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core-agent-ide/codex-rs/linux-sandbox
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viyatb-oai 603b6493a9
fix(linux-sandbox): ignore missing writable roots (#14890) 
## Summary
- skip nonexistent `workspace-write` writable roots in the Linux
bubblewrap mount builder instead of aborting sandbox startup
- keep existing writable roots mounted normally so mixed Windows/WSL
configs continue to work
- add unit and Linux integration regression coverage for the
missing-root case

## Context
This addresses regression A from #14875. Regression B will be handled in
a separate PR.

The old bubblewrap integration added `ensure_mount_targets_exist` as a
preflight guard because bubblewrap bind targets must exist, and failing
early let Codex return a clearer error than a lower-level mount failure.

That policy turned out to be too strict once bubblewrap became the
default Linux sandbox: shared Windows/WSL or mixed-platform configs can
legitimately contain a well-formed writable root that does not exist on
the current machine. This PR keeps bubblewrap's existing-target
requirement, but changes Codex to skip missing writable roots instead of
treating them as fatal configuration errors.
2026-03-17 00:21:00 -07:00
..
src fix(linux-sandbox): ignore missing writable roots (#14890) 2026-03-17 00:21:00 -07:00
tests fix(linux-sandbox): ignore missing writable roots (#14890) 2026-03-17 00:21:00 -07:00
BUILD.bazel build(linux-sandbox): always compile vendored bubblewrap on Linux; remove CODEX_BWRAP_ENABLE_FFI (#11498) 2026-02-11 21:30:41 -08:00
build.rs build(linux-sandbox): always compile vendored bubblewrap on Linux; remove CODEX_BWRAP_ENABLE_FFI (#11498) 2026-02-11 21:30:41 -08:00
Cargo.toml feat(linux-sandbox): implement proxy-only egress via TCP-UDS-TCP bridge (#11293) 2026-02-21 18:16:34 +00:00
config.h build(linux-sandbox): always compile vendored bubblewrap on Linux; remove CODEX_BWRAP_ENABLE_FFI (#11498) 2026-02-11 21:30:41 -08:00
README.md fix: reopen writable linux carveouts under denied parents (#14514) 2026-03-13 01:36:06 +00:00

README.md

codex-linux-sandbox

This crate is responsible for producing:

  • a codex-linux-sandbox standalone executable for Linux that is bundled with the Node.js version of the Codex CLI
  • a lib crate that exposes the business logic of the executable as run_main() so that
    • the codex-exec CLI can check if its arg0 is codex-linux-sandbox and, if so, execute as if it were codex-linux-sandbox
    • this should also be true of the codex multitool CLI

On Linux, the bubblewrap pipeline uses the vendored bubblewrap path compiled into this binary.

Current Behavior

  • Legacy SandboxPolicy / sandbox_mode configs remain supported.
  • Bubblewrap is the default filesystem sandbox pipeline and is standardized on the vendored path.
  • Legacy Landlock + mount protections remain available as an explicit legacy fallback path.
  • Set features.use_legacy_landlock = true (or CLI -c use_legacy_landlock=true) to force the legacy Landlock fallback.
  • The legacy Landlock fallback is used only when the split filesystem policy is sandbox-equivalent to the legacy model after cwd resolution.
  • Split-only filesystem policies that do not round-trip through the legacy SandboxPolicy model stay on bubblewrap so nested read-only or denied carveouts are preserved.
  • When the default bubblewrap pipeline is active, the helper applies PR_SET_NO_NEW_PRIVS and a seccomp network filter in-process.
  • When the default bubblewrap pipeline is active, the filesystem is read-only by default via --ro-bind / /.
  • When the default bubblewrap pipeline is active, writable roots are layered with --bind <root> <root>.
  • When the default bubblewrap pipeline is active, protected subpaths under writable roots (for example .git, resolved gitdir:, and .codex) are re-applied as read-only via --ro-bind.
  • When the default bubblewrap pipeline is active, overlapping split-policy entries are applied in path-specificity order so narrower writable children can reopen broader read-only or denied parents while narrower denied subpaths still win. For example, /repo = write, /repo/a = none, /repo/a/b = write keeps /repo writable, denies /repo/a, and reopens /repo/a/b as writable again.
  • When the default bubblewrap pipeline is active, symlink-in-path and non-existent protected paths inside writable roots are blocked by mounting /dev/null on the symlink or first missing component.
  • When the default bubblewrap pipeline is active, the helper explicitly isolates the user namespace via --unshare-user and the PID namespace via --unshare-pid.
  • When the default bubblewrap pipeline is active and network is restricted without proxy routing, the helper also isolates the network namespace via --unshare-net.
  • In managed proxy mode, the helper uses --unshare-net plus an internal TCP->UDS->TCP routing bridge so tool traffic reaches only configured proxy endpoints.
  • In managed proxy mode, after the bridge is live, seccomp blocks new AF_UNIX/socketpair creation for the user command.
  • When the default bubblewrap pipeline is active, it mounts a fresh /proc via --proc /proc by default, but you can skip this in restrictive container environments with --no-proc.

Notes

  • The CLI surface still uses legacy names like codex debug landlock.