Bug#7391 - Multi-table UPDATE security regression

  Add in missing privilege checks. 
  Tests for the privileges.


mysql-test/r/grant.result:
  Bug#7391 - Multi-table UPDATE security regression
    Tests column, table and db level access
mysql-test/t/grant.test:
  Bug#7391 - Multi-table UPDATE security regression
    Tests column, table and db level access
sql/sql_update.cc:
  Bug#7391 - Multi-table UPDATE security regression
    Add in missing privilege checks.

3 files changed, 156 insertions, 0 deletions

diff --git a/mysql-test/r/grant.result b/mysql-test/r/grant.result
index f0e5d16e916..2a433e3d5db 100644
--- a/mysql-test/r/grant.result
+++ b/mysql-test/r/grant.result
@@ -156,3 +156,67 @@ select host,db,user,select_priv,insert_priv from mysql.db where db="db6123";
 host	db	user	select_priv	insert_priv
 delete from mysql.user where user='test6123';
 drop database db6123;
+create database mysqltest_1;
+create database mysqltest_2;
+create table mysqltest_1.t1 select 1 a, 2 q;
+create table mysqltest_1.t2 select 1 b, 2 r;
+create table mysqltest_2.t1 select 1 c, 2 s;
+create table mysqltest_2.t2 select 1 d, 2 t;
+grant update (a) on mysqltest_1.t1 to mysqltest_3@localhost;
+grant select (b) on mysqltest_1.t2 to mysqltest_3@localhost;
+grant select (c) on mysqltest_2.t1 to mysqltest_3@localhost;
+grant update (d) on mysqltest_2.t2 to mysqltest_3@localhost;
+show grants for mysqltest_3@localhost;
+Grants for mysqltest_3@localhost
+GRANT USAGE ON *.* TO 'mysqltest_3'@'localhost'
+GRANT SELECT (b) ON `mysqltest_1`.`t2` TO 'mysqltest_3'@'localhost'
+GRANT SELECT (c) ON `mysqltest_2`.`t1` TO 'mysqltest_3'@'localhost'
+GRANT UPDATE (a) ON `mysqltest_1`.`t1` TO 'mysqltest_3'@'localhost'
+GRANT UPDATE (d) ON `mysqltest_2`.`t2` TO 'mysqltest_3'@'localhost'
+update mysqltest_1.t1, mysqltest_1.t2 set q=10 where b=1;
+UPDATE command denied to user: 'mysqltest_3@localhost' for column 'q' in table 't1'
+update mysqltest_1.t1, mysqltest_2.t2 set d=20 where d=1;
+select command denied to user: 'mysqltest_3@localhost' for table 't1'
+update mysqltest_2.t1, mysqltest_1.t2 set c=20 where b=1;
+UPDATE command denied to user: 'mysqltest_3@localhost' for column 'c' in table 't1'
+update mysqltest_2.t1, mysqltest_2.t2 set d=10 where s=2;
+SELECT command denied to user: 'mysqltest_3@localhost' for column 's' in table 't1'
+update mysqltest_1.t1, mysqltest_2.t2 set a=10,d=10;
+update mysqltest_1.t1, mysqltest_2.t1 set a=20 where c=20;
+select t1.*,t2.* from mysqltest_1.t1,mysqltest_1.t2;
+a	q	b	r
+10	2	1	2
+select t1.*,t2.* from mysqltest_2.t1,mysqltest_2.t2;
+c	s	d	t
+1	2	10	2
+revoke all on mysqltest_1.t1 from mysqltest_3@localhost;
+revoke all on mysqltest_1.t2 from mysqltest_3@localhost;
+revoke all on mysqltest_2.t1 from mysqltest_3@localhost;
+revoke all on mysqltest_2.t2 from mysqltest_3@localhost;
+grant all on mysqltest_2.* to mysqltest_3@localhost;
+grant select on *.* to mysqltest_3@localhost;
+flush privileges;
+use mysqltest_1;
+update mysqltest_2.t1, mysqltest_2.t2 set c=500,d=600;
+update mysqltest_1.t1, mysqltest_1.t2 set a=100,b=200;
+UPDATE command denied to user: 'mysqltest_3@localhost' for column 'a' in table 't1'
+use mysqltest_2;
+update mysqltest_1.t1, mysqltest_1.t2 set a=100,b=200;
+Access denied for user: 'mysqltest_3@localhost' to database 'mysqltest_1'
+update mysqltest_2.t1, mysqltest_1.t2 set c=100,b=200;
+Access denied for user: 'mysqltest_3@localhost' to database 'mysqltest_1'
+update mysqltest_1.t1, mysqltest_2.t2 set a=100,d=200;
+Access denied for user: 'mysqltest_3@localhost' to database 'mysqltest_1'
+select t1.*,t2.* from mysqltest_1.t1,mysqltest_1.t2;
+a	q	b	r
+10	2	1	2
+select t1.*,t2.* from mysqltest_2.t1,mysqltest_2.t2;
+c	s	d	t
+500	2	600	2
+delete from mysql.user where user='mysqltest_3';
+delete from mysql.db where user="mysqltest_3";
+delete from mysql.tables_priv where user="mysqltest_3";
+delete from mysql.columns_priv where user="mysqltest_3";
+flush privileges;
+drop database mysqltest_1;
+drop database mysqltest_2;
diff --git a/mysql-test/t/grant.test b/mysql-test/t/grant.test
index 21173a356ce..d9b4be04de3 100644
--- a/mysql-test/t/grant.test
+++ b/mysql-test/t/grant.test
@@ -2,6 +2,8 @@
 drop table if exists t1;
 --enable_warnings
 
+connect (master,localhost,root,,);
+connection master;
 #
 # Test that SSL options works properly
 #
@@ -114,3 +116,73 @@ grant usage on db6123.* to test6123 identified by 'magic123';
 select host,db,user,select_priv,insert_priv from mysql.db where db="db6123";
 delete from mysql.user where user='test6123';
 drop database db6123;
+
+#
+# Bug#7391: Cross-database multi-table UPDATE security problem
+#
+create database mysqltest_1;
+create database mysqltest_2;
+create table mysqltest_1.t1 select 1 a, 2 q;
+create table mysqltest_1.t2 select 1 b, 2 r;
+create table mysqltest_2.t1 select 1 c, 2 s;
+create table mysqltest_2.t2 select 1 d, 2 t;
+
+#test the column privileges
+grant update (a) on mysqltest_1.t1 to mysqltest_3@localhost;
+grant select (b) on mysqltest_1.t2 to mysqltest_3@localhost;
+grant select (c) on mysqltest_2.t1 to mysqltest_3@localhost;
+grant update (d) on mysqltest_2.t2 to mysqltest_3@localhost;
+connect (conn1,localhost,mysqltest_3,,);
+connection conn1;
+show grants for mysqltest_3@localhost;
+--error 1143
+update mysqltest_1.t1, mysqltest_1.t2 set q=10 where b=1;
+--error 1142
+update mysqltest_1.t1, mysqltest_2.t2 set d=20 where d=1;
+--error 1143
+update mysqltest_2.t1, mysqltest_1.t2 set c=20 where b=1;
+--error 1143
+update mysqltest_2.t1, mysqltest_2.t2 set d=10 where s=2;
+#the following two should work
+update mysqltest_1.t1, mysqltest_2.t2 set a=10,d=10;
+update mysqltest_1.t1, mysqltest_2.t1 set a=20 where c=20;
+connection master;
+select t1.*,t2.* from mysqltest_1.t1,mysqltest_1.t2;
+select t1.*,t2.* from mysqltest_2.t1,mysqltest_2.t2;
+revoke all on mysqltest_1.t1 from mysqltest_3@localhost;
+revoke all on mysqltest_1.t2 from mysqltest_3@localhost;
+revoke all on mysqltest_2.t1 from mysqltest_3@localhost;
+revoke all on mysqltest_2.t2 from mysqltest_3@localhost;
+
+#test the db/table level privileges
+grant all on mysqltest_2.* to mysqltest_3@localhost;
+grant select on *.* to mysqltest_3@localhost;
+flush privileges;
+disconnect conn1;
+connect (conn2,localhost,mysqltest_3,,);
+connection conn2;
+use mysqltest_1;
+update mysqltest_2.t1, mysqltest_2.t2 set c=500,d=600;
+# the following failed before, should fail now.
+--error 1143
+update mysqltest_1.t1, mysqltest_1.t2 set a=100,b=200;
+use mysqltest_2;
+#the following used to succeed, it must fail now.
+--error 1044
+update mysqltest_1.t1, mysqltest_1.t2 set a=100,b=200;
+--error 1044
+update mysqltest_2.t1, mysqltest_1.t2 set c=100,b=200;
+--error 1044
+update mysqltest_1.t1, mysqltest_2.t2 set a=100,d=200;
+#lets see the result
+connection master;
+select t1.*,t2.* from mysqltest_1.t1,mysqltest_1.t2;
+select t1.*,t2.* from mysqltest_2.t1,mysqltest_2.t2;
+
+delete from mysql.user where user='mysqltest_3';
+delete from mysql.db where user="mysqltest_3";
+delete from mysql.tables_priv where user="mysqltest_3";
+delete from mysql.columns_priv where user="mysqltest_3";
+flush privileges;
+drop database mysqltest_1;
+drop database mysqltest_2;
diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index cdcc90e8651..f7355f2e9b6 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -465,21 +465,34 @@ int mysql_multi_update(THD *thd,
     */
     for (tl= table_list ; tl ; tl=tl->next)
     {
+      TABLE_LIST *save= tl->next;
       TABLE *table= tl->table;
+      uint wants;
+      tl->next= 0;
       if (update_map & table->map) 
       {
 	DBUG_PRINT("info",("setting table `%s` for update", tl->alias));
 	tl->lock_type= thd->lex.lock_option;
 	tl->updating= 1;
+	wants= UPDATE_ACL;
       }
       else
       {
 	DBUG_PRINT("info",("setting table `%s` for read-only", tl->alias));
 	tl->lock_type= TL_READ;
 	tl->updating= 0;
+	wants= SELECT_ACL;
       }
       if (!using_lock_tables)
 	tl->table->reginfo.lock_type= tl->lock_type;
+
+      if (check_access(thd, wants, tl->db, &tl->grant.privilege, 0, 0) ||
+          (grant_option && check_grant(thd, wants, tl, 0, 0)))
+      {
+	tl->next= save;
+	DBUG_RETURN(0);
+      }
+      tl->next= save;
     }
 
     /* Relock the tables with the correct modes */
@@ -541,6 +554,13 @@ int mysql_multi_update(THD *thd,
     }
   }
 
+  /*
+    If we have no WHERE clause, make it true otherwise the Select
+    examines the privileges
+  */
+  if (!conds)
+    conds= new Item_int("1", 1LL, 1);
+  
   if (!(result=new multi_update(thd, table_list, fields, values,
 				handle_duplicates)))
     DBUG_RETURN(-1);