Files
codex/codex-rs/core/README.md
viyatb-oai 95ba762620 fix: support split carveouts in windows restricted-token sandbox (#14172)
## Summary
- keep legacy Windows restricted-token sandboxing as the supported
baseline
- support the split-policy subset that restricted-token can enforce
directly today
- support full-disk read, the same writable root set as legacy
`WorkspaceWrite`, and extra read-only carveouts under those writable
roots via additional deny-write ACLs
- continue to fail closed for unsupported split-only shapes, including
explicit unreadable (`none`) carveouts, reopened writable descendants
under read-only carveouts, and writable root sets that do not match the
legacy workspace roots

## Example
Given a filesystem policy like:

```toml
":root" = "read"
":cwd" = "write"
"./docs" = "read"
```

the restricted-token backend can keep the workspace writable while
denying writes under `docs` by layering an extra deny-write carveout on
top of the legacy workspace-write roots.

A policy like:

```toml
"/workspace" = "write"
"/workspace/docs" = "read"
"/workspace/docs/tmp" = "write"
```

still fails closed, because the unelevated backend cannot reopen the
nested writable descendant safely.

## Stack
-> fix: support split carveouts in windows restricted-token sandbox
#14172
fix: support split carveouts in windows elevated sandbox #14568
2026-03-24 22:54:18 -07:00

4.8 KiB

codex-core

This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.

Dependencies

Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this support matrix is:

macOS

Expects /usr/bin/sandbox-exec to be present.

When using the workspace-write sandbox policy, the Seatbelt profile allows writes under the configured writable roots while keeping .git (directory or pointer file), the resolved gitdir: target, and .codex read-only.

Network access and filesystem read/write roots are controlled by SandboxPolicy. Seatbelt consumes the resolved policy and enforces it.

Seatbelt also supports macOS permission-profile extensions layered on top of SandboxPolicy:

  • no extension profile provided: keeps legacy default preferences read access (user-preference-read).
  • extension profile provided with no macos_preferences grant: does not add preferences access clauses.
  • macos_preferences = "readonly": enables cfprefs read clauses and user-preference-read.
  • macos_preferences = "readwrite": includes readonly clauses plus user-preference-write and cfprefs shm write clauses.
  • macos_automation = true: enables broad Apple Events send permissions.
  • macos_automation = ["com.apple.Notes", ...]: enables Apple Events send only to listed bundle IDs.
  • macos_launch_services = true: enables LaunchServices lookups and open/launch operations.
  • macos_accessibility = true: enables com.apple.axserver mach lookup.
  • macos_calendar = true: enables com.apple.CalendarAgent mach lookup.
  • macos_contacts = "read_only": enables Address Book read access and Contacts read services.
  • macos_contacts = "read_write": includes the readonly Contacts clauses plus Address Book writes and keychain/temp helpers required for writes.

Linux

Expects the binary containing codex-core to run the equivalent of codex sandbox linux (legacy alias: codex debug landlock) when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.

Legacy SandboxPolicy / sandbox_mode configs are still supported on Linux. They can continue to use the legacy Landlock path when the split filesystem policy is sandbox-equivalent to the legacy model after cwd resolution. Split filesystem policies that need direct FileSystemSandboxPolicy enforcement, such as read-only or denied carveouts under a broader writable root, automatically route through bubblewrap. The legacy Landlock path is used only when the split filesystem policy round-trips through the legacy SandboxPolicy model without changing semantics. That includes overlapping cases like /repo = write, /repo/a = none, /repo/a/b = write, where the more specific writable child must reopen under a denied parent.

The Linux sandbox helper prefers /usr/bin/bwrap whenever it is available and supports the required argv-rewrite flags, and falls back to the vendored bubblewrap path compiled into the binary otherwise. When /usr/bin/bwrap is missing or too old to support the required flags, Codex also surfaces a startup warning through its normal notification path instead of printing directly from the sandbox helper.

Windows

Legacy SandboxPolicy / sandbox_mode configs are still supported on Windows.

The elevated setup/runner backend supports legacy ReadOnlyAccess::Restricted for read-only and workspace-write policies. Restricted read access honors explicit readable roots plus the command cwd, and keeps writable roots readable when workspace-write is used.

When include_platform_defaults = true, the elevated Windows backend adds backend-managed system read roots required for basic execution, such as C:\Windows, C:\Program Files, C:\Program Files (x86), and C:\ProgramData. When it is false, those extra system roots are omitted.

The unelevated restricted-token backend still supports the legacy full-read Windows model for legacy ReadOnly and WorkspaceWrite behavior. It also supports a narrow split-filesystem subset: full-read split policies whose writable roots still match the legacy WorkspaceWrite root set, but add extra read-only carveouts under those writable roots.

New [permissions] / split filesystem policies remain supported on Windows only when they round-trip through the legacy SandboxPolicy model without changing semantics. Policies that would require direct read restriction, explicit unreadable carveouts, reopened writable descendants under read-only carveouts, different writable root sets, or split carveout support in the elevated setup/runner backend still fail closed instead of running with weaker enforcement.

All Platforms

Expects the binary containing codex-core to simulate the virtual apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the codex-arg0 crate for details.