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package main
import (
"crypto/rand"
"crypto/tls"
"encoding/hex"
"encoding/json"
"errors"
"flag"
"fmt"
"html/template"
"io"
"log"
"net"
"net/http"
"os"
"strconv"
"strings"
"go4.org/wkfs"
"golang.org/x/oauth2"
"github.com/gorilla/csrf"
"github.com/gorilla/handlers"
"github.com/gorilla/mux"
"github.com/gorilla/sessions"
"github.com/nsheridan/cashier/lib"
"github.com/nsheridan/cashier/server/auth"
"github.com/nsheridan/cashier/server/auth/github"
"github.com/nsheridan/cashier/server/auth/google"
"github.com/nsheridan/cashier/server/config"
"github.com/nsheridan/cashier/server/signer"
"github.com/nsheridan/cashier/server/static"
"github.com/nsheridan/cashier/server/store"
"github.com/nsheridan/cashier/server/templates"
"github.com/nsheridan/cashier/server/util"
"github.com/nsheridan/cashier/server/wkfs/s3fs"
"github.com/nsheridan/cashier/server/wkfs/vaultfs"
"github.com/sid77/drop"
)
var (
cfg = flag.String("config_file", "cashierd.conf", "Path to configuration file.")
)
// appContext contains local context - cookiestore, authprovider, authsession etc.
type appContext struct {
cookiestore *sessions.CookieStore
authprovider auth.Provider
authsession *auth.Session
sshKeySigner *signer.KeySigner
certstore store.CertStorer
}
// getAuthTokenCookie retrieves a cookie from the request.
func (a *appContext) getAuthTokenCookie(r *http.Request) *oauth2.Token {
session, _ := a.cookiestore.Get(r, "session")
t, ok := session.Values["token"]
if !ok {
return nil
}
var tok oauth2.Token
if err := json.Unmarshal(t.([]byte), &tok); err != nil {
return nil
}
if !tok.Valid() {
return nil
}
return &tok
}
// setAuthTokenCookie marshals the auth token and stores it as a cookie.
func (a *appContext) setAuthTokenCookie(w http.ResponseWriter, r *http.Request, t *oauth2.Token) {
session, _ := a.cookiestore.Get(r, "session")
val, _ := json.Marshal(t)
session.Values["token"] = val
session.Save(r, w)
}
// getAuthStateCookie retrieves the oauth csrf state value from the client request.
func (a *appContext) getAuthStateCookie(r *http.Request) string {
session, _ := a.cookiestore.Get(r, "session")
state, ok := session.Values["state"]
if !ok {
return ""
}
return state.(string)
}
// setAuthStateCookie saves the oauth csrf state value.
func (a *appContext) setAuthStateCookie(w http.ResponseWriter, r *http.Request, state string) {
session, _ := a.cookiestore.Get(r, "session")
session.Values["state"] = state
session.Save(r, w)
}
func (a *appContext) getCurrentURL(r *http.Request) string {
session, _ := a.cookiestore.Get(r, "session")
path, ok := session.Values["auth_url"]
if !ok {
return ""
}
return path.(string)
}
func (a *appContext) setCurrentURL(w http.ResponseWriter, r *http.Request) {
session, _ := a.cookiestore.Get(r, "session")
session.Values["auth_url"] = r.URL.Path
session.Save(r, w)
}
func (a *appContext) isLoggedIn(w http.ResponseWriter, r *http.Request) bool {
tok := a.getAuthTokenCookie(r)
if !tok.Valid() || !a.authprovider.Valid(tok) {
return false
}
return true
}
func (a *appContext) login(w http.ResponseWriter, r *http.Request) (int, error) {
a.setCurrentURL(w, r)
http.Redirect(w, r, "/auth/login", http.StatusSeeOther)
return http.StatusSeeOther, nil
}
// parseKey retrieves and unmarshals the signing request.
func parseKey(r *http.Request) (*lib.SignRequest, error) {
var s lib.SignRequest
if err := json.NewDecoder(r.Body).Decode(&s); err != nil {
return nil, err
}
return &s, nil
}
// signHandler handles the "/sign" path.
// It unmarshals the client token to an oauth token, validates it and signs the provided public ssh key.
func signHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
var t string
if ah := r.Header.Get("Authorization"); ah != "" {
if len(ah) > 6 && strings.ToUpper(ah[0:7]) == "BEARER " {
t = ah[7:]
}
}
if t == "" {
return http.StatusUnauthorized, errors.New(http.StatusText(http.StatusUnauthorized))
}
token := &oauth2.Token{
AccessToken: t,
}
ok := a.authprovider.Valid(token)
if !ok {
return http.StatusUnauthorized, errors.New(http.StatusText(http.StatusUnauthorized))
}
// Sign the pubkey and issue the cert.
req, err := parseKey(r)
if err != nil {
return http.StatusInternalServerError, err
}
username := a.authprovider.Username(token)
a.authprovider.Revoke(token) // We don't need this anymore.
cert, err := a.sshKeySigner.SignUserKey(req, username)
if err != nil {
return http.StatusInternalServerError, err
}
if err := a.certstore.SetCert(cert); err != nil {
log.Printf("Error recording cert: %v", err)
}
json.NewEncoder(w).Encode(&lib.SignResponse{
Status: "ok",
Response: util.GetPublicKey(cert),
})
return http.StatusOK, nil
}
// loginHandler starts the authentication process with the provider.
func loginHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
state := newState()
a.setAuthStateCookie(w, r, state)
a.authsession = a.authprovider.StartSession(state)
http.Redirect(w, r, a.authsession.AuthURL, http.StatusFound)
return http.StatusFound, nil
}
// callbackHandler handles retrieving the access token from the auth provider and saves it for later use.
func callbackHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
if r.FormValue("state") != a.getAuthStateCookie(r) {
return http.StatusUnauthorized, errors.New(http.StatusText(http.StatusUnauthorized))
}
code := r.FormValue("code")
if err := a.authsession.Authorize(a.authprovider, code); err != nil {
return http.StatusInternalServerError, err
}
a.setAuthTokenCookie(w, r, a.authsession.Token)
http.Redirect(w, r, a.getCurrentURL(r), http.StatusFound)
return http.StatusFound, nil
}
// rootHandler starts the auth process. If the client is authenticated it renders the token to the user.
func rootHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
if !a.isLoggedIn(w, r) {
return a.login(w, r)
}
tok := a.getAuthTokenCookie(r)
page := struct {
Token string
}{tok.AccessToken}
tmpl := template.Must(template.New("token.html").Parse(templates.Token))
tmpl.Execute(w, page)
return http.StatusOK, nil
}
func listRevokedCertsHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
revoked, err := a.certstore.GetRevoked()
if err != nil {
return http.StatusInternalServerError, err
}
rl, err := a.sshKeySigner.GenerateRevocationList(revoked)
if err != nil {
return http.StatusInternalServerError, err
}
w.Header().Set("Content-Type", "application/octet-stream")
w.Write(rl)
return http.StatusOK, nil
}
func listAllCertsHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
if !a.isLoggedIn(w, r) {
return a.login(w, r)
}
tmpl := template.Must(template.New("certs.html").Parse(templates.Certs))
tmpl.Execute(w, map[string]interface{}{
csrf.TemplateTag: csrf.TemplateField(r),
})
return http.StatusOK, nil
}
func listCertsJSONHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
if !a.isLoggedIn(w, r) {
return http.StatusUnauthorized, errors.New(http.StatusText(http.StatusUnauthorized))
}
includeExpired, _ := strconv.ParseBool(r.URL.Query().Get("all"))
certs, err := a.certstore.List(includeExpired)
j, err := json.Marshal(certs)
if err != nil {
return http.StatusInternalServerError, errors.New(http.StatusText(http.StatusInternalServerError))
}
w.Write(j)
return http.StatusOK, nil
}
func revokeCertHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
if !a.isLoggedIn(w, r) {
return a.login(w, r)
}
r.ParseForm()
for _, id := range r.Form["cert_id"] {
if err := a.certstore.Revoke(id); err != nil {
return http.StatusInternalServerError, err
}
}
http.Redirect(w, r, "/admin/certs", http.StatusSeeOther)
return http.StatusSeeOther, nil
}
// appHandler is a handler which uses appContext to manage state.
type appHandler struct {
*appContext
h func(*appContext, http.ResponseWriter, *http.Request) (int, error)
}
// ServeHTTP handles the request and writes responses.
func (ah appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
status, err := ah.h(ah.appContext, w, r)
if err != nil {
log.Printf("HTTP %d: %q", status, err)
http.Error(w, err.Error(), status)
}
}
// newState generates a state identifier for the oauth process.
func newState() string {
k := make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, k); err != nil {
return "unexpectedstring"
}
return hex.EncodeToString(k)
}
func readConfig(filename string) (*config.Config, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
return config.ReadConfig(f)
}
func loadCerts(certFile, keyFile string) (tls.Certificate, error) {
key, err := wkfs.ReadFile(keyFile)
if err != nil {
return tls.Certificate{}, err
}
cert, err := wkfs.ReadFile(certFile)
if err != nil {
return tls.Certificate{}, err
}
return tls.X509KeyPair(cert, key)
}
func main() {
// Privileged section
flag.Parse()
config, err := readConfig(*cfg)
if err != nil {
log.Fatal(err)
}
// Register well-known filesystems.
s3fs.Register(config.AWS)
vaultfs.Register(config.Vault)
signer, err := signer.New(config.SSH)
if err != nil {
log.Fatal(err)
}
logfile := os.Stderr
if config.Server.HTTPLogFile != "" {
logfile, err = os.OpenFile(config.Server.HTTPLogFile, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0640)
if err != nil {
log.Fatal(err)
}
}
laddr := fmt.Sprintf("%s:%d", config.Server.Addr, config.Server.Port)
l, err := net.Listen("tcp", laddr)
if err != nil {
log.Fatal(err)
}
tlsConfig := &tls.Config{}
if config.Server.UseTLS {
tlsConfig.Certificates = make([]tls.Certificate, 1)
tlsConfig.Certificates[0], err = loadCerts(config.Server.TLSCert, config.Server.TLSKey)
if err != nil {
log.Fatal(err)
}
l = tls.NewListener(l, tlsConfig)
}
if config.Server.User != "" {
log.Print("Dropping privileges...")
if err := drop.DropPrivileges(config.Server.User); err != nil {
log.Fatal(err)
}
}
// Unprivileged section
var authprovider auth.Provider
switch config.Auth.Provider {
case "google":
authprovider, err = google.New(config.Auth)
case "github":
authprovider, err = github.New(config.Auth)
default:
log.Fatalf("Unknown provider %s\n", config.Auth.Provider)
}
if err != nil {
log.Fatal(err)
}
certstore, err := store.New(config.Server.Database)
if err != nil {
log.Fatal(err)
}
ctx := &appContext{
cookiestore: sessions.NewCookieStore([]byte(config.Server.CookieSecret)),
authprovider: authprovider,
sshKeySigner: signer,
certstore: certstore,
}
ctx.cookiestore.Options = &sessions.Options{
MaxAge: 900,
Path: "/",
Secure: config.Server.UseTLS,
HttpOnly: true,
}
CSRF := csrf.Protect([]byte(config.Server.CSRFSecret), csrf.Secure(config.Server.UseTLS))
r := mux.NewRouter()
r.Methods("GET").Path("/").Handler(appHandler{ctx, rootHandler})
r.Methods("GET").Path("/auth/login").Handler(appHandler{ctx, loginHandler})
r.Methods("GET").Path("/auth/callback").Handler(appHandler{ctx, callbackHandler})
r.Methods("POST").Path("/sign").Handler(appHandler{ctx, signHandler})
r.Methods("GET").Path("/revoked").Handler(appHandler{ctx, listRevokedCertsHandler})
r.Methods("POST").Path("/admin/revoke").Handler(CSRF(appHandler{ctx, revokeCertHandler}))
r.Methods("GET").Path("/admin/certs").Handler(CSRF(appHandler{ctx, listAllCertsHandler}))
r.Methods("GET").Path("/admin/certs.json").Handler(appHandler{ctx, listCertsJSONHandler})
r.PathPrefix("/").Handler(http.FileServer(static.FS(false)))
h := handlers.LoggingHandler(logfile, r)
log.Printf("Starting server on %s", laddr)
s := &http.Server{
Handler: h,
}
log.Fatal(s.Serve(l))
}
|