diff mbox series

[Openvpn-devel,v8] Implement generating TLS 1.0 PRF using new OpenSSL 3.0 APIs

Message ID 20240209110629.15364-1-frank@lichtenheld.com
State Accepted
Headers show
Series [Openvpn-devel,v8] Implement generating TLS 1.0 PRF using new OpenSSL 3.0 APIs | expand

Commit Message

Frank Lichtenheld Feb. 9, 2024, 11:06 a.m. UTC 
From: Arne Schwabe <arne@rfc2549.org>

OpenSSL 3.0 introduced a new API for doing key derivation. So this leaves
us now with three different implementation for 1.0.2, 1.1.x and 3.x.

This was initially done to maybe still have a working TLS 1.0 PRF when
using OpenSSL 3.0 in FIPS but it gives the same error as with the older API.
But since moving to a new API is always good, we use the new API when using
OpenSSL 3.0. We also print the internal OpenSSL error message when
the KDF fails.

This also allows us now to compile an OpenSSL build that has been built with
OPENSSL_NO_MD5. Which is not yet common but might be in the future.

Change-Id: Ic74195a4ed340547c5e862dc2438f95be318c286
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/457
This mail reflects revision 8 of this Change.
Acked-by according to Gerrit (reflected above):
Frank Lichtenheld <frank@lichtenheld.com>

Typo fix in commit message added during submission.

Comments

Gert Doering Feb. 10, 2024, 9:12 a.m. UTC | #1 
Tested locally (FreeBSD / OpenSSL 3.0, OpenBSD / LibreSSL) and via GHA,
and things still work.

Your patch has been applied to the master branch.

commit 7435114d9a979611dfe5ab751c213900cc1773e8
Author: Arne Schwabe
Date:   Fri Feb 9 12:06:29 2024 +0100

     Implement generating TLS 1.0 PRF using new OpenSSL 3.0 APIs

     Signed-off-by: Arne Schwabe <arne@rfc2549.org>
     Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
     Message-Id: <20240209110629.15364-1-frank@lichtenheld.com>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28203.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering
diff mbox series

Patch

diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index e8ddf14..4fd5e6b 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -54,6 +54,7 @@ 
 #endif
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L
 #include <openssl/provider.h>
+#include <openssl/core_names.h>
 #endif
 
 #if defined(_WIN32) && defined(OPENSSL_NO_EC)
@@ -1329,8 +1330,57 @@ 
 {
     return CRYPTO_memcmp(a, b, size);
 }
+#if (OPENSSL_VERSION_NUMBER >= 0x30000000L) && !defined(LIBRESSL_VERSION_NUMBER)
+bool
+ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret,
+             int secret_len, uint8_t *output, int output_len)
+{
+    bool ret = true;
+    EVP_KDF_CTX *kctx = NULL;
 
-#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
+
+    EVP_KDF *kdf = EVP_KDF_fetch(NULL, "TLS1-PRF", NULL);
+    if (!kdf)
+    {
+        goto err;
+    }
+
+    kctx = EVP_KDF_CTX_new(kdf);
+
+    if (!kctx)
+    {
+        goto err;
+    }
+
+    OSSL_PARAM params[4];
+
+    /* The OpenSSL APIs require us to cast the const aways even though the
+     * strings are never changed and only read */
+    params[0] = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
+                                                 SN_md5_sha1, strlen(SN_md5_sha1));
+    params[1] = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET,
+                                                  (uint8_t *) secret, (size_t) secret_len);
+    params[2] = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
+                                                  (uint8_t *) seed, (size_t) seed_len);
+    params[3] = OSSL_PARAM_construct_end();
+
+    if (EVP_KDF_derive(kctx, output, output_len, params) <= 0)
+    {
+        crypto_msg(D_TLS_DEBUG_LOW, "Generating TLS 1.0 PRF using "
+                   "EVP_KDF_derive failed");
+        goto err;
+    }
+
+    goto out;
+
+err:
+    ret = false;
+out:
+    EVP_KDF_free(kdf);
+
+    return ret;
+}
+#elif (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
 bool
 ssl_tls1_PRF(const uint8_t *seed, int seed_len, const uint8_t *secret,
              int secret_len, uint8_t *output, int output_len)