Commit 800e1cd9 authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

Additional workaround for PR#2771 

If OPENSSL_MAX_TLS1_2_CIPHER_LENGTH is set then limit the size of client
ciphersuites to this value. A value of 50 should be sufficient.

Document workarounds in CHANGES.
parent 293706e7

CHANGES

+13 −0
Original line number Diff line number Diff line
@@ -291,6 +291,19 @@ 
  

 Changes between 1.0.1 and 1.0.1a [xx XXX xxxx]



  *) Workarounds for some broken servers that "hang" if a client hello

     record length exceeds 255 bytes:

 

     1. Do not use record version number > TLS 1.0 in initial client

        hello: some (but not all) hanging servers will now work.

     2. If we set OPENSSL_MAX_TLS1_2_CIPHER_LENGTH this will truncate

        the number of ciphers sent in the client hello. This should be

        set to an even number, such as 50, for example by passing:

        -DOPENSSL_MAX_TLS1_2_CIPHER_LENGTH=50 to config or Configure.

        Most broken servers should now work.

     3. If all else fails setting OPENSSL_NO_TLS1_2_CLIENT will disable

        TLS 1.2 client support entirely.



  *) Fix SEGV in Vector Permutation AES module observed in OpenSSH.

     [Andy Polyakov]

ssl/s23_clnt.c

+9 −0
Original line number Diff line number Diff line
@@ -467,6 +467,15 @@ static int ssl23_client_hello(SSL *s) 
				SSLerr(SSL_F_SSL23_CLIENT_HELLO,SSL_R_NO_CIPHERS_AVAILABLE);

				return -1;

				}

#ifdef OPENSSL_MAX_TLS1_2_CIPHER_LENGTH

			/* Some servers hang if client hello > 256 bytes

			 * as hack workaround chop number of supported ciphers

			 * to keep it well below this if we use TLS v1.2

			 */

			if (TLS1_get_version(s) >= TLS1_2_VERSION

				&& i > OPENSSL_MAX_TLS1_2_CIPHER_LENGTH)

				i = OPENSSL_MAX_TLS1_2_CIPHER_LENGTH & ~1;

#endif

			s2n(i,p);

			p+=i;

ssl/s3_clnt.c

+9 −0
Original line number Diff line number Diff line
@@ -755,6 +755,15 @@ int ssl3_client_hello(SSL *s) 
			SSLerr(SSL_F_SSL3_CLIENT_HELLO,SSL_R_NO_CIPHERS_AVAILABLE);

			goto err;

			}

#ifdef OPENSSL_MAX_TLS1_2_CIPHER_LENGTH

			/* Some servers hang if client hello > 256 bytes

			 * as hack workaround chop number of supported ciphers

			 * to keep it well below this if we use TLS v1.2

			 */

			if (TLS1_get_version(s) >= TLS1_2_VERSION

				&& i > OPENSSL_MAX_TLS1_2_CIPHER_LENGTH)

				i = OPENSSL_MAX_TLS1_2_CIPHER_LENGTH & ~1;

#endif

		s2n(i,p);

		p+=i;