Ensure that login profile data is ephemeral


Review URL: http://codereview.chromium.org/1021006
(cherry picked from commit 18a9cb941767efa67995a4f0cef0cac97d46887b)
diff --git a/session_manager_setup.sh b/session_manager_setup.sh
index dd1af3a..5e1ca83 100644
--- a/session_manager_setup.sh
+++ b/session_manager_setup.sh
@@ -21,6 +21,7 @@
 export USER=chronos
 export DATA_DIR=/home/${USER}
 export LOGNAME=${USER}
 export SHELL=/bin/bash
 export HOME=${DATA_DIR}/user
@@ -36,6 +37,16 @@
 ${XAUTH} -q -f ${XAUTH_FILE} add :0 . ${MCOOKIE} && \
   chown ${USER}:${USER} ${XAUTH_FILE}
+# Disallow the login profile from having persistent data until
+# http://code.google.com/p/chromium-os/issues/detail?id=1967 is resolved.
+if mount | grep -q "${LOGIN_PROFILE_DIR} "; then
+  umount -f ${LOGIN_PROFILE_DIR}
+mkdir -p ${LOGIN_PROFILE_DIR}
+mount -n -t tmpfs -onodev,noexec,nosuid loginprofile ${LOGIN_PROFILE_DIR}
 # temporary hack to tell cryptohome that we're doing chrome-login
 touch /tmp/doing-chrome-login