|
- /* 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"
-
-
- namespace bssl {
-
- // 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,
- 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[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) ||
- 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;
- }
-
- ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HEADER,
- in.subspan(0, 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.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,
- 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();
- }
-
- 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;
- SSLAEADContext *aead = ssl->s3->aead_write_ctx.get();
- uint8_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 0;
- }
-
- out[0] = type;
-
- uint16_t record_version = ssl->s3->aead_write_ctx->RecordVersion();
- out[1] = record_version >> 8;
- out[2] = record_version & 0xff;
-
- out[3] = epoch >> 8;
- out[4] = epoch & 0xff;
- OPENSSL_memcpy(&out[5], &seq[2], 6);
-
- size_t ciphertext_len;
- if (!aead->Seal(out + DTLS1_RT_HEADER_LENGTH, &ciphertext_len,
- max_out - DTLS1_RT_HEADER_LENGTH, type, record_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,
- MakeSpan(out, DTLS1_RT_HEADER_LENGTH));
-
- return 1;
- }
-
- } // namespace bssl
|