Fixes for the following claims:
1) Certificate Message with no certs
OpenSSL implementation sends the Certificate message during SSL
handshake, however as per the specification, these have been omitted.
-- RFC 2712 --
CertificateRequest, and the ServerKeyExchange shown in Figure 1
will be omitted since authentication and the establishment of a
master secret will be done using the client's Kerberos credentials
for the TLS server. The client's certificate will be omitted for
the same reason.
-- RFC 2712 --
3) Pre-master secret Protocol version
The pre-master secret generated by OpenSSL does not have the correct
client version.
RFC 2712 says, if the Kerberos option is selected, the pre-master
secret structure is the same as that used in the RSA case.
TLS specification defines pre-master secret as:
struct {
ProtocolVersion client_version;
opaque random[46];
} PreMasterSecret;
where client_version is the latest protocol version supported by the
client
The pre-master secret generated by OpenSSL does not have the correct
client version. The implementation does not update the first 2 bytes
of random secret for Kerberos Cipher suites. At the server-end, the
client version from the pre-master secret is not validated.
PR: 1336
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index 0fb959e..4a34b44 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -1902,8 +1902,10 @@
n+=2;
}
- if (RAND_bytes(tmp_buf,sizeof tmp_buf) <= 0)
- goto err;
+ tmp_buf[0]=s->client_version>>8;
+ tmp_buf[1]=s->client_version&0xff;
+ if (RAND_bytes(&(tmp_buf[2]),sizeof tmp_buf-2) <= 0)
+ goto err;
/* 20010420 VRS. Tried it this way; failed.
** EVP_EncryptInit_ex(&ciph_ctx,enc, NULL,NULL);
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index db0f31e..85fa684 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -1,4 +1,4 @@
-/* ssl/s3_srvr.c */
+/* ssl/s3_srvr.c -*- mode:C; c-file-style: "eay" -*- */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
@@ -323,10 +323,11 @@
case SSL3_ST_SW_CERT_A:
case SSL3_ST_SW_CERT_B:
- /* Check if it is anon DH or anon ECDH */
- /* or normal PSK */
+ /* Check if it is anon DH or anon ECDH, */
+ /* normal PSK or KRB5 */
if (!(s->s3->tmp.new_cipher->algorithms & SSL_aNULL)
- && !(s->s3->tmp.new_cipher->algorithms & SSL_kPSK))
+ && !(s->s3->tmp.new_cipher->algorithms & SSL_kPSK)
+ && !(s->s3->tmp.new_cipher->algorithms & SSL_aKRB5))
{
ret=ssl3_send_server_certificate(s);
if (ret <= 0) goto end;
@@ -2061,6 +2062,25 @@
SSL_R_DATA_LENGTH_TOO_LONG);
goto err;
}
+ if (!((p[0] == (s->client_version>>8)) && (p[1] == (s->client_version & 0xff))))
+ {
+ /* The premaster secret must contain the same version number as the
+ * ClientHello to detect version rollback attacks (strangely, the
+ * protocol does not offer such protection for DH ciphersuites).
+ * However, buggy clients exist that send random bytes instead of
+ * the protocol version.
+ * If SSL_OP_TLS_ROLLBACK_BUG is set, tolerate such clients.
+ * (Perhaps we should have a separate BUG value for the Kerberos cipher)
+ */
+ if (!((s->options & SSL_OP_TLS_ROLLBACK_BUG) &&
+ (p[0] == (s->version>>8)) && (p[1] == (s->version & 0xff))))
+ {
+ SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
+ SSL_AD_DECODE_ERROR);
+ goto err;
+ }
+ }
+
EVP_CIPHER_CTX_cleanup(&ciph_ctx);
s->session->master_key_length=
