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Diffstat (limited to 'src/ssl/dtls_record.c')
| -rw-r--r-- | src/ssl/dtls_record.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/src/ssl/dtls_record.c b/src/ssl/dtls_record.c new file mode 100644 index 0000000..940494a --- /dev/null +++ b/src/ssl/dtls_record.c @@ -0,0 +1,308 @@ +/* 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" + + +/* 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, uint8_t *out, size_t *out_len, + size_t *out_consumed, uint8_t *out_alert, size_t max_out, const uint8_t *in, + size_t in_len) { + 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; + } + + if (ssl->msg_callback != NULL) { + ssl->msg_callback(0 /* read */, 0, SSL3_RT_HEADER, in, + DTLS1_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg); + } + + 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. */ + size_t plaintext_len; + if (!SSL_AEAD_CTX_open(ssl->aead_read_ctx, out, &plaintext_len, max_out, + type, version, sequence, 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; + } + + /* Check the plaintext length. */ + if (plaintext_len > 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. */ + + *out_type = type; + *out_len = plaintext_len; + *out_consumed = in_len - CBS_len(&cbs); + return ssl_open_record_success; +} + +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) { + /* Determine the parameters for the current epoch. */ + uint16_t epoch = ssl->d1->w_epoch; + SSL_AEAD_CTX *aead = ssl->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; + } + /* Check the record header does not alias any part of the input. + * |SSL_AEAD_CTX_seal| will internally enforce other aliasing requirements. */ + if (in < out + DTLS1_RT_HEADER_LENGTH && out < in + in_len) { + OPENSSL_PUT_ERROR(SSL, SSL_R_OUTPUT_ALIASES_INPUT); + 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; + 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) || + !ssl3_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; + + if (ssl->msg_callback) { + ssl->msg_callback(1 /* write */, 0, SSL3_RT_HEADER, out, + DTLS1_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg); + } + + return 1; +} |