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lib/libavb/avb_vbmeta_image.c
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897a1d947 libavb: Update SP... |
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// SPDX-License-Identifier: MIT |
d8f9d2af9 avb2.0: add Andro... |
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/* * Copyright (C) 2016 The Android Open Source Project |
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*/ #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. "); goto out; } /* Before we byteswap, ensure length is long enough. */ if (length < sizeof(AvbVBMetaImageHeader)) { avb_error("Length is smaller than header. "); 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. "); 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. "); 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. "); 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. "); goto out; } if (block_total > length) { avb_error("Block sizes add up to more than given length. "); 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. "); 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. "); 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. "); 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. "); 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. "); 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. "); 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. "); 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. "); goto out; } if (avb_safe_memcmp(authentication_block + h.hash_offset, computed_hash, h.hash_size) != 0) { avb_error("Hash does not match! "); 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. "); ret = "(unknown)"; } return ret; } |