  • Limited to temporary working directory
  • Cannot read system files
  • Cannot write outside workspace
  • Workspace is deleted after job completion

System calls:

  • Limited to necessary operations
  • Cannot access hardware directly
  • Cannot spawn unrestricted processes

What is Allowed

Read access:

  • System libraries (for Python packages to work)
  • Temporary workspace files
  • Input data provided by the job

Write access:

  • Temporary workspace only
  • Output files designated by the workload

Compute:

  • Full CPU access (within resource limits)
  • GPU access (if job requires it)
  • Memory up to configured limits

Resource Limits

Each job has configurable limits:

  • Timeout: Maximum execution time (default: 30 minutes)
  • Memory: Maximum RAM usage
  • CPU: Process priority

Jobs exceeding these limits are terminated and marked as failed.

Custom Workloads

Custom workloads uploaded by enterprises run with the same sandboxing.

The sandbox prevents custom code from:

  • Accessing the device owner files
  • Making network requests
  • Persisting data between jobs
  • Interfering with other processes

Proof of Execution

After each job, the agent generates a Proof of Execution containing:

  • SHA256 hash of workload code
  • SHA256 hash of input data
  • SHA256 hash of output
  • Execution timing
  • Anonymized node identifier

This provides verification that the job was executed correctly.

Privacy Protection

For device owners:

  • Your personal files are never accessible to workloads
  • Your identity is anonymized to job submitters
  • Workloads cannot exfiltrate data (no network access)

For job submitters:

  • Your code and data are processed in isolation
  • Other workloads cannot access your data
  • Results are uploaded securely