On Fri, 2017-11-10 at 20:35 +0100, Luis R. Rodriguez wrote: > On Fri, Nov 10, 2017 at 12:58:23PM -0500, Mimi Zohar wrote: > > Hi David, > > > > If you are interested in preventing the loading of unsigned firmware, > > the patch below is straight forward. The patch has ONLY been tested > > with IMA-appraisal enabled, and works as intended - allowing only > > signed firmware to be loaded. > > Very nice! This is the sort of thing that I mean by LSM'ifying fw access > through a system policy. > > We currently handle the LSM aspect for firmware through > kernel_read_file_from_path() and so the kernel_read_file LSM hook, so why a new > hook here? kernel_read_file(), itself, is not an LSM hook, but calls two LSM hooks named security_kernel_read_file(), prior to reading a file, and security_kernel_post_read_file(), post reading a file. In this case, we want to reject even reading the file if it isn't signed, so we're using the security_kernel_read_file() LSM hook. > > Where does this plug in? This is a standalone, micro LSM that can be configured at build. For now I left it is an optional Kconfig parameter, but at some point, you might want to consider making it required. Mimi
