[Openvpn-devel] [PATCH 8/8] [OSSL 3.0] Use EVP_PKEY_get_group_name to query group name

[Arne Schwabe]

EC_Key methods are deprecated in OpenSSL 3.0. Use
EVP_PKEY_get_group_name instead to query the EC group name from an
EVP_PKEY and add a compatibility function for older OpenSSL versions.
---
 src/openvpn/openssl_compat.h | 32 ++++++++++++++++++++++++++++++++
 src/openvpn/ssl_openssl.c    | 14 ++++++++------
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/openvpn/openssl_compat.h b/src/openvpn/openssl_compat.h
index ce8e2b360..933a71848 100644
--- a/src/openvpn/openssl_compat.h
+++ b/src/openvpn/openssl_compat.h
@@ -46,6 +46,38 @@
 #include <openssl/ssl.h>
 #include <openssl/x509.h>
 
+/* Functionality missing in 1.1.1 */
+#if OPENSSL_VERSION_NUMBER < 0x30000000L
+
+/* Note that this is not a perfect emulation of the new function but
+ * is good enough for our case of printing certificate details during
+ * handshake */
+static inline
+int EVP_PKEY_get_group_name(EVP_PKEY *pkey, char *gname, size_t gname_sz,
+                            size_t *gname_len)
+                            {
+    if ((EVP_PKEY_get0_EC_KEY(pkey) == NULL ||
+        EVP_PKEY_get0_EC_KEY(pkey) != NULL))
+    {
+        return 0;
+    }
+    const EC_KEY* ec = EVP_PKEY_get0_EC_KEY(pkey);
+    const EC_GROUP* group = EC_KEY_get0_group(ec);
+
+    int nid = EC_GROUP_get_curve_name(group);
+
+    if (nid != 0)
+    {
+        return 0;
+    }
+    const char *curve = OBJ_nid2sn(nid);
+
+    strncpy(gname, curve, gname_sz);
+    *gname_len = min_int(strlen(curve), gname_sz);
+    return 1;
+}
+#endif
+
 /* Functionality missing in 1.1.0 */
 #if OPENSSL_VERSION_NUMBER < 0x10101000L && !defined(ENABLE_CRYPTO_WOLFSSL)
 #define SSL_CTX_set1_groups SSL_CTX_set1_curves
diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index 68cdb880c..dc0ae20a7 100644
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -2049,13 +2049,15 @@ print_cert_details(X509 *cert, char *buf, size_t buflen)
     int typeid = EVP_PKEY_id(pkey);
 
 #ifndef OPENSSL_NO_EC
-    if (typeid == EVP_PKEY_EC && EVP_PKEY_get0_EC_KEY(pkey) != NULL)
+    char groupname[256];
+    if (typeid == EVP_PKEY_EC)
     {
-        const EC_KEY *ec = EVP_PKEY_get0_EC_KEY(pkey);
-        const EC_GROUP *group = EC_KEY_get0_group(ec);
-
-        int nid = EC_GROUP_get_curve_name(group);
-        if (nid == 0 || (curve = OBJ_nid2sn(nid)) == NULL)
+        size_t len;
+        if(EVP_PKEY_get_group_name(pkey, groupname, sizeof(groupname), &len))
+        {
+           curve = groupname;
+        }
+        else
         {
             curve = "(error getting curve name)";
         }
-- 
2.33.0



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