fix: support native package verifier scratch

scripts/check-image.sh

@@ -6,7 +6,9 @@
 #   - its module storage mount point, /var/lib/ekklesia/modules, exists, is root-owned, and is empty;
 #   - EKKLESIA_MODULES_DIR names that directory, in the image configuration and in a running process;
 #   - a checkout with a populated modules/ directory builds the same image: the runtime file system
-#     of both builds is identical, and no module from that directory enters it.
+#     of both builds is identical, and no module from that directory enters it;
+#   - the hardened verifier keeps /tmp noexec while a dedicated bounded execution scratch loads and
+#     runs the real sharp 0.35.5/libvips 1.3.4 native proof package.
 #
 #   bash scripts/check-image.sh                        builds both images from this checkout
 #   EKKLESIA_CHECK_IMAGE=<image> bash scripts/check-image.sh   checks one existing image's contents
@@ -103,6 +105,7 @@ context_copy() {
 tag_base="ekklesia-ci:${GITHUB_SHA:-local}-${GITHUB_RUN_ID:-0}-${GITHUB_RUN_ATTEMPT:-1}-"
 generic_image="${tag_base}generic-$$"
 populated_image="${tag_base}populated-$$"
+builder_image="${tag_base}native-proof-builder-$$"
 
 # build_image <context> <tag>
 build_image() {
@@ -143,4 +146,67 @@ else
   echo "note the two builds' layers differ (a cold build cache); their file systems do not"
 fi
 
+step "Proving native package verification with /tmp noexec and a dedicated execution scratch"
+built_images+=("$builder_image")
+DOCKER_BUILDKIT=1 docker build --quiet --file "$work/generic/deploy/Dockerfile" \
+  --target build --label "${EKKLESIA_CI_LABEL}=${project}" \
+  --label "${EKKLESIA_CI_CREATED_LABEL}=$(date +%s)" \
+  --tag "$builder_image" "$work/generic" >/dev/null || fail "the native proof builder did not build."
+mkdir "$work/native-package"
+package_archive="$({
+  docker run --rm --network none --user "$(id -u):$(id -g)" \
+    -v "$work/native-package:/proof" --entrypoint node "$builder_image" \
+    packages/module-pack/tests/support/pack-native-verifier-proof.mjs /proof
+} | tail -1)" || fail "the real native proof package did not build."
+[[ "$package_archive" == native-proof-0.1.0-linux-x64-glibc.tar.gz ]] ||
+  fail "the native proof builder returned an unexpected archive."
+
+docker run --rm --network none --read-only \
+  --tmpfs /tmp:rw,nosuid,nodev,noexec,size=64m \
+  --tmpfs /run/ekklesia-verifier:rw,nosuid,nodev,exec,size=1100m,mode=0700,uid=1000,gid=1000 \
+  --cap-drop ALL --security-opt no-new-privileges \
+  -e "PROOF_ARCHIVE=$package_archive" -v "$work/native-package:/package:ro" \
+  --entrypoint sh "$generic_image" -ec '
+    fail() { echo "check-image: $*" >&2; exit 1; }
+    verifier() {
+      EKKLESIA_MODULE_VERIFIER_SCRATCH_DIR=/run/ekklesia-verifier \
+        node core/dist/cli/verify-module-package.js "/package/$PROOF_ARCHIVE" \
+        --sha256-file "/package/$PROOF_ARCHIVE.sha256" "$@"
+    }
+    scratch_failure() {
+      if output="$(EKKLESIA_MODULE_VERIFIER_SCRATCH_DIR="$1" \
+        node core/dist/cli/verify-module-package.js "/package/$PROOF_ARCHIVE" \
+        --sha256-file "/package/$PROOF_ARCHIVE.sha256" 2>&1)"; then
+        fail "the verifier accepted unusable execution scratch $1."
+      fi
+      printf "%s\n" "$output" | grep -Fq "[MODULE_PACKAGE_VERIFIER_SCRATCH_UNAVAILABLE]" ||
+        fail "the verifier did not identify unusable execution scratch $1."
+    }
+
+    grep -Eq " /tmp .*noexec" /proc/mounts || fail "/tmp is not mounted noexec."
+    verifier --extract-to /tmp/noexec-installed >/tmp/noexec-verify.log
+    if env -i /usr/local/bin/node --input-type=module --eval \
+      "await import(\"file:///tmp/noexec-installed/server/index.js\");" \
+      >/tmp/noexec-load.log 2>&1; then
+      fail "the native addon unexpectedly loaded from noexec /tmp."
+    fi
+    rm -rf /tmp/noexec-installed
+    scratch_failure /tmp
+    scratch_failure /missing-verifier-scratch
+    scratch_failure /package
+
+    verifier --extract-to /run/ekklesia-verifier/installed >/tmp/native-verify.log
+    env -i /usr/local/bin/node --input-type=module --eval \
+      "const m=await import(\"file:///run/ekklesia-verifier/installed/server/index.js\"); const actual=await m.proof(); const expected={pixels:[255,0,0,255,0,0,255,0,0,255,0,0],png:{format:\"png\",height:3,width:5},resized:{channels:3,height:2,width:2}}; if(JSON.stringify(actual)!==JSON.stringify(expected)) throw new Error(\"sharp proof mismatch\");"
+    rm -rf /run/ekklesia-verifier/installed
+
+    verifier >/tmp/native-verify-a.log 2>&1 & first=$!
+    verifier >/tmp/native-verify-b.log 2>&1 & second=$!
+    wait "$first" || { cat /tmp/native-verify-a.log >&2; fail "first concurrent verification failed."; }
+    wait "$second" || { cat /tmp/native-verify-b.log >&2; fail "second concurrent verification failed."; }
+    [ -z "$(find /run/ekklesia-verifier -mindepth 1 -print -quit)" ] ||
+      fail "the verifier left execution scratch behind."
+  ' || fail "the hardened native verifier proof failed."
+echo "ok   /tmp stayed noexec; native verification, sharp execution, rejection, concurrency, and cleanup passed"
+
 echo "Generic platform image check passed."