Add Phan plugin to check for SQL injections

This adds a phan plugin which checks for SQL injections on code using our QueryBuilder, while it isn't perfect it should already catch most potential issues.

As always, static analysis will sometimes have false positives and this is also here the case. So in some cases the analyzer just doesn't know if something is potential user input or not, thus I had to add some `@suppress SqlInjectionChecker` in front of those potential injections.

The Phan plugin hasn't the most awesome code but it works and I also added a file with test cases.

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

4 files changed, 255 insertions, 0 deletions

diff --git a/build/.phan/config.php b/build/.phan/config.php
index 0e3e2788510..26421529433 100644
--- a/build/.phan/config.php
+++ b/build/.phan/config.php
@@ -151,4 +151,9 @@ return [
 	'whitelist_issue_types' => [
 		// 'PhanAccessMethodPrivate',
 	],
+
+	// A list of plugin files to execute
+	'plugins' => [
+		'build/.phan/plugins/SqlInjectionCheckerPlugin.php',
+	],
 ];
diff --git a/build/.phan/plugin-checker.php b/build/.phan/plugin-checker.php
new file mode 100644
index 00000000000..681904264f6
--- /dev/null
+++ b/build/.phan/plugin-checker.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+$expected = <<<EOT
+build/.phan/tests/SqlInjectionCheckerTest.php:23 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:35 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:37 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:39 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:41 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:43 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:54 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:61 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:62 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:69 SqlInjectionChecker Potential SQL injection detected
+build/.phan/tests/SqlInjectionCheckerTest.php:70 SqlInjectionChecker Potential SQL injection detected
+
+EOT;
+
+$result = shell_exec('php '. __DIR__ . '/../../lib/composer/etsy/phan/phan -k build/.phan/config.php --include-analysis-file-list build/.phan/tests/* --directory build/.phan/tests/');
+
+if($result !== $expected) {
+	echo("Output of phan doesn't match expectation\n");
+	echo("Expected: $expected\n");
+	echo("Result: $result\n");
+	exit(1);
+}
diff --git a/build/.phan/plugins/SqlInjectionCheckerPlugin.php b/build/.phan/plugins/SqlInjectionCheckerPlugin.php
new file mode 100644
index 00000000000..8cfd5ac4752
--- /dev/null
+++ b/build/.phan/plugins/SqlInjectionCheckerPlugin.php
@@ -0,0 +1,134 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+declare(strict_types=1);
+
+use Phan\PluginV2;
+use Phan\PluginV2\AnalyzeNodeCapability;
+use Phan\PluginV2\PluginAwareAnalysisVisitor;
+
+class SqlInjectionCheckerPlugin extends PluginV2  implements AnalyzeNodeCapability{
+	public static function getAnalyzeNodeVisitorClassName() : string {
+		return SqlInjectionCheckerVisitor::class;
+	}
+}
+
+class SqlInjectionCheckerVisitor extends PluginAwareAnalysisVisitor  {
+
+	private function throwError() {
+		$this->emit(
+			'SqlInjectionChecker',
+			'Potential SQL injection detected',
+			[],
+			\Phan\Issue::SEVERITY_CRITICAL
+		);
+	}
+
+	/**
+	 * Checks whether the query builder functions are using prepared statements
+	 *
+	 * @param \ast\Node $node
+	 */
+	private function checkQueryBuilderParameters(\ast\Node $node) {
+		$dangerousFunctions = [
+			'eq',
+			'neq',
+			'lt',
+			'lte',
+			'gt',
+			'gte',
+			'like',
+			'iLike',
+			'notLike',
+		];
+
+		$safeFunctions = [
+			'createNamedParameter',
+			'createPositionalParameter',
+			'createParameter',
+		];
+
+		$functionsToSearch = [
+			'set',
+			'setValue',
+		];
+
+		$expandedNode = \Phan\Language\UnionType::fromNode($this->context, $this->code_base, $node);
+		$expandedNodeType = (string)$expandedNode->asExpandedTypes($this->code_base);
+
+		if($expandedNodeType === '\OCP\DB\QueryBuilder\IQueryBuilder') {
+			/** @var \ast\Node $child */
+			foreach($node->children as $child) {
+				if(isset($child->kind) && $child->kind === 128) {
+					if(isset($child->children)) {
+						/** @var \ast\Node $subChild */
+						foreach ($child->children as $subChild) {
+							// For set actions
+							if(isset($node->children['method']) && in_array($node->children['method'], $functionsToSearch, true) && !is_string($subChild)) {
+								if(!isset($subChild->children['method']) || !in_array($subChild->children['method'], $safeFunctions, true)) {
+									$this->throwError();
+								}
+							}
+
+							if(isset($subChild->children['method'])) {
+								// For all "eq" etc. actions
+								$method = $subChild->children['method'];
+								if(!in_array($method, $dangerousFunctions, true)) {
+									return;
+								}
+
+								/** @var \ast\Node $functionNode */
+								$functionNode = $subChild->children['args'];
+
+								/** @var \ast\Node $secondParameterNode */
+								$secondParameterNode = $functionNode->children[1];
+								$expandedNode = \Phan\Language\UnionType::fromNode($this->context, $this->code_base, $secondParameterNode);
+
+								// For literals with a plain string or integer inside
+								if(isset($secondParameterNode->children['method']) && $secondParameterNode->children['method'] === 'literal') {
+									/** @var \ast\Node $functionNode */
+									$functionNode = $secondParameterNode->children['args'];
+
+									$expandedNode = \Phan\Language\UnionType::fromNode($this->context, $this->code_base, $functionNode);
+									if(isset($functionNode->children[0]) && (is_string($functionNode->children[0]) || is_int($functionNode->children[0]))) {
+										return;
+									}
+								}
+
+								// If it is an IParameter or a pure string no error is thrown
+								if((string)$expandedNode !== '\OCP\DB\QueryBuilder\IParameter' && !is_string($secondParameterNode)) {
+									$this->throwError();
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	public function visitMethodCall(\ast\Node $node) {
+		$this->checkQueryBuilderParameters($node);
+	}
+
+}
+
+return new SqlInjectionCheckerPlugin();
diff --git a/build/.phan/tests/SqlInjectionCheckerTest.php b/build/.phan/tests/SqlInjectionCheckerTest.php
new file mode 100644
index 00000000000..3824d5c1704
--- /dev/null
+++ b/build/.phan/tests/SqlInjectionCheckerTest.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+$builder = \OC::$server->getDatabaseConnection()->getQueryBuilder();
+$builder->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $_GET['asdf']));
+
+class SqlInjectionCheckerTest {
+	private $qb;
+
+	public function __construct(\OCP\IDBConnection $dbConnection) {
+		$this->qb = $dbConnection->getQueryBuilder();
+	}
+
+	public function testEqAndNeq() {
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $this->qb->expr()->literal('myString')));
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $this->qb->expr()->literal(0)));
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $this->qb->expr()->literal($_GET['bar'])));
+		$asdf = '123';
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $this->qb->expr()->literal($asdf)));
+		$asdf = 1;
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->neq('asdf', $asdf));
+		$asdf = '123';
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->lt('asdf', $asdf));
+		$this->qb->select('*')->from('ado')->where($this->qb->expr()->eq('s.resourceid', 'a.id'));
+		$this->qb->select('*')->from('ado')->andWhere($this->qb->expr()->gte('asdf', $_GET['asdf']));
+		$this->qb->select('*')
+			->from('ado')
+			->where($this->qb->expr()->eq('asdf', $this->qb->createNamedParameter('asdf')));
+		$this->qb->select('*')
+			->from('ado')
+			->where($this->qb->expr()->eq('asdf', $this->qb->createPositionalParameter('asdf')));
+	}
+
+	public function testInstantiatingDatabaseConnection() {
+		$qb = \OC::$server->getDatabaseConnection();
+		$qb->getQueryBuilder()->select('*')->from('ado')->where($this->qb->expr()->eq('asdf', $_GET['asdf']));
+	}
+
+	public function testSet() {
+		$this->qb->update('file_locks')->set('lock', $this->qb->createNamedParameter('lukaslukaslukas'));
+		$this->qb->update('file_locks')->set('lock', '1234');
+		$asdf = '1234';
+		$this->qb->update('file_locks')->set('lock', $asdf);
+		$this->qb->update('file_locks')->set('lock', $_GET['asdf']);
+	}
+
+	public function testSetValue() {
+		$this->qb->update('file_locks')->setValue('lock', $this->qb->createNamedParameter('lukaslukaslukas'));
+		$this->qb->update('file_locks')->setValue('lock', '1234');
+		$asdf = '1234';
+		$this->qb->update('file_locks')->setValue('lock', $asdf);
+		$this->qb->update('file_locks')->setValue('lock', $_GET['asdf']);
+	}
+}
\ No newline at end of file