From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: "Christopher M. Riedl" <cmr@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Cc: keescook@chromium.org, peterz@infradead.org, x86@kernel.org,
npiggin@gmail.com, linux-hardening@vger.kernel.org,
tglx@linutronix.de, dja@axtens.net
Subject: Re: [PATCH v5 4/8] lkdtm/x86_64: Add test to hijack a patch mapping
Date: Thu, 5 Aug 2021 11:09:06 +0200 [thread overview]
Message-ID: <95de5ec5-8d48-c969-3c9f-966561f9f58e@csgroup.eu> (raw)
In-Reply-To: <20210713053113.4632-5-cmr@linux.ibm.com>
Le 13/07/2021 à 07:31, Christopher M. Riedl a écrit :
> A previous commit implemented an LKDTM test on powerpc to exploit the
> temporary mapping established when patching code with STRICT_KERNEL_RWX
> enabled. Extend the test to work on x86_64 as well.
>
> Signed-off-by: Christopher M. Riedl <cmr@linux.ibm.com>
> ---
> drivers/misc/lkdtm/perms.c | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
> index 39e7456852229..41e87e5f9cc86 100644
> --- a/drivers/misc/lkdtm/perms.c
> +++ b/drivers/misc/lkdtm/perms.c
> @@ -224,7 +224,7 @@ void lkdtm_ACCESS_NULL(void)
> }
>
> #if (IS_BUILTIN(CONFIG_LKDTM) && defined(CONFIG_STRICT_KERNEL_RWX) && \
> - defined(CONFIG_PPC))
> + (defined(CONFIG_PPC) || defined(CONFIG_X86_64)))
> /*
> * This is just a dummy location to patch-over.
> */
> @@ -233,12 +233,25 @@ static void patching_target(void)
> return;
> }
>
> -#include <asm/code-patching.h>
> const u32 *patch_site = (const u32 *)&patching_target;
>
> +#ifdef CONFIG_PPC
> +#include <asm/code-patching.h>
> +#endif
> +
> +#ifdef CONFIG_X86_64
> +#include <asm/text-patching.h>
> +#endif
> +
> static inline int lkdtm_do_patch(u32 data)
> {
> +#ifdef CONFIG_PPC
> return patch_instruction((u32 *)patch_site, ppc_inst(data));
> +#endif
> +#ifdef CONFIG_X86_64
> + text_poke((void *)patch_site, &data, sizeof(u32));
> + return 0;
> +#endif
> }
>
> static inline u32 lkdtm_read_patch_site(void)
> @@ -249,11 +262,16 @@ static inline u32 lkdtm_read_patch_site(void)
> /* Returns True if the write succeeds */
> static inline bool lkdtm_try_write(u32 data, u32 *addr)
> {
> +#ifdef CONFIG_PPC
> __put_kernel_nofault(addr, &data, u32, err);
> return true;
>
> err:
> return false;
> +#endif
> +#ifdef CONFIG_X86_64
> + return !__put_user(data, addr);
> +#endif
> }
>
> static int lkdtm_patching_cpu(void *data)
> @@ -346,8 +364,8 @@ void lkdtm_HIJACK_PATCH(void)
>
> void lkdtm_HIJACK_PATCH(void)
> {
> - if (!IS_ENABLED(CONFIG_PPC))
> - pr_err("XFAIL: this test only runs on powerpc\n");
> + if (!IS_ENABLED(CONFIG_PPC) && !IS_ENABLED(CONFIG_X86_64))
> + pr_err("XFAIL: this test only runs on powerpc and x86_64\n");
> if (!IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
> pr_err("XFAIL: this test requires CONFIG_STRICT_KERNEL_RWX\n");
> if (!IS_BUILTIN(CONFIG_LKDTM))
>
Instead of spreading arch specific stuff into LKDTM, wouldn't it make sence to define common a
common API ? Because the day another arch like arm64 implements it own approach, do we add specific
functions again and again into LKDTM ?
Also, I find it odd to define tests only when they can succeed. For other tests like
ACCESS_USERSPACE, they are there all the time, regardless of whether we have selected
CONFIG_PPC_KUAP or not. I think it should be the same here, have it all there time, if
CONFIG_STRICT_KERNEL_RWX is selected the test succeeds otherwise it fails, but it is always there.
Christophe
next prev parent reply other threads:[~2021-08-05 9:09 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 5:31 [PATCH v5 0/8] Use per-CPU temporary mappings for patching on Radix MMU Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 1/8] powerpc: Add LKDTM accessor for patching addr Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 2/8] lkdtm/powerpc: Add test to hijack a patch mapping Christopher M. Riedl
2021-08-05 9:13 ` Christophe Leroy
2021-08-11 17:57 ` Christopher M. Riedl
2021-08-11 18:07 ` Kees Cook
2021-07-13 5:31 ` [PATCH v5 3/8] x86_64: Add LKDTM accessor for patching addr Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 4/8] lkdtm/x86_64: Add test to hijack a patch mapping Christopher M. Riedl
2021-08-05 9:09 ` Christophe Leroy [this message]
2021-08-11 17:53 ` Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 5/8] powerpc/64s: Introduce temporary mm for Radix MMU Christopher M. Riedl
2021-08-05 9:27 ` Christophe Leroy
2021-08-11 18:02 ` Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 6/8] powerpc: Rework and improve STRICT_KERNEL_RWX patching Christopher M. Riedl
2021-08-05 9:34 ` Christophe Leroy
2021-08-11 18:10 ` Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 7/8] powerpc/64s: Initialize and use a temporary mm for patching on Radix Christopher M. Riedl
2021-08-05 9:48 ` Christophe Leroy
2021-08-11 18:28 ` Christopher M. Riedl
2021-07-13 5:31 ` [PATCH v5 8/8] lkdtm/powerpc: Fix code patching hijack test Christopher M. Riedl
2021-08-05 9:18 ` Christophe Leroy
2021-08-11 17:57 ` Christopher M. Riedl
2021-08-05 9:03 ` [PATCH v5 0/8] Use per-CPU temporary mappings for patching on Radix MMU Christophe Leroy
2021-08-11 17:49 ` Christopher M. Riedl
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