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/*
* pam.go - Utility functions for interfacing with the PAM libraries.
*
* Copyright 2017 Google Inc.
* Author: Joe Richey (joerichey@google.com)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package pam
/*
#cgo LDFLAGS: -lpam
#include "pam.h"
#include <pwd.h>
#include <stdlib.h>
#include <security/pam_modules.h>
*/
import "C"
import (
"errors"
"fmt"
"unsafe"
"github.com/google/fscrypt/util"
)
// Handle wraps the C pam_handle_t type. This is used from within modules.
type Handle struct {
handle *C.pam_handle_t
status C.int
}
// NewHandle creates a Handle from a raw pointer.
func NewHandle(pamh unsafe.Pointer) *Handle {
return &Handle{
handle: (*C.pam_handle_t)(pamh),
status: C.PAM_SUCCESS,
}
}
func (h *Handle) setData(name string, data unsafe.Pointer, cleanup C.CleanupFunc) error {
cName := C.CString(name)
defer C.free(unsafe.Pointer(cName))
h.status = C.pam_set_data(h.handle, cName, data, cleanup)
return h.err()
}
func (h *Handle) getData(name string) (unsafe.Pointer, error) {
var data unsafe.Pointer
cName := C.CString(name)
defer C.free(unsafe.Pointer(cName))
h.status = C.pam_get_data(h.handle, cName, &data)
return data, h.err()
}
func (h *Handle) SetSecret(name string, secret unsafe.Pointer) error {
return h.setData(name, C.copyIntoSecret(secret), C.CleanupFunc(C.freeSecret))
}
func (h *Handle) GetSecret(name string) (unsafe.Pointer, error) {
return h.getData(name)
}
func (h *Handle) ClearSecret(name string) error {
return h.setData(name, unsafe.Pointer(C.CString("")), C.CleanupFunc(C.freeData))
}
func (h *Handle) SetString(name string, s string) error {
return h.setData(name, unsafe.Pointer(C.CString(s)), C.CleanupFunc(C.freeData))
}
func (h *Handle) GetString(name string) (string, error) {
data, err := h.getData(name)
if err != nil {
return "", err
}
return C.GoString((*C.char)(data)), nil
}
func (h *Handle) SetSlice(name string, slice []string) error {
sliceLength := uintptr(len(slice))
memorySize := (sliceLength + 1) * unsafe.Sizeof(uintptr(0))
data := C.malloc(C.size_t(memorySize))
cSlice := util.PointerSlice(data)
for i, str := range slice {
cSlice[i] = unsafe.Pointer(C.CString(str))
}
cSlice[sliceLength] = nil
return h.setData(name, data, C.CleanupFunc(C.freeArray))
}
func (h *Handle) GetSlice(name string) ([]string, error) {
data, err := h.getData(name)
if err != nil {
return nil, err
}
var slice []string
for _, cString := range util.PointerSlice(data) {
if cString == nil {
return slice, nil
}
slice = append(slice, C.GoString((*C.char)(cString)))
}
panic("We will never get here")
}
// GetItem retrieves a PAM information item. This a pointer directory to the
// data, so it shouldn't be modified.
func (h *Handle) GetItem(i Item) (unsafe.Pointer, error) {
var data unsafe.Pointer
h.status = C.pam_get_item(h.handle, C.int(i), &data)
return data, h.err()
}
// GetUID retrieves the UID of the corresponding PAM_USER.
func (h *Handle) GetUID() (int64, error) {
var pamUsername *C.char
h.status = C.pam_get_user(h.handle, &pamUsername, nil)
if err := h.err(); err != nil {
return 0, err
}
pwd := C.getpwnam(pamUsername)
if pwd == nil {
return 0, fmt.Errorf("unknown user %q", C.GoString(pamUsername))
}
return int64(pwd.pw_uid), nil
}
func (h *Handle) err() error {
if h.status == C.PAM_SUCCESS {
return nil
}
s := C.GoString(C.pam_strerror(h.handle, C.int(h.status)))
return errors.New(s)
}
// Transaction represents a wrapped pam_handle_t type created with pam_start
// form an application.
type Transaction Handle
// Start initializes a pam Transaction. End() should be called after the
// Transaction is no longer needed.
func Start(service, username string) (*Transaction, error) {
cService := C.CString(service)
defer C.free(unsafe.Pointer(cService))
cUsername := C.CString(username)
defer C.free(unsafe.Pointer(cUsername))
t := &Transaction{
handle: nil,
status: C.PAM_SUCCESS,
}
t.status = C.pam_start(cService, cUsername, &C.conv, &t.handle)
return t, (*Handle)(t).err()
}
// End finalizes a pam Transaction with pam_end().
func (t *Transaction) End() {
C.pam_end(t.handle, t.status)
}
// Authenticate returns a boolean indicating if the user authenticated correctly
// or not. If the authentication check did not complete, an error is returned.
func (t *Transaction) Authenticate(quiet bool) (bool, error) {
var flags C.int = C.PAM_DISALLOW_NULL_AUTHTOK
if quiet {
flags |= C.PAM_SILENT
}
t.status = C.pam_authenticate(t.handle, flags)
if t.status == C.PAM_AUTH_ERR {
return false, nil
}
return true, (*Handle)(t).err()
}
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