| /* 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; |
| } |