92 lines
2.5 KiB
Go
92 lines
2.5 KiB
Go
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// The UnixCredentials system call is currently only implemented on Linux
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// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
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// https://golang.org/s/go1.4-syscall
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// http://code.google.com/p/go/source/browse/unix/sockcmsg_linux.go?repo=sys
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// Local implementation of the UnixCredentials system call for FreeBSD
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package dbus
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/*
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const int sizeofPtr = sizeof(void*);
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#define _WANT_UCRED
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#include <sys/ucred.h>
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*/
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import "C"
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import (
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"io"
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"os"
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"syscall"
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"unsafe"
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)
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// http://golang.org/src/pkg/syscall/ztypes_linux_amd64.go
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// https://golang.org/src/syscall/ztypes_freebsd_amd64.go
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type Ucred struct {
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Pid int32
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Uid uint32
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Gid uint32
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}
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// http://golang.org/src/pkg/syscall/types_linux.go
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// https://golang.org/src/syscall/types_freebsd.go
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// https://github.com/freebsd/freebsd/blob/master/sys/sys/ucred.h
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const (
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SizeofUcred = C.sizeof_struct_ucred
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)
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// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
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func cmsgAlignOf(salen int) int {
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salign := C.sizeofPtr
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return (salen + salign - 1) & ^(salign - 1)
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}
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// http://golang.org/src/pkg/syscall/sockcmsg_unix.go
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func cmsgData(h *syscall.Cmsghdr) unsafe.Pointer {
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return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(syscall.SizeofCmsghdr)))
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}
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// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
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// UnixCredentials encodes credentials into a socket control message
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// for sending to another process. This can be used for
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// authentication.
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func UnixCredentials(ucred *Ucred) []byte {
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b := make([]byte, syscall.CmsgSpace(SizeofUcred))
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h := (*syscall.Cmsghdr)(unsafe.Pointer(&b[0]))
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h.Level = syscall.SOL_SOCKET
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h.Type = syscall.SCM_CREDS
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h.SetLen(syscall.CmsgLen(SizeofUcred))
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*((*Ucred)(cmsgData(h))) = *ucred
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return b
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}
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// http://golang.org/src/pkg/syscall/sockcmsg_linux.go
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// ParseUnixCredentials decodes a socket control message that contains
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// credentials in a Ucred structure. To receive such a message, the
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// SO_PASSCRED option must be enabled on the socket.
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func ParseUnixCredentials(m *syscall.SocketControlMessage) (*Ucred, error) {
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if m.Header.Level != syscall.SOL_SOCKET {
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return nil, syscall.EINVAL
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}
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if m.Header.Type != syscall.SCM_CREDS {
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return nil, syscall.EINVAL
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}
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ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
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return &ucred, nil
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}
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func (t *unixTransport) SendNullByte() error {
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ucred := &Ucred{Pid: int32(os.Getpid()), Uid: uint32(os.Getuid()), Gid: uint32(os.Getgid())}
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b := UnixCredentials(ucred)
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_, oobn, err := t.UnixConn.WriteMsgUnix([]byte{0}, b, nil)
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if err != nil {
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return err
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}
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if oobn != len(b) {
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return io.ErrShortWrite
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}
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return nil
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}
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