Merge pull request #3249 from chriswue/master

Adding support to mount an encrypted filesystem
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Rolf Neugebauer 2019-01-18 01:28:50 +01:00 committed by GitHub
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# Device encryption with dm-crypt
In the packages section you can find an image to setup dm-crypt encrypted devices in [linuxkit](https://github.com/linuxkit/linuxkit)-generated images.
## Usage
The setup is a one time step during boot:
```yaml
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:<hash>
command: ["/usr/bin/crypto", "dm_crypt_name", "/dev/sda1"]
- name: mount
image: linuxkit/mount:<hash>
command: ["/usr/bin/mountie", "/dev/mapper/dm_crypt_name", "/var/secure_storage"]
files:
- path: etc/dm-crypt/key
contents: "abcdefghijklmnopqrstuvwxyz123456"
```
The above will map `/dev/sda1` as an encrypted device under `/dev/mapper/dm_crypt_name` and mount it under `/var/secure_storage`
The `dm-crypt` container by default bind-mounts `/dev:/dev` and `/etc/dm-crypt:/etc/dm-crypt`. It expects the encryption key to be present in the file `/etc/dm-crypt/key`. You can pass an alternative location as encryption key which can be either a file path relative to `/etc/dm-crypt` or an absolute path.
Providing an alternative encryption key file name:
```yaml
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:<hash>
command: ["/usr/bin/crypto", "-k", "some_other_key", "dm_crypt_name", "/dev/sda1"]
- name: mount
image: linuxkit/mount:<hash>
command: ["/usr/bin/mountie", "/dev/mapper/dm_crypt_name", "/var/secure_storage"]
files:
- path: etc/dm-crypt/some_other_key
contents: "abcdefghijklmnopqrstuvwxyz123456"
```
Providing an alternative encryption key file name as absolute path:
```yaml
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:<hash>
command: ["/usr/bin/crypto", "-k", "/some/other/key", "dm_crypt_name", "/dev/sda1"]
binds:
- /dev:/dev
- /etc/dm-crypt/some_other_key:/some/other/key
- name: mount
image: linuxkit/mount:<hash>
command: ["/usr/bin/mountie", "/dev/mapper/dm_crypt_name", "/var/secure_storage"]
files:
- path: etc/dm-crypt/some_other_key
contents: "abcdefghijklmnopqrstuvwxyz123456"
```
Note that you have to also map `/dev:/dev` explicitly if you override the default bind-mounts.
The `dm-crypt` container
* Will create an `ext4` file system on the encrypted device if none is present.
* It will also initialize the encrypted device by filling it from `/dev/zero` prior to creating the filesystem. Which means if the device is being setup for the first time it might take a bit longer.
* Uses the `aes-cbc-essiv:sha256` cipher (it's explicitly specified in case the default ever changes)
* Consequently the encryption key is expected to be 32 bytes long, a random one can be created via
```shell
dd if=/dev/urandom of=dm-crypt.key bs=32 count=1
```
If you see the error `Cannot read requested amount of data.` next to the log message `Creating dm-crypt mapping for ...` then this means your keyfile doesn't contain enough data.
### Examples
There are two examples in the `examples/` folder:
1. `dm-crypt.yml` - formats an external disk and mounts it encrypted.
2. `dm-crypt-loop.yml` - mounts an encrypted loop device backed by a regular file sitting on an external disk
### Options
|Option|Default|Required|Notes|
|---|---|---|---|
|`-k` or `--key`|`key`|No|Encryption key file name. Must be either relative to `/etc/dm-crypt` or an absolute file path.|
|`-l` or `--luks`||No|Use LUKS format for encryption|
|`<dm_name>`||**Yes**|The device-mapper device name to use. The device will be mapped under `/dev/mapper/<dm_name>`|
|`<device>`||**Yes**|Device to encrypt.|

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# LinuxKit losetup
Image to setup a loop device backed by a regular file in a [linuxkit](https://github.com/linuxkit/linuxkit)-generated image. The typical use case is to have a portable storage location which can be used to persist settings or other files. Can be combined with the `linuxkit/dm-crypt` package for protection.
## Usage
The setup is a one time step during boot:
```yaml
onboot:
- name: losetup
image: linuxkit/losetup:<hash>
command: ["/usr/bin/loopy", "-c", "/var/test.img"]
```
The above will associate the file `/var/test.img` with `/dev/loop0` and will also create it if it's not present.
The container by default bind-mounts `/var:/var` and `/dev:/dev`. Usually the loop-file will reside on external storage which should be typically mounted under `/var` hence the choice of the defaults. If the loop-file is located somewhere else and you need a different bind-mount for it then do not forget to explicitly bind-mount `/dev:/dev` as well or else `losetup` will fail.
### Options
|Option|Default|Required|Notes|
|---|---|---|---|
|`-c` or `--create`||No|Creates the file if not present. If `--create` is not specified and the file is missing then the loop setup will obviously fail.|
|`-s` or `--size`|10|No|If `--create` was specified and the file is not present then this sets the size in MiB of the created file. The file will be filled from `/dev/zero`.|
|`-d` or `--dev`|`/dev/loop0`|No|Loop device which should be associated with the file.|
|`<file>`||**Yes**|The file to use as backing storage.|

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=tty0 console=ttyS0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
- linuxkit/containerd:326b096cd5fbab0f864e52721d036cade67599d6
- linuxkit/ca-certificates:v0.6
onboot:
- name: sysctl
image: linuxkit/sysctl:v0.6
- name: dhcpcd
image: linuxkit/dhcpcd:v0.6
command: ["/sbin/dhcpcd", "--nobackground", "-f", "/dhcpcd.conf", "-1"]
- name: format
image: linuxkit/format:v0.6
command: ["/usr/bin/format", "/dev/sda"]
- name: mount
image: linuxkit/mount:v0.6
command: ["/usr/bin/mountie", "/dev/sda1", "/var/external"]
- name: loop
image: linuxkit/losetup:b05ffc8641cc955abe45f6730cbe6d723b63bd3f
command: ["/usr/bin/loopy", "--create", "/var/external/storage_file"]
- name: dm-crypt
image: linuxkit/dm-crypt:9e41a164358b0235f0c242219b1a424c6552d46c
command: ["/usr/bin/crypto", "crypt_loop_dev", "/dev/loop0"]
- name: mount
image: linuxkit/mount:v0.6
command: ["/usr/bin/mountie", "/dev/mapper/crypt_loop_dev", "/var/secure_storage"]
- name: bbox
image: busybox
command: ["sh", "-c", "echo 'secret things' >/var/secure_storage/secrets"]
binds:
- /var:/var
services:
- name: getty
image: linuxkit/getty:2eb742cd7a68e14cf50577c02f30147bc406e478
env:
- INSECURE=true
- name: rngd
image: linuxkit/rngd:v0.6
files:
- path: etc/dm-crypt/key
# the below key is just to keep the example self-contained
# !!! provide a proper key for production use here !!!
contents: "abcdefghijklmnopqrstuvwxyz123456"
trust:
org:
- linuxkit

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=tty0 console=ttyS0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
- linuxkit/containerd:326b096cd5fbab0f864e52721d036cade67599d6
- linuxkit/ca-certificates:v0.6
onboot:
- name: sysctl
image: linuxkit/sysctl:v0.6
- name: dhcpcd
image: linuxkit/dhcpcd:v0.6
command: ["/sbin/dhcpcd", "--nobackground", "-f", "/dhcpcd.conf", "-1"]
- name: format
image: linuxkit/format:v0.6
command: ["/usr/bin/format", "/dev/sda"]
- name: dm-crypt
image: linuxkit/dm-crypt:9e41a164358b0235f0c242219b1a424c6552d46c
command: ["/usr/bin/crypto", "crypt_dev", "/dev/sda1"]
- name: mount
image: linuxkit/mount:v0.6
command: ["/usr/bin/mountie", "/dev/mapper/crypt_dev", "/var/secure_storage"]
- name: bbox
image: busybox
command: ["sh", "-c", "echo 'secret things' >/var/secure_storage/secrets"]
binds:
- /var:/var
services:
- name: getty
image: linuxkit/getty:2eb742cd7a68e14cf50577c02f30147bc406e478
env:
- INSECURE=true
- name: rngd
image: linuxkit/rngd:v0.6
files:
- path: etc/dm-crypt/key
# the below key is just to keep the example self-contained
# !!! provide a proper key for production use here !!!
contents: "abcdefghijklmnopqrstuvwxyz123456"
trust:
org:
- linuxkit

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FROM linuxkit/alpine:3683c9a66cd4da40bd7d6c7da599b2dcd738b559 AS mirror
RUN mkdir -p /out/etc/apk && cp -r /etc/apk/* /out/etc/apk/
RUN apk add --no-cache --initdb -p /out \
alpine-baselayout \
cryptsetup \
e2fsprogs
# Remove apk residuals
RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
FROM scratch
ENTRYPOINT []
WORKDIR /
COPY --from=mirror /out/ /
COPY crypto.sh /usr/bin/crypto
RUN chmod +x /usr/bin/crypto
CMD ["/usr/bin/crypto"]

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image: dm-crypt
config:
binds:
- /dev:/dev
- /etc/dm-crypt:/etc/dm-crypt
capabilities:
- CAP_SYS_ADMIN
- CAP_MKNOD

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#!/bin/sh
set -e
help()
{
echo "Usage: $0 [options] <dm_name> <device>"
echo
echo "Options:"
echo " -l|--luks Use LUKS extension"
echo " -k|--key-file Name of the key file, default: key"
echo " <dm_name> Name of the device mapper file, the encrypted device will become available under /dev/mapper/<dm_name>"
echo " <device> The encrypted device (e.g. /dev/sda1, /dev/loop0, etc)"
echo
}
luks=false
key_file="key"
O=`getopt -l key-file:luks,help -- k:lh "$@"` || exit 1
eval set -- "$O"
while true; do
case "$1" in
-l|--luks) luks=true; shift;;
-k|--key-file) key_file=$2; shift 2;;
-h|--help) help; exit 0;;
--) shift; break;;
*) echo "Unknown option $1"; help; exit 1;;
esac
done
if [ -z "$1" ]; then
echo "Missing argument <dm_name>"
help
exit 1
fi
if [ -z "$2" ]; then
echo "Missing argument <device>"
help
exit 1
fi
dm_name=$1
device=$2
dmdev_name="/dev/mapper/$dm_name"
cipher="aes-cbc-essiv:sha256"
case "$key_file" in
/*) ;;
*) key_file="/etc/dm-crypt/$key_file" ;;
esac
if [ ! -f "$key_file" ]; then
echo "Couldn't find encryption keyfile $key_file!"
exit 1
fi
if [ ! -d "/run/cryptsetup" ]; then
echo "Creating cryptsetup lock directory"
mkdir /run/cryptsetup
fi
if [ $luks = true ]; then
echo "Creating dm-crypt LUKS mapping for $device under $dmdev_name"
if ! cryptsetup isLuks $device; then
echo "Device $device doesn't seem to have a valid LUKS setup so one will be created."
cryptsetup --key-file "$key_file" --cipher "$cipher" luksFormat "$device"
fi
cryptsetup --key-file "$key_file" luksOpen "$device" "$dm_name"
else
echo "Creating dm-crypt mapping for $device under $dmdev_name"
cryptsetup --key-file "$key_file" --cipher "$cipher" create "$dm_name" "$device"
fi
o=`blkid $dmdev_name`
if [ -z "$o" ]; then
echo "Device $dmdev_name doesn't seem to contain a filesystem, creating one."
# dd will write the device until it's full and then return with an error because "no space left"
dd if=/dev/zero of="$dmdev_name" || true
mkfs.ext4 "$dmdev_name"
else
echo "Device $dmdev_name seems to contain filesystem: $o"
fi

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FROM linuxkit/alpine:3683c9a66cd4da40bd7d6c7da599b2dcd738b559 AS mirror
RUN mkdir -p /out/etc/apk && cp -r /etc/apk/* /out/etc/apk/
RUN apk add --no-cache --initdb -p /out \
alpine-baselayout \
busybox
# Remove apk residuals
RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
FROM scratch
ENTRYPOINT []
WORKDIR /
COPY --from=mirror /out/ /
COPY loopy.sh /usr/bin/loopy
RUN chmod +x /usr/bin/loopy
CMD ["/usr/bin/loopy"]

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image: losetup
config:
binds:
- /dev:/dev
- /var:/var
capabilities:
- CAP_SYS_ADMIN

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#!/bin/sh
set -e
help()
{
echo "Usage: $0 [options] <file>"
echo
echo "Options:"
echo " -c, --create Create <file> if not present, default: false"
echo " -s, --size NUM Size of <file> in MiB if it gets created, default: 10"
echo " -d, --dev DEVICE Use DEVICE as loop device, default: /dev/loop0"
echo
}
create=false
size_mib=10
loop_device="/dev/loop0"
O=`getopt -l create,size:,dev:,help -- cs:d:h "$@"` || exit 1
eval set -- "$O"
while true; do
case "$1" in
-c|--create) create=true; shift;;
-s|--size) size_mib=$2; shift 2;;
-d|--dev) loop_device=$2; shift 2;;
-h|--help) help; exit 0;;
--) shift; break;;
*) echo "Unknown option $1"; help; exit 1;;
esac
done
if [ -z "$1" ]; then
echo "Missing argument <file>"
help
exit 1
fi
container_file=$1
if [ ! -b "$loop_device" ]; then
echo "Loop device $loop_device doesn't exist! Did you forget to bind-mount '/dev'?"
exit 2
fi
if [ ! -f "$container_file" ]; then
if [ $create = true ]; then
echo "File $container_file not found, creating new one of size $size_mib MiB"
dd if="/dev/zero" of="$container_file" bs=1M count=$size_mib
else
echo "File $container_file not found. Please specify --create or ensure it's present."
exit 2
fi
fi
echo "Associating file $container_file with loop device $loop_device"
losetup "$loop_device" "$container_file"

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#!/bin/sh
function failed {
printf "dm-crypt test suite FAILED\n" >&1
exit 1
}
[ -b /dev/mapper/it_is_encrypted ] || failed
printf "dm-crypt test suite PASSED\n" >&1

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#!/bin/sh
# SUMMARY: Check that the losetup package works
# LABELS:
# REPEAT:
set -e
# Source libraries. Uncomment if needed/defined
#. "${RT_LIB}"
. "${RT_PROJECT_ROOT}/_lib/lib.sh"
NAME=dm-crypt
DISK=disk.img
clean_up() {
rm -rf ${NAME}-* ${DISK}
}
trap clean_up EXIT
# Test code goes here
linuxkit build -format kernel+initrd -name ${NAME} test.yml
RESULT="$(linuxkit run -disk file=${DISK},size=32M ${NAME})"
echo "${RESULT}"
echo "${RESULT}" | grep -q "suite PASSED"
exit 0

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=ttyS0 console=ttyAMA0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:9e41a164358b0235f0c242219b1a424c6552d46c
command: ["/usr/bin/crypto", "it_is_encrypted", "/dev/sda"]
- name: test
image: alpine:3.8
net: host
binds:
- /check.sh:/check.sh
- /dev:/dev
command: ["sh", "./check.sh"]
- name: poweroff
image: linuxkit/poweroff:afe8f7dd0d47a7991c54519b0f09124cb8c4e300
command: ["/bin/sh", "/poweroff.sh", "10"]
files:
- path: check.sh
source: ./check.sh
- path: etc/dm-crypt/key
contents: "abcdefghijklmnopqrstuvwxyz123456"
trust:
org:
- linuxkit
image:
- alpine:3.8

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#!/bin/sh
function failed {
printf "dm-crypt test suite FAILED\n" >&1
exit 1
}
[ -b /dev/mapper/it_is_encrypted ] || failed
printf "dm-crypt test suite PASSED\n" >&1

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#!/bin/sh
# SUMMARY: Check that the losetup package works
# LABELS:
# REPEAT:
set -e
# Source libraries. Uncomment if needed/defined
#. "${RT_LIB}"
. "${RT_PROJECT_ROOT}/_lib/lib.sh"
NAME=dm-crypt
DISK=disk.img
clean_up() {
rm -rf ${NAME}-* ${DISK}
}
trap clean_up EXIT
# Test code goes here
linuxkit build -format kernel+initrd -name ${NAME} test.yml
RESULT="$(linuxkit run -disk file=${DISK},size=8M ${NAME})"
echo "${RESULT}"
echo "${RESULT}" | grep -q "suite PASSED"
exit 0

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=ttyS0 console=ttyAMA0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:9e41a164358b0235f0c242219b1a424c6552d46c
command: ["/usr/bin/crypto", "-l", "it_is_encrypted", "/dev/sda"]
- name: test
image: alpine:3.8
net: host
binds:
- /check.sh:/check.sh
- /dev:/dev
command: ["sh", "./check.sh"]
- name: poweroff
image: linuxkit/poweroff:afe8f7dd0d47a7991c54519b0f09124cb8c4e300
command: ["/bin/sh", "/poweroff.sh", "10"]
files:
- path: check.sh
source: ./check.sh
- path: etc/dm-crypt/key
contents: "abcdefghijklmnopqrstuvwxyz123456"
trust:
org:
- linuxkit
image:
- alpine:3.8

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#!/bin/sh
function failed {
printf "dm-crypt test suite FAILED\n" >&1
exit 1
}
[ -b /dev/mapper/it_is_encrypted ] || failed
printf "dm-crypt test suite PASSED\n" >&1

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#!/bin/sh
# SUMMARY: Check that the losetup package works
# LABELS:
# REPEAT:
set -e
# Source libraries. Uncomment if needed/defined
#. "${RT_LIB}"
. "${RT_PROJECT_ROOT}/_lib/lib.sh"
NAME=dm-crypt
DISK=disk.img
clean_up() {
rm -rf ${NAME}-* ${DISK}
}
trap clean_up EXIT
# Test code goes here
linuxkit build -format kernel+initrd -name ${NAME} test.yml
RESULT="$(linuxkit run -disk file=${DISK},size=32M ${NAME})"
echo "${RESULT}"
echo "${RESULT}" | grep -q "suite PASSED"
exit 0

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=ttyS0 console=ttyAMA0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
onboot:
- name: dm-crypt
image: linuxkit/dm-crypt:9e41a164358b0235f0c242219b1a424c6552d46c
command: ["/usr/bin/crypto", "-k", "/some/other/enc_key", "it_is_encrypted", "/dev/sda"]
binds:
- /dev/:/dev
- /some/other/enc_key:/some/other/enc_key
- name: test
image: alpine:3.8
net: host
binds:
- /check.sh:/check.sh
- /dev:/dev
command: ["sh", "./check.sh"]
- name: poweroff
image: linuxkit/poweroff:afe8f7dd0d47a7991c54519b0f09124cb8c4e300
command: ["/bin/sh", "/poweroff.sh", "10"]
files:
- path: check.sh
source: ./check.sh
- path: some/other/enc_key
contents: "abcdefghijklmnopqrstuvwxyz123456"
trust:
org:
- linuxkit
image:
- alpine:3.8

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#!/bin/sh
function failed {
printf "losetup test suite FAILED\n" >&1
exit 1
}
LOOPFILE=$(losetup /dev/loop0 2>/dev/null | cut -d' ' -f3)
[ "$LOOPFILE" = "/var/test.img" ] || failed
printf "losetup test suite PASSED\n" >&1

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#!/bin/sh
# SUMMARY: Check that the losetup package works
# LABELS:
# REPEAT:
set -e
# Source libraries. Uncomment if needed/defined
#. "${RT_LIB}"
. "${RT_PROJECT_ROOT}/_lib/lib.sh"
NAME=losetup
clean_up() {
rm -rf ${NAME}-*
}
trap clean_up EXIT
# Test code goes here
linuxkit build -format kernel+initrd -name "${NAME}" test.yml
RESULT="$(linuxkit run $NAME)"
echo "${RESULT}"
echo "${RESULT}" | grep -q "suite PASSED"
exit 0

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kernel:
image: linuxkit/kernel:4.14.88
cmdline: "console=ttyS0 console=ttyAMA0"
init:
- linuxkit/init:c563953a2277eb73a89d89f70e4b6dcdcfebc2d1
- linuxkit/runc:83d0edb4552b1a5df1f0976f05f442829eac38fe
onboot:
- name: losetup
image: linuxkit/losetup:b05ffc8641cc955abe45f6730cbe6d723b63bd3f
command: ["/usr/bin/loopy", "-c", "/var/test.img"]
- name: test
image: alpine:3.8
net: host
binds:
- /check.sh:/check.sh
- /dev:/dev
command: ["sh", "./check.sh"]
- name: poweroff
image: linuxkit/poweroff:afe8f7dd0d47a7991c54519b0f09124cb8c4e300
command: ["/bin/sh", "/poweroff.sh", "10"]
files:
- path: check.sh
source: ./check.sh
trust:
org:
- linuxkit
image:
- alpine:3.8