/* * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include "../ssl_locl.h" #include "internal/constant_time_locl.h" #include #include "record_locl.h" #include "internal/cryptlib.h" static const unsigned char ssl3_pad_1[48] = { 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36 }; static const unsigned char ssl3_pad_2[48] = { 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c }; /* * Clear the contents of an SSL3_RECORD but retain any memory allocated */ void SSL3_RECORD_clear(SSL3_RECORD *r, size_t num_recs) { unsigned char *comp; size_t i; for (i = 0; i < num_recs; i++) { comp = r[i].comp; memset(&r[i], 0, sizeof(*r)); r[i].comp = comp; } } void SSL3_RECORD_release(SSL3_RECORD *r, size_t num_recs) { size_t i; for (i = 0; i < num_recs; i++) { OPENSSL_free(r[i].comp); r[i].comp = NULL; } } void SSL3_RECORD_set_seq_num(SSL3_RECORD *r, const unsigned char *seq_num) { memcpy(r->seq_num, seq_num, SEQ_NUM_SIZE); } /* * Peeks ahead into "read_ahead" data to see if we have a whole record waiting * for us in the buffer. */ static int ssl3_record_app_data_waiting(SSL *s) { SSL3_BUFFER *rbuf; size_t left, len; unsigned char *p; rbuf = RECORD_LAYER_get_rbuf(&s->rlayer); p = SSL3_BUFFER_get_buf(rbuf); if (p == NULL) return 0; left = SSL3_BUFFER_get_left(rbuf); if (left < SSL3_RT_HEADER_LENGTH) return 0; p += SSL3_BUFFER_get_offset(rbuf); /* * We only check the type and record length, we will sanity check version * etc later */ if (*p != SSL3_RT_APPLICATION_DATA) return 0; p += 3; n2s(p, len); if (left < SSL3_RT_HEADER_LENGTH + len) return 0; return 1; } int early_data_count_ok(SSL *s, size_t length, size_t overhead, int send) { uint32_t max_early_data = s->max_early_data; SSL_SESSION *sess = s->session; /* * If we are a client then we always use the max_early_data from the * session/psksession. Otherwise we go with the lowest out of the max early * data set in the session and the configured max_early_data. */ if (!s->server && sess->ext.max_early_data == 0) { if (!ossl_assert(s->psksession != NULL && s->psksession->ext.max_early_data > 0)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_EARLY_DATA_COUNT_OK, ERR_R_INTERNAL_ERROR); return 0; } sess = s->psksession; } if (!s->server || (s->hit && sess->ext.max_early_data < s->max_early_data)) max_early_data = sess->ext.max_early_data; if (max_early_data == 0) { SSLfatal(s, send ? SSL_AD_INTERNAL_ERROR : SSL_AD_UNEXPECTED_MESSAGE, SSL_F_EARLY_DATA_COUNT_OK, SSL_R_TOO_MUCH_EARLY_DATA); return 0; } /* If we are dealing with ciphertext we need to allow for the overhead */ max_early_data += overhead; if (s->early_data_count + length > max_early_data) { SSLfatal(s, send ? SSL_AD_INTERNAL_ERROR : SSL_AD_UNEXPECTED_MESSAGE, SSL_F_EARLY_DATA_COUNT_OK, SSL_R_TOO_MUCH_EARLY_DATA); return 0; } s->early_data_count += length; return 1; } /* * MAX_EMPTY_RECORDS defines the number of consecutive, empty records that * will be processed per call to ssl3_get_record. Without this limit an * attacker could send empty records at a faster rate than we can process and * cause ssl3_get_record to loop forever. */ #define MAX_EMPTY_RECORDS 32 #define SSL2_RT_HEADER_LENGTH 2 /*- * Call this to get new input records. * It will return <= 0 if more data is needed, normally due to an error * or non-blocking IO. * When it finishes, |numrpipes| records have been decoded. For each record 'i': * rr[i].type - is the type of record * rr[i].data, - data * rr[i].length, - number of bytes * Multiple records will only be returned if the record types are all * SSL3_RT_APPLICATION_DATA. The number of records returned will always be <= * |max_pipelines| */ /* used only by ssl3_read_bytes */ int ssl3_get_record(SSL *s) { int enc_err, rret; int i; size_t more, n; SSL3_RECORD *rr, *thisrr; SSL3_BUFFER *rbuf; SSL_SESSION *sess; unsigned char *p; unsigned char md[EVP_MAX_MD_SIZE]; unsigned int version; size_t mac_size; int imac_size; size_t num_recs = 0, max_recs, j; PACKET pkt, sslv2pkt; size_t first_rec_len; rr = RECORD_LAYER_get_rrec(&s->rlayer); rbuf = RECORD_LAYER_get_rbuf(&s->rlayer); max_recs = s->max_pipelines; if (max_recs == 0) max_recs = 1; sess = s->session; do { thisrr = &rr[num_recs]; /* check if we have the header */ if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) || (RECORD_LAYER_get_packet_length(&s->rlayer) < SSL3_RT_HEADER_LENGTH)) { size_t sslv2len; unsigned int type; rret = ssl3_read_n(s, SSL3_RT_HEADER_LENGTH, SSL3_BUFFER_get_len(rbuf), 0, num_recs == 0 ? 1 : 0, &n); if (rret <= 0) return rret; /* error or non-blocking */ RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY); p = RECORD_LAYER_get_packet(&s->rlayer); if (!PACKET_buf_init(&pkt, RECORD_LAYER_get_packet(&s->rlayer), RECORD_LAYER_get_packet_length(&s->rlayer))) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR); return -1; } sslv2pkt = pkt; if (!PACKET_get_net_2_len(&sslv2pkt, &sslv2len) || !PACKET_get_1(&sslv2pkt, &type)) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR); return -1; } /* * The first record received by the server may be a V2ClientHello. */ if (s->server && RECORD_LAYER_is_first_record(&s->rlayer) && (sslv2len & 0x8000) != 0 && (type == SSL2_MT_CLIENT_HELLO)) { /* * SSLv2 style record * * |num_recs| here will actually always be 0 because * |num_recs > 0| only ever occurs when we are processing * multiple app data records - which we know isn't the case here * because it is an SSLv2ClientHello. We keep it using * |num_recs| for the sake of consistency */ thisrr->type = SSL3_RT_HANDSHAKE; thisrr->rec_version = SSL2_VERSION; thisrr->length = sslv2len & 0x7fff; if (thisrr->length > SSL3_BUFFER_get_len(rbuf) - SSL2_RT_HEADER_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_PACKET_LENGTH_TOO_LONG); return -1; } if (thisrr->length < MIN_SSL2_RECORD_LEN) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT); return -1; } } else { /* SSLv3+ style record */ if (s->msg_callback) s->msg_callback(0, 0, SSL3_RT_HEADER, p, 5, s, s->msg_callback_arg); /* Pull apart the header into the SSL3_RECORD */ if (!PACKET_get_1(&pkt, &type) || !PACKET_get_net_2(&pkt, &version) || !PACKET_get_net_2_len(&pkt, &thisrr->length)) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR); return -1; } thisrr->type = type; thisrr->rec_version = version; /* * Lets check version. In TLSv1.3 we ignore this field. For the * ServerHello after an HRR we haven't actually selected TLSv1.3 * yet, but we still treat it as TLSv1.3, so we must check for * that explicitly */ if (!s->first_packet && !SSL_IS_TLS13(s) && s->hello_retry_request != SSL_HRR_PENDING && version != (unsigned int)s->version) { if ((s->version & 0xFF00) == (version & 0xFF00) && !s->enc_write_ctx && !s->write_hash) { if (thisrr->type == SSL3_RT_ALERT) { /* * The record is using an incorrect version number, * but what we've got appears to be an alert. We * haven't read the body yet to check whether its a * fatal or not - but chances are it is. We probably * shouldn't send a fatal alert back. We'll just * end. */ SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER); return -1; } /* * Send back error using their minor version number :-) */ s->version = (unsigned short)version; } SSLfatal(s, SSL_AD_PROTOCOL_VERSION, SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER); return -1; } if ((version >> 8) != SSL3_VERSION_MAJOR) { if (RECORD_LAYER_is_first_record(&s->rlayer)) { /* Go back to start of packet, look at the five bytes * that we have. */ p = RECORD_LAYER_get_packet(&s->rlayer); if (strncmp((char *)p, "GET ", 4) == 0 || strncmp((char *)p, "POST ", 5) == 0 || strncmp((char *)p, "HEAD ", 5) == 0 || strncmp((char *)p, "PUT ", 4) == 0) { SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD, SSL_R_HTTP_REQUEST); return -1; } else if (strncmp((char *)p, "CONNE", 5) == 0) { SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD, SSL_R_HTTPS_PROXY_REQUEST); return -1; } /* Doesn't look like TLS - don't send an alert */ SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER); return -1; } else { SSLfatal(s, SSL_AD_PROTOCOL_VERSION, SSL_F_SSL3_GET_RECORD, SSL_R_WRONG_VERSION_NUMBER); return -1; } } if (SSL_IS_TLS13(s) && s->enc_read_ctx != NULL && thisrr->type != SSL3_RT_APPLICATION_DATA && (thisrr->type != SSL3_RT_CHANGE_CIPHER_SPEC || !SSL_IS_FIRST_HANDSHAKE(s))) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_BAD_RECORD_TYPE); return -1; } if (thisrr->length > SSL3_BUFFER_get_len(rbuf) - SSL3_RT_HEADER_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_PACKET_LENGTH_TOO_LONG); return -1; } } /* now s->rlayer.rstate == SSL_ST_READ_BODY */ } if (SSL_IS_TLS13(s)) { if (thisrr->length > SSL3_RT_MAX_TLS13_ENCRYPTED_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG); return -1; } } else { size_t len = SSL3_RT_MAX_ENCRYPTED_LENGTH; #ifndef OPENSSL_NO_COMP /* * If OPENSSL_NO_COMP is defined then SSL3_RT_MAX_ENCRYPTED_LENGTH * does not include the compression overhead anyway. */ if (s->expand == NULL) len -= SSL3_RT_MAX_COMPRESSED_OVERHEAD; #endif if (thisrr->length > len) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG); return -1; } } /* * s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data. * Calculate how much more data we need to read for the rest of the * record */ if (thisrr->rec_version == SSL2_VERSION) { more = thisrr->length + SSL2_RT_HEADER_LENGTH - SSL3_RT_HEADER_LENGTH; } else { more = thisrr->length; } if (more > 0) { /* now s->packet_length == SSL3_RT_HEADER_LENGTH */ rret = ssl3_read_n(s, more, more, 1, 0, &n); if (rret <= 0) return rret; /* error or non-blocking io */ } /* set state for later operations */ RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER); /* * At this point, s->packet_length == SSL3_RT_HEADER_LENGTH * + thisrr->length, or s->packet_length == SSL2_RT_HEADER_LENGTH * + thisrr->length and we have that many bytes in s->packet */ if (thisrr->rec_version == SSL2_VERSION) { thisrr->input = &(RECORD_LAYER_get_packet(&s->rlayer)[SSL2_RT_HEADER_LENGTH]); } else { thisrr->input = &(RECORD_LAYER_get_packet(&s->rlayer)[SSL3_RT_HEADER_LENGTH]); } /* * ok, we can now read from 's->packet' data into 'thisrr' thisrr->input * points at thisrr->length bytes, which need to be copied into * thisrr->data by either the decryption or by the decompression When * the data is 'copied' into the thisrr->data buffer, thisrr->input will * be pointed at the new buffer */ /* * We now have - encrypted [ MAC [ compressed [ plain ] ] ] * thisrr->length bytes of encrypted compressed stuff. */ /* decrypt in place in 'thisrr->input' */ thisrr->data = thisrr->input; thisrr->orig_len = thisrr->length; /* Mark this record as not read by upper layers yet */ thisrr->read = 0; num_recs++; /* we have pulled in a full packet so zero things */ RECORD_LAYER_reset_packet_length(&s->rlayer); RECORD_LAYER_clear_first_record(&s->rlayer); } while (num_recs < max_recs && thisrr->type == SSL3_RT_APPLICATION_DATA && SSL_USE_EXPLICIT_IV(s) && s->enc_read_ctx != NULL && (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx)) & EVP_CIPH_FLAG_PIPELINE) && ssl3_record_app_data_waiting(s)); if (num_recs == 1 && thisrr->type == SSL3_RT_CHANGE_CIPHER_SPEC && (SSL_IS_TLS13(s) || s->hello_retry_request != SSL_HRR_NONE) && SSL_IS_FIRST_HANDSHAKE(s)) { /* * CCS messages must be exactly 1 byte long, containing the value 0x01 */ if (thisrr->length != 1 || thisrr->data[0] != 0x01) { SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_SSL3_GET_RECORD, SSL_R_INVALID_CCS_MESSAGE); return -1; } /* * CCS messages are ignored in TLSv1.3. We treat it like an empty * handshake record */ thisrr->type = SSL3_RT_HANDSHAKE; RECORD_LAYER_inc_empty_record_count(&s->rlayer); if (RECORD_LAYER_get_empty_record_count(&s->rlayer) > MAX_EMPTY_RECORDS) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_UNEXPECTED_CCS_MESSAGE); return -1; } thisrr->read = 1; RECORD_LAYER_set_numrpipes(&s->rlayer, 1); return 1; } /* * If in encrypt-then-mac mode calculate mac from encrypted record. All * the details below are public so no timing details can leak. */ if (SSL_READ_ETM(s) && s->read_hash) { unsigned char *mac; /* TODO(size_t): convert this to do size_t properly */ imac_size = EVP_MD_CTX_size(s->read_hash); if (!ossl_assert(imac_size >= 0 && imac_size <= EVP_MAX_MD_SIZE)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD, ERR_LIB_EVP); return -1; } mac_size = (size_t)imac_size; for (j = 0; j < num_recs; j++) { thisrr = &rr[j]; if (thisrr->length < mac_size) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT); return -1; } thisrr->length -= mac_size; mac = thisrr->data + thisrr->length; i = s->method->ssl3_enc->mac(s, thisrr, md, 0 /* not send */ ); if (i == 0 || CRYPTO_memcmp(md, mac, mac_size) != 0) { SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_SSL3_GET_RECORD, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC); return -1; } } } first_rec_len = rr[0].length; enc_err = s->method->ssl3_enc->enc(s, rr, num_recs, 0); /*- * enc_err is: * 0: (in non-constant time) if the record is publicly invalid. * 1: if the padding is valid * -1: if the padding is invalid */ if (enc_err == 0) { if (ossl_statem_in_error(s)) { /* SSLfatal() already got called */ return -1; } if (num_recs == 1 && ossl_statem_skip_early_data(s)) { /* * Valid early_data that we cannot decrypt might fail here as * publicly invalid. We treat it like an empty record. */ thisrr = &rr[0]; if (!early_data_count_ok(s, thisrr->length, EARLY_DATA_CIPHERTEXT_OVERHEAD, 0)) { /* SSLfatal() already called */ return -1; } thisrr->length = 0; thisrr->read = 1; RECORD_LAYER_set_numrpipes(&s->rlayer, 1); RECORD_LAYER_reset_read_sequence(&s->rlayer); return 1; } SSLfatal(s, SSL_AD_DECRYPTION_FAILED, SSL_F_SSL3_GET_RECORD, SSL_R_BLOCK_CIPHER_PAD_IS_WRONG); return -1; } #ifdef SSL_DEBUG printf("dec %lu\n", (unsigned long)rr[0].length); { size_t z; for (z = 0; z < rr[0].length; z++) printf("%02X%c", rr[0].data[z], ((z + 1) % 16) ? ' ' : '\n'); } printf("\n"); #endif /* r->length is now the compressed data plus mac */ if ((sess != NULL) && (s->enc_read_ctx != NULL) && (!SSL_READ_ETM(s) && EVP_MD_CTX_md(s->read_hash) != NULL)) { /* s->read_hash != NULL => mac_size != -1 */ unsigned char *mac = NULL; unsigned char mac_tmp[EVP_MAX_MD_SIZE]; mac_size = EVP_MD_CTX_size(s->read_hash); if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR); return -1; } for (j = 0; j < num_recs; j++) { thisrr = &rr[j]; /* * orig_len is the length of the record before any padding was * removed. This is public information, as is the MAC in use, * therefore we can safely process the record in a different amount * of time if it's too short to possibly contain a MAC. */ if (thisrr->orig_len < mac_size || /* CBC records must have a padding length byte too. */ (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE && thisrr->orig_len < mac_size + 1)) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD, SSL_R_LENGTH_TOO_SHORT); return -1; } if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) { /* * We update the length so that the TLS header bytes can be * constructed correctly but we need to extract the MAC in * constant time from within the record, without leaking the * contents of the padding bytes. */ mac = mac_tmp; if (!ssl3_cbc_copy_mac(mac_tmp, thisrr, mac_size)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD, ERR_R_INTERNAL_ERROR); return -1; } thisrr->length -= mac_size; } else { /* * In this case there's no padding, so |rec->orig_len| equals * |rec->length| and we checked that there's enough bytes for * |mac_size| above. */ thisrr->length -= mac_size; mac = &thisrr->data[thisrr->length]; } i = s->method->ssl3_enc->mac(s, thisrr, md, 0 /* not send */ ); if (i == 0 || mac == NULL || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0) enc_err = -1; if (thisrr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size) enc_err = -1; } } if (enc_err < 0) { if (ossl_statem_in_error(s)) { /* We already called SSLfatal() */ return -1; } if (num_recs == 1 && ossl_statem_skip_early_data(s)) { /* * We assume this is unreadable early_data - we treat it like an * empty record */ /* * The record length may have been modified by the mac check above * so we use the previously saved value */ if (!early_data_count_ok(s, first_rec_len, EARLY_DATA_CIPHERTEXT_OVERHEAD, 0)) { /* SSLfatal() already called */ return -1; } thisrr = &rr[0]; thisrr->length = 0; thisrr->read = 1; RECORD_LAYER_set_numrpipes(&s->rlayer, 1); RECORD_LAYER_reset_read_sequence(&s->rlayer); return 1; } /* * A separate 'decryption_failed' alert was introduced with TLS 1.0, * SSL 3.0 only has 'bad_record_mac'. But unless a decryption * failure is directly visible from the ciphertext anyway, we should * not reveal which kind of error occurred -- this might become * visible to an attacker (e.g. via a logfile) */ SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_SSL3_GET_RECORD, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC); return -1; } for (j = 0; j < num_recs; j++) { thisrr = &rr[j]; /* thisrr->length is now just compressed */ if (s->expand != NULL) { if (thisrr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_COMPRESSED_LENGTH_TOO_LONG); return -1; } if (!ssl3_do_uncompress(s, thisrr)) { SSLfatal(s, SSL_AD_DECOMPRESSION_FAILURE, SSL_F_SSL3_GET_RECORD, SSL_R_BAD_DECOMPRESSION); return -1; } } if (SSL_IS_TLS13(s) && s->enc_read_ctx != NULL) { size_t end; if (thisrr->length == 0 || thisrr->type != SSL3_RT_APPLICATION_DATA) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_BAD_RECORD_TYPE); return -1; } /* Strip trailing padding */ for (end = thisrr->length - 1; end > 0 && thisrr->data[end] == 0; end--) continue; thisrr->length = end; thisrr->type = thisrr->data[end]; if (thisrr->type != SSL3_RT_APPLICATION_DATA && thisrr->type != SSL3_RT_ALERT && thisrr->type != SSL3_RT_HANDSHAKE) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_BAD_RECORD_TYPE); return -1; } if (s->msg_callback) s->msg_callback(0, s->version, SSL3_RT_INNER_CONTENT_TYPE, &thisrr->data[end], 1, s, s->msg_callback_arg); } /* * TLSv1.3 alert and handshake records are required to be non-zero in * length. */ if (SSL_IS_TLS13(s) && (thisrr->type == SSL3_RT_HANDSHAKE || thisrr->type == SSL3_RT_ALERT) && thisrr->length == 0) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_BAD_LENGTH); return -1; } if (thisrr->length > SSL3_RT_MAX_PLAIN_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_DATA_LENGTH_TOO_LONG); return -1; } /* If received packet overflows current Max Fragment Length setting */ if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session) && thisrr->length > GET_MAX_FRAGMENT_LENGTH(s->session)) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD, SSL_R_DATA_LENGTH_TOO_LONG); return -1; } thisrr->off = 0; /*- * So at this point the following is true * thisrr->type is the type of record * thisrr->length == number of bytes in record * thisrr->off == offset to first valid byte * thisrr->data == where to take bytes from, increment after use :-). */ /* just read a 0 length packet */ if (thisrr->length == 0) { RECORD_LAYER_inc_empty_record_count(&s->rlayer); if (RECORD_LAYER_get_empty_record_count(&s->rlayer) > MAX_EMPTY_RECORDS) { SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD, SSL_R_RECORD_TOO_SMALL); return -1; } } else { RECORD_LAYER_reset_empty_record_count(&s->rlayer); } } if (s->early_data_state == SSL_EARLY_DATA_READING) { thisrr = &rr[0]; if (thisrr->type == SSL3_RT_APPLICATION_DATA && !early_data_count_ok(s, thisrr->length, 0, 0)) { /* SSLfatal already called */ return -1; } } RECORD_LAYER_set_numrpipes(&s->rlayer, num_recs); return 1; } int ssl3_do_uncompress(SSL *ssl, SSL3_RECORD *rr) { #ifndef OPENSSL_NO_COMP int i; if (rr->comp == NULL) { rr->comp = (unsigned char *) OPENSSL_malloc(SSL3_RT_MAX_ENCRYPTED_LENGTH); } if (rr->comp == NULL) return 0; /* TODO(size_t): Convert this call */ i = COMP_expand_block(ssl->expand, rr->comp, SSL3_RT_MAX_PLAIN_LENGTH, rr->data, (int)rr->length); if (i < 0) return 0; else rr->length = i; rr->data = rr->comp; #endif return 1; } int ssl3_do_compress(SSL *ssl, SSL3_RECORD *wr) { #ifndef OPENSSL_NO_COMP int i; /* TODO(size_t): Convert this call */ i = COMP_compress_block(ssl->compress, wr->data, (int)(wr->length + SSL3_RT_MAX_COMPRESSED_OVERHEAD), wr->input, (int)wr->length); if (i < 0) return 0; else wr->length = i; wr->input = wr->data; #endif return 1; } /*- * ssl3_enc encrypts/decrypts |n_recs| records in |inrecs|. Will call * SSLfatal() for internal errors, but not otherwise. * * Returns: * 0: (in non-constant time) if the record is publically invalid (i.e. too * short etc). * 1: if the record's padding is valid / the encryption was successful. * -1: if the record's padding is invalid or, if sending, an internal error * occurred. */ int ssl3_enc(SSL *s, SSL3_RECORD *inrecs, size_t n_recs, int sending) { SSL3_RECORD *rec; EVP_CIPHER_CTX *ds; size_t l, i; size_t bs, mac_size = 0; int imac_size; const EVP_CIPHER *enc; rec = inrecs; /* * We shouldn't ever be called with more than one record in the SSLv3 case */ if (n_recs != 1) return 0; if (sending) { ds = s->enc_write_ctx; if (s->enc_write_ctx == NULL) enc = NULL; else enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx); } else { ds = s->enc_read_ctx; if (s->enc_read_ctx == NULL) enc = NULL; else enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx); } if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) { memmove(rec->data, rec->input, rec->length); rec->input = rec->data; } else { l = rec->length; /* TODO(size_t): Convert this call */ bs = EVP_CIPHER_CTX_block_size(ds); /* COMPRESS */ if ((bs != 1) && sending) { i = bs - (l % bs); /* we need to add 'i-1' padding bytes */ l += i; /* * the last of these zero bytes will be overwritten with the * padding length. */ memset(&rec->input[rec->length], 0, i); rec->length += i; rec->input[l - 1] = (unsigned char)(i - 1); } if (!sending) { if (l == 0 || l % bs != 0) return 0; /* otherwise, rec->length >= bs */ } /* TODO(size_t): Convert this call */ if (EVP_Cipher(ds, rec->data, rec->input, (unsigned int)l) < 1) return -1; if (EVP_MD_CTX_md(s->read_hash) != NULL) { /* TODO(size_t): convert me */ imac_size = EVP_MD_CTX_size(s->read_hash); if (imac_size < 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_ENC, ERR_R_INTERNAL_ERROR); return -1; } mac_size = (size_t)imac_size; } if ((bs != 1) && !sending) return ssl3_cbc_remove_padding(rec, bs, mac_size); } return 1; } #define MAX_PADDING 256 /*- * tls1_enc encrypts/decrypts |n_recs| in |recs|. Will call SSLfatal() for * internal errors, but not otherwise. * * Returns: * 0: (in non-constant time) if the record is publically invalid (i.e. too * short etc). * 1: if the record's padding is valid / the encryption was successful. * -1: if the record's padding/AEAD-authenticator is invalid or, if sending, * an internal error occurred. */ int tls1_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int sending) { EVP_CIPHER_CTX *ds; size_t reclen[SSL_MAX_PIPELINES]; unsigned char buf[SSL_MAX_PIPELINES][EVP_AEAD_TLS1_AAD_LEN]; int i, pad = 0, ret, tmpr; size_t bs, mac_size = 0, ctr, padnum, loop; unsigned char padval; int imac_size; const EVP_CIPHER *enc; if (n_recs == 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return 0; } if (sending) { if (EVP_MD_CTX_md(s->write_hash)) { int n = EVP_MD_CTX_size(s->write_hash); if (!ossl_assert(n >= 0)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } } ds = s->enc_write_ctx; if (s->enc_write_ctx == NULL) enc = NULL; else { int ivlen; enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx); /* For TLSv1.1 and later explicit IV */ if (SSL_USE_EXPLICIT_IV(s) && EVP_CIPHER_mode(enc) == EVP_CIPH_CBC_MODE) ivlen = EVP_CIPHER_iv_length(enc); else ivlen = 0; if (ivlen > 1) { for (ctr = 0; ctr < n_recs; ctr++) { if (recs[ctr].data != recs[ctr].input) { /* * we can't write into the input stream: Can this ever * happen?? (steve) */ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } else if (ssl_randbytes(s, recs[ctr].input, ivlen) <= 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } } } } } else { if (EVP_MD_CTX_md(s->read_hash)) { int n = EVP_MD_CTX_size(s->read_hash); if (!ossl_assert(n >= 0)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } } ds = s->enc_read_ctx; if (s->enc_read_ctx == NULL) enc = NULL; else enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx); } if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) { for (ctr = 0; ctr < n_recs; ctr++) { memmove(recs[ctr].data, recs[ctr].input, recs[ctr].length); recs[ctr].input = recs[ctr].data; } ret = 1; } else { bs = EVP_CIPHER_block_size(EVP_CIPHER_CTX_cipher(ds)); if (n_recs > 1) { if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds)) & EVP_CIPH_FLAG_PIPELINE)) { /* * We shouldn't have been called with pipeline data if the * cipher doesn't support pipelining */ SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE); return -1; } } for (ctr = 0; ctr < n_recs; ctr++) { reclen[ctr] = recs[ctr].length; if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds)) & EVP_CIPH_FLAG_AEAD_CIPHER) { unsigned char *seq; seq = sending ? RECORD_LAYER_get_write_sequence(&s->rlayer) : RECORD_LAYER_get_read_sequence(&s->rlayer); if (SSL_IS_DTLS(s)) { /* DTLS does not support pipelining */ unsigned char dtlsseq[9], *p = dtlsseq; s2n(sending ? DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer) : DTLS_RECORD_LAYER_get_r_epoch(&s->rlayer), p); memcpy(p, &seq[2], 6); memcpy(buf[ctr], dtlsseq, 8); } else { memcpy(buf[ctr], seq, 8); for (i = 7; i >= 0; i--) { /* increment */ ++seq[i]; if (seq[i] != 0) break; } } buf[ctr][8] = recs[ctr].type; buf[ctr][9] = (unsigned char)(s->version >> 8); buf[ctr][10] = (unsigned char)(s->version); buf[ctr][11] = (unsigned char)(recs[ctr].length >> 8); buf[ctr][12] = (unsigned char)(recs[ctr].length & 0xff); pad = EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_AEAD_TLS1_AAD, EVP_AEAD_TLS1_AAD_LEN, buf[ctr]); if (pad <= 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } if (sending) { reclen[ctr] += pad; recs[ctr].length += pad; } } else if ((bs != 1) && sending) { padnum = bs - (reclen[ctr] % bs); /* Add weird padding of upto 256 bytes */ if (padnum > MAX_PADDING) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } /* we need to add 'padnum' padding bytes of value padval */ padval = (unsigned char)(padnum - 1); for (loop = reclen[ctr]; loop < reclen[ctr] + padnum; loop++) recs[ctr].input[loop] = padval; reclen[ctr] += padnum; recs[ctr].length += padnum; } if (!sending) { if (reclen[ctr] == 0 || reclen[ctr] % bs != 0) return 0; } } if (n_recs > 1) { unsigned char *data[SSL_MAX_PIPELINES]; /* Set the output buffers */ for (ctr = 0; ctr < n_recs; ctr++) { data[ctr] = recs[ctr].data; } if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_OUTPUT_BUFS, (int)n_recs, data) <= 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE); return -1; } /* Set the input buffers */ for (ctr = 0; ctr < n_recs; ctr++) { data[ctr] = recs[ctr].input; } if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_BUFS, (int)n_recs, data) <= 0 || EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_LENS, (int)n_recs, reclen) <= 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, SSL_R_PIPELINE_FAILURE); return -1; } } /* TODO(size_t): Convert this call */ tmpr = EVP_Cipher(ds, recs[0].data, recs[0].input, (unsigned int)reclen[0]); if ((EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds)) & EVP_CIPH_FLAG_CUSTOM_CIPHER) ? (tmpr < 0) : (tmpr == 0)) return -1; /* AEAD can fail to verify MAC */ if (sending == 0) { if (EVP_CIPHER_mode(enc) == EVP_CIPH_GCM_MODE) { for (ctr = 0; ctr < n_recs; ctr++) { recs[ctr].data += EVP_GCM_TLS_EXPLICIT_IV_LEN; recs[ctr].input += EVP_GCM_TLS_EXPLICIT_IV_LEN; recs[ctr].length -= EVP_GCM_TLS_EXPLICIT_IV_LEN; } } else if (EVP_CIPHER_mode(enc) == EVP_CIPH_CCM_MODE) { for (ctr = 0; ctr < n_recs; ctr++) { recs[ctr].data += EVP_CCM_TLS_EXPLICIT_IV_LEN; recs[ctr].input += EVP_CCM_TLS_EXPLICIT_IV_LEN; recs[ctr].length -= EVP_CCM_TLS_EXPLICIT_IV_LEN; } } } ret = 1; if (!SSL_READ_ETM(s) && EVP_MD_CTX_md(s->read_hash) != NULL) { imac_size = EVP_MD_CTX_size(s->read_hash); if (imac_size < 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC, ERR_R_INTERNAL_ERROR); return -1; } mac_size = (size_t)imac_size; } if ((bs != 1) && !sending) { int tmpret; for (ctr = 0; ctr < n_recs; ctr++) { tmpret = tls1_cbc_remove_padding(s, &recs[ctr], bs, mac_size); /* * If tmpret == 0 then this means publicly invalid so we can * short circuit things here. Otherwise we must respect constant * time behaviour. */ if (tmpret == 0) return 0; ret = constant_time_select_int(constant_time_eq_int(tmpret, 1), ret, -1); } } if (pad && !sending) { for (ctr = 0; ctr < n_recs; ctr++) { recs[ctr].length -= pad; } } } return ret; } int n_ssl3_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int sending) { unsigned char *mac_sec, *seq; const EVP_MD_CTX *hash; unsigned char *p, rec_char; size_t md_size; size_t npad; int t; if (sending) { mac_sec = &(ssl->s3->write_mac_secret[0]); seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer); hash = ssl->write_hash; } else { mac_sec = &(ssl->s3->read_mac_secret[0]); seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer); hash = ssl->read_hash; } t = EVP_MD_CTX_size(hash); if (t < 0) return 0; md_size = t; npad = (48 / md_size) * md_size; if (!sending && EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE && ssl3_cbc_record_digest_supported(hash)) { /* * This is a CBC-encrypted record. We must avoid leaking any * timing-side channel information about how many blocks of data we * are hashing because that gives an attacker a timing-oracle. */ /*- * npad is, at most, 48 bytes and that's with MD5: * 16 + 48 + 8 (sequence bytes) + 1 + 2 = 75. * * With SHA-1 (the largest hash speced for SSLv3) the hash size * goes up 4, but npad goes down by 8, resulting in a smaller * total size. */ unsigned char header[75]; size_t j = 0; memcpy(header + j, mac_sec, md_size); j += md_size; memcpy(header + j, ssl3_pad_1, npad); j += npad; memcpy(header + j, seq, 8); j += 8; header[j++] = rec->type; header[j++] = (unsigned char)(rec->length >> 8); header[j++] = (unsigned char)(rec->length & 0xff); /* Final param == is SSLv3 */ if (ssl3_cbc_digest_record(hash, md, &md_size, header, rec->input, rec->length + md_size, rec->orig_len, mac_sec, md_size, 1) <= 0) return 0; } else { unsigned int md_size_u; /* Chop the digest off the end :-) */ EVP_MD_CTX *md_ctx = EVP_MD_CTX_new(); if (md_ctx == NULL) return 0; rec_char = rec->type; p = md; s2n(rec->length, p); if (EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0 || EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0 || EVP_DigestUpdate(md_ctx, ssl3_pad_1, npad) <= 0 || EVP_DigestUpdate(md_ctx, seq, 8) <= 0 || EVP_DigestUpdate(md_ctx, &rec_char, 1) <= 0 || EVP_DigestUpdate(md_ctx, md, 2) <= 0 || EVP_DigestUpdate(md_ctx, rec->input, rec->length) <= 0 || EVP_DigestFinal_ex(md_ctx, md, NULL) <= 0 || EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0 || EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0 || EVP_DigestUpdate(md_ctx, ssl3_pad_2, npad) <= 0 || EVP_DigestUpdate(md_ctx, md, md_size) <= 0 || EVP_DigestFinal_ex(md_ctx, md, &md_size_u) <= 0) { EVP_MD_CTX_reset(md_ctx); return 0; } EVP_MD_CTX_free(md_ctx); } ssl3_record_sequence_update(seq); return 1; } int tls1_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int sending) { unsigned char *seq; EVP_MD_CTX *hash; size_t md_size; int i; EVP_MD_CTX *hmac = NULL, *mac_ctx; unsigned char header[13]; int stream_mac = (sending ? (ssl->mac_flags & SSL_MAC_FLAG_WRITE_MAC_STREAM) : (ssl->mac_flags & SSL_MAC_FLAG_READ_MAC_STREAM)); int t; if (sending) { seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer); hash = ssl->write_hash; } else { seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer); hash = ssl->read_hash; } t = EVP_MD_CTX_size(hash); if (!ossl_assert(t >= 0)) return 0; md_size = t; /* I should fix this up TLS TLS TLS TLS TLS XXXXXXXX */ if (stream_mac) { mac_ctx = hash; } else { hmac = EVP_MD_CTX_new(); if (hmac == NULL || !EVP_MD_CTX_copy(hmac, hash)) return 0; mac_ctx = hmac; } if (SSL_IS_DTLS(ssl)) { unsigned char dtlsseq[8], *p = dtlsseq; s2n(sending ? DTLS_RECORD_LAYER_get_w_epoch(&ssl->rlayer) : DTLS_RECORD_LAYER_get_r_epoch(&ssl->rlayer), p); memcpy(p, &seq[2], 6); memcpy(header, dtlsseq, 8); } else memcpy(header, seq, 8); header[8] = rec->type; header[9] = (unsigned char)(ssl->version >> 8); header[10] = (unsigned char)(ssl->version); header[11] = (unsigned char)(rec->length >> 8); header[12] = (unsigned char)(rec->length & 0xff); if (!sending && !SSL_READ_ETM(ssl) && EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE && ssl3_cbc_record_digest_supported(mac_ctx)) { /* * This is a CBC-encrypted record. We must avoid leaking any * timing-side channel information about how many blocks of data we * are hashing because that gives an attacker a timing-oracle. */ /* Final param == not SSLv3 */ if (ssl3_cbc_digest_record(mac_ctx, md, &md_size, header, rec->input, rec->length + md_size, rec->orig_len, ssl->s3->read_mac_secret, ssl->s3->read_mac_secret_size, 0) <= 0) { EVP_MD_CTX_free(hmac); return 0; } } else { /* TODO(size_t): Convert these calls */ if (EVP_DigestSignUpdate(mac_ctx, header, sizeof(header)) <= 0 || EVP_DigestSignUpdate(mac_ctx, rec->input, rec->length) <= 0 || EVP_DigestSignFinal(mac_ctx, md, &md_size) <= 0) { EVP_MD_CTX_free(hmac); return 0; } } EVP_MD_CTX_free(hmac); #ifdef SSL_DEBUG fprintf(stderr, "seq="); { int z; for (z = 0; z < 8; z++) fprintf(stderr, "%02X ", seq[z]); fprintf(stderr, "\n"); } fprintf(stderr, "rec="); { size_t z; for (z = 0; z < rec->length; z++) fprintf(stderr, "%02X ", rec->data[z]); fprintf(stderr, "\n"); } #endif if (!SSL_IS_DTLS(ssl)) { for (i = 7; i >= 0; i--) { ++seq[i]; if (seq[i] != 0) break; } } #ifdef SSL_DEBUG { unsigned int z; for (z = 0; z < md_size; z++) fprintf(stderr, "%02X ", md[z]); fprintf(stderr, "\n"); } #endif return 1; } /*- * ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC * record in |rec| by updating |rec->length| in constant time. * * block_size: the block size of the cipher used to encrypt the record. * returns: * 0: (in non-constant time) if the record is publicly invalid. * 1: if the padding was valid * -1: otherwise. */ int ssl3_cbc_remove_padding(SSL3_RECORD *rec, size_t block_size, size_t mac_size) { size_t padding_length; size_t good; const size_t overhead = 1 /* padding length byte */ + mac_size; /* * These lengths are all public so we can test them in non-constant time. */ if (overhead > rec->length) return 0; padding_length = rec->data[rec->length - 1]; good = constant_time_ge_s(rec->length, padding_length + overhead); /* SSLv3 requires that the padding is minimal. */ good &= constant_time_ge_s(block_size, padding_length + 1); rec->length -= good & (padding_length + 1); return constant_time_select_int_s(good, 1, -1); } /*- * tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC * record in |rec| in constant time and returns 1 if the padding is valid and * -1 otherwise. It also removes any explicit IV from the start of the record * without leaking any timing about whether there was enough space after the * padding was removed. * * block_size: the block size of the cipher used to encrypt the record. * returns: * 0: (in non-constant time) if the record is publicly invalid. * 1: if the padding was valid * -1: otherwise. */ int tls1_cbc_remove_padding(const SSL *s, SSL3_RECORD *rec, size_t block_size, size_t mac_size) { size_t good; size_t padding_length, to_check, i; const size_t overhead = 1 /* padding length byte */ + mac_size; /* Check if version requires explicit IV */ if (SSL_USE_EXPLICIT_IV(s)) { /* * These lengths are all public so we can test them in non-constant * time. */ if (overhead + block_size > rec->length) return 0; /* We can now safely skip explicit IV */ rec->data += block_size; rec->input += block_size; rec->length -= block_size; rec->orig_len -= block_size; } else if (overhead > rec->length) return 0; padding_length = rec->data[rec->length - 1]; if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx)) & EVP_CIPH_FLAG_AEAD_CIPHER) { /* padding is already verified */ rec->length -= padding_length + 1; return 1; } good = constant_time_ge_s(rec->length, overhead + padding_length); /* * The padding consists of a length byte at the end of the record and * then that many bytes of padding, all with the same value as the length * byte. Thus, with the length byte included, there are i+1 bytes of * padding. We can't check just |padding_length+1| bytes because that * leaks decrypted information. Therefore we always have to check the * maximum amount of padding possible. (Again, the length of the record * is public information so we can use it.) */ to_check = 256; /* maximum amount of padding, inc length byte. */ if (to_check > rec->length) to_check = rec->length; for (i = 0; i < to_check; i++) { unsigned char mask = constant_time_ge_8_s(padding_length, i); unsigned char b = rec->data[rec->length - 1 - i]; /* * The final |padding_length+1| bytes should all have the value * |padding_length|. Therefore the XOR should be zero. */ good &= ~(mask & (padding_length ^ b)); } /* * If any of the final |padding_length+1| bytes had the wrong value, one * or more of the lower eight bits of |good| will be cleared. */ good = constant_time_eq_s(0xff, good & 0xff); rec->length -= good & (padding_length + 1); return constant_time_select_int_s(good, 1, -1); } /*- * ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in * constant time (independent of the concrete value of rec->length, which may * vary within a 256-byte window). * * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to * this function. * * On entry: * rec->orig_len >= md_size * md_size <= EVP_MAX_MD_SIZE * * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into * a single or pair of cache-lines, then the variable memory accesses don't * actually affect the timing. CPUs with smaller cache-lines [if any] are * not multi-core and are not considered vulnerable to cache-timing attacks. */ #define CBC_MAC_ROTATE_IN_PLACE int ssl3_cbc_copy_mac(unsigned char *out, const SSL3_RECORD *rec, size_t md_size) { #if defined(CBC_MAC_ROTATE_IN_PLACE) unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE]; unsigned char *rotated_mac; #else unsigned char rotated_mac[EVP_MAX_MD_SIZE]; #endif /* * mac_end is the index of |rec->data| just after the end of the MAC. */ size_t mac_end = rec->length; size_t mac_start = mac_end - md_size; size_t in_mac; /* * scan_start contains the number of bytes that we can ignore because the * MAC's position can only vary by 255 bytes. */ size_t scan_start = 0; size_t i, j; size_t rotate_offset; if (!ossl_assert(rec->orig_len >= md_size && md_size <= EVP_MAX_MD_SIZE)) return 0; #if defined(CBC_MAC_ROTATE_IN_PLACE) rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63); #endif /* This information is public so it's safe to branch based on it. */ if (rec->orig_len > md_size + 255 + 1) scan_start = rec->orig_len - (md_size + 255 + 1); in_mac = 0; rotate_offset = 0; memset(rotated_mac, 0, md_size); for (i = scan_start, j = 0; i < rec->orig_len; i++) { size_t mac_started = constant_time_eq_s(i, mac_start); size_t mac_ended = constant_time_lt_s(i, mac_end); unsigned char b = rec->data[i]; in_mac |= mac_started; in_mac &= mac_ended; rotate_offset |= j & mac_started; rotated_mac[j++] |= b & in_mac; j &= constant_time_lt_s(j, md_size); } /* Now rotate the MAC */ #if defined(CBC_MAC_ROTATE_IN_PLACE) j = 0; for (i = 0; i < md_size; i++) { /* in case cache-line is 32 bytes, touch second line */ ((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32]; out[j++] = rotated_mac[rotate_offset++]; rotate_offset &= constant_time_lt_s(rotate_offset, md_size); } #else memset(out, 0, md_size); rotate_offset = md_size - rotate_offset; rotate_offset &= constant_time_lt_s(rotate_offset, md_size); for (i = 0; i < md_size; i++) { for (j = 0; j < md_size; j++) out[j] |= rotated_mac[i] & constant_time_eq_8_s(j, rotate_offset); rotate_offset++; rotate_offset &= constant_time_lt_s(rotate_offset, md_size); } #endif return 1; } int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap) { int i; int enc_err; SSL_SESSION *sess; SSL3_RECORD *rr; int imac_size; size_t mac_size; unsigned char md[EVP_MAX_MD_SIZE]; rr = RECORD_LAYER_get_rrec(&s->rlayer); sess = s->session; /* * At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length, * and we have that many bytes in s->packet */ rr->input = &(RECORD_LAYER_get_packet(&s->rlayer)[DTLS1_RT_HEADER_LENGTH]); /* * ok, we can now read from 's->packet' data into 'rr' rr->input points * at rr->length bytes, which need to be copied into rr->data by either * the decryption or by the decompression When the data is 'copied' into * the rr->data buffer, rr->input will be pointed at the new buffer */ /* * We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length * bytes of encrypted compressed stuff. */ /* check is not needed I believe */ if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_ENCRYPTED_LENGTH_TOO_LONG); return 0; } /* decrypt in place in 'rr->input' */ rr->data = rr->input; rr->orig_len = rr->length; if (SSL_READ_ETM(s) && s->read_hash) { unsigned char *mac; mac_size = EVP_MD_CTX_size(s->read_hash); if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD, ERR_R_INTERNAL_ERROR); return 0; } if (rr->orig_len < mac_size) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_LENGTH_TOO_SHORT); return 0; } rr->length -= mac_size; mac = rr->data + rr->length; i = s->method->ssl3_enc->mac(s, rr, md, 0 /* not send */ ); if (i == 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0) { SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC); return 0; } } enc_err = s->method->ssl3_enc->enc(s, rr, 1, 0); /*- * enc_err is: * 0: (in non-constant time) if the record is publically invalid. * 1: if the padding is valid * -1: if the padding is invalid */ if (enc_err == 0) { if (ossl_statem_in_error(s)) { /* SSLfatal() got called */ return 0; } /* For DTLS we simply ignore bad packets. */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); return 0; } #ifdef SSL_DEBUG printf("dec %ld\n", rr->length); { size_t z; for (z = 0; z < rr->length; z++) printf("%02X%c", rr->data[z], ((z + 1) % 16) ? ' ' : '\n'); } printf("\n"); #endif /* r->length is now the compressed data plus mac */ if ((sess != NULL) && !SSL_READ_ETM(s) && (s->enc_read_ctx != NULL) && (EVP_MD_CTX_md(s->read_hash) != NULL)) { /* s->read_hash != NULL => mac_size != -1 */ unsigned char *mac = NULL; unsigned char mac_tmp[EVP_MAX_MD_SIZE]; /* TODO(size_t): Convert this to do size_t properly */ imac_size = EVP_MD_CTX_size(s->read_hash); if (imac_size < 0) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD, ERR_LIB_EVP); return 0; } mac_size = (size_t)imac_size; if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD, ERR_R_INTERNAL_ERROR); return 0; } /* * orig_len is the length of the record before any padding was * removed. This is public information, as is the MAC in use, * therefore we can safely process the record in a different amount * of time if it's too short to possibly contain a MAC. */ if (rr->orig_len < mac_size || /* CBC records must have a padding length byte too. */ (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE && rr->orig_len < mac_size + 1)) { SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_LENGTH_TOO_SHORT); return 0; } if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) { /* * We update the length so that the TLS header bytes can be * constructed correctly but we need to extract the MAC in * constant time from within the record, without leaking the * contents of the padding bytes. */ mac = mac_tmp; if (!ssl3_cbc_copy_mac(mac_tmp, rr, mac_size)) { SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD, ERR_R_INTERNAL_ERROR); return 0; } rr->length -= mac_size; } else { /* * In this case there's no padding, so |rec->orig_len| equals * |rec->length| and we checked that there's enough bytes for * |mac_size| above. */ rr->length -= mac_size; mac = &rr->data[rr->length]; } i = s->method->ssl3_enc->mac(s, rr, md, 0 /* not send */ ); if (i == 0 || mac == NULL || CRYPTO_memcmp(md, mac, mac_size) != 0) enc_err = -1; if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size) enc_err = -1; } if (enc_err < 0) { /* decryption failed, silently discard message */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); return 0; } /* r->length is now just compressed */ if (s->expand != NULL) { if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_COMPRESSED_LENGTH_TOO_LONG); return 0; } if (!ssl3_do_uncompress(s, rr)) { SSLfatal(s, SSL_AD_DECOMPRESSION_FAILURE, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_BAD_DECOMPRESSION); return 0; } } if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH) { SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD, SSL_R_DATA_LENGTH_TOO_LONG); return 0; } rr->off = 0; /*- * So at this point the following is true * ssl->s3->rrec.type is the type of record * ssl->s3->rrec.length == number of bytes in record * ssl->s3->rrec.off == offset to first valid byte * ssl->s3->rrec.data == where to take bytes from, increment * after use :-). */ /* we have pulled in a full packet so zero things */ RECORD_LAYER_reset_packet_length(&s->rlayer); /* Mark receipt of record. */ dtls1_record_bitmap_update(s, bitmap); return 1; } /* * Retrieve a buffered record that belongs to the current epoch, i.e. processed */ #define dtls1_get_processed_record(s) \ dtls1_retrieve_buffered_record((s), \ &(DTLS_RECORD_LAYER_get_processed_rcds(&s->rlayer))) /*- * Call this to get a new input record. * It will return <= 0 if more data is needed, normally due to an error * or non-blocking IO. * When it finishes, one packet has been decoded and can be found in * ssl->s3->rrec.type - is the type of record * ssl->s3->rrec.data, - data * ssl->s3->rrec.length, - number of bytes */ /* used only by dtls1_read_bytes */ int dtls1_get_record(SSL *s) { int ssl_major, ssl_minor; int rret; size_t more, n; SSL3_RECORD *rr; unsigned char *p = NULL; unsigned short version; DTLS1_BITMAP *bitmap; unsigned int is_next_epoch; rr = RECORD_LAYER_get_rrec(&s->rlayer); again: /* * The epoch may have changed. If so, process all the pending records. * This is a non-blocking operation. */ if (!dtls1_process_buffered_records(s)) { /* SSLfatal() already called */ return -1; } /* if we're renegotiating, then there may be buffered records */ if (dtls1_get_processed_record(s)) return 1; /* get something from the wire */ /* check if we have the header */ if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) || (RECORD_LAYER_get_packet_length(&s->rlayer) < DTLS1_RT_HEADER_LENGTH)) { rret = ssl3_read_n(s, DTLS1_RT_HEADER_LENGTH, SSL3_BUFFER_get_len(&s->rlayer.rbuf), 0, 1, &n); /* read timeout is handled by dtls1_read_bytes */ if (rret <= 0) { /* SSLfatal() already called if appropriate */ return rret; /* error or non-blocking */ } /* this packet contained a partial record, dump it */ if (RECORD_LAYER_get_packet_length(&s->rlayer) != DTLS1_RT_HEADER_LENGTH) { RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY); p = RECORD_LAYER_get_packet(&s->rlayer); if (s->msg_callback) s->msg_callback(0, 0, SSL3_RT_HEADER, p, DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); /* Pull apart the header into the DTLS1_RECORD */ rr->type = *(p++); ssl_major = *(p++); ssl_minor = *(p++); version = (ssl_major << 8) | ssl_minor; /* sequence number is 64 bits, with top 2 bytes = epoch */ n2s(p, rr->epoch); memcpy(&(RECORD_LAYER_get_read_sequence(&s->rlayer)[2]), p, 6); p += 6; n2s(p, rr->length); /* * Lets check the version. We tolerate alerts that don't have the exact * version number (e.g. because of protocol version errors) */ if (!s->first_packet && rr->type != SSL3_RT_ALERT) { if (version != s->version) { /* unexpected version, silently discard */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } } if ((version & 0xff00) != (s->version & 0xff00)) { /* wrong version, silently discard record */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) { /* record too long, silently discard it */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } /* If received packet overflows own-client Max Fragment Length setting */ if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session) && rr->length > GET_MAX_FRAGMENT_LENGTH(s->session)) { /* record too long, silently discard it */ rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } /* now s->rlayer.rstate == SSL_ST_READ_BODY */ } /* s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data */ if (rr->length > RECORD_LAYER_get_packet_length(&s->rlayer) - DTLS1_RT_HEADER_LENGTH) { /* now s->packet_length == DTLS1_RT_HEADER_LENGTH */ more = rr->length; rret = ssl3_read_n(s, more, more, 1, 1, &n); /* this packet contained a partial record, dump it */ if (rret <= 0 || n != more) { if (ossl_statem_in_error(s)) { /* ssl3_read_n() called SSLfatal() */ return -1; } rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } /* * now n == rr->length, and s->packet_length == * DTLS1_RT_HEADER_LENGTH + rr->length */ } /* set state for later operations */ RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER); /* match epochs. NULL means the packet is dropped on the floor */ bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch); if (bitmap == NULL) { rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */ goto again; /* get another record */ } #ifndef OPENSSL_NO_SCTP /* Only do replay check if no SCTP bio */ if (!BIO_dgram_is_sctp(SSL_get_rbio(s))) { #endif /* Check whether this is a repeat, or aged record. */ /* * TODO: Does it make sense to have replay protection in epoch 0 where * we have no integrity negotiated yet? */ if (!dtls1_record_replay_check(s, bitmap)) { rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */ goto again; /* get another record */ } #ifndef OPENSSL_NO_SCTP } #endif /* just read a 0 length packet */ if (rr->length == 0) goto again; /* * If this record is from the next epoch (either HM or ALERT), and a * handshake is currently in progress, buffer it since it cannot be * processed at this time. */ if (is_next_epoch) { if ((SSL_in_init(s) || ossl_statem_get_in_handshake(s))) { if (dtls1_buffer_record (s, &(DTLS_RECORD_LAYER_get_unprocessed_rcds(&s->rlayer)), rr->seq_num) < 0) { /* SSLfatal() already called */ return -1; } } rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); goto again; } if (!dtls1_process_record(s, bitmap)) { if (ossl_statem_in_error(s)) { /* dtls1_process_record() called SSLfatal */ return -1; } rr->length = 0; RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */ goto again; /* get another record */ } return 1; }