Fix tls_cbc_digest_record is slow using SHA-384 and short messages

[openssl.git] / ssl / s3_cbc.c

diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c
index f8d7aed3e15b629ecbeac3be5820844dfe5885cb..8e11864b07f028776261e9c23879ee6b3a70b662 100644 (file)
--- a/ssl/s3_cbc.c
+++ b/ssl/s3_cbc.c
@@ -7,9 +7,9 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include <assert.h>
 #include "internal/constant_time_locl.h"
 #include "ssl_locl.h"
+#include "internal/cryptlib.h"
 
 #include <openssl/md5.h>
 #include <openssl/sha.h>
@@ -229,15 +229,14 @@ int ssl3_cbc_digest_record(const EVP_MD_CTX *ctx,
          * ssl3_cbc_record_digest_supported should have been called first to
          * check that the hash function is supported.
          */
-        assert(0);
-        if (md_out_size)
+        if (md_out_size != NULL)
             *md_out_size = 0;
-        return 0;
+        return ossl_assert(0);
     }
 
-    if (!ossl_assert(md_length_size <= MAX_HASH_BIT_COUNT_BYTES
-                    && md_block_size <= MAX_HASH_BLOCK_SIZE
-                    && 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;
@@ -257,12 +256,13 @@ int ssl3_cbc_digest_record(const EVP_MD_CTX *ctx,
      * 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
+     * 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 : 6;
+    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
@@ -421,8 +421,8 @@ int 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;
             /*