Don't prefer ECDHE-ECDSA ciphers when the client appears to be Safari on OS X.

OS X 10.8..10.8.3 has broken support for ECDHE-ECDSA ciphers.

doc/ssl/SSL_CTX_set_options.pod

@@ -88,9 +88,10 @@ As of OpenSSL 0.9.8q and 1.0.0c, this option has no effect.
 
 ...
 
-=item SSL_OP_MSIE_SSLV2_RSA_PADDING
+=item SSL_OP_SAFARI_ECDHE_ECDSA_BUG
 
-As of OpenSSL 0.9.7h and 0.9.8a, this option has no effect.
+Don't prefer ECDHE-ECDSA ciphers when the client appears to be Safari on OS X.
+OS X 10.8..10.8.3 has broken support for ECDHE-ECDSA ciphers.
 
 =item SSL_OP_SSLEAY_080_CLIENT_DH_BUG
 

ssl/s3_lib.c

@@ -3089,7 +3089,10 @@ void ssl3_clear(SSL *s)
 		s->s3->tlsext_custom_types = NULL;
 		}
 	s->s3->tlsext_custom_types_count = 0;	
-#endif
+#ifndef OPENSSL_NO_EC
+	s->s3->is_probably_safari = 0;
+#endif /* OPENSSL_NO_EC */
+#endif /* OPENSSL_NO_TLSEXT */
 
 	rp = s->s3->rbuf.buf;
 	wp = s->s3->wbuf.buf;
@@ -4170,8 +4173,15 @@ SSL_CIPHER *ssl3_choose_cipher(SSL *s, STACK_OF(SSL_CIPHER) *clnt,
 		ii=sk_SSL_CIPHER_find(allow,c);
 		if (ii >= 0)
 			{
-			ret=sk_SSL_CIPHER_value(allow,ii);
-			break;
+			if ((alg_k & SSL_kEECDH) && (alg_a & SSL_aECDSA) && s->s3->is_probably_safari)
+				{
+				if (!ret) ret=sk_SSL_CIPHER_value(allow,ii);
+				}
+			else
+				{
+				ret=sk_SSL_CIPHER_value(allow,ii);
+				break;
+				}
 			}
 		}
 	return(ret);

ssl/ssl.h

@@ -615,7 +615,7 @@ struct ssl_session_st
 #define SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG		0x00000008L
 #define SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG		0x00000010L
 #define SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER		0x00000020L
-#define SSL_OP_MSIE_SSLV2_RSA_PADDING			0x00000040L /* no effect since 0.9.7h and 0.9.8b */
+#define SSL_OP_SAFARI_ECDHE_ECDSA_BUG			0x00000040L
 #define SSL_OP_SSLEAY_080_CLIENT_DH_BUG			0x00000080L
 #define SSL_OP_TLS_D5_BUG				0x00000100L
 #define SSL_OP_TLS_BLOCK_PADDING_BUG			0x00000200L

ssl/ssl3.h

@@ -596,6 +596,14 @@ typedef struct ssl3_state_st
 	 * processed. */
 	unsigned char *alpn_selected;
 	unsigned alpn_selected_len;
+
+#ifndef OPENSSL_NO_EC
+	/* This is set to true if we believe that this is a version of Safari
+	 * running on OS X 10.6 or newer. We wish to know this because Safari
+	 * on 10.8 .. 10.8.3 has broken ECDHE-ECDSA support. */
+	char is_probably_safari;
+#endif	/* OPENSSL_NO_EC */
+
 #endif	/* OPENSSL_NO_TLSEXT */
 	} SSL3_STATE;
 

ssl/t1_lib.c

@@ -1899,6 +1899,89 @@ parse_error:
 	return -1;
 	}
 
+#ifndef OPENSSL_NO_EC
+/* ssl_check_for_safari attempts to fingerprint Safari using OS X
+ * SecureTransport using the TLS extension block in |d|, of length |n|.
+ * Safari, since 10.6, sends exactly these extensions, in this order:
+ *   SNI,
+ *   elliptic_curves
+ *   ec_point_formats
+ *
+ * We wish to fingerprint Safari because they broke ECDHE-ECDSA support in 10.8,
+ * but they advertise support. So enabling ECDHE-ECDSA ciphers breaks them.
+ * Sadly we cannot differentiate 10.6, 10.7 and 10.8.4 (which work), from
+ * 10.8..10.8.3 (which don't work).
+ */
+static void ssl_check_for_safari(SSL *s, const unsigned char *data, const unsigned char *d, int n) {
+	unsigned short type, size;
+	static const unsigned char kSafariExtensionsBlock[] = {
+		0x00, 0x0a,  /* elliptic_curves extension */
+		0x00, 0x08,  /* 8 bytes */
+		0x00, 0x06,  /* 6 bytes of curve ids */
+		0x00, 0x17,  /* P-256 */
+		0x00, 0x18,  /* P-384 */
+		0x00, 0x19,  /* P-521 */
+
+		0x00, 0x0b,  /* ec_point_formats */
+		0x00, 0x02,  /* 2 bytes */
+		0x01,        /* 1 point format */
+		0x00,        /* uncompressed */
+	};
+
+	/* The following is only present in TLS 1.2 */
+	static const unsigned char kSafariTLS12ExtensionsBlock[] = {
+		0x00, 0x0d,  /* signature_algorithms */
+		0x00, 0x0c,  /* 12 bytes */
+		0x00, 0x0a,  /* 10 bytes */
+		0x05, 0x01,  /* SHA-384/RSA */
+		0x04, 0x01,  /* SHA-256/RSA */
+		0x02, 0x01,  /* SHA-1/RSA */
+		0x04, 0x03,  /* SHA-256/ECDSA */
+		0x02, 0x03,  /* SHA-1/ECDSA */
+	};
+
+	if (data >= (d+n-2))
+		return;
+	data += 2;
+
+	if (data > (d+n-4))
+		return;
+	n2s(data,type);
+	n2s(data,size);
+
+	if (type != TLSEXT_TYPE_server_name)
+		return;
+
+	if (data+size > d+n)
+		return;
+	data += size;
+
+	if (TLS1_get_version(s) >= TLS1_2_VERSION)
+		{
+		const size_t len1 = sizeof(kSafariExtensionsBlock);
+		const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);
+
+		if (data + len1 + len2 != d+n)
+			return;
+		if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
+			return;
+		if (memcmp(data + len1, kSafariTLS12ExtensionsBlock, len2) != 0)
+			return;
+		}
+	else
+		{
+		const size_t len = sizeof(kSafariExtensionsBlock);
+
+		if (data + len != d+n)
+			return;
+		if (memcmp(data, kSafariExtensionsBlock, len) != 0)
+			return;
+		}
+
+	s->s3->is_probably_safari = 1;
+}
+#endif	/* OPENSSL_NO_EC */
+
 static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d, int n, int *al) 
 	{	
 	unsigned short type;
@@ -1932,6 +2015,12 @@ static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char
 	s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
 	                       SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
 #endif
+
+#ifndef OPENSSL_NO_EC
+	if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG)
+		ssl_check_for_safari(s, data, d, n);
+#endif	/* OPENSSL_NO_EC */
+
 	/* Clear any signature algorithms extension received */
 	if (s->cert->peer_sigalgs)
 		{