Description of problem:

vlock currently only uses pam_authenticate() to authenticate the user.  Strictly
speaking, the pam_acct_mgmt() function should also be called to verify that the
user is allowed to unlock the screen (for example, if time-of-day restrictions
are being imposed).

When unlocking the screen, it would be nice if vlock called pam_setcred() to
give modules a chance to reinitialize the user's credentials, as xscreensaver does.

Version-Release number of selected component (if applicable):
1.3-19

How reproducible:
Always.

Steps to Reproduce:
1. Add "required pam_listfile.so sense=allow item=user file=/dev/null" to
/etc/pam.d/vlock.
2. Lock, then try to unlock your VT.
  
Actual results:
vlock unlocks the VT

Expected results:
vlock stubbornly refuses to let you back in