/*
* Given a |secret|; a |label| of length |labellen|; and a |hash| of the
* handshake messages, derive a new secret |outlen| bytes long and store it in
* the location pointed to be |out|. The |hash| value may be NULL. Returns 1 on
* success 0 on failure.
*/
static int tls13_hkdf_expand(SSL *s, const unsigned char *secret,
const unsigned char *label, size_t labellen,
const unsigned char *hash,
unsigned char *out, size_t outlen)
{
const unsigned char label_prefix[] = "TLS 1.3, ";
const EVP_MD *md = ssl_handshake_md(s);
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
int ret;
size_t hkdflabellen;
size_t hashlen;
/*
* 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
* prefix and label + bytes for the label itself + bytes for the hash
*/
unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
+ EVP_MAX_MD_SIZE];
WPACKET pkt;
if (pctx == NULL)
return 0;
hashlen = EVP_MD_size(md);
if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
|| !WPACKET_put_bytes_u16(&pkt, outlen)
|| !WPACKET_start_sub_packet_u8(&pkt)
|| !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_close(&pkt)
|| !WPACKET_sub_memcpy_u8(&pkt, hash, (hash == NULL) ? 0 : hashlen)
|| !WPACKET_get_total_written(&pkt, &hkdflabellen)
|| !WPACKET_finish(&pkt)) {
WPACKET_cleanup(&pkt);
return 0;
}
ret = EVP_PKEY_derive_init(pctx) <= 0
|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
<= 0
|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
|| EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
|| EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
|| EVP_PKEY_derive(pctx, out, &outlen) <= 0;
EVP_PKEY_CTX_free(pctx);
return ret == 0;
}
/*
* Given a |secret|; a |label| of length |labellen|; and |data| of length
* |datalen| (e.g. typically a hash of the handshake messages), derive a new
* secret |outlen| bytes long and store it in the location pointed to be |out|.
* The |data| value may be zero length. Any errors will be treated as fatal if
* |fatal| is set. Returns 1 on success 0 on failure.
*/
int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
const unsigned char *label, size_t labellen,
const unsigned char *data, size_t datalen,
unsigned char *out, size_t outlen, int fatal)
{
static const unsigned char label_prefix[] = "tls13 ";
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
int ret;
size_t hkdflabellen;
size_t hashlen;
/*
* 2 bytes for length of derived secret + 1 byte for length of combined
* prefix and label + bytes for the label itself + 1 byte length of hash
* + bytes for the hash itself
*/
unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
+ 1 + EVP_MAX_MD_SIZE];
WPACKET pkt;
if (pctx == NULL)
return 0;
if (labellen > TLS13_MAX_LABEL_LEN) {
if (fatal) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
} else {
/*
* Probably we have been called from SSL_export_keying_material(),
* or SSL_export_keying_material_early().
*/
SSLerr(SSL_F_TLS13_HKDF_EXPAND, SSL_R_TLS_ILLEGAL_EXPORTER_LABEL);
}
EVP_PKEY_CTX_free(pctx);
return 0;
}
hashlen = EVP_MD_size(md);
if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
|| !WPACKET_put_bytes_u16(&pkt, outlen)
|| !WPACKET_start_sub_packet_u8(&pkt)
|| !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_close(&pkt)
|| !WPACKET_sub_memcpy_u8(&pkt, data, (data == NULL) ? 0 : datalen)
|| !WPACKET_get_total_written(&pkt, &hkdflabellen)
|| !WPACKET_finish(&pkt)) {
EVP_PKEY_CTX_free(pctx);
WPACKET_cleanup(&pkt);
if (fatal)
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
else
SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
return 0;
}
ret = EVP_PKEY_derive_init(pctx) <= 0
|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
<= 0
|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
|| EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
|| EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
|| EVP_PKEY_derive(pctx, out, &outlen) <= 0;
EVP_PKEY_CTX_free(pctx);
if (ret != 0) {
if (fatal)
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
else
SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
}
return ret == 0;
}
/*-
* tls13_enc encrypts/decrypts |n_recs| in |recs|. Will call SSLfatal() for
* internal errors, but not otherwise.
*
* Returns:
* 0: (in non-constant time) if the record is publically invalid (i.e. too
* short etc).
* 1: if the record encryption was successful.
* -1: if the record's AEAD-authenticator is invalid or, if sending,
* an internal error occurred.
*/
int tls13_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int sending)
{
EVP_CIPHER_CTX *ctx;
unsigned char iv[EVP_MAX_IV_LENGTH], recheader[SSL3_RT_HEADER_LENGTH];
size_t ivlen, taglen, offset, loop, hdrlen;
unsigned char *staticiv;
unsigned char *seq;
int lenu, lenf;
SSL3_RECORD *rec = &recs[0];
uint32_t alg_enc;
WPACKET wpkt;
if (n_recs != 1) {
/* Should not happen */
/* TODO(TLS1.3): Support pipelining */
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
if (sending) {
ctx = s->enc_write_ctx;
staticiv = s->write_iv;
seq = RECORD_LAYER_get_write_sequence(&s->rlayer);
} else {
ctx = s->enc_read_ctx;
staticiv = s->read_iv;
seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
}
/*
* If we're sending an alert and ctx != NULL then we must be forcing
* plaintext alerts. If we're reading and ctx != NULL then we allow
* plaintext alerts at certain points in the handshake. If we've got this
* far then we have already validated that a plaintext alert is ok here.
*/
if (ctx == NULL || rec->type == SSL3_RT_ALERT) {
memmove(rec->data, rec->input, rec->length);
rec->input = rec->data;
return 1;
}
ivlen = EVP_CIPHER_CTX_iv_length(ctx);
if (s->early_data_state == SSL_EARLY_DATA_WRITING
|| s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {
if (s->session != NULL && s->session->ext.max_early_data > 0) {
alg_enc = s->session->cipher->algorithm_enc;
} else {
if (!ossl_assert(s->psksession != NULL
&& s->psksession->ext.max_early_data > 0)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
alg_enc = s->psksession->cipher->algorithm_enc;
}
} else {
/*
* To get here we must have selected a ciphersuite - otherwise ctx would
* be NULL
*/
if (!ossl_assert(s->s3->tmp.new_cipher != NULL)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
alg_enc = s->s3->tmp.new_cipher->algorithm_enc;
}
if (alg_enc & SSL_AESCCM) {
if (alg_enc & (SSL_AES128CCM8 | SSL_AES256CCM8))
taglen = EVP_CCM8_TLS_TAG_LEN;
else
taglen = EVP_CCM_TLS_TAG_LEN;
if (sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen,
NULL) <= 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
} else if (alg_enc & SSL_AESGCM) {
taglen = EVP_GCM_TLS_TAG_LEN;
} else if (alg_enc & SSL_CHACHA20) {
taglen = EVP_CHACHAPOLY_TLS_TAG_LEN;
} else {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
if (!sending) {
/*
* Take off tag. There must be at least one byte of content type as
* well as the tag
*/
if (rec->length < taglen + 1)
return 0;
rec->length -= taglen;
}
/* Set up IV */
if (ivlen < SEQ_NUM_SIZE) {
/* Should not happen */
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
offset = ivlen - SEQ_NUM_SIZE;
memcpy(iv, staticiv, offset);
for (loop = 0; loop < SEQ_NUM_SIZE; loop++)
iv[offset + loop] = staticiv[offset + loop] ^ seq[loop];
/* Increment the sequence counter */
for (loop = SEQ_NUM_SIZE; loop > 0; loop--) {
++seq[loop - 1];
if (seq[loop - 1] != 0)
break;
}
if (loop == 0) {
/* Sequence has wrapped */
return -1;
}
/* TODO(size_t): lenu/lenf should be a size_t but EVP doesn't support it */
if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv, sending) <= 0
|| (!sending && EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG,
taglen,
rec->data + rec->length) <= 0)) {
return -1;
}
/* Set up the AAD */
if (!WPACKET_init_static_len(&wpkt, recheader, sizeof(recheader), 0)
|| !WPACKET_put_bytes_u8(&wpkt, rec->type)
|| !WPACKET_put_bytes_u16(&wpkt, rec->rec_version)
|| !WPACKET_put_bytes_u16(&wpkt, rec->length + taglen)
|| !WPACKET_get_total_written(&wpkt, &hdrlen)
|| hdrlen != SSL3_RT_HEADER_LENGTH
|| !WPACKET_finish(&wpkt)) {
WPACKET_cleanup(&wpkt);
return -1;
}
/*
* For CCM we must explicitly set the total plaintext length before we add
* any AAD.
*/
if (((alg_enc & SSL_AESCCM) != 0
&& EVP_CipherUpdate(ctx, NULL, &lenu, NULL,
(unsigned int)rec->length) <= 0)
|| EVP_CipherUpdate(ctx, NULL, &lenu, recheader,
sizeof(recheader)) <= 0
|| EVP_CipherUpdate(ctx, rec->data, &lenu, rec->input,
(unsigned int)rec->length) <= 0
|| EVP_CipherFinal_ex(ctx, rec->data + lenu, &lenf) <= 0
|| (size_t)(lenu + lenf) != rec->length) {
return -1;
}
if (sending) {
/* Add the tag */
if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen,
rec->data + rec->length) <= 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_ENC,
ERR_R_INTERNAL_ERROR);
return -1;
}
rec->length += taglen;
}
return 1;
}
