1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
From 37580f43b5a39f5f4e920d17273fab9713d3a744 Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Thu, 23 Oct 2014 17:09:57 +0100
Subject: [PATCH] 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@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 4b4c1fcc88aec8c9e001b0a0077d3cd4de1ed0e6)
Conflicts:
doc/ssl/SSL_CTX_set_options.pod
Conflicts:
Changes in the "CHANGES" file have been removed from this pacth since
it fails to apply.
Upstream-Status: Backport
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
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/doc/ssl/SSL_CTX_set_options.pod b/doc/ssl/SSL_CTX_set_options.pod
index 6e6b5e6..e80a72c 100644
--- a/doc/ssl/SSL_CTX_set_options.pod
+++ b/doc/ssl/SSL_CTX_set_options.pod
@@ -158,15 +158,7 @@ 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 e40701e..da4c21e 100644
--- a/ssl/d1_srvr.c
+++ b/ssl/d1_srvr.c
@@ -454,24 +454,15 @@ 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 43ffc77..023c679 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -1537,6 +1537,13 @@ 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 ac2cc3d..d883f86 100644
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -447,20 +447,11 @@ 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
@@ -474,7 +465,7 @@ 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 a6a1c77..2ba5923 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -596,9 +596,8 @@ 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
--
1.9.1
|
