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 8/8] lkdtm/powerpc: Fix code patching hijack test
Date: Thu, 5 Aug 2021 11:18:04 +0200 [thread overview]
Message-ID: <7a6c97ed-815b-49fc-5568-ab4420f53122@csgroup.eu> (raw)
In-Reply-To: <20210713053113.4632-9-cmr@linux.ibm.com>
Le 13/07/2021 à 07:31, Christopher M. Riedl a écrit :
> Code patching on powerpc with a STRICT_KERNEL_RWX uses a userspace
> address in a temporary mm on Radix now. Use __put_user() to avoid write
> failures due to KUAP when attempting a "hijack" on the patching address.
> __put_user() also works with the non-userspace, vmalloc-based patching
> address on non-Radix MMUs.
It is not really clean to use __put_user() on non user address, allthought it works by change.
I think it would be better to do something like
if (is_kernel_addr(addr))
copy_to_kernel_nofault(...);
else
copy_to_user_nofault(...);
>
> Signed-off-by: Christopher M. Riedl <cmr@linux.ibm.com>
> ---
> drivers/misc/lkdtm/perms.c | 9 ---------
> 1 file changed, 9 deletions(-)
>
> diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
> index 41e87e5f9cc86..da6a34a0a49fb 100644
> --- a/drivers/misc/lkdtm/perms.c
> +++ b/drivers/misc/lkdtm/perms.c
> @@ -262,16 +262,7 @@ 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)
>
next prev parent reply other threads:[~2021-08-05 9:18 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
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 [this message]
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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