initramfs-module-luks-ftpm: Add fTPM support

Add initramfs module to dynamic-layers/tpm-layer providing LUKS2 full
disk encryption with TPM-sealed keys for TI K3 platforms. Keys are
sealed by firmware TPM (fTPM) running in OP-TEE and stored in eMMC
RPMB.

Features:
- First-boot in-place encryption with tpm2_getrandom key generation
- TPM-sealed key storage via persistent handle 0x81080001
- Automatic unlock on subsequent boots
- Space verification ensuring 32MB available for LUKS header

The module is built only when meta-tpm layer is present and gets
included in initramfs only when DISTRO_FEATURES='luks' and
MACHINE_FEATURES='optee-ftpm'

LUKS packages (cryptsetup, tpm2-tools, tpm2-tss, optee-ftpm,
e2fsprogs-*) significantly increase initramfs size beyond the default
131072 limit. Increase INITRAMFS_MAXSIZE to 200000 to accommodate
these packages.

Signed-off-by: Shiva Tripathi <s-tripathi1@ti.com>
Signed-off-by: Ryan Eatmon <reatmon@ti.com>

4 files changed, 388 insertions, 0 deletions

diff --git a/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm/luksftpm b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm/luksftpm
new file mode 100644
index 00000000..5e3aedc4
--- /dev/null
+++ b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm/luksftpm
@@ -0,0 +1,341 @@
+#!/bin/sh
+# initramfs-framework module for LUKS encryption with fTPM support
+
+# Configuration
+BOOT_DEV="/dev/mmcblk1p1"           # Boot partition (FAT, unencrypted)
+ROOT_DEV="/dev/mmcblk1p2"           # Root partition (will be encrypted)
+CRYPT_NAME="root_crypt"
+CRYPT_DEV="/dev/mapper/${CRYPT_NAME}"
+BOOT_MNT="/boot_part"
+TPM_PRIMARY_CTX="/tmp/tpm_primary.ctx"
+TPM_KEY_PRIV="/tmp/tpm_key.priv"
+TPM_KEY_PUB="/tmp/tpm_key.pub"
+TPM_KEY_CTX="/tmp/tpm_key.ctx"
+TPM2_HANDLE="0x81080001"            # TPM persistent handle for LUKS key
+ENCRYPTION_MARKER="${BOOT_MNT}/.encryption_in_progress"
+
+# Wait for MMC device to appear
+wait_for_device() {
+    local device="$1"
+    local timeout="${2:-10}"
+
+    msg "Waiting for storage device ${device}..."
+    for i in $(seq 1 ${timeout}); do
+        if [ -b "${device}" ]; then
+            return 0
+        fi
+        sleep 1
+    done
+    return 1
+}
+
+# Initialize fTPM and check availability
+init_ftpm() {
+    msg "Initializing secure hardware (fTPM)..."
+
+    # Start TEE supplicant (required for fTPM TA to work)
+    if [ -x /usr/sbin/tee-supplicant ]; then
+        /usr/sbin/tee-supplicant -d &
+        TEE_SUPPLICANT_PID=$!
+        sleep 5
+    else
+        info "Warning: Trusted execution environment not available"
+        return 1
+    fi
+
+    # Load fTPM kernel module
+    if ! /sbin/modprobe tpm_ftpm_tee; then
+        info "Warning: TPM module failed to load"
+        return 1
+    fi
+
+    # Wait for TPM device
+    for i in $(seq 1 10); do
+        if [ -c /dev/tpmrm0 ]; then
+            export TPM2TOOLS_TCTI="device:/dev/tpmrm0"
+            return 0
+        fi
+        sleep 1
+    done
+
+    info "Warning: fTPM not available - encryption will be skipped"
+    return 1
+}
+
+# Generate 32-byte random key using TPM RNG
+generate_random_key() {
+    /usr/bin/tpm2_getrandom --hex 32
+}
+
+# Seal data with TPM and store in persistent handle
+tpm_seal_key() {
+    local KEY_DATA="$1"
+
+    # Create primary key in owner hierarchy
+    /usr/bin/tpm2_createprimary -C o -c "${TPM_PRIMARY_CTX}" -Q || return 1
+
+    # Create sealed object
+    echo -n "${KEY_DATA}" | \
+        /usr/bin/tpm2_create -C "${TPM_PRIMARY_CTX}" \
+        -u "${TPM_KEY_PUB}" -r "${TPM_KEY_PRIV}" \
+        -i- -Q || return 1
+
+    # Load sealed object into TPM
+    /usr/bin/tpm2_load -C "${TPM_PRIMARY_CTX}" \
+        -u "${TPM_KEY_PUB}" -r "${TPM_KEY_PRIV}" \
+        -c "${TPM_KEY_CTX}" -Q || return 1
+
+    # Make key persistent at handle (stored in TPM NV RAM - RPMB)
+    /usr/bin/tpm2_evictcontrol -C o -c "${TPM_KEY_CTX}" "${TPM2_HANDLE}" || return 1
+
+    return 0
+}
+
+# Unseal data from TPM persistent handle
+tpm_unseal_key() {
+    # Check if persistent handle exists
+    if ! /usr/bin/tpm2_getcap handles-persistent | grep -q "${TPM2_HANDLE}"; then
+        debug "ERROR: TPM persistent handle not found"
+        return 1
+    fi
+
+    # Unseal key directly from persistent handle
+    /usr/bin/tpm2_unseal -c "${TPM2_HANDLE}" || return 1
+
+    return 0
+}
+
+# Perform in-place LUKS encryption (first boot)
+encrypt_root_filesystem() {
+    msg "=========================================="
+    msg "First boot: Encrypting root filesystem"
+    msg "=========================================="
+
+    # Set marker to track encryption progress
+    touch "${ENCRYPTION_MARKER}"
+    sync
+
+    # Generate random encryption key using TPM RNG
+    msg "Generating encryption key..."
+    LUKS_KEY=$(generate_random_key)
+
+    if [ -z "${LUKS_KEY}" ]; then
+        msg "ERROR: Failed to generate encryption key"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    fi
+
+    # Seal key with TPM before encryption starts
+    msg "Securing key with TPM..."
+    if ! tpm_seal_key "${LUKS_KEY}"; then
+        msg "ERROR: Failed to secure key"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    fi
+
+    # Filesystem check before encryption
+    msg "Checking filesystem integrity..."
+    /usr/sbin/e2fsck -f -y "${ROOT_DEV}"
+    E2FSCK_RET=$?
+    if [ ${E2FSCK_RET} -ge 4 ]; then
+        msg "ERROR: Filesystem check failed"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    fi
+
+    # Shrink filesystem before encryption to leave room for LUKS header
+    msg "Preparing filesystem for encryption..."
+    /usr/sbin/resize2fs -M "${ROOT_DEV}" || {
+        msg "ERROR: Failed to prepare filesystem"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    }
+
+    # Verify partition has sufficient space for LUKS header
+    msg "Verifying space for encryption..."
+    MIN_BLOCKS=$(/usr/sbin/resize2fs -P "${ROOT_DEV}" 2>&1 | awk '/[Mm]inimum.*:/ {print $NF}')
+
+    # Get filesystem block size and device size
+    BLOCK_SIZE=$(/usr/sbin/tune2fs -l "${ROOT_DEV}" 2>/dev/null | awk '/^Block size:/ {print $NF}')
+    DEV_NAME=$(basename "${ROOT_DEV}")
+    PART_SECTORS=$(cat /sys/class/block/"${DEV_NAME}"/size 2>/dev/null)
+
+    if [ -z "${MIN_BLOCKS}" ] || [ -z "${BLOCK_SIZE}" ] || [ -z "${PART_SECTORS}" ]; then
+        msg "ERROR: Unable to determine partition geometry"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    fi
+
+    # Convert filesystem blocks to 512-byte sectors
+    MIN_SECTORS=$((MIN_BLOCKS * BLOCK_SIZE / 512))
+    LUKS_SECTORS=65536  # 32MB in 512-byte sectors
+
+    if [ $((PART_SECTORS - MIN_SECTORS)) -lt ${LUKS_SECTORS} ]; then
+        msg "ERROR: Insufficient space for LUKS header (need 32MB free)"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    fi
+
+    # Perform in-place encryption
+    msg "=========================================="
+    msg "Encrypting filesystem..."
+    msg "This will take several minutes."
+    msg "DO NOT POWER OFF THE DEVICE!"
+    msg "=========================================="
+
+    echo -n "${LUKS_KEY}" | \
+        /usr/sbin/cryptsetup reencrypt --encrypt \
+        --type luks2 \
+        --cipher aes-xts-plain64 \
+        --key-size 256 \
+        --hash sha256 \
+        --reduce-device-size 32M \
+        --key-file - \
+        "${ROOT_DEV}" || {
+        msg "ERROR: Encryption failed"
+        rm -f "${ENCRYPTION_MARKER}"
+        return 1
+    }
+
+    msg "=========================================="
+    msg "Encryption completed successfully!"
+    msg "=========================================="
+
+    # Remove encryption marker
+    rm -f "${ENCRYPTION_MARKER}"
+    sync
+
+    # Unlock the newly encrypted device
+    msg "Activating encrypted filesystem..."
+    echo -n "${LUKS_KEY}" | \
+        /usr/sbin/cryptsetup luksOpen "${ROOT_DEV}" "${CRYPT_NAME}" --key-file - || {
+        msg "ERROR: Failed to activate encrypted filesystem"
+        return 1
+    }
+
+    # Resize filesystem to fit the encrypted device
+    msg "Optimizing filesystem..."
+    /usr/sbin/resize2fs -f "${CRYPT_DEV}" || {
+        msg "ERROR: Failed to optimize filesystem"
+        return 1
+    }
+
+    # Verify filesystem after resize
+    /usr/sbin/e2fsck -f -y "${CRYPT_DEV}" || {
+        info "WARNING: Filesystem verification had issues, but continuing"
+    }
+
+    return 0
+}
+
+# Unlock encrypted root filesystem (subsequent boots)
+unlock_encrypted_root() {
+    msg "Unlocking encrypted filesystem..."
+
+    # Unseal key from TPM persistent handle
+    LUKS_KEY=$(tpm_unseal_key)
+
+    if [ -z "${LUKS_KEY}" ]; then
+        msg "ERROR: Failed to retrieve encryption key from TPM"
+        msg "Attempting passphrase fallback..."
+
+        # Try to unlock with passphrase (interactive)
+        /usr/sbin/cryptsetup luksOpen "${ROOT_DEV}" "${CRYPT_NAME}" || {
+            fatal "ERROR: Failed to unlock encrypted filesystem"
+        }
+    else
+        # Unlock with unsealed key
+        echo -n "${LUKS_KEY}" | \
+            /usr/sbin/cryptsetup luksOpen "${ROOT_DEV}" "${CRYPT_NAME}" --key-file - || {
+            fatal "ERROR: Failed to unlock with TPM key"
+        }
+    fi
+
+    msg "Encrypted filesystem unlocked"
+}
+
+# Module enabled check
+luksftpm_enabled() {
+    # Always run this module - it handles both encrypted and unencrypted cases
+    return 0
+}
+
+# Module main function
+luksftpm_run() {
+    # Wait for storage device
+    if ! wait_for_device "${ROOT_DEV}" 10; then
+        info "Storage device not found, skipping encryption module"
+        return 0
+    fi
+
+    # Mount boot partition
+    msg "Mounting boot partition..."
+    mkdir -p "${BOOT_MNT}"
+    if ! mount "${BOOT_DEV}" "${BOOT_MNT}"; then
+        info "ERROR: Failed to mount boot partition, attempting standard boot..."
+        mkdir -p ${ROOTFS_DIR}
+        mount "${ROOT_DEV}" ${ROOTFS_DIR}
+        return 0
+    fi
+
+    # Initialize fTPM
+    TPM_AVAILABLE=0
+    if init_ftpm; then
+        TPM_AVAILABLE=1
+    fi
+
+    # Check filesystem encryption status
+    msg "Checking filesystem encryption status..."
+
+    MOUNT_DEV="${ROOT_DEV}"
+
+    if /usr/sbin/cryptsetup isLuks "${ROOT_DEV}"; then
+        msg "Filesystem is encrypted"
+        unlock_encrypted_root
+        MOUNT_DEV="${CRYPT_DEV}"
+    else
+        msg "Filesystem is not encrypted"
+
+        # Check if encryption is enabled and TPM is available
+        if [ $TPM_AVAILABLE -eq 1 ]; then
+            # Check for encryption marker (resume interrupted encryption)
+            if [ -f "${ENCRYPTION_MARKER}" ]; then
+                msg "Resuming interrupted encryption..."
+                if ! encrypt_root_filesystem; then
+                    msg "ERROR: Failed to resume encryption"
+                    msg "Booting without encryption..."
+                    MOUNT_DEV="${ROOT_DEV}"
+                else
+                    MOUNT_DEV="${CRYPT_DEV}"
+                fi
+            else
+                # First boot - perform encryption
+                if encrypt_root_filesystem; then
+                    MOUNT_DEV="${CRYPT_DEV}"
+                else
+                    msg "ERROR: Encryption failed - booting without encryption"
+                    MOUNT_DEV="${ROOT_DEV}"
+                fi
+            fi
+        else
+            msg "TPM not available - skipping encryption"
+            MOUNT_DEV="${ROOT_DEV}"
+        fi
+    fi
+
+    # Unmount boot partition before switching root
+    umount "${BOOT_MNT}"
+
+    # Mount root filesystem to $ROOTFS_DIR (framework expects this)
+    msg "Mounting root filesystem..."
+    mkdir -p ${ROOTFS_DIR}
+    mount "${MOUNT_DEV}" ${ROOTFS_DIR} || {
+        fatal "ERROR: Failed to mount root filesystem!"
+    }
+
+    # Clean up tmpfs and sensitive variables
+    rm -f "${TPM_PRIMARY_CTX}" "${TPM_KEY_PUB}" "${TPM_KEY_PRIV}" "${TPM_KEY_CTX}"
+    unset LUKS_KEY TPM_AVAILABLE MOUNT_DEV TEE_SUPPLICANT_PID
+
+    msg "Boot complete"
+}
diff --git a/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm_1.0.bb b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm_1.0.bb
new file mode 100644
index 00000000..b2a41d08
--- /dev/null
+++ b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/initramfs-module-luks-ftpm_1.0.bb
@@ -0,0 +1,43 @@
+SUMMARY = "initramfs support for LUKS encryption with fTPM"
+DESCRIPTION = "Provides LUKS2 full disk encryption using firmware TPM (fTPM) for key management on TI K3 platforms"
+
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
+
+# Only build for platforms with optee-ftpm support
+COMPATIBLE_MACHINE = "null"
+COMPATIBLE_MACHINE:k3 = "${@bb.utils.contains('MACHINE_FEATURES', 'optee-ftpm', '.*', 'null', d)}"
+
+FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:"
+
+SRC_URI = "file://luksftpm"
+
+S = "${UNPACKDIR}"
+
+do_install() {
+    install -d ${D}/init.d
+    # Install as 85-luksftpm (runs after udev at 01, before rootfs at 90)
+    install -m 0755 ${UNPACKDIR}/luksftpm ${D}/init.d/85-luksftpm
+}
+
+FILES:${PN} = "/init.d/85-luksftpm"
+
+# Runtime dependencies
+RDEPENDS:${PN} = "\
+    initramfs-framework-base \
+    busybox \
+    kmod \
+    cryptsetup \
+    tpm2-tools \
+    tpm2-tss \
+    libtss2-tcti-device \
+    optee-client \
+    optee-ftpm \
+    e2fsprogs-e2fsck \
+    e2fsprogs-resize2fs \
+    e2fsprogs-tune2fs \
+    util-linux-blkid \
+    kernel-module-tpm-ftpm-tee \
+"
+
+PACKAGE_ARCH = "${MACHINE_ARCH}"
diff --git a/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/packagegroup-ti-core-initramfs.bbappend b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/packagegroup-ti-core-initramfs.bbappend
new file mode 100644
index 00000000..52c82389
--- /dev/null
+++ b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/packagegroup-ti-core-initramfs.bbappend
@@ -0,0 +1,3 @@
+LUKS_ENCRYPTION ?= "${@bb.utils.contains('MACHINE_FEATURES', 'optee-ftpm', 'initramfs-module-luks-ftpm', '', d)}"
+
+RDEPENDS:${PN}:append = " ${@bb.utils.contains('DISTRO_FEATURES', 'luks', '${LUKS_ENCRYPTION}', '', d)}"
diff --git a/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/ti-core-initramfs.bbappend b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/ti-core-initramfs.bbappend
new file mode 100644
index 00000000..8901d0bf
--- /dev/null
+++ b/meta-ti-bsp/dynamic-layers/tpm-layer/recipes-ti/initramfs/ti-core-initramfs.bbappend
@@ -0,0 +1 @@
+INITRAMFS_MAXSIZE = "200000"