AVB: decouple vbmeta.img from recovery.img for non-A/B devices
For following cases:
Case 1: A/B devices: no change
Case 2: non-A/B devices, with unsigned recovery image:
not allowed anymore by mandating BOARD_AVB_RECOVERY_KEY_PATH
Case 3: non-A/B devices, with signed recovery image:
vbmeta.img should not include ChainPartitionDescriptor of recovery.img,
otherwise device can not even boot into normal mode if recovery partition
is damaged
This CL will cause a build break if BOARD_AVB_RECOVERY_KEY_PATH
is not set for non-A/B targets with recovery.img
The following is an example to fix the build break by specifying
AVB signing configs for the recovery.img.
BOARD_AVB_RECOVERY_KEY_PATH := external/avb/test/data/testkey_rsa2048.pem
BOARD_AVB_RECOVERY_ALGORITHM := SHA256_RSA2048
BOARD_AVB_RECOVERY_ROLLBACK_INDEX := $(PLATFORM_SECURITY_PATCH_TIMESTAMP)
BOARD_AVB_RECOVERY_ROLLBACK_INDEX_LOCATION := 2
Also note that libavb in bootloader needs an update to include this
commit Iaa886037edb18c2ff6c60fa2a7f883ab7303ba1a, to support verifying
recovery.img independently (not through vbmeta.img).
Bug: 130351427
Test (Case 3):
normal mode: avb_slot_verify(flags=AVB_SLOT_VERIFY_FLAGS_NONE)
recovery mode: avb_slot_verify(flags=AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION)
Test: PYTHONPATH=build/make/tools/releasetools \
python -m unittest test_validate_target_files
Test: Use a lunch'd target. `atest --host releasetools_test releasetools_py3_test`
Test: validate_target_files.py with Case-3 target files
Change-Id: I2a73252b385fa463b4abd444923a8acc473df0b4
diff --git a/core/Makefile b/core/Makefile
index 1b6c532..368624f 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -3289,6 +3289,17 @@
$(error BOARD_AVB_VBMETA_SYSTEM and BOARD_AVB_VBMETA_VENDOR cannot have duplicates)
endif
+# When building a standalone recovery image for non-A/B devices, recovery image must be self-signed
+# to be verified independently, and cannot be chained into vbmeta.img. See the link below for
+# details.
+ifneq ($(AB_OTA_UPDATER),true)
+ifneq ($(INSTALLED_RECOVERYIMAGE_TARGET),)
+$(if $(BOARD_AVB_RECOVERY_KEY_PATH),,\
+ $(error BOARD_AVB_RECOVERY_KEY_PATH must be defined for non-A/B devices. \
+ See https://android.googlesource.com/platform/external/avb/+/master/README.md#booting-into-recovery))
+endif
+endif
+
# Appends os version and security patch level as a AVB property descriptor
BOARD_AVB_SYSTEM_ADD_HASHTREE_FOOTER_ARGS += \
@@ -3358,8 +3369,11 @@
$(eval $(_signing_args) := \
--algorithm $($(_signing_algorithm)) --key $($(_key_path)))
-$(eval INTERNAL_AVB_MAKE_VBMETA_IMAGE_ARGS += \
- --chain_partition $(part):$($(_rollback_index_location)):$(AVB_CHAIN_KEY_DIR)/$(part).avbpubkey)
+# The recovery partition in non-A/B devices should be verified separately. Skip adding the chain
+# partition descriptor for recovery partition into vbmeta.img.
+$(if $(or $(filter true,$(AB_OTA_UPDATER)),$(filter-out recovery,$(part))),\
+ $(eval INTERNAL_AVB_MAKE_VBMETA_IMAGE_ARGS += \
+ --chain_partition $(part):$($(_rollback_index_location)):$(AVB_CHAIN_KEY_DIR)/$(part).avbpubkey))
# Set rollback_index via footer args for non-chained vbmeta image. Chained vbmeta image will pick up
# the index via a separate flag (e.g. BOARD_AVB_VBMETA_SYSTEM_ROLLBACK_INDEX).
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index d73628f..b7a7f37 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -873,10 +873,20 @@
# Check if chain partition is used.
key_path = info_dict.get("avb_" + partition + "_key_path")
- if key_path:
- chained_partition_arg = GetAvbChainedPartitionArg(partition, info_dict)
- return ["--chain_partition", chained_partition_arg]
- return ["--include_descriptors_from_image", image]
+ if not key_path:
+ return ["--include_descriptors_from_image", image]
+
+ # For a non-A/B device, we don't chain /recovery nor include its descriptor
+ # into vbmeta.img. The recovery image will be configured on an independent
+ # boot chain, to be verified with AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION.
+ # See details at
+ # https://android.googlesource.com/platform/external/avb/+/master/README.md#booting-into-recovery.
+ if OPTIONS.info_dict.get("ab_update") != "true" and partition == "recovery":
+ return []
+
+ # Otherwise chain the partition into vbmeta.
+ chained_partition_arg = GetAvbChainedPartitionArg(partition, info_dict)
+ return ["--chain_partition", chained_partition_arg]
def GetAvbChainedPartitionArg(partition, info_dict, key=None):
diff --git a/tools/releasetools/validate_target_files.py b/tools/releasetools/validate_target_files.py
index 383ef7b..9c2bc51 100755
--- a/tools/releasetools/validate_target_files.py
+++ b/tools/releasetools/validate_target_files.py
@@ -346,20 +346,25 @@
key = info_dict['avb_vbmeta_key_path']
# avbtool verifies all the images that have descriptors listed in vbmeta.
+ # Using `--follow_chain_partitions` so it would additionally verify chained
+ # vbmeta partitions (e.g. vbmeta_system).
image = os.path.join(input_tmp, 'IMAGES', 'vbmeta.img')
cmd = [info_dict['avb_avbtool'], 'verify_image', '--image', image,
- '--key', key]
+ '--key', key, '--follow_chain_partitions']
# Append the args for chained partitions if any.
for partition in common.AVB_PARTITIONS + common.AVB_VBMETA_PARTITIONS:
key_name = 'avb_' + partition + '_key_path'
if info_dict.get(key_name) is not None:
+ if info_dict.get('ab_update') != 'true' and partition == 'recovery':
+ continue
+
# Use the key file from command line if specified; otherwise fall back
# to the one in info dict.
key_file = options.get(key_name, info_dict[key_name])
chained_partition_arg = common.GetAvbChainedPartitionArg(
partition, info_dict, key_file)
- cmd.extend(["--expected_chain_partition", chained_partition_arg])
+ cmd.extend(['--expected_chain_partition', chained_partition_arg])
proc = common.Run(cmd)
stdoutdata, _ = proc.communicate()
@@ -371,6 +376,22 @@
'Verified %s with avbtool (key: %s):\n%s', image, key,
stdoutdata.rstrip())
+ # avbtool verifies recovery image for non-A/B devices.
+ if (info_dict.get('ab_update') != 'true' and
+ info_dict.get('no_recovery') != 'true'):
+ image = os.path.join(input_tmp, 'IMAGES', 'recovery.img')
+ key = info_dict['avb_recovery_key_path']
+ cmd = [info_dict['avb_avbtool'], 'verify_image', '--image', image,
+ '--key', key]
+ proc = common.Run(cmd)
+ stdoutdata, _ = proc.communicate()
+ assert proc.returncode == 0, \
+ 'Failed to verify {} with avbtool (key: {}):\n{}'.format(
+ image, key, stdoutdata)
+ logging.info(
+ 'Verified %s with avbtool (key: %s):\n%s', image, key,
+ stdoutdata.rstrip())
+
def main():
parser = argparse.ArgumentParser(