manual merge to reconcile with MySQL ticket 27145

1 files changed, 33 insertions, 3 deletions

diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 6051aa028c7..525d8b9cccc 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -1281,9 +1281,39 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     if (!table->prelocking_placeholder &&
         (old_lex->sql_command == SQLCOM_SELECT && old_lex->describe))
     {
-      if (check_table_access(thd, SELECT_ACL, view_tables, FALSE,
-                             UINT_MAX, TRUE) &&
-          check_table_access(thd, SHOW_VIEW_ACL, table, FALSE, UINT_MAX, TRUE))
+      /*
+        The user we run EXPLAIN as (either the connected user who issued
+        the EXPLAIN statement, or the definer of a SUID stored routine
+        which contains the EXPLAIN) should have both SHOW_VIEW_ACL and
+        SELECT_ACL on the view being opened as well as on all underlying
+        views since EXPLAIN will disclose their structure. This user also
+        should have SELECT_ACL on all underlying tables of the view since
+        this EXPLAIN will disclose information about the number of rows in it.
+
+        To perform this privilege check we create auxiliary TABLE_LIST object
+        for the view in order a) to avoid trashing "table->grant" member for
+        original table list element, which contents can be important at later
+        stage for column-level privilege checking b) get TABLE_LIST object
+        with "security_ctx" member set to 0, i.e. forcing check_table_access()
+        to use active user's security context.
+
+        There is no need for creating similar copies of table list elements
+        for underlying tables since they are just have been constructed and
+        thus have TABLE_LIST::security_ctx == 0 and fresh TABLE_LIST::grant
+        member.
+
+        Finally at this point making sure we have SHOW_VIEW_ACL on the views
+        will suffice as we implicitly require SELECT_ACL anyway.
+      */
+        
+      TABLE_LIST view;
+      bzero((char *)&view, sizeof(TABLE_LIST));
+      view.db= table->db;
+      view.table_name= table->table_name;
+
+      if (check_table_access(thd, SELECT_ACL, view_tables,
+                             FALSE, UINT_MAX, TRUE) ||
+          check_table_access(thd, SHOW_VIEW_ACL, &view, FALSE, UINT_MAX, TRUE))
       {
         my_message(ER_VIEW_NO_EXPLAIN, ER(ER_VIEW_NO_EXPLAIN), MYF(0));
         goto err;