ssl/record/ssl3_record_tls13.c

   1 /*
   2  * Copyright 2016-2018 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 #include "internal/cryptlib.h"
  13
  14 /*-
  15  * tls13_enc encrypts/decrypts |n_recs| in |recs|. Will call SSLfatal() for
  16  * internal errors, but not otherwise.
  17  *
  18  * Returns:
  19  *    0: (in non-constant time) if the record is publically invalid (i.e. too
  20  *        short etc).
  21  *    1: if the record encryption was successful.
  22  *   -1: if the record's AEAD-authenticator is invalid or, if sending,
  23  *       an internal error occurred.
  24  */
  25 int tls13_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int sending)
  26 {
  27     EVP_CIPHER_CTX *ctx;
  28     unsigned char iv[EVP_MAX_IV_LENGTH], recheader[SSL3_RT_HEADER_LENGTH];
  29     size_t ivlen, taglen, offset, loop, hdrlen;
  30     unsigned char *staticiv;
  31     unsigned char *seq;
  32     int lenu, lenf;
  33     SSL3_RECORD *rec = &recs[0];
  34     uint32_t alg_enc;
  35     WPACKET wpkt;
  36
  37     if (n_recs != 1) {
  38         /* Should not happen */
  39         /* TODO(TLS1.3): Support pipelining */
  40         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
  41                  ERR_R_INTERNAL_ERROR);
  42         return -1;
  43     }
  44
  45     if (sending) {
  46         ctx = s->enc_write_ctx;
  47         staticiv = s->write_iv;
  48         seq = RECORD_LAYER_get_write_sequence(&s->rlayer);
  49     } else {
  50         ctx = s->enc_read_ctx;
  51         staticiv = s->read_iv;
  52         seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
  53     }
  54
  55     if (ctx == NULL
  56             || (rec->type == SSL3_RT_ALERT
  57                 && s->statem.enc_write_state
  58                    == ENC_WRITE_STATE_WRITE_PLAIN_ALERTS)) {
  59         memmove(rec->data, rec->input, rec->length);
  60         rec->input = rec->data;
  61         return 1;
  62     }
  63
  64     ivlen = EVP_CIPHER_CTX_iv_length(ctx);
  65
  66     if (s->early_data_state == SSL_EARLY_DATA_WRITING
  67             || s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {
  68         if (s->session != NULL && s->session->ext.max_early_data > 0) {
  69             alg_enc = s->session->cipher->algorithm_enc;
  70         } else {
  71             if (!ossl_assert(s->psksession != NULL
  72                              && s->psksession->ext.max_early_data > 0)) {
  73                 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
  74                          ERR_R_INTERNAL_ERROR);
  75                 return -1;
  76             }
  77             alg_enc = s->psksession->cipher->algorithm_enc;
  78         }
  79     } else {
  80         /*
  81          * To get here we must have selected a ciphersuite - otherwise ctx would
  82          * be NULL
  83          */
  84         if (!ossl_assert(s->s3->tmp.new_cipher != NULL)) {
  85             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
  86                      ERR_R_INTERNAL_ERROR);
  87             return -1;
  88         }
  89         alg_enc = s->s3->tmp.new_cipher->algorithm_enc;
  90     }
  91
  92     if (alg_enc & SSL_AESCCM) {
  93         if (alg_enc & (SSL_AES128CCM8 | SSL_AES256CCM8))
  94             taglen = EVP_CCM8_TLS_TAG_LEN;
  95          else
  96             taglen = EVP_CCM_TLS_TAG_LEN;
  97          if (sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen,
  98                                          NULL) <= 0) {
  99             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 100                      ERR_R_INTERNAL_ERROR);
 101             return -1;
 102         }
 103     } else if (alg_enc & SSL_AESGCM) {
 104         taglen = EVP_GCM_TLS_TAG_LEN;
 105     } else if (alg_enc & SSL_CHACHA20) {
 106         taglen = EVP_CHACHAPOLY_TLS_TAG_LEN;
 107     } else {
 108         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 109                  ERR_R_INTERNAL_ERROR);
 110         return -1;
 111     }
 112
 113     if (!sending) {
 114         /*
 115          * Take off tag. There must be at least one byte of content type as
 116          * well as the tag
 117          */
 118         if (rec->length < taglen + 1)
 119             return 0;
 120         rec->length -= taglen;
 121     }
 122
 123     /* Set up IV */
 124     if (ivlen < SEQ_NUM_SIZE) {
 125         /* Should not happen */
 126         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 127                  ERR_R_INTERNAL_ERROR);
 128         return -1;
 129     }
 130     offset = ivlen - SEQ_NUM_SIZE;
 131     memcpy(iv, staticiv, offset);
 132     for (loop = 0; loop < SEQ_NUM_SIZE; loop++)
 133         iv[offset + loop] = staticiv[offset + loop] ^ seq[loop];
 134
 135     /* Increment the sequence counter */
 136     for (loop = SEQ_NUM_SIZE; loop > 0; loop--) {
 137         ++seq[loop - 1];
 138         if (seq[loop - 1] != 0)
 139             break;
 140     }
 141     if (loop == 0) {
 142         /* Sequence has wrapped */
 143         return -1;
 144     }
 145
 146     /* TODO(size_t): lenu/lenf should be a size_t but EVP doesn't support it */
 147     if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv, sending) <= 0
 148             || (!sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
 149                                              taglen,
 150                                              rec->data + rec->length) <= 0)) {
 151         return -1;
 152     }
 153
 154     /* Set up the AAD */
 155     if (!WPACKET_init_static_len(&wpkt, recheader, sizeof(recheader), 0)
 156             || !WPACKET_put_bytes_u8(&wpkt, rec->type)
 157             || !WPACKET_put_bytes_u16(&wpkt, rec->rec_version)
 158             || !WPACKET_put_bytes_u16(&wpkt, rec->length + taglen)
 159             || !WPACKET_get_total_written(&wpkt, &hdrlen)
 160             || hdrlen != SSL3_RT_HEADER_LENGTH
 161             || !WPACKET_finish(&wpkt)) {
 162         WPACKET_cleanup(&wpkt);
 163         return -1;
 164     }
 165
 166     /*
 167      * For CCM we must explicitly set the total plaintext length before we add
 168      * any AAD.
 169      */
 170     if (((alg_enc & SSL_AESCCM) != 0
 171                  && EVP_CipherUpdate(ctx, NULL, &lenu, NULL,
 172                                      (unsigned int)rec->length) <= 0)
 173             || EVP_CipherUpdate(ctx, NULL, &lenu, recheader,
 174                                 sizeof(recheader)) <= 0
 175             || EVP_CipherUpdate(ctx, rec->data, &lenu, rec->input,
 176                                 (unsigned int)rec->length) <= 0
 177             || EVP_CipherFinal_ex(ctx, rec->data + lenu, &lenf) <= 0
 178             || (size_t)(lenu + lenf) != rec->length) {
 179         return -1;
 180     }
 181     if (sending) {
 182         /* Add the tag */
 183         if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen,
 184                                 rec->data + rec->length) <= 0) {
 185             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 186                      ERR_R_INTERNAL_ERROR);
 187             return -1;
 188         }
 189         rec->length += taglen;
 190     }
 191
 192     return 1;
 193 }