Bug#20543 select on information_schema strange warnings, view, different schemas/users

The fix is: if user has privileges to view fields and user has any
(insert,select,delete,update) privileges on underlying view 
then 'show fields' and select from I_S.COLUMNS table are sucsessful.

mysql-test/r/information_schema_db.result

@@ -97,3 +97,49 @@ v2	VIEW	View 'test.v2' references invalid table(s) or column(s) or function(s) o
 drop function f1;
 drop function f2;
 drop view v1, v2;
+create database testdb_1;
+create user testdb_1@localhost;
+grant all on testdb_1.* to testdb_1@localhost with grant option;
+create user testdb_2@localhost;
+grant all on test.* to testdb_2@localhost with grant option;
+use testdb_1;
+create table t1 (f1 char(4));
+create view v1 as select f1 from t1;
+grant insert on v1 to testdb_2@localhost;
+create table t3 (f1 char(4), f2 char(4));
+create view v3 as select f1,f2 from t3;
+grant insert(f1), insert(f2) on v3 to testdb_2@localhost;
+create view v2 as select f1 from testdb_1.v1;
+create view v4 as select f1,f2 from testdb_1.v3;
+revoke insert(f1) on v3 from testdb_2@localhost;
+show create view v4;
+ERROR HY000: EXPLAIN/SHOW can not be issued; lacking privileges for underlying table
+show fields from v4;
+ERROR HY000: EXPLAIN/SHOW can not be issued; lacking privileges for underlying table
+show fields from v2;
+Field	Type	Null	Key	Default	Extra
+f1	char(4)	YES		NULL	
+show fields from testdb_1.v1;
+Field	Type	Null	Key	Default	Extra
+f1	char(4)	YES		NULL	
+show create view v2;
+View	Create View
+v2	CREATE ALGORITHM=UNDEFINED DEFINER=`testdb_2`@`localhost` SQL SECURITY DEFINER VIEW `test`.`v2` AS select `v1`.`f1` AS `f1` from `testdb_1`.`v1`
+show create view testdb_1.v1;
+ERROR 42000: SHOW VIEW command denied to user 'testdb_2'@'localhost' for table 'v1'
+select table_name from information_schema.columns a 
+where a.table_name = 'v2';
+table_name
+v2
+select view_definition from information_schema.views a 
+where a.table_name = 'v2';
+view_definition
+/* ALGORITHM=UNDEFINED */ select `v1`.`f1` AS `f1` from `testdb_1`.`v1`
+select view_definition from information_schema.views a 
+where a.table_name = 'testdb_1.v1';
+view_definition
+select * from v2;
+ERROR HY000: View 'test.v2' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
+drop view testdb_1.v1,v2, testdb_1.v3, v4;
+drop database testdb_1;
+drop user testdb_1@localhost;

mysql-test/t/information_schema_db.test

@@ -98,3 +98,59 @@ where table_schema='test';
 drop function f1;
 drop function f2;
 drop view v1, v2;
+
+#
+# Bug#20543: select on information_schema strange warnings, view, different
+#             schemas/users
+#
+#
+create database testdb_1;
+create user testdb_1@localhost;
+grant all on testdb_1.* to testdb_1@localhost with grant option;
+
+create user testdb_2@localhost;
+grant all on test.* to testdb_2@localhost with grant option;
+
+connect (testdb_1,localhost,testdb_1,,test);
+use testdb_1;
+create table t1 (f1 char(4));
+create view v1 as select f1 from t1;
+grant insert on v1 to testdb_2@localhost;
+
+create table t3 (f1 char(4), f2 char(4));
+create view v3 as select f1,f2 from t3;
+grant insert(f1), insert(f2) on v3 to testdb_2@localhost;
+
+connect (testdb_2,localhost,testdb_2,,test);
+create view v2 as select f1 from testdb_1.v1;
+create view v4 as select f1,f2 from testdb_1.v3;
+
+connection testdb_1;
+revoke insert(f1) on v3 from testdb_2@localhost;
+connection testdb_2;
+
+--error 1345
+show create view v4;
+--error 1345
+show fields from v4;
+
+show fields from v2;
+show fields from testdb_1.v1;
+show create view v2;
+--error 1142
+show create view testdb_1.v1;
+
+select table_name from information_schema.columns a 
+where a.table_name = 'v2';
+select view_definition from information_schema.views a 
+where a.table_name = 'v2';
+select view_definition from information_schema.views a 
+where a.table_name = 'testdb_1.v1';
+
+--error 1356
+select * from v2;
+
+connection default;
+drop view testdb_1.v1,v2, testdb_1.v3, v4;
+drop database testdb_1;
+drop user testdb_1@localhost;

sql/sql_acl.cc

@@ -3787,9 +3787,24 @@ bool check_column_grant_in_table_ref(THD *thd, TABLE_LIST * table_ref,
   if (table_ref->view || table_ref->field_translation)
   {
     /* View or derived information schema table. */
+    ulong view_privs;
     grant= &(table_ref->grant);
     db_name= table_ref->view_db.str;
     table_name= table_ref->view_name.str;
+    if (table_ref->belong_to_view && 
+        (thd->lex->sql_command == SQLCOM_SHOW_FIELDS ||
+         thd->lex->sql_command == SQLCOM_SHOW_CREATE))
+    {
+      view_privs= get_column_grant(thd, grant, db_name, table_name, name);
+      if (view_privs & VIEW_ANY_ACL)
+      {
+        table_ref->belong_to_view->allowed_show= TRUE;
+        return FALSE;
+      }
+      table_ref->belong_to_view->allowed_show= FALSE;
+      my_message(ER_VIEW_NO_EXPLAIN, ER(ER_VIEW_NO_EXPLAIN), MYF(0));
+      return TRUE;
+    }
   }
   else
   {

sql/sql_show.cc

@@ -3110,31 +3110,18 @@ static int get_schema_views_record(THD *thd, struct st_table_list *tables,
   if (tables->view)
   {
     Security_context *sctx= thd->security_ctx;
-    ulong grant= SHOW_VIEW_ACL;
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-    char *save_table_name= tables->table_name;
-    if (!my_strcasecmp(system_charset_info, tables->definer.user.str,
-                       sctx->priv_user) &&
-        !my_strcasecmp(system_charset_info, tables->definer.host.str,
-                       sctx->priv_host))
-      grant= SHOW_VIEW_ACL;
-    else
+    if (!tables->allowed_show)
     {
-      tables->table_name= tables->view_name.str;
-      if (check_access(thd, SHOW_VIEW_ACL , base_name,
-                       &tables->grant.privilege, 0, 1,
-                       test(tables->schema_table)))
-        grant= get_table_grant(thd, tables);
-      else
-        grant= tables->grant.privilege;
+      if (!my_strcasecmp(system_charset_info, tables->definer.user.str,
+                         sctx->priv_user) &&
+          !my_strcasecmp(system_charset_info, tables->definer.host.str,
+                         sctx->priv_host))
+        tables->allowed_show= TRUE;
     }
-    tables->table_name= save_table_name;
-#endif
-
     restore_record(table, s->default_values);
     table->field[1]->store(tables->view_db.str, tables->view_db.length, cs);
     table->field[2]->store(tables->view_name.str, tables->view_name.length, cs);
-    if (grant & SHOW_VIEW_ACL)
+    if (tables->allowed_show)
     {
       char buff[2048];
       String qwe_str(buff, sizeof(buff), cs);

sql/sql_view.cc

@@ -934,7 +934,8 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table)
       }
     }
     else if (!table->prelocking_placeholder &&
-             old_lex->sql_command == SQLCOM_SHOW_CREATE)
+             old_lex->sql_command == SQLCOM_SHOW_CREATE &&
+             !table->belong_to_view)
     {
       if (check_table_access(thd, SHOW_VIEW_ACL, table, 0))
         goto err;

sql/table.h

@@ -569,6 +569,7 @@ typedef struct st_table_list
     tables. Unlike 'next_local', this in this list views are *not*
     leaves. Created in setup_tables() -> make_leaves_list().
   */
+  bool allowed_show;
   st_table_list	*next_leaf;
   Item          *where;                 /* VIEW WHERE clause condition */
   Item          *check_option;          /* WITH CHECK OPTION condition */