On Wed, Oct 16, 2019 at 08:51:27AM +0200, Miroslav Benes wrote: > On Tue, 15 Oct 2019, Joe Lawrence wrote: > > > On 10/15/19 10:13 AM, Miroslav Benes wrote: > > > Yes, it does. klp_module_coming() calls module_disable_ro() on all > > > patching modules which patch the coming module in order to call > > > apply_relocate_add(). New (patching) code for a module can be relocated > > > only when the relevant module is loaded. > > > > FWIW, would the LPC blue-sky2 model (ie, Steve's suggestion @ plumber's where > > livepatches only patch a single object and updates are kept on disk to handle > > coming module updates as they are loaded) eliminate those outstanding > > relocations and the need to perform this late permission flipping? > > Yes, it should, but we don't have to wait for it. PeterZ proposed a > different solution to this specific issue in > https://lore.kernel.org/lkml/20191015141111.GP2359@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > It should not be a problem to create a live patch module like that and the > code in kernel/livepatch/ is almost ready. Something like > module_section_disable_ro(mod, section) (and similar for X protection) > should be enough. Module reloads would still require juggling with the > protections, but I think it is all feasible. Just had a browse around the module code, and while the section info is in load_info, it doesn't get retained for active modules. So I suppose I'll go add that for KLP enabled things.
