-/* 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 "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.) */
+/*
+ * 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.
+/*
+ * 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.) */
+ * supported by TLS.)
+ */
#define MAX_HASH_BLOCK_SIZE 128
-/* Some utility functions are needed:
- *
- * These macros return the given value with the MSB copied to all the other
- * bits. They use the fact that arithmetic shift shifts-in the sign bit.
- * However, this is not ensured by the C standard so you may need to replace
- * them with something else on odd CPUs. */
-#define DUPLICATE_MSB_TO_ALL(x) ( (unsigned)( (int)(x) >> (sizeof(int)*8-1) ) )
-#define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned char)(DUPLICATE_MSB_TO_ALL(x)))
-
-/* constant_time_ge returns 0xff if a>=b and 0x00 otherwise. */
-static unsigned constant_time_ge(unsigned a, unsigned b)
- {
- a -= b;
- return DUPLICATE_MSB_TO_ALL(~a);
- }
-
-/* constant_time_eq_8 returns 0xff if a==b and 0x00 otherwise. */
-static unsigned char constant_time_eq_8(unsigned char a, unsigned char b)
- {
- unsigned c = a ^ b;
- c--;
- return DUPLICATE_MSB_TO_ALL_8(c);
- }
-
-/* 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 (int)((good & 1) | (~good & -1));
+/*
+ * 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);
}
-/* 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 char has_explicit_iv =
- s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION;
- const unsigned overhead = 1 /* padding length byte */ +
- mac_size +
- (has_explicit_iv ? block_size : 0);
-
- /* 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];
-
- /* 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--;
- }
- }
-
- 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(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. We
- * AND the bottom 8 bits together and duplicate the result to all the
- * bits. */
- good &= good >> 4;
- good &= good >> 2;
- good &= good >> 1;
- good <<= sizeof(good)*8-1;
- good = DUPLICATE_MSB_TO_ALL(good);
-
- rec->length -= good & (padding_length+1);
-
- /* We can always safely skip the explicit IV. We check at the beginning
- * of this function that the record has at least enough space for the
- * IV, MAC and padding length byte. (These can be checked in
- * non-constant time because it's all public information.) So, if the
- * padding was invalid, then we didn't change |rec->length| and this is
- * safe. If the padding was valid then we know that we have at least
- * overhead+padding_length bytes of space and so this is still safe
- * because overhead accounts for the explicit IV. */
- if (has_explicit_iv)
- {
- rec->data += block_size;
- rec->input += block_size;
- rec->length -= block_size;
- rec->orig_len -= block_size;
- }
-
- return (int)((good & 1) | (~good & -1));
- }
-
-#if defined(_M_AMD64) || defined(__x86_64__)
-#define CBC_MAC_ROTATE_IN_PLACE
-#endif
-
-/* 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 cache-line, then the variable memory accesses don't actually affect
- * the timing. This has been tested to be true on Intel amd64 chips.
+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.
*/
-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[EVP_MAX_MD_SIZE*2];
- 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 = (unsigned char*) (((intptr_t)(rotated_mac_buf + 64)) & ~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; i < rec->orig_len;)
- {
- for (j = 0; j < md_size && i < rec->orig_len; i++, j++)
- {
- unsigned char mac_started = constant_time_ge(i, mac_start);
- unsigned char mac_ended = constant_time_ge(i, mac_end);
- unsigned char b = 0;
- b = rec->data[i];
- rotated_mac[j] |= b & mac_started & ~mac_ended;
- }
- }
-
- /* Now rotate the MAC */
-#if defined(CBC_MAC_ROTATE_IN_PLACE)
- j = 0;
- for (i = 0; i < md_size; i++)
- {
- unsigned char offset = (div_spoiler + rotate_offset + i) % md_size;
- out[j++] = rotated_mac[offset];
- }
-#else
- memset(out, 0, md_size);
- for (i = 0; i < md_size; i++)
- {
- unsigned char offset = (div_spoiler + md_size - rotate_offset + i) % md_size;
- for (j = 0; j < md_size; j++)
- out[j] |= rotated_mac[i] & constant_time_eq_8(j, offset);
- }
-#endif
- }
-
-/* 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;
- l2n(md5->A, md_out);
- l2n(md5->B, md_out);
- l2n(md5->C, md_out);
- l2n(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);
- }
- }
-
-/* 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)
- {
-#ifdef OPENSSL_FIPS
- if (FIPS_mode())
- return 0;
-#endif
- switch (ctx->digest->type)
- {
- 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
+{
+ 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.
* 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 preceeding explicit IV.
+ * 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
* 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. ) */
-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)
- {
- unsigned char md_state[sizeof(SHA512_CTX)];
- 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,
- 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 */
- 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;
- /* mdLengthSize is the number of bytes in the length field that terminates
- * the hash. */
- unsigned md_length_size = 8;
-
- /* 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);
-
- switch (ctx->digest->type)
- {
- case NID_md5:
- MD5_Init((MD5_CTX*)md_state);
- 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;
- break;
- case NID_sha1:
- SHA1_Init((SHA_CTX*)md_state);
- 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:
- SHA224_Init((SHA256_CTX*)md_state);
- 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);
- 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:
- SHA384_Init((SHA512_CTX*)md_state);
- 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:
- SHA512_Init((SHA512_CTX*)md_state);
- 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. */
- OPENSSL_assert(0);
- if (md_out_size)
- *md_out_size = -1;
- return;
- }
-
- 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);
-
- 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 six 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 : 6;
- /* 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);
- OPENSSL_assert(mac_secret_length <= sizeof(hmac_pad));
- memcpy(hmac_pad, mac_secret, mac_secret_length);
- for (i = 0; i < md_block_size; i++)
- hmac_pad[i] ^= 0x36;
-
- md_transform(md_state, hmac_pad);
- }
-
- 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;
-
- if (k > 0)
- {
- if (is_sslv3)
- {
- /* 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). */
- unsigned overhang = header_length-md_block_size;
- md_transform(md_state, header);
- memcpy(first_block, header + md_block_size, overhang);
- memcpy(first_block + overhang, data, md_block_size-overhang);
- md_transform(md_state, first_block);
- for (i = 1; i < k/md_block_size - 1; i++)
- md_transform(md_state, 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, first_block);
- for (i = 1; i < k/md_block_size; i++)
- md_transform(md_state, 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(i, index_a);
- unsigned char is_block_b = constant_time_eq_8(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(j, c);
- is_past_cp1 = is_block_a & constant_time_ge(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 = (b&~is_past_c) | (0x80&is_past_c);
- /* If this the the block containing 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 = (b&~is_block_b) | (is_block_b&length_bytes[j-(md_block_size-md_length_size)]);
- }
- block[j] = b;
- }
-
- md_transform(md_state, block);
- md_final_raw(md_state, 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;
- }
-
- EVP_MD_CTX_init(&md_ctx);
- EVP_DigestInit_ex(&md_ctx, ctx->digest, NULL /* engine */);
- 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);
- }
- 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);
- }
- EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u);
- if (md_out_size)
- *md_out_size = md_out_size_u;
- EVP_MD_CTX_cleanup(&md_ctx);
- }
-
-#ifdef OPENSSL_FIPS
-
-/* 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.
+ * padding too. )
+ * Returns 1 on success or 0 on error
*/
-
-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);
- }
-#endif
+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