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Mounting a TrueCrypt system dd image in Linux

The following is a tutorial on mounting a dd image of a TrueCrypt system-level-encrypted volume. This tutorial was tested and written against Ubuntu 16.04.2 LTS.


Trying to mount your loopback device with losetup or mount doesn’t quite work. If you tried, you’d get an error like the following:

No such file or directory:
/sys/block/loop2/loop2p2/start
VeraCrypt::File::Open:276


Instead, use sudo kpartx -va IMAGE_FILENAME. This will give you something like the following:

add map loop2p1 (253:0): 0 204800 linear 7:2 2048
add map loop2p2 (253:1): 0 976564224 linear 7:2 206848
This shows you the partitions in the image and which loopback devices they are mounted to. In my case, loop2 and loop2p2, which I will continue using for the rest of this tutorial.
So this mounts the following:
  • /dev/loop2: The primary loopback device
  • /dev/mapper/loop2p*: The partition loopback devices (in my case, loop2p1 and loop2p2)


If you attempt to mount loop2p2 with TrueCrypt or VeraCrypt as a system partition, no matter the password, you will get the error “Partition device required”.
To fix this we need to get the loop2p2 to show up in /dev and make an edit to the VeraCrypt source code.


You can run the following command to see the loopback partition devices and their sizes. This is where I am pulling loop2p2 from.

lsblk /dev/loop2
This will give the following:
NAME      MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop2       7:2    0 465.8G  1 loop 
├─loop2p2 253:1    0 465.7G  1 part 
└─loop2p1 253:0    0   100M  1 part 
	

Run the following command to create /dev/loop2p* block devices:

sudo partx -a /dev/loop2


Run the following commands to download and compile VeraCrypt:

sudo apt-get install git yasm libfuse-dev libwxgtk3.0-dev #yasm requires universe repository
git clone https://github.com/veracrypt/VeraCrypt
cd VeraCrypt/src
nano Platform/Unix/FilesystemPath.cpp #You can use the editor of your choice for this

In Platform/Unix/FilesystemPath.cpp make the following change:
After the following 2 lines of code in the FilesystemPath::ToHostDriveOfPartition() function, currently Line 78:
#ifdef TC_LINUX
        path = StringConverter::StripTrailingNumber (StringConverter::ToSingle (Path));
Add the following:
string pathStr = StringConverter::ToSingle (path);
size_t t = pathStr.find("loop");
if(t != string::npos)
    path = pathStr.substr (0, pathStr.size() - 1);
Then continue to run the following commands to finish up:
make
Main/veracrypt -m system,ro,nokernelcrypto -tc /dev/loop2p2 YOUR_MOUNT_LOCATION


VeraCrypt parameter information:

  • If you don’t include the “nokernelcrypto” option, you will get the following error:
    device-mapper: reload ioctl on veracrypt1 failed: Device or resource busy
    Command failed
    
  • the “ro” is if you want to mount in readonly
  • “-tc” means the volume was created in TrueCrypt (not VeraCrypt)

  • Doing this in Windows is a lot easier. You just need to use a program called Arsenal Image Mounter to mount the drive, and then mount the partition in TrueCrypt (or VeraCrypt).