On Mon, Aug 07, 2023 at 07:08:52PM +0200, Pali Rohár wrote: > On Monday 07 August 2023 07:45:08 Kees Cook wrote: > > On August 6, 2023 9:23:46 AM PDT, "Pali Rohár" <pali@xxxxxxxxxx> wrote: > > >Hello, I would like to remind this email about binfmt_misc for PE. > > > > > >On Thursday 06 July 2023 13:55:50 Pali Rohár wrote: > > >> Hello, > > >> > > >> I would like to ask how to properly register binfmt_misc for different > > >> PE binaries, so kernel could execute the correct loader for them. > > >> > > >> I mean, how to register support for Win32 (console/gui) PE binaries and > > >> also for CLR PE binaries (dotnet). Win32 needs to be executed under wine > > >> and CLR ideally under dotnet core (or mono). > > >> > > >> I have read kernel documentation files admin-guide/binfmt-misc.rst > > >> and admin-guide/mono.rst. But seems that they are in conflicts as both > > >> wants to registers its own handler for the same magic: > > >> > > >> echo ':DOSWin:M::MZ::/usr/local/bin/wine:' > register > > >> > > >> echo ':CLR:M::MZ::/usr/bin/mono:' > /proc/sys/fs/binfmt_misc/register > > >> > > >> Not mentioning the fact that they register DOS MZ handler, which matches > > >> not only all PE binaries (including EFI, libraries, other processors), > > >> but also all kind of other NE/LE/LX binaries and different DOS extenders. > > >> > > >> From documentation it looks like that even registering PE binaries is > > >> impossible by binfmt_misc as PE is detected by checking that indirect > > >> reference from 0x3C is PE\0\0. And distinguish between Win32 and CLR > > >> needs to parse PE COM descriptor directory. > > >> > > >> Or it is possible to write binfmt_misc pattern match based on indirect > > >> offset? > > > > Normally a single userspace program will be registered and it can do whatever it needs to do to further distinguish the binary and hand it off to the appropriate loader. > > Ok, so you are saying that there should be one userspace program which > distinguish between DOS, CLR and Win32 and then exec the correct > "runtime" loader? Is there such one? Also it would be nice to mention it > in the documentation. I've not spent much time with it, but I think Wine can be set up to do this? Anyway, I'm happy to apply Documentation patches, if you want to send changes that would make things more clear. :) -Kees -- Kees Cook
