feat: secure build phase 1 — cosign cell-side image verification (warn default) + Dockerfile validation
Unit Tests / test (push) Successful in 13m28s

- config/cosign/cosign.pub: public verification key committed to repo (safe);
  cosign private key lives in /home/roof/.pic-secrets/ and is NEVER committed
- api/config_manager.py: image_verification config block (modes: off|warn|enforce,
  default: warn) so existing deployments are unaffected until images are signed
- api/service_composer.py: cosign verify before pull/up; enforce aborts the
  operation, warn logs and proceeds, off skips entirely; also fixes the prior
  unsafe proceed-on-pull-failure path
- api/service_store_manager.py: store-image digest requirement (warn default,
  reject under enforce)
- api/Dockerfile: cosign binary copied from the official cosign image
- docker-compose.yml: config/cosign/ bind-mounted into cell-api container
- install.sh: ensure/verify bundled cosign pubkey on new cell installs
- api/manifest_validator.py: validate_build_context() — Dockerfile lint
- tests: full coverage for config modes, composer verify paths, store digest
  guard, and validate_build_context

Verification defaults to warn so nothing breaks in production until images are
signed (phase 2). Private key stored outside git at /home/roof/.pic-secrets/.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
2026-06-11 03:53:47 -04:00
parent 8d904b1b8f
commit 238db60702
12 changed files with 622 additions and 2 deletions
+185
View File
@@ -48,6 +48,48 @@ _IMAGE_DIGEST_RE = re.compile(
r'^git\.pic\.ngo/roof/[a-zA-Z0-9._/-]+@sha256:[0-9a-f]{64}$'
)
# ── Build-context (Dockerfile) lint ───────────────────────────────────────
#
# These checks are *defense-in-depth*, not a guarantee. A Dockerfile is
# Turing-ish: a determined author can still fetch code at build time via a
# permitted base image's package manager, multi-stage tricks, or build args.
# The real trust boundary is the isolated builder + cosign signature applied
# by the trusted publish stage (P2). This static lint exists to catch the
# obvious-and-cheap mistakes (un-pinned bases, remote ADD, secret-named args)
# before an image is ever built, and to keep the published corpus uniform.
# Base images a community Dockerfile may build FROM. Each MUST be digest
# pinned so the build is reproducible and the base cannot be swapped under us.
# Keep this curated and small; extend deliberately as P2/P3 add languages.
BUILD_BASE_IMAGE_ALLOWLIST = frozenset({
'docker.io/library/alpine',
'docker.io/library/debian',
'docker.io/library/python',
'docker.io/library/golang',
'docker.io/library/node',
'alpine',
'debian',
'python',
'golang',
'node',
'gcr.io/distroless/static',
'gcr.io/distroless/base',
})
# FROM scratch is only allowed for these (otherwise rejected). Empty by
# default — community images should start from a pinned, scannable base.
BUILD_SCRATCH_ALLOWLIST = frozenset()
_DOCKERFILE_SECRET_NAME_RE = re.compile(r'(TOKEN|KEY|PASSWORD|SECRET)', re.IGNORECASE)
_FROM_RE = re.compile(r'^FROM\s+(.+?)(?:\s+AS\s+\S+)?$', re.IGNORECASE)
_ADD_RE = re.compile(r'^ADD\s+(.+)$', re.IGNORECASE)
_ARG_RE = re.compile(r'^ARG\s+([A-Za-z_][A-Za-z0-9_]*)', re.IGNORECASE)
_ENV_RE = re.compile(r'^ENV\s+(.+)$', re.IGNORECASE)
# Context size / file-count caps — a community build context should be small
# (a Dockerfile + a handful of config/entrypoint files), never a whole tree.
BUILD_CONTEXT_MAX_BYTES = 5 * 1024 * 1024 # 5 MiB
BUILD_CONTEXT_MAX_FILES = 200
def validate_manifest(manifest: dict) -> tuple:
"""
@@ -294,6 +336,149 @@ def validate_rendered_compose(yaml_text: str, allowed_data_dir: str = None,
return (len(errors) == 0, errors)
def _stage_aliases(dockerfile_text: str) -> set:
"""Collect multi-stage build aliases (FROM x AS alias) so later FROM <alias>
references resolve to a same-file stage rather than an external base."""
aliases = set()
for raw in dockerfile_text.splitlines():
line = raw.strip()
m = re.match(r'^FROM\s+\S+\s+AS\s+(\S+)\s*$', line, re.IGNORECASE)
if m:
aliases.add(m.group(1).lower())
return aliases
def _base_is_allowed(base_ref: str) -> tuple:
"""Return (ok, error_or_None) for a single FROM base image reference.
Requires an @sha256: digest pin and that the repository part (sans tag/
digest) is in BUILD_BASE_IMAGE_ALLOWLIST. 'scratch' is handled separately.
"""
if '@sha256:' not in base_ref:
return (False, f'FROM base image must be digest-pinned (@sha256:): {base_ref!r}')
repo = base_ref.split('@', 1)[0].split(':', 1)[0]
if repo not in BUILD_BASE_IMAGE_ALLOWLIST:
return (False, f'FROM base image not in allowlist: {repo!r}')
return (True, None)
def validate_build_context(dockerfile_text: str, context_files=None) -> tuple:
"""
Static lint of a community Dockerfile and its build context.
Returns (True, []) when the Dockerfile passes; (False, [errors]) otherwise.
Enforced (defense-in-depth — see module note above, this is NOT a sandbox):
- every external FROM base must be in BUILD_BASE_IMAGE_ALLOWLIST and
digest-pinned (@sha256:)
- FROM scratch only when allowlisted in BUILD_SCRATCH_ALLOWLIST
- no `ADD http(s)://...` (fetches arbitrary remote content at build time)
- no ARG/ENV whose name matches /(TOKEN|KEY|PASSWORD|SECRET)/i (baking a
secret into a layer / build cache)
- context size and file-count caps when context_files metadata is given
context_files: optional iterable of (path, size_bytes) tuples describing the
build context. Pass None to skip the size/count checks (e.g. when only the
Dockerfile text is available, as in CI lint of the manifest repo).
"""
errors = []
if not isinstance(dockerfile_text, str) or not dockerfile_text.strip():
return (False, ['Dockerfile is empty'])
aliases = _stage_aliases(dockerfile_text)
# Join backslash-continued lines so a multi-line instruction is one logical line.
logical_lines = []
buf = ''
for raw in dockerfile_text.splitlines():
stripped = raw.rstrip()
if stripped.endswith('\\'):
buf += stripped[:-1] + ' '
continue
buf += stripped
logical_lines.append(buf)
buf = ''
if buf:
logical_lines.append(buf)
saw_from = False
for line in logical_lines:
line = line.strip()
if not line or line.startswith('#'):
continue
m_from = _FROM_RE.match(line)
if m_from:
saw_from = True
base = m_from.group(1).strip().split()[0]
base_l = base.lower()
if base_l in aliases:
continue # references an earlier build stage, not an external base
if base_l == 'scratch':
if 'scratch' not in BUILD_SCRATCH_ALLOWLIST:
errors.append('FROM scratch is not allowed')
continue
ok, err = _base_is_allowed(base)
if not ok:
errors.append(err)
continue
m_add = _ADD_RE.match(line)
if m_add:
if re.search(r'https?://', m_add.group(1), re.IGNORECASE):
errors.append(f'ADD from a remote URL is not allowed: {line!r}')
continue
m_arg = _ARG_RE.match(line)
if m_arg and _DOCKERFILE_SECRET_NAME_RE.search(m_arg.group(1)):
errors.append(
f'ARG name looks secret-bearing (matches TOKEN|KEY|PASSWORD|SECRET): {m_arg.group(1)!r}'
)
continue
m_env = _ENV_RE.match(line)
if m_env:
# ENV NAME value | ENV NAME=value [NAME2=value2 ...]
body = m_env.group(1).strip()
names = []
if '=' in body:
for tok in body.split():
if '=' in tok:
names.append(tok.split('=', 1)[0])
else:
names.append(body.split()[0] if body.split() else '')
for name in names:
if name and _DOCKERFILE_SECRET_NAME_RE.search(name):
errors.append(
f'ENV name looks secret-bearing (matches TOKEN|KEY|PASSWORD|SECRET): {name!r}'
)
if not saw_from:
errors.append('Dockerfile has no FROM instruction')
if context_files is not None:
total_bytes = 0
count = 0
for entry in context_files:
try:
_path, size = entry
except (TypeError, ValueError):
_path, size = entry, 0
count += 1
total_bytes += int(size or 0)
if count > BUILD_CONTEXT_MAX_FILES:
errors.append(
f'build context has too many files: {count} > {BUILD_CONTEXT_MAX_FILES}'
)
if total_bytes > BUILD_CONTEXT_MAX_BYTES:
errors.append(
f'build context too large: {total_bytes} bytes > {BUILD_CONTEXT_MAX_BYTES}'
)
return (len(errors) == 0, errors)
def validate_provision_hook(hook) -> tuple:
"""
Validate a provision_hook value from accounts.provision_hook.