462 lines
16 KiB
Go
462 lines
16 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build windows
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// Package negotiate provides access to the Microsoft Negotiate SSP Package.
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//
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package negotiate
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import (
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"errors"
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"syscall"
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"time"
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"unsafe"
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"github.com/alexbrainman/sspi"
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)
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// TODO: maybe (if possible) move all winapi related out of sspi and into sspi/internal/winapi
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// PackageInfo contains Negotiate SSP package description.
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var PackageInfo *sspi.PackageInfo
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func init() {
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var err error
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PackageInfo, err = sspi.QueryPackageInfo(sspi.NEGOSSP_NAME)
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if err != nil {
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panic("failed to fetch Negotiate package info: " + err.Error())
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}
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}
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func acquireCredentials(principalName string, creduse uint32, ai *sspi.SEC_WINNT_AUTH_IDENTITY) (*sspi.Credentials, error) {
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c, err := sspi.AcquireCredentials(principalName, sspi.NEGOSSP_NAME, creduse, (*byte)(unsafe.Pointer(ai)))
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if err != nil {
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return nil, err
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}
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return c, nil
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}
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// AcquireCurrentUserCredentials acquires credentials of currently
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// logged on user. These will be used by the client to authenticate
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// itself to the server. It will also be used by the server
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// to impersonate the user.
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func AcquireCurrentUserCredentials() (*sspi.Credentials, error) {
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return acquireCredentials("", sspi.SECPKG_CRED_OUTBOUND, nil)
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}
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// TODO: see if I can share this common ntlm and negotiate code
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// AcquireUserCredentials acquires credentials of user described by
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// domain, username and password. These will be used by the client to
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// authenticate itself to the server. It will also be used by the
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// server to impersonate the user.
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func AcquireUserCredentials(domain, username, password string) (*sspi.Credentials, error) {
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if len(username) == 0 {
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return nil, errors.New("username parameter cannot be empty")
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}
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d, err := syscall.UTF16FromString(domain)
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if err != nil {
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return nil, err
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}
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u, err := syscall.UTF16FromString(username)
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if err != nil {
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return nil, err
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}
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p, err := syscall.UTF16FromString(password)
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if err != nil {
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return nil, err
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}
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ai := sspi.SEC_WINNT_AUTH_IDENTITY{
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User: &u[0],
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UserLength: uint32(len(u) - 1), // do not count terminating 0
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Domain: &d[0],
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DomainLength: uint32(len(d) - 1), // do not count terminating 0
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Password: &p[0],
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PasswordLength: uint32(len(p) - 1), // do not count terminating 0
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Flags: sspi.SEC_WINNT_AUTH_IDENTITY_UNICODE,
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}
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return acquireCredentials("", sspi.SECPKG_CRED_OUTBOUND, &ai)
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}
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// AcquireServerCredentials acquires server credentials that will
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// be used to authenticate clients.
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// The principalName parameter is passed to the underlying call to
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// the winapi AcquireCredentialsHandle function (and specifies the
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// name of the principal whose credentials the underlying handle
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// will reference).
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// As a special case, using an empty string for the principal name
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// will require the credential of the user under whose security context
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// the current process is running.
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func AcquireServerCredentials(principalName string) (*sspi.Credentials, error) {
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return acquireCredentials(principalName, sspi.SECPKG_CRED_INBOUND, nil)
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}
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func updateContext(c *sspi.Context, dst, src []byte, targetName *uint16) (authCompleted bool, n int, err error) {
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var inBuf, outBuf [1]sspi.SecBuffer
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inBuf[0].Set(sspi.SECBUFFER_TOKEN, src)
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inBufs := &sspi.SecBufferDesc{
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Version: sspi.SECBUFFER_VERSION,
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BuffersCount: 1,
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Buffers: &inBuf[0],
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}
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outBuf[0].Set(sspi.SECBUFFER_TOKEN, dst)
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outBufs := &sspi.SecBufferDesc{
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Version: sspi.SECBUFFER_VERSION,
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BuffersCount: 1,
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Buffers: &outBuf[0],
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}
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ret := c.Update(targetName, outBufs, inBufs)
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switch ret {
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case sspi.SEC_E_OK:
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// session established -> return success
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return true, int(outBuf[0].BufferSize), nil
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case sspi.SEC_I_COMPLETE_NEEDED, sspi.SEC_I_COMPLETE_AND_CONTINUE:
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ret = sspi.CompleteAuthToken(c.Handle, outBufs)
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if ret != sspi.SEC_E_OK {
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return false, 0, ret
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}
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case sspi.SEC_I_CONTINUE_NEEDED:
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default:
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return false, 0, ret
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}
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return false, int(outBuf[0].BufferSize), nil
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}
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func makeSignature(c *sspi.Context, msg []byte, qop, seqno uint32) ([]byte, error) {
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_, maxSignature, _, _, err := c.Sizes()
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if err != nil {
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return nil, err
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}
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if maxSignature == 0 {
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return nil, errors.New("integrity services are not requested or unavailable")
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}
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var b [2]sspi.SecBuffer
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b[0].Set(sspi.SECBUFFER_DATA, msg)
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b[1].Set(sspi.SECBUFFER_TOKEN, make([]byte, maxSignature))
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ret := sspi.MakeSignature(c.Handle, qop, sspi.NewSecBufferDesc(b[:]), seqno)
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if ret != sspi.SEC_E_OK {
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return nil, ret
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}
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return b[1].Bytes(), nil
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}
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func encryptMessage(c *sspi.Context, msg []byte, qop, seqno uint32) ([]byte, error) {
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_ /*maxToken*/, maxSignature, cBlockSize, cSecurityTrailer, err := c.Sizes()
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if err != nil {
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return nil, err
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}
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if maxSignature == 0 {
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return nil, errors.New("integrity services are not requested or unavailable")
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}
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var b [3]sspi.SecBuffer
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b[0].Set(sspi.SECBUFFER_TOKEN, make([]byte, cSecurityTrailer))
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b[1].Set(sspi.SECBUFFER_DATA, msg)
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b[2].Set(sspi.SECBUFFER_PADDING, make([]byte, cBlockSize))
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ret := sspi.EncryptMessage(c.Handle, qop, sspi.NewSecBufferDesc(b[:]), seqno)
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if ret != sspi.SEC_E_OK {
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return nil, ret
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}
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r0, r1, r2 := b[0].Bytes(), b[1].Bytes(), b[2].Bytes()
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res := make([]byte, 0, len(r0)+len(r1)+len(r2))
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res = append(res, r0...)
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res = append(res, r1...)
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res = append(res, r2...)
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return res, nil
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}
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func decryptMessage(c *sspi.Context, msg []byte, seqno uint32) (uint32, []byte, error) {
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var b [2]sspi.SecBuffer
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b[0].Set(sspi.SECBUFFER_STREAM, msg)
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b[1].Set(sspi.SECBUFFER_DATA, []byte{})
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var qop uint32
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ret := sspi.DecryptMessage(c.Handle, sspi.NewSecBufferDesc(b[:]), seqno, &qop)
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if ret != sspi.SEC_E_OK {
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return qop, nil, ret
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}
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return qop, b[1].Bytes(), nil
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}
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func verifySignature(c *sspi.Context, msg, token []byte, seqno uint32) (uint32, error) {
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var b [2]sspi.SecBuffer
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b[0].Set(sspi.SECBUFFER_DATA, msg)
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b[1].Set(sspi.SECBUFFER_TOKEN, token)
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var qop uint32
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ret := sspi.VerifySignature(c.Handle, sspi.NewSecBufferDesc(b[:]), seqno, &qop)
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if ret != sspi.SEC_E_OK {
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return 0, ret
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}
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return qop, nil
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}
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// ClientContext is used by the client to manage all steps of Negotiate negotiation.
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type ClientContext struct {
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sctxt *sspi.Context
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targetName *uint16
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}
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// NewClientContext creates a new client context. It uses client
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// credentials cred generated by AcquireCurrentUserCredentials or
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// AcquireUserCredentials and SPN to start a client Negotiate
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// negotiation sequence. targetName is the service principal name
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// (SPN) or the security context of the destination server.
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// NewClientContext returns a new token to be sent to the server.
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func NewClientContext(cred *sspi.Credentials, targetName string) (cc *ClientContext, outputToken []byte, err error) {
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return NewClientContextWithFlags(cred, targetName, sspi.ISC_REQ_CONNECTION)
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}
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// NewClientContextWithFlags creates a new client context. It uses client
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// credentials cred generated by AcquireCurrentUserCredentials or
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// AcquireUserCredentials and SPN to start a client Negotiate
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// negotiation sequence. targetName is the service principal name
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// (SPN) or the security context of the destination server.
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// The flags parameter is used to indicate requests for the context
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// (for example sspi.ISC_REQ_CONFIDENTIALITY|sspi.ISC_REQ_REPLAY_DETECT)
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// NewClientContextWithFlags returns a new token to be sent to the server.
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func NewClientContextWithFlags(cred *sspi.Credentials, targetName string, flags uint32) (cc *ClientContext, outputToken []byte, err error) {
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var tname *uint16
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if len(targetName) > 0 {
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p, err2 := syscall.UTF16FromString(targetName)
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if err2 != nil {
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return nil, nil, err2
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}
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if len(p) > 0 {
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tname = &p[0]
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}
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}
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otoken := make([]byte, PackageInfo.MaxToken)
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c := sspi.NewClientContext(cred, flags)
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authCompleted, n, err2 := updateContext(c, otoken, nil, tname)
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if err2 != nil {
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return nil, nil, err2
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}
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if authCompleted {
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c.Release()
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return nil, nil, errors.New("negotiate authentication should not be completed yet")
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}
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if n == 0 {
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c.Release()
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return nil, nil, errors.New("negotiate token should not be empty")
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}
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otoken = otoken[:n]
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return &ClientContext{sctxt: c, targetName: tname}, otoken, nil
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}
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// Release free up resources associated with client context c.
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func (c *ClientContext) Release() error {
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if c == nil {
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return nil
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}
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return c.sctxt.Release()
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}
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// Expiry returns c expiry time.
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func (c *ClientContext) Expiry() time.Time {
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return c.sctxt.Expiry()
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}
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// Update advances client part of Negotiate negotiation c. It uses
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// token received from the server and returns true if client part
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// of authentication is complete. It also returns new token to be
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// sent to the server.
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func (c *ClientContext) Update(token []byte) (authCompleted bool, outputToken []byte, err error) {
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otoken := make([]byte, PackageInfo.MaxToken)
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authDone, n, err2 := updateContext(c.sctxt, otoken, token, c.targetName)
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if err2 != nil {
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return false, nil, err2
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}
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if n == 0 && !authDone {
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return false, nil, errors.New("negotiate token should not be empty")
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}
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otoken = otoken[:n]
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return authDone, otoken, nil
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}
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// Sizes queries the client context for the sizes used in per-message
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// functions. It returns the maximum token size used in authentication
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// exchanges, the maximum signature size, the preferred integral size of
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// messages, the size of any security trailer, and any error.
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func (c *ClientContext) Sizes() (uint32, uint32, uint32, uint32, error) {
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return c.sctxt.Sizes()
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}
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// MakeSignature uses the established client context to create a signature
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// for the given message using the provided quality of protection flags and
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// sequence number. It returns the signature token in addition to any error.
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func (c *ClientContext) MakeSignature(msg []byte, qop, seqno uint32) ([]byte, error) {
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return makeSignature(c.sctxt, msg, qop, seqno)
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}
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// VerifySignature uses the established client context and signature token
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// to check that the provided message hasn't been tampered or received out
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// of sequence. It returns any quality of protection flags and any error
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// that occurred.
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func (c *ClientContext) VerifySignature(msg, token []byte, seqno uint32) (uint32, error) {
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return verifySignature(c.sctxt, msg, token, seqno)
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}
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// EncryptMessage uses the established client context to encrypt a message
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// using the provided quality of protection flags and sequence number.
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// It returns the signature token in addition to any error.
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// IMPORTANT: the input msg parameter is updated in place by the low-level windows api
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// so must be copied if the initial content should not be modified.
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func (c *ClientContext) EncryptMessage(msg []byte, qop, seqno uint32) ([]byte, error) {
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return encryptMessage(c.sctxt, msg, qop, seqno)
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}
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// DecryptMessage uses the established client context to decrypt a message
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// using the provided sequence number.
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// It returns the quality of protection flag and the decrypted message in addition to any error.
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func (c *ClientContext) DecryptMessage(msg []byte, seqno uint32) (uint32, []byte, error) {
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return decryptMessage(c.sctxt, msg, seqno)
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}
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// VerifyFlags determines if all flags used to construct the client context
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// were honored (see NewClientContextWithFlags). It should be called after c.Update.
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func (c *ClientContext) VerifyFlags() error {
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return c.sctxt.VerifyFlags()
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}
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// VerifySelectiveFlags determines if the given flags were honored (see NewClientContextWithFlags).
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// It should be called after c.Update.
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func (c *ClientContext) VerifySelectiveFlags(flags uint32) error {
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return c.sctxt.VerifySelectiveFlags(flags)
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}
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// ServerContext is used by the server to manage all steps of Negotiate
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// negotiation. Once authentication is completed the context can be
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// used to impersonate client.
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type ServerContext struct {
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sctxt *sspi.Context
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}
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// NewServerContext creates new server context. It uses server
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// credentials created by AcquireServerCredentials and token from
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// the client to start server Negotiate negotiation sequence.
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// It also returns new token to be sent to the client.
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func NewServerContext(cred *sspi.Credentials, token []byte) (sc *ServerContext, authDone bool, outputToken []byte, err error) {
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otoken := make([]byte, PackageInfo.MaxToken)
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c := sspi.NewServerContext(cred, sspi.ASC_REQ_CONNECTION)
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authDone, n, err2 := updateContext(c, otoken, token, nil)
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if err2 != nil {
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return nil, false, nil, err2
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}
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otoken = otoken[:n]
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return &ServerContext{sctxt: c}, authDone, otoken, nil
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}
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// Release free up resources associated with server context c.
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func (c *ServerContext) Release() error {
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if c == nil {
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return nil
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}
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return c.sctxt.Release()
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}
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// Expiry returns c expiry time.
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func (c *ServerContext) Expiry() time.Time {
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return c.sctxt.Expiry()
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}
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// Update advances server part of Negotiate negotiation c. It uses
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// token received from the client and returns true if server part
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// of authentication is complete. It also returns new token to be
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// sent to the client.
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func (c *ServerContext) Update(token []byte) (authCompleted bool, outputToken []byte, err error) {
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otoken := make([]byte, PackageInfo.MaxToken)
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authDone, n, err2 := updateContext(c.sctxt, otoken, token, nil)
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if err2 != nil {
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return false, nil, err2
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}
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if n == 0 && !authDone {
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return false, nil, errors.New("negotiate token should not be empty")
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}
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otoken = otoken[:n]
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return authDone, otoken, nil
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}
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const _SECPKG_ATTR_NATIVE_NAMES = 13
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type _SecPkgContext_NativeNames struct {
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ClientName *uint16
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ServerName *uint16
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}
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// GetUsername returns the username corresponding to the authenticated client
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func (c *ServerContext) GetUsername() (string, error) {
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var ns _SecPkgContext_NativeNames
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ret := sspi.QueryContextAttributes(c.sctxt.Handle, _SECPKG_ATTR_NATIVE_NAMES, (*byte)(unsafe.Pointer(&ns)))
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if ret != sspi.SEC_E_OK {
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return "", ret
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}
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sspi.FreeContextBuffer((*byte)(unsafe.Pointer(ns.ServerName)))
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defer sspi.FreeContextBuffer((*byte)(unsafe.Pointer(ns.ClientName)))
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return syscall.UTF16ToString((*[2 << 20]uint16)(unsafe.Pointer(ns.ClientName))[:]), nil
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}
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// ImpersonateUser changes current OS thread user. New user is
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// the user as specified by client credentials.
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func (c *ServerContext) ImpersonateUser() error {
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return c.sctxt.ImpersonateUser()
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}
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// RevertToSelf stops impersonation. It changes current OS thread
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// user to what it was before ImpersonateUser was executed.
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func (c *ServerContext) RevertToSelf() error {
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return c.sctxt.RevertToSelf()
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}
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// Sizes queries the server context for the sizes used in per-message
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// functions. It returns the maximum token size used in authentication
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// exchanges, the maximum signature size, the preferred integral size of
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// messages, the size of any security trailer, and any error.
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func (c *ServerContext) Sizes() (uint32, uint32, uint32, uint32, error) {
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return c.sctxt.Sizes()
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}
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// MakeSignature uses the established server context to create a signature
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// for the given message using the provided quality of protection flags and
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// sequence number. It returns the signature token in addition to any error.
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func (c *ServerContext) MakeSignature(msg []byte, qop, seqno uint32) ([]byte, error) {
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return makeSignature(c.sctxt, msg, qop, seqno)
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}
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// VerifySignature uses the established server context and signature token
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// to check that the provided message hasn't been tampered or received out
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// of sequence. It returns any quality of protection flags and any error
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// that occurred.
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func (c *ServerContext) VerifySignature(msg, token []byte, seqno uint32) (uint32, error) {
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return verifySignature(c.sctxt, msg, token, seqno)
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}
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// EncryptMessage uses the established server context to encrypt a message
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// using the provided quality of protection flags and sequence number.
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// It returns the signature token in addition to any error.
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// IMPORTANT: the input msg parameter is updated in place by the low-level windows api
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// so must be copied if the initial content should not be modified.
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func (c *ServerContext) EncryptMessage(msg []byte, qop, seqno uint32) ([]byte, error) {
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return encryptMessage(c.sctxt, msg, qop, seqno)
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}
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// DecryptMessage uses the established server context to decrypt a message
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// using the provided sequence number.
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// It returns the quality of protection flag and the decrypted message in addition to any error.
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func (c *ServerContext) DecryptMessage(msg []byte, seqno uint32) (uint32, []byte, error) {
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return decryptMessage(c.sctxt, msg, seqno)
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}
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