From patchwork Thu Feb 21 23:44:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Edgecombe, Rick P" X-Patchwork-Id: 10824893 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7C5681399 for ; Thu, 21 Feb 2019 23:51:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6E1B131D2C for ; Thu, 21 Feb 2019 23:51:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 61E3F31D30; Thu, 21 Feb 2019 23:51:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D335E31D2C for ; Thu, 21 Feb 2019 23:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727295AbfBUXvK (ORCPT ); Thu, 21 Feb 2019 18:51:10 -0500 Received: from mga14.intel.com ([192.55.52.115]:3167 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727275AbfBUXvJ (ORCPT ); Thu, 21 Feb 2019 18:51:09 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Feb 2019 15:51:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,397,1544515200"; d="scan'208";a="322394943" Received: from linksys13920.jf.intel.com (HELO rpedgeco-DESK5.jf.intel.com) ([10.54.75.11]) by fmsmga005.fm.intel.com with ESMTP; 21 Feb 2019 15:51:07 -0800 From: Rick Edgecombe To: Andy Lutomirski , Ingo Molnar Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, Thomas Gleixner , Borislav Petkov , Nadav Amit , Dave Hansen , Peter Zijlstra , linux_dti@icloud.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, akpm@linux-foundation.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, will.deacon@arm.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, deneen.t.dock@intel.com, Rick Edgecombe , Jessica Yu , Steven Rostedt Subject: [PATCH v3 16/20] modules: Use vmalloc special flag Date: Thu, 21 Feb 2019 15:44:47 -0800 Message-Id: <20190221234451.17632-17-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190221234451.17632-1-rick.p.edgecombe@intel.com> References: <20190221234451.17632-1-rick.p.edgecombe@intel.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Use new flag for handling freeing of special permissioned memory in vmalloc and remove places where memory was set RW before freeing which is no longer needed. Since freeing of VM_FLUSH_RESET_PERMS memory is not supported in an interrupt by vmalloc, the freeing of init sections is moved to a work queue. Instead of call_rcu it now uses synchronize_rcu() in the work queue. Lastly, there is now a WARN_ON in module_memfree since it should not be called in an interrupt with special memory as is required for VM_FLUSH_RESET_PERMS. Cc: Jessica Yu Cc: Steven Rostedt Signed-off-by: Rick Edgecombe --- kernel/module.c | 77 +++++++++++++++++++++++++------------------------ 1 file changed, 39 insertions(+), 38 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index ae1b77da6a20..3b97dfb47afb 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -98,6 +98,10 @@ DEFINE_MUTEX(module_mutex); EXPORT_SYMBOL_GPL(module_mutex); static LIST_HEAD(modules); +/* Work queue for freeing init sections in success case */ +static struct work_struct init_free_wq; +static struct llist_head init_free_list; + #ifdef CONFIG_MODULES_TREE_LOOKUP /* @@ -1949,6 +1953,8 @@ void module_enable_ro(const struct module *mod, bool after_init) if (!rodata_enabled) return; + set_vm_flush_reset_perms(mod->core_layout.base); + set_vm_flush_reset_perms(mod->init_layout.base); frob_text(&mod->core_layout, set_memory_ro); frob_text(&mod->core_layout, set_memory_x); @@ -1972,15 +1978,6 @@ static void module_enable_nx(const struct module *mod) frob_writable_data(&mod->init_layout, set_memory_nx); } -static void module_disable_nx(const struct module *mod) -{ - frob_rodata(&mod->core_layout, set_memory_x); - frob_ro_after_init(&mod->core_layout, set_memory_x); - frob_writable_data(&mod->core_layout, set_memory_x); - frob_rodata(&mod->init_layout, set_memory_x); - frob_writable_data(&mod->init_layout, set_memory_x); -} - /* Iterate through all modules and set each module's text as RW */ void set_all_modules_text_rw(void) { @@ -2024,23 +2021,8 @@ void set_all_modules_text_ro(void) } mutex_unlock(&module_mutex); } - -static void disable_ro_nx(const struct module_layout *layout) -{ - if (rodata_enabled) { - frob_text(layout, set_memory_rw); - frob_rodata(layout, set_memory_rw); - frob_ro_after_init(layout, set_memory_rw); - } - frob_rodata(layout, set_memory_x); - frob_ro_after_init(layout, set_memory_x); - frob_writable_data(layout, set_memory_x); -} - #else -static void disable_ro_nx(const struct module_layout *layout) { } static void module_enable_nx(const struct module *mod) { } -static void module_disable_nx(const struct module *mod) { } #endif #ifdef CONFIG_LIVEPATCH @@ -2120,6 +2102,11 @@ static void free_module_elf(struct module *mod) void __weak module_memfree(void *module_region) { + /* + * This memory may be RO, and freeing RO memory in an interrupt is not + * supported by vmalloc. + */ + WARN_ON(in_interrupt()); vfree(module_region); } @@ -2171,7 +2158,6 @@ static void free_module(struct module *mod) mutex_unlock(&module_mutex); /* This may be empty, but that's OK */ - disable_ro_nx(&mod->init_layout); module_arch_freeing_init(mod); module_memfree(mod->init_layout.base); kfree(mod->args); @@ -2181,7 +2167,6 @@ static void free_module(struct module *mod) lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size); /* Finally, free the core (containing the module structure) */ - disable_ro_nx(&mod->core_layout); module_memfree(mod->core_layout.base); } @@ -3424,17 +3409,34 @@ static void do_mod_ctors(struct module *mod) /* For freeing module_init on success, in case kallsyms traversing */ struct mod_initfree { - struct rcu_head rcu; + struct llist_node node; void *module_init; }; -static void do_free_init(struct rcu_head *head) +static void do_free_init(struct work_struct *w) { - struct mod_initfree *m = container_of(head, struct mod_initfree, rcu); - module_memfree(m->module_init); - kfree(m); + struct llist_node *pos, *n, *list; + struct mod_initfree *initfree; + + list = llist_del_all(&init_free_list); + + synchronize_rcu(); + + llist_for_each_safe(pos, n, list) { + initfree = container_of(pos, struct mod_initfree, node); + module_memfree(initfree->module_init); + kfree(initfree); + } } +static int __init modules_wq_init(void) +{ + INIT_WORK(&init_free_wq, do_free_init); + init_llist_head(&init_free_list); + return 0; +} +module_init(modules_wq_init); + /* * This is where the real work happens. * @@ -3511,7 +3513,6 @@ static noinline int do_init_module(struct module *mod) #endif module_enable_ro(mod, true); mod_tree_remove_init(mod); - disable_ro_nx(&mod->init_layout); module_arch_freeing_init(mod); mod->init_layout.base = NULL; mod->init_layout.size = 0; @@ -3522,14 +3523,18 @@ static noinline int do_init_module(struct module *mod) * We want to free module_init, but be aware that kallsyms may be * walking this with preempt disabled. In all the failure paths, we * call synchronize_rcu(), but we don't want to slow down the success - * path, so use actual RCU here. + * path. module_memfree() cannot be called in an interrupt, so do the + * work and call synchronize_rcu() in a work queue. + * * Note that module_alloc() on most architectures creates W+X page * mappings which won't be cleaned up until do_free_init() runs. Any * code such as mark_rodata_ro() which depends on those mappings to * be cleaned up needs to sync with the queued work - ie * rcu_barrier() */ - call_rcu(&freeinit->rcu, do_free_init); + if (llist_add(&freeinit->node, &init_free_list)) + schedule_work(&init_free_wq); + mutex_unlock(&module_mutex); wake_up_all(&module_wq); @@ -3826,10 +3831,6 @@ static int load_module(struct load_info *info, const char __user *uargs, module_bug_cleanup(mod); mutex_unlock(&module_mutex); - /* we can't deallocate the module until we clear memory protection */ - module_disable_ro(mod); - module_disable_nx(mod); - ddebug_cleanup: ftrace_release_mod(mod); dynamic_debug_remove(mod, info->debug);