ssl/record/ssl3_record_tls13.c

   1 /*
   2  * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (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_local.h"
  11 #include "record_local.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     /*
  56      * If we're sending an alert and ctx != NULL then we must be forcing
  57      * plaintext alerts. If we're reading and ctx != NULL then we allow
  58      * plaintext alerts at certain points in the handshake. If we've got this
  59      * far then we have already validated that a plaintext alert is ok here.
  60      */
  61     if (ctx == NULL || rec->type == SSL3_RT_ALERT) {
  62         memmove(rec->data, rec->input, rec->length);
  63         rec->input = rec->data;
  64         return 1;
  65     }
  66
  67     ivlen = EVP_CIPHER_CTX_iv_length(ctx);
  68
  69     if (s->early_data_state == SSL_EARLY_DATA_WRITING
  70             || s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {
  71         if (s->session != NULL && s->session->ext.max_early_data > 0) {
  72             alg_enc = s->session->cipher->algorithm_enc;
  73         } else {
  74             if (!ossl_assert(s->psksession != NULL
  75                              && s->psksession->ext.max_early_data > 0)) {
  76                 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
  77                          ERR_R_INTERNAL_ERROR);
  78                 return -1;
  79             }
  80             alg_enc = s->psksession->cipher->algorithm_enc;
  81         }
  82     } else {
  83         /*
  84          * To get here we must have selected a ciphersuite - otherwise ctx would
  85          * be NULL
  86          */
  87         if (!ossl_assert(s->s3.tmp.new_cipher != NULL)) {
  88             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
  89                      ERR_R_INTERNAL_ERROR);
  90             return -1;
  91         }
  92         alg_enc = s->s3.tmp.new_cipher->algorithm_enc;
  93     }
  94
  95     if (alg_enc & SSL_AESCCM) {
  96         if (alg_enc & (SSL_AES128CCM8 | SSL_AES256CCM8))
  97             taglen = EVP_CCM8_TLS_TAG_LEN;
  98          else
  99             taglen = EVP_CCM_TLS_TAG_LEN;
 100          if (sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen,
 101                                          NULL) <= 0) {
 102             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 103                      ERR_R_INTERNAL_ERROR);
 104             return -1;
 105         }
 106     } else if (alg_enc & SSL_AESGCM) {
 107         taglen = EVP_GCM_TLS_TAG_LEN;
 108     } else if (alg_enc & SSL_CHACHA20) {
 109         taglen = EVP_CHACHAPOLY_TLS_TAG_LEN;
 110     } else {
 111         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 112                  ERR_R_INTERNAL_ERROR);
 113         return -1;
 114     }
 115
 116     if (!sending) {
 117         /*
 118          * Take off tag. There must be at least one byte of content type as
 119          * well as the tag
 120          */
 121         if (rec->length < taglen + 1)
 122             return 0;
 123         rec->length -= taglen;
 124     }
 125
 126     /* Set up IV */
 127     if (ivlen < SEQ_NUM_SIZE) {
 128         /* Should not happen */
 129         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 130                  ERR_R_INTERNAL_ERROR);
 131         return -1;
 132     }
 133     offset = ivlen - SEQ_NUM_SIZE;
 134     memcpy(iv, staticiv, offset);
 135     for (loop = 0; loop < SEQ_NUM_SIZE; loop++)
 136         iv[offset + loop] = staticiv[offset + loop] ^ seq[loop];
 137
 138     /* Increment the sequence counter */
 139     for (loop = SEQ_NUM_SIZE; loop > 0; loop--) {
 140         ++seq[loop - 1];
 141         if (seq[loop - 1] != 0)
 142             break;
 143     }
 144     if (loop == 0) {
 145         /* Sequence has wrapped */
 146         return -1;
 147     }
 148
 149     /* TODO(size_t): lenu/lenf should be a size_t but EVP doesn't support it */
 150     if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv, sending) <= 0
 151             || (!sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
 152                                              taglen,
 153                                              rec->data + rec->length) <= 0)) {
 154         return -1;
 155     }
 156
 157     /* Set up the AAD */
 158     if (!WPACKET_init_static_len(&wpkt, recheader, sizeof(recheader), 0)
 159             || !WPACKET_put_bytes_u8(&wpkt, rec->type)
 160             || !WPACKET_put_bytes_u16(&wpkt, rec->rec_version)
 161             || !WPACKET_put_bytes_u16(&wpkt, rec->length + taglen)
 162             || !WPACKET_get_total_written(&wpkt, &hdrlen)
 163             || hdrlen != SSL3_RT_HEADER_LENGTH
 164             || !WPACKET_finish(&wpkt)) {
 165         WPACKET_cleanup(&wpkt);
 166         return -1;
 167     }
 168
 169     /*
 170      * For CCM we must explicitly set the total plaintext length before we add
 171      * any AAD.
 172      */
 173     if (((alg_enc & SSL_AESCCM) != 0
 174                  && EVP_CipherUpdate(ctx, NULL, &lenu, NULL,
 175                                      (unsigned int)rec->length) <= 0)
 176             || EVP_CipherUpdate(ctx, NULL, &lenu, recheader,
 177                                 sizeof(recheader)) <= 0
 178             || EVP_CipherUpdate(ctx, rec->data, &lenu, rec->input,
 179                                 (unsigned int)rec->length) <= 0
 180             || EVP_CipherFinal_ex(ctx, rec->data + lenu, &lenf) <= 0
 181             || (size_t)(lenu + lenf) != rec->length) {
 182         return -1;
 183     }
 184     if (sending) {
 185         /* Add the tag */
 186         if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen,
 187                                 rec->data + rec->length) <= 0) {
 188             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
 189                      ERR_R_INTERNAL_ERROR);
 190             return -1;
 191         }
 192         rec->length += taglen;
 193     }
 194
 195     return 1;
 196 }