Add a query/policy layer on top of SSH keys for Almanac

Summary:
Ref T5833. Currently, SSH keys are associated only with users, and are a bit un-modern. I want to let Almanac Devices have SSH keys so devices in a cluster can identify to one another.

For example, with hosted installs, initialization will go something like this:

  - A request comes in for `company.phacility.com`.
  - A SiteSource (from D10787) makes a Conduit call to Almanac on the master install to check if `company` is a valid install and pull config if it is.
  - This call can be signed with an SSH key which identifies a trusted Almanac Device.

In the cluster case, a web host can make an authenticated call to a repository host with similar key signing.

To move toward this, put a proper Query class on top of SSH key access (this diff). In following diffs, I'll:

  - Rename `userPHID` to `objectPHID`.
  - Move this to the `auth` database.
  - Provide UI for device/key association.

An alternative approach would be to build some kind of special token layer in Conduit, but I think that would be a lot harder to manage in the hosting case. This gives us a more direct attack on trusting requests from machines and recognizing machines as first (well, sort of second-class) actors without needing things like fake user accounts.

Test Plan:
  - Added and removed SSH keys.
  - Added and removed SSH keys from a bot account.
  - Tried to edit an unonwned SSH key (denied).
  - Ran `bin/ssh-auth`, got sensible output.
  - Ran `bin/ssh-auth-key`, got sensible output.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5833

Differential Revision: https://secure.phabricator.com/D10790

scripts/ssh/ssh-auth-key.php

@@ -4,48 +4,28 @@
 $root = dirname(dirname(dirname(__FILE__)));
 require_once $root.'/scripts/__init_script__.php';
 
-$cert = file_get_contents('php://stdin');
-
-if (!$cert) {
+try {
+  $cert = file_get_contents('php://stdin');
+  $public_key = PhabricatorAuthSSHPublicKey::newFromRawKey($cert);
+} catch (Exception $ex) {
   exit(1);
 }
 
-$parts = preg_split('/\s+/', $cert);
-if (count($parts) < 2) {
+$key = id(new PhabricatorAuthSSHKeyQuery())
+  ->setViewer(PhabricatorUser::getOmnipotentUser())
+  ->withKeys(array($public_key))
+  ->executeOne();
+if (!$key) {
   exit(1);
 }
 
-list($type, $body) = $parts;
-
-$user_dao = new PhabricatorUser();
-$ssh_dao = new PhabricatorUserSSHKey();
-$conn_r = $user_dao->establishConnection('r');
-
-$row = queryfx_one(
-  $conn_r,
-  'SELECT userName FROM %T u JOIN %T ssh ON u.phid = ssh.userPHID
-    WHERE ssh.keyType = %s AND ssh.keyBody = %s',
-  $user_dao->getTableName(),
-  $ssh_dao->getTableName(),
-  $type,
-  $body);
-
-if (!$row) {
-  exit(1);
-}
-
-$user = idx($row, 'userName');
-
-if (!$user) {
-  exit(1);
-}
-
-if (!PhabricatorUser::validateUsername($user)) {
+$object = $key->getObject();
+if (!($object instanceof PhabricatorUser)) {
   exit(1);
 }
 
 $bin = $root.'/bin/ssh-exec';
-$cmd = csprintf('%s --phabricator-ssh-user %s', $bin, $user);
+$cmd = csprintf('%s --phabricator-ssh-user %s', $bin, $object->getUsername());
 // This is additional escaping for the SSH 'command="..."' string.
 $cmd = addcslashes($cmd, '"\\');
 

scripts/ssh/ssh-auth.php

@@ -4,25 +4,27 @@
 $root = dirname(dirname(dirname(__FILE__)));
 require_once $root.'/scripts/__init_script__.php';
 
-$user_dao = new PhabricatorUser();
-$ssh_dao = new PhabricatorUserSSHKey();
-$conn_r = $user_dao->establishConnection('r');
+$keys = id(new PhabricatorAuthSSHKeyQuery())
+  ->setViewer(PhabricatorUser::getOmnipotentUser())
+  ->execute();
 
-$rows = queryfx_all(
-  $conn_r,
-  'SELECT userName, keyBody, keyType FROM %T u JOIN %T ssh
-    ON u.phid = ssh.userPHID',
-  $user_dao->getTableName(),
-  $ssh_dao->getTableName());
+foreach ($keys as $key => $ssh_key) {
+  // For now, filter out any keys which don't belong to users. Eventually we
+  // may allow devices to use this channel.
+  if (!($ssh_key->getObject() instanceof PhabricatorUser)) {
+    unset($keys[$key]);
+    continue;
+  }
+}
 
-if (!$rows) {
+if (!$keys) {
   echo pht('No keys found.')."\n";
   exit(1);
 }
 
 $bin = $root.'/bin/ssh-exec';
-foreach ($rows as $row) {
-  $user = $row['userName'];
+foreach ($keys as $ssh_key) {
+  $user = $ssh_key->getObject()->getUsername();
 
   $cmd = csprintf('%s --phabricator-ssh-user %s', $bin, $user);
   // This is additional escaping for the SSH 'command="..."' string.
@@ -30,13 +32,12 @@ foreach ($rows as $row) {
 
   // Strip out newlines and other nonsense from the key type and key body.
 
-  $type = $row['keyType'];
+  $type = $ssh_key->getKeyType();
   $type = preg_replace('@[\x00-\x20]+@', '', $type);
 
-  $key = $row['keyBody'];
+  $key = $ssh_key->getKeyBody();
   $key = preg_replace('@[\x00-\x20]+@', '', $key);
 
-
   $options = array(
     'command="'.$cmd.'"',
     'no-port-forwarding',

src/__phutil_library_map__.php

@@ -1317,6 +1317,8 @@ phutil_register_library_map(array(
     'PhabricatorAuthProviderConfigTransactionQuery' => 'applications/auth/query/PhabricatorAuthProviderConfigTransactionQuery.php',
     'PhabricatorAuthRegisterController' => 'applications/auth/controller/PhabricatorAuthRegisterController.php',
     'PhabricatorAuthRevokeTokenController' => 'applications/auth/controller/PhabricatorAuthRevokeTokenController.php',
+    'PhabricatorAuthSSHKeyQuery' => 'applications/auth/query/PhabricatorAuthSSHKeyQuery.php',
+    'PhabricatorAuthSSHPublicKey' => 'applications/auth/storage/PhabricatorAuthSSHPublicKey.php',
     'PhabricatorAuthSession' => 'applications/auth/storage/PhabricatorAuthSession.php',
     'PhabricatorAuthSessionEngine' => 'applications/auth/engine/PhabricatorAuthSessionEngine.php',
     'PhabricatorAuthSessionGarbageCollector' => 'applications/auth/garbagecollector/PhabricatorAuthSessionGarbageCollector.php',
@@ -4381,6 +4383,8 @@ phutil_register_library_map(array(
     'PhabricatorAuthProviderConfigTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
     'PhabricatorAuthRegisterController' => 'PhabricatorAuthController',
     'PhabricatorAuthRevokeTokenController' => 'PhabricatorAuthController',
+    'PhabricatorAuthSSHKeyQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorAuthSSHPublicKey' => 'Phobject',
     'PhabricatorAuthSession' => array(
       'PhabricatorAuthDAO',
       'PhabricatorPolicyInterface',
@@ -5627,7 +5631,10 @@ phutil_register_library_map(array(
     'PhabricatorUserProfileEditor' => 'PhabricatorApplicationTransactionEditor',
     'PhabricatorUserRealNameField' => 'PhabricatorUserCustomField',
     'PhabricatorUserRolesField' => 'PhabricatorUserCustomField',
-    'PhabricatorUserSSHKey' => 'PhabricatorUserDAO',
+    'PhabricatorUserSSHKey' => array(
+      'PhabricatorUserDAO',
+      'PhabricatorPolicyInterface',
+    ),
     'PhabricatorUserSchemaSpec' => 'PhabricatorConfigSchemaSpec',
     'PhabricatorUserSearchIndexer' => 'PhabricatorSearchDocumentIndexer',
     'PhabricatorUserSinceField' => 'PhabricatorUserCustomField',

src/applications/auth/query/PhabricatorAuthSSHKeyQuery.php

@@ -0,0 +1,104 @@
+<?php
+
+final class PhabricatorAuthSSHKeyQuery
+  extends PhabricatorCursorPagedPolicyAwareQuery {
+
+  private $ids;
+  private $objectPHIDs;
+  private $keys;
+
+  public function withIDs(array $ids) {
+    $this->ids = $ids;
+    return $this;
+  }
+
+  public function withObjectPHIDs(array $object_phids) {
+    $this->objectPHIDs = $object_phids;
+    return $this;
+  }
+
+  public function withKeys(array $keys) {
+    assert_instances_of($keys, 'PhabricatorAuthSSHPublicKey');
+    $this->keys = $keys;
+    return $this;
+  }
+
+  protected function loadPage() {
+    $table = new PhabricatorUserSSHKey();
+    $conn_r = $table->establishConnection('r');
+
+    $data = queryfx_all(
+      $conn_r,
+      'SELECT * FROM %T %Q %Q %Q',
+      $table->getTableName(),
+      $this->buildWhereClause($conn_r),
+      $this->buildOrderClause($conn_r),
+      $this->buildLimitClause($conn_r));
+
+    return $table->loadAllFromArray($data);
+  }
+
+  protected function willFilterPage(array $keys) {
+    $object_phids = mpull($keys, 'getObjectPHID');
+
+    $objects = id(new PhabricatorObjectQuery())
+      ->setViewer($this->getViewer())
+      ->setParentQuery($this)
+      ->withPHIDs($object_phids)
+      ->execute();
+    $objects = mpull($objects, null, 'getPHID');
+
+    foreach ($keys as $key => $ssh_key) {
+      $object = idx($objects, $ssh_key->getObjectPHID());
+      if (!$object) {
+        unset($keys[$key]);
+        continue;
+      }
+      $ssh_key->attachObject($object);
+    }
+
+    return $keys;
+  }
+
+  protected function buildWhereClause(AphrontDatabaseConnection $conn_r) {
+    $where = array();
+
+    if ($this->ids !== null) {
+      $where[] = qsprintf(
+        $conn_r,
+        'id IN (%Ld)',
+        $this->ids);
+    }
+
+    if ($this->objectPHIDs !== null) {
+      $where[] = qsprintf(
+        $conn_r,
+        'userPHID IN (%Ls)',
+        $this->objectPHIDs);
+    }
+
+    if ($this->keys !== null) {
+      // TODO: This could take advantage of a better key, and the hashing
+      // scheme for this table is a bit nonstandard and questionable.
+
+      $sql = array();
+      foreach ($this->keys as $key) {
+        $sql[] = qsprintf(
+          $conn_r,
+          '(keyType = %s AND keyBody = %s)',
+          $key->getType(),
+          $key->getBody());
+      }
+      $where[] = implode(' OR ', $sql);
+    }
+
+    $where[] = $this->buildPagingClause($conn_r);
+
+    return $this->formatWhereClause($where);
+  }
+
+  public function getQueryApplicationClass() {
+    return 'PhabricatorAuthApplication';
+  }
+
+}

src/applications/auth/storage/PhabricatorAuthSSHPublicKey.php

@@ -0,0 +1,86 @@
+<?php
+
+/**
+ * Data structure representing a raw public key.
+ */
+final class PhabricatorAuthSSHPublicKey extends Phobject {
+
+  private $type;
+  private $body;
+  private $comment;
+
+  private function __construct() {
+    // <internal>
+  }
+
+  public static function newFromRawKey($entire_key) {
+    $entire_key = trim($entire_key);
+    if (!strlen($entire_key)) {
+      throw new Exception(pht('No public key was provided.'));
+    }
+
+    $parts = str_replace("\n", '', $entire_key);
+
+    // The third field (the comment) can have spaces in it, so split this
+    // into a maximum of three parts.
+    $parts = preg_split('/\s+/', $parts, 3);
+
+    if (preg_match('/private\s*key/i', $entire_key)) {
+      // Try to give the user a better error message if it looks like
+      // they uploaded a private key.
+      throw new Exception(pht('Provide a public key, not a private key!'));
+    }
+
+    switch (count($parts)) {
+      case 1:
+        throw new Exception(
+          pht('Provided public key is not properly formatted.'));
+      case 2:
+        // Add an empty comment part.
+        $parts[] = '';
+        break;
+      case 3:
+        // This is the expected case.
+        break;
+    }
+
+    list($type, $body, $comment) = $parts;
+
+    $recognized_keys = array(
+      'ssh-dsa',
+      'ssh-dss',
+      'ssh-rsa',
+      'ecdsa-sha2-nistp256',
+      'ecdsa-sha2-nistp384',
+      'ecdsa-sha2-nistp521',
+    );
+
+    if (!in_array($type, $recognized_keys)) {
+      $type_list = implode(', ', $recognized_keys);
+      throw new Exception(
+        pht(
+          'Public key type should be one of: %s',
+          $type_list));
+    }
+
+    $public_key = new PhabricatorAuthSSHPublicKey();
+    $public_key->type = $type;
+    $public_key->body = $body;
+    $public_key->comment = $comment;
+
+    return $public_key;
+  }
+
+  public function getType() {
+    return $this->type;
+  }
+
+  public function getBody() {
+    return $this->body;
+  }
+
+  public function getComment() {
+    return $this->comment;
+  }
+
+}

src/applications/settings/panel/PhabricatorSettingsPanelSSHKeys.php

@@ -45,12 +45,16 @@ final class PhabricatorSettingsPanelSSHKeys
 
     $id = nonempty($edit, $delete);
 
-    if ($id && is_numeric($id)) {
-      // NOTE: This prevents editing/deleting of keys not owned by the user.
-      $key = id(new PhabricatorUserSSHKey())->loadOneWhere(
-        'userPHID = %s AND id = %d',
-        $user->getPHID(),
-        (int)$id);
+    if ($id) {
+      $key = id(new PhabricatorAuthSSHKeyQuery())
+        ->setViewer($viewer)
+        ->withIDs(array($id))
+        ->requireCapabilities(
+          array(
+            PhabricatorPolicyCapability::CAN_VIEW,
+            PhabricatorPolicyCapability::CAN_EDIT,
+          ))
+        ->executeOne();
       if (!$key) {
         return new Aphront404Response();
       }
@@ -77,7 +81,11 @@ final class PhabricatorSettingsPanelSSHKeys
       } else {
 
         try {
-          list($type, $body, $comment) = self::parsePublicKey($entire_key);
+          $public_key = PhabricatorAuthSSHPublicKey::newFromRawKey($entire_key);
+
+          $type = $public_key->getType();
+          $body = $public_key->getBody();
+          $comment = $public_key->getComment();
 
           $key->setKeyType($type);
           $key->setKeyBody($body);
@@ -153,9 +161,10 @@ final class PhabricatorSettingsPanelSSHKeys
     $user = $this->getUser();
     $viewer = $request->getUser();
 
-    $keys = id(new PhabricatorUserSSHKey())->loadAllWhere(
-      'userPHID = %s',
-      $user->getPHID());
+    $keys = id(new PhabricatorAuthSSHKeyQuery())
+      ->setViewer($viewer)
+      ->withObjectPHIDs(array($user->getPHID()))
+      ->execute();
 
     $rows = array();
     foreach ($keys as $key) {
@@ -294,7 +303,10 @@ final class PhabricatorSettingsPanelSSHKeys
           'viewPolicy' => $viewer->getPHID(),
         ));
 
-      list($type, $body, $comment) = self::parsePublicKey($public_key);
+      $public_key = PhabricatorAuthSSHPublicKey::newFromRawKey($public_key);
+
+      $type = $public_key->getType();
+      $body = $public_key->getBody();
 
       $key = id(new PhabricatorUserSSHKey())
         ->setUserPHID($user->getPHID())
@@ -377,53 +389,4 @@ final class PhabricatorSettingsPanelSSHKeys
       ->setDialog($dialog);
   }
 
-  private static function parsePublicKey($entire_key) {
-    $parts = str_replace("\n", '', trim($entire_key));
-
-    // The third field (the comment) can have spaces in it, so split this
-    // into a maximum of three parts.
-    $parts = preg_split('/\s+/', $parts, 3);
-
-    if (preg_match('/private\s*key/i', $entire_key)) {
-      // Try to give the user a better error message if it looks like
-      // they uploaded a private key.
-      throw new Exception(
-        pht('Provide your public key, not your private key!'));
-    }
-
-    switch (count($parts)) {
-      case 1:
-        throw new Exception(
-          pht('Provided public key is not properly formatted.'));
-      case 2:
-        // Add an empty comment part.
-        $parts[] = '';
-        break;
-      case 3:
-        // This is the expected case.
-        break;
-    }
-
-    list($type, $body, $comment) = $parts;
-
-    $recognized_keys = array(
-      'ssh-dsa',
-      'ssh-dss',
-      'ssh-rsa',
-      'ecdsa-sha2-nistp256',
-      'ecdsa-sha2-nistp384',
-      'ecdsa-sha2-nistp521',
-    );
-
-    if (!in_array($type, $recognized_keys)) {
-      $type_list = implode(', ', $recognized_keys);
-      throw new Exception(
-        pht(
-          'Public key type should be one of: %s',
-          $type_list));
-    }
-
-    return array($type, $body, $comment);
-  }
-
 }

src/applications/settings/storage/PhabricatorUserSSHKey.php

@@ -1,6 +1,8 @@
 <?php
 
-final class PhabricatorUserSSHKey extends PhabricatorUserDAO {
+final class PhabricatorUserSSHKey
+  extends PhabricatorUserDAO
+  implements PhabricatorPolicyInterface {
 
   protected $userPHID;
   protected $name;
@@ -9,6 +11,12 @@ final class PhabricatorUserSSHKey extends PhabricatorUserDAO {
   protected $keyHash;
   protected $keyComment;
 
+  private $object = self::ATTACHABLE;
+
+  public function getObjectPHID() {
+    return $this->getUserPHID();
+  }
+
   public function getConfiguration() {
     return array(
       self::CONFIG_COLUMN_SCHEMA => array(
@@ -42,4 +50,37 @@ final class PhabricatorUserSSHKey extends PhabricatorUserDAO {
     return trim(implode(' ', $parts));
   }
 
+  public function getObject() {
+    return $this->assertAttached($this->object);
+  }
+
+  public function attachObject($object) {
+    $this->object = $object;
+    return $this;
+  }
+
+
+/* -(  PhabricatorPolicyInterface  )----------------------------------------- */
+
+
+  public function getCapabilities() {
+    return array(
+      PhabricatorPolicyCapability::CAN_VIEW,
+      PhabricatorPolicyCapability::CAN_EDIT,
+    );
+  }
+
+  public function getPolicy($capability) {
+    return $this->getObject()->getPolicy($capability);
+  }
+
+  public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
+    return $this->getObject()->hasAutomaticCapability($capability, $viewer);
+  }
+
+  public function describeAutomaticCapability($capability) {
+    return pht(
+      'SSH keys inherit the policies of the user or object they authenticate.');
+  }
+
 }