The `readDenyPaths` policy field shipped in the previous commit broke Linux
confinement outright. bwrap has to create the `/dev/null` bind's mount point
inside a tree its own profile has already made read-only, so it refused the
entire confinement whenever the parent directory was absent — every host that
has not stored a credential yet, including a fresh install:
bwrap: Can't mkdir parents for /home/runner/.dsh/.env: Read-only file system
which the executor correctly classifies as SANDBOX_UNAVAILABLE, so every
confined bash call failed closed. Landlock cannot subtract from its own `/`
read grant, so it reported `partial` enforcement on every confined call for a
file it never hid, with no way to switch the denial off (schemastery fills an
omitted array with `[]`, so empty and omitted were indistinguishable).
A protection that breaks confinement where it works and misreports it where it
does not is worse than a documented absence. Revert the field, both expressible
backends, the enforcement downgrade, and the policy default; state the residue
plainly in the credentials-local READMEs — file mode stops other OS users, not
the model — and keep the OS-keychain provider recorded as the real answer.
The narrower discipline stands: no surface hoists the credential document into
`process.env`, and the model is never handed a resolved path to it.
The policy home's resolve() now stamps readDenyPaths, so every consumer
that pins the resolved shape (bash-sandbox hand-off, tool-fs stamps)
carries it, and three uncovered branches gained real tests: landlock
reporting partial enforcement for a denial it cannot express, the
policy's default under programmatic construction, and both ambient
credential paths in llm-deepseek without a mounted seam.
The credential store is 0600 under a 0700 directory, which stops other OS
users but not the model: tool processes run as the same user, so under
the shipped danger-full-access default they read it like any other file.
SandboxExecutionPolicy grows readDenyPaths, and sandbox-policy defaults
it to $DSH_HOME/.env — the exact file rather than the harness home, so
the model keeps its documented access to its own session log. Seatbelt
appends a trailing deny (last matching rule wins) and bwrap maps
/dev/null over each path after any workspace bind; Landlock grants are a
pure allow-list that cannot subtract from its own / read grant, so
confine() reports partial enforcement there instead of claiming a
boundary the process does not have.
A real-kernel Seatbelt e2e proves the shape: the same read succeeds
unconfined and fails under the denial, while a sibling file in the same
directory stays readable. Both READMEs state the residual boundary
plainly — no confining mode means no boundary — and record the OS
keychain provider as the real answer.
The earlier fix only widened the vitest timeout, but the real race is the
patient probe reading the 1s launcher under the 5000ms *default* probe budget:
under a full parallel run spawnSync blocks the worker and fork/exec latency can
push the launcher's wall-clock past 5000ms, so the patient probe wrongly reads
unusable and the assertion fails. Give the patient probe a generous explicit
15000ms budget (still far below its 1s launcher runtime margin) so only the
250ms impatient probe races the launcher; keep a 30s vitest timeout above the
patient budget.
`bounds the default probes` runs a real launcher that sleeps 1s under the
5000ms default probe budget, all wrapped in vitest's 5000ms default test
timeout. The blocking spawnSync races that wrapper and tips over under the
load spike of a full parallel run — a pre-existing, load-sensitive flake
(noted as unrelated in this PR's original description). Give the test an
explicit 20s timeout so its bounded subprocess work never races the default.
ctx.sandbox (dsh-sandbox): confine(argv, policy) returns the argv to spawn
instead — wrapped so the process and its children run confined — plus the
enforcement completeness and the backend denial/runner-failure dialects;
no usable backend throws the fail-closed SANDBOX_UNAVAILABLE. Policy rides
per call. dsh-sandbox-local selects by platform and caches the verdict:
multi-candidate chains probe FUNCTIONALLY in preference order (Linux:
bwrap → the registry-installed node-addon-landlock-run launcher), a sole
candidate is selected unprobed (darwin: sandbox-exec/Seatbelt) and fails
closed at execution via runnerFailureSignatures; win32 is a reserved empty
chain. Profile parity is honest per backend (documented temp-area and ABI
differences; enforcement full|partial is a structured result fact).
CI: the sandbox-e2e matrix proves real-kernel confinement per rung (bwrap,
Landlock per architecture through the registry-installed launcher,
Seatbelt), failing on a silent all-skip; the packed-install rehearsal
installs the launcher family from the registry and asserts the binary
executable apart from kernel enforcement.
