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/* DTLS implementation written by Nagendra Modadugu
* (nagendra@cs.stanford.edu) for the OpenSSL project 2005. */
/* ====================================================================
* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/ssl.h>
#include <assert.h>
#include <string.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include "internal.h"
#include "../crypto/internal.h"
/* to_u64_be treats |in| as a 8-byte big-endian integer and returns the value as
* a |uint64_t|. */
static uint64_t to_u64_be(const uint8_t in[8]) {
uint64_t ret = 0;
unsigned i;
for (i = 0; i < 8; i++) {
ret <<= 8;
ret |= in[i];
}
return ret;
}
/* dtls1_bitmap_should_discard returns one if |seq_num| has been seen in |bitmap|
* or is stale. Otherwise it returns zero. */
static int dtls1_bitmap_should_discard(DTLS1_BITMAP *bitmap,
const uint8_t seq_num[8]) {
const unsigned kWindowSize = sizeof(bitmap->map) * 8;
uint64_t seq_num_u = to_u64_be(seq_num);
if (seq_num_u > bitmap->max_seq_num) {
return 0;
}
uint64_t idx = bitmap->max_seq_num - seq_num_u;
return idx >= kWindowSize || (bitmap->map & (((uint64_t)1) << idx));
}
/* dtls1_bitmap_record updates |bitmap| to record receipt of sequence number
* |seq_num|. It slides the window forward if needed. It is an error to call
* this function on a stale sequence number. */
static void dtls1_bitmap_record(DTLS1_BITMAP *bitmap,
const uint8_t seq_num[8]) {
const unsigned kWindowSize = sizeof(bitmap->map) * 8;
uint64_t seq_num_u = to_u64_be(seq_num);
/* Shift the window if necessary. */
if (seq_num_u > bitmap->max_seq_num) {
uint64_t shift = seq_num_u - bitmap->max_seq_num;
if (shift >= kWindowSize) {
bitmap->map = 0;
} else {
bitmap->map <<= shift;
}
bitmap->max_seq_num = seq_num_u;
}
uint64_t idx = bitmap->max_seq_num - seq_num_u;
if (idx < kWindowSize) {
bitmap->map |= ((uint64_t)1) << idx;
}
}
enum ssl_open_record_t dtls_open_record(SSL *ssl, uint8_t *out_type, CBS *out,
size_t *out_consumed,
uint8_t *out_alert, uint8_t *in,
size_t in_len) {
*out_consumed = 0;
CBS cbs;
CBS_init(&cbs, in, in_len);
/* Decode the record. */
uint8_t type;
uint16_t version;
uint8_t sequence[8];
CBS body;
if (!CBS_get_u8(&cbs, &type) ||
!CBS_get_u16(&cbs, &version) ||
!CBS_copy_bytes(&cbs, sequence, 8) ||
!CBS_get_u16_length_prefixed(&cbs, &body) ||
(ssl->s3->have_version && version != ssl->version) ||
(version >> 8) != DTLS1_VERSION_MAJOR ||
CBS_len(&body) > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
/* The record header was incomplete or malformed. Drop the entire packet. */
*out_consumed = in_len;
return ssl_open_record_discard;
}
ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HEADER, in,
DTLS1_RT_HEADER_LENGTH);
uint16_t epoch = (((uint16_t)sequence[0]) << 8) | sequence[1];
if (epoch != ssl->d1->r_epoch ||
dtls1_bitmap_should_discard(&ssl->d1->bitmap, sequence)) {
/* Drop this record. It's from the wrong epoch or is a replay. Note that if
* |epoch| is the next epoch, the record could be buffered for later. For
* simplicity, drop it and expect retransmit to handle it later; DTLS must
* handle packet loss anyway. */
*out_consumed = in_len - CBS_len(&cbs);
return ssl_open_record_discard;
}
/* Decrypt the body in-place. */
if (!SSL_AEAD_CTX_open(ssl->s3->aead_read_ctx, out, type, version, sequence,
(uint8_t *)CBS_data(&body), CBS_len(&body))) {
/* Bad packets are silently dropped in DTLS. See section 4.2.1 of RFC 6347.
* Clear the error queue of any errors decryption may have added. Drop the
* entire packet as it must not have come from the peer.
*
* TODO(davidben): This doesn't distinguish malloc failures from encryption
* failures. */
ERR_clear_error();
*out_consumed = in_len - CBS_len(&cbs);
return ssl_open_record_discard;
}
*out_consumed = in_len - CBS_len(&cbs);
/* Check the plaintext length. */
if (CBS_len(out) > SSL3_RT_MAX_PLAIN_LENGTH) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
*out_alert = SSL_AD_RECORD_OVERFLOW;
return ssl_open_record_error;
}
dtls1_bitmap_record(&ssl->d1->bitmap, sequence);
/* TODO(davidben): Limit the number of empty records as in TLS? This is only
* useful if we also limit discarded packets. */
if (type == SSL3_RT_ALERT) {
return ssl_process_alert(ssl, out_alert, CBS_data(out), CBS_len(out));
}
ssl->s3->warning_alert_count = 0;
*out_type = type;
return ssl_open_record_success;
}
static const SSL_AEAD_CTX *get_write_aead(const SSL *ssl,
enum dtls1_use_epoch_t use_epoch) {
if (use_epoch == dtls1_use_previous_epoch) {
/* DTLS renegotiation is unsupported, so only epochs 0 (NULL cipher) and 1
* (negotiated cipher) exist. */
assert(ssl->d1->w_epoch == 1);
return NULL;
}
return ssl->s3->aead_write_ctx;
}
size_t dtls_max_seal_overhead(const SSL *ssl,
enum dtls1_use_epoch_t use_epoch) {
return DTLS1_RT_HEADER_LENGTH +
SSL_AEAD_CTX_max_overhead(get_write_aead(ssl, use_epoch));
}
size_t dtls_seal_prefix_len(const SSL *ssl, enum dtls1_use_epoch_t use_epoch) {
return DTLS1_RT_HEADER_LENGTH +
SSL_AEAD_CTX_explicit_nonce_len(get_write_aead(ssl, use_epoch));
}
int dtls_seal_record(SSL *ssl, uint8_t *out, size_t *out_len, size_t max_out,
uint8_t type, const uint8_t *in, size_t in_len,
enum dtls1_use_epoch_t use_epoch) {
const size_t prefix = dtls_seal_prefix_len(ssl, use_epoch);
if (buffers_alias(in, in_len, out, max_out) &&
(max_out < prefix || out + prefix != in)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT);
return 0;
}
/* Determine the parameters for the current epoch. */
uint16_t epoch = ssl->d1->w_epoch;
SSL_AEAD_CTX *aead = ssl->s3->aead_write_ctx;
uint8_t *seq = ssl->s3->write_sequence;
if (use_epoch == dtls1_use_previous_epoch) {
/* DTLS renegotiation is unsupported, so only epochs 0 (NULL cipher) and 1
* (negotiated cipher) exist. */
assert(ssl->d1->w_epoch == 1);
epoch = ssl->d1->w_epoch - 1;
aead = NULL;
seq = ssl->d1->last_write_sequence;
}
if (max_out < DTLS1_RT_HEADER_LENGTH) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
return 0;
}
out[0] = type;
uint16_t wire_version = ssl->s3->have_version ? ssl->version : DTLS1_VERSION;
out[1] = wire_version >> 8;
out[2] = wire_version & 0xff;
out[3] = epoch >> 8;
out[4] = epoch & 0xff;
OPENSSL_memcpy(&out[5], &seq[2], 6);
size_t ciphertext_len;
if (!SSL_AEAD_CTX_seal(aead, out + DTLS1_RT_HEADER_LENGTH, &ciphertext_len,
max_out - DTLS1_RT_HEADER_LENGTH, type, wire_version,
&out[3] /* seq */, in, in_len) ||
!ssl_record_sequence_update(&seq[2], 6)) {
return 0;
}
if (ciphertext_len >= 1 << 16) {
OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
return 0;
}
out[11] = ciphertext_len >> 8;
out[12] = ciphertext_len & 0xff;
*out_len = DTLS1_RT_HEADER_LENGTH + ciphertext_len;
ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HEADER, out,
DTLS1_RT_HEADER_LENGTH);
return 1;
}