MDEV-9610 Trigger on normal table can't insert into CONNECT engine table - Access Denied

in case of prelocking, don't check table->grant.privilege
in handler::external_lock(), do it in
handler::start_stmt().

storage/connect/ha_connect.cc

@@ -4054,7 +4054,7 @@ int ha_connect::delete_all_rows()
 } // end of delete_all_rows
 
 
-bool ha_connect::check_privileges(THD *thd, PTOS options, char *dbn)
+bool ha_connect::check_privileges(THD *thd, PTOS options, char *dbn, bool quick)
 {
   const char *db= (dbn && *dbn) ? dbn : NULL;
   TABTYPE     type=GetRealType(options);
@@ -4081,6 +4081,7 @@ bool ha_connect::check_privileges(THD *thd, PTOS options, char *dbn)
     case TAB_VEC:
     case TAB_JSON:
       if (options->filename && *options->filename) {
+        if (!quick) {
         char *s, path[FN_REFLEN], dbpath[FN_REFLEN];
 #if defined(__WIN__)
         s= "\\";
@@ -4099,7 +4100,7 @@ bool ha_connect::check_privileges(THD *thd, PTOS options, char *dbn)
           my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--secure-file-priv");
           return true;
           } // endif path
-
+        }
       } else
         return false;
 
@@ -4121,10 +4122,13 @@ bool ha_connect::check_privileges(THD *thd, PTOS options, char *dbn)
         Otherwise it's a DML, the table was normally opened, locked,
         privilege were already checked, and table->grant.privilege is set.
         With SQL SECURITY DEFINER, table->grant.privilege has definer's privileges.
+
+        Unless we're in prelocking mode, in this case table->grant.privilege
+        is only checked in start_stmt(), not in external_lock().
       */
       if (!table || !table->mdl_ticket || table->mdl_ticket->get_type() == MDL_EXCLUSIVE)
         return check_access(thd, FILE_ACL, db, NULL, NULL, 0, 0);
-      if (table->grant.privilege & FILE_ACL)
+      if ((!quick && thd->lex->requires_prelocking()) || table->grant.privilege & FILE_ACL)
         return false;
       status_var_increment(thd->status_var.access_denied_errors);
       my_error(access_denied_error_code(thd->password), MYF(0),
@@ -4308,6 +4312,9 @@ int ha_connect::start_stmt(THD *thd, thr_lock_type lock_type)
   PGLOBAL g= GetPlug(thd, xp);
   DBUG_ENTER("ha_connect::start_stmt");
 
+  if (check_privileges(thd, GetTableOptionStruct(), table->s->db.str, true))
+    DBUG_RETURN(HA_ERR_INTERNAL_ERROR);
+
   // Action will depend on lock_type
   switch (lock_type) {
     case TL_WRITE_ALLOW_WRITE:

storage/connect/ha_connect.h

@@ -536,7 +536,7 @@ int index_prev(uchar *buf);
   DsMrr_impl ds_mrr;
 
 protected:
-  bool check_privileges(THD *thd, PTOS options, char *dbn);
+  bool check_privileges(THD *thd, PTOS options, char *dbn, bool quick=false);
   MODE CheckMode(PGLOBAL g, THD *thd, MODE newmode, bool *chk, bool *cras);
   char *GetDBfromName(const char *name);
 

storage/connect/mysql-test/connect/r/grant3.result

+create table tcon (i int) engine=Connect table_type=DOS file_name='tcon.dos';
+create table tin (i int);
+create trigger tr after insert on tin for each row insert into tcon values (new.i);
+insert into tin values (1);
+drop table tin,tcon;

storage/connect/mysql-test/connect/t/grant3.test

+#
+# MDEV-9610 Trigger on normal table can't insert into CONNECT engine table - Access Denied
+#
+create table tcon (i int) engine=Connect table_type=DOS file_name='tcon.dos';
+create table tin (i int);
+create trigger tr after insert on tin for each row insert into tcon values (new.i);
+insert into tin values (1);
+drop table tin,tcon;
+
+let datadir=`select @@datadir`;
+remove_file $datadir/test/tcon.dos;