Fix CCM tag length setting for old OpenSSL versions

While OpenSSL 1.1 allows unconditionally setting the CCM tag length
even for decryption, some older versions apparently do not. As such,
we do need to treat CCM and OCB separately after all.

Author: nikic

ext/openssl/openssl.c

@@ -6483,8 +6483,9 @@ PHP_FUNCTION(openssl_digest)
 /* Cipher mode info */
 struct php_openssl_cipher_mode {
 	zend_bool is_aead;
-	zend_bool should_set_tag_length;
 	zend_bool is_single_run_aead;
+	zend_bool set_tag_length_always;
+	zend_bool set_tag_length_when_encrypting;
 	int aead_get_tag_flag;
 	int aead_set_tag_flag;
 	int aead_ivlen_flag;
@@ -6493,14 +6494,17 @@ struct php_openssl_cipher_mode {
 static void php_openssl_load_cipher_mode(struct php_openssl_cipher_mode *mode, const EVP_CIPHER *cipher_type) /* {{{ */
 {
 	int cipher_mode = EVP_CIPHER_mode(cipher_type);
+	memset(mode, 0, sizeof(struct php_openssl_cipher_mode));
 	switch (cipher_mode) {
 #if PHP_OPENSSL_API_VERSION >= 0x10100
 		case EVP_CIPH_GCM_MODE:
 		case EVP_CIPH_OCB_MODE:
 		case EVP_CIPH_CCM_MODE:
 			mode->is_aead = 1;
-			mode->should_set_tag_length =
-				cipher_mode == EVP_CIPH_CCM_MODE || cipher_mode == EVP_CIPH_OCB_MODE;
+			/* For OCB mode, explicitly set the tag length even when decrypting,
+			 * see https://github.com/openssl/openssl/issues/8331. */
+			mode->set_tag_length_always = cipher_mode == EVP_CIPH_OCB_MODE;
+			mode->set_tag_length_when_encrypting = cipher_mode == EVP_CIPH_CCM_MODE;
 			mode->is_single_run_aead = cipher_mode == EVP_CIPH_CCM_MODE;
 			mode->aead_get_tag_flag = EVP_CTRL_AEAD_GET_TAG;
 			mode->aead_set_tag_flag = EVP_CTRL_AEAD_SET_TAG;
@@ -6510,8 +6514,6 @@ static void php_openssl_load_cipher_mode(struct php_openssl_cipher_mode *mode, c
 # ifdef EVP_CIPH_GCM_MODE
 		case EVP_CIPH_GCM_MODE:
 			mode->is_aead = 1;
-			mode->should_set_tag_length = 0;
-			mode->is_single_run_aead = 0;
 			mode->aead_get_tag_flag = EVP_CTRL_GCM_GET_TAG;
 			mode->aead_set_tag_flag = EVP_CTRL_GCM_SET_TAG;
 			mode->aead_ivlen_flag = EVP_CTRL_GCM_SET_IVLEN;
@@ -6520,16 +6522,14 @@ static void php_openssl_load_cipher_mode(struct php_openssl_cipher_mode *mode, c
 # ifdef EVP_CIPH_CCM_MODE
 		case EVP_CIPH_CCM_MODE:
 			mode->is_aead = 1;
-			mode->should_set_tag_length = 1;
 			mode->is_single_run_aead = 1;
+			mode->set_tag_length_when_encrypting = 1;
 			mode->aead_get_tag_flag = EVP_CTRL_CCM_GET_TAG;
 			mode->aead_set_tag_flag = EVP_CTRL_CCM_SET_TAG;
 			mode->aead_ivlen_flag = EVP_CTRL_CCM_SET_IVLEN;
 			break;
 # endif
 #endif
-		default:
-			memset(mode, 0, sizeof(struct php_openssl_cipher_mode));
 	}
 }
 /* }}} */
@@ -6611,9 +6611,7 @@ static int php_openssl_cipher_init(const EVP_CIPHER *cipher_type,
 	if (php_openssl_validate_iv(piv, piv_len, max_iv_len, free_iv, cipher_ctx, mode) == FAILURE) {
 		return FAILURE;
 	}
-	if (mode->should_set_tag_length) {
-		/* Explicitly set the tag length even when decrypting,
-		 * see https://github.com/openssl/openssl/issues/8331. */
+	if (mode->set_tag_length_always || (enc && mode->set_tag_length_when_encrypting)) {
 		if (!EVP_CIPHER_CTX_ctrl(cipher_ctx, mode->aead_set_tag_flag, tag_len, NULL)) {
 			php_error_docref(NULL, E_WARNING, "Setting tag length for AEAD cipher failed");
 			return FAILURE;