V8.13.408.2025.11.13

Signed-off-by: Marc S. Weidner <msw@coresecret.dev>

config/includes.chroot/usr/lib/live/boot/0022-ciss-overlay-tmpfs.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+# bashsupport disable=BP5007
+# shellcheck disable=SC2249
+# shellcheck shell=sh
+
+# SPDX-Version: 3.0
+# SPDX-CreationInfo: 2025-11-12; 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: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
+# SPDX-FileType: SOURCE
+# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
+# 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
+
+# Purpose: Pre-create constrained tmpfs for OverlayFS upper/work before live-boot mounts overlay.
+# Phase  : premount (executed by live-boot inside the initramfs).
+
+set -eu
+
+### Phase gate: run only in the intended live-boot phase -----------------------------------------------------------------------
+PHASE="${1:-}"
+
+case "${PHASE}" in
+
+  premount)
+    ;;      ### Continue.
+  *)
+    exit 0  ### Do nothing in other phases.
+    ;;
+
+esac
+
+printf "\e[95m[INFO] Starting: [/usr/lib/live/boot/0022-ciss-overlay-tmpfs.sh] ... \n\e[0m"
+
+### Declare variables ----------------------------------------------------------------------------------------------------------
+OVERLAY_BASE="/run/live/overlay"
+UPPER="${OVERLAY_BASE}/upper"
+WORK="${OVERLAY_BASE}/work"
+
+### Size policy: hard ceiling to mitigate RAM-filling DoS; tune to your ISO profile.
+: "${CDLB_OVERLAY_TMPFS_SIZE:=70%}"
+
+### Create a base dir with restrictive perms.
+# shellcheck disable=SC2174
+mkdir -p -m 0700 "${OVERLAY_BASE}"
+
+### Mount dedicated tmpfs with strict flags; 'noexec' here blocks accidental execs from the raw tmpfs path.
+mount -t tmpfs -o "size=${CDLB_OVERLAY_TMPFS_SIZE},mode=0700,nosuid,nodev,noexec" tmpfs "${OVERLAY_BASE}"
+
+# Prepare upper/work with tight perms.
+# shellcheck disable=SC2174
+mkdir -p -m 0700 "${UPPER}" "${WORK}"
+
+printf "\e[92m[INFO] Successfully applied: [/usr/lib/live/boot/0022-ciss-overlay-tmpfs.sh] \n\e[0m"
+
+exit 0
+
+# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh