hashboot/hashboot.sh

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#!/bin/sh
#Hashes all files in /boot to check them during early boot
#Exit codes: 0 = success, 1 = checksum mbr mismatch, 2 = checksum /boot mismatch,
#3 = checksum mbr/boot mismatch, 4 = not root, 5 = no hasher found, 6 = wrong usage,
#7 = write error, 8 = dd error
VERSION="0.7.1"
PATH="/bin:/usr/bin:/sbin:/usr/sbin"
DIGEST_FILE="/var/lib/hashboot.digest"
LOG_FILE="/tmp/hashboot.log"
MBR_DEVICE="/dev/sda"
MBR_TMP="/tmp/mbr"
BACKUP_FILE="/var/cache/boot-backup.tar.gz"
HASHER=""
BOOT_MOUNTED=0
#Umount /boot if we mounted it, exit with given exit code
function die
{
if [ ${BOOT_MOUNTED} -gt 0 ]
then
umount /boot
fi
exit ${1}
}
#If we're not root: exit
if [ ${UID} -ne 0 ]
then
echo "You have to be root" >&2
die 4
fi
#Try different hashers, use the most secure
HASHER=$(/usr/bin/which --skip-dot sha512sum 2> /dev/null)
test -z ${HASHER} && HASHER=$(/usr/bin/which --skip-dot sha384sum 2> /dev/null)
test -z ${HASHER} && HASHER=$(/usr/bin/which --skip-dot sha256sum 2> /dev/null)
test -z ${HASHER} && HASHER=$(/usr/bin/which --skip-dot sha224sum 2> /dev/null)
#It gets insecure below here, but better than nothing?
test -z ${HASHER} && HASHER=$(/usr/bin/which --skip-dot sha1sum 2> /dev/null)
test -z ${HASHER} && HASHER=$(/usr/bin/which --skip-dot md5sum 2> /dev/null)
#If we found no hasher: exit
if [ -z ${HASHER} ]
then
echo "No hash calculator found" >&2
die 5
fi
#If /boot is in fstab but not mounted: mount, mark as mounted
if grep -q '/boot.*noauto' /etc/fstab && ! grep -q /boot /etc/mtab
then
mount /boot
BOOT_MOUNTED=1
fi
if [ "${1}" == "index" ]
then
#Write header
echo "#hashboot ${VERSION} - Algorithm: $(basename ${HASHER})" > ${DIGEST_FILE}
#Write MBR of MBR_DEVICE to ${DIGEST_FILE}
dd if=${MBR_DEVICE} of=${MBR_TMP} bs=1M count=1 status=noxfer || die 8
#Write hashes of all regular files to ${DIGEST_FILE}
${HASHER} ${MBR_TMP} > ${DIGEST_FILE}
find /boot -type f -exec ${HASHER} --binary {} >> ${DIGEST_FILE} +
if [ $? == 0 ]
then
echo "List of hashes written to ${DIGEST_FILE}"
else
echo "Error writing ${DIGEST_FILE}" >&2
die 7
fi
#Backup of good files
tar -czpPf ${BACKUP_FILE} ${MBR_TMP} /boot ${DIGEST_FILE}
if [ $? == 0 ]
then
echo "Backup written to ${BACKUP_FILE}"
else
echo "Error writing ${BACKUP_FILE}" >&2
die 7
fi
elif [ "${1}" == "check" ]
then
COUNTER=0
dd if=${MBR_DEVICE} of=${MBR_TMP} bs=1M count=1 status=noxfer || die 8
if $(grep ${MBR_TMP} ${DIGEST_FILE} | ${HASHER} --check --warn --quiet --strict > ${LOG_FILE})
then
echo "MBR ok"
else
echo " !! TIME TO PANIK: MBR WAS MODIFIED !!"
COUNTER=$((COUNTER + 1))
fi
if $(grep -v ${MBR_TMP} ${DIGEST_FILE} | ${HASHER} --check --warn --quiet --strict >> ${LOG_FILE})
then
echo "/boot ok"
else
echo " !! TIME TO PANIK: AT LEAST 1 FILE WAS MODIFIED !!"
COUNTER=$((COUNTER + 2))
die $COUNTER
fi
elif [ "${1}" == "recover" ]
then
echo "Restoring files from backup... (type yes or no for each file)"
#For each failed file: ask if it should be recovered from backup
for file in $(cut -d: -f1 ${LOG_FILE})
do
tar -xzpPvwf ${BACKUP_FILE} ${file}
[ $? != 0 ] && echo "Error restoring ${file} from backup, continuing" >&2
#If the MBR is to be recovered, copy to ${MBR_DEVICE}
if [ "${file}" == ${MBR_TMP} ]
then
cp ${MBR_TMP} ${MBR_DEVICE}
[ $? != 0 ] && echo "Error restoring MBR from backup, continuing" >&2
fi
done
else
echo "Usage: ${0} index|check|recover" >&2
die 6
fi
die 0