Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754174AbcJTGSR (ORCPT ); Thu, 20 Oct 2016 02:18:17 -0400 Received: from mail-pf0-f174.google.com ([209.85.192.174]:33816 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475AbcJTGSP (ORCPT ); Thu, 20 Oct 2016 02:18:15 -0400 From: AKASHI Takahiro To: rusty@rustcorp.com.au Cc: kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, AKASHI Takahiro Subject: [PATCH] module: extend 'rodata=off' boot cmdline parameter to module mappings Date: Thu, 20 Oct 2016 15:24:58 +0900 Message-Id: <20161020062458.14014-1-takahiro.akashi@linaro.org> X-Mailer: git-send-email 2.10.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3785 Lines: 116 The current "rodata=off" parameter disables read-only kernel mappings under CONFIG_DEBUG_RODATA: commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings") This patch is a logical extension to module mappings ie. read-only mappings at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX (mainly for debug use). Please note, however, that it only affects RO/RW permissions, keeping NX set. This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory (always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64. Suggested-by: Mark Rutland Signed-off-by: AKASHI Takahiro Cc: Rusty Russell --- v1: * remove RFC's "module_ronx=" and merge it with "rodata=" * always keep NX set if CONFIG_SET_MODULE_RONX include/linux/init.h | 3 ++- init/main.c | 2 +- kernel/module.c | 21 ++++++++++++++++++--- 3 files changed, 21 insertions(+), 5 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index e30104c..20aa2eb 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -126,7 +126,8 @@ void prepare_namespace(void); void __init load_default_modules(void); int __init init_rootfs(void); -#ifdef CONFIG_DEBUG_RODATA +#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) +extern bool rodata_enabled; void mark_rodata_ro(void); #endif diff --git a/init/main.c b/init/main.c index 2858be7..92db2f3 100644 --- a/init/main.c +++ b/init/main.c @@ -915,7 +915,7 @@ static int try_to_run_init_process(const char *init_filename) static noinline void __init kernel_init_freeable(void); #ifdef CONFIG_DEBUG_RODATA -static bool rodata_enabled = true; +bool rodata_enabled = true; static int __init set_debug_rodata(char *str) { return strtobool(str, &rodata_enabled); diff --git a/kernel/module.c b/kernel/module.c index f57dd63..34d1880 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1910,6 +1910,9 @@ static void frob_writable_data(const struct module_layout *layout, /* livepatching wants to disable read-only so it can frob module. */ void module_disable_ro(const struct module *mod) { + if (!rodata_enabled) + return; + frob_text(&mod->core_layout, set_memory_rw); frob_rodata(&mod->core_layout, set_memory_rw); frob_ro_after_init(&mod->core_layout, set_memory_rw); @@ -1919,6 +1922,9 @@ void module_disable_ro(const struct module *mod) void module_enable_ro(const struct module *mod, bool after_init) { + if (!rodata_enabled) + return; + frob_text(&mod->core_layout, set_memory_ro); frob_rodata(&mod->core_layout, set_memory_ro); frob_text(&mod->init_layout, set_memory_ro); @@ -1951,6 +1957,9 @@ void set_all_modules_text_rw(void) { struct module *mod; + if (!rodata_enabled) + return; + mutex_lock(&module_mutex); list_for_each_entry_rcu(mod, &modules, list) { if (mod->state == MODULE_STATE_UNFORMED) @@ -1967,6 +1976,9 @@ void set_all_modules_text_ro(void) { struct module *mod; + if (!rodata_enabled) + return; + mutex_lock(&module_mutex); list_for_each_entry_rcu(mod, &modules, list) { if (mod->state == MODULE_STATE_UNFORMED) @@ -1980,10 +1992,13 @@ void set_all_modules_text_ro(void) static void disable_ro_nx(const struct module_layout *layout) { - frob_text(layout, set_memory_rw); - frob_rodata(layout, set_memory_rw); + if (rodata_enabled) { + frob_text(layout, set_memory_rw); + frob_rodata(layout, set_memory_rw); + } frob_rodata(layout, set_memory_x); - frob_ro_after_init(layout, set_memory_rw); + if (rodata_enabled) + frob_ro_after_init(layout, set_memory_rw); frob_ro_after_init(layout, set_memory_x); frob_writable_data(layout, set_memory_x); } -- 2.10.0