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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 "crypto/s2n_cipher.h"
      17                 :            : #include "crypto/s2n_hmac.h"
      18                 :            : #include "crypto/s2n_sequence.h"
      19                 :            : #include "error/s2n_errno.h"
      20                 :            : #include "stuffer/s2n_stuffer.h"
      21                 :            : #include "tls/s2n_cipher_suites.h"
      22                 :            : #include "tls/s2n_connection.h"
      23                 :            : #include "tls/s2n_crypto.h"
      24                 :            : #include "tls/s2n_record_read.h"
      25                 :            : #include "utils/s2n_blob.h"
      26                 :            : #include "utils/s2n_safety.h"
      27                 :            : 
      28                 :            : int s2n_record_parse_stream(
      29                 :            :         const struct s2n_cipher_suite *cipher_suite,
      30                 :            :         struct s2n_connection *conn,
      31                 :            :         uint8_t content_type,
      32                 :            :         uint16_t encrypted_length,
      33                 :            :         uint8_t *implicit_iv,
      34                 :            :         struct s2n_hmac_state *mac,
      35                 :            :         uint8_t *sequence_number,
      36                 :            :         struct s2n_session_key *session_key)
      37                 :      74617 : {
      38                 :            :     /* Add the header to the HMAC */
      39                 :      74617 :     uint8_t *header = s2n_stuffer_raw_read(&conn->header_in, S2N_TLS_RECORD_HEADER_LENGTH);
      40 [ -  + ][ #  # ]:      74617 :     POSIX_ENSURE_REF(header);
      41                 :            : 
      42                 :      74617 :     struct s2n_blob en = { .size = encrypted_length, .data = s2n_stuffer_raw_read(&conn->in, encrypted_length) };
      43 [ -  + ][ #  # ]:      74617 :     POSIX_ENSURE_REF(en.data);
      44                 :            : 
      45                 :      74617 :     uint16_t payload_length = encrypted_length;
      46                 :      74617 :     uint8_t mac_digest_size = 0;
      47         [ -  + ]:      74617 :     POSIX_GUARD(s2n_hmac_digest_size(mac->alg, &mac_digest_size));
      48                 :            : 
      49 [ +  - ][ +  + ]:      74617 :     POSIX_ENSURE_GTE(payload_length, mac_digest_size);
      50                 :      74597 :     payload_length -= mac_digest_size;
      51                 :            : 
      52                 :            :     /* Decrypt stuff! */
      53         [ -  + ]:      74597 :     POSIX_GUARD(cipher_suite->record_alg->cipher->io.stream.decrypt(session_key, &en, &en));
      54                 :            : 
      55                 :            :     /* Update the MAC */
      56                 :      74597 :     header[3] = (payload_length >> 8);
      57                 :      74597 :     header[4] = payload_length & 0xff;
      58         [ -  + ]:      74597 :     POSIX_GUARD(s2n_hmac_reset(mac));
      59         [ -  + ]:      74597 :     POSIX_GUARD(s2n_hmac_update(mac, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
      60                 :            : 
      61         [ +  + ]:      74597 :     if (conn->actual_protocol_version == S2N_SSLv3) {
      62         [ -  + ]:        357 :         POSIX_GUARD(s2n_hmac_update(mac, header, 1));
      63         [ -  + ]:        357 :         POSIX_GUARD(s2n_hmac_update(mac, header + 3, 2));
      64                 :      74240 :     } else {
      65         [ -  + ]:      74240 :         POSIX_GUARD(s2n_hmac_update(mac, header, S2N_TLS_RECORD_HEADER_LENGTH));
      66                 :      74240 :     }
      67                 :            : 
      68                 :      74597 :     struct s2n_blob seq = { .data = sequence_number, .size = S2N_TLS_SEQUENCE_NUM_LEN };
      69         [ -  + ]:      74597 :     POSIX_GUARD(s2n_increment_sequence_number(&seq));
      70                 :            : 
      71                 :            :     /* MAC check for streaming ciphers - no padding */
      72         [ -  + ]:      74597 :     POSIX_GUARD(s2n_hmac_update(mac, en.data, payload_length));
      73                 :            : 
      74                 :      74597 :     uint8_t check_digest[S2N_MAX_DIGEST_LEN];
      75 [ -  + ][ #  # ]:      74597 :     POSIX_ENSURE_LTE(mac_digest_size, sizeof(check_digest));
      76         [ -  + ]:      74597 :     POSIX_GUARD(s2n_hmac_digest(mac, check_digest, mac_digest_size));
      77                 :            : 
      78         [ +  + ]:      74597 :     if (s2n_hmac_digest_verify(en.data + payload_length, check_digest, mac_digest_size) < 0) {
      79         [ +  - ]:      16158 :         POSIX_BAIL(S2N_ERR_BAD_MESSAGE);
      80                 :      16158 :     }
      81                 :            : 
      82                 :            :     /* O.k., we've successfully read and decrypted the record, now we need to align the stuffer
      83                 :            :      * for reading the plaintext data.
      84                 :            :      */
      85         [ -  + ]:      58439 :     POSIX_GUARD(s2n_stuffer_reread(&conn->in));
      86         [ -  + ]:      58439 :     POSIX_GUARD(s2n_stuffer_reread(&conn->header_in));
      87                 :            : 
      88                 :            :     /* Truncate and wipe the MAC and any padding */
      89         [ -  + ]:      58439 :     POSIX_GUARD(s2n_stuffer_wipe_n(&conn->in, s2n_stuffer_data_available(&conn->in) - payload_length));
      90                 :      58439 :     conn->in_status = PLAINTEXT;
      91                 :            : 
      92                 :      58439 :     return 0;
      93                 :      58439 : }