avb2.0: add Android Verified Boot 2.0 library
Add libavb lib (3rd party library from AOSP), that implements support of
AVB 2.0. This library is used for integrity checking of Android partitions
on eMMC.
libavb was added as it is and minimal changes were introduced to reduce
maintenance cost, because it will be deviated from AOSP upstream in the future.
Changes:
- license headers changed to conform SPDX-style
- avb_crc32.c dropped
- updates in avb_sysdeps_posix.c/avb_sysdeps.h
For additional details check [1] AVB 2.0 README.
[1] https://android.googlesource.com/platform/external/avb/+/master/README.md
Signed-off-by: Igor Opaniuk <igor.opaniuk@linaro.org>
diff --git a/lib/libavb/avb_vbmeta_image.c b/lib/libavb/avb_vbmeta_image.c
new file mode 100644
index 0000000..2acca7d
--- /dev/null
+++ b/lib/libavb/avb_vbmeta_image.c
@@ -0,0 +1,290 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "avb_vbmeta_image.h"
+#include "avb_crypto.h"
+#include "avb_rsa.h"
+#include "avb_sha.h"
+#include "avb_util.h"
+#include "avb_version.h"
+
+AvbVBMetaVerifyResult avb_vbmeta_image_verify(
+ const uint8_t* data,
+ size_t length,
+ const uint8_t** out_public_key_data,
+ size_t* out_public_key_length) {
+ AvbVBMetaVerifyResult ret;
+ AvbVBMetaImageHeader h;
+ uint8_t* computed_hash;
+ const AvbAlgorithmData* algorithm;
+ AvbSHA256Ctx sha256_ctx;
+ AvbSHA512Ctx sha512_ctx;
+ const uint8_t* header_block;
+ const uint8_t* authentication_block;
+ const uint8_t* auxiliary_block;
+ int verification_result;
+
+ ret = AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER;
+
+ if (out_public_key_data != NULL) {
+ *out_public_key_data = NULL;
+ }
+ if (out_public_key_length != NULL) {
+ *out_public_key_length = 0;
+ }
+
+ /* Ensure magic is correct. */
+ if (avb_safe_memcmp(data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) {
+ avb_error("Magic is incorrect.\n");
+ goto out;
+ }
+
+ /* Before we byteswap, ensure length is long enough. */
+ if (length < sizeof(AvbVBMetaImageHeader)) {
+ avb_error("Length is smaller than header.\n");
+ goto out;
+ }
+ avb_vbmeta_image_header_to_host_byte_order((const AvbVBMetaImageHeader*)data,
+ &h);
+
+ /* Ensure we don't attempt to access any fields if we do not meet
+ * the specified minimum version of libavb.
+ */
+ if ((h.required_libavb_version_major != AVB_VERSION_MAJOR) ||
+ (h.required_libavb_version_minor > AVB_VERSION_MINOR)) {
+ avb_error("Mismatch between image version and libavb version.\n");
+ ret = AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION;
+ goto out;
+ }
+
+ /* Ensure |release_string| ends with a NUL byte. */
+ if (h.release_string[AVB_RELEASE_STRING_SIZE - 1] != '\0') {
+ avb_error("Release string does not end with a NUL byte.\n");
+ goto out;
+ }
+
+ /* Ensure inner block sizes are multiple of 64. */
+ if ((h.authentication_data_block_size & 0x3f) != 0 ||
+ (h.auxiliary_data_block_size & 0x3f) != 0) {
+ avb_error("Block size is not a multiple of 64.\n");
+ goto out;
+ }
+
+ /* Ensure block sizes all add up to at most |length|. */
+ uint64_t block_total = sizeof(AvbVBMetaImageHeader);
+ if (!avb_safe_add_to(&block_total, h.authentication_data_block_size) ||
+ !avb_safe_add_to(&block_total, h.auxiliary_data_block_size)) {
+ avb_error("Overflow while computing size of boot image.\n");
+ goto out;
+ }
+ if (block_total > length) {
+ avb_error("Block sizes add up to more than given length.\n");
+ goto out;
+ }
+
+ uintptr_t data_ptr = (uintptr_t)data;
+ /* Ensure passed in memory doesn't wrap. */
+ if (!avb_safe_add(NULL, (uint64_t)data_ptr, length)) {
+ avb_error("Boot image location and length mismatch.\n");
+ goto out;
+ }
+
+ /* Ensure hash and signature are entirely in the Authentication data block. */
+ uint64_t hash_end;
+ if (!avb_safe_add(&hash_end, h.hash_offset, h.hash_size) ||
+ hash_end > h.authentication_data_block_size) {
+ avb_error("Hash is not entirely in its block.\n");
+ goto out;
+ }
+ uint64_t signature_end;
+ if (!avb_safe_add(&signature_end, h.signature_offset, h.signature_size) ||
+ signature_end > h.authentication_data_block_size) {
+ avb_error("Signature is not entirely in its block.\n");
+ goto out;
+ }
+
+ /* Ensure public key is entirely in the Auxiliary data block. */
+ uint64_t pubkey_end;
+ if (!avb_safe_add(&pubkey_end, h.public_key_offset, h.public_key_size) ||
+ pubkey_end > h.auxiliary_data_block_size) {
+ avb_error("Public key is not entirely in its block.\n");
+ goto out;
+ }
+
+ /* Ensure public key metadata (if set) is entirely in the Auxiliary
+ * data block. */
+ if (h.public_key_metadata_size > 0) {
+ uint64_t pubkey_md_end;
+ if (!avb_safe_add(&pubkey_md_end,
+ h.public_key_metadata_offset,
+ h.public_key_metadata_size) ||
+ pubkey_md_end > h.auxiliary_data_block_size) {
+ avb_error("Public key metadata is not entirely in its block.\n");
+ goto out;
+ }
+ }
+
+ /* Bail early if there's no hash or signature. */
+ if (h.algorithm_type == AVB_ALGORITHM_TYPE_NONE) {
+ ret = AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED;
+ goto out;
+ }
+
+ /* Ensure algorithm field is supported. */
+ algorithm = avb_get_algorithm_data(h.algorithm_type);
+ if (!algorithm) {
+ avb_error("Invalid or unknown algorithm.\n");
+ goto out;
+ }
+
+ /* Bail if the embedded hash size doesn't match the chosen algorithm. */
+ if (h.hash_size != algorithm->hash_len) {
+ avb_error("Embedded hash has wrong size.\n");
+ goto out;
+ }
+
+ /* No overflow checks needed from here-on after since all block
+ * sizes and offsets have been verified above.
+ */
+
+ header_block = data;
+ authentication_block = header_block + sizeof(AvbVBMetaImageHeader);
+ auxiliary_block = authentication_block + h.authentication_data_block_size;
+
+ switch (h.algorithm_type) {
+ /* Explicit fall-through: */
+ case AVB_ALGORITHM_TYPE_SHA256_RSA2048:
+ case AVB_ALGORITHM_TYPE_SHA256_RSA4096:
+ case AVB_ALGORITHM_TYPE_SHA256_RSA8192:
+ avb_sha256_init(&sha256_ctx);
+ avb_sha256_update(
+ &sha256_ctx, header_block, sizeof(AvbVBMetaImageHeader));
+ avb_sha256_update(
+ &sha256_ctx, auxiliary_block, h.auxiliary_data_block_size);
+ computed_hash = avb_sha256_final(&sha256_ctx);
+ break;
+ /* Explicit fall-through: */
+ case AVB_ALGORITHM_TYPE_SHA512_RSA2048:
+ case AVB_ALGORITHM_TYPE_SHA512_RSA4096:
+ case AVB_ALGORITHM_TYPE_SHA512_RSA8192:
+ avb_sha512_init(&sha512_ctx);
+ avb_sha512_update(
+ &sha512_ctx, header_block, sizeof(AvbVBMetaImageHeader));
+ avb_sha512_update(
+ &sha512_ctx, auxiliary_block, h.auxiliary_data_block_size);
+ computed_hash = avb_sha512_final(&sha512_ctx);
+ break;
+ default:
+ avb_error("Unknown algorithm.\n");
+ goto out;
+ }
+
+ if (avb_safe_memcmp(authentication_block + h.hash_offset,
+ computed_hash,
+ h.hash_size) != 0) {
+ avb_error("Hash does not match!\n");
+ ret = AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH;
+ goto out;
+ }
+
+ verification_result =
+ avb_rsa_verify(auxiliary_block + h.public_key_offset,
+ h.public_key_size,
+ authentication_block + h.signature_offset,
+ h.signature_size,
+ authentication_block + h.hash_offset,
+ h.hash_size,
+ algorithm->padding,
+ algorithm->padding_len);
+
+ if (verification_result == 0) {
+ ret = AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH;
+ goto out;
+ }
+
+ if (h.public_key_size > 0) {
+ if (out_public_key_data != NULL) {
+ *out_public_key_data = auxiliary_block + h.public_key_offset;
+ }
+ if (out_public_key_length != NULL) {
+ *out_public_key_length = h.public_key_size;
+ }
+ }
+
+ ret = AVB_VBMETA_VERIFY_RESULT_OK;
+
+out:
+ return ret;
+}
+
+void avb_vbmeta_image_header_to_host_byte_order(const AvbVBMetaImageHeader* src,
+ AvbVBMetaImageHeader* dest) {
+ avb_memcpy(dest, src, sizeof(AvbVBMetaImageHeader));
+
+ dest->required_libavb_version_major =
+ avb_be32toh(dest->required_libavb_version_major);
+ dest->required_libavb_version_minor =
+ avb_be32toh(dest->required_libavb_version_minor);
+
+ dest->authentication_data_block_size =
+ avb_be64toh(dest->authentication_data_block_size);
+ dest->auxiliary_data_block_size =
+ avb_be64toh(dest->auxiliary_data_block_size);
+
+ dest->algorithm_type = avb_be32toh(dest->algorithm_type);
+
+ dest->hash_offset = avb_be64toh(dest->hash_offset);
+ dest->hash_size = avb_be64toh(dest->hash_size);
+
+ dest->signature_offset = avb_be64toh(dest->signature_offset);
+ dest->signature_size = avb_be64toh(dest->signature_size);
+
+ dest->public_key_offset = avb_be64toh(dest->public_key_offset);
+ dest->public_key_size = avb_be64toh(dest->public_key_size);
+
+ dest->public_key_metadata_offset =
+ avb_be64toh(dest->public_key_metadata_offset);
+ dest->public_key_metadata_size = avb_be64toh(dest->public_key_metadata_size);
+
+ dest->descriptors_offset = avb_be64toh(dest->descriptors_offset);
+ dest->descriptors_size = avb_be64toh(dest->descriptors_size);
+
+ dest->rollback_index = avb_be64toh(dest->rollback_index);
+ dest->flags = avb_be32toh(dest->flags);
+}
+
+const char* avb_vbmeta_verify_result_to_string(AvbVBMetaVerifyResult result) {
+ const char* ret = NULL;
+
+ switch (result) {
+ case AVB_VBMETA_VERIFY_RESULT_OK:
+ ret = "OK";
+ break;
+ case AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED:
+ ret = "OK_NOT_SIGNED";
+ break;
+ case AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER:
+ ret = "INVALID_VBMETA_HEADER";
+ break;
+ case AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION:
+ ret = "UNSUPPORTED_VERSION";
+ break;
+ case AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH:
+ ret = "HASH_MISMATCH";
+ break;
+ case AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH:
+ ret = "SIGNATURE_MISMATCH";
+ break;
+ /* Do not add a 'default:' case here because of -Wswitch. */
+ }
+
+ if (ret == NULL) {
+ avb_error("Unknown AvbVBMetaVerifyResult value.\n");
+ ret = "(unknown)";
+ }
+
+ return ret;
+}