[Nginx] Limit request body size, configurable via NGINX_MAX_BODY_SIZE

data/Dockerfiles/nginx/bootstrap.py

@@ -1,4 +1,5 @@
 import os
+import re
 import subprocess
 from jinja2 import Environment, FileSystemLoader
 
@@ -44,6 +45,11 @@ def prepare_template_vars():
   ipv4_network = os.getenv("IPV4_NETWORK", "172.22.1")
   additional_server_names = os.getenv("ADDITIONAL_SERVER_NAMES", "")
   trusted_proxies = os.getenv("TRUSTED_PROXIES", "")
+  # nginx size syntax, invalid values fall back to the default
+  max_body_size = os.getenv("NGINX_MAX_BODY_SIZE", "128m").strip()
+  if not re.fullmatch(r'[0-9]+[kKmMgG]?', max_body_size):
+    print(f"Invalid NGINX_MAX_BODY_SIZE '{max_body_size}', using 128m")
+    max_body_size = "128m"
 
   template_vars = {
     'IPV4_NETWORK': ipv4_network,
@@ -60,6 +66,7 @@ def prepare_template_vars():
     'PHPFPMHOST': os.getenv("PHPFPMHOST", "php-fpm-mailcow"),
     'ENABLE_IPV6': os.getenv("ENABLE_IPV6", "true").lower() != "false",
     'HTTP_REDIRECT': os.getenv("HTTP_REDIRECT", "n").lower() in ("y", "yes"),
+    'NGINX_MAX_BODY_SIZE': max_body_size,
   }
 
   ssl_dir = '/etc/ssl/mail/'

data/conf/nginx/templates/sites-default.conf.j2

@@ -22,7 +22,8 @@ add_header Referrer-Policy strict-origin;
 
 index index.php index.html;
 
-client_max_body_size 0;
+# PHP accepts no larger requests (post_max_size), SOGo webmail, CalDAV/CardDAV and ActiveSync use NGINX_MAX_BODY_SIZE
+client_max_body_size 64m;
 
 gzip on;
 gzip_disable "msie6";
@@ -182,6 +183,8 @@ location /sogo-auth-verify {
     proxy_set_header  Content-Length "";
     proxy_pass        http://127.0.0.1:65510/sogo-auth;
     proxy_pass_request_body off;
+    # The subrequest checks the size of the original request against this limit, the body is never read here
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
 }
 
 location ^~ /Microsoft-Server-ActiveSync {
@@ -205,7 +208,7 @@ location ^~ /Microsoft-Server-ActiveSync {
     proxy_busy_buffers_size 512k;
     proxy_set_header Host $http_host;
     client_body_buffer_size 512k;
-    client_max_body_size 0;
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
 }
 
 location ^~ /SOGo {
@@ -256,7 +259,7 @@ location ^~ /SOGo {
     proxy_send_timeout 3600;
     proxy_read_timeout 3600;
     client_body_buffer_size 128k;
-    client_max_body_size 0;
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
     break;
 }