4 files changed, 554 insertions, 0 deletions
diff --git a/cmd/cashier/client_test.go b/cmd/cashier/client_test.go
new file mode 100644
index 0000000..492f4fc
--- /dev/null
+++ b/cmd/cashier/client_test.go
@@ -0,0 +1,99 @@
+package main
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/rsa"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/nsheridan/cashier/lib"
+	"github.com/nsheridan/cashier/testdata"
+
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+)
+
+func TestLoadCert(t *testing.T) {
+	priv, _ := ssh.ParseRawPrivateKey(testdata.Priv)
+	key := priv.(*rsa.PrivateKey)
+	pub, _ := ssh.NewPublicKey(&key.PublicKey)
+	c := &ssh.Certificate{
+		Key:         pub,
+		CertType:    ssh.UserCert,
+		ValidBefore: ssh.CertTimeInfinity,
+		ValidAfter:  0,
+	}
+	signer, err := ssh.NewSignerFromKey(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.SignCert(rand.Reader, signer)
+	a := agent.NewKeyring()
+	if err := installCert(a, c, key); err != nil {
+		t.Fatal(err)
+	}
+	listedKeys, err := a.List()
+	if err != nil {
+		t.Fatalf("Error reading from agent: %v", err)
+	}
+	if len(listedKeys) != 1 {
+		t.Fatalf("Expected 1 key, got %d", len(listedKeys))
+	}
+	if !bytes.Equal(listedKeys[0].Marshal(), c.Marshal()) {
+		t.Fatal("Certs not equal")
+	}
+}
+
+func TestSignGood(t *testing.T) {
+	res := &lib.SignResponse{
+		Status:   "ok",
+		Response: string(testdata.Cert),
+	}
+	j, _ := json.Marshal(res)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, string(j))
+	}))
+	defer ts.Close()
+	*ca = ts.URL
+	_, err := send([]byte(`{}`), "token")
+	if err != nil {
+		t.Fatal(err)
+	}
+	k, _, _, _, err := ssh.ParseAuthorizedKey(testdata.Pub)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cert, err := sign(k, "token")
+	if cert == nil && err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSignBad(t *testing.T) {
+	res := &lib.SignResponse{
+		Status:   "error",
+		Response: `{"response": "error"}`,
+	}
+	j, _ := json.Marshal(res)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, string(j))
+	}))
+	defer ts.Close()
+	*ca = ts.URL
+	_, err := send([]byte(`{}`), "token")
+	if err != nil {
+		t.Fatal(err)
+	}
+	k, _, _, _, err := ssh.ParseAuthorizedKey(testdata.Pub)
+	if err != nil {
+		t.Fatal(err)
+	}
+	cert, err := sign(k, "token")
+	if cert != nil && err == nil {
+		t.Fatal(err)
+	}
+}
diff --git a/cmd/cashier/keys.go b/cmd/cashier/keys.go
new file mode 100644
index 0000000..a2f95e9
--- /dev/null
+++ b/cmd/cashier/keys.go
@@ -0,0 +1,82 @@
+package main
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"fmt"
+
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
+)
+
+type key interface{}
+type keyfunc func(int) (key, ssh.PublicKey, error)
+
+var (
+	keytypes = map[string]keyfunc{
+		"rsa":     generateRSAKey,
+		"ecdsa":   generateECDSAKey,
+		"ed25519": generateED25519Key,
+	}
+)
+
+func generateED25519Key(bits int) (key, ssh.PublicKey, error) {
+	p, k, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		return nil, nil, err
+	}
+	pub, err := ssh.NewPublicKey(p)
+	if err != nil {
+		return nil, nil, err
+	}
+	return k, pub, nil
+}
+
+func generateRSAKey(bits int) (key, ssh.PublicKey, error) {
+	k, err := rsa.GenerateKey(rand.Reader, bits)
+	if err != nil {
+		return nil, nil, err
+	}
+	pub, err := ssh.NewPublicKey(&k.PublicKey)
+	if err != nil {
+		return nil, nil, err
+	}
+	return k, pub, nil
+}
+
+func generateECDSAKey(bits int) (key, ssh.PublicKey, error) {
+	var curve elliptic.Curve
+	switch bits {
+	case 256:
+		curve = elliptic.P256()
+	case 384:
+		curve = elliptic.P384()
+	case 521:
+		curve = elliptic.P521()
+	default:
+		return nil, nil, fmt.Errorf("Unsupported key size. Valid sizes are '256', '384', '521'")
+	}
+	k, err := ecdsa.GenerateKey(curve, rand.Reader)
+	if err != nil {
+		return nil, nil, err
+	}
+	pub, err := ssh.NewPublicKey(&k.PublicKey)
+	if err != nil {
+		return nil, nil, err
+	}
+	return k, pub, nil
+}
+
+func generateKey(keytype string, bits int) (key, ssh.PublicKey, error) {
+	f, ok := keytypes[keytype]
+	if !ok {
+		var valid []string
+		for k := range keytypes {
+			valid = append(valid, k)
+		}
+		return nil, nil, fmt.Errorf("Unsupported key type %s. Valid choices are %s", keytype, valid)
+	}
+	return f(bits)
+}
diff --git a/cmd/cashier/main.go b/cmd/cashier/main.go
new file mode 100644
index 0000000..8bcc3e7
--- /dev/null
+++ b/cmd/cashier/main.go
@@ -0,0 +1,127 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/nsheridan/cashier/lib"
+	"github.com/pkg/browser"
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+)
+
+var (
+	ca       = flag.String("ca", "http://localhost:10000", "CA server")
+	keybits  = flag.Int("bits", 2048, "Key size. Ignored for ed25519 keys")
+	validity = flag.Duration("validity", time.Hour*24, "Key validity")
+	keytype  = flag.String("key_type", "rsa", "Type of private key to generate - rsa, ecdsa or ed25519")
+)
+
+func installCert(a agent.Agent, cert *ssh.Certificate, key key) error {
+	pubcert := agent.AddedKey{
+		PrivateKey:  key,
+		Certificate: cert,
+		Comment:     cert.KeyId,
+	}
+	if err := a.Add(pubcert); err != nil {
+		return fmt.Errorf("error importing certificate: %s", err)
+	}
+	return nil
+}
+
+func send(s []byte, token string) (*lib.SignResponse, error) {
+	req, err := http.NewRequest("POST", *ca+"/sign", bytes.NewReader(s))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Add("Accept", "application/json")
+	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("Bad response from server: %s", resp.Status)
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	c := &lib.SignResponse{}
+	if err := json.Unmarshal(body, c); err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+func sign(pub ssh.PublicKey, token string) (*ssh.Certificate, error) {
+	marshaled := ssh.MarshalAuthorizedKey(pub)
+	marshaled = marshaled[:len(marshaled)-1]
+	s, err := json.Marshal(&lib.SignRequest{
+		Key:        string(marshaled),
+		ValidUntil: time.Now().Add(*validity),
+	})
+	if err != nil {
+		return nil, err
+	}
+	resp, err := send(s, token)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Status != "ok" {
+		return nil, fmt.Errorf("error: %s", resp.Response)
+	}
+	k, _, _, _, err := ssh.ParseAuthorizedKey([]byte(resp.Response))
+	if err != nil {
+		return nil, err
+	}
+	cert, ok := k.(*ssh.Certificate)
+	if !ok {
+		return nil, fmt.Errorf("did not receive a certificate from server")
+	}
+	return cert, nil
+}
+
+func main() {
+	flag.Parse()
+
+	fmt.Printf("Your browser has been opened to visit %s\n", *ca)
+	if err := browser.OpenURL(*ca); err != nil {
+		fmt.Println("Error launching web browser. Go to the link in your web browser")
+	}
+	fmt.Println("Generating new key pair")
+	priv, pub, err := generateKey(*keytype, *keybits)
+	if err != nil {
+		log.Fatalln("Error generating key pair: ", err)
+	}
+
+	fmt.Print("Enter token: ")
+	var token string
+	fmt.Scanln(&token)
+
+	cert, err := sign(pub, token)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	sock, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK"))
+	if err != nil {
+		log.Fatalln("Error connecting to agent: %s", err)
+	}
+	defer sock.Close()
+	a := agent.NewClient(sock)
+	if err := installCert(a, cert, priv); err != nil {
+		log.Fatalln(err)
+	}
+	fmt.Println("Certificate added.")
+}
diff --git a/cmd/cashierd/main.go b/cmd/cashierd/main.go
new file mode 100644
index 0000000..bc460da
--- /dev/null
+++ b/cmd/cashierd/main.go
@@ -0,0 +1,246 @@
+package main
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"html/template"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+
+	"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"
+)
+
+var (
+	cfg = flag.String("config_file", "config.json", "Path to configuration file.")
+)
+
+// appContext contains local context - cookiestore, authprovider, authsession, templates etc.
+type appContext struct {
+	cookiestore  *sessions.CookieStore
+	authprovider auth.Provider
+	authsession  *auth.Session
+	views        *template.Template
+	sshKeySigner *signer.KeySigner
+}
+
+// getAuthCookie retrieves a cookie from the request and validates it.
+func (a *appContext) getAuthCookie(r *http.Request) *oauth2.Token {
+	session, _ := a.cookiestore.Get(r, "tok")
+	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
+}
+
+// setAuthCookie marshals the auth token and stores it as a cookie.
+func (a *appContext) setAuthCookie(w http.ResponseWriter, r *http.Request, t *oauth2.Token) {
+	session, _ := a.cookiestore.Get(r, "tok")
+	val, _ := json.Marshal(t)
+	session.Values["token"] = val
+	session.Save(r, w)
+}
+
+// parseKey retrieves and unmarshals the signing request.
+func parseKey(r *http.Request) (*lib.SignRequest, error) {
+	var s lib.SignRequest
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(body, &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)
+	req.Principal = a.authprovider.Username(token)
+	a.authprovider.Revoke(token) // We don't need this anymore.
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+	signed, err := a.sshKeySigner.SignUserKey(req)
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+	json.NewEncoder(w).Encode(&lib.SignResponse{
+		Status:   "ok",
+		Response: signed,
+	})
+	return http.StatusOK, nil
+}
+
+// loginHandler starts the authentication process with the provider.
+func loginHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, error) {
+	a.authsession = a.authprovider.StartSession(newState())
+	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.authsession.State {
+		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
+	}
+	// Github tokens don't have an expiry. Set one so that the session expires
+	// after a period.
+	if a.authsession.Token.Expiry.Unix() <= 0 {
+		a.authsession.Token.Expiry = time.Now().Add(1 * time.Hour)
+	}
+	a.setAuthCookie(w, r, a.authsession.Token)
+	http.Redirect(w, 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) {
+	tok := a.getAuthCookie(r)
+	if !tok.Valid() || !a.authprovider.Valid(tok) {
+		http.Redirect(w, r, "/auth/login", http.StatusSeeOther)
+		return http.StatusSeeOther, nil
+	}
+	page := struct {
+		Token string
+	}{tok.AccessToken}
+	a.views.ExecuteTemplate(w, "token.html", page)
+	return http.StatusOK, 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)
+		switch status {
+		case http.StatusNotFound:
+			http.NotFound(w, r)
+		case http.StatusInternalServerError:
+			http.Error(w, http.StatusText(status), status)
+		default:
+			http.Error(w, http.StatusText(status), 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 main() {
+	flag.Parse()
+	config, err := readConfig(*cfg)
+	if err != nil {
+		log.Fatal(err)
+	}
+	signer, err := signer.New(config.SSH)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var authprovider auth.Provider
+	switch config.Auth.Provider {
+	case "google":
+		authprovider = google.New(&config.Auth)
+	case "github":
+		authprovider = github.New(&config.Auth)
+	default:
+		log.Fatalln("Unknown provider %s", config.Auth.Provider)
+	}
+
+	ctx := &appContext{
+		cookiestore:  sessions.NewCookieStore([]byte(config.Server.CookieSecret)),
+		authprovider: authprovider,
+		views:        template.Must(template.ParseGlob("templates/*")),
+		sshKeySigner: signer,
+	}
+	ctx.cookiestore.Options = &sessions.Options{
+		MaxAge:   900,
+		Path:     "/",
+		Secure:   config.Server.UseTLS,
+		HttpOnly: true,
+	}
+
+	m := mux.NewRouter()
+	m.Handle("/", appHandler{ctx, rootHandler})
+	m.Handle("/auth/login", appHandler{ctx, loginHandler})
+	m.Handle("/auth/callback", appHandler{ctx, callbackHandler})
+	m.Handle("/sign", appHandler{ctx, signHandler})
+
+	fmt.Println("Starting server...")
+	l := fmt.Sprintf(":%d", config.Server.Port)
+	if config.Server.UseTLS {
+		log.Fatal(http.ListenAndServeTLS(l, config.Server.TLSCert, config.Server.TLSKey, m))
+	}
+	log.Fatal(http.ListenAndServe(l, m))
+}