Bug#18790730 - CROSS-DATABASE FOREIGN KEY WITHOUT PERMISSIONS

               CHECK.

Analysis:
----------
Issue here is, while creating or altering the InnoDB table,
if the foreign key defined on the table references a parent
table on which the user has no access privileges then the
table is created without reporting any error. 

Currently the privilege level REFERENCES_ACL is unused
and is not used for access evaluation while creating the
table with a foreign key constraint or adding the foreign
key constraint to a table. But when no privileges are granted
to user then also access evaluation on parent table is ignored.

Fix:
---------
For DMLs, irrelevant of the fact, support does not want any
changes to avoid permission checks on every operation.

So, as a fix, added a function "check_fk_parent_table_access" 
to check whether any of the SELECT_ACL, INSERT_ACL, UDPATE_ACL,
DELETE_ACL or REFERENCE_ACL privileges are granted for user
at table level. If none of them is granted then error is reported.
This function is called during the table creation and alter 
operation. 

1 files changed, 3 insertions, 0 deletions

diff --git a/sql/sql_parse.h b/sql/sql_parse.h
index 9a55174b0fb..f7b4d530543 100644
--- a/sql/sql_parse.h
+++ b/sql/sql_parse.h
@@ -45,6 +45,9 @@ bool delete_precheck(THD *thd, TABLE_LIST *tables);
 bool insert_precheck(THD *thd, TABLE_LIST *tables);
 bool create_table_precheck(THD *thd, TABLE_LIST *tables,
                            TABLE_LIST *create_table);
+bool check_fk_parent_table_access(THD *thd,
+                                  HA_CREATE_INFO *create_info,
+                                  Alter_info *alter_info);
 
 bool parse_sql(THD *thd,
                Parser_state *parser_state,