Implement token authentication.

README

@@ -91,9 +91,10 @@ optional, but unless you specify at least one user definition (`op`,
 following fields are allowed:
 
  - `op`, `presenter`, `other`: each of these is an array of user
-   definitions (see below) and specifies the users allowed to connect
-   respectively with operator privileges, with presenter privileges, and
-   as passive listeners;
+   definitions (see *Authorisation* below) and specifies the users allowed
+   to connect respectively with operator privileges, with presenter
+   privileges, and as passive listeners;
+ - `authServer` and `authKeys`: see *Authorisation* below;
  - `public`: if true, then the group is visible on the landing page;
  - `displayName`: a human-friendly version of the group name;
  - `description`: a human-readable description of the group; this is
@@ -131,31 +132,53 @@ Supported video codecs include:
 Supported audio codecs include `"opus"`, `"g722"`, `"pcmu"` and `"pcma"`.
 Only Opus can be recorded to disk.  There is no good reason to use
 anything except Opus.
-   
-A user definition is a dictionary with the following fields:
 
- - `username`: the username of the user; if omitted, any username is
-   allowed;
- - `password`: if omitted, then no password is required.  Otherwise, this
-   can either be a string, specifying a plain text password, or
-   a dictionary generated by the `galene-password-generator` utility.
-   
-For example,
+
+## Client Authorisation
+
+Galene implements two authorisation methods: a simple username/password
+authorisation scheme that is built into the Galene server, and
+a token-based mechanism that relies on an external server.  The simple
+mechanism is intended to be used in standalone installations, while the
+server-based mechanism is designed to allow easy integration with an
+existing authorisation infrastructure (such as LDAP, OAuth2, or even Unix
+passwords).
+
+### Password authorisation
+
+When password authorisation is used, authorised usernames and password are
+defined directly in the group configuration file, in the `op`, `presenter`
+and `other` arrays.  Each member of the array is a dictionary, that may
+contain the fields `username` and `password`:
+
+ - if `username` is present, then the entry only matches clients that
+   specify this exact username; otherwise, any username matches;
+ - if `password` is present, then the entry only matches clients that
+   specify this exact password; otherwise, any password matches.
+
+For example, the entry
 
     {"username": "jch", "password": "1234"}
     
-specifies user *jch* with password *1234*, while
+specifies username *jch* with password *1234*, while
 
     {"password": "1234"}
     
-specifies that any (non-empty) username will do, and
+allows any username with password *1234*, and
 
     {}
     
-allows any (non-empty) username with any password.
+allows any username with any password.
+
+By default, empty usernames are forbidden; set the `allow-anonymous`
+option to allow empty usernames.  By default, recording is forbidden;
+specify the `allow-recording` option to allow operators to record.
+
+
+### Hashed passwords
 
 If you don't wish to store cleartext passwords on the server, you may
-generate hashed password with the `galene-password-generator` utility.  A
+generate hashed passwords with the `galene-password-generator` utility.  A
 user entry with a hashed password looks like this:
 
     {
@@ -170,6 +193,39 @@ user entry with a hashed password looks like this:
     }
 
 
+### Authorisation servers
+
+Galene is able to delegate authorisation decisions to an external
+authorisation server.  This makes it possible to integrate Galene with an
+existing authentication and authorisation infrastructure, such as LDAP,
+OAuth2 or even Unix passwords.
+
+When an authorisation server is used, the group configuration file
+specifies the URL of the authorisation server and one or more public keys
+in JWK format:
+
+    {
+        "authServer": "https://auth.example.org",
+        "authKeys": [{
+            "kty": "oct",
+            "alg": "HS256",
+            "k": "MYz3IfCq4Yq-UmPdNqWEOdPl4C_m9imHHs9uveDUJGQ",
+            "kid": "20211030"
+        }, {
+            "kty": "EC",
+            "alg": "ES256",
+            "crv": "P-256",
+            "x": "dElK9qBNyCpRXdvJsn4GdjrFzScSzpkz_I0JhKbYC88",
+            "y": "pBhVb37haKvwEoleoW3qxnT4y5bK35_RTP7_RmFKR6Q",
+            "kid": "20211101"
+        }]
+    }
+
+The `kid` field serves to distinguish among multiple keys, and must match
+the value provided by the authorisation server.  If the server doesn't
+provide a `kid`, the first key with a matching `alg` field will be used.
+
+
 # Further information
 
 Galène's web page is at <https://galene.org>.

README.PROTOCOL

@@ -39,6 +39,11 @@ configuration file.  Each object has the following fields:
  - `locked`: true if the group is locked;
  - `clientCount`: the number of clients currently in the group.
 
+If token-based authorisation is in use for the group, then the dictionary
+contains the following additional field:
+
+ - `authServer`: the URL of the authorisation server.
+
 A client may also fetch the URL `/group/name/.status.json` to retrieve the
 status of a single group.  If the group has not been marked as public,
 then the fields `locked` and `clientCount` are omitted.
@@ -112,6 +117,9 @@ The `join` message requests that the sender join or leave a group:
 }
 ```
 
+If token-based authorisation is beling used, then the `password` field is
+omitted, and a `token` field is included instead.
+
 When the sender has effectively joined the group, the peer will send
 a 'joined' message of kind 'join'; it may then send a 'joined' message of
 kind 'change' at any time, in order to inform the client of a change in
@@ -355,3 +363,37 @@ Finally, a group action requests that the server act on the current group.
 Currently defined kinds include `clearchat` (not to be confused with the
 `clearchat` user message), `lock`, `unlock`, `record`, `unrecord`,
 `subgroups` and `setdata`.
+
+# Authorisation protocol
+
+If a group's status dictionary has a non-empty `authServer` field, then
+the group uses token authentication.  Before joining, the client sends
+a POST request to the authorisation server URL containing in its body
+a JSON dictionary of the following form:
+```javascript
+{
+    "location": "https://galene.example.org/group/groupname",
+    "username": username,
+    "password": password
+}
+```
+If the user is not allowed to join the group, then the authorisation
+server replies with a code of 403 ("not authorised").  If the user is
+allowed to join, then the authorisation server replies with a signed JWT
+(a "JWS") the body of which has the following form:
+```javascript
+{
+    "sub": username,
+    "aud": "https://galene.example.org/group/groupname",
+    "permissions": ["present": true],
+    "iat": now,
+    "exp": now + 30s,
+    "iss": authorisation server URL
+}
+```
+The `permissions` field contains the permissions granted to the client, in
+the same format as in the `joined` message.  Since the client will only
+use the token once, at the very beginning of the session, the tokens
+issued may have a short lifetime (on the order of 30s).
+
+

go.mod

 module github.com/jech/galene
 
-go 1.13
+go 1.15
 
 require (
 	github.com/at-wat/ebml-go v0.16.0
+	github.com/golang-jwt/jwt/v4 v4.2.0
 	github.com/gorilla/websocket v1.4.2
 	github.com/jech/cert v0.0.0-20210819231831-aca735647728
 	github.com/jech/samplebuilder v0.0.0-20220125212352-4553ed6f9a6c

go.sum

@@ -6,6 +6,8 @@ github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0/go.mod h1:fyg7847qk6SyHyPtNmDHnmrv/HOrqktSC+C9fM+CJOE=
+github.com/golang-jwt/jwt/v4 v4.2.0 h1:besgBTC8w8HjP6NzQdxwKH9Z5oQMZ24ThTrHp3cZ8eU=
+github.com/golang-jwt/jwt/v4 v4.2.0/go.mod h1:/xlHOz8bRuivTWchD4jCa+NbatV+wEUSzwAxVc6locg=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.4.0-rc.1/go.mod h1:ceaxUfeHdC40wWswd/P6IGgMaK3YpKi5j83Wpe3EHw8=
 github.com/golang/protobuf v1.4.0-rc.1.0.20200221234624-67d41d38c208/go.mod h1:xKAWHe0F5eneWXFV3EuXVDTCmh+JuBKY0li0aMyXATA=

group/client.go

@@ -92,6 +92,7 @@ type ClientCredentials struct {
 	System   bool
 	Username string
 	Password string
+	Token    string
 }
 
 type Client interface {

group/group.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"log"
+	"net/url"
 	"os"
 	"path"
 	"path/filepath"
@@ -15,6 +16,8 @@ import (
 	"github.com/pion/ice/v2"
 	"github.com/pion/sdp/v3"
 	"github.com/pion/webrtc/v3"
+
+	"github.com/jech/galene/token"
 )
 
 var Directory, DataDirectory string
@@ -960,6 +963,12 @@ type Description struct {
 	// A list of logins for non-presenting users.
 	Other []ClientPattern `json:"other,omitempty"`
 
+	// The URL of the authentication server.
+	AuthServer string `json:"authServer"`
+
+	// The (public) keys of the authentication server
+	AuthKeys []map[string]interface{} `json:"authKeys"`
+
 	// Codec preferences.  If empty, a suitable default is chosen in
 	// the APIFromNames function.
 	Codecs []string `json:"codecs,omitempty"`
@@ -1062,6 +1071,7 @@ func (desc *Description) GetPermission(group string, creds ClientCredentials) (C
 	if !desc.AllowAnonymous && creds.Username == "" {
 		return p, ErrAnonymousNotAuthorised
 	}
+
 	if found, good := matchClient(group, creds, desc.Op); found {
 		if good {
 			p.Op = true
@@ -1086,6 +1096,52 @@ func (desc *Description) GetPermission(group string, creds ClientCredentials) (C
 		}
 		return p, ErrNotAuthorised
 	}
+
+	if desc.AuthServer != "" && creds.Token != "" {
+		aud, perms, err := token.Valid(
+			creds.Username, creds.Token,
+			desc.AuthKeys, desc.AuthServer,
+		)
+		if err != nil {
+			log.Printf("Token authentication: %v", err)
+			return p, ErrNotAuthorised
+		}
+		conf, err := GetConfiguration()
+		if err != nil {
+			log.Printf("Read config.json: %v", err)
+			return p, err
+		}
+		ok := false
+		for _, u := range aud {
+			url, err := url.Parse(u)
+			if err != nil {
+				log.Printf("Token URL: %v", err)
+				continue
+			}
+			// if canonicalHost is not set, we allow tokens
+			// for any domain name.  Hopefully different
+			// servers use distinct keys.
+			if conf.CanonicalHost != "" {
+				if !strings.EqualFold(
+					url.Host, conf.CanonicalHost,
+				) {
+					continue
+				}
+			}
+			if url.Path == path.Join("/group", group)+"/" {
+				ok = true
+				break
+			}
+		}
+		if !ok {
+			return p, ErrNotAuthorised
+		}
+		p.Op, _ = perms["op"].(bool)
+		p.Present, _ = perms["present"].(bool)
+		p.Record, _ = perms["record"].(bool)
+		return p, nil
+	}
+
 	return p, ErrNotAuthorised
 }
 
@@ -1093,6 +1149,7 @@ type Status struct {
 	Name        string `json:"name"`
 	DisplayName string `json:"displayName,omitempty"`
 	Description string `json:"description,omitempty"`
+	AuthServer  string `json:"authServer,omitempty"`
 	Locked      bool   `json:"locked,omitempty"`
 	ClientCount *int   `json:"clientCount,omitempty"`
 }
@@ -1102,6 +1159,7 @@ func (g *Group) Status (authentified bool) Status {
 	d := Status{
 		Name:        g.name,
 		DisplayName: desc.DisplayName,
+		AuthServer:  desc.AuthServer,
 		Description: desc.Description,
 	}
 

rtpconn/webclient.go

@@ -113,6 +113,7 @@ type clientMessage struct {
 	Dest             string                   `json:"dest,omitempty"`
 	Username         string                   `json:"username,omitempty"`
 	Password         string                   `json:"password,omitempty"`
+	Token            string                   `json:"token,omitempty"`
 	Privileged       bool                     `json:"privileged,omitempty"`
 	Permissions      *group.ClientPermissions `json:"permissions,omitempty"`
 	Status           *group.Status            `json:"status,omitempty"`
@@ -1332,6 +1333,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			group.ClientCredentials{
 				Username: m.Username,
 				Password: m.Password,
+				Token:    m.Token,
 			},
 		)
 		if err != nil {

static/galene.js

@@ -271,13 +271,25 @@ function setConnected(connected) {
 }
 
 /** @this {ServerConnection} */
-function gotConnected() {
+async function gotConnected() {
     username = getInputElement('username').value.trim();
     setConnected(true);
+
+    let pw = getInputElement('password').value;
+    getInputElement('password').value = '';
+    let credentials;
+    if(!groupStatus.authServer)
+        credentials = pw;
+    else
+        credentials = {
+            type: 'authServer',
+            authServer: groupStatus.authServer,
+            location: location.href,
+            password: pw,
+        };
+
     try {
-        let pw = getInputElement('password').value;
-        getInputElement('password').value = '';
-        this.join(group, username, pw);
+        await this.join(group, username, credentials);
     } catch(e) {
         console.error(e);
         displayError(e);

static/protocol.js

@@ -205,6 +205,7 @@ function ServerConnection() {
   * @property {string} [dest]
   * @property {string} [username]
   * @property {string} [password]
+  * @property {string} [token]
   * @property {boolean} [privileged]
   * @property {Object<string,boolean>} [permissions]
   * @property {Object<string,any>} [status]
@@ -416,19 +417,52 @@ ServerConnection.prototype.connect = async function(url) {
  *
  * @param {string} group - The name of the group to join.
  * @param {string} username - the username to join as.
- * @param {string} password - the password.
+ * @param {string|Object} credentials - password or authServer.
  * @param {Object<string,any>} [data] - the initial associated data.
  */
-ServerConnection.prototype.join = function(group, username, password, data) {
+ServerConnection.prototype.join = async function(group, username, credentials, data) {
     let m = {
         type: 'join',
         kind: 'join',
         group: group,
         username: username,
-        password: password,
     };
+    if((typeof credentials) === 'string') {
+        m.password = credentials;
+    } else {
+        switch(credentials.type) {
+        case 'password':
+            m.password = credentials.password;
+            break;
+        case 'token':
+            m.token = credentials.token;
+            break;
+        case 'authServer':
+            let r = await fetch(credentials.authServer, {
+                method: "POST",
+                headers: {
+                    "Content-Type": "application/json",
+                },
+                body: JSON.stringify({
+                    location: credentials.location,
+                    username: username,
+                    password: credentials.password,
+                }),
+            });
+            if(!r.ok)
+                throw new Error(
+                    `The authorisation server said: ${r.status} ${r.statusText}`,
+                );
+            m.token = await r.text();
+            break;
+        default:
+            throw new Error(`Unknown credentials type ${credentials.type}`);
+        }
+    }
+
     if(data)
         m.data = data;
+
     this.send(m);
 };
 

token/token.go

+package token
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"encoding/base64"
+	"errors"
+	"math/big"
+
+	"github.com/golang-jwt/jwt/v4"
+)
+
+func parseBase64(k string, d map[string]interface{}) ([]byte, error) {
+	v, ok := d[k].(string)
+	if !ok {
+		return nil, errors.New("key " + k + " not found")
+	}
+	vv, err := base64.RawURLEncoding.DecodeString(v)
+	if err != nil {
+		return nil, err
+	}
+	return vv, nil
+}
+
+func parseKey(key map[string]interface{}) (interface{}, error) {
+	kty, ok := key["kty"].(string)
+	if !ok {
+		return nil, errors.New("kty not found")
+	}
+	alg, ok := key["alg"].(string)
+	if !ok {
+		return nil, errors.New("alg not found")
+	}
+
+	switch kty {
+	case "oct":
+		var length int
+		switch(alg) {
+		case "HS256":
+			length = 32
+		case "HS384":
+			length = 48
+		case "HS512":
+			length = 64
+		default:
+			return nil, errors.New("unknown alg")
+		}
+		k, err := parseBase64("k", key)
+		if err != nil {
+			return nil, err
+		}
+		if len(k) != length {
+			return nil, errors.New("bad length for key")
+		}
+		return k, nil
+	case "EC":
+		if alg != "ES256" {
+			return nil, errors.New("uknown alg")
+		}
+		crv, ok := key["crv"].(string)
+		if !ok {
+			return nil, errors.New("crv not found")
+		}
+		if crv != "P-256" {
+			return nil, errors.New("unknown crv")
+		}
+		curve := elliptic.P256()
+		xbytes, err := parseBase64("x", key)
+		if err != nil {
+			return nil, err
+		}
+		var x big.Int
+		x.SetBytes(xbytes)
+		ybytes, err := parseBase64("y", key)
+		if err != nil {
+			return nil, err
+		}
+		var y big.Int
+		y.SetBytes(ybytes)
+		if !curve.IsOnCurve(&x, &y) {
+			return nil, errors.New("key is not on curve")
+		}
+		return &ecdsa.PublicKey{
+			Curve: curve,
+			X:     &x,
+			Y:     &y,
+		}, nil
+	default:
+		return nil, errors.New("unknown key type")
+	}
+}
+
+func getKey(header map[string]interface{}, keys []map[string]interface{}) (interface{}, error) {
+	alg, _ := header["alg"].(string)
+	kid, _ := header["kid"].(string)
+	for _, k := range keys {
+		kid2, _ := k["kid"].(string)
+		alg2, _ := k["alg"].(string)
+		if (kid == "" || kid == kid2) && alg == alg2 {
+			return parseKey(k)
+		}
+	}
+	return nil, errors.New("key not found")
+}
+
+func Valid(username, token string, keys []map[string]interface{}, issuer string) ([]string, map[string]interface{}, error) {
+	tok, err := jwt.Parse(token, func(t *jwt.Token) (interface{}, error) {
+		return getKey(t.Header, keys)
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+	claims := tok.Claims.(jwt.MapClaims)
+
+	sub, ok := claims["sub"].(string)
+	if !ok || sub != username {
+		return nil, nil, errors.New("invalid 'sub' field")
+	}
+	iss, ok := claims["iss"].(string)
+	if !ok || iss != issuer {
+		return nil, nil, errors.New("invalid 'iss' field")
+	}
+	aud, ok := claims["aud"]
+	var res []string
+	if ok {
+		switch aud := aud.(type) {
+		case string:
+			res = []string{aud}
+		case []string:
+			res = aud
+		}
+	}
+	perms, ok := claims["permissions"].(map[string]interface{})
+	if !ok {
+		return nil, nil, errors.New("invalid 'permissions' field")
+	}
+	return res, perms, nil
+}

token/token_test.go

+package token
+
+import (
+	"crypto/ecdsa"
+	"encoding/json"
+	"testing"
+)
+
+func TestHS256(t *testing.T) {
+	key := `{
+            "kty":"oct",
+            "alg":"HS256",
+            "k":"4S9YZLHK1traIaXQooCnPfBw_yR8j9VEPaAMWAog_YQ"
+        }`
+	var j map[string]interface{}
+	err := json.Unmarshal([]byte(key), &j)
+	if err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+	k, err := parseKey(j)
+	if err != nil {
+		t.Fatalf("parseKey: %v", err)
+	}
+	kk, ok := k.([]byte)
+	if !ok || len(kk) != 32 {
+		t.Errorf("parseKey: got %v", kk)
+	}
+}
+
+func TestES256(t *testing.T) {
+	key := `{
+            "kty":"EC",
+            "alg":"ES256",
+            "crv":"P-256",
+            "x":"dElK9qBNyCpRXdvJsn4GdjrFzScSzpkz_I0JhKbYC88",
+            "y":"pBhVb37haKvwEoleoW3qxnT4y5bK35_RTP7_RmFKR6Q"
+        }`
+	var j map[string]interface{}
+	err := json.Unmarshal([]byte(key), &j)
+	if err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+	k, err := parseKey(j)
+	if err != nil {
+		t.Fatalf("parseKey: %v", err)
+	}
+	kk, ok := k.(*ecdsa.PublicKey)
+	if !ok || kk.Params().Name != "P-256" {
+		t.Errorf("parseKey: got %v", kk)
+	}
+	if !kk.IsOnCurve(kk.X, kk.Y) {
+		t.Errorf("point is not on curve")
+	}
+}

webserver/webserver.go

@@ -86,9 +86,13 @@ func Serve(address string, dataDir string) error {
 	return err
 }
 
-func cspHeader(w http.ResponseWriter) {
+func cspHeader(w http.ResponseWriter, connect string) {
+	c := "connect-src ws: wss: 'self';"
+	if connect != "" {
+		c = "connect-src " + connect + " ws: wss: 'self';"
+	}
 	w.Header().Add("Content-Security-Policy",
-		"connect-src ws: wss: 'self'; img-src data: 'self'; media-src blob: 'self'; default-src 'self'")
+		c + " img-src data: 'self'; media-src blob: 'self'; default-src 'self'")
 }
 
 func notFound(w http.ResponseWriter) {
@@ -172,7 +176,7 @@ func (fh *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	cspHeader(w)
+	cspHeader(w, "")
 	p := r.URL.Path
 	// this ensures any leading .. are removed by path.Clean below
 	if !strings.HasPrefix(p, "/") {
@@ -314,7 +318,8 @@ func groupHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	cspHeader(w)
+	status := g.Status(false)
+	cspHeader(w, status.AuthServer)
 	serveFile(w, r, filepath.Join(StaticRoot, "galene.html"))
 }