104 lines
3.3 KiB
C
104 lines
3.3 KiB
C
/*
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* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include "../ssl_locl.h"
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#include "record_locl.h"
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/*-
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* tls13_enc encrypts/decrypts |n_recs| in |recs|.
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*
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* Returns:
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* 0: (in non-constant time) if the record is publically invalid (i.e. too
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* short etc).
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* 1: if the record encryption was successful.
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* -1: if the record's AEAD-authenticator is invalid or, if sending,
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* an internal error occurred.
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*/
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int tls13_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int send)
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{
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EVP_CIPHER_CTX *ctx;
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unsigned char iv[EVP_MAX_IV_LENGTH];
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size_t ivlen, offset, loop;
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unsigned char *staticiv;
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unsigned char *seq;
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int lenu, lenf;
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SSL3_RECORD *rec = &recs[0];
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if (n_recs != 1) {
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/* Should not happen */
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/* TODO(TLS1.3): Support pipelining */
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return -1;
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}
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if (send) {
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ctx = s->enc_write_ctx;
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staticiv = s->write_iv;
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seq = RECORD_LAYER_get_write_sequence(&s->rlayer);
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} else {
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ctx = s->enc_read_ctx;
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staticiv = s->read_iv;
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seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
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}
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if (ctx == NULL) {
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memmove(rec->data, rec->input, rec->length);
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rec->input = rec->data;
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return 1;
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}
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ivlen = EVP_CIPHER_CTX_iv_length(ctx);
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if (!send) {
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/*
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* Take off tag. There must be at least one byte of content type as
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* well as the tag
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*/
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/*
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* TODO(TLS1.3): We're going to need to figure out the tag len based on
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* the cipher. For now we just support GCM tags.
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* TODO(TLS1.3): When we've swapped over the record layer to TLSv1.3
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* then the length must be 1 + the tag len to account for the content
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* byte that we know must have been encrypted.
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*/
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if (rec->length < EVP_GCM_TLS_TAG_LEN)
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return 0;
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rec->length -= EVP_GCM_TLS_TAG_LEN;
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}
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/* Set up IV */
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if (ivlen < SEQ_NUM_SIZE) {
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/* Should not happen */
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return -1;
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}
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offset = ivlen - SEQ_NUM_SIZE;
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memcpy(iv, staticiv, offset);
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for (loop = 0; loop < SEQ_NUM_SIZE; loop++)
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iv[offset + loop] = staticiv[offset + loop] ^ seq[loop];
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/* TODO(size_t): lenu/lenf should be a size_t but EVP doesn't support it */
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if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv, send) <= 0
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|| EVP_CipherUpdate(ctx, rec->data, &lenu, rec->input,
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(unsigned int)rec->length) <= 0
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|| (!send && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
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EVP_GCM_TLS_TAG_LEN,
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rec->data + rec->length) <= 0)
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|| EVP_CipherFinal_ex(ctx, rec->data + lenu, &lenf) <= 0
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|| (size_t)(lenu + lenf) != rec->length) {
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return -1;
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}
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if (send) {
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/* Add the tag */
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if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, EVP_GCM_TLS_TAG_LEN,
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rec->data + rec->length) <= 0)
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return -1;
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rec->length += EVP_GCM_TLS_TAG_LEN;
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}
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return 1;
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}
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