Database Management Systems Design. Week 6 MySQL Project

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1 Database Management Systems Design Week 6 MySQL Project This week we will be looking at how we can control access to users and groups of users on databases, tables. I have attempted to limit coverage of SQL to ANSI standard SQL. Finally, we will look at how to use the MySQL Control Center that is specific to MySQL. We will be learning how to grant access to databases, tables to other users and groups of users. This may seem unnecessary with our localhost version of MySQL. The principles of how we grant access to these objects are standard as most databases are used in a multi-user environment. SQL refers to authority as the access rights a user has on a database. It refers to privilege as the access rights to a table or a view. Note that the syntax for granting privileges includes the with grant option. This means that a user can be granted access with the right to grant these privileges and only these privileges to other users. Browse the following on authority and study the section on privileges. The project for this week is at the end of this document. GRANT and REVOKE Syntax Note: Some of the following material is taken from the MySQL Manual. GRANT priv_type [(column_list)] [, priv_type [(column_list)]...] ON {tbl_name * *.* db_name.*} TO user_name [IDENTIFIED BY [PASSWORD] 'password'] [, user_name [IDENTIFIED BY [PASSWORD] 'password']...] [REQUIRE NONE [{SSL X509}] [CIPHER cipher [AND]] [ISSUER issuer [AND]] [SUBJECT subject]] [WITH [GRANT OPTION MAX_QUERIES_PER_HOUR # DB Module Week 6 MYSQL5Project Page 1

2 MAX_UPDATES_PER_HOUR # MAX_CONNECTIONS_PER_HOUR #]] REVOKE priv_type [(column_list)] [, priv_type [(column_list)]...] ON {tbl_name * *.* db_name.*} FROM user_name [, user_name...] GRANT is implemented in MySQL Version or later. For earlier MySQL versions, the GRANT statement does nothing. The GRANT and REVOKE commands allow system administrators to create users and grant and revoke rights to MySQL users at four privilege levels: Global level Global privileges apply to all databases on a given server. These privileges are stored in the mysql.user table. GRANT ALL ON *.* and REVOKE ALL ON *.* will grant and revoke only global privileges. Database level Database privileges apply to all tables in a given database. These privileges are stored in the mysql.db and mysql.host tables. GRANT ALL ON db.* and REVOKE ALL ON db.* will grant and revoke only database privileges. Table level Table privileges apply to all columns in a given table. These privileges are stored in the mysql.tables_priv table. GRANT ALL ON db.table and REVOKE ALL ON db.table will grant and revoke only table privileges. Column level Column privileges apply to single columns in a given table. These privileges are stored in the mysql.columns_priv table. When using REVOKE you must specify the same columns that were granted. For the GRANT and REVOKE statements, priv_type may be specified as any of the following: ALL [PRIVILEGES] Sets all simple privileges except WITH GRANT OPTION DB Module Week 6 MYSQL5Project Page 2

3 ALTER CREATE CREATE TEMPORARY TABLES DELETE DROP EXECUTE FILE INDEX INSERT LOCK TABLES PROCESS REFERENCES RELOAD REPLICATION CLIENT REPLICATION SLAVE SELECT SHOW DATABASES SHUTDOWN SUPER UPDATE Allows usage of ALTER TABLE Allows usage of CREATE TABLE Allows usage of CREATE TEMPORARY TABLE Allows usage of DELETE Allows usage of DROP TABLE. Allows the user to run stored procedures (MySQL 5.0) Allows usage of SELECT... INTO OUTFILE and LOAD DATA INFILE. Allows usage of CREATE INDEX and DROP INDEX Allows usage of INSERT Allows usage of LOCK TABLES on tables for which one has the SELECT privilege. Allows usage of SHOW FULL PROCESSLIST For the future Allows usage of FLUSH Gives the right to the user to ask where the slaves/masters are. Needed for the replication slaves (to read binlogs from master). Allows usage of SELECT SHOW DATABASES shows all databases. Allows usage of mysqladmin shutdown Allows one connect (once) even if max_connections is reached and execute commands CHANGE MASTER, KILL thread, mysqladmin debug, PURGE MASTER LOGS and SET GLOBAL Allows usage of UPDATE DB Module Week 6 MYSQL5Project Page 3

4 USAGE GRANT OPTION Synonym for ``no privileges.'' Synonym for WITH GRANT OPTION USAGE can be used when you want to create a user that has no privileges. In older MySQL versions, the PROCESS privilege gives the same rights as the new SUPER privilege. To revoke the GRANT privilege from a user, use a priv_type value of GRANT OPTION: mysql> REVOKE GRANT OPTION ON... FROM...; The only priv_type values you can specify for a table are SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, GRANT OPTION, INDEX, and ALTER. The only priv_type values you can specify for a column (that is, when you use a column_list clause) are SELECT, INSERT, and UPDATE. MySQL allows you to create database level privileges even if the database doesn't exist, to make it easy to prepare for database usage. Currently MySQL does however not allow one to create table level grants if the table doesn't exist. MySQL will not automatically revoke any privileges even if you drop a table or drop a database. You can set global privileges by using ON *.* syntax. You can set database privileges by using ON db_name.* syntax. If you specify ON * and you have a current database, you will set the privileges for that database. (Warning: if you specify ON * and you don't have a current database, you will affect the global privileges!) Please note: the `_' and `%' wildcards are allowed when specifying database names in GRANT commands. This means that if you wish to use for instance a `_' character as part of a database name, you should specify it as `\_' in the GRANT command, to prevent the user from being able to access additional databases matching the wildcard pattern, for example, GRANT... ON `foo\_bar`.* TO... DB Module Week 6 MYSQL5Project Page 4

5 In order to accommodate granting rights to users from arbitrary hosts, MySQL supports specifying the user_name value in the form If you want to specify a user string containing special characters (such as `-'), or a host string containing special characters or wildcard characters (such as `%'), you can quote the user or host name (for example, 'test-user'@'test-hostname'). You can specify wildcards in the hostname. For example, user@'%.loc.gov' applies to user for any host in the loc.gov domain, and user@' %' applies to user for any host in the class C subnet. The simple form user is a synonym for user@"%". MySQL doesn't support wildcards in user names. Anonymous users are defined by inserting entries with User='' into the mysql.user table or creating an user with an empty name with the GRANT command. Note: if you allow anonymous users to connect to the MySQL server, you should also grant privileges to all local users as user@localhost because otherwise the anonymous user entry for the local host in the mysql.user table will be used when the user tries to log into the MySQL server from the local machine! You can verify if this applies to you by executing this query: mysql> SELECT Host,User FROM mysql.user WHERE User=''; For the moment, GRANT only supports host, table, database, and column names up to 60 characters long. A user name can be up to 16 characters. The privileges for a table or column are formed from the logical OR of the privileges at each of the four privilege levels. For example, if the mysql.user table specifies that a user has a global SELECT privilege, this can't be denied by an entry at the database, table, or column level. The privileges for a column can be calculated as follows: global privileges OR (database privileges AND host privileges) OR table privileges DB Module Week 6 MYSQL5Project Page 5

6 OR column privileges In most cases, you grant rights to a user at only one of the privilege levels, so life isn't normally as complicated as above. If you grant privileges for a user/hostname combination that does not exist in the mysql.user table, an entry is added and remains there until deleted with a DELETE command. In other words, GRANT may create user table entries, but REVOKE will not remove them; you must do that explicitly using DELETE. If you don't want to send the password in clear text you can use the PASSWORD option followed by a scrambled password from SQL function PASSWORD() or the C API function make_scrambled_password(char *to, const char *password). Warning: if you create a new user but do not specify an IDENTIFIED BY clause, the user has no password. This is insecure. Passwords can also be set with the SET PASSWORD command. If you grant privileges for a database, an entry in the mysql.db table is created if needed. When all privileges for the database have been removed with REVOKE, this entry is deleted. If a user doesn't have any privileges on a table, the table is not displayed when the user requests a list of tables (for example, with a SHOW TABLES statement). The same is true for SHOW DATABASES. The WITH GRANT OPTION clause gives the user the ability to give to other users any privileges the user has at the specified privilege level. You should be careful to whom you give the GRANT privilege, as two users with different privileges may be able to join privileges! You cannot grant another user a privilege you don't have yourself; the GRANT privilege allows you to give away only those privileges you possess. Be aware that when you grant a user the GRANT privilege at a particular privilege level, any privileges the user already possesses (or is given in the future!) at that level are also grantable by that user. Suppose you grant a user the INSERT privilege on a database. If you DB Module Week 6 MYSQL5Project Page 6

7 then grant the SELECT privilege on the database and specify WITH GRANT OPTION, the user can give away not only the SELECT privilege, but also INSERT. If you then grant the UPDATE privilege to the user on the database, the user can give away the INSERT, SELECT and UPDATE. You should not grant ALTER privileges to a normal user. If you do that, the user can try to subvert the privilege system by renaming tables! Note that if you are using table or column privileges for even one user, the server examines table and column privileges for all users and this will slow down MySQL a bit. The biggest differences between the SQL standard and MySQL versions of GRANT are: In MySQL privileges are given for an username + hostname combination and not only for an username. SQL-99 doesn't have global or database-level privileges, nor does it support all the privilege types that MySQL supports. MySQL doesn't support the SQL-99 TRIGGER or UNDER privileges. SQL-99 privileges are structured in a hierarchal manner. If you remove a user, all privileges the user has granted are revoked. In MySQL the granted privileges are not automatically revoked, but you have to revoke these yourself if needed. In MySQL, if you have the INSERT privilege on only some of the columns in a table, you can execute INSERT statements on the table; the columns for which you don't have the INSERT privilege will be set to their default values. SQL-99 requires you to have the INSERT privilege on all columns. With SQL99, when you drop a table, all privileges for the table are revoked. With SQL-99, when you revoke a privilege, all privileges that were granted based on the privilege are also revoked. In MySQL, privileges can be dropped only with explicit REVOKE commands or by manipulating the MySQL grant tables. DB Module Week 6 MYSQL5Project Page 7

Using MySQL Workbench To Create new users: Start the MySQL Workbench. Select Server Administration from the home page. The Startup tab is selected. Click on the Accounts tab.

8 Using MySQL Workbench To Create new users: Start the MySQL Workbench. Select Server Administration from the home page. The Startup tab is selected. Click on the Accounts tab. Click Add Account on the bottom left of the page. Enter the user name john. Leave the password filed blank. (So that john can log on without the password) Click on Apply button. You should have the window similar to this one: DB Module Week 6 MYSQL5Project Page 8

9 Similarly, please create the local users phil, Claire, and frank. The users john, phil, claire, and frank can connect without a password, but only from the local host. The global privileges are all set to 'N'. It is assumed that you will grant database-specific privileges later. GRANT EXAMPLES Example 1: Grant all privileges on the table master1 to john. GRANT ALL ON master1 TO john; Example 2: Grant the appropriate privileges on the CALENDAR table so that users PHIL and CLAIRE can read it and insert new entries into it. Do not allow them to change or remove any existing entries. GRANT SELECT, INSERT ON CALENDAR TO phil, Claire; Example 3: Grant all privileges on the COUNCIL table to user FRANK and the ability to extend all privileges to others. GRANT ALL ON COUNCIL TO FRANK WITH GRANT OPTION; Example 4: GRANT SELECT privilege on table CORPDATA.EMPLOYEE to a user named JOHN. GRANT SELECT ON CORPDATA.EMPLOYEE TO JOHN; Example 5: Grant update privileges on table EMPLOYEE to all local users. GRANT UPDATE ON EMPLOYEE TO PUBLIC; REVOKE EXAMPLES Example 1: Revoke SELECT privilege on table EMPLOYEE from user ENGLES. DB Module Week 6 MYSQL5Project Page 9

10 REVOKE SELECT ON EMPLOYEE FROM ENGLES; Example 2: Revoke update privileges on table EMPLOYEE previously granted to all local users. REVOKE UPDATE ON EMPLOYEE FROM PUBLIC; Example 3: Revoke all privileges on table EMPLOYEE from users PELLOW and MLI. REVOKE ALL ON EMPLOYEE FROM PELLOW, MLI; Example 4: Revoke SELECT privilege on table CORPDATA.EMPLOYEE from a user named JOHN. REVOKE SELECT ON CORPDATA.EMPLOYEE FROM JOHN MySQL PROJECT FOR WEEK 6. (Paste your SQL commands into one file (word or txt) with the subject Week 6 Project ) 1. Using the MySQL Administrator (or any other GUI client or command line) create the following as users to MySQL CAP database: SLEEPY, DOC, BASHFUL, DOPEY, and HAPPY. You can use upper or lowercase whichever you prefer. (I suggest you have the same password for all of the users you add or no password.) Grant Usage to CAP database to all five dwarfs. Include a copy of your grant statement with screenshot or output in your project homework. 2. We don t trust DOPEY and SLEEPY, so grant them both only SELECT privileges on the agent, customer, and product table. Include a copy of your grant statement with screenshot or output in your project homework. 3. Grant BASHFUL all privileges on table Order_Line. Include a copy of your grant statement with screenshot or output in your project homework. 4. Grant HAPPY privileges to Select on all tables in the database. DB Module Week 6 MYSQL5Project Page 10

11 Include a copy of your grant statement with screenshot or output in your project homework. 5. Grant HAPPY privileges to insert into the ORDER1 table. Include a copy of your grant statement with screenshot or output in your project homework. 6. Grant DOPEY the privilege of updating the qty in the Order_Line table. Include a copy of your grant statement with screenshot or output in your project homework. 7. DOPEY has been bad. Revoke all privileges for him on all but the agent table. Include a copy of your grant statement with screenshot or output in your project homework. 8. Grant the privilege of select to the table Order_Line to the PUBLIC. Include a copy of your grant statement with screenshot or output in your project homework. DB Module Week 6 MYSQL5Project Page 11

Database Security: Transactions, Access Control, and SQL Injection

.. Cal Poly Spring 2013 CPE/CSC 365 Introduction to Database Systems Eriq Augustine.. Transactions Database Security: Transactions, Access Control, and SQL Injection A transaction is a sequence of SQL