Bashhacker Part2: wipefree

Mögliche Gründe, warum das wiederherstellen von sensiblen Dateien vermeiden will gibt es viele. Thomas C. Greene hat für diese Aufgabe ein einfaches Script erstellt, welches ich ein wenig verändert habe. Das Skript überprüft, ob benötigte externe Programme bereits vorhanden sind. Es kann nun angewählt werden, wie oft das Dateisystem mit Nullen oder Datenmüll überschrieben wird. Du kannst das Volume angeben. Außerdem werden Durchlaufzeiten und Fortschritt des Skriptes gezählt und angezeigt.

Code:
#!/bin/bash

#wipefree

#Script that will wipe the free space of several partitions

##Comes with the package Bash-Tools
#Original Idea by Thomas C. Greene
#Ideas Collected by Mendel Cooper (Advanced Bash Scripting guide)
#rewritten for opensue 10.2 by Matthias Propst

#VARS
NOT_ROOT=67
NO_PART=82
NO_INT=24
NO_SYNC=34
#VARS

###functions begin here

#checks for root
check_root ()
{
echo "Checking whether you are root."

if [ $UID -ne 0 ]
then
echo "Only root can wipeout free space."
drop_failure
exit $NOT_ROOT
else
drop_ok
check_sync
fi
}

check_sync ()
{
VERSION=$(sync --version 2> /dev/null echo "-" )
if [[ $VERSION == "-" ]]
then
echo "sync does not seemed to be installed"
echo "Please install sync and rerun again. It is usaly in the package coreutils."
echo "Script exits now."
drop_failure
exit $NO_SYNC
else
echo "found $VERSION"
drop_ok
often
fi
}

often ()
{
##stes the counter. this is important and ensures the script to stop
unset COUNTER
read -p "How often to you need `basename $0` to run: " COUNTER
${COUNTER:="0"} 2> /dev/null
CHECK=$(( $COUNTER * 1 )) 2> /dev/null
#this prevents the user passing 0 or an non integer value
##sets the Counter. this important and ensures the script to stop


if [[ $CHECK != $COUNTER OR $COUNTER == "0" ]] #because Check will be the errormessage from a non integer value or counter is 0 this checks whether counter is an integer > 0
then
echo "$COUNTER is not an integer value."
drop_failure
exit $NO_INT
else
algorithm
fi
}

algorithm()
{
unset ALGO
unset ALGO_NAME
clear
#Users Choise of which algorithm (method) is used
echo "Algorithms:"
echo "(1) urandom: Uses the /dev/urnadom (default)"
echo "(2) zero: Uses /dev/zero to overwrite your free space (fast but unsecure)"
echo "(3) filesplitter: uses a mixture of both zero and urandom and split up the _cleanupfile_. (should be best result)"
read -n 1 -p "Which algorithm do you want to run. Press Enter to use default." ALGO
${ALGO:=1} 2> /dev/null

case $ALGO in
1) check_part
;;
2) check_part
;;
3) check_part
;;
*) algorithm #if any other keys is pressed the script asks again
;;
esac

}

check_part ()
{
clear
echo "We will wipe out free space in"

for f in $FS #the loop list all folders given and checks whether the folder belongs to a partition
do
unset PART
unset CRYPTO_PART

if [[ $f == "/dev/" OR ! ${f/#\/dev*} OR ! ${f/#\/proc*} $f == "swap" ]]
then
echo "Oops"
echo "$f: This is not allowed"
exit $NO_PART
fi

PART=$(echo `less /etc/fstab grep $f`)
CRYPTO_PART=$(echo `less /etc/cryptotab grep $f`)

${PART:="-"} 2> /dev/null
${CRYPTO_PART:="-"} 2> /dev/null

if [ "$PART" == "-" ] ##if the partition is not in /etc/fstab than probly in /etc/cryptotab
then
if [ "$CRYPTP_PART" == "-" ]
then
echo "$f is not a partition"
echo "Maybe this is not your fault. Because the Script does not handle /foobar/ if the folder /foobar has"
echo "its own partition. Try to rerun the script with /foobar instead of /foobar/." #a warning because i dont know how to prevent that. maybe someone else has an idea+++script exits at first found invalid partition this depends on the order of given scripts
drop_failure
exit $NO_PART
fi
else
echo $f
fi
done
drop_ok

echo "$COUNTER times"
echo "with the"
case $ALGO in #prints a summary
1) echo "urandom"
;;
2) echo "zero"
;;
3) echo "filesplitter"
;;
esac
echo "algorithm."
sleep 3

main
}

trapint ()
{
echo "dont press ctrl + c"
}

main ()
{
echo "Starting now."
echo "This may take a long time."
echo -e '\E[5;31mDo not interrupt or kill this script until it is finished'; tput sgr0
sleep 3

case $ALGO in
1)

until [ $COUNTER -eq 0 ]
do
((COUNTER -=1))
((COUNTER2 +=1))
echo "Starting pass $COUNTER2."
echo "Remaining $COUNTER passes."

for f in $FS
do
name="$f/_cleanupfile_"
echo "Creating $name"
set +e +u
trap trapint 2 SIGTSTP
dd if=/dev/urandom of="$f/_cleanupfile_"
sync; sync
rm "${f}/_cleanupfile_"
sync; sync
drop_ok
done

done
;;
2)
until [ $COUNTER -eq 0 ]
do
((COUNTER -=1))
((COUNTER2 +=1))
echo "Starting pass $COUNTER2"
echo "Remainig $COUNTER passes."

for f in $FS
do
name="$f/_cleanupfile_"
echo "Creating $name"
set +e +u
trap trapint 2 SIGTSTP
##creates the big cleanupfile
dd if=/dev/zero of="$f/_cleanupfile_"
sync; sync ##sync the cleanupfile
rm "${f}/_cleanupfile_"
sync; sync ##sync free space
drop_ok
done
done
;;
3)
until [ $COUNTER -eq 0 ]
do
((COUNTER -=1))
((COUNTER2 +=1))
echo "Starting pass $COUNTER2"
echo "Remainig $COUNTER passes."

for f in $FS
do
folder="$f/_clean_"

a=0
i=0
while [ $a -eq 0 ]
do
unset a
mkdir -p $folder
((i+=1))
unset RAND
RAND=$(($RANDOM %2 )) #generates random integer and checks whether this is odd or even by using the mathemtic modulo function

case $RAND in
0) #rand was even
name="$folder/_cleanupfile_$i"
echo "Creating $name"
set +e +u
trap trapint 2 SIGTSTP
dd count=250000 if=/dev/zero of="$name"
;;
1) #rand was odd
name="$folder/_cleanupfile_$i"
echo "Creating $name"
set +e +u
trap trapint 2 SIGTSTP
dd count=250000 if=/dev/urandom of="$name"
;;
esac
a=$?
done
sync; sync
rm -r "${f}/_clean_"
sync; sync
drop_ok

done
done
;;
esac

echo -e '\t \t \t \t \E[32mdone'; tput sgr0

exit 0
}

drop_ok ()
{
echo -e '\t \t \t \t \E[32mok'; tput sgr0
}

drop_failure ()
{
echo -e '\t \t \t \t \E[31mfailure'; tput sgr0
}

###functions end here

FS=$*
${FS:="/"} 2> /dev/null #if no argument is given, / is assumed
check_root

exit 0