## 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
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
ReadOnlyandWorkspaceWritebehavior - 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), andC:\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.