[PATCH 08/29] module: extend 'rodata=off' boot cmdline parameter to module mappings
From: Alex Shi <hidden>
Date: 2018-02-28 03:58:35
Also in:
lkml, stable
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: AKASHI Takahiro <redacted>
commit 39290b389ea upstream.
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 <mark.rutland@arm.com>
Signed-off-by: AKASHI Takahiro <redacted>
Reviewed-by: Kees Cook <redacted>
Acked-by: Rusty Russell <redacted>
Link: http://lkml.kernel.org/r/20161114061505.15238-1-takahiro.akashi at linaro.org
Signed-off-by: Jessica Yu <redacted>
Signed-off-by: Alex Shi <redacted>
Conflicts:
keeping kaiser.h in init/main.c
---
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 8e346d1..4dfe300 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h@@ -133,6 +133,9 @@ 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 99f0265..f22957a 100644
--- a/init/main.c
+++ b/init/main.c@@ -81,6 +81,7 @@ #include <linux/proc_ns.h> #include <linux/io.h> #include <linux/kaiser.h> +#include <linux/cache.h> #include <asm/io.h> #include <asm/bugs.h>
@@ -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 07bfb99..0651f2d 100644
--- a/kernel/module.c
+++ b/kernel/module.c@@ -1911,6 +1911,9 @@ 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);
@@ -1920,6 +1923,9 @@ 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);
@@ -1952,6 +1958,9 @@ 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)
@@ -1968,6 +1977,9 @@ 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)
@@ -1981,10 +1993,12 @@ 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