## Summary
- launch Windows sandboxed children on a private desktop instead of
`Winsta0\Default`
- make private desktop the default while keeping
`windows.sandbox_private_desktop=false` as the escape hatch
- centralize process launch through the shared
`create_process_as_user(...)` path
- scope the private desktop ACL to the launching logon SID
## Why
Today sandboxed Windows commands run on the visible shared desktop. That
leaves an avoidable same-desktop attack surface for window interaction,
spoofing, and related UI/input issues. This change moves sandboxed
commands onto a dedicated per-launch desktop by default so the sandbox
no longer shares `Winsta0\Default` with the user session.
The implementation stays conservative on security with no silent
fallback back to `Winsta0\Default`
If private-desktop setup fails on a machine, users can still opt out
explicitly with `windows.sandbox_private_desktop=false`.
## Validation
- `cargo build -p codex-cli`
- elevated-path `codex exec` desktop-name probe returned
`CodexSandboxDesktop-*`
- elevated-path `codex exec` smoke sweep for shell commands, nested
`pwsh`, jobs, and hidden `notepad` launch
- unelevated-path full private-desktop compatibility sweep via `codex
exec` with `-c windows.sandbox=unelevated`
• Keep Windows sandbox runner launches working from packaged installs by
running the helper from a user-owned runtime location.
On some Windows installs, the packaged helper location is difficult to
use reliably for sandboxed runner launches even though the binaries are
present. This change works around that by copying codex-
command-runner.exe into CODEX_HOME/.sandbox-bin/, reusing that copy
across launches, and falling back to the existing packaged-path lookup
if anything goes wrong.
The runtime copy lives in a dedicated directory with tighter ACLs than
.sandbox: sandbox users can read and execute the runner there, but they
cannot modify it. This keeps the workaround focused on the
command runner, leaves the setup helper on its trusted packaged path,
and adds logging so it is clear which runner path was selected at
launch.
`SandboxPolicy::ReadOnly` previously implied broad read access and could
not express a narrower read surface.
This change introduces an explicit read-access model so we can support
user-configurable read restrictions in follow-up work, while preserving
current behavior today.
It also ensures unsupported backends fail closed for restricted-read
policies instead of silently granting broader access than intended.
## What
- Added `ReadOnlyAccess` in protocol with:
- `Restricted { include_platform_defaults, readable_roots }`
- `FullAccess`
- Updated `SandboxPolicy` to carry read-access configuration:
- `ReadOnly { access: ReadOnlyAccess }`
- `WorkspaceWrite { ..., read_only_access: ReadOnlyAccess }`
- Preserved existing behavior by defaulting current construction paths
to `ReadOnlyAccess::FullAccess`.
- Threaded the new fields through sandbox policy consumers and call
sites across `core`, `tui`, `linux-sandbox`, `windows-sandbox`, and
related tests.
- Updated Seatbelt policy generation to honor restricted read roots by
emitting scoped read rules when full read access is not granted.
- Added fail-closed behavior on Linux and Windows backends when
restricted read access is requested but not yet implemented there
(`UnsupportedOperation`).
- Regenerated app-server protocol schema and TypeScript artifacts,
including `ReadOnlyAccess`.
## Compatibility / rollout
- Runtime behavior remains unchanged by default (`FullAccess`).
- API/schema changes are in place so future config wiring can enable
restricted read access without another policy-shape migration.
Today, there is a single capability SID that allows the sandbox to write
to
* workspace (cwd)
* tmp directories if enabled
* additional writable roots
This change splits those up, so that each workspace has its own
capability SID, while tmp and additional roots, which are
installation-wide, are still governed by the "generic" capability SID
This isolates workspaces from each other in terms of sandbox write
access.
Also allows us to protect <cwd>/.codex when codex runs in a specific
<cwd>
The elevated setup synchronously applies read/write ACLs to any
workspace roots.
However, until we apply *read* permission to the full path, powershell
cannot use some roots as a cwd as it needs access to all parts of the
path in order to apply it as the working directory for a command.
The solution is, while the async read-ACL part of setup is running, use
a "junction" that lives in C:\Users\CodexSandbox{Offline|Online} that
points to the cwd.
Once the read ACLs are applied, we stop using the junction.
-----
this PR also removes some dead code and overly-verbose logging, and has
some light refactoring to the ACL-related functions
## Description
Introduced `ExternalSandbox` policy to cover use case when sandbox
defined by outside environment, effectively it translates to
`SandboxMode#DangerFullAccess` for file system (since sandbox configured
on container level) and configurable `network_access` (either Restricted
or Enabled by outside environment).
as example you can configure `ExternalSandbox` policy as part of
`sendUserTurn` v1 app_server API:
```
{
"conversationId": <id>,
"cwd": <cwd>,
"approvalPolicy": "never",
"sandboxPolicy": {
"type": ""external-sandbox",
"network_access": "enabled"/"restricted"
},
"model": <model>,
"effort": <effort>,
....
}
```
a few fixes based on testing feedback:
* ensure cap_sid file is always written by elevated setup.
* always log to same file whether using elevated sandbox or not
* process potentially slow ACE write operations in parallel
* dedupe write roots so we don't double process any
* don't try to create read/write ACEs on the same directories, due to
race condition
