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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
114 lines
2.0 KiB
Bash
Executable File
114 lines
2.0 KiB
Bash
Executable File
#!/bin/sh
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#
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# \brief Create cgdconfig(8) configuration file from key or extract the key
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# from the specified configuration file
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# \author Josef Soentgen
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# \date 2014-04-29
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#
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#
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# Note: This script is merely just a awk(1) wrapper and only generates a
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# aes-cbc 256 storedkey configuration and expects the given key to
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# be a proper base64 encoded key generated by cgdconfig(8).
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#
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#
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# Print usage
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#
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print_usage() {
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local help=$1
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printf "usage: $PROG_NAME [-h] <-f file|-k key>\n"
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if [ "$help" != "" ]; then
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printf "\t-h show this help screen\n"
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printf "\t-k key generate config file from key and print "
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printf "to stdout\n"
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printf "\t-f file extract key from config file and print "
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printf "to stdout\n"
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fi
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}
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#
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# Parse arguments given on the commandline
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#
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parse_arguments() {
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local args="$(getopt hf:k: ${*})"
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[ $? != 0 ] && exit 1
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if [ $# -lt 1 ]
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then
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print_usage
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exit 1
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fi
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set -- $args
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while [ $# -ge 0 ]; do
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case "$1" in
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-h)
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print_usage "help"
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exit 0;;
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-k) ARG_KEY="$2"; shift; shift;;
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-f) ARG_FILE="$2"; shift; shift;;
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--) shift; break;;
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esac
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done
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}
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#
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# Extract the key string from the configuration file
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#
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extract_key() {
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local cgd_file="$1"
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awk 'BEGIN { found=0 }
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{
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if (found == 1) key=key $1
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if ($1 == "keygen") { found=1; key=$4 }
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}
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END { sub(/;$/, "", key); print key }' $cgd_file
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}
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#
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# Generate a proper cgd(8) configuration file from the given key
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#
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generate_conf() {
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local key="$1"
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printf "$key" | awk '{ key=$0 }
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END {
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printf("algorithm aes-cbc;\n")
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printf("iv-method encblkno1;\n")
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printf("keylength 256;\n")
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printf("verify_method none;\n")
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printf("keygen storedkey key ")
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printf("%s \\\n", substr(key, 1, 30))
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printf(" %s;\n", substr(key, 31))
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}'
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}
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main() {
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parse_arguments "$@"
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if [ "$ARG_FILE" != "" ]; then
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extract_key "$ARG_FILE"
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fi
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if [ "$ARG_KEY" != "" ]; then
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generate_conf "$ARG_KEY"
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fi
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}
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PROG_NAME=$(basename $0)
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ARG_FILE=
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ARG_KEY=
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main "$@"
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exit 0
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# End of file
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