[kernel-hardening] [PATCH 1/2] powerpc: Don't fortify prom_init

[Michael Ellerman]

Daniel Axtens <dja at axtens.net> writes:
> prom_init is a bit special; in theory it should be able to be
> linked separately to the kernel. To keep this from getting too
> complex, the symbols that prom_init.c uses are checked.
>
> Fortification adds symbols, and it gets quite messy as it includes
> things like panic(). So just don't fortify prom_init.c for now.

Calling panic() at that point is unlikely to work well.

> Cc: Kees Cook <keescook at chromium.org>
> Cc: Daniel Micay <danielmicay at gmail.com>
> Signed-off-by: Daniel Axtens <dja at axtens.net>
>
> ---
>
> This will need to go in before the main fortify support, but it
> doesn't make any sense in the absence of fortify. I think it would
> make most sense for Kees to queue this up with the main fortify patch,
> with an Ack from mpe?

Yeah that's fine by me.

> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index dd8a04f3053a..613f79f03877 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -15,6 +15,9 @@
>  
>  #undef DEBUG_PROM
>  
> +/* we cannot use FORTIFY as it brings in new symbols */
> +#define __NO_FORTIFY
> +
>  #include <stdarg.h>
>  #include <linux/kernel.h>
>  #include <linux/string.h>

Acked-by: Michael Ellerman <mpe at ellerman.id.au>

cheers