fix: harden database backup imports

2026-08-20 08:23:25 +00:00 · 2026-06-29 10:27:01 +02:00
parent e7dff30b7c
commit 2d63d51237
5 changed files with 471 additions and 44 deletions
@@ -0,0 +1,209 @@
+<?php
+
+namespace App\Support;
+
+use Illuminate\Http\UploadedFile;
+
+class DatabaseBackupFileValidator
+{
+    public const ALLOWED_EXTENSIONS = [
+        'sql',
+        'sql.gz',
+        'gz',
+        'zip',
+        'tar',
+        'tar.gz',
+        'tgz',
+        'dump',
+        'bak',
+        'bson',
+        'bson.gz',
+        'archive',
+        'archive.gz',
+        'bz2',
+        'xz',
+        'dmp',
+    ];
+
+    private const DANGEROUS_EXTENSIONS = [
+        'asp',
+        'aspx',
+        'bat',
+        'bash',
+        'cgi',
+        'cmd',
+        'com',
+        'exe',
+        'htm',
+        'html',
+        'jar',
+        'js',
+        'jsp',
+        'php',
+        'php3',
+        'php4',
+        'php5',
+        'phtml',
+        'pl',
+        'ps1',
+        'py',
+        'rb',
+        'sh',
+    ];
+
+    public static function hasAllowedExtension(string $name): bool
+    {
+        return self::extensionFor($name) !== null;
+    }
+
+    public static function isUploadAllowed(UploadedFile $file, int $maxBytes): bool
+    {
+        $originalName = $file->getClientOriginalName();
+        $size = $file->getSize();
+
+        if ($size === false || $size > $maxBytes) {
+            return false;
+        }
+
+        $extension = self::extensionFor($originalName);
+        if ($extension === null) {
+            return false;
+        }
+
+        return self::contentMatchesExtension($file->getPathname(), $extension);
+    }
+
+    /**
+     * Scan a stored backup file (decompressing gzip on the fly) for PostgreSQL
+     * restore directives that lead to OS command execution.
+     */
+    public static function fileContainsPostgresqlProgramExecution(string $path): bool
+    {
+        $contents = self::readPossiblyGzippedText($path);
+
+        if ($contents === null) {
+            return false;
+        }
+
+        return self::containsPostgresqlProgramExecution($contents);
+    }
+
+    public static function containsPostgresqlProgramExecution(string $sql): bool
+    {
+        $withoutComments = self::stripSqlComments($sql);
+
+        if (preg_match('/^\s*\\\\(?:!|copy\b.*\bprogram\b)/mi', $withoutComments) === 1) {
+            return true;
+        }
+
+        return preg_match('/\bcopy\b[\s\S]{0,2000}\b(?:from|to)\s+program\b/i', $withoutComments) === 1;
+    }
+
+    private static function extensionFor(string $name): ?string
+    {
+        $lower = strtolower($name);
+        $suffixes = array_map(fn (string $ext) => '.'.$ext, self::ALLOWED_EXTENSIONS);
+        usort($suffixes, fn (string $a, string $b) => strlen($b) <=> strlen($a));
+
+        foreach ($suffixes as $suffix) {
+            if (! str_ends_with($lower, $suffix)) {
+                continue;
+            }
+
+            $stem = substr($lower, 0, -strlen($suffix));
+            if ($stem === '' || str_ends_with($stem, '.')) {
+                return null;
+            }
+
+            $parts = array_filter(explode('.', $stem));
+            if (array_intersect($parts, self::DANGEROUS_EXTENSIONS) !== []) {
+                return null;
+            }
+
+            return ltrim($suffix, '.');
+        }
+
+        return null;
+    }
+
+    private static function contentMatchesExtension(string $path, string $extension): bool
+    {
+        $sample = (string) file_get_contents($path, false, null, 0, 4096);
+
+        return match ($extension) {
+            'sql' => self::looksLikeText($sample) && ! self::containsPostgresqlProgramExecution($sample),
+            'sql.gz', 'gz', 'tar.gz', 'tgz', 'bson.gz', 'archive.gz' => str_starts_with($sample, "\x1f\x8b"),
+            'zip' => str_starts_with($sample, "PK\x03\x04") || str_starts_with($sample, "PK\x05\x06") || str_starts_with($sample, "PK\x07\x08"),
+            'tar' => substr($sample, 257, 5) === 'ustar',
+            'bz2' => str_starts_with($sample, 'BZh'),
+            'xz' => str_starts_with($sample, "\xfd7zXZ\x00"),
+            'dump', 'bak', 'archive', 'dmp' => str_starts_with($sample, 'PGDMP')
+                || (self::looksLikeText($sample) && ! self::containsPostgresqlProgramExecution($sample)),
+            'bson' => self::looksLikeBson($path, $sample),
+            default => false,
+        };
+    }
+
+    private static function readPossiblyGzippedText(string $path): ?string
+    {
+        // Cap the scan so a huge legitimate dump cannot exhaust memory; the
+        // remote pre-restore scanner inspects the full file as a second layer.
+        $maxBytes = 50 * 1024 * 1024;
+
+        $handle = @fopen($path, 'rb');
+        if ($handle === false) {
+            return null;
+        }
+        $magic = (string) fread($handle, 2);
+        fclose($handle);
+
+        if ($magic === "\x1f\x8b") {
+            $gz = @gzopen($path, 'rb');
+            if ($gz === false) {
+                return null;
+            }
+
+            $data = '';
+            while (! gzeof($gz) && strlen($data) < $maxBytes) {
+                $chunk = gzread($gz, 1024 * 1024);
+                if ($chunk === false || $chunk === '') {
+                    break;
+                }
+                $data .= $chunk;
+            }
+            gzclose($gz);
+
+            return $data;
+        }
+
+        return (string) file_get_contents($path, false, null, 0, $maxBytes);
+    }
+
+    private static function looksLikeText(string $sample): bool
+    {
+        if ($sample === '' || str_contains($sample, "\0")) {
+            return false;
+        }
+
+        return mb_check_encoding($sample, 'UTF-8') || mb_check_encoding($sample, 'ASCII');
+    }
+
+    private static function looksLikeBson(string $path, string $sample): bool
+    {
+        if (strlen($sample) < 5) {
+            return false;
+        }
+
+        $documentLength = unpack('V', substr($sample, 0, 4))[1] ?? 0;
+        $fileSize = filesize($path) ?: 0;
+
+        return $documentLength >= 5 && $documentLength <= $fileSize;
+    }
+
+    private static function stripSqlComments(string $sql): string
+    {
+        $sql = preg_replace('/\/\*[\s\S]*?\*\//', ' ', $sql) ?? $sql;
+
+        return preg_replace('/--[^\r\n]*/', ' ', $sql) ?? $sql;
+    }
+}