diff --git a/vendor/golang.org/x/sys/unix/sockcmsg_linux.go b/vendor/golang.org/x/sys/unix/sockcmsg_linux.go
new file mode 100644
index 0000000..5f63147
--- /dev/null
+++ b/vendor/golang.org/x/sys/unix/sockcmsg_linux.go
@@ -0,0 +1,85 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Socket control messages
+
+package unix
+
+import "unsafe"
+
+// 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, CmsgSpace(SizeofUcred))
+	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
+	h.Level = SOL_SOCKET
+	h.Type = SCM_CREDENTIALS
+	h.SetLen(CmsgLen(SizeofUcred))
+	*(*Ucred)(h.data(0)) = *ucred
+	return b
+}
+
+// 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 *SocketControlMessage) (*Ucred, error) {
+	if m.Header.Level != SOL_SOCKET {
+		return nil, EINVAL
+	}
+	if m.Header.Type != SCM_CREDENTIALS {
+		return nil, EINVAL
+	}
+	ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
+	return &ucred, nil
+}
+
+// PktInfo4 encodes Inet4Pktinfo into a socket control message of type IP_PKTINFO.
+func PktInfo4(info *Inet4Pktinfo) []byte {
+	b := make([]byte, CmsgSpace(SizeofInet4Pktinfo))
+	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
+	h.Level = SOL_IP
+	h.Type = IP_PKTINFO
+	h.SetLen(CmsgLen(SizeofInet4Pktinfo))
+	*(*Inet4Pktinfo)(h.data(0)) = *info
+	return b
+}
+
+// PktInfo6 encodes Inet6Pktinfo into a socket control message of type IPV6_PKTINFO.
+func PktInfo6(info *Inet6Pktinfo) []byte {
+	b := make([]byte, CmsgSpace(SizeofInet6Pktinfo))
+	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
+	h.Level = SOL_IPV6
+	h.Type = IPV6_PKTINFO
+	h.SetLen(CmsgLen(SizeofInet6Pktinfo))
+	*(*Inet6Pktinfo)(h.data(0)) = *info
+	return b
+}
+
+// ParseOrigDstAddr decodes a socket control message containing the original
+// destination address. To receive such a message the IP_RECVORIGDSTADDR or
+// IPV6_RECVORIGDSTADDR option must be enabled on the socket.
+func ParseOrigDstAddr(m *SocketControlMessage) (Sockaddr, error) {
+	switch {
+	case m.Header.Level == SOL_IP && m.Header.Type == IP_ORIGDSTADDR:
+		pp := (*RawSockaddrInet4)(unsafe.Pointer(&m.Data[0]))
+		sa := new(SockaddrInet4)
+		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+		sa.Port = int(p[0])<<8 + int(p[1])
+		sa.Addr = pp.Addr
+		return sa, nil
+
+	case m.Header.Level == SOL_IPV6 && m.Header.Type == IPV6_ORIGDSTADDR:
+		pp := (*RawSockaddrInet6)(unsafe.Pointer(&m.Data[0]))
+		sa := new(SockaddrInet6)
+		p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+		sa.Port = int(p[0])<<8 + int(p[1])
+		sa.ZoneId = pp.Scope_id
+		sa.Addr = pp.Addr
+		return sa, nil
+
+	default:
+		return nil, EINVAL
+	}
+}