Signed and Authenticated Static Photo URLs

* Add support for authenticated static photo URLs, leveraging the NGINX module
  ngx_http_auth_request. The README is updated with an example NGINX config
  how to set this up on the proxy side.
* In settings.json a new SignedPhoto section is added: not enabled by default.
* PhotoURL will append a ?jwt= token to the /static/photos/ path for the
  current user, which expires after 30 seconds.
* When SignedPhoto is enabled, it will enforce that the JWT token is valid and
  matches the username of the current logged-in user, or else will return with
  a 403 Forbidden error.

README.md

@@ -20,20 +20,6 @@ The website can also run out of a local SQLite database which is convenient
 for local development. The production server runs on PostgreSQL and the
 web app is primarily designed for that.
 
-### PostGIS Extension for PostgreSQL
-
-For the "Who's Nearby" feature to work you will need a PostgreSQL
-database with the PostGIS geospatial extension installed. Usually
-it might be a matter of `dnf install postgis` and activating the
-extension on your nonshy database as your superuser (postgres):
-
-```psql
-create extension postgis;
-```
-
-If you get errors like "Type geography not found" from Postgres when
-running distance based searches, this is the likely culprit.
-
 ## Building the App
 
 This app is written in Go: [go.dev](https://go.dev). You can probably
@@ -61,6 +47,96 @@ a database.
 For simple local development, just set `"UseSQLite": true` and the
 app will run with a SQLite database.
 
+### Postgres is Highly Recommended
+
+This website is intended to run under PostgreSQL and some of its
+features leverage Postgres specific extensions. For quick local
+development, SQLite will work fine but some website features will
+be disabled and error messages given. These include:
+
+* Location features such as "Who's Nearby" (PostGIS extension)
+* "Newest" tab on the forums: to deduplicate comments by most recent
+  thread depends on Postgres, SQLite will always show all latest
+  comments without deduplication.
+
+### PostGIS Extension for PostgreSQL
+
+For the "Who's Nearby" feature to work you will need a PostgreSQL
+database with the PostGIS geospatial extension installed. Usually
+it might be a matter of `dnf install postgis` and activating the
+extension on your nonshy database as your superuser (postgres):
+
+```psql
+create extension postgis;
+```
+
+If you get errors like "Type geography not found" from Postgres when
+running distance based searches, this is the likely culprit.
+
+### Signed Photo URLs (NGINX)
+
+The website supports "signed photo" URLs that can help protect the direct
+links to user photos (their /static/photos/*.jpg paths) to ensure only
+logged-in and authorized users are able to access those links.
+
+This feature is not enabled (enforcing) by default, as it relies on
+cooperation with the NGINX reverse proxy server
+(module ngx_http_auth_request).
+
+In your NGINX config, set your /static/ path to leverage NGINX auth_request
+like so:
+
+```nginx
+server {
+    # your boilerplate server info (SSL, etc.) - not relevant to this example.
+    listen 80 default_server;
+    listen [::]:80 default_server;
+
+    # Relevant: setting the /static/ URL on NGINX to be an alias to your local
+    # nonshy static folder on disk. In this example, the git clone for the
+    # website was at /home/www-user/git/nonshy/website, so that ./web/static/
+    # is the local path where static files (e.g., photos) are uploaded.
+    location /static/ {
+        # Important: auth_request tells NGINX to do subrequest authentication
+        # on requests into the /static/ URI of your website.
+        auth_request /static-auth;
+
+        # standard NGINX alias commands.
+        alias /home/www-user/git/nonshy/website/web/static/;
+        autoindex off;
+    }
+
+    # Configure the internal subrequest auth path.
+    # Note: the path "/static-auth" can be anything you want.
+    location = /static-auth {
+        internal;  # this is an internal route for NGINX only, not public
+
+        # Proxy to the /v1/auth/static URL on the web app.
+        # This line assumes the website runs on localhost:8080.
+        proxy_pass http://localhost:8080/v1/auth/static;
+        proxy_pass_request_body off;
+        proxy_set_header Content-Length "";
+
+        # Important: the X-Original-URI header tells the web app what the
+        # original path (e.g. /static/photos/*) was, so the web app knows
+        # which sub-URL to enforce authentication on.
+        proxy_set_header X-Original-URI $request_uri;
+    }
+}
+```
+
+When your NGINX config is set up like the above, you can edit the
+settings.json to mark SignedPhoto/Enabled=true, and restart the
+website. Be sure to test it!
+
+On a photo gallery view, all image URLs under /static/photos/ should
+come with a ?jwt= parameter, and the image should load for the current
+user. The JWT token is valid for 30 seconds after which the direct link
+to the image should expire and give a 403 Forbidden response.
+
+When this feature is NOT enabled/not enforcing: the jwt= parameter is
+still generated on photo URLs but is not enforced by the web app.
+
 ## Usage
 
 The `nonshy` binary has sub-commands to either run the web server

pkg/config/config.go

@@ -38,6 +38,9 @@ const (
 
 	TwoFactorBackupCodeCount  = 12
 	TwoFactorBackupCodeLength = 8 // characters a-z0-9
+
+	// Signed URLs for static photo authentication.
+	SignedPhotoJWTExpires = 30 * time.Second
 )
 
 // Authentication

pkg/config/variable.go

@@ -15,7 +15,7 @@ import (
 
 // Version of the config format - when new fields are added, it will attempt
 // to write the settings.toml to disk so new defaults populate.
-var currentVersion = 4
+var currentVersion = 5
 
 // Current loaded settings.json
 var Current = DefaultVariable()
@@ -32,6 +32,7 @@ type Variable struct {
 	BareRTC          BareRTC
 	Maintenance      Maintenance
 	Encryption       Encryption
+	SignedPhoto      SignedPhoto
 	WebPush          WebPush
 	Turnstile        Turnstile
 	UseXForwardedFor bool
@@ -126,6 +127,12 @@ func LoadSettings() {
 		writeSettings = true
 	}
 
+	// Initialize JWT token for SignedPhoto feature.
+	if Current.SignedPhoto.JWTSecret == "" {
+		Current.SignedPhoto.JWTSecret = uuid.New().String()
+		writeSettings = true
+	}
+
 	// Have we added new config fields? Save the settings.json.
 	if Current.Version != currentVersion || writeSettings {
 		log.Warn("New options are available for your settings.json file. Your settings will be re-saved now.")
@@ -196,6 +203,12 @@ type Encryption struct {
 	ColdStorageRSAPublicKey []byte
 }
 
+// SignedPhoto settings.
+type SignedPhoto struct {
+	Enabled   bool
+	JWTSecret string
+}
+
 // WebPush settings.
 type WebPush struct {
 	VAPIDPublicKey  string

pkg/controller/api/static_auth.go

@@ -0,0 +1,84 @@
+package api
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"code.nonshy.com/nonshy/website/pkg/config"
+	"code.nonshy.com/nonshy/website/pkg/encryption"
+	"code.nonshy.com/nonshy/website/pkg/session"
+	"github.com/golang-jwt/jwt/v4"
+)
+
+// StaticAuth API protects paths like /static/photos/ to authenticated user requests only.
+func StaticAuth() http.HandlerFunc {
+	type Response struct {
+		Success  bool   `json:"success"`
+		Error    string `json:",omitempty"`
+		Username string `json:"username"`
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// We only protect the /static/photos subpath.
+		// And check if the SignedPhoto feature is enabled and enforcing.
+		var originalURI = r.Header.Get("X-Original-URI")
+		if !config.Current.SignedPhoto.Enabled || !strings.HasPrefix(originalURI, config.PhotoWebPath) {
+			SendJSON(w, http.StatusOK, Response{
+				Success: true,
+			})
+			return
+		}
+
+		// Parse the JWT token parameter from the original URL.
+		var token string
+		if path, err := url.Parse(originalURI); err == nil {
+			query := path.Query()
+			token = query.Get("jwt")
+		}
+
+		// The token is required from here.
+		if token == "" {
+			SendJSON(w, http.StatusForbidden, Response{
+				Error: "JWT token is required",
+			})
+			return
+		}
+
+		// Check if we're logged in.
+		currentUser, err := session.CurrentUser(r)
+		if err != nil {
+			SendJSON(w, http.StatusForbidden, Response{
+				Error: "Login Required",
+			})
+			return
+		}
+
+		// Validate the JWT token.
+		claims, ok, err := encryption.ValidateClaims(
+			token,
+			[]byte(config.Current.SignedPhoto.JWTSecret),
+			&jwt.RegisteredClaims{},
+		)
+		if !ok || err != nil {
+			SendJSON(w, http.StatusForbidden, Response{
+				Error: fmt.Sprintf("JWT claims: %v", err),
+			})
+			return
+		}
+
+		// Sanity check that the username in these claims is the same as the viewer.
+		if c, ok := claims.(*jwt.RegisteredClaims); !ok || c.Subject != currentUser.Username {
+			SendJSON(w, http.StatusForbidden, Response{
+				Error: "That photo was not for you",
+			})
+			return
+		}
+
+		SendJSON(w, http.StatusOK, Response{
+			Success:  true,
+			Username: currentUser.Username,
+		})
+	})
+}

pkg/controller/chat/chat.go

@@ -3,7 +3,6 @@ package chat
 import (
 	"bytes"
 	"encoding/json"
-	"fmt"
 	"io"
 	"net/http"
 	"sort"
@@ -11,6 +10,7 @@ import (
 	"time"
 
 	"code.nonshy.com/nonshy/website/pkg/config"
+	"code.nonshy.com/nonshy/website/pkg/encryption"
 	"code.nonshy.com/nonshy/website/pkg/geoip"
 	"code.nonshy.com/nonshy/website/pkg/log"
 	"code.nonshy.com/nonshy/website/pkg/middleware"
@@ -22,7 +22,7 @@ import (
 	"github.com/golang-jwt/jwt/v4"
 )
 
-// JWT claims.
+// Claims are the JWT claims for the BareRTC chat room.
 type Claims struct {
 	// Custom claims.
 	IsAdmin    bool     `json:"op,omitempty"`
@@ -123,25 +123,17 @@ func Landing() http.HandlerFunc {
 
 			// Create the JWT claims.
 			claims := Claims{
-				IsAdmin:    currentUser.HasAdminScope(config.ScopeChatModerator),
+				IsAdmin:          currentUser.HasAdminScope(config.ScopeChatModerator),
-				Avatar:     avatar,
+				Avatar:           avatar,
-				ProfileURL: "/u/" + currentUser.Username,
+				ProfileURL:       "/u/" + currentUser.Username,
-				Nickname:   currentUser.NameOrUsername(),
+				Nickname:         currentUser.NameOrUsername(),
-				Emoji:      emoji,
+				Emoji:            emoji,
-				Gender:     Gender(currentUser),
+				Gender:           Gender(currentUser),
-				VIP:        isShy, // "shy accounts" use the "VIP" status for special icon in chat
+				VIP:              isShy, // "shy accounts" use the "VIP" status for special icon in chat
-				Rules:      rules,
+				Rules:            rules,
-				RegisteredClaims: jwt.RegisteredClaims{
+				RegisteredClaims: encryption.StandardClaims(currentUser.ID, currentUser.Username, 5*time.Minute),
-					ExpiresAt: jwt.NewNumericDate(time.Now().Add(5 * time.Minute)),
-					IssuedAt:  jwt.NewNumericDate(time.Now()),
-					NotBefore: jwt.NewNumericDate(time.Now()),
-					Issuer:    config.Title,
-					Subject:   currentUser.Username,
-					ID:        fmt.Sprintf("%d", currentUser.ID),
-				},
 			}
-			token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+			token, err := encryption.SignClaims(claims, []byte(config.Current.BareRTC.JWTSecret))
-			ss, err := token.SignedString(secret)
 			if err != nil {
 				session.FlashError(w, r, "Couldn't sign you into the chat: %s", err)
 				templates.Redirect(w, r.URL.Path)
@@ -165,7 +157,7 @@ func Landing() http.HandlerFunc {
 			}()
 
 			// Redirect them to the chat room.
-			templates.Redirect(w, strings.TrimSuffix(chatURL, "/")+"/?jwt="+ss)
+			templates.Redirect(w, strings.TrimSuffix(chatURL, "/")+"/?jwt="+token)
 			return
 		}
 

pkg/encryption/jwt.go

@@ -0,0 +1,71 @@
+package encryption
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"code.nonshy.com/nonshy/website/pkg/config"
+	"github.com/golang-jwt/jwt/v4"
+)
+
+// StandardClaims returns a standard JWT claim for a username.
+//
+// It will include values for Subject (username), Issuer (site title), ExpiresAt, IssuedAt, NotBefore.
+//
+// If the userID is >0, the ID field is included.
+func StandardClaims(userID uint64, username string, expires time.Duration) jwt.RegisteredClaims {
+	claim := jwt.RegisteredClaims{
+		Subject:   username,
+		Issuer:    config.Title,
+		ExpiresAt: jwt.NewNumericDate(time.Now().Add(expires)),
+		IssuedAt:  jwt.NewNumericDate(time.Now()),
+		NotBefore: jwt.NewNumericDate(time.Now()),
+	}
+	if userID > 0 {
+		claim.ID = fmt.Sprintf("%d", userID)
+	}
+	return claim
+}
+
+// SignClaims creates and returns a signed JWT token.
+func SignClaims(claims jwt.Claims, secret []byte) (string, error) {
+	// Get our Chat JWT secret.
+	if len(secret) == 0 {
+		return "", errors.New("JWT secret key is not configured")
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	ss, err := token.SignedString(secret)
+	if err != nil {
+		return "", err
+	}
+
+	return ss, nil
+}
+
+// ValidateClaims checks a JWT token is signed by the site key and returns the claims.
+func ValidateClaims(tokenStr string, secret []byte, v jwt.Claims) (jwt.Claims, bool, error) {
+	// Handle a JWT authentication token.
+	var (
+		claims jwt.Claims
+		authOK bool
+	)
+	if tokenStr != "" {
+		token, err := jwt.ParseWithClaims(tokenStr, v, func(token *jwt.Token) (interface{}, error) {
+			return secret, nil
+		})
+		if err != nil {
+			return nil, false, err
+		}
+
+		if !token.Valid {
+			return nil, false, errors.New("token was not valid")
+		}
+
+		claims = token.Claims
+		authOK = true
+	}
+
+	return claims, authOK, nil
+}

pkg/router/router.go

@@ -112,6 +112,7 @@ func New() http.Handler {
 
 	// JSON API endpoints.
 	mux.HandleFunc("GET /v1/version", api.Version())
+	mux.HandleFunc("GET /v1/auth/static", api.StaticAuth())
 	mux.HandleFunc("GET /v1/users/me", api.LoginOK())
 	mux.HandleFunc("POST /v1/users/check-username", api.UsernameCheck())
 	mux.HandleFunc("GET /v1/web-push/vapid-public-key", webpush.VAPIDPublicKey)

pkg/templates/template_funcs.go

@@ -12,6 +12,8 @@ import (
 	"time"
 
 	"code.nonshy.com/nonshy/website/pkg/config"
+	"code.nonshy.com/nonshy/website/pkg/encryption"
+	"code.nonshy.com/nonshy/website/pkg/log"
 	"code.nonshy.com/nonshy/website/pkg/markdown"
 	"code.nonshy.com/nonshy/website/pkg/models"
 	"code.nonshy.com/nonshy/website/pkg/photo"
@@ -38,7 +40,7 @@ func TemplateFuncs(r *http.Request) template.FuncMap {
 		"ToMarkdown":         ToMarkdown,
 		"ToJSON":             ToJSON,
 		"ToHTML":             ToHTML,
-		"PhotoURL":           photo.URLPath,
+		"PhotoURL":           PhotoURL(r),
 		"Now":                time.Now,
 		"RunTime":            RunTime,
 		"PrettyTitle": func() template.HTML {
@@ -98,6 +100,28 @@ func RunTime(r *http.Request) string {
 	return "ERROR"
 }
 
+// PhotoURL returns a URL path to photos.
+func PhotoURL(r *http.Request) func(filename string) string {
+	return func(filename string) string {
+		// Get the current user to sign a JWT token.
+		var token string
+		if currentUser, err := session.CurrentUser(r); err == nil {
+			claims := encryption.StandardClaims(currentUser.ID, currentUser.Username, config.SignedPhotoJWTExpires)
+			token, err = encryption.SignClaims(claims, []byte(config.Current.SignedPhoto.JWTSecret))
+			if err != nil {
+				log.Error("PhotoURL: SignClaims: %s", err)
+			}
+		}
+
+		// JWT query string to append?
+		if token != "" {
+			token = "?jwt=" + token
+		}
+
+		return photo.URLPath(filename) + token
+	}
+}
+
 // BlurExplicit returns true if the current user has the blur_explicit setting on and the given Photo is Explicit.
 func BlurExplicit(r *http.Request) func(*models.Photo) bool {
 	return func(photo *models.Photo) bool {