9950b5e265
## Summary - always pass `--unshare-user` in the Linux bubblewrap argv builders - stop relying on bubblewrap's auto-userns behavior, which is skipped for `uid 0` - update argv expectations in tests and document the explicit user namespace behavior The installed Codex binary reproduced the same issue with: - `codex -c features.use_linux_sandbox_bwrap=true sandbox linux -- true` - `bwrap: Creating new namespace failed: Operation not permitted` This happens because Codex asked bubblewrap for mount/pid/network namespaces without explicitly asking for a user namespace. In a root-inside-container environment without ambient `CAP_SYS_ADMIN`, that fails. Adding `--unshare-user` makes bubblewrap create the user namespace first and then the remaining namespaces succeed.
41 lines
2.2 KiB
Markdown
41 lines
2.2 KiB
Markdown
# codex-linux-sandbox
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This crate is responsible for producing:
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- a `codex-linux-sandbox` standalone executable for Linux that is bundled with the Node.js version of the Codex CLI
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- a lib crate that exposes the business logic of the executable as `run_main()` so that
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- the `codex-exec` CLI can check if its arg0 is `codex-linux-sandbox` and, if so, execute as if it were `codex-linux-sandbox`
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- this should also be true of the `codex` multitool CLI
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On Linux, the bubblewrap pipeline uses the vendored bubblewrap path compiled
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into this binary.
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**Current Behavior**
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- Legacy Landlock + mount protections remain available as the legacy pipeline.
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- The bubblewrap pipeline is standardized on the vendored path.
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- During rollout, the bubblewrap pipeline is gated by the temporary feature
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flag `use_linux_sandbox_bwrap` (CLI `-c` alias for
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`features.use_linux_sandbox_bwrap`; legacy remains default when off).
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- When enabled, the bubblewrap pipeline applies `PR_SET_NO_NEW_PRIVS` and a
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seccomp network filter in-process.
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- When enabled, the filesystem is read-only by default via `--ro-bind / /`.
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- When enabled, writable roots are layered with `--bind <root> <root>`.
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- When enabled, protected subpaths under writable roots (for example `.git`,
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resolved `gitdir:`, and `.codex`) are re-applied as read-only via `--ro-bind`.
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- When enabled, symlink-in-path and non-existent protected paths inside
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writable roots are blocked by mounting `/dev/null` on the symlink or first
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missing component.
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- When enabled, the helper explicitly isolates the user namespace via
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`--unshare-user` and the PID namespace via `--unshare-pid`.
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- When enabled and network is restricted without proxy routing, the helper also
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isolates the network namespace via `--unshare-net`.
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- In managed proxy mode, the helper uses `--unshare-net` plus an internal
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TCP->UDS->TCP routing bridge so tool traffic reaches only configured proxy
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endpoints.
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- In managed proxy mode, after the bridge is live, seccomp blocks new
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AF_UNIX/socketpair creation for the user command.
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- When enabled, it mounts a fresh `/proc` via `--proc /proc` by default, but
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you can skip this in restrictive container environments with `--no-proc`.
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**Notes**
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- The CLI surface still uses legacy names like `codex debug landlock`.
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