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Subject: Re: [PATCH v14 6/6] arm64: Add IMA log information in kimage used
 for kexec
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        bauerman@linux.ibm.com, robh@kernel.org,
        takahiro.akashi@linaro.org, gregkh@linuxfoundation.org,
        will@kernel.org, catalin.marinas@arm.com, mpe@ellerman.id.au
Cc:     james.morse@arm.com, sashal@kernel.org, benh@kernel.crashing.org,
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        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,
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Date:   Tue, 12 Jan 2021 18:28:30 -0500
In-Reply-To: <20210104192602.10131-7-nramas@linux.microsoft.com>
References: <20210104192602.10131-1-nramas@linux.microsoft.com>
         <20210104192602.10131-7-nramas@linux.microsoft.com>
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Hi Lakshmi,

On Mon, 2021-01-04 at 11:26 -0800, Lakshmi Ramasubramanian wrote:
> Address and size of the buffer containing the IMA measurement log need
> to be passed from the current kernel to the next kernel on kexec.
> 
> Any existing "linux,ima-kexec-buffer" property in the device tree
> needs to be removed and its corresponding memory reservation in
> the currently running kernel needs to be freed. The address and
> size of the current kernel's IMA measurement log need to be added
> to the device tree's IMA kexec buffer node and memory for the buffer
> needs to be reserved for the log to be carried over to the next kernel
> on the kexec call.
> 
> Add address and size fields to "struct kimage_arch" for ARM64 platform
> to hold the address and size of the IMA measurement log buffer. Remove
> any existing "linux,ima-kexec-buffer" property in the device tree and
> free the corresponding memory reservation in the currently running
> kernel. Add "linux,ima-kexec-buffer" property to the device tree and
> reserve the memory for storing the IMA log that needs to be passed from
> the current kernel to the next one.
> 
> Update CONFIG_KEXEC_FILE to select CONFIG_HAVE_IMA_KEXEC to indicate
> that the IMA measurement log information is present in the device tree
> for ARM64.

Perhaps for some previous version of this patch set, this patch
description was appropriate, but for the code below it's kind of
overkill.

Mimi
> 
> Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> ---
>  arch/arm64/Kconfig             | 1 +
>  arch/arm64/include/asm/kexec.h | 5 +++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index a6b5b7ef40ae..312b4d5ad232 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1095,6 +1095,7 @@ config KEXEC
>  config KEXEC_FILE
>  	bool "kexec file based system call"
>  	select KEXEC_CORE
> +	select HAVE_IMA_KEXEC if IMA
>  	help
>  	  This is new version of kexec system call. This system call is
>  	  file based and takes file descriptors as system call argument
> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
> index d24b527e8c00..2bd19ccb6c43 100644
> --- a/arch/arm64/include/asm/kexec.h
> +++ b/arch/arm64/include/asm/kexec.h
> @@ -100,6 +100,11 @@ struct kimage_arch {
>  	void *elf_headers;
>  	unsigned long elf_headers_mem;
>  	unsigned long elf_headers_sz;
> +
> +#ifdef CONFIG_IMA_KEXEC
> +	phys_addr_t ima_buffer_addr;
> +	size_t ima_buffer_size;
> +#endif
>  };
>  
>  extern const struct kexec_file_ops kexec_image_ops;