payload_signer.cc revision c31e4a742b56c122b50febc1f78fd1c3772ab7fd 
1// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "update_engine/payload_generator/payload_signer.h"
6
7#include <base/logging.h>
8#include <base/strings/string_split.h>
9#include <base/strings/string_util.h>
10#include <chromeos/data_encoding.h>
11#include <openssl/pem.h>
12
13#include "update_engine/omaha_hash_calculator.h"
14#include "update_engine/payload_generator/delta_diff_generator.h"
15#include "update_engine/payload_verifier.h"
16#include "update_engine/subprocess.h"
17#include "update_engine/update_metadata.pb.h"
18#include "update_engine/utils.h"
19
20using std::string;
21using std::vector;
22
23namespace chromeos_update_engine {
24
25namespace {
26
27// Given raw |signatures|, packs them into a protobuf and serializes it into a
28// binary blob. Returns true on success, false otherwise.
29bool ConvertSignatureToProtobufBlob(const vector<chromeos::Blob>& signatures,
30                                    chromeos::Blob* out_signature_blob) {
31  // Pack it into a protobuf
32  Signatures out_message;
33  uint32_t version = kSignatureMessageOriginalVersion;
34  LOG_IF(WARNING, kSignatureMessageCurrentVersion -
35         kSignatureMessageOriginalVersion + 1 < signatures.size())
36      << "You may want to support clients in the range ["
37      << kSignatureMessageOriginalVersion << ", "
38      << kSignatureMessageCurrentVersion << "] inclusive, but you only "
39      << "provided " << signatures.size() << " signatures.";
40  for (const chromeos::Blob& signature : signatures) {
41    Signatures_Signature* sig_message = out_message.add_signatures();
42    sig_message->set_version(version++);
43    sig_message->set_data(signature.data(), signature.size());
44  }
45
46  // Serialize protobuf
47  string serialized;
48  TEST_AND_RETURN_FALSE(out_message.AppendToString(&serialized));
49  out_signature_blob->insert(out_signature_blob->end(),
50                             serialized.begin(),
51                             serialized.end());
52  LOG(INFO) << "Signature blob size: " << out_signature_blob->size();
53  return true;
54}
55
56// Given an unsigned payload under |payload_path| and the |signature_blob_size|
57// generates an updated payload that includes a dummy signature op in its
58// manifest. It populates |out_metadata_size| with the size of the final
59// manifest after adding the dummy signature operation, and
60// |out_signatures_offset| with the expected offset for the new blob. Returns
61// true on success, false otherwise.
62bool AddSignatureOpToPayload(const string& payload_path,
63                             uint64_t signature_blob_size,
64                             chromeos::Blob* out_payload,
65                             uint64_t* out_metadata_size,
66                             uint64_t* out_signatures_offset) {
67  const int kProtobufOffset = 20;
68  const int kProtobufSizeOffset = 12;
69
70  // Loads the payload.
71  chromeos::Blob payload;
72  DeltaArchiveManifest manifest;
73  uint64_t metadata_size;
74  TEST_AND_RETURN_FALSE(PayloadVerifier::LoadPayload(
75      payload_path, &payload, &manifest, &metadata_size));
76
77  // Is there already a signature op in place?
78  if (manifest.has_signatures_size()) {
79    // The signature op is tied to the size of the signature blob, but not it's
80    // contents. We don't allow the manifest to change if there is already an op
81    // present, because that might invalidate previously generated
82    // hashes/signatures.
83    if (manifest.signatures_size() != signature_blob_size) {
84      LOG(ERROR) << "Attempt to insert different signature sized blob. "
85                 << "(current:" << manifest.signatures_size()
86                 << "new:" << signature_blob_size << ")";
87      return false;
88    }
89
90    LOG(INFO) << "Matching signature sizes already present.";
91  } else {
92    // Updates the manifest to include the signature operation.
93    DeltaDiffGenerator::AddSignatureOp(payload.size() - metadata_size,
94                                       signature_blob_size,
95                                       &manifest);
96
97    // Updates the payload to include the new manifest.
98    string serialized_manifest;
99    TEST_AND_RETURN_FALSE(manifest.AppendToString(&serialized_manifest));
100    LOG(INFO) << "Updated protobuf size: " << serialized_manifest.size();
101    payload.erase(payload.begin() + kProtobufOffset,
102                  payload.begin() + metadata_size);
103    payload.insert(payload.begin() + kProtobufOffset,
104                   serialized_manifest.begin(),
105                   serialized_manifest.end());
106
107    // Updates the protobuf size.
108    uint64_t size_be = htobe64(serialized_manifest.size());
109    memcpy(&payload[kProtobufSizeOffset], &size_be, sizeof(size_be));
110    metadata_size = serialized_manifest.size() + kProtobufOffset;
111
112    LOG(INFO) << "Updated payload size: " << payload.size();
113    LOG(INFO) << "Updated metadata size: " << metadata_size;
114  }
115
116  out_payload->swap(payload);
117  *out_metadata_size = metadata_size;
118  *out_signatures_offset = metadata_size + manifest.signatures_offset();
119  LOG(INFO) << "Signature Blob Offset: " << *out_signatures_offset;
120  return true;
121}
122}  // namespace
123
124bool PayloadSigner::SignHash(const chromeos::Blob& hash,
125                             const string& private_key_path,
126                             chromeos::Blob* out_signature) {
127  LOG(INFO) << "Signing hash with private key: " << private_key_path;
128  string sig_path;
129  TEST_AND_RETURN_FALSE(
130      utils::MakeTempFile("signature.XXXXXX", &sig_path, nullptr));
131  ScopedPathUnlinker sig_path_unlinker(sig_path);
132
133  string hash_path;
134  TEST_AND_RETURN_FALSE(
135      utils::MakeTempFile("hash.XXXXXX", &hash_path, nullptr));
136  ScopedPathUnlinker hash_path_unlinker(hash_path);
137  // We expect unpadded SHA256 hash coming in
138  TEST_AND_RETURN_FALSE(hash.size() == 32);
139  chromeos::Blob padded_hash(hash);
140  PayloadVerifier::PadRSA2048SHA256Hash(&padded_hash);
141  TEST_AND_RETURN_FALSE(utils::WriteFile(hash_path.c_str(),
142                                         padded_hash.data(),
143                                         padded_hash.size()));
144
145  // This runs on the server, so it's okay to cop out and call openssl
146  // executable rather than properly use the library
147  vector<string> cmd;
148  base::SplitString("openssl rsautl -raw -sign -inkey x -in x -out x",
149                    ' ',
150                    &cmd);
151  cmd[cmd.size() - 5] = private_key_path;
152  cmd[cmd.size() - 3] = hash_path;
153  cmd[cmd.size() - 1] = sig_path;
154
155  int return_code = 0;
156  TEST_AND_RETURN_FALSE(Subprocess::SynchronousExec(cmd, &return_code,
157                                                    nullptr));
158  TEST_AND_RETURN_FALSE(return_code == 0);
159
160  chromeos::Blob signature;
161  TEST_AND_RETURN_FALSE(utils::ReadFile(sig_path, &signature));
162  out_signature->swap(signature);
163  return true;
164}
165
166bool PayloadSigner::SignPayload(const string& unsigned_payload_path,
167                                const vector<string>& private_key_paths,
168                                chromeos::Blob* out_signature_blob) {
169  chromeos::Blob hash_data;
170  TEST_AND_RETURN_FALSE(OmahaHashCalculator::RawHashOfFile(
171      unsigned_payload_path, -1, &hash_data) ==
172                        utils::FileSize(unsigned_payload_path));
173
174  vector<chromeos::Blob> signatures;
175  for (const string& path : private_key_paths) {
176    chromeos::Blob signature;
177    TEST_AND_RETURN_FALSE(SignHash(hash_data, path, &signature));
178    signatures.push_back(signature);
179  }
180  TEST_AND_RETURN_FALSE(ConvertSignatureToProtobufBlob(signatures,
181                                                       out_signature_blob));
182  return true;
183}
184
185bool PayloadSigner::SignatureBlobLength(const vector<string>& private_key_paths,
186                                        uint64_t* out_length) {
187  DCHECK(out_length);
188
189  string x_path;
190  TEST_AND_RETURN_FALSE(
191      utils::MakeTempFile("signed_data.XXXXXX", &x_path, nullptr));
192  ScopedPathUnlinker x_path_unlinker(x_path);
193  TEST_AND_RETURN_FALSE(utils::WriteFile(x_path.c_str(), "x", 1));
194
195  chromeos::Blob sig_blob;
196  TEST_AND_RETURN_FALSE(PayloadSigner::SignPayload(x_path,
197                                                   private_key_paths,
198                                                   &sig_blob));
199  *out_length = sig_blob.size();
200  return true;
201}
202
203bool PayloadSigner::PrepPayloadForHashing(
204        const string& payload_path,
205        const vector<int>& signature_sizes,
206        chromeos::Blob* payload_out,
207        uint64_t* metadata_size_out,
208        uint64_t* signatures_offset_out) {
209  // TODO(petkov): Reduce memory usage -- the payload is manipulated in memory.
210
211  // Loads the payload and adds the signature op to it.
212  vector<chromeos::Blob> signatures;
213  for (int signature_size : signature_sizes) {
214    signatures.emplace_back(signature_size, 0);
215  }
216  chromeos::Blob signature_blob;
217  TEST_AND_RETURN_FALSE(ConvertSignatureToProtobufBlob(signatures,
218                                                       &signature_blob));
219  TEST_AND_RETURN_FALSE(AddSignatureOpToPayload(payload_path,
220                                                signature_blob.size(),
221                                                payload_out,
222                                                metadata_size_out,
223                                                signatures_offset_out));
224
225  return true;
226}
227
228bool PayloadSigner::HashPayloadForSigning(const string& payload_path,
229                                          const vector<int>& signature_sizes,
230                                          chromeos::Blob* out_hash_data) {
231  chromeos::Blob payload;
232  uint64_t metadata_size;
233  uint64_t signatures_offset;
234
235  TEST_AND_RETURN_FALSE(PrepPayloadForHashing(payload_path,
236                                              signature_sizes,
237                                              &payload,
238                                              &metadata_size,
239                                              &signatures_offset));
240
241  // Calculates the hash on the updated payload. Note that we stop calculating
242  // before we reach the signature information.
243  TEST_AND_RETURN_FALSE(OmahaHashCalculator::RawHashOfBytes(payload.data(),
244                                                            signatures_offset,
245                                                            out_hash_data));
246  return true;
247}
248
249bool PayloadSigner::HashMetadataForSigning(const string& payload_path,
250                                           const vector<int>& signature_sizes,
251                                           chromeos::Blob* out_metadata_hash) {
252  chromeos::Blob payload;
253  uint64_t metadata_size;
254  uint64_t signatures_offset;
255
256  TEST_AND_RETURN_FALSE(PrepPayloadForHashing(payload_path,
257                                              signature_sizes,
258                                              &payload,
259                                              &metadata_size,
260                                              &signatures_offset));
261
262  // Calculates the hash on the manifest.
263  TEST_AND_RETURN_FALSE(OmahaHashCalculator::RawHashOfBytes(payload.data(),
264                                                            metadata_size,
265                                                            out_metadata_hash));
266  return true;
267}
268
269bool PayloadSigner::AddSignatureToPayload(
270    const string& payload_path,
271    const vector<chromeos::Blob>& signatures,
272    const string& signed_payload_path,
273    uint64_t *out_metadata_size) {
274  // TODO(petkov): Reduce memory usage -- the payload is manipulated in memory.
275
276  // Loads the payload and adds the signature op to it.
277  chromeos::Blob signature_blob;
278  TEST_AND_RETURN_FALSE(ConvertSignatureToProtobufBlob(signatures,
279                                                       &signature_blob));
280  chromeos::Blob payload;
281  uint64_t signatures_offset;
282  TEST_AND_RETURN_FALSE(AddSignatureOpToPayload(payload_path,
283                                                signature_blob.size(),
284                                                &payload,
285                                                out_metadata_size,
286                                                &signatures_offset));
287  // Appends the signature blob to the end of the payload and writes the new
288  // payload.
289  LOG(INFO) << "Payload size before signatures: " << payload.size();
290  payload.resize(signatures_offset);
291  payload.insert(payload.begin() + signatures_offset,
292                 signature_blob.begin(),
293                 signature_blob.end());
294  LOG(INFO) << "Signed payload size: " << payload.size();
295  TEST_AND_RETURN_FALSE(utils::WriteFile(signed_payload_path.c_str(),
296                                         payload.data(),
297                                         payload.size()));
298  return true;
299}
300
301bool PayloadSigner::GetMetadataSignature(const void* const metadata,
302                                         size_t metadata_size,
303                                         const string& private_key_path,
304                                         string* out_signature) {
305  // Calculates the hash on the updated payload. Note that the payload includes
306  // the signature op but doesn't include the signature blob at the end.
307  chromeos::Blob metadata_hash;
308  TEST_AND_RETURN_FALSE(OmahaHashCalculator::RawHashOfBytes(metadata,
309                                                            metadata_size,
310                                                            &metadata_hash));
311
312  chromeos::Blob signature;
313  TEST_AND_RETURN_FALSE(SignHash(metadata_hash,
314                                 private_key_path,
315                                 &signature));
316
317  *out_signature = chromeos::data_encoding::Base64Encode(signature);
318  return true;
319}
320
321
322}  // namespace chromeos_update_engine
323