- /* Chop the digest off the end :-) */
- EVP_MD_CTX_init(&md_ctx);
-
- EVP_MD_CTX_copy_ex( &md_ctx,hash);
- EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
- EVP_DigestUpdate(&md_ctx,ssl3_pad_1,npad);
- EVP_DigestUpdate(&md_ctx,seq,8);
- rec_char=rec->type;
- EVP_DigestUpdate(&md_ctx,&rec_char,1);
- p=md;
- s2n(rec->length,p);
- EVP_DigestUpdate(&md_ctx,md,2);
- EVP_DigestUpdate(&md_ctx,rec->input,rec->length);
- EVP_DigestFinal_ex( &md_ctx,md,NULL);
-
- EVP_MD_CTX_copy_ex( &md_ctx,hash);
- EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
- EVP_DigestUpdate(&md_ctx,ssl3_pad_2,npad);
- EVP_DigestUpdate(&md_ctx,md,md_size);
- EVP_DigestFinal_ex( &md_ctx,md,&md_size);
-
- EVP_MD_CTX_cleanup(&md_ctx);
+ if (!send &&
+ EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
+ ssl3_cbc_record_digest_supported(hash))
+ {
+ /* This is a CBC-encrypted record. We must avoid leaking any
+ * timing-side channel information about how many blocks of
+ * data we are hashing because that gives an attacker a
+ * timing-oracle. */
+
+ /* npad is, at most, 48 bytes and that's with MD5:
+ * 16 + 48 + 8 (sequence bytes) + 1 + 2 = 75.
+ *
+ * With SHA-1 (the largest hash speced for SSLv3) the hash size
+ * goes up 4, but npad goes down by 8, resulting in a smaller
+ * total size. */
+ unsigned char header[75];
+ unsigned j = 0;
+ memcpy(header+j, mac_sec, md_size);
+ j += md_size;
+ memcpy(header+j, ssl3_pad_1, npad);
+ j += npad;
+ memcpy(header+j, seq, 8);
+ j += 8;
+ header[j++] = rec->type;
+ header[j++] = rec->length >> 8;
+ header[j++] = rec->length & 0xff;
+
+ ssl3_cbc_digest_record(
+ hash,
+ md, &md_size,
+ header, rec->input,
+ rec->length + md_size, rec->orig_len,
+ mac_sec, md_size,
+ 1 /* is SSLv3 */);
+ }
+ else
+ {
+ unsigned int md_size_u;
+ /* Chop the digest off the end :-) */
+ EVP_MD_CTX_init(&md_ctx);
+
+ EVP_MD_CTX_copy_ex( &md_ctx,hash);
+ EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
+ EVP_DigestUpdate(&md_ctx,ssl3_pad_1,npad);
+ EVP_DigestUpdate(&md_ctx,seq,8);
+ rec_char=rec->type;
+ EVP_DigestUpdate(&md_ctx,&rec_char,1);
+ p=md;
+ s2n(rec->length,p);
+ EVP_DigestUpdate(&md_ctx,md,2);
+ EVP_DigestUpdate(&md_ctx,rec->input,rec->length);
+ EVP_DigestFinal_ex( &md_ctx,md,NULL);
+
+ EVP_MD_CTX_copy_ex( &md_ctx,hash);
+ EVP_DigestUpdate(&md_ctx,mac_sec,md_size);
+ EVP_DigestUpdate(&md_ctx,ssl3_pad_2,npad);
+ EVP_DigestUpdate(&md_ctx,md,md_size);
+ EVP_DigestFinal_ex( &md_ctx,md,&md_size_u);
+ md_size = md_size_u;
+
+ EVP_MD_CTX_cleanup(&md_ctx);
+ }