From b49a04f796b9ad8533c53fee541132a4c2214909 Mon Sep 17 00:00:00 2001
From: ArthurHoaro <arthur@hoa.ro>
Date: Sat, 9 Feb 2019 16:44:48 +0100
Subject: Rewrite IP ban management

This adds a dedicated manager class to handle all ban interactions, which is instantiated and handled by LoginManager.
IPs are now stored in the same format as the datastore, through FileUtils.

Fixes #1032 #587
---
 application/security/BanManager.php | 213 ++++++++++++++++++++++++++++++++++++
 1 file changed, 213 insertions(+)
 create mode 100644 application/security/BanManager.php

(limited to 'application/security/BanManager.php')

diff --git a/application/security/BanManager.php b/application/security/BanManager.php
new file mode 100644
index 00000000..68190c54
--- /dev/null
+++ b/application/security/BanManager.php
@@ -0,0 +1,213 @@
+<?php
+
+
+namespace Shaarli\Security;
+
+use Shaarli\FileUtils;
+
+/**
+ * Class BanManager
+ *
+ * Failed login attempts will store the associated IP address.
+ * After N failed attempts, the IP will be prevented from log in for duration D.
+ * Both N and D can be set in the configuration file.
+ *
+ * @package Shaarli\Security
+ */
+class BanManager
+{
+    /** @var array List of allowed proxies IP */
+    protected $trustedProxies;
+
+    /** @var int Number of allowed failed attempt before the ban */
+    protected $nbAttempts;
+
+    /** @var  int Ban duration in seconds */
+    protected $banDuration;
+
+    /** @var string Path to the file containing IP bans and failures */
+    protected $banFile;
+
+    /** @var string Path to the log file, used to log bans */
+    protected $logFile;
+
+    /** @var array List of IP with their associated number of failed attempts */
+    protected $failures = [];
+
+    /** @var array List of banned IP with their associated unban timestamp */
+    protected $bans = [];
+
+    /**
+     * BanManager constructor.
+     *
+     * @param array  $trustedProxies List of allowed proxies IP
+     * @param int    $nbAttempts     Number of allowed failed attempt before the ban
+     * @param int    $banDuration    Ban duration in seconds
+     * @param string $banFile        Path to the file containing IP bans and failures
+     * @param string $logFile        Path to the log file, used to log bans
+     */
+    public function __construct($trustedProxies, $nbAttempts, $banDuration, $banFile, $logFile) {
+        $this->trustedProxies = $trustedProxies;
+        $this->nbAttempts = $nbAttempts;
+        $this->banDuration = $banDuration;
+        $this->banFile = $banFile;
+        $this->logFile = $logFile;
+        $this->readBanFile();
+    }
+
+    /**
+     * Handle a failed login and ban the IP after too many failed attempts
+     *
+     * @param array $server The $_SERVER array
+     */
+    public function handleFailedAttempt($server)
+    {
+        $ip = $this->getIp($server);
+        // the IP is behind a trusted forward proxy, but is not forwarded
+        // in the HTTP headers, so we do nothing
+        if (empty($ip)) {
+            return;
+        }
+
+        // increment the fail count for this IP
+        if (isset($this->failures[$ip])) {
+            $this->failures[$ip]++;
+        } else {
+            $this->failures[$ip] = 1;
+        }
+
+        if ($this->failures[$ip] >= $this->nbAttempts) {
+            $this->bans[$ip] = time() + $this->banDuration;
+            logm(
+                $this->logFile,
+                $server['REMOTE_ADDR'],
+                'IP address banned from login: '. $ip
+            );
+        }
+        $this->writeBanFile();
+    }
+
+    /**
+     * Remove failed attempts for the provided client.
+     *
+     * @param array $server $_SERVER
+     */
+    public function clearFailures($server)
+    {
+        $ip = $this->getIp($server);
+        // the IP is behind a trusted forward proxy, but is not forwarded
+        // in the HTTP headers, so we do nothing
+        if (empty($ip)) {
+            return;
+        }
+
+        if (isset($this->failures[$ip])) {
+            unset($this->failures[$ip]);
+        }
+        $this->writeBanFile();
+    }
+
+    /**
+     * Check whether the client IP is banned or not.
+     *
+     * @param array $server $_SERVER
+     *
+     * @return bool True if the IP is banned, false otherwise
+     */
+    public function isBanned($server)
+    {
+        $ip = $this->getIp($server);
+        // the IP is behind a trusted forward proxy, but is not forwarded
+        // in the HTTP headers, so we allow the authentication attempt.
+        if (empty($ip)) {
+            return false;
+        }
+
+        // the user is not banned
+        if (! isset($this->bans[$ip])) {
+            return false;
+        }
+
+        // the user is still banned
+        if ($this->bans[$ip] > time()) {
+            return true;
+        }
+
+        // the ban has expired, the user can attempt to log in again
+        if (isset($this->failures[$ip])) {
+            unset($this->failures[$ip]);
+        }
+        unset($this->bans[$ip]);
+        logm($this->logFile, $server['REMOTE_ADDR'], 'Ban lifted for: '. $ip);
+
+        $this->writeBanFile();
+        return false;
+    }
+
+    /**
+     * Retrieve the IP from $_SERVER.
+     * If the actual IP is behind an allowed reverse proxy,
+     * we try to extract the forwarded IP from HTTP headers.
+     *
+     * @param array $server $_SERVER
+     *
+     * @return string|bool The IP or false if none could be extracted
+     */
+    protected function getIp($server)
+    {
+        $ip = $server['REMOTE_ADDR'];
+        if (! in_array($ip, $this->trustedProxies)) {
+            return $ip;
+        }
+        return getIpAddressFromProxy($server, $this->trustedProxies);
+    }
+
+    /**
+     * Read a file containing banned IPs
+     */
+    protected function readBanFile()
+    {
+        $data = FileUtils::readFlatDB($this->banFile);
+        if (isset($data['failures']) && is_array($data['failures'])) {
+            $this->failures = $data['failures'];
+        }
+
+        if (isset($data['bans']) && is_array($data['bans'])) {
+            $this->bans = $data['bans'];
+        }
+    }
+
+    /**
+     * Write the banned IPs to a file
+     */
+    protected function writeBanFile()
+    {
+        return FileUtils::writeFlatDB(
+            $this->banFile,
+            [
+                'failures' => $this->failures,
+                'bans' => $this->bans,
+            ]
+        );
+    }
+
+    /**
+     * Get the Failures (for UT purpose).
+     *
+     * @return array
+     */
+    public function getFailures()
+    {
+        return $this->failures;
+    }
+
+    /**
+     * Get the Bans (for UT purpose).
+     *
+     * @return array
+     */
+    public function getBans()
+    {
+        return $this->bans;
+    }
+}
-- 
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