On Thu, Jul 28, 2022 at 02:52:06PM +0200, Hans de Goede wrote: > Hi, > > On 7/28/22 14:07, Greg KH wrote: > > On Thu, Jul 28, 2022 at 01:57:25PM +0200, Hans de Goede wrote: > >> Hi, > >> > >> On 7/10/22 18:59, Greg KH wrote: > >>> On Sun, Jul 10, 2022 at 09:00:11AM -0700, Jithu Joseph wrote: > >>>> Existing implementation limits IFS images to be loaded only from > >>>> a default file-name /lib/firmware/intel/ifs/ff-mm-ss.scan. > >>> > >>> That was by design, why is this suddenly not acceptable? > >>> > >>>> But there are situations where there may be multiple scan files > >>>> that can be run on a particular system stored in /lib/firmware/intel/ifs > >>> > >>> Again, this was by design. > >>> > >>>> E.g. > >>>> 1. Because test contents are larger than the memory reserved for IFS by BIOS > >>> > >>> What does the BIOS have to do with this? > >>> > >>>> 2. To provide increased test coverage > >>> > >>> Test coverage of what? > >>> > >>>> 3. Custom test files to debug certain specific issues in the field > >>> > >>> Why can't you rename the existing file? > >>> > >>>> Renaming each of these to ff-mm-ss.scan and then loading might be > >>>> possible in some environments. But on systems where /lib is read-only > >>>> this is not a practical solution. > >>> > >>> What system puts /lib/ as read-only that you want to have loading > >>> hardware firmware? That kind of defeats the security implications of > >>> having a read-only /lib/, right? > >>> > >>>> Modify the semantics of the driver file > >>>> /sys/devices/virtual/misc/intel_ifs_0/reload such that, > >>>> it interprets the input as the filename to be loaded. > >>> > >>> So you are now going to allow any file to be read from the system, in an > >>> unknown filesystem namespace, by this driver? > >> > >> @Intel folks to me this is the big blocker which needs to be solved before > >> we can move forward with figuring out how to allow loading multiple > >> different sets of test patterns through IFS. > >> > >> Which in turn is required to remove the broken marking... > >> > >> How about echoing a suffix to be appended to the default filename to > >> the reload attribute? This suffix would then need to be sanity checked > >> to only contain [a-z][0-9] (we don't want '/' but it seems better to > >> limit this further) to avoid directory traversal attacks. > >> > >> (and echoing an empty suffix can be used to force reloading the > >> default test-patterns after a linux-firmware pkg upgrade) > >> > >> This way we avoid the allowing user to load an arbitrary file issue. > >> > >> Greg, would using a suffix appended to the default filename be > >> acceptable to you as a solution to solving the load arbitrary > >> file issue? > > > > Not really, a suffix doesn't protect much at all. > > ? > > Currently the driver will always load: > > /lib/firmware/intel/ifs/%02x-%02x-%02x.scan > > with the "%02x" bits being fixed parts of the CPU model. > > My suggestion is to make it: > > /lib/firmware/intel/ifs/%02x-%02x-%02x%s.scan Ah, sorry, I skimmed that, you are right, that would be fine. But still odd to ever be needed in a real system. > > This really feels like a "test the product in the factory" type of > > option that someone seems to want to do without just renaming the > > firmware file. Why this is unique from all other firmware file loading > > in the kernel needs to really be explained here in order to even > > consider justifying this type of change. > > First of all I really wish some of the Intel folks would elaborate > more on why multiple test-pattern files are necessary. Ping > anyone@intel, you have all been very quiet in this thread which > is not helpful (not helpful at all really). > > Speculating myself as far as I understand IFS is not for factory > tests but for testing in the fields since big cloud vendors have > found that sometimes there are hard to catch CPU defects which > they only find out by running statistics which show that certain > tasks only crash when run on machine a, socket b, core c. Who knows, Intel doesn't say so we can't really guess :( greg k-h
