From fc757d494089b7e1e4e37b7eaaa798cd7e9ad391 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 29 Jun 2023 16:06:39 +0100
Subject: [PATCH] userdb: Add proper error reporting when getting groups from a
 uid

Previously, if dbus_connection_get_unix_user() succeeded but
_dbus_unix_groups_from_uid() failed, then bus_connection_get_unix_groups()
would incorrectly fail without setting the error indicator, resulting
in "(null)" being logged, which is rather unhelpful.

This also lets us distinguish between ENOMEM and other errors, such as
the uid not existing in the system's user database.

Fixes: 145fb99b (untitled refactoring commit, 2006-12-12)
Helps: https://gitlab.freedesktop.org/dbus/dbus/-/issues/343
Signed-off-by: Simon McVittie <smcv@collabora.com>

Conflict:Adapt Context
Reference:https://gitlab.freedesktop.org/dbus/dbus/-/commit/fc757d494089b7e1e4e37b7eaaa798cd7e9ad391
---
 bus/connection.c                |  2 +-
 bus/policy.c                    |  2 +-
 dbus/dbus-sysdeps-util-unix.c   |  6 ++++--
 dbus/dbus-sysdeps-util-win.c    | 15 ++++++++++++---
 dbus/dbus-sysdeps.h             |  3 ++-
 dbus/dbus-userdb-util.c         | 15 ++++++++++-----
 dbus/dbus-userdb.h              |  3 ++-
 test/internals/misc-internals.c |  4 ++--
 8 files changed, 34 insertions(+), 16 deletions(-)

diff --git a/bus/connection.c b/bus/connection.c
index 557aaf6..b912d89 100644
--- a/bus/connection.c
+++ b/bus/connection.c
@@ -1079,7 +1079,7 @@ bus_connection_get_unix_groups  (DBusConnection   *connection,
 
   if (dbus_connection_get_unix_user (connection, &uid))
     {
-      if (!_dbus_unix_groups_from_uid (uid, groups, n_groups))
+      if (!_dbus_unix_groups_from_uid (uid, groups, n_groups, error))
         {
           _dbus_verbose ("Did not get any groups for UID %lu\n",
                          uid);
diff --git a/bus/policy.c b/bus/policy.c
index 74cb41b..b6890c7 100644
--- a/bus/policy.c
+++ b/bus/policy.c
@@ -450,7 +450,7 @@ bus_policy_allow_unix_user (BusPolicy        *policy,
   int n_group_ids;
 
   /* On OOM or error we always reject the user */
-  if (!_dbus_unix_groups_from_uid (uid, &group_ids, &n_group_ids))
+  if (!_dbus_unix_groups_from_uid (uid, &group_ids, &n_group_ids, NULL))
     {
       _dbus_verbose ("Did not get any groups for UID %lu\n",
                      uid);
diff --git a/dbus/dbus-sysdeps-util-unix.c b/dbus/dbus-sysdeps-util-unix.c
index 9fe7d55..eb5654e 100644
--- a/dbus/dbus-sysdeps-util-unix.c
+++ b/dbus/dbus-sysdeps-util-unix.c
@@ -992,14 +992,16 @@ _dbus_parse_unix_group_from_config (const DBusString  *groupname,
  * @param uid the UID
  * @param group_ids return location for array of group IDs
  * @param n_group_ids return location for length of returned array
+ * @param error error location
  * @returns #TRUE if the UID existed and we got some credentials
  */
 dbus_bool_t
 _dbus_unix_groups_from_uid (dbus_uid_t            uid,
                             dbus_gid_t          **group_ids,
-                            int                  *n_group_ids)
+                            int                  *n_group_ids,
+                            DBusError            *error)
 {
-  return _dbus_groups_from_uid (uid, group_ids, n_group_ids);
+  return _dbus_groups_from_uid (uid, group_ids, n_group_ids, error);
 }
 
 /**
diff --git a/dbus/dbus-sysdeps-util-win.c b/dbus/dbus-sysdeps-util-win.c
index c572fcd..5e4634f 100644
--- a/dbus/dbus-sysdeps-util-win.c
+++ b/dbus/dbus-sysdeps-util-win.c
@@ -649,6 +649,13 @@ dbus_bool_t _dbus_windows_user_is_process_owner (const char *windows_sid)
   unix emulation functions - should be removed sometime in the future
  =====================================================================*/
 
+static void
+set_unix_uid_unsupported (DBusError *error)
+{
+  dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED,
+                  "UNIX user IDs not supported on Windows");
+}
+
 /**
  * Checks to see if the UNIX user ID is at the console.
  * Should always fail on Windows (set the error to
@@ -662,8 +669,7 @@ dbus_bool_t
 _dbus_unix_user_is_at_console (dbus_uid_t         uid,
                                DBusError         *error)
 {
-  dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED,
-                  "UNIX user IDs not supported on Windows\n");
+  set_unix_uid_unsupported (error);
   return FALSE;
 }
 
@@ -707,13 +713,16 @@ _dbus_parse_unix_user_from_config (const DBusString  *username,
  * @param uid the UID
  * @param group_ids return location for array of group IDs
  * @param n_group_ids return location for length of returned array
+ * @param error error location
  * @returns #TRUE if the UID existed and we got some credentials
  */
 dbus_bool_t
 _dbus_unix_groups_from_uid (dbus_uid_t            uid,
                             dbus_gid_t          **group_ids,
-                            int                  *n_group_ids)
+                            int                  *n_group_ids,
+                            DBusError            *error)
 {
+  set_unix_uid_unsupported (error);
   return FALSE;
 }
 
diff --git a/dbus/dbus-sysdeps.h b/dbus/dbus-sysdeps.h
index e7e36ad..3363733 100644
--- a/dbus/dbus-sysdeps.h
+++ b/dbus/dbus-sysdeps.h
@@ -298,7 +298,8 @@ dbus_bool_t _dbus_parse_unix_group_from_config  (const DBusString  *groupname,
                                                  dbus_gid_t        *gid_p);
 dbus_bool_t _dbus_unix_groups_from_uid          (dbus_uid_t         uid,
                                                  dbus_gid_t       **group_ids,
-                                                 int               *n_group_ids);
+                                                 int               *n_group_ids,
+                                                 DBusError         *error);
 dbus_bool_t _dbus_unix_user_is_at_console       (dbus_uid_t         uid,
                                                  DBusError         *error);
 dbus_bool_t _dbus_unix_user_is_process_owner    (dbus_uid_t         uid);
diff --git a/dbus/dbus-userdb-util.c b/dbus/dbus-userdb-util.c
index 1ca21eb..0093ee4 100644
--- a/dbus/dbus-userdb-util.c
+++ b/dbus/dbus-userdb-util.c
@@ -373,31 +373,35 @@ _dbus_user_database_lookup_group (DBusUserDatabase *db,
  * @param uid the UID
  * @param group_ids return location for array of group IDs
  * @param n_group_ids return location for length of returned array
+ * @param error error to fill in on failure
  * @returns #TRUE if the UID existed and we got some credentials
  */
 dbus_bool_t
 _dbus_groups_from_uid (dbus_uid_t         uid,
                        dbus_gid_t       **group_ids,
-                       int               *n_group_ids)
+                       int               *n_group_ids,
+                       DBusError         *error)
 {
   DBusUserDatabase *db;
   const DBusUserInfo *info;
   *group_ids = NULL;
   *n_group_ids = 0;
 
-  /* FIXME: this can't distinguish ENOMEM from other errors */
   if (!_dbus_user_database_lock_system ())
-    return FALSE;
+    {
+      _DBUS_SET_OOM (error);
+      return FALSE;
+    }
 
   db = _dbus_user_database_get_system ();
   if (db == NULL)
     {
+      _DBUS_SET_OOM (error);
       _dbus_user_database_unlock_system ();
       return FALSE;
     }
 
-  if (!_dbus_user_database_get_uid (db, uid,
-                                    &info, NULL))
+  if (!_dbus_user_database_get_uid (db, uid, &info, error))
     {
       _dbus_user_database_unlock_system ();
       return FALSE;
@@ -410,6 +414,7 @@ _dbus_groups_from_uid (dbus_uid_t         uid,
       *group_ids = dbus_new (dbus_gid_t, info->n_group_ids);
       if (*group_ids == NULL)
         {
+          _DBUS_SET_OOM (error);
 	  _dbus_user_database_unlock_system ();
           return FALSE;
         }
diff --git a/dbus/dbus-userdb.h b/dbus/dbus-userdb.h
index fcb515c..9026caa 100644
--- a/dbus/dbus-userdb.h
+++ b/dbus/dbus-userdb.h
@@ -100,7 +100,8 @@ dbus_bool_t _dbus_get_user_id_and_primary_group (const DBusString  *username,
                                                  dbus_gid_t        *gid_p);
 dbus_bool_t _dbus_groups_from_uid		(dbus_uid_t            uid,
                                                  dbus_gid_t          **group_ids,
-                                                 int                  *n_group_ids);
+                                                 int                  *n_group_ids,
+                                                 DBusError            *error);
 DBUS_PRIVATE_EXPORT
 dbus_bool_t _dbus_is_console_user               (dbus_uid_t         uid,
                                                  DBusError         *error);
diff --git a/test/internals/misc-internals.c b/test/internals/misc-internals.c
index a1777bb..e0fac35 100644
--- a/test/internals/misc-internals.c
+++ b/test/internals/misc-internals.c
@@ -935,7 +935,7 @@ _dbus_userdb_test (const char *test_data_dir)
   dbus_uid_t uid;
   unsigned long *group_ids;
   int n_group_ids, i;
-  DBusError error;
+  DBusError error = DBUS_ERROR_INIT;
 
   if (!_dbus_username_from_current_process (&username))
     _dbus_test_fatal ("didn't get username");
@@ -946,7 +946,7 @@ _dbus_userdb_test (const char *test_data_dir)
   if (!_dbus_get_user_id (username, &uid))
     _dbus_test_fatal ("didn't get uid");
 
-  if (!_dbus_groups_from_uid (uid, &group_ids, &n_group_ids))
+  if (!_dbus_groups_from_uid (uid, &group_ids, &n_group_ids, &error))
     _dbus_test_fatal ("didn't get groups");
 
   _dbus_test_diag ("    Current user: %s homedir: %s gids:",
-- 
2.33.0