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129 lines
4.9 KiB
129 lines
4.9 KiB
/*
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* Copyright (C) 2020 The Android Open Source Project
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include <libavb/avb_crypto.h>
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#include <libavb/avb_rsa.h>
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#include <libavb/avb_sha.h>
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#include <libavb/avb_util.h>
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#include "avb_aftl_types.h"
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#include "avb_aftl_util.h"
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#include "avb_aftl_validate.h"
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/* Verifies that the logged VBMeta hash matches the one on device. */
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bool avb_aftl_verify_vbmeta_hash(uint8_t* vbmeta,
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size_t vbmeta_size,
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AftlIcpEntry* icp_entry) {
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uint8_t vbmeta_hash[AVB_AFTL_HASH_SIZE];
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avb_assert(vbmeta != NULL && icp_entry != NULL);
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if (!avb_aftl_sha256(vbmeta, vbmeta_size, vbmeta_hash)) return false;
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/* Only SHA256 hashes are currently supported. If the vbmeta hash
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size is not AVB_AFTL_HASH_SIZE, return false. */
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if (icp_entry->annotation_leaf->annotation->vbmeta_hash_size !=
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AVB_AFTL_HASH_SIZE) {
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avb_error("Invalid VBMeta hash size.\n");
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return false;
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}
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/* Return whether the calculated VBMeta hash matches the stored one. */
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return avb_safe_memcmp(vbmeta_hash,
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icp_entry->annotation_leaf->annotation->vbmeta_hash,
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AVB_AFTL_HASH_SIZE) == 0;
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}
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/* Verifies the Merkle tree root hash. */
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bool avb_aftl_verify_icp_root_hash(AftlIcpEntry* icp_entry) {
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uint8_t leaf_hash[AVB_AFTL_HASH_SIZE];
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uint8_t result_hash[AVB_AFTL_HASH_SIZE];
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avb_assert(icp_entry != NULL);
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/* Calculate the RFC 6962 hash of the seed entry. */
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if (!avb_aftl_rfc6962_hash_leaf(icp_entry->annotation_leaf_raw,
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icp_entry->annotation_leaf_size,
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leaf_hash)) {
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return false;
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}
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/* Calculate the Merkle tree's root hash. */
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if (!avb_aftl_root_from_icp(icp_entry->leaf_index,
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icp_entry->log_root_descriptor.tree_size,
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icp_entry->proofs,
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icp_entry->proof_hash_count,
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leaf_hash,
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AVB_AFTL_HASH_SIZE,
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result_hash))
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return false;
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/* Return whether the calculated root hash matches the stored one. */
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return (avb_safe_memcmp(result_hash,
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icp_entry->log_root_descriptor.root_hash,
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AVB_AFTL_HASH_SIZE) == 0);
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}
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/* Verifies the log root signature for the transparency log submission. */
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bool avb_aftl_verify_entry_signature(const uint8_t* key,
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size_t key_num_bytes,
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AftlIcpEntry* icp_entry) {
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uint8_t* sig;
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size_t sig_num_bytes;
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uint8_t log_root_hash[AVB_AFTL_HASH_SIZE];
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size_t log_root_hash_num_bytes;
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const AvbAlgorithmData* algorithm_data;
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avb_assert(key != NULL && icp_entry != NULL);
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/* Extract the log root signature from the AftlIcpEntry. */
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sig = icp_entry->log_root_signature;
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if (sig == NULL) {
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avb_error("Invalid log root signature.\n");
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return false;
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}
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sig_num_bytes = icp_entry->log_root_sig_size;
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log_root_hash_num_bytes = AVB_AFTL_HASH_SIZE;
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/* Calculate the SHA256 of the TrillianLogRootDescriptor. */
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if (!avb_aftl_sha256(icp_entry->log_root_descriptor_raw,
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icp_entry->log_root_descriptor_size,
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log_root_hash))
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return false;
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/* algorithm_data is used to calculate the padding for signature verification.
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*/
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algorithm_data = avb_get_algorithm_data(AVB_ALGORITHM_TYPE_SHA256_RSA4096);
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if (algorithm_data == NULL) {
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avb_error("Failed to get algorithm data.\n");
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return false;
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}
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return avb_rsa_verify(key,
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key_num_bytes,
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sig,
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sig_num_bytes,
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log_root_hash,
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log_root_hash_num_bytes,
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algorithm_data->padding,
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algorithm_data->padding_len);
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}
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