fix for bug #17289 Events: missing privilege check for drop database

Events were executed with all privileges possible on planet Earth :(
WL#1034


mysql-test/r/events.result:
  update test results
mysql-test/t/events.test:
  test for bug#17289 Events: missing privilege check for drop database
sql/event.h:
  -add two new methods to event_timed to change and restore
   the security context
sql/event_executor.cc:
  - move code regarding privilieges checking to event_timed::execute()
  - add a new function evex_print_warnings() which prints the notes/warnings/errors
    to the console (easily capturable with logs-into-tables) so one can see what
    has happened if there was an error of some sort!
sql/event_timed.cc:
  - fix documentation
  - add a new error code -99, EVENT was revoked from the user on the DB
  - set_sec_ctx, execute, restore_sex_ctx
sql/sql_error.cc:
  - make warning_level_names public to be used in event_executor.cc
  - change from 2 arrays to a LEX_STRING array

mysql-test/r/events.result

 create database if not exists events_test;
 use events_test;
+CREATE USER pauline@localhost;
+CREATE DATABASE db_x;
+GRANT EVENT ON db_x.* TO pauline@localhost;
+USE db_x;
+CREATE TABLE x_table(a int);
+CREATE EVENT e_x1 ON SCHEDULE EVERY 1 SECOND DO DROP DATABASE db_x;
+CREATE EVENT e_x2 ON SCHEDULE EVERY 1 SECOND DO DROP TABLE x_table;
+SHOW DATABASES LIKE 'db_x';
+Database (db_x)
+db_x
+SET GLOBAL event_scheduler=1;
+SHOW DATABASES LIKE 'db_x';
+Database (db_x)
+db_x
+SHOW TABLES FROM db_x;
+Tables_in_db_x
+x_table
+SET GLOBAL event_scheduler=0;
+DROP EVENT e_x1;
+DROP EVENT e_x2;
+DROP DATABASE db_x;
+DROP USER pauline@localhost;
+USE events_test;
 drop event if exists event1;
 Warnings:
 Note	1305	Event event1 does not exist
@@ -166,7 +189,7 @@ show processlist;
 Id	User	Host	db	Command	Time	State	Info
 #	root	localhost	events_test	Query	#	NULL	show processlist
 #	event_scheduler		NULL	Connect	#	Sleeping	NULL
-#	root		events_test	Connect	#	User lock	select get_lock("test_lock2", 20)
+#	root	localhost	events_test	Connect	#	User lock	select get_lock("test_lock2", 20)
 "Release the mutex, the event worker should finish."
 select release_lock("test_lock2");
 release_lock("test_lock2")
@@ -184,6 +207,8 @@ set global event_scheduler=0;
 show processlist;
 Id	User	Host	db	Command	Time	State	Info
 #	root	localhost	events_test	Query	#	NULL	show processlist
+#	event_scheduler		NULL	Connect	#	Sleeping	NULL
+#	root	localhost	events_test	Connect	#	User lock	select get_lock("test_lock2_1", 20)
 "Release the lock so the child process should finish. Hence the scheduler also"
 select release_lock("test_lock2_1");
 release_lock("test_lock2_1")

mysql-test/t/events.test

 create database if not exists events_test;
 use events_test;
+
+#
+# START:  BUG #17289 Events: missing privilege check for drop database
+#
+CREATE USER pauline@localhost;
+CREATE DATABASE db_x;
+GRANT EVENT ON db_x.* TO pauline@localhost;
+USE db_x;
+CREATE TABLE x_table(a int);
+connect (priv_conn,localhost,pauline,,db_x);
+CREATE EVENT e_x1 ON SCHEDULE EVERY 1 SECOND DO DROP DATABASE db_x;
+CREATE EVENT e_x2 ON SCHEDULE EVERY 1 SECOND DO DROP TABLE x_table;
+connection default;
+SHOW DATABASES LIKE 'db_x';
+SET GLOBAL event_scheduler=1;
+--sleep 2
+SHOW DATABASES LIKE 'db_x';
+SHOW TABLES FROM db_x;
+SET GLOBAL event_scheduler=0;
+--sleep 1
+connection priv_conn;
+DROP EVENT e_x1;
+DROP EVENT e_x2;
+disconnect priv_conn;
+connection default;
+DROP DATABASE db_x;
+DROP USER pauline@localhost;
+USE events_test;
+--sleep 1
+#
+# END:    BUG #17289 Events: missing privilege check for drop database
+#
+
 drop event if exists event1;
 create event event1 on schedule every 15 minute starts now() ends date_add(now(), interval 5 hour) DO begin end;
 alter event event1 rename to event2 enable;

sql/event.h

@@ -203,6 +203,12 @@ class event_timed
     delete sphead;
     sphead= 0;
   }
+protected:
+  bool
+  change_security_context(THD *thd, Security_context **backup);
+
+  void
+  restore_security_context(THD *thd, Security_context *backup);
 };
 
 

sql/event_executor.cc

@@ -49,7 +49,8 @@ static uint workers_count;
 static int
 evex_load_events_from_db(THD *thd);
 
-
+bool
+evex_print_warnings(THD *thd, event_timed *et);
 
 /*
   TODO Andrey: Check for command line option whether to start
@@ -135,7 +136,8 @@ init_event_thread(THD* thd)
 {
   DBUG_ENTER("init_event_thread");
   thd->client_capabilities= 0;
-  thd->security_ctx->skip_grants();
+  thd->security_ctx->master_access= 0;
+  thd->security_ctx->db_access= 0;
   thd->security_ctx->host= (char*)my_localhost;
   my_net_init(&thd->net, 0);
   thd->net.read_timeout = slave_net_timeout;
@@ -204,7 +206,7 @@ event_executor_main(void *arg)
 
   if (init_event_thread(thd))
     goto err;
-  
+  thd->security_ctx->skip_grants();
   // make this thread invisible it has no vio -> show processlist won't see
   thd->system_thread= 1;
 
@@ -481,21 +483,8 @@ event_executor_worker(void *event_void)
   thd= current_thd;
 #endif
 
-  // thd->security_ctx->priv_host is char[MAX_HOSTNAME]
-  
-  strxnmov(thd->security_ctx->priv_host, sizeof(thd->security_ctx->priv_host),
-                event->definer_host.str, NullS);  
-
-  thd->security_ctx->user= thd->security_ctx->priv_user=
-                             my_strdup(event->definer_user.str, MYF(0));
-
-  thd->db= event->dbname.str;
-  if (!check_access(thd, EVENT_ACL, event->dbname.str, 0, 0, 0,
-                      is_schema_db(event->dbname.str)))
   {
     int ret;
-    DBUG_PRINT("info", ("    EVEX EXECUTING event %s.%s [EXPR:%d]",
-               event->dbname.str, event->name.str,(int) event->expression));
     sql_print_information("    EVEX EXECUTING event %s.%s [EXPR:%d]",
                event->dbname.str, event->name.str,(int) event->expression);
 
@@ -507,10 +496,7 @@ event_executor_worker(void *event_void)
     if (ret == EVEX_COMPILE_ERROR)
       sql_print_information("    EVEX COMPILE ERROR for event %s.%s",
                              event->dbname.str, event->name.str);
-    
-    DBUG_PRINT("info", ("    EVEX EXECUTED event %s.%s  [EXPR:%d]. RetCode=%d",
-                        event->dbname.str, event->name.str,
-                        (int) event->expression, ret));
+    evex_print_warnings(thd, event);
   }
   if ((event->flags & EVENT_EXEC_NO_MORE) || event->status==MYSQL_EVENT_DISABLED)
   {
@@ -521,7 +507,6 @@ event_executor_worker(void *event_void)
     delete event;
   }
 
-  thd->db= 0;
 
 err:
   VOID(pthread_mutex_lock(&LOCK_thread_count));
@@ -666,3 +651,62 @@ bool sys_var_event_executor::update(THD *thd, set_var *var)
   DBUG_RETURN(0);
 }
 
+extern LEX_STRING warning_level_names[];
+
+/*
+  Prints the stack of infos, warnings, errors from thd to
+  the console so it can be fetched by the logs-into-tables and
+  checked later.
+  
+  Synopsis
+    evex_print_warnings
+      thd    - thread used during the execution of the event
+      et     - the event itself
+  
+  Returns
+    0 - OK (always)   
+
+*/
+
+bool
+evex_print_warnings(THD *thd, event_timed *et)
+{  
+  MYSQL_ERROR *err;
+  DBUG_ENTER("evex_show_warnings");
+  char msg_buf[1024];
+  char prefix_buf[512];
+  String prefix(prefix_buf, sizeof(prefix_buf), system_charset_info);
+  prefix.length(0);
+  
+  List_iterator_fast<MYSQL_ERROR> it(thd->warn_list);
+  while ((err= it++))
+  {
+    String err_msg(msg_buf, sizeof(msg_buf), system_charset_info);
+    err_msg.length(0);// set it to 0 or we start adding at the end
+    if (!prefix.length())
+    {
+      prefix.append("SCHEDULER: [");
+
+      append_identifier(thd,&prefix,et->definer_user.str,et->definer_user.length);
+      prefix.append('@');
+      append_identifier(thd,&prefix,et->definer_host.str,et->definer_host.length);
+      prefix.append("][", 2);
+      append_identifier(thd,&prefix, et->dbname.str, et->dbname.length);
+      prefix.append('.');
+      append_identifier(thd,&prefix, et->name.str, et->name.length);
+      prefix.append("] ", 2);
+    }
+    
+    err_msg.append(prefix);
+    err_msg.append('[');
+    err_msg.append(warning_level_names[err->level].str,
+                   warning_level_names[err->level].length, system_charset_info);
+    err_msg.append("] [");
+    err_msg.append(err->msg, strlen(err->msg), system_charset_info);
+    err_msg.append("]");
+    sql_print_information("%*s", err_msg.length(), err_msg.c_ptr());
+  }
+
+
+  DBUG_RETURN(FALSE);
+}

sql/event_timed.cc

@@ -982,12 +982,13 @@ event_timed::get_show_create_event(THD *thd, uint32 *length)
    Executes the event (the underlying sp_head object);
 
    SYNOPSIS
-     evex_fill_row()
+     event_timed::execute()
        thd    THD
        mem_root  If != NULL use it to compile the event on it
 
    Returns 
           0  - success
+        -99  - No access to the database.
        -100  - event in execution (parallel execution is impossible)
       others - retcodes of sp_head::execute_procedure()
       
@@ -996,10 +997,12 @@ event_timed::get_show_create_event(THD *thd, uint32 *length)
 int
 event_timed::execute(THD *thd, MEM_ROOT *mem_root)
 {
-  List<Item> empty_item_list;
+  Security_context *save_ctx;
   int ret= 0;
    
   DBUG_ENTER("event_timed::execute");
+  DBUG_PRINT("info", ("    EVEX EXECUTING event %s.%s [EXPR:%d]",
+               dbname.str, name.str, (int) expression));
 
   VOID(pthread_mutex_lock(&this->LOCK_running));
   if (running) 
@@ -1011,12 +1014,35 @@ event_timed::execute(THD *thd, MEM_ROOT *mem_root)
   VOID(pthread_mutex_unlock(&this->LOCK_running));
 
   // TODO Andrey : make this as member variable and delete in destructor
-  empty_item_list.empty();
   
   if (!sphead && (ret= compile(thd, mem_root)))
     goto done;
   
-  ret= sphead->execute_procedure(thd, &empty_item_list);
+  thd->db= dbname.str;
+  thd->db_length= dbname.length;
+
+  DBUG_PRINT("info", ("master_access=%d db_access=%d",
+             thd->security_ctx->master_access, thd->security_ctx->db_access));
+  change_security_context(thd, &save_ctx);
+  DBUG_PRINT("info", ("master_access=%d db_access=%d",
+             thd->security_ctx->master_access, thd->security_ctx->db_access));
+//  if (mysql_change_db(thd, dbname.str, 0))
+  if (!check_access(thd, EVENT_ACL,dbname.str, 0, 0, 0,is_schema_db(dbname.str)))
+  {
+    List<Item> empty_item_list;
+    empty_item_list.empty();
+    ret= sphead->execute_procedure(thd, &empty_item_list);
+  }
+  else
+  {
+    DBUG_PRINT("error", ("%s@%s has no rights on %s", definer_user.str,
+               definer_host.str, dbname.str));
+    ret= -99;
+  }
+  restore_security_context(thd, save_ctx);
+  DBUG_PRINT("info", ("master_access=%d db_access=%d",
+             thd->security_ctx->master_access, thd->security_ctx->db_access));
+  thd->db= 0;
 
   VOID(pthread_mutex_lock(&this->LOCK_running));
   running= false;
@@ -1029,11 +1055,61 @@ event_timed::execute(THD *thd, MEM_ROOT *mem_root)
     delete sphead;
     sphead= 0;
   }
+  DBUG_PRINT("info", ("    EVEX EXECUTED event %s.%s  [EXPR:%d]. RetCode=%d",
+                      dbname.str, name.str, (int) expression, ret));
 
   DBUG_RETURN(ret);
 }
 
 
+/*
+  Switches the security context
+  Synopsis
+    event_timed::change_security_context()
+      thd    - thread
+      backup - where to store the old context 
+  
+  RETURN
+    0  - OK
+    1  - Error (generates error too)
+*/
+bool
+event_timed::change_security_context(THD *thd, Security_context **backup)
+{
+  DBUG_ENTER("event_timed::change_security_context");
+  DBUG_PRINT("info",("%s@%s@%s",definer_user.str,definer_host.str, dbname.str));
+  *backup= 0;
+  if (acl_getroot_no_password(&sphead->m_security_ctx, definer_user.str,
+                              definer_host.str, definer_host.str, dbname.str))
+  {
+    my_error(ER_NO_SUCH_USER, MYF(0), definer_user.str, definer_host.str);
+    DBUG_RETURN(TRUE);
+  }
+  *backup= thd->security_ctx;
+  thd->security_ctx= &sphead->m_security_ctx;
+
+  DBUG_RETURN(FALSE);
+}
+
+
+/*
+  Restores the security context
+  Synopsis
+    event_timed::restore_security_context()
+      thd    - thread
+      backup - switch to this context
+ */
+
+void
+event_timed::restore_security_context(THD *thd, Security_context *backup)
+{
+  DBUG_ENTER("event_timed::change_security_context");
+  if (backup)
+    thd->security_ctx= backup;
+  DBUG_VOID_RETURN;
+}
+
+
 /*
   Returns
                      0 - Success

sql/sql_error.cc

@@ -211,8 +211,13 @@ void push_warning_printf(THD *thd, MYSQL_ERROR::enum_warning_level level,
     TRUE  Error sending data to client
 */
 
-static const char *warning_level_names[]= {"Note", "Warning", "Error", "?"};
-static int warning_level_length[]= { 4, 7, 5, 1 };
+LEX_STRING warning_level_names[]=
+{
+  {(char*) STRING_WITH_LEN("Note")},
+  {(char*) STRING_WITH_LEN("Warning")},
+  {(char*) STRING_WITH_LEN("Error")},
+  {(char*) STRING_WITH_LEN("?")}
+};
 
 bool mysqld_show_warnings(THD *thd, ulong levels_to_show)
 {  
@@ -246,8 +251,8 @@ bool mysqld_show_warnings(THD *thd, ulong levels_to_show)
     if (idx > unit->select_limit_cnt)
       break;
     protocol->prepare_for_resend();
-    protocol->store(warning_level_names[err->level],
-		    warning_level_length[err->level], system_charset_info);
+    protocol->store(warning_level_names[err->level].str,
+		    warning_level_names[err->level].length, system_charset_info);
     protocol->store((uint32) err->code);
     protocol->store(err->msg, strlen(err->msg), system_charset_info);
     if (protocol->write())