executor: fix privilege check for 'show create user current_us… (#11229)

pingcap · Jul 15, 2019 · 36f9978 · 36f9978
1 parent ea59413
commit 36f9978
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Showing 2 changed files with 41 additions and 6 deletions.
diff --git a/executor/show.go b/executor/show.go
@@ -65,7 +65,7 @@ type ShowExec struct {
 	IndexName   model.CIStr     // Used for show table regions.
 	Flag        int             // Some flag parsed from sql, such as FULL.
 	Full        bool
-	User        *auth.UserIdentity   // Used for show grants.
+	User        *auth.UserIdentity   // Used by show grants, show create user.
 	Roles       []*auth.RoleIdentity // Used for show grants.
 	IfNotExists bool                 // Used for `show create database if not exists`
 
@@ -946,8 +946,23 @@ func (e *ShowExec) fetchShowCreateUser() error {
 	if checker == nil {
 		return errors.New("miss privilege checker")
 	}
+
+	userName, hostName := e.User.Username, e.User.Hostname
+	sessVars := e.ctx.GetSessionVars()
+	if e.User.CurrentUser {
+		userName = sessVars.User.AuthUsername
+		hostName = sessVars.User.AuthHostname
+	} else {
+		// Show create user requires the SELECT privilege on mysql.user.
+		// Ref https://dev.mysql.com/doc/refman/5.7/en/show-create-user.html
+		activeRoles := sessVars.ActiveRoles
+		if !checker.RequestVerification(activeRoles, mysql.SystemDB, mysql.UserTable, "", mysql.SelectPriv) {
+			return e.tableAccessDenied("SELECT", mysql.UserTable)
+		}
+	}
+
 	sql := fmt.Sprintf(`SELECT * FROM %s.%s WHERE User='%s' AND Host='%s';`,
-		mysql.SystemDB, mysql.UserTable, e.User.Username, e.User.Hostname)
+		mysql.SystemDB, mysql.UserTable, userName, hostName)
 	rows, _, err := e.ctx.(sqlexec.RestrictedSQLExecutor).ExecRestrictedSQL(e.ctx, sql)
 	if err != nil {
 		return errors.Trace(err)
@@ -956,9 +971,8 @@ func (e *ShowExec) fetchShowCreateUser() error {
 		return ErrCannotUser.GenWithStackByArgs("SHOW CREATE USER",
 			fmt.Sprintf("'%s'@'%s'", e.User.Username, e.User.Hostname))
 	}
-	showStr := fmt.Sprintf("CREATE USER '%s'@'%s' IDENTIFIED WITH 'mysql_native_password' AS '%s' %s",
-		e.User.Username, e.User.Hostname, checker.GetEncodedPassword(e.User.Username, e.User.Hostname),
-		"REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK")
+	showStr := fmt.Sprintf("CREATE USER '%s'@'%s' IDENTIFIED WITH 'mysql_native_password' AS '%s' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK",
+		e.User.Username, e.User.Hostname, checker.GetEncodedPassword(e.User.Username, e.User.Hostname))
 	e.appendRow([]interface{}{showStr})
 	return nil
 }

diff --git a/executor/show_test.go b/executor/show_test.go
@@ -278,7 +278,7 @@ func (s *testSuite2) TestShow2(c *C) {
 	tk.MustQuery("show grants for current_user").Check(testkit.Rows(`GRANT ALL PRIVILEGES ON *.* TO 'root'@'%'`))
 }
 
-func (s *testSuite2) TestShow3(c *C) {
+func (s *testSuite2) TestShowCreateUser(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	// Create a new user.
 	tk.MustExec(`CREATE USER 'test_show_create_user'@'%' IDENTIFIED BY 'root';`)
@@ -296,6 +296,27 @@ func (s *testSuite2) TestShow3(c *C) {
 	// Case: a user that doesn't exist
 	err = tk.QueryToErr("show create user 'aaa'@'localhost';")
 	c.Assert(err.Error(), Equals, executor.ErrCannotUser.GenWithStackByArgs("SHOW CREATE USER", "'aaa'@'localhost'").Error())
+
+	tk.Se.Auth(&auth.UserIdentity{Username: "root", Hostname: "127.0.0.1", AuthUsername: "root", AuthHostname: "%"}, nil, nil)
+	rows := tk.MustQuery("show create user current_user")
+	rows.Check(testkit.Rows("CREATE USER 'root'@'127.0.0.1' IDENTIFIED WITH 'mysql_native_password' AS '' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK"))
+
+	rows = tk.MustQuery("show create user current_user()")
+	rows.Check(testkit.Rows("CREATE USER 'root'@'127.0.0.1' IDENTIFIED WITH 'mysql_native_password' AS '' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK"))
+
+	tk.MustExec("create user 'check_priv'")
+
+	// "show create user" for other user requires the SELECT privilege on mysql database.
+	tk1 := testkit.NewTestKit(c, s.store)
+	tk1.MustExec("use mysql")
+	succ := tk1.Se.Auth(&auth.UserIdentity{Username: "check_priv", Hostname: "127.0.0.1", AuthUsername: "test_show", AuthHostname: "asdf"}, nil, nil)
+	c.Assert(succ, IsTrue)
+	err = tk1.QueryToErr("show create user 'root'@'%'")
+	c.Assert(err, NotNil)
+
+	// "show create user" for current user doesn't check privileges.
+	rows = tk1.MustQuery("show create user current_user")
+	rows.Check(testkit.Rows("CREATE USER 'check_priv'@'127.0.0.1' IDENTIFIED WITH 'mysql_native_password' AS '' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK"))
 }
 
 func (s *testSuite2) TestUnprivilegedShow(c *C) {