fix for CVE-2010-4180

[openssl.git] / ssl / s3_srvr.c

diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index a3bb3aef1ec5899be5ed9cffd1d7152f67b18516..e2d570f80f0a373b846755a2c115cb96a7c8f98d 100644 (file)
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -166,7 +166,6 @@ int ssl3_accept(SSL *s)
        BUF_MEM *buf;
        unsigned long l,Time=(unsigned long)time(NULL);
        void (*cb)(const SSL *ssl,int type,int val)=NULL;
-       long num1;
        int ret= -1;
        int new_state,state,skip=0;
 
@@ -248,6 +247,18 @@ int ssl3_accept(SSL *s)
                                s->state=SSL3_ST_SR_CLNT_HELLO_A;
                                s->ctx->stats.sess_accept++;
                                }
+                       else if (!s->s3->send_connection_binding &&
+                               !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION))
+                               {
+                               /* Server attempting to renegotiate with
+                                * client that doesn't support secure
+                                * renegotiation.
+                                */
+                               SSLerr(SSL_F_SSL3_ACCEPT, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
+                               ssl3_send_alert(s,SSL3_AL_FATAL,SSL_AD_HANDSHAKE_FAILURE);
+                               ret = -1;
+                               goto end;
+                               }
                        else
                                {
                                /* s->state == SSL_ST_RENEGOTIATE,
@@ -435,15 +446,24 @@ int ssl3_accept(SSL *s)
                        break;
                
                case SSL3_ST_SW_FLUSH:
-                       /* number of bytes to be flushed */
-                       num1=BIO_ctrl(s->wbio,BIO_CTRL_WPENDING,0,NULL);
-                       if (num1 > 0)
+
+                       /* This code originally checked to see if
+                        * any data was pending using BIO_CTRL_INFO
+                        * and then flushed. This caused problems
+                        * as documented in PR#1939. The proposed
+                        * fix doesn't completely resolve this issue
+                        * as buggy implementations of BIO_CTRL_PENDING
+                        * still exist. So instead we just flush
+                        * unconditionally.
+                        */
+
+                       s->rwstate=SSL_WRITING;
+                       if (BIO_flush(s->wbio) <= 0)
                                {
-                               s->rwstate=SSL_WRITING;
-                               num1=BIO_flush(s->wbio);
-                               if (num1 <= 0) { ret= -1; goto end; }
-                               s->rwstate=SSL_NOTHING;
+                               ret= -1;
+                               goto end;
                                }
+                       s->rwstate=SSL_NOTHING;
 
                        s->state=s->s3->tmp.next_state;
                        break;
@@ -907,6 +927,10 @@ int ssl3_get_client_hello(SSL *s)
                                break;
                                }
                        }
+/* Disabled because it can be used in a ciphersuite downgrade
+ * attack: CVE-2010-4180.
+ */
+#if 0
                if (j == 0 && (s->options & SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG) && (sk_SSL_CIPHER_num(ciphers) == 1))
                        {
                        /* Special case as client bug workaround: the previously used cipher may
@@ -921,6 +945,7 @@ int ssl3_get_client_hello(SSL *s)
                                j = 1;
                                }
                        }
+#endif
                if (j == 0)
                        {
                        /* we need to have the cipher in the cipher