[OpenWrt-Devel] [PATCH v2 00/12] dm-verity support
Thomas Petazzoni
thomas.petazzoni at bootlin.com
Thu Nov 21 11:23:10 EST 2019
Hello,
This is the second iteration of my patch series adding support for
dm-verity in OpenWRT. See below for some introduction about the
purpose of this series.
Changes since v1
================
- Rebase the patch series on the latest master.
- Make sure all patches have @bootlin.com as author, and not some
stale @free-electrons.com
- Switch to using the upstream kernel patches to set up a DM target at
boot time using the kernel command line, rather than patches that
were submitted years ago and not merged.
- Make sure kernel patches are provided for both 4.14 and 4.19
- Drop the SOURCE_DATE_EPOCH usage when creating the mksquashfs image.
- Format the cryptsetup patch properly.
- Only build the host tools if CONFIG_TARGET_ROOTFS_SQUASHFS_HASHED is
enabled
- Instead of unconditionally enabling the necessary kernel options for
dm-verity support, we now add the appropriate options to
config/Config-kernel.in, and select them only when needed.
- Drop empty Host/Configure rule in tools/libaio/Makefile
Introduction
============
dm-verity is a Linux kernel Device Mapper target that verifies that
the data in a block device has not been tampered with, by checking it
at runtime against a hash tree, itself verified by a root hash, which
is passed from a trusted source. dm-verity only supports read
operations, so we only support the read-only squashfs root filesystem
in this series.
This "hash tree" is a bunch of metadata that needs to be stored on
non-volatile storage. It can be appended to the filesystem data, or
stored on a separate block device/partition. We have chosen to support
only the case where it is appended to the filesystem data.
In the proposed series:
- Patches 1-5 introduce new host packages. The first four are simply
dependencies needed for cryptsetup, which is the tool used to
generate the hash tree at build time.
- Patch 6 extends the mkits.sh script so that a U-Boot script can be
embedded in a FIT image. Indeed, to set up a dm-verity device at
boot time, you need to pass a lot of details to the kernel that
describe the dm-verity device, including the root hash. Those
details need to be trusted: having them as part of the FIT image
allows to leverage the signing capabilities of FIT images.
- Patch 7 extends config/Config-kernel.in to be able to enable the
appropriate kernel options for dm-verity support.
- Patch 8 allows to create a FIT image with an embedded U-Boot
script, leveraging the feature added in patch 6.
- Patch 9 adds the code itself that generates the dm-verity capable
squashfs image, and a script that produces the U-Boot script with
the various parameters needed to setup the DM device at boot time.
- Patch 10 adds two kernel patches that allow setting up a DM device
at boot time, which have been backported from the upstream kernel,
while patch 10 updates the kernel configuration to enable the
appropriate option for dm-verity.
- Patches 11 and 12 are just related to enabling this mechanism on
Armada XP GP, which is the platform I used to work on this topic.
This work was tested on Armada XP GP, with both MMC and NAND storage.
One aspect that is not solved by this patch series is the logic in the
fstools programs to set up the overlay at boot time. Indeed, when
there is a squashfs filesystem, fstools assumes that it can use the
space after the squashfs filesystem for its overlay (in the MMC
storage case). It is not the case with dm-verity, because we have the
hash tree after the squashfs filesystem. This is something I intend to
work on.
Thomas Petazzoni
Thomas Petazzoni (12):
tools/libaio: new package
tools/lvm2: new package
tools/popt: new package
tools/libjson-c: new package
tools/cryptsetup: new package
scripts/mkits.sh: extend with -s option to include a U-Boot script
config/Config-kernel.in: add options to enable dm-verity related
kernel features
include/image-commands.mk: extend Build/fit for U-Boot script
integration
include/image.mk: add support for building a dm-verity enabled
squashfs image
target/linux/generic: backport patches adding DM_INIT functionality
target/linux/mvebu: enable UBI factory image on Armada XP GP
target/linux/mvebu: generate a FIT image on Armada XP GP with
dm-verity
config/Config-images.in | 8 +
config/Config-kernel.in | 15 +
include/image-commands.mk | 1 +
include/image.mk | 17 +-
scripts/mkits.sh | 22 +-
scripts/prepare-dm-verity-uboot-script.sh | 41 ++
...-to-directly-boot-to-a-mapped-device.patch | 668 ++++++++++++++++++
...-init-fix-max-devices-targets-checks.patch | 48 ++
...hang-in-early-create-error-condition.patch | 49 ++
...ion-dm-init-fix-multi-device-example.patch | 45 ++
...-to-directly-boot-to-a-mapped-device.patch | 668 ++++++++++++++++++
...-init-fix-max-devices-targets-checks.patch | 48 ++
...hang-in-early-create-error-condition.patch | 49 ++
...ion-dm-init-fix-multi-device-example.patch | 45 ++
target/linux/mvebu/image/cortex-a9.mk | 15 +
tools/Makefile | 3 +
tools/cryptsetup/Makefile | 28 +
.../patches/0001-dont-use-c89.patch | 11 +
tools/libaio/Makefile | 30 +
tools/libjson-c/Makefile | 25 +
tools/lvm2/Makefile | 47 ++
tools/popt/Makefile | 22 +
22 files changed, 1900 insertions(+), 5 deletions(-)
create mode 100755 scripts/prepare-dm-verity-uboot-script.sh
create mode 100644 target/linux/generic/backport-4.14/390-dm-add-support-to-directly-boot-to-a-mapped-device.patch
create mode 100644 target/linux/generic/backport-4.14/391-dm-init-fix-max-devices-targets-checks.patch
create mode 100644 target/linux/generic/backport-4.14/392-dm-ioctl-fix-hang-in-early-create-error-condition.patch
create mode 100644 target/linux/generic/backport-4.14/393-Documentation-dm-init-fix-multi-device-example.patch
create mode 100644 target/linux/generic/backport-4.19/400-dm-add-support-to-directly-boot-to-a-mapped-device.patch
create mode 100644 target/linux/generic/backport-4.19/401-dm-init-fix-max-devices-targets-checks.patch
create mode 100644 target/linux/generic/backport-4.19/402-dm-ioctl-fix-hang-in-early-create-error-condition.patch
create mode 100644 target/linux/generic/backport-4.19/403-Documentation-dm-init-fix-multi-device-example.patch
create mode 100644 tools/cryptsetup/Makefile
create mode 100644 tools/cryptsetup/patches/0001-dont-use-c89.patch
create mode 100644 tools/libaio/Makefile
create mode 100644 tools/libjson-c/Makefile
create mode 100644 tools/lvm2/Makefile
create mode 100644 tools/popt/Makefile
--
2.23.0
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