$FilesAndFolders = gci "c:\data" -recurse | % {$_.FullName}
foreach($FileAndFolder in $FilesAndFolders)
{
    #using get-item instead because some of the folders have '[' or ']' character and Powershell throws exception trying to do a get-acl or set-acl on them.
    $item = gi -literalpath $FileAndFolder 
    $acl = $item.GetAccessControl() 
    $permission = "Everyone","FullControl","Allow"
    $rule = New-Object System.Security.AccessControl.FileSystemAccessRule $permission
    $acl.SetAccessRule($rule)
    $item.SetAccessControl($acl)
}