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gitea/vendor/github.com/quasoft/websspi/websspi_windows.go

615 lines
18 KiB

package websspi
import (
"context"
"encoding/base64"
"encoding/gob"
"errors"
"fmt"
"log"
"net/http"
"strings"
"sync"
"syscall"
"time"
"unsafe"
"github.com/quasoft/websspi/secctx"
)
// The Config object determines the behaviour of the Authenticator.
type Config struct {
contextStore secctx.Store
authAPI API
KrbPrincipal string // Name of Kerberos principle used by the service (optional).
AuthUserKey string // Key of header to fill with authenticated username, eg. "X-Authenticated-User" or "REMOTE_USER" (optional).
EnumerateGroups bool // If true, groups the user is a member of are enumerated and stored in request context (default false)
ServerName string // Specifies the DNS or NetBIOS name of the remote server which to query about user groups. Ignored if EnumerateGroups is false.
}
// NewConfig creates a configuration object with default values.
func NewConfig() *Config {
return &Config{
contextStore: secctx.NewCookieStore(),
authAPI: &Win32{},
}
}
// Validate makes basic validation of configuration to make sure that important and required fields
// have been set with values in expected format.
func (c *Config) Validate() error {
if c.contextStore == nil {
return errors.New("Store for context handles not specified in Config")
}
if c.authAPI == nil {
return errors.New("Authentication API not specified in Config")
}
return nil
}
// contextKey represents a custom key for values stored in context.Context
type contextKey string
func (c contextKey) String() string {
return "websspi-key-" + string(c)
}
var (
UserInfoKey = contextKey("UserInfo")
)
// The Authenticator type provides middleware methods for authentication of http requests.
// A single authenticator object can be shared by concurrent goroutines.
type Authenticator struct {
Config Config
serverCred *CredHandle
credExpiry *time.Time
ctxList []CtxtHandle
ctxListMux *sync.Mutex
}
// New creates a new Authenticator object with the given configuration options.
func New(config *Config) (*Authenticator, error) {
err := config.Validate()
if err != nil {
return nil, fmt.Errorf("invalid config: %v", err)
}
var auth = &Authenticator{
Config: *config,
ctxListMux: &sync.Mutex{},
}
err = auth.PrepareCredentials(config.KrbPrincipal)
if err != nil {
return nil, fmt.Errorf("could not acquire credentials handle for the service: %v", err)
}
log.Printf("Credential handle expiry: %v\n", *auth.credExpiry)
return auth, nil
}
// PrepareCredentials method acquires a credentials handle for the specified principal
// for use during the live of the application.
// On success stores the handle in the serverCred field and its expiry time in the
// credExpiry field.
// This method must be called once - when the application is starting or when the first
// request from a client is received.
func (a *Authenticator) PrepareCredentials(principal string) error {
var principalPtr *uint16
if principal != "" {
var err error
principalPtr, err = syscall.UTF16PtrFromString(principal)
if err != nil {
return err
}
}
credentialUsePtr, err := syscall.UTF16PtrFromString(NEGOSSP_NAME)
if err != nil {
return err
}
var handle CredHandle
var expiry syscall.Filetime
status := a.Config.authAPI.AcquireCredentialsHandle(
principalPtr,
credentialUsePtr,
SECPKG_CRED_INBOUND,
nil, // logonId
nil, // authData
0, // getKeyFn
0, // getKeyArgument
&handle,
&expiry,
)
if status != SEC_E_OK {
return fmt.Errorf("call to AcquireCredentialsHandle failed with code 0x%x", status)
}
expiryTime := time.Unix(0, expiry.Nanoseconds())
a.credExpiry = &expiryTime
a.serverCred = &handle
return nil
}
// Free method should be called before shutting down the server to let
// it release allocated Win32 resources
func (a *Authenticator) Free() error {
var status SECURITY_STATUS
a.ctxListMux.Lock()
for _, ctx := range a.ctxList {
// TODO: Also check for stale security contexts and delete them periodically
status = a.Config.authAPI.DeleteSecurityContext(&ctx)
if status != SEC_E_OK {
return fmt.Errorf("call to DeleteSecurityContext failed with code 0x%x", status)
}
}
a.ctxList = nil
a.ctxListMux.Unlock()
if a.serverCred != nil {
status = a.Config.authAPI.FreeCredentialsHandle(a.serverCred)
if status != SEC_E_OK {
return fmt.Errorf("call to FreeCredentialsHandle failed with code 0x%x", status)
}
a.serverCred = nil
}
return nil
}
// StoreCtxHandle stores the specified context to the internal list (ctxList)
func (a *Authenticator) StoreCtxHandle(handle *CtxtHandle) {
if handle == nil || *handle == (CtxtHandle{}) {
// Should not add nil or empty handle
return
}
a.ctxListMux.Lock()
defer a.ctxListMux.Unlock()
a.ctxList = append(a.ctxList, *handle)
}
// ReleaseCtxHandle deletes a context handle and removes it from the internal list (ctxList)
func (a *Authenticator) ReleaseCtxHandle(handle *CtxtHandle) error {
if handle == nil || *handle == (CtxtHandle{}) {
// Removing a nil or empty handle is not an error condition
return nil
}
a.ctxListMux.Lock()
defer a.ctxListMux.Unlock()
// First, try to delete the handle
status := a.Config.authAPI.DeleteSecurityContext(handle)
if status != SEC_E_OK {
return fmt.Errorf("call to DeleteSecurityContext failed with code 0x%x", status)
}
// Then remove it from the internal list
foundAt := -1
for i, ctx := range a.ctxList {
if ctx == *handle {
foundAt = i
break
}
}
if foundAt > -1 {
a.ctxList[foundAt] = a.ctxList[len(a.ctxList)-1]
a.ctxList = a.ctxList[:len(a.ctxList)-1]
}
return nil
}
// AcceptOrContinue tries to validate the auth-data token by calling the AcceptSecurityContext
// function and returns and error if validation failed or continuation of the negotiation is needed.
// No error is returned if the token was validated (user was authenticated).
func (a *Authenticator) AcceptOrContinue(context *CtxtHandle, authData []byte) (newCtx *CtxtHandle, out []byte, exp *time.Time, err error) {
if authData == nil {
err = errors.New("input token cannot be nil")
return
}
var inputDesc SecBufferDesc
var inputBuf SecBuffer
inputDesc.BuffersCount = 1
inputDesc.Version = SECBUFFER_VERSION
inputDesc.Buffers = &inputBuf
inputBuf.BufferSize = uint32(len(authData))
inputBuf.BufferType = SECBUFFER_TOKEN
inputBuf.Buffer = &authData[0]
var outputDesc SecBufferDesc
var outputBuf SecBuffer
outputDesc.BuffersCount = 1
outputDesc.Version = SECBUFFER_VERSION
outputDesc.Buffers = &outputBuf
outputBuf.BufferSize = 0
outputBuf.BufferType = SECBUFFER_TOKEN
outputBuf.Buffer = nil
var expiry syscall.Filetime
var contextAttr uint32
var newContextHandle CtxtHandle
var status = a.Config.authAPI.AcceptSecurityContext(
a.serverCred,
context,
&inputDesc,
ASC_REQ_ALLOCATE_MEMORY|ASC_REQ_MUTUAL_AUTH|ASC_REQ_CONFIDENTIALITY|
ASC_REQ_INTEGRITY|ASC_REQ_REPLAY_DETECT|ASC_REQ_SEQUENCE_DETECT, // contextReq uint32,
SECURITY_NATIVE_DREP, // targDataRep uint32,
&newContextHandle,
&outputDesc, // *SecBufferDesc
&contextAttr, // contextAttr *uint32,
&expiry, // *syscall.Filetime
)
if newContextHandle.Lower != 0 || newContextHandle.Upper != 0 {
newCtx = &newContextHandle
}
tm := time.Unix(0, expiry.Nanoseconds())
exp = &tm
if status == SEC_E_OK || status == SEC_I_CONTINUE_NEEDED {
// Copy outputBuf.Buffer to out and free the outputBuf.Buffer
out = make([]byte, outputBuf.BufferSize)
var bufPtr = uintptr(unsafe.Pointer(outputBuf.Buffer))
for i := 0; i < len(out); i++ {
out[i] = *(*byte)(unsafe.Pointer(bufPtr))
bufPtr++
}
}
if outputBuf.Buffer != nil {
freeStatus := a.Config.authAPI.FreeContextBuffer(outputBuf.Buffer)
if freeStatus != SEC_E_OK {
status = freeStatus
err = fmt.Errorf("could not free output buffer; FreeContextBuffer() failed with code: 0x%x", freeStatus)
return
}
}
if status == SEC_I_CONTINUE_NEEDED {
err = errors.New("Negotiation should continue")
return
} else if status != SEC_E_OK {
err = fmt.Errorf("call to AcceptSecurityContext failed with code 0x%x", status)
return
}
// TODO: Check contextAttr?
return
}
// GetCtxHandle retrieves the context handle for this client from request's cookies
func (a *Authenticator) GetCtxHandle(r *http.Request) (*CtxtHandle, error) {
sessionHandle, err := a.Config.contextStore.GetHandle(r)
if err != nil {
return nil, fmt.Errorf("could not get context handle from session: %s", err)
}
if contextHandle, ok := sessionHandle.(*CtxtHandle); ok {
log.Printf("CtxHandle: 0x%x\n", *contextHandle)
if contextHandle.Lower == 0 && contextHandle.Upper == 0 {
return nil, nil
}
return contextHandle, nil
}
log.Printf("CtxHandle: nil\n")
return nil, nil
}
// SetCtxHandle stores the context handle for this client to cookie of response
func (a *Authenticator) SetCtxHandle(r *http.Request, w http.ResponseWriter, newContext *CtxtHandle) error {
// Store can't store nil value, so if newContext is nil, store an empty CtxHandle
ctx := &CtxtHandle{}
if newContext != nil {
ctx = newContext
}
err := a.Config.contextStore.SetHandle(r, w, ctx)
if err != nil {
return fmt.Errorf("could not save context to cookie: %s", err)
}
log.Printf("New context: 0x%x\n", *ctx)
return nil
}
// GetFlags returns the negotiated context flags
func (a *Authenticator) GetFlags(context *CtxtHandle) (uint32, error) {
var flags SecPkgContext_Flags
status := a.Config.authAPI.QueryContextAttributes(context, SECPKG_ATTR_FLAGS, (*byte)(unsafe.Pointer(&flags)))
if status != SEC_E_OK {
return 0, fmt.Errorf("QueryContextAttributes failed with status 0x%x", status)
}
return flags.Flags, nil
}
// GetUsername returns the name of the user associated with the specified security context
func (a *Authenticator) GetUsername(context *CtxtHandle) (username string, err error) {
var names SecPkgContext_Names
status := a.Config.authAPI.QueryContextAttributes(context, SECPKG_ATTR_NAMES, (*byte)(unsafe.Pointer(&names)))
if status != SEC_E_OK {
err = fmt.Errorf("QueryContextAttributes failed with status 0x%x", status)
return
}
if names.UserName != nil {
username = UTF16PtrToString(names.UserName, 2048)
status = a.Config.authAPI.FreeContextBuffer((*byte)(unsafe.Pointer(names.UserName)))
if status != SEC_E_OK {
err = fmt.Errorf("FreeContextBuffer failed with status 0x%x", status)
}
return
}
err = errors.New("QueryContextAttributes returned empty name")
return
}
// GetUserGroups returns the groups the user is a member of
func (a *Authenticator) GetUserGroups(userName string) (groups []string, err error) {
var serverNamePtr *uint16
if a.Config.ServerName != "" {
serverNamePtr, err = syscall.UTF16PtrFromString(a.Config.ServerName)
if err != nil {
return
}
}
userNamePtr, err := syscall.UTF16PtrFromString(userName)
if err != nil {
return
}
var buf *byte
var entriesRead uint32
var totalEntries uint32
err = a.Config.authAPI.NetUserGetGroups(
serverNamePtr,
userNamePtr,
0,
&buf,
MAX_PREFERRED_LENGTH,
&entriesRead,
&totalEntries,
)
if buf == nil {
err = fmt.Errorf("NetUserGetGroups(): returned nil buffer, error: %s", err)
return
}
defer func() {
freeErr := a.Config.authAPI.NetApiBufferFree(buf)
if freeErr != nil {
err = freeErr
}
}()
if err != nil {
return
}
if entriesRead < totalEntries {
err = fmt.Errorf("NetUserGetGroups(): could not read all entries, read only %d entries of %d", entriesRead, totalEntries)
return
}
ptr := uintptr(unsafe.Pointer(buf))
for i := uint32(0); i < entriesRead; i++ {
groupInfo := (*GroupUsersInfo0)(unsafe.Pointer(ptr))
groupName := UTF16PtrToString(groupInfo.Grui0_name, MAX_GROUP_NAME_LENGTH)
if groupName != "" {
groups = append(groups, groupName)
}
ptr += unsafe.Sizeof(GroupUsersInfo0{})
}
return
}
// GetUserInfo returns a structure containing the name of the user associated with the
// specified security context and the groups to which they are a member of (if Config.EnumerateGroups)
// is enabled
func (a *Authenticator) GetUserInfo(context *CtxtHandle) (*UserInfo, error) {
// Get username
username, err := a.GetUsername(context)
if err != nil {
return nil, err
}
info := UserInfo{
Username: username,
}
// Get groups
if a.Config.EnumerateGroups {
info.Groups, err = a.GetUserGroups(username)
if err != nil {
return nil, err
}
}
return &info, nil
}
// GetAuthData parses the "Authorization" header received from the client,
// extracts the auth-data token (input token) and decodes it to []byte
func (a *Authenticator) GetAuthData(r *http.Request, w http.ResponseWriter) (authData []byte, err error) {
// 1. Check if Authorization header is present
headers := r.Header["Authorization"]
if len(headers) == 0 {
err = errors.New("the Authorization header is not provided")
return
}
if len(headers) > 1 {
err = errors.New("received multiple Authorization headers, but expected only one")
return
}
authzHeader := strings.TrimSpace(headers[0])
if authzHeader == "" {
err = errors.New("the Authorization header is empty")
return
}
// 1.1. Make sure header starts with "Negotiate"
if !strings.HasPrefix(strings.ToLower(authzHeader), "negotiate") {
err = errors.New("the Authorization header does not start with 'Negotiate'")
return
}
// 2. Extract token from Authorization header
authzParts := strings.Split(authzHeader, " ")
if len(authzParts) < 2 {
err = errors.New("the Authorization header does not contain token (gssapi-data)")
return
}
token := authzParts[len(authzParts)-1]
if token == "" {
err = errors.New("the token (gssapi-data) in the Authorization header is empty")
return
}
// 3. Decode token
authData, err = base64.StdEncoding.DecodeString(token)
if err != nil {
err = errors.New("could not decode token as base64 string")
return
}
return
}
// Authenticate tries to authenticate the HTTP request and returns nil
// if authentication was successful.
// Returns error and data for continuation if authentication was not successful.
func (a *Authenticator) Authenticate(r *http.Request, w http.ResponseWriter) (userInfo *UserInfo, outToken string, err error) {
// 1. Extract auth-data from Authorization header
authData, err := a.GetAuthData(r, w)
if err != nil {
err = fmt.Errorf("could not get auth data: %s", err)
return
}
// 2. Authenticate user with provided token
contextHandle, err := a.GetCtxHandle(r)
if err != nil {
return
}
newCtx, output, _, err := a.AcceptOrContinue(contextHandle, authData)
// If a new context was created, make sure to delete it or store it
// both in internal list and response Cookie
defer func() {
// Negotiation is ending if we don't expect further responses from the client
// (authentication was successful or no output token is going to be sent back),
// clear client cookie
endOfNegotiation := err == nil || len(output) == 0
// Current context (contextHandle) is not needed anymore and should be deleted if:
// - we don't expect further responses from the client
// - a new context has been returned by AcceptSecurityContext
currCtxNotNeeded := endOfNegotiation || newCtx != nil
if !currCtxNotNeeded {
// Release current context only if its different than the new context
if contextHandle != nil && *contextHandle != *newCtx {
remErr := a.ReleaseCtxHandle(contextHandle)
if remErr != nil {
err = remErr
return
}
}
}
if endOfNegotiation {
// Clear client cookie
setErr := a.SetCtxHandle(r, w, nil)
if setErr != nil {
err = fmt.Errorf("could not clear context, error: %s", setErr)
return
}
// Delete any new context handle
remErr := a.ReleaseCtxHandle(newCtx)
if remErr != nil {
err = remErr
return
}
// Exit defer func
return
}
if newCtx != nil {
// Store new context handle to internal list and response Cookie
a.StoreCtxHandle(newCtx)
setErr := a.SetCtxHandle(r, w, newCtx)
if setErr != nil {
err = setErr
return
}
}
}()
outToken = base64.StdEncoding.EncodeToString(output)
if err != nil {
err = fmt.Errorf("AcceptOrContinue failed: %s", err)
return
}
// 3. Get username and user groups
currentCtx := newCtx
if currentCtx == nil {
currentCtx = contextHandle
}
userInfo, err = a.GetUserInfo(currentCtx)
if err != nil {
err = fmt.Errorf("could not get username, error: %s", err)
return
}
return
}
// AppendAuthenticateHeader populates WWW-Authenticate header,
// indicating to client that authentication is required and returns a 401 (Unauthorized)
// response code.
// The data parameter can be empty for the first 401 response from the server.
// For subsequent 401 responses the data parameter should contain the gssapi-data,
// which is required for continuation of the negotiation.
func (a *Authenticator) AppendAuthenticateHeader(w http.ResponseWriter, data string) {
value := "Negotiate"
if data != "" {
value += " " + data
}
w.Header().Set("WWW-Authenticate", value)
}
// Return401 populates WWW-Authenticate header, indicating to client that authentication
// is required and returns a 401 (Unauthorized) response code.
// The data parameter can be empty for the first 401 response from the server.
// For subsequent 401 responses the data parameter should contain the gssapi-data,
// which is required for continuation of the negotiation.
func (a *Authenticator) Return401(w http.ResponseWriter, data string) {
a.AppendAuthenticateHeader(w, data)
http.Error(w, "Error!", http.StatusUnauthorized)
}
// WithAuth authenticates the request. On successful authentication the request
// is passed down to the next http handler. The next handler can access information
// about the authenticated user via the GetUserName method.
// If authentication was not successful, the server returns 401 response code with
// a WWW-Authenticate, indicating that authentication is required.
func (a *Authenticator) WithAuth(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log.Printf("Authenticating request to %s\n", r.RequestURI)
user, data, err := a.Authenticate(r, w)
if err != nil {
log.Printf("Authentication failed with error: %v\n", err)
a.Return401(w, data)
return
}
log.Print("Authenticated\n")
// Add the UserInfo value to the reqest's context
r = r.WithContext(context.WithValue(r.Context(), UserInfoKey, user))
// and to the request header with key Config.AuthUserKey
if a.Config.AuthUserKey != "" {
r.Header.Set(a.Config.AuthUserKey, user.Username)
}
// The WWW-Authenticate header might need to be sent back even
// on successful authentication (eg. in order to let the client complete
// mutual authentication).
if data != "" {
a.AppendAuthenticateHeader(w, data)
}
next.ServeHTTP(w, r)
})
}
func init() {
gob.Register(&CtxtHandle{})
gob.Register(&UserInfo{})
}