The rumpkernel based tools are intended to be used by executing
'tool/rump'. Since it covers the most common use cases for these
tools, this script is comparatively extensive, hence giving a short
tutorial seems reasonable:
* Format a disk image with Ext2:
To format a disk image with the Ext2 file system, first prepare the
actual image by executing dd:
! dd if=/dev/zero of=/path/to/disk_image bs=1M count=128
Second, use 'tool/rump' to format the disk image:
! rump -f -F ext2fs /path/to/disk_image
Afterwards the just created file system may be populated with the
content of another directory by executing
! rump -F ext2fs -p /path/to/another_dir /path/to/disk_image
The content of the file system image can be listed by executing
! rump -F ext2fs -l /path/to/disk_image
* Create a encrypted disk image:
Creating a cryptographic disk image based on cgd(4) is done by
executing the following command:
! rump -c /path/to/disk_image
This will generate a key that may be used to decrypt the image
later on. Since this command will _only_ generate a key and NOT
initialize the disk image, it is highly advised to prepare the disk
image by using '/dev/urandom' instead of '/dev/zero' (only new blocks
that will be written to the disk image are encrypted). In addition
while generating the key a temporary configuration file will be
created. Although this file has proper permissions, it may leak the
generated key if it is created on persistent storage. To specify a more
secure directory the '-t' option should be used:
! rump -c -t /path/to/secure/directory /path/to/disk_image
Decrypting the disk image requires the key generated in the previous
step:
! rump -c -k <key> /path/to/disk_image
For now this key has to specified as command line argument. This is
an issue if the shell, which is used, is maintaing a history of
executed commands.
For completness sake let us put all examples together by creating a
encrypted Ext2 image that will contain all files of Genode's _demo_
scenario:
! dd if=/dev/urandom of=/tmp/demo.img bs=1M count=16
! $(GENODE_DIR)/tool/rump -c -t /ramfs -F ext2fs /tmp/demo.img > \
! /ramfs/key # key is printed out to stdout
! $(GENODE_DIR)/tool/rump -c -t /ramfs -F ext2fs -k <key> \
! -p $(BUILD_DIR)/var/run/demo /tmp/demo.img
To check if the image was populated succesfully, execute the
following:
! $(GENODE_DIR)/tool/rump -c -t /ramfs -F ext2fs -k <key> -l \
! /tmp/demo.img
Josef Söntgen