[sandbox] Restrict pkey_alloc flags

The "flags" argument to pkey_alloc must currently always be zero.
Enforce this via the sandbox to pretect against future extensions.

R=rsesek@chromium.org

Bug: chromium:1229359
Change-Id: I9922701728facbe5a44466bb6fc8534ec797be27
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3028921
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#901869}
NOKEYCHECK=True
GitOrigin-RevId: 59d1fff9ed5d72b4ecf4d48f7e0710c6e5c19bfc
3 files changed
tree: d88e95ff3c670906378be63e8d3358f65ec5cee3
  1. linux/
  2. mac/
  3. policy/
  4. win/
  5. BUILD.gn
  6. constants.h
  7. DEPS
  8. DIR_METADATA
  9. features.gni
  10. ipc.dict
  11. OWNERS
  12. README.md
  13. 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.