Three independent root causes, all found by measuring instead of assuming:
1. SSH failed on 10/16 challenges while state.json looked perfect.
Only the 6 native GEMASTIK XVIII images provision 'ctfuser'; every imported
XVI/XVII image does 'echo root:${PASSWORD} | chpasswd' and logs in as root.
set_ssh_passwords() hardcoded ctfuser, so chpasswd set a password nobody
used -> 'Permission denied' on every team. Registry gains a per-challenge
'ssh_user'; chpasswd targets the real login and reports failures loudly.
2. phew SLA timed out on a healthy service, four bugs stacked:
- chall.py block-buffers stdout through the exec pipe (PYTHONUNBUFFERED now
set) and does a fresh Pailier keygen (~12 s) before printing its menu;
- _read_until read a TEXT pipe, so read(1) pulled 8 KB into Python's
TextIOWrapper buffer and select() then blocked on data already in memory;
- its buffer was per-call, so the read satisfying 'pt (hex)' also swallowed
the '> ' the next call waited for -> a race that failed intermittently;
- reaping killed chall.py it did not own: a blanket pkill -f, a
snapshot-diff (concurrent sessions diff against the same pre-spawn set),
and a class-level _children shared across uvicorn's thread pool. The child
now prints its own pid so exactly one session is reaped.
Also: ONE interactive session per check instead of five spawns (Paillier is
randomized per ciphertext, not per process) - 5 keygens were the CPU load
that starved the checks. And the 6 orphan single-node containers from the
original deploy were removed; one held 58 leaked chall.py and drove load
average 76 on 2 CPUs.
3. missing_sidecars() matched compose-generated names (teamN-<svc>-1) while
every service sets an explicit container_name, so it reported all 16 running
challenges as missing and hid the one real gap (anti-alchemy-db, which has
no container_name). Now reads container_name when present and falls back to
the compose default otherwise.
Verified: 64/64 SLA across 4 teams; 64/64 real SSH logins succeed with
correct <chall>_teamN hostnames; phew 3/3 sequential with no process leak.
Adds panel/verify_ssh_creds.py, audit_ssh_users.sh, reset_runtime.sh,
sla_sweep.sh, fix_sidecars.sh, phew_concurrency_test.sh, exec_probe_i.py.
Passwords failed on 10/16 challenges while state.json looked correct:
- only the 6 native GEMASTIK XVIII images provision 'ctfuser'; every imported
XVI/XVII image does 'echo root:${PASSWORD} | chpasswd' and logs in as root.
set_ssh_passwords() hardcoded ctfuser, so chpasswd set a password on an
account nobody uses -> 'Permission denied' everywhere.
Registry gains a per-challenge 'ssh_user'; chpasswd now targets the real
login (and ctfuser/ctf when present) and reports failures loudly.
- phew checker: chall.py block-buffers stdout through the docker exec pipe
(PYTHONUNBUFFERED now set) and leaks chall.py inside the container on
timeout (26 orphans, container saturated) -> reaps the whole exec process
group. Startup does a fresh Pailier keygen (~12 s) so crypto reads need
_CRYPTO_TIMEOUT, not the 5 s prompt default.
Adds panel/verify_ssh_creds.py (proves the state->container binding from
inside via a real login), audit_ssh_users.sh, reset_runtime.sh.
Found by testing a real enable/disable cycle (art, fjb, gift-card):
1. compose_gen always swapped build->image, so a never-built challenge
produced 'pull access denied for services-<name>'. Now it only reuses
the image when it exists locally, otherwise keeps build: so
'docker compose up --build' builds it.
2. Canonical templates use 'build: context: .' (written for the shared
services/ tree). In the per-team compose that resolves to the team dir
which has no Dockerfile -> 'failed to read dockerfile'. The renderer
now rewrites the main service's context to ./<name>.
3. Teams created before the XVI/XVII import had no xvi/xvii subpackages
under their local challenges/ dir, so the regenerated receiver main.py
crash-looped on import. gen_receiver_main now mirrors ALL shared
checkers (native + xvi + xvii) into every team receiver on each sync.
4. systemd Environment= keys can't contain hyphens, so
CHALLENGE_PORT_GIFT-CARD was silently dropped. Keys are now
normalized to underscores on both the writer and reader side.
5. Several checkers called 'docker exec' with no timeout; against a
container with accumulated chall.py zombies that blocks forever and
stalls the whole SLA loop. Added mandatory timeouts (Phew, Sheesh,
Carbeat, Poke, Warmup).
Also: enabling a challenge now copies its source tree into each team's
services/ dir (team dirs only held challenges enabled at create_team
time), and the XVII checkers were rewritten to be protocol-aware
(gift-card/gift-voucher are socat TCP, not HTTP) with strict timeouts.
Cyrene
MythEclipse
root
Rayhan Hanaputra
lightningitoid
rafliher