Fix some bugs, add network whitelisting, start on documentation

README.md

@@ -0,0 +1,40 @@
+# Docker Socket Proxy
+
+## Description
+I wanted an easy/simple and secure way to use Traefik in my homelab without giving it free reign over my host machine and the Docker socket.  This project is a WIP where I am testing out some concepts and ideas.
+
+## Getting Started
+First build and run the proxy.
+
+```shell
+cd proxy
+go run main.go # You may need sudo to connect to /var/run/docker.sock
+```
+
+Now try it out!  Traefik uses pinned API version routes so first get the version:
+```shell
+$ export DOCKER_API_VERSION=v$(curl localhost:8000/version | jq -r '.ApiVersion')
+$ echo $DOCKER_API_VERSION
+1.49
+```
+
+Now make some requests
+```shell
+# List containers (Allowed)
+$ curl localhost:8000/v$DOCKER_API_VERSION/containers/json | jq 
+
+# Be sure to replace the below container ids with a valid one when testing.
+# Stop a running container (Allowed)
+$ curl -X POST localhost:8000/$DOCKER_API_VERSION/containers/52812bebe72b45cbe960babc2e3ff43a21bf9dd6c29ce9462ed39ec3c4e31072/stop
+
+# Start a container (Allowed)
+$ curl -X POST localhost:8000/$DOCKER_API_VERSION/containers/52812bebe72b45cbe960babc2e3ff43a21bf9dd6c29ce9462ed39ec3c4e31072/start
+```
+
+Now try something sneaky like creating a new network:
+```shell
+$ curl -X POST localhost:8000/$DOCKER_API_VERSION/networks/create -H 'content-type: application/json' -d @example-payloads/network.json
+Forbidden
+ ```
+
+See the full code for the list of routes that are allowed.  Any not in the allow list are blocked by default.

compose.yml

@@ -2,12 +2,19 @@ name: traefik_secure
 services:
   socket-proxy:
     image: dockerproxy
+    build:
+      context: ./proxy
+      dockerfile: Dockerfile
     container_name: socket-proxy
+    ports:
+      - 8000:8000
     networks:
       - traefik
     volumes:
-      - /var/run/docker.sock:/var/run/docker.sock
+      - /var/run/docker.sock:/var/run/docker.sock:ro
     restart: unless-stopped
+    environment:
+      - ALLOWED_NETWORKS=traefik_secure_traefik
   traefik:
     image: traefik:latest
     container_name: traefik
@@ -17,7 +24,7 @@ services:
       - "--entrypoints.web.address=:80"
       - "--entrypoints.websecure.address=:443"
       - "--providers.docker=true"
-      - "--providers.docker.endpoint=tcp://socket-proxy"
+      - "--providers.docker.endpoint=tcp://socket-proxy:8000"
       - "--providers.docker.exposedbydefault=false"
       - "--entrypoints.traefik.address=:8080"
       - "--api.insecure=true"
@@ -27,8 +34,6 @@ services:
       - "traefik.http.routers.api.rule=Host(`traefik.docker.localhost`)"
       - "traefik.http.routers.api.entrypoints=web"
       - "traefik.http.routers.api.service=api@internal"
-#      - "traefik.http.routers.api.middlewares=auth"
-#      - "traefik.http.middlewares.auth.basicauth.users=admin:$apr1$rANDOMhASh$eUcPa3gZzIU0TNaipFi.Q/"
     ports:
       - "80:80"
       - "8080:8080"

proxy/example-payloads/network.json

@@ -0,0 +1,43 @@
+{
+  "Name": "my_network",
+  "Driver": "bridge",
+  "Scope": "string",
+  "Internal": true,
+  "Attachable": true,
+  "Ingress": false,
+  "ConfigOnly": false,
+  "ConfigFrom": {
+    "Network": "config_only_network_01"
+  },
+  "IPAM": {
+    "Driver": "default",
+    "Config": [
+      {
+        "Subnet": "172.20.0.0/16",
+        "IPRange": "172.20.10.0/24",
+        "Gateway": "172.20.10.11",
+        "AuxiliaryAddresses": {
+          "property1": "string",
+          "property2": "string"
+        }
+      }
+    ],
+    "Options": {
+      "foo": "bar"
+    }
+  },
+  "EnableIPv4": true,
+  "EnableIPv6": true,
+  "Options": {
+    "com.docker.network.bridge.default_bridge": "true",
+    "com.docker.network.bridge.enable_icc": "true",
+    "com.docker.network.bridge.enable_ip_masquerade": "true",
+    "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
+    "com.docker.network.bridge.name": "docker0",
+    "com.docker.network.driver.mtu": "1500"
+  },
+  "Labels": {
+    "com.example.some-label": "some-value",
+    "com.example.some-other-label": "some-other-value"
+  }
+}

proxy/main.go

@@ -9,6 +9,8 @@ import (
 	"net"
 	"net/http"
 	"net/http/httputil"
+	"os"
+	"regexp"
 	"strings"
 )
 
@@ -41,11 +43,12 @@ func main() {
 		proxy.ServeHTTP(w, r)
 	})
 
-	log.Println("Unix socket proxy running on :80")
-	log.Fatal(http.ListenAndServe(":80", nil))
+	log.Println("Unix socket proxy running on :8000")
+	log.Fatal(http.ListenAndServe(":8000", nil))
 }
 
 func isAllowed(method, path string) bool {
+	// White listed endpoints that are considered relatively safe for now.
 	if method == "GET" {
 		if strings.HasSuffix(path, "/containers/json") ||
 			strings.HasSuffix(path, "/networks") ||
@@ -65,10 +68,28 @@ func isAllowed(method, path string) bool {
 			return true
 		}
 	}
+	// If it doesn't fit into any of the above, then do some more checks on it.
 	return allowPath(path)
 
 }
 
+// Only allow specific Docker API paths (e.g., container inspect, used by Traefik)
+func allowPath(path string) bool {
+	pattern := `^v\d+\.\d+$`
+	re := regexp.MustCompile(pattern)
+
+	log.Printf("Inspecting %s", path)
+	// Example: /v1.24/containers/<container-id>/json
+	parts := strings.Split(path, "/")
+	log.Printf("Parts %d parts[0] %s", len(parts), parts)
+	if len(parts) == 5 && re.MatchString(parts[1]) && parts[2] == "containers" && parts[4] == "json" {
+		log.Printf("Passes")
+		return true
+	}
+	return false
+}
+
+// Remove some sensitive data from the Docker API response.
 func redactSensitiveFields(resp *http.Response) error {
 	data, err := io.ReadAll(resp.Body)
 	if err != nil {
@@ -82,6 +103,8 @@ func redactSensitiveFields(resp *http.Response) error {
 		log.Printf("➡️ Body (object): %+v", obj)
 
 		// Redact sensitive fields from single object
+		log.Printf("🧪 Item: %+v", obj)
+
 		redactObject(obj)
 
 		redacted, _ := json.Marshal(obj)
@@ -96,10 +119,23 @@ func redactSensitiveFields(resp *http.Response) error {
 	if err := json.Unmarshal(data, &arr); err == nil {
 		log.Printf("➡️ Body (array): %d items", len(arr))
 
-		// Redact sensitive fields from each item in the array
+		// Special case: filter top-level networks (from /networks)
+		if strings.Contains(resp.Request.URL.Path, "/networks") {
+			filtered := make([]map[string]interface{}, 0)
+			for _, item := range arr {
+				if name, ok := item["Name"].(string); ok && allowedNetworks[name] {
+					filtered = append(filtered, item)
+				} else {
+					log.Printf("🗑️ Removing disallowed network: %s", name)
+				}
+			}
+			arr = filtered
+		} else {
+			// Generic redaction
 			for _, item := range arr {
 				redactObject(item)
 			}
+		}
 
 		redacted, _ := json.Marshal(arr)
 		resp.Body = io.NopCloser(strings.NewReader(string(redacted)))
@@ -116,34 +152,78 @@ func redactSensitiveFields(resp *http.Response) error {
 	return nil
 }
 
-// Only allow specific Docker API paths (e.g., container inspect, used by Traefik)
-func allowPath(path string) bool {
-	log.Printf("Inspecting %s", path)
-	// Example: /v1.24/containers/<container-id>/json
-	parts := strings.Split(path, "/")
-	log.Printf("Parts %d parts[0] %s", len(parts), parts)
-	if len(parts) == 5 && parts[1] == "v1.24" && parts[2] == "containers" && parts[4] == "json" {
-		log.Printf("Passes")
-		return true
+var allowedNetworks = getAllowedNetworks()
+
+func getAllowedNetworks() map[string]bool {
+	env := os.Getenv("ALLOWED_NETWORKS")
+	nets := strings.Split(env, ",")
+	allowed := make(map[string]bool, len(nets))
+	for _, n := range nets {
+		n = strings.TrimSpace(n)
+		if n != "" {
+			allowed[n] = true
 		}
-	return false
+	}
+	return allowed
 }
 
+// This function is responsible for removing keys/properties from the response.
 func redactObject(obj map[string]interface{}) {
 	// Top-level redactions
 	delete(obj, "HostConfig")
 	delete(obj, "GraphDriver")
 	delete(obj, "Mounts")
 
-	// Nested redactions
+	// Config redactions
 	if config, ok := obj["Config"].(map[string]interface{}); ok {
 		delete(config, "Env")
 		delete(config, "Volumes")
 		delete(config, "User")
 	}
 
-	if netSettings, ok := obj["NetworkSettings"].(map[string]interface{}); ok {
+	// NetworkSettings redactions
+	netSettings, ok := obj["NetworkSettings"].(map[string]interface{})
+	if !ok {
+		log.Println("🔍 No NetworkSettings present")
+		return
+	}
+
 	delete(netSettings, "SandboxID")
 	delete(netSettings, "SandboxKey")
+
+	networksRaw, ok := netSettings["Networks"]
+	if !ok {
+		log.Println("🔍 No Networks field present")
+		return
+	}
+
+	// Filter out any networks that traefik is not on and therefore should not care/know about.
+	switch networks := networksRaw.(type) {
+	case map[string]interface{}:
+		log.Printf("🌐 Found networks: %v", keysOf(networks))
+		for name := range networks {
+			if !allowedNetworks[name] {
+				log.Printf("🗑️ Removing disallowed network: %s", name)
+				delete(networks, name)
 			}
 		}
+	case []interface{}:
+		log.Printf("🌐 Found networks (array): %v", networks)
+		var filtered []interface{}
+		for _, v := range networks {
+			if name, ok := v.(string); ok && allowedNetworks[name] {
+				filtered = append(filtered, name)
+			}
+		}
+		netSettings["Networks"] = filtered
+	default:
+		log.Printf("⚠️ Unknown type for Networks: %T", networksRaw)
+	}
+}
+func keysOf(m map[string]interface{}) []string {
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	return keys
+}