Only allow one SGC handshake restart for SSL/TLS. (CVE-2011-4619)

1 files changed, 11 insertions, 0 deletions

diff --git a/ssl/ssl3.h b/ssl/ssl3.h
index 05a59e6ce0..badf89d3d9 100644
--- a/ssl/ssl3.h
+++ b/ssl/ssl3.h
@@ -388,6 +388,17 @@ typedef struct ssl3_buffer_st
 #define TLS1_FLAGS_TLS_PADDING_BUG		0x0008
 #define TLS1_FLAGS_SKIP_CERT_VERIFY		0x0010
 #define TLS1_FLAGS_KEEP_HANDSHAKE		0x0020
+ 
+/* SSL3_FLAGS_SGC_RESTART_DONE is set when we
+ * restart a handshake because of MS SGC and so prevents us
+ * from restarting the handshake in a loop. It's reset on a
+ * renegotiation, so effectively limits the client to one restart
+ * per negotiation. This limits the possibility of a DDoS
+ * attack where the client handshakes in a loop using SGC to
+ * restart. Servers which permit renegotiation can still be
+ * effected, but we can't prevent that.
+ */
+#define SSL3_FLAGS_SGC_RESTART_DONE		0x0040
 
 #ifndef OPENSSL_NO_SSL_INTERN