scripts/iso R-61 slice 1: the baked root password becomes knowable (v1.24.0 train, part 1/3)

The ISO build now writes the minted throwaway root plaintext to a 0600
sibling file (<iso>.rootpw.txt: password + ISO name + build date) — the
single record of truth. Never stdout/logs/manifest; the manifest carries
only a pointer line. OUT_ISO naming hoisted above the mint (the sibling
is named after the ISO); the mint itself and ROOT_PLAIN's lifetime are
unchanged beyond the one file write. FELHOM_ISO_KEEP_WORK=1 debug escape
added for the harness. New test/rootpw-emission.sh: dry-run emission,
0600, plaintext<->answer-hash cross-check (openssl -6 -salt), no
plaintext on stdout, manifest-heredoc guard. Red-proof run: plaintext
injected into the manifest heredoc -> harness FAILs -> restored.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UuFPHmHNrCJj1VhY6QdDMU
This commit is contained in:
2026-07-22 10:04:41 +02:00
parent 1613bc7120
commit 9e292958c2
2 changed files with 103 additions and 7 deletions
+28 -7
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@@ -41,7 +41,7 @@
#===============================================================================
set -euo pipefail
ISO_VERSION="1.22.0" # Felhom release the ISO is tagged to (aligns with felhom-host-install SCRIPT_VERSION).
ISO_VERSION="1.24.0" # Felhom release the ISO is tagged to (aligns with felhom-host-install SCRIPT_VERSION).
IMAGE="${FELHOM_ISO_ASSISTANT_IMAGE:-felhom-iso-assistant:trixie}"
HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -208,7 +208,15 @@ fi
# --- workspace ------------------------------------------------------------------------------------
WORK="$(mktemp -d "${TMPDIR:-/tmp}/felhom-iso.XXXXXX")"
# chmod first: the mkimage surgery's osirrox extract leaves read-only file modes that rm can't clear.
cleanup() { chmod -R u+w "$WORK" 2>/dev/null || true; rm -rf "$WORK"; }
# FELHOM_ISO_KEEP_WORK=1 is a DEBUG/TEST escape: keep $WORK for post-mortem (the rootpw-emission
# harness cross-checks the emitted plaintext against the rendered answer's hash). Never a build mode.
cleanup() {
if [[ "${FELHOM_ISO_KEEP_WORK:-0}" == "1" ]]; then
log_warn "FELHOM_ISO_KEEP_WORK=1 — workspace KEPT at $WORK (debug/test only; delete it yourself)"
return 0
fi
chmod -R u+w "$WORK" 2>/dev/null || true; rm -rf "$WORK"
}
trap cleanup EXIT
mkdir -p "$OUT_DIR" "$WORK/tmp"
ISO_DIR="$(cd "$(dirname "$PVE_ISO")" && pwd)"; ISO_BASE="$(basename "$PVE_ISO")"
@@ -226,13 +234,27 @@ EOF
log_info "generated secret-free pairing env (hub=$PAIR_HUB_URL)"
fi
# --- resolve the output ISO name (needed by the mint below: the rootpw sibling file is named after
# the ISO). Rule 4: the loader mode is loud in the filename — a '-mkimage' ISO implies
# Secure-Boot-off prep. -----------------------------------------------------------------------
LOADER_SUFFIX=""; [[ "$LOADER" != "shim" ]] && LOADER_SUFFIX="-${LOADER}"
MODE_SUFFIX=""; $PAIRING && MODE_SUFFIX="-generic" # the secret-free universal ISO is unmistakable
OUT_ISO="$OUT_DIR/felhom-pve-${PVE_VERSION}-v${ISO_VERSION}-${PROFILE_NAME}${MODE_SUFFIX}${LOADER_SUFFIX}.iso"
# --- mint fresh THROWAWAY root hash ---------------------------------------------------------------
log_step "minting fresh throwaway root password hash"
ROOT_PLAIN="felhom-throwaway-$(head -c12 /dev/urandom | base64 | tr -dc 'A-Za-z0-9')"
ROOT_HASH="$(openssl passwd -6 "$ROOT_PLAIN")"
# R-61 slice 1: the baked root password becomes KNOWABLE. The plaintext is written to a 0600 sibling
# file next to the ISO — the SINGLE record of truth — and nowhere else: never stdout/stderr/logs,
# never the manifest (manifests get pasted into committed REPORTs; a separate file cannot ride along
# by accident). A fixed well-known password stays REJECTED (operator ruling 2026-07-21): a
# pre-pairing box sits on a stranger's LAN. Note: an aborted build can leave a rootpw file for an
# ISO that was never produced; the next build of the same name overwrites it.
( umask 077; printf '%s %s built %s\n' "$ROOT_PLAIN" "$(basename "$OUT_ISO")" "$(date -Is)" > "$OUT_ISO.rootpw.txt" )
unset ROOT_PLAIN
[[ -n "$ROOT_HASH" ]] || die "failed to mint root hash"
log_info "throwaway root hash written to the answer file (value stored out-of-band, not logged)"
log_info "throwaway root hash written to the answer file; plaintext in $(basename "$OUT_ISO").rootpw.txt (0600, operator-only — value not logged)"
# --- render answer.toml (pure bash param-expansion; no metachar hazards) ---------------------------
log_step "rendering answer.toml"
@@ -283,10 +305,7 @@ chmod 0755 "$STUB"
grep -q '@@BOOTSTRAP_.*_B64@@' "$STUB" && die "stub still has unfilled markers — injection failed"
# --- prepare-iso ----------------------------------------------------------------------------------
# Rule 4: the loader mode is loud in the filename — a '-mkimage' ISO implies Secure-Boot-off prep.
LOADER_SUFFIX=""; [[ "$LOADER" != "shim" ]] && LOADER_SUFFIX="-${LOADER}"
MODE_SUFFIX=""; $PAIRING && MODE_SUFFIX="-generic" # the secret-free universal ISO is unmistakable
OUT_ISO="$OUT_DIR/felhom-pve-${PVE_VERSION}-v${ISO_VERSION}-${PROFILE_NAME}${MODE_SUFFIX}${LOADER_SUFFIX}.iso"
# (OUT_ISO is resolved above the mint — the rootpw sibling file is named after it.)
GRUB_VERSION="" # populated by the mkimage surgery (the grub-mkimage build used)
log_step "building ISO: $(basename "$OUT_ISO")"
if $DRY_RUN; then
@@ -361,6 +380,7 @@ boot-menu : ${BRAND_NOTE}
$( $BRAND && cat "$WORK/brand-report.txt" 2>/dev/null || true )
host-install-url : $(grep -oE 'FELHOM_INSTALL_URL=[^ ]*' "$BOOTSTRAP_ENV" 2>/dev/null || echo 'https://felhom.eu/scripts/felhom-host-install.sh (default)')
secret-bearing : ${SECRET_BEARING}$( $PAIRING && echo ' (GENERIC ISO — carries NO customer secret)' || echo ' (embeds the customer retrieval passphrase — supervised/single-use, delete after the run)')
root-password : see $(basename "$OUT_ISO").rootpw.txt (operator-only; NEVER commit or paste into REPORTs)
output : $(basename "$OUT_ISO")
output-sha256 : ${OUT_SHA}
output-size-bytes : ${OUT_SIZE}
@@ -370,6 +390,7 @@ log_success "ISO built: $OUT_ISO"
log_info "sha256 : $OUT_SHA"
log_info "size : $OUT_SIZE bytes"
log_info "manifest : $OUT_ISO.manifest.txt"
log_info "root-pw : $OUT_ISO.rootpw.txt (0600, operator-only — the console credential for this build; never commit/paste)"
if $PAIRING; then
log_success "GENERIC secret-free ISO — carries NO customer secret. Bind the box on the hub after it registers."
else
+75
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@@ -0,0 +1,75 @@
#!/bin/bash
# rootpw-emission.sh — R-61 slice 1 regression harness for build-felhom-iso.sh's root-password
# emission. Runs ON THE BUILD HOST (needs docker + the assistant image present for the build
# script's preflight, but --dry-run never starts a container). Asserts, against a real dry-run
# with a fake source ISO:
# 1. the 0600 sibling <iso>.rootpw.txt exists and names the ISO it belongs to;
# 2. its plaintext MATCHES the hash actually rendered into answer.toml
# (openssl passwd -6 -salt <extracted> cross-check — file <-> answer, not file <-> itself);
# 3. the plaintext appears NOWHERE in the build's stdout/stderr;
# 4. the manifest heredoc in the build script carries the rootpw.txt POINTER and never
# references the plaintext variable (the manifest gets pasted into committed REPORTs —
# the plaintext must be structurally unable to ride along).
# Red-proof (documented, run manually): add `root-password-plain : ${ROOT_PLAIN}` to the manifest
# heredoc -> assertion 4 fails -> restore.
set -uo pipefail
HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BUILD="$HERE/../build-felhom-iso.sh"
fail=0
say() { echo "TEST: $*"; }
check() { if eval "$2"; then echo " ok: $1"; else echo " FAIL: $1"; fail=1; fi; }
SCRATCH="$(mktemp -d "${TMPDIR:-/tmp}/felhom-rootpw-test.XXXXXX")"
trap 'chmod -R u+w "$SCRATCH" 2>/dev/null; rm -rf "$SCRATCH"' EXIT
mkdir -p "$SCRATCH/tmp" "$SCRATCH/out"
# fake source ISO (the dry run only sha-verifies it; nothing reads its content as an ISO)
FAKE_ISO="$SCRATCH/proxmox-ve_9.9-1.iso"
head -c 65536 /dev/urandom > "$FAKE_ISO"
FAKE_SHA="$(sha256sum "$FAKE_ISO" | awk '{print $1}')"
say "dry-run build (pairing, nested-canary) with FELHOM_ISO_KEEP_WORK=1"
BUILD_LOG="$SCRATCH/build.log"
FELHOM_ISO_KEEP_WORK=1 TMPDIR="$SCRATCH/tmp" bash "$BUILD" \
--pve-iso "$FAKE_ISO" --iso-sha256 "$FAKE_SHA" \
--profile "$HERE/../profiles/nested-canary.profile" \
--pairing --out "$SCRATCH/out" --dry-run > "$BUILD_LOG" 2>&1
rc=$?
check "dry-run exited 0" "[ $rc -eq 0 ]"
ROOTPW_FILE="$(ls "$SCRATCH"/out/*.rootpw.txt 2>/dev/null | head -1)"
check "rootpw sibling file exists" "[ -n \"$ROOTPW_FILE\" ] && [ -f \"$ROOTPW_FILE\" ]"
check "rootpw file mode is 0600" "[ \"\$(stat -c %a \"$ROOTPW_FILE\")\" = 600 ]"
PW="$(awk '{print $1}' "$ROOTPW_FILE" 2>/dev/null)"
ISO_NAME="$(awk '{print $2}' "$ROOTPW_FILE" 2>/dev/null)"
check "password field has the throwaway shape" "[[ \"$PW\" == felhom-throwaway-* ]]"
check "file names the ISO it belongs to" "[ \"$ISO_NAME.rootpw.txt\" = \"$(basename "$ROOTPW_FILE")\" ]"
# cross-check: the plaintext must correspond to the hash RENDERED INTO THE ANSWER (kept workspace)
ANSWER="$(ls "$SCRATCH"/tmp/felhom-iso.*/answer.toml 2>/dev/null | head -1)"
check "kept workspace has answer.toml" "[ -n \"$ANSWER\" ] && [ -f \"$ANSWER\" ]"
# the hash contains literal $-signs — compare OUTSIDE check()'s eval and pass only a verdict in
HASH="$(sed -n 's/^root-password-hashed = "\(.*\)"$/\1/p' "$ANSWER" 2>/dev/null)"
SALT="$(printf '%s' "$HASH" | awk -F'$' '{print $3}')"
RECOMPUTED="$(openssl passwd -6 -salt "$SALT" "$PW" 2>/dev/null)"
HASH_MATCH=no; [ -n "$HASH" ] && [ "$RECOMPUTED" = "$HASH" ] && HASH_MATCH=yes
check "plaintext matches the answer's rendered hash" "[ \"$HASH_MATCH\" = yes ]"
# the plaintext must never surface on stdout/stderr
check "plaintext absent from build stdout/stderr" "! grep -qF \"$PW\" \"$BUILD_LOG\""
# manifest heredoc guard (source-level: dry-run emits no manifest; the live build's manifest is
# additionally verified in the ISO-build leg). Pointer present, plaintext variable absent.
# the heredoc text contains ${VAR} references — grep it outside check()'s eval, pass verdicts in
MANIFEST_SRC="$(awk '/^cat > "\$OUT_ISO.manifest.txt" <<EOF$/{f=1;next} f&&/^EOF$/{exit} f' "$BUILD")"
SRC_FOUND=no; [ -n "$MANIFEST_SRC" ] && SRC_FOUND=yes
HAS_POINTER=no; grep -q 'rootpw.txt' <<< "$MANIFEST_SRC" && HAS_POINTER=yes
LEAKS_PLAIN=no; grep -q 'ROOT_PLAIN' <<< "$MANIFEST_SRC" && LEAKS_PLAIN=yes
check "manifest heredoc found in build script" "[ \"$SRC_FOUND\" = yes ]"
check "manifest carries the rootpw.txt pointer" "[ \"$HAS_POINTER\" = yes ]"
check "manifest never references ROOT_PLAIN" "[ \"$LEAKS_PLAIN\" = no ]"
echo "=================================================="
if [ $fail -eq 0 ]; then echo "ALL ROOTPW-EMISSION TESTS PASSED"; else echo "SOME TESTS FAILED"; fi
exit $fail