Fixes #14: Prevents directory listing in subdirectories

This commit prevents directory listings in every directory level,
not just on root level ("upload/").

In earlier versions, an attacker could get a list of past uploads
if he ever received a valid file download path, removed the file name and
descendet in parent directories.

README.md

@@ -2,7 +2,9 @@
 
 A simple file server for handling XMPP http_upload requests. This server is meant to be used with the Prosody [mod_http_upload_external](https://modules.prosody.im/mod_http_upload_external.html) module.
 
-*(This module can also be used with future versions of Ejabberd: https://github.com/processone/ejabberd/commit/fface33d54f24c777dbec96fda6bd00e665327fe)*
+**Despite the name, this server is also compatible with Ejabberd and Ejabberd's http_upload module!**
+
+---
 
 ## Why should I use this server?
 
@@ -18,7 +20,7 @@ A simple file server for handling XMPP http_upload requests. This server is mean
     > The GC will free the memory at some point, but the OS may still report that Prosody is using that memory due to the way the libc allocator works.
     > Most long lived processes behave this way (only increasing RAM, rarely decreasing)."
 * This server works without any script interpreters or additional dependencies. It is delivered as a binary.
-* Go is very good at serving HTTP requests.
+* Go is very good at serving HTTP requests and "made for this task".
 
 
 ## Download
@@ -34,19 +36,25 @@ To compile the server, you need a full Golang development environment. This can
 
 Then checkout this repo:
 
-    go get github.com/ThomasLeister/prosody-filer
+```sh
+go get github.com/ThomasLeister/prosody-filer
+```
 
 and switch to the new directory:
 
-    cd $GOPATH/src/github.com/ThomasLeister/prosody-filer
+```sh
+cd $GOPATH/src/github.com/ThomasLeister/prosody-filer
+```
 
 The application can now be build:
 
-    ### Build static binary
-    ./build.sh
+```sh
+### Build static binary
+./build.sh
 
-    ### OR regular Go build
-    go build main.go
+### OR regular Go build
+go build main.go
+```
 
 
 ## Set up / configuration
@@ -56,11 +64,15 @@ The application can now be build:
 
 Create a new user for Prosody Filer to run as:
 
-    adduser --disabled-login --disabled-password prosody-filer
+```sh
+adduser --disabled-login --disabled-password prosody-filer
+```
 
 Switch to the new user:
 
-    su - prosody-filer
+```sh
+su - prosody-filer
+```
 
 Copy
 
@@ -69,12 +81,18 @@ Copy
 
 to ```/home/prosody-filer/```. Rename the configuration to ```config.toml```.
 
+Make sure the `prosody-filer` binary is executable: 
+
+```
+chmod u+x prosody-filer
+```
+
 
 ### Configure Prosody
 
 Back in your root shell make sure ```mod_http_upload``` is **dis**abled and ```mod_http_upload_external``` is **en**abled! Then configure the external upload module:
 
-```
+```lua
 http_upload_external_base_url = "https://uploads.myserver.tld/upload/"
 http_upload_external_secret = "mysecret"
 http_upload_external_file_size_limit = 50000000 -- 50 MB
@@ -84,13 +102,26 @@ Restart Prosody when you are finished:
 
     systemctl restart prosody
 
+
+### Alternative: Configure Ejabberd
+
+Although this tool is named after Prosody, it can be used with Ejabberd, too! Make sure you have a Ejabberd configuration similar to this:
+
+```yaml
+  mod_http_upload:
+    put_url: "https://uploads.@HOST@/upload"
+    external_secret: "mysecret"
+    max_size: 52428800
+```
+
+
 ### Configure Prosody Filer
 
 Prosody Filer configuration is done via the config.toml file in TOML syntax. There's not much to be configured:
 
-```
-### IP address and port to listen to, e.g. "127.0.0.1:5050"
-listenport      = "127.0.0.1:5050"
+```toml
+### IP address and port to listen to, e.g. "[::]:5050"
+listenport      = "[::1]:5050"
 
 ### Secret (must match the one in prosody.conf.lua!)
 secret          = "mysecret"
@@ -142,24 +173,36 @@ Done! Prosody Filer is now listening on the specified port and waiting for reque
 
 Create a new config file ```/etc/nginx/sites-available/uploads.myserver.tld```:
 
-    server {
-        listen 80;
-        listen [::]:80;
-        listen 443 ssl;
-        listen [::]:443 ssl;
+```nginx
+server {
+    listen 80;
+    listen [::]:80;
+    listen 443 ssl;
+    listen [::]:443 ssl;
 
-        server_name uploads.myserver.tld;
+    server_name uploads.myserver.tld;
 
-        ssl_certificate /etc/letsencrypt/live/uploads.myserver.tld/fullchain.pem;
-        ssl_certificate_key /etc/letsencrypt/live/uploads.myserver.tld/privkey.pem;
+    ssl_certificate /etc/letsencrypt/live/uploads.myserver.tld/fullchain.pem;
+    ssl_certificate_key /etc/letsencrypt/live/uploads.myserver.tld/privkey.pem;
 
-        client_max_body_size 50m;
+    client_max_body_size 50m;
 
-        location /upload/ {
-                proxy_pass http://127.0.0.1:5050/upload/;
-                proxy_request_buffering off;
+    location /upload/ {
+        if ( $request_method = OPTIONS ) {
+                add_header Access-Control-Allow-Origin '*';
+                add_header Access-Control-Allow-Methods 'PUT, GET, OPTIONS, HEAD';
+                add_header Access-Control-Allow-Headers 'Authorization, Content-Type';
+                add_header Access-Control-Allow-Credentials 'true';
+                add_header Content-Length 0;
+                add_header Content-Type text/plain;
+                return 200;
         }
+
+        proxy_pass http://[::]:5050/upload/;
+        proxy_request_buffering off;
     }
+}
+```
 
 Enable the new config:
 
@@ -173,24 +216,41 @@ Reload Nginx:
 
     systemctl reload nginx
 
-#### Configuration for letting nginx serve the uploaded files
+
+#### Alternative configuration for letting Nginx serve the uploaded files
+
+*(not officially supported - user contribution!)*
 
 ```nginx
 server {
-    listen 443 ssl http2;
-    listen [::]:443 ssl http2;
-    server_name xmppserver.tld;
+    listen 80;
+    listen [::]:80;
+    listen 443 ssl;
+    listen [::]:443 ssl;
 
-    # ...
+    server_name uploads.myserver.tld;
+
+    ssl_certificate /etc/letsencrypt/live/uploads.myserver.tld/fullchain.pem;
+    ssl_certificate_key /etc/letsencrypt/live/uploads.myserver.tld/privkey.pem;
 
     location /upload/ {
+        if ( $request_method = OPTIONS ) {
+                add_header Access-Control-Allow-Origin '*';
+                add_header Access-Control-Allow-Methods 'PUT, GET, OPTIONS, HEAD';
+                add_header Access-Control-Allow-Headers 'Authorization, Content-Type';
+                add_header Access-Control-Allow-Credentials 'true';
+                add_header Content-Length 0;
+                add_header Content-Type text/plain;
+                return 200;
+        }
+
         root /home/prosody-filer;
         client_max_body_size 51m;
         client_body_buffer_size 51m;
         try_files $uri $uri/ @prosodyfiler;
     }
     location @prosodyfiler {
-        proxy_pass http://127.0.0.1:5050;
+        proxy_pass http://[::1]:5050;
         proxy_buffering off;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
@@ -199,11 +259,51 @@ server {
         proxy_set_header X-Forwarded-Server $host;
         proxy_set_header X-Forwarded-For $remote_addr;
     }
-
-    # ...
 }
 ```
 
+## apache2 configuration (alternative to Nginx)
+
+*(This configuration was provided by a user and has never been tested by the author of Prosody Filer. It might be outdated and might not work anymore)*
+
+```
+<VirtualHost *:80>
+    ServerName upload.example.eu
+    RedirectPermanent / https://upload.example.eu/
+</VirtualHost>
+
+<VirtualHost *:443>
+    ServerName upload.example.eu
+    SSLEngine on
+
+    SSLCertificateFile "Path to the ca file"
+    SSLCertificateKeyFile "Path to the key file"
+
+    Header always set Public-Key-Pins: ''
+    Header always set Strict-Transport-Security "max-age=63072000; includeSubdomains; preload"
+    H2Direct on
+
+    <Location /upload>
+        Header always set Access-Control-Allow-Origin "*"
+        Header always set Access-Control-Allow-Headers "Content-Type"
+        Header always set Access-Control-Allow-Methods "OPTIONS, PUT, GET"
+
+        RewriteEngine On
+
+        RewriteCond %{REQUEST_METHOD} OPTIONS
+        RewriteRule ^(.*)$ $1 [R=200,L]
+    </Location>
+
+    SSLProxyEngine on
+
+    ProxyPreserveHost On
+    ProxyRequests Off
+    ProxyPass / http://localhost:5050/
+    ProxyPassReverse / http://localhost:5050/
+</VirtualHost>
+```
+
+
 ## Automatic purge
 
 Prosody Filer has no immediate knowlegde over all the stored files and the time they were uploaded, since no database exists for that. Also Prosody is not capable to do auto deletion if *mod_http_upload_external* is used. Therefore the suggested way of purging the uploads directory is to execute a purge command via a cron job:

config.example.toml

@@ -2,8 +2,8 @@
 ### Server configuration
 ### (rename this file to "config.toml"!)
 
-### IP address and port to listen to, e.g. "127.0.0.1:5050"
-listenport      = "127.0.0.1:5050"
+### IP address and port to listen to, e.g. "[::]:5050" to listen to ipv6 and ipv4 addresses
+listenport      = "[::]:5050"
 
 ### Secret (must match the one in prosody.conf.lua!)
 secret          = "mysecret"

main.go

@@ -48,7 +48,6 @@ func addCORSheaders(w http.ResponseWriter) {
 	w.Header().Set("Access-Control-Max-Age", "7200")
 }
 
-
 /*
  * Request handler
  * Is activated when a clients requests the file, file information or an upload
@@ -67,7 +66,7 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 		log.Println("Failed to parse URL query params:", err)
 	}
 
-	fileStorePath := strings.TrimPrefix(u.Path, "/" + conf.UploadSubDir)
+	fileStorePath := strings.TrimPrefix(u.Path, "/"+conf.UploadSubDir)
 
 	// Add CORS headers
 	addCORSheaders(w)
@@ -137,7 +136,8 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", contentType)
 	} else if r.Method == "GET" {
 		contentType := mime.TypeByExtension(filepath.Ext(fileStorePath))
-		if fileStorePath == "" {
+		if f, err := os.Stat(conf.Storedir + fileStorePath); err != nil || f.IsDir() {
+			log.Println("Directory listing forbidden!")
 			http.Error(w, "403 Forbidden", 403)
 			return
 		}