Christoph Hellwig, a well-known Linux kernel developer who at one time was part of the technical management committee of the Linux Foundation and acted as a plaintiff in a lawsuit related to GPL with VMware, tighten the protection against linking proprietary drivers with Linux kernel components that are exported only for modules under the GPL license. To bypass the restriction on exporting GPL symbols, manufacturers of proprietary drivers use a bridging module, the code for which is open and distributed under the GPLv2 license, but its functions are limited to translating the proprietary driver's access to the necessary kernel APIs that are prohibited for use from proprietary code directly.
To block such maneuvers, Christoph Hellwig for the Linux kernel proposed patches that ensure the inheritance of flags related to exporting GPL symbols. The proposal boils down to inheriting the TAINT_PROPRIETARY_MODULE flag in all modules importing symbols from modules with this flag. Thus, if the GPL bridging module tries to import symbols from a non-GPL module, the GPL module will inherit the TAINT_PROPRIETARY_MODULE tag and will not be able to access the kernel components available only for modules under the GPL license, even if the module previously imported symbols from the ‘gplonly’ category.
During the discussion, there was also a proposal for reverse blocking — if a module imports symbols EXPORT_SYMBOL_GPL, any symbols exported by that module should not be imported by modules that explicitly do not declare GPL compatibility. That is, if a module imports symbols EXPORT_SYMBOL_GPL, then all its exported symbols should be treated as EXPORT_SYMBOL_GPL. Christoph Hellwig , fully agrees with this proposal, but such a change will not be approved by Linus Torvalds, as it will render a large part of the kernel subsystems inaccessible to proprietary drivers because the fundamental symbols exported under the GPL are involved in driver development.
The change was proposed in response to an engineer from Facebook's series of patches implementing a new netgpu subsystem, allowing direct memory access (DMA
zero-copy) between the network card and GPU, while handling protocol processing with the CPU. of the developers was caused megvalósítások kizárólag a NVIDIA szabadalmazott meghajtói számára a megadott meghajtók GPL-felülete által. Válaszként a patch-készítő , hogy az alrendszer nem köthető a NVIDIA-hoz, és annak támogatása biztosítható többek között az AMD és Intel GPU-khoz készült szoftveres interfészek számára is. Ennek eredményeként a netgpu kernelbe való integrálását lehetetlennek nyilvánították, amíg működő támogatás nem állt rendelkezésre szabad meghajtók alapján, mint például az AMDGPU, Intel i915 vagy Nouveau.
Forrás: opennet.ru
