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Message-ID: <a458667c-fb8d-a01f-130b-0fef733dd001@csgroup.eu>
Date: Wed, 3 Jun 2020 09:14:49 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: "Christopher M. Riedl" <cmr@...ormatik.wtf>,
linuxppc-dev@...ts.ozlabs.org, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 4/5] powerpc/lib: Add LKDTM accessor for patching addr
Le 03/06/2020 à 07:19, Christopher M. Riedl a écrit :
> When live patching a STRICT_RWX kernel, a mapping is installed at a
> "patching address" with temporary write permissions. Provide a
> LKDTM-only accessor function for this address in preparation for a LKDTM
> test which attempts to "hijack" this mapping by writing to it from
> another CPU.
>
> Signed-off-by: Christopher M. Riedl <cmr@...ormatik.wtf>
> ---
> arch/powerpc/lib/code-patching.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index df0765845204..c23453049116 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -52,6 +52,13 @@ int raw_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
> static struct mm_struct *patching_mm __ro_after_init;
> static unsigned long patching_addr __ro_after_init;
>
> +#ifdef CONFIG_LKDTM
> +unsigned long read_cpu_patching_addr(unsigned int cpu)
If this fonction is not static, it means it is intended to be used from
some other C file, so it should be declared in a .h too.
Christophe
> +{
> + return patching_addr;
> +}
> +#endif
> +
> void __init poking_init(void)
> {
> spinlock_t *ptl; /* for protecting pte table */
>
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