Fix DTLS retransmission from previous session.
authorDr. Stephen Henson <steve@openssl.org>
Fri, 20 Dec 2013 15:26:50 +0000 (15:26 +0000)
committerDr. Stephen Henson <steve@openssl.org>
Fri, 20 Dec 2013 23:12:18 +0000 (23:12 +0000)
For DTLS we might need to retransmit messages from the previous session
so keep a copy of write context in DTLS retransmission buffers instead
of replacing it after sending CCS. CVE-2013-6450.

CHANGES
ssl/d1_both.c
ssl/ssl_locl.h
ssl/t1_enc.c

diff --git a/CHANGES b/CHANGES
index cfaebba..173be24 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,11 @@
 
  Changes between 1.0.1e and 1.0.1f [xx XXX xxxx]
 
+  *) Keep original DTLS digest and encryption contexts in retransmission
+     structures so we can use the previous session parameters if they need
+     to be resent. (CVE-2013-6450)
+     [Steve Henson]
+
   *) Add option SSL_OP_SAFARI_ECDHE_ECDSA_BUG (part of SSL_OP_ALL) which
      avoids preferring ECDHE-ECDSA ciphers when the client appears to be
      Safari on OS X.  Safari on OS X 10.8..10.8.3 advertises support for
index 65ec001..7a5596a 100644 (file)
@@ -214,6 +214,12 @@ dtls1_hm_fragment_new(unsigned long frag_len, int reassembly)
 static void
 dtls1_hm_fragment_free(hm_fragment *frag)
        {
+
+       if (frag->msg_header.is_ccs)
+               {
+               EVP_CIPHER_CTX_free(frag->msg_header.saved_retransmit_state.enc_write_ctx);
+               EVP_MD_CTX_destroy(frag->msg_header.saved_retransmit_state.write_hash);
+               }
        if (frag->fragment) OPENSSL_free(frag->fragment);
        if (frag->reassembly) OPENSSL_free(frag->reassembly);
        OPENSSL_free(frag);
index 96ce9a7..e485907 100644 (file)
@@ -621,6 +621,8 @@ extern SSL3_ENC_METHOD TLSv1_enc_data;
 extern SSL3_ENC_METHOD SSLv3_enc_data;
 extern SSL3_ENC_METHOD DTLSv1_enc_data;
 
+#define SSL_IS_DTLS(s) (s->method->version == DTLS1_VERSION)
+
 #define IMPLEMENT_tls_meth_func(version, func_name, s_accept, s_connect, \
                                s_get_meth) \
 const SSL_METHOD *func_name(void)  \
index 72015f5..56db834 100644 (file)
@@ -414,15 +414,20 @@ int tls1_change_cipher_state(SSL *s, int which)
                        s->mac_flags |= SSL_MAC_FLAG_WRITE_MAC_STREAM;
                        else
                        s->mac_flags &= ~SSL_MAC_FLAG_WRITE_MAC_STREAM;
-               if (s->enc_write_ctx != NULL)
+               if (s->enc_write_ctx != NULL && !SSL_IS_DTLS(s))
                        reuse_dd = 1;
-               else if ((s->enc_write_ctx=OPENSSL_malloc(sizeof(EVP_CIPHER_CTX))) == NULL)
+               else if ((s->enc_write_ctx=EVP_CIPHER_CTX_new()) == NULL)
                        goto err;
-               else
-                       /* make sure it's intialized in case we exit later with an error */
-                       EVP_CIPHER_CTX_init(s->enc_write_ctx);
                dd= s->enc_write_ctx;
-               mac_ctx = ssl_replace_hash(&s->write_hash,NULL);
+               if (SSL_IS_DTLS(s))
+                       {
+                       mac_ctx = EVP_MD_CTX_create();
+                       if (!mac_ctx)
+                               goto err;
+                       s->write_hash = mac_ctx;
+                       }
+               else
+                       mac_ctx = ssl_replace_hash(&s->write_hash,NULL);
 #ifndef OPENSSL_NO_COMP
                if (s->compress != NULL)
                        {