Files
codex/codex-rs/core
Michael Bolin 755880ef9c permissions: derive config defaults as profiles (#19772)
## Why

This continues the permissions migration by making legacy config default
resolution produce the canonical `PermissionProfile` first. The legacy
`SandboxPolicy` projection should stay available at compatibility
boundaries, but config loading should not create a legacy policy just to
immediately convert it back into a profile.

Specifically, when `default_permissions` is not specified in
`config.toml`, instead of creating a `SandboxPolicy` in
`codex-rs/core/src/config/mod.rs` and then trying to derive a
`PermissionProfile` from it, we use `derive_permission_profile()` to
create a more faithful `PermissionProfile` using the values of
`ConfigToml` directly.

This also keeps the existing behavior of `sandbox_workspace_write` and
extra writable roots after #19841 replaced `:cwd` with `:project_roots`.
Legacy workspace-write defaults are represented as symbolic
`:project_roots` write access plus symbolic project-root metadata
carveouts. Extra absolute writable roots are still added directly and
continue to get concrete metadata protections for paths that exist under
those roots.

The platform sandboxes differ when a symbolic project-root subpath does
not exist yet.

* **Seatbelt** can encode literal/subpath exclusions directly, so macOS
emits project-root metadata subpath policies even if `.git`, `.agents`,
or `.codex` do not exist.
* **bwrap** has to materialize bind-mount targets. Binding `/dev/null`
to a missing `.git` can create a host-visible placeholder that changes
Git repo discovery. Binding missing `.agents` would not affect Git
discovery, but it would still create a host-visible project metadata
placeholder from an automatic compatibility carveout. Linux therefore
skips only missing automatic `.git` and `.agents` read-only metadata
masks; missing `.codex` remains protected so first-time project config
creation goes through the protected-path approval flow. User-authored
`read` and `none` subpath rules keep normal bwrap behavior, and `none`
can still mask the first missing component to prevent creation under
writable roots.

## What Changed

- Adds profile-native helpers for legacy workspace-write semantics,
including `PermissionProfile::workspace_write_with()`,
`FileSystemSandboxPolicy::workspace_write()`, and
`FileSystemSandboxPolicy::with_additional_legacy_workspace_writable_roots()`.
- Makes `FileSystemSandboxPolicy::workspace_write()` the single legacy
workspace-write constructor so both `from_legacy_sandbox_policy()` and
`From<&SandboxPolicy>` include the project-root metadata carveouts.
- Removes the no-carveout `legacy_workspace_write_base_policy()` path
and the `prune_read_entries_under_writable_roots()` cleanup that was
only needed by that split construction.
- Adds `ConfigToml::derive_permission_profile()` for legacy sandbox-mode
fallback resolution; named `default_permissions` profiles continue
through the permissions profile pipeline instead of being reconstructed
from `sandbox_mode`.
- Updates `Config::load()` to start from the derived profile, validate
that it still has a legacy compatibility projection, and apply
additional writable roots directly to managed workspace-write filesystem
policies.
- Updates Linux bwrap argument construction so missing automatic
`.git`/`.agents` symbolic project-root read-only carveouts are skipped
before emitting bind args; missing `.codex`, user-authored `read`/`none`
subpath rules, and existing missing writable-root behavior are
preserved.
- Adds coverage that legacy workspace-write config produces symbolic
project-root metadata carveouts, extra legacy workspace writable roots
still protect existing metadata paths such as `.git`, and bwrap skips
missing `.git`/`.agents` project-root carveouts while preserving missing
`.codex` and user-authored missing subpath rules.

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/19772).
* #19776
* #19775
* #19774
* #19773
* __->__ #19772
2026-04-27 16:50:10 -07:00
..

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 keeps the legacy default preferences read access (user-preference-read) needed for cfprefs-backed macOS behavior.

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 the first bwrap found on PATH outside the current working directory whenever it is available. If bwrap is present but too old to support --argv0, the helper keeps using system bubblewrap and switches to a no---argv0 compatibility path for the inner re-exec. If bwrap is missing, it falls back to the vendored bubblewrap path compiled into the binary and Codex surfaces a startup warning through its normal notification path instead of printing directly from the sandbox helper. Codex also surfaces a startup warning when bubblewrap cannot create user namespaces. WSL2 uses the normal Linux bubblewrap path. WSL1 is not supported for bubblewrap sandboxing because it cannot create the required user namespaces, so Codex rejects sandboxed shell commands that would enter the bubblewrap path before invoking bwrap.

Windows

Legacy SandboxPolicy / sandbox_mode configs are still supported on Windows. Legacy read-only and workspace-write policies imply full filesystem read access; exact readable roots are represented by split filesystem policies instead.

The elevated Windows sandbox also supports:

  • legacy ReadOnly and WorkspaceWrite behavior
  • split filesystem policies that need exact readable roots, exact writable roots, or extra read-only carveouts under writable roots
  • backend-managed system read roots required for basic execution, such as C:\Windows, C:\Program Files, C:\Program Files (x86), and C:\ProgramData, when a split filesystem policy requests platform defaults

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 can be enforced directly by the selected Windows backend or round-trip through the legacy SandboxPolicy model without changing semantics. Policies that would require direct explicit unreadable carveouts (none) or reopened writable descendants under read-only carveouts 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.