[openssl-commits] [openssl] master update

[Matt Caswell]

The branch master has been updated
       via  1257adecd4afba978806b77bd5d45f32715d97d3 (commit)
      from  464175692f1f00a9e5a87f040d0c59184d63b53b (commit)


- Log -----------------------------------------------------------------
commit 1257adecd4afba978806b77bd5d45f32715d97d3
Author: David Benjamin <davidben at google.com>
Date:   Sat Mar 5 22:50:44 2016 -0500

    Tighten up logic around ChangeCipherSpec.
    
    ChangeCipherSpec messages have a defined value. They also may not occur
    in the middle of a handshake message. The current logic will accept a
    ChangeCipherSpec with value 2. It also would accept up to three bytes of
    handshake data before the ChangeCipherSpec which it would discard
    (because s->init_num gets reset).
    
    Instead, require that s->init_num is 0 when a ChangeCipherSpec comes in.
    
    RT#4391
    
    Reviewed-by: Andy Polyakov <appro at openssl.org>
    Reviewed-by: Matt Caswell <matt at openssl.org>

-----------------------------------------------------------------------

Summary of changes:
 ssl/statem/statem_lib.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index 6ceb9ec..eb3e591 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -354,6 +354,16 @@ int tls_get_message_header(SSL *s, int *mt)
                 return 0;
             }
             if (recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
+                /*
+		 * A ChangeCipherSpec must be a single byte and may not occur
+		 * in the middle of a handshake message.
+		 */
+                if (s->init_num != 0 || i != 1 || p[0] != SSL3_MT_CCS) {
+                    al = SSL_AD_UNEXPECTED_MESSAGE;
+                    SSLerr(SSL_F_TLS_GET_MESSAGE_HEADER,
+                           SSL_R_BAD_CHANGE_CIPHER_SPEC);
+                    goto f_err;
+                }
                 s->s3->tmp.message_type = *mt = SSL3_MT_CHANGE_CIPHER_SPEC;
                 s->init_num = i - 1;
                 s->s3->tmp.message_size = i;