The bwrap engine + OCI engine that lived in internal/convert/runner.go
both leak isolation policy into Go code. Replaced with a single image-
side wrapper that drop-in-shadows pandoc and chromium-browser on PATH.
zddc-server's only contract with the image is now "exec.Command(name,
args) gets you that tool's behavior" — sandboxing, resource caps, and
namespace setup live entirely in shell scripts shipped by the image.
Architecture:
- zddc/runtime/zddc-cgroup-init runs at container start. cgroup v2's
"no internal processes" constraint forbids a cgroup from having both
children and processes; the init script moves PID 1 into a child,
enables +memory +pids in subtree_control, then exec's zddc-server.
Best-effort: degrades cleanly to "no resource caps" if cgroupfs
isn't writable.
- zddc/runtime/zddc-sandbox-exec is the per-call wrapper, symlinked
from /usr/local/bin/{pandoc,chromium-browser}. Creates a transient
cgroup v2 (memory.max + pids.max), then bubblewrap-sandboxes the
real binary at /usr/bin/<name>: --unshare-all, --ro-bind /usr,
--proc /proc, --tmpfs /tmp, --clearenv. Caller's scratch dir comes
in via ZDDC_SCRATCH env and is bind-mounted at the SAME path so
absolute paths round-trip unchanged.
Go simplifications (~250 lines net deletion):
- Runner interface: Run(ctx, binary, stdin, scratchDir, cmd) — no
ToolSpec, no mount list, no engine concept. Single localRunner
implementation; bwrapRunner + containerRunner both deleted.
- health.Probe just looks up pandoc + chromium on PATH; Capabilities
drops engine kinds.
- Convert.go: ToHTML/ToPDF write to a per-call scratch dir under
TMPDIR and pass absolute paths; the wrapper bind-mounts the dir.
No more "/tpl" / "/pdf" mount-point indirection.
- Config drops --convert-pandoc-image, --convert-chromium-image,
--convert-engine, --convert-podman-socket (OCI engine gone) and
--convert-cpus (CPU caps don't apply in the new model — wall-clock
+ memory + pids is the cap set). Defaults raised to match the new
caps the user authorized: mem 512→1024 MiB, pids 100→256,
timeout 30→60 s.
Image:
- zddc/runtime.Containerfile builds the production runtime image
(alpine + bubblewrap + pandoc + chromium + font-noto). Two
COPY statements pull in the wrapper scripts; ln -s symlinks the
shadow names.
- bitnest dev image mirrors this layout under /var/lib/zddc-dev-build/.
Container privilege required:
- Nested bwrap needs the outer container to permit user + mount
namespace creation + MS_SLAVE on root. The default seccomp +
AppArmor profiles block all of these. Quadlet adds:
--cap-add=ALL
--security-opt=seccomp=unconfined
--security-opt=apparmor=unconfined
--security-opt=unmask=ALL
Helm chart sets the equivalent via securityContext (capabilities.
add: SYS_ADMIN, seccompProfile.type: Unconfined, appArmorProfile.
type: Unconfined). Trade-off documented in AGENTS.md: zddc-server
RCE now has near-root power within the container, but the bind-
mount layout still bounds blast radius; bwrap is the real boundary
between zddc-server and untrusted markdown.
Tests: convert_test.go fully rewritten for the new Runner signature.
Drops TestBwrapArgs_* (functionality moved out of Go) and
TestImageTag (no more image refs). All 15 Go test packages green.
Verified live on bitnest: pandoc --version round-trip exits 0
through the wrapper; MD→DOCX produces a valid Word 2007+ file
end-to-end.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Single audit pass that removes pre-release back-compat, consolidates the
admin-policy decider, and fixes the .zddc write path.
Field removal — acl.allow / acl.deny:
- Drop ACLRules.Allow / Deny struct fields and mergeLegacyACL().
- Remove walker / lookups / validate / decider branches that read them.
- Migrate every test fixture (YAML strings and ACLRules struct literals)
to acl.permissions: { principal → verb-set }.
- Rewrite both bundled Rego policies (access.rego, access_federal.rego)
to traverse level.acl.permissions; rewrite parity-test helpers.
- Update create-project form (profile page) to collect permissions
instead of allow/deny lists.
Admin decider consolidation:
- Delete zddc.CanEditZddc — strict-ancestor rule retired. Subtree admins
own their own .zddc; the policy decider's IsActiveAdmin short-circuit
is the single bypass site.
- Migrate tablehandler.ServeTable to AllowActionFromChainP — closes the
same Forbidden bug already fixed for /browse.html.
- Drop AccessView.EditableParentChoices and treeEntry.CanEdit (always
true after the retirement). Profile page renders AdminSubtrees
directly for both lists.
- Drop the excludeLeaf parameter from AdminLevelInChain /
IsAdminForChain — no production caller passed true.
Dead code removed:
- policy.AllowWriteFromChain (zero production callers, zero tests).
- zddc.AllowedWithChain (zero production callers; tests deleted).
ModeStrict retirement — federal posture is OPA-only:
- Delete cascade_mode.go / cascade_mode_test.go and the ModeStrict
branches in cascade.go and acl.go.
- Drop --cascade-mode flag, CascadeMode config field, and the
InternalDecider.Mode field.
- Drop the mode parameter from every cascade helper:
GrantedVerbsAtLevel, AllowedAction, EffectiveVerbs,
EffectiveVerbsRange, RoleMembers, MatchesPrincipal,
MatchingPrincipals, WormZoneGrant, PolicyChain.VisibleStart.
- Strip cascade_mode from /.profile/config and
/.profile/effective-policy responses.
- Refresh README / ARCHITECTURE.md to describe federal posture as
"deploy OPA with access_federal.rego" (NIST AC-6); the bundled Rego
is the parent-deny-is-absolute variant. The in-process Go evaluator
implements only the commercial cascade.
Legacy redirects + .admin.css fallback:
- Drop /<dir>/.zddc.html → ?file=.zddc redirect and its test.
- Drop ?zip=1 retired comment + legacy test (handled by the
.zip virtual-URL path; covered by TestServeSubtreeZip).
- Drop .admin.css fallback in profile_assets.go — only .profile.css now.
- Refresh stale "retired" / "back-compat" / "legacy" comment markers.
.zddc write path fix:
- Dispatcher: route only GET/HEAD on .zddc URLs to ServeZddcFile; carve
.zddc out of the dot-prefix guard so PUT/DELETE/POST reach
ServeFileAPI. Before this, .zddc writes 405'd at ServeZddcFile and
the YAML editor's save flow had no live path.
- ServeFileAPI.resolveTargetPath: same .zddc-leaf carve-out so the file
API accepts the path; intermediate dot dirs (.zddc.d/) stay reserved.
- Listing: compute Writable per-file with ActionAdmin for .zddc
(matches the file API's gate) instead of ActionWrite for everything.
- Virtual .zddc placeholder: compute Writable via the same
parentActiveAdmin || ActionAdmin path. Was always false before.
- browse YAML editor canSave: exempt virtual .zddc — the synthetic
body is designed to materialize on PUT.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Replace `?zip=1` / `?convert=docx|html|pdf` query forms with path-suffix
URLs that look like ordinary files. `<dir>.zip` and `<file>.docx` /
`.html` / `.pdf` are virtual files served by the dispatcher when stat
fails at the requested path AND the corresponding base resource exists:
GET /Project-1/archive.zip ← if archive/ is a real directory
GET /Project-1/notes.docx ← if notes.md exists
Real on-disk files always win — a genuine archive.zip in the tree
serves its bytes normally. The virtual forms only fire when nothing
real is there.
Why: the URL form lets clients emit plain <a href> without query-
string handling; `curl -O` writes a sensible filename; mirror tools
pick up the path through normal recursion; the protocol surface
becomes "every URL is a file". Bash + filesystem mental model.
Server:
- New helpers handler.RecognizeVirtualSubtreeZip /
RecognizeVirtualConvert (in subtreezip.go and converthandler.go).
- Dispatcher's stat-fails branch checks them between IsDefaultMdlSpec
and MatchAppHTML. ACL is enforced on the base resource (the source
directory for zip, the .md source for convert).
- Three legacy query-form branches removed from main.go.
Client:
- browse/js/download.js: `dir + '.zip'` instead of `dir + '/?zip=1'`.
- browse/js/preview-markdown.js: convert anchor hrefs become
`<mdUrl-minus-.md>.<fmt>` instead of `<mdUrl>?convert=<fmt>`.
- shared/zddc-source.js downloadConverted: same transform.
Tests: subtreezip_test.go test URLs cosmetically updated to the new
shape (the handler is exercised directly, so the URL is metadata only,
but the test reads better).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
New endpoint GET /<path>/foo.md?convert=docx|html|pdf renders a markdown
source on demand. Surfaced as the Download buttons in browse's markdown
editor (separate commit).
Execution model — two upstream container images, lazy-pulled:
• docker.io/pandoc/latex:latest — MD→DOCX, MD→HTML (entrypoint pandoc)
• docker.io/zenika/alpine-chrome — HTML→PDF (entrypoint chromium-browser)
No custom image build. The runner passes --pull=missing on every podman/
docker invocation so the operator only needs the runtime installed —
first request pulls the image, subsequent requests use the local cache.
Overrides: --convert-pandoc-image / --convert-chromium-image (and the
matching ZDDC_CONVERT_* env vars). Engine: --convert-engine (podman
preferred, docker fallback). Resource caps: --convert-mem-mib (512),
--convert-cpus (2), --convert-pids (100), --convert-timeout (30s).
PDF flow is two-stage: pandoc renders the markdown through the embedded
viewer-template.html to standalone HTML, then chromium prints that HTML
via --print-to-pdf. Preserves the print-media CSS already authored in
viewer-template.html rather than going through pandoc's LaTeX template.
Each conversion runs in a throw-away container with --rm --network=none
--read-only --tmpfs=/tmp --cap-drop=ALL --security-opt=no-new-privileges
--env=HOME=/tmp plus a bind-mounted scratch dir for I/O. Pandoc reads
markdown from stdin / writes to stdout; the viewer template lives at
/tpl (ro). Chromium reads HTML from a read-write bind mount at /pdf
and writes the PDF to the same mount; the host reads it back. No shell
wrappers, no shell quoting — argv flows straight into each image's
entrypoint.
On-disk cache at <dir>/.converted/<base>.<ext> with mtime synced to the
source. Fast path is a stat-and-serve with no exec; slow path
singleflights concurrent requests for the same target. PUT/DELETE/MOVE
on the source .md purges the .converted/ sidecars.
Per-project template variables (client/project/contractor/project_number)
come from a new .zddc `convert:` cascade block, walked leaf→root with
per-key latest-wins. Filename-derived variables (title, tracking_number,
revision, status, is_draft) come from a new zddc.ParseFilename helper.
If neither podman nor docker is on PATH, the endpoint serves 503 with
a clear Retry-After. The rest of the server keeps working.
This is the first os/exec site in the codebase. The hardening in
internal/convert/runner.go — context.CancelFunc → process kill,
cmd.WaitDelay, platform-specific SysProcAttr (Setpgid + Pdeathsig on
Linux), minimal env, stdout cap via limitWriter, stderr ring buffer —
sets the pattern for any future shell-outs.
Public surface:
convert.ToDocx(ctx, source, meta) / .ToHTML / .ToPDF
convert.Probe(ctx, engineOverride) → install Runner if engine present
convert.SetImages(pandoc, chromium)
convert.ConfigureLimits(memMiB, cpus, pids, timeout)
convert.Available()
Container handler at internal/handler/converthandler.go; dispatcher
branch in cmd/zddc-server/main.go inserts the convert lookup after the
existing ACL gate, reusing the source file's read policy verbatim.
