Rusty, Jessica On Wed, Oct 26, 2016 at 10:43:32AM +1030, Rusty Russell wrote: > AKASHI Takahiro <[email protected]> writes: > > On Thu, Oct 20, 2016 at 01:48:15PM -0700, Kees Cook wrote: > >> On Wed, Oct 19, 2016 at 11:24 PM, AKASHI Takahiro > >> <[email protected]> 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 patch looks good (except the minor issues noted by Kees); please CC > the followup version to Jessica as new module maintainer.
I think that the new version (v2)[1] addresses Kees' comments already. [1] http://lkml.iu.edu//hypermail/linux/kernel/1610.2/04163.html Thanks, -Takahiro AKASHI > Thanks! > Rusty. > > >> > > >> > 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 <[email protected]> > >> > Signed-off-by: AKASHI Takahiro <[email protected]> > >> > Cc: Rusty Russell <[email protected]> > >> > --- > >> > 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; > >> > >> Is there a mismatch here between the extern ifdef and the bool ifdef? > >> I.e. shouldn't the ifdef here be || DEBUG_SET_MODULE_RONX too? > > > > Yes. > > > >> Also, can you mark this as __ro_after_init, since nothing changes it > >> after the kernel command line is parsed? > > > > Yes, yes. > > > > Thanks, > > -Takahiro AKASHI > > > >> Otherwise, this looks fine to me. > >> > >> -Kees > >> > >> > >> -- > >> Kees Cook > >> Nexus Security
