Messages in this thread | | | Subject | Re: [PATCH v5 1/1] security: Add mechanism to safely (un)load LSMs after boot time | From | Tetsuo Handa <> | Date | Mon, 09 Apr 2018 14:25:01 +0900 |
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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.
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