AVB: support chain partition signing
Current build system will include AVB metadata from each partition and
store them into /vbmeta partiton when BOARD_AVB_ENABLE is set, which makes
each partition tightly-coupled.
Add the support for 'chain partition':
- The vbmeta of each partition is stored on the same partition itself.
- The public key used to verify each partition is stored in /vbmeta.
For example, the following build variables are required to enable chain
partition for system partition:
- BOARD_AVB_SYSTEM_KEY_PATH := path/to/system_private_key
- BOARD_AVB_SYSTEM_ALGORITHM := SHA512_RSA8192
- BOARD_AVB_SYSTEM_ROLLBACK_INDEX := 1
- BOARD_AVB_SYSTEM_ROLLBACK_INDEX_LOCATION := 2
The corresponding settings will be added into META/misc_info.txt for
build_image.py and/or add_img_to_target_files.py:
- avb_system_key_path=path/to/system_private_key
- avb_system_algorithm=SHA512_RSA8192
- avb_system_add_hashtree_footer_args=--rollback_index 1
- avb_system_rollback_index_location=2
To enable chain partition for other partitions, just replace SYSTEM with
BOOT, VENDOR and/or DTBO in the build variables.
Also switch from `avbtool make_vbmeta_image --setup_rootfs_from_kernel system.img ...`
to `avbtool add_hashtree_footer --image system.img --setup_as_rootfs_from_kernel...`
when BOARD_BUILD_SYSTEM_ROOT_IMAGE is true. This works for both chained
and no-chained:
- chained: `avbtool add_hashtree_footer --setup_as_rootfs_from_kernel` will
add dm-verity kernel cmdline descriptor to system.img
- no-chained: `avbtool make_vbmeta_image --include_descriptors_from_image
system.img` will include the kernel cmdline descriptor from system.img into
vbmeta.img
Bug: 38399657
Test: `make` pass, flash images from $OUT and boot device without chain partitions
Test: `make` pass, flash images from $OUT and boot device with chain partitions
Test: `make dist` pass, flash images from TF.zip and boot device without chain partitions
Test: `make dist` pass, flash images from TF.zip and boot device with chain partitions
Test: follow the same steps in
https://android-review.googlesource.com/#/c/407572/
Change-Id: I344f79290743d7d47b5e7441b3a21df812a69099
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 652fadf..2ad628b 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -345,6 +345,15 @@
print("%-25s = (%s) %s" % (k, type(v).__name__, v))
+def AppendAVBSigningArgs(cmd, partition):
+ """Append signing arguments for avbtool."""
+ # e.g., "--key path/to/signing_key --algorithm SHA256_RSA4096"
+ key_path = OPTIONS.info_dict.get("avb_" + partition + "_key_path")
+ algorithm = OPTIONS.info_dict.get("avb_" + partition + "_algorithm")
+ if key_path and algorithm:
+ cmd.extend(["--key", key_path, "--algorithm", algorithm])
+
+
def _BuildBootableImage(sourcedir, fs_config_file, info_dict=None,
has_ramdisk=False, two_step_image=False):
"""Build a bootable image from the specified sourcedir.
@@ -480,13 +489,13 @@
img_keyblock.close()
# AVB: if enabled, calculate and add hash to boot.img.
- if info_dict.get("board_avb_enable", None) == "true":
+ if info_dict.get("avb_enable") == "true":
avbtool = os.getenv('AVBTOOL') or info_dict["avb_avbtool"]
part_size = info_dict["boot_size"]
cmd = [avbtool, "add_hash_footer", "--image", img.name,
"--partition_size", str(part_size), "--partition_name", "boot"]
- cmd.extend(shlex.split(info_dict["avb_signing_args"]))
- args = info_dict.get("board_avb_boot_add_hash_footer_args")
+ AppendAVBSigningArgs(cmd, "boot")
+ args = info_dict.get("avb_boot_add_hash_footer_args")
if args and args.strip():
cmd.extend(shlex.split(args))
p = Run(cmd, stdout=subprocess.PIPE)