mirror of
https://github.com/tailscale/tailscale.git
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d72722b5b2
Change-Id: I4af086878f8f7fb7b579844125f9eae352ca4115 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
543 lines
15 KiB
Go
543 lines
15 KiB
Go
// The tsidp command is an OpenID Connect Identity Provider server.
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package main
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import (
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"context"
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crand "crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/base64"
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"encoding/binary"
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"encoding/json"
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"encoding/pem"
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"flag"
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"fmt"
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"io"
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"log"
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"net/http"
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"net/netip"
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"net/url"
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"os"
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"strings"
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"sync"
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"time"
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"gopkg.in/square/go-jose.v2"
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"gopkg.in/square/go-jose.v2/jwt"
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"tailscale.com/client/tailscale"
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"tailscale.com/client/tailscale/apitype"
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"tailscale.com/tailcfg"
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"tailscale.com/tsnet"
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"tailscale.com/tsweb"
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"tailscale.com/types/key"
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"tailscale.com/types/lazy"
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"tailscale.com/types/logger"
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"tailscale.com/types/views"
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"tailscale.com/util/mak"
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"tailscale.com/util/must"
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"tailscale.com/util/rands"
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)
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var (
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flagVerbose = flag.Bool("verbose", false, "be verbose")
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)
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func main() {
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flag.Parse()
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ctx := context.Background()
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ts := &tsnet.Server{
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Hostname: "idp",
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}
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if !*flagVerbose {
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ts.Logf = logger.Discard
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}
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st, err := ts.Up(ctx)
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if err != nil {
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log.Fatal(err)
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}
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lc, err := ts.LocalClient()
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if err != nil {
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log.Fatalf("getting local client: %v", err)
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}
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srv := &idpServer{
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lc: lc,
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serverURL: "https://" + strings.TrimSuffix(st.Self.DNSName, "."),
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}
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log.Printf("Running tsidp at %s ...", srv.serverURL)
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ln, err := ts.ListenTLS("tcp", ":443")
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if err != nil {
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log.Fatal(err)
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}
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log.Fatal(http.Serve(ln, srv))
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}
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type idpServer struct {
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lc *tailscale.LocalClient
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serverURL string // "https://foo.bar.ts.net"
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lazySigningKey lazy.SyncValue[*signingKey]
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lazySigner lazy.SyncValue[jose.Signer]
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mu sync.Mutex // guards the fields below
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code map[string]*authRequest
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accessToken map[string]*authRequest
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}
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type authRequest struct {
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nonce string
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redirectURI string
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who *apitype.WhoIsResponse
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validTill time.Time
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}
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func (s *idpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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log.Printf("%v %v", r.Method, r.URL)
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if r.URL.Path == oidcJWKSPath {
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if err := s.serveJWKS(w, r); err != nil {
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log.Printf("Error serving JWKS: %v", err)
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}
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return
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}
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if r.URL.Path == oidcConfigPath {
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if err := s.serveOpenIDConfig(w, r); err != nil {
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log.Printf("Error serving OpenID config: %v", err)
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}
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return
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}
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if r.URL.Path == "/" {
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io.WriteString(w, "<html><body><h1>Tailscale OIDC IdP</h1>")
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return
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}
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if r.URL.Path == "/authorize" {
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who, err := s.lc.WhoIs(r.Context(), r.RemoteAddr)
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if err != nil {
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log.Printf("Error getting WhoIs: %v", err)
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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uq := r.URL.Query()
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code := rands.HexString(32)
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ar := &authRequest{
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nonce: uq.Get("nonce"),
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who: who,
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redirectURI: uq.Get("redirect_uri"),
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}
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s.mu.Lock()
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mak.Set(&s.code, code, ar)
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s.mu.Unlock()
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q := make(url.Values)
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q.Set("code", code)
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q.Set("state", uq.Get("state"))
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u := uq.Get("redirect_uri") + "?" + q.Encode()
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log.Printf("Redirecting to %q", u)
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http.Redirect(w, r, u, http.StatusFound)
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return
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}
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if r.URL.Path == "/userinfo" {
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s.serveUserInfo(w, r)
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return
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}
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if r.URL.Path == "/token" {
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s.serveToken(w, r)
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return
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}
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http.Error(w, "tsidp: not found", http.StatusNotFound)
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}
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func (s *idpServer) serveUserInfo(w http.ResponseWriter, r *http.Request) {
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if r.Method != "GET" {
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http.Error(w, "tsidp: method not allowed", http.StatusMethodNotAllowed)
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return
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}
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tk, ok := strings.CutPrefix(r.Header.Get("Authorization"), "Bearer ")
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if !ok {
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http.Error(w, "tsidp: invalid Authorization header", http.StatusBadRequest)
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return
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}
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s.mu.Lock()
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ar, ok := s.accessToken[tk]
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s.mu.Unlock()
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if !ok {
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http.Error(w, "tsidp: invalid token", http.StatusBadRequest)
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return
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}
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if ar.validTill.Before(time.Now()) {
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http.Error(w, "tsidp: token expired", http.StatusBadRequest)
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s.mu.Lock()
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delete(s.accessToken, tk)
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s.mu.Unlock()
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}
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ui := userInfo{}
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if ar.who.Node.IsTagged() {
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http.Error(w, "tsidp: tagged nodes not supported", http.StatusBadRequest)
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return
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}
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ui.Sub = ar.who.Node.User.String()
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ui.Name = ar.who.UserProfile.DisplayName
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ui.Email = ar.who.UserProfile.LoginName
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ui.Picture = ar.who.UserProfile.ProfilePicURL
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// TODO(maisem): not sure if this is the right thing to do
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ui.UserName, _, _ = strings.Cut(ar.who.UserProfile.LoginName, "@")
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w.Header().Set("Content-Type", "application/json")
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if err := json.NewEncoder(w).Encode(ui); err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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}
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}
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type userInfo struct {
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Sub string `json:"sub"`
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Name string `json:"name"`
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Email string `json:"email"`
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Picture string `json:"picture"`
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UserName string `json:"username"`
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}
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func (s *idpServer) serveToken(w http.ResponseWriter, r *http.Request) {
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if r.Method != "POST" {
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http.Error(w, "tsidp: method not allowed", http.StatusMethodNotAllowed)
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return
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}
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// TODO: check who is making the request
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if r.FormValue("grant_type") != "authorization_code" {
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http.Error(w, "tsidp: grant_type not supported", http.StatusBadRequest)
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return
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}
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code := r.FormValue("code")
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if code == "" {
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http.Error(w, "tsidp: code is required", http.StatusBadRequest)
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return
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}
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s.mu.Lock()
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ar, ok := s.code[code]
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delete(s.code, code)
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s.mu.Unlock()
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if !ok {
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http.Error(w, "tsidp: code not found", http.StatusBadRequest)
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return
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}
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if ar.redirectURI != r.FormValue("redirect_uri") {
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http.Error(w, "tsidp: redirect_uri mismatch", http.StatusBadRequest)
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return
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}
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signer, err := s.oidcSigner()
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if err != nil {
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log.Printf("Error getting signer: %v", err)
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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jti := rands.HexString(32)
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who := ar.who
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// TODO(maisem): not sure if this is the right thing to do
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userName, _, _ := strings.Cut(ar.who.UserProfile.LoginName, "@")
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n := who.Node.View()
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if n.IsTagged() {
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http.Error(w, "tsidp: tagged nodes not supported", http.StatusBadRequest)
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return
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}
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now := time.Now()
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_, tcd, _ := strings.Cut(n.Name(), ".")
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tsClaims := tailscaleClaims{
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Claims: jwt.Claims{
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Audience: jwt.Audience{"unused"},
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Expiry: jwt.NewNumericDate(now.Add(5 * time.Minute)),
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ID: jti,
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IssuedAt: jwt.NewNumericDate(now),
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Issuer: s.serverURL,
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NotBefore: jwt.NewNumericDate(now),
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Subject: n.User().String(),
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},
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Nonce: ar.nonce,
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Key: n.Key(),
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Addresses: n.Addresses(),
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NodeID: n.ID(),
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NodeName: n.Name(),
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Tailnet: tcd,
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UserID: n.User(),
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Email: who.UserProfile.LoginName,
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UserName: userName,
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}
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// Create an OIDC token using this issuer's signer.
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token, err := jwt.Signed(signer).Claims(tsClaims).CompactSerialize()
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if err != nil {
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log.Printf("Error getting token: %v", err)
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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at := rands.HexString(32)
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s.mu.Lock()
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ar.validTill = now.Add(5 * time.Minute)
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mak.Set(&s.accessToken, at, ar)
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s.mu.Unlock()
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w.Header().Set("Content-Type", "application/json")
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if err := json.NewEncoder(w).Encode(oidcTokenResponse{
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AccessToken: at,
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TokenType: "Bearer",
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ExpiresIn: 5 * 60,
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IDToken: token,
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}); err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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}
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}
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type oidcTokenResponse struct {
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IDToken string `json:"id_token"`
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TokenType string `json:"token_type"`
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AccessToken string `json:"access_token"`
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RefreshToken string `json:"refresh_token"`
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ExpiresIn int `json:"expires_in"`
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}
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const (
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oidcJWKSPath = "/.well-known/jwks.json"
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oidcConfigPath = "/.well-known/openid-configuration"
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)
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func (s *idpServer) oidcSigner() (jose.Signer, error) {
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return s.lazySigner.GetErr(func() (jose.Signer, error) {
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sk, err := s.oidcPrivateKey()
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if err != nil {
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return nil, err
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}
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return jose.NewSigner(jose.SigningKey{
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Algorithm: jose.RS256,
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Key: sk.k,
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}, &jose.SignerOptions{EmbedJWK: false, ExtraHeaders: map[jose.HeaderKey]interface{}{
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jose.HeaderType: "JWT",
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"kid": fmt.Sprint(sk.kid),
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}})
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})
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}
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func (s *idpServer) oidcPrivateKey() (*signingKey, error) {
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return s.lazySigningKey.GetErr(func() (*signingKey, error) {
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var sk signingKey
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b, err := os.ReadFile("oidc-key.json")
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if err == nil {
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if err := sk.UnmarshalJSON(b); err == nil {
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return &sk, nil
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} else {
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log.Printf("Error unmarshaling key: %v", err)
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}
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}
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id, k := mustGenRSAKey(2048)
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sk.k = k
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sk.kid = id
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b, err = sk.MarshalJSON()
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if err != nil {
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log.Fatalf("Error marshaling key: %v", err)
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}
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if err := os.WriteFile("oidc-key.json", b, 0600); err != nil {
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log.Fatalf("Error writing key: %v", err)
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}
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return &sk, nil
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})
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}
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func (s *idpServer) serveJWKS(w http.ResponseWriter, r *http.Request) error {
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if r.URL.Path != oidcJWKSPath {
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return tsweb.Error(404, "", nil)
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}
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w.Header().Set("Content-Type", "application/json")
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sk, err := s.oidcPrivateKey()
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if err != nil {
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return tsweb.Error(500, err.Error(), err)
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}
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// TODO(maisem): maybe only marshal this once and reuse?
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// TODO(maisem): implement key rotation.
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je := json.NewEncoder(w)
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je.SetIndent("", " ")
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if err := je.Encode(jose.JSONWebKeySet{
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Keys: []jose.JSONWebKey{
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{
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Key: sk.k.Public(),
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Algorithm: string(jose.RS256),
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Use: "sig",
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KeyID: fmt.Sprint(sk.kid),
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},
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},
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}); err != nil {
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return tsweb.Error(500, err.Error(), err)
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}
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return nil
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}
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// openIDProviderMetadata is a partial representation of
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// https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata.
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type openIDProviderMetadata struct {
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Issuer string `json:"issuer"`
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AuthorizationEndpoint string `json:"authorization_endpoint,omitempty"`
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TokenEndpoint string `json:"token_endpoint,omitempty"`
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UserInfoEndpoint string `json:"userinfo_endpoint,omitempty"`
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JWKS_URI string `json:"jwks_uri"`
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ScopesSupported views.Slice[string] `json:"scopes_supported"`
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ResponseTypesSupported views.Slice[string] `json:"response_types_supported"`
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SubjectTypesSupported views.Slice[string] `json:"subject_types_supported"`
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ClaimsSupported views.Slice[string] `json:"claims_supported"`
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IDTokenSigningAlgValuesSupported views.Slice[string] `json:"id_token_signing_alg_values_supported"`
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// TODO(maisem): maybe add other fields?
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// Currently we fill out the REQUIRED fields, scopes_supported and claims_supported.
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}
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type tailscaleClaims struct {
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jwt.Claims `json:",inline"`
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Nonce string `json:"nonce,omitempty"` // the nonce from the request
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Key key.NodePublic `json:"key"` // the node public key
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Addresses views.Slice[netip.Prefix] `json:"addresses"` // the Tailscale IPs of the node
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NodeID tailcfg.NodeID `json:"nid"` // the stable node ID
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NodeName string `json:"node"` // name of the node
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Tailnet string `json:"tailnet"` // tailnet (like tail-scale.ts.net)
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// Tags is the list of tags the node is tagged with prefixed with the Tailnet name.
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Tags []string `json:"tags,omitempty"` // the tags on the node (like alice.github:tag:foo or example.com:tag:foo)
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// Email is the emailish of the user prefixed with the Tailnet name.
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Email string `json:"email,omitempty"` // user emailish (like alice.github:alice@github or example.com:bob@example.com)
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UserID tailcfg.UserID `json:"uid,omitempty"` // user legacy id
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UserName string `json:"username,omitempty"` // user name
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}
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var (
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openIDSupportedClaims = views.SliceOf([]string{
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// Standard claims, these correspond to fields in jwt.Claims.
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"sub", "aud", "exp", "iat", "iss", "jti", "nbf", "username", "email",
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// Tailscale claims, these correspond to fields in tailscaleClaims.
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"key", "addresses", "nid", "node", "tailnet", "tags", "user", "uid",
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})
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// As defined in the OpenID spec this should be "openid".
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openIDSupportedScopes = views.SliceOf([]string{"openid", "email", "profile"})
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// We only support getting the id_token.
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openIDSupportedReponseTypes = views.SliceOf([]string{"id_token", "code"})
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// The type of the "sub" field in the JWT, which means it is globally unique identifier.
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// The other option is "pairwise", which means the identifier is different per receiving 3p.
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openIDSupportedSubjectTypes = views.SliceOf([]string{"public"})
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// The algo used for signing. The OpenID spec says "The algorithm RS256 MUST be included."
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// https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata
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openIDSupportedSigningAlgos = views.SliceOf([]string{string(jose.RS256)})
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)
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func (s *idpServer) serveOpenIDConfig(w http.ResponseWriter, r *http.Request) error {
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if r.URL.Path != oidcConfigPath {
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return tsweb.Error(404, "", nil)
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}
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w.Header().Set("Content-Type", "application/json")
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je := json.NewEncoder(w)
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je.SetIndent("", " ")
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if err := je.Encode(openIDProviderMetadata{
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Issuer: s.serverURL,
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JWKS_URI: s.serverURL + oidcJWKSPath,
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UserInfoEndpoint: s.serverURL + "/userinfo",
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AuthorizationEndpoint: s.serverURL + "/authorize", // TODO: add /<nodeid> suffix
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TokenEndpoint: s.serverURL + "/token",
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ScopesSupported: openIDSupportedScopes,
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ResponseTypesSupported: openIDSupportedReponseTypes,
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SubjectTypesSupported: openIDSupportedSubjectTypes,
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ClaimsSupported: openIDSupportedClaims,
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IDTokenSigningAlgValuesSupported: openIDSupportedSigningAlgos,
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}); err != nil {
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log.Printf("Error encoding JSON: %v", err)
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http.Error(w, err.Error(), http.StatusInternalServerError)
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}
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return nil
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}
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const (
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minimumRSAKeySize = 2048
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)
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// mustGenRSAKey generates a new RSA key with the provided number of bits. It
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// panics on failure. bits must be at least minimumRSAKeySizeBytes * 8.
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func mustGenRSAKey(bits int) (kid uint64, k *rsa.PrivateKey) {
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if bits < minimumRSAKeySize {
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panic("request to generate a too-small RSA key")
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}
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kid = must.Get(readUint64(crand.Reader))
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k = must.Get(rsa.GenerateKey(crand.Reader, bits))
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return
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}
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// readUint64 reads from r until 8 bytes represent a non-zero uint64.
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func readUint64(r io.Reader) (uint64, error) {
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for {
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var b [8]byte
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if _, err := io.ReadFull(r, b[:]); err != nil {
|
|
return 0, err
|
|
}
|
|
if v := binary.BigEndian.Uint64(b[:]); v != 0 {
|
|
return v, nil
|
|
}
|
|
}
|
|
}
|
|
|
|
// rsaPrivateKeyJSONWrapper is the the JSON serialization
|
|
// format used by RSAPrivateKey.
|
|
type rsaPrivateKeyJSONWrapper struct {
|
|
Key string
|
|
ID uint64
|
|
}
|
|
|
|
type signingKey struct {
|
|
k *rsa.PrivateKey
|
|
kid uint64
|
|
}
|
|
|
|
func (sk *signingKey) MarshalJSON() ([]byte, error) {
|
|
b := pem.Block{
|
|
Type: "RSA PRIVATE KEY",
|
|
Bytes: x509.MarshalPKCS1PrivateKey(sk.k),
|
|
}
|
|
bts := pem.EncodeToMemory(&b)
|
|
return json.Marshal(rsaPrivateKeyJSONWrapper{
|
|
Key: base64.URLEncoding.EncodeToString(bts),
|
|
ID: sk.kid,
|
|
})
|
|
}
|
|
|
|
func (sk *signingKey) UnmarshalJSON(b []byte) error {
|
|
var wrapper rsaPrivateKeyJSONWrapper
|
|
if err := json.Unmarshal(b, &wrapper); err != nil {
|
|
return err
|
|
}
|
|
if len(wrapper.Key) == 0 {
|
|
return nil
|
|
}
|
|
b64dec, err := base64.URLEncoding.DecodeString(wrapper.Key)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
blk, _ := pem.Decode(b64dec)
|
|
k, err := x509.ParsePKCS1PrivateKey(blk.Bytes)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
sk.k = k
|
|
sk.kid = wrapper.ID
|
|
return nil
|
|
}
|