Fix for BUG#27337: Privileges are not properly restored.

The problem was that THD::db_access variable was not restored after
database switch in stored-routine-execution code.

The fix is to restore THD::db_access in this case.

Unfortunately, this fix requires additional changes,
because in prepare_schema_table(), called on the parsing stage, we checked
privileges. That was wrong according to our design, but this flaw haven't
struck so far, because it was masked. All privilege checkings must be
done on the execution stage in order to be compatible with prepared statements
and stored routines. So, this patch also contains patch for
prepare_schema_table(), which moves the checkings to the execution phase.


mysql-test/r/grant.result:
  Updated result file.
mysql-test/t/grant.test:
  Added test case for BUG#27337.
sql/mysql_priv.h:
  Added function declaration.
sql/sql_db.cc:
  Fix for BUG#27337 -- set THD::db_access even if we're called
  from stored-routine-execution code.
sql/sql_parse.cc:
  Split prepare_schema_table() into two functions:
    - prepare_schema_table(), which is called from the parser (parsing stage);
    - check_show_access(), which is called on the execution stage.
sql/sql_show.cc:
  Ignore schema_select_lex member if its table is NULL.

1 files changed, 144 insertions, 0 deletions

diff --git a/mysql-test/t/grant.test b/mysql-test/t/grant.test
index 92ed69d3f4b..623bd4363cb 100644
--- a/mysql-test/t/grant.test
+++ b/mysql-test/t/grant.test
@@ -958,4 +958,148 @@ DROP DATABASE mysqltest4;
 DROP USER mysqltest_1@localhost;
 
 
+#
+# BUG#27337: Privileges are not restored properly.
+#
+# Actually, the patch for this bugs fixes two problems. So, here are two test
+# cases.
+
+# Test case 1: privileges are not restored properly after calling a stored
+# routine defined with SQL SECURITY INVOKER clause.
+
+# Prepare.
+
+--disable_warnings
+DROP DATABASE IF EXISTS mysqltest1;
+DROP DATABASE IF EXISTS mysqltest2;
+--enable_warnings
+
+CREATE DATABASE mysqltest1;
+CREATE DATABASE mysqltest2;
+
+GRANT ALL PRIVILEGES ON mysqltest1.* TO mysqltest_1@localhost;
+GRANT SELECT ON mysqltest2.* TO mysqltest_1@localhost;
+
+CREATE PROCEDURE mysqltest1.p1() SQL SECURITY INVOKER
+  SELECT 1;
+
+# Test.
+
+--connect (bug27337_con1,localhost,mysqltest_1,,mysqltest2)
+--echo
+--echo ---> connection: bug27337_con1
+
+--error ER_TABLEACCESS_DENIED_ERROR
+CREATE TABLE t1(c INT);
+
+CALL mysqltest1.p1();
+
+--error ER_TABLEACCESS_DENIED_ERROR
+CREATE TABLE t1(c INT);
+
+--disconnect bug27337_con1
+
+--connect (bug27337_con2,localhost,mysqltest_1,,mysqltest2)
+--echo
+--echo ---> connection: bug27337_con2
+
+--error ER_TABLEACCESS_DENIED_ERROR
+CREATE TABLE t1(c INT);
+
+SHOW TABLES;
+
+# Cleanup.
+
+--connection default
+--echo
+--echo ---> connection: default
+
+--disconnect bug27337_con2
+
+DROP DATABASE mysqltest1;
+DROP DATABASE mysqltest2;
+
+DROP USER mysqltest_1@localhost;
+
+# Test case 2: priveleges are not checked properly for prepared statements.
+
+# Prepare.
+
+--disable_warnings
+DROP DATABASE IF EXISTS mysqltest1;
+DROP DATABASE IF EXISTS mysqltest2;
+--enable_warnings
+
+CREATE DATABASE mysqltest1;
+CREATE DATABASE mysqltest2;
+
+CREATE TABLE mysqltest1.t1(c INT);
+CREATE TABLE mysqltest2.t2(c INT);
+
+GRANT SELECT ON mysqltest1.t1 TO mysqltest_1@localhost;
+GRANT SELECT ON mysqltest2.t2 TO mysqltest_2@localhost;
+
+# Test.
+
+--connect (bug27337_con1,localhost,mysqltest_1,,mysqltest1)
+--echo
+--echo ---> connection: bug27337_con1
+
+SHOW TABLES FROM mysqltest1;
+
+PREPARE stmt1 FROM 'SHOW TABLES FROM mysqltest1';
+
+EXECUTE stmt1;
+
+--connect (bug27337_con2,localhost,mysqltest_2,,mysqltest2)
+--echo
+--echo ---> connection: bug27337_con2
+
+SHOW COLUMNS FROM mysqltest2.t2;
+
+PREPARE stmt2 FROM 'SHOW COLUMNS FROM mysqltest2.t2';
+
+EXECUTE stmt2;
+
+--connection default
+--echo
+--echo ---> connection: default
+
+REVOKE SELECT ON mysqltest1.t1 FROM mysqltest_1@localhost;
+REVOKE SELECT ON mysqltest2.t2 FROM mysqltest_2@localhost;
+
+--connection bug27337_con1
+--echo
+--echo ---> connection: bug27337_con1
+
+--error ER_DBACCESS_DENIED_ERROR
+SHOW TABLES FROM mysqltest1;
+
+--error ER_DBACCESS_DENIED_ERROR
+EXECUTE stmt1;
+
+--connection bug27337_con2
+--echo
+--echo ---> connection: bug27337_con2
+
+--error ER_TABLEACCESS_DENIED_ERROR
+SHOW COLUMNS FROM mysqltest2.t2;
+
+--error ER_TABLEACCESS_DENIED_ERROR
+EXECUTE stmt2;
+
+# Cleanup.
+
+--connection default
+--echo
+--echo ---> connection: default
+
+--disconnect bug27337_con2
+
+DROP DATABASE mysqltest1;
+DROP DATABASE mysqltest2;
+
+DROP USER mysqltest_1@localhost;
+
+
 --echo End of 5.0 tests