| Message ID | 20161021011333.11411-1-takahiro.akashi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
[Adding Jessica] On Fri, Oct 21, 2016 at 10:13:33AM +0900, AKASHI Takahiro wrote: > 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 <mark.rutland@arm.com> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > Reviewed-by: Kees Cook <keescook@chromium.org> > Cc: Rusty Russell <rusty@rustcorp.com.au> FWIW: Acked-by: Mark Rutland <mark.rutland@arm.com> Thanks, Mark. > --- > v2: > * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate > * make "rodata_enabled" variable as __ro_after_init > 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 | 7 +++++-- > kernel/module.c | 21 ++++++++++++++++++--- > 3 files changed, 26 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 <linux/integrity.h> > #include <linux/proc_ns.h> > #include <linux/io.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 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 >
+++ AKASHI Takahiro [21/10/16 10:13 +0900]: >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 <mark.rutland@arm.com> >Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >Reviewed-by: Kees Cook <keescook@chromium.org> >Cc: Rusty Russell <rusty@rustcorp.com.au> >--- >v2: > * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate > * make "rodata_enabled" variable as __ro_after_init >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 | 7 +++++-- > kernel/module.c | 21 ++++++++++++++++++--- > 3 files changed, 26 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 <linux/integrity.h> > #include <linux/proc_ns.h> > #include <linux/io.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 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); Why not merge this hunk with the previous if (rodata_enabled) check? I think it's more readable that way. In any case, the rest of the patch looks good to me. Jessica
On Sat, Nov 12, 2016 at 07:04:22PM -0800, Jessica Yu wrote: > +++ AKASHI Takahiro [21/10/16 10:13 +0900]: > >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 <mark.rutland@arm.com> > >Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > >Reviewed-by: Kees Cook <keescook@chromium.org> > >Cc: Rusty Russell <rusty@rustcorp.com.au> > >--- > >v2: > > * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate > > * make "rodata_enabled" variable as __ro_after_init > >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 | 7 +++++-- > >kernel/module.c | 21 ++++++++++++++++++--- > >3 files changed, 26 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 <linux/integrity.h> > >#include <linux/proc_ns.h> > >#include <linux/io.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 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); > > Why not merge this hunk with the previous if (rodata_enabled) check? > I think it's more readable that way. In any case, the rest of the > patch looks good to me. Sure. See my v3. Thanks, -Takahiro AKASHI > Jessica
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 <linux/integrity.h> #include <linux/proc_ns.h> #include <linux/io.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 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); }
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 <mark.rutland@arm.com> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Rusty Russell <rusty@rustcorp.com.au> --- v2: * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate * make "rodata_enabled" variable as __ro_after_init 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 | 7 +++++-- kernel/module.c | 21 ++++++++++++++++++--- 3 files changed, 26 insertions(+), 5 deletions(-)