Improve security of docker registry install

Docker_Registry_Install_Guide.md

@@ -1,6 +1,6 @@
 # Docker Registry Install Guide
 
-This guide covers setting up a rootless Docker Registry v2 with host TLS reverse proxy for secure image storage. The registry runs rootless via Podman with loopback-only access, while a host nginx reverse proxy provides TLS termination and authentication.
+This guide covers setting up a rootless Docker Registry v2 with host TLS reverse proxy for secure image storage. The registry runs rootless via Podman with loopback-only access, while a host nginx reverse proxy provides TLS termination and mTLS authentication.
 
 ## Architecture Overview
 
@@ -14,7 +14,7 @@ This guide covers setting up a rootless Docker Registry v2 with host TLS reverse
          │                       │                       │
          │                       │                       │
          └─── HTTPS :443 ────────┼───────────────────────┘
-                                 │
+         (Unauthenticated pulls) │
                                  └─── HTTPS :4443 ───────┘
                                  (mTLS Authentication)
 ```
@@ -26,6 +26,8 @@ This guide covers setting up a rootless Docker Registry v2 with host TLS reverse
 - **Loopback Isolation**: Registry only accessible via `127.0.0.1:5000`
 - **mTLS Authentication**: Client certificates required for push operations
 - **No $HOME I/O**: All Podman state outside user home directory
+- **Port 443**: Unauthenticated pulls only (GET requests)
+- **Port 4443**: Authenticated pushes only (mTLS required)
 
 ## Prerequisites
 
@@ -36,7 +38,7 @@ This guide covers setting up a rootless Docker Registry v2 with host TLS reverse
 
 ## Step 1: Install Podman (if not already installed)
 
-### 1.5 Install Podman
+### 1.1 Install Podman
 
 ```bash
 # Install Podman and related tools
@@ -54,7 +56,7 @@ sudo usermod --add-subuids 100000-165535 CI_SERVICE_USER
 sudo usermod --add-subgids 100000-165535 CI_SERVICE_USER
 ```
 
-## Step 2: Set Up Rootless Docker Registry v2 with Host TLS Reverse Proxy
+## Step 2: Set Up Rootless Docker Registry v2
 
 ### 2.1 Create System-wide Podman Configuration
 
@@ -102,6 +104,11 @@ sudo mkdir -p /etc/registry/certs/private /etc/registry/certs/clients
 sudo chown root:root /etc/registry/certs/private /etc/registry/certs/clients
 sudo chmod 750 /etc/registry/certs/private
 sudo chmod 755 /etc/registry/certs/clients
+
+# Create registry data directory
+sudo mkdir -p /var/lib/registry/data
+sudo chown CI_SERVICE_USER:CI_SERVICE_USER /var/lib/registry/data
+sudo chmod 755 /var/lib/registry/data
 ```
 
 ### 2.4 Install Systemd Services
@@ -112,27 +119,26 @@ sudo chmod 755 /etc/registry/certs/clients
 # Install systemd user service for rootless registry
 sudo tee /etc/systemd/user/registry.service > /dev/null << 'EOF'
 [Unit]
-Description=Rootless Docker Registry v2
-After=network.target
+Description=Rootless Docker Registry v2 (loopback only)
+After=network-online.target
+Wants=network-online.target
 
 [Service]
-Type=simple
 Environment=PODMAN_ROOT=/var/tmp/podman-%U/root
 Environment=PODMAN_RUNROOT=/run/user/%U/podman-run
 Environment=PODMAN_TMPDIR=/var/tmp/podman-%U/tmp
 Environment=XDG_DATA_HOME=/var/tmp/podman-%U/xdg-data
 Environment=XDG_CONFIG_HOME=/var/tmp/podman-%U/xdg-config
-Environment=REGISTRY_HTTP_ADDR=0.0.0.0:5000
-Environment=REGISTRY_STORAGE_DELETE_ENABLED=false
-ExecStart=/usr/bin/podman run --rm --name registry \
-  --root=${PODMAN_ROOT} --runroot=${PODMAN_RUNROOT} --tmpdir=${PODMAN_TMPDIR} --events-backend=file \
+ExecStart=/usr/bin/podman --root=${PODMAN_ROOT} --runroot=${PODMAN_RUNROOT} --tmpdir=${PODMAN_TMPDIR} --events-backend=file \
+  run --rm --name registry \
   -p 127.0.0.1:5000:5000 \
-  --cap-drop=ALL --read-only --tmpfs /tmp:size=64m --security-opt=no-new-privileges \
-  -v /var/lib/registry:/var/lib/registry:Z \
+  --read-only --tmpfs /tmp:size=64m --cap-drop=ALL --security-opt=no-new-privileges \
+  -e REGISTRY_HTTP_ADDR=0.0.0.0:5000 \
+  -e REGISTRY_STORAGE_DELETE_ENABLED=false \
+  -v /var/lib/registry/data:/var/lib/registry:z \
   registry:2
-ExecStop=/usr/bin/podman stop --root=${PODMAN_ROOT} --runroot=${PODMAN_RUNROOT} --tmpdir=${PODMAN_TMPDIR} --events-backend=file registry
-Restart=always
-RestartSec=10
+ExecStop=/usr/bin/podman --root=${PODMAN_ROOT} --runroot=${PODMAN_RUNROOT} --tmpdir=${PODMAN_TMPDIR} stop -t 10 registry
+Restart=on-failure
 
 [Install]
 WantedBy=default.target
@@ -145,12 +151,11 @@ EOF
 # Install systemd system service for TLS reverse proxy
 sudo tee /etc/systemd/system/registry-proxy.service > /dev/null << 'EOF'
 [Unit]
-Description=Docker Registry TLS Reverse Proxy
-After=network.target registry.service
-Requires=registry.service
+Description=TLS proxy for Docker Registry (443 pulls / 4443 pushes)
+After=network-online.target
+Wants=network-online.target
 
 [Service]
-Type=simple
 User=registry-proxy
 Group=registry-proxy
 AmbientCapabilities=CAP_NET_BIND_SERVICE
@@ -159,13 +164,16 @@ NoNewPrivileges=yes
 PrivateTmp=yes
 ProtectSystem=strict
 ProtectHome=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
 RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
 IPAddressDeny=any
 IPAddressAllow=127.0.0.1/8 ::1
-ExecStart=/usr/sbin/nginx -c /etc/registry/nginx.conf
-ExecReload=/usr/sbin/nginx -c /etc/registry/nginx.conf -s reload
-Restart=always
-RestartSec=10
+ExecStart=/usr/sbin/nginx -g 'daemon off;' -c /etc/registry/nginx.conf
+Restart=on-failure
 
 [Install]
 WantedBy=multi-user.target
@@ -177,99 +185,50 @@ EOF
 ```bash
 # Create nginx configuration for TLS reverse proxy
 sudo tee /etc/registry/nginx.conf > /dev/null << 'EOF'
-events {
-    worker_connections 1024;
-}
-
+worker_processes auto;
+events { worker_connections 1024; }
 http {
-    include /etc/nginx/mime.types;
-    default_type application/octet-stream;
+  limit_req_zone $binary_remote_addr zone=reg_read:10m rate=10r/s;
+  limit_req_zone $binary_remote_addr zone=reg_write:10m rate=5r/s;
+  client_max_body_size 2g;
+  proxy_http_version 1.1;
+  proxy_set_header Connection "";
+  upstream reg { server 127.0.0.1:5000; }
 
-    # Rate limiting
-    limit_req_zone $binary_remote_addr zone=read_limit:10m rate=10r/s;
-    limit_req_zone $binary_remote_addr zone=write_limit:10m rate=5r/s;
-    
-    # Upstream registry
-    upstream registry {
-        server 127.0.0.1:5000;
+  # 443: unauthenticated pulls only
+  server {
+    listen 443 ssl http2;
+    ssl_certificate     /etc/registry/certs/registry.crt;
+    ssl_certificate_key /etc/registry/certs/private/registry.key;
+    ssl_protocols TLSv1.2 TLSv1.3;
+    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+    if ($request_method ~* ^(PUT|PATCH|POST|DELETE)$) { return 403; }
+    location /v2/ {
+      limit_req zone=reg_read burst=20 nodelay;
+      proxy_pass http://reg;
+      proxy_set_header Host $host;
+      proxy_set_header X-Forwarded-Proto https;
+      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
     }
+  }
 
-    # Port 443: Unauthenticated pulls only
-    server {
-        listen 443 ssl http2;
-        server_name _;
-        
-        # TLS configuration
-        ssl_protocols TLSv1.2 TLSv1.3;
-        ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384;
-        ssl_prefer_server_ciphers off;
-        ssl_session_cache shared:SSL:10m;
-        ssl_session_timeout 10m;
-        
-        # Security headers
-        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
-        add_header X-Frame-Options DENY always;
-        add_header X-Content-Type-Options nosniff always;
-        
-        # Certificate files
-        ssl_certificate /etc/registry/certs/registry.crt;
-        ssl_certificate_key /etc/registry/certs/private/registry.key;
-        
-        # Block write methods (PUT, PATCH, POST, DELETE)
-        if ($request_method ~ ^(PUT|PATCH|POST|DELETE)$) {
-            return 403;
-        }
-        
-        # Rate limiting for reads
-        limit_req zone=read_limit burst=20 nodelay;
-        
-        # Proxy to registry
-        location / {
-            proxy_pass http://registry;
-            proxy_set_header Host $http_host;
-            proxy_set_header X-Real-IP $remote_addr;
-            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-            proxy_set_header X-Forwarded-Proto $scheme;
-        }
-    }
-    
-    # Port 4443: Authenticated pushes only (mTLS)
-    server {
-        listen 4443 ssl http2;
-        server_name _;
-        
-        # TLS configuration
-        ssl_protocols TLSv1.2 TLSv1.3;
-        ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384;
-        ssl_prefer_server_ciphers off;
-        ssl_session_cache shared:SSL:10m;
-        ssl_session_timeout 10m;
-        
-        # mTLS configuration
-        ssl_client_certificate /etc/registry/certs/clients/ca.crt;
-        ssl_verify_client on;
-        
-        # Security headers
-        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
-        add_header X-Frame-Options DENY always;
-        add_header X-Content-Type-Options nosniff always;
-        
-        # Certificate files
-        ssl_certificate /etc/registry/certs/registry.crt;
-        ssl_certificate_key /etc/registry/certs/private/registry.key;
-        
-        # Rate limiting for writes
-        limit_req zone=write_limit burst=10 nodelay;
-        
-        # Proxy to registry (full API access)
-        location / {
-            proxy_pass http://registry;
-            proxy_set_header Host $http_host;
-            proxy_set_header X-Real-IP $remote_addr;
-            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-            proxy_set_header X-Forwarded-Proto $scheme;
-        }
+  # 4443: authenticated pushes only (mTLS)
+  server {
+    listen 4443 ssl http2;
+    ssl_certificate     /etc/registry/certs/registry.crt;
+    ssl_certificate_key /etc/registry/certs/private/registry.key;
+    ssl_protocols TLSv1.2 TLSv1.3;
+    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+    ssl_client_certificate /etc/registry/certs/clients/ca.crt;
+    ssl_verify_client on;
+    location /v2/ {
+      limit_req zone=reg_write burst=10;
+      proxy_pass http://reg;
+      proxy_set_header Host $host:4443;
+      proxy_set_header X-Forwarded-Proto https;
+      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
     }
+  }
 }
 EOF
 
@@ -390,7 +349,9 @@ sudo ufw allow 4443/tcp # Docker Registry via nginx (authenticated pushes with m
 # Enable and start services
 sudo systemctl --global enable registry.service
 sudo systemctl enable registry-proxy.service
-sudo -u CI_SERVICE_USER -H sh -lc 'systemctl --user daemon-reload; systemctl --user enable --now registry.service'
+
+# Start as the service user
+sudo -u CI_SERVICE_USER sh -lc 'systemctl --user daemon-reload && systemctl --user enable --now registry.service'
 sudo systemctl start registry-proxy.service
 ```
 
@@ -537,6 +498,7 @@ The project uses a two-port configuration:
 5. **🔧 Robust Boot**: User manager guaranteed to exist at boot time
 6. **🎯 Clear Separation**: Unauthenticated pulls vs authenticated pushes
 7. **⚡ Low-Port Binding**: Via minimal capability (`CAP_NET_BIND_SERVICE`)
+8. **🛡️ Comprehensive Hardening**: Multiple security layers and restrictions
 
 ## 🎉 Congratulations!
 
@@ -549,5 +511,6 @@ You have successfully set up a rootless Docker Registry v2 with host TLS reverse
 - ✅ **FHS-compliant directory structure** for better organization and security
 - ✅ **No $HOME I/O** policy with all state outside user home directory
 - ✅ **Port 443 allows unauthenticated Docker Registry v2 pulls; Port 4443 is for authenticated pushes (mTLS)**
+- ✅ **Comprehensive security hardening** with multiple protection layers
 
 Your Docker Registry is now ready for secure image storage with proper authentication and isolation!