On Sun, Apr 8, 2018 at 10:25 PM, Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> wrote: > Sargun Dhillon wrote: >> > Remove SECURITY_HOOK_COUNT and "struct security_hook_list"->owner and >> > the exception in randomize_layout_plugin.c because preventing module >> > unloading won't work as expected. >> > >> >> Rather than completely removing the unloading code, might it make >> sense to add a BUG_ON or WARN_ON, in security_delete_hooks if >> allow_unload_module is false, and owner is not NULL? > > Do we need to check ->owner != NULL? Although it will be true that > SELinux's ->owner == NULL and LKM-based LSM module's ->owner != NULL, > I think we unregister SELinux before setting allow_unload_module to false. > Thus, rejecting delete_security_hooks() if allow_unload_module == false will > be sufficient. SELinux might want to call panic() if delete_security_hooks() > did not unregister due to allow_unload_module == false. Also, > allow_unload_module would be renamed to allow_unregister_module. > > By the way, please don't use BUG_ON() or WARN_ON() because syzbot would hit > and call panic() because syzbot runs tests with panic_on_warn == true.
I think my primary question is for the SELinux folks -- what do you think the behaviour should be? If allow_unload_modules / allow_unregister_module is set, do you want to be able to call security_delete_hooks? What do you think the right action should be if it fails?