PR #30136 review surfaced two issues, both rooted in the same audit gap:
docker integration tests were running as root, not the unprivileged
`hermes` user (UID 10000) that the runtime actually uses via
`s6-setuidgid hermes`. Anything that probed PID-1 state or wrote to
the s6 control surface worked as root in the tests but was inert in
production.
Fixes:
1. `_s6_running()` previously called `Path("/proc/1/exe").resolve()`,
which is root-only readable. For UID 10000 the symlink yields
PermissionError, `resolve()` silently returns the unresolved path,
and `exe.name == "exe"` — so detection always returned False, the
service-manager runtime-registration path was inert, and every
`hermes profile create` / `hermes -p X gateway start` silently
skipped the s6 hook. Replace with `/proc/1/comm` (world-readable)
+ `/run/s6/basedir` (s6-overlay-specific) — both required, fail
closed.
2. `02-reconcile-profiles` now also chowns `/run/service/.s6-svscan/`
{control,lock} to hermes so `s6-svscanctl -a/-an` works without
root. Previously the directory chown stopped at `/run/service`
and the FIFO inside stayed root-owned, so `register_profile_gateway`
from hermes failed at the rescan-trigger step with EACCES — the
wrapper in profiles.py caught the exception and printed a swallowed
warning, so profile creation appeared to succeed while the slot
was rolled back.
Audit changes to flush this class of bug next time:
- Add `docker_exec` / `docker_exec_sh` helpers to `tests/docker/conftest.py`
that default to `-u hermes`. The module docstring explains why and
flags `user="root"` as opt-in only for tests that explicitly need
root (none currently do).
- Refactor every `docker exec` call in tests/docker/ through the new
helpers (test_dashboard.py, test_zombie_reaping.py, test_profile_gateway.py,
test_container_restart.py, test_s6_profile_gateway_integration.py).
- Add 5 unit tests covering `_s6_running` under various probe states
(both signals present; comm wrong; basedir missing; PermissionError
on /proc/1/comm; missing /proc — non-Linux). The PermissionError
test is the explicit regression guard for the original bug.
Known follow-up: the per-service `supervise/control` FIFO inside each
`/run/service/gateway-<profile>/supervise/` is created root-owned by
s6-supervise (which runs as root because s6-svscan is PID 1). `s6-svc
-u/-d/-t` from the hermes user will get EACCES on those. The audit
under `-u hermes` will reveal this in lifecycle tests — surfacing the
issue cleanly so it can be fixed in a focused follow-up (likely via a
small SUID helper or a polling chown loop in cont-init.d). The
detection + svscanctl fixes here are independent and complete on
their own.
Tasks 0.2-0.6 of the s6-overlay supervision plan. Locks the
user-visible behavior we must preserve through the Phase 2 init-
system swap:
- test_main_invocation.py (Task 0.2): docker run <image> with no
args, chat subcommand passthrough, bare executable passthrough,
bash pattern, exit-code propagation
- test_tui_passthrough.py (Task 0.3): TTY allocation via docker -t
using the host's script(1) for a PTY
- test_dashboard.py (Task 0.4): HERMES_DASHBOARD=1 opt-in,
HERMES_DASHBOARD_PORT override
- test_profile_gateway.py (Task 0.5): per-profile gateway
start/stop and profile-delete-stops-gateway. Both marked
xfail(strict=True) because the current tini image refuses
gateway lifecycle commands inside the container; Phase 4
Task 4.3 flips them to passing.
- test_zombie_reaping.py (Task 0.6): PID 1 reaps orphaned
zombies. tini does this today; s6-overlay's /init must
continue to.
Refs: docs/plans/2026-05-07-s6-overlay-dynamic-subagent-gateways.md
