Bug#32091: Security breach via directory changes

Problem: the table's INDEX and DATA DIR was taken
  directly from the table's first partition.
  This allowed rename attack similar to
  bug#32111 when ALTER TABLE REMOVE PARTITIONING

Solution: Silently ignore the INDEX/DATA DIR
  for the table. (Like some other storage engines
  do). 
  Partitioned tables do not support DATA/INDEX
  DIR on the table level, only on its partitions.


mysql-test/r/partition_mgm.result:
  Bug#32091: Security breach via directory changes
  test result
mysql-test/t/partition_mgm.test:
  Bug#32091: Security breach via directory changes
  test case
sql/ha_partition.cc:
  Bug#32091: Security breach via directory changes
  
  Do not use the first partition's DATA/INDEX DIR
  as the table's DATA/INDEX DIR.
  (A partitioned table do not have support for DATA/
  INDEX DIR, only its partitions do)

2 files changed, 192 insertions, 2 deletions

diff --git a/mysql-test/r/partition_mgm.result b/mysql-test/r/partition_mgm.result
index 04ac603fea7..7d2c159bb15 100644
--- a/mysql-test/r/partition_mgm.result
+++ b/mysql-test/r/partition_mgm.result
@@ -1,4 +1,85 @@
 DROP TABLE IF EXISTS t1;
+# Creating two non colliding tables mysqltest2.t1 and test.t1
+# test.t1 have partitions in mysqltest2-directory!
+# user root:
+GRANT USAGE ON test.* TO mysqltest_1@localhost;
+CREATE DATABASE mysqltest2;
+USE mysqltest2;
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (0);
+# user mysqltest_1:
+USE test;
+CREATE TABLE t1 (a INT)
+PARTITION BY LIST (a) (
+PARTITION p0 VALUES IN (0)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2',
+PARTITION p1 VALUES IN (1)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/test',
+PARTITION p2 VALUES IN (2)
+);
+# without the patch for bug#32091 this would create
+# files mysqltest2/t1.MYD + .MYI and possible overwrite
+# the mysqltest2.t1 table (depending on bug#32111)
+ALTER TABLE t1 REMOVE PARTITIONING;
+INSERT INTO t1 VALUES (1);
+SELECT * FROM t1;
+a
+1
+# user root:
+USE mysqltest2;
+FLUSH TABLES;
+# if the patch works, this should be different
+# and before the patch they were the same!
+SELECT * FROM t1;
+a
+0
+USE test;
+SELECT * FROM t1;
+a
+1
+DROP TABLE t1;
+DROP DATABASE mysqltest2;
+# test that symlinks can not overwrite files when CREATE TABLE
+# user root:
+CREATE DATABASE mysqltest2;
+USE mysqltest2;
+CREATE TABLE t1 (a INT)
+PARTITION BY LIST (a) (
+PARTITION p0 VALUES IN (0)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2',
+PARTITION p1 VALUES IN (1)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+   );
+# user mysqltest_1:
+USE test;
+CREATE TABLE t1 (a INT)
+PARTITION BY LIST (a) (
+PARTITION p0 VALUES IN (0)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2',
+PARTITION p1 VALUES IN (1)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+   );
+ERROR HY000: Can't create/write to file 'MYSQLTEST_VARDIR/master-data/mysqltest2/t1#P#p0.MYI' (Errcode: 17)
+CREATE TABLE t1 (a INT)
+PARTITION BY LIST (a) (
+PARTITION p0 VALUES IN (0)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/test',
+PARTITION p1 VALUES IN (1)
+DATA DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY 'MYSQLTEST_VARDIR/master-data/mysqltest2'
+  );
+ERROR HY000: Can't create/write to file 'MYSQLTEST_VARDIR/master-data/test/t1#P#p1.MYI' (Errcode: 17)
+# user root (cleanup):
+DROP DATABASE mysqltest2;
+USE test;
+REVOKE USAGE ON *.* FROM mysqltest_1@localhost;
 create table t1 (a int)
 partition by range (a)
 subpartition by key (a)
diff --git a/mysql-test/t/partition_mgm.test b/mysql-test/t/partition_mgm.test
index a06f8d1aee5..a405e15ec16 100644
--- a/mysql-test/t/partition_mgm.test
+++ b/mysql-test/t/partition_mgm.test
@@ -1,7 +1,116 @@
 -- source include/have_partition.inc
---disable_warnings
+-- disable_warnings
 DROP TABLE IF EXISTS t1;
---enable_warnings
+-- enable_warnings
+
+#
+# Bug 32091: Security breach via directory changes
+#
+# The below test shows that a pre-existing table mysqltest2.t1 cannot be
+# replaced by a user with no rights in 'mysqltest2'. The altered table
+# test.t1 will be altered (remove partitioning) into the test directory
+# and having its partitions removed from the mysqltest2 directory.
+# (the partitions data files are named <tablename>#P#<partname>.MYD
+# and will not collide with a non partitioned table's data files.) 
+# NOTE: the privileges on files and directories are the same for all
+# database users in mysqld, though mysqld enforces privileges on
+# the database and table levels which in turn maps to directories and
+# files, but not the other way around (any db-user can use any
+# directory or file that the mysqld-process can use, via DATA/INDEX DIR)
+# this is the security flaw that was used in bug#32091 and bug#32111
+-- echo # Creating two non colliding tables mysqltest2.t1 and test.t1
+-- echo # test.t1 have partitions in mysqltest2-directory!
+-- echo # user root:
+  GRANT USAGE ON test.* TO mysqltest_1@localhost;
+  CREATE DATABASE mysqltest2;
+  USE mysqltest2;
+  CREATE TABLE t1 (a INT);
+  INSERT INTO t1 VALUES (0);
+connect(con1,localhost,mysqltest_1,,);
+-- echo # user mysqltest_1:
+  USE test;
+  -- replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+  eval CREATE TABLE t1 (a INT)
+   PARTITION BY LIST (a) (
+    PARTITION p0 VALUES IN (0)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2',
+    PARTITION p1 VALUES IN (1)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/test',
+    PARTITION p2 VALUES IN (2)
+  );
+  -- echo # without the patch for bug#32091 this would create
+  -- echo # files mysqltest2/t1.MYD + .MYI and possible overwrite
+  -- echo # the mysqltest2.t1 table (depending on bug#32111)
+  -- replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+  ALTER TABLE t1 REMOVE PARTITIONING;
+  INSERT INTO t1 VALUES (1);
+  SELECT * FROM t1;
+connection default;
+-- echo # user root:
+  USE mysqltest2;
+  FLUSH TABLES;
+  -- echo # if the patch works, this should be different
+  -- echo # and before the patch they were the same!
+  SELECT * FROM t1;
+  USE test;
+  SELECT * FROM t1;
+  DROP TABLE t1;
+  DROP DATABASE mysqltest2;
+# The below test shows that a pre-existing partition can not be
+# destroyed by a new partition from another table.
+# (Remember that a table or partition that uses the DATA/INDEX DIR
+# is symlinked and thus has
+# 1. the real file in the DATA/INDEX DIR and
+# 2. a symlink in its default database directory pointing to
+# the real file.
+# So it is using/blocking 2 files in (in 2 different directories
+-- echo # test that symlinks can not overwrite files when CREATE TABLE
+-- echo # user root:
+  CREATE DATABASE mysqltest2;
+  USE mysqltest2;
+  -- replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+  eval CREATE TABLE t1 (a INT)
+   PARTITION BY LIST (a) (
+    PARTITION p0 VALUES IN (0)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2',
+    PARTITION p1 VALUES IN (1)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+   );
+connection con1;
+-- echo # user mysqltest_1:
+  USE test;
+  -- replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+  -- error 1
+  eval CREATE TABLE t1 (a INT)
+   PARTITION BY LIST (a) (
+    PARTITION p0 VALUES IN (0)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2',
+    PARTITION p1 VALUES IN (1)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+   );
+  -- replace_result $MYSQLTEST_VARDIR MYSQLTEST_VARDIR
+  -- error 1
+  eval CREATE TABLE t1 (a INT)
+   PARTITION BY LIST (a) (
+    PARTITION p0 VALUES IN (0)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/test'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/test',
+    PARTITION p1 VALUES IN (1)
+     DATA DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2'
+     INDEX DIRECTORY '$MYSQLTEST_VARDIR/master-data/mysqltest2'
+  );
+connection default;
+-- echo # user root (cleanup):
+  DROP DATABASE mysqltest2;
+  USE test;
+  REVOKE USAGE ON *.* FROM mysqltest_1@localhost;
+  disconnect con1;
 
 #
 # Bug 21143: mysqld hang when error in number of subparts in