WL#2486 - natural/using joins according to SQL:2003

Post-review fixes that simplify the way access rights
are checked during name resolution and factor out all
entry points to check access rights into one single
function.


sql/item.cc:
  Simplfied find_field_in_table - factored out all acces right checks
  into a separate function.
sql/mysql_priv.h:
  Simplified the way we control whether to perform access right
  checks for columns.
sql/sql_acl.cc:
  - Added new functon check_column_grant_in_table_ref that serves as a single
    point of entry to check access rights during name resolution for different
    kinds of table references.
  - Moved check_grant_column_in_sctx to sql_acl.cc where it
    logically belongs.
  - Removed the parameter check_grants - it is checked before
    calling the function.
sql/sql_acl.h:
  - Added new function check_column_grant_in_table_ref.
  - Made check_grant_column_in_sctx available to other modules.
sql/sql_base.cc:
  - Factored out all code that check access rights for columns during
    name resolution into one function - check_column_grant_in_table_ref.
  - Moved check_grant_column_in_sctx to sql_acl.cc where it
    logically belongs.
  - Removed the parameter check_grants - it is checked before
    calling the function.
sql/table.cc:
  Removed code that duplicates the functionality of
  check_column_grant_in_table_ref, and called directly
  that function.
sql/table.h:
  check_grants method is replaced by more general
  check_column_grant_in_table_ref.

sql/item.cc

@@ -5179,7 +5179,7 @@ void Item_trigger_field::setup_field(THD *thd, TABLE *table)
     set field_idx properly.
   */
   (void)find_field_in_table(thd, table, field_name, (uint) strlen(field_name),
-                            0, 0, &field_idx, 0);
+                            0, &field_idx);
   thd->set_query_id= save_set_query_id;
   triggers= table->triggers;
 }

sql/mysql_priv.h

@@ -794,14 +794,12 @@ find_field_in_table_ref(THD *thd, TABLE_LIST *table_list,
                         const char *name, uint length,
                         const char *item_name, const char *db_name,
                         const char *table_name, Item **ref,
-                        bool check_grants_table, bool check_grants_view,
-                        bool allow_rowid, uint *cached_field_index_ptr,
+                        bool check_privileges, bool allow_rowid,
+                        uint *cached_field_index_ptr,
                         bool register_tree_change, TABLE_LIST **actual_table);
 Field *
-find_field_in_table(THD *thd, TABLE *table, const char *name,
-                    uint length, bool check_grants, bool allow_rowid,
-                    uint *cached_field_index_ptr,
-                    Security_context *sctx);
+find_field_in_table(THD *thd, TABLE *table, const char *name, uint length,
+                    bool allow_rowid, uint *cached_field_index_ptr);
 
 #ifdef HAVE_OPENSSL
 #include <openssl/des.h>

sql/sql_acl.cc

@@ -2763,7 +2763,7 @@ bool mysql_table_grant(THD *thd, TABLE_LIST *table_list,
         Field *f=find_field_in_table_ref(thd, table_list, column->column.ptr(),
                                          column->column.length(),
                                          column->column.ptr(), NULL, NULL,
-                                         0, 1, 1, 0,
+                                         NULL, TRUE, FALSE,
                                          &unused_field_idx, FALSE, &dummy);
         if (f == (Field*)0)
         {
@@ -3617,11 +3617,28 @@ bool check_grant(THD *thd, ulong want_access, TABLE_LIST *tables,
 }
 
 
+/*
+  Check column rights in given security context
+
+  SYNOPSIS
+    check_grant_column()
+    thd                  thread handler
+    grant                grant information structure
+    db_name              db name
+    table_name           table  name
+    name                 column name
+    length               column name length
+    sctx                 security context
+
+  RETURN
+    FALSE OK
+    TRUE  access denied
+*/
+
 bool check_grant_column(THD *thd, GRANT_INFO *grant,
 			const char *db_name, const char *table_name,
-			const char *name, uint length, uint show_tables)
+			const char *name, uint length,  Security_context *sctx)
 {
-  Security_context *sctx= thd->security_ctx;
   GRANT_TABLE *grant_table;
   GRANT_COLUMN *grant_column;
   ulong want_access= grant->want_privilege & ~grant->privilege;
@@ -3652,28 +3669,74 @@ bool check_grant_column(THD *thd, GRANT_INFO *grant,
     rw_unlock(&LOCK_grant);
     DBUG_RETURN(0);
   }
-#ifdef NOT_USED
-  if (show_tables && (grant_column || grant->privilege & COL_ACLS))
-  {
-    rw_unlock(&LOCK_grant);			/* purecov: deadcode */
-    DBUG_RETURN(0);				/* purecov: deadcode */
-  }
-#endif
 
 err:
   rw_unlock(&LOCK_grant);
-  if (!show_tables)
+  char command[128];
+  get_privilege_desc(command, sizeof(command), want_access);
+  my_error(ER_COLUMNACCESS_DENIED_ERROR, MYF(0),
+           command,
+           sctx->priv_user,
+           sctx->host_or_ip,
+           name,
+           table_name);
+  DBUG_RETURN(1);
+}
+
+
+/*
+  Check the access right to a column depending on the type of table.
+
+  SYNOPSIS
+    check_column_grant_in_table_ref()
+    thd              thread handler
+    table_ref        table reference where to check the field
+    name             name of field to check
+    length           length of name
+
+  DESCRIPTION
+    Check the access rights to a column depending on the type of table
+    reference where the column is checked. The function provides a
+    generic interface to check column access rights that hides the
+    heterogeneity of the column representation - whether it is a view
+    or a stored table colum.
+
+  RETURN
+    FALSE OK
+    TRUE  access denied
+*/
+
+bool check_column_grant_in_table_ref(THD *thd, TABLE_LIST * table_ref,
+                                     const char *name, uint length)
+{
+  GRANT_INFO *grant;
+  const char *db_name;
+  const char *table_name;
+  Security_context *sctx= test(table_ref->security_ctx) ?
+                          table_ref->security_ctx : thd->security_ctx;
+
+  if (table_ref->view || table_ref->field_translation)
   {
-    char command[128];
-    get_privilege_desc(command, sizeof(command), want_access);
-    my_error(ER_COLUMNACCESS_DENIED_ERROR, MYF(0),
-             command,
-             sctx->priv_user,
-             sctx->host_or_ip,
-             name,
-             table_name);
+    /* View or derived information schema table. */
+    grant= &(table_ref->grant);
+    db_name= table_ref->view_db.str;
+    table_name= table_ref->view_name.str;
   }
-  DBUG_RETURN(1);
+  else
+  {
+    /* Normal or temporary table. */
+    TABLE *table= table_ref->table;
+    grant= &(table->grant);
+    db_name= table->s->db;
+    table_name= table->s->table_name;
+  }
+
+  if (grant->want_privilege)
+    return check_grant_column(thd, grant, db_name, table_name, name,
+                              length, sctx);
+  else
+    return FALSE;
+
 }
 
 

sql/sql_acl.h

@@ -204,7 +204,9 @@ bool check_grant(THD *thd, ulong want_access, TABLE_LIST *tables,
 		 uint show_command, uint number, bool dont_print_error);
 bool check_grant_column (THD *thd, GRANT_INFO *grant,
 			 const char *db_name, const char *table_name,
-			 const char *name, uint length, uint show_command=0);
+			 const char *name, uint length, Security_context *sctx);
+bool check_column_grant_in_table_ref(THD *thd, TABLE_LIST * table_ref,
+                                     const char *name, uint length);
 bool check_grant_all_columns(THD *thd, ulong want_access, GRANT_INFO *grant,
                              const char* db_name, const char *table_name,
                              Field_iterator *fields);

sql/table.cc

@@ -2606,60 +2606,6 @@ GRANT_INFO *Natural_join_column::grant()
 }
 
 
-
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-
-/*
-  Check the access rights for the current join column.
-  columns.
-
-  SYNOPSIS
-    Natural_join_column::check_grants()
-
-  DESCRIPTION
-    Check the access rights to a column from a natural join in a generic
-    way that hides the heterogeneity of the column representation - whether
-    it is a view or a stored table colum.
-
-  RETURN
-    FALSE  The column can be accessed
-    TRUE   There are no access rights to all equivalent columns
-*/
-
-bool
-Natural_join_column::check_grants(THD *thd, const char *name, uint length)
-{
-  GRANT_INFO *grant;
-  const char *db_name;
-  const char *table_name;
-  Security_context *save_security_ctx= thd->security_ctx;
-  Security_context *new_sctx= table_ref->security_ctx;
-  bool res;
-
-  if (view_field)
-  {
-    DBUG_ASSERT(table_field == NULL);
-    grant= &(table_ref->grant);
-    db_name= table_ref->view_db.str;
-    table_name= table_ref->view_name.str;
-  }
-  else
-  {
-    DBUG_ASSERT(table_field && view_field == NULL);
-    grant= &(table_ref->table->grant);
-    db_name= table_ref->table->s->db;
-    table_name= table_ref->table->s->table_name;
-  }
-
-  if (new_sctx)
-    thd->security_ctx= new_sctx;
-  res= check_grant_column(thd, grant, db_name, table_name, name, length);
-  thd->security_ctx= save_security_ctx;
-  return res;
-}
-#endif
-
-
 void Field_iterator_view::set(TABLE_LIST *table)
 {
   DBUG_ASSERT(table->field_translation);

sql/table.h

@@ -407,9 +407,6 @@ class Natural_join_column: public Sql_alloc
   const char *table_name();
   const char *db_name();
   GRANT_INFO *grant();
-#ifndef NO_EMBEDDED_ACCESS_CHECKS
-  bool check_grants(THD *thd, const char *name, uint length);
-#endif
 };