--- /dev/null
+/* ====================================================================
+ * 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). */
+
+#include <assert.h>
+#include <string.h>
+
+#include <openssl/digest.h>
+#include <openssl/nid.h>
+#include <openssl/sha.h>
+
+#include "../internal.h"
+#include "internal.h"
+#include "../fipsmodule/cipher/internal.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
+
+int EVP_tls_cbc_remove_padding(crypto_word_t *out_padding_ok, size_t *out_len,
+ const uint8_t *in, size_t in_len,
+ size_t block_size, size_t mac_size) {
+ const size_t overhead = 1 /* padding length byte */ + mac_size;
+
+ // These lengths are all public so we can test them in non-constant time.
+ if (overhead > in_len) {
+ return 0;
+ }
+
+ size_t padding_length = in[in_len - 1];
+
+ crypto_word_t good = constant_time_ge_w(in_len, 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.)
+ size_t to_check = 256; // maximum amount of padding, inc length byte.
+ if (to_check > in_len) {
+ to_check = in_len;
+ }
+
+ for (size_t i = 0; i < to_check; i++) {
+ uint8_t mask = constant_time_ge_8(padding_length, i);
+ uint8_t b = in[in_len - 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_w(0xff, good & 0xff);
+
+ // Always treat |padding_length| as zero on error. If, assuming block size of
+ // 16, a padding of [<15 arbitrary bytes> 15] treated |padding_length| as 16
+ // and returned -1, distinguishing good MAC and bad padding from bad MAC and
+ // bad padding would give POODLE's padding oracle.
+ padding_length = good & (padding_length + 1);
+ *out_len = in_len - padding_length;
+ *out_padding_ok = good;
+ return 1;
+}
+
+void EVP_tls_cbc_copy_mac(uint8_t *out, size_t md_size, const uint8_t *in,
+ size_t in_len, size_t orig_len) {
+ uint8_t rotated_mac1[EVP_MAX_MD_SIZE], rotated_mac2[EVP_MAX_MD_SIZE];
+ uint8_t *rotated_mac = rotated_mac1;
+ uint8_t *rotated_mac_tmp = rotated_mac2;
+
+ // mac_end is the index of |in| just after the end of the MAC.
+ size_t mac_end = in_len;
+ size_t mac_start = mac_end - md_size;
+
+ assert(orig_len >= in_len);
+ assert(in_len >= md_size);
+ assert(md_size <= EVP_MAX_MD_SIZE);
+
+ // scan_start contains the number of bytes that we can ignore because
+ // the MAC's position can only vary by 255 bytes.
+ size_t scan_start = 0;
+ // This information is public so it's safe to branch based on it.
+ if (orig_len > md_size + 255 + 1) {
+ scan_start = orig_len - (md_size + 255 + 1);
+ }
+
+ size_t rotate_offset = 0;
+ uint8_t mac_started = 0;
+ OPENSSL_memset(rotated_mac, 0, md_size);
+ for (size_t i = scan_start, j = 0; i < orig_len; i++, j++) {
+ if (j >= md_size) {
+ j -= md_size;
+ }
+ crypto_word_t is_mac_start = constant_time_eq_w(i, mac_start);
+ mac_started |= is_mac_start;
+ uint8_t mac_ended = constant_time_ge_8(i, mac_end);
+ rotated_mac[j] |= in[i] & mac_started & ~mac_ended;
+ // Save the offset that |mac_start| is mapped to.
+ rotate_offset |= j & is_mac_start;
+ }
+
+ // Now rotate the MAC. We rotate in log(md_size) steps, one for each bit
+ // position.
+ for (size_t offset = 1; offset < md_size; offset <<= 1, rotate_offset >>= 1) {
+ // Rotate by |offset| iff the corresponding bit is set in
+ // |rotate_offset|, placing the result in |rotated_mac_tmp|.
+ const uint8_t skip_rotate = (rotate_offset & 1) - 1;
+ for (size_t i = 0, j = offset; i < md_size; i++, j++) {
+ if (j >= md_size) {
+ j -= md_size;
+ }
+ rotated_mac_tmp[i] =
+ constant_time_select_8(skip_rotate, rotated_mac[i], rotated_mac[j]);
+ }
+
+ // Swap pointers so |rotated_mac| contains the (possibly) rotated value.
+ // Note the number of iterations and thus the identity of these pointers is
+ // public information.
+ uint8_t *tmp = rotated_mac;
+ rotated_mac = rotated_mac_tmp;
+ rotated_mac_tmp = tmp;
+ }
+
+ OPENSSL_memcpy(out, rotated_mac, md_size);
+}
+
+// u32toBE serialises an unsigned, 32-bit number (n) as four bytes at (p) in
+// big-endian order. The value of p is advanced by four.
+#define u32toBE(n, p) \
+ do { \
+ *((p)++) = (uint8_t)((n) >> 24); \
+ *((p)++) = (uint8_t)((n) >> 16); \
+ *((p)++) = (uint8_t)((n) >> 8); \
+ *((p)++) = (uint8_t)((n)); \
+ } while (0)
+
+// u64toBE serialises an unsigned, 64-bit number (n) as eight bytes at (p) in
+// big-endian order. The value of p is advanced by eight.
+#define u64toBE(n, p) \
+ do { \
+ *((p)++) = (uint8_t)((n) >> 56); \
+ *((p)++) = (uint8_t)((n) >> 48); \
+ *((p)++) = (uint8_t)((n) >> 40); \
+ *((p)++) = (uint8_t)((n) >> 32); \
+ *((p)++) = (uint8_t)((n) >> 24); \
+ *((p)++) = (uint8_t)((n) >> 16); \
+ *((p)++) = (uint8_t)((n) >> 8); \
+ *((p)++) = (uint8_t)((n)); \
+ } while (0)
+
+typedef union {
+ SHA_CTX sha1;
+ SHA256_CTX sha256;
+ SHA512_CTX sha512;
+} HASH_CTX;
+
+static void tls1_sha1_transform(HASH_CTX *ctx, const uint8_t *block) {
+ SHA1_Transform(&ctx->sha1, block);
+}
+
+static void tls1_sha256_transform(HASH_CTX *ctx, const uint8_t *block) {
+ SHA256_Transform(&ctx->sha256, block);
+}
+
+static void tls1_sha512_transform(HASH_CTX *ctx, const uint8_t *block) {
+ SHA512_Transform(&ctx->sha512, block);
+}
+
+// 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_sha1_final_raw(HASH_CTX *ctx, uint8_t *md_out) {
+ SHA_CTX *sha1 = &ctx->sha1;
+ u32toBE(sha1->h[0], md_out);
+ u32toBE(sha1->h[1], md_out);
+ u32toBE(sha1->h[2], md_out);
+ u32toBE(sha1->h[3], md_out);
+ u32toBE(sha1->h[4], md_out);
+}
+
+static void tls1_sha256_final_raw(HASH_CTX *ctx, uint8_t *md_out) {
+ SHA256_CTX *sha256 = &ctx->sha256;
+ for (unsigned i = 0; i < 8; i++) {
+ u32toBE(sha256->h[i], md_out);
+ }
+}
+
+static void tls1_sha512_final_raw(HASH_CTX *ctx, uint8_t *md_out) {
+ SHA512_CTX *sha512 = &ctx->sha512;
+ for (unsigned i = 0; i < 8; i++) {
+ u64toBE(sha512->h[i], md_out);
+ }
+}
+
+int EVP_tls_cbc_record_digest_supported(const EVP_MD *md) {
+ switch (EVP_MD_type(md)) {
+ case NID_sha1:
+ case NID_sha256:
+ case NID_sha384:
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+int EVP_tls_cbc_digest_record(const EVP_MD *md, uint8_t *md_out,
+ size_t *md_out_size, const uint8_t header[13],
+ const uint8_t *data, size_t data_plus_mac_size,
+ size_t data_plus_mac_plus_padding_size,
+ const uint8_t *mac_secret,
+ unsigned mac_secret_length) {
+ HASH_CTX md_state;
+ void (*md_final_raw)(HASH_CTX *ctx, uint8_t *md_out);
+ void (*md_transform)(HASH_CTX *ctx, const uint8_t *block);
+ unsigned md_size, md_block_size = 64;
+ // md_length_size is the number of bytes in the length field that terminates
+ // the hash.
+ unsigned md_length_size = 8;
+
+ // Bound the acceptable input so we can forget about many possible overflows
+ // later in this function. This is redundant with the record size limits in
+ // TLS.
+ if (data_plus_mac_plus_padding_size >= 1024 * 1024) {
+ assert(0);
+ return 0;
+ }
+
+ switch (EVP_MD_type(md)) {
+ case NID_sha1:
+ SHA1_Init(&md_state.sha1);
+ md_final_raw = tls1_sha1_final_raw;
+ md_transform = tls1_sha1_transform;
+ md_size = SHA_DIGEST_LENGTH;
+ break;
+
+ case NID_sha256:
+ SHA256_Init(&md_state.sha256);
+ md_final_raw = tls1_sha256_final_raw;
+ md_transform = tls1_sha256_transform;
+ md_size = SHA256_DIGEST_LENGTH;
+ break;
+
+ case NID_sha384:
+ SHA384_Init(&md_state.sha512);
+ md_final_raw = tls1_sha512_final_raw;
+ md_transform = tls1_sha512_transform;
+ md_size = SHA384_DIGEST_LENGTH;
+ md_block_size = 128;
+ md_length_size = 16;
+ break;
+
+ default:
+ // EVP_tls_cbc_record_digest_supported should have been called first to
+ // check that the hash function is supported.
+ assert(0);
+ *md_out_size = 0;
+ return 0;
+ }
+
+ assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES);
+ assert(md_block_size <= MAX_HASH_BLOCK_SIZE);
+ assert(md_size <= EVP_MAX_MD_SIZE);
+
+ static const size_t kHeaderLength = 13;
+
+ // kVarianceBlocks 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.
+ //
+ // 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.
+ static const size_t kVarianceBlocks = 6;
+
+ // From now on we're dealing with the MAC, which conceptually has 13
+ // bytes of `header' before the start of the data.
+ size_t len = data_plus_mac_plus_padding_size + kHeaderLength;
+ // max_mac_bytes contains the maximum bytes of bytes in the MAC, including
+ // |header|, assuming that there's no padding.
+ size_t max_mac_bytes = len - md_size - 1;
+ // num_blocks is the maximum number of hash blocks.
+ size_t 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 |kVarianceBlocks| 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.
+ size_t num_starting_blocks = 0;
+ // k is the starting byte offset into the conceptual header||data where
+ // we start processing.
+ size_t k = 0;
+ // mac_end_offset is the index just past the end of the data to be
+ // MACed.
+ size_t mac_end_offset = data_plus_mac_size + kHeaderLength - md_size;
+ // c is the index of the 0x80 byte in the final hash block that
+ // contains application data.
+ size_t c = mac_end_offset % md_block_size;
+ // index_a is the hash block number that contains the 0x80 terminating
+ // value.
+ size_t index_a = mac_end_offset / md_block_size;
+ // index_b is the hash block number that contains the 64-bit hash
+ // length, in bits.
+ size_t index_b = (mac_end_offset + md_length_size) / md_block_size;
+
+ if (num_blocks > kVarianceBlocks) {
+ num_starting_blocks = num_blocks - kVarianceBlocks;
+ k = md_block_size * num_starting_blocks;
+ }
+
+ // bits is the hash-length in bits. It includes the additional hash
+ // block for the masked HMAC key.
+ size_t bits = 8 * mac_end_offset; // at most 18 bits to represent
+
+ // Compute the initial HMAC block.
+ bits += 8 * md_block_size;
+ // hmac_pad is the masked HMAC key.
+ uint8_t hmac_pad[MAX_HASH_BLOCK_SIZE];
+ OPENSSL_memset(hmac_pad, 0, md_block_size);
+ assert(mac_secret_length <= sizeof(hmac_pad));
+ OPENSSL_memcpy(hmac_pad, mac_secret, mac_secret_length);
+ for (size_t i = 0; i < md_block_size; i++) {
+ hmac_pad[i] ^= 0x36;
+ }
+
+ md_transform(&md_state, hmac_pad);
+
+ // The length check means |bits| fits in four bytes.
+ uint8_t length_bytes[MAX_HASH_BIT_COUNT_BYTES];
+ OPENSSL_memset(length_bytes, 0, md_length_size - 4);
+ length_bytes[md_length_size - 4] = (uint8_t)(bits >> 24);
+ length_bytes[md_length_size - 3] = (uint8_t)(bits >> 16);
+ length_bytes[md_length_size - 2] = (uint8_t)(bits >> 8);
+ length_bytes[md_length_size - 1] = (uint8_t)bits;
+
+ if (k > 0) {
+ // k is a multiple of md_block_size.
+ uint8_t first_block[MAX_HASH_BLOCK_SIZE];
+ OPENSSL_memcpy(first_block, header, 13);
+ OPENSSL_memcpy(first_block + 13, data, md_block_size - 13);
+ md_transform(&md_state, first_block);
+ for (size_t i = 1; i < k / md_block_size; i++) {
+ md_transform(&md_state, data + md_block_size * i - 13);
+ }
+ }
+
+ uint8_t mac_out[EVP_MAX_MD_SIZE];
+ OPENSSL_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 (size_t i = num_starting_blocks;
+ i <= num_starting_blocks + kVarianceBlocks; i++) {
+ uint8_t block[MAX_HASH_BLOCK_SIZE];
+ uint8_t is_block_a = constant_time_eq_8(i, index_a);
+ uint8_t is_block_b = constant_time_eq_8(i, index_b);
+ for (size_t j = 0; j < md_block_size; j++) {
+ uint8_t b = 0;
+ if (k < kHeaderLength) {
+ b = header[k];
+ } else if (k < data_plus_mac_plus_padding_size + kHeaderLength) {
+ b = data[k - kHeaderLength];
+ }
+ k++;
+
+ uint8_t is_past_c = is_block_a & constant_time_ge_8(j, c);
+ uint8_t is_past_cp1 = is_block_a & constant_time_ge_8(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 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 = constant_time_select_8(
+ is_block_b, length_bytes[j - (md_block_size - md_length_size)], b);
+ }
+ 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 (size_t j = 0; j < md_size; j++) {
+ mac_out[j] |= block[j] & is_block_b;
+ }
+ }
+
+ EVP_MD_CTX md_ctx;
+ EVP_MD_CTX_init(&md_ctx);
+ if (!EVP_DigestInit_ex(&md_ctx, md, NULL /* engine */)) {
+ EVP_MD_CTX_cleanup(&md_ctx);
+ return 0;
+ }
+
+ // Complete the HMAC in the standard manner.
+ for (size_t 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);
+ unsigned md_out_size_u;
+ EVP_DigestFinal(&md_ctx, md_out, &md_out_size_u);
+ *md_out_size = md_out_size_u;
+ EVP_MD_CTX_cleanup(&md_ctx);
+
+ return 1;
+}
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