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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                 :            :         struct s2n_record_header *header,
      32                 :            :         uint8_t *implicit_iv,
      33                 :            :         struct s2n_hmac_state *mac,
      34                 :            :         uint8_t *sequence_number,
      35                 :            :         struct s2n_session_key *session_key)
      36                 :      76826 : {
      37                 :      76826 :     struct s2n_blob en = { .size = header->length, .data = s2n_stuffer_raw_read(&conn->in, header->length) };
      38 [ -  + ][ #  # ]:      76826 :     POSIX_ENSURE_REF(en.data);
      39                 :            : 
      40                 :      76826 :     uint16_t payload_length = header->length;
      41                 :      76826 :     uint8_t mac_digest_size = 0;
      42         [ -  + ]:      76826 :     POSIX_GUARD(s2n_hmac_digest_size(mac->alg, &mac_digest_size));
      43                 :            : 
      44 [ -  + ][ #  # ]:      76826 :     POSIX_ENSURE_GTE(payload_length, mac_digest_size);
      45                 :      76826 :     payload_length -= mac_digest_size;
      46                 :            : 
      47                 :            :     /* Decrypt stuff! */
      48         [ -  + ]:      76826 :     POSIX_GUARD(cipher_suite->record_alg->cipher->io.stream.decrypt(session_key, &en, &en));
      49                 :            : 
      50                 :            :     /* Update the MAC */
      51         [ -  + ]:      76826 :     POSIX_GUARD(s2n_hmac_reset(mac));
      52         [ -  + ]:      76826 :     POSIX_GUARD(s2n_hmac_update(mac, sequence_number, S2N_TLS_SEQUENCE_NUM_LEN));
      53                 :            : 
      54         [ +  + ]:      76826 :     if (conn->actual_protocol_version == S2N_SSLv3) {
      55         [ -  + ]:        362 :         POSIX_GUARD(s2n_hmac_update(mac, &header->content_type, 1));
      56         [ -  + ]:        362 :         POSIX_GUARD(s2n_hmac_update_u16(mac, payload_length));
      57                 :      76464 :     } else {
      58         [ -  + ]:      76464 :         POSIX_GUARD(s2n_hmac_update(mac, &header->content_type, sizeof(header->content_type)));
      59         [ -  + ]:      76464 :         POSIX_GUARD(s2n_hmac_update_u16(mac, header->version));
      60         [ -  + ]:      76464 :         POSIX_GUARD(s2n_hmac_update_u16(mac, payload_length));
      61                 :      76464 :     }
      62                 :            : 
      63                 :      76826 :     struct s2n_blob seq = { .data = sequence_number, .size = S2N_TLS_SEQUENCE_NUM_LEN };
      64         [ -  + ]:      76826 :     POSIX_GUARD(s2n_increment_sequence_number(&seq));
      65                 :            : 
      66                 :            :     /* MAC check for streaming ciphers - no padding */
      67         [ -  + ]:      76826 :     POSIX_GUARD(s2n_hmac_update(mac, en.data, payload_length));
      68                 :            : 
      69                 :      76826 :     uint8_t check_digest[S2N_MAX_DIGEST_LEN] = { 0 };
      70 [ -  + ][ #  # ]:      76826 :     POSIX_ENSURE_LTE(mac_digest_size, sizeof(check_digest));
      71         [ -  + ]:      76826 :     POSIX_GUARD(s2n_hmac_digest(mac, check_digest, mac_digest_size));
      72                 :            : 
      73         [ +  + ]:      76826 :     if (s2n_hmac_digest_verify(en.data + payload_length, check_digest, mac_digest_size) < 0) {
      74         [ +  - ]:      16178 :         POSIX_BAIL(S2N_ERR_BAD_MESSAGE);
      75                 :      16178 :     }
      76                 :            : 
      77                 :            :     /* O.k., we've successfully read and decrypted the record, now we need to align the stuffer
      78                 :            :      * for reading the plaintext data.
      79                 :            :      */
      80         [ -  + ]:      60648 :     POSIX_GUARD(s2n_stuffer_reread(&conn->in));
      81                 :            : 
      82                 :            :     /* Truncate and wipe the MAC and any padding */
      83                 :      60648 :     uint32_t mac_len = 0;
      84         [ -  + ]:      60648 :     POSIX_GUARD(s2n_sub_overflow(s2n_stuffer_data_available(&conn->in), payload_length, &mac_len));
      85         [ -  + ]:      60648 :     POSIX_GUARD(s2n_stuffer_wipe_n(&conn->in, mac_len));
      86                 :      60648 :     conn->in_status = PLAINTEXT;
      87                 :            : 
      88                 :      60648 :     return 0;
      89                 :      60648 : }