V9.14.022.2026.06.11: document and test audit safeguards

README.md

@@ -60,12 +60,15 @@ and spoofing surfaces.
 
 Internally, the builder employs a dedicated secret-handling pipeline backed by a tmpfs-only secrets directory
 (`/dev/shm/cdlb_secrets`). Sensitive material such as root passwords, SSH keys, and signing keys never appears on the command
-line, is guarded by strict `0400 root:root` permissions, and any symlink inside the secret path is treated as a hard failure
+line, is guarded by a `0700 root:root` secret root and single-link regular `0400` or `0600` root-owned files, and any symlink
-that aborts the run. Critical code paths temporarily disable Bash xtrace so that credentials never leak into debug logs, and
+inside the secret path is treated as a hard failure that aborts the run. Filename-only secret arguments reject slashes and
-transient secret files are shredded (`shred -fzu`) as soon as they are no longer needed. GNUPG homes used for signing are
+traversal.
-wiped, unencrypted chroot artifacts and includes are removed after `lb build`, and the final artifact is reduced to the
+Critical code paths temporarily disable Bash xtrace, and a final exact-value debug-log sanitisation pass provides additional
-encrypted SquashFS inside the LUKS2 container. At runtime, LUKS passphrases in the live ISO and installer are transported via
+defence in depth. Transient secret files are shredded (`shred -fzu`) as soon as they are no longer needed, but this is only a
-named pipes inside the initramfs instead of process arguments, further minimizing exposure in process listings.
+best-effort cleanup on SSD, NVMe, copy-on-write, journaled, and virtualised storage. Use tmpfs for secrets and encrypted storage
+for build workspaces. Destructive build cleanup is restricted to the exact canonical directory carrying the
+`.ciss-live-builder-owned` marker. This private operator workflow still requires strict local path validation; it does not
+define public ISO release policy.
 
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 * [CenturionDNS Resolver](https://eddns.eu/)
@@ -493,10 +496,14 @@ To use **``CISS.debian.live.builder``** as intended, the following baseline is e
    
 2. Preparation:
    1. Ensure you are root.
-   2. Create the build directory `mkdir /opt/cdlb` and the tmpfs secrets directory `mkdir /dev/shm/cdlb_secrets`.
+   2. Create the empty build directory with `install -d -m 0700 -o root -g root /opt/cdlb`.
-   3. Place your desired SSH public key in the `authorized_keys` file, for example, in the `/dev/shm/cdlb_secrets` directory.
+   3. Create the tmpfs secret root with `install -d -m 0700 -o root -g root /dev/shm/cdlb_secrets`.
-   4. Place your desired Password in the `password.txt` file, for example, in the `/dev/shm/cdlb_secrets` directory.
+   4. Place required secret files in the secret root as single-link regular, non-symlink, root-owned files with mode `0400`
-   5. Make any other changes you need to.
+      or `0600`.
+   5. Place your desired SSH public key in `/dev/shm/cdlb_secrets/authorized_keys`.
+   6. Place your desired root password in `/dev/shm/cdlb_secrets/password.txt`.
+   7. Use filename-only values without slashes, `.` or `..` for `--key_age`, `--key_luks`, and signing-file arguments.
+   8. Make any other changes you need to.
 
 3. Run the config builder script `./ciss_live_builder.sh` and the integrated `lb build` command (example):
 
@@ -538,6 +545,10 @@ To use **``CISS.debian.live.builder``** as intended, the following baseline is e
    both the newer Sigstore bundle asset, and the legacy-split certificate/signature assets before checking the downloaded
    SOPS binary with `sha256sum -c --ignore-missing`.
 
+   On the first run, the builder creates `.ciss-live-builder-owned` in a new or empty build directory whose canonical parent
+   already exists. A populated directory without that marker is rejected and is never adopted automatically. Cleanup remains
+   intentionally destructive inside the exact validated marker-owned directory.
+
 4. Locate your ISO in the `--build-directory`.
 5. Boot from the ISO and login to the live image via the console, or the multi-layer secured **coresecret** SSH tunnel.
 6. Type `sysp` for the final kernel hardening features.
@@ -559,7 +570,8 @@ preview it or run it.
 
 2. Preparation:
    1. Ensure you are root.
-   2. Create the build directory `mkdir /opt/cdlb` and the tmpfs secrets directory `mkdir /dev/shm/cdlb_secrets`.
+   2. Create the empty build directory and tmpfs secret root with restrictive ownership and permissions:
+      `install -d -m 0700 -o root -g root /opt/cdlb /dev/shm/cdlb_secrets`.
    3. Place your desired SSH public key in the `authorized_keys` file, for example, in the `/dev/shm/cdlb_secrets` directory.
    4. Place your desired Password in the `password.txt` file, for example, in the `/dev/shm/cdlb_secrets` directory.
    5. Copy and edit the sample and set your options (no spaces around commas in lists): 
@@ -656,10 +668,10 @@ The private directory is ignored by Git. The hooks fail if the CISS EFI image si
   #...
         - name: Preparing the build environment.
           run: |
-            mkdir -p /opt/config
+            install -d -m 0700 -o root -g root /opt/livebuild /dev/shm/cdlb_secrets
-            mkdir -p /opt/livebuild
+            umask 0077
-            echo "${{ secrets.CHANGE_ME }}" >| /opt/config/password.txt
+            printf '%s\n' "${{ secrets.CHANGE_ME }}" >| /dev/shm/cdlb_secrets/password.txt
-            echo "${{ secrets.CHANGE_ME }}" >| /opt/config/authorized_keys
+            printf '%s\n' "${{ secrets.CHANGE_ME }}" >| /dev/shm/cdlb_secrets/authorized_keys
   #...
         - name: Starting CISS.debian.live.builder. This may take a while ...
           run: |
@@ -672,9 +684,9 @@ The private directory is ignored by Git. The hooks fail if the CISS EFI image si
               --build-directory /opt/livebuild \
               --control "${timestamp}" \
               --jump-host "${{ secrets.CHANGE_ME }}" \
-              --root-password-file /opt/config/password.txt \
+              --root-password-file /dev/shm/cdlb_secrets/password.txt \
               --ssh-port CHANGE_ME \
-              --ssh-pubkey /opt/config
+              --ssh-pubkey /dev/shm/cdlb_secrets
   #...
         ### SKIP OR CHANGE ALL REMAINING STEPS
   ```

docs/DOCUMENTATION.md

@@ -37,6 +37,10 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
 
   --build-directory </path/to/build_directory>
     Where the Debian Live Build Image should be generated. RECOMMENDED path: </opt/cdlb>
+    The path MUST be canonical and dedicated to the builder; a new directory's canonical parent MUST already exist.
+    New or empty directories receive the
+    '.ciss-live-builder-owned' marker; populated unmarked directories are rejected. Cleanup is intentionally destructive
+    only inside the exact validated marker-owned directory.
     MUST be provided.
 
   --change-splash <STRING> one of <club | hexagon>
@@ -57,6 +61,7 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
   --debug, -d
     Enables debug logging for the main program routine. Detailed logging information are written to:
     </tmp/ciss_live_builder_1801049.log>
+    A final exact-value sanitisation pass is defence in depth and does not replace careful tracing discipline.
 
   --dhcp-centurion
     If a DHCP lease is provided, the provider's name server will be overridden and the hardened, privacy-focused
@@ -86,11 +91,13 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
 
   --key_age=*
     The SOPS AGE private keyring for decryption operations. Change '*' to your desired SOPS AGE key file.
+    '*' MUST be a filename only without slashes, '.' or '..' traversal.
     File MUST be placed in:
     </dev/shm/cdlb_secrets>
 
   --key_luks=*
     The LUKS encryption / decryption passphrase for '/'-fs-encryption. Change '*' to your desired passphrase file.
+    '*' MUST be a filename only without slashes, '.' or '..' traversal.
     File MUST be placed in:
     </dev/shm/cdlb_secrets>
 
@@ -140,7 +147,7 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
   --root-password-file </dev/shm/cdlb_secrets/password.txt>>
     Password file for 'root', if given, MUST be a string of 42 to 64 characters.
     If the argument is omitted, no further login authentication is required for the local console.
-    MUST be placed in:
+    Safe absolute paths remain supported and are validated separately. RECOMMENDED path:
     </dev/shm/cdlb_secrets/password.txt>
 
   --secure-boot-profile <STRING> one of <debian-shim | ciss-uki>
@@ -156,7 +163,8 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
     specified via '--signing_key=*'. If the keyring is protected, then provide the passphrase in its own file.
     Specify the fingerprint of the key to use via '--signing_key_fpr=*'.
     Optionally import an offline GPG CA signing public key via: '--signing_ca=*'.
-    Change '*' to your desired files / fingerprint. Files MUST be placed in:
+    Change '*' to your desired filename-only files / fingerprint. Filename-only values MUST NOT contain slashes or traversal.
+    Files MUST be placed in:
     </dev/shm/cdlb_secrets>
 
   --sshfp
@@ -182,6 +190,9 @@ A lightweight Shell Wrapper for building a hardened Debian Live ISO Image.
 
 💡 Notes:
 🔵 You MUST be 'root' to run this script.
+🔵 Private operator control does not remove the requirement for strict local secret path validation.
+🔵 '/dev/shm/cdlb_secrets' MUST be tmpfs-backed, root-owned, mode 0700, and contain only single-link regular non-symlink files
+   with mode 0400 or 0600. Secure deletion with shred is best-effort only on modern storage.
 
 💷 Please consider donating to my work at:
 🌐 https://coresecret.eu/spenden/

lib/lib_usage.sh

@@ -67,6 +67,10 @@ usage() {
     echo
     echo -e "\e[97m  --build-directory </path/to/build_directory> \e[0m"
     echo "    Where the Debian Live Build Image should be generated. RECOMMENDED path: </opt/cdlb>"
+    echo "    The path MUST be canonical and dedicated to the builder; a new directory's canonical parent MUST already exist."
+    echo "    New or empty directories receive the"
+    echo "    '.ciss-live-builder-owned' marker; populated unmarked directories are rejected. Cleanup is intentionally"
+    echo "    destructive only inside the exact validated marker-owned directory."
     echo "    MUST be provided."
     echo
     echo -e "\e[97m  --change-splash <STRING> one of <club | hexagon> \e[0m"
@@ -87,6 +91,7 @@ usage() {
     echo -e "\e[97m  --debug, -d \e[0m"
     echo "    Enables debug logging for the main program routine. Detailed logging information are written to:"
     echo "    </tmp/ciss_live_builder_$$.log>"
+    echo "    A final exact-value sanitisation pass is defence in depth and does not replace careful tracing discipline."
     echo
     echo -e "\e[97m  --dhcp-centurion \e[0m"
     echo "    If a DHCP lease is provided, the provider's name server will be overridden and the hardened, privacy-focused "
@@ -108,11 +113,13 @@ usage() {
     echo
     echo -e "\e[97m  --key_age=* \e[0m"
     echo "    The SOPS AGE private keyring for decryption operations. Change '*' to your desired SOPS AGE key file."
+    echo "    '*' MUST be a filename only without slashes, '.' or '..' traversal."
     echo "    File MUST be placed in:"
     echo "    </dev/shm/cdlb_secrets>"
     echo
     echo -e "\e[97m  --key_luks=* \e[0m"
     echo "    The LUKS encryption / decryption passphrase for '/'-fs-encryption. Change '*' to your desired passphrase file."
+    echo "    '*' MUST be a filename only without slashes, '.' or '..' traversal."
     echo "    File MUST be placed in:"
     echo "    </dev/shm/cdlb_secrets>"
     echo
@@ -162,7 +169,7 @@ usage() {
     echo -e "\e[97m  --root-password-file </dev/shm/cdlb_secrets/password.txt>> \e[0m"
     echo "    Password file for 'root', if given, MUST be a string of 42 to 64 characters."
     echo "    If the argument is omitted, no further login authentication is required for the local console."
-    echo "    MUST be placed in:"
+    echo "    Safe absolute paths remain supported and are validated separately. RECOMMENDED path:"
     echo "    </dev/shm/cdlb_secrets/password.txt>"
     echo
     echo -e "\e[97m  --secure-boot-profile <STRING> one of <debian-shim | ciss-uki> \e[0m"
@@ -178,7 +185,8 @@ usage() {
     echo "    specified via '--signing_key=*'. If the keyring is protected, then provide the passphrase in its own file."
     echo "    Specify the fingerprint of the key to use via '--signing_key_fpr=*'."
     echo "    Optionally import an offline GPG CA signing public key via: '--signing_ca=*'."
-    echo "    Change '*' to your desired files / fingerprint. Files MUST be placed in:"
+    echo "    Change '*' to your desired filename-only files / fingerprint. Filename-only values MUST NOT contain slashes"
+    echo "    or traversal. Files MUST be placed in:"
     echo "    </dev/shm/cdlb_secrets>"
     echo
     echo -e "\e[97m  --sops-version <STRING> \e[0m"
@@ -212,6 +220,9 @@ usage() {
     echo
     echo -e "\e[93m💡 Notes: \e[0m"
     echo -e "\e[93m🔵 You MUST be 'root' to run this script. \e[0m"
+    echo -e "\e[93m🔵 Private operator control does not remove the requirement for strict local secret path validation. \e[0m"
+    echo -e "\e[93m🔵 '/dev/shm/cdlb_secrets' MUST be tmpfs-backed, root-owned, mode 0700, and contain only \e[0m"
+    echo -e "\e[93m   single-link regular secret files with mode 0400 or 0600. Secure deletion with shred is best-effort only. \e[0m"
     echo
     echo -e "\e[95m💷 Please consider donating to my work at: \e[0m"
     echo -e "\e[95m🌐 https://coresecret.eu/spenden/ \e[0m"

tests/test_secret_debug_cleanup.sh

@@ -0,0 +1,191 @@
+#!/bin/bash
+# SPDX-Version: 3.0
+# SPDX-CreationInfo: 2026-06-11; WEIDNER, Marc S.; <msw@coresecret.dev>
+# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
+# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
+# SPDX-FileCopyrightText: 2024-2026; WEIDNER, Marc S.; <msw@coresecret.dev>
+# SPDX-FileType: SOURCE
+# SPDX-License-Identifier: LicenseRef-CNCL-1.1 OR LicenseRef-CCLA-1.1
+# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
+# SPDX-PackageName: CISS.debian.live.builder
+# SPDX-Security-Contact: security@coresecret.eu
+set -Ceuo pipefail
+# shellcheck disable=SC1091,SC2034
+
+declare TEST_ROOT=""
+declare TEST_TMP=""
+TEST_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+TEST_TMP="$(realpath "$(mktemp -d)")"
+readonly TEST_ROOT TEST_TMP
+declare -r ERR_BUILD_PATH=217
+declare -r ERR_GUARD_SRCE=131
+declare -r ERR_SANITIZING=133
+declare -r ERR_SECRET_PATH=216
+declare -r VAR_WORKDIR="${TEST_ROOT}"
+declare VAR_TMP_SECRET="${TEST_TMP}/secret-root"
+declare LOG_DEBUG=""
+declare LOG_ERROR=""
+declare LOG_VAR=""
+declare VAR_EARLY_DEBUG="false"
+declare ERRTRAP="true"
+
+cleanup_test() {
+  chmod -R u+rwX "${TEST_TMP}" 2>/dev/null || true
+  rm -rf "${TEST_TMP}"
+}
+trap cleanup_test EXIT
+
+guard_sourcing() {
+  return 0
+}
+
+# shellcheck source=../lib/lib_secret_validation.sh
+. "${TEST_ROOT}/lib/lib_secret_validation.sh"
+# shellcheck source=../lib/lib_build_directory.sh
+. "${TEST_ROOT}/lib/lib_build_directory.sh"
+# shellcheck source=../lib/lib_debug_sanitizer.sh
+. "${TEST_ROOT}/lib/lib_debug_sanitizer.sh"
+# shellcheck source=../lib/lib_trap_on_exit.sh
+. "${TEST_ROOT}/lib/lib_trap_on_exit.sh"
+
+fail() {
+  printf 'FAIL: %s\n' "$1" >&2
+  exit 1
+}
+
+expect_failure() {
+  declare description="$1"
+  shift
+  if "$@" >/dev/null 2>&1; then
+    fail "${description}"
+  fi
+}
+
+mkdir -m 0700 "${VAR_TMP_SECRET}"
+printf 'safe-private-value\n' > "${VAR_TMP_SECRET}/safe.txt"
+chmod 0400 "${VAR_TMP_SECRET}/safe.txt"
+
+validate_secret_directory "${VAR_TMP_SECRET}" "test secret root" "false" || fail "safe secret root rejected"
+validate_secret_filename "safe.txt" "test secret filename" || fail "safe secret filename rejected"
+validate_secret_file "${VAR_TMP_SECRET}/safe.txt" "test secret file" || fail "safe secret file rejected"
+validate_secret_absolute_file "${VAR_TMP_SECRET}/safe.txt" "test absolute secret file" \
+  || fail "safe absolute secret file rejected"
+expect_failure "relative external secret path accepted" \
+  validate_secret_absolute_file "secret-root/safe.txt" "test absolute secret file"
+mkdir -m 0700 "${TEST_TMP}/external-secret-dir"
+printf 'external-private-value\n' > "${TEST_TMP}/external-secret-dir/external.txt"
+chmod 0400 "${TEST_TMP}/external-secret-dir/external.txt"
+ln -s "${TEST_TMP}/external-secret-dir" "${TEST_TMP}/external-secret-dir-link"
+expect_failure "external secret file through a symlinked parent accepted" \
+  validate_secret_absolute_file "${TEST_TMP}/external-secret-dir-link/external.txt" "test absolute secret file"
+expect_failure "external secret directory through a symlinked parent accepted" \
+  validate_secret_absolute_directory "${TEST_TMP}/external-secret-dir-link" "test absolute secret directory"
+declare secret_root_fs=""
+secret_root_fs="$(secure_stat -f -c '%T' "${VAR_TMP_SECRET}")"
+if [[ "${secret_root_fs}" != "tmpfs" && "${secret_root_fs}" != "ramfs" ]]; then
+  expect_failure "persistent secret staging area accepted" validate_secret_staging_area
+fi
+expect_failure "secret filename traversal accepted" validate_secret_filename "../safe.txt" "test secret filename"
+expect_failure "absolute filename-only secret accepted" validate_secret_filename "/tmp/safe.txt" "test secret filename"
+expect_failure "slash in filename-only secret accepted" validate_secret_filename "subdir/safe.txt" "test secret filename"
+
+ln -s "${VAR_TMP_SECRET}" "${TEST_TMP}/secret-root-link"
+expect_failure "secret-root symlink accepted" \
+  validate_secret_directory "${TEST_TMP}/secret-root-link" "test secret root" "false"
+mkdir -m 0700 "${TEST_TMP}/unsafe-secret-root-mode"
+chmod 0755 "${TEST_TMP}/unsafe-secret-root-mode"
+expect_failure "broad secret-root permissions accepted" \
+  validate_secret_directory "${TEST_TMP}/unsafe-secret-root-mode" "test secret root" "false"
+ln -s "${VAR_TMP_SECRET}/safe.txt" "${VAR_TMP_SECRET}/unsafe-link"
+expect_failure "secret-file symlink accepted" validate_secret_file "${VAR_TMP_SECRET}/unsafe-link" "test secret file"
+rm "${VAR_TMP_SECRET}/unsafe-link"
+ln "${VAR_TMP_SECRET}/safe.txt" "${VAR_TMP_SECRET}/unsafe-hardlink"
+expect_failure "hardlinked secret file accepted" validate_secret_file "${VAR_TMP_SECRET}/safe.txt" "test secret file"
+rm "${VAR_TMP_SECRET}/unsafe-hardlink"
+
+declare fake_secret='CISS-CANARY-[exact]-value'
+declare expected_redaction=""
+declare sanitisation_status=0
+printf -v expected_redaction '%*s' "${#fake_secret}" ''
+expected_redaction="${expected_redaction// /*}"
+register_secret_value "${fake_secret}"
+
+LOG_DEBUG="${TEST_TMP}/debug.log"
+LOG_VAR="${TEST_TMP}/var.log"
+LOG_ERROR="${TEST_TMP}/error.log"
+printf 'before %s after\nunrelated line\n' "${fake_secret}" > "${LOG_DEBUG}"
+printf 'unrelated vars\n' > "${LOG_VAR}"
+printf 'unrelated error\n' > "${LOG_ERROR}"
+chmod 0600 "${LOG_DEBUG}" "${LOG_VAR}" "${LOG_ERROR}"
+
+sanitize_debug_logs || fail "debug-log sanitisation failed"
+grep -Fq "${fake_secret}" "${LOG_DEBUG}" && fail "debug-log canary remained"
+grep -Fq "${expected_redaction}" "${LOG_DEBUG}" || fail "expected exact-value redaction missing"
+grep -Fq 'unrelated line' "${LOG_DEBUG}" || fail "unrelated debug content changed"
+
+ln -s "${LOG_DEBUG}" "${TEST_TMP}/unsafe-debug-link"
+(
+  LOG_DEBUG="${TEST_TMP}/unsafe-debug-link"
+  trap_on_exit 73 "test" 1 "test" "false"
+) 2>/dev/null || sanitisation_status=$?
+[[ ${sanitisation_status} -eq 73 ]] || fail "sanitisation failure masked the original exit status"
+
+expect_failure "empty build-directory path accepted" validate_build_directory_path ""
+expect_failure "root build-directory path accepted" validate_build_directory_path "/"
+expect_failure "broad parent build-directory path accepted" validate_build_directory_path "/tmp"
+expect_failure "secret root accepted as build directory" validate_build_directory_path "${VAR_TMP_SECRET}"
+mkdir -m 0700 "${VAR_TMP_SECRET}/unsafe-build-child"
+expect_failure "secret-root descendant accepted as build directory" \
+  validate_build_directory_path "${VAR_TMP_SECRET}/unsafe-build-child"
+
+mkdir -m 0700 "${TEST_TMP}/unmarked"
+expect_failure "build directory without marker accepted" validate_build_directory_marker "${TEST_TMP}/unmarked"
+printf 'do-not-adopt\n' > "${TEST_TMP}/unmarked/content"
+expect_failure "non-empty unmarked build directory adopted" initialize_build_directory "${TEST_TMP}/unmarked" unsafe_result
+
+mkdir -m 0700 "${TEST_TMP}/unsafe-build-mode"
+chmod 0777 "${TEST_TMP}/unsafe-build-mode"
+expect_failure "unsafe build-directory permissions accepted" \
+  initialize_build_directory "${TEST_TMP}/unsafe-build-mode" unsafe_result
+
+mkdir -m 0700 "${TEST_TMP}/marker-link-dir"
+printf '%s\n' "${TEST_TMP}/marker-link-dir" > "${TEST_TMP}/marker-target"
+chmod 0400 "${TEST_TMP}/marker-target"
+ln -s "${TEST_TMP}/marker-target" "${TEST_TMP}/marker-link-dir/.ciss-live-builder-owned"
+expect_failure "symlinked builder-owned marker accepted" validate_build_directory_marker "${TEST_TMP}/marker-link-dir"
+
+mkdir -m 0700 "${TEST_TMP}/marker-hardlink-dir"
+printf '%s\n' "${TEST_TMP}/marker-hardlink-dir" > "${TEST_TMP}/marker-hardlink-target"
+chmod 0400 "${TEST_TMP}/marker-hardlink-target"
+ln "${TEST_TMP}/marker-hardlink-target" "${TEST_TMP}/marker-hardlink-dir/.ciss-live-builder-owned"
+expect_failure "hardlinked builder-owned marker accepted" validate_build_directory_marker "${TEST_TMP}/marker-hardlink-dir"
+
+mkdir -m 0700 "${TEST_TMP}/marker-extra-content-dir"
+printf '%s\nunexpected\n' "${TEST_TMP}/marker-extra-content-dir" \
+  > "${TEST_TMP}/marker-extra-content-dir/.ciss-live-builder-owned"
+chmod 0400 "${TEST_TMP}/marker-extra-content-dir/.ciss-live-builder-owned"
+expect_failure "builder-owned marker with extra content accepted" \
+  validate_build_directory_marker "${TEST_TMP}/marker-extra-content-dir"
+
+ln -s "${TEST_TMP}/unmarked" "${TEST_TMP}/build-link"
+expect_failure "build-directory symlink accepted" validate_build_directory_path "${TEST_TMP}/build-link"
+
+declare validated_build_dir=""
+initialize_build_directory "${TEST_TMP}/owned-build" validated_build_dir || fail "safe builder-owned directory rejected"
+validate_build_directory_marker "${validated_build_dir}" || fail "builder marker rejected"
+mkdir "${validated_build_dir}/subdir"
+printf 'remove me\n' > "${validated_build_dir}/artifact"
+printf 'remove me too\n' > "${validated_build_dir}/.hidden-artifact"
+printf 'nested\n' > "${validated_build_dir}/subdir/nested"
+clean_build_directory_contents "${validated_build_dir}" || fail "safe builder-owned cleanup failed"
+validate_build_directory_marker "${validated_build_dir}" || fail "builder marker removed by cleanup"
+[[ -z "$(find "${validated_build_dir}" -mindepth 1 ! -name '.ciss-live-builder-owned' -print -quit)" ]] \
+  || fail "builder-owned cleanup left unexpected content"
+
+mkdir -m 0700 "${TEST_TMP}/outside-build"
+mkdir "${TEST_TMP}/outside-build/includes.chroot"
+ln -s "${TEST_TMP}/outside-build" "${validated_build_dir}/config"
+expect_failure "cleanup subpath through a symlinked parent accepted" \
+  validate_build_directory_subpath "${validated_build_dir}" "config/includes.chroot" unsafe_subpath
+
+printf 'PASS: secret validation, debug sanitisation, and build cleanup guards\n'