From 59abc641d6f5c2af46515bc917fe0474b7b3727f Mon Sep 17 00:00:00 2001
From: Christian Zeitnitz <christian@zeitnitz.eu>
Date: Fri, 16 Jul 2021 21:40:28 +0200
Subject: [PATCH] Implement firewall - settings in iptables_rules.json -
 creates a script under /tmp/iptables_raspap.sh and executes it - no installer
 yet - to do: deal with Bridge and VPN settings

---
 config/iptables_rules.json | 168 +++++++++++++++++++++++++++++++++++
 includes/firewall.php      | 174 +++++++++++++++++++++++++++++++++++++
 installers/raspap.sudoers  |   1 +
 templates/firewall.php     |  70 +++++++++++++++
 4 files changed, 413 insertions(+)
 create mode 100644 config/iptables_rules.json
 create mode 100644 includes/firewall.php
 create mode 100644 templates/firewall.php

diff --git a/config/iptables_rules.json b/config/iptables_rules.json
new file mode 100644
index 00000000..fa23d707
--- /dev/null
+++ b/config/iptables_rules.json
@@ -0,0 +1,168 @@
+{
+    "info": "IPTABLES rules. $...$ expressions will be replaces automatically ($INTERFACE$, $PORT$, $IPADDRESS$)",
+    "rules_v4_file": "/etc/iptables/rules.v4",
+    "rules_v6_file": "/etc/iptables/rules.v6",
+    "order": [ "pre_rules", "restriction_rules", "main_rules", "exception_rules" ],
+    "pre_rules": [
+        {
+            "name": "firewall policies",
+            "fw-state": true,
+            "comment": "Policy rules (firewall)",
+            "rules": [
+                "-P INPUT DROP",
+                "-P FORWARD ACCEPT",
+                "-P OUTPUT ACCEPT",
+                "-t nat -P PREROUTING ACCEPT",
+                "-t nat -P POSTROUTING ACCEPT",
+                "-t nat -P INPUT ACCEPT",
+                "-t nat -P OUTPUT ACCEPT"
+            ]
+        },
+        {
+            "name": "policies",
+            "fw-state": false,
+            "comment": "Policy rules",
+            "rules": [
+                "-P INPUT ACCEPT",
+                "-P FORWARD ACCEPT",
+                "-P OUTPUT ACCEPT",
+                "-t nat -P PREROUTING ACCEPT",
+                "-t nat -P POSTROUTING ACCEPT",
+                "-t nat -P INPUT ACCEPT",
+                "-t nat -P OUTPUT ACCEPT"
+            ]
+        },
+        {
+            "name": "loopback",
+            "fw-state": true,
+            "comment": "allow loopback device",
+            "rules": [
+                "-A INPUT -i lo -j ACCEPT",
+                "-A OUTPUT -o lo -j ACCEPT"
+            ]
+        },
+        {
+            "name": "ping",
+            "fw-state": true,
+            "comment": "allow ping request and echo",
+            "rules": [
+                "-A INPUT -p icmp --icmp-type 8/0 -j ACCEPT",
+                "-A INPUT -p icmp --icmp-type 0/0 -j ACCEPT"
+            ]
+        },
+        {
+            "name": "ntp",
+            "fw-state": true,
+            "comment": "allow ntp request via udp (tcp should work w/o rule)",
+            "rules": [
+                "-A INPUT -p udp --sport 123 -j ACCEPT"
+            ]
+        },
+        {
+            "name": "dns",
+            "fw-state": true,
+            "comment": "allow dns request via tcp and udp",
+            "rules": [
+                "-A INPUT -p udp -m multiport --sport 53,853 -j ACCEPT",
+                "-A INPUT -p tcp -m multiport --sport 53,853 -j ACCEPT"
+            ]
+        }
+    ],
+    "main_rules": [
+        {
+            "name": "accesspoint",
+            "fw-state": true,
+            "comment": "Access point interface by default no restrictions",
+            "dependson": [
+                    { "var": "ap-device", "type": "string", "replace": "$INTERFACE$" }
+            ],
+            "rules": [
+                    "-A INPUT -i $INTERFACE$ -j ACCEPT",
+                    "-A OUTPUT -o $INTERFACE$ -j ACCEPT"
+            ]
+        },
+        {
+            "name": "clients",
+            "fw-state": true,
+            "comment": "Rules for client interfaces (includes tun device)",
+            "rules": [
+                "-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT"
+            ]
+        },
+        {
+            "name": "openvpn",
+            "comment": "Rules for tunnel device (tun)",
+            "dependson": [
+                  { "var": "openvpn-enable", "type": "bool" },
+                  { "var": "openvpn-serverip", "type": "string", "replace": "$IPADDRESS$" },
+                  { "var": "client-device", "type": "string", "replace": "$INTERFACE$" }
+            ],
+            "rules": [
+                "-A FORWARD -i tun+ -o $INTERFACE$ -m state --state RELATED,ESTABLISHED -j ACCEPT",
+                "-A FORWARD -i $INTERFACE$ -o tun+ -j ACCEPT",
+                "-t nat -A POSTROUTING -o tun+ -j MASQUERADE"
+            ]
+        }
+    ],
+    "exception_rules": [
+        {
+            "name": "ssh",
+            "fw-state": true,
+            "comment": "Allow ssh access to RaspAP on port 22",
+            "dependson": [
+                { "var": "ssh-enable", "type": "bool" }
+            ],
+            "rules": [
+                "-A INPUT -p tcp --dport 22 -j ACCEPT"
+            ]
+        },
+        {
+            "name": "http",
+            "fw-state": true,
+            "comment": "Allow access to RaspAP GUI (https)",
+            "dependson": [
+                { "var": "http-enable", "type": "bool" }
+            ],
+            "rules": [
+                "-A INPUT -p tcp -m multiport --dports 80,443 -j ACCEPT"
+            ]
+        },
+        {
+            "name": "interface",
+            "fw-state": true,
+            "comment": "Exclude interface from firewall",
+            "dependson": [
+                { "var": "excl-devices", "type": "list", "replace": "$INTERFACE$" }
+            ],
+            "rules": [
+                "-A INPUT -i $INTERFACE$ -j ACCEPT",
+                "-A OUTPUT -o $INTERFACE$ -j ACCEPT"
+            ]
+        },
+        {
+            "name": "ipaddress",
+            "fw-state": true,
+            "comment": "allow access from/to IP",
+            "dependson": [
+                { "var": "excluded-ips", "type": "list", "replace": "$IPADDRESS$" }
+            ],
+            "rules": [
+                "-A INPUT -s $IPADDRESS$ -j ACCEPT",
+                "-A INPUT -d $IPADDRESS$ -j ACCEPT"
+            ]
+        }
+    ],
+    "restriction_rules": [
+        {
+            "name": "ipaddress",
+            "fw-state": true,
+            "dependson": [
+                { "var": "restricted-ips", "type": "list", "replace": "$IPADDRESS$" }
+            ],
+            "comment": "Block access from IP-address",
+            "rules": [
+                "-A INPUT -s $IPADDRESS$ -j DROP"
+            ]
+        }
+    ]
+}
diff --git a/includes/firewall.php b/includes/firewall.php
new file mode 100644
index 00000000..ceac3748
--- /dev/null
+++ b/includes/firewall.php
@@ -0,0 +1,174 @@
+<?php
+
+require_once 'includes/status_messages.php';
+require_once 'includes/functions.php';
+
+define(RASPAP_FIREWALL_CONF,"/tmp/iptables.conf");
+define(RASPAP_IPTABLES_CONF,"/etc/raspap/networking/firewall/iptables_rules.json");
+define(RASPAP_IPTABLES_SCRIPT,"/tmp/iptables_raspap.sh");
+
+function getDependson(&$rule, &$conf) {
+   if ( isset($rule["dependson"][0]) ) {
+      $don = &$rule["dependson"];
+      if ( !empty($don[0]) && isset($conf[$don[0]["var"]]) ) {
+         if ( !isset($don[0]["type"]) ) $don[0]["type"]="bool";
+         return $don;
+      }
+   }
+   return false;
+}
+
+function isRuleEnabled(&$sect, &$conf) {
+   $fw_on = isset($conf["firewall-enable"]) && $conf["firewall-enable"];
+   $active = isset($sect["fw-state"]) && $sect["fw-state"]==1;
+   $active = $fw_on ? $active : !$active;
+   $active = $active || !isset($sect["fw-state"]);
+   if ( ($don = getDependson($sect, $conf)) !== false &&
+         $don[0]["type"] == "bool" && !$conf[$don[0]["var"]] )  $active = false;
+   return $active;
+}
+
+function createRuleStr(&$sect, &$conf) {
+   if ( !is_array($sect["rules"]) ) return "";
+   $rules = $sect["rules"];
+   $depon = getDependson($sect,$conf);
+   $rs = array();
+   foreach ( $rules as $rule ) {
+      if ( preg_match('/\$[a-z0-9]*\$/i',$rule) ) {
+         $r = array($rule);
+         foreach ( $depon as $dep ) {
+            $rr = array();
+            $repl=$val="";
+            switch ( $dep["type"] ) {
+               case "list":
+                   if ( isset($dep["var"]) && !empty($conf[$dep["var"]]) ) $val = explode(',', $conf[$dep["var"]]);
+                   if ( !empty($val) && isset($dep["replace"]) ) $repl=$dep["replace"];
+                   break;
+               case "string":
+                   if ( isset($dep["var"]) ) $val=$conf[$dep["var"]];
+                   if ( !empty($val) && isset($dep["replace"]) ) $repl=$dep["replace"];
+                   break;
+               default:
+                   break;
+            }
+            if ( !empty($repl) && !empty($val) ) {
+//echo "replace $repl $val \n"; //print_r( $val); echo "\n";
+               if ( is_array($val) ) {
+                  foreach ( $val as $v ) $rr = array_merge($rr,str_replace($repl, $v, $r));
+               }
+               else $rr = array_merge($rr, str_replace($repl, $val, $r));
+            }
+            $r = !empty($rr) ? $rr : $r;
+         }
+         $rs = array_merge($rs,$rr);
+      } else {
+         $rs[] = $rule;
+      }
+   }
+   $str="";
+   foreach ( $rs as $r ) {
+      if ( !preg_match('/\$[a-z0-9]*\$/i',$r) ) $str .= "iptables ".$r."\n";
+   }
+   return $str;
+}
+
+function setFirewall() {
+    $json = file_get_contents(RASPAP_IPTABLES_CONF);
+    $ipt  = json_decode($json, true);
+    $conf = ReadFirewallConf();
+
+//echo "<pre>";
+// print_r($ipt);
+    $txt = "#!/bin/bash\n";
+    $txt .= "iptables -F\n";
+    $txt .= "iptables -X\n";
+    $txt .= "iptables -t nat -F\n";
+    file_put_contents(RASPAP_IPTABLES_SCRIPT, $txt);
+    if ( empty($conf) || empty($ipt) ) return false;
+    $count=0;
+    foreach ( $ipt["order"] as $idx ) {
+       if ( isset($ipt[$idx]) ) {
+//          echo "Handle $idx \n";
+          foreach ( $ipt[$idx] as $i => $sect ) {
+             if ( isRuleEnabled($sect, $conf) ) {
+//               echo "   rule $i name ".$sect["name"]."\n";
+               $str_rules= createRuleStr($sect, $conf);
+               if ( !empty($str_rules) ) {
+                  file_put_contents(RASPAP_IPTABLES_SCRIPT, $str_rules, FILE_APPEND);
+                  ++$count;
+               }
+             }
+          }
+       }
+    }
+//    echo "Firewall ON";
+//echo "</pre>";
+    if ( $count > 0 ) {
+       exec("chmod +x ".RASPAP_IPTABLES_SCRIPT);
+       exec("sudo ".RASPAP_IPTABLES_SCRIPT);
+//       exec("sudo iptables-save > /etc/iptables/rules.v4");
+//       unlink(RASPAP_IPTABLES_SCRIPT);
+    }
+    return ($count > 0);
+}
+
+function WriteFirewallConf($conf) {
+     if ( is_array($conf) ) write_php_ini($conf,RASPAP_FIREWALL_CONF);
+}
+
+
+function ReadFirewallConf() {
+    if ( file_exists(RASPAP_FIREWALL_CONF) ) {
+       $conf = parse_ini_file(RASPAP_FIREWALL_CONF);
+    } else {
+       $conf = array();
+       $conf["firewall-enable"] = false;
+       $conf["openvpn-enable"] = false;
+       $conf["openvpn-serverip"] = "";
+       $conf["wireguard-enable"] = false;
+       $conf["wireguard-serverip"] = "";
+       $conf["ssh-enable"] = false;
+       $conf["http-enable"] = false;
+       $conf["excl-devices"] = "";
+       $conf["excluded-ips"] = "";
+       $conf["ap-device"] = "";
+       $conf["client-device"] = "";
+       $conf["restricted-ips"] = "";
+    }
+    return $conf;
+}
+
+function DisplayFirewallConfig()
+{
+
+    $status = new StatusMessages();
+
+    $json = file_get_contents(RASPAP_IPTABLES_CONF);
+    $ipt_rules = json_decode($json, true);
+
+    getWifiInterface();
+    $ap_device = $_SESSION['ap_interface'];
+    $clients = getClients();
+    $fw_conf = ReadFirewallConf();
+    $fw_conf["ap-device"] = $ap_device;
+    $id=findCurrentClientIndex($clients);
+    if ( $id >= 0 ) $fw_conf["client-device"] = $clients["device"][$id]["name"];
+    if (!empty($_POST)) {
+        $fw_conf["ssh-enable"] = isset($_POST['ssh-enable']);
+        $fw_conf["http-enable"] = isset($_POST['http-enable']);
+        $fw_conf["firewall-enable"] = isset($_POST['firewall-enable']) || isset($_POST['apply-firewall']);
+        if ( isset($_POST['firewall-enable']) ) $status->addMessage(_('Firewall is now enabled'), 'success');
+        if ( isset($_POST['apply-firewall']) )  $status->addMessage(_('Firewall settings changed'), 'success');
+        if ( isset($_POST['firewall-disable']) ) $status->addMessage(_('Firewall is now disabled'), 'warning');
+        if ( isset($_POST['save-firewall']) )  $status->addMessage(_('Firewall settings saved. Firewall is still disabled.'), 'success');
+        WriteFirewallConf($fw_conf);
+        setFirewall();
+    }
+    echo renderTemplate("firewall", compact(
+                "status",
+                "ap_device",
+                "clients",
+                "fw_conf",
+                "ipt_rules")
+    );
+}
diff --git a/installers/raspap.sudoers b/installers/raspap.sudoers
index 7ce40f28..ae737910 100644
--- a/installers/raspap.sudoers
+++ b/installers/raspap.sudoers
@@ -62,3 +62,4 @@ www-data ALL=(ALL) NOPASSWD:/bin/cat /etc/wireguard/*.conf
 www-data ALL=(ALL) NOPASSWD:/bin/cat /etc/wireguard/wg-*.key
 www-data ALL=(ALL) NOPASSWD:/bin/rm /etc/wireguard/*.conf
 www-data ALL=(ALL) NOPASSWD:/bin/rm /etc/wireguard/wg-*.key
+www-data ALL=(ALL) NOPASSWD:/tmp/iptables_raspap.sh
diff --git a/templates/firewall.php b/templates/firewall.php
new file mode 100644
index 00000000..39e41b71
--- /dev/null
+++ b/templates/firewall.php
@@ -0,0 +1,70 @@
+<div class="row">
+  <div class="col-lg-12">
+    <div class="card">
+      <div class="card-header">
+        <div class="row">
+          <div class="col">
+            <i class="fas fa-shield-alt mr-2"></i><?php echo _("Firewall"); ?>
+          </div>
+        </div><!-- /.row -->
+      </div><!-- /.card-header -->
+      <div class="card-body">
+        <?php $status->showMessages(); ?>
+        <h4><?php echo _("Client Firewall"); ?></h4>
+        <?php if ( $fw_conf["firewall-enable"]) : ?>
+           <i class="fas fa-circle mr-2 service-status-up"></i><?php echo _("Firewall is ENABLED"); ?>
+        <?php else : ?>
+           <i class="fas fa-circle mr-2 service-status-down"></i><?php echo _("Firewall is OFF "); ?>
+        <?php endif ?>
+        <div class="row">
+          <div class="col-md-6">
+            <p class="mr-2"><small><?php echo _("The default firewall will allow only outgoing and already established traffic. No UDP traffic is allowed.") ?></small></p>
+          </div>
+        </div>
+
+        <form id="frm-firewall" action="firewall_conf" method="POST" >
+          <?php echo CSRFTokenFieldTag(); ?>
+          <h5><?php echo _("Exceptions for Services"); ?></h4>
+          <div class="row">
+            <div class="form-group col-md-6">
+                <div class="custom-control custom-switch">
+                    <input class="custom-control-input" id="ssh-enable" type="checkbox" name="ssh-enable" value="1" aria-describedby="exceptions-description" <?php if ($fw_conf["ssh-enable"]) echo "checked"; ?> >
+                    <label class="custom-control-label" for="ssh-enable"><?php echo _("allow SSH access on port 22") ?></label>
+                </div>
+                <div class="custom-control custom-switch">
+                    <input class="custom-control-input" id="http-enable" type="checkbox" name="http-enable" value="1" aria-describedby="exceptions-description" <?php if ($fw_conf["http-enable"]) echo "checked"; ?> >
+                    <label class="custom-control-label" for="http-enable"><?php echo _("allow access to the RaspAP GUI") ?></label>
+                </div>
+                <p class="mb-0" id="exceptions-description">
+                    <small><?php echo _("Allow access for some services from the client side.") ?></small>
+                </p>
+            </div>
+          </div>
+          <?php if ($fw_conf["firewall-enable"]) : ?>
+              <input type="submit" class="btn btn-outline btn-primary" value="<?php echo _("Apply changes"); ?>" name="apply-firewall" />
+              <input type="submit" class="btn btn-warning firewall-apply" value="<?php echo _("Disable Firewall") ?>"  name="firewall-disable" data-toggle="modal" data-target="#firewallModal"/>
+          <?php else : ?>
+              <input type="submit" class="btn btn-outline btn-primary" value="<?php echo _("Save"); ?>" name="save-firewall" />
+              <input type="submit" class="btn btn-success firewall-apply" value="<?php echo _("Enable Firewall") ?>" name="firewall-enable" data-toggle="modal" data-target="#firewallModal"/>
+          <?php endif ?>
+        </form>
+      </div><!-- /.card-body -->
+      <div class="card-footer"></div>
+    </div><!-- /.card -->
+  </div><!-- /.col-lg-12 -->
+</div><!-- /.row -->
+
+<!-- Modal -->
+<div class="modal fade" id="firewallModal" tabindex="-1" role="dialog" aria-labelledby="ModalLabel" aria-hidden="true">
+  <div class="modal-dialog" role="document">
+    <div class="modal-content">
+      <div class="modal-header">
+        <div class="modal-title" id="ModalLabel">
+            <i class="fas fa-sync-alt mr-2"></i>
+            <?php if($fw_conf["firewall-enable"]) echo _("Disable the firewall ..."); else  echo _("Enable the Firewall ..."); ?>
+        </div>
+        <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">&times;</span>
+      </div>
+  </div>
+</div>
+