MDEV-14101 Provide an option to select TLS protocol version

Server and command line tools now support option --tls_version to specify the
TLS version between client and server. Valid values are TLSv1.0, TLSv1.1, TLSv1.2, TLSv1.3
or a combination of them. E.g.

--tls_version=TLSv1.3
--tls_version=TLSv1.2,TLSv1.3

In case there is a gap between versions, the lowest version will be used:
--tls_version=TLSv1.1,TLSv1.3 -> Only TLSv1.1 will be available.

If the used TLS library doesn't support the specified TLS version, it will use
the default configuration.

Limitations:

SSLv3 is not supported. The default configuration doesn't support TLSv1.0 anymore.
TLSv1.3 protocol currently is only supported by OpenSSL 1.1.0 (client and server) and
GnuTLS 3.6.5 (client only).

Overview of TLS implementations and protocols

Server:

+-----------+-----------------------------------------+
| Library   | Supported TLS versions                  |
+-----------+-----------------------------------------+
| WolfSSL   | TLSv1.1, TLSv1,2                        |
+-----------+-----------------------------------------+
| OpenSSL   | (TLSv1.0), TLSv1.1, TLSv1,2, TLSv1.3    |
+-----------+-----------------------------------------+
| LibreSSL  | (TLSv1.0), TLSv1.1, TLSv1,2, TLSv1.3    |
+-----------+-----------------------------------------+

Client (MariaDB Connector/C)
+-----------+-----------------------------------------+
| Library   | Supported TLS versions                  |
+-----------+-----------------------------------------+
| GnuTLS    | (TLSv1.0), TLSv1.1, TLSv1.2, TLSv1.3    |
+-----------+-----------------------------------------+
| Schannel  | (TLSv1.0), TLSv1.1, TLSv1.2             |
+-----------+-----------------------------------------+
| OpenSSL   | (TLSv1.0), TLSv1.1, TLSv1,2, TLSv1.3    |
+-----------+-----------------------------------------+
| LibreSSL  | (TLSv1.0), TLSv1.1, TLSv1,2, TLSv1.3    |
+-----------+-----------------------------------------+

client/client_priv.h

@@ -46,7 +46,7 @@ enum options_client
   OPT_MAX_ALLOWED_PACKET, OPT_NET_BUFFER_LENGTH,
   OPT_SELECT_LIMIT, OPT_MAX_JOIN_SIZE, OPT_SSL_SSL,
   OPT_SSL_KEY, OPT_SSL_CERT, OPT_SSL_CA, OPT_SSL_CAPATH,
-  OPT_SSL_CIPHER, OPT_SHUTDOWN_TIMEOUT, OPT_LOCAL_INFILE,
+  OPT_SSL_CIPHER, OPT_TLS_VERSION, OPT_SHUTDOWN_TIMEOUT, OPT_LOCAL_INFILE,
   OPT_DELETE_MASTER_LOGS, OPT_COMPACT,
   OPT_PROMPT, OPT_IGN_LINES,OPT_TRANSACTION,OPT_MYSQL_PROTOCOL,
   OPT_FRM, OPT_SKIP_OPTIMIZATION,

client/mysql.cc

@@ -1363,6 +1363,7 @@ static bool do_connect(MYSQL *mysql, const char *host, const char *user,
 		  opt_ssl_capath, opt_ssl_cipher);
     mysql_options(mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(mysql,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqladmin.cc

@@ -359,6 +359,7 @@ int main(int argc,char *argv[])
 		  opt_ssl_capath, opt_ssl_cipher);
     mysql_options(&mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(&mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(&mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(&mysql,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqlbinlog.cc

@@ -2126,6 +2126,7 @@ static Exit_status safe_connect()
                   opt_ssl_capath, opt_ssl_cipher);
     mysql_options(mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(mysql,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqldump.c

@@ -1709,6 +1709,7 @@ static int connect_to_db(char *host, char *user,char *passwd)
                   opt_ssl_capath, opt_ssl_cipher);
     mysql_options(&mysql_connection, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(&mysql_connection, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(&mysql_connection, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(&mysql_connection,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqlimport.c

@@ -448,6 +448,7 @@ static MYSQL *db_connect(char *host, char *database,
 		  opt_ssl_capath, opt_ssl_cipher);
     mysql_options(mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(mysql,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqlshow.c

@@ -122,6 +122,7 @@ int main(int argc, char **argv)
 		  opt_ssl_capath, opt_ssl_cipher);
     mysql_options(&mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(&mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(&mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
   }
   mysql_options(&mysql,MYSQL_OPT_SSL_VERIFY_SERVER_CERT,
                 (char*)&opt_ssl_verify_server_cert);

client/mysqltest.cc

@@ -6068,6 +6068,7 @@ void do_connect(struct st_command *command)
 		  opt_ssl_capath, ssl_cipher ? ssl_cipher : opt_ssl_cipher);
     mysql_options(con_slot->mysql, MYSQL_OPT_SSL_CRL, opt_ssl_crl);
     mysql_options(con_slot->mysql, MYSQL_OPT_SSL_CRLPATH, opt_ssl_crlpath);
+    mysql_options(con_slot->mysql, MARIADB_OPT_TLS_VERSION, opt_tls_version);
 #if MYSQL_VERSION_ID >= 50000
     /* Turn on ssl_verify_server_cert only if host is "localhost" */
     opt_ssl_verify_server_cert= !strcmp(ds_host.str, "localhost");

extra/mariabackup/xtrabackup.cc

@@ -199,6 +199,7 @@ static char*	log_ignored_opt;
 
 
 extern my_bool opt_use_ssl;
+extern char *opt_tls_version;
 my_bool opt_ssl_verify_server_cert;
 my_bool opt_extended_validation;
 my_bool opt_encrypted_backup;
@@ -830,6 +831,7 @@ enum options_xtrabackup
   OPT_XTRA_CHECK_PRIVILEGES
 };
 
+
 struct my_option xb_client_options[] =
 {
   {"verbose", 'V', "display verbose output",

include/sslopt-longopts.h

@@ -46,6 +46,11 @@
     "Certificate revocation list path (implies --ssl).",
    &opt_ssl_crlpath, &opt_ssl_crlpath, 0, GET_STR, REQUIRED_ARG,
    0, 0, 0, 0, 0, 0},
+  {"tls-version", OPT_TLS_VERSION,
+   "TLS protocol version for secure connection.",
+   &opt_tls_version, &opt_tls_version, 0, GET_STR, REQUIRED_ARG,
+   0, 0, 0, 0, 0, 0},
+
 #ifdef MYSQL_CLIENT
   {"ssl-verify-server-cert", OPT_SSL_VERIFY_SERVER_CERT,
    "Verify server's \"Common Name\" in its cert against hostname used "

include/sslopt-vars.h

@@ -30,6 +30,7 @@ SSL_STATIC char *opt_ssl_cipher  = 0;
 SSL_STATIC char *opt_ssl_key     = 0;
 SSL_STATIC char *opt_ssl_crl     = 0;
 SSL_STATIC char *opt_ssl_crlpath = 0;
+SSL_STATIC char *opt_tls_version = 0;
 #ifdef MYSQL_CLIENT
 SSL_STATIC my_bool opt_ssl_verify_server_cert= 0;
 #endif

include/violite.h

@@ -59,6 +59,11 @@ struct vio_keepalive_opts
 };
 
 
+#define VIO_TLSv1_0   1
+#define VIO_TLSv1_1   2
+#define VIO_TLSv1_2   4
+#define VIO_TLSv1_3   8
+
 #define VIO_LOCALHOST 1U                        /* a localhost connection */
 #define VIO_BUFFERED_READ 2U                    /* use buffered read */
 #define VIO_READ_BUFFER_SIZE 16384U             /* size of read buffer */
@@ -148,7 +153,8 @@ enum enum_ssl_init_error
 {
   SSL_INITERR_NOERROR= 0, SSL_INITERR_CERT, SSL_INITERR_KEY,
   SSL_INITERR_NOMATCH, SSL_INITERR_BAD_PATHS, SSL_INITERR_CIPHERS,
-  SSL_INITERR_MEMFAIL, SSL_INITERR_DH, SSL_INITERR_LASTERR
+  SSL_INITERR_MEMFAIL, SSL_INITERR_DH, SSL_INITERR_PROTOCOL,
+  SSL_INITERR_LASTERR
 };
 const char* sslGetErrString(enum enum_ssl_init_error err);
 
@@ -169,7 +175,8 @@ struct st_VioSSLFd
 *new_VioSSLAcceptorFd(const char *key_file, const char *cert_file,
 		      const char *ca_file,const char *ca_path,
 		      const char *cipher, enum enum_ssl_init_error *error,
-                      const char *crl_file, const char *crl_path);
+		      const char *crl_file, const char *crl_path,
+		      ulonglong tls_version);
 void free_vio_ssl_acceptor_fd(struct st_VioSSLFd *fd);
 #endif /* HAVE_OPENSSL */
 

mysql-test/main/mysqld--help.result

@@ -1352,6 +1352,8 @@ The following specify which files/extra groups are read (specified before remain
  --time-format=name  The TIME format (ignored)
  --timed-mutexes     Specify whether to time mutexes. Deprecated, has no
  effect.
+ --tls-version=name  TLS protocol version for secure connections.. Any
+ combination of: TLSv1.0, TLSv1.1, TLSv1.2, TLSv1.3
  --tmp-disk-table-size=# 
  Max size for data for an internal temporary on-disk
  MyISAM or Aria table.

mysql-test/main/mysqld--help.test

@@ -23,7 +23,7 @@ perl;
                log-slow-queries pid-file slow-query-log-file log-basename
                datadir slave-load-tmpdir tmpdir socket thread-pool-size
                large-files-support lower-case-file-system system-time-zone
-               collation-server character-set-server log-tc-size version.*/;
+               collation-server character-set-server log-tc-size tls-version version.*/;
 
   # Plugins which may or may not be there:
   @plugins=qw/innodb archive blackhole federated partition

mysql-test/main/openssl_6975.test

@@ -18,25 +18,25 @@ let $mysql=$MYSQL --ssl-key=$MYSQL_TEST_DIR/std_data/client-key.pem --ssl-cert=$
 
 disable_abort_on_error;
 echo TLS1.2 ciphers: user is ok with any cipher;
-exec $mysql                  --ssl-cipher=AES128-SHA256;
+exec $mysql --tls-version=TLSv1.2 --ssl-cipher=AES128-SHA256;
 --replace_result DHE-RSA-CHACHA20-POLY1305 DHE-RSA-AES256-GCM-SHA384 ECDHE-RSA-AES256-GCM-SHA384 DHE-RSA-AES256-GCM-SHA384
-exec $mysql                  --ssl-cipher=TLSv1.2;
+exec $mysql --tls-version=TLSv1.2 --ssl-cipher=TLSv1.2;
 echo TLS1.2 ciphers: user requires SSLv3 cipher AES128-SHA;
-exec $mysql --user ssl_sslv3 --ssl-cipher=AES128-SHA256;
-exec $mysql --user ssl_sslv3 --ssl-cipher=TLSv1.2;
+exec $mysql --user ssl_sslv3 --tls-version=TLSv1.2 --ssl-cipher=AES128-SHA256;
+exec $mysql --user ssl_sslv3 --tls-version=TLSv1.2 --ssl-cipher=TLSv1.2;
 echo TLS1.2 ciphers: user requires TLSv1.2 cipher AES128-SHA256;
-exec $mysql --user ssl_tls12 --ssl-cipher=AES128-SHA256;
-exec $mysql --user ssl_tls12 --ssl-cipher=TLSv1.2;
+exec $mysql --user ssl_tls12 --tls-version=TLSv1.2 --ssl-cipher=AES128-SHA256;
+exec $mysql --user ssl_tls12 --tls-version=TLSv1.2 --ssl-cipher=TLSv1.2;
 
 echo SSLv3 ciphers: user is ok with any cipher;
-exec $mysql                  --ssl-cipher=AES256-SHA;
-exec $mysql                  --ssl-cipher=SSLv3;
+exec $mysql --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=AES256-SHA;
+exec $mysql --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=SSLv3;
 echo SSLv3 ciphers: user requires SSLv3 cipher AES128-SHA;
-exec $mysql --user ssl_sslv3 --ssl-cipher=AES128-SHA;
-exec $mysql --user ssl_sslv3 --ssl-cipher=SSLv3;
+exec $mysql --user ssl_sslv3 --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=AES128-SHA;
+exec $mysql --user ssl_sslv3 --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=SSLv3;
 echo SSLv3 ciphers: user requires TLSv1.2 cipher AES128-SHA256;
-exec $mysql --user ssl_tls12 --ssl-cipher=AES128-SHA;
-exec $mysql --user ssl_tls12 --ssl-cipher=SSLv3;
+exec $mysql --user ssl_tls12 --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=AES128-SHA;
+exec $mysql --user ssl_tls12 --tls-version=TLSv1.0,TLSv1.1,TLSv1.2 --ssl-cipher=SSLv3;
 
 drop user ssl_sslv3@localhost;
 drop user ssl_tls12@localhost;

mysql-test/main/tls_version.opt

@@ -0,0 +1 @@
+--tls_version=TLSv1.1,TLSv1.2

mysql-test/main/tls_version.result

@@ -0,0 +1,14 @@
+Variable_name	Value
+Ssl_version	TLSv1.2
+Variable_name	Value
+Ssl_version	TLSv1.2
+Variable_name	Value
+Ssl_version	TLSv1.1
+Variable_name	Value
+Ssl_version	TLSv1.1
+Variable_name	Value
+Ssl_version	TLSv1.2
+Variable_name	Value
+Ssl_version	TLSv1.2
+@@tls_version
+TLSv1.1,TLSv1.2

mysql-test/main/tls_version.test

@@ -0,0 +1,24 @@
+# Tests for SSL connections, only run if mysqld is compiled
+# with support for SSL.
+
+-- source include/have_ssl_communication.inc
+#default is highest available version: TLSv1.2
+--exec $MYSQL --host=localhost --ssl -e "show status like 'ssl_version';"
+# TLSv1.2
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.2 -e "show status like 'ssl_version';"
+# TLSv1.1
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.1 -e "show status like 'ssl_version';"
+# if a gap is between TLS versions, lowest version number should be used (TLS1.1)
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.1,TLSv1.3 -e "show status like 'ssl_version';"
+# TLSv1.3 is not enabled, so TLSv1.2 should be used
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.2,TLSv1.3 -e "show status like 'ssl_version';"
+# Highest TLS version number should be used (TLSv1.2)
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.1,TLSv1.2 -e "show status like 'ssl_version';"
+# Errors:
+# TLS v1.0 is disabled on server, so we should get an error
+--replace_regex /2026 SSL connection error.*/2026 SSL connection error: xxxx/
+--error 1
+--exec $MYSQL --host=localhost --ssl --tls_version=TLSv1.0 -e "show status like 'ssl_version';"
+# finally list available protocols
+--exec $MYSQL --host=localhost --ssl -e "select @@tls_version;"
+

mysql-test/suite/sys_vars/inc/sysvars_server.inc

@@ -31,6 +31,7 @@ select * from information_schema.system_variables
           'rand_seed1',
           'rand_seed2',
           'system_time_zone',
+          'tls_version',
           'version_comment',
           'version_source_revision',
           'version_compile_machine', 'version_compile_os',
@@ -55,6 +56,7 @@ select VARIABLE_NAME, VARIABLE_SCOPE, VARIABLE_TYPE, VARIABLE_COMMENT,
           'rand_seed1',
           'rand_seed2',
           'system_time_zone',
+          'tls_version',
           'version_comment',
           'version_source_revision',
           'version_compile_machine', 'version_compile_os',

mysql-test/suite/sys_vars/r/sysvars_server_embedded.result

@@ -20,6 +20,7 @@ variable_name not in (
 'rand_seed1',
 'rand_seed2',
 'system_time_zone',
+'tls_version',
 'version_comment',
 'version_source_revision',
 'version_compile_machine', 'version_compile_os',
@@ -4661,6 +4662,7 @@ where variable_name in (
 'rand_seed1',
 'rand_seed2',
 'system_time_zone',
+'tls_version',
 'version_comment',
 'version_source_revision',
 'version_compile_machine', 'version_compile_os',
@@ -4767,6 +4769,16 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NULL
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	NULL
+VARIABLE_NAME	TLS_VERSION
+VARIABLE_SCOPE	GLOBAL
+VARIABLE_TYPE	SET
+VARIABLE_COMMENT	TLS protocol version for secure connections.
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	TLSv1.0,TLSv1.1,TLSv1.2,TLSv1.3
+READ_ONLY	YES
+COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	VERSION
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	VARCHAR

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -20,6 +20,7 @@ variable_name not in (
 'rand_seed1',
 'rand_seed2',
 'system_time_zone',
+'tls_version',
 'version_comment',
 'version_source_revision',
 'version_compile_machine', 'version_compile_os',
@@ -5725,6 +5726,7 @@ where variable_name in (
 'rand_seed1',
 'rand_seed2',
 'system_time_zone',
+'tls_version',
 'version_comment',
 'version_source_revision',
 'version_compile_machine', 'version_compile_os',
@@ -5831,6 +5833,16 @@ NUMERIC_BLOCK_SIZE	NULL
 ENUM_VALUE_LIST	NULL
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	NULL
+VARIABLE_NAME	TLS_VERSION
+VARIABLE_SCOPE	GLOBAL
+VARIABLE_TYPE	SET
+VARIABLE_COMMENT	TLS protocol version for secure connections.
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	TLSv1.0,TLSv1.1,TLSv1.2,TLSv1.3
+READ_ONLY	YES
+COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	VERSION
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	VARCHAR

sql/mysqld.cc

@@ -1444,8 +1444,8 @@ Query_cache query_cache;
 my_bool opt_use_ssl  = 0;
 char *opt_ssl_ca= NULL, *opt_ssl_capath= NULL, *opt_ssl_cert= NULL,
   *opt_ssl_cipher= NULL, *opt_ssl_key= NULL, *opt_ssl_crl= NULL,
-  *opt_ssl_crlpath= NULL;
-
+  *opt_ssl_crlpath= NULL, *opt_tls_version= NULL;
+ulonglong tls_version= 0;
 
 static scheduler_functions thread_scheduler_struct, extra_thread_scheduler_struct;
 scheduler_functions *thread_scheduler= &thread_scheduler_struct,
@@ -4722,7 +4722,8 @@ static void init_ssl()
     ssl_acceptor_fd= new_VioSSLAcceptorFd(opt_ssl_key, opt_ssl_cert,
 					  opt_ssl_ca, opt_ssl_capath,
 					  opt_ssl_cipher, &error,
-                                          opt_ssl_crl, opt_ssl_crlpath);
+					  opt_ssl_crl, opt_ssl_crlpath,
+					  tls_version);
     DBUG_PRINT("info",("ssl_acceptor_fd: %p", ssl_acceptor_fd));
     if (!ssl_acceptor_fd)
     {
@@ -4761,7 +4762,8 @@ int reinit_ssl()
 
   enum enum_ssl_init_error error = SSL_INITERR_NOERROR;
   st_VioSSLFd *new_fd = new_VioSSLAcceptorFd(opt_ssl_key, opt_ssl_cert,
-    opt_ssl_ca, opt_ssl_capath, opt_ssl_cipher, &error, opt_ssl_crl, opt_ssl_crlpath);
+    opt_ssl_ca, opt_ssl_capath, opt_ssl_cipher, &error, opt_ssl_crl,
+    opt_ssl_crlpath, tls_version);
 
   if (!new_fd)
   {

sql/mysqld.h

@@ -635,6 +635,7 @@ extern Atomic_counter<uint32_t> thread_count;
 
 extern char *opt_ssl_ca, *opt_ssl_capath, *opt_ssl_cert, *opt_ssl_cipher,
   *opt_ssl_key, *opt_ssl_crl, *opt_ssl_crlpath;
+extern ulonglong tls_version;
 
 extern MYSQL_PLUGIN_IMPORT pthread_key(THD*, THR_THD);
 
@@ -697,6 +698,7 @@ enum options_mysqld
   OPT_WSREP_SYNC_WAIT,
 #endif /* WITH_WSREP */
   OPT_MYSQL_COMPATIBILITY,
+  OPT_TLS_VERSION,
   OPT_MYSQL_TO_BE_IMPLEMENTED,
   OPT_which_is_always_the_last
 };

sql/sys_vars.cc

@@ -3565,6 +3565,29 @@ static Sys_var_charptr Sys_ssl_crlpath(
        READ_ONLY GLOBAL_VAR(opt_ssl_crlpath), SSL_OPT(OPT_SSL_CRLPATH),
        IN_FS_CHARSET, DEFAULT(0));
 
+static const char *tls_version_names[]=
+{
+  "TLSv1.0",
+  "TLSv1.1",
+  "TLSv1.2",
+  "TLSv1.3",
+  0
+};
+
+export bool tls_version_string_representation(THD *thd, sql_mode_t sql_mode,
+                                              LEX_CSTRING *ls)
+{
+  set_to_string(thd, ls, tls_version, tls_version_names);
+  return ls->str == 0;
+}
+
+static Sys_var_set Sys_tls_version(
+       "tls_version",
+       "TLS protocol version for secure connections.",
+       READ_ONLY GLOBAL_VAR(tls_version), CMD_LINE(REQUIRED_ARG),
+       tls_version_names,
+       DEFAULT(VIO_TLSv1_1 | VIO_TLSv1_2 | VIO_TLSv1_3));
+
 static Sys_var_mybool Sys_standard_compliant_cte(
        "standard_compliant_cte",
        "Allow only CTEs compliant to SQL standard",