From c122ebed451272090e594f3a511cc8a6017a62e2 Mon Sep 17 00:00:00 2001 From: Ray Strode Date: Thu, 24 Mar 2011 16:47:37 -0400 Subject: [PATCH] worker: CVE-2011-0727: change to user before copying user files This commit changes to a user before copying user files to prevent a possible symlink local root exploit attack. --- daemon/gdm-session-worker.c | 29 +++++++++++++++++------------ 1 files changed, 17 insertions(+), 12 deletions(-) diff -up gdm-2.30.2/daemon/gdm-session-worker.c.with-fix gdm-2.30.2/daemon/gdm-session-worker.c --- gdm-2.30.2/daemon/gdm-session-worker.c.with-fix 2011-03-28 13:56:04.488869029 -0400 +++ gdm-2.30.2/daemon/gdm-session-worker.c 2011-03-28 13:57:15.205843697 -0400 @@ -1034,10 +1034,6 @@ gdm_cache_copy_file (GdmSessionWorker *w error->message); g_error_free (error); } else { - chown (cachefilename, - worker->priv->uid, - worker->priv->gid); - g_chmod (cachefilename, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH); g_debug ("Copy successful"); } @@ -1171,7 +1167,23 @@ gdm_session_worker_uninitialize_pam (Gdm return; if (worker->priv->state >= GDM_SESSION_WORKER_STATE_SESSION_OPENED) { - gdm_session_worker_cache_userfiles (worker); + pid_t pid; + + pid = fork (); + + if (pid == 0) { + if (setuid (worker->priv->uid) < 0) { + g_debug ("GdmSessionWorker: could not reset uid: %s", g_strerror (errno)); + _exit (1); + } + + gdm_session_worker_cache_userfiles (worker); + _exit (0); + } + + if (pid > 0) { + gdm_wait_on_pid (pid); + } pam_close_session (worker->priv->pam_handle, 0); gdm_session_auditor_report_logout (worker->priv->auditor);