debug.sh

#!/bin/bash
trap "" 0 1 2 3 9 13 15

# User configuration
HOME_DIRECTORY="/home/rhydon"
BUILDROOT_IMAGES_PATH="$HOME_DIRECTORY/workspace/buildroot-2020.02.4/output/images"

VM_USERNAME="root"
VM_PASSWORD="123456"
KERNEL_MODULE_NAME="kernel_development"

CWD=`pwd`
REMOTE_DIR="/"`basename $CWD`
SSH_PORT=5555
SNAPSHOT_NAME="first_snapshot"
SNAPSHOT_CMDLINE_FILE="loadvm_cmdline"

cd $BUILDROOT_IMAGES_PATH

if pgrep "qemu" > /dev/null
then
    pkill -9 qemu
    while pgrep "qemu" > /dev/null; do
        sleep 0.1
    done
fi


if pgrep "gdb" > /dev/null
then
    pkill -9 gdb
    while pgrep "gdb" > /dev/null; do
        sleep 0.1
    done
fi

echo "loadvm $SNAPSHOT_NAME" > $SNAPSHOT_CMDLINE_FILE

echo "[+] running QEMU emulation"
setsid ./start-qemu.sh &

# Busy loop for waiting for the vm to startup and setup ssh
until sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT -o StrictHostKeyChecking=no $VM_USERNAME@localhost exit
do 
    echo "[+] waiting for the VM to initialize"
    sleep 1
done

echo "[+] VM: initialized"

echo "[+] reverting to snapshot: $SNAPSHOT_NAME"
socat OPEN:$SNAPSHOT_CMDLINE_FILE unix-connect:qemu-monitor-socket

echo "[+] moving kernel module $KERNEL_MODULE_NAME to the vm"
sshpass -p "$VM_PASSWORD" scp -P $SSH_PORT -r $CWD $VM_USERNAME@localhost:$REMOTE_DIR

echo "[+] loading $KERNEL_MODULE_NAME to the kernel"
sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost "insmod $REMOTE_DIR/$KERNEL_MODULE_NAME.ko"

echo "[+] retrieving $KERNEL_MODULE_NAME sections"
init_text_addr=`sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost cat /sys/module/$KERNEL_MODULE_NAME/sections/.init.text`
exit_text_addr=`sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost cat /sys/module/$KERNEL_MODULE_NAME/sections/.exit.text`

text_addr=`sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost cat /sys/module/$KERNEL_MODULE_NAME/sections/.text`
data_addr=`sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost cat /sys/module/$KERNEL_MODULE_NAME/sections/.data`
bss_addr=`sshpass -p "$VM_PASSWORD" ssh -p $SSH_PORT $VM_USERNAME@localhost cat /sys/module/$KERNEL_MODULE_NAME/sections/.bss`


GDBINIT_PATH=$BUILDROOT_IMAGES_PATH/.gdbinit

if [ -f $GDBINIT_PATH.bak ]; then
    echo "[+] using an existing .gdbinit file"
    cp $GDBINIT_PATH.bak $GDBINIT_PATH
else
    echo "[+] creating a new .gdbinit file"
    rm -f $GDBINIT_PATH
    touch $GDBINIT_PATH
fi

section_flags=""

if [ -z "$text_addr" ]; 
    then : # no text section
else
    section_flags+=" -s .text ${text_addr}"
fi

if [ -z "$data_addr" ]; 
    then : # no data section
else
    section_flags+=" -s .data ${data_addr}"
fi

if [ -z "$bss_addr" ];
    then : # no bss section 
else
    section_flags+=" -s .bss ${bss_addr}"
fi

echo "source ~/.gdbinit-gef.py" >> $GDBINIT_PATH
echo "set disassembly-flavor intel" >> $GDBINIT_PATH
echo "file /home/rhydon/workspace/buildroot-2020.02.4/output/build/linux-4.19.91/vmlinux" >> $GDBINIT_PATH
echo "add-symbol-file $CWD/$KERNEL_MODULE_NAME.ko -s .init.text $init_text_addr -s .exit.text $exit_text_addr ${section_flags}" >> $GDBINIT_PATH