Merge "fs_mgr_avb: refactors how vbmeta is loaded" (a6db40c7) · Commits · e / os / android_system_core

fs_mgr/fs_mgr.cpp

+37 −39

Original line number	Diff line number	Diff line
		@@ -707,6 +707,23 @@ static int handle_encryptable(const struct fstab_rec* rec)
		}
		}

		static std::string extract_by_name_prefix(struct fstab* fstab) {
		// We assume that there's an entry for the /misc mount point in the
		// fstab file and use that to get the device file by-name prefix.
		// The device needs not to have an actual /misc partition.
		// e.g.,
		// - /dev/block/platform/soc.0/7824900.sdhci/by-name/misc ->
		// - /dev/block/platform/soc.0/7824900.sdhci/by-name/
		struct fstab_rec* fstab_entry = fs_mgr_get_entry_for_mount_point(fstab, "/misc");
		if (fstab_entry == nullptr) {
		LERROR << "/misc mount point not found in fstab";
		return "";
		}
		std::string full_path(fstab_entry->blk_device);
		size_t end_slash = full_path.find_last_of("/");
		return full_path.substr(0, end_slash + 1);
		}

		// TODO: add ueventd notifiers if they don't exist.
		// This is just doing a wait_for_device for maximum of 1s
		int fs_mgr_test_access(const char *device) {
		@@ -750,17 +767,12 @@ int fs_mgr_mount_all(struct fstab *fstab, int mount_mode)
		int mret = -1;
		int mount_errno = 0;
		int attempted_idx = -1;
		int avb_ret = FS_MGR_SETUP_AVB_FAIL;
		FsManagerAvbUniquePtr avb_handle(nullptr);

		if (!fstab) {
		return -1;
		}

		if (fs_mgr_is_avb_used() &&
		(avb_ret = fs_mgr_load_vbmeta_images(fstab)) == FS_MGR_SETUP_AVB_FAIL) {
		return -1;
		}

		for (i = 0; i < fstab->num_entries; i++) {
		/* Don't mount entries that are managed by vold or not for the mount mode*/
		if ((fstab->recs[i].fs_mgr_flags & (MF_VOLDMANAGED \| MF_RECOVERYONLY)) \|\|
		@@ -799,16 +811,15 @@ int fs_mgr_mount_all(struct fstab *fstab, int mount_mode)
		wait_for_file(fstab->recs[i].blk_device, WAIT_TIMEOUT);
		}

		if (fs_mgr_is_avb_used() && (fstab->recs[i].fs_mgr_flags & MF_AVB)) {
		/* If HASHTREE_DISABLED is set (cf. 'adb disable-verity'), we
		* should set up the device without using dm-verity.
		* The actual mounting still take place in the following
		* mount_with_alternatives().
		*/
		if (avb_ret == FS_MGR_SETUP_AVB_HASHTREE_DISABLED) {
		LINFO << "AVB HASHTREE disabled";
		} else if (fs_mgr_setup_avb(&fstab->recs[i]) !=
		FS_MGR_SETUP_AVB_SUCCESS) {
		if (fstab->recs[i].fs_mgr_flags & MF_AVB) {
		if (!avb_handle) {
		avb_handle = FsManagerAvbHandle::Open(extract_by_name_prefix(fstab));
		if (!avb_handle) {
		LERROR << "Failed to open FsManagerAvbHandle";
		return -1;
		}
		}
		if (!avb_handle->SetUpAvb(&fstab->recs[i])) {
		LERROR << "Failed to set up AVB on partition: "
		<< fstab->recs[i].mount_point << ", skipping!";
		/* Skips mounting the device. */
		@@ -934,10 +945,6 @@ int fs_mgr_mount_all(struct fstab *fstab, int mount_mode)
		}
		}

		if (fs_mgr_is_avb_used()) {
		fs_mgr_unload_vbmeta_images();
		}

		if (error_count) {
		return -1;
		} else {
		@@ -976,17 +983,12 @@ int fs_mgr_do_mount(struct fstab fstab, const char n_name, char *n_blk_device,
		int mount_errors = 0;
		int first_mount_errno = 0;
		char *m;
		int avb_ret = FS_MGR_SETUP_AVB_FAIL;
		FsManagerAvbUniquePtr avb_handle(nullptr);

		if (!fstab) {
		return ret;
		}

		if (fs_mgr_is_avb_used() &&
		(avb_ret = fs_mgr_load_vbmeta_images(fstab)) == FS_MGR_SETUP_AVB_FAIL) {
		return ret;
		}

		for (i = 0; i < fstab->num_entries; i++) {
		if (!fs_match(fstab->recs[i].mount_point, n_name)) {
		continue;
		@@ -1021,16 +1023,15 @@ int fs_mgr_do_mount(struct fstab fstab, const char n_name, char *n_blk_device,
		do_reserved_size(n_blk_device, fstab->recs[i].fs_type, &fstab->recs[i], &fs_stat);
		}

		if (fs_mgr_is_avb_used() && (fstab->recs[i].fs_mgr_flags & MF_AVB)) {
		/* If HASHTREE_DISABLED is set (cf. 'adb disable-verity'), we
		* should set up the device without using dm-verity.
		* The actual mounting still take place in the following
		* mount_with_alternatives().
		*/
		if (avb_ret == FS_MGR_SETUP_AVB_HASHTREE_DISABLED) {
		LINFO << "AVB HASHTREE disabled";
		} else if (fs_mgr_setup_avb(&fstab->recs[i]) !=
		FS_MGR_SETUP_AVB_SUCCESS) {
		if (fstab->recs[i].fs_mgr_flags & MF_AVB) {
		if (!avb_handle) {
		avb_handle = FsManagerAvbHandle::Open(extract_by_name_prefix(fstab));
		if (!avb_handle) {
		LERROR << "Failed to open FsManagerAvbHandle";
		return -1;
		}
		}
		if (!avb_handle->SetUpAvb(&fstab->recs[i])) {
		LERROR << "Failed to set up AVB on partition: "
		<< fstab->recs[i].mount_point << ", skipping!";
		/* Skips mounting the device. */
		@@ -1079,9 +1080,6 @@ int fs_mgr_do_mount(struct fstab fstab, const char n_name, char *n_blk_device,
		}

		out:
		if (fs_mgr_is_avb_used()) {
		fs_mgr_unload_vbmeta_images();
		}
		return ret;
		}

fs_mgr/fs_mgr_avb.cpp

+118 −140

Original line number	Diff line number	Diff line
		@@ -28,6 +28,7 @@
		#include <android-base/file.h>
		#include <android-base/parseint.h>
		#include <android-base/properties.h>
		#include <android-base/stringprintf.h>
		#include <android-base/strings.h>
		#include <android-base/unique_fd.h>
		#include <cutils/properties.h>
		@@ -85,24 +86,6 @@
		hashtree_desc.fec_offset / hashtree_desc.data_block_size, /* fec_start */ \
		VERITY_TABLE_OPT_IGNZERO, VERITY_TABLE_OPT_RESTART

		AvbSlotVerifyData* fs_mgr_avb_verify_data = nullptr;
		AvbOps* fs_mgr_avb_ops = nullptr;

		enum HashAlgorithm {
		kInvalid = 0,
		kSHA256 = 1,
		kSHA512 = 2,
		};

		struct androidboot_vbmeta {
		HashAlgorithm hash_alg;
		uint8_t digest[SHA512_DIGEST_LENGTH];
		size_t vbmeta_size;
		bool allow_verification_error;
		};

		androidboot_vbmeta fs_mgr_vbmeta_prop;

		static inline bool nibble_value(const char& c, uint8_t* value) {
		FS_MGR_CHECK(value != nullptr);

		@@ -159,27 +142,78 @@ static std::string bytes_to_hex(const uint8_t* bytes, size_t bytes_len) {
		return hex;
		}

		static bool load_vbmeta_prop(androidboot_vbmeta* vbmeta_prop) {
		FS_MGR_CHECK(vbmeta_prop != nullptr);
		template <typename Hasher>
		static std::pair<size_t, bool> verify_vbmeta_digest(const AvbSlotVerifyData& verify_data,
		const uint8_t* expected_digest) {
		size_t total_size = 0;
		Hasher hasher;
		for (size_t n = 0; n < verify_data.num_vbmeta_images; n++) {
		hasher.update(verify_data.vbmeta_images[n].vbmeta_data,
		verify_data.vbmeta_images[n].vbmeta_size);
		total_size += verify_data.vbmeta_images[n].vbmeta_size;
		}

		bool matched = (memcmp(hasher.finalize(), expected_digest, Hasher::DIGEST_SIZE) == 0);

		return std::make_pair(total_size, matched);
		}

		// Reads the following values from kernel cmdline and provides the
		// VerifyVbmetaImages() to verify AvbSlotVerifyData.
		// - androidboot.vbmeta.device_state
		// - androidboot.vbmeta.hash_alg
		// - androidboot.vbmeta.size
		// - androidboot.vbmeta.digest
		class FsManagerAvbVerifier {
		public:
		// The factory method to return a unique_ptr<FsManagerAvbVerifier>
		static std::unique_ptr<FsManagerAvbVerifier> Create();
		bool VerifyVbmetaImages(const AvbSlotVerifyData& verify_data);
		bool IsDeviceUnlocked() { return is_device_unlocked_; }

		protected:
		FsManagerAvbVerifier() = default;

		private:
		enum HashAlgorithm {
		kInvalid = 0,
		kSHA256 = 1,
		kSHA512 = 2,
		};

		HashAlgorithm hash_alg_;
		uint8_t digest_[SHA512_DIGEST_LENGTH];
		size_t vbmeta_size_;
		bool is_device_unlocked_;
		};

		std::unique_ptr<FsManagerAvbVerifier> FsManagerAvbVerifier::Create() {
		std::string cmdline;
		android::base::ReadFileToString("/proc/cmdline", &cmdline);
		if (!android::base::ReadFileToString("/proc/cmdline", &cmdline)) {
		LERROR << "Failed to read /proc/cmdline";
		return nullptr;
		}

		std::string hash_alg;
		std::string digest;
		std::unique_ptr<FsManagerAvbVerifier> avb_verifier(new FsManagerAvbVerifier());
		if (!avb_verifier) {
		LERROR << "Failed to create unique_ptr<FsManagerAvbVerifier>";
		return nullptr;
		}

		std::string digest;
		std::string hash_alg;
		for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
		std::vector<std::string> pieces = android::base::Split(entry, "=");
		const std::string& key = pieces[0];
		const std::string& value = pieces[1];

		if (key == "androidboot.vbmeta.device_state") {
		vbmeta_prop->allow_verification_error = (value == "unlocked");
		avb_verifier->is_device_unlocked_ = (value == "unlocked");
		} else if (key == "androidboot.vbmeta.hash_alg") {
		hash_alg = value;
		} else if (key == "androidboot.vbmeta.size") {
		if (!android::base::ParseUint(value.c_str(), &vbmeta_prop->vbmeta_size)) {
		return false;
		if (!android::base::ParseUint(value.c_str(), &avb_verifier->vbmeta_size_)) {
		return nullptr;
		}
		} else if (key == "androidboot.vbmeta.digest") {
		digest = value;
		@@ -190,48 +224,31 @@ static bool load_vbmeta_prop(androidboot_vbmeta* vbmeta_prop) {
		size_t expected_digest_size = 0;
		if (hash_alg == "sha256") {
		expected_digest_size = SHA256_DIGEST_LENGTH * 2;
		vbmeta_prop->hash_alg = kSHA256;
		avb_verifier->hash_alg_ = kSHA256;
		} else if (hash_alg == "sha512") {
		expected_digest_size = SHA512_DIGEST_LENGTH * 2;
		vbmeta_prop->hash_alg = kSHA512;
		avb_verifier->hash_alg_ = kSHA512;
		} else {
		LERROR << "Unknown hash algorithm: " << hash_alg.c_str();
		return false;
		return nullptr;
		}

		// Reads digest.
		if (digest.size() != expected_digest_size) {
		LERROR << "Unexpected digest size: " << digest.size()
		<< " (expected: " << expected_digest_size << ")";
		return false;
		return nullptr;
		}

		if (!hex_to_bytes(vbmeta_prop->digest, sizeof(vbmeta_prop->digest), digest)) {
		if (!hex_to_bytes(avb_verifier->digest_, sizeof(avb_verifier->digest_), digest)) {
		LERROR << "Hash digest contains non-hexidecimal character: " << digest.c_str();
		return false;
		}

		return true;
		}

		template <typename Hasher>
		static std::pair<size_t, bool> verify_vbmeta_digest(const AvbSlotVerifyData& verify_data,
		const androidboot_vbmeta& vbmeta_prop) {
		size_t total_size = 0;
		Hasher hasher;
		for (size_t n = 0; n < verify_data.num_vbmeta_images; n++) {
		hasher.update(verify_data.vbmeta_images[n].vbmeta_data,
		verify_data.vbmeta_images[n].vbmeta_size);
		total_size += verify_data.vbmeta_images[n].vbmeta_size;
		return nullptr;
		}

		bool matched = (memcmp(hasher.finalize(), vbmeta_prop.digest, Hasher::DIGEST_SIZE) == 0);

		return std::make_pair(total_size, matched);
		return avb_verifier;
		}

		static bool verify_vbmeta_images(const AvbSlotVerifyData& verify_data,
		const androidboot_vbmeta& vbmeta_prop) {
		bool FsManagerAvbVerifier::VerifyVbmetaImages(const AvbSlotVerifyData& verify_data) {
		if (verify_data.num_vbmeta_images == 0) {
		LERROR << "No vbmeta images";
		return false;
		@@ -240,17 +257,17 @@ static bool verify_vbmeta_images(const AvbSlotVerifyData& verify_data,
		size_t total_size = 0;
		bool digest_matched = false;

		if (vbmeta_prop.hash_alg == kSHA256) {
		if (hash_alg_ == kSHA256) {
		std::tie(total_size, digest_matched) =
		verify_vbmeta_digest<SHA256Hasher>(verify_data, vbmeta_prop);
		} else if (vbmeta_prop.hash_alg == kSHA512) {
		verify_vbmeta_digest<SHA256Hasher>(verify_data, digest_);
		} else if (hash_alg_ == kSHA512) {
		std::tie(total_size, digest_matched) =
		verify_vbmeta_digest<SHA512Hasher>(verify_data, vbmeta_prop);
		verify_vbmeta_digest<SHA512Hasher>(verify_data, digest_);
		}

		if (total_size != vbmeta_prop.vbmeta_size) {
		LERROR << "total vbmeta size mismatch: " << total_size
		<< " (expected: " << vbmeta_prop.vbmeta_size << ")";
		if (total_size != vbmeta_size_) {
		LERROR << "total vbmeta size mismatch: " << total_size << " (expected: " << vbmeta_size_
		<< ")";
		return false;
		}

		@@ -408,8 +425,7 @@ static bool get_hashtree_descriptor(const std::string& partition_name,
		continue;
		}
		if (desc.tag == AVB_DESCRIPTOR_TAG_HASHTREE) {
		desc_partition_name =
		(const uint8_t*)descriptors[j] + sizeof(AvbHashtreeDescriptor);
		desc_partition_name = (const uint8_t*)descriptors[j] + sizeof(AvbHashtreeDescriptor);
		if (!avb_hashtree_descriptor_validate_and_byteswap(
		(AvbHashtreeDescriptor*)descriptors[j], out_hashtree_desc)) {
		continue;
		@@ -441,134 +457,96 @@ static bool get_hashtree_descriptor(const std::string& partition_name,
		return true;
		}

		static bool init_is_avb_used() {
		// When AVB is used, boot loader should set androidboot.vbmeta.{hash_alg,
		// size, digest} in kernel cmdline or in device tree. They will then be
		// imported by init process to system properties: ro.boot.vbmeta.{hash_alg, size, digest}.
		//
		// In case of early mount, init properties are not initialized, so we also
		// ensure we look into kernel command line and device tree if the property is
		// not found
		//
		// Checks hash_alg as an indicator for whether AVB is used.
		// We don't have to parse and check all of them here. The check will
		// be done in fs_mgr_load_vbmeta_images() and FS_MGR_SETUP_AVB_FAIL will
		// be returned when there is an error.

		std::string hash_alg;
		if (!fs_mgr_get_boot_config("vbmeta.hash_alg", &hash_alg)) {
		return false;
		}
		if (hash_alg == "sha256" \|\| hash_alg == "sha512") {
		return true;
		}
		return false;
		}

		bool fs_mgr_is_avb_used() {
		static bool result = init_is_avb_used();
		return result;
		FsManagerAvbUniquePtr FsManagerAvbHandle::Open(const std::string& device_file_by_name_prefix) {
		if (device_file_by_name_prefix.empty()) {
		LERROR << "Missing device file by-name prefix";
		return nullptr;
		}

		int fs_mgr_load_vbmeta_images(struct fstab* fstab) {
		FS_MGR_CHECK(fstab != nullptr);

		// Gets the expected hash value of vbmeta images from
		// kernel cmdline.
		if (!load_vbmeta_prop(&fs_mgr_vbmeta_prop)) {
		return FS_MGR_SETUP_AVB_FAIL;
		// Gets the expected hash value of vbmeta images from kernel cmdline.
		std::unique_ptr<FsManagerAvbVerifier> avb_verifier = FsManagerAvbVerifier::Create();
		if (!avb_verifier) {
		LERROR << "Failed to create FsManagerAvbVerifier";
		return nullptr;
		}

		fs_mgr_avb_ops = fs_mgr_dummy_avb_ops_new(fstab);
		if (fs_mgr_avb_ops == nullptr) {
		LERROR << "Failed to allocate dummy avb_ops";
		return FS_MGR_SETUP_AVB_FAIL;
		FsManagerAvbUniquePtr avb_handle(new FsManagerAvbHandle());
		if (!avb_handle) {
		LERROR << "Failed to allocate FsManagerAvbHandle";
		return nullptr;
		}

		// Invokes avb_slot_verify() to load and verify all vbmeta images.
		// Sets requested_partitions to nullptr as it's to copy the contents
		// of HASH partitions into fs_mgr_avb_verify_data, which is not required as
		// fs_mgr only deals with HASHTREE partitions.
		const char* requested_partitions[] = {nullptr};
		std::string ab_suffix = fs_mgr_get_slot_suffix();

		AvbSlotVerifyResult verify_result =
		avb_slot_verify(fs_mgr_avb_ops, requested_partitions, ab_suffix.c_str(),
		fs_mgr_vbmeta_prop.allow_verification_error, &fs_mgr_avb_verify_data);
		FsManagerAvbOps avb_ops(device_file_by_name_prefix);
		AvbSlotVerifyResult verify_result = avb_ops.AvbSlotVerify(
		fs_mgr_get_slot_suffix(), avb_verifier->IsDeviceUnlocked(), &avb_handle->avb_slot_data_);

		// Only allow two verify results:
		// - AVB_SLOT_VERIFY_RESULT_OK.
		// - AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION (for UNLOCKED state).
		if (verify_result == AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION) {
		if (!fs_mgr_vbmeta_prop.allow_verification_error) {
		if (!avb_verifier->IsDeviceUnlocked()) {
		LERROR << "ERROR_VERIFICATION isn't allowed";
		goto fail;
		return nullptr;
		}
		} else if (verify_result != AVB_SLOT_VERIFY_RESULT_OK) {
		LERROR << "avb_slot_verify failed, result: " << verify_result;
		goto fail;
		return nullptr;
		}

		// Verifies vbmeta images against the digest passed from bootloader.
		if (!verify_vbmeta_images(*fs_mgr_avb_verify_data, fs_mgr_vbmeta_prop)) {
		LERROR << "verify_vbmeta_images failed";
		goto fail;
		if (!avb_verifier->VerifyVbmetaImages(*avb_handle->avb_slot_data_)) {
		LERROR << "VerifyVbmetaImages failed";
		return nullptr;
		} else {
		// Checks whether FLAGS_HASHTREE_DISABLED is set.
		AvbVBMetaImageHeader vbmeta_header;
		avb_vbmeta_image_header_to_host_byte_order(
		(AvbVBMetaImageHeader*)fs_mgr_avb_verify_data->vbmeta_images[0].vbmeta_data,
		(AvbVBMetaImageHeader*)avb_handle->avb_slot_data_->vbmeta_images[0].vbmeta_data,
		&vbmeta_header);

		bool hashtree_disabled =
		((AvbVBMetaImageFlags)vbmeta_header.flags & AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED);
		if (hashtree_disabled) {
		return FS_MGR_SETUP_AVB_HASHTREE_DISABLED;
		avb_handle->status_ = kFsManagerAvbHandleHashtreeDisabled;
		return avb_handle;
		}
		}

		if (verify_result == AVB_SLOT_VERIFY_RESULT_OK) {
		return FS_MGR_SETUP_AVB_SUCCESS;
		}

		fail:
		fs_mgr_unload_vbmeta_images();
		return FS_MGR_SETUP_AVB_FAIL;
		avb_handle->status_ = kFsManagerAvbHandleSuccess;
		return avb_handle;
		}

		void fs_mgr_unload_vbmeta_images() {
		if (fs_mgr_avb_verify_data != nullptr) {
		avb_slot_verify_data_free(fs_mgr_avb_verify_data);
		return nullptr;
		}

		if (fs_mgr_avb_ops != nullptr) {
		fs_mgr_dummy_avb_ops_free(fs_mgr_avb_ops);
		}
		bool FsManagerAvbHandle::SetUpAvb(struct fstab_rec* fstab_entry) {
		if (!fstab_entry) return false;
		if (!avb_slot_data_ \|\| avb_slot_data_->num_vbmeta_images < 1) {
		return false;
		}

		int fs_mgr_setup_avb(struct fstab_rec* fstab_entry) {
		if (!fstab_entry \|\| !fs_mgr_avb_verify_data \|\| fs_mgr_avb_verify_data->num_vbmeta_images < 1) {
		return FS_MGR_SETUP_AVB_FAIL;
		if (status_ == kFsManagerAvbHandleHashtreeDisabled) {
		LINFO << "AVB HASHTREE disabled on:" << fstab_entry->mount_point;
		return true;
		}
		if (status_ != kFsManagerAvbHandleSuccess) return false;

		std::string partition_name(basename(fstab_entry->mount_point));
		if (!avb_validate_utf8((const uint8_t*)partition_name.c_str(), partition_name.length())) {
		LERROR << "Partition name: " << partition_name.c_str() << " is not valid UTF-8.";
		return FS_MGR_SETUP_AVB_FAIL;
		return false;
		}

		AvbHashtreeDescriptor hashtree_descriptor;
		std::string salt;
		std::string root_digest;
		if (!get_hashtree_descriptor(partition_name, *fs_mgr_avb_verify_data, &hashtree_descriptor,
		&salt, &root_digest)) {
		return FS_MGR_SETUP_AVB_FAIL;
		if (!get_hashtree_descriptor(partition_name, *avb_slot_data_, &hashtree_descriptor, &salt,
		&root_digest)) {
		return false;
		}

		// Converts HASHTREE descriptor to verity_table_params.
		if (!hashtree_dm_verity_setup(fstab_entry, hashtree_descriptor, salt, root_digest)) {
		return FS_MGR_SETUP_AVB_FAIL;
		return false;
		}

		return FS_MGR_SETUP_AVB_SUCCESS;
		return true;
		}

fs_mgr/fs_mgr_avb_ops.cpp

+76 −100

File changed.

Preview size limit exceeded, changes collapsed.

fs_mgr/fs_mgr_avb_ops.h

+30 −27

Original line number	Diff line number	Diff line
		@@ -29,31 +29,34 @@

		#include "fs_mgr.h"

		__BEGIN_DECLS

		/* Allocates a "dummy" AvbOps instance solely for use in user-space.
		* Returns nullptr on OOM.
		*
		* It mainly provides read_from_partitions() for user-space to get
		* AvbSlotVerifyData.vbmeta_images[] and the caller MUST check their
		* integrity against the androidboot.vbmeta.{hash_alg, size, digest}
		* values from /proc/cmdline, e.g. verify_vbmeta_images()
		* in fs_mgr_avb.cpp.
		*
		* Other I/O operations are only required in boot loader so we set
		* them as dummy operations here.
		* - Will allow any public key for signing.
		* - returns 0 for any rollback index location.
		* - returns device is unlocked regardless of the actual state.
		* - returns a dummy guid for any partition.
		*
		* Frees with fs_mgr_dummy_avb_ops_free().
		*/
		AvbOps* fs_mgr_dummy_avb_ops_new(struct fstab* fstab);

		/* Frees an AvbOps instance previously allocated with fs_mgr_avb_ops_new(). */
		void fs_mgr_dummy_avb_ops_free(AvbOps* ops);

		__END_DECLS

		// This class provides C++ bindings to interact with libavb, a small
		// self-contained piece of code that's intended to be used in bootloaders.
		// It mainly contains two functions:
		// - ReadFromPartition(): to read AVB metadata from a given partition.
		// It provides the implementation of AvbOps.read_from_partition() when
		// reading metadata through libavb.
		// - AvbSlotVerify(): the C++ binding of libavb->avb_slot_verify() to
		// read and verify the metadata and store it into the out_data parameter.
		// The caller MUST check the integrity of metadata against the
		// androidboot.vbmeta.{hash_alg, size, digest} values from /proc/cmdline.
		// e.g., see class FsManagerAvbVerifier for more details.
		//
		class FsManagerAvbOps {
		public:
		FsManagerAvbOps(const std::string& device_file_by_name_prefix);

		static FsManagerAvbOps* GetInstanceFromAvbOps(AvbOps* ops) {
		return reinterpret_cast<FsManagerAvbOps*>(ops->user_data);
		}

		AvbIOResult ReadFromPartition(const char* partition, int64_t offset, size_t num_bytes,
		void* buffer, size_t* out_num_read);

		AvbSlotVerifyResult AvbSlotVerify(const std::string& ab_suffix, bool allow_verification_error,
		AvbSlotVerifyData** out_data);

		private:
		AvbOps avb_ops_;
		std::string device_file_by_name_prefix_;
		};
		#endif /* __CORE_FS_MGR_AVB_OPS_H */

fs_mgr/fs_mgr_priv_avb.h

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