User service daemon and client specification

Abstract

This is a specification for a Unix system facility to allow one program to invoke another when only limited trust exists between them.

Copyright Notice

userv is Copyright 1996-2003 Ian Jackson.

userv is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with userv; if not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

Contents

• 1 Introduction
• 2 Client program usage
• 2.1 Options
• 2.2 Security-overriding options
• 3 Execution environment of the service program
• 3.1 File descriptors
• 3.2 Environment
• 4 Service-side configuration
• 4.1 Configuration file syntax
• 4.2 Configuration file directives
• 4.3 Errors in the configuration file
• 4.4 Defaults
• 5 Information passed through the client/daemon combination
• 6 Applications and notes on use
• 6.1 Examples
• 6.2 Standard services and directory management
• 6.3 Reducing the number of absolutely privileged subsystems
• 6.4 Do not give away excessive privilege to userv-using facilities
• 6.5 userv can often replace sudo, but not really
• 6.6 Error handling and input streams (eg stdin)
• 6.7 Don't give access to general-purpose utilities

User service daemon and client specification