Commit d0dc991c authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

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

parent 2ec0497f

ssl/s3_srvr.c

+10 −0
Original line number Diff line number Diff line
@@ -297,6 +297,7 @@ int ssl3_accept(SSL *s) 
				}



			s->init_num=0;

			s->s3->flags &= ~SSL3_FLAGS_SGC_RESTART_DONE;



			if (s->state != SSL_ST_RENEGOTIATE)

				{
@@ -871,6 +872,14 @@ int ssl3_check_client_hello(SSL *s) 
	int ok;

	long n;



	/* 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;

		}



	/* this function is called when we really expect a Certificate message,

	 * so permit appropriate message length */

	n=s->method->ssl_get_message(s,
@@ -899,6 +908,7 @@ int ssl3_check_client_hello(SSL *s) 
			s->s3->tmp.ecdh = NULL;

			}

#endif

		s->s3->flags |= SSL3_FLAGS_SGC_RESTART_DONE;

		return 2;

		}

	return 1;

ssl/ssl.h

+2 −0
Original line number Diff line number Diff line
@@ -2133,6 +2133,7 @@ void ERR_load_SSL_strings(void); 
#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			 315

#define SSL_F_SSL3_CLIENT_HELLO				 131

#define SSL_F_SSL3_CONNECT				 132

#define SSL_F_SSL3_CTRL					 213
@@ -2412,6 +2413,7 @@ void ERR_load_SSL_strings(void); 
#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			 370

#define SSL_R_NON_SSLV2_INITIAL_PACKET			 175

#define SSL_R_NO_CERTIFICATES_RETURNED			 176

#define SSL_R_NO_CERTIFICATE_ASSIGNED			 177

ssl/ssl3.h

+11 −0
Original line number Diff line number Diff line
@@ -389,6 +389,17 @@ typedef struct ssl3_buffer_st 
#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



typedef struct ssl3_state_st

ssl/ssl_err.c

+2 −0
Original line number Diff line number Diff line
@@ -138,6 +138,7 @@ static ERR_STRING_DATA SSL_str_functs[]= 
{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"},
@@ -420,6 +421,7 @@ static ERR_STRING_DATA SSL_str_reasons[]= 
{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"},