mirror of https://github.com/tailscale/tailscale/
ipn/localapi: move cert fetching code to localapi, cache, add cert subcommand
Updates #1235 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>pull/2677/head
Brad Fitzpatrick
3 years ago
parent
4c8b5fdec4
commit
57b794c338
@ -0,0 +1,400 @@
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// Copyright (c) 2021 Tailscale Inc & 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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//go:build !ios && !android
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// +build !ios,!android
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package localapi
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import (
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"bytes"
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"context"
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"crypto"
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/rand"
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"crypto/rsa"
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"crypto/tls"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/json"
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"encoding/pem"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net"
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"net/http"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"time"
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"golang.org/x/crypto/acme"
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"tailscale.com/ipn/ipnstate"
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"tailscale.com/paths"
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"tailscale.com/types/logger"
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)
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func (h *Handler) certDir() (string, error) {
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base := paths.DefaultTailscaledStateFile()
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if base == "" {
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return "", errors.New("no default DefaultTailscaledStateFile")
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}
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full := filepath.Join(filepath.Dir(base), "certs")
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if err := os.MkdirAll(full, 0700); err != nil {
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return "", err
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}
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return full, nil
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}
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var acmeDebug, _ = strconv.ParseBool(os.Getenv("TS_DEBUG_ACME"))
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func (h *Handler) serveCert(w http.ResponseWriter, r *http.Request) {
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if !h.PermitWrite {
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http.Error(w, "cert access denied", http.StatusForbidden)
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return
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}
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dir, err := h.certDir()
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if err != nil {
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h.logf("certDir: %v", err)
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http.Error(w, "failed to get cert dir", 500)
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return
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}
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suff := strings.TrimPrefix(r.URL.Path, "/localapi/v0/cert/")
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if suff == r.URL.Path {
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http.Error(w, "internal handler config wired wrong", 500)
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return
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}
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domain := suff
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mu := &h.certMu
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mu.Lock()
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defer mu.Unlock()
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logf := logger.WithPrefix(h.logf, fmt.Sprintf("cert(%q): ", domain))
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traceACME := func(v interface{}) {
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if !acmeDebug {
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return
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}
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j, _ := json.MarshalIndent(v, "", "\t")
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log.Printf("acme %T: %s", v, j)
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}
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pair, err := h.getCertPEM(r.Context(), logf, traceACME, dir, domain, time.Now())
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if err != nil {
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logf("getCertPEM: %v", err)
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http.Error(w, fmt.Sprint(err), 500)
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return
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}
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w.Header().Set("Content-Type", "text/plain")
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switch r.URL.Query().Get("type") {
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case "", "crt", "cert":
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w.Write(pair.certPEM)
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case "key":
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w.Write(pair.keyPEM)
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case "pair":
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w.Write(pair.keyPEM)
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w.Write(pair.certPEM)
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default:
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http.Error(w, `invalid type; want "cert" (default), "key", or "pair"`, 400)
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}
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}
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type keyPair struct {
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certPEM []byte
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keyPEM []byte
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cached bool
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}
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func (h *Handler) getCertPEM(ctx context.Context, logf logger.Logf, traceACME func(interface{}), dir, domain string, now time.Time) (*keyPair, error) {
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keyFile := filepath.Join(dir, domain+".key")
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certFile := filepath.Join(dir, domain+".crt")
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if keyPEM, err := os.ReadFile(keyFile); err == nil {
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certPEM, _ := os.ReadFile(certFile)
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if validCertPEM(domain, keyPEM, certPEM, now) {
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return &keyPair{certPEM: certPEM, keyPEM: keyPEM, cached: true}, nil
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}
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}
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key, err := acmeKey(dir)
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if err != nil {
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return nil, fmt.Errorf("acmeKey: %w", err)
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}
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ac := &acme.Client{Key: key}
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a, err := ac.GetReg(ctx, "" /* pre-RFC param */)
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switch {
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case err == nil:
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// Great, already registered.
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logf("already had ACME account.")
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case err == acme.ErrNoAccount:
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a, err = ac.Register(ctx, new(acme.Account), acme.AcceptTOS)
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if err == acme.ErrAccountAlreadyExists {
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// Potential race. Double check.
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a, err = ac.GetReg(ctx, "" /* pre-RFC param */)
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}
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if err != nil {
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return nil, fmt.Errorf("acme.Register: %w", err)
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}
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logf("registered ACME account.")
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traceACME(a)
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default:
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return nil, fmt.Errorf("acme.GetReg: %w", err)
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}
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if a.Status != acme.StatusValid {
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return nil, fmt.Errorf("unexpected ACME account status %q", a.Status)
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}
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// Before hitting LetsEncrypt, see if this is a domain that Tailscale will do DNS challenges for.
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st := h.b.StatusWithoutPeers()
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if err := checkCertDomain(st, domain); err != nil {
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return nil, err
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}
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order, err := ac.AuthorizeOrder(ctx, []acme.AuthzID{{Type: "dns", Value: domain}})
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if err != nil {
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return nil, err
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}
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traceACME(order)
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for _, aurl := range order.AuthzURLs {
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az, err := ac.GetAuthorization(ctx, aurl)
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if err != nil {
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return nil, err
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}
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traceACME(az)
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for _, ch := range az.Challenges {
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if ch.Type == "dns-01" {
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rec, err := ac.DNS01ChallengeRecord(ch.Token)
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if err != nil {
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return nil, err
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}
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key := "_acme-challenge." + domain
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var resolver net.Resolver
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var ok bool
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txts, _ := resolver.LookupTXT(ctx, key)
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for _, txt := range txts {
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if txt == rec {
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ok = true
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logf("TXT record already existed")
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break
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}
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}
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if !ok {
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err = h.b.SetDNS(ctx, key, rec)
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if err != nil {
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return nil, fmt.Errorf("SetDNS %q => %q: %w", key, rec, err)
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}
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logf("did SetDNS")
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}
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chal, err := ac.Accept(ctx, ch)
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if err != nil {
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return nil, fmt.Errorf("Accept: %v", err)
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}
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traceACME(chal)
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break
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}
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}
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}
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wait0 := time.Now()
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orderURI := order.URI
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for {
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order, err = ac.WaitOrder(ctx, orderURI)
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if err == nil {
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break
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}
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if oe, ok := err.(*acme.OrderError); ok && oe.Status == acme.StatusInvalid {
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if time.Since(wait0) > 2*time.Minute {
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return nil, errors.New("timeout waiting for order to not be invalid")
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}
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log.Printf("order invalid; waiting...")
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select {
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case <-time.After(5 * time.Second):
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continue
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case <-ctx.Done():
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return nil, ctx.Err()
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}
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}
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return nil, fmt.Errorf("WaitOrder: %v", err)
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}
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traceACME(order)
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certPrivKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
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if err != nil {
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return nil, err
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}
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var privPEM bytes.Buffer
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if err := encodeECDSAKey(&privPEM, certPrivKey); err != nil {
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return nil, err
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}
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if err := ioutil.WriteFile(keyFile, privPEM.Bytes(), 0600); err != nil {
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return nil, err
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}
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csr, err := certRequest(certPrivKey, domain, nil)
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if err != nil {
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return nil, err
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}
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der, _, err := ac.CreateOrderCert(ctx, order.FinalizeURL, csr, true)
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if err != nil {
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return nil, fmt.Errorf("CreateOrder: %v", err)
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}
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var certPEM bytes.Buffer
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for _, b := range der {
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pb := &pem.Block{Type: "CERTIFICATE", Bytes: b}
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if err := pem.Encode(&certPEM, pb); err != nil {
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return nil, err
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}
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}
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if err := ioutil.WriteFile(certFile, certPEM.Bytes(), 0644); err != nil {
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return nil, err
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}
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return &keyPair{certPEM: certPEM.Bytes(), keyPEM: privPEM.Bytes()}, nil
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}
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// certRequest generates a CSR for the given common name cn and optional SANs.
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func certRequest(key crypto.Signer, cn string, ext []pkix.Extension, san ...string) ([]byte, error) {
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req := &x509.CertificateRequest{
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Subject: pkix.Name{CommonName: cn},
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DNSNames: san,
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ExtraExtensions: ext,
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}
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return x509.CreateCertificateRequest(rand.Reader, req, key)
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}
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func encodeECDSAKey(w io.Writer, key *ecdsa.PrivateKey) error {
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b, err := x509.MarshalECPrivateKey(key)
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if err != nil {
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return err
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}
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pb := &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
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return pem.Encode(w, pb)
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}
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// parsePrivateKey is a copy of x/crypto/acme's parsePrivateKey.
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//
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// Attempt to parse the given private key DER block. OpenSSL 0.9.8 generates
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// PKCS#1 private keys by default, while OpenSSL 1.0.0 generates PKCS#8 keys.
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// OpenSSL ecparam generates SEC1 EC private keys for ECDSA. We try all three.
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//
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// Inspired by parsePrivateKey in crypto/tls/tls.go.
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func parsePrivateKey(der []byte) (crypto.Signer, error) {
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if key, err := x509.ParsePKCS1PrivateKey(der); err == nil {
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return key, nil
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}
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if key, err := x509.ParsePKCS8PrivateKey(der); err == nil {
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switch key := key.(type) {
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case *rsa.PrivateKey:
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return key, nil
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case *ecdsa.PrivateKey:
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return key, nil
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default:
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return nil, errors.New("acme/autocert: unknown private key type in PKCS#8 wrapping")
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}
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}
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if key, err := x509.ParseECPrivateKey(der); err == nil {
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return key, nil
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}
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return nil, errors.New("acme/autocert: failed to parse private key")
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}
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func acmeKey(dir string) (crypto.Signer, error) {
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pemName := filepath.Join(dir, "acme-account.key.pem")
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if v, err := ioutil.ReadFile(pemName); err == nil {
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priv, _ := pem.Decode(v)
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if priv == nil || !strings.Contains(priv.Type, "PRIVATE") {
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return nil, errors.New("acme/autocert: invalid account key found in cache")
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}
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return parsePrivateKey(priv.Bytes)
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}
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privKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
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if err != nil {
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return nil, err
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}
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var pemBuf bytes.Buffer
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if err := encodeECDSAKey(&pemBuf, privKey); err != nil {
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return nil, err
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}
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if err := ioutil.WriteFile(pemName, pemBuf.Bytes(), 0600); err != nil {
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return nil, err
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}
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return privKey, nil
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}
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func validCertPEM(domain string, keyPEM, certPEM []byte, now time.Time) bool {
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if len(keyPEM) == 0 || len(certPEM) == 0 {
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return false
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}
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tlsCert, err := tls.X509KeyPair(certPEM, keyPEM)
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if err != nil {
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return false
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}
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var leaf *x509.Certificate
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intermediates := x509.NewCertPool()
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for i, certDER := range tlsCert.Certificate {
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cert, err := x509.ParseCertificate(certDER)
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if err != nil {
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return false
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}
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if i == 0 {
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leaf = cert
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} else {
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intermediates.AddCert(cert)
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}
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}
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if leaf == nil {
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return false
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}
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_, err = leaf.Verify(x509.VerifyOptions{
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DNSName: domain,
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CurrentTime: now,
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Intermediates: intermediates,
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})
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return err == nil
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}
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func checkCertDomain(st *ipnstate.Status, domain string) error {
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if domain == "" {
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return errors.New("missing domain name")
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}
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for _, d := range st.CertDomains {
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if d == domain {
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return nil
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}
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}
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// Transitional way while server doesn't yet populate CertDomains: also permit the client
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// attempting Self.DNSName.
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okay := st.CertDomains[:len(st.CertDomains):len(st.CertDomains)]
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if st.Self != nil {
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if v := strings.Trim(st.Self.DNSName, "."); v != "" {
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if v == domain {
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return nil
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}
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okay = append(okay, v)
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}
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}
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switch len(okay) {
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case 0:
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return errors.New("your Tailscale account does not support getting TLS certs")
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case 1:
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return fmt.Errorf("invalid domain %q; only %q is permitted", domain, okay[0])
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default:
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return fmt.Errorf("invalid domain %q; must be one of %q", domain, okay)
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}
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}
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@ -0,0 +1,17 @@
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// Copyright (c) 2021 Tailscale Inc & 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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//go:build ios || android
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// +build ios android
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package localapi
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import (
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"net/http"
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"runtime"
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)
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func (h *Handler) serveCert(w http.ResponseWriter, r *http.Request) {
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http.Error(w, "disabled on "+runtime.GOOS, http.StatusNotFound)
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}
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