5230455705

Committed 10 Jun 2023 02:30PM UTC coverage: 91.715% (-0.03%) from 91.746%

Build # 5230455705

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randombit

Commit Message

Merge GH #3584 Change clang-format AllowShortFunctionsOnASingleLine config from All to Inline

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97.83

/src/lib/tls/tls13/tls_transcript_hash_13.cpp

/*
* TLS transcript hash implementation for TLS 1.3
* (C) 2022 Jack Lloyd
*     2022 Hannes Rantzsch, René Meusel - neXenio GmbH
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/tls_transcript_hash_13.h>

#include <botan/tls_exceptn.h>
#include <botan/tls_messages.h>
#include <botan/internal/tls_reader.h>

#include <utility>

namespace Botan::TLS {

Transcript_Hash_State::Transcript_Hash_State(std::string_view algo_spec) {
   set_algorithm(algo_spec);
}

Transcript_Hash_State::Transcript_Hash_State(const Transcript_Hash_State& other) :
      m_hash((other.m_hash != nullptr) ? other.m_hash->copy_state() : nullptr),
      m_unprocessed_transcript(other.m_unprocessed_transcript),
      m_current(other.m_current),
      m_previous(other.m_previous),
      m_truncated(other.m_truncated) {}

Transcript_Hash_State Transcript_Hash_State::recreate_after_hello_retry_request(
   std::string_view algo_spec, const Transcript_Hash_State& prev_transcript_hash_state) {
   // make sure that we have seen exactly 'client_hello' and 'hello_retry_request'
   // before re-creating the transcript hash state
   BOTAN_STATE_CHECK(prev_transcript_hash_state.m_hash == nullptr);
   BOTAN_STATE_CHECK(prev_transcript_hash_state.m_unprocessed_transcript.size() == 2);

   Transcript_Hash_State ths(algo_spec);

   const auto& client_hello_1 = prev_transcript_hash_state.m_unprocessed_transcript.front();
   const auto& hello_retry_request = prev_transcript_hash_state.m_unprocessed_transcript.back();

   const size_t hash_length = ths.m_hash->output_length();
   BOTAN_ASSERT_NOMSG(hash_length < 256);

   // RFC 8446 4.4.1
   //    [...], when the server responds to a ClientHello with a HelloRetryRequest,
   //    the value of ClientHello1 is replaced with a special synthetic handshake
   //    message of handshake type "message_hash" [(0xFE)] containing:
   std::vector<uint8_t> message_hash;
   message_hash.reserve(4 + hash_length);
   message_hash.push_back(0xFE /* message type 'message_hash' RFC 8446 4. */);
   message_hash.push_back(0x00);
   message_hash.push_back(0x00);
   message_hash.push_back(static_cast<uint8_t>(hash_length));
   message_hash += ths.m_hash->process(client_hello_1);

   ths.update(message_hash);
   ths.update(hello_retry_request);

   return ths;
}

namespace {

// TODO: This is a massive code duplication of the client hello parsing code,
//       as well as basic parsing of extensions. We should resolve this.
//
// Ad-hoc idea: When parsing the production objects, we could keep markers into
//              the original buffer. E.g. the PSK extensions would keep its off-
//              set into the entire client hello buffer. Using that offset we
//              could quickly identify the offset of the binders list slice the
//              buffer without re-parsing it.
//
// Finds the truncation offset in a serialization of Client Hello as defined in
// RFC 8446 4.2.11.2 used for the calculation of PSK binder MACs.
size_t find_client_hello_truncation_mark(std::span<const uint8_t> client_hello) {
   TLS_Data_Reader reader("Client Hello Truncation", client_hello);

   // handshake message type
   BOTAN_ASSERT_NOMSG(reader.get_byte() == static_cast<uint8_t>(Handshake_Type::ClientHello));

   // message length
   reader.discard_next(3);

   // legacy version
   reader.discard_next(2);

   // random
   reader.discard_next(32);

   // session ID
   const auto session_id_length = reader.get_byte();
   reader.discard_next(session_id_length);

   // TODO: DTLS contains a hello_cookie in this location
   //       Currently we don't support DTLS 1.3

   // cipher suites
   const auto ciphersuites_length = reader.get_uint16_t();
   reader.discard_next(ciphersuites_length);

   // compression methods
   const auto compression_methods_length = reader.get_byte();
   reader.discard_next(compression_methods_length);

   // extensions
   const auto extensions_length = reader.get_uint16_t();
   const auto extensions_offset = reader.read_so_far();
   while(reader.has_remaining() && reader.read_so_far() - extensions_offset < extensions_length) {
      const auto ext_type = static_cast<Extension_Code>(reader.get_uint16_t());
      const auto ext_length = reader.get_uint16_t();

      // skip over all extensions, finding the PSK extension to be truncated
      if(ext_type != Extension_Code::PresharedKey) {
         reader.discard_next(ext_length);
         continue;
      }

      // PSK identities list
      const auto identities_length = reader.get_uint16_t();
      reader.discard_next(identities_length);

      // check that only the binders are left in the buffer...
      const auto binders_length = reader.peek_uint16_t();
      if(binders_length != reader.remaining_bytes() - 2 /* binders_length */) {
         throw TLS_Exception(Alert::IllegalParameter,
                             "Failed to truncate Client Hello that doesn't end on the PSK binders list");
      }

      // the reader now points to the truncation point
      break;
   }

   // if no PSK extension was found, this will point to the end of the buffer
   return reader.read_so_far();
}

std::vector<uint8_t> read_hash_state(std::unique_ptr<HashFunction>& hash) {
   // Botan does not support finalizing a HashFunction without resetting
   // the internal state of the hash. Hence we first copy the internal
   // state and then finalize the transient HashFunction.
   return hash->copy_state()->final_stdvec();
}

}  // namespace

void Transcript_Hash_State::update(std::span<const uint8_t> serialized_message_s) {
   auto serialized_message = serialized_message_s.data();
   auto serialized_message_length = serialized_message_s.size();
   if(m_hash != nullptr) {
      auto truncation_mark = serialized_message_length;

      // Check whether we should generate a truncated hash for supporting PSK
      // binder calculation or verification. See RFC 8446 4.2.11.2.
      if(serialized_message_length > 0 && *serialized_message == static_cast<uint8_t>(Handshake_Type::ClientHello)) {
         truncation_mark = find_client_hello_truncation_mark(serialized_message_s);
      }

      if(truncation_mark < serialized_message_length) {
         m_hash->update(serialized_message, truncation_mark);
         m_truncated = read_hash_state(m_hash);
         m_hash->update(serialized_message + truncation_mark, serialized_message_length - truncation_mark);
      } else {
         m_truncated.clear();
         m_hash->update(serialized_message, serialized_message_length);
      }

      m_previous = std::exchange(m_current, read_hash_state(m_hash));
   } else {
      m_unprocessed_transcript.push_back(
         std::vector(serialized_message, serialized_message + serialized_message_length));
   }
}

const Transcript_Hash& Transcript_Hash_State::current() const {
   BOTAN_STATE_CHECK(!m_current.empty());
   return m_current;
}

const Transcript_Hash& Transcript_Hash_State::previous() const {
   BOTAN_STATE_CHECK(!m_previous.empty());
   return m_previous;
}

const Transcript_Hash& Transcript_Hash_State::truncated() const {
   BOTAN_STATE_CHECK(!m_truncated.empty());
   return m_truncated;
}

void Transcript_Hash_State::set_algorithm(std::string_view algo_spec) {
   BOTAN_STATE_CHECK(m_hash == nullptr || m_hash->name() == algo_spec);
   if(m_hash != nullptr) {
      return;
   }

   m_hash = HashFunction::create_or_throw(algo_spec);
   for(const auto& msg : m_unprocessed_transcript) {
      update(msg);
   }
   m_unprocessed_transcript.clear();
}

Transcript_Hash_State Transcript_Hash_State::clone() const {
   return *this;
}

}  // namespace Botan::TLS

1	/*
2	* TLS transcript hash implementation for TLS 1.3
3	* (C) 2022 Jack Lloyd
4	* 2022 Hannes Rantzsch, René Meusel - neXenio GmbH
5	*
6	* Botan is released under the Simplified BSD License (see license.txt)
7	*/
8
9	#include <botan/internal/tls_transcript_hash_13.h>
10
11	#include <botan/tls_exceptn.h>
12	#include <botan/tls_messages.h>
13	#include <botan/internal/tls_reader.h>
14
15	#include <utility>
16
17	namespace Botan::TLS {
18
19	Transcript_Hash_State::Transcript_Hash_State(std::string_view algo_spec) {	132✔
20	set_algorithm(algo_spec);	132✔
21	}	132✔
22
23	Transcript_Hash_State::Transcript_Hash_State(const Transcript_Hash_State& other) :	102✔
24	m_hash((other.m_hash != nullptr) ? other.m_hash->copy_state() : nullptr),	102✔
25	m_unprocessed_transcript(other.m_unprocessed_transcript),	102✔
26	m_current(other.m_current),	102✔
27	m_previous(other.m_previous),	102✔
28	m_truncated(other.m_truncated) {}	102✔
29
30	Transcript_Hash_State Transcript_Hash_State::recreate_after_hello_retry_request(	71✔
31	std::string_view algo_spec, const Transcript_Hash_State& prev_transcript_hash_state) {
32	// make sure that we have seen exactly 'client_hello' and 'hello_retry_request'
33	// before re-creating the transcript hash state
34	BOTAN_STATE_CHECK(prev_transcript_hash_state.m_hash == nullptr);	71✔
35	BOTAN_STATE_CHECK(prev_transcript_hash_state.m_unprocessed_transcript.size() == 2);	71✔
36
37	Transcript_Hash_State ths(algo_spec);	71✔
38
39	const auto& client_hello_1 = prev_transcript_hash_state.m_unprocessed_transcript.front();	71✔
40	const auto& hello_retry_request = prev_transcript_hash_state.m_unprocessed_transcript.back();	71✔
41
42	const size_t hash_length = ths.m_hash->output_length();	71✔
43	BOTAN_ASSERT_NOMSG(hash_length < 256);	71✔
44
45	// RFC 8446 4.4.1
46	// [...], when the server responds to a ClientHello with a HelloRetryRequest,
47	// the value of ClientHello1 is replaced with a special synthetic handshake
48	// message of handshake type "message_hash" [(0xFE)] containing:
49	std::vector<uint8_t> message_hash;	71✔
50	message_hash.reserve(4 + hash_length);	71✔
51	message_hash.push_back(0xFE /* message type 'message_hash' RFC 8446 4. */);	71✔
52	message_hash.push_back(0x00);	71✔
53	message_hash.push_back(0x00);	71✔
54	message_hash.push_back(static_cast<uint8_t>(hash_length));	71✔
55	message_hash += ths.m_hash->process(client_hello_1);	142✔
56
57	ths.update(message_hash);	71✔
58	ths.update(hello_retry_request);	71✔
59
60	return ths;	71✔
61	}	71✔
62
63	namespace {
64
65	// TODO: This is a massive code duplication of the client hello parsing code,
66	// as well as basic parsing of extensions. We should resolve this.
67	//
68	// Ad-hoc idea: When parsing the production objects, we could keep markers into
69	// the original buffer. E.g. the PSK extensions would keep its off-
70	// set into the entire client hello buffer. Using that offset we
71	// could quickly identify the offset of the binders list slice the
72	// buffer without re-parsing it.
73	//
74	// Finds the truncation offset in a serialization of Client Hello as defined in
75	// RFC 8446 4.2.11.2 used for the calculation of PSK binder MACs.
76	size_t find_client_hello_truncation_mark(std::span<const uint8_t> client_hello) {	888✔
77	TLS_Data_Reader reader("Client Hello Truncation", client_hello);	888✔
78
79	// handshake message type
80	BOTAN_ASSERT_NOMSG(reader.get_byte() == static_cast<uint8_t>(Handshake_Type::ClientHello));	888✔
81
82	// message length
83	reader.discard_next(3);	888✔
84
85	// legacy version
86	reader.discard_next(2);	888✔
87
88	// random
89	reader.discard_next(32);	888✔
90
91	// session ID
92	const auto session_id_length = reader.get_byte();	888✔
93	reader.discard_next(session_id_length);	888✔
94
95	// TODO: DTLS contains a hello_cookie in this location
96	// Currently we don't support DTLS 1.3
97
98	// cipher suites
99	const auto ciphersuites_length = reader.get_uint16_t();	888✔
100	reader.discard_next(ciphersuites_length);	888✔
101
102	// compression methods
103	const auto compression_methods_length = reader.get_byte();	888✔
104	reader.discard_next(compression_methods_length);	888✔
105
106	// extensions
107	const auto extensions_length = reader.get_uint16_t();	888✔
108	const auto extensions_offset = reader.read_so_far();	888✔
109	while(reader.has_remaining() && reader.read_so_far() - extensions_offset < extensions_length) {	11,243✔
110	const auto ext_type = static_cast<Extension_Code>(reader.get_uint16_t());	10,622✔
111	const auto ext_length = reader.get_uint16_t();	10,622✔
112
113	// skip over all extensions, finding the PSK extension to be truncated
114	if(ext_type != Extension_Code::PresharedKey) {	10,622✔
115	reader.discard_next(ext_length);	10,355✔
116	continue;	10,355✔
117	}
118
119	// PSK identities list
120	const auto identities_length = reader.get_uint16_t();	267✔
121	reader.discard_next(identities_length);	267✔
122
123	// check that only the binders are left in the buffer...
124	const auto binders_length = reader.peek_uint16_t();	267✔
125	if(binders_length != reader.remaining_bytes() - 2 /* binders_length */) {	267✔
126	throw TLS_Exception(Alert::IllegalParameter,	×
127	"Failed to truncate Client Hello that doesn't end on the PSK binders list");	×
128	}
129
130	// the reader now points to the truncation point
131	break;
132	}
133
134	// if no PSK extension was found, this will point to the end of the buffer
135	return reader.read_so_far();	888✔
136	}
137
138	std::vector<uint8_t> read_hash_state(std::unique_ptr<HashFunction>& hash) {	5,572✔
139	// Botan does not support finalizing a HashFunction without resetting
140	// the internal state of the hash. Hence we first copy the internal
141	// state and then finalize the transient HashFunction.
142	return hash->copy_state()->final_stdvec();	11,144✔
143	}
144
145	} // namespace
146
147	void Transcript_Hash_State::update(std::span<const uint8_t> serialized_message_s) {	8,163✔
148	auto serialized_message = serialized_message_s.data();	8,163✔
149	auto serialized_message_length = serialized_message_s.size();	8,163✔
150	if(m_hash != nullptr) {	8,163✔
151	auto truncation_mark = serialized_message_length;	5,305✔
152
153	// Check whether we should generate a truncated hash for supporting PSK
154	// binder calculation or verification. See RFC 8446 4.2.11.2.
155	if(serialized_message_length > 0 && *serialized_message == static_cast<uint8_t>(Handshake_Type::ClientHello)) {	5,305✔
156	truncation_mark = find_client_hello_truncation_mark(serialized_message_s);	888✔
157	}
158
159	if(truncation_mark < serialized_message_length) {	5,305✔
160	m_hash->update(serialized_message, truncation_mark);	267✔
161	m_truncated = read_hash_state(m_hash);	267✔
162	m_hash->update(serialized_message + truncation_mark, serialized_message_length - truncation_mark);	267✔
163	} else {
164	m_truncated.clear();	5,038✔
165	m_hash->update(serialized_message, serialized_message_length);	5,038✔
166	}
167
168	m_previous = std::exchange(m_current, read_hash_state(m_hash));	5,305✔
169	} else {
170	m_unprocessed_transcript.push_back(	5,716✔
171	std::vector(serialized_message, serialized_message + serialized_message_length));	5,716✔
172	}
173	}	8,163✔
174
175	const Transcript_Hash& Transcript_Hash_State::current() const {	2,943✔
176	BOTAN_STATE_CHECK(!m_current.empty());	2,943✔
177	return m_current;	2,930✔
178	}
179
180	const Transcript_Hash& Transcript_Hash_State::previous() const {	1,077✔
181	BOTAN_STATE_CHECK(!m_previous.empty());	1,077✔
182	return m_previous;	1,073✔
183	}
184
185	const Transcript_Hash& Transcript_Hash_State::truncated() const {	188✔
186	BOTAN_STATE_CHECK(!m_truncated.empty());	188✔
187	return m_truncated;	187✔
188	}
189
190	void Transcript_Hash_State::set_algorithm(std::string_view algo_spec) {	1,009✔
191	BOTAN_STATE_CHECK(m_hash == nullptr \|\| m_hash->name() == algo_spec);	1,139✔
192	if(m_hash != nullptr) {	1,007✔
193	return;
194	}
195
196	m_hash = HashFunction::create_or_throw(algo_spec);	944✔
197	for(const auto& msg : m_unprocessed_transcript) {	2,153✔
198	update(msg);	1,209✔
199	}
200	m_unprocessed_transcript.clear();	944✔
201	}
202
203	Transcript_Hash_State Transcript_Hash_State::clone() const {	102✔
204	return *this;	102✔
205	}
206
207	} // namespace Botan::TLS

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