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Index: openssl-0.9.8o/ssl/s3_srvr.c
===================================================================
--- openssl-0.9.8o.orig/ssl/s3_srvr.c 2012-03-13 21:44:39.000000000 +0100
+++ openssl-0.9.8o/ssl/s3_srvr.c 2012-03-13 21:44:42.000000000 +0100
@@ -235,6 +235,7 @@
}
s->init_num=0;
+ s->s3->flags &= ~SSL3_FLAGS_SGC_RESTART_DONE;
if (s->state != SSL_ST_RENEGOTIATE)
{
@@ -709,6 +710,13 @@
s->s3->tmp.reuse_message = 1;
if (s->s3->tmp.message_type == SSL3_MT_CLIENT_HELLO)
{
+ /* We only allow the client to restart the handshake once per
+ * negotiation. */
+ if (s->s3->flags & SSL3_FLAGS_SGC_RESTART_DONE)
+ {
+ SSLerr(SSL_F_SSL3_CHECK_CLIENT_HELLO, SSL_R_MULTIPLE_SGC_RESTARTS);
+ return -1;
+ }
/* Throw away what we have done so far in the current handshake,
* which will now be aborted. (A full SSL_clear would be too much.) */
#ifndef OPENSSL_NO_DH
@@ -725,6 +733,7 @@
s->s3->tmp.ecdh = NULL;
}
#endif
+ s->s3->flags |= SSL3_FLAGS_SGC_RESTART_DONE;
return 2;
}
return 1;
Index: openssl-0.9.8o/ssl/ssl.h
===================================================================
--- openssl-0.9.8o.orig/ssl/ssl.h 2012-03-13 21:44:39.000000000 +0100
+++ openssl-0.9.8o/ssl/ssl.h 2012-03-13 21:44:42.000000000 +0100
@@ -1739,6 +1739,7 @@
#define SSL_F_SSL3_CALLBACK_CTRL 233
#define SSL_F_SSL3_CHANGE_CIPHER_STATE 129
#define SSL_F_SSL3_CHECK_CERT_AND_ALGORITHM 130
+#define SSL_F_SSL3_CHECK_CLIENT_HELLO 292
#define SSL_F_SSL3_CLIENT_HELLO 131
#define SSL_F_SSL3_CONNECT 132
#define SSL_F_SSL3_CTRL 213
@@ -1974,6 +1975,7 @@
#define SSL_R_MISSING_TMP_RSA_KEY 172
#define SSL_R_MISSING_TMP_RSA_PKEY 173
#define SSL_R_MISSING_VERIFY_MESSAGE 174
+#define SSL_R_MULTIPLE_SGC_RESTARTS 325
#define SSL_R_NON_SSLV2_INITIAL_PACKET 175
#define SSL_R_NO_CERTIFICATES_RETURNED 176
#define SSL_R_NO_CERTIFICATE_ASSIGNED 177
Index: openssl-0.9.8o/ssl/ssl3.h
===================================================================
--- openssl-0.9.8o.orig/ssl/ssl3.h 2012-03-13 21:44:39.000000000 +0100
+++ openssl-0.9.8o/ssl/ssl3.h 2012-03-13 21:44:42.000000000 +0100
@@ -333,6 +333,17 @@
#define SSL3_FLAGS_DELAY_CLIENT_FINISHED 0x0002
#define SSL3_FLAGS_POP_BUFFER 0x0004
#define TLS1_FLAGS_TLS_PADDING_BUG 0x0008
+
+/* 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
typedef struct ssl3_state_st
{
Index: openssl-0.9.8o/ssl/ssl_err.c
===================================================================
--- openssl-0.9.8o.orig/ssl/ssl_err.c 2012-03-13 21:44:39.000000000 +0100
+++ openssl-0.9.8o/ssl/ssl_err.c 2012-03-13 21:44:42.000000000 +0100
@@ -1,6 +1,6 @@
/* ssl/ssl_err.c */
/* ====================================================================
- * Copyright (c) 1999-2008 The OpenSSL Project. All rights reserved.
+ * Copyright (c) 1999-2011 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -137,6 +137,7 @@
{ERR_FUNC(SSL_F_SSL3_CALLBACK_CTRL), "SSL3_CALLBACK_CTRL"},
{ERR_FUNC(SSL_F_SSL3_CHANGE_CIPHER_STATE), "SSL3_CHANGE_CIPHER_STATE"},
{ERR_FUNC(SSL_F_SSL3_CHECK_CERT_AND_ALGORITHM), "SSL3_CHECK_CERT_AND_ALGORITHM"},
+{ERR_FUNC(SSL_F_SSL3_CHECK_CLIENT_HELLO), "SSL3_CHECK_CLIENT_HELLO"},
{ERR_FUNC(SSL_F_SSL3_CLIENT_HELLO), "SSL3_CLIENT_HELLO"},
{ERR_FUNC(SSL_F_SSL3_CONNECT), "SSL3_CONNECT"},
{ERR_FUNC(SSL_F_SSL3_CTRL), "SSL3_CTRL"},
@@ -375,6 +376,7 @@
{ERR_REASON(SSL_R_MISSING_TMP_RSA_KEY) ,"missing tmp rsa key"},
{ERR_REASON(SSL_R_MISSING_TMP_RSA_PKEY) ,"missing tmp rsa pkey"},
{ERR_REASON(SSL_R_MISSING_VERIFY_MESSAGE),"missing verify message"},
+{ERR_REASON(SSL_R_MULTIPLE_SGC_RESTARTS) ,"multiple sgc restarts"},
{ERR_REASON(SSL_R_NON_SSLV2_INITIAL_PACKET),"non sslv2 initial packet"},
{ERR_REASON(SSL_R_NO_CERTIFICATES_RETURNED),"no certificates returned"},
{ERR_REASON(SSL_R_NO_CERTIFICATE_ASSIGNED),"no certificate assigned"},
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