On 6/23/25 16:28, Peter Zijlstra wrote: > On Mon, Jun 23, 2025 at 04:21:15PM +0200, Vlastimil Babka wrote: >> On 6/23/25 16:01, Christoph Hellwig wrote: >> > On Mon, Jun 23, 2025 at 07:00:39AM -0700, Christoph Hellwig wrote: >> >> On Mon, Jun 23, 2025 at 12:16:27PM +0200, Christian Brauner wrote: >> >> > I'm more than happy to switch a bunch of our exports so that we only >> >> > allow them for specific modules. But for that we also need >> >> > EXPOR_SYMBOL_FOR_MODULES() so we can switch our non-gpl versions. >> >> >> >> Huh? Any export for a specific in-tree module (or set thereof) is >> >> by definition internals and an _GPL export if perfectly fine and >> >> expected. >> >> Peterz tells me EXPORT_SYMBOL_GPL_FOR_MODULES() is not limited to in-tree >> modules, so external module with GPL and matching name can import. >> >> But if we're targetting in-tree stuff like kvm, we don't need to provide a >> non-GPL variant I think? > > So the purpose was to limit specific symbols to known in-tree module > users (hence GPL only). > > Eg. KVM; x86 exports a fair amount of low level stuff just because KVM. > Nobody else should be touching those symbols. > > If you have a pile of symbols for !GPL / out-of-tree consumers, it > doesn't really make sense to limit the export to a named set of modules, > does it? > > So yes, nothing limits things to in-tree modules per-se. The > infrastructure only really cares about module names (and implicitly > trusts the OS to not overwrite existing kernel modules etc.). So you > could add an out-of-tree module name to the list (or have an out-of-free > module have a name that matches a glob; "kvm-vmware" would match "kvm-*" > for example). > > But that is very much beyond the intention of things. So AFAIK we have a way to recognize out of tree modules when loading, as there's a taint just for that. Then the same mechanism could perhaps just refuse loading them if they use any _FOR_MODULES() export, regardless of name? Then the _GPL_ part would become implicit and redundant and we could drop it as Christoph suggested?
