From 39290b389ea2654f9190e3b48c57d27b24def83e Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Mon, 14 Nov 2016 15:15:05 +0900 Subject: [PATCH] module: extend 'rodata=off' boot cmdline parameter to module mappings 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: and Acked-by: Mark Rutland Signed-off-by: AKASHI Takahiro Reviewed-by: Kees Cook Acked-by: Rusty Russell Link: http://lkml.kernel.org/r/20161114061505.15238-1-takahiro.akashi@linaro.org Signed-off-by: Jessica Yu --- include/linux/init.h | 3 +++ init/main.c | 7 +++++-- kernel/module.c | 20 +++++++++++++++++--- 3 files changed, 25 insertions(+), 5 deletions(-) diff --git a/include/linux/init.h b/include/linux/init.h index e30104c..885c3e6 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -126,6 +126,9 @@ void prepare_namespace(void); void __init load_default_modules(void); int __init init_rootfs(void); +#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) +extern bool rodata_enabled; +#endif #ifdef CONFIG_DEBUG_RODATA void mark_rodata_ro(void); #endif diff --git a/init/main.c b/init/main.c index 2858be7..959a242 100644 --- a/init/main.c +++ b/init/main.c @@ -81,6 +81,7 @@ #include #include #include +#include #include #include @@ -914,14 +915,16 @@ 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; +#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_SET_MODULE_RONX) +bool rodata_enabled __ro_after_init = true; static int __init set_debug_rodata(char *str) { return strtobool(str, &rodata_enabled); } __setup("rodata=", set_debug_rodata); +#endif +#ifdef CONFIG_DEBUG_RODATA static void mark_readonly(void) { if (rodata_enabled) diff --git a/kernel/module.c b/kernel/module.c index 6281c70..039ce82 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1902,6 +1902,9 @@ 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); @@ -1911,6 +1914,9 @@ 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); @@ -1943,6 +1949,9 @@ 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) @@ -1959,6 +1968,9 @@ 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) { /* @@ -1978,10 +1990,12 @@ 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_ro_after_init(layout, set_memory_rw); + } frob_rodata(layout, set_memory_x); - frob_ro_after_init(layout, set_memory_rw); frob_ro_after_init(layout, set_memory_x); frob_writable_data(layout, set_memory_x); } -- 2.7.4