Fix OpenSSL 3.0.x related issues. (#10291)

* Drop obsolete initialization calls.
* Use decoder API for DH parameters.
* Enable auto DH parameters if not explicitly used, which should be the
  preferred configuration going forward.

2 files changed, 42 insertions, 7 deletions

diff --git a/redis.conf b/redis.conf
index 55ed8a13e..d9644a776 100644
--- a/redis.conf
+++ b/redis.conf
@@ -213,7 +213,9 @@ tcp-keepalive 300
 #
 # tls-client-key-file-pass secret
 
-# Configure a DH parameters file to enable Diffie-Hellman (DH) key exchange:
+# Configure a DH parameters file to enable Diffie-Hellman (DH) key exchange,
+# required by older versions of OpenSSL (<3.0). Newer versions do not require
+# this configuration and recommend against it.
 #
 # tls-dh-params-file redis.dh
 
diff --git a/src/tls.c b/src/tls.c
index 2fcf57b8f..c6449b2a7 100644
--- a/src/tls.c
+++ b/src/tls.c
@@ -39,6 +39,9 @@
 #include <openssl/err.h>
 #include <openssl/rand.h>
 #include <openssl/pem.h>
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+#include <openssl/decoder.h>
+#endif
 
 #define REDIS_TLS_PROTO_TLSv1       (1<<0)
 #define REDIS_TLS_PROTO_TLSv1_1     (1<<1)
@@ -146,14 +149,13 @@ void tlsInit(void) {
      */
     #if OPENSSL_VERSION_NUMBER < 0x10100000L
     OPENSSL_config(NULL);
+    SSL_load_error_strings();
+    SSL_library_init();
     #elif OPENSSL_VERSION_NUMBER < 0x10101000L
     OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);
     #else
     OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG|OPENSSL_INIT_ATFORK, NULL);
     #endif
-    ERR_load_crypto_strings();
-    SSL_load_error_strings();
-    SSL_library_init();
 
 #ifdef USE_CRYPTO_LOCKS
     initCryptoLocks();
@@ -323,20 +325,46 @@ int tlsConfigure(redisTLSContextConfig *ctx_config) {
     if (ctx_config->prefer_server_ciphers)
         SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
 
-#if defined(SSL_CTX_set_ecdh_auto)
+#if ((OPENSSL_VERSION_NUMBER < 0x30000000L) && defined(SSL_CTX_set_ecdh_auto))
     SSL_CTX_set_ecdh_auto(ctx, 1);
 #endif
     SSL_CTX_set_options(ctx, SSL_OP_SINGLE_DH_USE);
 
     if (ctx_config->dh_params_file) {
         FILE *dhfile = fopen(ctx_config->dh_params_file, "r");
-        DH *dh = NULL;
         if (!dhfile) {
             serverLog(LL_WARNING, "Failed to load %s: %s", ctx_config->dh_params_file, strerror(errno));
             goto error;
         }
 
-        dh = PEM_read_DHparams(dhfile, NULL, NULL, NULL);
+#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)
+        EVP_PKEY *pkey = NULL;
+        OSSL_DECODER_CTX *dctx = OSSL_DECODER_CTX_new_for_pkey(
+                &pkey, "PEM", NULL, "DH", OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS, NULL, NULL);
+        if (!dctx) {
+            serverLog(LL_WARNING, "No decoder for DH params.");
+            fclose(dhfile);
+            goto error;
+        }
+        if (!OSSL_DECODER_from_fp(dctx, dhfile)) {
+            serverLog(LL_WARNING, "%s: failed to read DH params.", ctx_config->dh_params_file);
+            OSSL_DECODER_CTX_free(dctx);
+            fclose(dhfile);
+            goto error;
+        }
+
+        OSSL_DECODER_CTX_free(dctx);
+        fclose(dhfile);
+
+        if (SSL_CTX_set0_tmp_dh_pkey(ctx, pkey) <= 0) {
+            ERR_error_string_n(ERR_get_error(), errbuf, sizeof(errbuf));
+            serverLog(LL_WARNING, "Failed to load DH params file: %s: %s", ctx_config->dh_params_file, errbuf);
+            EVP_PKEY_free(pkey);
+            goto error;
+        }
+        /* Not freeing pkey, it is owned by OpenSSL now */
+#else
+        DH *dh = PEM_read_DHparams(dhfile, NULL, NULL, NULL);
         fclose(dhfile);
         if (!dh) {
             serverLog(LL_WARNING, "%s: failed to read DH params.", ctx_config->dh_params_file);
@@ -351,6 +379,11 @@ int tlsConfigure(redisTLSContextConfig *ctx_config) {
         }
 
         DH_free(dh);
+#endif
+    } else {
+#if (OPENSSL_VERSION_NUMBER >= 0x30000000L)
+        SSL_CTX_set_dh_auto(ctx, 1);
+#endif
     }
 
     /* If a client-side certificate is configured, create an explicit client context */