module: extend 'rodata=off' boot cmdline parameter to module mappings
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 <takahiro.akashi@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Link: http://lkml.kernel.org/r/20161114061505.15238-1-takahiro.akashi@linaro.org
Signed-off-by: Jessica Yu <jeyu@redhat.com>
Signed-off-by: Alex Shi <alex.shi@linaro.org> [v4.9 backport]
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 @@
/* 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_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 @@
{
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 @@
{
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 @@
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);
}