Le mercredi 18 novembre 2020, 21:02:32 CET Kees Cook a écrit :
> On Wed, Nov 18, 2020 at 12:07:30PM +0100, laniel_francis@xxxxxxxxxxxxxxxxxxx
wrote:
> > From: Francis Laniel <laniel_francis@xxxxxxxxxxxxxxxxxxx>
> >
> > This new test ensures that fortified strscpy has the same behavior than
> > vanilla strscpy (e.g. returning -E2BIG when src content is truncated).
> > Finally, it generates a crash at runtime because there is a write overflow
> > in destination string.
> >
> > Signed-off-by: Francis Laniel <laniel_francis@xxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > ---
> >
> > drivers/misc/lkdtm/Makefile | 1 +
> > drivers/misc/lkdtm/core.c | 1 +
> > drivers/misc/lkdtm/fortify.c | 82 +++++++++++++++++++++++++
> > drivers/misc/lkdtm/lkdtm.h | 3 +
> > tools/testing/selftests/lkdtm/tests.txt | 1 +
> > 5 files changed, 88 insertions(+)
> > create mode 100644 drivers/misc/lkdtm/fortify.c
> >
> > diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
> > index c70b3822013f..d898f7b22045 100644
> > --- a/drivers/misc/lkdtm/Makefile
> > +++ b/drivers/misc/lkdtm/Makefile
> > @@ -10,6 +10,7 @@ lkdtm-$(CONFIG_LKDTM) += rodata_objcopy.o
> >
> > lkdtm-$(CONFIG_LKDTM) += usercopy.o
> > lkdtm-$(CONFIG_LKDTM) += stackleak.o
> > lkdtm-$(CONFIG_LKDTM) += cfi.o
> >
> > +lkdtm-$(CONFIG_LKDTM) += fortify.o
> >
> > KASAN_SANITIZE_stackleak.o := n
> > KCOV_INSTRUMENT_rodata.o := n
> >
> > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> > index b8c51a633fcc..3c0a67f072c0 100644
> > --- a/drivers/misc/lkdtm/core.c
> > +++ b/drivers/misc/lkdtm/core.c
> > @@ -175,6 +175,7 @@ static const struct crashtype crashtypes[] = {
> >
> > CRASHTYPE(USERCOPY_KERNEL),
> > CRASHTYPE(STACKLEAK_ERASING),
> > CRASHTYPE(CFI_FORWARD_PROTO),
> >
> > + CRASHTYPE(FORTIFIED_STRSCPY),
> >
> > #ifdef CONFIG_X86_32
> >
> > CRASHTYPE(DOUBLE_FAULT),
> >
> > #endif
> >
> > diff --git a/drivers/misc/lkdtm/fortify.c b/drivers/misc/lkdtm/fortify.c
> > new file mode 100644
> > index 000000000000..790d46591bf5
> > --- /dev/null
> > +++ b/drivers/misc/lkdtm/fortify.c
> > @@ -0,0 +1,82 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2020 Francis Laniel <laniel_francis@xxxxxxxxxxxxxxxxxxx>
> > + *
> > + * Add tests related to fortified functions in this file.
> > + */
> > +#include <linux/string.h>
> > +#include <linux/slab.h>
> > +#include "lkdtm.h"
>
> Ah, I just noticed one small nit here during build testing: lkdtm.h
> needs to be included first to get the correct pr_fmt to avoid a warning:
>
> In file included from drivers/misc/lkdtm/fortify.c:9:
> drivers/misc/lkdtm/lkdtm.h:5: warning: "pr_fmt" redefined
> 5 | #define pr_fmt(fmt) "lkdtm: " fmt
>
> -Kees
This my bad, I noticed this warning but though it was "normal" with LKDTM.
I should have asked about it!
I will send the v6 soon!
