pineapple-src/externals/libressl/ssl/tls12_record_layer.c
2022-04-24 22:29:35 +02:00

1330 lines
31 KiB
C
Executable file

/* $OpenBSD: tls12_record_layer.c,v 1.36 2022/01/14 09:12:15 tb Exp $ */
/*
* Copyright (c) 2020 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <limits.h>
#include <stdlib.h>
#include <openssl/evp.h>
#include "ssl_locl.h"
#define TLS12_RECORD_SEQ_NUM_LEN 8
#define TLS12_AEAD_FIXED_NONCE_MAX_LEN 12
struct tls12_record_protection {
uint16_t epoch;
uint8_t seq_num[TLS12_RECORD_SEQ_NUM_LEN];
EVP_AEAD_CTX *aead_ctx;
uint8_t *aead_nonce;
size_t aead_nonce_len;
uint8_t *aead_fixed_nonce;
size_t aead_fixed_nonce_len;
size_t aead_variable_nonce_len;
size_t aead_tag_len;
int aead_xor_nonces;
int aead_variable_nonce_in_record;
EVP_CIPHER_CTX *cipher_ctx;
EVP_MD_CTX *hash_ctx;
int stream_mac;
uint8_t *mac_key;
size_t mac_key_len;
};
static struct tls12_record_protection *
tls12_record_protection_new(void)
{
return calloc(1, sizeof(struct tls12_record_protection));
}
static void
tls12_record_protection_clear(struct tls12_record_protection *rp)
{
EVP_AEAD_CTX_free(rp->aead_ctx);
freezero(rp->aead_nonce, rp->aead_nonce_len);
freezero(rp->aead_fixed_nonce, rp->aead_fixed_nonce_len);
EVP_CIPHER_CTX_free(rp->cipher_ctx);
EVP_MD_CTX_free(rp->hash_ctx);
freezero(rp->mac_key, rp->mac_key_len);
memset(rp, 0, sizeof(*rp));
}
static void
tls12_record_protection_free(struct tls12_record_protection *rp)
{
if (rp == NULL)
return;
tls12_record_protection_clear(rp);
freezero(rp, sizeof(struct tls12_record_protection));
}
static int
tls12_record_protection_engaged(struct tls12_record_protection *rp)
{
return rp->aead_ctx != NULL || rp->cipher_ctx != NULL;
}
static int
tls12_record_protection_unused(struct tls12_record_protection *rp)
{
return rp->aead_ctx == NULL && rp->cipher_ctx == NULL &&
rp->hash_ctx == NULL && rp->mac_key == NULL;
}
static int
tls12_record_protection_eiv_len(struct tls12_record_protection *rp,
size_t *out_eiv_len)
{
int eiv_len;
*out_eiv_len = 0;
if (rp->cipher_ctx == NULL)
return 0;
eiv_len = 0;
if (EVP_CIPHER_CTX_mode(rp->cipher_ctx) == EVP_CIPH_CBC_MODE)
eiv_len = EVP_CIPHER_CTX_iv_length(rp->cipher_ctx);
if (eiv_len < 0 || eiv_len > EVP_MAX_IV_LENGTH)
return 0;
*out_eiv_len = eiv_len;
return 1;
}
static int
tls12_record_protection_block_size(struct tls12_record_protection *rp,
size_t *out_block_size)
{
int block_size;
*out_block_size = 0;
if (rp->cipher_ctx == NULL)
return 0;
block_size = EVP_CIPHER_CTX_block_size(rp->cipher_ctx);
if (block_size < 0 || block_size > EVP_MAX_BLOCK_LENGTH)
return 0;
*out_block_size = block_size;
return 1;
}
static int
tls12_record_protection_mac_len(struct tls12_record_protection *rp,
size_t *out_mac_len)
{
int mac_len;
*out_mac_len = 0;
if (rp->hash_ctx == NULL)
return 0;
mac_len = EVP_MD_CTX_size(rp->hash_ctx);
if (mac_len <= 0 || mac_len > EVP_MAX_MD_SIZE)
return 0;
*out_mac_len = mac_len;
return 1;
}
struct tls12_record_layer {
uint16_t version;
uint16_t initial_epoch;
int dtls;
uint8_t alert_desc;
const EVP_AEAD *aead;
const EVP_CIPHER *cipher;
const EVP_MD *handshake_hash;
const EVP_MD *mac_hash;
/* Pointers to active record protection (memory is not owned). */
struct tls12_record_protection *read;
struct tls12_record_protection *write;
struct tls12_record_protection *read_current;
struct tls12_record_protection *write_current;
struct tls12_record_protection *write_previous;
};
struct tls12_record_layer *
tls12_record_layer_new(void)
{
struct tls12_record_layer *rl;
if ((rl = calloc(1, sizeof(struct tls12_record_layer))) == NULL)
goto err;
if ((rl->read_current = tls12_record_protection_new()) == NULL)
goto err;
if ((rl->write_current = tls12_record_protection_new()) == NULL)
goto err;
rl->read = rl->read_current;
rl->write = rl->write_current;
return rl;
err:
tls12_record_layer_free(rl);
return NULL;
}
void
tls12_record_layer_free(struct tls12_record_layer *rl)
{
if (rl == NULL)
return;
tls12_record_protection_free(rl->read_current);
tls12_record_protection_free(rl->write_current);
tls12_record_protection_free(rl->write_previous);
freezero(rl, sizeof(struct tls12_record_layer));
}
void
tls12_record_layer_alert(struct tls12_record_layer *rl, uint8_t *alert_desc)
{
*alert_desc = rl->alert_desc;
}
int
tls12_record_layer_write_overhead(struct tls12_record_layer *rl,
size_t *overhead)
{
size_t block_size, eiv_len, mac_len;
*overhead = 0;
if (rl->write->aead_ctx != NULL) {
*overhead = rl->write->aead_tag_len;
} else if (rl->write->cipher_ctx != NULL) {
eiv_len = 0;
if (rl->version != TLS1_VERSION) {
if (!tls12_record_protection_eiv_len(rl->write, &eiv_len))
return 0;
}
if (!tls12_record_protection_block_size(rl->write, &block_size))
return 0;
if (!tls12_record_protection_mac_len(rl->write, &mac_len))
return 0;
*overhead = eiv_len + block_size + mac_len;
}
return 1;
}
int
tls12_record_layer_read_protected(struct tls12_record_layer *rl)
{
return tls12_record_protection_engaged(rl->read);
}
int
tls12_record_layer_write_protected(struct tls12_record_layer *rl)
{
return tls12_record_protection_engaged(rl->write);
}
void
tls12_record_layer_set_aead(struct tls12_record_layer *rl, const EVP_AEAD *aead)
{
rl->aead = aead;
}
void
tls12_record_layer_set_cipher_hash(struct tls12_record_layer *rl,
const EVP_CIPHER *cipher, const EVP_MD *handshake_hash,
const EVP_MD *mac_hash)
{
rl->cipher = cipher;
rl->handshake_hash = handshake_hash;
rl->mac_hash = mac_hash;
}
void
tls12_record_layer_set_version(struct tls12_record_layer *rl, uint16_t version)
{
rl->version = version;
rl->dtls = ((version >> 8) == DTLS1_VERSION_MAJOR);
}
void
tls12_record_layer_set_initial_epoch(struct tls12_record_layer *rl,
uint16_t epoch)
{
rl->initial_epoch = epoch;
}
uint16_t
tls12_record_layer_read_epoch(struct tls12_record_layer *rl)
{
return rl->read->epoch;
}
uint16_t
tls12_record_layer_write_epoch(struct tls12_record_layer *rl)
{
return rl->write->epoch;
}
int
tls12_record_layer_use_write_epoch(struct tls12_record_layer *rl, uint16_t epoch)
{
if (rl->write->epoch == epoch)
return 1;
if (rl->write_current->epoch == epoch) {
rl->write = rl->write_current;
return 1;
}
if (rl->write_previous != NULL && rl->write_previous->epoch == epoch) {
rl->write = rl->write_previous;
return 1;
}
return 0;
}
void
tls12_record_layer_write_epoch_done(struct tls12_record_layer *rl, uint16_t epoch)
{
if (rl->write_previous == NULL || rl->write_previous->epoch != epoch)
return;
rl->write = rl->write_current;
tls12_record_protection_free(rl->write_previous);
rl->write_previous = NULL;
}
void
tls12_record_layer_clear_read_state(struct tls12_record_layer *rl)
{
tls12_record_protection_clear(rl->read);
rl->read->epoch = rl->initial_epoch;
}
void
tls12_record_layer_clear_write_state(struct tls12_record_layer *rl)
{
tls12_record_protection_clear(rl->write);
rl->write->epoch = rl->initial_epoch;
tls12_record_protection_free(rl->write_previous);
rl->write_previous = NULL;
}
void
tls12_record_layer_reflect_seq_num(struct tls12_record_layer *rl)
{
memcpy(rl->write->seq_num, rl->read->seq_num,
sizeof(rl->write->seq_num));
}
static const uint8_t tls12_max_seq_num[TLS12_RECORD_SEQ_NUM_LEN] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};
int
tls12_record_layer_inc_seq_num(struct tls12_record_layer *rl, uint8_t *seq_num)
{
CBS max_seq_num;
int i;
/*
* RFC 5246 section 6.1 and RFC 6347 section 4.1 - both TLS and DTLS
* sequence numbers must not wrap. Note that for DTLS the first two
* bytes are used as an "epoch" and not part of the sequence number.
*/
CBS_init(&max_seq_num, seq_num, TLS12_RECORD_SEQ_NUM_LEN);
if (rl->dtls) {
if (!CBS_skip(&max_seq_num, 2))
return 0;
}
if (CBS_mem_equal(&max_seq_num, tls12_max_seq_num,
CBS_len(&max_seq_num)))
return 0;
for (i = TLS12_RECORD_SEQ_NUM_LEN - 1; i >= 0; i--) {
if (++seq_num[i] != 0)
break;
}
return 1;
}
static int
tls12_record_layer_set_mac_key(struct tls12_record_protection *rp,
const uint8_t *mac_key, size_t mac_key_len)
{
freezero(rp->mac_key, rp->mac_key_len);
rp->mac_key = NULL;
rp->mac_key_len = 0;
if (mac_key == NULL || mac_key_len == 0)
return 1;
if ((rp->mac_key = calloc(1, mac_key_len)) == NULL)
return 0;
memcpy(rp->mac_key, mac_key, mac_key_len);
rp->mac_key_len = mac_key_len;
return 1;
}
static int
tls12_record_layer_ccs_aead(struct tls12_record_layer *rl,
struct tls12_record_protection *rp, int is_write, CBS *mac_key, CBS *key,
CBS *iv)
{
if (!tls12_record_protection_unused(rp))
return 0;
if ((rp->aead_ctx = EVP_AEAD_CTX_new()) == NULL)
return 0;
/* AES GCM cipher suites use variable nonce in record. */
if (rl->aead == EVP_aead_aes_128_gcm() ||
rl->aead == EVP_aead_aes_256_gcm())
rp->aead_variable_nonce_in_record = 1;
/* ChaCha20 Poly1305 XORs the fixed and variable nonces. */
if (rl->aead == EVP_aead_chacha20_poly1305())
rp->aead_xor_nonces = 1;
if (!CBS_stow(iv, &rp->aead_fixed_nonce, &rp->aead_fixed_nonce_len))
return 0;
rp->aead_nonce = calloc(1, EVP_AEAD_nonce_length(rl->aead));
if (rp->aead_nonce == NULL)
return 0;
rp->aead_nonce_len = EVP_AEAD_nonce_length(rl->aead);
rp->aead_tag_len = EVP_AEAD_max_overhead(rl->aead);
rp->aead_variable_nonce_len = TLS12_RECORD_SEQ_NUM_LEN;
if (rp->aead_xor_nonces) {
/* Fixed nonce length must match, variable must not exceed. */
if (rp->aead_fixed_nonce_len != rp->aead_nonce_len)
return 0;
if (rp->aead_variable_nonce_len > rp->aead_nonce_len)
return 0;
} else {
/* Concatenated nonce length must equal AEAD nonce length. */
if (rp->aead_fixed_nonce_len +
rp->aead_variable_nonce_len != rp->aead_nonce_len)
return 0;
}
if (!EVP_AEAD_CTX_init(rp->aead_ctx, rl->aead, CBS_data(key),
CBS_len(key), EVP_AEAD_DEFAULT_TAG_LENGTH, NULL))
return 0;
return 1;
}
static int
tls12_record_layer_ccs_cipher(struct tls12_record_layer *rl,
struct tls12_record_protection *rp, int is_write, CBS *mac_key, CBS *key,
CBS *iv)
{
EVP_PKEY *mac_pkey = NULL;
int gost_param_nid;
int mac_type;
int ret = 0;
if (!tls12_record_protection_unused(rp))
goto err;
mac_type = EVP_PKEY_HMAC;
rp->stream_mac = 0;
if (CBS_len(iv) > INT_MAX || CBS_len(key) > INT_MAX)
goto err;
if (EVP_CIPHER_iv_length(rl->cipher) != CBS_len(iv))
goto err;
if (EVP_CIPHER_key_length(rl->cipher) != CBS_len(key))
goto err;
/* Special handling for GOST... */
if (EVP_MD_type(rl->mac_hash) == NID_id_Gost28147_89_MAC) {
if (CBS_len(mac_key) != 32)
goto err;
mac_type = EVP_PKEY_GOSTIMIT;
rp->stream_mac = 1;
} else {
if (CBS_len(mac_key) > INT_MAX)
goto err;
if (EVP_MD_size(rl->mac_hash) != CBS_len(mac_key))
goto err;
}
if ((rp->cipher_ctx = EVP_CIPHER_CTX_new()) == NULL)
goto err;
if ((rp->hash_ctx = EVP_MD_CTX_new()) == NULL)
goto err;
if (!tls12_record_layer_set_mac_key(rp, CBS_data(mac_key),
CBS_len(mac_key)))
goto err;
if ((mac_pkey = EVP_PKEY_new_mac_key(mac_type, NULL, CBS_data(mac_key),
CBS_len(mac_key))) == NULL)
goto err;
if (!EVP_CipherInit_ex(rp->cipher_ctx, rl->cipher, NULL, CBS_data(key),
CBS_data(iv), is_write))
goto err;
if (EVP_DigestSignInit(rp->hash_ctx, NULL, rl->mac_hash, NULL,
mac_pkey) <= 0)
goto err;
/* More special handling for GOST... */
if (EVP_CIPHER_type(rl->cipher) == NID_gost89_cnt) {
gost_param_nid = NID_id_tc26_gost_28147_param_Z;
if (EVP_MD_type(rl->handshake_hash) == NID_id_GostR3411_94)
gost_param_nid = NID_id_Gost28147_89_CryptoPro_A_ParamSet;
if (EVP_CIPHER_CTX_ctrl(rp->cipher_ctx, EVP_CTRL_GOST_SET_SBOX,
gost_param_nid, 0) <= 0)
goto err;
if (EVP_MD_type(rl->mac_hash) == NID_id_Gost28147_89_MAC) {
if (EVP_MD_CTX_ctrl(rp->hash_ctx, EVP_MD_CTRL_GOST_SET_SBOX,
gost_param_nid, 0) <= 0)
goto err;
}
}
ret = 1;
err:
EVP_PKEY_free(mac_pkey);
return ret;
}
static int
tls12_record_layer_change_cipher_state(struct tls12_record_layer *rl,
struct tls12_record_protection *rp, int is_write, CBS *mac_key, CBS *key,
CBS *iv)
{
if (rl->aead != NULL)
return tls12_record_layer_ccs_aead(rl, rp, is_write, mac_key,
key, iv);
return tls12_record_layer_ccs_cipher(rl, rp, is_write, mac_key,
key, iv);
}
int
tls12_record_layer_change_read_cipher_state(struct tls12_record_layer *rl,
CBS *mac_key, CBS *key, CBS *iv)
{
struct tls12_record_protection *read_new = NULL;
int ret = 0;
if ((read_new = tls12_record_protection_new()) == NULL)
goto err;
/* Read sequence number gets reset to zero. */
/* DTLS epoch is incremented and is permitted to wrap. */
if (rl->dtls)
read_new->epoch = rl->read_current->epoch + 1;
if (!tls12_record_layer_change_cipher_state(rl, read_new, 0,
mac_key, key, iv))
goto err;
tls12_record_protection_free(rl->read_current);
rl->read = rl->read_current = read_new;
read_new = NULL;
ret = 1;
err:
tls12_record_protection_free(read_new);
return ret;
}
int
tls12_record_layer_change_write_cipher_state(struct tls12_record_layer *rl,
CBS *mac_key, CBS *key, CBS *iv)
{
struct tls12_record_protection *write_new;
int ret = 0;
if ((write_new = tls12_record_protection_new()) == NULL)
goto err;
/* Write sequence number gets reset to zero. */
/* DTLS epoch is incremented and is permitted to wrap. */
if (rl->dtls)
write_new->epoch = rl->write_current->epoch + 1;
if (!tls12_record_layer_change_cipher_state(rl, write_new, 1,
mac_key, key, iv))
goto err;
if (rl->dtls) {
tls12_record_protection_free(rl->write_previous);
rl->write_previous = rl->write_current;
rl->write_current = NULL;
}
tls12_record_protection_free(rl->write_current);
rl->write = rl->write_current = write_new;
write_new = NULL;
ret = 1;
err:
tls12_record_protection_free(write_new);
return ret;
}
static int
tls12_record_layer_build_seq_num(struct tls12_record_layer *rl, CBB *cbb,
uint16_t epoch, uint8_t *seq_num, size_t seq_num_len)
{
CBS seq;
CBS_init(&seq, seq_num, seq_num_len);
if (rl->dtls) {
if (!CBB_add_u16(cbb, epoch))
return 0;
if (!CBS_skip(&seq, 2))
return 0;
}
return CBB_add_bytes(cbb, CBS_data(&seq), CBS_len(&seq));
}
static int
tls12_record_layer_pseudo_header(struct tls12_record_layer *rl,
uint8_t content_type, uint16_t record_len, CBS *seq_num, uint8_t **out,
size_t *out_len)
{
CBB cbb;
*out = NULL;
*out_len = 0;
/* Build the pseudo-header used for MAC/AEAD. */
if (!CBB_init(&cbb, 13))
goto err;
if (!CBB_add_bytes(&cbb, CBS_data(seq_num), CBS_len(seq_num)))
goto err;
if (!CBB_add_u8(&cbb, content_type))
goto err;
if (!CBB_add_u16(&cbb, rl->version))
goto err;
if (!CBB_add_u16(&cbb, record_len))
goto err;
if (!CBB_finish(&cbb, out, out_len))
goto err;
return 1;
err:
CBB_cleanup(&cbb);
return 0;
}
static int
tls12_record_layer_mac(struct tls12_record_layer *rl, CBB *cbb,
EVP_MD_CTX *hash_ctx, int stream_mac, CBS *seq_num, uint8_t content_type,
const uint8_t *content, size_t content_len, size_t *out_len)
{
EVP_MD_CTX *mac_ctx = NULL;
uint8_t *header = NULL;
size_t header_len = 0;
size_t mac_len;
uint8_t *mac;
int ret = 0;
if ((mac_ctx = EVP_MD_CTX_new()) == NULL)
goto err;
if (!EVP_MD_CTX_copy(mac_ctx, hash_ctx))
goto err;
if (!tls12_record_layer_pseudo_header(rl, content_type, content_len,
seq_num, &header, &header_len))
goto err;
if (EVP_DigestSignUpdate(mac_ctx, header, header_len) <= 0)
goto err;
if (EVP_DigestSignUpdate(mac_ctx, content, content_len) <= 0)
goto err;
if (EVP_DigestSignFinal(mac_ctx, NULL, &mac_len) <= 0)
goto err;
if (!CBB_add_space(cbb, &mac, mac_len))
goto err;
if (EVP_DigestSignFinal(mac_ctx, mac, &mac_len) <= 0)
goto err;
if (mac_len == 0)
goto err;
if (stream_mac) {
if (!EVP_MD_CTX_copy(hash_ctx, mac_ctx))
goto err;
}
*out_len = mac_len;
ret = 1;
err:
EVP_MD_CTX_free(mac_ctx);
freezero(header, header_len);
return ret;
}
static int
tls12_record_layer_read_mac_cbc(struct tls12_record_layer *rl, CBB *cbb,
uint8_t content_type, CBS *seq_num, const uint8_t *content,
size_t content_len, size_t mac_len, size_t padding_len)
{
uint8_t *header = NULL;
size_t header_len = 0;
uint8_t *mac = NULL;
size_t out_mac_len = 0;
int ret = 0;
/*
* Must be constant time to avoid leaking details about CBC padding.
*/
if (!ssl3_cbc_record_digest_supported(rl->read->hash_ctx))
goto err;
if (!tls12_record_layer_pseudo_header(rl, content_type, content_len,
seq_num, &header, &header_len))
goto err;
if (!CBB_add_space(cbb, &mac, mac_len))
goto err;
if (!ssl3_cbc_digest_record(rl->read->hash_ctx, mac, &out_mac_len, header,
content, content_len + mac_len, content_len + mac_len + padding_len,
rl->read->mac_key, rl->read->mac_key_len))
goto err;
if (mac_len != out_mac_len)
goto err;
ret = 1;
err:
freezero(header, header_len);
return ret;
}
static int
tls12_record_layer_read_mac(struct tls12_record_layer *rl, CBB *cbb,
uint8_t content_type, CBS *seq_num, const uint8_t *content,
size_t content_len)
{
EVP_CIPHER_CTX *enc = rl->read->cipher_ctx;
size_t out_len;
if (EVP_CIPHER_CTX_mode(enc) == EVP_CIPH_CBC_MODE)
return 0;
return tls12_record_layer_mac(rl, cbb, rl->read->hash_ctx,
rl->read->stream_mac, seq_num, content_type, content, content_len,
&out_len);
}
static int
tls12_record_layer_write_mac(struct tls12_record_layer *rl, CBB *cbb,
uint8_t content_type, CBS *seq_num, const uint8_t *content,
size_t content_len, size_t *out_len)
{
return tls12_record_layer_mac(rl, cbb, rl->write->hash_ctx,
rl->write->stream_mac, seq_num, content_type, content, content_len,
out_len);
}
static int
tls12_record_layer_aead_concat_nonce(struct tls12_record_layer *rl,
struct tls12_record_protection *rp, CBS *seq_num)
{
CBB cbb;
if (rp->aead_variable_nonce_len > CBS_len(seq_num))
return 0;
/* Fixed nonce and variable nonce (sequence number) are concatenated. */
if (!CBB_init_fixed(&cbb, rp->aead_nonce, rp->aead_nonce_len))
goto err;
if (!CBB_add_bytes(&cbb, rp->aead_fixed_nonce,
rp->aead_fixed_nonce_len))
goto err;
if (!CBB_add_bytes(&cbb, CBS_data(seq_num),
rp->aead_variable_nonce_len))
goto err;
if (!CBB_finish(&cbb, NULL, NULL))
goto err;
return 1;
err:
CBB_cleanup(&cbb);
return 0;
}
static int
tls12_record_layer_aead_xored_nonce(struct tls12_record_layer *rl,
struct tls12_record_protection *rp, CBS *seq_num)
{
uint8_t *pad;
CBB cbb;
int i;
if (rp->aead_variable_nonce_len > CBS_len(seq_num))
return 0;
if (rp->aead_fixed_nonce_len < rp->aead_variable_nonce_len)
return 0;
if (rp->aead_fixed_nonce_len != rp->aead_nonce_len)
return 0;
/*
* Variable nonce (sequence number) is right padded, before the fixed
* nonce is XOR'd in.
*/
if (!CBB_init_fixed(&cbb, rp->aead_nonce, rp->aead_nonce_len))
goto err;
if (!CBB_add_space(&cbb, &pad,
rp->aead_fixed_nonce_len - rp->aead_variable_nonce_len))
goto err;
if (!CBB_add_bytes(&cbb, CBS_data(seq_num),
rp->aead_variable_nonce_len))
goto err;
if (!CBB_finish(&cbb, NULL, NULL))
goto err;
for (i = 0; i < rp->aead_fixed_nonce_len; i++)
rp->aead_nonce[i] ^= rp->aead_fixed_nonce[i];
return 1;
err:
CBB_cleanup(&cbb);
return 0;
}
static int
tls12_record_layer_open_record_plaintext(struct tls12_record_layer *rl,
uint8_t content_type, CBS *fragment, uint8_t **out, size_t *out_len)
{
if (tls12_record_protection_engaged(rl->read))
return 0;
/* XXX - decrypt/process in place for now. */
*out = (uint8_t *)CBS_data(fragment);
*out_len = CBS_len(fragment);
return 1;
}
static int
tls12_record_layer_open_record_protected_aead(struct tls12_record_layer *rl,
uint8_t content_type, CBS *seq_num, CBS *fragment, uint8_t **out,
size_t *out_len)
{
struct tls12_record_protection *rp = rl->read;
uint8_t *header = NULL;
size_t header_len = 0;
uint8_t *plain;
size_t plain_len;
CBS var_nonce;
int ret = 0;
if (rp->aead_xor_nonces) {
if (!tls12_record_layer_aead_xored_nonce(rl, rp, seq_num))
goto err;
} else if (rp->aead_variable_nonce_in_record) {
if (!CBS_get_bytes(fragment, &var_nonce,
rp->aead_variable_nonce_len))
goto err;
if (!tls12_record_layer_aead_concat_nonce(rl, rp, &var_nonce))
goto err;
} else {
if (!tls12_record_layer_aead_concat_nonce(rl, rp, seq_num))
goto err;
}
/* XXX EVP_AEAD_max_tag_len vs EVP_AEAD_CTX_tag_len. */
if (CBS_len(fragment) < rp->aead_tag_len) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
if (CBS_len(fragment) > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
rl->alert_desc = SSL_AD_RECORD_OVERFLOW;
goto err;
}
/* XXX - decrypt/process in place for now. */
plain = (uint8_t *)CBS_data(fragment);
plain_len = CBS_len(fragment) - rp->aead_tag_len;
if (!tls12_record_layer_pseudo_header(rl, content_type, plain_len,
seq_num, &header, &header_len))
goto err;
if (!EVP_AEAD_CTX_open(rp->aead_ctx, plain, out_len, plain_len,
rp->aead_nonce, rp->aead_nonce_len, CBS_data(fragment),
CBS_len(fragment), header, header_len)) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
if (*out_len > SSL3_RT_MAX_PLAIN_LENGTH) {
rl->alert_desc = SSL_AD_RECORD_OVERFLOW;
goto err;
}
if (*out_len != plain_len)
goto err;
*out = plain;
ret = 1;
err:
freezero(header, header_len);
return ret;
}
static int
tls12_record_layer_open_record_protected_cipher(struct tls12_record_layer *rl,
uint8_t content_type, CBS *seq_num, CBS *fragment, uint8_t **out,
size_t *out_len)
{
EVP_CIPHER_CTX *enc = rl->read->cipher_ctx;
SSL3_RECORD_INTERNAL rrec;
size_t block_size, eiv_len;
uint8_t *mac = NULL;
size_t mac_len = 0;
uint8_t *out_mac = NULL;
size_t out_mac_len = 0;
uint8_t *plain;
size_t plain_len;
size_t min_len;
CBB cbb_mac;
int ret = 0;
memset(&cbb_mac, 0, sizeof(cbb_mac));
memset(&rrec, 0, sizeof(rrec));
if (!tls12_record_protection_block_size(rl->read, &block_size))
goto err;
/* Determine explicit IV length. */
eiv_len = 0;
if (rl->version != TLS1_VERSION) {
if (!tls12_record_protection_eiv_len(rl->read, &eiv_len))
goto err;
}
mac_len = 0;
if (rl->read->hash_ctx != NULL) {
if (!tls12_record_protection_mac_len(rl->read, &mac_len))
goto err;
}
/* CBC has at least one padding byte. */
min_len = eiv_len + mac_len;
if (EVP_CIPHER_CTX_mode(enc) == EVP_CIPH_CBC_MODE)
min_len += 1;
if (CBS_len(fragment) < min_len) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
if (CBS_len(fragment) > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
rl->alert_desc = SSL_AD_RECORD_OVERFLOW;
goto err;
}
if (CBS_len(fragment) % block_size != 0) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
/* XXX - decrypt/process in place for now. */
plain = (uint8_t *)CBS_data(fragment);
plain_len = CBS_len(fragment);
if (!EVP_Cipher(enc, plain, CBS_data(fragment), plain_len))
goto err;
rrec.data = plain;
rrec.input = plain;
rrec.length = plain_len;
/*
* We now have to remove padding, extract MAC, calculate MAC
* and compare MAC in constant time.
*/
if (block_size > 1)
ssl3_cbc_remove_padding(&rrec, eiv_len, mac_len);
if ((mac = calloc(1, mac_len)) == NULL)
goto err;
if (!CBB_init(&cbb_mac, EVP_MAX_MD_SIZE))
goto err;
if (EVP_CIPHER_CTX_mode(enc) == EVP_CIPH_CBC_MODE) {
ssl3_cbc_copy_mac(mac, &rrec, mac_len, rrec.length +
rrec.padding_length);
rrec.length -= mac_len;
if (!tls12_record_layer_read_mac_cbc(rl, &cbb_mac, content_type,
seq_num, rrec.input, rrec.length, mac_len,
rrec.padding_length))
goto err;
} else {
rrec.length -= mac_len;
memcpy(mac, rrec.data + rrec.length, mac_len);
if (!tls12_record_layer_read_mac(rl, &cbb_mac, content_type,
seq_num, rrec.input, rrec.length))
goto err;
}
if (!CBB_finish(&cbb_mac, &out_mac, &out_mac_len))
goto err;
if (mac_len != out_mac_len)
goto err;
if (timingsafe_memcmp(mac, out_mac, mac_len) != 0) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
if (rrec.length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_len) {
rl->alert_desc = SSL_AD_BAD_RECORD_MAC;
goto err;
}
if (rrec.length > SSL3_RT_MAX_PLAIN_LENGTH) {
rl->alert_desc = SSL_AD_RECORD_OVERFLOW;
goto err;
}
*out = rrec.data;
*out_len = rrec.length;
ret = 1;
err:
CBB_cleanup(&cbb_mac);
freezero(mac, mac_len);
freezero(out_mac, out_mac_len);
return ret;
}
int
tls12_record_layer_open_record(struct tls12_record_layer *rl, uint8_t *buf,
size_t buf_len, uint8_t **out, size_t *out_len)
{
CBS cbs, fragment, seq_num;
uint16_t version;
uint8_t content_type;
CBS_init(&cbs, buf, buf_len);
CBS_init(&seq_num, rl->read->seq_num, sizeof(rl->read->seq_num));
if (!CBS_get_u8(&cbs, &content_type))
return 0;
if (!CBS_get_u16(&cbs, &version))
return 0;
if (rl->dtls) {
/*
* The DTLS sequence number is split into a 16 bit epoch and
* 48 bit sequence number, however for the purposes of record
* processing it is treated the same as a TLS 64 bit sequence
* number. DTLS also uses explicit read sequence numbers, which
* we need to extract from the DTLS record header.
*/
if (!CBS_get_bytes(&cbs, &seq_num, SSL3_SEQUENCE_SIZE))
return 0;
if (!CBS_write_bytes(&seq_num, rl->read->seq_num,
sizeof(rl->read->seq_num), NULL))
return 0;
}
if (!CBS_get_u16_length_prefixed(&cbs, &fragment))
return 0;
if (rl->read->aead_ctx != NULL) {
if (!tls12_record_layer_open_record_protected_aead(rl,
content_type, &seq_num, &fragment, out, out_len))
return 0;
} else if (rl->read->cipher_ctx != NULL) {
if (!tls12_record_layer_open_record_protected_cipher(rl,
content_type, &seq_num, &fragment, out, out_len))
return 0;
} else {
if (!tls12_record_layer_open_record_plaintext(rl,
content_type, &fragment, out, out_len))
return 0;
}
if (!rl->dtls) {
if (!tls12_record_layer_inc_seq_num(rl, rl->read->seq_num))
return 0;
}
return 1;
}
static int
tls12_record_layer_seal_record_plaintext(struct tls12_record_layer *rl,
uint8_t content_type, const uint8_t *content, size_t content_len, CBB *out)
{
if (tls12_record_protection_engaged(rl->write))
return 0;
return CBB_add_bytes(out, content, content_len);
}
static int
tls12_record_layer_seal_record_protected_aead(struct tls12_record_layer *rl,
uint8_t content_type, CBS *seq_num, const uint8_t *content,
size_t content_len, CBB *out)
{
struct tls12_record_protection *rp = rl->write;
uint8_t *header = NULL;
size_t header_len = 0;
size_t enc_record_len, out_len;
uint8_t *enc_data;
int ret = 0;
if (rp->aead_xor_nonces) {
if (!tls12_record_layer_aead_xored_nonce(rl, rp, seq_num))
goto err;
} else {
if (!tls12_record_layer_aead_concat_nonce(rl, rp, seq_num))
goto err;
}
if (rp->aead_variable_nonce_in_record) {
if (rp->aead_variable_nonce_len > CBS_len(seq_num))
goto err;
if (!CBB_add_bytes(out, CBS_data(seq_num),
rp->aead_variable_nonce_len))
goto err;
}
if (!tls12_record_layer_pseudo_header(rl, content_type, content_len,
seq_num, &header, &header_len))
goto err;
/* XXX EVP_AEAD_max_tag_len vs EVP_AEAD_CTX_tag_len. */
enc_record_len = content_len + rp->aead_tag_len;
if (enc_record_len > SSL3_RT_MAX_ENCRYPTED_LENGTH)
goto err;
if (!CBB_add_space(out, &enc_data, enc_record_len))
goto err;
if (!EVP_AEAD_CTX_seal(rp->aead_ctx, enc_data, &out_len, enc_record_len,
rp->aead_nonce, rp->aead_nonce_len, content, content_len, header,
header_len))
goto err;
if (out_len != enc_record_len)
goto err;
ret = 1;
err:
freezero(header, header_len);
return ret;
}
static int
tls12_record_layer_seal_record_protected_cipher(struct tls12_record_layer *rl,
uint8_t content_type, CBS *seq_num, const uint8_t *content,
size_t content_len, CBB *out)
{
EVP_CIPHER_CTX *enc = rl->write->cipher_ctx;
size_t block_size, eiv_len, mac_len, pad_len;
uint8_t *enc_data, *eiv, *pad, pad_val;
uint8_t *plain = NULL;
size_t plain_len = 0;
int ret = 0;
CBB cbb;
if (!CBB_init(&cbb, SSL3_RT_MAX_PLAIN_LENGTH))
goto err;
/* Add explicit IV if necessary. */
eiv_len = 0;
if (rl->version != TLS1_VERSION) {
if (!tls12_record_protection_eiv_len(rl->write, &eiv_len))
goto err;
}
if (eiv_len > 0) {
if (!CBB_add_space(&cbb, &eiv, eiv_len))
goto err;
arc4random_buf(eiv, eiv_len);
}
if (!CBB_add_bytes(&cbb, content, content_len))
goto err;
mac_len = 0;
if (rl->write->hash_ctx != NULL) {
if (!tls12_record_layer_write_mac(rl, &cbb, content_type,
seq_num, content, content_len, &mac_len))
goto err;
}
plain_len = eiv_len + content_len + mac_len;
/* Add padding to block size, if necessary. */
if (!tls12_record_protection_block_size(rl->write, &block_size))
goto err;
if (block_size > 1) {
pad_len = block_size - (plain_len % block_size);
pad_val = pad_len - 1;
if (pad_len > 255)
goto err;
if (!CBB_add_space(&cbb, &pad, pad_len))
goto err;
memset(pad, pad_val, pad_len);
}
if (!CBB_finish(&cbb, &plain, &plain_len))
goto err;
if (plain_len % block_size != 0)
goto err;
if (plain_len > SSL3_RT_MAX_ENCRYPTED_LENGTH)
goto err;
if (!CBB_add_space(out, &enc_data, plain_len))
goto err;
if (!EVP_Cipher(enc, enc_data, plain, plain_len))
goto err;
ret = 1;
err:
CBB_cleanup(&cbb);
freezero(plain, plain_len);
return ret;
}
int
tls12_record_layer_seal_record(struct tls12_record_layer *rl,
uint8_t content_type, const uint8_t *content, size_t content_len, CBB *cbb)
{
uint8_t *seq_num_data = NULL;
size_t seq_num_len = 0;
CBB fragment, seq_num_cbb;
CBS seq_num;
int ret = 0;
/*
* Construct the effective sequence number - this is used in both
* the DTLS header and for MAC calculations.
*/
if (!CBB_init(&seq_num_cbb, SSL3_SEQUENCE_SIZE))
goto err;
if (!tls12_record_layer_build_seq_num(rl, &seq_num_cbb, rl->write->epoch,
rl->write->seq_num, sizeof(rl->write->seq_num)))
goto err;
if (!CBB_finish(&seq_num_cbb, &seq_num_data, &seq_num_len))
goto err;
CBS_init(&seq_num, seq_num_data, seq_num_len);
if (!CBB_add_u8(cbb, content_type))
goto err;
if (!CBB_add_u16(cbb, rl->version))
goto err;
if (rl->dtls) {
if (!CBB_add_bytes(cbb, CBS_data(&seq_num), CBS_len(&seq_num)))
goto err;
}
if (!CBB_add_u16_length_prefixed(cbb, &fragment))
goto err;
if (rl->write->aead_ctx != NULL) {
if (!tls12_record_layer_seal_record_protected_aead(rl,
content_type, &seq_num, content, content_len, &fragment))
goto err;
} else if (rl->write->cipher_ctx != NULL) {
if (!tls12_record_layer_seal_record_protected_cipher(rl,
content_type, &seq_num, content, content_len, &fragment))
goto err;
} else {
if (!tls12_record_layer_seal_record_plaintext(rl,
content_type, content, content_len, &fragment))
goto err;
}
if (!CBB_flush(cbb))
goto err;
if (!tls12_record_layer_inc_seq_num(rl, rl->write->seq_num))
goto err;
ret = 1;
err:
CBB_cleanup(&seq_num_cbb);
free(seq_num_data);
return ret;
}