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1 : : /*
2 : : * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
3 : : *
4 : : * Licensed under the Apache License, Version 2.0 (the "License").
5 : : * You may not use this file except in compliance with the License.
6 : : * A copy of the License is located at
7 : : *
8 : : * http://aws.amazon.com/apache2.0
9 : : *
10 : : * or in the "license" file accompanying this file. This file is distributed
11 : : * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
12 : : * express or implied. See the License for the specific language governing
13 : : * permissions and limitations under the License.
14 : : */
15 : :
16 : : #include <stdint.h>
17 : :
18 : : #include "crypto/s2n_cipher.h"
19 : : #include "crypto/s2n_hmac.h"
20 : : #include "crypto/s2n_sequence.h"
21 : : #include "error/s2n_errno.h"
22 : : #include "stuffer/s2n_stuffer.h"
23 : : #include "tls/s2n_cipher_suites.h"
24 : : #include "tls/s2n_connection.h"
25 : : #include "tls/s2n_crypto.h"
26 : : #include "tls/s2n_ktls.h"
27 : : #include "tls/s2n_record.h"
28 : : #include "utils/s2n_blob.h"
29 : : #include "utils/s2n_random.h"
30 : : #include "utils/s2n_safety.h"
31 : :
32 : : extern uint8_t s2n_unknown_protocol_version;
33 : :
34 : : /* In TLS1.3 the record type is obfuscated as APPLICATION_DATA once the handshake begins to be encrypted.
35 : : * The real record type is encrypted and written in the final byte of the record.
36 : : * In TLS1.2 the record type is always cleartext. */
37 : 3606565 : #define RECORD_TYPE(is_tls13_record, content_type) (is_tls13_record ? TLS_APPLICATION_DATA : content_type)
38 : :
39 : : /* How much overhead does the IV, MAC, TAG and padding bytes introduce ? */
40 : : static S2N_RESULT s2n_tls_record_overhead(struct s2n_connection *conn, uint16_t *out)
41 : 3606890 : {
42 [ - + ][ # # ]: 3606890 : RESULT_ENSURE_REF(conn);
43 [ # # ][ - + ]: 3606890 : RESULT_ENSURE_MUT(out);
44 : 3606890 : struct s2n_crypto_parameters *active = conn->server;
45 : :
46 [ + + ]: 3606890 : if (conn->mode == S2N_CLIENT) {
47 : 84395 : active = conn->client;
48 : 84395 : }
49 : :
50 : 3606890 : uint8_t extra = 0;
51 [ - + ]: 3606890 : RESULT_GUARD_POSIX(s2n_hmac_digest_size(active->cipher_suite->record_alg->hmac_alg, &extra));
52 : :
53 [ + + ]: 3606890 : if (active->cipher_suite->record_alg->cipher->type == S2N_CBC) {
54 : : /* Subtract one for the padding length byte */
55 : 41818 : extra += 1;
56 : :
57 [ + + ]: 41818 : if (conn->actual_protocol_version > S2N_TLS10) {
58 : 32922 : extra += active->cipher_suite->record_alg->cipher->io.cbc.record_iv_size;
59 : 32922 : }
60 [ + + ]: 3565072 : } else if (active->cipher_suite->record_alg->cipher->type == S2N_AEAD) {
61 : 3346693 : extra += active->cipher_suite->record_alg->cipher->io.aead.tag_size;
62 : 3346693 : extra += active->cipher_suite->record_alg->cipher->io.aead.record_iv_size;
63 [ + + ][ + + ]: 3346693 : } else if (active->cipher_suite->record_alg->cipher->type == S2N_COMPOSITE && conn->actual_protocol_version > S2N_TLS10) {
64 : 131169 : extra += active->cipher_suite->record_alg->cipher->io.comp.record_iv_size;
65 : 131169 : }
66 : :
67 : 3606890 : *out = extra;
68 : :
69 : 3606890 : return S2N_RESULT_OK;
70 : 3606890 : }
71 : :
72 : : /* This function returns maximum size of plaintext data to write for the payload.
73 : : * Record overheads are not included here.
74 : : */
75 : : S2N_RESULT s2n_record_max_write_payload_size(struct s2n_connection *conn, uint16_t *max_fragment_size)
76 : 3629836 : {
77 [ - + ][ # # ]: 3629836 : RESULT_ENSURE_REF(conn);
78 [ # # ][ - + ]: 3629836 : RESULT_ENSURE_REF(conn->config);
79 [ # # ][ - + ]: 3629836 : RESULT_ENSURE_MUT(max_fragment_size);
80 [ + + ][ + - ]: 3629836 : RESULT_ENSURE(conn->max_outgoing_fragment_length > 0, S2N_ERR_FRAGMENT_LENGTH_TOO_SMALL);
81 : :
82 [ + + ]: 3629835 : *max_fragment_size = S2N_MIN(conn->max_outgoing_fragment_length, S2N_TLS_MAXIMUM_FRAGMENT_LENGTH);
83 : :
84 : : /* If a custom send buffer is configured, ensure it will be large enough for the payload.
85 : : * That may mean we need a smaller fragment size.
86 : : */
87 : 3629835 : uint32_t send_buffer_override = conn->config->send_buffer_size_override;
88 [ + + ]: 3629835 : if (send_buffer_override) {
89 : 70 : uint16_t max_record_size = 0;
90 [ - + ]: 70 : RESULT_GUARD(s2n_record_max_write_size(conn, *max_fragment_size, &max_record_size));
91 [ + + ]: 70 : if (send_buffer_override < max_record_size) {
92 : 10 : size_t overhead = (max_record_size - *max_fragment_size);
93 [ - + ][ # # ]: 10 : RESULT_ENSURE_GT(send_buffer_override, overhead);
94 : 10 : *max_fragment_size = send_buffer_override - overhead;
95 : 10 : }
96 : 70 : }
97 : :
98 : 3629835 : return S2N_RESULT_OK;
99 : 3629835 : }
100 : :
101 : : S2N_RESULT s2n_record_max_write_size(struct s2n_connection *conn, uint16_t max_fragment_size, uint16_t *max_record_size)
102 : 3307531 : {
103 [ + + ][ + - ]: 3307531 : RESULT_ENSURE_REF(conn);
104 [ + + ][ + - ]: 3307530 : RESULT_ENSURE_MUT(max_record_size);
105 : :
106 [ + + ]: 3307529 : if (!IS_NEGOTIATED(conn)) {
107 : 3300578 : *max_record_size = S2N_TLS_MAX_RECORD_LEN_FOR(max_fragment_size);
108 [ + + ]: 3300578 : } else if (conn->actual_protocol_version < S2N_TLS13) {
109 : 2392 : *max_record_size = S2N_TLS12_MAX_RECORD_LEN_FOR(max_fragment_size);
110 : 4559 : } else {
111 : 4559 : *max_record_size = S2N_TLS13_MAX_RECORD_LEN_FOR(max_fragment_size);
112 : 4559 : }
113 : 3307529 : return S2N_RESULT_OK;
114 : 3307530 : }
115 : :
116 : : /* Find the largest size that will fit within an ethernet frame for a "small" payload */
117 : : S2N_RESULT s2n_record_min_write_payload_size(struct s2n_connection *conn, uint16_t *payload_size)
118 : 325 : {
119 [ # # ][ - + ]: 325 : RESULT_ENSURE_REF(conn);
120 [ # # ][ - + ]: 325 : RESULT_ENSURE_MUT(payload_size);
121 : :
122 : : /* remove ethernet, TCP/IP and TLS header overheads */
123 : : /* We pessimistically assume that it's an Ipv6 header (40 bytes) vs an Ipv4
124 : : * header (20 bytes) to avoid having to care about the IP protocol. */
125 : 325 : const uint16_t min_outgoing_fragment_length = ETH_MTU - IP_V6_HEADER_LENGTH
126 : 325 : - TCP_HEADER_LENGTH - TCP_OPTIONS_LENGTH - S2N_TLS_RECORD_HEADER_LENGTH;
127 : :
128 [ # # ]: 325 : RESULT_ENSURE(min_outgoing_fragment_length <= S2N_TLS_MAXIMUM_FRAGMENT_LENGTH, S2N_ERR_FRAGMENT_LENGTH_TOO_LARGE);
129 : 325 : uint16_t size = min_outgoing_fragment_length;
130 : :
131 [ + + ]: 325 : const struct s2n_crypto_parameters *active = conn->mode == S2N_CLIENT ? conn->client : conn->server;
132 : :
133 : : /* Round the fragment size down to be block aligned */
134 [ + + ]: 325 : if (active->cipher_suite->record_alg->cipher->type == S2N_CBC) {
135 : 1 : size -= size % active->cipher_suite->record_alg->cipher->io.cbc.block_size;
136 [ + + ]: 324 : } else if (active->cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) {
137 : 1 : size -= size % active->cipher_suite->record_alg->cipher->io.comp.block_size;
138 : : /* Composite digest length */
139 : 1 : size -= active->cipher_suite->record_alg->cipher->io.comp.mac_key_size;
140 : : /* Padding length byte */
141 : 1 : size -= 1;
142 : 1 : }
143 : :
144 : : /* If TLS1.3, remove content type */
145 [ + + ]: 325 : if (conn->actual_protocol_version >= S2N_TLS13) {
146 [ # # ][ - + ]: 68 : RESULT_ENSURE(size > S2N_TLS_CONTENT_TYPE_LENGTH, S2N_ERR_FRAGMENT_LENGTH_TOO_SMALL);
147 : 68 : size -= S2N_TLS_CONTENT_TYPE_LENGTH;
148 : 68 : }
149 : :
150 : : /* subtract overheads of a TLS record */
151 : 325 : uint16_t overhead = 0;
152 [ - + ]: 325 : RESULT_GUARD(s2n_tls_record_overhead(conn, &overhead));
153 [ - + ][ # # ]: 325 : RESULT_ENSURE(size > overhead, S2N_ERR_FRAGMENT_LENGTH_TOO_SMALL);
154 : 325 : size -= overhead;
155 : :
156 [ - + ][ # # ]: 325 : RESULT_ENSURE(size > 0, S2N_ERR_FRAGMENT_LENGTH_TOO_SMALL);
157 [ # # ][ - + ]: 325 : RESULT_ENSURE(size <= ETH_MTU, S2N_ERR_FRAGMENT_LENGTH_TOO_LARGE);
158 : :
159 : 325 : *payload_size = size;
160 : :
161 : 325 : return S2N_RESULT_OK;
162 : 325 : }
163 : :
164 : : int s2n_record_write_protocol_version(struct s2n_connection *conn, uint8_t record_type, struct s2n_stuffer *out)
165 : 3606565 : {
166 : 3606565 : uint8_t record_protocol_version = conn->actual_protocol_version;
167 : :
168 : : /**
169 : : *= https://www.rfc-editor.org/rfc/rfc8446#section-5.1
170 : : *# This version value is historical, deriving from the use of 0x0301 for
171 : : *# TLS 1.0 and 0x0300 for SSL 3.0. In order to maximize backward
172 : : *# compatibility, a record containing an initial ClientHello SHOULD have
173 : : *# version 0x0301 (reflecting TLS 1.0)
174 : : *
175 : : * We set actual_protocol_version early for clients, but we do not
176 : : * use that assumed value here in case we are talking to a legacy
177 : : * server that expects TLS1.0.
178 : : *
179 : : * Both TLS 1.3 early data and a deserialized connection will
180 : : * send data without the server_protocol_version being known. However,
181 : : * the record type would be set to APPLICATION_DATA in their cases
182 : : * so this check is avoided.
183 : : **/
184 [ + + ]: 3606565 : if (conn->server_protocol_version == s2n_unknown_protocol_version
185 [ + + ]: 3606565 : && record_type == TLS_HANDSHAKE) {
186 [ + + ]: 8166 : record_protocol_version = S2N_MIN(record_protocol_version, S2N_TLS10);
187 : 8166 : }
188 : :
189 : : /**
190 : : *= https://www.rfc-editor.org/rfc/rfc8446#section-5.1
191 : : *# legacy_record_version: MUST be set to 0x0303 for all records
192 : : *# generated by a TLS 1.3 implementation other than an initial
193 : : *# ClientHello (i.e., one not generated after a HelloRetryRequest),
194 : : *# where it MAY also be 0x0301 for compatibility purposes.
195 : : **/
196 [ + + ]: 3606565 : record_protocol_version = S2N_MIN(record_protocol_version, S2N_TLS12);
197 : :
198 : : /* Never send an empty protocol version.
199 : : * If the protocol version is unknown, default to TLS1.0 like we do for initial ClientHellos.
200 : : */
201 [ + + ]: 3606565 : if (record_protocol_version == s2n_unknown_protocol_version) {
202 : 18 : record_protocol_version = S2N_TLS10;
203 : 18 : }
204 : :
205 : 3606565 : uint8_t protocol_version[S2N_TLS_PROTOCOL_VERSION_LEN];
206 : 3606565 : protocol_version[0] = record_protocol_version / 10;
207 : 3606565 : protocol_version[1] = record_protocol_version % 10;
208 : :
209 [ - + ]: 3606565 : POSIX_GUARD(s2n_stuffer_write_bytes(out, protocol_version, S2N_TLS_PROTOCOL_VERSION_LEN));
210 : :
211 : 3606565 : return 0;
212 : 3606565 : }
213 : :
214 : : static inline int s2n_record_encrypt(
215 : : struct s2n_connection *conn,
216 : : const struct s2n_cipher_suite *cipher_suite,
217 : : struct s2n_session_key *session_key,
218 : : struct s2n_blob *iv,
219 : : struct s2n_blob *aad,
220 : : struct s2n_blob *en,
221 : : uint8_t *implicit_iv, uint16_t block_size)
222 : 3606564 : {
223 [ # # ][ - + ]: 3606564 : POSIX_ENSURE_REF(en->data);
224 : :
225 : 3606564 : switch (cipher_suite->record_alg->cipher->type) {
226 [ + + ]: 54391 : case S2N_STREAM:
227 [ - + ]: 54391 : POSIX_GUARD(cipher_suite->record_alg->cipher->io.stream.encrypt(session_key, en, en));
228 : 54391 : break;
229 [ + + ]: 54391 : case S2N_CBC:
230 [ - + ]: 41817 : POSIX_GUARD(cipher_suite->record_alg->cipher->io.cbc.encrypt(session_key, iv, en, en));
231 : :
232 : : /* Copy the last encrypted block to be the next IV */
233 [ + + ]: 41817 : if (conn->actual_protocol_version < S2N_TLS11) {
234 [ - + ][ # # ]: 8896 : POSIX_ENSURE_GTE(en->size, block_size);
235 [ - + ][ # # ]: 8896 : POSIX_CHECKED_MEMCPY(implicit_iv, en->data + en->size - block_size, block_size);
[ + - ]
236 : 8896 : }
237 : 41817 : break;
238 [ + + ]: 3346371 : case S2N_AEAD:
239 [ - + ]: 3346371 : POSIX_GUARD(cipher_suite->record_alg->cipher->io.aead.encrypt(session_key, iv, aad, en, en));
240 : 3346371 : break;
241 [ + + ]: 3346371 : case S2N_COMPOSITE:
242 : : /* This will: compute mac, append padding, append padding length, and encrypt */
243 [ - + ]: 163985 : POSIX_GUARD(cipher_suite->record_alg->cipher->io.comp.encrypt(session_key, iv, en, en));
244 : :
245 : : /* Copy the last encrypted block to be the next IV */
246 [ # # ][ - + ]: 163985 : POSIX_ENSURE_GTE(en->size, block_size);
247 [ - + ][ # # ]: 163985 : POSIX_CHECKED_MEMCPY(implicit_iv, en->data + en->size - block_size, block_size);
[ + - ]
248 : 163985 : break;
249 [ - + ]: 163985 : default:
250 [ # # ]: 0 : POSIX_BAIL(S2N_ERR_CIPHER_TYPE);
251 : 0 : break;
252 : 3606564 : }
253 : :
254 : 3606564 : return 0;
255 : 3606564 : }
256 : :
257 : : static S2N_RESULT s2n_record_write_mac(struct s2n_connection *conn, struct s2n_blob *record_header,
258 : : struct s2n_blob *plaintext, struct s2n_stuffer *out, uint32_t *bytes_written)
259 : 3606565 : {
260 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(conn);
261 [ # # ][ - + ]: 3606565 : RESULT_ENSURE_REF(conn->server);
262 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(conn->client);
263 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(record_header);
264 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(plaintext);
265 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(out);
266 [ # # ][ - + ]: 3606565 : RESULT_ENSURE_REF(bytes_written);
267 : 3606565 : *bytes_written = 0;
268 : :
269 : 3606565 : struct s2n_hmac_state *mac = &conn->server->server_record_mac;
270 : 3606565 : const struct s2n_cipher_suite *cipher_suite = conn->server->cipher_suite;
271 : 3606565 : uint8_t *sequence_number = conn->server->server_sequence_number;
272 : :
273 [ + + ]: 3606565 : if (conn->mode == S2N_CLIENT) {
274 : 84077 : mac = &conn->client->client_record_mac;
275 : 84077 : cipher_suite = conn->client->cipher_suite;
276 : 84077 : sequence_number = conn->client->client_sequence_number;
277 : 84077 : }
278 : :
279 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(cipher_suite);
280 [ - + ][ # # ]: 3606565 : RESULT_ENSURE_REF(cipher_suite->record_alg);
281 : :
282 [ + + ]: 3606565 : if (cipher_suite->record_alg->hmac_alg == S2N_HMAC_NONE) {
283 : : /* If the S2N_HMAC_NONE algorithm is specified, a MAC should not be explicitly written.
284 : : * This is the case for AEAD and Composite cipher types, where the MAC is written as part
285 : : * of encryption. This is also the case for plaintext handshake records, where the null
286 : : * stream cipher is used.
287 : : */
288 : 3556657 : return S2N_RESULT_OK;
289 : 3556657 : }
290 : :
291 : : /**
292 : : *= https://www.rfc-editor.org/rfc/rfc5246#section-6.2.3.1
293 : : *# The MAC is generated as:
294 : : *#
295 : : *# MAC(MAC_write_key, seq_num +
296 : : */
297 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_update(mac, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
298 : :
299 : 49908 : struct s2n_stuffer header_stuffer = { 0 };
300 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_stuffer_init_written(&header_stuffer, record_header));
301 : :
302 : : /**
303 : : *= https://www.rfc-editor.org/rfc/rfc5246#section-6.2.3.1
304 : : *# TLSCompressed.type +
305 : : */
306 : 49908 : void *record_type_byte = s2n_stuffer_raw_read(&header_stuffer, sizeof(uint8_t));
307 [ # # ][ - + ]: 49908 : RESULT_ENSURE_REF(record_type_byte);
308 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_update(mac, record_type_byte, sizeof(uint8_t)));
309 : :
310 : : /**
311 : : *= https://www.rfc-editor.org/rfc/rfc5246#section-6.2.3.1
312 : : *# TLSCompressed.version +
313 : : */
314 : 49908 : void *protocol_version_bytes = s2n_stuffer_raw_read(&header_stuffer, S2N_TLS_PROTOCOL_VERSION_LEN);
315 [ - + ][ # # ]: 49908 : RESULT_ENSURE_REF(protocol_version_bytes);
316 [ + + ]: 49908 : if (conn->actual_protocol_version > S2N_SSLv3) {
317 : : /* SSLv3 doesn't include the protocol version in the MAC. */
318 [ - + ]: 49242 : RESULT_GUARD_POSIX(s2n_hmac_update(mac, protocol_version_bytes, S2N_TLS_PROTOCOL_VERSION_LEN));
319 : 49242 : }
320 : :
321 : : /**
322 : : *= https://www.rfc-editor.org/rfc/rfc5246#section-6.2.3.1
323 : : *# TLSCompressed.length +
324 : : *
325 : : * Note that the length field refers to the length of the plaintext content, not the length of
326 : : * TLSCiphertext fragment written to the record header, which accounts for additional fields
327 : : * such as the padding and MAC.
328 : : */
329 : 49908 : uint8_t content_length_bytes[sizeof(uint16_t)] = { 0 };
330 : 49908 : struct s2n_blob content_length_blob = { 0 };
331 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_blob_init(&content_length_blob, content_length_bytes, sizeof(content_length_bytes)));
332 : 49908 : struct s2n_stuffer content_length_stuffer = { 0 };
333 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_stuffer_init(&content_length_stuffer, &content_length_blob));
334 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_stuffer_write_uint16(&content_length_stuffer, plaintext->size));
335 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_update(mac, content_length_bytes, sizeof(content_length_bytes)));
336 : :
337 : : /**
338 : : *= https://www.rfc-editor.org/rfc/rfc5246#section-6.2.3.1
339 : : *# TLSCompressed.fragment);
340 : : *#
341 : : *# where "+" denotes concatenation.
342 : : */
343 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_update(mac, plaintext->data, plaintext->size));
344 : :
345 : 49908 : uint8_t mac_digest_size = 0;
346 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_digest_size(mac->alg, &mac_digest_size));
347 : 49908 : uint8_t *digest = s2n_stuffer_raw_write(out, mac_digest_size);
348 [ - + ][ # # ]: 49908 : RESULT_ENSURE_REF(digest);
349 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_digest(mac, digest, mac_digest_size));
350 : 49908 : *bytes_written = mac_digest_size;
351 : :
352 [ - + ]: 49908 : RESULT_GUARD_POSIX(s2n_hmac_reset(mac));
353 : :
354 : 49908 : return S2N_RESULT_OK;
355 : 49908 : }
356 : :
357 : : int s2n_record_writev(struct s2n_connection *conn, uint8_t content_type, const struct iovec *in, int in_count, size_t offs, size_t to_write)
358 : 3606575 : {
359 [ + + ]: 3606575 : if (conn->ktls_send_enabled) {
360 : 8 : return s2n_ktls_record_writev(conn, content_type, in, in_count, offs, to_write);
361 : 8 : }
362 : :
363 : 3606567 : struct s2n_blob iv = { 0 };
364 : 3606567 : uint8_t padding = 0;
365 : 3606567 : uint16_t block_size = 0;
366 : 3606567 : uint8_t aad_iv[S2N_TLS_MAX_IV_LEN] = { 0 };
367 : :
368 : : /* In TLS 1.3, handle CCS message as unprotected records */
369 : 3606567 : struct s2n_crypto_parameters *current_client_crypto = conn->client;
370 : 3606567 : struct s2n_crypto_parameters *current_server_crypto = conn->server;
371 [ + + ][ + + ]: 3606567 : if (conn->actual_protocol_version == S2N_TLS13 && content_type == TLS_CHANGE_CIPHER_SPEC) {
372 [ # # ][ - + ]: 7523 : POSIX_ENSURE_REF(conn->initial);
373 : 7523 : conn->client = conn->initial;
374 : 7523 : conn->server = conn->initial;
375 : 7523 : }
376 : :
377 : 3606567 : uint8_t *sequence_number = conn->server->server_sequence_number;
378 : 3606567 : struct s2n_session_key *session_key = &conn->server->server_key;
379 : 3606567 : const struct s2n_cipher_suite *cipher_suite = conn->server->cipher_suite;
380 : 3606567 : uint8_t *implicit_iv = conn->server->server_implicit_iv;
381 : :
382 [ + + ]: 3606567 : if (conn->mode == S2N_CLIENT) {
383 : 84077 : sequence_number = conn->client->client_sequence_number;
384 : 84077 : session_key = &conn->client->client_key;
385 : 84077 : cipher_suite = conn->client->cipher_suite;
386 : 84077 : implicit_iv = conn->client->client_implicit_iv;
387 : 84077 : }
388 : :
389 : : /* The NULL stream cipher MUST NEVER be used for ApplicationData.
390 : : * Writing ApplicationData unencrypted defeats the purpose of TLS. */
391 [ + + ]: 3606567 : if (cipher_suite->record_alg->cipher == &s2n_null_cipher) {
392 [ + - ][ + + ]: 54393 : POSIX_ENSURE(content_type != TLS_APPLICATION_DATA, S2N_ERR_ENCRYPT);
393 : 54393 : }
394 : :
395 : 3606566 : const int is_tls13_record = cipher_suite->record_alg->flags & S2N_TLS13_RECORD_AEAD_NONCE;
396 [ - + ][ # # ]: 3606566 : s2n_stack_blob(aad, is_tls13_record ? S2N_TLS13_AAD_LEN : S2N_TLS_MAX_AAD_LEN, S2N_TLS_MAX_AAD_LEN);
[ - + ][ + + ]
397 : :
398 : : /* If we aren't buffering multiple records, then the output stuffer should be empty. */
399 [ + + ]: 3606566 : if (!conn->multirecord_send) {
400 [ + + ][ + - ]: 3606536 : POSIX_ENSURE(s2n_stuffer_data_available(&conn->out) == 0, S2N_ERR_RECORD_STUFFER_NEEDS_DRAINING);
401 : 3606536 : }
402 : :
403 : : /* Before we do anything, we need to figure out what the length of the
404 : : * fragment is going to be.
405 : : */
406 : 3606565 : uint16_t max_write_payload_size = 0;
407 [ - + ]: 3606565 : POSIX_GUARD_RESULT(s2n_record_max_write_payload_size(conn, &max_write_payload_size));
408 [ + + ]: 3606565 : const uint16_t data_bytes_to_take = S2N_MIN(to_write, max_write_payload_size);
409 : :
410 : 3606565 : uint16_t extra = 0;
411 [ - + ]: 3606565 : POSIX_GUARD_RESULT(s2n_tls_record_overhead(conn, &extra));
412 : :
413 : : /* If we have padding to worry about, figure that out too */
414 [ + + ]: 3606565 : if (cipher_suite->record_alg->cipher->type == S2N_CBC) {
415 : 41817 : block_size = cipher_suite->record_alg->cipher->io.cbc.block_size;
416 [ + + ]: 41817 : if (((data_bytes_to_take + extra) % block_size)) {
417 : 38764 : padding = block_size - ((data_bytes_to_take + extra) % block_size);
418 : 38764 : }
419 [ + + ]: 3564748 : } else if (cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) {
420 : 163985 : block_size = cipher_suite->record_alg->cipher->io.comp.block_size;
421 : 163985 : }
422 : :
423 [ + + ]: 3606565 : if (s2n_stuffer_is_freed(&conn->out)) {
424 : : /* If the output buffer has not been allocated yet, allocate
425 : : * at least enough memory to hold a record with the local maximum fragment length.
426 : : *
427 : : * The local maximum fragment length is:
428 : : * 1) The local default configured for new connections
429 : : * 2) The local value set by the user via s2n_connection_prefer_throughput()
430 : : * or s2n_connection_prefer_low_latency()
431 : : * 3) On the server, the minimum of the local value and the value negotiated with the
432 : : * client via the max_fragment_length extension
433 : : *
434 : : * Because this only occurs if the output buffer has not been allocated,
435 : : * it does NOT resize existing buffers.
436 : : */
437 : 3307043 : uint16_t max_wire_record_size = 0;
438 [ - + ]: 3307043 : POSIX_GUARD_RESULT(s2n_record_max_write_size(conn, max_write_payload_size, &max_wire_record_size));
439 : :
440 [ + + ]: 3307043 : uint32_t buffer_size = S2N_MAX(conn->config->send_buffer_size_override, max_wire_record_size);
441 [ - + ]: 3307043 : POSIX_GUARD(s2n_stuffer_growable_alloc(&conn->out, buffer_size));
442 : 3307043 : }
443 : :
444 : : /* A record only local stuffer used to avoid tainting the conn->out stuffer or overwriting
445 : : * previous records. It should be used to add an individual record to the out stuffer.
446 : : */
447 : 3606565 : struct s2n_blob record_blob = { 0 };
448 : 3606565 : struct s2n_stuffer record_stuffer = { 0 };
449 [ - + ]: 3606565 : POSIX_GUARD(s2n_blob_init(&record_blob,
450 : 3606565 : conn->out.blob.data + conn->out.write_cursor,
451 : 3606565 : s2n_stuffer_space_remaining(&conn->out)));
452 [ - + ]: 3606565 : POSIX_GUARD(s2n_stuffer_init(&record_stuffer, &record_blob));
453 : :
454 : : /* Now that we know the length, start writing the record */
455 [ + + ]: 3606565 : uint8_t record_type = RECORD_TYPE(is_tls13_record, content_type);
456 [ - + ]: 3606565 : POSIX_GUARD(s2n_stuffer_write_uint8(&record_stuffer, record_type));
457 [ - + ]: 3606565 : POSIX_GUARD(s2n_record_write_protocol_version(conn, record_type, &record_stuffer));
458 : :
459 : : /* Compute non-payload parts of the MAC(seq num, type, proto vers, fragment length) for composite ciphers.
460 : : * Composite "encrypt" will MAC the payload data and fill in padding.
461 : : */
462 [ + + ]: 3606565 : if (cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) {
463 : : /* Only fragment length is needed for MAC, but the EVP ctrl function needs fragment length + eiv len. */
464 : 163985 : uint16_t payload_and_eiv_len = data_bytes_to_take;
465 [ + + ]: 163985 : if (conn->actual_protocol_version > S2N_TLS10) {
466 : 131168 : payload_and_eiv_len += block_size;
467 : 131168 : }
468 : :
469 : : /* Outputs number of extra bytes required for MAC and padding */
470 : 163985 : int pad_and_mac_len = 0;
471 [ - + ]: 163985 : POSIX_GUARD(cipher_suite->record_alg->cipher->io.comp.initial_hmac(session_key, sequence_number, content_type, conn->actual_protocol_version,
472 : 163985 : payload_and_eiv_len, &pad_and_mac_len));
473 : 163985 : extra += pad_and_mac_len;
474 : 163985 : }
475 : :
476 : : /* TLS 1.3 protected record occupies one extra byte for content type */
477 [ + + ]: 3606565 : if (is_tls13_record) {
478 : 110044 : extra += S2N_TLS_CONTENT_TYPE_LENGTH;
479 : 110044 : }
480 : :
481 : : /* Rewrite the length to be the actual fragment length */
482 : 3606565 : const uint16_t actual_fragment_length = data_bytes_to_take + padding + extra;
483 : : /* ensure actual_fragment_length + S2N_TLS_RECORD_HEADER_LENGTH <= max record length */
484 [ + + ]: 3606565 : const uint16_t max_record_length = is_tls13_record ? S2N_TLS13_MAXIMUM_RECORD_LENGTH : S2N_TLS_MAXIMUM_RECORD_LENGTH;
485 [ - + ][ # # ]: 3606565 : S2N_ERROR_IF(actual_fragment_length + S2N_TLS_RECORD_HEADER_LENGTH > max_record_length, S2N_ERR_RECORD_LENGTH_TOO_LARGE);
486 [ - + ]: 3606565 : POSIX_GUARD(s2n_stuffer_write_uint16(&record_stuffer, actual_fragment_length));
487 : :
488 : : /* If we're AEAD, write the sequence number as an IV, and generate the AAD */
489 [ + + ]: 3606565 : if (cipher_suite->record_alg->cipher->type == S2N_AEAD) {
490 : 3346371 : struct s2n_stuffer iv_stuffer = { 0 };
491 [ - + ]: 3346371 : POSIX_GUARD(s2n_blob_init(&iv, aad_iv, sizeof(aad_iv)));
492 [ - + ]: 3346371 : POSIX_GUARD(s2n_stuffer_init(&iv_stuffer, &iv));
493 : :
494 [ + + ]: 3346371 : if (cipher_suite->record_alg->flags & S2N_TLS12_AES_GCM_AEAD_NONCE) {
495 : : /* Partially explicit nonce. See RFC 5288 Section 3 */
496 [ - + ]: 2178483 : POSIX_GUARD(s2n_stuffer_write_bytes(&record_stuffer, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
497 [ - + ]: 2178483 : POSIX_GUARD(s2n_stuffer_write_bytes(&iv_stuffer, implicit_iv, cipher_suite->record_alg->cipher->io.aead.fixed_iv_size));
498 [ - + ]: 2178483 : POSIX_GUARD(s2n_stuffer_write_bytes(&iv_stuffer, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
499 [ + + ][ + - ]: 2178483 : } else if (cipher_suite->record_alg->flags & S2N_TLS12_CHACHA_POLY_AEAD_NONCE || is_tls13_record) {
500 : : /* Fully implicit nonce. See RFC7905 Section 2 */
501 : 1167888 : uint8_t four_zeroes[4] = { 0 };
502 [ - + ]: 1167888 : POSIX_GUARD(s2n_stuffer_write_bytes(&iv_stuffer, four_zeroes, 4));
503 [ - + ]: 1167888 : POSIX_GUARD(s2n_stuffer_write_bytes(&iv_stuffer, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
504 [ + + ]: 15182544 : for (int i = 0; i < cipher_suite->record_alg->cipher->io.aead.fixed_iv_size; i++) {
505 : 14014656 : aad_iv[i] = aad_iv[i] ^ implicit_iv[i];
506 : 14014656 : }
507 : 1167888 : } else {
508 [ # # ]: 0 : POSIX_BAIL(S2N_ERR_INVALID_NONCE_TYPE);
509 : 0 : }
510 : :
511 : : /* Set the IV size to the amount of data written */
512 : 3346371 : iv.size = s2n_stuffer_data_available(&iv_stuffer);
513 [ + + ]: 3346371 : if (is_tls13_record) {
514 [ - + ]: 110044 : POSIX_GUARD_RESULT(s2n_tls13_aead_aad_init(data_bytes_to_take + S2N_TLS_CONTENT_TYPE_LENGTH, cipher_suite->record_alg->cipher->io.aead.tag_size, &aad));
515 : 3236327 : } else {
516 [ - + ]: 3236327 : POSIX_GUARD_RESULT(s2n_aead_aad_init(conn, sequence_number, content_type, data_bytes_to_take, &aad));
517 : 3236327 : }
518 [ + + ][ + + ]: 3346371 : } else if (cipher_suite->record_alg->cipher->type == S2N_CBC || cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) {
519 [ - + ]: 205802 : POSIX_GUARD(s2n_blob_init(&iv, implicit_iv, block_size));
520 : :
521 : : /* For TLS1.1/1.2; write the IV with random data */
522 [ + + ]: 205802 : if (conn->actual_protocol_version > S2N_TLS10) {
523 [ - + ]: 164089 : POSIX_GUARD_RESULT(s2n_get_public_random_data(&iv));
524 [ + + ]: 164089 : if (cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) {
525 : : /* Write a separate random block to the record. This will be used along with the previously generated
526 : : * iv blob to generate the final explicit_iv for this record.
527 : : *
528 : : * How? Openssl's AES-CBC stitched encrypt populates the first block of application data with:
529 : : * AES(Key, XOR(iv, initial_block))
530 : : *
531 : : * If we make initial_block a random block unrelated to random_iv, explicit IV for this record
532 : : * is random value based on the two random blobs we just generated:
533 : : * AES(Key, XOR(random_iv, explicit_iv_placeholder) == AES(Key, XOR(random_iv, random_iv2))
534 : : *
535 : : * NOTE: We can't use the same random IV blob as both the initial block and IV since it will result in:
536 : : * AES(Key, XOR(random_iv, random_iv)) == AES(Key, 0), which will be shared by all records in this session.
537 : : */
538 : 131168 : struct s2n_blob explicit_iv_placeholder = { 0 };
539 : 131168 : uint8_t zero_block[S2N_TLS_MAX_IV_LEN] = { 0 };
540 [ - + ]: 131168 : POSIX_GUARD(s2n_blob_init(&explicit_iv_placeholder, zero_block, block_size));
541 [ - + ]: 131168 : POSIX_GUARD_RESULT(s2n_get_public_random_data(&explicit_iv_placeholder));
542 [ - + ]: 131168 : POSIX_GUARD(s2n_stuffer_write(&record_stuffer, &explicit_iv_placeholder));
543 : 131168 : } else {
544 : : /* We can write the explicit IV directly to the record for non composite CBC because
545 : : * s2n starts AES *after* the explicit IV.
546 : : */
547 [ - + ]: 32921 : POSIX_GUARD(s2n_stuffer_write(&record_stuffer, &iv));
548 : 32921 : }
549 : 164089 : }
550 : 205802 : }
551 : :
552 : : /* Write the plaintext data */
553 [ - + ]: 3606565 : POSIX_GUARD(s2n_stuffer_writev_bytes(&record_stuffer, in, in_count, offs, data_bytes_to_take));
554 : 3606565 : void *orig_write_ptr = record_stuffer.blob.data + record_stuffer.write_cursor - data_bytes_to_take;
555 : :
556 : : /* Write the MAC */
557 : 3606565 : struct s2n_blob header_blob = { 0 };
558 [ - + ]: 3606565 : POSIX_GUARD(s2n_blob_slice(&record_blob, &header_blob, 0, S2N_TLS_RECORD_HEADER_LENGTH));
559 : 3606565 : struct s2n_blob plaintext_blob = { 0 };
560 [ - + ]: 3606565 : POSIX_GUARD(s2n_blob_init(&plaintext_blob, orig_write_ptr, data_bytes_to_take));
561 : 3606565 : uint32_t mac_digest_size = 0;
562 [ - + ]: 3606565 : POSIX_GUARD_RESULT(s2n_record_write_mac(conn, &header_blob, &plaintext_blob, &record_stuffer, &mac_digest_size));
563 : :
564 : : /* We are done with this sequence number, so we can increment it */
565 : 3606565 : struct s2n_blob seq = { 0 };
566 [ - + ]: 3606565 : POSIX_GUARD(s2n_blob_init(&seq, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
567 [ + + ]: 3606565 : POSIX_GUARD(s2n_increment_sequence_number(&seq));
568 : :
569 : : /* Write content type for TLS 1.3 record (RFC 8446 Section 5.2) */
570 [ + + ]: 3606564 : if (is_tls13_record) {
571 [ - + ]: 110044 : POSIX_GUARD(s2n_stuffer_write_uint8(&record_stuffer, content_type));
572 : 110044 : }
573 : :
574 [ + + ]: 3606564 : if (cipher_suite->record_alg->cipher->type == S2N_CBC) {
575 : : /* Include padding bytes, each with the value 'p', and
576 : : * include an extra padding length byte, also with the value 'p'.
577 : : */
578 [ + + ]: 363199 : for (int i = 0; i <= padding; i++) {
579 [ - + ]: 321382 : POSIX_GUARD(s2n_stuffer_write_uint8(&record_stuffer, padding));
580 : 321382 : }
581 : 41817 : }
582 : :
583 : : /* Rewind to rewrite/encrypt the packet */
584 [ - + ]: 3606564 : POSIX_GUARD(s2n_stuffer_rewrite(&record_stuffer));
585 : :
586 : : /* Skip the header */
587 [ - + ]: 3606564 : POSIX_GUARD(s2n_stuffer_skip_write(&record_stuffer, S2N_TLS_RECORD_HEADER_LENGTH));
588 : :
589 : 3606564 : uint16_t encrypted_length = data_bytes_to_take + mac_digest_size;
590 : 3606564 : switch (cipher_suite->record_alg->cipher->type) {
591 [ + + ]: 3346371 : case S2N_AEAD:
592 [ - + ]: 3346371 : POSIX_GUARD(s2n_stuffer_skip_write(&record_stuffer, cipher_suite->record_alg->cipher->io.aead.record_iv_size));
593 : 3346371 : encrypted_length += cipher_suite->record_alg->cipher->io.aead.tag_size;
594 [ + + ]: 3346371 : if (is_tls13_record) {
595 : : /* one extra byte for content type */
596 : 110044 : encrypted_length += S2N_TLS_CONTENT_TYPE_LENGTH;
597 : 110044 : }
598 : 3346371 : break;
599 [ + + ]: 41817 : case S2N_CBC:
600 [ + + ]: 41817 : if (conn->actual_protocol_version > S2N_TLS10) {
601 : : /* Leave the IV alone and unencrypted */
602 [ - + ]: 32921 : POSIX_GUARD(s2n_stuffer_skip_write(&record_stuffer, iv.size));
603 : 32921 : }
604 : : /* Encrypt the padding and the padding length byte too */
605 : 41817 : encrypted_length += padding + 1;
606 : 41817 : break;
607 [ + + ]: 163985 : case S2N_COMPOSITE:
608 : : /* Composite CBC expects a pointer starting at explicit IV: [Explicit IV | fragment | MAC | padding | padding len ]
609 : : * extra will account for the explicit IV len(if applicable), MAC digest len, padding len + padding byte.
610 : : */
611 : 163985 : encrypted_length += extra;
612 : 163985 : break;
613 [ + + ]: 54391 : default:
614 : 54391 : break;
615 : 3606564 : }
616 : :
617 : : /* Check that stuffer have enough space to write encrypted record, because raw_write cannot expand tainted stuffer */
618 [ - + ][ # # ]: 3606564 : S2N_ERROR_IF(s2n_stuffer_space_remaining(&record_stuffer) < encrypted_length, S2N_ERR_RECORD_STUFFER_SIZE);
619 : :
620 : : /* Do the encryption */
621 : 3606564 : struct s2n_blob en = { .size = encrypted_length, .data = s2n_stuffer_raw_write(&record_stuffer, encrypted_length) };
622 [ - + ]: 3606564 : POSIX_GUARD(s2n_record_encrypt(conn, cipher_suite, session_key, &iv, &aad, &en, implicit_iv, block_size));
623 : :
624 : : /* Sync the out stuffer write cursor with the record stuffer. */
625 [ - + ]: 3606564 : POSIX_GUARD(s2n_stuffer_skip_write(&conn->out, s2n_stuffer_data_available(&record_stuffer)));
626 : :
627 [ + + ][ + + ]: 3606564 : if (conn->actual_protocol_version == S2N_TLS13 && content_type == TLS_CHANGE_CIPHER_SPEC) {
628 : 7523 : conn->client = current_client_crypto;
629 : 7523 : conn->server = current_server_crypto;
630 : 7523 : }
631 : :
632 : 3606564 : return data_bytes_to_take;
633 : 3606564 : }
634 : :
635 : : S2N_RESULT s2n_record_write(struct s2n_connection *conn, uint8_t content_type, struct s2n_blob *in)
636 : 3392051 : {
637 : 3392051 : struct iovec iov;
638 : 3392051 : iov.iov_base = in->data;
639 : 3392051 : iov.iov_len = in->size;
640 : 3392051 : int written = s2n_record_writev(conn, content_type, &iov, 1, 0, in->size);
641 [ + + ]: 3392051 : RESULT_GUARD_POSIX(written);
642 [ + - ][ + + ]: 3392048 : RESULT_ENSURE((uint32_t) written == in->size, S2N_ERR_FRAGMENT_LENGTH_TOO_LARGE);
643 : 3392028 : return S2N_RESULT_OK;
644 : 3392048 : }
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