feat: Add configurable proxy for outgoing traffic to prevent SSRF

Dockerfile

@@ -28,7 +28,7 @@ RUN npm install npm --global \
 FROM node:22-alpine
 
 RUN apk -U upgrade \
-  && apk add bash python3 --no-cache \
+  && apk add bash python3 squid --no-cache \
   && npm install npm --global
 
 USER node

docker-compose-dev.yml

@@ -50,6 +50,10 @@ services:
       # It should not be enabled without a rate limiter for security reasons.
       # - SHOW_DETAILED_AUTH_ERRORS=false
 
+      # All outgoing HTTP requests (SMTP, webhooks, Apprise notifications, favicon fetching, etc.)
+      # will be sent through this proxy if set.
+      # - OUTGOING_PROXY=http://proxy:3128
+
       # - S3_ENDPOINT=
       # - S3_REGION=
       # - S3_ACCESS_KEY_ID=

docker-compose.yml

@@ -61,6 +61,12 @@ services:
       # It should not be enabled without a rate limiter for security reasons.
       # - SHOW_DETAILED_AUTH_ERRORS=false
 
+      # All outgoing HTTP requests (SMTP, webhooks, Apprise notifications, favicon fetching, etc.)
+      # will be sent through this proxy if set.
+      # If commented out, an internal Squid proxy will be started inside the container,
+      # which you can control via OUTGOING_BLOCKED_* and OUTGOING_ALLOWED_* below.
+      # - OUTGOING_PROXY=http://proxy:3128
+
       # - S3_ENDPOINT=
       # - S3_REGION=
       # - S3_ACCESS_KEY_ID=
@@ -110,6 +116,18 @@ services:
       # Using Gravatar directly exposes user IPs and hashed emails to a third party (GDPR risk).
       # Use a proxy you control for privacy, or leave commented out or empty to disable.
       # - GRAVATAR_BASE_URL=https://www.gravatar.com/avatar/
+
+      # --------------------------------------------------------------------
+      # Outgoing traffic control (internal Squid proxy)
+      # --------------------------------------------------------------------
+
+      # These IPs/hostnames will always be blocked (highest priority)
+      # - OUTGOING_BLOCKED_IPS=
+      # - OUTGOING_BLOCKED_HOSTS=localhost,postgres,valkey
+
+      # Only these IPs/hostnames will be reachable
+      # - OUTGOING_ALLOWED_IPS=
+      # - OUTGOING_ALLOWED_HOSTS=
     depends_on:
       postgres:
         condition: service_healthy

server/.env.sample

@@ -41,6 +41,10 @@ SECRET_KEY=notsecretkey
 # It should not be enabled without a rate limiter for security reasons.
 # SHOW_DETAILED_AUTH_ERRORS=false
 
+# All outgoing HTTP requests (SMTP, webhooks, Apprise notifications, favicon fetching, etc.)
+# will be sent through this proxy if set.
+# OUTGOING_PROXY=http://proxy:3128
+
 # S3_ENDPOINT=
 # S3_REGION=
 # S3_ACCESS_KEY_ID=

server/api/helpers/utils/download-favicon.js

@@ -4,6 +4,7 @@
  */
 
 const { URL } = require('url');
+const { ProxyAgent } = require('undici');
 const icoToPng = require('ico-to-png');
 const sharp = require('sharp');
 
@@ -20,6 +21,9 @@ const fetchWithTimeout = (url) => {
 
   return fetch(url, {
     signal: abortController.signal,
+    dispatcher: sails.config.custom.outgoingProxy
+      ? new ProxyAgent(sails.config.custom.outgoingProxy)
+      : undefined,
   });
 };
 

server/api/helpers/utils/make-smtp-transporter.js

@@ -23,6 +23,11 @@ module.exports = {
 
       if (config.smtpHost) {
         sourceConfig = config;
+
+        // TODO: hack to make it work with proxy
+        if (sourceConfig.smtpPort === null) {
+          sourceConfig.smtpPort = sourceConfig.smtpSecure ? 465 : 587;
+        }
       }
     }
 
@@ -47,6 +52,10 @@ module.exports = {
         tls: {
           rejectUnauthorized: sourceConfig.smtpTlsRejectUnauthorized,
         },
+        proxy:
+          sails.config.custom.outgoingProxy && !sails.config.custom.smtpHost
+            ? sails.config.custom.outgoingProxy
+            : undefined,
       },
       {
         from: sourceConfig.smtpFrom,

server/api/helpers/utils/send-notifications.js

@@ -26,12 +26,21 @@ module.exports = {
 
   async fn(inputs) {
     try {
-      await promisifyExecFile(`${sails.config.appPath}/.venv/bin/python3`, [
+      await promisifyExecFile(
-        `${sails.config.appPath}/utils/send_notifications.py`,
+        `${sails.config.appPath}/.venv/bin/python3`,
-        JSON.stringify(inputs.services),
+        [
-        inputs.title,
+          `${sails.config.appPath}/utils/send_notifications.py`,
-        JSON.stringify(inputs.bodyByFormat),
+          JSON.stringify(inputs.services),
-      ]);
+          inputs.title,
+          JSON.stringify(inputs.bodyByFormat),
+        ],
+        {
+          env: {
+            HTTP_PROXY: sails.config.custom.outgoingProxy,
+            HTTPS_PROXY: sails.config.custom.outgoingProxy,
+          },
+        },
+      );
     } catch (error) {
       sails.log.error(`Error sending notifications: ${error.stderr || error.message}`);
     }

server/api/helpers/utils/send-webhooks.js

@@ -3,6 +3,8 @@
  * Licensed under the Fair Use License: https://github.com/plankanban/planka/blob/master/LICENSE.md
  */
 
+const { ProxyAgent } = require('undici');
+
 const Webhook = require('../../models/Webhook');
 
 /**
@@ -61,6 +63,9 @@ async function sendWebhook(webhook, event, data, prevData, user) {
       headers,
       body,
       method: 'POST',
+      dispatcher: sails.config.custom.outgoingProxy
+        ? new ProxyAgent(sails.config.custom.outgoingProxy)
+        : undefined,
     });
 
     if (!response.ok) {

server/config/custom.js

@@ -66,6 +66,7 @@ module.exports.custom = {
   demoMode: process.env.DEMO_MODE === 'true',
 
   showDetailedAuthErrors: process.env.SHOW_DETAILED_AUTH_ERRORS === 'true',
+  outgoingProxy: process.env.OUTGOING_PROXY,
 
   s3Endpoint: process.env.S3_ENDPOINT,
   s3Region: process.env.S3_REGION,

server/package-lock.json

@@ -38,6 +38,7 @@
         "sails-postgresql": "^5.0.1",
         "serve-static": "^2.2.1",
         "sharp": "^0.34.5",
+        "undici": "^7.21.0",
         "uuid": "^11.1.0",
         "validator": "^13.15.26",
         "winston": "^3.19.0",
@@ -11381,6 +11382,15 @@
       "integrity": "sha512-hzSoAVtJF+3ZtiFX0VgfFPHEDRm7Y/QPjGyNo4TVdnDTdft3tr8hEkD25a1jC+TjTuE7tkHGKkhwCgs9dgBB2g==",
       "license": "MIT"
     },
+    "node_modules/undici": {
+      "version": "7.21.0",
+      "resolved": "https://registry.npmjs.org/undici/-/undici-7.21.0.tgz",
+      "integrity": "sha512-Hn2tCQpoDt1wv23a68Ctc8Cr/BHpUSfaPYrkajTXOS9IKpxVRx/X5m1K2YkbK2ipgZgxXSgsUinl3x+2YdSSfg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=20.18.1"
+      }
+    },
     "node_modules/undici-types": {
       "version": "7.16.0",
       "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",

server/package.json

@@ -83,6 +83,7 @@
     "sails-postgresql": "^5.0.1",
     "serve-static": "^2.2.1",
     "sharp": "^0.34.5",
+    "undici": "^7.21.0",
     "uuid": "^11.1.0",
     "validator": "^13.15.26",
     "winston": "^3.19.0",

server/start.sh

@@ -18,7 +18,106 @@ load_secret() {
   fi
 }
 
-if [[ -n "${DATABASE_URL}" ]]; then
+start_outgoing_proxy_if_needed() {
+  # If a custom outgoing proxy is set, do not start internal proxy
+  if [[ -n "${OUTGOING_PROXY:-}" ]]; then
+    return
+  fi
+
+  # Minimum safe defaults
+  if [[ -z "${OUTGOING_BLOCKED_HOSTS+x}" ]]; then
+    OUTGOING_BLOCKED_HOSTS="localhost,postgres"
+  fi
+
+  # If no blocked/allowed rules exist, do not start internal proxy
+  if [[ -z "${OUTGOING_BLOCKED_IPS:-}" && -z "${OUTGOING_BLOCKED_HOSTS:-}" && -z "${OUTGOING_ALLOWED_IPS:-}" && -z "${OUTGOING_ALLOWED_HOSTS:-}" ]]; then
+    return
+  fi
+
+  SQUID_CONF="/tmp/squid.conf"
+  SQUID_PID="/tmp/squid.pid"
+
+  : > "$SQUID_CONF"
+
+  # Basic settings
+  echo "pid_filename $SQUID_PID" >> "$SQUID_CONF"
+  echo "http_port 3128" >> "$SQUID_CONF"
+  echo "acl all src all" >> "$SQUID_CONF"
+
+  # Disable caching
+  echo "cache deny all" >> "$SQUID_CONF"
+  echo "cache_mem 0" >> "$SQUID_CONF"
+  echo "memory_pools off" >> "$SQUID_CONF"
+  echo "cache_swap_low 0" >> "$SQUID_CONF"
+  echo "cache_swap_high 0" >> "$SQUID_CONF"
+
+  # Disable logs
+  echo "access_log /tmp/test.log" >> "$SQUID_CONF"
+  echo "cache_store_log none" >> "$SQUID_CONF"
+  echo "cache_log /dev/null" >> "$SQUID_CONF"
+  echo "logfile_rotate 0" >> "$SQUID_CONF"
+  echo "debug_options ALL,1" >> "$SQUID_CONF"
+
+  # Make it pass-through like
+  echo "forwarded_for delete" >> "$SQUID_CONF"
+  echo "via off" >> "$SQUID_CONF"
+  echo "request_header_access X-Forwarded-For deny all" >> "$SQUID_CONF"
+  echo "request_header_access Via deny all" >> "$SQUID_CONF"
+  echo "request_header_access Cache-Control deny all" >> "$SQUID_CONF"
+
+  # Blocked IPs
+  if [[ -n "${OUTGOING_BLOCKED_IPS:-}" ]]; then
+    IFS=',' read -ra BLOCKED_IPS <<< "$OUTGOING_BLOCKED_IPS"
+    for ip in "${BLOCKED_IPS[@]}"; do
+      echo "acl blocked_ip dst $ip" >> "$SQUID_CONF"
+    done
+    echo "http_access deny blocked_ip" >> "$SQUID_CONF"
+  fi
+
+  # Blocked hostnames
+  if [[ -n "${OUTGOING_BLOCKED_HOSTS:-}" ]]; then
+    IFS=',' read -ra BLOCKED_HOSTS <<< "$OUTGOING_BLOCKED_HOSTS"
+    for host in "${BLOCKED_HOSTS[@]}"; do
+      echo "acl blocked_host dstdomain $host" >> "$SQUID_CONF"
+    done
+    echo "http_access deny blocked_host" >> "$SQUID_CONF"
+  fi
+
+  # Allowed IPs
+  if [[ -n "${OUTGOING_ALLOWED_IPS:-}" ]]; then
+    IFS=',' read -ra ALLOWED_IPS <<< "$OUTGOING_ALLOWED_IPS"
+    for ip in "${ALLOWED_IPS[@]}"; do
+      echo "acl allowed_ip dst $ip" >> "$SQUID_CONF"
+    done
+    echo "http_access allow allowed_ip" >> "$SQUID_CONF"
+  fi
+
+  # Allowed hostnames
+  if [[ -n "${OUTGOING_ALLOWED_HOSTS:-}" ]]; then
+    IFS=',' read -ra ALLOWED_HOSTS <<< "$OUTGOING_ALLOWED_HOSTS"
+    for host in "${ALLOWED_HOSTS[@]}"; do
+      echo "acl allowed_host dstdomain $host" >> "$SQUID_CONF"
+    done
+    echo "http_access allow allowed_host" >> "$SQUID_CONF"
+  fi
+
+  # If any allowed rules exist, everything else is denied
+  if [[ -n "${OUTGOING_ALLOWED_IPS+x}${OUTGOING_ALLOWED_HOSTS+x}" ]]; then
+    echo "http_access deny all" >> "$SQUID_CONF"
+  else
+    # If no allowed rules exist, everything else is allowed
+    echo "http_access allow all" >> "$SQUID_CONF"
+  fi
+
+  # Start Squid
+  rm -f "$SQUID_PID"
+  squid -N -f "$SQUID_CONF" &
+
+  # Set environment variable
+  export OUTGOING_PROXY="http://127.0.0.1:3128"
+}
+
+if [[ -n "${DATABASE_URL:-}" ]]; then
   if [[ -z "${DATABASE_PASSWORD:-}" && -e "${DATABASE_PASSWORD__FILE:-}" ]]; then
     DATABASE_PASSWORD="$(read_secret "${DATABASE_PASSWORD__FILE}")"
     export DATABASE_URL="${DATABASE_URL/\$\{DATABASE_PASSWORD\}/${DATABASE_PASSWORD}}"
@@ -31,6 +130,8 @@ load_secret S3_SECRET_ACCESS_KEY
 load_secret OIDC_CLIENT_SECRET
 load_secret SMTP_PASSWORD
 
+start_outgoing_proxy_if_needed
+
 export NODE_ENV=production
 
 node db/init.js