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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"
BSSL_NAMESPACE_BEGIN
// dtls1_bitmap_should_discard returns one if |seq_num| has been seen in
// |bitmap| or is stale. Otherwise it returns zero.
static bool dtls1_bitmap_should_discard(DTLS1_BITMAP *bitmap,
uint64_t seq_num) {
const unsigned kWindowSize = sizeof(bitmap->map) * 8;
if (seq_num > bitmap->max_seq_num) {
return false;
}
uint64_t idx = bitmap->max_seq_num - seq_num;
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, uint64_t seq_num) {
const unsigned kWindowSize = sizeof(bitmap->map) * 8;
// Shift the window if necessary.
if (seq_num > bitmap->max_seq_num) {
uint64_t shift = seq_num - bitmap->max_seq_num;
if (shift >= kWindowSize) {
bitmap->map = 0;
} else {
bitmap->map <<= shift;
}
bitmap->max_seq_num = seq_num;
}
uint64_t idx = bitmap->max_seq_num - seq_num;
if (idx < kWindowSize) {
bitmap->map |= ((uint64_t)1) << idx;
}
}
enum ssl_open_record_t dtls_open_record(SSL *ssl, uint8_t *out_type,
Span<uint8_t> *out,
size_t *out_consumed,
uint8_t *out_alert, Span<uint8_t> in) {
*out_consumed = 0;
if (ssl->s3->read_shutdown == ssl_shutdown_close_notify) {
return ssl_open_record_close_notify;
}
if (in.empty()) {
return ssl_open_record_partial;
}
CBS cbs = CBS(in);
// Decode the record.
uint8_t type;
uint16_t version;
uint8_t sequence_bytes[8];
CBS body;
if (!CBS_get_u8(&cbs, &type) ||
!CBS_get_u16(&cbs, &version) ||
!CBS_copy_bytes(&cbs, sequence_bytes, sizeof(sequence_bytes)) ||
!CBS_get_u16_length_prefixed(&cbs, &body) ||
CBS_len(&body) > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
// The record header was incomplete or malformed. Drop the entire packet.
*out_consumed = in.size();
return ssl_open_record_discard;
}
bool version_ok;
if (ssl->s3->aead_read_ctx->is_null_cipher()) {
// Only check the first byte. Enforcing beyond that can prevent decoding
// version negotiation failure alerts.
version_ok = (version >> 8) == DTLS1_VERSION_MAJOR;
} else {
version_ok = version == ssl->s3->aead_read_ctx->RecordVersion();
}
if (!version_ok) {
// The record header was incomplete or malformed. Drop the entire packet.
*out_consumed = in.size();
return ssl_open_record_discard;
}
Span<const uint8_t> header = in.subspan(0, DTLS1_RT_HEADER_LENGTH);
ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HEADER, header);
uint64_t sequence = CRYPTO_load_u64_be(sequence_bytes);
uint16_t epoch = static_cast<uint16_t>(sequence >> 48);
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.size() - CBS_len(&cbs);
return ssl_open_record_discard;
}
// discard the body in-place.
if (!ssl->s3->aead_read_ctx->Open(
out, type, version, sequence, header,
MakeSpan(const_cast<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.size() - CBS_len(&cbs);
return ssl_open_record_discard;
}
*out_consumed = in.size() - CBS_len(&cbs);
// Check the plaintext length.
if (out->size() > 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, *out);
}
ssl->s3->warning_alert_count = 0;
*out_type = type;
return ssl_open_record_success;
}
static const SSLAEADContext *get_write_aead(const SSL *ssl,
enum dtls1_use_epoch_t use_epoch) {
if (use_epoch == dtls1_use_previous_epoch) {
assert(ssl->d1->w_epoch >= 1);
return ssl->d1->last_aead_write_ctx.get();
}
return ssl->s3->aead_write_ctx.get();
}
size_t dtls_max_seal_overhead(const SSL *ssl,
enum dtls1_use_epoch_t use_epoch) {
return DTLS1_RT_HEADER_LENGTH + get_write_aead(ssl, use_epoch)->MaxOverhead();
}
size_t dtls_seal_prefix_len(const SSL *ssl, enum dtls1_use_epoch_t use_epoch) {
return DTLS1_RT_HEADER_LENGTH +
get_write_aead(ssl, use_epoch)->ExplicitNonceLen();
}
bool 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 false;
}
// Determine the parameters for the current epoch.
uint16_t epoch = ssl->d1->w_epoch;
SSLAEADContext *aead = ssl->s3->aead_write_ctx.get();
uint64_t *seq = &ssl->s3->write_sequence;
if (use_epoch == dtls1_use_previous_epoch) {
assert(ssl->d1->w_epoch >= 1);
epoch = ssl->d1->w_epoch - 1;
aead = ssl->d1->last_aead_write_ctx.get();
seq = &ssl->d1->last_write_sequence;
}
if (max_out < DTLS1_RT_HEADER_LENGTH) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BUFFER_TOO_SMALL);
return false;
}
out[0] = type;
uint16_t record_version = ssl->s3->aead_write_ctx->RecordVersion();
out[1] = record_version >> 8;
out[2] = record_version & 0xff;
// Ensure the sequence number update does not overflow.
const uint64_t kMaxSequenceNumber = (uint64_t{1} << 48) - 1;
if (*seq + 1 > kMaxSequenceNumber) {
OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
return false;
}
uint64_t seq_with_epoch = (uint64_t{epoch} << 48) | *seq;
CRYPTO_store_u64_be(&out[3], seq_with_epoch);
size_t ciphertext_len;
if (!aead->CiphertextLen(&ciphertext_len, in_len, 0)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE);
return false;
}
out[11] = ciphertext_len >> 8;
out[12] = ciphertext_len & 0xff;
Span<const uint8_t> header = MakeConstSpan(out, DTLS1_RT_HEADER_LENGTH);
size_t len_copy;
if (!aead->Seal(out + DTLS1_RT_HEADER_LENGTH, &len_copy,
max_out - DTLS1_RT_HEADER_LENGTH, type, record_version,
seq_with_epoch, header, in, in_len)) {
return false;
}
assert(ciphertext_len == len_copy);
(*seq)++;
*out_len = DTLS1_RT_HEADER_LENGTH + ciphertext_len;
ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HEADER, header);
return true;
}
BSSL_NAMESPACE_END