From: Michael Ellerman <mpe@ellerman.id.au>
To: Christophe Leroy <christophe.leroy@csgroup.eu>,
Jordan Niethe <jniethe5@gmail.com>
Cc: ajd@linux.ibm.com,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Nicholas Piggin <npiggin@gmail.com>,
cmr@codefail.de, naveen.n.rao@linux.ibm.com,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH v14 3/9] powerpc/modules: Make module_alloc() Strict Module RWX aware
Date: Tue, 18 May 2021 11:43:18 +1000 [thread overview]
Message-ID: <87fsykkea1.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <27d15f13-c6bd-86d7-c4fc-2c4c495f54b3@csgroup.eu>
Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 17/05/2021 à 13:01, Michael Ellerman a écrit :
>> Jordan Niethe <jniethe5@gmail.com> writes:
>>> On Mon, May 17, 2021 at 4:37 PM Christophe Leroy
>>> <christophe.leroy@csgroup.eu> wrote:
>>>> Le 17/05/2021 à 05:28, Jordan Niethe a écrit :
>>>>> Make module_alloc() use PAGE_KERNEL protections instead of
>>>>> PAGE_KERNEL_EXEX if Strict Module RWX is enabled.
>>>>>
>>>>> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
>>>>> ---
>>>>> v14: - Split out from powerpc: Set ARCH_HAS_STRICT_MODULE_RWX
>>>>> - Add and use strict_module_rwx_enabled() helper
>>>>> ---
>>>>> arch/powerpc/include/asm/mmu.h | 5 +++++
>>>>> arch/powerpc/kernel/module.c | 4 +++-
>>>>> 2 files changed, 8 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
>>>>> index 607168b1aef4..7710bf0cbf8a 100644
>>>>> --- a/arch/powerpc/include/asm/mmu.h
>>>>> +++ b/arch/powerpc/include/asm/mmu.h
>>>>> @@ -357,6 +357,11 @@ static inline bool strict_kernel_rwx_enabled(void)
>>>>> return false;
>>>>> }
>>>>> #endif
>>>>> +
>>>>> +static inline bool strict_module_rwx_enabled(void)
>>>>> +{
>>>>> + return IS_ENABLED(CONFIG_STRICT_MODULE_RWX) && strict_kernel_rwx_enabled();
>>>>> +}
>>>>
>>>> Looking at arch/Kconfig, I have the feeling that it is possible to select CONFIG_STRICT_MODULE_RWX
>>>> without selecting CONFIG_STRICT_KERNEL_RWX.
>>>>
>>>> In that case, strict_kernel_rwx_enabled() will return false.
>>
>>> Ok, if someone did that currently it would break things, e.g. code
>>> patching. I think it should it be made impossible to
>>> CONFIG_STRICT_MODULE_RWX without CONFIG_STRICT_KERNEL_RWX?
>>
>> Yeah I don't see any reason to support that combination.
>>
>> We should be moving to a world where both are on by default, or in fact
>> are always enabled.
>
> Would it work if we add the following in arch/powerpc/Kconfig ? :
>
> select STRICT_KERNEL_RWX if STRICT_MODULE_RWX
>
> There should be no dependency issue as powerpc only selects ARCH_HAS_STRICT_MODULE_RWX when
> ARCH_HAS_STRICT_KERNEL_RWX is also selected.
I think it will work. It's slightly rude to select things like that, but
I think it's OK for something like this.
Medium term we can possibly just have the generic STRICT_MODULE_RWX
depend on STRICT_KERNEL_RWX.
cheers
next prev parent reply other threads:[~2021-05-18 1:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 3:28 [PATCH v14 0/9] powerpc: Further Strict RWX support Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 1/9] powerpc/mm: Implement set_memory() routines Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 2/9] powerpc/lib/code-patching: Set up Strict RWX patching earlier Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 3/9] powerpc/modules: Make module_alloc() Strict Module RWX aware Jordan Niethe
2021-05-17 6:36 ` Christophe Leroy
2021-05-17 6:48 ` Jordan Niethe
2021-05-17 11:01 ` Michael Ellerman
2021-05-17 11:05 ` Christophe Leroy
2021-05-18 1:43 ` Michael Ellerman [this message]
2021-05-17 3:28 ` [PATCH v14 4/9] powerpc/kprobes: Mark newly allocated probes as ROX Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 5/9] powerpc/bpf: Remove bpf_jit_free() Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 6/9] powerpc/bpf: Write protect JIT code Jordan Niethe
2021-05-17 6:39 ` Christophe Leroy
2021-05-20 4:02 ` Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 7/9] powerpc: Set ARCH_HAS_STRICT_MODULE_RWX Jordan Niethe
2021-05-17 6:48 ` Christophe Leroy
2021-05-20 3:50 ` Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 8/9] powerpc/mm: implement set_memory_attr() Jordan Niethe
2021-05-17 3:28 ` [PATCH v14 9/9] powerpc/32: use set_memory_attr() Jordan Niethe
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