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 publicly 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 */
25int 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}
197