1fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ssl/s3_cbc.c */ 2fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ==================================================================== 3fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * Copyright (c) 2012 The OpenSSL Project. All rights reserved. 4fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 5fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * Redistribution and use in source and binary forms, with or without 6fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * modification, are permitted provided that the following conditions 7fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * are met: 8fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 9fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 1. Redistributions of source code must retain the above copyright 10fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * notice, this list of conditions and the following disclaimer. 11fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 12fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 2. Redistributions in binary form must reproduce the above copyright 13fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * notice, this list of conditions and the following disclaimer in 14fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * the documentation and/or other materials provided with the 15fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * distribution. 16fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 17fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 3. All advertising materials mentioning features or use of this 18fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * software must display the following acknowledgment: 19fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * "This product includes software developed by the OpenSSL Project 20fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 21fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 22fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 23fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * endorse or promote products derived from this software without 24fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * prior written permission. For written permission, please contact 25fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * openssl-core@openssl.org. 26fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 27fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 5. Products derived from this software may not be called "OpenSSL" 28fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * nor may "OpenSSL" appear in their names without prior written 29fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * permission of the OpenSSL Project. 30fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 31fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 6. Redistributions of any form whatsoever must retain the following 32fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * acknowledgment: 33fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * "This product includes software developed by the OpenSSL Project 34fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 35fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 36fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 37fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 38fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 39fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 40fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 41fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 42fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 43fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 45fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 46fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 47fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * OF THE POSSIBILITY OF SUCH DAMAGE. 48fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ==================================================================== 49fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 50fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * This product includes cryptographic software written by Eric Young 51fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * (eay@cryptsoft.com). This product includes software written by Tim 52fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * Hudson (tjh@cryptsoft.com). 53fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 54fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom */ 55fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 56c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root#include "../crypto/constant_time_locl.h" 57fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#include "ssl_locl.h" 58fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 59fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#include <openssl/md5.h> 60fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#include <openssl/sha.h> 61fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 62fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's length 63fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * field. (SHA-384/512 have 128-bit length.) */ 64fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#define MAX_HASH_BIT_COUNT_BYTES 16 65fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 66fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support. 67fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * Currently SHA-384/512 has a 128-byte block size and that's the largest 68fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * supported by TLS.) */ 69fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#define MAX_HASH_BLOCK_SIZE 128 70fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 71fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC 72fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * record in |rec| by updating |rec->length| in constant time. 73fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 74fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * block_size: the block size of the cipher used to encrypt the record. 75fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * returns: 76fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 0: (in non-constant time) if the record is publicly invalid. 77fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 1: if the padding was valid 78fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * -1: otherwise. */ 79fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromint ssl3_cbc_remove_padding(const SSL* s, 80fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom SSL3_RECORD *rec, 81fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned block_size, 82fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned mac_size) 83fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 84fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned padding_length, good; 85fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const unsigned overhead = 1 /* padding length byte */ + mac_size; 86fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 87fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* These lengths are all public so we can test them in non-constant 88fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * time. */ 89fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (overhead > rec->length) 90fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom return 0; 91fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 92fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom padding_length = rec->data[rec->length-1]; 93fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom good = constant_time_ge(rec->length, padding_length+overhead); 94fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* SSLv3 requires that the padding is minimal. */ 95fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom good &= constant_time_ge(block_size, padding_length+1); 9604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom padding_length = good & (padding_length+1); 9704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->length -= padding_length; 9804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->type |= padding_length<<8; /* kludge: pass padding length */ 99c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root return constant_time_select_int(good, 1, -1); 100c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root } 101fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 102fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC 103fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * record in |rec| in constant time and returns 1 if the padding is valid and 104fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * -1 otherwise. It also removes any explicit IV from the start of the record 105fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * without leaking any timing about whether there was enough space after the 106fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * padding was removed. 107fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 108fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * block_size: the block size of the cipher used to encrypt the record. 109fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * returns: 110fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 0: (in non-constant time) if the record is publicly invalid. 111fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 1: if the padding was valid 112fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * -1: otherwise. */ 113fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromint tls1_cbc_remove_padding(const SSL* s, 114fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom SSL3_RECORD *rec, 115fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned block_size, 116fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned mac_size) 117fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 118fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned padding_length, good, to_check, i; 119eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom const unsigned overhead = 1 /* padding length byte */ + mac_size; 120eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom /* Check if version requires explicit IV */ 121ff41a4bc41ae1e1391f9b05117623ff70b985983Kenny Root if (s->version >= TLS1_1_VERSION || s->version == DTLS1_BAD_VER) 12204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom { 123eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom /* These lengths are all public so we can test them in 124eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom * non-constant time. 125eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom */ 126eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom if (overhead + block_size > rec->length) 127eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom return 0; 128eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom /* We can now safely skip explicit IV */ 12904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->data += block_size; 13004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->input += block_size; 13104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->length -= block_size; 13204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom } 133eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom else if (overhead > rec->length) 134eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom return 0; 13504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom 136fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom padding_length = rec->data[rec->length-1]; 137fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 138fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* NB: if compression is in operation the first packet may not be of 139fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * even length so the padding bug check cannot be performed. This bug 140fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * workaround has been around since SSLeay so hopefully it is either 141fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * fixed now or no buggy implementation supports compression [steve] 142fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom */ 143fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if ( (s->options&SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) 144fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 145fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* First packet is even in size, so check */ 146fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0",8) == 0) && 147fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom !(padding_length & 1)) 148fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 149fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom s->s3->flags|=TLS1_FLAGS_TLS_PADDING_BUG; 150fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 151fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && 152fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom padding_length > 0) 153fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 154fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom padding_length--; 155fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 156fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 157fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 15804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER) 15904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom { 16004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom /* padding is already verified */ 161eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rec->length -= padding_length + 1; 16204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom return 1; 16304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom } 16404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom 165fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom good = constant_time_ge(rec->length, overhead+padding_length); 166fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* The padding consists of a length byte at the end of the record and 167fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * then that many bytes of padding, all with the same value as the 168fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * length byte. Thus, with the length byte included, there are i+1 169fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * bytes of padding. 170fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 171fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * We can't check just |padding_length+1| bytes because that leaks 172fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * decrypted information. Therefore we always have to check the maximum 173fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * amount of padding possible. (Again, the length of the record is 174fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * public information so we can use it.) */ 175fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom to_check = 255; /* maximum amount of padding. */ 176fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (to_check > rec->length-1) 177fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom to_check = rec->length-1; 178fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 179fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < to_check; i++) 180fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 181c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned char mask = constant_time_ge_8(padding_length, i); 182fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char b = rec->data[rec->length-1-i]; 183fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* The final |padding_length+1| bytes should all have the value 184fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * |padding_length|. Therefore the XOR should be zero. */ 185fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom good &= ~(mask&(padding_length ^ b)); 186fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 187fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 188fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If any of the final |padding_length+1| bytes had the wrong value, 189c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root * one or more of the lower eight bits of |good| will be cleared. 190c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root */ 191c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root good = constant_time_eq(0xff, good & 0xff); 19204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom padding_length = good & (padding_length+1); 19304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->length -= padding_length; 19404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom rec->type |= padding_length<<8; /* kludge: pass padding length */ 195fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 196c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root return constant_time_select_int(good, 1, -1); 197fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 198fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 199fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in 200fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * constant time (independent of the concrete value of rec->length, which may 201fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * vary within a 256-byte window). 202fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 203fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to 204fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * this function. 205fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 206fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * On entry: 207fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * rec->orig_len >= md_size 208fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * md_size <= EVP_MAX_MD_SIZE 209fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 210fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with 211fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into 212eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom * a single or pair of cache-lines, then the variable memory accesses don't 213eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom * actually affect the timing. CPUs with smaller cache-lines [if any] are 214eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom * not multi-core and are not considered vulnerable to cache-timing attacks. 215fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom */ 216eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom#define CBC_MAC_ROTATE_IN_PLACE 217eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom 218fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromvoid ssl3_cbc_copy_mac(unsigned char* out, 219fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const SSL3_RECORD *rec, 22004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom unsigned md_size,unsigned orig_len) 221fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 222fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#if defined(CBC_MAC_ROTATE_IN_PLACE) 223eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom unsigned char rotated_mac_buf[64+EVP_MAX_MD_SIZE]; 224fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char *rotated_mac; 225fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#else 226fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char rotated_mac[EVP_MAX_MD_SIZE]; 227fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#endif 228fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 229fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* mac_end is the index of |rec->data| just after the end of the MAC. */ 230fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned mac_end = rec->length; 231fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned mac_start = mac_end - md_size; 232fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* scan_start contains the number of bytes that we can ignore because 233fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * the MAC's position can only vary by 255 bytes. */ 234fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned scan_start = 0; 235fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned i, j; 236fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned div_spoiler; 237fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned rotate_offset; 238fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 23904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom OPENSSL_assert(orig_len >= md_size); 240fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); 241fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 242fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#if defined(CBC_MAC_ROTATE_IN_PLACE) 243eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotated_mac = rotated_mac_buf + ((0-(size_t)rotated_mac_buf)&63); 244fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#endif 245fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 246fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* This information is public so it's safe to branch based on it. */ 24704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom if (orig_len > md_size + 255 + 1) 24804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom scan_start = orig_len - (md_size + 255 + 1); 249fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* div_spoiler contains a multiple of md_size that is used to cause the 250fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * modulo operation to be constant time. Without this, the time varies 251fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * based on the amount of padding when running on Intel chips at least. 252fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 253fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * The aim of right-shifting md_size is so that the compiler doesn't 254fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * figure out that it can remove div_spoiler as that would require it 255fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * to prove that md_size is always even, which I hope is beyond it. */ 256fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom div_spoiler = md_size >> 1; 257fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom div_spoiler <<= (sizeof(div_spoiler)-1)*8; 258fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; 259fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 260fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memset(rotated_mac, 0, md_size); 261eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom for (i = scan_start, j = 0; i < orig_len; i++) 262fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 263c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned char mac_started = constant_time_ge_8(i, mac_start); 264c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root unsigned char mac_ended = constant_time_ge_8(i, mac_end); 265eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom unsigned char b = rec->data[i]; 266eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotated_mac[j++] |= b & mac_started & ~mac_ended; 267eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom j &= constant_time_lt(j,md_size); 268fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 269fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 270fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* Now rotate the MAC */ 271fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#if defined(CBC_MAC_ROTATE_IN_PLACE) 272fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom j = 0; 273fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < md_size; i++) 274fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 275eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom /* in case cache-line is 32 bytes, touch second line */ 276eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom ((volatile unsigned char *)rotated_mac)[rotate_offset^32]; 277eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom out[j++] = rotated_mac[rotate_offset++]; 278eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotate_offset &= constant_time_lt(rotate_offset,md_size); 279fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 280fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#else 281fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memset(out, 0, md_size); 282eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotate_offset = md_size - rotate_offset; 283eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotate_offset &= constant_time_lt(rotate_offset,md_size); 284fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < md_size; i++) 285fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 286fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (j = 0; j < md_size; j++) 287eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset); 288eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotate_offset++; 289eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom rotate_offset &= constant_time_lt(rotate_offset,md_size); 290fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 291fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom#endif 292fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 293fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 294eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom/* u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in 295eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom * little-endian order. The value of p is advanced by four. */ 296eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom#define u32toLE(n, p) \ 297eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom (*((p)++)=(unsigned char)(n), \ 298eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom *((p)++)=(unsigned char)(n>>8), \ 299eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom *((p)++)=(unsigned char)(n>>16), \ 300eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom *((p)++)=(unsigned char)(n>>24)) 301eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom 302fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* These functions serialize the state of a hash and thus perform the standard 303fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * "final" operation without adding the padding and length that such a function 304fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * typically does. */ 305fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromstatic void tls1_md5_final_raw(void* ctx, unsigned char *md_out) 306fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 307fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom MD5_CTX *md5 = ctx; 308eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom u32toLE(md5->A, md_out); 309eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom u32toLE(md5->B, md_out); 310eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom u32toLE(md5->C, md_out); 311eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom u32toLE(md5->D, md_out); 312fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 313fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 314fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromstatic void tls1_sha1_final_raw(void* ctx, unsigned char *md_out) 315fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 316fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom SHA_CTX *sha1 = ctx; 317fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha1->h0, md_out); 318fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha1->h1, md_out); 319fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha1->h2, md_out); 320fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha1->h3, md_out); 321fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha1->h4, md_out); 322fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 32304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#define LARGEST_DIGEST_CTX SHA_CTX 324fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 32504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA256 326fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromstatic void tls1_sha256_final_raw(void* ctx, unsigned char *md_out) 327fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 328fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom SHA256_CTX *sha256 = ctx; 329fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned i; 330fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 331fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < 8; i++) 332fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 333fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n(sha256->h[i], md_out); 334fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 335fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 33604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#undef LARGEST_DIGEST_CTX 33704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#define LARGEST_DIGEST_CTX SHA256_CTX 33804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 339fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 34004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA512 341fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromstatic void tls1_sha512_final_raw(void* ctx, unsigned char *md_out) 342fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 343fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom SHA512_CTX *sha512 = ctx; 344fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned i; 345fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 346fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < 8; i++) 347fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 348fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom l2n8(sha512->h[i], md_out); 349fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 350fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 35104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#undef LARGEST_DIGEST_CTX 35204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#define LARGEST_DIGEST_CTX SHA512_CTX 35304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 354fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 355fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function 356fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * which ssl3_cbc_digest_record supports. */ 357fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromchar ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) 358fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 35904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifdef OPENSSL_FIPS 36004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom if (FIPS_mode()) 36104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom return 0; 36204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 36304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom switch (EVP_MD_CTX_type(ctx)) 364fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 365fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_md5: 366fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha1: 36704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA256 368fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha224: 369fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha256: 37004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 37104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA512 372fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha384: 373fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha512: 37404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 375fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom return 1; 376fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom default: 377fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom return 0; 378fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 379fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 380fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 381fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom/* ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS 382fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * record. 383fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 384fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ctx: the EVP_MD_CTX from which we take the hash function. 385fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * ssl3_cbc_record_digest_supported must return true for this EVP_MD_CTX. 386fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written. 387fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * md_out_size: if non-NULL, the number of output bytes is written here. 388fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * header: the 13-byte, TLS record header. 389fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * data: the record data itself, less any preceeding explicit IV. 390fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * data_plus_mac_size: the secret, reported length of the data and MAC 391fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * once the padding has been removed. 392fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * data_plus_mac_plus_padding_size: the public length of the whole 393fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * record, including padding. 394fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * is_sslv3: non-zero if we are to use SSLv3. Otherwise, TLS. 395fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 396fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * On entry: by virtue of having been through one of the remove_padding 397fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * functions, above, we know that data_plus_mac_size is large enough to contain 398fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * a padding byte and MAC. (If the padding was invalid, it might contain the 399fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * padding too. ) */ 400fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstromvoid ssl3_cbc_digest_record( 401fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const EVP_MD_CTX *ctx, 402fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char* md_out, 403fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom size_t* md_out_size, 404fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const unsigned char header[13], 405fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const unsigned char *data, 406fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom size_t data_plus_mac_size, 407fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom size_t data_plus_mac_plus_padding_size, 408fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom const unsigned char *mac_secret, 409fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned mac_secret_length, 410fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom char is_sslv3) 411fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 41204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom union { double align; 41304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom unsigned char c[sizeof(LARGEST_DIGEST_CTX)]; } md_state; 414fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom void (*md_final_raw)(void *ctx, unsigned char *md_out); 415fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom void (*md_transform)(void *ctx, const unsigned char *block); 416fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned md_size, md_block_size = 64; 417fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned sslv3_pad_length = 40, header_length, variance_blocks, 418fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom len, max_mac_bytes, num_blocks, 419fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom num_starting_blocks, k, mac_end_offset, c, index_a, index_b; 42004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom unsigned int bits; /* at most 18 bits */ 421fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES]; 422fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* hmac_pad is the masked HMAC key. */ 423fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE]; 424fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char first_block[MAX_HASH_BLOCK_SIZE]; 425fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char mac_out[EVP_MAX_MD_SIZE]; 426fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned i, j, md_out_size_u; 427fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_MD_CTX md_ctx; 428fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* mdLengthSize is the number of bytes in the length field that terminates 429fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * the hash. */ 430fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned md_length_size = 8; 431eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom char length_is_big_endian = 1; 432fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 433fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* This is a, hopefully redundant, check that allows us to forget about 434fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * many possible overflows later in this function. */ 435fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(data_plus_mac_plus_padding_size < 1024*1024); 436fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 43704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom switch (EVP_MD_CTX_type(ctx)) 438fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 439fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_md5: 44004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom MD5_Init((MD5_CTX*)md_state.c); 441fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_md5_final_raw; 442fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) MD5_Transform; 443fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 16; 444fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom sslv3_pad_length = 48; 445eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_is_big_endian = 0; 446fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 447fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha1: 44804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom SHA1_Init((SHA_CTX*)md_state.c); 449fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_sha1_final_raw; 450fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA1_Transform; 451fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 20; 452fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 45304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA256 454fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha224: 45504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom SHA224_Init((SHA256_CTX*)md_state.c); 456fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_sha256_final_raw; 457fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform; 458fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 224/8; 459fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 460fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha256: 46104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom SHA256_Init((SHA256_CTX*)md_state.c); 462fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_sha256_final_raw; 463fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA256_Transform; 464fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 32; 465fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 46604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 46704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifndef OPENSSL_NO_SHA512 468fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha384: 46904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom SHA384_Init((SHA512_CTX*)md_state.c); 470fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_sha512_final_raw; 471fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform; 472fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 384/8; 473fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_block_size = 128; 474fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_length_size = 16; 475fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 476fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom case NID_sha512: 47704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom SHA512_Init((SHA512_CTX*)md_state.c); 478fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_final_raw = tls1_sha512_final_raw; 479fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_transform = (void(*)(void *ctx, const unsigned char *block)) SHA512_Transform; 480fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_size = 64; 481fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_block_size = 128; 482fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom md_length_size = 16; 483fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom break; 48404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 485fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom default: 486fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* ssl3_cbc_record_digest_supported should have been 487fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * called first to check that the hash function is 488fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * supported. */ 489fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(0); 490fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (md_out_size) 491fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom *md_out_size = -1; 492fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom return; 493fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 494fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 495fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); 496fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE); 497fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); 498fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 499fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom header_length = 13; 500fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (is_sslv3) 501fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 502fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom header_length = 503fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom mac_secret_length + 504fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom sslv3_pad_length + 505fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 8 /* sequence number */ + 506fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 1 /* record type */ + 507fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 2 /* record length */; 508fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 509fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 510fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* variance_blocks is the number of blocks of the hash that we have to 511fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * calculate in constant time because they could be altered by the 512fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * padding value. 513fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 514fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * In SSLv3, the padding must be minimal so the end of the plaintext 515fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * varies by, at most, 15+20 = 35 bytes. (We conservatively assume that 516fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * the MAC size varies from 0..20 bytes.) In case the 9 bytes of hash 517fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * termination (0x80 + 64-bit length) don't fit in the final block, we 518fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * say that the final two blocks can vary based on the padding. 519fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 520fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not 521fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * required to be minimal. Therefore we say that the final six blocks 522fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * can vary based on the padding. 523fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 524fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * Later in the function, if the message is short and there obviously 525fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * cannot be this many blocks then variance_blocks can be reduced. */ 526fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom variance_blocks = is_sslv3 ? 2 : 6; 527fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* From now on we're dealing with the MAC, which conceptually has 13 528fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * bytes of `header' before the start of the data (TLS) or 71/75 bytes 529fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * (SSLv3) */ 530fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom len = data_plus_mac_plus_padding_size + header_length; 531fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* max_mac_bytes contains the maximum bytes of bytes in the MAC, including 532fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * |header|, assuming that there's no padding. */ 533fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom max_mac_bytes = len - md_size - 1; 534fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* num_blocks is the maximum number of hash blocks. */ 535fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom num_blocks = (max_mac_bytes + 1 + md_length_size + md_block_size - 1) / md_block_size; 536fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* In order to calculate the MAC in constant time we have to handle 537fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * the final blocks specially because the padding value could cause the 538fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * end to appear somewhere in the final |variance_blocks| blocks and we 539fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * can't leak where. However, |num_starting_blocks| worth of data can 540fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * be hashed right away because no padding value can affect whether 541fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * they are plaintext. */ 542fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom num_starting_blocks = 0; 543fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* k is the starting byte offset into the conceptual header||data where 544fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * we start processing. */ 545fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom k = 0; 546fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* mac_end_offset is the index just past the end of the data to be 547fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * MACed. */ 548fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom mac_end_offset = data_plus_mac_size + header_length - md_size; 549fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* c is the index of the 0x80 byte in the final hash block that 550fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * contains application data. */ 551fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom c = mac_end_offset % md_block_size; 552fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* index_a is the hash block number that contains the 0x80 terminating 553fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * value. */ 554fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom index_a = mac_end_offset / md_block_size; 555fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* index_b is the hash block number that contains the 64-bit hash 556fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * length, in bits. */ 557fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom index_b = (mac_end_offset + md_length_size) / md_block_size; 558fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* bits is the hash-length in bits. It includes the additional hash 559fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * block for the masked HMAC key, or whole of |header| in the case of 560fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * SSLv3. */ 561fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 562fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* For SSLv3, if we're going to have any starting blocks then we need 563fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * at least two because the header is larger than a single block. */ 564fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0)) 565fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 566fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom num_starting_blocks = num_blocks - variance_blocks; 567fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom k = md_block_size*num_starting_blocks; 568fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 569fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 570fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom bits = 8*mac_end_offset; 571fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (!is_sslv3) 572fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 573fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* Compute the initial HMAC block. For SSLv3, the padding and 574fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * secret bytes are included in |header| because they take more 575fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * than a single block. */ 576fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom bits += 8*md_block_size; 577fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memset(hmac_pad, 0, md_block_size); 578fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad)); 579fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memcpy(hmac_pad, mac_secret, mac_secret_length); 580fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < md_block_size; i++) 581fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom hmac_pad[i] ^= 0x36; 582fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 58304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, hmac_pad); 584fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 585fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 586eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom if (length_is_big_endian) 587eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom { 588eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom memset(length_bytes,0,md_length_size-4); 589eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-4] = (unsigned char)(bits>>24); 590eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-3] = (unsigned char)(bits>>16); 591eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-2] = (unsigned char)(bits>>8); 592eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-1] = (unsigned char)bits; 593eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom } 594eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom else 595eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom { 596eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom memset(length_bytes,0,md_length_size); 597eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-5] = (unsigned char)(bits>>24); 598eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-6] = (unsigned char)(bits>>16); 599eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-7] = (unsigned char)(bits>>8); 600eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom length_bytes[md_length_size-8] = (unsigned char)bits; 601eeffacea337ec6a275e4c496acd12ca67a244533Brian Carlstrom } 602fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 603fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (k > 0) 604fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 605fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (is_sslv3) 606fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 607fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* The SSLv3 header is larger than a single block. 608fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * overhang is the number of bytes beyond a single 609fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * block that the header consumes: either 7 bytes 610fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * (SHA1) or 11 bytes (MD5). */ 611fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned overhang = header_length-md_block_size; 61204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, header); 613fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memcpy(first_block, header + md_block_size, overhang); 614fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memcpy(first_block + overhang, data, md_block_size-overhang); 61504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, first_block); 616fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 1; i < k/md_block_size - 1; i++) 61704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, data + md_block_size*i - overhang); 618fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 619fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom else 620fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 621fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* k is a multiple of md_block_size. */ 622fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memcpy(first_block, header, 13); 623fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memcpy(first_block+13, data, md_block_size-13); 62404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, first_block); 625fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 1; i < k/md_block_size; i++) 62604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, data + md_block_size*i - 13); 627fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 628fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 629fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 630fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memset(mac_out, 0, sizeof(mac_out)); 631fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 632fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* We now process the final hash blocks. For each block, we construct 633fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * it in constant time. If the |i==index_a| then we'll include the 0x80 634fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * bytes and zero pad etc. For each block we selectively copy it, in 635fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * constant time, to |mac_out|. */ 636fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = num_starting_blocks; i <= num_starting_blocks+variance_blocks; i++) 637fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 638fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char block[MAX_HASH_BLOCK_SIZE]; 639fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char is_block_a = constant_time_eq_8(i, index_a); 640fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char is_block_b = constant_time_eq_8(i, index_b); 641fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (j = 0; j < md_block_size; j++) 642fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 643fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom unsigned char b = 0, is_past_c, is_past_cp1; 644fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (k < header_length) 645fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom b = header[k]; 646fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom else if (k < data_plus_mac_plus_padding_size + header_length) 647fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom b = data[k-header_length]; 648fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom k++; 649fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 650c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root is_past_c = is_block_a & constant_time_ge_8(j, c); 651c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root is_past_cp1 = is_block_a & constant_time_ge_8(j, c+1); 652fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If this is the block containing the end of the 653fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * application data, and we are at the offset for the 654fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * 0x80 value, then overwrite b with 0x80. */ 655c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root b = constant_time_select_8(is_past_c, 0x80, b); 656fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If this the the block containing the end of the 657fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * application data and we're past the 0x80 value then 658fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * just write zero. */ 659fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom b = b&~is_past_cp1; 660fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If this is index_b (the final block), but not 661fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * index_a (the end of the data), then the 64-bit 662fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * length didn't fit into index_a and we're having to 663fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * add an extra block of zeros. */ 664fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom b &= ~is_block_b | is_block_a; 665fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 666fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* The final bytes of one of the blocks contains the 667fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom * length. */ 668fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (j >= md_block_size - md_length_size) 669fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 670fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If this is index_b, write a length byte. */ 671c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root b = constant_time_select_8( 672c64f6fe2be99cb3fa8e491b5bede9a217de87a4cKenny Root is_block_b, length_bytes[j-(md_block_size-md_length_size)], b); 673fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 674fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom block[j] = b; 675fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 676fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 67704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_transform(md_state.c, block); 67804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom md_final_raw(md_state.c, block); 679fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* If this is index_b, copy the hash value to |mac_out|. */ 680fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (j = 0; j < md_size; j++) 681fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom mac_out[j] |= block[j]&is_block_b; 682fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 683fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 684fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_MD_CTX_init(&md_ctx); 685fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */); 686fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (is_sslv3) 687fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 688fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */ 689fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom memset(hmac_pad, 0x5c, sslv3_pad_length); 690fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 691fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length); 692fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length); 693fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestUpdate(&md_ctx, mac_out, md_size); 694fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 695fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom else 696fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom { 697fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom /* Complete the HMAC in the standard manner. */ 698fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom for (i = 0; i < md_block_size; i++) 699fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom hmac_pad[i] ^= 0x6a; 700fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom 701fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size); 702fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestUpdate(&md_ctx, mac_out, md_size); 703fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 704fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); 705fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom if (md_out_size) 706fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom *md_out_size = md_out_size_u; 707fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom EVP_MD_CTX_cleanup(&md_ctx); 708fa75fdba32eae335f286afb1dc93ef1b5ec72615Brian Carlstrom } 70904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom 71004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#ifdef OPENSSL_FIPS 71104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom 71204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom/* Due to the need to use EVP in FIPS mode we can't reimplement digests but 71304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * we can ensure the number of blocks processed is equal for all cases 71404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * by digesting additional data. 71504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom */ 71604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom 71704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstromvoid tls_fips_digest_extra( 71804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom const EVP_CIPHER_CTX *cipher_ctx, EVP_MD_CTX *mac_ctx, 71904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom const unsigned char *data, size_t data_len, size_t orig_len) 72004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom { 72104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom size_t block_size, digest_pad, blocks_data, blocks_orig; 72204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE) 72304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom return; 72404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom block_size = EVP_MD_CTX_block_size(mac_ctx); 72504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom /* We are in FIPS mode if we get this far so we know we have only SHA* 72604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * digests and TLS to deal with. 72704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * Minimum digest padding length is 17 for SHA384/SHA512 and 9 72804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * otherwise. 72904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * Additional header is 13 bytes. To get the number of digest blocks 73004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * processed round up the amount of data plus padding to the nearest 73104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise. 73204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * So we have: 73304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size 73404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * equivalently: 73504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * blocks = (payload_len + digest_pad + 12)/block_size + 1 73604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * HMAC adds a constant overhead. 73704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * We're ultimately only interested in differences so this becomes 73804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * blocks = (payload_len + 29)/128 73904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * for SHA384/SHA512 and 74004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * blocks = (payload_len + 21)/64 74104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * otherwise. 74204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom */ 74304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom digest_pad = block_size == 64 ? 21 : 29; 74404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom blocks_orig = (orig_len + digest_pad)/block_size; 74504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom blocks_data = (data_len + digest_pad)/block_size; 74604ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom /* MAC enough blocks to make up the difference between the original 74704ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * and actual lengths plus one extra block to ensure this is never a 74804ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * no op. The "data" pointer should always have enough space to 74904ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * perform this operation as it is large enough for a maximum 75004ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom * length TLS buffer. 75104ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom */ 75204ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom EVP_DigestSignUpdate(mac_ctx, data, 75304ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom (blocks_orig - blocks_data + 1) * block_size); 75404ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom } 75504ef91b390dfcc6125913e2f2af502d23d7a5112Brian Carlstrom#endif 756