pam

README

Go PAM

This is a Go wrapper for the PAM application API.

Testing

To run the full suite, the tests must be run as the root user. To setup your system for testing, create a user named "test" with the password "secret". For example:

$ sudo useradd test \
    -d /tmp/test \
    -p '$1$Qd8H95T5$RYSZQeoFbEB.gS19zS99A0' \
    -s /bin/false

Then execute the tests:

$ sudo GOPATH=$GOPATH $(which go) test -v

Documentation

Overview

Package pam provides a wrapper for the PAM application API.

Example

This example uses the default PAM service to authenticate any users. This should cause PAM to ask its conversation handler for a username and password in sequence.

package main

import (
	"bufio"
	"errors"
	"fmt"
	"os"

	"github.com/msteinert/pam"
	"golang.org/x/term"
)

func main() {
	t, err := pam.StartFunc("", "", func(s pam.Style, msg string) (string, error) {
		switch s {
		case pam.PromptEchoOff:
			fmt.Print(msg)
			pw, err := term.ReadPassword(int(os.Stdin.Fd()))
			if err != nil {
				return "", err
			}
			fmt.Println()
			return string(pw), nil
		case pam.PromptEchoOn:
			fmt.Print(msg)
			s := bufio.NewScanner(os.Stdin)
			s.Scan()
			return s.Text(), nil
		case pam.ErrorMsg:
			fmt.Fprintf(os.Stderr, "%s\n", msg)
			return "", nil
		case pam.TextInfo:
			fmt.Println(msg)
			return "", nil
		default:
			return "", errors.New("unrecognized message style")
		}
	})
	if err != nil {
		fmt.Fprintf(os.Stderr, "start: %s\n", err.Error())
		os.Exit(1)
	}
	err = t.Authenticate(0)
	if err != nil {
		fmt.Fprintf(os.Stderr, "authenticate: %s\n", err.Error())
		os.Exit(1)
	}
	fmt.Println("authentication succeeded!")
}

Index

• Constants
• type ConversationFunc
  • func (f ConversationFunc) RespondPAM(s Style, msg string) (string, error)
• type ConversationHandler
• type Flags
• type Item
• type Style
• type Transaction
  • func Start(service, user string, handler ConversationHandler) (*Transaction, error)
  • func StartFunc(service, user string, handler func(Style, string) (string, error)) (*Transaction, error)
  • func (t *Transaction) AcctMgmt(f Flags) error
  • func (t *Transaction) Authenticate(f Flags) error
  • func (t *Transaction) ChangeAuthTok(f Flags) error
  • func (t *Transaction) CloseSession(f Flags) error
  • func (t *Transaction) Error() string
  • func (t *Transaction) GetEnv(name string) string
  • func (t *Transaction) GetEnvList() (map[string]string, error)
  • func (t *Transaction) GetItem(i Item) (string, error)
  • func (t *Transaction) OpenSession(f Flags) error
  • func (t *Transaction) PutEnv(nameval string) error
  • func (t *Transaction) SetCred(f Flags) error
  • func (t *Transaction) SetItem(i Item, item string) error

Examples

• Package

Constants

const (
	// PromptEchoOff indicates the conversation handler should obtain a
	// string without echoing any text.
	PromptEchoOff Style = C.PAM_PROMPT_ECHO_OFF
	// PromptEchoOn indicates the conversation handler should obtain a
	// string while echoing text.
	PromptEchoOn = C.PAM_PROMPT_ECHO_ON
	// ErrorMsg indicates the conversation handler should display an
	// error message.
	ErrorMsg = C.PAM_ERROR_MSG
	// TextInfo indicates the conversation handler should display some
	// text.
	TextInfo = C.PAM_TEXT_INFO
)

Coversation handler style types.

const (
	// Service is the name which identifies the PAM stack.
	Service Item = C.PAM_SERVICE
	// User identifies the username identity used by a service.
	User = C.PAM_USER
	// Tty is the terminal name.
	Tty = C.PAM_TTY
	// Rhost is the requesting host name.
	Rhost = C.PAM_RHOST
	// Authtok is the currently active authentication token.
	Authtok = C.PAM_AUTHTOK
	// Oldauthtok is the old authentication token.
	Oldauthtok = C.PAM_OLDAUTHTOK
	// Ruser is the requesting user name.
	Ruser = C.PAM_RUSER
	// UserPrompt is the string use to prompt for a username.
	UserPrompt = C.PAM_USER_PROMPT
)

PAM Item types.

const (
	// Silent indicates that no messages should be emitted.
	Silent Flags = C.PAM_SILENT
	// DisallowNullAuthtok indicates that authorization should fail
	// if the user does not have a registered authentication token.
	DisallowNullAuthtok = C.PAM_DISALLOW_NULL_AUTHTOK
	// EstablishCred indicates that credentials should be established
	// for the user.
	EstablishCred = C.PAM_ESTABLISH_CRED
	// DeleteCred inidicates that credentials should be deleted.
	DeleteCred = C.PAM_DELETE_CRED
	// ReinitializeCred indicates that credentials should be fully
	// reinitialized.
	ReinitializeCred = C.PAM_REINITIALIZE_CRED
	// RefreshCred indicates that the lifetime of existing credentials
	// should be extended.
	RefreshCred = C.PAM_REFRESH_CRED
	// ChangeExpiredAuthtok indicates that the authentication token
	// should be changed if it has expired.
	ChangeExpiredAuthtok = C.PAM_CHANGE_EXPIRED_AUTHTOK
)

PAM Flag types.

Types

type ConversationFunc

type ConversationFunc func(Style, string) (string, error)

ConversationFunc is an adapter to allow the use of ordinary functions as conversation callbacks.

func (ConversationFunc) RespondPAM

func (f ConversationFunc) RespondPAM(s Style, msg string) (string, error)

RespondPAM is a conversation callback adapter.

type ConversationHandler

type ConversationHandler interface {
	// RespondPAM receives a message style and a message string. If the
	// message Style is PromptEchoOff or PromptEchoOn then the function
	// should return a response string.
	RespondPAM(Style, string) (string, error)
}

ConversationHandler is an interface for objects that can be used as conversation callbacks during PAM authentication.

type Flags

type Flags int

Flags are inputs to various PAM functions than be combined with a bitwise or. Refer to the official PAM documentation for which flags are accepted by which functions.

type Item

type Item int

Item is a an PAM information type.

type Style

type Style int

Style is the type of message that the conversation handler should display.

type Transaction

type Transaction struct {
	// contains filtered or unexported fields
}

Transaction is the application's handle for a PAM transaction.

func Start

func Start(service, user string, handler ConversationHandler) (*Transaction, error)

Start initiates a new PAM transaction. Service is treated identically to how pam_start treats it internally.

All application calls to PAM begin with Start (or StartFunc). The returned transaction provides an interface to the remainder of the API.

func StartFunc

func StartFunc(service, user string, handler func(Style, string) (string, error)) (*Transaction, error)

StartFunc registers the handler func as a conversation handler.

func (*Transaction) AcctMgmt

func (t *Transaction) AcctMgmt(f Flags) error

AcctMgmt is used to determine if the user's account is valid.

Valid flags: Silent, DisallowNullAuthtok

func (*Transaction) Authenticate

func (t *Transaction) Authenticate(f Flags) error

Authenticate is used to authenticate the user.

Valid flags: Silent, DisallowNullAuthtok

func (*Transaction) ChangeAuthTok

func (t *Transaction) ChangeAuthTok(f Flags) error

ChangeAuthTok is used to change the authentication token.

Valid flags: Silent, ChangeExpiredAuthtok

func (*Transaction) CloseSession

func (t *Transaction) CloseSession(f Flags) error

CloseSession closes a previously opened session.

Valid flags: Silent

func (*Transaction) Error

func (t *Transaction) Error() string

func (*Transaction) GetEnv

func (t *Transaction) GetEnv(name string) string

GetEnv is used to retrieve a PAM environment variable.

func (*Transaction) GetEnvList

func (t *Transaction) GetEnvList() (map[string]string, error)

GetEnvList returns a copy of the PAM environment as a map.

func (*Transaction) GetItem

func (t *Transaction) GetItem(i Item) (string, error)

GetItem retrieves a PAM information item.

func (*Transaction) OpenSession

func (t *Transaction) OpenSession(f Flags) error

OpenSession sets up a user session for an authenticated user.

Valid flags: Slient

func (*Transaction) PutEnv

func (t *Transaction) PutEnv(nameval string) error

PutEnv adds or changes the value of PAM environment variables.

NAME=value will set a variable to a value. NAME= will set a variable to an empty value. NAME (without an "=") will delete a variable.

func (*Transaction) SetCred

func (t *Transaction) SetCred(f Flags) error

SetCred is used to establish, maintain and delete the credentials of a user.

Valid flags: EstablishCred, DeleteCred, ReinitializeCred, RefreshCred

func (*Transaction) SetItem

func (t *Transaction) SetItem(i Item, item string) error

SetItem sets a PAM information item.