1 files changed, 127 insertions, 0 deletions
diff --git a/src/tls/tls_rsa.c b/src/tls/tls_rsa.c
new file mode 100644
index 0000000..67f2a2e
--- /dev/null
+++ b/src/tls/tls_rsa.c
@@ -0,0 +1,127 @@
+/*++
+/* NAME
+/*	tls_rsa
+/* SUMMARY
+/*	RSA support
+/* SYNOPSIS
+/*	#define TLS_INTERNAL
+/*	#include <tls.h>
+/*
+/*	RSA	*tls_tmp_rsa_cb(ssl, export, keylength)
+/*	SSL	*ssl; /* unused */
+/*	int	export;
+/*	int	keylength;
+/* DESCRIPTION
+/*	tls_tmp_rsa_cb() is a call-back routine for the
+/*	SSL_CTX_set_tmp_rsa_callback() function.
+/*
+/*	This implementation will generate only 512-bit ephemeral
+/*	RSA keys for export ciphersuites. It will log a warning in
+/*	all other usage contexts.
+/* LICENSE
+/* .ad
+/* .fi
+/*	This software is free. You can do with it whatever you want.
+/*	The original author kindly requests that you acknowledge
+/*	the use of his software.
+/* AUTHOR(S)
+/*	Originally written by:
+/*	Lutz Jaenicke
+/*	BTU Cottbus
+/*	Allgemeine Elektrotechnik
+/*	Universitaetsplatz 3-4
+/*	D-03044 Cottbus, Germany
+/*
+/*	Updated by:
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Viktor Dukhovni.
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <msg.h>
+
+#ifdef USE_TLS
+
+/* TLS library. */
+
+#define TLS_INTERNAL
+#include <tls.h>
+#include <openssl/rsa.h>
+
+ /*
+  * 2015-12-05: Ephemeral RSA removed from OpenSSL 1.1.0-dev
+  */
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
+/* tls_tmp_rsa_cb - call-back to generate ephemeral RSA key */
+
+RSA    *tls_tmp_rsa_cb(SSL *unused_ssl, int export, int keylength)
+{
+    static RSA *rsa_tmp;
+
+    /*
+     * We generate ephemeral RSA keys only for export ciphersuites.  In all
+     * other contexts use of ephemeral RSA keys violates the SSL/TLS
+     * protocol, and only takes place when applications ask for trouble and
+     * set the SSL_OP_EPHEMERAL_RSA option.  Postfix should never do that.
+     */
+    if (!export || keylength != 512) {
+	msg_warn("%sexport %d-bit ephemeral RSA key requested",
+		 export ? "" : "non-", keylength);
+	return 0;
+    }
+    if (rsa_tmp == 0) {
+	BIGNUM *e = BN_new();
+
+	if (e != 0 && BN_set_word(e, RSA_F4) && (rsa_tmp = RSA_new()) != 0)
+	    if (!RSA_generate_key_ex(rsa_tmp, keylength, e, 0)) {
+		RSA_free(rsa_tmp);
+		rsa_tmp = 0;
+	    }
+	if (e)
+	    BN_free(e);
+    }
+    return (rsa_tmp);
+}
+
+#endif					/* OPENSSL_VERSION_NUMBER */
+
+#ifdef TEST
+
+#include <msg_vstream.h>
+
+int     main(int unused_argc, char *const argv[])
+{
+    int     ok = 0;
+
+    /*
+     * 2015-12-05: Ephemeral RSA removed from OpenSSL 1.1.0-dev
+     */
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+    RSA    *rsa;
+
+    msg_vstream_init(argv[0], VSTREAM_ERR);
+
+    /* Export at 512-bits should work */
+    rsa = tls_tmp_rsa_cb(0, 1, 512);
+    ok = rsa != 0 && RSA_size(rsa) == 512 / 8;
+    ok = ok && PEM_write_RSAPrivateKey(stdout, rsa, 0, 0, 0, 0, 0);
+    tls_print_errors();
+
+    /* Non-export or unexpected bit length should fail */
+    ok = ok && tls_tmp_rsa_cb(0, 0, 512) == 0;
+    ok = ok && tls_tmp_rsa_cb(0, 1, 1024) == 0;
+#endif
+
+    return ok ? 0 : 1;
+}
+
+#endif
+
+#endif