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130 lines
4.9 KiB
Bash
Executable File
130 lines
4.9 KiB
Bash
Executable File
#!/bin/bash
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# Unseal a LUKS Disk Unlock Key from TPM and add to a new initramfs
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set -e -o pipefail
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. /etc/functions
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TRACE_FUNC
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TMP_KEY_DEVICES="/tmp/kexec/kexec_key_devices.txt"
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TMP_KEY_LVM="/tmp/kexec/kexec_key_lvm.txt"
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INITRD="$1"
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if [ -z "$INITRD" ]; then
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die "Usage: $0 /boot/initramfs... "
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fi
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if [ ! -r "$TMP_KEY_DEVICES" ]; then
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die "No devices defined for disk encryption"
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fi
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if [ -r "$TMP_KEY_LVM" ]; then
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# Activate the LVM volume group
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VOLUME_GROUP=$(cat $TMP_KEY_LVM)
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if [ -z "$TMP_KEY_LVM" ]; then
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die "No LVM volume group defined for activation"
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fi
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lvm vgchange -a y $VOLUME_GROUP ||
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die "$VOLUME_GROUP: unable to activate volume group"
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fi
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# Measure the LUKS headers before we unseal the LUKS Disk Unlock Key from TPM
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cat "$TMP_KEY_DEVICES" | cut -d\ -f1 | xargs /bin/qubes-measure-luks ||
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die "LUKS measure failed"
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# Unpack the initrd and fixup the crypttab
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# this is a hack to split it into two parts since
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# we know that the first 0x3400 bytes are the microcode
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INITRD_DIR=/tmp/secret/initrd
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SECRET_CPIO=/tmp/secret/initrd.cpio
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bootdir=$(dirname "$INITRD")
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mkdir -p "$INITRD_DIR/etc"
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if [ -e /boot/kexec_lukshdr_hash.txt ] && [ -e /tmp/luksDump.txt ]; then
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if ! cmp -s /boot/kexec_lukshdr_hash.txt /tmp/luksDump.txt >/dev/null 2>&1; then
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#LUKS header hash part of detached signed hash digest under boot doesn't match qubes-measure-luks tmp file
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warn "Encrypted disk keys have changed since the TPM Disk Unlock Key was sealed. If you did not make this change, the disk may be compromised"
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exit 1
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else
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#LUKS header hash part of detached signed hash digest matches
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echo "+++ Encrypted disk keys have not been changed since sealed in TPM Disk Unlock Key"
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#TODO: remove "+++" with boot info helper when added, same with "!!!" currently for info.
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fi
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else
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warn "Could not check for tampering of Encrypted disk keys"
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warn "Re-seal the TPM Disk Unlock Key by re-selecting your default boot option to enable this check (Options -> Boot Options -> Show OS boot menu)."
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fi
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# Attempt to unseal the Disk Unlock Key from the TPM
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# should we give this some number of tries?
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unseal_failed="n"
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if ! kexec-unseal-key "$INITRD_DIR/secret.key"; then
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unseal_failed="y"
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echo
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echo "!!! Failed to unseal the TPM LUKS Disk Unlock Key"
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fi
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# Override PCR 4 so that user can't read the key
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DEBUG "Extending TPM PCR 4 to prevent further secret unsealing"
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tpmr extend -ix 4 -ic generic ||
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die 'Unable to scramble PCR'
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# Check to continue
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if [ "$unseal_failed" = "y" ]; then
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confirm_boot="n"
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read \
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-n 1 \
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-p "Do you wish to boot and use the LUKS Disk Recovery Key? [Y/n] " \
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confirm_boot
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echo
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if [ "$confirm_boot" != 'y' \
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-a "$confirm_boot" != 'Y' \
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-a -n "$confirm_boot" ] \
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; then
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die "!!! Aborting boot due to failure to unseal TPM Disk Unlock Key"
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fi
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fi
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echo
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echo '+++ Building initrd'
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# pad the initramfs (dracut doesn't pad the last gz blob)
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# without this the kernel init/initramfs.c fails to read
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# the subsequent uncompressed/compressed cpio
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dd if="$INITRD" of="$SECRET_CPIO" bs=512 conv=sync ||
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die "Failed to copy initrd to /tmp"
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if [ "$unseal_failed" = "n" ]; then
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# kexec-save-default might have created crypttab overrides to be injected in initramfs through additional cpio
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if [ -r "$bootdir/kexec_initrd_crypttab_overrides.txt" ]; then
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echo "+++ $bootdir/kexec_initrd_crypttab_overrides.txt found..."
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echo "+++ Preparing initramfs crypttab overrides as defined under $bootdir/kexec_initrd_crypttab_overrides.txt to be injected through cpio at next kexec call..."
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# kexec-save-default has found crypttab files under initrd and saved them
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cat "$bootdir/kexec_initrd_crypttab_overrides.txt" | while read line; do
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crypttab_file=$(echo "$line" | awk -F ':' {'print $1'})
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crypttab_entry=$(echo "$line" | awk -F ':' {'print $NF'})
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# Replace each initrd crypttab file with modified entry containing /secret.key path
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mkdir -p "$INITRD_DIR/$(dirname $crypttab_file)"
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echo "$crypttab_entry" | tee -a "$INITRD_DIR/$crypttab_file" >/dev/null
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echo "+++ initramfs's $crypttab_file will be overriden with: $crypttab_entry"
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done
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else
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# No crypttab files were found under selected default boot option's initrd file
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# Meanwhile, force crypttab to be created from scratch on both possible locations: /etc/crypttab and /cryptroot/crypttab
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crypttab_files="etc/crypttab cryptroot/crypttab"
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for crypttab_file in $crypttab_files; do
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mkdir -p "$INITRD_DIR/$(dirname $crypttab_file)"
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# overwrite crypttab to mirror behavior of seal-key
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echo "+++ The following $crypttab_file overrides will be passed through concatenated secret/initrd.cpio at kexec call:"
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for uuid in $(cat "$TMP_KEY_DEVICES" | cut -d\ -f2); do
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# NOTE: discard operation (TRIM) is activated by default if no crypptab found in initrd
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echo "luks-$uuid UUID=$uuid /secret.key luks,discard" | tee -a "$INITRD_DIR/$crypttab_file"
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done
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done
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fi
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(
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cd "$INITRD_DIR"
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find . -type f | cpio -H newc -o
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) >>"$SECRET_CPIO"
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fi
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