1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
// The UnixCredentials system call is currently only implemented on Linux
// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
// https://golang.org/s/go1.4-syscall
// http://code.google.com/p/go/source/browse/unix/sockcmsg_linux.go?repo=sys
// Local implementation of the UnixCredentials system call for DragonFly BSD
package dbus
/*
#include <sys/ucred.h>
*/
import "C"
import (
"io"
"os"
"syscall"
"unsafe"
)
// http://golang.org/src/pkg/syscall/ztypes_linux_amd64.go
// http://golang.org/src/pkg/syscall/ztypes_dragonfly_amd64.go
type Ucred struct {
Pid int32
Uid uint32
Gid uint32
}
// http://golang.org/src/pkg/syscall/types_linux.go
// http://golang.org/src/pkg/syscall/types_dragonfly.go
// https://github.com/DragonFlyBSD/DragonFlyBSD/blob/master/sys/sys/ucred.h
const (
SizeofUcred = C.sizeof_struct_ucred
)
// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
func cmsgAlignOf(salen int) int {
// From http://golang.org/src/pkg/syscall/sockcmsg_unix.go
//salign := sizeofPtr
// NOTE: It seems like 64-bit Darwin and DragonFly BSD kernels
// still require 32-bit aligned access to network subsystem.
//if darwin64Bit || dragonfly64Bit {
// salign = 4
//}
salign := 4
return (salen + salign - 1) & ^(salign - 1)
}
// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
func cmsgData(h *syscall.Cmsghdr) unsafe.Pointer {
return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(syscall.SizeofCmsghdr)))
}
// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
// UnixCredentials encodes credentials into a socket control message
// for sending to another process. This can be used for
// authentication.
func UnixCredentials(ucred *Ucred) []byte {
b := make([]byte, syscall.CmsgSpace(SizeofUcred))
h := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
h.Level = syscall.SOL_SOCKET
h.Type = syscall.SCM_CREDS
h.SetLen(syscall.CmsgLen(SizeofUcred))
*((*Ucred)(cmsgData(h))) = *ucred
return b
}
// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
// ParseUnixCredentials decodes a socket control message that contains
// credentials in a Ucred structure. To receive such a message, the
// SO_PASSCRED option must be enabled on the socket.
func ParseUnixCredentials(m *syscall.SocketControlMessage) (*Ucred, error) {
if m.Header.Level != syscall.SOL_SOCKET {
return nil, syscall.EINVAL
}
if m.Header.Type != syscall.SCM_CREDS {
return nil, syscall.EINVAL
}
ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
return &ucred, nil
}
func (t *unixTransport) SendNullByte() error {
ucred := &Ucred{Pid: int32(os.Getpid()), Uid: uint32(os.Getuid()), Gid: uint32(os.Getgid())}
b := UnixCredentials(ucred)
_, oobn, err := t.UnixConn.WriteMsgUnix([]byte{0}, b, nil)
if err != nil {
return err
}
if oobn != len(b) {
return io.ErrShortWrite
}
return nil
}
|
