From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>,
robh@kernel.org, takahiro.akashi@linaro.org,
gregkh@linuxfoundation.org, will@kernel.org,
catalin.marinas@arm.com, mpe@ellerman.id.au, james.morse@arm.com,
sashal@kernel.org, benh@kernel.crashing.org, paulus@samba.org,
frowand.list@gmail.com, vincenzo.frascino@arm.com,
mark.rutland@arm.com, dmitry.kasatkin@gmail.com,
jmorris@namei.org, serge@hallyn.com, pasha.tatashin@soleen.com,
allison@lohutok.net, masahiroy@kernel.org, bhsharma@redhat.com,
mbrugger@suse.com, hsinyi@chromium.org, tao.li@vivo.com,
christophe.leroy@c-s.fr, prsriva@linux.microsoft.com,
balajib@linux.microsoft.com, linux-integrity@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v13 2/6] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c
Date: Tue, 22 Dec 2020 21:03:05 -0800 [thread overview]
Message-ID: <159c7e4d-0cad-158f-6f5b-9f3b60159b38@linux.microsoft.com> (raw)
In-Reply-To: <878s9pl5hb.fsf@manicouagan.localdomain>
On 12/22/20 4:40 PM, Thiago Jung Bauermann wrote:
>
> Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:
>
>> On 12/22/20 11:45 AM, Mimi Zohar wrote:
>>> On Tue, 2020-12-22 at 10:53 -0800, Lakshmi Ramasubramanian wrote:
>>>> On 12/22/20 6:26 AM, Mimi Zohar wrote:
>>>>
>>>> Hi Mimi,
>>>>
>>>>>
>>>>> On Sat, 2020-12-19 at 09:57 -0800, Lakshmi Ramasubramanian wrote:
>>>>>>
>>>>>> diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
>>>>>> index 4aff6846c772..b6c52608cb49 100644
>>>>>> --- a/arch/powerpc/kexec/Makefile
>>>>>> +++ b/arch/powerpc/kexec/Makefile
>>>>>> @@ -9,13 +9,6 @@ obj-$(CONFIG_PPC32) += relocate_32.o
>>>>>> obj-$(CONFIG_KEXEC_FILE) += file_load.o ranges.o
>>>>>> file_load_$(BITS).o elf_$(BITS).o
>>>>>> -ifdef CONFIG_HAVE_IMA_KEXEC
>>>>>> -ifdef CONFIG_IMA
>>>>>> -obj-y += ima.o
>>>>>> -endif
>>>>>> -endif
>>>>>
>>>>> Notice how "kexec/ima.o" is only included if the architecture supports
>>>>> it and IMA is configured. In addition only if CONFIG_IMA_KEXEC is
>>>>> configured, is the IMA measurement list carried across kexec. After
>>>>> moving the rest of ima.c to drivers/of/kexec.c, this changes. Notice
>>>>> how drivers/of/Kconfig includes kexec.o:
>>>>>
>>>>> obj-$(CONFIG_KEXEC_FILE) += kexec.o
>>>>>
>>>>> It is not dependent on CONFIG_HAVE_IMA_KEXEC. Shouldn't all of the
>>>>> functions defined in ima.c being moved to kexec.o be defined within a
>>>>> CONFIG_HAVE_IMA_KEXEC ifdef?
>>>>>
>>>>
>>>> Thanks for reviewing the changes.
>>>>
>>>> In "drivers/of/kexec.c" the function remove_ima_buffer() is defined
>>>> under "#ifdef CONFIG_HAVE_IMA_KEXEC"
>>>>
>>>> setup_ima_buffer() is defined under "#ifdef CONFIG_IMA_KEXEC" - the same
>>>> way it was defined in "arch/powerpc/kexec/ima.c".
>>>>
>>>> As you know, CONFIG_IMA_KEXEC depends on CONFIG_HAVE_IMA_KEXEC (as
>>>> defined in "security/integrity/ima/Kconfig").
>>>>
>>>> ima_get_kexec_buffer() and ima_free_kexec_buffer() are unconditionally
>>>> defined in "drivers/of/kexec.c" even though they are called only when
>>>> CONFIG_HAVE_IMA_KEXEC is enabled. I will update these two functions to
>>>> be moved under "#ifdef CONFIG_HAVE_IMA_KEXEC"
>>> The issue is the reverse. CONFIG_HAVE_IMA_KEXEC may be enabled without
>>> CONFIG_IMA_KEXEC being enabled. This allows the architecture to
>>> support carrying the measurement list across kexec, but requires
>>> enabling it at build time.
>>> Only if CONFIG_HAVE_IMA_KEXEC is enabled should any of these functions
>>> be compiled at build. This allows restoring the previous IMA
>>> measurement list, even if CONFIG_IMA_KEXEC is not enabled.
>>> Only if CONFIG_IMA_KEXEC is enabled, should carrying the measurement
>>> list across kexec be enabled. See how arch_ima_add_kexec_buffer,
>>> write_number, setup_ima_buffer are ifdef'ed in
>>> arch/powerpc/kexec/ima.c.
>>>
>>
>> Yes - I agree. I will make the following changes:
>>
>> => Enable the functions moved from "arch/powerpc/kexec/ima.c" to
>> "drivers/of/kexec.c" only when CONFIG_HAVE_IMA_KEXEC is enabled.
>>
>> => Also, compile write_number() and setup_ima_buffer() only when
>> CONFIG_IMA_KEXEC is enabled.
>
> Sounds good, with one additional change:
>
> So far, CONFIG_HAVE_IMA_KEXEC was tested only in files that were built
> when CONFIG_IMA was set. With this series this is not the case anymore
> (in drivers/of/kexec.c). The simplest way to keep this consistent is to
> only enable CONFIG_HAVE_IMA_KEXEC if CONFIG_IMA is also set.
>
> For example, with this:
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index e9f13fe08492..4ddd17215ecf 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -548,7 +548,7 @@ config KEXEC
> config KEXEC_FILE
> bool "kexec file based system call"
> select KEXEC_CORE
> - select HAVE_IMA_KEXEC
> + select HAVE_IMA_KEXEC if IMA
> select BUILD_BIN2C
> select KEXEC_ELF
> depends on PPC64
>
> And then the same thing on the arm64 patch.
This is a good idea Thiago - I will make this change in the Kconfig for
both powerpc and arm64.
thanks,
-lakshmi
next prev parent reply other threads:[~2020-12-23 5:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-19 17:57 [PATCH v13 0/6] Carry forward IMA measurement log on kexec on ARM64 Lakshmi Ramasubramanian
2020-12-19 17:57 ` [PATCH v13 1/6] ima: Move arch_ima_add_kexec_buffer() to ima Lakshmi Ramasubramanian
2020-12-22 14:22 ` Mimi Zohar
2020-12-22 22:53 ` Thiago Jung Bauermann
2020-12-19 17:57 ` [PATCH v13 2/6] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c Lakshmi Ramasubramanian
2020-12-22 14:26 ` Mimi Zohar
2020-12-22 18:53 ` Lakshmi Ramasubramanian
2020-12-22 19:45 ` Mimi Zohar
2020-12-22 21:02 ` Lakshmi Ramasubramanian
2020-12-23 0:40 ` Thiago Jung Bauermann
2020-12-23 5:03 ` Lakshmi Ramasubramanian [this message]
2020-12-23 0:19 ` Thiago Jung Bauermann
2020-12-23 5:01 ` Lakshmi Ramasubramanian
2020-12-23 17:57 ` Thiago Jung Bauermann
2020-12-23 0:48 ` Thiago Jung Bauermann
2020-12-23 4:56 ` Lakshmi Ramasubramanian
2020-12-31 22:28 ` Rob Herring
2020-12-19 17:57 ` [PATCH v13 3/6] kexec: Use fdt_appendprop_addrrange() to add ima buffer to FDT Lakshmi Ramasubramanian
2020-12-23 0:57 ` Thiago Jung Bauermann
2020-12-19 17:57 ` [PATCH v13 4/6] powerpc: Delete unused function delete_fdt_mem_rsv() Lakshmi Ramasubramanian
2020-12-23 1:08 ` Thiago Jung Bauermann
2020-12-23 5:09 ` Lakshmi Ramasubramanian
2020-12-19 17:57 ` [PATCH v13 5/6] arm64: Free DTB buffer if fdt_open_into() fails Lakshmi Ramasubramanian
2020-12-23 1:11 ` Thiago Jung Bauermann
2020-12-19 17:57 ` [PATCH v13 6/6] arm64: Add IMA log information in kimage used for kexec Lakshmi Ramasubramanian
2020-12-23 1:17 ` Thiago Jung Bauermann
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