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aosp12/system/update_engine/payload_generator/payload_signer.cc

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//
// Copyright (C) 2011 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 "update_engine/payload_generator/payload_signer.h"
#include <endian.h>
#include <memory>
#include <utility>
#include <base/logging.h>
#include <base/strings/string_number_conversions.h>
#include <base/strings/string_split.h>
#include <base/strings/string_util.h>
#include <brillo/data_encoding.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include "update_engine/common/constants.h"
#include "update_engine/common/hash_calculator.h"
#include "update_engine/common/subprocess.h"
#include "update_engine/common/utils.h"
#include "update_engine/payload_consumer/delta_performer.h"
#include "update_engine/payload_consumer/payload_constants.h"
#include "update_engine/payload_consumer/payload_metadata.h"
#include "update_engine/payload_consumer/payload_verifier.h"
#include "update_engine/payload_generator/delta_diff_generator.h"
#include "update_engine/payload_generator/payload_file.h"
#include "update_engine/update_metadata.pb.h"
using std::string;
using std::vector;
namespace chromeos_update_engine {
namespace {
// Given raw |signatures|, packs them into a protobuf and serializes it into a
// string. Returns true on success, false otherwise.
bool ConvertSignaturesToProtobuf(const vector<brillo::Blob>& signatures,
const vector<size_t>& padded_signature_sizes,
string* out_serialized_signature) {
TEST_AND_RETURN_FALSE(signatures.size() == padded_signature_sizes.size());
// Pack it into a protobuf
Signatures out_message;
for (size_t i = 0; i < signatures.size(); i++) {
const auto& signature = signatures[i];
const auto& padded_signature_size = padded_signature_sizes[i];
TEST_AND_RETURN_FALSE(padded_signature_size >= signature.size());
Signatures::Signature* sig_message = out_message.add_signatures();
// Skip assigning the same version number because we don't need to be
// compatible with old major version 1 client anymore.
// TODO(Xunchang) don't need to set the unpadded_signature_size field for
// RSA key signed signatures.
sig_message->set_unpadded_signature_size(signature.size());
brillo::Blob padded_signature = signature;
padded_signature.insert(
padded_signature.end(), padded_signature_size - signature.size(), 0);
sig_message->set_data(padded_signature.data(), padded_signature.size());
}
// Serialize protobuf
TEST_AND_RETURN_FALSE(
out_message.SerializeToString(out_serialized_signature));
LOG(INFO) << "Signature blob size: " << out_serialized_signature->size();
return true;
}
// Given an unsigned payload under |payload_path| and the |payload_signature|
// and |metadata_signature| generates an updated payload that includes the
// signatures. It populates |out_metadata_size| with the size of the final
// manifest after adding the fake signature operation, and
// |out_signatures_offset| with the expected offset for the new blob, and
// |out_metadata_signature_size| which will be size of |metadata_signature|
// if the payload major version supports metadata signature, 0 otherwise.
// Returns true on success, false otherwise.
bool AddSignatureBlobToPayload(const string& payload_path,
const string& payload_signature,
const string& metadata_signature,
brillo::Blob* out_payload,
uint64_t* out_metadata_size,
uint32_t* out_metadata_signature_size,
uint64_t* out_signatures_offset) {
uint64_t manifest_offset = 20;
const int kProtobufSizeOffset = 12;
brillo::Blob payload;
TEST_AND_RETURN_FALSE(utils::ReadFile(payload_path, &payload));
PayloadMetadata payload_metadata;
TEST_AND_RETURN_FALSE(payload_metadata.ParsePayloadHeader(payload));
uint64_t metadata_size = payload_metadata.GetMetadataSize();
uint32_t metadata_signature_size =
payload_metadata.GetMetadataSignatureSize();
// Write metadata signature size in header.
uint32_t metadata_signature_size_be = htobe32(metadata_signature.size());
memcpy(payload.data() + manifest_offset,
&metadata_signature_size_be,
sizeof(metadata_signature_size_be));
manifest_offset += sizeof(metadata_signature_size_be);
// Replace metadata signature.
payload.erase(payload.begin() + metadata_size,
payload.begin() + metadata_size + metadata_signature_size);
payload.insert(payload.begin() + metadata_size,
metadata_signature.begin(),
metadata_signature.end());
metadata_signature_size = metadata_signature.size();
LOG(INFO) << "Metadata signature size: " << metadata_signature_size;
DeltaArchiveManifest manifest;
TEST_AND_RETURN_FALSE(payload_metadata.GetManifest(payload, &manifest));
// Is there already a signature op in place?
if (manifest.has_signatures_size()) {
// The signature op is tied to the size of the signature blob, but not it's
// contents. We don't allow the manifest to change if there is already an op
// present, because that might invalidate previously generated
// hashes/signatures.
if (manifest.signatures_size() != payload_signature.size()) {
LOG(ERROR) << "Attempt to insert different signature sized blob. "
<< "(current:" << manifest.signatures_size()
<< "new:" << payload_signature.size() << ")";
return false;
}
LOG(INFO) << "Matching signature sizes already present.";
} else {
// Updates the manifest to include the signature operation.
PayloadSigner::AddSignatureToManifest(
payload.size() - metadata_size - metadata_signature_size,
payload_signature.size(),
&manifest);
// Updates the payload to include the new manifest.
string serialized_manifest;
TEST_AND_RETURN_FALSE(manifest.AppendToString(&serialized_manifest));
LOG(INFO) << "Updated protobuf size: " << serialized_manifest.size();
payload.erase(payload.begin() + manifest_offset,
payload.begin() + metadata_size);
payload.insert(payload.begin() + manifest_offset,
serialized_manifest.begin(),
serialized_manifest.end());
// Updates the protobuf size.
uint64_t size_be = htobe64(serialized_manifest.size());
memcpy(&payload[kProtobufSizeOffset], &size_be, sizeof(size_be));
metadata_size = serialized_manifest.size() + manifest_offset;
LOG(INFO) << "Updated payload size: " << payload.size();
LOG(INFO) << "Updated metadata size: " << metadata_size;
}
uint64_t signatures_offset =
metadata_size + metadata_signature_size + manifest.signatures_offset();
LOG(INFO) << "Signature Blob Offset: " << signatures_offset;
payload.resize(signatures_offset);
payload.insert(payload.begin() + signatures_offset,
payload_signature.begin(),
payload_signature.end());
*out_payload = std::move(payload);
*out_metadata_size = metadata_size;
*out_metadata_signature_size = metadata_signature_size;
*out_signatures_offset = signatures_offset;
return true;
}
// Given a |payload| with correct signature op and metadata signature size in
// header and |metadata_size|, |metadata_signature_size|, |signatures_offset|,
// calculate hash for payload and metadata, save it to |out_hash_data| and
// |out_metadata_hash|.
bool CalculateHashFromPayload(const brillo::Blob& payload,
const uint64_t metadata_size,
const uint32_t metadata_signature_size,
const uint64_t signatures_offset,
brillo::Blob* out_hash_data,
brillo::Blob* out_metadata_hash) {
if (out_metadata_hash) {
// Calculates the hash on the manifest.
TEST_AND_RETURN_FALSE(HashCalculator::RawHashOfBytes(
payload.data(), metadata_size, out_metadata_hash));
}
if (out_hash_data) {
// Calculates the hash on the updated payload. Note that we skip metadata
// signature and payload signature.
HashCalculator calc;
TEST_AND_RETURN_FALSE(calc.Update(payload.data(), metadata_size));
TEST_AND_RETURN_FALSE(signatures_offset >=
metadata_size + metadata_signature_size);
TEST_AND_RETURN_FALSE(calc.Update(
payload.data() + metadata_size + metadata_signature_size,
signatures_offset - metadata_size - metadata_signature_size));
TEST_AND_RETURN_FALSE(calc.Finalize());
*out_hash_data = calc.raw_hash();
}
return true;
}
std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)> CreatePrivateKeyFromPath(
const string& private_key_path) {
FILE* fprikey = fopen(private_key_path.c_str(), "rb");
if (!fprikey) {
PLOG(ERROR) << "Failed to read " << private_key_path;
return {nullptr, nullptr};
}
auto private_key = std::unique_ptr<EVP_PKEY, decltype(&EVP_PKEY_free)>(
PEM_read_PrivateKey(fprikey, nullptr, nullptr, nullptr), EVP_PKEY_free);
fclose(fprikey);
return private_key;
}
} // namespace
bool PayloadSigner::GetMaximumSignatureSize(const string& private_key_path,
size_t* signature_size) {
*signature_size = 0;
auto private_key = CreatePrivateKeyFromPath(private_key_path);
if (!private_key) {
LOG(ERROR) << "Failed to create private key from " << private_key_path;
return false;
}
*signature_size = EVP_PKEY_size(private_key.get());
return true;
}
void PayloadSigner::AddSignatureToManifest(uint64_t signature_blob_offset,
uint64_t signature_blob_length,
DeltaArchiveManifest* manifest) {
LOG(INFO) << "Making room for signature in file";
manifest->set_signatures_offset(signature_blob_offset);
manifest->set_signatures_size(signature_blob_length);
}
bool PayloadSigner::VerifySignedPayload(const string& payload_path,
const string& public_key_path) {
brillo::Blob payload;
TEST_AND_RETURN_FALSE(utils::ReadFile(payload_path, &payload));
PayloadMetadata payload_metadata;
TEST_AND_RETURN_FALSE(payload_metadata.ParsePayloadHeader(payload));
DeltaArchiveManifest manifest;
TEST_AND_RETURN_FALSE(payload_metadata.GetManifest(payload, &manifest));
TEST_AND_RETURN_FALSE(manifest.has_signatures_offset() &&
manifest.has_signatures_size());
uint64_t metadata_size = payload_metadata.GetMetadataSize();
uint32_t metadata_signature_size =
payload_metadata.GetMetadataSignatureSize();
uint64_t signatures_offset =
metadata_size + metadata_signature_size + manifest.signatures_offset();
CHECK_EQ(payload.size(), signatures_offset + manifest.signatures_size());
brillo::Blob payload_hash, metadata_hash;
TEST_AND_RETURN_FALSE(CalculateHashFromPayload(payload,
metadata_size,
metadata_signature_size,
signatures_offset,
&payload_hash,
&metadata_hash));
string signature(payload.begin() + signatures_offset, payload.end());
string public_key;
TEST_AND_RETURN_FALSE(utils::ReadFile(public_key_path, &public_key));
TEST_AND_RETURN_FALSE(payload_hash.size() == kSHA256Size);
auto payload_verifier = PayloadVerifier::CreateInstance(public_key);
TEST_AND_RETURN_FALSE(payload_verifier != nullptr);
TEST_AND_RETURN_FALSE(
payload_verifier->VerifySignature(signature, payload_hash));
if (metadata_signature_size) {
signature.assign(payload.begin() + metadata_size,
payload.begin() + metadata_size + metadata_signature_size);
TEST_AND_RETURN_FALSE(metadata_hash.size() == kSHA256Size);
TEST_AND_RETURN_FALSE(
payload_verifier->VerifySignature(signature, metadata_hash));
}
return true;
}
bool PayloadSigner::SignHash(const brillo::Blob& hash,
const string& private_key_path,
brillo::Blob* out_signature) {
LOG(INFO) << "Signing hash with private key: " << private_key_path;
// We expect unpadded SHA256 hash coming in
TEST_AND_RETURN_FALSE(hash.size() == kSHA256Size);
// The code below executes the equivalent of:
//
// openssl rsautl -raw -sign -inkey |private_key_path|
// -in |padded_hash| -out |out_signature|
auto private_key = CreatePrivateKeyFromPath(private_key_path);
if (!private_key) {
LOG(ERROR) << "Failed to create private key from " << private_key_path;
return false;
}
int key_type = EVP_PKEY_id(private_key.get());
brillo::Blob signature;
if (key_type == EVP_PKEY_RSA) {
RSA* rsa = EVP_PKEY_get0_RSA(private_key.get());
TEST_AND_RETURN_FALSE(rsa != nullptr);
brillo::Blob padded_hash = hash;
PayloadVerifier::PadRSASHA256Hash(&padded_hash, RSA_size(rsa));
signature.resize(RSA_size(rsa));
ssize_t signature_size = RSA_private_encrypt(padded_hash.size(),
padded_hash.data(),
signature.data(),
rsa,
RSA_NO_PADDING);
if (signature_size < 0) {
LOG(ERROR) << "Signing hash failed: "
<< ERR_error_string(ERR_get_error(), nullptr);
return false;
}
TEST_AND_RETURN_FALSE(static_cast<size_t>(signature_size) ==
signature.size());
} else if (key_type == EVP_PKEY_EC) {
EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(private_key.get());
TEST_AND_RETURN_FALSE(ec_key != nullptr);
signature.resize(ECDSA_size(ec_key));
unsigned int signature_size;
if (ECDSA_sign(0,
hash.data(),
hash.size(),
signature.data(),
&signature_size,
ec_key) != 1) {
LOG(ERROR) << "Signing hash failed: "
<< ERR_error_string(ERR_get_error(), nullptr);
return false;
}
// NIST P-256
LOG(ERROR) << "signature max size " << signature.size() << " size "
<< signature_size;
TEST_AND_RETURN_FALSE(signature.size() >= signature_size);
signature.resize(signature_size);
} else {
LOG(ERROR) << "key_type " << key_type << " isn't supported for signing";
return false;
}
out_signature->swap(signature);
return true;
}
bool PayloadSigner::SignHashWithKeys(const brillo::Blob& hash_data,
const vector<string>& private_key_paths,
string* out_serialized_signature) {
vector<brillo::Blob> signatures;
vector<size_t> padded_signature_sizes;
for (const string& path : private_key_paths) {
brillo::Blob signature;
TEST_AND_RETURN_FALSE(SignHash(hash_data, path, &signature));
signatures.push_back(signature);
size_t padded_signature_size;
TEST_AND_RETURN_FALSE(
GetMaximumSignatureSize(path, &padded_signature_size));
padded_signature_sizes.push_back(padded_signature_size);
}
TEST_AND_RETURN_FALSE(ConvertSignaturesToProtobuf(
signatures, padded_signature_sizes, out_serialized_signature));
return true;
}
bool PayloadSigner::SignPayload(const string& unsigned_payload_path,
const vector<string>& private_key_paths,
const uint64_t metadata_size,
const uint32_t metadata_signature_size,
const uint64_t signatures_offset,
string* out_serialized_signature) {
brillo::Blob payload;
TEST_AND_RETURN_FALSE(utils::ReadFile(unsigned_payload_path, &payload));
brillo::Blob hash_data;
TEST_AND_RETURN_FALSE(CalculateHashFromPayload(payload,
metadata_size,
metadata_signature_size,
signatures_offset,
&hash_data,
nullptr));
TEST_AND_RETURN_FALSE(
SignHashWithKeys(hash_data, private_key_paths, out_serialized_signature));
return true;
}
bool PayloadSigner::SignatureBlobLength(const vector<string>& private_key_paths,
uint64_t* out_length) {
DCHECK(out_length);
brillo::Blob hash_blob;
TEST_AND_RETURN_FALSE(HashCalculator::RawHashOfData({'x'}, &hash_blob));
string sig_blob;
TEST_AND_RETURN_FALSE(
SignHashWithKeys(hash_blob, private_key_paths, &sig_blob));
*out_length = sig_blob.size();
return true;
}
bool PayloadSigner::HashPayloadForSigning(const string& payload_path,
const vector<size_t>& signature_sizes,
brillo::Blob* out_payload_hash_data,
brillo::Blob* out_metadata_hash) {
// Create a signature blob with signatures filled with 0.
// Will be used for both payload signature and metadata signature.
vector<brillo::Blob> signatures;
for (int signature_size : signature_sizes) {
signatures.emplace_back(signature_size, 0);
}
string signature;
TEST_AND_RETURN_FALSE(
ConvertSignaturesToProtobuf(signatures, signature_sizes, &signature));
brillo::Blob payload;
uint64_t metadata_size, signatures_offset;
uint32_t metadata_signature_size;
// Prepare payload for hashing.
TEST_AND_RETURN_FALSE(AddSignatureBlobToPayload(payload_path,
signature,
signature,
&payload,
&metadata_size,
&metadata_signature_size,
&signatures_offset));
TEST_AND_RETURN_FALSE(CalculateHashFromPayload(payload,
metadata_size,
metadata_signature_size,
signatures_offset,
out_payload_hash_data,
out_metadata_hash));
return true;
}
bool PayloadSigner::AddSignatureToPayload(
const string& payload_path,
const vector<size_t>& padded_signature_sizes,
const vector<brillo::Blob>& payload_signatures,
const vector<brillo::Blob>& metadata_signatures,
const string& signed_payload_path,
uint64_t* out_metadata_size) {
// TODO(petkov): Reduce memory usage -- the payload is manipulated in memory.
// Loads the payload and adds the signature op to it.
string payload_signature, metadata_signature;
TEST_AND_RETURN_FALSE(ConvertSignaturesToProtobuf(
payload_signatures, padded_signature_sizes, &payload_signature));
if (!metadata_signatures.empty()) {
TEST_AND_RETURN_FALSE(ConvertSignaturesToProtobuf(
metadata_signatures, padded_signature_sizes, &metadata_signature));
}
brillo::Blob payload;
uint64_t signatures_offset;
uint32_t metadata_signature_size;
TEST_AND_RETURN_FALSE(AddSignatureBlobToPayload(payload_path,
payload_signature,
metadata_signature,
&payload,
out_metadata_size,
&metadata_signature_size,
&signatures_offset));
LOG(INFO) << "Signed payload size: " << payload.size();
TEST_AND_RETURN_FALSE(utils::WriteFile(
signed_payload_path.c_str(), payload.data(), payload.size()));
return true;
}
bool PayloadSigner::GetMetadataSignature(const void* const metadata,
size_t metadata_size,
const string& private_key_path,
string* out_signature) {
// Calculates the hash on the updated payload. Note that the payload includes
// the signature op but doesn't include the signature blob at the end.
brillo::Blob metadata_hash;
TEST_AND_RETURN_FALSE(
HashCalculator::RawHashOfBytes(metadata, metadata_size, &metadata_hash));
brillo::Blob signature;
TEST_AND_RETURN_FALSE(SignHash(metadata_hash, private_key_path, &signature));
*out_signature = brillo::data_encoding::Base64Encode(signature);
return true;
}
} // namespace chromeos_update_engine
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