branderson
cc8ee744e7
An audit of the stack from a v1 box, asking whether each note's commands can run at the point it tells you to run them. TOOLING AVAILABILITY IS FINE. Every command is either a ./bin/ form or comes after a bootstrap in the same note, and a v1 box with no state file gets the "predates version tracking" path rather than an error. The linear v1 -> v4 walk works. THREE OTHER THINGS DID NOT. v4 declared `verify-node: dejima-devbox-audit drift`, and drift verifies nothing about v4's node work. That work is a log level on six rules in the hypervisor console; drift hashes files, units and ports in the guest. It would have reported `ok` on a box whose console was never touched, and mark-node would have recorded "verified" on the strength of unrelated evidence - which is the exact failure this design exists to prevent. Removed. Nothing in the guest can see a log level on the node, so v4 declares no check and the note says to look at pve-firewall.log instead. v4 never said `mark-node 4`. The node half would have shown outstanding forever. Added as its own step, which is also where the no-check point belongs. And status ran that bogus check on every invocation, because status now runs verify commands for OUTSTANDING node work as well as recorded work - so every `status` was hashing /etc. Removing the wrong verify-node fixes it; the feature is right and the check was not. PROSE ECONOMY, same audit as the docs, applied to what these PRs added: drift's comments 55 -> 39 lines, against 39 of code snippets.bats header 41 -> 28 lines, against 47 of code upgrades/0004 964 -> 812 words Nothing removed but restatement. The load-bearing parts - the partial-state trap, why the watchlist is short, why placeholders are substituted before parsing - are all still there and are easier to find for being shorter. `bats test/` 155 passing.
Devbox Hardener
Bounds what a compromised development VM can reach on your network, and tells you what that bound actually is.
A devbox is a long-lived VM that runs dejima sessions. Unlike a CI runner it holds uncommitted work, so it cannot be rolled back on a schedule — and rollback is the whole containment story of the sister project, dejima-ci-hardener. What replaces it is the hypervisor firewall, plus knowing precisely what sits inside it.
It does not prevent root on the devbox. Nothing here tries to. It makes root reach less, and makes that reach something you can check rather than assume.
| proxmox/README.md | Start here. The node side: create the VM, apply the firewall. Everything in the web console |
| docs/building-a-devbox.md | The guest side: install, bootstrap, verify. The same on any hypervisor |
| docs/threat-model.md | What each layer grants, what was rejected and why, and what is not bounded |
Do the node side first, through the end of its §3.
Before you use it
Early development. Not ready to be depended on. Nothing here has been through outside review, an external audit, or adversarial testing by anyone but the person who wrote it. Every security property this describes is a claim awaiting scrutiny, not one that has survived it. Do not put this anywhere that being wrong about it would matter.
One maintainer, no support. Nothing about this is promised: not a reply, not a fix, not a release. SECURITY.md has the detail, and is where to report a vulnerability rather than in a public issue.
One person's work per devbox. A condition of the tool rather than an observation about how devboxes get used: the blast radius here is stated in terms of what is on the box, so a machine holding several people's work is out of spec and the reasoning does not hold for it. If you need separation between people, use a devbox each.
Container escape is deliberately deprioritised. An escape gains root, which is more than the container has — and root on this VM is already a row in the blast radius table, bounded by the same hypervisor firewall however it was reached. So patching is what is left worth doing, and separating escape from root inside the guest is not.
Use
sudo ./bin/dejima-devbox-bootstrap # once, in the guest
cd ~/dejima && ./install.sh # dejima's own step, as your own account
sudo dejima-devbox-audit # all three
sudo dejima-devbox-audit reach # containment only, what the timer runs
sudo dejima-devbox-audit radius # what root here would get
sudo dejima-devbox-audit drift # what changed since you last said it was clean
./bin/dejima-devbox-upgrade status # what this box is missing, from a checkout
Bootstrap installs what dejima needs from the host - Docker with the compose
v2 plugin, python3, jq - and clones dejima to ~/dejima. It stops there.
Installing dejima is dejima's step: install.sh writes into your ~/.claude,
~/.local/bin and ~/.config/dejima, and what it does there is that project's
to define and to change. A copy of that contract kept here would go stale
without anything noticing.
The harness is a step before that one, and neither this tool nor
install.sh arranges it: whichever harness dejima will run for you, it is
installed on this box as the account that will run dejima, and signed in, before
the first session. The credential proxy runs on this side and reads that
account's copy, and the container's mounts are that account's directories. docs/building-a-devbox.md
§5
has what each half breaks if it is missing.
The audit needs root. The config is 0640 root, and the radius report stats
files in the home of the account that runs dejima, which it reads from the
config rather than from $HOME - under sudo and under the timer that is
root's, whose home on a devbox holds nothing.
How it fails
The firewall is on the hypervisor, so the guest cannot verify it by reading it. That is what makes it worth having and what makes checking it awkward. The audit tests behaviour instead, by probing the default gateway: already in the routing table so it reveals nothing, guaranteed alive where an arbitrary address is not, and inside the ranges the firewall drops.
A timeout has two causes, and telling them apart is the whole design:
PASS |
Nothing answered and the network demonstrably works |
FAIL |
Something answered. Rules missing, or an exception above them |
INDETERMINATE |
Nothing answered, including things that should. Not a pass. |
A check that reports success when it does not know is worse than no check, because it gets believed.
The IPv6 half has the same three states for different reasons. It asks the
segment who is there over IPv6 and counts the answers, and there a silence is
unambiguous: the node dropped the family, or the guest never had it, and both
are the outcome wanted. So silence is a plain PASS with no positive control.
INDETERMINATE is reserved for the probe not running at all, which is still not
a pass. It is a separate check because the node's other rules name IPv4 ranges
and match none of that traffic - see
the LAN boundary is two boundaries.
A rule that REJECTs rather than DROPs reports FAIL even though it is
working. bash's /dev/tcp cannot tell a rejection from a live host
refusing. That is the safe direction to be wrong in, and it is why the template
specifies DROP.
Nothing is stored about what this VM must not reach. Such a list would be a map of valuable targets, kept on the machine this project assumes will be owned. The audit derives its targets from the routing table and its controls from your forge, so there is nothing to type and nothing to leak.
Versions, and the boxes already out there
VERSION is what this checkout ships; /etc/dejima-devbox/state is what a
given devbox is at. Two numbers, because the guest half is installed from a
checkout and the node half is typed into a console, and only one of them is
knowable from inside the VM.
dejima needs none of this — short-lived containers, tip of main only, git pull closes any gap. A devbox is pinned to the day it was built, and a snapshot
restore can move it backwards without anyone deciding to.
docs/upgrading.md is the process; upgrades/ is
one note per version, written for someone at a console who has not read the diff.
./bin/dejima-devbox-upgrade status # run from a checkout, not the installed copy
Tests
bats test/
test/devbox.bats asserts against a real devbox and skips everywhere else. It
is gated on DEJIMA_DEVBOX=1 rather than on detecting a devbox, because a
detector that guesses wrong skips silently, and a suite that passes by asserting
nothing is worse than one that fails.
Further reading
| docs/ | Index of everything below |
| docs/threat-model.md | What each layer grants, why escape is deprioritised, what was rejected |
| docs/reference.md | The three verdicts, the three addressing modes, the one config key |
| SECURITY.md | What this claims, and where to report a vulnerability |
| dejima-ci-hardener | The sister project, for hosts that can be rolled back |
License
GPL-3.0-or-later. See LICENSE.
The dejima wordmark and logo are not code and are not covered by that licence. They are trademarks; who holds them and what may be done with them is stated once for the organisation, at dejima's ATTRIBUTION.md.