X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=ssl%2Fs3_cbc.c;h=7d9c3776973decb1398ff9b4b971dc2230824950;hp=e5a04ace60df9a960132b7ce6b6c8dc8815cf76e;hb=67dc995eaf538ea309c6292a1a5073465201f55b;hpb=35a1cc90bc1795e8893c11e442790ee7f659fffb diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c index e5a04ace60..7d9c377697 100644 --- a/ssl/s3_cbc.c +++ b/ssl/s3_cbc.c @@ -1,60 +1,15 @@ -/* ssl/s3_cbc.c */ -/* ==================================================================== - * Copyright (c) 2012 The OpenSSL Project. All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in - * the documentation and/or other materials provided with the - * distribution. - * - * 3. All advertising materials mentioning features or use of this - * software must display the following acknowledgment: - * "This product includes software developed by the OpenSSL Project - * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" - * - * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to - * endorse or promote products derived from this software without - * prior written permission. For written permission, please contact - * openssl-core@openssl.org. - * - * 5. Products derived from this software may not be called "OpenSSL" - * nor may "OpenSSL" appear in their names without prior written - * permission of the OpenSSL Project. - * - * 6. Redistributions of any form whatsoever must retain the following - * acknowledgment: - * "This product includes software developed by the OpenSSL Project - * for use in the OpenSSL Toolkit (http://www.openssl.org/)" - * - * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY - * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR - * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR - * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT - * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; - * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, - * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) - * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED - * OF THE POSSIBILITY OF SUCH DAMAGE. - * ==================================================================== - * - * This product includes cryptographic software written by Eric Young - * (eay@cryptsoft.com). This product includes software written by Tim - * Hudson (tjh@cryptsoft.com). +/* + * Copyright 2012-2016 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 "../crypto/constant_time_locl.h" +#include "internal/constant_time_locl.h" #include "ssl_locl.h" +#include "internal/cryptlib.h" #include #include @@ -72,228 +27,6 @@ */ #define MAX_HASH_BLOCK_SIZE 128 -/*- - * 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(const SSL *s, - SSL3_RECORD *rec, - unsigned block_size, unsigned mac_size) -{ - unsigned padding_length, good; - const unsigned 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(rec->length, padding_length + overhead); - /* SSLv3 requires that the padding is minimal. */ - good &= constant_time_ge(block_size, padding_length + 1); - rec->length -= good & (padding_length + 1); - return constant_time_select_int(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, - unsigned block_size, unsigned mac_size) -{ - unsigned padding_length, good, to_check, i; - const unsigned 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]; - - /* - * NB: if compression is in operation the first packet may not be of even - * length so the padding bug check cannot be performed. This bug - * workaround has been around since SSLeay so hopefully it is either - * fixed now or no buggy implementation supports compression [steve] - */ - if ((s->options & SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) { - /* First packet is even in size, so check */ - if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0", 8) == 0) && - !(padding_length & 1)) { - s->s3->flags |= TLS1_FLAGS_TLS_PADDING_BUG; - } - if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && padding_length > 0) { - padding_length--; - } - } - - if (EVP_CIPHER_flags(s->enc_read_ctx->cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) { - /* padding is already verified */ - rec->length -= padding_length + 1; - return 1; - } - - good = constant_time_ge(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 = 255; /* maximum amount of padding. */ - if (to_check > rec->length - 1) - to_check = rec->length - 1; - - for (i = 0; i < to_check; i++) { - unsigned char mask = constant_time_ge_8(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(0xff, good & 0xff); - rec->length -= good & (padding_length + 1); - - return constant_time_select_int(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 - -void ssl3_cbc_copy_mac(unsigned char *out, - const SSL3_RECORD *rec, unsigned 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. - */ - unsigned mac_end = rec->length; - unsigned mac_start = mac_end - md_size; - /* - * scan_start contains the number of bytes that we can ignore because the - * MAC's position can only vary by 255 bytes. - */ - unsigned scan_start = 0; - unsigned i, j; - unsigned div_spoiler; - unsigned rotate_offset; - - OPENSSL_assert(rec->orig_len >= md_size); - OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); - -#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); - /* - * div_spoiler contains a multiple of md_size that is used to cause the - * modulo operation to be constant time. Without this, the time varies - * based on the amount of padding when running on Intel chips at least. - * The aim of right-shifting md_size is so that the compiler doesn't - * figure out that it can remove div_spoiler as that would require it to - * prove that md_size is always even, which I hope is beyond it. - */ - div_spoiler = md_size >> 1; - div_spoiler <<= (sizeof(div_spoiler) - 1) * 8; - rotate_offset = (div_spoiler + mac_start - scan_start) % md_size; - - memset(rotated_mac, 0, md_size); - for (i = scan_start, j = 0; i < rec->orig_len; i++) { - unsigned char mac_started = constant_time_ge_8(i, mac_start); - unsigned char mac_ended = constant_time_ge_8(i, mac_end); - unsigned char b = rec->data[i]; - rotated_mac[j++] |= b & mac_started & ~mac_ended; - j &= constant_time_lt(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(rotate_offset, md_size); - } -#else - memset(out, 0, md_size); - rotate_offset = md_size - rotate_offset; - rotate_offset &= constant_time_lt(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(j, rotate_offset); - rotate_offset++; - rotate_offset &= constant_time_lt(rotate_offset, md_size); - } -#endif -} - /* * u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in * little-endian order. The value of p is advanced by four. @@ -328,9 +61,6 @@ static void tls1_sha1_final_raw(void *ctx, unsigned char *md_out) l2n(sha1->h4, md_out); } -#define LARGEST_DIGEST_CTX SHA_CTX - -#ifndef OPENSSL_NO_SHA256 static void tls1_sha256_final_raw(void *ctx, unsigned char *md_out) { SHA256_CTX *sha256 = ctx; @@ -341,11 +71,6 @@ static void tls1_sha256_final_raw(void *ctx, unsigned char *md_out) } } -# undef LARGEST_DIGEST_CTX -# define LARGEST_DIGEST_CTX SHA256_CTX -#endif - -#ifndef OPENSSL_NO_SHA512 static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) { SHA512_CTX *sha512 = ctx; @@ -356,9 +81,8 @@ static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) } } -# undef LARGEST_DIGEST_CTX -# define LARGEST_DIGEST_CTX SHA512_CTX -#endif +#undef LARGEST_DIGEST_CTX +#define LARGEST_DIGEST_CTX SHA512_CTX /* * ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function @@ -366,19 +90,13 @@ static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out) */ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) { - if (FIPS_mode()) - return 0; switch (EVP_MD_CTX_type(ctx)) { case NID_md5: case NID_sha1: -#ifndef OPENSSL_NO_SHA256 case NID_sha224: case NID_sha256: -#endif -#ifndef OPENSSL_NO_SHA512 case NID_sha384: case NID_sha512: -#endif return 1; default: return 0; @@ -405,16 +123,17 @@ char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx) * functions, above, we know that data_plus_mac_size is large enough to contain * a padding byte and MAC. (If the padding was invalid, it might contain the * padding too. ) + * Returns 1 on success or 0 on error */ -void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, - unsigned char *md_out, - size_t *md_out_size, - const unsigned char header[13], - const unsigned char *data, - size_t data_plus_mac_size, - size_t data_plus_mac_plus_padding_size, - const unsigned char *mac_secret, - unsigned mac_secret_length, char is_sslv3) +int ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, + unsigned char *md_out, + size_t *md_out_size, + const unsigned char header[13], + const unsigned char *data, + size_t data_plus_mac_size, + size_t data_plus_mac_plus_padding_size, + const unsigned char *mac_secret, + size_t mac_secret_length, char is_sslv3) { union { double align; @@ -422,23 +141,24 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, } md_state; void (*md_final_raw) (void *ctx, unsigned char *md_out); void (*md_transform) (void *ctx, const unsigned char *block); - unsigned md_size, md_block_size = 64; - unsigned sslv3_pad_length = 40, header_length, variance_blocks, + size_t md_size, md_block_size = 64; + size_t sslv3_pad_length = 40, header_length, variance_blocks, len, max_mac_bytes, num_blocks, num_starting_blocks, k, mac_end_offset, c, index_a, index_b; - unsigned int bits; /* at most 18 bits */ + size_t bits; /* at most 18 bits */ unsigned char length_bytes[MAX_HASH_BIT_COUNT_BYTES]; /* hmac_pad is the masked HMAC key. */ unsigned char hmac_pad[MAX_HASH_BLOCK_SIZE]; unsigned char first_block[MAX_HASH_BLOCK_SIZE]; unsigned char mac_out[EVP_MAX_MD_SIZE]; - unsigned i, j, md_out_size_u; - EVP_MD_CTX md_ctx; + size_t i, j; + unsigned md_out_size_u; + EVP_MD_CTX *md_ctx = NULL; /* * mdLengthSize is the number of bytes in the length field that * terminates * the hash. */ - unsigned md_length_size = 8; + size_t md_length_size = 8; char length_is_big_endian = 1; int ret; @@ -446,11 +166,13 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, * This is a, hopefully redundant, check that allows us to forget about * many possible overflows later in this function. */ - OPENSSL_assert(data_plus_mac_plus_padding_size < 1024 * 1024); + if (!ossl_assert(data_plus_mac_plus_padding_size < 1024 * 1024)) + return 0; switch (EVP_MD_CTX_type(ctx)) { case NID_md5: - MD5_Init((MD5_CTX *)md_state.c); + if (MD5_Init((MD5_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_md5_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))MD5_Transform; @@ -459,31 +181,32 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, length_is_big_endian = 0; break; case NID_sha1: - SHA1_Init((SHA_CTX *)md_state.c); + if (SHA1_Init((SHA_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha1_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA1_Transform; md_size = 20; break; -#ifndef OPENSSL_NO_SHA256 case NID_sha224: - SHA224_Init((SHA256_CTX *)md_state.c); + if (SHA224_Init((SHA256_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha256_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; md_size = 224 / 8; break; case NID_sha256: - SHA256_Init((SHA256_CTX *)md_state.c); + if (SHA256_Init((SHA256_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha256_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA256_Transform; md_size = 32; break; -#endif -#ifndef OPENSSL_NO_SHA512 case NID_sha384: - SHA384_Init((SHA512_CTX *)md_state.c); + if (SHA384_Init((SHA512_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha512_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; @@ -492,7 +215,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, md_length_size = 16; break; case NID_sha512: - SHA512_Init((SHA512_CTX *)md_state.c); + if (SHA512_Init((SHA512_CTX *)md_state.c) <= 0) + return 0; md_final_raw = tls1_sha512_final_raw; md_transform = (void (*)(void *ctx, const unsigned char *block))SHA512_Transform; @@ -500,21 +224,20 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, md_block_size = 128; md_length_size = 16; break; -#endif default: /* * ssl3_cbc_record_digest_supported should have been called first to * check that the hash function is supported. */ - OPENSSL_assert(0); - if (md_out_size) - *md_out_size = -1; - return; + if (md_out_size != NULL) + *md_out_size = 0; + return ossl_assert(0); } - OPENSSL_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES); - OPENSSL_assert(md_block_size <= MAX_HASH_BLOCK_SIZE); - OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE); + if (!ossl_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES) + || !ossl_assert(md_block_size <= MAX_HASH_BLOCK_SIZE) + || !ossl_assert(md_size <= EVP_MAX_MD_SIZE)) + return 0; header_length = 13; if (is_sslv3) { @@ -610,7 +333,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, */ bits += 8 * md_block_size; memset(hmac_pad, 0, md_block_size); - OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad)); + if (!ossl_assert(mac_secret_length <= sizeof(hmac_pad))) + return 0; memcpy(hmac_pad, mac_secret, mac_secret_length); for (i = 0; i < md_block_size; i++) hmac_pad[i] ^= 0x36; @@ -634,12 +358,22 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, if (k > 0) { if (is_sslv3) { + size_t overhang; + /* * The SSLv3 header is larger than a single block. overhang is * the number of bytes beyond a single block that the header - * consumes: either 7 bytes (SHA1) or 11 bytes (MD5). + * consumes: either 7 bytes (SHA1) or 11 bytes (MD5). There are no + * ciphersuites in SSLv3 that are not SHA1 or MD5 based and + * therefore we can be confident that the header_length will be + * greater than |md_block_size|. However we add a sanity check just + * in case */ - unsigned overhang = header_length - md_block_size; + if (header_length <= md_block_size) { + /* Should never happen */ + return 0; + } + overhang = header_length - md_block_size; md_transform(md_state.c, header); memcpy(first_block, header + md_block_size, overhang); memcpy(first_block + overhang, data, md_block_size - overhang); @@ -667,8 +401,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, for (i = num_starting_blocks; i <= num_starting_blocks + variance_blocks; i++) { unsigned char block[MAX_HASH_BLOCK_SIZE]; - unsigned char is_block_a = constant_time_eq_8(i, index_a); - unsigned char is_block_b = constant_time_eq_8(i, index_b); + unsigned char is_block_a = constant_time_eq_8_s(i, index_a); + unsigned char is_block_b = constant_time_eq_8_s(i, index_b); for (j = 0; j < md_block_size; j++) { unsigned char b = 0, is_past_c, is_past_cp1; if (k < header_length) @@ -677,8 +411,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, b = data[k - header_length]; k++; - is_past_c = is_block_a & constant_time_ge_8(j, c); - is_past_cp1 = is_block_a & constant_time_ge_8(j, c + 1); + is_past_c = is_block_a & constant_time_ge_8_s(j, c); + is_past_cp1 = is_block_a & constant_time_ge_8_s(j, c + 1); /* * If this is the block containing the end of the application * data, and we are at the offset for the 0x80 value, then @@ -686,8 +420,8 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, */ b = constant_time_select_8(is_past_c, 0x80, b); /* - * If this the the block containing the end of the application - * data and we're past the 0x80 value then just write zero. + * If this block contains the end of the application data + * and we're past the 0x80 value then just write zero. */ b = b & ~is_past_cp1; /* @@ -717,71 +451,36 @@ void ssl3_cbc_digest_record(const EVP_MD_CTX *ctx, mac_out[j] |= block[j] & is_block_b; } - EVP_MD_CTX_init(&md_ctx); - EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */ ); + md_ctx = EVP_MD_CTX_new(); + if (md_ctx == NULL) + goto err; + if (EVP_DigestInit_ex(md_ctx, EVP_MD_CTX_md(ctx), NULL /* engine */ ) <= 0) + goto err; if (is_sslv3) { /* We repurpose |hmac_pad| to contain the SSLv3 pad2 block. */ memset(hmac_pad, 0x5c, sslv3_pad_length); - EVP_DigestUpdate(&md_ctx, mac_secret, mac_secret_length); - EVP_DigestUpdate(&md_ctx, hmac_pad, sslv3_pad_length); - EVP_DigestUpdate(&md_ctx, mac_out, md_size); + if (EVP_DigestUpdate(md_ctx, mac_secret, mac_secret_length) <= 0 + || EVP_DigestUpdate(md_ctx, hmac_pad, sslv3_pad_length) <= 0 + || EVP_DigestUpdate(md_ctx, mac_out, md_size) <= 0) + goto err; } else { /* Complete the HMAC in the standard manner. */ for (i = 0; i < md_block_size; i++) hmac_pad[i] ^= 0x6a; - EVP_DigestUpdate(&md_ctx, hmac_pad, md_block_size); - EVP_DigestUpdate(&md_ctx, mac_out, md_size); + if (EVP_DigestUpdate(md_ctx, hmac_pad, md_block_size) <= 0 + || EVP_DigestUpdate(md_ctx, mac_out, md_size) <= 0) + goto err; } - ret = EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u); + /* TODO(size_t): Convert me */ + ret = EVP_DigestFinal(md_ctx, md_out, &md_out_size_u); if (ret && md_out_size) *md_out_size = md_out_size_u; - EVP_MD_CTX_cleanup(&md_ctx); -} - -/* - * Due to the need to use EVP in FIPS mode we can't reimplement digests but - * we can ensure the number of blocks processed is equal for all cases by - * digesting additional data. - */ + EVP_MD_CTX_free(md_ctx); -void tls_fips_digest_extra(const EVP_CIPHER_CTX *cipher_ctx, - EVP_MD_CTX *mac_ctx, const unsigned char *data, - size_t data_len, size_t orig_len) -{ - size_t block_size, digest_pad, blocks_data, blocks_orig; - if (EVP_CIPHER_CTX_mode(cipher_ctx) != EVP_CIPH_CBC_MODE) - return; - block_size = EVP_MD_CTX_block_size(mac_ctx); - /*- - * We are in FIPS mode if we get this far so we know we have only SHA* - * digests and TLS to deal with. - * Minimum digest padding length is 17 for SHA384/SHA512 and 9 - * otherwise. - * Additional header is 13 bytes. To get the number of digest blocks - * processed round up the amount of data plus padding to the nearest - * block length. Block length is 128 for SHA384/SHA512 and 64 otherwise. - * So we have: - * blocks = (payload_len + digest_pad + 13 + block_size - 1)/block_size - * equivalently: - * blocks = (payload_len + digest_pad + 12)/block_size + 1 - * HMAC adds a constant overhead. - * We're ultimately only interested in differences so this becomes - * blocks = (payload_len + 29)/128 - * for SHA384/SHA512 and - * blocks = (payload_len + 21)/64 - * otherwise. - */ - digest_pad = block_size == 64 ? 21 : 29; - blocks_orig = (orig_len + digest_pad) / block_size; - blocks_data = (data_len + digest_pad) / block_size; - /* - * MAC enough blocks to make up the difference between the original and - * actual lengths plus one extra block to ensure this is never a no op. - * The "data" pointer should always have enough space to perform this - * operation as it is large enough for a maximum length TLS buffer. - */ - EVP_DigestSignUpdate(mac_ctx, data, - (blocks_orig - blocks_data + 1) * block_size); + return 1; + err: + EVP_MD_CTX_free(md_ctx); + return 0; }