#!/bin/bash
#
# Find linux installs and reset passwords
# (c) 2008 Dennis Kaarsemaker
#
# Instructions:
# To recover/reset passwords of an installed linux system, it's easiest to boot
# from a live CD and run this script. To do so, follow this list:
# - Boot from live cd
# - Download this file to the desktop
# - Run this command: bash ~/Desktop/reset_passwords
# - Follow the instructions presented by the script
#
# For each user account it finds, it will prompt you to ask whether you want to
# change the password.

# Bugs:
#  - Doesn't work if /usr is on a separate filesystem
#  - Doesn't work for non-lsb distros

# Warning, disclaimer
if [ "$1" != "--nowarn" ]; then
    echo -e "\033[1;31mThis tool will let you reset the passwords of any accounts\033[0m"
    echo -e "\033[1;31mit finds on installed linux systems. Use with care!\033[0m"
    echo -n "Press enter to continue, or CTRL-C to abort "
    read discard
fi

if [ $UID -ne 0 ]; then
    echo -e "\033[0;37mYou are $USER, not root. Attempting to run sudo\033[0m"
    exec sudo bash "$0" --nowarn
fi

# Warn if things are mounted on /mnt
mount | grep -q '/mnt' && {
    echo "A partition has been mounted under /mnt, aborting"
    echo "To unmount these partitions, run the following commands:"
    awk '/mnt/{ print "sudo umount " $2}' < /proc/mounts
    exit;
}

# Find partitions
partitions=$(fdisk -l | sed -n -e 's@^\(/dev/[[:alnum:]]\+\).*@\1@p')

# Iterate over partitions
for part in $partitions; do
    echo -e "\033[0;37mTrying partition $part\033[0m"

    # Mount
    mount $part /mnt >/dev/null 2>&1 || {
        echo -e "\033[0;37mCouldn't mount $part\033[0m"
        continue
    }

    # Detect linux
    if [ ! -e /mnt/etc/shadow ] || [ ! -e /mnt/usr/bin/lsb_release ]; then
        echo "$part doesn't seem to be a linux rootpartition"
        umount /mnt
        continue
    fi
    echo -e "\033[4;30mFound the following distribution on $part\033[0m:"
    chroot /mnt /usr/bin/lsb_release -i -r -c -d
    echo -ne "\033[4;30mReset passwords in this system\033[0m? [y/n] "
    read cont
    case $cont in
        [yY])
            ;;
        *)
            echo -e "\033[0;37mSkipping $part\033[0m"
            umount /mnt
            continue
    esac

    # Detect users with usable passwords
    users=$(chroot /mnt /usr/bin/passwd -S -a | sed -n -e 's/\([^[:space:]]\+\) P.*/\1/p')

    # Iterate over them
    for user in $users; do
        echo -ne "Reset the password for \033[4;30m$user\033[0m? [y/n] "
        read input
        case $input in
            [yY])
                chroot /mnt /usr/bin/passwd $user
                ;;
        esac
    done

    umount /mnt
done