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

@@ -1,8 +1,10 @@
 # Prosody Filer
 
-A simple file server for handling XMPP http_upload requests. This server is meat to be used with the Prosody [mod_http_upload_external](https://modules.prosody.im/mod_http_upload_external.html) module.
+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?
 
@@ -18,12 +20,12 @@ A simple file server for handling XMPP http_upload requests. This server is meat
     > 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 
+## Download
 
-If you are using regular x86_64 Linux, you can download a finished binary for your system on the [release page](https://github.com/ThomasLeister/prosody-filer/releases). **No need to compile this application yourself**. 
+If you are using regular x86_64 Linux, you can download a finished binary for your system on the [release page](https://github.com/ThomasLeister/prosody-filer/releases). **No need to compile this application yourself**.
 
 
 ## Build (optional)
@@ -32,21 +34,27 @@ If you're using something different than a x64 Linux, you need to compile this a
 
 To compile the server, you need a full Golang development environment. This can be set up quickly: https://golang.org/doc/install#install
 
-Then checkout this repo: 
+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: 
+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: 
+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
@@ -54,49 +62,72 @@ The application can now be build:
 
 ### Setup Prosody Filer environment
 
-Create a new user for Prosody Filer to run as: 
+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  
+Copy
 
-* the binary ```prosody-filer``` and 
-* config ```config.example.toml``` 
+* the binary ```prosody-filer``` and
+* config ```config.example.toml```
 
 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
 ```
 
-Restart Prosody when you are finished: 
+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"
 
 ### Where to store the uploaded files
-storeDir        = "./uploads/"
+storeDir        = "./upload/"
 
 ### Subdirectory for HTTP upload / download requests (usually "upload/")
 uploadSubDir    = "upload/"
@@ -105,6 +136,10 @@ uploadSubDir    = "upload/"
 Make sure ```mysecret``` matches the secret defined in your mod_http_upload_external settings!
 
 
+In addition to that, make sure that the nginx user or group can read the files uploaded
+via prosody-filer if you want to have them served by nginx directly.
+
+
 ### Systemd service file
 
 Create a new Systemd service file: ```/etc/systemd/system/prosody-filer.service```
@@ -119,11 +154,12 @@ Create a new Systemd service file: ```/etc/systemd/system/prosody-filer.service`
     WorkingDirectory=/home/prosody-filer
     User=prosody-filer
     Group=prosody-filer
+    # Group=nginx  # if the files should get served by nginx directly:
 
     [Install]
     WantedBy=multi-user.target
 
-Reload the service definitions, enable the service and start it: 
+Reload the service definitions, enable the service and start it:
 
     systemctl daemon-reload
     systemctl enable prosody-filer
@@ -137,26 +173,38 @@ 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;
         }
-    }
 
-Enable the new config:  
+        proxy_pass http://[::]:5050/upload/;
+        proxy_request_buffering off;
+    }
+}
+```
+
+Enable the new config:
 
     ln -s /etc/nginx/sites-available/uploads.myserver.tld /etc/nginx/sites-enabled/
 
@@ -169,14 +217,100 @@ Reload Nginx:
     systemctl reload nginx
 
 
+#### Alternative configuration for letting Nginx serve the uploaded files
+
+*(not officially supported - user contribution!)*
+
+```nginx
+server {
+    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://[::1]:5050;
+        proxy_buffering off;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-Proto $scheme;
+        proxy_set_header X-Forwarded-Host $host:$server_port;
+        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:
 
-    @daily    find /home/prosody-filer/uploads -maxdepth 0 -type d -mtime +28 | xargs rm -rf
+    @daily    find /home/prosody-filer/upload/* -maxdepth 0 -type d -mtime +28 | xargs rm -rf
 
-This will delete uploads older than 28 days.  
+This will delete uploads older than 28 days.
 
 
 ## Check if it works
@@ -186,5 +320,3 @@ Get the log via
     journalctl -f -u prosody-filer
 
 If your XMPP clients uploads or downloads any file, there should be some log messages on the screen.
-
-

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

@@ -37,6 +37,17 @@ type Config struct {
 
 var conf Config
 
+/*
+ * Sets CORS headers
+ */
+func addCORSheaders(w http.ResponseWriter) {
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, HEAD, GET, PUT")
+	w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
+	w.Header().Set("Access-Control-Allow-Credentials", "true")
+	w.Header().Set("Access-Control-Max-Age", "7200")
+}
+
 /*
  * Request handler
  * Is activated when a clients requests the file, file information or an upload
@@ -55,7 +66,10 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 		log.Println("Failed to parse URL query params:", err)
 	}
 
-	fileStorePath := strings.TrimLeft(u.Path, conf.UploadSubDir)
+	fileStorePath := strings.TrimPrefix(u.Path, "/"+conf.UploadSubDir)
+
+	// Add CORS headers
+	addCORSheaders(w)
 
 	if r.Method == "PUT" {
 		// Check if MAC is attached to URL
@@ -83,7 +97,7 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 			// Make sure the path exists
 			os.MkdirAll(filepath.Dir(conf.Storedir+fileStorePath), os.ModePerm)
 
-			file, err := os.Create(conf.Storedir + fileStorePath)
+			file, err := os.OpenFile(conf.Storedir+fileStorePath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0755)
 			defer file.Close()
 			if err != nil {
 				log.Println("Creating new file failed:", err)
@@ -94,7 +108,7 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 			n, err := io.Copy(file, r.Body)
 			if err != nil {
 				log.Println("Writing to new file failed:", err)
-				http.Error(w, "409 Conflict", 409)
+				http.Error(w, "500 Internal Server Error", 500)
 				return
 			}
 
@@ -122,7 +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
 		}

main_test.go

@@ -1,13 +1,55 @@
 package main
 
+/*
+ * Manual testing with CURL
+ * Send with:
+ * curl -X PUT "http://localhost:5050/upload/thomas/abc/catmetal.jpg?v=e17531b1e88bc9a5cbf816eca8a82fc09969c9245250f3e1b2e473bb564e4be0" --data-binary '@catmetal.jpg'
+ * HMAC: e17531b1e88bc9a5cbf816eca8a82fc09969c9245250f3e1b2e473bb564e4be0
+ */
+
 import (
 	"bytes"
+	"io"
 	"io/ioutil"
+	"log"
 	"net/http"
 	"net/http/httptest"
+	"os"
+	"path/filepath"
 	"testing"
 )
 
+func mockUpload() {
+	os.MkdirAll(filepath.Dir(conf.Storedir+"thomas/abc/"), os.ModePerm)
+	from, err := os.Open("./catmetal.jpg")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer from.Close()
+
+	to, err := os.OpenFile(conf.Storedir+"thomas/abc/catmetal.jpg", os.O_RDWR|os.O_CREATE, 0660)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer to.Close()
+
+	_, err = io.Copy(to, from)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func cleanup() {
+	// Clean up
+	if _, err := os.Stat(conf.Storedir); err == nil {
+		// Delete existing catmetal picture
+		err := os.RemoveAll(conf.Storedir)
+		if err != nil {
+			log.Println("Error while cleaning up:", err)
+		}
+	}
+}
+
 func TestReadConfig(t *testing.T) {
 	// Set config
 	err := readConfig("config.toml", &conf)
@@ -46,6 +88,9 @@ func TestUploadValid(t *testing.T) {
 	if status := rr.Code; status != http.StatusOK {
 		t.Errorf("handler returned wrong status code: got %v want %v. HTTP body: %s", status, http.StatusOK, rr.Body.String())
 	}
+
+	// clean up
+	cleanup()
 }
 
 func TestUploadMissingMAC(t *testing.T) {
@@ -142,6 +187,9 @@ func TestDownloadHead(t *testing.T) {
 	// Set config
 	readConfig("config.toml", &conf)
 
+	// Mock upload
+	mockUpload()
+
 	// Create request
 	req, err := http.NewRequest("HEAD", "/upload/thomas/abc/catmetal.jpg", nil)
 
@@ -159,12 +207,18 @@ func TestDownloadHead(t *testing.T) {
 	if status := rr.Code; status != http.StatusOK {
 		t.Errorf("handler returned wrong status code: got %v want %v. HTTP body: %s", status, http.StatusOK, rr.Body.String())
 	}
+
+	// cleanup
+	cleanup()
 }
 
 func TestDownloadGet(t *testing.T) {
 	// Set config
 	readConfig("config.toml", &conf)
 
+	// moch upload
+	mockUpload()
+
 	// Create request
 	req, err := http.NewRequest("GET", "/upload/thomas/abc/catmetal.jpg", nil)
 
@@ -182,6 +236,9 @@ func TestDownloadGet(t *testing.T) {
 	if status := rr.Code; status != http.StatusOK {
 		t.Errorf("handler returned wrong status code: got %v want %v. HTTP body: %s", status, http.StatusOK, rr.Body.String())
 	}
+
+	// cleanup
+	cleanup()
 }
 
 func TestEmptyGet(t *testing.T) {