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Only allow ephemeral RSA keys in export ciphersuites.

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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>
This commit is contained in:
Dr. Stephen Henson
2014-10-23 17:09:57 +01:00
parent b15f876964
commit ce325c60c7
7 changed files with 38 additions and 57 deletions
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21
ssl/s3_srvr.c
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@@ -453,20 +453,11 @@ 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
@@ -480,7 +471,7 @@ int ssl3_accept(SSL *s)
* server certificate contains the server's
* public key for key exchange.
*/
if (s->s3->tmp.use_rsa_tmp
if (
/* PSK: send ServerKeyExchange if PSK identity
* hint if provided */
#ifndef OPENSSL_NO_PSK