+++ /dev/null
-/*
- * Copyright 2012-2018 The OpenSSL Project Authors. All Rights Reserved.
- *
- * Licensed under the OpenSSL license (the "License"). You may not use
- * this file except in compliance with the License. You can obtain a copy
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
-
-#include "internal/constant_time_locl.h"
-#include "ssl_locl.h"
-#include "internal/cryptlib.h"
-
-#include <openssl/md5.h>
-#include <openssl/sha.h>
-
-/*
- * MAX_HASH_BIT_COUNT_BYTES is the maximum number of bytes in the hash's
- * length field. (SHA-384/512 have 128-bit length.)
- */
-#define MAX_HASH_BIT_COUNT_BYTES 16
-
-/*
- * MAX_HASH_BLOCK_SIZE is the maximum hash block size that we'll support.
- * Currently SHA-384/512 has a 128-byte block size and that's the largest
- * supported by TLS.)
- */
-#define MAX_HASH_BLOCK_SIZE 128
-
-/*
- * 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.
- */
-#define u32toLE(n, p) \
- (*((p)++)=(unsigned char)(n), \
- *((p)++)=(unsigned char)(n>>8), \
- *((p)++)=(unsigned char)(n>>16), \
- *((p)++)=(unsigned char)(n>>24))
-
-/*
- * These functions serialize the state of a hash and thus perform the
- * standard "final" operation without adding the padding and length that such
- * a function typically does.
- */
-static void tls1_md5_final_raw(void *ctx, unsigned char *md_out)
-{
- MD5_CTX *md5 = ctx;
- u32toLE(md5->A, md_out);
- u32toLE(md5->B, md_out);
- u32toLE(md5->C, md_out);
- u32toLE(md5->D, md_out);
-}
-
-static void tls1_sha1_final_raw(void *ctx, unsigned char *md_out)
-{
- SHA_CTX *sha1 = ctx;
- l2n(sha1->h0, md_out);
- l2n(sha1->h1, md_out);
- l2n(sha1->h2, md_out);
- l2n(sha1->h3, md_out);
- l2n(sha1->h4, md_out);
-}
-
-static void tls1_sha256_final_raw(void *ctx, unsigned char *md_out)
-{
- SHA256_CTX *sha256 = ctx;
- unsigned i;
-
- for (i = 0; i < 8; i++) {
- l2n(sha256->h[i], md_out);
- }
-}
-
-static void tls1_sha512_final_raw(void *ctx, unsigned char *md_out)
-{
- SHA512_CTX *sha512 = ctx;
- unsigned i;
-
- for (i = 0; i < 8; i++) {
- l2n8(sha512->h[i], md_out);
- }
-}
-
-#undef LARGEST_DIGEST_CTX
-#define LARGEST_DIGEST_CTX SHA512_CTX
-
-/*
- * ssl3_cbc_record_digest_supported returns 1 iff |ctx| uses a hash function
- * which ssl3_cbc_digest_record supports.
- */
-char ssl3_cbc_record_digest_supported(const EVP_MD_CTX *ctx)
-{
- switch (EVP_MD_CTX_type(ctx)) {
- case NID_md5:
- case NID_sha1:
- case NID_sha224:
- case NID_sha256:
- case NID_sha384:
- case NID_sha512:
- return 1;
- default:
- return 0;
- }
-}
-
-/*-
- * ssl3_cbc_digest_record computes the MAC of a decrypted, padded SSLv3/TLS
- * record.
- *
- * ctx: the EVP_MD_CTX from which we take the hash function.
- * ssl3_cbc_record_digest_supported must return true for this EVP_MD_CTX.
- * md_out: the digest output. At most EVP_MAX_MD_SIZE bytes will be written.
- * md_out_size: if non-NULL, the number of output bytes is written here.
- * header: the 13-byte, TLS record header.
- * data: the record data itself, less any preceding explicit IV.
- * data_plus_mac_size: the secret, reported length of the data and MAC
- * once the padding has been removed.
- * data_plus_mac_plus_padding_size: the public length of the whole
- * record, including padding.
- * is_sslv3: non-zero if we are to use SSLv3. Otherwise, TLS.
- *
- * On entry: by virtue of having been through one of the remove_padding
- * 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
- */
-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;
- unsigned char c[sizeof(LARGEST_DIGEST_CTX)];
- } md_state;
- void (*md_final_raw) (void *ctx, unsigned char *md_out);
- void (*md_transform) (void *ctx, const unsigned char *block);
- 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;
- 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];
- 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.
- */
- size_t md_length_size = 8;
- char length_is_big_endian = 1;
- int ret;
-
- /*
- * This is a, hopefully redundant, check that allows us to forget about
- * many possible overflows later in this function.
- */
- if (!ossl_assert(data_plus_mac_plus_padding_size < 1024 * 1024))
- return 0;
-
- switch (EVP_MD_CTX_type(ctx)) {
- case NID_md5:
- 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;
- md_size = 16;
- sslv3_pad_length = 48;
- length_is_big_endian = 0;
- break;
- case NID_sha1:
- 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;
- case NID_sha224:
- 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:
- 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;
- case NID_sha384:
- 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;
- md_size = 384 / 8;
- md_block_size = 128;
- md_length_size = 16;
- break;
- case NID_sha512:
- 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;
- md_size = 64;
- md_block_size = 128;
- md_length_size = 16;
- break;
- default:
- /*
- * ssl3_cbc_record_digest_supported should have been called first to
- * check that the hash function is supported.
- */
- if (md_out_size != NULL)
- *md_out_size = 0;
- return ossl_assert(0);
- }
-
- 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) {
- header_length = mac_secret_length + sslv3_pad_length + 8 /* sequence
- * number */ +
- 1 /* record type */ +
- 2 /* record length */ ;
- }
-
- /*
- * variance_blocks is the number of blocks of the hash that we have to
- * calculate in constant time because they could be altered by the
- * padding value. In SSLv3, the padding must be minimal so the end of
- * the plaintext varies by, at most, 15+20 = 35 bytes. (We conservatively
- * assume that the MAC size varies from 0..20 bytes.) In case the 9 bytes
- * of hash termination (0x80 + 64-bit length) don't fit in the final
- * block, we say that the final two blocks can vary based on the padding.
- * TLSv1 has MACs up to 48 bytes long (SHA-384) and the padding is not
- * required to be minimal. Therefore we say that the final |variance_blocks|
- * blocks can
- * vary based on the padding. Later in the function, if the message is
- * short and there obviously cannot be this many blocks then
- * variance_blocks can be reduced.
- */
- variance_blocks = is_sslv3 ? 2 : ( ((255 + 1 + md_size + md_block_size - 1) / md_block_size) + 1);
- /*
- * From now on we're dealing with the MAC, which conceptually has 13
- * bytes of `header' before the start of the data (TLS) or 71/75 bytes
- * (SSLv3)
- */
- len = data_plus_mac_plus_padding_size + header_length;
- /*
- * max_mac_bytes contains the maximum bytes of bytes in the MAC,
- * including * |header|, assuming that there's no padding.
- */
- max_mac_bytes = len - md_size - 1;
- /* num_blocks is the maximum number of hash blocks. */
- num_blocks =
- (max_mac_bytes + 1 + md_length_size + md_block_size -
- 1) / md_block_size;
- /*
- * In order to calculate the MAC in constant time we have to handle the
- * final blocks specially because the padding value could cause the end
- * to appear somewhere in the final |variance_blocks| blocks and we can't
- * leak where. However, |num_starting_blocks| worth of data can be hashed
- * right away because no padding value can affect whether they are
- * plaintext.
- */
- num_starting_blocks = 0;
- /*
- * k is the starting byte offset into the conceptual header||data where
- * we start processing.
- */
- k = 0;
- /*
- * mac_end_offset is the index just past the end of the data to be MACed.
- */
- mac_end_offset = data_plus_mac_size + header_length - md_size;
- /*
- * c is the index of the 0x80 byte in the final hash block that contains
- * application data.
- */
- c = mac_end_offset % md_block_size;
- /*
- * index_a is the hash block number that contains the 0x80 terminating
- * value.
- */
- index_a = mac_end_offset / md_block_size;
- /*
- * index_b is the hash block number that contains the 64-bit hash length,
- * in bits.
- */
- index_b = (mac_end_offset + md_length_size) / md_block_size;
- /*
- * bits is the hash-length in bits. It includes the additional hash block
- * for the masked HMAC key, or whole of |header| in the case of SSLv3.
- */
-
- /*
- * For SSLv3, if we're going to have any starting blocks then we need at
- * least two because the header is larger than a single block.
- */
- if (num_blocks > variance_blocks + (is_sslv3 ? 1 : 0)) {
- num_starting_blocks = num_blocks - variance_blocks;
- k = md_block_size * num_starting_blocks;
- }
-
- bits = 8 * mac_end_offset;
- if (!is_sslv3) {
- /*
- * Compute the initial HMAC block. For SSLv3, the padding and secret
- * bytes are included in |header| because they take more than a
- * single block.
- */
- bits += 8 * md_block_size;
- memset(hmac_pad, 0, md_block_size);
- 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;
-
- md_transform(md_state.c, hmac_pad);
- }
-
- if (length_is_big_endian) {
- memset(length_bytes, 0, md_length_size - 4);
- length_bytes[md_length_size - 4] = (unsigned char)(bits >> 24);
- length_bytes[md_length_size - 3] = (unsigned char)(bits >> 16);
- length_bytes[md_length_size - 2] = (unsigned char)(bits >> 8);
- length_bytes[md_length_size - 1] = (unsigned char)bits;
- } else {
- memset(length_bytes, 0, md_length_size);
- length_bytes[md_length_size - 5] = (unsigned char)(bits >> 24);
- length_bytes[md_length_size - 6] = (unsigned char)(bits >> 16);
- length_bytes[md_length_size - 7] = (unsigned char)(bits >> 8);
- length_bytes[md_length_size - 8] = (unsigned char)bits;
- }
-
- 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). 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
- */
- 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);
- md_transform(md_state.c, first_block);
- for (i = 1; i < k / md_block_size - 1; i++)
- md_transform(md_state.c, data + md_block_size * i - overhang);
- } else {
- /* k is a multiple of md_block_size. */
- memcpy(first_block, header, 13);
- memcpy(first_block + 13, data, md_block_size - 13);
- md_transform(md_state.c, first_block);
- for (i = 1; i < k / md_block_size; i++)
- md_transform(md_state.c, data + md_block_size * i - 13);
- }
- }
-
- memset(mac_out, 0, sizeof(mac_out));
-
- /*
- * We now process the final hash blocks. For each block, we construct it
- * in constant time. If the |i==index_a| then we'll include the 0x80
- * bytes and zero pad etc. For each block we selectively copy it, in
- * constant time, to |mac_out|.
- */
- 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_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)
- b = header[k];
- else if (k < data_plus_mac_plus_padding_size + header_length)
- b = data[k - header_length];
- k++;
-
- 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
- * overwrite b with 0x80.
- */
- b = constant_time_select_8(is_past_c, 0x80, b);
- /*
- * 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;
- /*
- * If this is index_b (the final block), but not index_a (the end
- * of the data), then the 64-bit length didn't fit into index_a
- * and we're having to add an extra block of zeros.
- */
- b &= ~is_block_b | is_block_a;
-
- /*
- * The final bytes of one of the blocks contains the length.
- */
- if (j >= md_block_size - md_length_size) {
- /* If this is index_b, write a length byte. */
- b = constant_time_select_8(is_block_b,
- length_bytes[j -
- (md_block_size -
- md_length_size)], b);
- }
- block[j] = b;
- }
-
- md_transform(md_state.c, block);
- md_final_raw(md_state.c, block);
- /* If this is index_b, copy the hash value to |mac_out|. */
- for (j = 0; j < md_size; j++)
- mac_out[j] |= block[j] & is_block_b;
- }
-
- 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);
-
- 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;
-
- if (EVP_DigestUpdate(md_ctx, hmac_pad, md_block_size) <= 0
- || EVP_DigestUpdate(md_ctx, mac_out, md_size) <= 0)
- goto err;
- }
- /* 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_free(md_ctx);
-
- return 1;
- err:
- EVP_MD_CTX_free(md_ctx);
- return 0;
-}
projects / openssl.git / blobdiff