Merge "Check SPL downgrade before install OTA in recovery" (bbde214b) · Commits · e / os / android_bootable_recovery

install/Android.bp

+41 −0

Original line number	Diff line number	Diff line
		@@ -26,6 +26,7 @@ cc_defaults {

		defaults: [
		"recovery_defaults",
		"libspl_check_defaults",
		],

		shared_libs: [
		@@ -49,12 +50,51 @@ cc_defaults {
		"librecovery_utils",
		"libotautil",
		"libsnapshot_nobinder",
		"ota_metadata_proto_cc",

		// external dependencies
		"libvintf",
		],
		}

		cc_test_host {
		name: "libinstall_host_unittests",
		defaults: [
		"libspl_check_defaults"
		],
		srcs: [
		"spl_check_unittests.cpp",
		],
		static_libs: [
		"libspl_check",
		],
		}

		cc_defaults {
		name: "libspl_check_defaults",
		static_libs: [
		"libbase",
		"ota_metadata_proto_cc",
		"liblog",
		"libziparchive",
		"libz",
		"libprotobuf-cpp-lite",
		],
		}

		cc_library_static {
		name: "libspl_check",
		recovery_available: true,
		host_supported: true,
		defaults: [
		"libspl_check_defaults",
		],
		srcs: ["spl_check.cpp"],
		export_include_dirs: [
		"include",
		],
		}

		cc_library_static {
		name: "libinstall",
		recovery_available: true,
		@@ -73,6 +113,7 @@ cc_library_static {
		"verifier.cpp",
		"wipe_data.cpp",
		"wipe_device.cpp",
		"spl_check.cpp",
		],

		header_libs: [

install/include/install/spl_check.h

0 → 100644

+26 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <string_view>

		#include <android-base/logging.h>
		#include <ota_metadata.pb.h>
		#include <ziparchive/zip_archive.h>

		bool ViolatesSPLDowngrade(const build::tools::releasetools::OtaMetadata& metadata,
		std::string_view current_spl);

		bool ViolatesSPLDowngrade(ZipArchiveHandle zip, std::string_view current_spl);

install/install.cpp

+7 −0

Original line number	Diff line number	Diff line
		@@ -47,6 +47,7 @@
		#include <android-base/unique_fd.h>

		#include "install/package.h"
		#include "install/spl_check.h"
		#include "install/verifier.h"
		#include "install/wipe_data.h"
		#include "otautil/error_code.h"
		@@ -348,6 +349,12 @@ static InstallResult TryUpdateBinary(Package* package, bool* wipe_cache,
		android::base::GetBoolProperty("ro.virtual_ab.allow_non_ab", false);
		bool device_only_supports_ab = device_supports_ab && !ab_device_supports_nonab;

		const auto current_spl = android::base::GetProperty("ro.build.version.security_patch", "");
		if (ViolatesSPLDowngrade(zip, current_spl)) {
		LOG(ERROR) << "Denying OTA because it's SPL downgrade";
		return INSTALL_ERROR;
		}

		if (package_is_ab) {
		CHECK(package->GetType() == PackageType::kFile);
		}

install/spl_check.cpp

0 → 100644

+78 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include "install/spl_check.h"

		bool ViolatesSPLDowngrade(const build::tools::releasetools::OtaMetadata& metadata,
		std::string_view current_spl) {
		const auto& post_spl = metadata.postcondition().security_patch_level();
		if (current_spl.empty()) {
		LOG(WARNING) << "Failed to get device's current security patch level. Target SPL is "
		<< post_spl << " permitting OTA install";
		return false;
		}
		// SPL(security patch level) is expected to be in format yyyy-mm-dd, e.g. 2018-05-29. Given this
		// specific format, comparing two SPL can be done by just regular string comparison. If the format
		// must lay out year/month/date in the exact order, and must properly prepend dates with 0(for
		// example, 05 for May). Otherwise this comparison doesn't work. We don't expect SPL date formats
		// to change, leave this as is.
		if (post_spl < current_spl) {
		LOG(ERROR) << "Current SPL: " << current_spl << " Target SPL: " << post_spl
		<< " this is considered a downgrade";
		if (metadata.spl_downgrade() \|\| metadata.downgrade()) {
		LOG(WARNING)
		<< "SPL downgrade detected, but OTA package explicitly permitts this(OtaMetadata has "
		"spl_downgrade / downgrade bit set).Permitting update anyway.Installing a SPL "
		"downgrade OTA can cause /data fail to decrypt and device fails to boot.";
		return false;
		}
		return true;
		} else {
		LOG(INFO) << "old spl: " << current_spl << " new spl: " << post_spl << " CHECK passes";
		}
		return false;
		}

		bool ViolatesSPLDowngrade(ZipArchiveHandle zip, std::string_view current_spl) {
		static constexpr auto&& OTA_OTA_METADATA = "META-INF/com/android/metadata.pb";
		ZipEntry64 metadata_entry;
		if (FindEntry(zip, OTA_OTA_METADATA, &metadata_entry) != 0) {
		LOG(WARNING) << "Failed to find " << OTA_OTA_METADATA
		<< " treating this as non-spl-downgrade, permit OTA install. If device bricks "
		"after installing, check kernel log to see if /data failed to decrypt";
		return false;
		}
		const auto metadata_entry_length = metadata_entry.uncompressed_length;
		if (metadata_entry_length > std::numeric_limits<size_t>::max()) {
		LOG(ERROR) << "Failed to extract " << OTA_OTA_METADATA
		<< " because's uncompressed size exceeds size of address space. "
		<< metadata_entry_length;
		return false;
		}
		std::vector<uint8_t> ota_metadata(metadata_entry_length);
		int32_t err = ExtractToMemory(zip, &metadata_entry, ota_metadata.data(), metadata_entry_length);
		if (err != 0) {
		LOG(ERROR) << "Failed to extract " << OTA_OTA_METADATA << ": " << ErrorCodeString(err);
		return false;
		}
		using build::tools::releasetools::OtaMetadata;
		OtaMetadata metadata;
		if (!metadata.ParseFromArray(ota_metadata.data(), ota_metadata.size())) {
		LOG(ERROR) << "Failed to parse ota_medata";
		return false;
		}
		return ViolatesSPLDowngrade(metadata, current_spl);
		}

install/spl_check_unittests.cpp

0 → 100644

+45 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <gtest/gtest.h>

		#include "install/spl_check.h"
		#include "ota_metadata.pb.h"

		using build::tools::releasetools::OtaMetadata;
		class SplCheckUnittest : public ::testing::Test {
		public:
		OtaMetadata metadata;
		};

		TEST_F(SplCheckUnittest, OlderSPL) {
		metadata.set_spl_downgrade(false);
		metadata.mutable_postcondition()->set_security_patch_level("2021-04-25");
		ASSERT_TRUE(ViolatesSPLDowngrade(metadata, "2021-05-01"));
		}

		TEST_F(SplCheckUnittest, NewerSPL) {
		metadata.set_spl_downgrade(false);
		metadata.mutable_postcondition()->set_security_patch_level("2021-06-01");
		ASSERT_FALSE(ViolatesSPLDowngrade(metadata, "2021-05-05"));
		}

		TEST_F(SplCheckUnittest, OlderSPLPermit) {
		// If spl_downgrade is set to true, OTA should be permitted
		metadata.set_spl_downgrade(true);
		metadata.mutable_postcondition()->set_security_patch_level("2021-04-11");
		ASSERT_FALSE(ViolatesSPLDowngrade(metadata, "2021-05-11"));
		}
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