[openssl-commits] [openssl] OpenSSL source code branch OpenSSL_1_0_0-stable updated. OpenSSL_1_0_0o-58-g08a8877
Dr. Stephen Henson
steve at openssl.org
Tue Jan 6 13:46:44 UTC 2015
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- Log -----------------------------------------------------------------
commit 08a88774bd8463bedf7fe440a165d3d98b702361
Author: Dr. Stephen Henson <steve at openssl.org>
Date: Thu Oct 23 17:09:57 2014 +0100
Only allow ephemeral RSA keys in export ciphersuites.
OpenSSL clients would tolerate temporary RSA keys in non-export
ciphersuites. It also had an option SSL_OP_EPHEMERAL_RSA which
enabled this server side. Remove both options as they are a
protocol violation.
Thanks to Karthikeyan Bhargavan for reporting this issue.
(CVE-2015-0204)
Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Tim Hudson <tjh at openssl.org>
(cherry picked from commit 4b4c1fcc88aec8c9e001b0a0077d3cd4de1ed0e6)
Conflicts:
CHANGES
doc/ssl/SSL_CTX_set_options.pod
-----------------------------------------------------------------------
Summary of changes:
CHANGES | 8 ++++++++
doc/ssl/SSL_CTX_set_options.pod | 10 +---------
doc/ssl/SSL_CTX_set_tmp_rsa_callback.pod | 23 ++++++++---------------
ssl/d1_srvr.c | 21 ++++++---------------
ssl/s3_clnt.c | 7 +++++++
ssl/s3_srvr.c | 21 ++++++---------------
ssl/ssl.h | 5 ++---
7 files changed, 38 insertions(+), 57 deletions(-)
diff --git a/CHANGES b/CHANGES
index 519869b..0fbac88 100644
--- a/CHANGES
+++ b/CHANGES
@@ -11,6 +11,14 @@
(CVE-2014-3572)
[Steve Henson]
+ *) Remove non-export ephemeral RSA code on client and server. This code
+ violated the TLS standard by allowing the use of temporary RSA keys in
+ non-export ciphersuites and could be used by a server to effectively
+ downgrade the RSA key length used to a value smaller than the server
+ certificate. Thanks for Karthikeyan Bhargavan for reporting this issue.
+ (CVE-2015-0204)
+ [Steve Henson]
+
*) Fix various certificate fingerprint issues.
By using non-DER or invalid encodings outside the signed portion of a
diff --git a/doc/ssl/SSL_CTX_set_options.pod b/doc/ssl/SSL_CTX_set_options.pod
index 36bfa59..0de9786 100644
--- a/doc/ssl/SSL_CTX_set_options.pod
+++ b/doc/ssl/SSL_CTX_set_options.pod
@@ -152,15 +152,7 @@ temporary/ephemeral DH parameters are used.
=item SSL_OP_EPHEMERAL_RSA
-Always use ephemeral (temporary) RSA key when doing RSA operations
-(see L<SSL_CTX_set_tmp_rsa_callback(3)|SSL_CTX_set_tmp_rsa_callback(3)>).
-According to the specifications this is only done, when a RSA key
-can only be used for signature operations (namely under export ciphers
-with restricted RSA keylength). By setting this option, ephemeral
-RSA keys are always used. This option breaks compatibility with the
-SSL/TLS specifications and may lead to interoperability problems with
-clients and should therefore never be used. Ciphers with EDH (ephemeral
-Diffie-Hellman) key exchange should be used instead.
+This option is no longer implemented and is treated as no op.
=item SSL_OP_CIPHER_SERVER_PREFERENCE
diff --git a/doc/ssl/SSL_CTX_set_tmp_rsa_callback.pod b/doc/ssl/SSL_CTX_set_tmp_rsa_callback.pod
index 534643c..8794eb7 100644
--- a/doc/ssl/SSL_CTX_set_tmp_rsa_callback.pod
+++ b/doc/ssl/SSL_CTX_set_tmp_rsa_callback.pod
@@ -74,21 +74,14 @@ exchange and use EDH (Ephemeral Diffie-Hellman) key exchange instead
in order to achieve forward secrecy (see
L<SSL_CTX_set_tmp_dh_callback(3)|SSL_CTX_set_tmp_dh_callback(3)>).
-On OpenSSL servers ephemeral RSA key exchange is therefore disabled by default
-and must be explicitly enabled using the SSL_OP_EPHEMERAL_RSA option of
-L<SSL_CTX_set_options(3)|SSL_CTX_set_options(3)>, violating the TLS/SSL
-standard. When ephemeral RSA key exchange is required for export ciphers,
-it will automatically be used without this option!
-
-An application may either directly specify the key or can supply the key via
-a callback function. The callback approach has the advantage, that the
-callback may generate the key only in case it is actually needed. As the
-generation of a RSA key is however costly, it will lead to a significant
-delay in the handshake procedure. Another advantage of the callback function
-is that it can supply keys of different size (e.g. for SSL_OP_EPHEMERAL_RSA
-usage) while the explicit setting of the key is only useful for key size of
-512 bits to satisfy the export restricted ciphers and does give away key length
-if a longer key would be allowed.
+An application may either directly specify the key or can supply the key via a
+callback function. The callback approach has the advantage, that the callback
+may generate the key only in case it is actually needed. As the generation of a
+RSA key is however costly, it will lead to a significant delay in the handshake
+procedure. Another advantage of the callback function is that it can supply
+keys of different size while the explicit setting of the key is only useful for
+key size of 512 bits to satisfy the export restricted ciphers and does give
+away key length if a longer key would be allowed.
The B<tmp_rsa_callback> is called with the B<keylength> needed and
the B<is_export> information. The B<is_export> flag is set, when the
diff --git a/ssl/d1_srvr.c b/ssl/d1_srvr.c
index f52c735..08b1ab2 100644
--- a/ssl/d1_srvr.c
+++ b/ssl/d1_srvr.c
@@ -373,24 +373,15 @@ int dtls1_accept(SSL *s)
case SSL3_ST_SW_KEY_EXCH_B:
alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
- /* clear this, it may get reset by
- * send_server_key_exchange */
- if ((s->options & SSL_OP_EPHEMERAL_RSA)
-#ifndef OPENSSL_NO_KRB5
- && !(alg_k & SSL_kKRB5)
-#endif /* OPENSSL_NO_KRB5 */
- )
- /* option SSL_OP_EPHEMERAL_RSA sends temporary RSA key
- * even when forbidden by protocol specs
- * (handshake may fail as clients are not required to
- * be able to handle this) */
- s->s3->tmp.use_rsa_tmp=1;
- else
- s->s3->tmp.use_rsa_tmp=0;
+ /*
+ * clear this, it may get reset by
+ * send_server_key_exchange
+ */
+ s->s3->tmp.use_rsa_tmp=0;
/* only send if a DH key exchange or
* RSA but we have a sign only certificate */
- if (s->s3->tmp.use_rsa_tmp
+ if (0
/* PSK: send ServerKeyExchange if PSK identity
* hint if provided */
#ifndef OPENSSL_NO_PSK
diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index f2e9e54..98617c2 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -1328,6 +1328,13 @@ int ssl3_get_key_exchange(SSL *s)
#ifndef OPENSSL_NO_RSA
if (alg_k & SSL_kRSA)
{
+ /* Temporary RSA keys only allowed in export ciphersuites */
+ if (!SSL_C_IS_EXPORT(s->s3->tmp.new_cipher))
+ {
+ al=SSL_AD_UNEXPECTED_MESSAGE;
+ SSLerr(SSL_F_SSL3_GET_SERVER_CERTIFICATE,SSL_R_UNEXPECTED_MESSAGE);
+ goto f_err;
+ }
if ((rsa=RSA_new()) == NULL)
{
SSLerr(SSL_F_SSL3_GET_KEY_EXCHANGE,ERR_R_MALLOC_FAILURE);
diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index 20c6fa0..0dce557 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -380,20 +380,11 @@ int ssl3_accept(SSL *s)
case SSL3_ST_SW_KEY_EXCH_B:
alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
- /* clear this, it may get reset by
- * send_server_key_exchange */
- if ((s->options & SSL_OP_EPHEMERAL_RSA)
-#ifndef OPENSSL_NO_KRB5
- && !(alg_k & SSL_kKRB5)
-#endif /* OPENSSL_NO_KRB5 */
- )
- /* option SSL_OP_EPHEMERAL_RSA sends temporary RSA key
- * even when forbidden by protocol specs
- * (handshake may fail as clients are not required to
- * be able to handle this) */
- s->s3->tmp.use_rsa_tmp=1;
- else
- s->s3->tmp.use_rsa_tmp=0;
+ /*
+ * clear this, it may get reset by
+ * send_server_key_exchange
+ */
+ s->s3->tmp.use_rsa_tmp=0;
/* only send if a DH key exchange, fortezza or
@@ -407,7 +398,7 @@ int ssl3_accept(SSL *s)
* server certificate contains the server's
* public key for key exchange.
*/
- if (s->s3->tmp.use_rsa_tmp
+ if (0
/* PSK: send ServerKeyExchange if PSK identity
* hint if provided */
#ifndef OPENSSL_NO_PSK
diff --git a/ssl/ssl.h b/ssl/ssl.h
index 4f4fc82..a143bff 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -560,9 +560,8 @@ typedef struct ssl_session_st
#define SSL_OP_SINGLE_ECDH_USE 0x00080000L
/* If set, always create a new key when using tmp_dh parameters */
#define SSL_OP_SINGLE_DH_USE 0x00100000L
-/* Set to always use the tmp_rsa key when doing RSA operations,
- * even when this violates protocol specs */
-#define SSL_OP_EPHEMERAL_RSA 0x00200000L
+/* Does nothing: retained for compatibiity */
+#define SSL_OP_EPHEMERAL_RSA 0x0
/* Set on servers to choose the cipher according to the server's
* preferences */
#define SSL_OP_CIPHER_SERVER_PREFERENCE 0x00400000L
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