Two bwrap failures found by live host tasks, both in the
AppArmor profile (not in codex or the worker):
1. deny capability sys_admin (etc.) breaks bwrap at userns
creation: codex-host with the deny list failed, the same
profile with capability, allowed it. codexsvc holds no host
capabilities, so the allow only covers fake-root caps inside
bwrap's own user namespace (scoped, harmless to the host);
network/ptrace/file denies still hold independently.
2. bwrap brings up loopback in its new net namespace via a
NETLINK_ROUTE socket: without network netlink raw, codex
workspace-write fails with 'Failed to bind NETLINK_ROUTE
socket' and no tool runs. And a bare 'deny network raw'
overrides the netlink allow (deny wins over allow), so the
raw deny must name inet/inet6 explicitly (verified by an
isolated netlink bind test under each profile variant).
README correction in the same change: codex workspace-write
does NOT isolate /tmp -- an agent /tmp write lands on host
/tmp (verified). The verified boundary is: own worktree
writable, everything else read-only, /tmp shared.
Docker outer layer and bwrap inner layer are mutually exclusive
on this host (fresh proc mounts fail with kernel EPERM inside
Docker's nested pidns, but work on the host under a userns
profile). So tasks that need an inner sandbox run on the host:
- Worker --claim-executor-only: strict executor claim (only
executor == own type, never NULL). The host worker MUST use
it, or it would steal NULL-executor tasks meant for Docker
workers (those tasks would lose the Docker outer layer).
Default behavior unchanged (NULL claimable by any worker).
- host-config-host.json: sandbox workspace-write, state
work/host-state-host.json (distinct from Docker tasks'
host-state.json), same relay home and test repo as Docker.
- deploy/apparmor/codex-host: docker-codex base + userns,
mount, pivot_root for bwrap; still denies raw network,
ptrace, dangerous capabilities, /proc/sys writes.
- deploy/host-worker/codex-host-worker.service: aa-exec -p
codex-host, --executor local --claim-executor-only,
capacity 2, proxy env 127.0.0.1:8888 so host tasks' relay/git
egress also goes through the Tinyproxy allowlist (host direct
egress would bypass it).
POST /tasks already accepts executor (local/docker/cloud), so
no API change was needed for routing.
Tests: 4 host-sandbox-routing tests (strict claim incl. CAS,
default still takes NULL, config sandbox/state, profile
allows bwrap without deny mount). Full suites pass.
- AppArmor network rules must use socket types (stream/dgram),
not protocol names (tcp/udp/icmp): the parser rejected the
profile (Invalid network entry) until fixed.
- Tinyproxy has no 'Upstream none' syntax; the line failed the
service at startup. Direct connection is the default, so the
line is removed.
- Tinyproxy Filter is POSIX BASIC regex, not extended: the
extended-style anchored patterns denied even allowed domains
(verified: xcmapi.org got 403). Rewritten in basic syntax
(\(...\)* groups); the anchored form still blocks
evilgithub.com and xcmapi.org.evil.com (verified on host).
- Filter file must be world-readable (was 640 root:root, so
tinyproxy could not read it and exited on reload); install
steps now chmod 644 (documented in the filter header via
the install note in tinyproxy.conf).
Host already runs these exact files (proxy allow/block
verified: xcmapi/github/api.github 200, example/evilgithub/
xcmapi.org.evil.com 403).
Inner codex sandbox stays danger-full-access by choice (bwrap
path is a separate decision); this hardens everything around it:
- DockerExecutor: --security-opt plumbing (repeatable, dedups
no-new-privileges), --pids-limit (CLI default 512, fork-bomb
guard), per-call extra_env (-e NAME=VALUE, non-secrets only,
e.g. proxy URLs; the model key still goes by -e NAME only).
- Worker: --egress-proxy-port (0 = off). When on, Docker task
containers get HTTP(S)_PROXY pointing at the host filtering
proxy via their network gateway IP (tenant network gateway
or default bridge gateway). Gateway unresolvable => the
attempt fails instead of running unproxied (fail closed,
same rule as tenant network creation failure).
- AppArmor profile deploy/apparmor/docker-codex: docker-default
base + deny network raw/packet, deny ptrace, deny mount/
umount/pivot_root, deny dangerous capabilities, deny writes
to /proc/sys, /sys, /proc/keys. Deliberately NO userns rule
(that would enable the bwrap path, not this one). File rules
mirror docker-default (broad + sensitive denies); a strict
file allowlist would need profiling codex's file access set
and is not claimed here.
- Egress proxy deploy/egress/: Tinyproxy with
FilterDefaultDeny + anchored domain allowlist (relay,
github, pypi, npm). Anchoring matters: an unanchored
'github.com' regex would also match 'evilgithub.com'.
- Seccomp honesty (README): Docker default seccomp already
enforces on all task containers; no new stricter allowlist
is claimed in this change (building one from memory risks
silently breaking the toolchain; it needs syscall profiling
first).
Tests: 3 outer-hardening tests (security-opt dedup, pids
limit, proxy env without leaking the key value, gateway
parse/fail, proxy fail-closed). Full suites pass.
host