1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except
6 * in compliance with the License. You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "adb/tls/tls_connection.h"
18
19 #include <limits.h>
20
21 #include <algorithm>
22 #include <vector>
23
24 #include <android-base/logging.h>
25 #include <android-base/strings.h>
26 #include <openssl/err.h>
27 #include <openssl/ssl.h>
28
29 using android::base::borrowed_fd;
30
31 namespace adb {
32 namespace tls {
33
34 namespace {
35
36 static constexpr char kExportedKeyLabel[] = "adb-label";
37
38 class TlsConnectionImpl : public TlsConnection {
39 public:
40 explicit TlsConnectionImpl(Role role, std::string_view cert, std::string_view priv_key,
41 borrowed_fd fd);
42 ~TlsConnectionImpl() override;
43
44 bool AddTrustedCertificate(std::string_view cert) override;
45 void SetCertVerifyCallback(CertVerifyCb cb) override;
46 void SetCertificateCallback(SetCertCb cb) override;
47 void SetClientCAList(STACK_OF(X509_NAME) * ca_list) override;
48 std::vector<uint8_t> ExportKeyingMaterial(size_t length) override;
49 void EnableClientPostHandshakeCheck(bool enable) override;
50 TlsError DoHandshake() override;
51 std::vector<uint8_t> ReadFully(size_t size) override;
52 bool ReadFully(void* buf, size_t size) override;
53 bool WriteFully(std::string_view data) override;
54
55 static bssl::UniquePtr<EVP_PKEY> EvpPkeyFromPEM(std::string_view pem);
56 static bssl::UniquePtr<CRYPTO_BUFFER> BufferFromPEM(std::string_view pem);
57
58 private:
59 static int SSLSetCertVerifyCb(X509_STORE_CTX* ctx, void* opaque);
60 static int SSLSetCertCb(SSL* ssl, void* opaque);
61
62 static bssl::UniquePtr<X509> X509FromBuffer(bssl::UniquePtr<CRYPTO_BUFFER> buffer);
63 static const char* SSLErrorString();
64 void Invalidate();
65 TlsError GetFailureReason(int err);
RoleToString()66 const char* RoleToString() { return role_ == Role::Server ? kServerRoleStr : kClientRoleStr; }
67
68 Role role_;
69 bssl::UniquePtr<EVP_PKEY> priv_key_;
70 bssl::UniquePtr<CRYPTO_BUFFER> cert_;
71
72 bssl::UniquePtr<STACK_OF(X509_NAME)> ca_list_;
73 bssl::UniquePtr<SSL_CTX> ssl_ctx_;
74 bssl::UniquePtr<SSL> ssl_;
75 std::vector<bssl::UniquePtr<X509>> known_certificates_;
76 bool client_verify_post_handshake_ = false;
77
78 CertVerifyCb cert_verify_cb_;
79 SetCertCb set_cert_cb_;
80 borrowed_fd fd_;
81 static constexpr char kClientRoleStr[] = "[client]: ";
82 static constexpr char kServerRoleStr[] = "[server]: ";
83 }; // TlsConnectionImpl
84
TlsConnectionImpl(Role role,std::string_view cert,std::string_view priv_key,borrowed_fd fd)85 TlsConnectionImpl::TlsConnectionImpl(Role role, std::string_view cert, std::string_view priv_key,
86 borrowed_fd fd)
87 : role_(role), fd_(fd) {
88 CHECK(!cert.empty() && !priv_key.empty());
89 LOG(INFO) << RoleToString() << "Initializing adbwifi TlsConnection";
90 cert_ = BufferFromPEM(cert);
91 CHECK(cert_);
92 priv_key_ = EvpPkeyFromPEM(priv_key);
93 CHECK(priv_key_);
94 }
95
~TlsConnectionImpl()96 TlsConnectionImpl::~TlsConnectionImpl() {
97 // shutdown the SSL connection
98 if (ssl_ != nullptr) {
99 SSL_shutdown(ssl_.get());
100 }
101 }
102
103 // static
SSLErrorString()104 const char* TlsConnectionImpl::SSLErrorString() {
105 auto sslerr = ERR_peek_last_error();
106 return ERR_reason_error_string(sslerr);
107 }
108
109 // static
EvpPkeyFromPEM(std::string_view pem)110 bssl::UniquePtr<EVP_PKEY> TlsConnectionImpl::EvpPkeyFromPEM(std::string_view pem) {
111 bssl::UniquePtr<BIO> bio(BIO_new_mem_buf(pem.data(), pem.size()));
112 return bssl::UniquePtr<EVP_PKEY>(PEM_read_bio_PrivateKey(bio.get(), nullptr, nullptr, nullptr));
113 }
114
115 // static
BufferFromPEM(std::string_view pem)116 bssl::UniquePtr<CRYPTO_BUFFER> TlsConnectionImpl::BufferFromPEM(std::string_view pem) {
117 bssl::UniquePtr<BIO> bio(BIO_new_mem_buf(pem.data(), pem.size()));
118 char* name = nullptr;
119 char* header = nullptr;
120 uint8_t* data = nullptr;
121 long data_len = 0;
122
123 if (!PEM_read_bio(bio.get(), &name, &header, &data, &data_len)) {
124 LOG(ERROR) << "Failed to read certificate";
125 return nullptr;
126 }
127 OPENSSL_free(name);
128 OPENSSL_free(header);
129
130 auto ret = bssl::UniquePtr<CRYPTO_BUFFER>(CRYPTO_BUFFER_new(data, data_len, nullptr));
131 OPENSSL_free(data);
132 return ret;
133 }
134
135 // static
X509FromBuffer(bssl::UniquePtr<CRYPTO_BUFFER> buffer)136 bssl::UniquePtr<X509> TlsConnectionImpl::X509FromBuffer(bssl::UniquePtr<CRYPTO_BUFFER> buffer) {
137 if (!buffer) {
138 return nullptr;
139 }
140 return bssl::UniquePtr<X509>(X509_parse_from_buffer(buffer.get()));
141 }
142
143 // static
SSLSetCertVerifyCb(X509_STORE_CTX * ctx,void * opaque)144 int TlsConnectionImpl::SSLSetCertVerifyCb(X509_STORE_CTX* ctx, void* opaque) {
145 auto* p = reinterpret_cast<TlsConnectionImpl*>(opaque);
146 return p->cert_verify_cb_(ctx);
147 }
148
149 // static
SSLSetCertCb(SSL * ssl,void * opaque)150 int TlsConnectionImpl::SSLSetCertCb(SSL* ssl, void* opaque) {
151 auto* p = reinterpret_cast<TlsConnectionImpl*>(opaque);
152 return p->set_cert_cb_(ssl);
153 }
154
AddTrustedCertificate(std::string_view cert)155 bool TlsConnectionImpl::AddTrustedCertificate(std::string_view cert) {
156 // Create X509 buffer from the certificate string
157 auto buf = X509FromBuffer(BufferFromPEM(cert));
158 if (buf == nullptr) {
159 LOG(ERROR) << RoleToString() << "Failed to create a X509 buffer for the certificate.";
160 return false;
161 }
162 known_certificates_.push_back(std::move(buf));
163 return true;
164 }
165
SetCertVerifyCallback(CertVerifyCb cb)166 void TlsConnectionImpl::SetCertVerifyCallback(CertVerifyCb cb) {
167 cert_verify_cb_ = cb;
168 }
169
SetCertificateCallback(SetCertCb cb)170 void TlsConnectionImpl::SetCertificateCallback(SetCertCb cb) {
171 set_cert_cb_ = cb;
172 }
173
SetClientCAList(STACK_OF (X509_NAME)* ca_list)174 void TlsConnectionImpl::SetClientCAList(STACK_OF(X509_NAME) * ca_list) {
175 CHECK(role_ == Role::Server);
176 ca_list_.reset(ca_list != nullptr ? SSL_dup_CA_list(ca_list) : nullptr);
177 }
178
ExportKeyingMaterial(size_t length)179 std::vector<uint8_t> TlsConnectionImpl::ExportKeyingMaterial(size_t length) {
180 if (ssl_.get() == nullptr) {
181 return {};
182 }
183
184 std::vector<uint8_t> out(length);
185 if (SSL_export_keying_material(ssl_.get(), out.data(), out.size(), kExportedKeyLabel,
186 sizeof(kExportedKeyLabel), nullptr, 0, false) == 0) {
187 return {};
188 }
189 return out;
190 }
191
EnableClientPostHandshakeCheck(bool enable)192 void TlsConnectionImpl::EnableClientPostHandshakeCheck(bool enable) {
193 client_verify_post_handshake_ = enable;
194 }
195
GetFailureReason(int err)196 TlsConnection::TlsError TlsConnectionImpl::GetFailureReason(int err) {
197 switch (ERR_GET_REASON(err)) {
198 case SSL_R_SSLV3_ALERT_BAD_CERTIFICATE:
199 case SSL_R_SSLV3_ALERT_UNSUPPORTED_CERTIFICATE:
200 case SSL_R_SSLV3_ALERT_CERTIFICATE_REVOKED:
201 case SSL_R_SSLV3_ALERT_CERTIFICATE_EXPIRED:
202 case SSL_R_SSLV3_ALERT_CERTIFICATE_UNKNOWN:
203 case SSL_R_TLSV1_ALERT_ACCESS_DENIED:
204 case SSL_R_TLSV1_ALERT_UNKNOWN_CA:
205 case SSL_R_TLSV1_CERTIFICATE_REQUIRED:
206 return TlsError::PeerRejectedCertificate;
207 case SSL_R_CERTIFICATE_VERIFY_FAILED:
208 return TlsError::CertificateRejected;
209 default:
210 return TlsError::UnknownFailure;
211 }
212 }
213
DoHandshake()214 TlsConnection::TlsError TlsConnectionImpl::DoHandshake() {
215 LOG(INFO) << RoleToString() << "Starting adbwifi tls handshake";
216 ssl_ctx_.reset(SSL_CTX_new(TLS_method()));
217 // TODO: Remove set_max_proto_version() once external/boringssl is updated
218 // past
219 // https://boringssl.googlesource.com/boringssl/+/58d56f4c59969a23e5f52014e2651c76fea2f877
220 if (ssl_ctx_.get() == nullptr ||
221 !SSL_CTX_set_min_proto_version(ssl_ctx_.get(), TLS1_3_VERSION) ||
222 !SSL_CTX_set_max_proto_version(ssl_ctx_.get(), TLS1_3_VERSION)) {
223 LOG(ERROR) << RoleToString() << "Failed to create SSL context";
224 return TlsError::UnknownFailure;
225 }
226
227 // Register user-supplied known certificates
228 for (auto const& cert : known_certificates_) {
229 if (X509_STORE_add_cert(SSL_CTX_get_cert_store(ssl_ctx_.get()), cert.get()) == 0) {
230 LOG(ERROR) << RoleToString() << "Unable to add certificates into the X509_STORE";
231 return TlsError::UnknownFailure;
232 }
233 }
234
235 // Custom certificate verification
236 if (cert_verify_cb_) {
237 SSL_CTX_set_cert_verify_callback(ssl_ctx_.get(), SSLSetCertVerifyCb, this);
238 }
239
240 // set select certificate callback, if any.
241 if (set_cert_cb_) {
242 SSL_CTX_set_cert_cb(ssl_ctx_.get(), SSLSetCertCb, this);
243 }
244
245 // Server-allowed client CA list
246 if (ca_list_ != nullptr) {
247 bssl::UniquePtr<STACK_OF(X509_NAME)> names(SSL_dup_CA_list(ca_list_.get()));
248 SSL_CTX_set_client_CA_list(ssl_ctx_.get(), names.release());
249 }
250
251 // Register our certificate and private key.
252 std::vector<CRYPTO_BUFFER*> cert_chain = {
253 cert_.get(),
254 };
255 if (!SSL_CTX_set_chain_and_key(ssl_ctx_.get(), cert_chain.data(), cert_chain.size(),
256 priv_key_.get(), nullptr)) {
257 LOG(ERROR) << RoleToString()
258 << "Unable to register the certificate chain file and private key ["
259 << SSLErrorString() << "]";
260 Invalidate();
261 return TlsError::UnknownFailure;
262 }
263
264 SSL_CTX_set_verify(ssl_ctx_.get(), SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, nullptr);
265
266 // Okay! Let's try to do the handshake!
267 ssl_.reset(SSL_new(ssl_ctx_.get()));
268 if (!SSL_set_fd(ssl_.get(), fd_.get())) {
269 LOG(ERROR) << RoleToString() << "SSL_set_fd failed. [" << SSLErrorString() << "]";
270 return TlsError::UnknownFailure;
271 }
272
273 switch (role_) {
274 case Role::Server:
275 SSL_set_accept_state(ssl_.get());
276 break;
277 case Role::Client:
278 SSL_set_connect_state(ssl_.get());
279 break;
280 }
281 if (SSL_do_handshake(ssl_.get()) != 1) {
282 LOG(ERROR) << RoleToString() << "Handshake failed in SSL_accept/SSL_connect ["
283 << SSLErrorString() << "]";
284 auto sslerr = ERR_get_error();
285 Invalidate();
286 return GetFailureReason(sslerr);
287 }
288
289 if (client_verify_post_handshake_ && role_ == Role::Client) {
290 uint8_t check;
291 // Try to peek one byte for any failures. This assumes on success that
292 // the server actually sends something.
293 if (SSL_peek(ssl_.get(), &check, 1) <= 0) {
294 LOG(ERROR) << RoleToString() << "Post-handshake SSL_peek failed [" << SSLErrorString()
295 << "]";
296 auto sslerr = ERR_get_error();
297 Invalidate();
298 return GetFailureReason(sslerr);
299 }
300 }
301
302 LOG(INFO) << RoleToString() << "Handshake succeeded.";
303 return TlsError::Success;
304 }
305
Invalidate()306 void TlsConnectionImpl::Invalidate() {
307 ssl_.reset();
308 ssl_ctx_.reset();
309 }
310
ReadFully(size_t size)311 std::vector<uint8_t> TlsConnectionImpl::ReadFully(size_t size) {
312 std::vector<uint8_t> buf(size);
313 if (!ReadFully(buf.data(), buf.size())) {
314 return {};
315 }
316
317 return buf;
318 }
319
ReadFully(void * buf,size_t size)320 bool TlsConnectionImpl::ReadFully(void* buf, size_t size) {
321 CHECK_GT(size, 0U);
322 if (!ssl_) {
323 LOG(ERROR) << RoleToString() << "Tried to read on a null SSL connection";
324 return false;
325 }
326
327 size_t offset = 0;
328 uint8_t* p8 = reinterpret_cast<uint8_t*>(buf);
329 while (size > 0) {
330 int bytes_read =
331 SSL_read(ssl_.get(), p8 + offset, std::min(static_cast<size_t>(INT_MAX), size));
332 if (bytes_read <= 0) {
333 LOG(ERROR) << RoleToString() << "SSL_read failed [" << SSLErrorString() << "]";
334 return false;
335 }
336 size -= bytes_read;
337 offset += bytes_read;
338 }
339 return true;
340 }
341
WriteFully(std::string_view data)342 bool TlsConnectionImpl::WriteFully(std::string_view data) {
343 CHECK(!data.empty());
344 if (!ssl_) {
345 LOG(ERROR) << RoleToString() << "Tried to read on a null SSL connection";
346 return false;
347 }
348
349 while (!data.empty()) {
350 int bytes_out = SSL_write(ssl_.get(), data.data(),
351 std::min(static_cast<size_t>(INT_MAX), data.size()));
352 if (bytes_out <= 0) {
353 LOG(ERROR) << RoleToString() << "SSL_write failed [" << SSLErrorString() << "]";
354 return false;
355 }
356 data = data.substr(bytes_out);
357 }
358 return true;
359 }
360 } // namespace
361
362 // static
Create(TlsConnection::Role role,std::string_view cert,std::string_view priv_key,borrowed_fd fd)363 std::unique_ptr<TlsConnection> TlsConnection::Create(TlsConnection::Role role,
364 std::string_view cert,
365 std::string_view priv_key, borrowed_fd fd) {
366 CHECK(!cert.empty());
367 CHECK(!priv_key.empty());
368
369 return std::make_unique<TlsConnectionImpl>(role, cert, priv_key, fd);
370 }
371
372 // static
SetCertAndKey(SSL * ssl,std::string_view cert,std::string_view priv_key)373 bool TlsConnection::SetCertAndKey(SSL* ssl, std::string_view cert, std::string_view priv_key) {
374 CHECK(ssl);
375 // Note: declaring these in local scope is okay because
376 // SSL_set_chain_and_key will increase the refcount (bssl::UpRef).
377 auto x509_cert = TlsConnectionImpl::BufferFromPEM(cert);
378 auto evp_pkey = TlsConnectionImpl::EvpPkeyFromPEM(priv_key);
379 if (x509_cert == nullptr || evp_pkey == nullptr) {
380 return false;
381 }
382
383 std::vector<CRYPTO_BUFFER*> cert_chain = {
384 x509_cert.get(),
385 };
386 if (!SSL_set_chain_and_key(ssl, cert_chain.data(), cert_chain.size(), evp_pkey.get(),
387 nullptr)) {
388 LOG(ERROR) << "SSL_set_chain_and_key failed";
389 return false;
390 }
391
392 return true;
393 }
394
395 } // namespace tls
396 } // namespace adb
397