ssl/record/ssl3_record_tls13.c

   1 /*
   2  * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "../ssl_locl.h"
  11 #include "record_locl.h"
  12
  13 /*-
  14  * tls13_enc encrypts/decrypts |n_recs| in |recs|.
  15  *
  16  * Returns:
  17  *    0: (in non-constant time) if the record is publically invalid (i.e. too
  18  *        short etc).
  19  *    1: if the record encryption was successful.
  20  *   -1: if the record's AEAD-authenticator is invalid or, if sending,
  21  *       an internal error occurred.
  22  */
  23 int tls13_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int send)
  24 {
  25     EVP_CIPHER_CTX *ctx;
  26     unsigned char iv[EVP_MAX_IV_LENGTH];
  27     size_t ivlen, offset, loop;
  28     unsigned char *staticiv;
  29     unsigned char *seq;
  30     int lenu, lenf;
  31     SSL3_RECORD *rec = &recs[0];
  32
  33     if (n_recs != 1) {
  34         /* Should not happen */
  35         /* TODO(TLS1.3): Support pipelining */
  36         return -1;
  37     }
  38
  39     if (send) {
  40         ctx = s->enc_write_ctx;
  41         staticiv = s->write_iv;
  42         seq = RECORD_LAYER_get_write_sequence(&s->rlayer);
  43     } else {
  44         ctx = s->enc_read_ctx;
  45         staticiv = s->read_iv;
  46         seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
  47     }
  48
  49     if (ctx == NULL) {
  50         memmove(rec->data, rec->input, rec->length);
  51         rec->input = rec->data;
  52         return 1;
  53     }
  54     ivlen = EVP_CIPHER_CTX_iv_length(ctx);
  55
  56     if (!send) {
  57         /*
  58          * Take off tag. There must be at least one byte of content type as
  59          * well as the tag
  60          */
  61         /*
  62          * TODO(TLS1.3): We're going to need to figure out the tag len based on
  63          * the cipher. For now we just support GCM tags.
  64          * TODO(TLS1.3): When we've swapped over the record layer to TLSv1.3
  65          * then the length must be 1 + the tag len to account for the content
  66          * byte that we know must have been encrypted.
  67          */
  68         if (rec->length < EVP_GCM_TLS_TAG_LEN)
  69             return 0;
  70         rec->length -= EVP_GCM_TLS_TAG_LEN;
  71     }
  72
  73     /* Set up IV */
  74     if (ivlen < SEQ_NUM_SIZE) {
  75         /* Should not happen */
  76         return -1;
  77     }
  78     offset = ivlen - SEQ_NUM_SIZE;
  79     memcpy(iv, staticiv, offset);
  80     for (loop = 0; loop < SEQ_NUM_SIZE; loop++)
  81         iv[offset + loop] = staticiv[offset + loop] ^ seq[loop];
  82
  83     /* TODO(size_t): lenu/lenf should be a size_t but EVP doesn't support it */
  84     if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv, send) <= 0
  85             || EVP_CipherUpdate(ctx, rec->data, &lenu, rec->input,
  86                                 (unsigned int)rec->length) <= 0
  87             || (!send && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
  88                                              EVP_GCM_TLS_TAG_LEN,
  89                                              rec->data + rec->length) <= 0)
  90             || EVP_CipherFinal_ex(ctx, rec->data + lenu, &lenf) <= 0
  91             || (size_t)(lenu + lenf) != rec->length) {
  92         return -1;
  93     }
  94
  95     if (send) {
  96         /* Add the tag */
  97         if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, EVP_GCM_TLS_TAG_LEN,
  98                                 rec->data + rec->length) <= 0)
  99             return -1;
 100         rec->length += EVP_GCM_TLS_TAG_LEN;
 101     }
 102
 103     return 1;
 104 }