Linux sandbox: cleanup fstatfs usage in bpf policies

A Chrome OS glibc patch added fstatfs() calls to dlopen(), which causes
seccomp failures when dlopen() is called under various sandboxes.
This CL consolidates the allowances of fstatfs() under a
SyscallSets::IsDlopen() function, and allows it unconditionally in the
GPU process policy.

Change-Id: Ie96895f4ccda5d43b5c93808fc7839515fb62b61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3256943
Auto-Submit: Matthew Denton <mpdenton@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Commit-Queue: Matthew Denton <mpdenton@chromium.org>
Cr-Commit-Position: refs/heads/main@{#938520}
NOKEYCHECK=True
GitOrigin-RevId: 51c6555b3426cf7100c155993737d0aaf49e15e8
5 files changed
tree: 92fd697775ab985cc255a85b1c3d4492e4702650
  1. linux/
  2. mac/
  3. policy/
  4. win/
  5. BUILD.gn
  6. COMMON_METADATA
  7. constants.h
  8. DEPS
  9. DIR_METADATA
  10. features.gni
  11. ipc.dict
  12. OWNERS
  13. README.md
  14. sandbox_export.h
README.md

Sandbox Library

This directory contains platform-specific sandboxing libraries. Sandboxing is a technique that can improve the security of an application by separating untrustworthy code (or code that handles untrustworthy data) and restricting its privileges and capabilities.

Each platform relies on the operating system's process primitive to isolate code into distinct security principals, and platform-specific technologies are used to implement the privilege reduction. At a high-level:

  • mac/ uses the Seatbelt sandbox. See the detailed design for more.
  • linux/ uses namespaces and Seccomp-BPF. See the detailed design for more.
  • win/ uses a combination of restricted tokens, distinct job objects, alternate desktops, and integrity levels. See the detailed design for more.

Built on top of the low-level sandboxing library is the //sandbox/policy component, which provides concrete policies and helper utilities for sandboxing specific Chromium processes and services. The core sandbox library cannot depend on the policy component.